CFD-PBE Simulation of para-Xylene Crystallization Behavior and Process Amplification under Different Operating Conditions

Abstract

The crystallization technology is one of the most potential ways to produce para-xylene (PX) with high purity, but it has some drawbacks such as low yield and difficult to control crystallization due to the insufficient study of the PX nucleation characteristics and growth behavior. To further investigate this issue, this paper couples the Euler−Euler model and population balance equation (PBE) model, correlates the PX crystallization kinetics, and accurately solves the PBE using the Gaussian integral hypothesis and product difference algorithm, which innovatively and directly simulates the PX suspension crystallization process and yields its multiphysical field characteristics. A multiobjective genetic algorithm is then used to study and optimize the crystallization mechanism and variation patterns, and the PX crystallization amplification law is derived. The results can be concluded as follows.There is a complete internal circulation flow in the crystallizer, and the fluid near the stirring paddle, at the entrance, and at the bottom has the strongest molecular kinetic energy and mixing degree. The crystal concentration and size increase exponentially before 750 s of crystallization, after which the growth trend decreases and gradually reaches dynamic equilibrium. The inlet velocity and stirring speed are inversely connected with the average particle size and particle size distribution interval, while supersaturation is positively correlated with both. The supersaturation has the most obvious effect on the crystal size distribution (CSD) curve. In comparison to the original settings, the optimized operating parameters raise the average particle size of PX by 6.68% and decrease the distribution interval by 38.21%. At last, the sedimentation velocity can be employed as an amplification factor to simplify the amplification process. This paper might serve as a theoretical reference for PX crystallization research and process optimization.

Exploration of Multishafts Stirred Reactors: An Investigation on Experiments and Large Eddy Simulations for Turbulent Chaos and Mixing Characteristics

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Particulate Fouling Analysis and Optimization of Heat Transfer Tubes Inserted with a Self-Rotating Rotor Coupled with RSM and MOGA

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Computational fluid dynamics simulation of a jet crystallizer for continuous crystallization of lovastatin

“…The simulation models typically consist of computational fluid dynamics (CFD) coupled with population balance equations (PBEs) in order to properly capture crystal size distribution (see e.g. 17 , 18 for recent examples of CFD-PBE crystallization modeling). Here, those studies focusing on anti-solvent crystallization, preferably of lovastatin and in jet crystallizers, are considered.…”