Experiment and simulation of the pneumatic classification and drying of coking coal in a fluidized bed dryer

Abstract

Coking coal pneumatic classification and drying behavior within a three-stage cross-flow fluidized bed dryer were investigated experimentally and numerically. Firstly, the influence of fluidization velocities on coal classification and drying was analyzed with a pilot-scale fluidized bed dryer. It was found that the coal was dried fast and the moisture content of the product particles was below 2%, and the optimum classification efficiency was 92 wt% at a fluidization velocity of 2.2 m/s. Then the fluid dynamics property inside the dryer was calculated with a computational particle fluid dynamics modeling approach, simultaneously the optimization of the classification parameters and dryer configuration was studied. The classification efficiency can be increased by increasing the fluidization velocity in the 3rd stage chamber connected to the overflow outlet or a decrease in the overflow outlet height. However, the latter was not as sensitive as the fluidization velocity in the 3rd stage chamber.