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RESEARCH PRODUCT

Corrosion in alcanolamines for natural gas treatment - High temperature experiments in lean and rich conditions

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International audience; In the oil and gas industry, acid gas removal is required for the treatment of natural gas. New applications were also recently pushed forward for CO 2 capture from the flue gas of power plants. For both applications, the most widespread industrial processes use absorption-desorption by an alcanolamine solvent. In such amine units for acid gas removal, corrosion represents an important operational concern. Influent parameters governing corrosion are temperature and acid gas loading, amine nature, and the presence of degradation by-products. Some of these parameters were studied with corrosion experiments in autoclave. Test temperature was between 110°C and 120°C, i.e. within the inlet and outlet temperatures of the regenerator where the risks of corrosion are the highest. CO 2 loadings of rich solvent representing absorber outlet conditions (α close to 0.5 mol of CO 2 per mol of amine) and of lean solvent similar to regenerator outlet conditions (α close to zero) were tested. Different blends of amine solvents were used. Corrosion rates of carbon steel and of some stainless steel grades were examined through weight loss experiments and surface analysis. Concentrations of dissolved metallic species were also analysed. The more severe corrosion risks were found in the pure DEA solutions. In rich conditions, AISI 304L could suffer depassivation and uniform corrosion. This corrosion was increased in an industrial DEA solution, containing higher levels of degradation products. In the MDEA and MDEA / DEA solutions, the corrosion rates were considerably lowered for 304L and for C steel.