Formation of heat stable salts during thermal degradation of aqueous methyldiethanolamine (mdea) solvent and corrosion studies with different alloys

The objective of this research work was to study the formation of heat stable salts (HSS) during thermal degradation of Methyldiethanolamine (MDEA) solvent and to check the corrosion rates for different alloys. HSS such as acetate, formate, sulfates, thiosulfate, glycolate, nitrate etc. were formed with varying concentrations during thermal degradation of MDEA. The corrosion rates of three different specimen of alloys, namely SS-304, SS-321 and Hastelloy-x, under thermal degradation of lean MDEA (46.34 weight %) from Gasco, Habshan (Abu Dhabi) and 46 weight% fresh MDEA loaded with H2S and RSH at 130ºC were observed. The corrosion rate using lean MDEA at a stirring speed of 700 rpm and at 130°C were observed as SS-321 (0.2977 millimeter/year as ‘mmy’), Hastelloy-x (0.1859 mmy) and SS-304 (0.11396 mmy). The fresh MDEA solutions were degraded at 130ºC with and without stirring pat 700 rpm. Formation of HSS was much higher when fresh MDEA degraded thermally without stirring. Thermally degraded fresh MDEA solution without stirring has no effect on SS-304 but corroded the Hastelloy-x at 1.0214 mmy. Thermally degraded fresh MDEA solution loaded with H2S and RSH and stirred at 700 rpm corroded the specimens most as SS-321 (64.7144 mmy), SS-304 (60.8032 mmy) and Hastelloy-x (0.2678 mmy).