Performance Improvement of Coal Fired Thermal Power Station through Energy Audit

Abstract

Energy supply and demand gap is very large in India. To overcome this new power plants are to be established, which are under process. For building and develop new facilities requires certain years and huge investment; on the other hand energy conservation and management practices can easily adapted and improve the performance of existing power plants with little investment. So the main objective of the present work is to improve performance of power plant by conducting energy audit and exergy analysis and suggest ways to enhance the performance of various equipment. The power plant consists of various equipments like boiler, coal mill, air preheater, turbine, condenser, regenerative system, etc. The present work includes energy audit of coal mill and performance assessment of turbine, condenser and feed water heaters. It also includes overall heat rate analysis. To evaluate performance of coal mills their performances are studied at full load i.e. 210 MW and minimum load i.e. 160 MW. Based on specific power consumption and air to fuel ratio comparison with design data energy savings opportunities are identified and also suggestions are made. It has been found that mill # 3 & 4 of Unit 1, mill # 2 & 4 of Unit 2 and mill # 4 of Unit 3 are not performing properly. There has been noted that with the implementation of Mill Pulverization Super Performance system the savings upto 192 lacs can achieved yearly. The simple payback period of MPSP system can be covered in approximately 33 days. The performance of feed water heaters has been studied with the parameters such as inlet temperature, saturation temperature, terminal temperature difference, drain cooler approach & temperature raise. It is evident that by using feed water heaters it is possible to save ~80 T/hr coal which results in savings of 70 crores per year and 0.8 MT of CO2 emission reduced per year. Based on performance analysis it was found that six HP Heaters and six LP Heaters has poor performance. The performance of turbine and condenser has been studied at 100% maximum continuous rating using energy audit and exergy analysis fundamentals. Comparing actual data with design data it was found Low pressure turbine of Unit 2 and Unit 3 and condensers of Unit 2 and Unit 3 are not performing properly. Remedial actions required to improve performance are suggested. Heat rate analysis was carried out for Unit 1, 2 & 3. Deviation of heat rate from design heat rate is 13%, 6% and 5% for Unit 1, 2 & 3 respectively. 1% improvement in heat rate reduces coal consumption by 9000 tonnes per year, monetary savings of 10 millions INR yearly and CO2 emission reduction by 13000 tonnes per year. If all units heat rate achieved as per design rate then in total 0.2 MT of coal consumption reduces, 247 millions INR saved and 0.3 MT CO2 emission reduced on yearly basis.