List of submitted papers and abstracts that have been accepted for the presentation at the International Conference Power Plants 2012
Slavcho Neykov - Energy Community Secretariat - Vienna, Austria
Lecture / Presentation
Abstract
THE ENERGY TOPIC IN SEE
– HOW TO APPROACH AND WHY SPECIFIC?
Dejan Rebić - EU Delegation in Serbia
Lecture / Presentation
Abstract
EU ENERGY PROJECTS IN SERBIA
др Аца Марковић - председник УО ЈП ЕПС
Lecture / Presentation
Abstract
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Ljubo Maćić - Agencija za energetiku Republike Srbije
Lecture / Presentation
Abstract
-
Dragan Jovanović - TE-KO KOSTOLAC
Lecture / Presentation
Abstract
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Dr Miodrag Mesarovć - Energoprojekt Entel
Pages 1 - 13
Abstract
To generate eclectricity, power plants use both, non-renewable and renewable sources of primary energy, as well as other natural resources (water, limestone, etc.). Also, for their equipment and construction, different non-renewable natural resources are used, as well as the energy, generated also by the use of natural sources. Since the demand for electricity constantly grows, and natural non-renewable resources are finite, the principle of sustainable development means that power plants, besides environmental acceptability and energy efficiency, satisfy resource efficiency, which often are in conflict. In this report the consumption of natural resources and energy have been analysed for particular types of power plants based on both, non-renewable and renewable sources, extended to their overall life cycle. It was found that such an objective approach changes the accustomed ideas on particular types of power plants.
Djorji Biljanovski, Aleksandar Vlajčić, Predrag Jovanović, Vladimir Koković - PD TENT, SKF
Pages 14 - 14
Abstract
Reaching higher efficiency and reliability in electric energy production by implementation of Asset Efficiency Optimization process
Starting with increasing requirements for efficient energy production and security of energy supply in Serbia and South East Europe, business plans and KPIs of TPP "Nikola Tesla", paper presents Asset Management Improvement projects, in order to achieve either same level of production and decrease costs, or to increase production maintaining costs on the same level.
Počevši od povećanih zahteva za efikasnom proizvodnjom električne energije i sigurnim snabdevanjem energijom u Srbiji i Jugoistočnoj Evropi, planova poslovanja i ključnih pokazatelja uspešnosti Termoelektrana "Nikola Tesla" u radu su predstavljeni projekti za unapređenje upravljanja osnovnim sredstvima u cilju postizanja istog nivoa proizvodnje uz smanjenje troškova ili povećanje proizvodnje uz zadržavanje troškova na istom nivou.
Volker Schuele - Alstom Power GmbH - Integrated Solutions , Dirk Renjewski - Alstom Power GmbH - Integrated Solutions , Olivier Clement - Alstom Power GmbH - Integrated Solutions , Fabian Bierewirtz - Alstom Power GmbH - Integrated Solutions
Pages 15 - 24
Abstract
The existing Power Generation fossil fuel assets have, in many cases, hidden capacity due in part to the conservative nature of their original design. In order to release these hidden reserves and maximise the Plant performance, Alstom Power has developed a suite of products which improve emissions control, output and heat rate.
To quantify the potential improvement the first step is a Plant assessment in which the condition of the Plant is assessed alongside the opportunities for improved performance. Many options can be presented to the Plant owner. In this paper we look at 3 specific products:
- Cold End Performance. This offers the possibility to improve the efficiency and capacity of existing plants based on an holistic methodology and system approach to optimise the LP-turbine, condenser and cooling water system to achieve a greater cumulative benefit.
- Steam Temperature Control. By improving the control and measurement accuracy of the live and reheat steam temperatures the plant efficiency can be increased. This reduce measurement errors and maintains stable control thereby removing the need for contingency margins.
- Heat Recovery System. One of the most significant losses impacting performance is the low grade heat released to the atmosphere in the flue gas. By the addition of an extra heat exchanger upstream of an ESP the plant efficiency and output can be increase and with low sulphur coals with the added benefit of a reduction in particulate emissions. A system approach is essential to ensure the successful integration of the heat exchanger within the existing Plant and to maximise the combined benefits of improved performance and emissions reduction.
Upgrading of existing plants is a cost effective means of increasing Plant performance and releasing the hidden potential of a conservative original design. By using an integrated system approach these benefits can be maximised and the full potential of the Power Plant Assets realised.
Hellmuth Brueggemann - ALSTOM Boiler Deutschland GmbH , T. M. Marling - ALSTOM Boiler Deutschland GmbH
Pages 25 - 34
Abstract
The discussion on world climate change and efficient power generation requests for advanced firing systems and burners. Since renewable energy sources will be further utilized in power generation, new fossil-fired power stations need to be flexible from very low loads to full load, as they are to compensate the difference between power demand and power generation. Furthermore, new hard coal and lignite-fired power stations will have to burn biomass in order to reduce their CO2 footprint from coal combustion. In this report the achievements of the development of advanced and flexible firing systems and burners to cope with future needs will be addressed. These burners as fixed burners as well as tilting burners have the clearly defined objectives to utilise a wide fuel range with low emissions, without slagging and high availability in all operation modes. Through consequent use of return of experience from new power projects as well as retrofitted units the proven jet burner technology could be further developed. The improvements enable the new power plant fleet, currently under execution in Germany and Europe, to operate with the most advanced and environment-friendly burner technology and to fulfil their future tasks.
Dr. Christian Storm, Dr. Bernhard Pinkert, Dr. Stefan Hamel - Babcock Borsig Steinmüller GmbH, Oberhausen, Germany
Pages 35 - 46
Abstract
The paper presents a modernization project of a T-type steam generator into a state of the art firing system including a lifetime extension. The total capacity of the Power Plant, which consists of 3 units, is 675 MW. Raw lignite from different mines in the surrounding area is used as fuel.
The majority of the components of the original power plant equipment were supplied by Russian manufacturers. The units of the power plant essentially consist of the following:
steam generator
- Steam turbine, generator and auxiliary equipment
- Flue gas dedusting using electrostatic precipitators, flue gas ducts
- Suction draught fan and a common stack for Units 1 and 2 and a stack for Unit 3
- Natural passage cooling tower
- Oil storage and supply station
- Two coal supply systems
- Three systems of internal pneumatic ash disposal, including storage
- Auxiliary facilities
The main focus of the modernization is the reduction of the CO and NOx emissions. This is achieved by primary measures. Simultaneously, it is necessary to replace some significant components of the pressure parts. As an additional result an increase of plant availability is achieved.
With the modernization, the following aims are to be realized:
- Reduction of emissions according to EC Directive 2001/80/EC
- Increase of the pressure part’s operating life to further 120,000 operating hours
- Increase of the boiler efficiency
- Realization of boiler operation with n-1 mills at nominal capacity
- Increase of availability
The modernization works mainly include the following:
- Installation of new pulverized coal burners, pulverized coal ducts, and classifiers
- Installation of a burnout air system (2 OFA levels)
- Modification and new construction of hot air ducts including the required measuring devices
- Installation of a grate (tip grate)
- Modernization of the regenerative air preheater
Babcock Borsig Steinmüller GmbH designs and executes the works to meet the objectives.
A new firing system will be implemented in order to comply with the emission limits and to improve combustion stability. Intense CFD-studies have been performed to evaluate the design of burners and burner arrangement and to implement the optimized solution for a low-emission retrofit.
Dr. Georg Gasteiger, Dr. Bernhard Pinkert, Dr. Christian Storm, Frank Adamczyk - Babcock Borsig Steinmüller GmbH, Oberhausen, Germany , mgr inż. Krzysztof Matyskiewicz - PGE, Belchatow, Poland
Pages 47 - 58
Abstract
Most of the power plants in Eastern Europe are 25 to 45 years old. The Eastern European countries are obliged to fulfill the European Guidelines to reduce the emissions on air pollutants and dust. Under consideration of the remaining lifetime of pressure parts and the requirements regarding the environmental protection tmodernisation is an alternative to the construction of new power plants.
Units 1-12 of power plant Bełchatów were built between 1978 and 1988. The original units were identically equipped and their unit capacity amounts to 370 MW each. At the time of completion total power reached a capacity of 4,320 MW. Since then it is the largest lignite-fired power plant location in Europe and one of the largest worldwide.
Until now the power plant has been fed up by coal from the open-cast mining of Klesczów. The annual consumption amounts to appr. 34 million tons of coal. A modernisation had become necessary on basis of an operation period longer than 150,000 hours. The change of some pressure parts is required latest after 200,000 hours. Additionally Poland is obliged to fulfill the European Guideline 2001/80/EG to reduce the emission of air pollutants.
Due to the large expense of modernisation the owner PGE decided to implement measures to increase the efficiency as well. The measures were elaborated on basis of extended studies.
The retrofit works were subdivided into different lots. This led to the special situation that all partners were obliged to the objectives of modernization. In addition to the measures on the steam generator the main works included:
- The modernisation of the steam generator
- The modernisation of the firing system
- The modernisation of the steam turbine
- The exchange of HP and IP steam pipes
- The modernisation of the regenerative air preheaters
- The modernisation of the ESP
- The installation of a new I&C system
- The compliance of emission guidelines
Wieslaw Zablocki - RAFAKO S.A. , Krzysztof Burek - RAFAKO S.A.
Pages 59 - 67
Abstract
The paper presents 2 x 900MWe supercritical unit project to be built at PGE Opole Power Plant. The turn-key contract of ca. 2.4 billion EUR net between consortium of RAFAKO (leader) / Polimex–Mostostal / Mostostal Warszawa and PGE was signed on February 15, 2012. The Opole units will follow other supercritical units built in Poland: 464MWe at Patnów Power Plant, 460MWe at Łagisza Power Plant and 858MWe at Bełchatów Power Plant. New Opole power generation units will be of high steam parameters (597 °C / 609 °C / 275 bar / 5.8 bar), thus resulting in high unit efficiency of 45.5%. The units will also fulfill very stringent emission level requirements (regarding SO2, NOx, dust, noise).
Main Project milestones:
- NTP – 6 ÷ 12 months from the contract conclusion,
- 54 months from NTP – PAC for Unit 5,
- 62 months from NTP – PAC for Unit 6.
Frank Oberheid - D-PM1 - Doosan Lentjes GmbH
Pages 68 - 84
Abstract
Presentation content:
- Company Introduction and History
- Pollutants in Focus
- Emission Limits
- Economical Aspects of Retrofit
- Desulphurisation Technologies
– Wet Lime/Limestone FGD
– Dry CFB FGD
– Comparison
- Selected Retrofit References
Wolfgang Apelt - Vattenfall Europe PowerConsult GmbH, Germany , Ronald Rost - Vattenfall Europe PowerConsult GmbH, Germany
Pages 85 - 130
Abstract
This presentation informs about the development and actual status of Vattenfall’s lignite-fired 675 MW unit Boxberg R which is currently in the final commissioning stage and about the hardcoal-fired 2 x 820 MW Moorburg project which is under construction. Each project will be presented with its major design parameters with special focus on site characteristics, plant efficiency and stack emissions. Energy efficiency measures will be compared with best available techniques. The project and engineering management will be outlined and the construction progress illustrated.
Piotr Czerwinski - ALSTOM Power sp. z o.o. w Warszawie
Pages 131 - 159
Abstract
The concept of retrofitting steam turbines has now become well established as a recognized solution for improving the performance and reliability of existing power plants.
However, the diversity of plant owners' original equipment, changing power market conditions, environmental requirements and plant integration opportunities requires suppliers to be able to continually develop and innovate in order to offer highly bespoke solutions that maximize the benefits of a retrofit, delivering successful projects to the customers.
The presentation will provide an insight into the possibilities and opportunities that retrofitting can provide.
The presentation will cover the following issues (agenda items):
- typical drivers for modernization of existing steam turbines
- major constraints for retrofit projects
- possible retrofit solutions ranging from upgrades up to integrated retrofits
- economic evaluation of different retrofit solutions (NPV, IRR, payback time) basing on some examples (with sensitivity analysis)
- conclusions.
As we are interested now in retrofitting of three 200 MW LMZ turbines, all examples will be given for this type of turbine.
Volker Schuele - Alstom Power GmbH - Integrated Solutions , Dirk Renjewski - Alstom Power GmbH - Integrated Solutions , Olivier Clement - Alstom Power GmbH - Integrated Solutions , Fabian Bierewirtz - Alstom Power GmbH - Integrated Solutions
Pages 160 - 169
Abstract
Responding to world environmental concerns, the share of renewables is increasing in the energy mix especially in Europe. Several countries are supporting this process through subsidies or feed in tariff mechanisms. Nowadays a necessity for power plant operators, the integration of this energy source is a real challenge and has a strong impact on the operation of existing fossil power plants.
Based on this, two potential approaches can be of value for the operator. The most logical one is to increase the operational flexibility of the power plant in terms of spinning reserve and back-up capacity (load gradients, technical minimum load, etc) in order to balance the renewable energies output fluctuations. Another option can be the integration of a renewable energy source directly into an existing power plant. This arrangement allows the plant to balance the fluctuating power output with its thermal and mechanical inertia.
For a successful and most cost effective project of both options, an integrated approach is proposed as this has advantages over a component approach. To incorporate new technologies without an integrated approach and a full review of the affected systems can lead to a less than optimum solution with unexpected surprises when the unit is returned to service.
Alstom Power has developed Plant Product solutions that improve the flexibility and the environmental impact of the entire power plant. In this paper, we describe 2 different integrated options:
The Solar Boost approach generates renewable power by using concentrating solar thermal equipment and integrating the heat in the waters-steam cycle of an existing steam unit. The integration in the existing steam unit has been optimized to achieve high efficiency and low investment costs and minimizing the risks for the existing steam unit.
The Peak Power technology is able to supply overload power or to reduce the minimum power output by means of heat storage. This heat will be loaded and unloaded from/to the water steam cycle. It allows a high degree of operational flexibility and even gives the possibility to reduce power limitations due to the supply of frequency support.
Adapting existing plants is of high importance today and by using an integrated approach with innovative products this will lead to more operational flexibility and emission reduction of the Plant while controlling O&M maintenance cost.
Dr.-Eng. Daniel Seibt - Vattenfall Europe PowerConsult GmbH, Germany , Ronald Rost - Vattenfall Europe PowerConsult GmbH, Germany
Pages 170 - 215
Abstract
The usage of biomass and waste in existing power plants is a good possibility to reduce the CO2 footprint, make most efficient use of those fuels and contribute to an economic plant operation. This presentation informs about Vattenfall activities for the usage of woody biomass and of residue derived waste in existing power and CHP plants. Biomass co-firing with general aspects and project specifics will be highlighted on example of a 240 MWth fluid bed boiler. Special consideration will be given to logistical aspects in a city like Berlin. The second part of the presentation informs about Vattenfall’s experiences in the usage of waste, which will be explained for the Jaenschwalde lignite power plant.
Pascal FONTAINE - CMI Energy , Xavier Dhubert - CMI Energy
Pages 216 - 228
Abstract
In the Balkan and Central Europe, there is a large fleet of older oil & coal fired power plants with a potential for repowering into modern combined cycle power plants. This paper will review the specific HRSG design features required for such repowering projects. Compared to green field projects, repowering a steam turbine with a new train of gas turbine and HRSG includes some special challenges. The HRSGs have to be tailor made to suit the existing site constraints. We will explain how a Vertical type HRSG can be adapted and modelled to match a limited foot print. In addition we will present the specificities of the design of HRSGs when the Gas Turbine fires heavy fuel oil, as mandatory in some projects. CMI has recently completed such a large repowering projects, for instance Senoko Singapore; Dunamenti Hungary, Shoiaba/SEC/ Saoudi Arabia, … These experiences will be the support throughout this paper to explain these specific repowering challenges
Tobias Bönsel, Dr.Rolf Graf , Bogusław Krztoń - Foster Wheeler Graf Wulff GmbH, Germany
Pages 229 - 240
Abstract
Tightening environmental regulations are lowering the requirements for emissions from power plant and industrial facilities around the world. Newer, stricter standards are being required by more governments for pollutants that are already being regulated—SOx, NOx and particulate matter. In addition, metals, acid gases, and organic compounds are setting requirements for flue gas cleaning systems. USA’s EPA Mercury and Air Toxics Standards (MATS) rule enacted in December 2011 and the upcoming IED requirements become completly in force by January 2016 in Europe. Due to the new requirements for flue gas acids like SOx,HCl, HF, dust and many other multi-pollutants, owners of coal fired,oil fired and waste fired power plants are continuously evaluating the merits of adding back-end air quality control systems (AQCS).
This paper takes a special focus to the first operation experiences of Basin Dry Fork station project, which entered in commercial operation 2011, featuring best available dry flue gas scrubbing technology (BAT) for the first time worldwide in single unit size for a 420 -450MWe coal fired boiler plant. It will be shown how the technology is able to meet the strict emission requirements and even more. Furthermore, experiences from an oil-fired refinery boiler in Europe taken into operation in Jan.2012 are highlighted.
The dry technology of Circulating Fluidized Bed Scrubbing (CFBS) is a viable pathway for addressing multi-pollutant control in a cost effective manner. Combining lime hydration and storage equipment, a circulating fluidized bed upflow reactor/absorber and downstream fabric filter, all CFBS system equipment can be installed in one building or outdoor. Construction costs can be reduced as the major system components can be pre-assembled on the ground and lifted into place during system erection.The technology provides high pollutant removal efficiencies up to 99% for SO2, SO3, HCl and HF. Further on the absorber/fabric filter arrangement is highly adaptable for sorbent injection for removal of heavy metals including mercury.
Ana Stanić - English Solicitor, E&A Law and Visiting Professor of Energy Law at CEU, Budapest
Pages 241 - 241
Abstract
This paper will discuss the package of new rules concerning energy infrastructure proposed by the European Union Commission in October last year and its implications for the region of South East Europe. In particular, it will (i) outline the Commission’s proposal for a Regulation on the guidelines for trans-European energy infrastructure, (ii) examine the SEE projects currently being considered to be included as EU priority projects as part of the Regulation and (iii) the work being done by the Energy Community to integrate the energy markets of the SEE into that of the EU.
prof.dr.Miroslav Benišek - University of Belgrade, Mechanical Engineering Faculty, Belgrade, Serbia
Pages 242 - 254
Abstract
After lasting several decennium of Serbians hydropower station operation the significance reconstructions were performed or the significance reconstructions will be performed. In the assemble of voluminous works, which have to lead to expected reconstructions results, the model tests take the important place. The turbine model on the quality test bed, also using the best quality of instrumentation which provide the high accuracy, in the preferable independent laboratory is performed. The obtained universal model hill charts can be recalculate on the prototype hill chart which confirm the desired turbines characteristics. In this paper the next applied procedures will be presented: production of model preparation and test bed constructions, measurements methods universal hill chart, scale up calculation from model to prototype. All procedure by model tests whose were carried out on HPS Djerdap 1, HPS Djerdap 2 and HPS Bajina Bašta are presented.
Apstrakt
Nakon višedecenijskog rada većih srpskih hidroelektrana sprovedeni su ili se sprovode značajni zahvati rekonstrukcija.U sklopu obimnih poslova koji treba da dovedu do očekivanog ishoda rekonstrukcija hidroelektrana u cilju modernizacija i povečanja snaga, važno mesto zauzimaju i modelska ispitivanja projektovanog tipa turbine od strane renomiranog i na tenderu izabranog proizvođaća. Ispitivanja turbina se vrše na visoko sofisticiranim opitnim instalacijama u neutralnim laboratorijama, koja treba da obezbede visoku tačnost merenja. Dobijene univerzalne karakteristike modela se preračunavaju na eksploatacione karakteristike prototipa velike turbine , na osnovu kojih se utvrdjuje valjanost turbine.
U radu će biti prikazani postupci koji se primenjuju: izrada modela turbine, priprema i izgled opitnih instalacija, metodologija ispitivanja, dobijanje univerzalnih karakteristika, postupci preračunavanja sa modela na prototip... Sva razmatranja biće prikazana na primerima modelskih ispitivanja koja su sprovedena u cilju rekonstrukcija HE Djerdap 1,HE Djerdap 2 i HE Bajina Bašta.
Slobodan Milić and Ana Krička - Energoprojekt Entel
Pages 255 - 264
Abstract
All the existing hydroelectric power plants in Serbia are over 30 years old, some over 50 years. Unavoidable activity that should enable their further operation is refurbishment of their equipment, particularly energy the chain turbine-generator-transformer. The logic of the technological advancement and ever increasing demand for energy and capacity imperatively put the obligation to increase the capacity and production at least within the space limits of the existing equipment. On the other hand, refurbishment requires a one year long shut-down of the power plant, which causes a loss of power and energy and therefore intention is to shorten the duration of the shut down. By the installation of an additional turbine-generator set of the same or smaller dimensions, where this is technically possible, it is possible to reduce the losses during refurbishment and to increase the capacity and production after the refurbishment. Particularly important, with regards to the lack of power and energy during a long time, are the effects during refurbishment. It has been demonstrated that an additional turbine-generator set operating during the refurbishment generates incomes which enables repayment of about 70% of the investment value. In this article as an example, presented are the approach and analysis related to an additional turbine generator set in the Potpeć hydro electric power plant.
Z. Kovačević, M. Spasojević, A. Ostojić, S. Milić - 1Energoprojekt-Hidroinženjering, Energoprojekt Entel
Pages 265 - 278
Abstract
This paper presents the one-dimensional model of unsteady flow in HPP Iron Gates 1 and 2 reservoirs, caused by the combination of both HPP regimes and natural waves entering reservoirs. The model results are used as basis for energy production analysis. The area modeled includes the Danube River between the gauging station Lom (rkm 743+300) and the city of Novi Sad (rkm 1254+150), the Sava River between its mouth (rkm 0+000) and the city of Sabac (rkm 102+850), the Tisa River between its mouth (rkm 0+000) and the city of Novi Becej (rkm 62+350), as well as the mouth areas of smaller tributaries of the Danube (Tamis, Velika Morava, Mlava, Nera, Pek, Porecka, and Timok) and the Sava (Kolubara). The model includes the HPP Iron Gates 1 structure, as well as both HPP Iron Gates 2 structures, one on the Danube River, and the other on the Gogos side channel. The model’s domain is split into three subdomains, the first one covering area upstream from the HPP Iron Gates 1, the second one covering area between HPP Iron Gates 1 an HPP Iron Gates 2, and the third one covering area downstram from the HPP Iron Gates 2. The model’s formulation, calibration, and verification are based on existing bathymetric, discharge, and free-surface elevation data. The model is based on the HEC-RAS program.
M. H. Benišek and I. O. Božić - University of Belgrade, Faculty of Mechanical Engineering
Pages 279 - 287
Abstract
Hydraulic turbines’ energy characteristics have been determined by model tests in laboratories and then recalculated to prototype characteristics. Some of the most significant scale-up formulae for dimensionless total hydraulic losses recalculations are given chronologically in this paper. In addition, according to the rare and valuable experimental results of four different dimension models and a prototype of geometrically similar Kaplan turbine, the novel relation of dependency between total hydraulic losses and turbine Reynolds numbers for optimal operation regimes is obtained. Based on this relation, a new scale-up formula is proposed by the authors.
Dane D. Džepčeski, Slobodan S. Bogdanović, Dušan B. Arnautović, Vladimir S. Stanojčić, Jelena S. Pavlović - Electrical engineering institute „Nikola Tesla“ a.d., Koste Glavinića 8a, Belgrade, Serbia - Member of University of Belgrade , Dušan M. Trišić, Boris V. Jovanović - PD „Drinsko-Limske hidroelektrane“, Trg Dušana Jerkovića 1, Bajina Bašta, Serbia
Pages 288 - 296
Abstract
In this paper test results of characteristics and parameters of an turbine governing system of one hydro power unit, when unit operates in primary frequency control, are presented. Test results were taken over from the report of testing that was carried out for the needs of power system operator, that is for provider of system service of grid frequency control. Short overview of characteristics and parameters of turbine governing system is shown side by side with test results in order to provide better background for presentation and interpretation of these results. Test results are presented together with criteria defined in current standards and policies that refer to the primary frequency control. Test preparation and testing procedures are described. The results are processed in such a way as to enable their comparison with the corresponding test results obtained from any other unit.
Apstrakt
U radu su prikazani rezultati ispitivanja sistema turbinske regulacije jednog hidroagregata prilikom rada agregata u primarnoj regulaciji učestanosti. Kroz prikaz rezultata ispitivanja opisani su poredbeni kriterijumi koji su definisani u važećoj regulativi i standardima koji se odnose na oblast primarne regulacije učestanosti. Primenjenom metodologijom ispitivanja i analize dobijenih rezultata pokušano je određivanje opšteg pristupa koji omogućava jednostavno poređenje kvaliteta učešća ispitivanih agregata u primarnoj regulaciji učestanosti. Svi prikazani rezultati preuzeti su iz rezultata ispitivanja koja su vršena za potrebe realizacije eksperimentalnog dela studije „Sistemski parametri regulacije pobude i turbinske regulacije u elektranam EPS-a“.
