(482a) Heterogeneity Analysis of the Dry FGD Process At Medium Temperature In CFB Reactor Based On Eulerian Simulation

The flow field structure and the desulfurization reaction of the dry FGD process in CFB reactor was studied by numerical method with Eulerian two-fluid model. By using the Syamlal & O’Brien drag force model with particle clustering effect correction and the improved sulfur capture model for the T-T sorbent, the relative errors of the computed bed inventory and desulfurization efficiency are lower than 5% and 6% respectively in comparison with experimental data. The simulated results show that from the bottom to the top of the bed, the flow field changes from dense region to transition region and then to dilute region; the PDDs of particle volume fraction, gas and particle-phase velocities changes from monotonous single-peak distribution to heterogeneous two-peak distribution and finally recover monotonous single-peak distribution corresponding to the axial distribution of heterogeneity of cross-sectional particle volume fraction distribution. Analysis of the heterogeneity of the particle volume fraction implies that the heterogeneity reaches maximum at the transition region while the sub-peak appears near the outlet under the hat chamber structure. The heterogeneity of SO2 concentration distribution increases with the increasing of the product of the particle volume fraction and the heterogeneity of its distribution. Finally, it was found that The heterogeneous axial distribution of sorbent particles shortens the effective sulfating reaction time thus the Calcium utility efficiency and with a certain particle volume fraction, the sulfating reaction rate as well as the desulfurization efficiency increase as the heterogeneity of the particle volume fraction distribution decreases. This work ascertains the optimization method for improving the Calcium utilization efficiency and desulfurization efficiency apparently that is to improve the uniformity of the distribution of sorbent particles.