CFD Simulation of Hydrogen Sulfide (H₂S) Desulfurization Using Ionic Liquids and Graphene Oxide Membrane

Abstract

Hydrogen sulfide (H2S) is considered a toxic and corrosive gas, commonly found in natural gas, crude oil, and other fossil fuels. This corrosive gas may lead to stress corrosion cracking (SCC). This phenomenon is caused by the combined influence of tensile stress and a corrosive environment. This may lead to the sudden failure of normally ductile metal alloys, especially at an elevated temperature. Desulfurization is the process of removing H2S from these fuels to reduce their harmful environmental and health impacts. Ionic liquids (ILs) have shown great potential for application as liquid absorbents for H2S extraction because of their advantages such as non-volatility, functionality, high carbon solubility and low energy requirements for regeneration. The proposed hydrogen sulfide extraction system consists of a tube, membrane and shell. 1-ethyl-3-methylimidazolium (emim)-based ionic liquids with bis-(trifluoromethyl) sulfonylimide (NTf2) anion has been selected due to its high H2S diffusion coefficient. Functionalized graphene oxide (GO) advanced membranes have been employed in this design. In this research, H2S extraction with ionic liquids has been numerically studied. The COMSOL finite element and multi-physics code has been employed to solve the continuity, turbulent fluid flow (k-ε model), and transient diffusion equations. For small time periods, there is sharp gradient in H2S concentration profile inside the shell section. This is because the diffusion coefficient of H2S in the ionic liquid is very small and the shell section is much thicker than the membrane. It has been determined that H2S is absorbed almost completely by ionic liquids after a time period of 30,000 s.

Keywords

• hydrogen sulfide
• desulfurization
• ionic liquid
• COMSOL multiphysics code
• Reynolds average Navier–Stokes (RANS)
• diffusion equation