Miodrag Arsić*, Srđan Bošnjak**, Bojan Međo*** , Meri Burzić****, Brane Vistać*, Zoran Savić* - *Materials Testing Institute, Bulevar vojvode Mišića 43, Belgrade **Faculty of Mechanical Engineering, The University of Belgrade, Kraljice Marije 16, Belgrade ***Faculty of Technology and Metallurgy, The University of Belgrade, Karnegijeva 4, Belgrade ****Innovation Center of the Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade
Pages 297 - 306
Abstract
Horizontal Kaplan turbines, made in Russia, were built in 10 hydro-electric generating units at „DJERDAP 2“. Nominal power of each is 28 MW. Taking into account the fact that fatigue started to occur at many components and structures of turbine and hydromechanical
equipment, the researches have been conducted regarding the influence of the loading regime, operational environment and type of damage to the service life of equipment components. After 163.411 hours (approximately 22 years) the collapse of the hydro-electric generating set A6 turbine shaft in the area of high stress concentration occurred, at the transition radius R80 between the flange and the runner hub. Turbine shaft has been designed as a welded structure of the cylindrical body of the hollow shaft and the flange, while the estimated service life for it was 40 years. It was made of cast steel 20GSL, according to GOST 977-88.
In this paper the results of the analytical calculation regarding the strength of the turbine shaft are presented, taking into account high stress concentration and influence of the corrosive environment, as well as results of experimental tests regarding the fatigue of shaft material. Standard tensile tests under constant amplitude loading were carried out on smooth specimens in order to determine fatigue properties of the base material, as well as bending tests on notched specimens, in accordance with the standard ASTM E399, in order to determine fracture mechanics parameters or correlation between the crack growth rate and the stress intensity factor.
Through an analytical calculation it was established that value of bending stresses that act on the turbine shaft and occur due to fatigue, corrosion and stress concentration factors is higher than 25 MPa for flanges exposed to water, as well as higher than 40 MPa for flanges exposed to "corrosive water" and protected by epoxy fibres, and can cause the occurence of surface cracks on the transition radius between the cylindrical part of the shaft and the flange. It has been established that stress values in the area under the influence of bending stresses were higher than allowable values, which led to the occurence of many cracks due to fatigue corrosion. One of those cracks caused the fracture of the shaft and of the whole turbine by its stable or unstable growth.
A comparison of a number of loading cycles until the critical length of the crack was reached, determined on the basis of the dependency between the crack growth rate and the stress intensity factor (Nk = 2.78 x 106), as well as on the basis of the number of loading cycles until the occurrence of shaft fracture after 163.411 hours of turbine A6 operation with a frequency of 1,04s-1 (N=63x109), showed that anti-corrosion protection slowed down the process of formation of initial cracks.
Nemanja Milojčić, Dušan Arnautović, Zoran Ćirić, Đorđe Stojić, Slavko Veinović, Predrag Ninković, Mladen Ostojić, Blagota Jovanović, Rajko Prole, Dane Džepčeski, Marko Janković, Tomislav Gajić, Dušan Joksimović, Mladen Milošević, Milan Milinković, Jelena Pavlović, Jasna Dragosavac, Vladimir Stanojčić - Electrical Engineering Institute "Nikola Tesla" - University of Belgrade, Belgrade, Koste Glavinica 8a
Pages 307 - 313
Abstract
In this paper integrated system which is developed for micro, mini and small hydropower plants is presented. The system is complete and uniform set of equipment which can be adapted to different unit powers and different configurations of the main and auxiliary unit equipment in the HPP. Main parts of the system are: LV AC distribution panel, DC distribution panel with rectifier, central control system for main unit and auxiliary equipment, excitation system, turbine governor, synchronizer and electrical protections system. Implemented part of the system and equipment on the 200 kVA unit in mini HPP "Moravica" - Ivanjica are described.
Apstrakt
U radu je predstavljen razvijen integrisani sistem za upravljanje radom mikro, mini i malih hidroelektrana. Sistem predstavlja jedinstvenu celinu koju čini oprema koja se lako može prilagoditi za različite snage hidroagregata i konfiguracije glavne i pomoćne opreme u hidroelektrani. Osnovni elementi sistema su: niskonaponski naizmenični razvod napajanja, jednosmerni razvod napajanja sa ispravljačem, centralni sistem upravljanja agregatom i pomoćnom opremom, sistem pobude agregata, sistem turbinske regulacije, sinhronizator i sistem električnih zaštita agregata. Dat je opis dela sistema i opreme koja je instalirana u MHE "Moravica" - Ivanjica na hidroagregatu snage 200 kVA.
Saša Dragoljub Milić - Electrical Engineering Institute Nikola Tesla, University of Belgrade, Belgrade, Serbia , Nebojša Karanović, Zoran Kršenković - CE Djerdap Hydroelectric Power Plants Ltd. Serbia
Pages 314 - 321
Abstract
In this paper we propose a novel laser monitoring system of vessel detection in the lock of hydropower plant Djerdap on Danube river in Serbia. The lock consists of one chamber and top and bottom gates. The proposed monitoring system is a stand-alone class, based on remote laser detection of vessel in the area of gates at both ends of the lock. The system is useful for continuous remote monitoring without interruption water transport. It consists of following parts: four laser sensors (two sensors per gate), two programmable logic controllers, alert device and industrial computer with a few application softwares, database and interface for connection to SCADA. The communication among system parts is done by optical network with appropriate active and passive network components. The paper describes in detail the monitoring concept, placement and routing of sensors and a computer program which performs object detection in the visual field of laser sensors. This monitoring system has a vital role in keeping water transport operations safe, preventive maintenance and avoidance of vessel damaging in the area of gates at both ends that control level of water in the chamber.
Marko Janković, Predrag Ninković, Sava Dobričić, Tomislav Gajić, Jasna Dragosavac, Žarko Janda - Electrical Engineering Institute “Nikola Tesla”
Pages 322 - 331
Abstract
Small hydropower (SHP) is one of the most appropriate options to meet increasing energy demand especially in a country like Serbia, where a significant power potential in this sector is available. It is clean and renewable in contrast to fossil fuel based generations which pollute the environment and whose resources are depleting fast. However, high cost per unit generation is a constraint in case of SHP development. So, cost effectiveness is very important factor in SHP development. Control and operation system for SHP should be simple, reliable, cheap and with minimum interference of operating personal. Control system should be such that remote operation can be performed easily. The main functions of the controller for SHP automation is to execute starting and the shut down sequences under normal and emergency conditions. In addition to these operating sequences, certain control actions like speed control for synchronization and speed control when the machine is put on the grid are also to be performed for frequency control and load sharing. The excitation system should respond with respect to the system requirement that is either to control the voltage or to share the reactive power with the other units operating in parallel. Functions other than control like continuous monitoring, data recording, instrumentation and protections should also be performed. The main goal of the development of such equipment is to support a strong trend in Serbia to direct the investments in energy toward local companies. The basic idea is to use imported hardware only in the case when the cost of the development of domestic equipment is much higher. Complete software and specially dedicated hardware, which has the larger share of costs, is develloped by domestic companies. From the maintenance point of view, it is important to have local maintenance staff available. The control of local processes at the level of primary equipment is realized in the framework of distributed devices. These devices, at hardware and software level are fully product of Serbian experts. So, not only that the investment funds remain in Serbia, but professionals are educated and became experienced in working with modern equipment. The device is equipped with modern devices for on-line monitoring and diagnostics of synchronous machines and network conditions. Consequently, the synthesis of the respective control actions can be performed in an attemt to integrate these SHP in incoming smart grid network. Smart power generation is a concept of matching electricity production with demand using multiple generators which can start, stop and operate efficiently at chosen load, independently of the others, making them suitable for base load and peaking power generation. Matching supply and demand, called load balancing, is essential for a stable and reliable supply of electricity. The load balancing task has become much more challenging as increasingly intermittent and variable generators such as wind turbines and solar cells are added to the grid, forcing other producers to adapt their output much more frequently than has been required in the past.
Dejan Mandić, Milan Ćalović and Slobodan Milić - Energoprojekt Entel
Pages 332 - 344
Abstract
The problem of large commercial storage of electrical energy during low demand hours and its utilization in high demand hours presents, for a long time, one of the long lasting challenges for the professionals in the operations and planning of modern power systems. With the short summary of presently available and used storing technologies, this paper puts the main attention to the problem how to use pump storage (reversible) hydropower plants for the conversion of excessive electric energy in low-load periods to the high value hydro energy storage to be used for the generation of electric energy in high demand hours, through the cycles of turbine generation regime within the same hydroelectric power plant. The paper presents the short summary of the construction of such power plants in the world and in Serbia, as well as presently used technological solutions. Also, it it lists the main operating parameters of pumping storage hydroelectric power plants and discusses their role in modern power systems. Based on such analyses, it was possible to define economic and energy effects, with an aim to valorize their operation characteristics and possible economic effects. The procedure of the valorization is illustrated on the example of of operation of pump storage hydroelectric plant Bistrica within the open market of electric power system of Serbia (EPS), by emphasizing the mandatory procedure that should be followed within the process of decision-making in the planning phase of any reversible hydroelectric power plant.
Milan Ivanović, Sanja Ivković, Dragan Dabić, Nikola Georgijević, Dragan Popović - Electrical Engineering Institute Nikola Tesla, Koste Glavinića 8a, Belgrade
Pages 345 - 352
Abstract
In this paper, an overview of the preliminary results, obtained within Digsilent PowerFactory is given. Digsilent PowerFactory have been used as reference program for validating models used for the study "System parameters of excitation and turbine control for power plants in the EPS". Objective of the study is to capture, analyze and adjust the relevant parameters of the excitation and turbine control systems for all plants within EPS. The final objective is to improve the quality of regulation, to provide reserves for primary, secondary and tertiary frequency control and to provide resources for generation and absorption of reactive power for the primary voltage control. For the study, model of southeast Europe power system has been created in the DINST software, developed in the Electrical Institute Nikola Tesla. As a referent program, Digsilent PowerFactory has been used. In the paper, comparative results of measurements and simulations of the response voltage regulator on a stepping change of the reference voltage.
Vojin Kostić - Elektrotehnički institut „Nikola Tesla”, Univerzitet u Beogradu, Beograd , Dragutin Salamon - Elektrotehnički fakultet, Univerzitet u Beogradu, Beograd, Srbija , Aleksandar Pavlović, Saša Milić - Elektrotehnički institut „Nikola Tesla”, Univerzitet u Beogradu, Beograd
Pages 353 - 360
Abstract
U radu je dat prikaz poboljšane U-I metode za merenje impedanse sistema uzemljenja. Sistemi uzemljenja imaju veoma važnu ulogu tokom normalnog režima rada i tokom perioda trajanja kvara u elektroenergetskom sistemu. Prema važećim propisima obavezno je vršiti periodična ispitivanja sistema uzemljenja da bi se procenila bezbednost ljudi i opreme u periodu normalnog rada i prilikom kvarova. Nedostatak dosadašnjih merenja je što se u velikim elektroenergetskim objektima (termoelektrane, hidroelektrane) nisu mogle izbeći velike smetnje koje su ponekad bile veće od stvarne vrednosti merene pojave. Modifikacijom postojeće metode merenja moguće je izbeći navedeni problem.
Abstract:
This paper presents improved U-I method for the earthing system impedance measurement. Earthing systems have important part during normal operatning mode and during earth fault condition in power system. According present regulations inspections of earthing systems are obligately in aim to evaluate safety of people and equipment during normal operatning mode and during earth fault condition. Absence of present measurements in large power system objects (thermo and hydro power plants) is interference value which is higher then the thru measurement value. Modification of existing method can avoid foregoing problem.
Key words: earthing system impedance, measurements, interference, modificated method
Vladimir Đ. Vukić - Institute of Electrical Engineering “Nikola Tesla”, University of Belgrade, Belgrade, Serbia
Pages 361 - 371
Abstract
Results were presented on examinations of two valve-regulated lead-acid (VRLA) batteries AGM SVT 300 after six-year exploitation in two industrial systems of uninterruptible power supply. Batteries of the same type, with the nominal service life of twelve years, operated with similar load and the number of cells, but in various temperature conditions. Battery B1, operating without a proper air-conditioning for a long time, expressed failure of three battery cells (out of total 106). These failures were followed by significant characteristic degradation of another four cells after completion of the charging process of the previously deeply discharged battery. Due to the abrupt degradation of the battery B1 characteristics, it was concluded that its replacement with the new battery was necessary. In the case of the battery B2, exploited with good air-conditioning, characteristics of the 100 battery cells (out of total 102) were spotless during the discharge of the 80% of nominal capacity, as well as during the following charging. From two cells from the battery line, not being from the same batch as the remaining hundred cells was discharged only 30% of the nominal capacity. At the beginning of the charging process of battery B2, the voltage of the two weak cells rose up to 2.55 V, in order to nearly achieve equalization of all the 102 cells in the battery circuit at the end of the charging process. It was estimated that battery B2 might remain in exploitation for a long time, with the eventual replacement of two weak cells. Voltage variations of the weak battery cells were analyzed, as well as their failure mechanisms. Implemented procedure for equalization of the VRLA battery’s cells after accomplishing charging process was described. A practice of batteries operation with rectifiers that would enable their operation during the entire declared service life was proposed.
Vladimir Đ. Vukić - Institute of Electrical Engineering “Nikola Tesla”, University of Belgrade, Belgrade, Serbia
Pages 372 - 381
Abstract
In the paper the upgrade procedure for high-power thyristor rectifiers in the thermal power plant “Nikola Tesla A” is described. According to the user request, a reconstruction of the existing rectifiers is performed, in order to increase the robustness of the power plant uninterruptible direct current power supply system. Originally, thyristor rectifiers were not designed for operation without batteries. Nevertheless, battery is not completely reliable and not in every situation stable source of direct current. Both temporary or permanent battery faults may be affected by a number of causes, starting with battery fuse reaction, then increase of the intermediate resistance of the battery cell connections, and, finally, mechanical damage and breach of the battery circuit. Thus it may happen that, in a critical situation, battery fault would induce the thyristor rectifier switch off, leaving all the consumers without a direct voltage, including even the protective devices. In such a situation, it is very important for rectifier to stay in operation, continuing power supply of the critical consumers with a stable direct current, even if the extremely heavy electrical disturbance occurs in a local direct current grid. Additionally, electric transient must not affect any protective function that turns the rectifier off, if the variation of the consumer's current occur in а range from 1% up to 100% of the nominal load, regardless of the simultaneous disconnection or connection of the storage battery. Moreover, alternative procedure was requested for a relatively quick detection of the battery availability on the rectifier’s output contacts. Such a rigorous request regarding the rectifier’s dynamic characteristics could be only met by the simultaneous reconstruction of the thyristor rectifier power circuit and modification of the electronic control circuit. Reconstruction of all the fourteen rectifiers in the power plant, with nominal output voltages of 110 V and 220 V, was performed. Of the mentioned number, nine upgraded rectifiers were of type “DRI 07”, with digital controllers, alongside with five older devices with analog control electronics. In order to fulfill all the specified requests, on all the high-power rectifiers were mounted output filter electrolytic capacitors, altogether with the auxiliary power circuit components (protective switch, capacitor discharging resistors, fuses). Beside the modification of the power circuit, also upgrade of the voltage and current digital regulators was necessary, as well as the addition of the EMI filters and improvement of several protective and signalling functions.
Improvements of the thyristor rectifiers based on the digital controller of type “DRI 07” were described in detail. Responses of the rectifier digital regulators were presented in the cases of the battery disconnection and connection, in circumstances of permanent operation in the voltage regulation mode, as well as during the alternation of the voltage and current regulators in a trickle charge mode. The effect of the adaptive PI regulator on dynamic characteristics of rectifier was analyzed during the abrupt load current variations. Applied procedure for the battery availability check was described, as well as its influence on the characteristics of the storage battery.
N.Kartalović - INT
Pages 382 - 391
Abstract
The paper presents the tests and analysis of partial discharge and condition diagnostic of turbo generator stator insulation system. It is particularly emphasized the importance of on-line and off-line partial discharge measurement and also the importance of monitoring. Since 2007, the system for permanent monitoring of partial discharges was installed on two turbo generators. Data collected from years of data monitoring of partial discharges are kept in a separate archive while all other diagnostic tests are stored in a database for the generators. This paper presents the results of the condition diagnostic assessment of turbo generator insulation system in a power plant TENT A. This allowed the identification of trends and correlations between specific values and parameters. Measured and analyzed characteristic of insulation system, such as: the phase winding insulation resistance, dissipation factor and capacitance, AC and DC leakage current, high voltage testing and partial discharge, were of interest. This paper presents some results and analysis which indicate the significant changes in the condition of the insulation system. On the other hand, complex diagnostics of insulation system, which relies on the correlation of certain parameters, especially with a partial discharge, indicates the nature of these changes and their lower importance.
Ana Milosevic - INT
Pages 392 - 401
Abstract
This paper presents a complete system for permanent monitoring of partial discharges on hydro generators. As part of the revitalization of aggregates in hydro power plant Djerdap 1, system for monitoring partial discharge installs in all six generators. A system for monitoring partial discharge, type ICMmonitor was successfully put into operation on the new (rehabilitated) generator G6. The system is connected to SCADA system. The paper shows the technical solution of that system. In order to achieve the full capacity of monitoring system, it is necessary to do some preliminary testing, so-called mapping of generator. For this purpose, it was assessed partial discharge signal propagation through a stator winding or through a particular branch of phase. The results provide a spectral analysis of partial discharge signals depending on the position of discharge. The signal attenuation in the single measuring channel, cross-talk or the character of cross-talk between phases is also obtained. The paper presents comparative studies of partial discharge on generator made with built-in monitoring system and with portable test device. The initial parameters give the possibility of an effective condition diagnostics of insulation systems during further exploitation. The analysis of partial discharge monitoring during the first year of generator operation is presented.
dr Miloje Kostić - Electrical Engineering Institute Nikola Tesla , Nikola Georgijević - Electrical Engineering Institute Nikola Tesla , Milan Ivanović - Electrical Engineering Institute Nikola Tesla
Pages 402 - 412
Abstract
Generator capability curves (PG-QG) are necessary for the power plant operating stuff. The most important part of this curve is the part which defines the generator regime with increased reactive power, within operating coordinates (QG ≥ QG,N, PG ≤ PG,N). The actual capability curve of the generator can be determined by using new method for determination of Potier reactance, which is based on the the no-load test and the reactive load test. This method was tested on 348 MW turbogenerator unit at the "Kostolac B" thermal power plant, and verified for operating modes around the nominal values of active and reactive power. This method was adopted by the Profession Council of JP EPS.
For the new study ″Generator capability curve construction (by the new method for determination of Potier reactance)″, the capability curves are constructed for five turbogenerators, with power rating from 110MW to 620MW.
Capability curves from generator manufacturer's documentation compared to the P-Q curves constructed using this new method are significantly different. Therefore, it was recommended to reconstruct P-Q curves periodically, every 6-7 years, or after major repairs. Similar discrepancies of capability curves, compared to manufacturers, were obtained during the testing and researches of power generators in U.S.
Described differences of P-Q curves obtained using this new method compared to manufacturers documentation are especially interesting for two generators connected to 110 kV via block-transformer:
- 110 MW generator, cos φ=0.80, at the "Kolubara" power plant,
- 200 MW generator, cos φ=0.85, at the "Kostolac A" power plant.
Also, it was established that supply voltage variation within range 110 kV±5%, has major influence on the capability curve region with coordinates (QG ≥ QG,N, PG ≤ PG,N), and the corresponding results will be presented in this paper.
Djordje Stojic - Elektrotehnicki institut "Nikola Tesla" , Slavko Veinovic - Elektrotehnicki institut "Nikola Tesla" , Milan Milinkovic - Elektrotehnicki institut "Nikola Tesla"
Pages 413 - 421
Abstract
In this paper, the excitation controller for the synchronous generator with the exciter is presented, introducing the novel stabilization feedback action based on the generator rotor current. Proposed improvement is represented by the fact that the level of performance required for the synchronous generator voltage control by the related standards can be achieved with novel additional pure gain based feedback action. When compared to the existing solutions that rely on sequential differential compensators to achieve the required dynamic indices, the proposed solution is less sensitive in relation to the measurement noise. Also, when compared to the solutions with different stabilizing feedback actions, the structure proposed in this paper enables more stable and faster dynamic response. The comparative analysis between different solutions is presented in the paper, demonstrating the improvements introduced in the paper. The performance of the proposed solution is verified through the set of simulation and experimental runs, with the resultant responses presented in the paper. Simulations are carried out by using the full order generator and exciter models, while the experimental tests were conducted on the 300 MW aggregate installed in a thermal power plant.
Milan V. Petrović, Miloš Despić, Milan Banjac, Dejan Đukanović, Srđan Milić - University of Belgrade-Faculty of Mechanical Engineering, Belgrade , Đorđi Biljanoski, Milan Petković,Glišo Klasnić, Srđan Josipović, Savo Bezmarević, Dušan Kovačević,Vladimir Paunović - Thermal Power Plant Nikola Tesla A, Obrenovac, Serbia
Pages 422 - 431
Abstract
In the TPP Nikola Tesla, unit A6 a retrofit the steam turbines was made recently. It has allowed an increase of the unit power by 40 MW and reduction of the specific heat consumption of the turbine plant by 105 kJ/kWh. After the redesigned facilities were put into operation, comprehensive thermal acceptance tests were carried out. The results showed that the guaranteed value of the performances were achieved. Although the guarantee was fulfilled, the analysis of test results showed that, there are some deviations in the operations of a part of the facilities. The problem was located and eliminated so that the performances of the unit could be greatly improved. The paper presents our experience form the tests and most important results.
Apstrakt
U TE Nikola Tesla na bloku A6 urađen je retrofit parne turbine koji je omogućio povećanje snage bloka za 40 MW i smanjenje specifične potrošnje toplote turbopostrojenja za 105 kJ/kWh. Posle puštanja rekonstruisanog postrojenja u pogon sprovedena su sveobuhvatna prijemna termotehnička ispitivanja. Rezultati ispitivanja su pokazali da su garantovane vrednosti radnih karakteristika postignute. Takođe, na osnovu analize rezultata ispitivanja je utvrđeno da, iako je garancija ispunjena, postoji odstupanje u radu dela postrojenja čijim je otklanjanjem značajno unapređen rad bloka. U radu će biti prikazana iskustva sa ispitivanja i najvažniji rezultati.
Momir Samardžić - Power Utility of the Republic of Srpska, TPP Ugljevik , Prof. dr Zdravko N. Milovanović - University of Banja Luka, Faculty of Mechanical Engineering, S. Stepanovica 71, Banja Luka
Pages 432 - 441
Abstract
Most of its working time EES spends in normal working conditions, which are characterized by satisfaction of electric energy consumers needs, by presence of enough reserves in production and transfer capacities, where the frequency of the system, voltages in junction points, power flows by branches, active and reactive productions of generator are in permissible limits of variation and there is no overloads of elements inside EES (power limits are not endangered). Working in this mode in real time leads to potential risks which could be initiated by different sudden disruptions (it is usual that safety of a system is held just for single disruptions – safety limits, n-1 safety criterion). Working regimes with maximum efficiency, minimal losses, safe and secure work demand continuous application of methods for optimizing working parameters of technological process of electric energy production in thermal power plants. As technological process of electricity production in thermal power plants is very complex and depends on numbers of factors, optimization of the process implies continuous tracking and analysis of working parameters of the media which takes part in technological process of electricity production with the goal of its accommodation to the current conditions which are in charge as in higher hierarchical electro energetic system, so in the thermal power plant itself. For the realization of process of optimization it is necessary to have quality and competent personnel, modern and quality equipment for testing, measuring, regulation and control, as well as degree of automatization as high as possible.
Apstrakt
Najveći dio svog radnog vremena EES provodi u normalnom režimu rada, koga karakteriše zadovoljene potrebe potrošača za električnom energijom, postojanje dovoljnih rezervi u proizvodnim i prenosnim kapacitetima, pri čemu su frekvencije sistema, naponi u čvorištima, tokovi snaga po granama, aktivne i reaktivne proizvodnje generatora u granicama dozvoljenih promjena i nema preopterećenih elemenata u okviru EES (nisu narušena pogonska ograničenja). Rad u okviru ovakvog stanja u realnom vremenu dovodi do pojave potencijalnih opasnosti, koje mogu biti inicirane različitim iznenadnim poremećajima (uobičajno je da se sigurnost pogona odražava samo za jednostruke poremećaje - sigurnosna ograničenja, n-1 kriterij sigurnosti). Režimi rada sa najvećom efikasnošću, najmanjim gubicima, sigurnim i bezbijednim radom zahtijevaju kontinuiranu primjenu metoda optimizacije radnih parametara tehnološkog procesa proizvodnje električne energije termoelektrana. Kako je tehnološki proces proizvodnje električne energije u termoelektranama veoma kompleksan i zavisan od niza uticajnih faktora, optimizacija procesa podrazumijeva kontinuirano praćenje i analizi radnih parametara medija koji učestvuju u tehnološkom procesu proizvodnje električne energije termoelektrana, s ciljem njihovog podešavanja trenutnim uslovima koji vrijede kako u višem hijerarhijskom elektroenergetskom sistemu tako i na samoj elektrani. Da bi se proces optimizacije mogao realizovati neophodno je posjedovati kvalitetne i stručne kadrove, zatim savremenu i kvalitetnu ispitivačku mjernu, regulacioni i upravljački opremu, kao i što veći stepen automatizacije procesa.
