Experiment Investigation Of Carbon Dioxide Separation By Chemical Absorption Method

Greenhouse effect induced by the emission of greenhouse gases has become the mostserious environment problem that mankind confronts recently．CO₂has the greatestcontribution to greenhouse effect in various greenhouse gases. The amount of CO₂frompower plant accounts for30percent of all the emission caused by human activity. So howto removal CO₂from flue gas of power plants is the sticking point on easing greenhouseeffect．Chemical absorption method is thought as one of the more mature CO₂capturetechnologies. In this paper, chemical absorption method （alcohol amine and ionic liquid）have been studied. The effect of different absorbent, absorbent concentration and absorbentregeneration cycle times on absorption efficiency have been investigated. Thentechno-economical analysis is compared preliminary for a400MW coal-fired power plant．The CO₂absorption performances of one-component amine （MEA and MDEA） havebeen discussed. MEA has great absorption rate and absorptive amount but absorbing loadper mole is low and MDEA opposite. Increasing the absorbent concentration is beneficial toimprove the absorption rate, but too much will decrease the absorbing load. Mixing the twoone-component amine can significantly improve the CO₂absorption efficiency. Theregeneration behavior of the amine absorbent is investigated. The result show that MEA hasa huge desorption energy consumption and long desorption time. After6times ofdesorption cycle，the regeneration rate reduce to44.5%. The mixture of amine（5:5） canimprove the regeneration behavior，after6times of desorption cycle，the regeneration rateof mixed amine is51.7%. More MDEA means lower desorption energy consumption andhigher regeneration rate.The experiment result of four ionic liquids absorb CO₂shows that：Alkaline functionalgroups （-NH2） add in conventional ionic liquid can improve the absorption efficiency ofabsorbent. The cationic carbon chain length of ionic liquids has a big impact on theabsorption effect. the regeneration behavior of the ionic liquid show that：ionic liquid has agreat regeneration performance，after8times of desorption cycle，the regeneration rate is high to94.4%.At the end of the thesis，the techno-economic analysis was compared preliminary withdifferent absorbents. A400MW coal-fired plant was chosen as an example. The resultshows that MEA has the highest absorbing cost，which is250.1yuan per ton CO₂. Althoughthe material cost of ionic liquids is400times that of MEA，it has a lower absorbing costthan MEA，which is224.6yuan per ton CO₂，for its amazing recycling rate. Mixed amine isthe lowest, which is207.2yuan per ton CO₂in this paper.