Development of a mechanistic corrosion model for carbon steel in MEA-based CO2 absorption process.

Date
2012-07
Authors
Najumudeen, Ameerudeen
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Faculty of Graduate Studies and Research, University of Regina
Abstract

This work developed a mechanistic corrosion model that can be used to predict corrosion rate of carbon steel in the carbon dioxide (CO2) absorption processes using aqueous solutions of monoethanolamine (MEA). The developed model enhances the capacity of the existing corrosion model developed by Veawab (2000) by incorporating three additional features including the presence of iron carbonate (FeCO3) on the metal surface and the presence of dissolved oxygen (O2) and heat-stable salts (HSSs) in the aqueous MEA solutions. The model was developed in Matlab, and comprises three sub-models, i.e. vapour-liquid equilibrium (VLE), species diffusion through a porous film, and electrode kinetics on the metal-solution interface. Two VLE sub-models, i.e. the Kent-Eisenberg (K-E) and the electrolyte non-random two-liquid (e-NRTL), are built into the model. The inputs required for model simulation are three process variables of the CO2 absorption process, i.e. solution temperature, MEA concentration, and CO2 loading of the MEA solution. The outputs from the model simulation can be presented as species concentrations in bulk solution and at the metal-solution interface, polarization curves, and corrosion rate. Simulation results show that the model using the e-NRTL sub-model better describes the experimental polarization curves obtained from the literature than the model using the K-E sub-model. The presence of either dissolved O2 or acetic acid (as HSS) does not affect corrosion of carbon steel, whereas the presence of the FeCO3 film on the metal-solution interface retards the diffusion of oxidizing agents and, in turn, reduces corrosion rate. Sensitivity analysis for parametric effects on corrosion was also carried out to reveal primary oxidizing agents contributing to corrosion in various operating conditions.

Description
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Industrial Systems Engineering, University of Regina. xviii, 123 l.
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