Ultra-Sour Natural Gas Sweetening Using Membranes/Amines Hybrid Systems for Recurrent Middle East Conditions

Abstract

Abstract Recently an increasing number of countries have expressed their concerns over meeting their future gas domestic demands and export commitments. This tendency is particularly palpable in the Middle East countries. Thus, the region's gas producers have been compelled to develop unconventional ultra-sour gas fields previously considered uneconomic due to technical challenges. Conventional gas processing considers chemical absorption methods using solvents (such as an alkanolamine) for acid gas (e.g., H2S and CO2) removal. However, new polymeric membranes for bulk H2S removal from both very high H2S content gas and operating pressures have been recently developed. These recent developments can contribute to the treatment of unconventional ultra-sour gas or retrofitting existing plants. Accordingly, the present study analyzes a hybrid sour gas sweetening system consisting of two stages. In a first stage, a membrane system is used to reduce the inlet feed gas bulk H2S and CO2 concentrations. Consecutively, the sweet gas product final specifications are met using an amine-based system. Ultra-sour gas (e.g., 25% H2S) is considered to be treated. The study uses a simulation-based optimization approach. The proposed hybrid process was simulated using ProMax® v3.2. The ultra-sour gas conditions are uncommon on a global scale, but they can be found recurrently in the Middle East. The simulation results show that the operating and capital expenditures of the process can be reduced using a hybrid system.