Evaluation of erosion–corrosion in multiphase flow via CFD and experimental analysis

A numerical simulation is proposed of erosion–corrosion phenomena in four-phase flows comprising two immiscible liquids, gas and particulate solid. The simulation geometry is a pipe bend and the evaluated quantity is the wall erosion–corrosion brought about by the flow of a fluid mixture of two liquid phases, one of which is corrosive, plus a gas phase flow and a solid phase. A computational fluid dynamic tool has been adopted for the simulation of the flow field inside the piping and for the simulation of the particle trajectories and impact rates. As far as corrosion is concerned, a passivating and an actively corroding metallic material have been considered. Erosion model parameters have been derived from experiments correlating particle impact angle and erosion rate. Corrosion model parameters have been obtained from electrochemical measurements. The effects of the key operating parameters (fluid flow velocity, particulate content and gas volume fraction) have been evaluated by a two-level design of experiments approach. The single most important effects on synergistic damaging and on the ratio of corrosive to overall damaging have been identified. Erosion-enhanced and erosion-limited effects of flow conditions have been highlighted for the passivating and for the actively corroding alloys, respectively.