Hydro dynamic Flow Characteristics in an Internally Circulating Fluidized Bed Gasifier

摘要

In this paper, the hydrodynamic flow inside an internally circulating fluidized bed (ICFBG) was characterized using experimental and three-dimensional computational fluid dynamics (CFD) models. Eulerian-Eulerian model (EEM) incorporating the kinetic theory of granular flow was implemented in order to simulate the gas-solid flow. A full-scale plexiglass cold flow experimental model was built to verify simulation results prior to the fabrication of the gasifier. Six parameters were manipulated to achieve the optimum design geometry: fluidization flow rate of the draft tube (Q(dt)), aeration flow rate of the annulus (Q(an)), initial bed static height (H-bs), draft tube height (H-dt), draft tube diameter (D-dt), and orifice diameter (D-or). The investigated parameters showed strong effect on the particle flow characteristics in terms of the pressure difference (Delta p) and solid circulation rate (G(s)). The predicted results by simulation for the optimum case were in close agreement with experimental measurements with about 5% deviation. The results show that the ICFBG operated stably with the maximum G(s) value of 86.6 kg/h at Q(dt) of 350 LPM, Q(an) of 150 LPM, H-bs of 280 mm, H-dt of 320 mm, Ddt of 100 mm, and D-or of 20 mm.