制氢中变气活化MDEA法脱碳工艺流程模拟与优化

Simulation and optimization of process flow of activated MDEA decarburization of shift gas in hydrogen production system

为脱除天然气重整中变气中的CO_(2),使其含量低于0.0005%(物质的量分数,下同),从而达到纯氢技术指标,选用质量分数为35%MDEA+3.5%PZ+61.5%H2O的贫胺液为吸收液,采用Aspen HYSYS软件搭建了脱碳工艺流程并建立了系统能耗计算模型。对吸收塔吸收压力、贫胺液循环流量和富胺液进再生塔温度三个关键参数进行了敏感度分析;并以系统总能耗最小为目标,利用遗传算法对关键参数进行了优化。结果表明:所建流程氢气回收率可至97%以上,且CO_(2)捕集率及纯度均达到99%。优化后,系统总能耗降低了2.4%,脱除单位CO_(2)能耗降低了4.14%。此外,处理CO_(2)含量分别为20%、25%、30%、35%的中变气,优化计算所得脱除单位CO_(2)能耗分别为21.54 GJ/t、19.71 GJ/t、17.84 GJ/t、15.71 GJ/t。

In order to remove the CO_(2) in the shift gas from the natural gas reforming and make its content less than 0.0005%mole fraction to reach the technical standard of pure hydrogen,the lean amine solution with mass fraction of 35%MDEA+3.5%PZ+61.5%H2O was selected as the absorption liquid,the decarbonization process was simulated by using Aspen HYSYS software,and the calculation model of the system energy consumption was established.Sensitivity analysis was carried out on three key parameters:the pressure of absorption tower,the circulation flow rate of lean amine solution and the temperature of pregnant amine solution into the regeneration tower.Aiming at minimizing the total energy consumption of the system,the key parameters were optimized by genetic algorithm.The results show that the hydrogen recovery rate of the process can reach more than 97%,and the CO_(2) capture rate and purity both can reach 99%.After optimization,the total energy consumption of the system is reduced by 2.4%,and the energy consumption per unit of CO_(2) removal is reduced by 4.14%.In addition,when the shift gas with CO_(2) content of 20%,25%,30%and 35%,the optimized energy consumption per unit of CO_(2) removal are 21.54 GJ/t,19.71 GJ/t,17.84 GJ/t and 15.71.GJ/t,respectively.