Ninel V. Čukalevski - Institute Mihajlo Pupin*, Energosoft, Digit, Serbia , Dragan Nikolić - JP EPS, Serbia
Pages 442 - 451
Abstract
To be able to take competitive technical and commercial decisions at different hierarchical levels at the electricity utility, as well as at different locations, utility employees that are at the different decision making positions need numerous adequate and timely process and maintenance data from all company segments in generation, mining and electricity distribution, on the regular basis. Now days this is in most part done locally with limited IT support, and with almost no integration between applications/systems. To improve effectiveness of the current operation and maintenance processes, new technical information system was designed and its first phase developed and implemented at national utility. The scope of this phase is limited to the extensive utility technical data base, and basic applications for its creation and maintenance, together with the two main applications for shift/daily operations reporting at all of the utility segments. IT technologies selected and applied are state of the art, based on commercial ORDBMS, web application server as a middleware core and Java applications, within the three tier architecture.
In this paper the system architecture, functional scope, data model and applied information technologies will be described. These will be illustrated in the paper with the HMI samples from the recent project.
Nemanja Banjalic, Ivan Gajic, Zoran Stojanovic, Milorad Jovanovic - Thermal power plants Nikola Tesla, P.O. Box 25, 11500 Obrenovac
Pages 452 - 457
Abstract
Turbogenerator bearings are placed close to the turbine rotor gland steam chambers because of their specificity and compactness of the turbogenerator as a whole. Bearings are lubricated with oil and there is always certain amount of oil vapour present in the area around the bearing casing. The preassure inside gland steam chambers is lower than the atmosferic one, hence oil vapour, together with the surrounding air, is sucked into the gland steam installation. The gland steam, contaminated with the turbine lubricating oil causes many operational problems. Installation for the gland steam condensate filtration efficiently removes oil and impurities, without additional pumps and power consumption, on the gravity force basis, safely and without condensate losses in all unit operational regimes. Also, the installation could be used in other thermal power plants and industrial facilities with the similar problem, having in mind their specific characteristics.
Milutin Savićević, dipl. inž., Dragan Živić, dipl. inž., Slaviša Jotov, dipl. inž., Zoran Stojković, dipl. inž - PD TEKO, Kostolac , Bojan Papić, dipl. inž., Miroslav Crnčević, dipl. inž. - Institut „Mihajlo Pupin“, Beograd
Pages 458 - 468
Abstract
The „Mihailo Pupin“ Institute – Belgrade has been in the business with the applied researches in the wide scope of electronics since its establishment in 1946. The realized research results have been implemented in the electric power industry, traffic and industrial companies in Serbia, and even wider, with the synthesis of the scientific and expert knowledge in the area of the process management, remote control, automatic management and software engineering.
In the realization of the obtained works within the adaptation of the Block TPP Kostolac – B2, power 348.5 MW, the company “IMP- Automation and Control systems” performed successfully all comprehensive and very important works.
The paper presents the agreed and implemented works and it emphasizes their importance for the future block operation. The given comparison of the realized production results in the block operation, before and after adaptation, implies to the significantly better technical and economic effects, achieved after the completition of the block adaptation.
Kratak sadržaj:
Institut Mihajlo Pupin - Beograd od svog osnivanja, 1946. godine, bavi se primenjenim istraživanjima u širokom spektru elektronike.Ostvareni istraživački rezultati uz sintezu naučnog i ekspertskog znanja u oblasti upravljanja procesima, daljinskog nadzora, automatskog upravljanja i softverskog inženjerstva, našli su svoju primenu u elektroprivredi, saobraćajnim i industrijskim preduzećima u Srbiji, pa i šire.
U realizaciji dobijenih poslova u okviru adaptacije bloka TE Kostolac – B2, snage 348,5 MW, preduzeće, IMP-Automatika uspešno je ostvarilo obimne i vrlo značajne poslove. U radu se daje prikaz ugovorenih i raelizovanih poslova i ukazuje i ističe njihov značaj za budući rad bloka. Datim upoređenjem ostvarenih proizvodnih rezultata u radu bloka B-2, pre i posle adaptecije, ukazuje se na značajno bolje tehničke i ekonomske efekte, koje blok ostvaruje posle izvršene adaptacije.
Dragan V. Kalaba - Faculty of Tehnical Sciences, University of Priština, Kneza Miloša 7, Kosovska Mitrovica, Serbia , Milan Lj. Đorđević - Faculty of Tehnical Sciences, University of Priština, Kneza Miloša 7, Kosovska Mitrovica, Serbia , Zoran J. Radaković - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, Belgrade, Serbia , Snežana D. Kirin - Innovation Centre of the Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, Belgrade, Serbia
Pages 469 - 484
Abstract
The probabilistic analysis and availability evaluation of the thermal power systems during useful life period are helpful in minimizing failures of the system and thus to optimize the system working. The present system of thermal power plant under study consists of three subsystems and the availability and reliability assessment is based on a thirteen-year failure database. By implementation of mathematical application of theory of reliability, based on statistics and theory of possibility, exploitation research of the availability has defined the function, or the probabilistic law, according to which the random variable behaves (occurrence of complete unplanned standstill). The initial hypothesis that the distribution of the observed random variable approaches exponential distribution has been confirmed. Obtained results make possible to acquire a better knowledge of current system state as well as a more accurate assessment of its behavior during future exploitation. Final benefit is opportunity for potential improvement of complex system maintenance policies aimed at the reduction of unexpected failure occurrences.
Dane D. Džepčeski*, Vladimir S. Stanojčić, Dušan B. Arnautović, Slobodan S. Bogdanović, Jelena S. Pavlović, Jasna D. Dragosavac, Aleksandar B. Latinović**, Vukašin Ð. Masnikosa - Electrical engineering institute „Nikola Tesla“ a.d. Koste Glaviniæa 8a, Belgrade, Serbia Member of the University of Belgrade* Electric Power Industry of Serbia, Vojvode Stepe 412, Belgrade, Serbia**
Pages 485 - 492
Abstract
In this paper testing results of characteristics and parameters of a turbine governing system of one thermal power unit, that are of importance when unit operates in primary frequency control, are presented. Short overview of these characteristics and parameters is shown in order to provide background for presentation and interpretation of test results. Test results are presented together with applied testing procedures and with current standards and policies that address this issue. General approach to processing of the gathered data enables comparison of each unit response to the simulated step disturbance of grid frequency, whether it is thermal or hydro unit.
Apstrakt
U radu je izložen pregled osnovnih pojmova koji se odnose na primarnu regulaciju učestanosti u elektroenergetskom sistemu. Detaljno je opisana primenjena metodologija ispitivanja sistema turbinske regulacije termoagregata pri radu agregata u primarnoj regulaciji. Prikazani su rezultati ispitivanja sprovedenih na jednom od tipskih termoagregata koji su obuhvaćeni eksperimentalnim delom studije „Sistemski parametri regulacije pobude i turbinske regulacije u elektranam EPS-a“. Rezultati ispitivanja su prikazani na takav način da je uporedo sa analizom rezultata dat i pregled poredbenih kriterijuma iz važeće regulative i standarda koji obrađuju ovu oblast, kako bi se moglo izvršiti poređenje rezultata ispitivanja na predmetnom agregatu i bilo kom drugom ispitivanom termoagregatu. Opštost kvalitativne analize prikazanih rezultata ogleda se u mogućnosti poređenja odziva po aktivnoj snazi termo i hidroagregata na simulirani poremećaj učestanosti u elektroenergetskom sistemu.
Vera Šijački Žeravčić, Gordana Bakić, Miloš Đukić - Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd , Biljana Anđelić - Tehnički fakultet Čačak Univerziteta u Kragujevcu, Svetog Save 65, 32000 Čačak , Bratislav Rajičić - Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd
Pages 493 - 502
Abstract
Mešoviti zavareni spojevi koji se često koriste pri izradi opreme, najčešće cevi, uvek predstavljaju posebno kritično mesto u sistemu, sa aspekta moguće pojave oštećenja. Često se javljaju problemi u slučaju zavarivanja raznorodnih spojeva niskolegiranih i visokolegiranih čelika zbog izbora dodatnog materijala, jer on može da odgovara samo jednom od čelika u spoju, najčešće onom koji je niže klase. Izabrani dodatni materijal će, sa druge strane, da determiniše osobine zavarenog spoja, jer će da diktira odvijanje metalurških procesa, odnosno faze koje se izdvajaju tokom zavarivanja i predstavljaju nosilac osobina spoja. Dosadašnja iskustva su pokazala da neke od faza koje se izdvajaju pri raznorodnom zavarivanju X10CrMoVNb91 mogu da imaju nepovoljan uticaj na eksploatacionu upotrebljivost ovih spojeva. U ovom radu su razmatrane različite faze koje se javljaju pri obrazovanju mešovitih spojeva od kojih je jedan čelik X10CrMoVNb91 koji je našao široku primenu na termoenergetskim postrojenjima.
Gordana Bakić, Vera Šijački Žeravčić, Miloš Đukić, Bratislav Rajičić - Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd , Biljana Anđelić - Tehnički fakultet Čačak Univerziteta u Kragujevcu, Svetog Save 65, 32000 Čačak
Pages 503 - 513
Abstract
Klasa čelika 1.25Cr1Mo0.3V se već dugo koristi za izradu elemenata TE postrojenja izloženih povišenoj temperaturi i unutrašnjem pritisku, tako da je i na našim postrojenjima već dugo u upotrebi. Ovaj čelik je mnogo bolje poznat kao: 15H1M1F (GOST), kao livena verzija 15H1M1FL (GOST), zatim livena verzija razvijena na zapadnom tržištu G17CrMoV510 (DIN EN) i relativno nova verzija od koje se izrađuju valjani proizvodi pod oznakom 15CrMoV510 (VdTUV). Iako je ruska varijanta ovog čelika dobro poznata i sa aspekta osobina i sa aspekta ponašanja u eksploataciji, zapadna varijanta pod oznakom 15CrMoV510 se praktično tretira kao potpuno nov materijal kod kojeg nije jasno pre svega njegovo ponašanje u eksploataciji, pa čak ni neke njegove osnovne karakteristike. S obzirom da se danas čelik 15CrMoV510 intenzivno ugrađuje u naš termoenergetski sistem u procesu revitalizacije parovoda, u ovom radu je dat pregled najznačajnijih karakteristika čelika ove klase. Određene osobine čelika 1.25Cr1Mo0.3V determinišu njegovo ponašanje u uslovima eksploatacije, a one mogu da imaju prihvatljive i neprihvatljive varijacije, koje se javljaju tokom njegove fabrikacije. U ovom radu je stavljen poseban akcenat na korelaciju ključnih osobina i eksploatacione upotrebljivosti, kako za osnovni materijal tako i za zavarene spojeve.
Bratislav Rajičić, Gordana Bakić, Miloš Djukić, Vera Šijački Žeravčić - Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd , Milenko Braunović - MB Interface Inc, 5975 Av De L'authion Bureau 503, Montreal, Quebec, Canada , Biljana Andjelić - Tehnical Faculty Čačak, University of Kragujevac, Svetog Save 65, 32000 Čačak
Pages 514 - 523
Abstract
Based on the analysis of the exploitation behavior of domestic thermal power plants it was concluded that the failures on the boiler tubing systems is due to erosion by flying ashes and that it is the main cause for the boiler tube failure especially in the evaporator and economiser surfaces. Current boiler tube erosion protection methods can be classified into three basic categories: a) welding overlay; b) thermal spraying (metallization) and c) mechanical protection. Welding overlay and thermal spraying procedures are successfully implemented on the clean boiler tubings prior to installation, although the same procedure with qualitative preparation (cleaning) can effectively be used even with the boiler tubings that were in the operation for a period of time. On modern thermal power plants in the world, thermal spraying method is widely used for the protection against erosion, abrasion and corrosion. Despite being inexpensive, mechanical protection methods are generally not used in the modern systems because of limited lifetime, difficulties during dismantling and reduced heat transfer on the protected tubings. In order to reduce the number of outages (direct material saving) and thus improve the operational reliability, availability and competitiveness, the use of modern erosion protection methods is of high priority.
Gordana Bakić, Bratislav Rajičić, Miloš Đukić, Vera Šijački Žeravčić - Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd , Momčilo Kokanović - BSK d.o.o. Obrenovac , M. Janićijević - MORSAD Topola , Biljana Anđelić - Tehnički fakultet Čačak Univerziteta u Kragujevcu, Svetog Save 65, 32000 Čačak
Pages 524 - 525
Abstract
Erozija i abrazija različite opreme termoelektrana je stalni pratilac rada postrojenja, posebno u slučajevima kada se koriste visokoerozivni ugljevi. U ovim uslovima dolazi do čestih otkaza komponenti koje su u stalnom kontaktu ili sa ugljem (mlinovi, kanali aero smeše) ili sa pepelom (cevni sistem kotla, sistem za otpepeljavanje) jer on sadrži veliki procenat mineralnih sastojaka velike tvrdoće. Zato se u svetu čine veliki napori da se razviju materijali koji bi pod ovakvim uslovima pokazivali dobru erozionu i abrazionu otpornost, odnosno generalno dobru otpornost na habanje, a da pritom budu ekonomski isplativi. U ovom radu prikazana je jedna od legura koja ima vrlo povoljna svojstva otpornosti u uslovima habanja generalno, a koja do sada nije našla veću primenu na termoenergetskim postrojenjima kod nas. Legura spada u klasu visokolegiranog belog livenog gvožđa i može relativno jednostavno da se proizvede. Dosadašnji rezultati eksperimentalnih ispitivanja, a posebno ispitivanja in situ su pokazali da delovi opreme izrađeni od ovog materijala višestruko premašuju radni vek uobičajenih legura za konkretnu namenu. Jasno je da se zbog postignutih osobina otvara mogućnost za širu primenu ovog materijala u izradi delova opreme koje rade u izrazitim uslovima habanja.
Miloš Djukic, Vera Šijački Žeravčić, Gordana Bakić - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade , Biljana Andjelić - Tehnical Faculty Čačak, University of Kragujevac, Svetog Save 65, 32000 Čačak , Bratislav Rajičić - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade
Pages 526 - 537
Abstract
Defining mechanisms of interaction of hydrogen with metals, which cause local changes in microstructural and mechanical properties of metals, as a result of the occurrence of different types of hydrogen damages, including hydrogen embrittlement, is an extremely complex problem. Depending on the specific interaction between influencing factors responsible for the initiation and development of hydrogen damages, different micro-mechanisms of hydrogen embrittlement manifested in macro decrease of metal plasticity (embrittlement), often accompanied by an increase in the plasticity on micro (local) level. Despite the fact that hydrogen corrosion frequently caused damages of the boiler evaporator tubes of sub-critical thermal power plants, this type of corrosion is at the same time least investigated, particularly from the point of view of their initiation, growth kinetics and possible causes and mechanisms. This paper gives an overview of the current knowledge in the field of hydrogen embrittlement mechanisms of metal with special reference to their interactions.
Sonja Vidojkovic - Termoelektrane "Nikola Tesla"
Pages 538 - 542
Abstract
One of the foremost concern in thermal power plants is the formation of deposits of corrosion products in diverse areas of the water/ steam cycle. This deposition process causes local overheating and rupture of boiler tubes, damages of turbines and other segments of power units, that ultimately leads to sizable efficiency loss. The corrosion products are metal oxides usually present in colloidal form and tend to precipitate on the heat exchange surfaces. In this paper a new approach to prevention deposit using electrokinetic properties of colloidal particles is discussed. The mechanism of deposition formation is outlined considering the role of electrostatic interactions between the steel wall surface and colloidal particles. Furthermore, utilization of zeta potential data in deposit predicting and control is thoroughly elucidated. It was inferred that described concept is applicable in power industry through changing electrokinetic potential of colloidal particle what is attainable either by modification of structure of adsorption layer of metal oxide particles or by altering pH of boiler water. It was stated that exploiting surface properties of corrosion product for controlling and mitigation deposition in power chemistry circuits may have a huge benefit for power plants improving their availability, reliability and performances.
DSc Goce Vasilevski Scientific institution MINING INSTITUTE,Skopje - energetika
Pages 543 - 550
Abstract
When time varying heat transfer we can expect certain changes in temperature of the material subjected to the same. Depending on the material properties of these changes can significantly affect the time-temperature field inside thematerial.
In this paper we shall present a brief overview of the impact of material characteristics on the rate of change of temperature inside of the material for several characteristic structural materials under certain boundary conditions of time varying heat transfer.
DSc. Goce Vasilevski Scientific institution MINING INSTITUTE, Skopje - energetika
Pages 551 - 557
Abstract
During time varying heat transfer we can expect certain changes in temperature of the material subjected to these processes. Depending on the material properties these changes can significantly vary from case to case and can affect the time-temperature field inside the material.
In this paper we shall present a brief overview of the impact of material characteristics on the rate acceleration of change of temperature inside of the material for several characteristic structural materials under certain boundary conditions of time varying heat transfer.
G.H. Kanevce - Macedonian Academy of Sciences and arts , L.P. Kanevce - Faculty of Technical Sciences, Bitola, Republic of Macedonia
Pages 558 - 564
Abstract
In this paper our newest prediction of the electricity consumption in Macedonia up to 2031 is presented, as well as, the possibilities for meeting the Macedonian electricity needs in the analyzed period. The presented results are part of the Macedonian energy system development analysis, conducted using the MARKAL software package. In the last ten years the electricity in Macedonia has been generated by the lignite fired thermal power plants (80%) and the hydropower plants (20%). From the results presented in this paper, in 2031, it is expected that the share of lignite thermal power plants in the electricity generation will be 37%. The nearly same share (34%) will have the natural gas power plants and combined heat and power plants. The share of the large hydropower plants will be 21%. The percentage share of all other renewable energy sources will be 8%.
Apstrakt
U ovom radu su prikazana naša najnovija predviđanja potrošnje električne energije u Makedoniji do 2031. godine, kao i mogućnosti za obezbeđivanje iste u analiziranom periodu. Predstavljeni rezultati su deo analize razvoja makedonskog energetskog sistema koja je sprovedena korišćenjem programskog paketa MARKAL. Tokom zadnjih deset godina električna energija u Makedoniji se proizvodila u termoelektranama na lignit (80%) i hidroelektranama (20%). Prema rezultatima prikazanim u radu predviđa se da, u 2031. godini, udeo termoelektrana na lignit u proizvodnji električne energije bude 37%. Skoro isti udeo (34%) će imati elektrane na prirodan gas i kombinovane termoelektrane-toplane na prirodan gas. Udeo velikih hidroelektrana će biti 21%, a procentualni udeo svih ostalih obnovljivih izvora energije 8%.
Prof. Milovan Studovic PhD, retired full professor - University of Belgrade, Mechanical Engineering Faculty
Pages 565 - 566
Abstract
This paper provides an overview of the current “portfolio” of infrastructure development, technological and operational performance of the energy production systems and economic indicators of energy companies in EU and SEE, in relation to the status in 2000 (as referent year), with impact of the economic recession after year 2008, on the economic effectiveness of the whole energy system (on both, production and demand side), as well as the evaluation of the potential consequences in the line to achieving desired and possible socio-economic development, within period 201o-2020, in “selected” EU and SEE countries.
In the context of the “imposed” options of the energy sector development, the analysis the influence of the relevant institutions and interest groups, on the authority and responsibility on the "imposed'' options of development is discussed, with the comments of their professional competencies for defining “portfolio” of so called “sustainable energy sector development”, in the line with society`s expectations, regarding of their social, safety, and environmental responsibilities, including also the certain economic effectiveness of energy industry operation.
Apstrakt
U radu se daje osvrt na tekući „portfolio’’ infrastrukturnog razvoja, tehnološke i operativne performanse proizvodnih sistema i ekonomske indikatore poslovanja energetskih subjekata u EU i JIE, u odnosu na 2000. godinu, te uticaja ekonomske recesije posle 2008. godine na ekonomsko poslovanje celine energetskog sektora (na strani proizvodnje i strani potrošnje energije) i procenom eventualnih posledica, u pogedu dostizanja poželjnog i mogućeg socio-ekonomskog razvoja, u periodu od 2015 do 2020. godine u „odabranim’’ zemaljama EU i JIE.
U kontekstu „nametnutih’’ opcija razvoja energetskih sektora, analiziran je uticaj relevantnih institucija i interesnih grupa, sa stanovišta društvene nadležnosti i odgovornosti u formulisanju „nametnutih’’ opcije razvoja energetskog sektora, uključujući i njihovu profesionalnu kredibilnost u definisanju „portfolia’’ tzv. „održivog ravoja energetike’’ i društvene odgovornosti za socijalno prihvatljivo i ekonomski efektivno poslovanje energetskog sektora.
P. Radovanovic, M. Jovanovic and A. Eric - VINCA Institute Laboratory for Thermal Technique and Energy, Belgrade University, POB 522, 11001 Belgrade, Serbia
Pages 567 - 578
Abstract
In the process of accession to the EU, Republic of Serbia will be obliged to achieve an appropriate share of renewable sources in primary energy consumption in addition to control the emission of carbon dioxide in order to comply with EU’s energy policy. In this paper the potential of the production of the so called “green electricity” from biomass and waste in Republic of Serbia is shown with particular attention to the Electric Power Industry of Serbia (EPS), as the largest potential producer of electricity from renewable fuels.
Based both on the available total quantity and heating value of non-hazardous solid waste material (municipal and industrial), the calculation of the total available energy potential of waste in the Republic of Serbia (by regions) was performed for the state of the 2010th and the projections of waste quantity growth until 2020th. Also, for the same time period, the available amount of waste biomass suitable for co-firing with coal was estimated, as the respective energy potential.
The possible energy effects of co-combustion in EPS power plants as well as reduced emissions of CO2 with significant financial impact are demonstrated.
Actually, this paper is a short excerpt from the Preliminary study on necessity and techno-economical justification of renewable fuel co-firing in EPS’s thermal power plants fired with coal, which was revised and accepted by Electric Power Industry of Serbia this year.
Miloš Teleky - process engineer senior, SES Tlmače , Dalibor Cucor - Commercial director, SES Tlmače , Peter Gaži - project manager, SES Tlmače
Pages 579 - 591
Abstract
Recently, there has occurred a demand on Turkish market to increase capacities of electric power generation based on coal combustion. It is concerning combustion of local lignite as there are large reserves of lignite in various places across the country as well as coal imported to Turkey and combusted in power plants situated alongshore.
Lignite mined in Turkey is of different quality depending on location. Its calorific value ranges from 900 kcal/kg to 2500 kcal/kg. Its water content reaches up to 55%. The fuel is often of high surface humidity that causes problems with its transporting and storing. Imported fuels are bituminous coal.
Comparison of Turkish and Serbian lignites will be presented.
Information from commissioning of two circulating fluidized bed boilers in Turkish market - the fluidized bed boiler of 120 t/h steam output for combustion of local lignite in the heating and power plant of the aluminium smelter in Seydisehir. In the second boiler of 460 t/h steam output it is combusted imported fuel – bituminous coal from the Ukraine. The boiler is in the power plant near Zonguldak city on the north coast of Turkey.
Currently, SES Tlmače works on two projects of thermal power plants in Turkey for combustion of local lignite of total output of 535 MWe. There are four fluidized bed boilers, of 370 t/h steam output each.
Mr. Vojislav VULETIĆ, PhD, Prof. Nenad ĐAJIĆ, PhD - Gas Association Serbia, Belgrade
Pages 592 - 601
Abstract
Combined heat and power generation from natural gas in Serbia has been kept to a minimum, with the production realized only in the Heat and Thermal Power Plant Novi Sad. Since there was no construction of new power generation plants for a long period of time it has become a necessity for the years to come. Therefore the possibility of combined heat and power generation using natural gas is to be considered.
The contracted imported natural gas supplies do not cover demands of the Electric Power Industry of Serbia. At the same time, the existing gas transmission system in Serbia is not capable of transporting increased gas quantities through one route running from the north of the country. This situation imposes the construction of the „South Stream“ pipeline in Serbia as a new route for all future natural gas supplies.
The construction of the „South Stream“ branch through Serbia shall commence at the end of this year, making the construction of new cogeneration plants in Serbia possible. This paper describes several potential construction locations the Electric Power Industry of Serbia is interested in.
