Research On Configuration Scheme And Thermal Economic Of Nuclear-gas Combined Cycle Generating Unit

Nuclear power plays an important role in adjusting China's energy structure.However,with the rapid development of renewable energy and the strong growth of global natural gas supply led by shale gas,the development of nuclear power ha s been challenged.The fourth generation of nuclear reactors can effectively improve the power generation efficiency and inherent safety,but they cannot realize large-scale commercial operation at present.Under the above background,the analysis and thermal economy research of nuclear-gas combined cycle power generation system can increase the output of nuclear power units,reduce the cost of power generation,enhance the peak-adjustment capacity and improve the flexibility of nuclear power units.Taking daya bay 984 MW nuclear power plant as the research object,this paper designs three schemes of nuclear-gas combined cycle generator set.EBSILON software is used to establish the corresponding simulation model.Take the exergy efficiency of unit,specific consumption and other parameters as thermal efficiency index,contrast analysis the nuclear power plant thermal system and nuclear-gas combined cycle system,the heating area of superheater and economizer in the waste heat boiler match gas turbine type SGT5-4000 F is calculated.At the same time,equipment investment cost estimation and technical economic analysis are carr ied out.The results show that the combined cycle system can increase the main steam temperature and output power of steam turbine.In three kinds of scheme,the one of economizer replace high and low pressure heaters have the highest unit exergy efficiency,the minimum additional consumption and most generated power.The reduction of ambient temperature or pressure can increases gas turbine efficiency and combined cycle power.When the gas turbine is under load,it can maintain the inlet temperature of steam generator remain unchanged through the afterburning of natural gas.In the heat exchanger of waste heat boiler,the heat transfer coefficient can be increased and the heating area can be reduced by using spiral fin tube with small tube diameter.The investment cost of nuclear-gas combined cycle power generation system is higher than that of the original nuclear power plant,and the generation cost is lower than that of the original nuclear power plant under certain conditions.