C-CFD-FluidizedBedRaoster.pdf

Continuous fluidized bed roasters are being widely used in industries for oxidation of sulphide ores. In the present study we consider a roaster of height 24.5m, freeboard diameter of 16.85m and bed diameter of 12.5m. The distributor contains 12300 nozzles of diameter 6mm. It has two material inlets for the zinc concentrate, one gas outlet for the top product and one outlet for the bottom product. The air is blown from the bottom through four inlets for distribution across the distributor. Cooling of the bed is done by ten cooling coils inserted in the bed and water injected on the top of the bed. The feed contains around 60% particles of size ��� 57 micron. The initial bed height is 0.8m. In this study a 3D multiphase Eulerian-Eulerian computational fluid dynamics model has been used to study the flow profile of the particles of different sizes individually (two-phase flow) as well as together (five phases). Due to the complexity of the geometry, the roaster was divided into several zones to reduce the number of cells and the computational time. Single phase simulations were carried out with 2.4 million, 3.2 million as well as 4.3 million cells and it was found that for preliminary studies a computational domain consisting of 2.4 million cells would suffice. Simulations were carried out on a HPC with 32 nodes. It was seen that there was considerable difference in the flow profiles in the case of two-phase and five-phase flow for finer particles due to resistance offered by larger size particles on the flow of finer particles.