The Equipment Developent And Techonlogy Research Of Biogas Alkali Chemical Absorption Purification

In recent years, Biogas purification is an important means of high utilization of biogas, with continuous growth of biogas production in China.The commonly used biogas purification methods mainly includ in-situ method and ectopic method, ectopic method mainly contain high pressure water washing, alkali chemical absorption and membrane method. Selected alkali chemical absorption method, designed a set of alkali chemical absorption device for biogas purification, using real biogas, to provide data support for industrial application of biogas purification.According to the experiment scheme, a set of alkali chemical absorption pilot device for biogas purification which can purify 20m3/h biogas was designed, and the critical part of the design process and auxiliary equipment was calculated and selected. After the leak testing,debugging, cleaning, purification device build in the factory can run stably.In this paper, by using the designed pilot plant as the absorption equipment, 20%MEA, 30%MEA, 30%MDEA and 30%MDEA+20%MEA(mixed amine) as absorbent, the absorption performance of real biogas was measured. Found that the gas flow rate, absorbent flow rate, temperature,operating pressure, absorbent solution and gas-liquid ratio will affect the efficiency of purification, temperature, operating pressure and absorbent solution will affect the regeneration solution pH and CO2 load. MEA has a good absorption effect,30% (20%) MEA’s purification efficiency was 100%as gas-liquid ratio is lower than 55 (30),regeneration liquid CO2 margin was 0.15 (0.125) mol/molMEA, but the degradation phenomenon was found with high desorption times. The absorption effect of 30%MDEA is worse than that of 20% and 30%MEA,and gas-liquid ratio must be lower than 15. While with better desorption performance, regeneration liquid CO2 margin being 0.05 mol/molMDEA. The mixed amine has good absorption and desorption effect, the gas-liquid ratio is lower than 35,which can reach the purification requirement, and the absorption capacity is lower than that of the two absorption effect, but higher than that of the single component. The desorption performance were better than MEA and lower than MDEA, and the analytical solution CO2 margin is 0.09mol/mol mixed amine. The unit energy consumption per unit volume was only 72.2%of 30%MDEA energy consumption and 20%MEA energy consumption.In summary, the design of the pilot test device for purification, found that MEA has the best absorption ability, MDEA has the best desorption performance, and mixed amine has good absorption ability, low energy consumption level, and high prospect of biogas tpurification engineering application, providing data support for the biogas purification engineering.