Evaluation of the Diffusive Capacity of Hydrogen Through 9Cr-1Mo Ferritic Steel in the Dual Environment of a Furnace: a Simulation Study in Comsol Multiphysics®

Abstract

Hydrogen transport and storage represent a challenge due to its high diffusivity capacity, which causes the pitting of pipes. This study focused on addressing this problem by simulating the effect caused by the hydrogen generated during the heating pre-processing step of crude oil before addressing it to the distillation unit. For this purpose, the software COMSOL Multiphysics® was employed to determine how the hydrogen diffusion across ferritic steel containers increases the corrosion rate in a furnace. Then, a dual corrosion process was assessed at 650 °C, simulating the flow of water vapor at the outer part of the pipe whereas hydrogen sulfides -as contamination from crude oil- at the inner part. The ferritic steel selected for this research was the 9Cr-1Mo steel due to its usual implementation in processes developed at high temperatures in industry. Besides, we also studied the corrosion rate of both pipe’s faces independently, omitting the effect of the other fluid on the other side of the pipe -singular environments-. The influence of hydrogen sulfide on the corrosion rate on the water vapor side was found negligible. Meanwhile, water vapor boosted the corrosion rate on the hydrogen sulfide side, making it 1.2 times greater compared to its singular estimation. The corrosion rate induced by the water vapor is higher due to the higher number of corrosion products -current density- that it delivers when reacting with the steel elements at high temperatures. These approaches aimed to quantify the hydrogen diffusion contribution to the corrosion rate of the ferritic steels used in oil refining furnaces.