Effect Of Flue Gas Waste Heat Composite Heating On Performance Of Biomass Direct Combustion Power Generation System

In view of the situation of large water vapor content in the exhaust gas of biomass direct combustion power generation system and huge potential for latent heat recovery,combined with the problems existing in the actual heating process.In order to recycle the waste heat of the flue gas generated by the biomass direct-fired power generation system,and at the same time prepare heating water for the user side.This paper presents for the first time a new combined heat and power system that integrates a biomass direct-fired power generation system with a composite heating system.Among them,the composite heating system is composed of absorption heat pump and water source heat pump.Taking a biomass direct combustion cogeneration system in Panshi,Jilin Province as the research object,through theoretical analysis,combined with Aspen Plus simulation and TRNSYS simulation,the effect of adding a composite heating system on the biomass direct combustion cogeneration system was studied.In order to clarify the energy flow,the exergy analysis of the new cogeneration system was conducted,and various indicators and environmental benefits of the system were evaluated.The following conclusions are drawn:?1?The Aspen Plus software was used to build a composite heating system to simulate the absorption heat pump heating system and the water source heat pump heating system.The simulation results show that:the composite heating system can reduce the flue gas temperature from 145?to 58.8?and generate 70?of heating water to the user.?2?Exergy analysis of each subsystem in the new combined heat and power system shows that the total loss of the boiler accounts for a maximum of 56.91%of the exergy loss of the entire system;the exergy loss of the absorption heat pump system is 0.47%;the exergy loss of the water source heat pump system is 0.58%;the exergy efficiency of the new cogeneration system is 41.85%.Furthermore,the exergy analysis of the boiler,absorption heat pump and water source heat pump is carried out.The most exergy loss of the boiler occurs in the combustion process.The largest exergy loss of the absorption heat pump is the generator.Through analysis,it can be concluded that the greater the temperature difference,the greater the exergy loss.?3?Taking the weather of Jilin as the meteorological parameter,using TRNSYS software to simulate the new cogeneration system,the simulation results show that the system is not easily affected by environmental factors,and the operating mode is relatively stable.Among them,the average output power of the absorption heat pump?4?system in the heating season is 3056.62 kW,and the water source heat pump system is 1737.77 kW.The heating capacity of the two is efficient and stable during the heating season.The average heating capacity of the absorption heat pump system is 5191.48 kW,and the average heating capacity of the water source heat pump system is 7208.70 kW.The average COP of the absorption heat pump is 1.70,and the average COP of the water source heat pump is 4.15.?5?The energy saving and environmental protection benefits of the new combined heat and power system are analyzed.The results show that:after adding the composite heating system,the energy saving rate of the new combined heat and power system has increased by 5.2%,and the comprehensive energy utilization rate has increased by 7.8%The utilization rate of flue gas waste heat recovery increased by15.5%.At the same time,each heating season can save 6416.53 t of standard coal,annual CO₂ emission reduction is 16682.98 t,SO₂ emission reduction is 128.33 t,NO_X emission reduction is 449.16 t.The dynamic recovery period of the composite heating system is 4.13 years.It shows that the addition of the composite system has a positive effect on the recovery and utilization of flue gas waste heat and the improvement of various performance indexes of the power plant.