Зоран Бакић - Министарство финасија и привреде Републике Србије , Бранислав Ковачевић - ЈП Електропривреда Србије , Илија Ковачевић - Про-ИНГ д.о.о. Београд
Pages 602 - 669
Abstract
У процесу успостављања новог и модерног система инфраструктуре квалитета (ИК), као будућег кључног сегмента унутрашњег тржишта и слободног протока роба, морају се постићи три основна циља: 1. стављање на тржиште безбедних производа са постепеним уклањањем техничких баријера у трговини, 2. јачање заштите потрошача и 3. унапређење конкурентности српске привреде. Наиме, заокруживањем новог система инфраструктуре квалитета у Србији, Република Србија ће бити неколико корака ближе евроинтеграцијама и њеним вредностима.
Четири новоусвојена закона који чине, основу ИК. Закон о акредитацији, Закон о стандардизацији, Закон о метрологији и Закон о техничким захтевима за производе и оцењивање усаглашености, суштински представљају покретач бољег функционисања свих значајних институција ИК.
Захваљујући постепеном спровођењу нових закона ИК, индустрији у Србији на располагању су нова именована тела за оцењивање усаглашености одређених индустријских производа, нова овлашћена тела за оверавање мерила, нови једноставнији поступци када је реч о увозу, извозу, производњи и оцењивању усаглашености. Ово су све разлози због којих учесници у области ИК у Републици Србији (потрошач, произвођач, увозник, извозник, па и држава) могу да одахну, те да буду сигурнији у компатибилну и конкурентну улогу српске привреде на европском и светском тржишту.
Prof. Dr Slobodan Vukosavić - School of Electrical Engineering University of Belgrade , Dr Željko Despotović - Mihajlo Pupin Institute, University of Belgrade , M.Sc. Nikola Popov - School of Electrical Engineering University of Belgrade
Pages 670 - 680
Abstract
The power management method of electrostatic precipitators (ESP) significantly affect on the separation efficiency of fly ash and fine particles from smoke gases that through the funnel drainage into the atmosphere as a specific unwanted product of electric energy production on thermal power plants (TPP). In previous decades ESP in TPP were fed by SCR controlled devices having a high degree of reliability, but with relatively low collection efficiency, hence requiring large effective surface of the collection plates and a large weight of steel construction. The collection and energy efficiency of the ESP can be increased by applying multi resonant high frequency high voltage (HFHV) power supply. This paper describe the HFHV power unit AR70/1000, topology, principles of operation and measurement results obtained during extensive experimental investigations on thermal power plants
mr Kemal Bečić, dipl.ing. - JP Elektroprivreda BiH, Podružnica Termoelektrana "Kakanj", Kakanj , Enez Đakovac, dipl.ing. - JP Elektroprivreda BiH, Podružnica Termoelektrana "Kakanj", Kakanj
Pages 681 - 691
Abstract
Savremeni elektroodvajači postižu visoku efikasnost otprašivanja uz niske eksploatacione troškove i mali pad pritiska, ali efikasnost otprašivanja rapidno opada sa smanjivanjem veličine čestice. Vrećasti filteri zadržavaju visok stepen otprašivanja u širem rasponu veličine čestica, ali se odlikuju velikim padom pritiska što često rezultira velikim i skupim kućištima. Hibridni filteri koji se sastoje od elektroodvajača i vrećastih filtera spojenih u seriju ujedinjuju dobre strane obje tehnike. U ovom radu su prikazani efekti ugradnje vrećastih filtera na elektroodvajačima blokova 110 MWe u Termoelektrani “Kakanj”, kao i očekivani efekti ugradnje vrećastog filtera na elektroodvajaču bloka 230 MWe.
M. Erić*, Z. Marković*, P. Škobalj*, D. Cvetinović*, P. Stefanović*, **M.Petković, **D Stanković - *University of Belgrade, Institute of Nuclear Sciences Vinča, P.O. Box 522, 11001 Belgrade, Serbia **JP EPS PD TENT 11500 Obrenovac, Serbia
Pages 692 - 702
Abstract
Republic of Serbia as a country signatory (from 2006) of the TREATY establishing ENERGY COMMUNITY of the SOUTH EASTERN EUROPE (ECSEE) adopted obligations to reduce emission of SOx, NOx and particulate matter-dust from Large Combustion Plants (>50 MWth) up to 2017. in compliance with EU requirements i.e Directive 2001/80/EC. According to obligations, transposition of the Directive 2001/80/EC into state legislation have been performed: Low on air protection (Sl. Glasnik RS br. 36/09) and the Directive on Limitation emission values for the pollutations emited in air (Sl. Glasnik RS br. 71/10) were addopted by the Parliamanent, while Electric Power Industry of Serbia (JP EPS) as a socially responsible company have started with reconstructions and modernization of the electrostatic precipitators on all their units since 2005. TPP Nikola Tesla A performed reconstruction of the electrostatic precipitators at units: A5 (2004), A1 (2006), A2 (2005), A4 (2007) and, at unit A6 with increased power level (from 308,5 MW to 348 MW) during 2010. Most of the investment for the Upgraded Electrostatic Precipitator at unit A6 were financed by the EU grant while part of the investment was financed by the JP EPS, too. By the international tender and the Contract, the contractor (RAFAKO) had the obligation to reconstruct the ESP in that way that the emission of particulate matter should be below 50 mg/Nm3 in all workig conditions of the boiler and ESP, especially under increased power level of the Unit, during the prolonged life of next 15 years.
Paper presents results of the measurements of boiler/Unit parameters and outlet concentration of particulate matter during the guarantee investigations for the reconstructed electrostatic precipitators performed by Institute of Nuclear Sciences Vinča, Laboratory for Thermal Engineering and Energy as an independent institution, accepted by all parties of the Contract and performed in accordance with standards ISO 9096 and EN 13284-1.
Mr Branislava Jovanović, Mr Vladana Rajaković-Ognjanović - Građevinski fakultet, Univerzitet u Beogradu, Bulevar Kralja Aleksandra 73,IZ1 000 Beograd , Dr Ljubinka Rajaković - Tehnološko-metalurški fakultet, Univerzitet u Beogradu, Karnegijeva 4, 11 000 Beograd
Pages 703 - 712
Abstract
This paper presents results on wastewater quantity and quality generated in thermo power plants Kostolac A&B. The results are obtained from Preliminary design on wastewater treatment in TPP Kostolac. Huge water consumption neccessary for electrical energy production (for cooling purposes, preparation of demi and deka water, etc.) inevitably leads to large wastewater production. Total wastewater production in TPP Kostolac A is estimated to 160 m3/MWh and 140 m3/MWh in TPP Kostolac B. However, results on wastewater quality indicated that only small portion shoud be treated prior to discharge into the recipients. In regard to Serbian and EU wastewater discharge and treatment regulations, only oiled and oiled storm waters should be treated prior to discharge, which is only 0,4 L/MWh in TPP Kostolac A and 0,9 L/MWh in TPP Kostolac B.
Apstrakt
U ovom radu su prikazani neki od rezultata bilansiranja količina i praćenja kvaliteta otpadnih voda u TE Kostolac A i B koja su urađena u okviru Generalnog projekta tretmana otpadnih voda u PD „Termoelektrane Kostolac”. Obzirom na velike količine voda koje se zahvataju za potrebe proizvodnje električne energije (hlađenje, priprema demi i deka vode, vode za piće itd), u okviru procesa proizvodnje električne energije nastaju i velike količine otpadnih voda. Ukupna produkcija otpadnih voda u TE Kostolac A je oko 160 m3/MWh i 140 m3/MWh u TE Kostolac B. Međutim, rezultati ispitivanja kvaliteta otpadnih voda su pokazali da ne treba sve otpadne vode koje se generišu u TE Kostolac prečišćavati. Prema kriterijumima domaće i EU zakonske regulative u obe TE treba prečišćavati zauljene i atmosferske zauljene otpadne vode. U TEKO A to je svega oko 0,4 L/MWh i 0,9 L/MWh u TEKO B.
Vladimir Jovanović - Univerzitet u Beogradu, Mašinski fakultet
Pages 713 - 722
Abstract
Faktor goriva („F faktor“) je alternativni način određivanja protoka dimnih gasova koji je od oktobra 1975. uveden kao standardna metoda od strane američkog Saveznog registra (Federal Register). Od tada se koristi u proračunima vezanim za zaštitu životne sredine zato što omogućava relativno jednostavno i brzo određivanje emisije štetnih i opasnih materija iz procesa sagorevanja. U literaturi su dostupni podaci za faktor goriva za različita goriva, međutim, kada su u pitanju ugljevi, oni su dati za američke ugljeve koji se razlikuju od srpskih lignita. S obzirom da primenljivost ovog faktora zavisi od sastava goriva, poželjno je da se pre primene proveri u odnosu na referentnu metodu, merenjem protoka dimnog gasa pomoću Pitot-ove sonde. U ovom radu su prikazani rezultati merenja dobijenih pri merenjima emisije iz kotlova u TE Obrenovac A i B tokom perioda od devet godina. Na osnovu poznatih podataka elementarne i tehničke analize uglja određen je faktor goriva za srpski lignit Kolubara, a zatim proveren poređenjem sa rezultatima merenja protoka dimnih gasova.
Dr Željko Despotović - Mihajlo Pupin Institute, University of Belgrade , Dr Aleksandar Ribić - Mihajlo Pupin Institute, University of Belgrade
Pages 723 - 736
Abstract
In addition to the high voltage power supply and drive electrostatic precipitator rappers, very important is the system to remove precipitated dust from the collecting hoppers which are located directly below the electrode system. Vibration of collecting hoppers appropriate amplitude and frequency can significantly improve the removal of precipitated dust. The vibratory actuators having electromagnetic drive are commonly used in these systems as a source of vibration. They are a standard controlled by thyristor converters. This converter is provided amplitude control of vibration and through it control of the flow collecting particles. Since these converters are synchronized to the 50Hz network, frequency of generated vibrations can be at 50Hz (single thyristor) or 100Hz (two thyristor in ant parallel). For the efficient flow and transport of separated particles is needed in addition to amplitude control to provide and frequency control of collecting hoppers. This paper presents one possible solution to the switching control of vibration actuator through IGBT converters which provided their amplitude and frequency control. Based on a simulation model of the system was developed experimental model, which shows the characteristic oscilloscopic records and confirmed the effectiveness of proposed solutions
Dr Željko Despotović - Mihajlo Pupin Institute, University of Belgrade , M.Sc. Marija - JankovićMihajlo Pupin Institute, University of Belgrade , Dr Vladimir Šinik - Tehnical Faculty “Mihajlo Pupin”- Zrenjanin, University of N.Sad
Pages 737 - 747
Abstract
Vibratory conveying drives are the most efficient way to transport bulk and particulate materials. Using the appropriate power converter can provide amplitude and frequency control of vibratory conveying. The range of the required amplitude of the load carrying element is 0.1-5mm, while the required frequency in the range 5-150Hz. Through the switching converter can provide these requirements. This paper describes the asymmetric half-bridge topology of IGBT converter that provides amplitude-frequency control of vibratory conveying. Despite all the advantages, this topology significantly impairs the quality of the input current of whole vibratory conveying drive, which is powering from the grid. As a measure of the impact this current can take the spectral composition of the input current. This paper presents experimental results for the most critical cases: when the excitation frequency is equal to the network frequency 50 Hz and when the higher or lower than it in a few hertz. After experimentally obtained spectra was proposed a solution to the power factor correction circuit, which provides a sinusoidal input current.
Predrag M. Živković - Univerzitet u Nišu, Mašinski fakultet, Aleksandra Medvedeva 14, Niš, Srbija , Mladen A. Tomić - Visoka tehnička škola strukovnih studija Aleksandra Medvedeva 20, Niš, Srbija , Gradimir S. Ilić - Univerzitet u Nišu, Mašinski fakultet, Aleksandra Medvedeva 14, Niš, Srbija , Aleksandra D. Boričić - Visoka tehnička škola strukovnih studija Aleksandra Medvedeva 20, Niš, Srbija
Pages 748 - 757
Abstract
Increase of traffic intensity as well as the rapid industry development across the world resulted in air quality becoming one of the most important influences of everyday life. Air quality monitoring is the necessary factor for proper decision making regarding air quality and pollution. Basics of such investigations are the measurement of wind characteristics, as the wind is the most influential factor in turbulent pollution diffusion into the atmosphere. The most of the air pollution originates from combustion processes, and the sources of pollution can be very distant. It is important to make quantitative, as well as qualitative analysis of the the polution levels. In this paper, specific methodology for continuous wind, temperature and air quality data acquisition is presented. Comparison of the measured results is given, as well as the detailed presentation of the characteristics of the acquisition software used.
Mladen A. Tomić - Visoka tehnička škola strukovnih studija Aleksandra Medvedeva 20, Niš, Srbija , Predrag M. Živković - Univerzitet u Nišu, Mašinski fakultet, Aleksandra Medvedeva 14, Niš, Srbija , Ivan T. Ćirić - Univerzitet u Nišu, Mašinski fakultet, Aleksandra Medvedeva 14, Niš, Srbija , Boban T. Cvetanović - Visoka tehnička škola strukovnih studija Aleksandra Medvedeva 20, Niš, Srbija , Žarko M. Stevanović - Institut za nuklearne nauke Vinča, Laboratorija za termotehniku i energetiku, Poštanski fax 522, 11001 Beograd, Srbija
Pages 758 - 767
Abstract
The subject of this paper is to effectively estimate traffic induced pollution emission in the city of Niš. It is well known that the traffic is the single largest pollutant. Therefore, proper treatment of this component of pollution is very important for precise estimation of pollution levels. Measurements of traffic frequency, vehicle direction, CO2 concentration, were carried out at several critical locations in the city. This experimental data were used as training data for hybrid soft computing estimator of pollution levels is developed. Developed inteligent system estimator is fuzzy model optimally adjusted by artificial neural network, commonly known as ANFIS. Test data for some characteristic cases presented at the end of the paper shows good agreement of ANFIS estimator output with experimental data. Presented results are true indicator of implemented method usability.
Prof. dr Zdravko N. Milovanović, Prof. dr Darko Knežević, Doc. dr Aleksandar Milašinović - Univerzitet U Banjoj Luci, Mašinski fakultet Banja Luka, S. Stepanovića 71, 78000 Banja Luka , Svetlana Dumonjić-Milovanović - Partner inženjering doo, Kralja Nikole 25, 78000 Banja Luka , Jovan Škundrić - Univerzitet U Banjoj Luci, Mašinski fakultet Banja Luka, S. Stepanovića 71, 78000 Banja Luka
Pages 768 - 781
Abstract
The location for suggested wind farm is placed on mountain rock "Trusina" 934 and 1180 meters above the sea level. The future wind farm will be placed 15 kilometers southern from Nevesinje and 2.5 kilometers northern form Berkovići. Size and shape of the site is determined according to measurements of the wind potential using the measuring poles of 12 and 50 meters heights, and according to detail analysis for the period from 21st of December 2006 till 10th of June 2009. The measuring process on the pole of 50 meters height is still active and will be continued until the end of 2010. Besides the measuring on the pole of 50 meters height, from November of 2010, on the location of "Trusina" another 12 meters high pole was installed for additional verifying of already measured data. During June of 2011 on "Trusina" location another two poles were installed, one of which is a brand new 50 meters high pole on the location of "Buturovac" and another is 12 meters high pole on the location of "Tovanovo brdo" with the aim of getting more additional data for even further increase of the accuracy of overall data having in mind the size of the "Trusina" location. Calculation of the wind properties has been done according to the collected data. Records of the measured data from the 50 meters high pole have been made using so called "data logger" in form of series for each 10 minutes for values of the wind speed given by seven anemometers (average value, maximal value, minimal value and standard deviation), and data of the wind directions were collected using two wind direction indicators and additional meteorological sensors. Inside the paper the results of the data processing are given in tabular form together with adequate wind speed frequency distribution functions and wind rose diagrams. For the purpose of easier comparing of diagrams, the data for whole measuring period (30 months) and for period of two years (2007 and 2008) were also given. As an additional conformation the database of meteorological station "Dubrovnik", located near the "Ćilipi" airport for the period from 30th of September 1999 till 31st of August 2010 was also analyzed. These data are available in NCEP/SYNOP form (surface synoptic observations). According to the data collected and processed in this way, the calculation of possible number of wind turbines on the specified location has been done so has their arrangement for each wind turbine on micro locations of the future wind farm "Trusina".
Vladimir Mijakovski - University “Sv. Kliment Ohridski”, Faculty of Technical Sciences, Ivo Lola Ribar bb, Bitola, Republic of Macedonia , Vangelče Mitrevski - University “Sv. Kliment Ohridski”, Faculty of Technical Sciences, Ivo Lola Ribar bb, Bitola, Republic of Macedonia , Kire Popovski - University “Sv. Kliment Ohridski”, Faculty of Technical Sciences, Ivo Lola Ribar bb, Bitola, Republic of Macedonia , Nikola Mijakovski - xSoft engineering, Arhimedova bb, Skopje, Republic of Macedonia
Pages 782 - 789
Abstract
The Directive 2009/28/EC on the promotion of electricity from renewable energy sources in the internal electricity market defines renewable energy sources as energy from renewable non-fossil sources, namely wind, solar, aerothermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases.
Biomass, as energy resource, has been and is an important part of the energy balance of the Republic of Macedonia. In this paper, current status and perspectives for utilization of Municipal Solid Waste (MSW) as an energy source in the Republic of Macedonia, its importance in the future energy mix of the country and tools for its further development, will be analysed.
Jasna Grujić and Maja Stipić - Energoprojekt Entel
Pages 790 - 799
Abstract
In accordance with the European trends related to environmental protection and use of renewable energy sources, Republic of Serbia has accepted an obligation to adopt a plan for implementation of Directive 2001/77/EC on the promotion of electricity production from renewable sources. Accordingly, large number of regulations has been adopted, including those that define status of privileged power producer. Entity which is awarded the status of privileged power producer is granted the right to produce and sell electricity in accordance with the so called feed-in tariffs, introduced as an incentive for promoting investments in the field considered. This paper presents concrete solutions of photovoltaic solar power plants installed on the roofs of buildings, embracing their design, construction and commissioning, as well as the legal procedure of obtaining permits and licenses, including acquiring the status of privileged power producer in Serbia
Suzana Kostić - Electrical Engineering Institute "Nikola Tesla"
Pages 800 - 810
Abstract
Today, most of the electric energy production is from non-renewable sources such as fossil fuels (coal, oil and natural gas). As is well known, fossil fuels are non-renewable and have a negative consequence on the environment (global warming). Therefore, more and more renewable energy sources are used, such as solar, wind, tides, wave, hydro, small-power energy and geothermal heat.
Although the potentials of renewable energy sources are huge, the current technological development does not make it possible to rely only on them. Most of the energy obtained from renewable sources is water energy, whereas the share of other renewable sources of energy is currently comparatively small. Actually, in parallel with the technological development, the renewable sources of energy are expected to economically compete with the conventional sources of energy. It may be said that the technologies for using wind energy, biomass and solar energy are already becoming more and more mutually competitive. The process of adopting new technologies is still slow, due to comparatively high initial prices. In line with the recognized environmental importance of renewable sources, greater construction of plants using such energy is being promoted.
Renewable energy sources are central issues in the current European Union energy policy. In accordance to that, the European Parliament passed the Directive (2008) on climate changes and energy (the “20-20-20”), and therefore the EU is committed to reducing its emissions of greenhouse gases by 2020 to at least 20% below the 1990 levels, increasing the energy efficiency by 20% and increasing the share of renewable sources in the final energy to 20%.
In 2009, the Serbian Government passed two significant Decrees which systematically regulate the status of producers of electricity using renewable energy sources – the Decree on the measures of incentives for production of electricity using renewable energy sources and combined production of electricity and heat and the Act on acquiring the status of privileged producers of electricity.
Production costs for the different renewable energy sources are determined in this paper: solar power, wind power, small hydro-power and biomass power. They are calculated for different investment costs, different annual electric energy production, the given rate of interest and all that for the given life cycle of the plant. The costs established in this way are compared with purchase prices of renewable energy sources in Serbia and finally, on the basis of that, the economy of investing in renewable energy sources is analyzed.
Prof. dr Zdravko N. Milovanović* - Univerzitet U Banjoj Luci, Mašinski fakultet Banja Luka, S. Stepanovića 71, 78000 Banja Luka , Momir Samardžić* - MH Elektroprivreda Republike Srpske, ZP RiTE Ugljevik* , Svetlana Dumonjić-Milovanović - Partner inženjering doo, Kralja Nikole 25, 78000 Banja Luka , Prof. dr Darko Knežević - Univerzitet U Banjoj Luci, Mašinski fakultet Banja Luka, S. Stepanovića 71, 78000 Banja Luka , Mr Vinko Babić - Univerzitet U Banjoj Luci, Mašinski fakultet Banja Luka, S. Stepanovića 71, 78000 Banja Luka
Pages 811 - 829
Abstract
Kod svakog oblika proizvodnje električne energije neminovno dolazi do uticaja na okolinu, pri čemu je u slučaju korišćenja energije vjetra taj uticaj u poređenju sa konvencionalnim tehnologijama relativno zanemarljiv. Pri radu vjetroturbine ne javljaju se emisije štetnih gasova, ne stvara se čvrsti otpadni materijal, a ni radioaktivni otpad. Kod proizvodnje električne energije iz vjetroturbina ne dolazi do nikakvih štetnih posljedica za stanovništvo, i to ne samo na lokaciji gdje se vjetropark nalazi, već ni bilo gdje drugdje u svijetu u smislu emitovanja prekograničnog zagađenja. Pored toga, korišćenje energije vjetra potpuno se uklapa u koncept održivog razvoja i nema nikakvih posledica za život budućih generacija. Negativni efekti izgradnje vjetroparka valoriziraju se procjenom mogućih uticaja i posljedica projekta na komponente životne sredine, temeljne prirodne i kulturno-istorijske vrijednosti i razvojne mogućnosti, i mogu se svrstati u dvije kategorije. Prvu kategoriju predstavljaju uticaji koji su posljedica izgradnje i imaju privremeni karakter. Posljedice nastaju radi upotrebe teške mehanizacije, građevinske tehnologije i organizacije gradilišta. Negativni uticaji, takođe, su rezultat iskopa i odlaganja materijala, transporta i ugradnje manjih ili većih količina građevinskog materijala. Drugu kategoriju sačinjavaju uticaji koji proizilaze iz uspostavljanja polja vjetrogeneratora i njihovog funkcionisanja. Ti uticaji imaju stalan (trajan) karakter i kao takvi predstavljaju uticaje od posebnog interesa. I pored toga što je uticaj energije vjetra na okolinu daleko manji od uticaja konvencionalnih energetskih izvora, on ipak postoji. Zbog toga je, u skladu sa važećom zakonskom legislativom u Republici Srpskoj odnosno BiH u cjelini, već u okviru Prethodne procjene uticaja na životnu sredinu neophodno analizirati uticaj na kvalitet zemljišta i pojavu efekta erozije tla, uticaj na kvalitet vode, uticaj na kvalitet vazduha i mikroklimu, uticaj na kvalitet pejzažnih karakteristika područja, uticaj na ukupni nivo buke, uticaj na intenzitet vibracija i zračenja, uticaj na kvalitet flore i faune, zatim uticaj na prirodna dobra posebnih vrijednosti, kulturna i materijalna dobra, kao i uticaj na moguće zasjenjivanje i treperenje.
Zarko Stevanovic - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija , Nikola Mirkov - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija , Zana Stevanovic - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija
Pages 830 - 836
Abstract
U ovom radu opisujemo metodologiju za izracunavanje ekstremne brzine vetra na osnovu eksperimentalnih podataka sa meteoroloskog stuba. Precizno odredjivanje ekstremnih brzina vetra presudno je u odredjivanju aerodinamickog opterecenja vetro-turbina, i sluzi kao ulazni podatak prilikom odredjivanja modela vetro-turbine za specificnu lokaciju. Metodologija je bazirana na statistickim modelima iz teorije o generalnim ekstremnim vrednostima. Prikazana metodologija obuhvata odredjivanje tzv. "pedesetogodisnje" brzine vetra, na kojoj su vazeci standardi za proracune aerodinamickog opterecenja vetro-turbina zasnovani. Opisana metodologija ima univerzalni karakter, a tacnost se povecava sa duzinom intervala prikupljanja statistickih podataka.
