Research On Mixed Absorbent And Optimiaztion Of CO₂ Capture Process

Chemical absorption,as a kind of post-combustion capture technology,is a widely used,but still suffering from high energy consumption and high initial investment cost.In this paper,combining experiment with simulation was adopted to optimize the operation scheme of a single absorbent,develop new typies of low regeneration energy of the mixed amines absorbent and carry out the coupling optimization of advanced technology,in order to provide a low-energy operation scheme for subsequent engineering applications.In this paper,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.Then the CO₂chemical absorption process based on high concentration MEA absorbent was improved.The important process parameters such as lean CO₂loading,stripping pressure,terminal temperature difference of the rich-lean heat exchanger and CO₂removal efficiency were optimized.Then,the novel coupling processes were investigated,which include absorber inter-cooling,rich-split and MVR processes.The results show that 40wt.%MEA has great potential in reducing energy consumption.When the lean loading was 0.25mol CO₂/mol MEA and removal efficiency was 90%,the regeneration energy of 40wt.%MEA was2.61GJ/t CO₂,which was 34.75%lower than that of traditional process based on30wt.%MEA.Three kinds of novel mixed amines were proposed.The absorption performance,regeneration performance and physicochemical properties of different concentration ratios were studied through the rapid screening experiment device.The results showed that the concentration ratios with better performance were 22wt.%（～2.5m）AMP+12wt.%（～2m）MEA,28wt.%AEEA+7wt.%AMP and 32wt.%AEEA+3wt.%DEA,among which 2.5m AMP+2m MEA（MAH）was most likely to realize industrial application.Based on the above experiments,this paper researched the potential of MAH mixed amines absorbent in the aspect of reducing energy consumption through process simulation optimization.According to the datas of thermodynamic experiments,the physical properties of AMP and its reaction products by fitting regression were embedded in the electrolyte system of Aspen Plus,and the property package of MAH missed absorbent was established.Therefore,the deviation of physical properties of the new absorbent was made up.Based on the strict MAH chemical absorption of thermodynamic model,a mixed amines absorption process was built for 150,000-ton per year CO₂capture project through the general simulation software Aspen Plus,and combining with pilot platform experimental data to complete the validation of the model.The new process of basic operation parameters and coupling operation parameters were optimized.When the lean loading was0.23mol CO₂/mol MEA and removal efficiency was 90%,according to the proportion of MAH,increasing the concentration of absorbent to 40wt.%,the regeneration energy of 40wt.%MAH was 2.44GJ/t CO₂,which was 39%lower than that of traditional process based on 30wt.%MEA.In this paper,the low regeneration energy absorbent and the process of CO2capture were studied systematically.Main conclusions of the research have contributed to engineering applications.