Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

Tsotsas, Evangelos

doi:10.1002/1522-2640(200004)72:4<313::aid-cite313>3.0.co;2-2

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…The fixed-bed porosity in the vicinity of walls is higher than the porosity at the reactor axis. The higher local porosities in the vicinity of walls are approximated by the empirical equation for fixed-beds consisting of cylinders . The porosity of the fixed-bed without wall effects was assumed to be ψ ∞ = 0.4 in the present work.…”

Section: Simulation Modelmentioning

confidence: 99%

“…The momentum balance is based on the extended Brinkmann equation which considers porosity profiles: The effective viscosity η eff accounts for the wall friction. The relation of the effective viscosity to the gas-phase viscosity that is valid for a bed of cylinders (eq 4) was given in ref . The functions f 1 and f 2 account for laminar and turbulent friction in the bed, respectively.…”

Section: Simulation Modelmentioning

confidence: 99%

“…Reference 7 presents an evaluation of the state of the art simulation models in german. The chosen model is described in ref , which, again, is in german. The model is, separated into several aspects, reported in english in refs −10.…”

Section: Introductionmentioning

confidence: 99%

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Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

Brandstädter¹,

Kraushaar‐Czarnetzki²

2007

Ind. Eng. Chem. Res.

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The partial selective oxidation of mixtures of n-butenes and n-butane in an industrial-scale fixed-bed reactor has been simulated to find suitable operation conditions and to give a rough estimate of the performance of such a reactor. A two-dimensional homogeneous reactor model has been used in combination with a kinetic model based on experimental results. Since the pressure drop along the reactor tubes was assumed to be 1−1.5 bar, the gas phase in the reactor tubes had to be treated as a compressible fluid. The operation conditions of the reactor were found by repeated simulation and continuous improvement. The simulations resulted in a conversion level of 90% and a yield of maleic anhydride of 48% for a synthetic raffinate II mixture containing only n-butenes and n-butane. A typical real raffinate II mixture which also contains isobutane would result in a yield of maleic anhydride of ≈42%. Production capacities of 17 100 and 22 5000 t/y where achieved with allowed pressure drops of 1.0 and 1.5 bar, respectively.

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Section: Simulation Modelmentioning

confidence: 99%

Section: Simulation Modelmentioning

confidence: 99%

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Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

Brandstädter¹,

Kraushaar‐Czarnetzki²

2007

Ind. Eng. Chem. Res.

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“…The rate of dispersion in the gas phase is considered to be linearly dependent on the concentration gradient, and the dispersion coefficient depends on the flow regime . The phenomenon of dispersion in fixed beds with very low fluid velocities consists of diffusion, which is predominant in the filter cake, and back-mixing due to microscopic Taylor dispersion, which is of no importance. The dispersion coefficient of SO 2 depends, in particular, on the superficial gas velocity, the porosity of the fixed bed, the particle size of the powder making up the fixed bed, and the diffusion coefficient of SO 2 .…”

Section: Mass Balance Equations and Parametersmentioning

confidence: 99%

SO₂ Removal in the Filter Cake of a Jet-Pulsed Filter: A Combined Filter and Fixed-Bed Reaction Model

Kavouras

Breitschaedel

Krammer

et al. 2002

Ind. Eng. Chem. Res.

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Jet-pulsed filters are frequently used to separate fine solid particles from gas streams. An example for the application of the filter as both a solid separator and a fixed-bed reactor is a dry flue gas cleaning process, where the dry solid sorbent Ca(OH)2 forms a filter cake that captures a major part of the SO2 and HCl out of the flue gas. One important phenomenon concerning the formation of the filter cake on jet-pulsed filters is imperfect cake removal. Here a jet pulse tears off the entire filter cake from only a fraction of the exposed filter area, and only part of the total filter area is subjected to the jet-pulse cleaning. This property of jet-pulsed filters has a great influence on the chemical reaction simulation between gas and solid in the filter cake because the gas velocity through the cake, the cake thickness, and the residence time distribution of the solid forming the cake differ widely over the entire filter area. A recently developed filter model, in which different classes of cake thicknesses are understood to result from different cake generations, is used to determine the distributions of cake thickness, gas velocity, and residence time of the solid over the filter area. With the combination of the filter model and a fixed-bed reaction model using an empirical kinetic equation, the SO2 removal in the fixed bed of the filter cake can be simulated. The combined filter and reaction model was successfully validated with an experiment from a pilot plant for dry flue gas cleaning, where solid Ca(OH)2 was used as a sorbent. A sample of the partially reacted sorbent from the pilot plant had been used to derive the empirical kinetic equation for SO2 sorption in fixed-bed laboratory experiments.

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“…In general, it can be said that the pseudohomogeneous model gives good results in the absence of strong source terms within the heat balance, e.g. reaction or adsorption enthalpies [6]. However, modeling of a chromatographic reactor is not the goal of this work and the heat of adsorption has only minor effects in liquid chromatography.…”

Section: Model Equationsmentioning

confidence: 99%

Heat Transfer and Hydrodynamics in Preparative Continuous Annular Chromatography (P-CAC)

Brozio

Bart²

2000

Chem. Eng. Technol.

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Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

Cited by 9 publications

References 1 publication

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

SO₂ Removal in the Filter Cake of a Jet-Pulsed Filter: A Combined Filter and Fixed-Bed Reaction Model

Heat Transfer and Hydrodynamics in Preparative Continuous Annular Chromatography (P-CAC)

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Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

Cited by 9 publications

References 1 publication

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

SO2 Removal in the Filter Cake of a Jet-Pulsed Filter: A Combined Filter and Fixed-Bed Reaction Model

Heat Transfer and Hydrodynamics in Preparative Continuous Annular Chromatography (P-CAC)

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Product

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SO₂ Removal in the Filter Cake of a Jet-Pulsed Filter: A Combined Filter and Fixed-Bed Reaction Model