Computational Fluid Dynamics of a Gas-Solid Fluidized Bed at High Pressure.

摘要

Computational fluid dynamics was used to study the effect of pressure on the hydrodynamic behaviour of a gas solid fluidized bed comprising Polyehtylene particles. Time average properties and dynamic characteristics on the fluidized bed were predicted by means of the Eulerian-Eulerian multiphase model in the computational fluid dynamic software FLUENT v 6.3.;Analysis of pressure fluctuations showed that the fluidized bed was operating in the multiple bubble regime. This agrees well with visual observations. However it was not possible to establish a hydrodynamic similitude between the CFD model predictions and experimental results reported by Orta (2010).;Further investigation is necessary to validate CFD models for non-ideal particles under a wide range of operating conditions.;The effect of pressure on the bed expansion, dense phase voidage, bubble size and bubble velocity predicted by the CFD model agreed well with the literature for different particles (e.g. sand, coal, FCC powder). The results showed that as the gas pressure increases the bed expansion and dense phase voidage increases, the bubble size and bubble velocity decreases. The bubble properties predicted by the CFD model at ambient pressure agreed well with Orta (2010) experimental results. However opposite trends were observed in the CFD model predictions and experimental results reported by Orta (2010) as the pressure was increased.