Large eddy simulations of mixing effects on the course of precipitation process

Precipitation of sparingly soluble materials is a fast process, so the way in which reagents are mixed usually affects the particle size distribution (PSD) of precipitated particles. The large eddy simulation (LES) method is used in this work to simulate effects of flow and mixing on precipitation. The LES method is validated in the first part of this work by comparing model predictions with experimental data for fast parallel chemical test reactions carried out in the rectangular channel reactor. Predictions of the non-equilibrium multiple-time-scale mixing model combined with a standard k-epsilon model and conditional moment closure are also included in the comparison. Also the velocity and scalar concentration distributions are compared with PIV and PLIF experimental data to validate the model. Precipitation model is tested in this part by comparing predictions of the model based on LES with results obtained using the multiple time-scale mixing model combined with the k-epsilon model. In the second part of this work precipitation of BaSO4 from aqueous solutions of BaCl2 and Na2SO4 carried out at T=298.2 K in a 2-meter long tubular reactor equipped with the impingement T-shaped mixing head is considered. Predictions of both methods of modeling are compared with experimental data. (C) 2011 Elsevier Ltd. All rights reserved.