二氧化碳捕集耦合工艺设计与优化

Design and optimization of CO_(2) capture coupled process

采用醇胺法工艺对高含碳天然气进行脱碳处理时,其能耗随着碳含量的增加而提高。为降低高含碳天然气的脱碳能耗,提出了一种醇胺法工艺(N-甲基二乙醇胺作吸收剂)与级间冷却、富液分流解吸、酸气再压缩热泵和蒸汽机械再压缩技术(MVR)热泵工艺耦合的二氧化碳(CO_(2))捕集耦合工艺流程(简称“耦合工艺”)。采用AspenHysys软件对影响耦合工艺节能效果的关键参数(级间物流冷却温度、贫液节流后压力、酸气再压缩压力和再生塔底重沸器温度)进行了分析,并通过响应面分析与遗传算法结合的方式对关键参数进行了优化。结果表明,优化后耦合工艺的级间物流冷却温度为58℃,贫液节流后压力为0.084MPa,酸气再压缩压力为0.195MPa,再生塔底重沸器温度为92℃。与联合工艺(膜分离+醇胺法)相比,耦合工艺的能耗明显降低,脱碳单位能耗(脱除1 t CO_(2)需要消耗的能量)由1.338 GJ/t下降至1.110 GJ/t。与优化前相比,耦合工艺优化后的净化气中CO_(2)含量(体积分数)由2.533%下降至2.326%,脱碳单位能耗由1.110GJ/t下降至1.074GJ/t。

The energy consumption of high carbon natural gas increases with the increase of carbon content when it is decarburized by the alcohol amine process.In order to reduce the energy consumption of high carbon natural gas,a carbon dioxide(CO_(2))capture coupled process(referred to as“coupled process”)was proposed,which coupled the alcohol amine process(N-methyldiethanolamine as the absorbent)with inter-stage cooling,liquid rich shingle desorption,acid gas recompression heat pump and steam-mechanical recompression technology(MVR)heat pump processes.The key parameters,such as inter-stage flow cooling temperature,lean liquid throttling pressure,acid gas recompression pressure and regenerator bottom reboiler temperature,were analyzed by Aspen Hysys software,and the key parameters were optimized by response surface analysis and genetic algorithm.The results show that the inter-stage flow cooling temperature,the lean liquid throttling pressure,the acid gas compression pressure and the regenerator bottom reboiler temperature is 58℃,0.0844 MPa,0.195 MPa and 92℃,respectively.Compared with the combined process(membrane separation+alcohol amine method),the energy consumption of the coupled process is significantly reduced,and the unit energy consumption of decarbonization(the energy required to remove 1 t CO_(2))decreases from 1.338 GJ/t to 1.110 GJ/t.Compared with before optimization,the CO_(2) content(volume fraction)in the purified gas of coupled process after optimization decreases from 2.533%to 2.326%,and unit energy consumption decreases from 1.110 GJ/t to 1.074 GJ/t.