A novel zero-emission Allam cycle coupled to supercritical CO2 gasification of coal for efficient power generation

• Supercritical CO 2 gasification of coal is integrated with coal-fueled Allam cycle. • Lower gasification exergy destruction is realized by supercritical CO 2 agent. • The optimal net efficiency is 53.61% for the modified cycle with recompression. • Modified cycle shows superior thermal performance over most published cycles. To achieve efficient power generation and nearly zero carbon emission, a novel coal-fueled Allam cycle integrated with supercritical CO 2 (sCO 2 ) gasification is proposed and investigated from the perspective of thermodynamics. In the proposed cycle, sCO 2 serves as the gasification agent and reacting with coal to produce syngas, then the syngas at high pressure is directly combusted with oxygen to drive the sCO 2 cycle for electric power generation and split the high purity CO 2 from the cycle cold-end for carbon capture and storage (CCS). For the basic cycle without recompression, the net efficiency is as high as 49.75 % on the lower heating value basis. Exergy analysis shows that the largest exergy destruction occurs at the combustor, followed by the gasifier and recuperator. With the application of recompression and identifying the optimal mass flow rate of 862 kg/s, the exergy destruction of recuperator and gasifier are significantly reduced, resulting in a notable increase in the net efficiency to 53.45 %. The influences of the turbine inlet temperature and outlet pressure on the net efficiency are comprehensively analyzed. Results show that the net efficiency of the system can be further improved to 53.61 % at the turbine inlet temperature of 1140 °C and back pressure of 3.11 MPa. In addition, the proposed concept also shows superiority on thermal performance in comparison with most coal-fueled Allam cycles published previously.