Numerical investigation of aluminium hydrochlorination in a fluidized bed reactor via the MP-PIC model

Abstract

This study numerically investigates gas–solid flow behaviour and reactive species transport during the hydrochlorination of aluminium in a fluidized bed reactor (FBR) operating at a temperature of 523 K. The present study reports the first numerical investigation of the aluminium hydrochlorination reaction. The hydrogen chloride (HCl) gas inlet flow rates are varied as 0.1, 0.2, and 0.3 lpm. A coupled Eulerian–Lagrangian approach employing the MP-PIC model is utilized to resolve solid–gas momentum exchange, species consumption, and product formation. In the MP-PIC model, the gas phase is treated as a continuum Eulerian phase and the solid aluminium particles are represented by Lagrangian particles. To perform the simulation, a reactor having a height of 570 mm and a diameter of 12 mm is considered at a temperature of 523 K. The results reveal that the low-velocity regime produces distinct hydrodynamic characteristics when compared to high flow rates. Furthermore, the results showed that decreasing the flow rate enhances the consumption of HCl and increases the production of aluminium chloride (AlCl₃) and hydrogen (H₂) along the reactor height. At a flow rate of 0.1 lpm, the extended residence time enables the highest conversion, while increasing the flow rate to 0.3 lpm leads to an incomplete reaction despite improved mixing and turbulence. The finding highlights the dominant role of residence time in low-flow hydrochlorination and provides insights into the optimal operation of a small-scale fluidized bed reactor for aluminium hydrochlorination.