Process validation of propane dehydrogenation in a CFB reactor with heat supply and catalyst regeneration: CFD simulation coupled with reaction kinetics

Abstract

Although fixed-bed and moving-bed technologies for propane dehydrogenation have been commercialized in large scales, the process efficiency is still low due to the highly endothermic nature of the reaction and quick catalyst deactivation. Herein, the superiority of the circulating fluidized bed reactor in mitigating these issues is validated, in which the continuous dehydrogenation-regeneration process for propane dehydrogenation is numerically studied with integrated heat supply by using circulating catalyst particles as heat carriers and catalyst regeneration to remove deposited coke. The physical model of the riser with considering the heat supply and catalyst regeneration is developed to simplify the full-loop reactor. Additionally, the two-fluid model, incorporating a sub-grid drag model and detailed reaction kinetics, is adopted to simulate the propane dehydrogenation process in the circulating fluidized bed reactor, and key operating parameters are optimized. Results indicate the reactor with integrated heat supply and catalyst regeneration can be operated steadily under a wide range of operating conditions. Specifically, higher catalyst inventory, circulating particle temperature, and regeneration extent all positively contribute to the propylene yield, while the optimal inlet gas flow rate for maximizing propylene yield is found to range between 20 and 25 Nm³·h⁻¹. These findings promote the understanding of the propane dehydrogenation processes in circulating fluidized bed reactors.