Powder Technology, Vol.350, 81-90, 2019
Determination of minimum fluidization velocity in fluidized bed at elevated pressures and temperatures using CFD simulations
The minimum fluidization velocity of particles is one of the most critical parameters for the design and operation of fluidized beds. It is difficult and expensive to experimentally measure this parameter at elevated pressures and temperatures. In this study, a three-dimensional model based on Eulerian-Lagrangian frames was used to predict the minimum fluidization velocity at elevated pressures and temperatures. The solid phase was simulated using the multi-phase particle-in-cell approach. The particle flow was described using the discrete particle approach, and a large eddy simulation was conducted to predict the turbulent gas motion. The simulation results were compared with the experimental data reported in previous literatures. The bed temperature ranged from 25 to 800 degrees C, and the operating pressure ranged from 0.1-4 MPa. In general, the minimum fluidization velocity decreased as the temperature and pressure increased. The variation trends were not significant at high temperatures and pressures (greater than 600 degrees C and 2 MP, respectively). With a decrease in the particle density, the minimum fluidization velocity decreased. With an increase in the particle size, the minimum fluidization velocity increased. Moreover, the influence of the particle size distribution on the minimum fluidization velocity was systematically evaluated. To precisely calculate the minimum fluidization velocity at elevated temperatures and pressures, a correlation was proposed based on the simulation results. (C) 2019 Elsevier B.V. All rights reserved.