Thermodynamic and economic analysis of co-firing dried sludge in coal-fired power plants
The increasing volume of sewage sludge production in China has created an urgent need for its harmless and resourceful treatment.This paper aims to tackle this issue by adopting a novel strategy that integrates coal-fired power plants with a sewage sludge drying system,in this method,the sludge will be co-fired after being dried.By taking a typical supercritical 660 MW unit as the research object,the influences of moisture content(10％,20％,35％,50％,and 65％)and blending ratio(2％,4％,6％,8％,and 10％)of the dried sludge on parameters such as flue gas temperature,boiler efficiency,net power generation efficiency,equivalent net efficiency of sewage sludge power generation and equivalent net efficiency of dried sludge power generation are investigated through thermodynamic calculation of the boiler and comprehensive thermodynamic and economic analysis of the entire system under THA condition.The results indicate that,when the moisture content of the dried sludge exceeds 50％,it leads to parameter deterioration,and this trend intensifies with an increase in the blending ratio.Considering all factors,it is recommended to maintain the moisture content of the dried sludge at 50％or below,and if it exceeds this value,the blending ratio should be limited to less than 4％.Blending sludge leads to a reduction in the exergy efficiency of the system,which is mainly due to the increasing exergy losses in the boiler and drying equipment.Moreover,the study reveals that the optimal economic performance is achieved when blending the sludge with moisture content of 20％and blending ratio of 10％,in this case the dynamic payback period is only 4.02 years.
sewage sludge dryingmoisture contentblending amountcoal-fired power stationthermodynamic analysiseconomic analysis
万方数据
维普
