NEW TECHNOLOGIES FOR NEW LIGNITE POWER PLANTS IN KOSOVA THE WAY TO IMPROVE EFFICIENCY AND PROTECT THE ENVIRONMENT

is also be made to the importance of low rank coals-lignite in the international scene. The combination of the high moisture content and high reactivity of low lignite necessitates their use close to the mine, unless they can be upgraded to value-added products with improved transport safety and economics. Their primary use is therefore power generation or to provide domestic and industrial fuels for local use, although a number of novel alternative fuel and non-fuel applications provide value-added potential. Due to the generally low mining cost of these coals, emphasis was previously placed on developing technologies to minimise the capital expenditure rather than maximise thermal efficiency in their use. However, the current concerns over global warming have focussed attention on developing utilisation technologies to reduce the comparatively high CO2 emissions from burning these coals. Key words: new technologies, lignite ,moisture, efficiency, environement INTRODUCTION Kosovo has large lignite resources and their utilization for large scale thermal power generation has been envisaged in the regional electricity generation plans. Acording to that and the need for new capacities we have analyzed and make study on a new thermal power plant based on the Sibovc lignite field. That is planned to be developed next after the exhausting current mines of Bardhi and Mirash. The study has analyzed two alternative unit capacities namely 300 and 500 MW size. We assumed that the plant will be built in two phases i.e. 900-1000 MW in the first phase (3 x 300 MW or 2 x 500 MW), the first units running by 2012-2014 and the second phase (4 x 300 MW alternatively 2 x 600 MW or 2 x 500 MW) would start when the first phase has demonstrated its ability to generate power and sell it to the market. The aim of study was to compare eficiency improvement and environmental protection as a result from usage of new technologies. KOSOVA’s LIGNITE Kosova has hugh amount of lignite resources but for our waork we have analysed the Sibofc field where are concentrated 840 million tons of lignite. Some 200 million tons of that is planned to be reserved for the supply of the existing power plants of Kosovo A and B. That mine will be a continuation of Bardhi in the southwestern corner of the new field It concluded that the cost of lignite fuel available from the new mine is one of the lowest ones in whole Europe making power generation on the Kosovar lignite very attractive. The remaining lignite resource of approximately 650 million tons would make possible to build a 2000 MW power plant. The mine could furnish the plant at its full load for its whole lifetime of 40 years. It has been assumed that the investor will develop its mining operations independently of the KEK mine. LIGNITE ANALYSIS The huge lignite resource found in Kosovo can be characterized with the following analysis as received from the Sibovc (>8000 samples analyzed) mine(table a): Its typical ash analysis is assumed to be as follows based on the information of the adjoining Bardhi and Mirash fields(table b): Heat value, LHV 8200 Ash 15,3 Moisture 42 Sulphur, total 1,1 Sulphur,combustible 0,35 Carbon 22,0 Hydrogen 2,1 Nitrogen & oxygen 13,0% Chlorine 0,03% Table a. Table b. This Kosovo lignite can be characterized by its relatively low ash content, low combustible sulphur as the most of the sulphur is found in sulphate/sulfite form and the existence of ample calcium in the fuel. The lignite also contains some chlorine. NEW THERMAL POWER PLANT Power plant concept and applied technology The new plant will apply the latest well proven steam power plant technology available for lignite firing. Its pollution control methods will be as the current EU rules call for. For combustion of the lignite in 300 MW units the modern Circulated Fluidized Bed (CFB) technology can be used. As the fuel contains limestone, desulphurization takes place during the actual combustion process in the boiler and very low sulphurdioxide (SO2) emissions can be expected. In the casen of 500 MW units more conventional pulverized firing (PF) is used and there a separate desulphurization plant is required to meet the SiO2 38 Al2O3 6,8 Fe2O3 5,4 CaO 35 MgO 2,2 SO3 8,3 Others 4,3 same emission limit. Additional investigation is recommended to identify the most economical method for desulphurization. The pulverized firing concept is also calculated for the 300 MW plant for comparison purposes. Both combustion processes can meet the given nitrogen oxide (NOx) emissions. The plant cleans its flue gases from dust in the electrostatic precipitators. Thereafter the flue gases are planned to be taken into the large cooling tower and mixed with the exiting water vapour of the tower i.e. the highly visible stack is eliminated. The plant is estimated to have an overall efficiency of more than 40 %. In the case of applying CFB combustion technology for the 300 MW plant its efficiency will be 1-1,5 percentage points less