Comprehensive Modeling of Gas Fluidized-Bed Reactors Allowing for Transients, Multiple Flow Regimes and Selective Removal of Species

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Andres Mahecha-Botero ◽  
John Grace ◽  
Said S.E.H. Elnashaie ◽  
C. Jim Lim
Keyword(s):  
Fluidized Bed ◽  
Catalyst Deactivation ◽  
Flow Regimes ◽  
Fluidized Bed Reactors ◽  
Ethylene Dichloride ◽  
Catalytic Reactors ◽  
Catalytic Systems ◽  
Pressure Profiles ◽  
Special Cases ◽  
Reactor Models

A multiphase reaction engineering model is being developed to investigate the dynamic and steady state behaviour of fluidized-bed catalytic reactors. It accounts for transients, axial and radial dispersion, temperature and pressure profiles, interphase mass and heat transfer, different hydrodynamic flow regimes, catalyst deactivation, reactions with changes in molar flows and various energy options. The model is general enough that it can treat catalytic systems, subject to mass and energy transfer resistances within the phases, as well as permeating membranes. It is able to handle multiple phases and regions (low-density phase, high-density phase, freeboard region and permselective membranes). The model reduces as special cases to a number of simpler fluidized bed reactor models previously reported in the literature, allowing evaluation of the influence of different simplifying assumptions. As a case study, the model is shown to simulate oxy-chlorination fluidized-bed reactors for the production of ethylene dichloride from ethylene, extending a recent paper by Abba et al. (Chem. Eng. Sci., (2002) 57, 4797-4807).

Catalyst deactivation by coking in the MTG process in fixed and fluidized bed reactors

1997 ◽  
Vol 37 (3) ◽  
pp. 239-248 ◽  
Author(s):  
Andrés T. Aguayo ◽  
Ana G. Gayubo ◽  
JoséM. Ortega ◽  
Martin Olazar ◽  
Javier Bilbao
Keyword(s):  
Fluidized Bed ◽  
Catalyst Deactivation ◽  
Fluidized Bed Reactors

Comparison of CFD Simulation and Simplified Modeling of a Fluidized Bed CO2 Capture Reactor

2016 ◽  
Vol 14 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Daoyin Liu ◽  
Zhonglin Zhang ◽  
Yaming Zhuang ◽  
Xiaoping Chen
Keyword(s):  
Fluidized Bed ◽  
Flow Model ◽  
Cfd Simulation ◽  
Plug Flow ◽  
Fluidized Bed Reactors ◽  
Cfd Model ◽  
Two Phase ◽  
Multiphase Cfd ◽  
Reactor Models ◽  
Dem Model

AbstractCO2 capture using solid sorbents in fluidized bed reactors is a promising technology. The multiphase CFD model is increasingly developed to study the reactors, but it is difficult to model all the realistic details and it requires significant computational time. In this study, both the multiphase CFD model (i.e., CFD-DEM model coupled with reaction) and the simplified reactor models (i.e., plug flow model and bubbling two-phase model) are developed for modeling a fluidized bed CO2 capture reactor. The comparisons are made at different gas velocities from fixed bed to fluidized bed. The DEM based model reveals a detailed view of CO2 adsorption process with particle flow dynamics, based on which the assumptions in the simplified models can be evaluated. The plug flow model predictions generally show similar trends to the DEM model but there are quantitative differences; thus, it can be used to determine the reactor performance limit. The bubbling two-phase model gives better predictions than the plug flow model because the effect of bubbles on the inter-phase mass transfer and reaction is included. In the future, a closer combination of the multiphase CFD simulation and the simplified reactor models will likely be an efficient design method of CO2 capture fluidized bed reactors.

scholarly journals Modeling of metallocene catalyzed propylene polymerization in fluidized bed reactors

