ENERGY AND EXERGY ANALYSIS FOR PERFORMANCE IMPROVEMENT OF COAL FIRED THERMAL POWER PLANT

Steadily growing demand of power and heavily dependence on conventional sources like coal and gas for power generation has made it imperative to utilize these resources efficiently and economically. The conventional steam power plant designs are normally based on the energetic performance of plant components viz. boiler, turbine etc. First law based energetic performance analysis is not sufficient to know about the complete utilization of energy as it does not provide any information regarding quality degradation during transformation process. In this research paper concept of exergetic performance analysis i.e. application of first and second law of thermodynamics together, has been utilized to identity the location/components where major energy and exergy losses takes place and also to determine the extent of losses. In the present study complete first and second law analysis of a 250MW coal fired thermal power plant at Korba, Chhattisgarh, India, is carried out at three different loads. The energy and exergy efficiency of the components have been determined. The energy efficiency of the plant is found to be 38.5%, 37.54% and 34.63% respectively for the plant operation at 250MW, 200MW and 125MW. A similar trend is seen in exergetic performance and exergy efficiency is recorded as 36.32%, 34.41% and 32.67% respectively at three loads mentioned above. It is observed that at the full load of 250MW the maximum energy loss (46.26% of the input) among all the components is taking place in the condenser which is the 72.46% of total energy loss whereas the maximum exergy loss of around 50% of the input takes place in the boiler and this contributes to 76.67% of total exergy loss. Both on the basis of quantity and percent exergy loss, boiler is the key component showing huge potential for saving. This study suggests that the possible measures should be taken to avoid the quality degradation of energy in boiler i.e. in the zone of higher temperature gradient and operation of the plant closed to the full load should be ensured for better performance.