Aiming at the problems of excessive energy consumption and high methane loss in the device for capturing low-concentration CO2 in shale gas,taking the shale gas produced in northern Guizhou China as the research object,piperazine (PZ) activated N-methyldiethanolamine (MDEA) method was used to capture CO2,and Aspen HYSYS software was used to establish the process model for capturing low-concentration CO2,and chemical reaction formula was introduced to improve the calculation accuracy of the process model.Under the conditions of comprehensive investigation of CO2 capture effect,equipment energy consumption,methane loss and acid gas load of rich liquid,the formulation of amine liquid (MDEA and PZ mass fraction) was optimized,and the key parameters such as amine liquid volume flow,absorption temperature and regeneration temperature were optimized.On the premise of reaching the CO2 capture index,the optimal MDEA mass fraction was 37%～42%,and the optimal PZ mass fraction was 2.5%～5.0%.It was recommended that the optimal formula (mass fraction) of amine solution was 40%MDEA+3%PZ,the optimal circulation amount of amine solution was 45 m3·h-1,and the optimal regeneration temperature was 118 ℃.After optimization,the total energy consumption of the system was reduced by 8.9%,and the regenerative energy consumption was reduced by 12%,with remarkable energy saving effect.
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