Analytical and numerical considerations of the minimum fluidization velocity of the molybdenite particles

In this study, the hydrodynamic simulation of molybdenite powder fluidized bed has been carried out analytically and numerically. The ultimate goal of this research was to design a fluidized bed dryer and roaster for molybdenite powder of Khaton-Abad Molybdenite Factory. The Euler-Euler approach was used to model a fluidized bed to predict the minimum fluidization velocity and behavior of solids in the molybdenite fluidized bed roaster by using the CFD package ANSYS FLUENT. The minimum fluidization velocity, which is one of the most critical parameters for the design and operation of fluidized beds, was obtained analytically and numerically. Numerical result shows that the minimum fluidization velocity for spherical molybdenite particles of 0.0001 m in size and density of 4600 kg/m3 is 2 cm/s at a temperature of 300 K. The computational geometry of a 2D fluidized bed had a height of 0.5 m and a width of 0.05 m. Analytical results show that the minimum fluidization velocity at 870 K is about half of the minimum fluidization velocity at 300 K. A correlation has been derived from the Ergun equation and the hypothesis of Wen and Yu for predicting the minimum fluidization velocity of irregular and spherical particles at low particle Reynolds numbers. The computational results and the prediction with the derived correlation were in good agreement with the experimental data for various types and diameters of particles.