Study Of The Boiler Retrofitting For Energy Conservation And Efficiency Improvement In A 600MW Subcritical Unit

In this paper,a 600 MW subcritical boiler of the Inner Mongolia Power Generation Company has been regarded as the research object.The boiler retrofitting for energy conservation and efficiency improvement has been researched in this study,which should be met the thermal parameter requirements of steam turbine owing to the energy conservation transformation.Series of works has been accomplished as follows:(1)The investigation of boiler general situation and operation situation has been done;the in-situ tests for boiler maximum output,boiler efficiency,steam temperatures of superheat and reheat were investigated under the conditions of BMCR,100%,75% and 50% loads,to analyze the characteristics in boiler daily operation before the transformation.The results show that the efficiency of the boiler maximum continuous output and maximum load conditions are slightly better than the design value,up to 2087.62t/h and 93.42% respectively.The main steam temperature can be maintained above the 50% load;and the reheat steam temperature was low in all conditions,especially in low load,and the gap reaches 20?.(2)According to the thermodynamic parameters matching between boiler and steam turbine,the steam parameters of the boiler has been determined.The modification scheme including the screen type and final superheater as well as the wall type,screen type and final reheater was proposed.(3)Russian thermal calculation standard method for boiler was introduced to proofread the boiler retrofit scheme,and the main thermal parameters of the retrofited boiler was obtained to analyze and assess the achievements in the boiler retrofitting for energy conservation.(4)The thermal parameters of the boiler before and after the retrofitting for energy conservation were compared and analyzed.The results show that,after the transformation,the main steam capacity of the boiler increased by 4.4%,up to 2150t/h;the main steam and reheat steam temperature has also increased significantly,respectively reached 571? and 569?,which demonstrated that the outlet parameters in retrofited boiler counld be fully met the requirement from the steam turbine.The influence of modification on boiler operations was also discussed.After the boiler modifications,the flue gas temperature and heat flux inside the furnace increased,therefore a serious slagging should be avoided by some methods,and the flow rate of flue gas increased by 9%,so the abrasions of tubes should be taken into account.