Jovan Škundrić, Prof. dr Zdravko N. Milovanović - Univerzitet u Banjoj Luci, Mašinski fakultet
Pages 837 - 847
Abstract
Vjetar kao čist i lako dostupan obnovljiv energent svakako da predstavlja atraktivan i zanimljiv put kojim može da se krene pri proizvodnji električne energije. Ipak, dobro je poznata činjenica da, barem u uslovima današnjeg vremena, konverzija vjetroenergije u električnu nije nimalo jeftina, čemu zajednički doprinose s jedne strane skupa tehnologija izrade kvalitetnih vjetroturbina i s druge, činjenica da vjetar kao radni medij ima veoma malu gustinu. Upravo iz ovog razloga, a i s obzirom da brzina u izrazu za snagu vjetra, kako je poznato, figuriše sa trećim stepenom, pri odabiru potencijalne lokacije za eksploataciju energije vjetra, od naročitog je značaja poznavanje intenziteta njegove brzine koji može da se očekuje, ali ne samo u smislu informacije o srednjoj godišnjoj brzini, već i o strukturi vjetra u smislu podataka o vjerovatnoćama javljanja pojedinih vrijednosti intenziteta brzine. S tim u vezi, u okviru ovog rada izvršena je analiza uticaja karaktera vjetra na očekivanu raspoloživu količinu energije posredstvom variranja parametra oblika Weibull-ove raspodjele. Dobijeni rezultati računati su numeričkim putem, a na osnovu prethodno formiranih matematičkih modela.
Dejan Mitrović - Masinski fakultet Nis , Branislav Stojanović - Masinski fakultet Nis , Jelena Janevski - Masinski fakultet Nis , Marko Ignjatović - Masinski fakultet Nis , Mirko Stojiljković - Masinski fakultet Nis
Pages 848 - 857
Abstract
One of the most important characteristics of biomass boilers is the need for continuous operation with nominal load. In this way, boiler is operated with maximum efficiency, boiler lifecycle elongates and the ratio between heat production and CO2 emissions is considered optimal. On the other side, outside temperature variations determine boiler operation, which is very dynamical, i.e. with frequent changes in operating load. In order to increase overall efficiency, biomass boilers are equipped with heat storage tanks. Heat storage enables accumulation of the surplus energy and provides heating in case when heating loads are relatively small. By applying heat storage, optimal boiler operation is provided throughout the most of the heating season. The goal of this paper is to analyze heat storage temperature variation depending on tank volume, outside temperature and boiler heat capacities. Two typical days were analyzed, with average daily temperatures of -5oC and 5oC. Primary energy savings have been calculated in the case heat storage was to be used in district heating system, for those typical days and for situations with 1 or 2 biomass boilers.
Jelena POPOVIĆ, dipl.ing. - Intellectual Property Office, Kneginje Ljubice 5, Belgrade, Serbia
Pages 858 - 864
Abstract
The newest knowledge from all technical feels of human activitis are concentred in the patent documentations. Patent information are contained in patent documentation are impotant by-product patentn procedure. Access to patent information is easy, quick and mostly free of cost. Nowdays for innovation and development new prodact are needed financial resource and complex team of researches. Therefore, one should uesed limitations on territorial and temporal of patent to apply already knouwn solutiones are presented in patent documentation. However, patent documentations can use as resours of activity analises in sertan technical feels.
In this artical presents analiyas of patentn protektion in our contry and in the wold. Presents results of patent documentation reaserch clas F02C of International Patent Classification.
Apstrakt
Najnovija znanja iz svih tehničkih oblasti ljudske delatnosti skoncentrisana su u patentnoj dokumentaciji. Patentne informacije sadržane u patentnoj dokumentaciji su sporedan proizvod postupka ispitivanja patentnih prijava. Pristup patentnim informacijama je relativno lak, brz i uglavnom besplatan. Na današnjem stupnju tehnološkog razvoja za razvoj pronalazaka i novih proizvoda neophodno je imati velike, uglavnom, multidisciplinarne timove istraživača. Pored toga, potrebno je ulagati velika finansiska sredstva. Stoga treba, kad god je to moguće, koristiti teritorijalno i vremensko ograničenje patenata i primenjivati već poznata rešenja prezentovana u patentnoj dokumentaciji. Osim toga, patentna dokumentacija može da posluži kao odličan izvor za analizu aktivnosti u određenim oblastima tehnike, što je u ovom radu i učinjeno.
U radu je dat pregled i analiza patentne zaštite u našoj zemlji i na svetskom nivu iz oblasti gasnih i hidrauličnih turbina. Prikazani su rezultati pretraživanja patentne dokumentacije u našoj zemlji i na svetskom nivou u klasi F02C iz Međunarodne klasifikacije patenata.
Vladimir Stevanovic - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade
Pages 865 - 873
Abstract
Examples from the countries of European Union show that coal-fired thermal power plants (TPPs) can be used for combined heat and electricity production that is acceptable from the point of view of economy and energy efficiency. Coal-fired TPPs close to the cities of Hamburg and Prague were reconstructed for the cogeneration and connected to heat distribution networks in the cities by long district heating pipelines. There are a few municipalities in Serbia (Obrenovac, Pozarevac, Kostolac) that are supplied with heat from the coal-fired TPPs reconstructed for the cogeneration. Effects of the cogeneration are shown on the example of the heating of Obrenovac from the Units A1 and A2 of the TPP “Nikola Tesla A”. The possibility of the utilization of other units of TPP “Nikola Tesla A” for the cogeneration is considered, especially regarding the limited capacity for the electricity production and a fact that cogeneration reduces the TPP’s electrical power. A heat accumulation in the long district heating pipelines enables an increase of the electric power in the periods of maximum daily and evening electricity consumption on account of the accumulated heat during the night.
Apstrakt
Primeri iz zemalja Evropske unije pokazuju da termoelektrane na ugalj mogu da se iskoriste za spregnutu proizvodnju električne i toplotne energije koja je prihvatljiva sa stanovišta ekonomije i energetske efikasnosti. Vangradske termoelektrane na ugalj u blizini Hamburga i Praga su rekonstruisane za toplifikacioni režim rada i daljinskim toplovodima su povezane sa gradskim distributivnim mrežama. U Srbiji postoje gradovi (Obrenovac, Požarevac, Kostolac) koji se snabdevaju toplotom iz termoelektrana na ugalj rekonstruisanih za kogeneraciju. Na primeru grejanja Obrenovca se pokazuju efekti kogeneracije iz blokova A1 i A2 Termoelektrane „Nikola Tesla A“ (TENT A). Razmatra se mogućnost korišćenja i preostalih blokova TENT A za kogeneraciju, pogotovu sa stanovišta ograničenog kapaciteta za proizvodnju električne energije i činjenice da kogeneracija smanjuje električnu snagu termoelektrane. Akumulacija toplote u magistralnim toplovodima velike dužine omogućava povećanje električne snage u toku perioda maksimalne dnevne i večernje potrošnje struje na račun akumulacije toplote u toku noći.
Ključne reči: kogeneracija, ugalj, sistem daljinskog grejanja
Vitomir Kravarušić, dipl inž, EPS - TE TO Novi Sad
Pages 874 - 885
Abstract
Uporedo sa poskupljenjem energenata i energije, a naročito prirodnog gasa, poskupljuju i investicije za izgradnju termoelektrana na fosilna goriva zbog povećanih cena čelika i bakra, a istovremeno se pooštravaju uslovi zaštite životne sredine i uvode veoma skupe mere za sprečavanje globalnog zagrevanja atmosfere. Iz tih razloga se pred konstruktore termoenergetske opreme i investirore termoenergetskih postrojena postavljaju sve ozbiljniji zahtevi u pogledu visoke energetske efikasnosti, jeftinijih investicija, kraćih rokova izgradnje i profitabilnosti poslovanja. Pošto se u Srbiji nije izgradio nijedan veći proizvodni energetski kapacitet u poslednjih 20 godina, Elektroprivredi Srbije bi odgovarao ulazak u pogon elektrane veće snage sa što kraćim rokom izgradnje, do ulaska većih blokova TE na ugalj. Takva mogućnost se pojavila u TE TO Novi Sad gde, pored potreba EPS-a za električnom energijom postoji i potreba za baznom toplotnom energijom za grejanje Novog Sada. Postoji istvremena potreba za električnom i toplotnom energijom pa se planira izgradnja kogenerativnog gasno-parnog postrojenja visoke energetske efikasnosti električne snage oko 450 MWe i toplotne snage oko 300 MWt. Svi povoljni uslovi postoje u pogledu lokacije, plasmana električne i toplotne energije i spremnosti u pogledu saradnje EPS-a i grada Novog Sada. Postoje i objektivne poteškoće oko obezbeđenja kontinualnih isporuka i prihvatljive cene gasa i obezbeđenja finansijskih sredstava za izgradnju ovog postrojenja. Iz tih razloga, vođeni zajedničkim interesima, EPS i grad Novi Sad su, uz saglasnost Vlade Srbije, formirali zajedničko akcionarsko društvo ENERGIJA Novi Sad a.d., radi izbora strateškog partnera za izgradnju novog kogenerativnog postrojenja. EPS i grad Novi Sad ulažu postojeća postrojenja i zemljište, a streteški partner obezbeđuje finansijska sredstva u visini većinskog vlasništva, a preostali deo investicija se obezbeđuje preko komercijalnih kredita. Za ovakav vid poslovne transakcije u EPS-u se mora obaviti korporativna transformacija da bi se mogao uložiti akcijski kapital i po toj osnovi ostvariti upravljačka funkcija u budećem akcinarskom društvu ENERGIJA Novi Sad a.d. U ovom radu se detaljnije govori o performansama savremenog kogenerativnog gasno-parnog postrojenja visoke energetske efikasnosti i novim oblicima investicione izgradnje u EPS-u.
Milan Ivanović, Saša Minić - Electrical Engineering Institute Nikola Tesla, Koste Glavinića 8a, Belgrade , Miloš Kostić - MT-Komex doo, Ulica oslobođenja 22b, Beograd
Pages 886 - 900
Abstract
The paper presents the results of techno - economic analysis of connecting cogeneration plant to the distributive network of ED Belgrade. For all available cogeneration plant types, criterion of permissible power has been checked, for connection to 35 kV and 10 kV bus, in nearby TS 35/10 kV. The results of the analysis indicated the impossibility of connection CHP to the 10 kV. According to the criterion of permissible power, it was determined that the highest power of a unit generator in a small power plant is 4.7 MVA, for connection to 35 kV bus in TS 35/10 kV. This criterion was met for only six cogeneration units. For all of them, criteria of short-circuit power at the connection point have been checked, as well as impact of their operation on network voltage. Investments required for implementation of various solutions have been estimated. Only variable costs, which are relevant for comparison of alternative solutions, have been taken into account.
Siniša Kisić, Dipl.Ing.E.E., Bojan Milinković, Dipl.Ing.E.E. - Energoprojekt Entel p.l.c., Belgrade
Pages 901 - 906
Abstract
From the point of inclusion of South East Europe economic systems into market economies, along with regular production, a very important factor shall also be the electricity cost per kilowatt and system security. It is therefore necessary to periodically perform a security assessment and to improve the existing physical and technical security solutions as well as to apply current trends and recommendations for technical and organizational security solutions in the energy complex.
Technical solutions include cable and radio telecommunications network, the suggestion and organization of IP nodes, and monitoring of the complex through the upgrade and development of new video surveillance devices, intrusion systems, communications and guard control system.
The example of PD "TE-KO Kostolac" and concluding observations in connection therewith shall be used as a reference for giving the appropriate organizational and technical recommendations with the dynamics of their implementation and assurance that these investments may fully be justified.
I believe that this paper may suggest a need to comprehensively consider the problem of physical and technical security and protection in many large systems.
Sadržaj rada:
Sa aspekta uključenosti privrednih sistema jugoistočne Evrope ka tržišnim ekonomijama pored redovne proizvodnje važana će biti i cena kilovata i bezbednost sistema. Stoga je potrebno periodično raditi bezbednosnu procenu i poboljšavati postojeća rešenja fizičko tehničke zaštite i primenjivati savremene trendove i preporuke za tehnička i organizaciona bezbednosna rešenja u energetskim kompleksima.
Tehnička rešenja obuhvataju kablovske i radio veze telekomunikacione mreže, predlog i organizaciju IP čvorišta i nadziranja kompleksa putem nadogradnje postojećih i uvođenja novih pozicija video nadzora, protivprovalnih sistema, komunikacije i kontrole stražarske službe.
Kroz primer TE TO Kostolac i zaključna razmatranja daju se preporuke u organizacionom i tehničkom smislu sa dinamikom realizacije i uverenjem opravdanosti investicije.
Smatram da rad može da podstakne razmišljane o primeni sveobuhvatnog posmatranja problema zaštite kod mnogih velikih sistema.
Mirjana Laković*, Milica Jović*, Slobodan Laković*, Mladen Stojiljković* - Mašinski fakultet u Nišu, ul. A. Medvedeva 14, 18000 Niš*
Pages 907 - 920
Abstract
Energy efficiency of thermal power plants depends on many factors. The influence of atmospheric air parameters on energy efficiency, in terms of achieving maximum power and/or minimum specific heat consumption is very important in design and exploitation of the power plants.
With increasing temperature of the atmospheric air, heat and mass transfer conditions in a cooling tower deteriorates, and the range of the cooling tower decreases. This results in higher cooling water temperature at the inlet of the condenser and thus reduces the energy efficiency of plant.
Considering that we are witnessing climatic changes due to which there are more tropical days during the year, it can be concluded that this problem will be even more prominent in the future.
Therefore, it is necessary to reconsider the design conditions in the design of new facilities ie to adopt a higher design temperature of the atmospheric air in the design of cooling towers. In the plants that are in operation it is necessary to reconstruct the cooling water system in order to achieve energy-efficient operation in the warmer months.
In this paper the performance of the cooling tower system of the power plant Kolubara A, unit A5, and its impact on the energy efficiency of the plant is considered. Based on the results the proposal for reconstruction of cooling towers is given, in order to achieve more efficient operation of the plant, especially in the summer months.
Branislav Grbović - Borovac International Pty Ltd, Perth, Australija , Jadranka Vukašinović - PD RB Kolubara, Lazarevac, Srbija , Miroslav Spasojević - Termoelektrana Nikola Tesla A, Obrenovac, Srbija
Pages 921 - 928
Abstract
Čišćenje kolubarskih lignita od jalovih primesa , koje se ne mogu izdvojiti selektivnim otkopavanjem, omogućava da rudnici Kolubare bolje koriste raspoložive geološke rezerve uglja iz svojih ležišta, a elektrane TENT da povećaju energetsku efikasnost i zaštitu okoline.
Sa postojećom tehnikom masovnog otkopavanja moćnih homogenih slojeva Istočnih ležišta Kolubare ostvarivana je proizvodnja kvalitetnog uglja za elektrane uz visoko iskorišćenje geloških rezervi uglja. Prelaskom na korišćenje zapadnih raslojenih ležišta nije više moguće istovremeno obezbediti zadovoljavajući kvalitet uglja za elektrane bez štete po iskorišćenje raspoloživih geoloških rezervi.
U radu se prikazuju teškoća na rudniku za obezbeđenje kvalitetnog uglja elektranama i posledice rada elektrana TENT sa korišćenjem uglja iz raslojenih kolubarskih ležišta.
U radu se daje i prikaz hidrauličkog procesa čišćenja kolubarskog uglja Borovac, koji je razrađen uz podršku i operativnu pomoć Kolubare i TENT.
Proces Borovac omogućava da se, uz racionalno ulaganje u nove kopove i elektrane, ostvare značajne ekonomske i ekološke koristi.
Čišćenjem se dobijaju tri proizvoda:
• Očišćen krupan klasiran ksilitski ugalj (krupnoće +40 – 150 mm) koji služi za široku potrošnju, ili se (nakon dopunskog drobljenja) ovaj kvalitetan ugalj isporučuje elektranama i koristi za proizvodnju elektroenergije..
• Očišćen, sitan ugalj (krupnoće +1,0-40 mm ) za elektrane; i
• Jalovina u obliku mulja gline sa peskom koja se (kao koristan proizvod) koristi:
- Da se deponuje u otkopani prostor kopa zajedno sa pepelom i služi za zaštitu podzemnih voda od zagađenja;
- Da obezbedi glinenu podlogu za prijem pepela iz svih elektrana (koji se ne plasira za potrebe cementara i putogradnje) u otkopani prostor kopa; ili
- Da se koristi kao sirovina u keramičarskoj industriji.
Dubrovskiy V.A., Isakov Yu.V., Potylitsyn M.Yu., Potapov I.I., Shirokov V.N. - The Federal State Autonomous Educational Establishment of Higher Professional Education (FSAEE HPE) «Siberian Federal University»
Pages 929 - 931
Abstract
Ecological restrictions demand developing and introducing new, non-polluting coal technologies ensuring highly complete combustion of fuel at the lowest harmful load on environment. The application of water coal fuel (WCF) allows to increase requirements in reliability, ecological and economic efficiency of operation of boiler units of thermal power plants. The technology of preparation of WCF provides for a mechanical process of crushing the coal raw materials following higher power inputs, mechanical wear of the equipment working elements: spherical mills, cavitators, and others.
In liquid, under successive high-voltage discharges, there are formed electrohydraulic effects which are capable to do mechanical work in crushing brown coals of the Kansk-Achinsk basin and their mixing with water.
We had done earlier experimental work on crushing brown coals in the liquid environment by using an electrohydraulic method for preliminary applicability checking of this method.
In this paper there have been given results of the investigation into obtaining WCF from brown coals of the Kansk-Achinsk basin by using the electrohydraulic crushing depending on various sizes of initial samples. The investigations were carried out on the designed model sample of an electrohydraulic coal crusher (ECC).
Samples of brown coal of the Kansk-Achinsk basin were loaded into the active zone of a cell. The design of the cell active zone allowed to load 5 … 6 kg of coal and 10-15 l of water. The analysis of discharges influence on coal raw materials was carried out for brown coal of the Kansk-Achinsk basin.
The obtained samples of coal after crushing were dried up and dissipated through a set of standard sieves.
The obtained results of the investigations are the basis for developing the technology of obtaining WCF while using electrohydraulic crushing.
Srđan V. Belošević - Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory for Thermal Engineering and Energy, PO Box 522, 11001 Belgrade, Serbia
Pages 932 - 947
Abstract
Nowadays, the following aims of coal-fired power plant technology development can be identified: higher efficiency in energy transformation, reduction of pollutants emission, operation of facilities in a wide range of loads and efficient utilization of variable quality fuels, which is of special importance in the case of domestic power plants. The emission reduction measures are to be applied at the new power plants as well as at the existing ones, in an optimal and economical way.
In doing this, application of mathematical models and numerical analysis of processes may play an important role. Modeling is regularly used worldwide for optimization of burners, furnaces and boilers, as well as in identification and solving the operation problems. Among the most important pollutants are oxides of nitrogen, while modifying the combustion can reduce NOx most economically. The paper explores the possibilities of reducing NOx emission by combustion modifications in the 350 MWe Kostolac B boiler furnace, tangentially fired by pulverized lignite.
Numerical experiments were done by an in-house developed 3D differential comprehensive combustion code, with formation and destruction reactions of fuel- and thermal-NO. The code was designed to be easily used by engineering staff dealing with the process analysis in boiler units. The effects of different operating parameters were investigated, such as: coal and preheated air distribution over the individual burners and the burner tiers, grinding fineness and quality of coal and the cold air ingress. The NOx emission reduction of up to 20-30% could be achieved only by proper organization of combustion in the existing furnace, together with the improvement of the flame position and the furnace exit gas temperature. The use of overfire air system might provide the emission reduction of up to 25% and might give up to 7% of additional reduction in already optimized cases. Due to the contradictory requirements with respect to emission reduction and efficient combustion with safe operation of the superheaters, the facility is often to be controlled within narow limits of operation parameters, as demonstrated by means of the boiler thermal calculations. Pollutants control approach like this enables evaluation of alternative approaches, considering the efficiency of both the furnace processes and the entire boiler unit.
Dragan Tucaković - Mašinski fakultet Beograd , Titoslav Živanović - Mašinski fakultet Beograd , Goran Stupar - Mašinski fakultet Beograd , Miloš Banjac - Mašinski fakultet Beograd , Srđan Belošević - Institut za nuklearne nauke Vinča , Nenad Crnomarković - Institut za nuklearne nauke Vinča , Ivan Tomanović - Institut za nuklearne nauke Vinča , Vladimir Beljanski - Institut za nuklearne nauke Vinča
Pages 948 - 960
Abstract
U cilju određivanja toplotnog bilansa i provere temperaturskih uslova rada grejnih površina energetskog parnog kotla, razvijen je korisnički softver za termički proračun parnog kotla blokova 1 i 2 u TE Kostolac B. Softver povezuje proračune, kako sklopa postrojenja za pripremu ugljenog praha i ložišta, tako i kontrolne termičke proračune ozračenih, poluozračenih i konvektivnih grejnih površina. Ovim softverskim paketom moguće je utvrditi toplotni radni režimi parnog kotla u celini, kako pri nominalnom, tako i pri smanjenim i povećanim opterećenjima, što podrazumeva određivanje temperature prijemnika i predajnika toplote na ulazu i izlazu iz svake grejne površine, protok ubrizgane vode u liniju sveže i naknadno pregrejane pare, kao i niz drugih relevantnih parametarara koji definišu rad kotla. Rezultati doijeni softverom za termički proračun parnog kotla blokova 1 i 2 u TE Kostolac B dobro se slažu sa odgovarajućim vrednostima koje su se kontinualno merile tokom 2011. godine na osnovu čega je i izvršena verifikacija softvera od strane Javnog preduzeća termoelektrane Kostolac. Razvijen i verifikovan softver je prvenstveno namenjen ispitivanju uticaja različitih mera za redukciju emisije azotnih i sumpornih oksida na stepen efikasnosti, pouzdanost i sigurnost rada razmatranog parnog kotla u celini kako bi se izvršila verifikacija i izabrala optimalna mera redukcije. Osim toga, softver se može koristiti za analizu i optimizaciju rada kotla, s obzirom da omogućuje promenu većeg broja ulaznih veličina (kvaliteta goriva, koeficijente viška vazduha, prisisa štetnog vazduha u ložištu i mlinskom postrojenju, curenja vazduha iz rotacionog regenerativnog zagrejača vazduha, zaprljanost grejnih površina, temperature predgrejanog vazduha, raspodele ugljenog praha, otparaka i vazduha po etažama gorionika i tako dalje) čime je omogućena simulacija rada parnog kotla u realnim eksploatacionim uslovima. Da bi se sagledale mogućnosti navedenog softverskog paketa, softver će u radu biti predstavljen u skraćenom obimu što podrazumeva prikaz načina unosa odgovarajućih ulaznih parametara, sam termički proračun, kao i prikaz relevantnih sračunatih veličina za odabrano opterećenje i garantni kvalitet goriva razmatranog parnog kotla. In purpose of determening the heat balance and checking the temperature work conditions of utility steam boiler heating surfaces, a computer code for thermal calculation of steam boilers 1 and 2 in TPP Kostolac B has been developed. This software connects calculations of mill facility and control termal calculations of irradiated and convective heating surfaces. This computer code enables the determination of work regimes of boiler as a whole during nominal, reduced and incrased loads, which means determination of temperatures at the inlet and outlet of each heating surface, flow of water injected into lines of superheaters and reheaters, and series of other relevant parameters that define boiler work. Results aquired using software for thermal calculation of steam boilers 1 and 2 in TPP Kostolac B are consistent with corresponding values that were continuously measured during 2011. Consequently, a software verification was carried out by TPP Kostolac. The developed and verified software is primarily designed for examination of impacts of different NOx and SOx emission reduction measures on work efficiency and reliability and safety of steam boiler as a whole.
