Performance Research And Optimization Of Combined Heat And Power System In Solar Power Tower Plant

Climate change is a global problem faced by human beings.With the continuous development of economy and society,greenhouse gas emissions in the world are rising sharply,which has an immeasurable impact on the earth’s ecology.The solar power tower station equipped with heat storage system can realize clean,efficient,safe and flexible power production.In view of the abundant solar energy and high heating demand in Northwest China,this paper puts forward the idea of solar cogeneration,and discusses the feasibility of cogeneration in heating period through the heating transformation of condensing solar power generating unit.The main contents of this paper are as follows:(1)Based on the energy balance and mass balance,the mathematical models of the key units such as the heat collection field,the steam turbine unit and the heat storage system are established.The programs of solar tower heat collection field,the heat storage system and the off design steam turbine unit are compiled,and the steady-state simulation system of the solar power tower station,combined with heat and power unit is constructed as below.(2)Aiming at a 50MW condensing unit of solar power tower plant,combined with the annual hourly DNI and outdoor temperature and other meteorological parameters in the selected area,the influence of solar multiple and heat storage duration on the annual power generation and capacity factor of the system is studied.Taking LCOE as the system economic evaluation index,the solar multiple and heat storage duration are optimized.The results show that the system is optimal when the solar multiple is 3.0 and the heat storage duration is 12h.At this time,the LCOE of the system is 0.218$/(kW·h).and the annual power generation is 216.4 GW·h.(3)To carry out the heating transformation of the above 50MW unit,study the external heating capacity and the overall performance of the system after the heating transformation of the unit,and obtain the thermoelectric characteristic curve of the transformed cogeneration unit.The results show that under the rated extraction condition,the heating power of the unit is 58.64mw,and the electric output power is 35.33mw.Based on the above research results,combined with the selected area hourly DNI,outdoor temperature and other meteorological parameters and building heating index,the heating area is optimized.The results show that:when the heating area is 800000 m2,the heating capacity of the whole heating season is 88.1GW·h,and the annual power supply is 196.2GW·h.The system has good economy and annual performance.