as subcritical steam parameters would be used.The exact efficiency figures will depend on the final plant design taking into consideration also of the possible impacts of the Kyoto protocol for Kosovo. The plant itself is estimated to fullfill all requirements for environment protection acording to EU directives. APLICABLE TECHNOLOGIES FOR NEW POWER PLANTS IN KOSOVA Pulverised Coal Combustion(PCC) The conventional coal-fired generation system used today is pulverised coal combustion (PCC). PCC can be used to fire a wide variety of coals. In PCC power stations, coal is first pulverised then blown into a furnace where it is combusted at high temperature. The resulting heat is used to raise steam, which drives a steam turbine and generator. Efficiencies have been steadily rising –and hence the rate of emissions has been reducing –for many years and the trend continues. Efficiency improvements have been achieved through increasing the operating temperatures and pressures of existing steam cycles, leading to supercritical and more recently ultra-supercritical PCC plant designs. This has been facilitated through the development of materials that can safely handle the higher temperatures and pressures over the life of the plant. Supercritical plant operate at higher steam temperatures and pressures than conventional sub-critical PCC plant and offer higher efficiencies –up to 45% - and lower emissions. Ultra-supercritical technologies are emergent and relate to higher operating temperatures and pressures than supercritical plant. Research is underway to develop new materials that can safely operate at higher temperature and pressure. Future efficiencies from ultra-supercritical plant may approach 50% with appropriate materials development. Pressurised pulverised combustion of coal (PPCC) is also currently under development, mainly in Germany. It is similar to conventional pulverised coal combustion, in that it is based on the combustion of a finely Kosovo New TPP Efficiency vs. Fuel & CO2 NPV -400,0 -300,0 -200,0 -100,0 0,0 100,0 200,0 300,0

35 40 45 50 Efficiency %E u r o p e r k W Fuel CO2-credit Combined ground cloud of coal particles, the heat released from combustion generates high pressure, high temperature steam, which is used in steam turbine-generators to produce electricity. The pressurised flue gases exit the boiler and are expanded through a gas turbine to generate further electricity and to drive the gas turbine's compressor; hence this is a form of combined cycle power generation. This technology is currently development stage and is not widespread. Fluidised Bed Combustion Air is forced through a bed of ash, pulverised coal and limestone, causing rapid mixing and encouraging complete combustion of the fuel. The limestone provides a sorbent for sulphur dioxide. The heat is used in a conventional steam cycle to drive a steam turbine for electricity generation. The higher heat exchanger efficiencies and better mixing allows FBC systems to operate at lower temperatures than conventional (pulverised) coal-burning systems. By increasing pressures within a bed, a high-pressure gas stream can also be used to drive a gas turbine, generating additional electricity. As with conventional PCC based systems with post combustion treatment, fluidised bed combustion (FBC) systems can meet stringent NOx and SO2 emission regulations. These technologies are also more suited for applications using low quality or mixed fuels, such as biomass and coal. CFB technologie scheme PFBC technologie scheme Fluidised bed combustion technologies include atmospheric pressure fluidised bed combustion in both bubbling (BFBC) and circulating (CFBC) beds, and pressurised fluidised bed combustion (PFBC). Atmospheric pressure systems are currently available commercially although they are not as widespread as conventional PCC systems. Pressurised bed systems are currently at demonstrationstage only. Pressurized fluidized bed combustion (PFBC) Fluidized bed combustion, (FBC) in boilers can be particularly useful for high ash coals with variable characteristics although pressurized. PFBC has also been used on a (PFBC development over the years) (PFBC scheme) commercial scale in Sweden and Japan with traded coals of higher quality. It is used with a combined-cycle concept incorporating both steam and gas turbines. Considerable effort has been devoted to the development of PFBC during the 1990s. The other demonstration units were in Germany, Spain and the USA. FBC in pressurized boilers can be executed in compact units, and can be potentially useful for low grade coals and those with variable characteristics.The pressurized coal combustion system generates steam, in conventional heat transfer surfaces and produces hot gas to be supplied to the adjoining gas turbine. Gas cleaning is a vital aspect of the system, as is the ability of the gas turbine to cope with some residual solids in the fuel. The need to pressurize the feed coal, limestone and combustion air, and to depressurize the flue gases and the ash removal system introduces some significant