Simulation and optimization of amine sweetening process

Amine sweetening is the most vital segment of the gas processing plant, which contributes to the removal of H₂S, CO₂ and other minor contaminants such as COS and mercaptans. The work attempts to improve the efficiency of the gas processing process through a process simulation exercise towards which ProMax was utilized. A base case simulation mimicking a real operational amine sweetening plant was developed using process parameters and flow rates currently being in practice. Based on a thorough literature search, it was understood that parameters such as the pH, heat stable salts, regenerator pressure, and absorption column intercooling were found to influence the plant efficiency. The present work attempts to assess the effect of the above said parameters on the base case simulation and identify optimal conditions to enhance the overall efficiency. A decrease in the pH was attempted through the addition of different acids, and it was not found to improve the efficiency of the operation as stated in the literature pertaining to MEA solvent. In other words, the regenerator energy consumption was found to increase with the increase in the acid concentration. An increase in the regenerator pressure was found to decrease the regenerator energy requirement contributing to better energy efficiency, with the optimal operating pressure being 2.5 bar. An increase in the heat stable salts at a controlled concentration was found to improve the absorption efficiency of the H₂S while had no significant effect on CO₂ absorption. The application of intercooler improved the absorption efficiency of both H₂S and CO₂ as well as reduced the reboiler heat duty. The combination of optimal conditions revealed that the plant processing capacity could be increased to about 4.2 % with an energy reduction of 81,000 tons of steam per year.