Abstract
A linear polarization resistance probe was used to study corrosion rates in oil sands dense slurries. The study was conducted in a pilot-scale horizontal slurry flow loop with nine test conditions evaluated. Slurry consisted of a bimodal (sand and rocks) particle distribution mixed with municipal water. The sand had a median size, d50 of approximately 0.776 mm and spread (d90 / d10) ratios in the range of 2.5 to 3.5. The rocks ranged in size from 6 to 12 mm (0.25 to 0.5 inches). The study was done in a 193.7 mm (7.625 inch) carbon steel pipe flow loop with mixture velocity and solids concentration of 4.5-7.0 m/s and 19.3-29.1 v/v%, respectively. The oxygen was injected to achieve a dissolved oxygen concentration of 1.0 ppm to 11.7 ppm. The measured corrosion rates were used to validate five existing corrosion rate models. The interaction of slurry flow characteristics and corrosion is a complex phenomenon and poses a significant challenge for any modeling attempts. Nonetheless, several findings in this work can be leveraged for corrosion predictions. The slurry effect on corrosion was not linear but depended highly on slurry flow regime, fines content, dissolved oxygen concentration, and local solids concentration and velocity distributions. In general, most existing models either overestimated or underestimated corrosion rates, with a couple showing some promise for further evaluation.