Dragan Tucaković - Mašinski fakultet u Beogradu , Goran Stupar - Mašinski fakultet u Beogradu , Titoslav Živanović - Mašinski fakultet u Beogradu , Miloš Banjac - Mašinski fakultet u Beogradu , Srđan Belošević - Institut za nuklearne nauke Vinča , Nenad Crnomarković - Institut za nuklearne nauke Vinča , Ivan Tomanović - Institut za nuklearne nauke Vinča , Vladimir Beljanski - Institut za nuklearne nauke Vinča
Pages 961 - 971
Abstract
Parni kotao bloka 2 u TE ”Kostolac” B, snage 350 MW, projektovan je za kostolački lignit donje toplotne moći 7326,9 kJ/kg. Poboljšanje kvaliteta uglja, u odnosu na garantni kvalitet, izazvalo je određene promene u radu kotla koje utiču na njegovu efikasnost. Osim toga, u toku eksploatacije kotla dolazi do variranja pojedinih parametara koji su takođe veoma bitni za pozdan rad, kako kotla, tako i bloka u celini. Naime, veliki uticaj na rad parnog kotla ima položaj jezgra plamena u ložištu (mesta sa maksimalnom temperaturom u ložištu). Da bi sagledali pojedine promene pri radu kotla, nastale povišenjem ili sniženjem temperature dimnih gasova na izlazu iz ložišta, u radu će biti prikazani rezultati termičkog proračuna za nominalno opterećnje kotla pri sagorevanju uglja donje toplotne moći 8373,6 kJ/kg, kako pri projektnom stepenu razdvajanja ugljenog praha od 0,7, tako i pri stepenu razdvajanja ugljenog praha od 0,6 i 0,8. Pri radu kotla sa nominalnom produkcijom, pritisak sveže pare na izlazu iz kotla često je niži od projektnog koji za razmatrani kotao iznosi 186 bar. U tom slučaju zbog promena fizičkih karakteristika pare, dolazi do povišenja temperature pare na izlazu iz pojedinih pregrejača i povećanja protoka vode za ubrizgavanje. Osim toga, na razmatrane temperature pare, kao i količinu vode koja se ubrizgava u liniju sveže pare, bitan uticaj ima i stepen suvoće pare na izlazu iz separatora (flaše), odnosno na ulazu u prvi stupanj pregrejača sveže pare. U cilju ove analize u radu će biti prikazani rezultati termičkog proračuna sa pritiscima sveže pregrejane pare na izlazu iz kotla od 176 bar, 181 bar i 186 bar, takođe pri sagorevanju uglja donje toplotne moći 8373,6 kJ/kg. Steam boiler of block 2 in TPP ”Kostolac” B, power 350 MW, was designed for Kostolac lignite with lower heating value of 7326.9 kJ/kg. The increase in coal quality, compared to the guaranteed quality, caused certain changes in boiler work which affected its efficiency. Beside that, during boiler exploitation, there is varying of certain parameters which are also important for safe work of the boiler. Position of flame in the furnace (place with highest temperature in furnace) has great influence on steam boiler work. In order to perceive individual changes during boiler work, changes created with increasing or decreasing of flue gas temperature at furnace outlet, this paper will show the results of thermal calculation for nominal boiler load, combustion of coal with lower heating value of 8373.6 kJ/kg and degrees of coal dust extraction of 0.6, 0.7, 0.8. During boiler work with nominal load, steam pressure at boiler outlet is often lower than designed, which is 186 bar for this boiler. In that case, because of changes to physical characteristics of steam, there is an increase of steam temperature on certain superheaters and an increase of flow of injection water. Beside that, on the considered steam temperatures and amount of injection water, vapour quality at the separator outlet (inlet of first superheater) has a substantial influece...
Nenad Đ. Crnomarković, Miroslav A. Sijerčić, Srđan V. Belošević - Institute of Nuclear Sciences Vinča, University of Belgrade, P. O. Box 522, 11001 Belgrade, Serbia , Dragan R. Tucaković, Titoslav V. Živanović - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11001 Belgrade, Serbia
Pages 972 - 981
Abstract
Radiative heat exchange is the dominant mode of heat exchange in pulverized coal-fired furnaces. Calculation of the radiative heat exchange depends on radiative properties of the pulverized coal flame, which are determined by the radiative properties of the gas- and dispersed- phases. Radiative properties of the dispersed phase depend on the characteristics of the process inside the furnace, which cannot be precisely determined in advance and which have to be adopted. Investigation of the influence of the adopted characteristics on radiative properties of the pulverized coal flame and radiative heat exchange is the objective of this paper.
Pulverized coal flame is a two phase medium, containing dispersed- and gas-phases. Dispersed phase is made of solid particles, among which the most important are fly-ash particles. Radiative properties of the dispersed phase depend on radiative properties of the single particle, particle size distribution and volume concentration of the particles. Fly-ash particles are formed by three mechanisms: (1) fusion of the mineral matters during the combustion of the particle, (2) break up, or fragmentation of the particle before the end of the combustion, and (3) vaporization and formation of new particles through the homogeneous nucleation. Mineral matters that are transformed in accordance with the first two mechanisms form fly-ash particles whose diameter is from 10.0 to 20.0 micron. Mineral matters that are transformed according to the third mechanism form submicron particles whose diameter is about 0.1 micron. Number of the submicron particles cannot be determined precisely, because vaporized mineral matters are partially condensed on the surface of already formed particles. Influence of the char particles fragmentation on the radiative properties of the dispersed phase was analyzed. On average, one char particle breaks into three to five particles during combustion. Influence of the fragmentation of particles on the absorption and scattering coefficients of the cloud of particles was shown.
Investigation was carried out for the conditions of combustion of Kolubara lignite inside the furnace of the A2 TENT steam boiler. For the chose furnace, the comprehensive mathematical model of the two-phase flow process with chemical reactions and radiative heat exchange was formed. The gas phase was described by the time averaged differential equations of the conservations in the Euler`s field. The pressure field was solved through the SIMPLE model, using the combination of the continuity equation with the momentum conservation equation. System of equations of the gas phase was closed by k-e model of turbulence. The dispersed phase was described by the differential equations in the Lagrangian`s field. Radiative heat exchange was modeled by the Hottel`s zonal model. Radiative properties of the gas phase was determined by the simple gas model. Radiative properties of the dispersed phase were determined by the anomalous difraction method, for the conditions when one char particles forms one, two, three, four and five fly-ash particles. The results of radiative heat exchange using the measured radiative properties of the disperesed phase were also shown.
Vinko L. Babić - Univerzitet u Banjoj Luci, Mašinski fakultet , Titoslav Živanović - Univerzitet u Beogradu, Mašinski fakultet , Žarko Stevanović - Univerzitet u Beogradu, Institut za nuklearne nauke Vinča, Laboratorija za termotehniku i enregetiku , Zdravko N. Milovanović - Univerzitet u Banjoj Luci, Mašinski fakultet
Pages 982 - 990
Abstract
Within this paper the method for numerical simulation of two-phase flow of the mixture between gas and solid particles of the coal powder (aero-mixture) through the coal powder separator has been presented. Inside the simulation the separator itself was considered as a three dimensional model due to its complex geometry. The flow through the coal mill separator of the fan mill VML.210.50 has been taken into consideration and for a fuel the lignite "Dubrave" was chosen. For solving the mathematical model of the flow that has been created the numerical method of control volumes has been performed.
In recent past problems of such type had been solved experimentally and theoretical research had been based on empiric methods. In comparison to that the method applied in this paper has a number of advantages. This way the optimization of the coal powder separation can be accomplished and moreover the optimization of construction of the separator for certain operating conditions.
Apstrakt
U ovom radu se prikazuje numerički način simulacije strujanja dvofazne smješe gasa i čvrstih čestica ugljenog praha (aerosmješa) kroz separator ugljenog praha. Pri tome se separator tretira trodimenzionalno zbog složene geometrije. Razmatra se strujanje kroz mlinski separator ventilatorskog mlina VML. 210.50, a za gorivo je uzet lignit „Dubrave“. Za rješavanje postavljenog matematičkog modela strujanja koristi se numerički metod kontrolnih zapremina.
Do sada su ovakvi problemi uglavnom rješavani eksperimentalno, a teorijska istraživanja su bazirana na empirijskim metodama. U odnosu na njih ovdje primjenjeni metod ima niz prednosti. Na ovaj način se može vršiti optimizacija separacije ugljenog praha, odnosno konstrukcije separatora za date uslove rada.
M.S. Kozić - VTI, Belgrade, Serbia , S.S. Ristić, M.A. Puharić, B.T. Katavić - Institut Goša, Belgrade, Serbia
Pages 991 - 1000
Abstract
This paper presents the results of 3D numerical flow simulation in ventilation mill and air mixture duct of Kostolac B power plant, where centrifugal separators, with adjustable blade angle, are used. Numerical simulations of multiphase flow were performed using the Euler-Euler and Euler-Lagrange approach of ANSYS FLUENT software package. The generated model geometry of the ventilation mill and air mixture duct is faithful to the real model, except the smallest details were omitted because of the limitation of the available memory. An unstructured tetrahedral grid, consisted of 2 630 600 volume and 706 444 surface elements, was generated. The blade angle was changed in the interval of 20º to 60º. The main aim of the numerical simulation was to determine the blade angle influence on pulverized coal distribution at the burners. The results of numerical simulations were compared with measurements in the mills with this type of separators and can be used in order to modify the flow separator geometry to obtain the optimal pulverized coal distribution.
V. B. Beljanski, I. D. Tomanović, S. V. Belošević, M. A. Sijerčić, B. D. Stanković, N. Đ. Crnomarković, A. D. Stojanović - Institute of Nuclear Sciences Vinca, Laboratory for Thermal Engineering and Energy, University of Belgrade, P.O. Box 522, 11001, Belgrade, Serbia
Pages 1001 - 1012
Abstract
Emission of SO2 from coal fired boilers is of great concern to environmental protection. One method for SO2 reduction in coal fired furnaces is direct injection of Ca-based sorbent into the furnace. Numerical analysis given in this paper relates primarily to the lime (CaO) as a sorbent, which are reduced CaCO3 (after calcination) and Ca(OH)2 (after dehydration). This work presents the explanations of physics of complex absorption reaction (sulfation process) when the sorbent injection occurs, deals with modeling problems and implementation of heterogeneous absorption reaction in CFD code. Borgwardt’s model for absorption was selected because it was well balanced (accuracy against calculation time) and didn’t bring additional numerical instability to complex CFD code. Modifications of Borgwardt’s model that are the most common in literature were also analyzed. To verify numerical implementation of adopted model numerous numerical experiments were performed in order to simulate the reactor and experiments that were used by Borgwardt in his work. Due to lack of or insufficient data, addition calculations and numerical optimizations were performed to obtain frequency factor at zero sulfate loading and effectiveness factor for various sorbent sizes. Numerical results were compared against Borgwardt’s experiment and good agreement was obtained. This analysis was very useful because it provided required data and confirmed method of numerical implementation of the selected model. This model for SO2 absorption and method of numerical implementation now can be applied to CFD code that deals with 3D combustion in pulverized coal-fired boiler.
I. D. Tomanovic, V. B. Beljanski, S. V. Belosevic, M. A. Sijercic, B. D. Stankovic, N. Dj. Crnomarkovic, A. D. Stojanovic - Vinca Institute of Nuclear Sciences, University of Belgrade, Mike Alasa 12 – 14 11001, Belgrade, Serbia
Pages 1013 - 1024
Abstract
Modern environmental regulations require the stringent monitoring of emissions of pollutants resulting from combustion of coal and the introduction of appropriate methods in order to reduce their emissions. The cost effective and relatively efficient methods for a sulfur oxides reduction are dry desulphurization processes, such as furnace sorbent injection, suitable for upgrade and extension of the service life of thermal power plants. In order to examine the possibilities for reduction of emission of the sulfur oxides, a numerical model of flue gas desulphurization by direct calcium based pulverized sorbent (specifically limestone, i.e. CaO) injection was developed and incorporated into previously developed CFD code for prediction of processes in furnace of pulverized coal utility boiler. Together with this model, the numerical model for tracking of sulfur oxides formation during pulverized coal combustion process was incorporated. Sulfur oxides formation model is verified by available results obtained by measurements on utility steam boiler of thermal power plant Kostolac B with tangentially fired burner tiers, nominal power 350 MWe. The comparison of results obtained by SO2 emission measurement and results of numerical simulation showed good agreement. The model reflects significant influence of combustion process organization, and the initial amount of sulfur in the coal on sulfur oxides concentration at furnace exit. For numerical investigation of desulphurization process by direct sorbent injection into furnace, special variant of 3D computer code for simulation of furnace processes, with possibility to numerically track particles of pulverized sorbent was developed. Corresponding improvements of user interface were also developed to allow easier variation of process parameters. As base for model of limestone particle sulfation reaction, i.e. reaction of sulfur – dioxide with CaO, Borgwardt’s empirical approach based on the pore concept is adopted, which represents a satisfactory compromise between calculation speed and accuracy of the obtained results, and it was previously validated by comparison with available results from the experimental reactor. Numerical study with selected process parameters, such as Ca/S ratio, injection position, flow and size distribution of sorbent particle, was performed in order to determinate SO2 emission reduction efficiency at the end of furnace of utility boiler Kostolac B. Ratio Ca/S and temperature of flue gas has significant impact on amount of absorbed sulfur, i.e. on sulfation reaction rate. Particular attention was paid to the optimization of pulverized sorbent injection position, which is examined in configuration with injection through pulverized coal line, and/or through special ports in zone above burner tiers close to furnace exit. Such numerical investigation can be base for finding optimal, efficient and cost effective solutions for SO2 emission reduction form power plant boiler furnaces, using just sorbent injection, or combining it with other emission reduction methods.
Goran Vučković - University of Niš, Faculty of Mechanical Engineering, Niš, A. Medvedeva 14, Serbia , Gradimir Ilić - University of Niš, Faculty of Mechanical Engineering, Niš, A. Medvedeva 14, Serbia , Mića Vukić - University of Niš, Faculty of Mechanical Engineering, Niš, A. Medvedeva 14, Serbia , Milan Banić - University of Niš, Faculty of Mechanical Engineering, Niš, A. Medvedeva 14, Serbia , Gordana Stefanović - University of Niš, Faculty of Mechanical Engineering, Niš, A. Medvedeva 14, Serbia
Pages 1025 - 1026
Abstract
The success of methods to increase the energy efficiency, to a large extent depends on the efficiency of individual elements, devices and apparatus, which are in the system. Energy efficiency operation of each of the elements of the system can be achieved with good design, which requires knowledge of the processes that take place in the device. The pipelines are an integral part of every industrial plant.
The objective of this paper is to illustrate the CFD simulation of entropy generation in one part of pipeline for steam transport in complex industrial plant, like a way of reducing irreversibility production in pipelines. The irreversibility of any fluid flow in pipelines is due to two factors, the transfer of heat across the stream to stream temperature difference (heat transfer irreversibility) and the frictional pressure drop that accompanies the circulation of fluid through the apparatus (fluid friction irreversibility).
In this paper the pipeline for steam transport in rubber industry is analysed. The superheated steam at the pressure 10 bar is a fluid that transfers the energy from the steam boiler to the apparatus in the factory. For a defined geometry of pipeline, the model was created, and as results are represented the fields of local entropy generation due to heat transfer and fluid friction, and the total entropy generation in the pipeline.
The minimum values of the local entropy generation rate in the steam flow meter (2.801x10-7 W/m3K and 6.274x10-7 W/m3K) are obtained in the core of fluid at the straight part of pipeline with constant cross-section. The maximum values (1.705 W/m3K and 14.360 W/m3K) are occurs near the wall. In the case of pipe curve at 90º turns the local entropy generation rate has a minimum values (3.223x10-10 W/m3K and 4.730x10-10 W/m3K) in the core of stream in the inlet of curve, and maximum values (1.733 W/m3K and 14.580 W/m3K) near the wall due to heat transfer and friction between the fluid and the wall. On the entropy generation has a dominant influence of irreversibility due to friction in comparison to the irreversibility caused by heat transfer.
Ljubo Maćić - Energy Agency of the Republic of Serbia, Belgrade, Serbia
Pages 1027 - 1028
Abstract
Security of supply and energy prices are two extremely important, interconnected components of the energy policy of any country. The energy sector of Serbia is facing huge changes and their success will depend on pricing policy. Most of the provisions of the 2011 Energy Law will be applied in 2013. Big electricity and natural gas customers will enter the market. Safe energy supply in the years to come asks for huge investments in new capacities which will cover energy consumption growth and replace the plants which will be gradually out of operation. Market opening and pricing policy which should create the conditions for a long-term security of supply and contribute to rational use of energy were considered.
Apstrakt
Sigurnost snabdevanja i cene energije su dve izuzetno važne, medjusobno povezane, komponente energetske politike svake zemlje. Energetski sektor Srbije ulazi u velike promene, čiji uspeh će bitno zavisiti od politike cena. U 2013. godini primeniće se najveći deo odredbi Zakona o energetici donetog 2011. godine. Na tržište će izaći veliki kupci električne energije i prirodnog gasa. Za pouzdano snabdevanje energijom u narednim godinama neophodne su velike investicije u nove kapacitete, kojima će se pokrivati rast potrošnje energije i zamenjivati elektrane koje će izlaziti iz pogona. Razmatrani su otvaranje tržišta i politika cena koja treba da obezbedi uslove za dugoročnu sigurnost snabdevanja i doprinese racionalnoj potrošnjii energije.
Mr Nikola Počuča - ENBIMA Institut, Beograd , Prof. dr Gordana Dražić - Fakultet za primenjenu ekologiju FUTURA, Univerzitet Singidunum, Beograd
Pages 1029 - 1036
Abstract
The world tends to reduce the green house effect by stabilizing the emission of CO2. In order to achieve this goal it is necessary to use renewable energy sources like biomass. The production of biomass and its thermal treatment – acquisition of energy – represent a closed CO2 cycle, since the amount of CO2 which is released during the burning, is the same amount which is taken by the plants in the growing phase. The quantity and usage of biomass show a great potential for already existing electrical and thermal power plants. It is shown that through the substitution of fossil fuels with biomass there is an immense reduction in the dependable emission of CO2. For the usage of biomass all burning techniques can be taken into account. Same power plants would need only a small amount of investing. It is necessary to switch to biomass as soon as possible, especially on smaller scale and co-generative power plants. The usage of biomass should be favored, but also solutions for the problems in the burning process have to be resolved.
Apstrakt
Smanjenje efekta stakene bašte kroz stabilizaciju emisije CO2 se postiže korisšćenjem obnovljivih izvora energije, prvenstveno biomase. Proizvodnja biomase i njeno sagorevanje u cilju dobijanja energije predstavljaju zatvoren CO2 ciklus, jer se u fazi rasta biljaka iz vazduha izvlači količina CO2 koja se ponovo oslobodii pri spaljivanju iste. Produkcija i upotreba biomase pokazuje zavidan potencijal za postojeća postrojenja za proizvodnju električne i toplotne energije. Pokazuje se da supstitucijom fosilnih goriva biomasom se znatno smanjuje pritisak na životnu sredinu u odnosu na korišćenje fosilnih goriva. Za korišćenje biomase principijelno odgovaraju sve tehnike sagorevanja, a samo negde su potrebna relativno mala do-investiranja kroz redizajniranje procesa. Najpogodnija su mala i kogenerativna postrojenja ali za postizanje značajnih efekata na smanjenje produkcije gasova sa efektom staklene bašte je neophodno da se favorizuje korišćenje biomase, otpadne ili namenski proizvedene, u velikim postrojenjima. Za ovo je potrebna široka akcija sa ciljem rešavanja, još uvek mnogobrojnih, problema u lancu pribavljanja i korišćenja biomase kao obnovljivog izvora energije. Ključne reči: biomasa, emisija CO2, supstitucija fosilnih goriva, ekološke prednosti.
Dejan Momčilović1, Ivana Atanasovska2 Radivoje Mitrović3 - 1 Institute for testing of materials IMS, Bulevar vojvode Misića 43, 11000 Belgrade, Serbia, dejanmomcilovic@yahoo.com
Pages 1037 - 1038
Abstract
Abstract.
Energy efficiency is today one on key questions, not for engineers only buth rather to whole mankind. The failures of various parts of mechanical systems engaged in electric power insdustry abd their analysis are the lessons that should be learned thoroughly. Every behavior of structure beyond design envelope or inexpected conditions must be examined carefully in order to minimise future losses and subsequently increase energy efficiency. New and better design procedures or procedures that will gain more accurate results are major request to engineers and researchers last few decades. The importance of properly done failure analysis sometimes presents the basis for repair and retrofitting, All that actions shoud be carefuly planned with respect to facts drawn from particular analysis of mechanical system.
A case study from hydro power turbine shaft plant was chosen as subject for developed methodology of comprehensive failure analysis presentation. This paper illustrates the application of some new methods on the assessment of decrease of fatigue life of turbine shaft due to stress concentration on corrosion pits on shaft to flange radius. In the paper the inability to solve the problem by classic approach in mechanical design is discussed, too. The main conclusion of paper is that without specific type of knowledge it is not possible to accomplish the failure analysis with complete set of results and conclusions.
Gordana Kastratović - University of Belgrade, Faculty of Transport and Traffic Engineering, Vojvode Stepe 305, 11000 Belgrade, Serbia , Nenad Vidanović - University of Belgrade, Faculty of Transport and Traffic Engineering, Vojvode Stepe 305, 11000 Belgrade, Serbia , Vukman Bakić - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, PO.Box 522, 11000 Belgrade, Serbia , Milada Pezo - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, PO.Box 522, 11000 Belgrade, Serbia , Zoran Marković - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, PO.Box 522, 11000 Belgrade, Serbia
Pages 1039 - 1048
Abstract
The guyed masts are used for meteorological measurements, wireless communication or for power transmission. Those are flexible structures which are subjected to fluid flow, so it is necessary to model both the structure and the fluid. In this paper the emphasis is set on the structural analysis, as it discusses the problem of triangular cross-section optimization of the tower lattice structure of an 80 m tall guyed mast, which consists of 13 segments with four levels of guys and a ground exposure. The guyed mast was subjected to different wind load conditions. The behavior of the mast is non-linear due to its slenderness and compliant guyed-support system. The optimization is achieved by usage of the commercial finite element software ANSYS. The minimal total mass of the construction has been selected as the objective function, while the criterion of the stress was used as the constraint function. The obtained results were analyzed, in order to provide better understanding, and hence prediction, of the structural behavior of the guyed masts.
Milena Milojević - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Nikola Krajnović - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Vesna Petkovski - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Đorđe Čović - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija
Pages 1049 - 1050
Abstract
Abstrakt: Simulatori i trenažeri predstavljaju moderan vid obuke osoblja u elektroenergetskim postrojenjima. Pogodnosti koje ovakav sistem omogućava se ogledaju u zadržavanju svih manipulativnih operacija koje DCS pruža bez opasnosti po opremu termoelektrane. Realizovani AMEG Simulator-trenažer obuhvata model termobloka i DCS-a koji njime upravlja. Razvijeni model tehnološkog procesa je zasnovan na fizičkim zakonima koji definišu ponašanje realnog objekta. Obuhvaćeni su svi segmenti: dopremanje i sagorevanje goriva, kretanje vazduha i dimnog gasa, vodeno-parni podsistem, turbinsko postrojenje. Takođe, simulirani su i svi aktuatori: ventili, klapne, ventilatori, pumpe itd. U radu je detaljno prikazan model vazdušnog i dimnog trakta kotla u okviru AMEG sistema bloka A4 termoelektrane „Nikola Tesla” u Obrenovcu. Modelirani su svi pritisci i protoci vazduha i dimnog gasa u postrojenju korišćenjem analogije procesa sa električnim kolom. Rešavanje kola je realizovano iterativnim izračunavanjem diferencnih jednačina definisanih tako da se sistem jednostavno prilagođava promenama strukture. Nepoznati parameti jednačina su dobijeni na osnovu mehaničkih podataka o termobloku i optimizacijom pomoću postojeće arhive podataka snimljene na realnom sistemu. Identifikacija je izvedena gradijentnim iterativnim algoritmom. Verifikacija modela je pokazala da realizovani model realno oslikava ponašanje procesa u svim režimima rada.
Abstract: Simulators and training machines are the modern form of personnel specialization in power plants. The benefits that this system provides are reflected in the retention of all handling operations that DCS enables without threat to the factory equipment. Implemented AMEG Simulator-training machine includes power plant model and corresponding DCS model. The developed model of the technological process is based on physical laws that define the real object behavior. This covers all segments: fuel delivery and combustion, air and flue gas flow, water-steam subsystem, turbine. Also, all actuators are simulated: valves, dampers, fans, pumps, etc. The paper presents a detailed model of steam boiler fresh air and flue gas tract within the AMEG system of power plant "Nikola Tesla" block A4 in Obrenovac. The all fresh air and flue gas pressures and flow rates are modeled using the analogy with electrical circuit. Solving circuit is performed by an iterative calculation of difference equations defined so that the system adapts easily to structure changes. Unknown equation parameters are obtained from the power plant mechanical data and from optimization based on existing data archives recorded on a real system. Identification was performed using an iterative gradient algorithm. The model verification shows that the implemented model realistically depicts behavior of the process at all work regimes.
Nebojša Radmilović - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Ivan Nikolić - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Ljubiša Jovanović - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija , Nebojša Panjevac - Institut „Mihajlo Pupin - Automatika”, Volgina 15, Beograd, Srbija
Pages 1051 - 1052
Abstract
Abstrakt: Parna turbina termoelektrane predstavlja nelinearan objekat upravljanja, zbog specifičnosti svoje konstrukcije u pogledu realizacije parnih ventila na ulazu u turbinu, kao izvršnih organa upravljanja. Pri tome parametri sistema su promenjivi u zavisnosti od pogonskog stanja u kome se turbopostrojenje nalazi. Stoga se pojavila potreba za analizom ponašanja sistema primenjujući adaptivne tehnike automatskog upravljanja. Pri tome uvođenjem distribuiranih sistema upravljanja, uz upotrebu kontrolera jednostavnih za programiranje, omogućena je realizacija ovakvih tehnika upravljanja na realnim sistemima. Zahtevi za stabilnošću i pouzdanošću celog sistema, a samim tim pogotovo i automatskog algoritma upravljanja, su izuzetno strogi, te je neophodno pre puštanja u rad uraditi detaljne analize za koju vrstu, adaptivnih algoritama upravljanja se treba odlučiti. U ovom radu su prikazane dve metode adaptivnog upravljanja poznate kao „MIT pravilo“ [1] i „SPR“ [2]. Poređenje je urađeno na nelinearnom modelu parne turbine snage 210MW, prilikom automatske regulacije broja obrtaja. Ovaj simulator je korišćen za fabrička primo-predajna ispitiavnja sistema turbinskog regulatora. Za ovu vrstu turbina je karakteristična kruta sprega između ventila visokog i niskog pritiska, gde dolazi do oteženog rada regulacije zbog pare koja ostaje zarobljena u međupregrejačima prilikom brzog zatvaranja svih regulacionih ventila i koja daje pogonski momenat turbini srednjeg pritiska.
