Optimization Of Supercritical CO₂ Power Cycle With Integrated Coal Gasification And Fuel Cell

Coal gasification fuel cell technology is a new low-carbon power generation mode with great development potential.It has the advantages of high power generation efficiency,low pollution,easy to capture CO₂ and strong flexibility.It has attracted extensive attention of scholars all over the world.The coal gasification fuel cell（IGFC）system works at high temperature and has high waste heat utilization value.If it is combined with other power systems for power generation,the energy utilization efficiency will be greatly improved.In this paper,the supercritical carbon dioxide Brayton cycle is integrated with the IGFC system,and the system is studied from the perspective of thermal performance and eco-nomic performance.According to the working characteristics of the two-stage dry powder entrained flow gasifier of Huaneng Tianjin IGCC power plant,the calculation method of zoning simulation is established.The results show that the zoning simulation method has higher accuracy than the single reactor simulation method,On this basis,the effects of pressure,oxygen coal ratio,water coal ratio and split ratio on coal gasification effect are analyzed in detail,and the reasonable variation range of these parameters is determined.Then,the purified syngas is introduced into the high-capacity fuel cell for electrochemical reaction.Four cycle configurations are designed for the fuel cell.The four cycle configu-rations are compared and analyzed from the perspectives of current density,fuel utilization and working temperature.The results show that ACR configuration is the most conducive to improve the performance of SOFC,Therefore,taking the optimization of SOFC power generation efficiency as the goal and considering many restrictive factors,the optimal re-circulation ratio of anode exhaust gas and cathode exhaust gas is obtained.Finally,accord-ing to the characteristics that different waste heat in IGFC system has different tastes,four supercritical carbon dioxide Brayton cycle schemes are designed according to the principle of cascade utilization of energy,and the thermal economy of the four schemes are com-pared and analyzed.The results show that scheme B and scheme C are the most suitable,and scheme C has better thermodynamic performance,which can make the net power gen-eration efficiency of the whole system reach 60.22%,The economic performance of scheme B is better.When the IGFC subsystem is not considered,the power generation cost is only 3.71M$.