不同碳捕集场景下 MEA / MDEA 混合胺溶液的适用性分析

The absorption of CO₂ 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 CO₂ 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 CO₂ capture capacity of 500 000 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 CO₂ concentration. When the mass concentration of CO₂ 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 CO₂ 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 CO₂ 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 CO₂ in the flue gas is 25%-55%, the blended amine solution with a mass ratio of 1:4 exhibits the best performance.