Abstract: Steam turbine in thermal power plants is nonlinear control object, due to the specificity of its construction in terms of realization of steam valves at turbine entrance, as well as control actuators. At the same time, system parameters are changeable depending on the operating state of turbine facility. It is therefore a need to analyze the behavior of system, if is applied adaptive techniques of automatic control. Also, introduction of distributed control system, using controllers simple for programming, enables implementation of these control techniques at real plant. The requirements for stability and reliability of the whole system, especially the automatic control algorithm, are very strict. According to this, it is necessary to do detailed analysis of different adaptive control algorithms and decide which one is the best for this application, before commissioning. This paper presents two methods of adaptive control known as „MIT rule“ [1] and „SPR“ [2]. The comparsion is done on nonlinear model of steam turbine wich has 210MW power, at part of automatic speed control. This simulator is used for factory acceptance tests of turbine governor system. In the turbines of this type, with rigid coupling between high and intermediate pressure valves, a special disturbance is present because of the steam that remains trapped in the middle reheaters, which is caused by the fast closing of the control valves, and gives momentum to intermediate turbine.
Vukman Bakić, Saša Stojković - 1. University of Belgrade, Institute Vinča, Laboratory for Thermal and Energy Research, Belgrade, Serbia, 2. University of Kragujevac, Technical Faculty, Čačak, Serbia
Pages 1053 - 1062
Abstract
The dynamic analysis of a combined wind-photovoltaic power system for power supply of meteorological mast is presented. Meteorological mast contains electronic equipment for measuring the wind speed and direction, as well as turbulence intensity. The logger, modem and aviation security luminaries are also typical load. The mast is practically always alone and very far from distribution network. Due to that reason, the mast needs stand-alone power source. The analysis is based on transient simulation tool TRNSYS 16 and it has done for Typical Meteorological Year for one site with meteorological mast erected. The power system consists of photovoltaic (PV) panel, small wind generator, battery, charge controller and inverter. The main goal of the study is to determine system’s elements in optimized way. The reliability of supply should be very high because of air aviation hazard at night. It is shown in the paper that this goal can be achieved successfully.
U radu je prikazana dinamička analiza hibridnog vetar-solarnog sistema za napajanje meteorološkog stuba. Meteorološki stub sadrži elektronsku opremu za merenje brzine i pravca vetra, kao i intenziteta turbulencije. Sistem za akviziciju podataka, modem i sigurnosne svetiljke takođe predstavljaju električno opterećenje. Stub je praktično uvek usamljen i daleko od distributivne mreže. Iz tog razloga, neophodan mu je samostalan električni izvor snage. Analiza je zasnovana na primeni softverskog alata TRNSYS 16, a izvedena je za tipičnu meteorološku godinu na mestu gde je podignut jedan meteorološki stub. Sistem za napajanje sastoji se od PV panela, malog vetrogeneratora, baterije, kontrolera punjenja i invertora. Osnovni cilj analize je da se elementi sistema odaberu na optimalan način. Pouzdanost napajanja treba da bude velika zbog opasnosti po letelice u toku noćnog leta. U radu je pokazano da se to može izvesti na zadovoljavajući način.
Andrijana D. Stojanović, Srđan V. Belošević, Branislav D. Stanković, Nenad Đ. Crnomarković, Ivan D. Tomanović, Vladimir B. Beljanski - Institut za Nuklearne nauke Vinča
Pages 1063 - 1073
Abstract
Novi propisi o graničnim vrednostima emisije zagađujućih materija iz postrojenja za sagorevanje fosilnih goriva zahtevaju strožu kontrolu sumpor dioksida (SO2), praškastih materija, ugljen-monoksida (CO2) i oksida azota (NOx). Suvi postupci odsumporavanja dimnih gasova predstavljaju moguće rešenje za redukciju emisije sumpor-dioksida sa malim početnim troškovima koji mogu doprineti produženju radnog veka postojećih postrojenja. U ovom radu su razmotreni suvi postupci odsumporavanja dimnih gasova kotlova na sprašeni ugalj u svetlu dostignuća i primene komercijalnih postrojenja i procesa za kontrolu emisije sumpor-dioksida. Posebno se opisuju tehnologije sa sorbentima na bazi kalcijuma kao što su: odsumporavanje direktnim unošenjem sorbenta u ložište, unošenjem sorbenta u kanal iza zagrejača vazduha ili u za to posebno projektovan reaktor kao i suvi sistem sa raspršivanjem. Rad završava diskusijom o efikasnosti i ekonomičnosti opisanih postupaka u poređenju sa drugim postupcima odsumporavanja. Cilj je da se ukaže na prednosti i nedostatke suvih postupaka odsumporavanja i pomogne istraživačima i inženjerima u izboru optimalnih rešenja sistema za odsumporavanje kod već postojećih ili novih termoelektrana. Izbor metode je često zasnovan na poređenju cene primene metoda. Stoga su za opisane tehnologije dati prosečni troškovi redukcije emisije i istaknute one najefikasnije
Nikola Mirkov - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija , Vukman Bakic - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija , Milada Pezo - Laboratorija za termotehniku i energetiku, Institut za nueklarne nauke „Vinca“, Univerzitet u Beogradu, Srbija , Sasa Kenjeres - Department of Multi-scale Physics, Delft University of Technology, Delft, The Netherlands
Pages 1074 - 1082
Abstract
U ovom radu predstavljamo numericke simulacije turbulentnih strujanja vazduha nad kompleksnim realnim terenom. Realisticnost predstavljanja topografije je obezbedjena zahvaljujuci upotrebi postojecih digitalnih modela elevacije terena. Simulacije su izvedene u visokoj rezoluciji. Istrazeni su uticaji neravnomernosti terena na strujnu sliku. Ovo je ostvareno korekcijama matematickih modela turbulentnih strujanja koji obezbedjuju fizicku ostvarivost rezultata putem ogranicavanja izvornih clanova za kineticku energiju turbulencije. Jedna od ispitanih korekcija je Durbinova korekcija ogranicenja za vremensku razmeru turbulentnih fluktuacija. Ovako definisana korekcija sprecava prekomerno nastajanje turbulentne kineticke energije u stagnacionim regionima strujanja, koje je prisutno u mnogim modelima turbulencije. Durbinova korekcija ogranicenja vremenske razmere je primenjena u sklopu RNG verzije dvojednacinskog k-ε modela. U proracunima smo koristili sopstveni program za simuliranje nestisljivih strujanja. Metod diskretnog resavanja Navije-Stoksovih jednacina je zasnovan na metodi konacnih zapremina. Program je paralelizovan i omogucava proracune kompleksih geometrija prihvatajuci mreze struktuirane po blokovima. Rezultati proracuna su uporedjeni sa postojecim podacima sa merenja na atmosferskoj razmeri. Rezultati daju uvid u to, kako ukljucivanje raznih efekata fizike turbulentnih strujanja pomaze u predvidjanju strujanja u zivotnoj sredini od prakticnog interersa. Pristup koji prikazujemo ima za poseban cilj primenu u energetskom sektoru, u procesu odabira lokacije za postavljanje farmi vetra koje bi optimizovale proizvodne kapacitete vetro-parkova.
Vujo I. Miljevic - Institut Vinca
Pages 1083 - 1092
Abstract
Abstract: Za odstranjivanja sumpor dioksida (SO2) i azotnih oksida (NOx) su praktično razvijene tehnologije. Međutim, još uvek ostaje ugljen dioksid (CO2), koji je takođe sastavni deo dimnog gasa - ali gasa sa efektom staklene bašte.
Japanska kompanija Tokyo Gas Co. Ltd., za odstranivanje CO2 koristi smešu CO2 i vodonika na visokoj temperaturi (550 K) i visokom pritisku (9MPA), kada se dobija kao sporedni proizvod metanol. Ova tehnologija ima malu efikasnost. Metanol je od velikog značaja za hemijsku industriju, a smeša sa benzinom se koristi za automobilske motore. To su samo neke od primena
metanola.
U Institutu za nuklearne nauke "Vinča", u Laboratoriji za atomsku fiziku, sa radi i na razvoju primene ELFI tehnologije za otklanjanje CO2 iz dimnih gasova. Pošto je ELFI tehnologija plazma hemijska tehnologija, u literaturi se može naći primena plazma hemijske tehnologije u raznim oblastima istraživanja. To znači da istraživanja CO2, pored otklanjanja "efekta staklene bašte" imaju veliki energetski značaj. Korišćenje metanola predstavlja jedan od najefikasnijih metoda za smanjenje CO2, jer se u procesu dobijanja metanola koristi CO2. Pored ostalog, metanol na neki način predtavlja "izvor nafte".
Današnja moderna industrijska postrojenja procesuju velike količine dimnih gasova, uključujući i CO2. ELFI plazma tehnologija omogućava procesovanje gasova iz modernih industrijskih postrojenja - nemaju "scale-up" ograničenja.
Plazma hemiski metod odstranjivanja CO2 se radi u Institutu za nuklearne nauke "Vinča" u Laboratoriji za atomsku fiziku.
Dragan P. Dabić, Branka B. Kostić*, Miljana Z. Zindović, Goran Č. Đukić, Marko G. Gostović, Pavle N. Krička**, Vukašin Đ. Masnikosa, Srđan Z. Zdravković*** - Uni. of Belgrade, Electrical Engineering Institute “Nikola Tesla”, Belgrade, Koste Glavinića 8A* “Saturn Elestric”, Belgrade, Inženjera Kapusa 6** PE “Electric Power Industry of Serbia”, Belgrade, Vojvode Stepe 412***
Pages 1093 - 1108
Abstract
This paper presents a detailed model of power plant with corresponding protection for all facility elements and their settings, which are created within CAPE software. Selectivity has been analyzed up to the main fuses in switchboards 0.4 kV. The power plant model is a part of a complete model of southeast European power system, which is imported from PSS software. Relay parameter settings have been analyzed for the few switching schemes. Simulations of the faults on 400 kV lines indicated that the adjustment of some protective devices is inadequate. It was also indicated that some parameters of protective devices can not be adjusted to desired values. For a phase-to-ground fault (through the large resistance) on the transmission line RP Djerdap 1 - Drmno, fault clearing is done by switching off the block - transformer breaker instead of switching off line breaker. For a large number of faults on the 400 kV lines, unnecessary reaction of the undervoltage relays at 6.3 kV feeders have been noted. Due to this reaction, 6 kV motor breakers for pumping stations should be switched off. For the faults (three phase, two-phase and two-phase to earth) at any 6.3 kV cable feeder, undervoltage protection of 6.3 kV motors (connected to the same bus as faulted feeder) reacts too fast. It was found that the time delay of this protection should be increased (e.g. 350 ms), in order to be higher than time delay of the rapid second zone of the distance protection, if it is acceptable in terms of technical characteristics of the protected motor. These motors have no influence on the technological process of electricity generation in hydro power plant Djerdap 1. Actual settings of the overcurrent protection of the own consumption transformer do not provide its adequate overload protection. For the faults (three-phase, two phase and double-phase-to-ground) on the main 6.3 kV bus or cable connected feeders, protection of the own consumption transformer is non- selective, which causes unnecessary tripping of the 0.4 kV own consumption. For the phase-to-ground faults in 6 kV network, protection does not respond. Three-phase, two phase and double-phase-to-ground faults on the main 10 kV bus in Sip causes turning off the entire transformer T2. Based on the fault simulation, suggestions for readjustment of the non-selective and/or uncoordinated (with the basic protection of individual elements) relays have been given. It was also proposed that relays, which can not be adjusted to meet necessary conditions for coordination, reliability and selectivity, should be replaced. Mechanical and thermal damage curves of the transformer for the critical faults, are also shown.
Branka B. Kostić, Dragan P. Dabić*, Miljana Z. Zindović, Goran Č. Đukić, Marko G. Gostović, Pavle N. Krička**, Vukašin Đ. Masnikosa, Srđan Z. Zdravković*** - Electrical Engineering Institute “Nikola Tesla”, Uni. of Belgrade, Belgrade, Koste Glavinića 8A* “Saturn Elestric”, Belgrade, Inženjera Kapusa 6** PE “Electric Power Industry of Serbia”, Belgrade, Vojvode Stepe 412***
Pages 1109 - 1124
Abstract
For purposes of analysis of protection system selectivity in PP “Kostolac A” detailed model was created using the software package CAPE. The model includes the protection of all existing elements and their settings and is associated with a complete model of Southeastern Europe network, imported from the PSS. Selectivity was tested up to the main fuses in switchboards 0.4 kV. Relay parameter settings were analyzed for a few switching schemes. Based on the fault simulations, suggestions for readjustment of the non-selective and/or uncoordinated relays (with the basic protection of individual elements) were presented. It was also proposed that relays, which can not be adjusted to meet necessary conditions for coordination, reliability and selectivity, should be replaced. As an illustration of applied analysis, the results of some simulations are presented in tabular form and for the critical faults mechanical and thermal damage curves of the transformer are also shown.
Željko Gagić, Mihailo Nikolić, Savo Bezmarević, Nemanja Samardžić; Nebojša Radmilović, Nikola Krajnović, Vanja Čukalevski - “ Termoeletrana Nikola Tesla A”- Obrenovac; “Institut Mihajlo Pupin“- Beograd
Pages 1125 - 1125
Abstract
Simulatori rada termoenergetskog postrojenja imaju veoma važnu ulogu u toku razvoja i optimiranja algoritama u novim ili modernizovanim sistemima za upravljanje i regulaciju, kao i u toku testiranja opreme tih sistema u fazi proizvodnje ili kod uspostavljanja konfiguracije na objektu. U procesu održavanja i eksploatacije termoenergetskog postrojenja omogućuju obuku i uvežbavanje procedura u svim pogonskim situacijama, posebno u poremećenim stanjima koja se u realnim uslovima ne dešavaju često. Osnova takvih simulatora su dobro kalibrisani dinamički matematički modeli elemenata postrojenja. U radu je prikazan model jedne jednoosovinske kondenzacione parne turbine sa međupregrevanjem pare, i tehnološkim podsistemima koji imaju zanačajan uticaj na dinamiku turbinskog postrojenja u tranzijentnim stanjima, od kojih su najvažniji bajpasi visokog i niskog pritiska.
Branislav Stanković*, Miroslav Sijerčić*, Srđan Belošević*, Svetislav Čantrak** - Institut za nuklearne nauke „Vinča“, Univerzitet u Beogradu, Laboratorija za termotehniku i energetiku, Mihajla Petrovića Alasa 12-14, p. fah 522, 11001 Beograd, Srbija* Mašinski fakultet Univerziteta u Beogradu, Kraljice Marije 16, 11120 Beograd 35, Srbija**
Pages 1126 - 1127
Abstract
Definisanje graničnih uslova na zidu koji se opisuju zidnim funkcijama predstavlja značajan problem i zahteva posebno razmatranje. Najčešći pojedinačni uzrok zbog kojeg program može da ne konvergira ka rešenju ili da konvergira ka pogrešnom rešenju je neodgovarajuća postavka graničnih uslova ili njihova pogrešna ugradnja. Za praktične probleme i kompjutersko-inženjerske proračune, kako kod strujnih tako i kod strujno-termičkih procesa, koncept zidnih funkcija ima važnu ulogu. Glavni cilj ovog rada je da se otkrije šta je to u vezi sa turbulentnim strujanjem u neposrednoj blizini zida što prouzrokuje teškoće, u delu problema koji se odnosi na modeliranje turbulencije. Sloj fluida u kojem je uticaj viskoznosti prisutan postavlja niz pitanja i problema koje je potrebno rešiti i sa aspekta modeliranja i sa numeričkog aspekta. Razlog je u činjenici da su zbog prisustva čvrste granice karakteristike strujanja fluida i turbulentnih struktura znatno drugačije u odnosu na slobodne turbulentne tokove. U samoj blizini zida, u veoma tankom sloju fluida, dolazi do vrlo izraženih promena (velikih gradijenata) osrednjenih i turbulentnih strujnih veličina, prema eksperimentalnim merenjima i DNS podacima. U ovom tankom sloju koji prianja uz zid, turbulentne veličine se menjaju brže za nekoliko redova veličine u poređenju sa strujanjem van tog regiona. Pored toga, turbulentne fluktuacije se veoma razlikuju u različitim pravcima – turbulentno strujanje je izrazito anizotropno u blizini zida. Poseban tretman ove zone uz zid je neophodan zato što se jednačine koje opisuju strujanje fluida ne mogu rešiti do samog čvrstog zida u svom izvornom obliku – moraju se modifikovati pomoću zidnih funkcija – zbog složene strukture strujanja koju karakterišu nagle promene osrednjenih i turbulentnih veličina na veoma malom prostoru u neposrednoj blizini zida. Od velikog je značaja da se postave u fizičkom smislu realni, dobro zasnovani granični uslovi, inače može doći do ozbiljnih teškoća u procesu dobijanja rešenja jednačina. Osim toga, primenom koncepta zidnih funkcija postižu se značajne uštede kako u pogledu kompjuterskog vremena potrebnog za proračun, tako i u pogledu kompjuterske memorije.
Milada Pezo - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, P.O.Box 522, 11000 Belgrade, Serbia , Vukman Bakić - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, P.O.Box 522, 11000 Belgrade, Serbia , Zoran Marković - University of Belgrade, Vinca Institute of Nuclear Science, Laboratory for Thermal and Energy Research, P.O.Box 522, 11000 Belgrade, Serbia , Gordana Kastratović - University of Belgrade, Faculty of Transport and Traffic Engineering, , Nenad Vidanović - University of Belgrade, Faculty of Transport and Traffic Engineering,
Pages 1128 - 1137
Abstract
The guyed masts are made of thin, light, steel beam elements which have flexible structures and they are relatively less stable than other structures. The beam element is suitable for analyzing slender to moderately stubby/thick beam structures. For a guyed mast, wind load is the main factor affecting the stability of the structure. Therefore, a proper evaluation of the response due to wind action may decrease the occurrence of failure. In this paper is analyzed the tower, an 97 m tall guyed mast which consists of 16 segments (6 m length each) and one segment, 1 m length which is connected to the ground, with four levels of guys and a ground exposure. The guyed mast was subjected to different wind load conditions. The analysis is achieved by using of the commercial finite element software ANSYS. The commercial finite element software ANSYS was used for finite element modeling and numerical simulation of a thin-walled guyed mast structure response to dynamic wind action.
Goran Živković*, Dragoljub Dakić**, Nedžad Rudonja***, Branislav Repić - *Vinča Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy **Innovative Center of the Faculty of Mechanical Engineering, Belgrade ***Faculty of Mechanical Engineering, University of Belgrade
Pages 1138 - 1149
Abstract
Introduction of thermal storage tanks (TST) in facilities that use renewable energy resources represents a good way to increase their energy efficiency. This paper surveys a part of the activities (performed during the realization of the second year of project III 42011 financed by the Ministry of education and science of the Republic of Serbia) on the development of TST whose storage medium melts at the atmospheric pressure, enabling on that way the use of the energy of phase change for energy storage. TST of this type enable more thermal energy storage per volume unit, but also (depending of the working medium) enable higher temperatures of the working medium, which is necessary in the co-generated facilities. For the development of the numerical model of heat transfer and fluid flow processes in TST a commercial numerical package Fluent 12.1 was used, since it possesses its own routine for computation a temperature and flow fields in TST with the change of phases, but also it enables to user to implement the package with its own model by using the user define functions. For the purpose of the experimental research of thermal and flow processes in TST in the Laboratory for thermal engineering and energy of the Vinča Institute a prototype of TST was designed and made. It has a cylindrical shape, with the working volume of 77 dm3. The working material is heated by 3 kW electric heater positioned along the TST axes, and is cooled by the air which circulates around the tank. The measurement of temperature inside the tank was performed by 16 thermocouples, 4 along the tanks height and 4 along the tanks radius. For the purpose of this work a paraffin as a working medium was used. Measurements and the numerical computation were performed for non-stationary as well as for stationary working regimes. A good agreement between the numerical and experimental results was achieved, which showed that the developed model represents a good basis for its further improvement and use in the case of more complex geometries, taking into account flow processes inside the tank as well. Key words: energy storage tank, measurements, numerical model, phase change Jedna od mogućnosti za povećanje energetske efikasnosti postrojenja, pogotovo onih koja koriste obnovljive izvore energije, jeste i skladištenje energije u akumulatorima toplote (AT). U radu je prikazan deo aktivnosti (u okviru projekta III 42011 Ministarstva prosvete i nauke Republike Srbije) na razvoju AT sa ispunom kod koje postoji mogućnost promene faze na atmosferskom pritisku, te iskorišćenja toplote faznog prelaza za skladištenje toplotne energije. Ovakvi tipovi AT, pored toga što omogućavaju veću akumulaciju energije po jedinici zapremine AT, kao i mogućnost lakšeg održavanja radnog medijuma na određenoj temperaturi, takođe omogućavaju i više temperature medijuma za skladištenje energije, što je neophodno pri radu postrojenja sa kombinovanim ciklusom. Za razvoj numeričkog modela strujno-termičkih procesa u AT korišćen je komercijalni CFD paket Fluent 12.1, koji poseduje moduo za proračun strujanja sa promenom faze, i koji je po potrebi bio
Stevan Đ. Nemoda, Milica R. Mladenović, Aleksandar M. Erić, Dejan M. Đurović - University of Belgrade, Institute of Nuclear Sciences "Vinča", Laboratory for Thermal Engineering and Energy P. O. Box 522, 11001 Belgrade, Serbia , Dragoljub V. Dakić - Univ. of Belgrade, Faculty of Mech. Engineering, Innovation Centre, Kraljice Marije 16, 11120 Belgrade 35, Serbia , Mirko S. Komatina - University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, 11120 Belgrade, Serbia
Pages 1150 - 1169
Abstract
The paper deals with the development of mathematical models for detailed simulation of lateral jet penetration into the fluidized bed (FB), primarily from the aspect of feeding of gaseous and liquid fuels into FB furnaces. For that purpose a series of comparisons of the results of a previously developed procedure - fluid-porous medium numerical simulation of gaseous jet penetration into the fluidized bed, Fluent’s two-fluid Euler-Euler FB simulation model, and experimental results (from the literature) of gaseous jet penetration into the FB, were conducted. The suggested procedure of FB modelling has been primarily applied to 2D numerical simulation of lateral jet injection of the fluid into the FB, which includes determination of the jet penetration length. Fluent’s two-fluid Euler-Euler model, which includes the kinetic theory of granular flow, is also applied to the numerical simulation of lateral fluid jets into the FB. The drag coefficient between fluid and granular phases is defined by applying Syamlal-O'Brien model. The results of calculations using the proposed models are compared with the experimental results taken from available references, which included a series of measurements of the lateral jet penetration length into the 2D model of the fluidized bed using video cameras. The calculation results, using both models, and experimental data are in good agreement. The results of calculations and experiments are compared with a range of correlations, i.e. semi-empirical dependences found in the literature, of the jet penetration length into the FB as a function of jet velocity.
The developed simulation procedures of jet penetration into the FB were applied to the analysis of the effects, which is registered during the experiments on a fluidized pilot furnace with feeding of liquid fuels into the bed. The experiments have shown that the intense combustion zone is shifted to areas deeper below the bed surface layer during the combustion of liquid fuels with significant water/moisture content, compared to moisture-free fuel. Registered effect suggests that the water in the fuel increases the global reaction rate of combustion in the FB furnace with lateral fuel feeding into the bed. This phenomenon has also been observed with high and low volatile liquid fuels and can be explained by increasing the volumetric flow rate of fuel feeding into the bed, due to the transition of water from the fuel into steam. In order to clarify this effect, numerical simulations of jet penetration into the FB with three-phase systems: gas (fuel, oxidizer, and water vapour), bed particles and the water (which turns to steam at the nozzle exit), have been carried out. The case of combustion of fuel with high volatile content has been analyzed by simulating the penetration of the jet containing volatile components of the fuel and water in a liquid state (which rapidly evaporates in the combustion chamber), while the case of a low volatility fuel has been considered by jet simulation, with the jet consisting of oil and water mixture. All calculations are non-stationary and they model the first moments of jet formation.
