Packed-Bed Reactor Performance Enhancement by Membrane Distributed Feed: The Case of Methanol Oxidative Dehydrogenation

2002 ◽  
Vol 752 ◽  
Author(s):  
Victor Diakov ◽  
Arvind Varma
Keyword(s):  
Oxidative Dehydrogenation ◽  
Membrane Reactor ◽  
Performance Enhancement ◽  
Fixed Bed ◽  
Packed Bed ◽  
Operating Conditions ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Reactor Performance ◽  
Wide Range

ABSTRACTFor methanol oxidative dehydrogenation to formaldehyde, the performance of the packed-bed membrane reactor (PBMR) is compared with that of the conventional fixed-bed reactor (FBR) over a wide range of operating conditions. The reaction was studied in three reactor configurations: the conventional FBR and the packed-bed membrane reactor, with either methanol (PBMR-M) or oxygen (PBMR-O) as the permeating component. The kinetics of methanol and formaldehyde partial oxidation reactions were determined and incorporated in a PBMR model. Both experimental data and model considerations demonstrate that the PBMR enhances reactant conversion and selectivity.Small oscillations in CO production were observed experimentally. Their amplitude was taken as a basis for comparison of packed-bed operation instability. The likely source of oscillatory behavior is the non-uniformity in reaction conditions along the reactor. It was found that membrane distributed feed, by providing a more uniform reactor operation, is an effective remedy from these instabilities.It is found, both by simulations and experimental observations, that relative reactor performance depends strongly on the operating conditions. Using formaldehyde yield as the basis for optimization, optimal reactor performances are determined to be in the order: PBMR-O > FBR > PBMR-M. Further PBMR productivity enhancement is possible by optimizing the membrane feed distribution pattern.

A New Reactor Concept for Efficient Solar-Thermochemical Fuel Production

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Ivan Ermanoski ◽  
Nathan P. Siegel ◽  
Ellen B. Stechel
Keyword(s):  
Solar Energy ◽  
High Efficiency ◽  
Packed Bed ◽  
Operating Conditions ◽  
Packed Bed Reactor ◽  
Reactive Material ◽  
Starting Point ◽  
Wide Range ◽  
Solar Thermochemical ◽  
The U.S

We describe and analyze the efficiency of a new solar-thermochemical reactor concept, which employs a moving packed bed of reactive particles produce of H2 or CO from solar energy and H2O or CO2. The packed bed reactor incorporates several features essential to achieving high efficiency: spatial separation of pressures, temperature, and reaction products in the reactor; solid–solid sensible heat recovery between reaction steps; continuous on-sun operation; and direct solar illumination of the working material. Our efficiency analysis includes material thermodynamics and a detailed accounting of energy losses, and demonstrates that vacuum pumping, made possible by the innovative pressure separation approach in our reactor, has a decisive efficiency advantage over inert gas sweeping. We show that in a fully developed system, using CeO2 as a reactive material, the conversion efficiency of solar energy into H2 and CO at the design point can exceed 30%. The reactor operational flexibility makes it suitable for a wide range of operating conditions, allowing for high efficiency on an annual average basis. The mixture of H2 and CO, known as synthesis gas, is not only usable as a fuel but is also a universal starting point for the production of synthetic fuels compatible with the existing energy infrastructure. This would make it possible to replace petroleum derivatives used in transportation in the U.S., by using less than 0.7% of the U.S. land area, a roughly two orders of magnitude improvement over mature biofuel approaches. In addition, the packed bed reactor design is flexible and can be adapted to new, better performing reactive materials.

Steady State Model for Heat Transfer in a Packed Bed Reactor of Elliptic Cylindrical Shape

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Laércio G. Oliveira ◽  
Ramdayal Swarnakar ◽  
Antonio G. B. de Lima
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Fixed Bed ◽  
Packed Bed ◽  
Numerical Results ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Dimensionless Temperature ◽  
Cylindrical Shape ◽  
Temperature Profiles

The fixed-bed reactors of circular cylindrical geometry with heated or cooled walls are frequently used to carry out heterogeneous reactions of solid-gas type in engineering applications. The design of a fixed bed reactor requires an extensive knowledge of heat transfer characteristics within the packed bed. In this sense, this work presents a three-dimensional mathematical model to predict the heat transfer inside a fixed bed elliptical cylinder heat exchanger. The model considers uniform velocity and temperature profiles of the fluid phase at the entrance of the reactor, and constant thermo-physical properties. The surface of the equipment convective boundary condition is assumed to be constant. The energy equation, written in the elliptical cylindrical coordinates, was discretized using a finite-volume method considering a fully implicit formulation, and WUDS interpolation scheme. Numerical results of the dimensionless temperature profiles inside the packed bed reactor at a steady state are presented and temperature distribution is interpreted. To validate the model, numerical results obtained for the circular cylinder are compared with analytical results from literature and a good agreement was obtained.

