Improving Mechanistic CO2 Corrosion Models

CO₂ corrosion is observed in the oil and gas industry. It is becoming an increasing problem in the power industry due to the demand for CO₂ capture. The research community has had an increased focus on the specific problem in order to develop predictive models for forecasting process equipment corrosion rates.

Several models have been developed since 1970. Mechanistic models were developed through the 1990's. During 2001 a mechanistic model was published by Nesic and co-workers. It incorporates a core electrochemical model coupled to a diffusion and a bulk equilibrium model.

Diffusion theory developed by Nernst-Planck is being used in the corrosion models. Unfortunately this theory is only applicable to diluted ideal solutions of low ionic strength and may not be applied to higher concentrations which are found in wet gas pipelines.

We seek to improve corrosion models by extending the above theory to non-ideal realistic systems. The drawback and limitation of current models are presented, the theory is extended, and examples will be shown how to improve the theory to high ionic strength solutions. Calculations will show how large deviations are generated by assuming non-ideal solutions to be ideal. The theory is general and applicable to other electrolyte diffusion problems.