Simulation-based analysis for highly sour natural gas sweetening using membranes/amines hybrid systems

The most widely employed sweetening gas scheme considers chemical absorption by solvents for acid gases removal. While this scheme is both well-known and proven, its application for tapping highly sour gas resources can be operationally challenging, costly, and wasteful. Nevertheless, new polymeric membranes have been applied for bulk H₂S removal from natural gas, including very high H₂S concentrations and operating pressures. Recent developments on this area may contribute to the development of unconventionally high sour gas resources or potentially retrofitting existing plants. For instance, in a primary stage the membrane system could be used to reduce the bulk concentration of H₂S and CO₂ in the feed gas. Sequentially, the final sweet gas product specifications could be met using an amine-based system. Accordingly, this type of hybrid scheme could potentially help reducing capital and operating expenditures. The present study examines the sweetening of highly sour gas with 15% H₂S (i.e., over 20% of H₂S and CO₂ combined) applying a simulation-based analysis. The proposed hybrid process was simulated using ProMax® v3.2. The simulation results show that the operating/utility expenditures of the sweetening process could be reduced using a hybrid system approach (instead of a stand-alone amine system).