Absorption of acid gases (CO2, H2S) from natural gas using a ternary blend of N-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), and Sulfolane

Abstract. Natural gas (NG) must be treated to remove sulphur compounds and acid gases i.e., carbon dioxide (CO2) and hydrogen sulfide (H2S) to ensure that it complies with requirements for sale and transportation. More than 95% of the NG processing plants are operated through the acid gas removal unit (AGRU) using aqueous amine solvent in removing sour gas components from the hydrocarbon gas due to the availability of amine solvent at a low cost. However, the main limitation of this process is the high operating cost of providing sufficient thermal energy at the reboiler for solvent regeneration. Meanwhile, the reboiler duty requirement generally increases with the requirement of CO2 removal efficiency as higher energy consumption is required to strip off a more significant amount of CO2 from the rich solvent. This current study addresses the absorption performance of acid gases using ternary hybrid solvents of MDEA, AMP, and Sulfolane. A study on the effects of solubility on H2S and CO2 absorption was performed at varying pressure (1000-6000 kPa) and temperatures (25°C-50°C) using Aspen HYSYS®V12.1. The results revealed that the concentration of CO2 and H2S in sweet gas increased with the decrease in pressure, while increasing temperature increased the concentration of H2S and CO2 in sweet gas. The future study will look at the reboiler duty required for solvent regeneration using this ternary blend of MDEA, AMP, and Sulfolane.