不同碳捕集场景下MEA/MDEA混合胺溶液的适用性分析

Applicability analysis of MEA/MDEAblended amine solution under different carbon capture scenarios

醇胺溶液吸收CO_(2)是工业上固定碳排放源碳捕集时最常用的方法,然而,捕集过程中的能耗问题一直是限制其大规模应用的主要障碍。通过提高化学吸收法入口处烟气中CO_(2)的含量,可提高吸收效率,在一定程度上实现降低能耗的降低。醇胺溶液的种类繁多,其中单乙醇胺(MEA)和甲基二乙醇胺(MDEA)因其良好的性能而备受关注。研究人员对醇胺溶液在燃煤烟气中的捕集性能进行了广泛研究,但鲜少对其他烟气工况下的吸收剂降低捕集能耗的效果进行相关研究。为了研究不同碳捕集场景下MEA/MDEA混合胺溶液适用性,获得不同碳捕集场景下MEA/MDEA混合胺溶液的最佳配比,使用Aspen Plus软件搭建了CO_(2)年捕集量为50万t的燃烧后碳捕集系统,对比分析了贫液负载、吸收压力以及解吸压力等关键操作参数对捕集过程中混合胺溶液胺流量、富液负载、循环容量以及再生能耗的影响,为不同碳捕集工况下捕集过程中操作参数的选择提供了依据。同时,对不同碳捕集场景下,不同配比的混合胺溶液的捕集性能展开深入了研究。结果表明,在同一碳捕集场景下,不同配比的混合胺溶液的性能呈现出较大差异,配比为1∶4的MEA/MDEA溶液对CO_(2)浓度变化最为敏感,当CO_(2)质量浓度从5%提高至55%时,再生能耗下降了40.07%。最后,通过层次分析法获得了不同碳捕集场景所适用的混合胺溶液的最佳配比:在CO_(2)质量分数为5%的碳捕集场景中,质量配比为4∶1的MEA/MDEA混合胺溶液性能最佳;在CO_(2)质量分数为15%的碳捕集场景中,质量配比为2∶3的混合胺溶液性能最佳;而在CO_(2)质量分数为25%~55%的碳捕集场景中,则是质量配比为1∶4的混合胺溶液呈现出最佳的性能。

The absorption of CO_(2)by alcohol amine solution is the most commonly used method for carbon capture from fixed carbon emission sources in industry.However,the energy consumption in the capture process has always been a major obstacle to its large-scale application.By increasing the content of CO_(2)in the flue gas at the inlet of the chemical absorption method,the absorption efficiency can be improved,and the energy consumption can be reduced to a certain extent.There are many kinds of alcohol amine solutions,among which monoethanolamine(MEA)and methyldiethanolamine(MDEA)have attracted much attention due to their good performance.Researchers have extensively studied the capture performance of alcohol amine solutions in coal-fired flue gas,but few studies have been conducted on the effect of absorbents on reducing capture energy consumption under other flue gas conditions.In order to study the applicability of MEA/MDEA blended amine solution under different carbon capture scenarios and obtain the optimal ratio of MEA/MDEA blended amine solution under different carbon capture scenarios,a post-combustion carbon capture system with an annual CO_(2)capture capacity of 500000 tons was built by Aspen Plus.The effects of key operating parameters such as lean liquid load,absorption pressure and desorption pressure on amine flow rate,rich liquid load,cycle capacity and regeneration energy consumption of blended amine solution in the capture process were compared and analyzed,which provided a basis for the selection of operating parameters in the capture process under different working conditions.At the same time,the capture performance of blended amine solutions with different carbon capture scenarios and different ratios was studied in depth.The results show that the performance of blended amine solutions with different ratios under the same carbon capture scenarios is quite different.The MEA/MDEA solution with a ratio of 1:4 is most sensitive to the change of CO_(2)concentration.When the mass concentration of CO_(2)increases from 5%to 55%,the regeneration energy consumption decreases by 40.07%.Finally,the optimal ratio of blended amine solution suitable for different carbon capture scenarios was obtained by analytic hierarchy process(AHP):in a carbon capture scenario with a CO_(2)mass fraction of 5%,the MEA/MDEA blended amine solution with a mass ratio of 4:1 has the best performance;in the carbon capture scenario with a CO_(2)mass fraction of 15%in the flue gas,the blended amine solution with a mass ratio of 2:3 has the best performance;in the carbon capture scenario where the mass fraction of CO_(2)in the flue gas is 25%-55%,the blended amine solution with a mass ratio of 1:4 exhibits the best performance.