Performance Enhancement of Boiler Using Energy Conservation Practices

Abstract

All the power plants are facing the problem of boiler performance deterioration. GSECL Wanakbori Thermal Power Station is also facing the same problem of boiler performance reduction frequently. The consequence of which affects the working of power plant and national income in general. The aim of this research work is to do energy analysis of 210 MW boiler of Wanakbori Thermal Power Station and find the reduction in energy performance of the boiler. For that the effect of waterside deposits on the energy performance of the boiler, performance gain after installation of burner tilting device, gain in boiler efficiency after correcting the fuel/air ratio and exergy analysis of power plant are considered in this analysis.

In analysis of e_ect on energy performance due to water side deposits in the waterwall of boiler, for simplicity the overall system is considered at 100% maximum continuous rating (MCR) and linear growth rate of deposition is assumed. The composition of water wall deposits is used for energy conservation analysis. The quantity of water wall deposits was found in the range of 36.8 - 55.5 mg/cm2. The reduction in heat transfer in water wall system and efficiency of boiler were calculated. The boiler is rated as dirty and suggested for acid cleaning. Due to cleaning thermal efficiency is improved by approximately 1 %.

The analysis on performance gain after the installation of burner tilting device resulted in reduction in reheat spray. The reduction in spray is observed as 20.57 t/hr. Reduction in spray results in reduction of boiler heat supplied, increase of power output in HP turbine and loss of generator output in IP and LP turbine. The economical gain is observed around 350 lacs due to implementation of burner tilting device. The appropriate positions of air dampers were corrected to supply the optimum air/fuel ratio. The supply of optimum air/fuel ratio shows increase in boiler efficiency about 1%.

In exergy analysis of boiler, the exergy input such as exergy supply by fuel, water and air and exergy output such as exergy available with steam and flue gas were calculated to found out exergetic boiler efficiency. The exergy efficiency and irreversibility of all the boilers were found. The exergy efficiency were found between 34.45 % to 38.53 % and irreversibility found between 341.23 MW to 412.67 MW.