Energy Conservation and Exergy Analysis of Captive Power Plant Based on CFBC Boiler

Abstract

The ratio of energy available to requirement decreasing day by day around the world due to the increase in population and use of energy consuming equipments. This can be ful lled by installing new power plants but it needs many years and huge investment. There is another plan which can be worked out with development of new plant and that is to improve existing plant performance. This dissertation study deals with the exergy analysis and energy conservation of thermal power plant stimulated by coal asfuel. The exergy analysis includes exergy input, exergy utilization, destruction of exergy,irreversiblity of components and exergy e ciency. The Sankey diagram and Grassmanndiagram for the plant is prepared to carry out exergy analysis of various components.In present study based on performance analysis, the energy saving opportunity identi edin power plant auxiliary systems like Conveying Compressor, Instrument Compressor,Plant cleaning air Compressor and Coal Handling Plant. The utilization of compressorsto supply air for various functions are optimized. This lead to saving in energy and costas 48.26 MWh per year and 2.37 lacs per year respectively. Similarly installation of newcoal handling plant also lead to reduction in consumption of energy and cost as 260.11MWh per year and 12.75 lacs per year respectively. Energy and exergy analysis of boilerfurnace, economizer, air preheater, primary and nal super heaters, turbine, condenser,cooling tower, pressure reducing desuperheating systems, attamparators are carried out.Based on study it was found that steam coming out from the boiler is at higher pressurethan the need of condensate turbine. This issue is solved by use of Pressure reducingdesuperheating systems. To improve performance of economizer using hp heater 1, it issuggested to extract steam from the turbinehowever it is not used in the plant. Alsothe steam coming out from the turbine is condensed in condenser which leads to loss inenergy. To over come this issues a new back pressure turbine having capacity similar toboiler is installed. Also steam is extracted from this turbine and utilized in hp heater1. Use of new turbine eliminated to use of Pressure reducingdesuperheating system,condenser and cooling tower. This lead toreduction in energy consumption and exergydestruction in the plant. The steam coming out from the turbine is used in deaerator.This modi cations lead to improve utilization e ciency of steam from 57 % to 97.1 %and exergy efficiency from 31.36 % to 45.53 %.