Research On Waste Heat Utilization Of Oxygen-rich Unit And Carbon Capture System Thermal Assisted By Solar Energy

As a carbon emission reduction method,oxygen-rich combustion carbon capture technology can effectively alleviate the impact of greenhouse effect on climate.However,oxygen-rich combustion technology needs to add air separation system and flue gas compression and purification system to the original thermal power generation system,so additional energy consumption will reduce the unit economy.Because of the characteristics of high flue gas temperature and much compressing waste heat in oxygen-rich combustion power station,the utilization of waste heat in oxygen-rich combustion power station can improve its economy.On this basis,a trough-type solar coupling oxygen-rich combustion carbon capture system was developed to compensate for the energy penalty caused by carbon capture.In this paper,Ebsilon professional simulation software is used to model the oxygen-rich combustion thermal power generation system and the trough solar energy collection system,and Aspen Plus process simulation software is used to model the air separation system and the flue gas compression and purification system.In the research process of waste heat utilization of oxygen-rich combustion,following the principle of energy cascade utilization,six schemes of waste heat utilization are proposed.On this basis,the coupling characteristics of the trough solar thermal collector system and the oxygen-rich combustion power station were studied,and seven coupling schemes were proposed,which were studied from three perspectives of thermal characteristics,thermal economy and economic efficiency.The results show that: 1)The optimal scheme for the utilization of waste heat in the oxygen-rich combustion system is to use the flue gas low-temperature economizer in parallel with the stage 5 and 6 regenerative heaters and the interstage heat exchanger in the air separation system in parallel with the stage 7 and 8 regenerative heaters.Under this scheme,the thermal efficiency of the unit is increased by 0.76 %.Exergy efficiency is38.18%.2)The increase of coal price will lead to the increase of coal cost,so the unit economy will be reduced.The change of carbon tax has a more obvious impact on thetraditional generator set.Under the condition that the coal price is 210 /t,when the carbon tax is 183 /t,the power supply cost of the optimal oxygen-rich waste heat utilization system is the same as that of the traditional generator set.At the coal price of 210 /t,when carbon tax is 167.5 /t,the traditional generator set has the same unit investment return as the optimal oxygen-enriched power station system.3)The coupling mode of the optimal solar energy collection system is that the trough solar energy collection system completely replaces the high pressure extraction steam of the high pressure cylinder of 1-3 levels.In this coupling mode,the total power generation of the system is 690.23 MW,the exergy loss of unit power generation equipment is 4257.9kJ/kWh,and the leveling power generation cost(LEC)is 0.906 /kWh.4)The design life and the price of the collector plate that affect the economy of the trough solar energy collector field are analyzed.The results show that the LEC decreases with the increase of the design life and the LEC increases with the increase of the price of the collector plate.Under the background of carbon dioxide emission reduction,the research of trough-type solar coupling oxygen-rich combustion power generation system can promote the application and development of solar thermal technology in new fields.