Study of an integrated gas turbine -Molten carbonate fuel cell-organic Rankine cycle system with CO2 recovery

A huge amount of energy is consumed by recovering CO2 in the gas turbine (GT) exhaust gas with the traditional method because of the low CO2 concentration. A new system integrated with gas turbine, MCFC and ORC with CO2 capture is proposed in this article. CO2 in the gas turbine exhaust gas is concentrated by the MCFC electrochemical reaction. Compared with traditional CO2 capture methods, it effectively decreases the energy consumption of CO2 capture. The mid-temperature exhaust gas heat is recovered by two stages organic Rankine cycle systems. The influences of the major parameters on the new system performance are deeply studied. Also, the thermal and economic performances of the new system are compared with those of the reference system without CO2 capture and with CO2 capture based on the traditional mono-ethanol ammine (MEA) method. The results show that, when the CO2 capture rate is 0.85, the thermal efficiency of the new system is 62.34%, 3 percentage points higher than that of the gas steam combined cycle system without CO2 capture; and the exergy efficiency is 60.08%, 2.47 percentage points higher than that of the gas steam combined cycle system without CO2 capture. Its economic performance will be improved with the reduction of the MCFC cost in the future.