2019 ◽  
Vol 268 ◽  
pp. 02002
Author(s):  
Chew-Sang Law ◽  
Mohd Azlan Hussain
Keyword(s):  
Fluidized Bed ◽  
Mixed Model ◽  
Monomer Concentration ◽  
Fluidized Bed Reactor ◽  
Propylene Polymerization ◽  
Fluidized Bed Reactors ◽  
Multi Scale ◽  
Reactor Temperature ◽  
Mixed Reactor ◽  
Reactor Models

A study was performed to improve the model for metallocene catalyzed polyolefin polymerization in fluidized bed reactor by adapting multi-scale modeling approach. Monomer concentration and reactor temperature was predicted using kinetic model of polypropylene homopolymerization coupled with well mixed reactor models of fluidized bed reactor. Well mixed model typically used for Ziegler-Nata was selected as supported homogeneous metallocene exhibited heterogeneous property similar to ZN catalyst. Result of simulation showed that model was able to predict reaction temperature accurate with around 3% over-prediction of reactor temperature, which is more accurate than previous model. Model predicted decrease in final monomer concentration from 0.9929 mol/s to 0.986 mol/s when initial reactor was raised from 25C to 75C.

Computational analysis of the particle size effect on the pressure profiles and type of flow regimes of TiO2 microparticles in a fluidized bed

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alireza Bahramian
Keyword(s):  
Particle Size ◽  
Flow Regime ◽  
Fluidized Bed ◽  
Fluid Dynamic ◽  
Pressure Fluctuations ◽  
Flow Regimes ◽  
Particle Size Effect ◽  
Pressure Profiles ◽  
Effect Of Particle Size ◽  
Drag Models

Abstract The effect of particle size on the pressure profiles and flow regimes of the bed containing TiO2 microparticles (MPs) was investigated in a fluidized bed. The fluidization behavior of particles with mean diameters, d p , of 170, 200, 225, and 300 μm at different gas velocities, U g , was investigated both experimental and computational viewpoints. A computational fluid dynamic (CFD) model was developed by the Eulerian–Eulerian approach to evaluate the sensitivity of the Syamlal–O’Brien, and Gidaspow drag models on the predicted results of the bed pressure profiles. The results showed that with increasing particle size, the amplitude of pressure fluctuations increases and the type of flow regime in the bed tended from bubbling to slugging flow regime. The error analysis showed that the use of the Gidaspow model led to more accurate results than the Syamlal–O’Brien model in predicting the bed pressure drop and pressure fluctuations in the slugging flow regime. However, the Syamlal–O’Brien model was more suitable for predicting the pressure profiles in the bubbling flow regime. The results were more suitable for the bed containing particles of 300 μm than the beds with d p  ≤ 225 μm. The highest and lowest deviations between the experimental data and simulation outputs were obtained at U g of 0.295 and 0.650 m/s, respectively. The findings confirmed that the mutual effects existed between the d p pressure profiles, and the type of flow regimes in the bed.

Influence of Seeding Conditions on Initial Biofilm Development during the Startup of Anaerobic Fluidized Bed Reactors

1989 ◽  
Vol 21 (4-5) ◽  
pp. 157-165 ◽  
Author(s):  
F. Ehlinger ◽  
J. M. Audic ◽  
G. M. Faup
Keyword(s):  
Fluidized Bed ◽  
Future Development ◽  
Protein Concentration ◽  
Specific Activity ◽  
Fluidized Bed Reactor ◽  
Fluidized Bed Reactors ◽  
Support Material ◽  
Biofilm Development ◽  
Initial Biofilm

The characterization of the biofilm of an anaerobic fluidized-bed reactor was completed under standard conditions. The distribution of the fixed protein concentration depended on the level in the reactor. The protein concentration reached 1520 µg.g−1 of support at the top of the reactor and only 1200 µg.g−1 at the bottom after 504 hours of operation but the specific activity of the biofilm was 33×10−4 µM acetate.h−1.mg−1 proteins at the bottom and only 26×10−4 µM.h−1.mg−1 at the top. The efficiency of a fluidized bed reactor and the composition of the biofilm changed with an increase of the pH from 7 to 8.5 during the seeding of the support material. Future development of the biofilm and the specific activity of the support were affected.

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