Sensitivity of Gas-Solids Dispersion and Mass Transfer Coefficient in an Eulerian-Eulerian CFD Model

摘要

Eulerian-Eulerian CFD models have become widely accepted in the modeling of dense gas-solids systems. These models have been used to predicted bubble dynamics in fluidized beds and clustering and core annular structure in circulating fluidized beds. However, coupling the hydrodynamics predicted by these models with chemical reactions is relatively new application. In a recent review paper by Breault 2004 gas-solids dispersion coefficient reported in the literature differ by 5 orders of magnitude and mass transfer coefficients differ by 7 orders of magnitude. Given such variability in these coefficients this paper investigates the sensitivity of these values in the Eulerian-Eulerian model MFIX (Multiphase Flow with Interphase exchanges; www.mfix.org). Two dimensional simulations based on a circulating fluidized bed (CFB) in operation at the National Energy Technology Laboratory (NETL) were conducted. The simulations were conducted in the core-annular regime with carbon combustion as the single chemical reaction. The sensitivity in the predicted carbon conversion as a function of gas-solids dispersion and mass transfer coefficient is reported.