A STUDY ON THE SWIRLING FLOW-FIELD IN THE FREEBOARD OF A VORTEXING FLUIDIZED-BED COMBUSTOR

A computational fluid dynamics model, based on K-E turbulence model fo r the closure of steady turbulent flow, was used for the evaluation of the swirling flow field. Also a vortexing fluidized bed combustor (VF BC) cold model testing facility was designed, fabricated, and tested. Computations and experimental data permitted the investigation of the effects of various operating parameters on the gas flow profiles and v ortex numbers. The results show that a stable suspension layer in the freeboard was produced by the swirling gas motion. The vortex number i s found to increase with the secondary air velocity, increase with the diameter of the imaginary circle, and decrease with the ratio of volu metric flow rates of the primary air to the secondary air. In this pap er, a correlation for evaluating the vortex number was proposed which was shown to be one of the most useful parameters in the design of a V FBC.