单乙醇胺吸收CO_2的热力学模型和过程模拟

Thermodynamic modeling and process simulation for CO_2 absorption into aqueous monoethanolamine solution

采用非随机双流体电解质(ENRTL)热力学模型,通过拟合单乙醇胺(MEA)的饱和蒸气压、热容数据,MEA和水(H2O)二元体系的汽液平衡、热容、混合热数据,以及二氧化碳(CO2)在MEA水溶液中的溶解度数据,建立了MEA吸收CO2的热力学模型,并用核磁共振(NMR)组成数据成功地进行了验证。在此模型基础上,利用平衡级模型建立了MEA吸收/解吸CO2的过程模拟,利用文献中中试工厂数据验证了过程模拟的准确性。对于质量分数为30%的MEA溶液,固定吸收塔CO2去除率为90%的条件下,当吸收塔液气质量流率比值为2时,再沸器能耗最小,为3.64 GJ·(t CO2)-1。

A thermodynamic model for monoethanolamine （MEA）-H20-CO2 was built using the electrolyte non-random two-liquid model. Over twenty parameters were regressed from the vapor pressure and heat capacity data for MEA, data of vapor-liquid equilibrium, heat capacity and heat of mixing for MEA-H20, and CO2 solubility data for MEA-H20-CO2 over a wide range of temperature, concentration and CO2 loading. The model was validated by the NMR speciation data and then used to build a process simulation for CO2 absorption/ desorption into 30%（mass） MEA. The simulation results match the pilot plant data in literature. For 30%（mass） MEA solution, when the CO2 removal rate in the absorber is 90%, the reboiler heat duty is the minimum by changing the mass flow ratio of liquid to gas in the absorber. The minimum reboiler heat duty is 3.64 GJ＇（t CO2）-l, when the ratio is 2.