The CFD Applied Basic Research Of Two Typical Polydisperse Gas-solid Fluidized Bed Reactor

Fluidized bed reactor(FBR) is widely used in various chemical production processes due to its simple construction and excellent transfer capabilities. The precise understand of the dynamics behavior is very important to the efficient operation and optimization of FBR. In recent years, as the rapid development of computer’s performance, computational fluid dynamics(CFD) gradually become an important tool which can efficiently predict the multi-phase flow behavior in FBR. Unfortunately, the diameter of solid phase is assumed to mono-disperse in many previous CFD simulations. However, in reality, there always exists a diameter distribution in many processes, such as olefin polymerization and fluidized catalytic cracking(FCC). Therefore, population balance method(PBM) is always introduced to describe the solid phase size distribution.In this paper, following three aspects were investigated using numerical simulation on the platform of commercial CFD software named FLUENT 6.3.26 to further improve the CFD-PBM coupled model in two typical polydisperse gas-solid systems(olefin polymerization FBR and fluid catalytic cracking riser reactor).(1) Compared the suitability of four different drag models: Syamlal-O’Brien drag model, Gidaspow drag model, McKeen drag model and EMMS drag model in CFD-PBM coupled model in olefin polymerization FBR. The results showed that EMMS model was the most suitable drag model in this system.(2) Compared the suitability of three different methods of moments: quadrature moments of method(QMOM), direct quadrature moments of method(DQMOM) and fixed pivot quadrature moments of method(FPQMOM) that used to solve the population balance equation in CFD-PBM coupled model in olefin polymerization. The results showed that using FPQMOM can predict the most real simulated results and can improve the computational efficiency.(3) Extended the comparison of the suitability of QMOM, DQMOM and FPQMOM to the CFD-PBM coupled model in FCC riser reactor. The results showed that using QMOM can obtain the most real simulated results in this system.