Removal of acid gases by hydrogen sulfide (H2S) and carbon dioxide (CO2) from natural, refinery or synthesis gases in large volume is most conveniently accomplished by absorption in a suitable solvent. Most familiar gas treating processes employ an amine-containing solvent that can be re-used by desorbing the acid gases through release of pressure and application of heat. The Shell Sulfmol process represents an improved version of these processes and utilizes a novel solvent composed of di-isopropanolamine (DIPA), sulfolane and water. The Sulfinol process offers many advantages over competitive systems1-3 including better corrosion characteristics. In general, carbon steel has been used successfully for equipment items in plants where significant H2S is present. In plants where H2S is absent, such as in treating hydrogen from steam-methane reformers, carbon steel has been used for most equipment items with austenitic stainless steels used in certain areas. In neither case are corrosion inhibitors necessary. Laboratory and pilot plant tests combined with prior experience with aqueous alkanolamine systems provided the information necessary for materials selection in the first commercial plants. Corrosion history of the plants has been good. In a few areas, plant experience has led to modification of the original materials selections.
