title: Multi-scale CFD simulation of hydrodynamics and cracking reactions in fixed fluidized bed reactors.
abstract: Fixed fluidized bed reactor is widely used to evaluate the crackability of heavy oils and the activity of catalysts. To understand the hydrodynamics, reaction kinetics and thermodynamics in conventional and modified fixed fluidized bed reactors, the computational fluid dynamics method, energy-minimization multi-scale-based two-fluid model coupled with a six-lump kinetic model was used to investigate the gas-solid flow and cracking reactions. The gas mixing and particle volume fraction distributions, as well as product yields in the conventional and modified fixed fluidized bed reactors were analyzed. The residence time distribution model was utilized to obtain the parameters indicating the back-mixing degree, such as mean residence time and dimensionless variance of the gas. The results showed that the simulated product distribution is in reasonable agreement with the experimental data; the modified fixed fluidized bed reactor is closer to the ideal plug flow reactor, which can efficiently enhance the gas-solid mixing, reduce the gas back-mixing degree, and hence improve the reaction performance.
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Jin H
authors.initials: JH
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Zhen B
authors.initials: ZB
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Yuan Y
authors.initials: YY
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Hong H
authors.initials: HH
authors.lastname: Shan
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
authors.forename: Chao H
authors.initials: CH
authors.lastname: Yang
keywords: Catalytic cracking; Fixed fluidized bed reactor; Multi-scale structure; Reaction kinetics; Simulation