Preparation of inorganic salt particles by reactive crystallization in an annular swirling flow reactor

Abstract

This study investigates the performance of an annular conical swirling flow reactor in liquid–liquid reactions for the preparation of inorganic salt particles. Utilizing Particle Image Velocimetry (PIV) measurements and Computational Fluid Dynamics (CFD) simulations, it was observed that the conical design effectively inhibited the attenuation of swirling flow intensity along the axial direction, with the primary mass transfer region close to the central conical wall. In comparison to a stirred reactor, calcium carbonate particles synthesized in the swirling flow reactor exhibited more uniform morphology, smoother and defect-free surface. Notably, the average particle size remained consistently within 5–6 μm (excluding the 0.3 M feedstock), whereas stirring led to particles with an average size ranging from 8-11 μm. Analysis of the residence time distribution curve revealed minimal back mixing in the swirling flow reactor, ensuring nearly equal growth time for salt particles, thus yielding particles with a uniform size distribution. As a result, the swirling flow reactor presents compelling prospects for applications in reactive crystallization.