operating complications. The combustion air is pressurized in the compressor section of the gas turbine.The proportion of power coming from the steam/gas turbines is approximately 80/20%. PFBC and generation by the combined cycle route involves unique control considerations, as the combustor and gas turbine have to be properly matched through the whole operating range. Integrated gasification combined cycle (IGCC) Coal is converted into a gas (‘syngas’ comprising carbon monoxide and hydrogen) –the gas is then be used as a fuel for supply to a combined cycle gas/steam turbine plant. Emissions from IGCC are significantly lower than for combustion-based plant as sulphur oxides, nitrogen oxides and ash/slag are removed from the fuel-gas before use. IGCC can also provide high process efficiencies approaching 50%. Carbon dioxide emissions from IGCC plant can be more easily captured than for conventional and fluidised bed plant as the carbon dioxide is in a more concentrated stream. This technology offers the opportunity to produce near zero emissions electricity from coal fired power plants - when integrated with carbon dioxide storage. There are currently few IGCC demonstration plants worldwide however gasification technologies have been widely used in the petrochemical industry for many years. Development work is underway to demonstrate this technology at commercial scale. Carbon capture and storage (CCS) Carbon capture and storage technologies enable emissions of carbon dioxide to be stripped out of the exhaust stream from coal combustion or product stream from coal gasification and stored in such a way that they do not enter the atmosphere. Technologies for capturing CO2 from emission streams have been used for many years to produce pure CO2 for use in the food processing and chemicals industry. Petroleum companies routinely separate CO2 from natural gas before it is transported to market by pipeline.There are technical and cost challenges to be addressed in separating out CO2 from high volume, low CO2 concentration flue gases, such as those generated by conventional pulverised coal-fired power stations, but retrofit (or new build) of these 'post-combustion' capture systems will become an economic and practical CO2 reduction option. This can be achieved by reacting the product stream from coal gasification in a water shift process so that carbon dioxide, rather than carbon monoxide, is produced with hydrogen. The CO2 is captured for storage or use, and the hydrogen is combusted in a gas turbine –or in the future used in a fuel cell. Geological Storage-Injection of CO2 into the earth's subsurface offers potential for the permanent storage of very large quantities of CO2. The CO2 is compressed to a dense state, before being piped deep underground into natural geological 'reservoirs'. Provided the reservoir site is carefully chosen, the CO2 will remain stored (trapped in the bedrock or dissolved in solution) for very long periods of time and can be monitored. A number of options for the geological storage of CO2 are being researched. Emission requirementsand environmental protection It is assumed that the new thermal power plant, TPP, will fully comply with the EU Large Combustion Plant, LCP, rules. That will mean the following emission levels from the beginning of the operation: Sulphur dioxide, SO2 mg/nm3 200 Nitrogen oxides, NOx mg/nm3 200 Particulates mg/nm3 30 Fluidized bed gasifiers are less developed than the two other gasifier types. Operating flexibility is more limited for this class of gasifiers because of performing several functions (e.g. fluidization, gasification, sulfur removal by limestone injection) at the same time, and there are too few independent variables for the desired process optimization. Still the fluidized bed technology perhaps offers better potential for utilizing low rank coals with high ash and moisture content. Conclusions We are facing a shortage of energy. Our towns continue to grow, increasing the need for housing. We are more and more reliant on new technology for power generation in friendly way to environment and eficient use of natural resources.Our lifestyles demand more electricity and yet, power plants are not being built. Besides, when faced with the possibility of a new power plant, no one wants one in their backyard. In the near future we will be part of the communities that must decide what to do. Kosova’s prosperity, standard and quality of life of its citizens, will greatly depend from the fact how domestic energy resources are obtained, transformed, allocated and consumed. Hereafter the pourpose of the work is to stimulate energy consumption in more rational way, use and adopt new energy technologies, development and provide adequate infrastructure for energy sector and for economy with growing tendency. This creates a base for the future of this sector in Kosova’s economic and social context. It provides a basic framework through which Kosova can utilize this opportunity for the benefit of its all citizens. Referencies

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