基于高浓度MEA的CO_(2)化学吸收工艺优化

Optimization of CO_(2) Chemical Absorption Process Based on High Concentration MEA

工艺改进优化是降低CO_(2)化学吸收工艺再生能耗的有效方法。对基于高浓度乙醇胺(ethanolamine,MEA)吸收剂的CO_(2)化学吸收捕集工艺进行了改进,通过大型通用流程模拟软件Aspen Plus,结合汽液平衡、热容等热力学实验数据,建立了高浓度MEA化学吸收热力学模型,并与中试平台的实验结果进行对比验证,结果表明,模型能够准确地预测CO_(2)吸收和再生过程。对贫液负荷、再生塔压力、贫富液换热器端差、捕集率等重要工艺参数进行了优化,并对耦合的新工艺进行了研究,包括级间冷却工艺、富液分级流工艺和蒸汽机械再压缩技术(mechanicalvapor recompression,MVR)工艺。研究表明,40%MEA在降低能耗方面的潜力较大,传统工艺和新型工艺参数的联合优化能够有效降低再生能耗。综合优化后,基于40%MEA吸收剂的新型工艺,贫液负荷为0.25mol CO_(2)/mol MEA,捕集率为90%时,再生能耗为2.61GJ/tCO_(2),相比基于30%MEA吸收剂的传统工艺(4.0GJ/tCO_(2))降低34.75%。

The improvement and optimization of the process are effective methods to lower the energy penalty of carbon capture technology. In this paper, the CO_(2) chemical absorption process based on high concentration ethanolamine(MEA) absorbent was improved. Based on Aspen Plus process simulation software, combined with thermodynamic experimental data such as vapor-liquid equilibrium and heat capacity, the high concentration of MEA chemical absorption thermodynamics model was established, which is validated against experimental results from the pilot platform. The results indicate that the model could accurately predict the CO_(2) absorption and stripping process. The important process parameters such as lean CO_(2) loading, stripping pressure,terminal temperature difference of the rich-lean heat exchanger and CO_(2) removal efficiency were optimized. Then, the novel coupling processes were investigated, which include absorber inter-cooling, rich-split and MVR processes. The results show that 40% MEA has great potential in reducing energy consumption. The joint optimization of the parameters of the traditional process and new process can effectively reduce regeneration energy. After comprehensive optimization, when the lean loading was 0.25 mol CO_(2)/mol MEA and removal efficiency was 90%, the regeneration energy of 40%MEA is 2.61 GJ/tCO_(2), which is 34.75% lower than that of traditional process based on 30 wt.%MEA(4.0 GJ/tCO_(2)).