基于SOFC的近零碳排放联合循环动力系统热力性能研究

Research on Thermal Performance of Near Zero Carbon Emission Combined Cycle Power System Based on SOFC

基于传统富氧燃烧碳捕集的固体氧化物燃料电池(SOFC)发电系统,提出一种改进的新型近零碳排放的SOFC-燃气轮机(GT)-有机朗肯循环(ORC)系统。利用Aspen Plus软件和内嵌FORTRAN语言对系统进行建模,分析了阳极再循环、后燃烧室废气再循环、电流密度、燃料利用率和蒸汽碳比对系统性能的影响。结果显示,改进后的系统可以有效避免传统空气分离器功耗大、氧气分离率低等问题。在设计工况下,考虑碳捕集的SOFC-GT-ORC系统净发电功率为1304.09 kW,碳捕集摩尔流量为7.9 kmol/h,捕集纯度高达99.8%。净发电效率为75.68%,相比于传统系统提升了6.68%。采用阳极和后燃烧室废气再循环显著提升了SOFC电池堆发电效率,并且存在最佳循环比(R an=0.15和R cc=0.27),使得联合循环系统效率最高。系统发电效率随着燃料利用率的增大显著提升,电流密度和蒸汽碳比增加对系统发电性能不利。SOFC电池堆和换热器在系统中的损失较大,但换热器的优化潜力更大。

Based on the solid oxide fuel cell(SOFC)power generation system with traditional oxygen rich combustion and carbon capture,an improved novel SOFC-gas turbine(GT)-organic Rankine cycle(ORC)system with near zero carbon emission was proposed.The system model was established by Aspen Plus software and embedded FORTRAN language,and analyses were conducted on the effects of anode recirculation,rear combustion chamber exhaust gas recirculation,current density,fuel utilization rate,and steam carbon ratio on the system performance.Results show that,the improved system can effectively avoid problems such as high power consumption and low oxygen separation rate of traditional air separators.Under design conditions,the net power generation of SOFC-GT-ORC system considering carbon capture is 1304.09 kW,the carbon capture mole flow rate is 7.9 kmol/h,and the capture purity is as high as 99.8%.The net power generation efficiency is 75.68%,which is 6.68%higher than that of traditional systems.The use of anodes and post combustion chamber exhaust gas recirculation significantly improves the power generation efficiency of SOFC battery stacks,and there are optimal cycle ratios of R an=0.15 and R cc=0.27,resulting in the highest efficiency of the combined cycle system.The power generation efficiency of the system is significantly improved with the increase of fuel utilization rate,and the increase of current density and steam carbon ratio is detrimental to the power generation performance of the system.The exergy losses of SOFC battery stacks and heat exchangers in the system are relatively high,but the optimization potential of heat exchangers is greater.