Corrosion in amine units for acid gas treatment : a laboratory study

Abstract

International audienceCorrosion represents one of the most important operational issues in amine units used for acid gas treatment. Considerable experience is available in the literature both on laboratory and in the field. Based on this experience, proven mitigation strategies are available, using corrosion inhibitors or corrosion resistant alloys at selected locations in the plant. However, the technical causes of the corrosivity of amine solvents are still not well understood. Furthermore, recent field experience showing severe corrosion in sweet units pointed out the difficulty to transpose design solutions from sour to sweet gas. There is obviously a need for more precise data on the impact of different parameters on amine units corrosion. For this study, experimental work was focused on sweet Diethanolamine (DEA) systems. The impact of acid gas loading and temperature was examined deeply. Electrochemical and weight loss measurements were performed on carbon steel, AISI 410 and AISI 304L. At the same time, thermodynamic calculations were used to determine the composition of the solvent at different temperature and CO 2 loading. For each experimental condition, it was possible to calculate the concentrations of different species, such as carbonate, bicarbonate, residual amine, carbamate, protonated amine and the pH. The comparisons between corrosion data and test solution composition give helpful indications to better understand the causes of the increased corrosivity of highly loaded solvents