Low Temperature Flue Gas Waste Heat Power Generation(Organic Rankine Cycle) Technology Research In Municipal Solid Waste To Energy Plant

Based on the investigation of organic Rankine cycle at home and abroad,the low temperature flue gas system of 600 t / d scale WTE plant of Yangzhou second-stage project is used to establish Organic Rankine cycle power generation system.And calculate the heat of the exhaust gas is about 1771 KW.Based on the first la w of thermodynamics and the second law of thermodynamics,the relevant calculation models are established.According to the principle of selecting refrigerants,the isentropic refrigerant or dry refrigerant with higher latent heat of vaporization,smaller dynamic viscosity,better thermal conductivity,lower specific volume and lower critical pressure is selected for organic Rankine cycle system.Although we cannot choose the perfect refrigerant,but we can choose the refrigerant with relative more merits.We select six commonly used refrigerants,R245 fa,R152a,R134 a,R123,R1234 ze,R227ea.The thermal efficiency,power loss,power generation and net work of ORC power generation system were studied.The influence of evaporation temperature,expansion ratio and ambient temperature on the thermal efficiency of ORC power generation system was analyzed and compared with the waste heat of WTE plant.The effect of evaporating temperature on the thermal efficiency of organic Rankine cycle ORC power generation system was studied when the inlet steam of the expander was saturated and the expansion ratio was 2 and the condensed water temperature was 38 ?.Increasing the evaporating temperature can improve the enthalpy of the refrigerant of the expander inlet,so the average temperature increases,and the thermal efficiency of the system increases,and the net work of the turbine increases.But evaporation temperature cannot be infinitely increased,while considering the high temperature performance of the equipment materials,and taking into account the investment of equipment,select a reasonable evaporation temperature.When the evaporation temperature is 100 ? and the expansion ratio is 2,the refrigerant R152 a is selected,the system thermal efficiency is the highest,up to 4.92%.The effect of the expansion ratio on the thermal efficiency of organic Rankine cycle ORC power generation system was studied when the inlet steam of the expander was saturated and the evaporation temperature was 100 ?,and the condensing water temperature was 38 ?.The larger the expansion ratio,the higher the thermal efficiency,the smaller the exergy loss,the greater the power ge neration and the net work of the system.Under the conditions of equipment cost,system stability and safety,the optimal thermal efficiency can be obtained by selecting appropriate expansion ratio.When evaporation temperature is 100 ?,expansion ratio is 4,choose refrigerant R152 a,the system thermal efficiency reach the highest,up to 10.75%.The effect of the ambient temperature on the organic Rankine cycle ORC power generation system was studied when condenser cooling water temperature is(25/33)? and(32/40)?,the inlet steam of the expander was saturated and the evaporation temperature was 100 ?.Appropriate to reduce the temperature of the condenser cooling water can make the ORC system thermal efficiency and power generation increased.The thermal efficiency and power generation of the ORC system in winter are higher than those in summer.The temperature of the evaporator is 100 ?,the condenser cooling water temperature is(25/33)?,choose refrigerant R123,the system thermal efficiency reach the highest,up to 6.39%.The results of this study do the technical preparation for the development of low temperature flue gas waste heat power generation technology of WTE plant,to provide theoretical guidance for the development of the industrial test.The paper also provides some reference for the research and development of smelting industry low temperature flue gas recovery technology.It has great significance to promote the work of energy conservation and emission reduction in China.