N-Methyldiethanolamine (MDEA) is widely used in the treatment of acid gas streams containing hydrogen sulfide and carbon dioxide in industry, and it can absorb hydrogen sulfide and part of carbon dioxide. At home and abroad, many experiments have been carried out on the absorption of acid gas by methyldiethanolamine, and it has been industrialized and achieved good results. Due to the continuous development of the process, it is urgently needed for MDEA to make an accurate prediction of the absorption effect of hydrogen sulfide and carbon dioxide. However, the complexity of the absorption process, including chemical reaction balance, physical absorption, and kinetic factors, makes it difficult to accurately predict the absorption of hydrogen sulfide and carbon dioxide.
Aiming at the desulfurization and decarbonization process in the natural gas purification plant, the concept of equilibrium solubility and material balance were used to establish a mathematical model for the selective absorption of H2S and CO2 in N-methyldiethanolamine aqueous solution, and simulated calculations for the actual industrial process . Factors such as operating pressure and amine circulation volume were examined separately to analyze the absorption tower’s absorption of acid gas. A comparison was made under working conditions. Based on the data simulation results, the improvement measures and methods under this specific condition are put forward, that is, the method of removing carbon dioxide in the middle stage can be used to reduce the volume fraction of carbon dioxide in the gas stream from 4.7% to 3%, which meets the production requirements. These results provide a theoretical basis for the actual operation and modification of the absorption tower.
