Hydrodynamics and flow-accelerated corrosion in a stirred crystallizer: Experiment and simulation

The industrial stirred crystallizer was scaled down to a lab-scale stirred vessel, and an easy and effective experimental method was designed to investigate the bubble behavior and flow-accelerated corrosion on the crystallizer. Results show that there was inhomogeneous bubble behavior in the lab-scale equipment, which could be divided into Quickly Released Bubbles and Slowly Released Bubbles. Slowly Released Bubbles have little effect on the flow-accelerated corrosion in the stirred crystallizer, while Quickly Released Bubbles makes evident influence on that. The dynamics of Quickly Released Bubbles was divided into 2 stages: (1) coalescence stage, (2) stage of bubble-wall collision and break-up. The second stage of bubble motion greatly enhances cavitation damage. An Eulerian three-fluid model for the gas-liquid-solid three-phase flow in the crystallizer was proposed and the CFD simulation was carried out. The values predicted by CFD simulation for gas holdup agreed well with experimental data. Simulation results of corrosion rate in bubble-wall “collision region” also agreed well with corrosion phenomena in industrial equipment, which can provide the basis for the further research of industrial application.