Abstract: The intensification of the greenhouse effect has led to a gradual increase in people's awareness of carbon capture. Aiming at the carbon capture problem, combining the CO₂ supercritical Rankine cycle with the organic Rankine cycle, the original gas turbine exhaust gas power generation system was improved,an LNG cold energy cascade utilization system combining exhaust gas power generation and CO₂ capture was proposed. The thermodynamic simulation of the system was carried out using Aspen Plus software, the effects of evaporation pressure and evaporation temperature on the thermodynamic performance of the system were analyzed in detail. The results show that the increasing of the evaporation pressure and evaporation temperature of the CO₂ supercritical Rankine cycle have a positive effect on the net output power and thermal efficiency of the system. After the evaporation temperature of the organic Rankine cycle reaches 250 ℃, the waste heat recovery rate reaches the maximum value and no longer changes with evaporation pressure. The net output power of the system can reach 251.6 kW, the recovery rate of waste heat is 92.00% and the exergy efficiency is 57.00%.The amount of CO₂ liquefaction can reach 883.6 kg/h, which is equivalent to reducing CO₂ emissions by 7.63 million tons per year, and is of great significance to environmental protection.

Key words: CO₂ supercritical, Power generation, CO₂ capture, LNG cold energy, Thermodynamic performance

摘要： 温室效应的加剧使人们的碳捕集意识逐渐提高。针对碳捕集问题，将CO₂超临界朗肯循环和有机朗肯循环相结合，对原有燃气轮机废气发电系统进行改进，提出了一种废气发电与CO₂捕集相结合的LNG冷能梯级利用系统。利用Aspen Plus软件对系统进行热力学模拟计算，详细分析了蒸发压力和蒸发温度对系统热力学性能的影响。结果表明，提高CO₂超临界朗肯循环的蒸发压力和蒸发温度，对系统的净输出功和热效率有积极影响；有机朗肯循环的蒸发温度达到250 ℃后，其余热回收率达到最大值且不再随蒸发压力发生变化；系统净输出功可达251.6 kW，余热回收率为92.00%，㶲效率为57.00%；CO₂液化量达到883.6 kg/h时，可减少CO₂排放量763万t/a。研究成果对保护环境具有重大意义。

关键词: CO₂超临界, 发电, CO₂捕集, LNG冷能, 热力学性能