Research On The CO₂ Phase-Changing Absorbent Based Of MDEA

Traditional single hydramine absorber cannot be good performance of both absorption and desorption process. Primary amine, secondary alcohol amine has good absorption performance but desorption performance is poor, tertiary amine has low desorption energy consumption, but the absorption rate is poor. In order to make up for the shortage of the single hydramine absorber, researchers devoted to exploit high property absorbent which contains"high absorption rate, large capacity, low energy consumption."At present the development of new type absorbent mainly concentrated in the ionic liquid absorbent, compound amine absorber, etc. But according to the results of the present study, ionic liquid cause of absorbent viscosity, high cost, is not suitable for industrialized operation; compound amine absorbent can only promote in a limited degree on absorption or desorption properties. Therefore, CO2 phase-changing absorbent can greatly reduce desorption capacity, lower the energy consumption of desorption, as a new type of high-performance absorbent, which gradually get the attention of the researchers.This study based on MDEA as chemical absorbent, through the systematic experiment, selected with a phase-changing absorbent, which has several advantages such as quick absorption rate, low desorption energy consumption ang large difference of two phase of CO2 loading after phase splitted. On this basis, use the MDEA-n-butyl alcohol-water phase-changing absorbent to conducted systematic continuous experiments, provides a preliminary experimental basis of large-scale industrial application of carbon capture technology.At the same time, has carried on the positive exploration of the feasibility with other solvent blended phase-change absorbent.Results shows that using the mass fraction 30% MDEA+ 30%n-butyl alcohol+30% water phase-changing absorbent, at 20℃ for absorption and 80℃ for desorption, compared with the 30%MDEA, the initial absorption rate has obvious improvement, the upper loading is only 5.27% of that in the lower liquid after phase splitted. And lower liquid volume was only about 61.9% of the total volume, the absorbent of n-butanol components was only 7.04% of the total, and the desorption energy consumption dropped to 2873.3 kJ/kgCO2, compared with 30% MDEA absorber reduces about 1/3. MDEA-n-butyl alcohol-water phase-changing absorbent can promote both absorption performance and desorption performance, and has a good cycle effect, make a great significance to reduce energy consumption of desorption and lower carbon capture cost.