D.Djurovic - University of Belgrade, Institute of Nuclear Sciences ‘‘Vinca’’, Laboratory for Thermal Engineering and Energy, P.O. Box 522, 11001 Belgrade, Serbia , S.Nemoda - University of Belgrade, Institute of Nuclear Sciences ‘‘Vinca’’, Laboratory for Thermal Engineering and Energy, P.O. Box 522, 11001 Belgrade, Serbia , B.Repic - University of Belgrade, Institute of Nuclear Sciences ‘‘Vinca’’, Laboratory for Thermal Engineering and Energy, P.O. Box 522, 11001 Belgrade, Serbia , D.Dakic - University of Belgrade, Faculty of Mechanical Engineering, Innovation Centre, Kraljice Marije 16, 11120 Belgrade 35, Serbia
Pages 1170 - 1178
Abstract
The issue of renewable sources is becoming topical in Serbia, and in particular it will become important in the country's accession to the European Union. Biomass is deemed to be the main renewable energy source in Serbia with estimated 2.7 Mtoe/year of energy potential, with 60% being the agricultural biomass. Over the past couple of years, considerable efforts have been made to develop a technology which would enable biomass utilization for energy production. In this paper has been presented optimization of the existing furnace for biomass combustion in the way of improving energy efficiency and environmental protection. By proper dimensioning of furnace also could be avoided unnecessary investment costs. Two-dimensional turbulent flow model with homogeneous chemical reactions has been developed. Calculations based on the proposed models were conducted using commercial CFD package FLUENT 6.3.26. Comparative analysis of the results of modeling existing and proposed (optimized) furnace has shown lower CO emission at the proposed furnace outlet.
Aleksandar Eric, Stevan Nemoda - University of Belgrade, Institute of Nuclear Science Vinca, Laboratory for Thermal Engineering and Energy, P.O.Box 522, 11001 Belgrade , Mirko Komatina - University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 19, Belgrade, Serbia , Dragoljub Dakic - University of Belgrade, Faculty of Mechanical Engineering, Innovation Centre, Kraljice Marije 19, Belgrade, Serbia , Branislav Repic, Milica Mladenovic - University of Belgrade, Institute of Nuclear Science Vinca, Laboratory for Thermal Engineering and Energy, P.O.Box 522, 11001 Belgrade
Pages 1179 - 1191
Abstract
This paper presents a comparison of results of 2D and 3D CFD modeling of baled agricultural biomass combustion in the furnace which operates on the cigarette combustion principle. The complex physical and chemical processes occurring in the bale and the area around it are taken into account. The bale of agricultural biomass is treated as a porous medium, so calculations include laws of the conservation of mass and heat transfer in porous media. The area around the bale is presented as a fluid environment in which are applied well-known transport processes modelling. The models are described by a set of partial differential equations which define the momentum, heat and mass transfer processes in the porous and fluid system.
The aim of this investigation was analysis of results obtained using 2D and 3D CFD models for investigating the influence on the accuracy of the final modelling results due to approximations that are introduced in the 2D modeling. The verification of the developed numerical models was performed through a comprehensive experimental research conducted on an experimental-industrial plant i.e. on the 1.5 MW boiler for heating the greenhouses in the “Agricultural Corporation in Belgrade”.
The results have shown that the 2D model with satisfactory accuracy can be used to describe the complex transport processes during combustion of baled biomass in the proposed furnace. This knowledge can be of great benefit to the use numerical simulation for the furnace operate optimization because the use of a 2D model significantly reduces the required calculation time and the resources required for the simulation.
Vuk Spasojević - Institute for Nuclear sciences "Vinča", Laboratory for Thermal Engineering and Energy , Mirjana Kijevčanin - Faculty of technology and metallurgy, University of Belgrade , Nikola Živković, Dejan Cvetinović, Milić Erić - Institute for Nuclear sciences "Vinča", Laboratory for Thermal Engineering and Energy
Pages 1192 - 1200
Abstract
Intensive scientific research in past 20 years provide clear evidence that climate changes and increase of green house gases concentration in atmosphere are caused by human activities. Energy sector plays main role in these processes with overall emission of carbon dioxide between 60 and 70 % mainly due to combustion of solid, liquid and gas fossil fuels. Similar case is characteristic for energy sector of Republic of Serbia, which emitted around 60% of overall carbon dioxide during 1990s. Republic of Serbia has been a member of United Nations Convention on Climate Change and Kyoto Protocol since 2008 with no green house gasses emission reduction commitments as a developing country. Nevertheless, increase in power supply demand from year to year and expected rise of industrial activities indicate rise of fossil fuels consumption and because of that, raise of green house gases emissions. Previous mentioned facts implicate that energy sector is crucial sector in which establishment and implementation of measures and activities will take place with green house gases emission reduction as main task. Main goal of this paper is to provide review of currently available methods for carbon dioxide removal from which some are commercially available while others are under development. Special attention will be given through detailed description of methods based on hemi sorption with aqueous solutions of alkanol amines, which found wide commercial use in industry. Choice of appropriate absorbent, process equipment, methods, working parameters, combustion process etc. are some of key points that will be presented within this work with main goal for providing clear picture about possibilities and limitations of carbon dioxide removal methods.
Vuk Spasojević - Institute for Nuclear sciences "Vinča", Laboratory for Thermal Engineering and Energy , Nikola Živković, Predrag Stefanović, Borislav Grubor - University of Belgrade, Institute for nuclear sciences “Vinča”, Laboratory for thermal engineering and energy, P.O. BOX 522, 11001 Belgrade, Republic of Serbia , Slobodan Đekić - Public Enterprise Electric Power Industry of Serbia,Department for Strategy and Investments, Vojvode Stepe 412, 11000 Beograd , Zoran Marković - University of Belgrade, Institute for nuclear sciences “Vinča”, Laboratory for thermal engineering and energy, P.O. BOX 522, 11001 Belgrade, Republic of Serbia
Pages 1201 - 1211
Abstract
The concept of clean production in manufacturing processes of Kolubara coal mines implies efforts toward preservation of raw materials, water and energy, emissions reduction of toxic and hazardous substances and abatement of wasta materials generated through production process. In addition, the concept of cleaner production completes the economical use of resources with an aim to minimize waste from production processes by type and by quantity. Waste materials from the manufacturing process have negative effects such as: increase of cost of production base, increase of the market value of the final product (coal), occupation of a large part of disposal space with constant need for monitoring its security in terms of prevention of spontaneous combustion or a more negative impact in terms of contamination of air and groundwater. Once implemented organizational requirements for management and use of waste material from the process of exploitation, processing and transportation can be made in order to determine the economic valuation of the energy potential of waste materials. This paper presents a method of sampling the various types of waste materials generated from the manufacturing process at Kolubara coal mines as well as the results of complex measurements and analysis in order to determine energy potential. The classification of waste materials on the basis of the new criteria are set out and presented within this paper with clear conclusion regarding use of waste materials that may serve as potential fuel, and those that do not meet the criteria, but can be used in other industries such as production of cement, building materials etc. Waste materials that are characterized as potential fuel can be used with coal dust in process of co-combustion within the power plants of Public Enterprise Electric Power Industry of Serbia.
Apstrakt
Koncept čiste proizvodnje u proizvodnim procesima RB „Kolubara“, podrazmeva napore usmerene na očuvanje sirovina, vode i energije, smanjenje primene i emisija toksičnih i opasnih materija kao i izbegavanje stvaranja otpada u delu proizvodnog procesa. Pored toga, koncept čistije proizvodnje zaokružuje koncept ekonomičnog korišćenje resursa sa osnovnim ciljem smanjenja otpada iz procesa proizvodnje kako po vrsti tako i po količinama. Otpadni materijal iz procesa proizvodnje povećava troškove osnovne proizvodnje, povećavajući tržišnu vrednost finalnog proizvoda (lignita), zauzima veliki deo prostora odlagališta i neophodno je njegovo stalno praćenje u smislu bezbednosti od samozapaljenja ili negativanog uticaja u pogledu kontaminacije vazduha i podzemnih voda. Nakon sprovedenih organizacionih pretpostavki za upravljanjem i korišćenjem otpadnih materijala iz procesa eksploatacije, prerade i transporta moguće je izvršiti ekonomsku valorizaciju i odrediti energetski potencijal otpadnih materija. U radu je prikazan načina uzorkovanja raznih vrsta otpadnih materija koje nastaju iz procesa proizvodnje u RB „Kolubara“ kao i rezultati kompleksnih merenja i analiza, a u cilju određivanja njihog energetskog potencijala. Izvršena je klasifikacija otpadnih materija na osnovu prikazanih kriterijuma na otpadne materije koje mogu da posluže kao potencijalno gorivo i na one koje ne zadovoljavaju postavljene kriterijume, ali se mogu koristiti u drugim industrijskim granama poput industrije cementa, građevinskih materijala i drugo.
Nikola Živković - Belgrade University, Institute for Nuclear Sciences “Vinča”, Laboratory for thermal engineering and energy , Slobodan Šerbanović, Mirjana Kijevčanin, Emila Živković - Belgrade University, Faculty of Technology and Metallurgy , Vuk Spasojević, Milić Erić - Belgrade University, Institute for Nuclear Sciences “Vinča”, Laboratory for thermal engineering and energy
Pages 1212 - 1219
Abstract
In order to mitigate climate change, the priority task is to reduce emissions of greenhouse gases among which are sulfur oxides, from stationary power plants. The legal framework of the European Union has limited the allowable emissions of gases with harmful effects, and developed a strategy to adapt to the climate change. Goals and obligations to reduce the emissions are before the Republic of Serbia in the process of joining the EU. According to priority and timeliness of the aforementioned problems, the paper gives the categorization procedures for removing sulfur oxides from thermal power plants flue gases. The most frequent wet lime/limestone process has been described. The processes with chemical and physical absorption and thermal regeneration of the solvent have been presented. Processes that have commercial application in the world, as well as the new trends related to the use of regenerative processes for purification of flue gases are specifically outlined.
Apstrakt
Prioritetni zadatak u cilju ublažavanja klimatskih promena, je smanjenje emisija gasova sa efektom staklene bašte među koje spadaju i sumporni oksidi, iz stacionarnih termoenergetskih postrojenja. Zakonski okvir Evropske Unije ograničio je dozvoljene emisije gasova sa štetnim dejstvom i razvijena je strategija prilagođavanja novonastalim klimatskim promenama. U procesu pridruživanja EU, pred Republikom Srbijom stoje ciljevi i obaveze u pogledu smanjenja emisija gasova sa štetnim dejstvom. S obzirom na prioritet i aktuelnost navedene problematike, u radu je data kategorizacija postupaka za uklanjanje sumpornih oksida iz dimnih gasova iz termoenergetskih postrojenja. Od mokrih postupaka opisan je krečni postupak koji je najzastupljeniji. Navedeni su postupci sa hemijskom i fizičkom apsorpcijom i termalnom regeneracijom solventa. Posebno su naglašeni procesi koji imaju komercijalnu primenu u svetu, kao i novi trendovi vezani za primenu regenerativnih postupaka za prečišćavanje dimnih gasova.
Milica Mladenović, Dragoljub Dakić, Stevan Nemoda, Aleksandar Erić, Dejan Đurović, Milijana Paprika - Univerzity of Belgrade, Institute of Nuclear Sciences "Vinča", Laboratory for Thermal Engineering and Energy, 11000 Belgrade, Serbia , Mirko Komatina - Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade
Pages 1220 - 1236
Abstract
Converting waste into energy is an increasingly important topic, both in terms of environmental protection and energy efficiency improvement and rational use of limited energy resources, in order not to jeopardize future generations. The topic of this paper is fluidized bed combustion of paper sludge – waste from recyclable paper processing.
The paper gives a detailed description of demo-experimental fluidized bed hot-water boiler, with a power of about 500 kW, for combustion of non-conventional solid and liquid fuels, i.e. industrial waste materials, developed by the Laboratory for Thermal Engineering and Energy of Vinča Institute and installed in the factory TIPO Kotlogradnja. The experimental results of fluidized bed combustion of paper sludge are given, which include temperature field gradients, analysis of the composition of flue gases exiting the furnace and the parameters of the fuel combustion. Based on the results, an evaluation of the paper sludge FB combustion, and possibility of utilization of its energy potential are given.
Šefik Bajmak, Prof. dr. - Fakultet tehničkih nauka Univerziteta u Prištini
Pages 1237 - 1248
Abstract
In many industries and is widely applied heat and cooling energy to achieve different technological processes. Based on the analysis of design solutions was determined that the centralized supply of cooling energy with water as a carrier of cooling energy, amount spent per unit of production from cooling energy can be reduced to 2 times the intended effect of cooling stations (equipment) up to 1.3 times, the cost of electrical energy by 1.5 times and the number of workers who serve the cooling system from 2.5 to 3.5 times. In the complex and combined SCHSCE, used analog equipment in SCHSCE with KPP -TCCS. To be assessed effectiveness SCHSCE type heat pump, which runs summer and winter in different regimes is necessary to start from the primary carrier of energy consumed in the source of energy supply. Comprehensiveness application SCHSCE -TTP or HPP-ABCS depends on energy-climatologically indicators and and from relationship coefficient converting the .
Ivan Lazović, Žarko Stevanović, Valentina Turanjanin, Borislav Grubor, Sandra Stefanović, Nikola Mirkov, Nenad Stepanić - University of Belgrade, Serbia, Institute of Nuclear Sciences „Vinča”, Laboratory for Thermal Engineering and Energy
Pages 1249 - 1257
Abstract
The results of energy envelope characteristics measurements in elementary school "Ljubica Radosavljevic – Nada" in Zajecar, with total area of 3960 m2, and the main indoor air quality parameters are presented in this paper. The measurements were performed during heating season, from 2. 4. – 12. 4. 2012. The obtained results of the heat flux through the building envelope, temperature, humidity, and CO2 concentrations of indoor air in a representative number of rooms within the building are shown. The calculation methodology of heat transfer coefficient of the building envelope is also presented in this work. The obtained measurement results pointed out that the school building has low energy efficiency.
Predrag Škobalj - Univerzitet u Beogradu, Institut za Nuklearne nauke "Vinča", Laboratorija za termotehniku i energetiku , Mirjana Kijevčanin - Univerzitet u Beogradu, Tehnološko metalurški fakultet , Naim Afgan - Instituto Superior Technico, Lisbon, Portugal , Predrag Radovanović - Univerzitet u Beogradu, Institut za Nuklearne nauke "Vinča", Laboratorija za termotehniku i energetiku
Pages 1258 - 1259
Abstract
U sastavu JP EPS, PD TE „Nikola Tesla“ doo, Obrenovac, posluje TE „Kolubara“-A, Veliki Crljeni, sa svojih 5 termoblokova ukupne instalisane snage 270 MW, od kojih su prva dva bloka, svaki nominalne snage 32 MW, puštena u rad još 1956. godine. S obzirom na tehničko stanje tih postrojenja, u bliskom budućem periodu odlučivaće se o njihovom statusu, odnosno o eventualnom prestanku njihove eksploatacije, ili pak o njihovoj revitalizaciji i modernizaciji u cilju nastavka eksploatacije.
U ovom radu biće predstavljeno 6 opcija mogućeg statusa razmatranih termoblokova sa indikatorima održivog razvoja (IOR), koji se sastoje iz ekonomskih, ekoloških, socijalnih i indikatora resursa, odnosno demonstriraće se jedan od mogućih pristupa za stvaranje podloga za donošenje poslovnih odluka na osnovu višekriterijalne analize.
Kako održivi razvoj znači uspostavljanje ravnoteže između ekonomskih, socijalno-ekoloških i tehnoloških aspekata, uz uzimanje u obzir etičkih vrednosti, indikatori održivosti su po definiciji parametri koji se koriste za opis odgovarajućih opcija s ciljem kvalifikacije određenog sistema. Tojest, IOR pokazuju da su proizvodnja i korišćenje energije usko povezani sa ekonomskim, ekološkim i drugim parametrima kao što su cene energenata i energije, privredni i tehnološki razvoj lokalnih zajednica, pri čemu je zaposlenost lokalnog stanovištva jedan od bitnih socijalnih parametara.
M. Erić, Z. Marković, P. Škobalj, D. Cvetinović, V. Spasojević, P. Stefanović - University of Belgrade, Institute of Nuclear Sciences Vinca, P.O. Box 522, 11001 Belgrade, Serbia
Pages 1260 - 1268
Abstract
The unit ''Ugljevik'' I has been in operation since 1985, when the unit put into operation. Existing electrostatic precipitators in TPP ''Ugljevik'' are designed for dust removal efficiency of 99.68%, At the nominal operation of 300 MW electrostatic precipitators separate about 110 t/h of flying ash. Total designed concentration of particulate matter in the flue gas at the outlet of the electrostatic precipitator 150 mg/Nm3. Today concentration is significantly higher than in earliar period.
In conditions of increased concentration of particulate matter lifetime of cold flue gases fan is significantly reduced due to the abrasion of turbine blades. Therefore, the new design of cold flue gases fans are mounted, which can work in the working conditions of increased concentrations of particulate matter up to 2000 mg/Nm3. New fans are worn before the scheduled hours of work.
Institute of Nuclear Sciences ''Vinca'', Laboratory for Thermal Engineering and Energy was engaged by equipment manufacturer to perform tests of dust concentration in the flue channel at the outlet of electrostatic and before segregation of cold gases. In addition to the required tests for the Institute of Nuclear Sciences ''Vinca'' was conducted additional tests .
The paper presents the results of the following tests: measurement of particulate matter concentration and the SO2 content in the flue gas and tests of the composition of crystalline compounds in samples of fly ash.
Rastko Jovanović, Dejan Cvetinović, Predrag Stefanović - University of Belgrade, VINCA Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, P.O.Box 522, 11001 Belgrade, Serbia , Boško Rašuo, Miroljub Adžić - University of Belgrade, Mechanical Engineering Faculty, Kraljice Marije 16, 11120 Belgrade 35, Serbia
Pages 1269 - 1282
Abstract
Numerical modeling is well established tool for prediction of combustion processes. Computational Fluid Dynamics - CFD models utilize three different global chemical rates for description of the coal combustion processes: coal devolatilisation, volatile combustion and char combustion. Reported rates for coal devolatilisation vary considerably among the authors depending on the type of experimental procedure used in investigating the devolatilisation phenomenon. Accurate representation of devolatilisation process is necessary in order to conduct successful CFD simulations of pulverized coal combustion and gasification. The subject of this work is three-dimensional numerical simulation of Serbian lignite pulverized coal devolatilisation in drop tube type laboratory scale furnace. The aim of this study is to determine the influence of different devolatilisation kinetic factors on total devolatilisation time in numerical modeling of pulverized Serbian lignite devolatilisation. The influence of eight different devolatilisation kinetic rates mostly used in devolatilisation numerical modeling was investigated in the presented work.
Rastko Jovanović, Milić Erić, Vuk Spasojević, Nikola Živković, Zoran Marković - University of Belgrade, VINCA Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, P.O.Box 522, 11001 Belgrade, Serbia
Pages 1283 - 1288
Abstract
Coal particles distribution inside air – coal mixture ducts has significant influence on boiler efficiency of pulverized lignite fueled power stations. In order to ensure optimal furnace performance coal – air mixture ducts design must fulfill number of requirements. The most important are: desired particle residence time and particle distribution along duct cross-section. Particle residence time must be sufficient for the raw lignite, which have high moisture content (up to 50 % of crude moisture) to dry. Uniform pulverized coal particles distribution along channel cross –section is also very important since it enables proper mixing between primary and secondary phases (pulverized coal particles and oxygen), and thus allows complete combustion to occur inside boiler furnace. Conical swirl generator was chosen among several possible solutions as technically and technologically simplest one. The subject of this paper is three-dimensional numerical modeling of turbulent two phase flow field inside cylindrical air –coal mixture channel. The aim of presented work is numerical optimization of particle distribution, and flow parameters inside laboratory scale burner duct with swirl generator. The obtained simulation results pointed out swirl generator influence on enhanced mixing and increased particle residence time inside air –coal burner duct. The established numerical model will enable future analysis of pulverized coal particles distribution, and flow characteristics inside full scale air – coal ducts of industrial boilers.
Rastko Jovanović, Dejan Cvetinović, Predrag Stefanović, Predrag Škobalj, Zoran Marković - University of Belgrade, VINCA Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, P.O.Box 522, 11001 Belgrade, Serbia
Pages 1289 - 1302
Abstract
It is planned to supplement current heavy oil system for boiler start-up and flame support in Serbian power plants in order to decrease air pollutions emission and operational costs. New system for unit start-up and flame support is based on coal gasification by low temperature air plasma. Introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. There are several conditions which must be fulfilled in order to introduce advanced thermal plasma system. CFD is extensively used as powerful tool for pulverized coal combustion and gasification modeling. Important stages during particle combustion, such as particle devolatilisation and char combustion, are described with satisfying accuracy in existing CFD codes. Particle fragmentation, due to its small size and thus limited influence on combustion process is commonly neglected. However, during plasma coal gasification, very high plasma temperature (round 4000 K) induces strong thermal stresses inside interacting coal particles. These stresses lead to “thermal shock” and extensive particle fragmentation during which coal particles with initial size of 50-100 μm disintegrate into fragments of at most 5-10 μm. This intensifies volatile release by a factor 3-4 and substantially accelerates the oxidation of combustible matter. The main focus of this work is to suggest novel approach to pulverized coal gasification under high temperature conditions. Novel model for particle fragmentation was implemented into comprehensive CFD code ANSYS FLUENT 13.0. In order to incorporate developed model it was necessary to define particle heating, devolatilisation, fragmentation, and char combustion through a set of user defined routines written in C programming language. These routines were than attached to the main FLUENT solver. Proposed model was validated against experimental data obtained in pilot scale plasma burner test facility built in Belgrade Institute of Nuclear Sciences “Vinca”, Serbia. Newly developed model showed very good agreement with experimental results with relative error less than 4%, while the standard gasification model available in FLUENT produced error up to 10%. In the next stage of simulations the proposed model will be used on real scale plasma burner in order to determine the most appropriate flow rate inside burner channel for thermochemical plasma treatment of pulverized Serbian lignite coal.
Predrag Stefanović, Zoran Marković, Milić Erić, Dejan Cvetinović, Predrag Skobalj, Vuk Spasojević - University of Belgrade, Institute for Nuclear sciences "Vinča", Laboratory for Thermal Engineering and Energy
Pages 1303 - 1312
Abstract
Low calorific, open-pit mined lignite is the basic energy source in Serbia. The lignite from the Kolubara open-pit mines is predominantly used as a fuel in domestic heat and power generation. According to first National Communication, the subsector with highest green house gases (GHGs) emission in Serbia is power generation/heat production subsector. Precise annual inventory of the GHG emissions, especially in the energy subsector, is one of the Serbia’s major objectives on its path to EU membership. In order to increase electricity production in the following decades,”Electric Power Industry of Serbia” (EPS) undertake extensive investment program of thermal power plant unit’s refurbishment that should improve productivity, energy efficiency, extend lifecycle and to reduce pollutant emission from the units. In that sense, introduction of new technologies of lignite predrying and homogenization of lignite supplied to the thermal power plants (TPPs) are taken into consideration.
Thermal Power Plants “Nikola Tesla” (TPP TENT) are not equipped with adequate on-line CO2 emission measuring systems. The internationally recommended first order estimation of the CO2 emissions by fuel combustion is calculated as the product of the fuel consumption, recommended net calorific value and the default carbon emission and oxidation factor. Therefore, the real effects of boiler thermal efficiency are not taken into account adequately.
This paper presents results of 20 on city measurements of CO2 emissions from 4 unitss operating in the TPP TENT system that combust Kolubara lignite as well as results of the laboratory analysis of the raw coal, bottom and flying ash samples taken during these tests. The TPUs power level during measurements ranged from 185 to 348 MW. The net calorific value of the samples of Kolubara raw lignite combusted in the boilers of TPP units during measurements was found to be in the range 6 ÷ 10 MJ/kg. An linear correlation CEFr [tC/TJ] = 34.407 - 0.5891 Qdr [MJ/kg] between the carbon emission factor CEFr and the lower calorific value Qdr of the Kolubara raw lignite was proposed for this range of net calorific values, giving the considerably higher values for CEFr than recommended by the IPCC Tier 1 methodology.
The results of calculation of CO2 emission factors obtained by means of three different approaches are presented: a) using linear correlation recommended for Kolubara lignite, b) based on the measured levels of CO2 content in the flue gas and c) using carbon mass balance based on the laboratory determined values of carbon content in raw lignite, fly ash and bottom ash. Taking into account combined uncertainties of the measurements and calculations, one can conclude that results of the CO2 emission factor calculation based on the CEFr linear equation for Kolubara lignite are in the acceptable correlation to the results based on of CO2 emission measurements and calculations based on carbon mass balance.