MEA and Piperazine Corrosion of Carbon Steel and Stainless Steel

Abstract

Two methods were developed to measure the corrosion of 1010 carbon steel and 316L stainless steel in solutions of ethanolamine, piperazine, and several other linear amines at high temperature and pressure. The effect of amine concentration, CO2 loading, and temperature were measured. The first method uses Swagelok® steel cylinders heated in ovens to accelerate corrosion of the metal surface, which is then estimated by measuring dissolved metal. Although the steel cylinder method gave reasonable corrosion rates for 316L SS, it significantly under predicted the corrosion rate of 1010 CS. This is likely due to the weakly adhering passive film that was protective only at the stagnant conditions in the non-agitated cylinders. The second method uses an electrical resistance probe to measure corrosion in a bench-scale thermosiphon apparatus, which was constructed to simulate more realistic flow conditions. Both methods were used to examine a series of linear amines and their results were compared. Corrosion of the electrical resistance probe by a variety of degraded piperazine solutions from pilot plants was measured. Loading was found to be the dominant factor in piperazine corrosion. Counterintuitively, corrosion rates of stainless steel decrease at high loadings, probably due to the formation of a FeCO3 film. Degraded piperazine was only slightly more corrosive than clean piperazine at most conditions. Over a wide variety of conditions, 1010 carbon steel showed lower corrosion rates in piperazine solutions than 316L stainless steel.