Partial load operation characteristics of the sCO2 cycle
The supercritical carbon dioxide(sCO2)cycle power generation system is compact,flexible,and efficient.In this paper,a 300-MW sCO2 cycle power generation system is taken as the research object,and a partial load model based on the inventory control operation mode is established by coupling the off-design models of components.During partial load operations,the operating parameters of the regenerators and turbomachines change according to different rules.To analyze the performance damage mechanism of the system,two research schemes are established:(1)The main operating parameters of the turbomachine(the main gas pressure and isentropic efficiency)are unchanged,and the influence of the regenerators on system thermal efficiency is studied and(2)the parameters of the turbomachines and the regenerators are varied.The results of these research schemes show that with decreasing load ratio,regenerator effectiveness increases,and the pressure drop decreases,which has a positive effect on system performance.During a partial load operation,the reduction of the main gas pressure greatly influences the turbine work,and simultaneously,the turbine efficiency decreases substantially,which has a negative effect on the system.Under standard inventory control operation,system thermal efficiency varies parabolically with the load ratio.When the load ratio is 100%-75%,the positive effect on the system is greater than the negative effect,so the thermal efficiency is greater than the design thermal efficiency.At 85%load,the system thermal efficiency reaches the maximum value of 49.82%.When the load ratio is 75%-30%,the positive effect on the system is less than the negative effect,and the thermal efficiency is less than the design thermal efficiency.The research results can guide the variable load operation of the sCO2 cycle system and provide target values for the dynamic control process of the system.