Modeling and simulation of circulating fluidized bed reactor with catalytic ozone decomposition reaction

Abstract

Hydrodynamic modeling of catalytic ozone decomposition reaction in circulating fluidized bed (CFB) reactors was studied based on the experimental work of Schoenfelder et al. [AIChE J. 42 (1996) 1875] by using Reactive Flow Analysis Program (RFAP). The aims of this research were to study the effect of solid viscosity on hydrodynamic behavior of gas and solid and to improve the performance of ozone CFB reactors by studying the effect of operating parameters of the system on ozone conversion. The effect of solid viscosity on flow structure was investigated by using two different models of solid viscosity, the constant solid viscosity coefficient model, and the kinetic theory model, incorporated in RFAP. The solid viscosity calculated from different models had a significant effect on gas–solid flow pattern. The solid volume fraction profile calculated from the kinetic theory model with restitutive coefficient of 0.9999 matched the experimental value better than the constant solid viscosity coefficient model. However, the solid volume fraction at the bottommost of the riser predicted by this model was lower than the experimental value. Without the experimental data of solid volume fraction, this model can reasonably predict the outlet ozone conversion at different superficial gas velocities. To improve the performance of ozone CFB reactors, the operating parameters, particle density, gas distributor design, and reactor configuration were adjusted in the RFAP. The results showed that increasing catalyst density (from 1.42 to 2 g/cm 3) increased the reaction conversion by about 8%. The non-uniform gas distributor design provided 8–10% ozone conversion more than the uniform gas distributor design. In addition, the new CFB reactor configuration (with baffles) can enhance the radial gas–solid mixing, thereby increasing approximately 5–12% of ozone conversion.