CFD Simulation of Solid Suspension in a Stirred Tank.

Abstract

Particle concentration distribution in seven phases in stirred tank is simulated on the basis of information in three dimensional flow field, as obtained by numerical solution of the flow equations (CFD), using the well known κ-ε model. A model for simulation of multi-phase flow field was developed based on the commercial CFD program of CFX4.2. The volume fraction distribution of different sizes of particle was studied by the simulation results. Local particle size distributions in suspension are studied as a function of agitation intensity and distance from the bottom of the tank by the use of CFD. For this purpose a multiple phase approach was used. There, the different particle size classes are taken as separate computational phases. Six classes of particle sizes were used in the simulation. The continuous phase was water. The six solid phases were composed of particle sizes of 50, 100, 300, 500, 700 and 900 μm. The particle density was 2600 kg/m3, different stirrer speeds were used with multiple phase flow. Further, expressions were developed and added in the program which enable the local particle size distributions to be calculated. Computed suspension densities were verified with existing experimental data in the literature.