scholarly journals Encapsulated catalase from Serratia genus for H2O2 decomposition in food applications

2018 ◽  
Vol 20 (4) ◽  
pp. 39-43 ◽  
Author(s):  
Katarzyna Czyzewska ◽  
Anna Trusek
Keyword(s):  
High Activity ◽  
Fixed Bed ◽  
Industrial Applications ◽  
Fixed Bed Reactor ◽  
Reactor Performance ◽  
Operational Conditions ◽  
H2o2 Decomposition ◽  
Wide Range ◽  
Immobilized Catalase ◽  
Food Applications

Abstract The recombinant catalase isolated from a psychrotolerant microorganism belonging to Serratia genus exhibits a high activity in a wide range of pH. Due to a great catalytic potential in operational conditions, it can be used in various industrial applications whereby it acts as a hydrogen peroxide scavenger. To reduce the cost of biocatalyst the enzyme encapsulation into a hydrogel structure was proposed. The obtained results showed a high activity of encapsulated catalase in acidic conditions (pH in range 4.4 - 6.6) and at low temperatures (6-15°C). Moreover, immobilized catalase exhibited a high stability in natural media, especially in milk. Its activity during peroxide decomposition in milk, the possibility of re-using, as well as the fixed bed reactor performance confirmed wide application possibilities. High values of enzyme and substrate concentrations led to the beads burst due to rapid oxygen diffusion from the capsules, thus they are limited.

Modeling and Simulation of a Packed-bed Reactor for Carrying out the Water-Gas Shift Reaction

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Yaidelin A. Manrique ◽  
Carlos V. Miguel ◽  
Diogo Mendes ◽  
Adelio Mendes ◽  
Luis M. Madeira
Keyword(s):  
Fixed Bed ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Water Gas Shift ◽  
Small Scale ◽  
Heterogeneous Model ◽  
Co Conversion ◽  
Reactor Operating ◽  
Water Gas

Abstract In this work the water-gas shift (WGS) process was addressed, with particular emphasis in the development of phenomenological models that can reproduce experimental results in a WGS reactor operating at low temperatures. It was simulated the conversion obtained in a fixed-bed reactor (PBR) packed with a Cu-based catalyst making use of a composed kinetic equation in which the Langmuir-Hinshelwood rate model was used for the lowest temperature range (up to 215 ºC), while for temperatures in the range 215 – 300 ºC a redox model was employed. Several packed-bed reactor models were then proposed, all of them without any fitting parameters. After comparing the simulations against experimental CO conversion data for different temperatures and space time values, it was concluded that the heterogeneous model comprising axial dispersion and mass transfer resistances shows the best fitting. This model revealed also good adherence to other experiments employing different feed compositions (CO and H2O contents); it predicts also the overall trend of increasing CO conversion with the total pressure. This modeling work is particularly important for small scale applications related with hydrogen production/purification for fuel cells.

Catalytic wet peroxidation of phenol in a fixed bed reactor

2007 ◽  
Vol 55 (12) ◽  
pp. 75-81 ◽  
Author(s):  
F. Martínez ◽  
M.I. Pariente ◽  
J.A. Melero ◽  
J.A. Botas ◽  
E. Gómez
Keyword(s):  
Phenol Degradation ◽  
Fixed Bed ◽  
Methyl Cellulose ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Continuous Treatment ◽  
Catalyst Stability ◽  
Solid Catalyst ◽  
Relevant Role

Iron-containing mesostructured materials (Fe-SBA-15) are suitable for continuous treatment of phenolic aqueous solutions by means of catalytic wet peroxide oxidation (CWPO) in a packed-bed reactor. These materials were successfully extruded, crushed and sieved with a particle size ranging from 1 to 1.6 mm using mineral clay and methyl cellulose as binders. Non-significant changes have been found in the textural and structural properties of the extruded material in comparison to the parent powder Fe-SBA-15 material. Activity of extruded catalyst in terms of phenol degradation and TOC reduction has been monitored in a continuous mode. The increase of residence time enhances significantly the TOC degradation. The catalyst stability, taking into account the loss of iron species from the catalyst into the aqueous solution, has also been examined. The catalytic results of Fe-SBA-15 material in comparison to a homogeneous catalytic test prove the relevant role of the solid catalyst in the oxidation process.

Intrinsic Kinetics Study of CO Methanation on Ni-Mo-SiO2 Catalyst Prepared by Hydrothermal Method

2018 ◽  
Vol 921 ◽  
pp. 40-47
Author(s):  
Jia Ying Zhang
Keyword(s):  
Kinetic Model ◽  
Orthogonal Design ◽  
Fixed Bed ◽  
Reaction Network ◽  
Space Velocity ◽  
Operating Conditions ◽  
Least Square ◽  
Fixed Bed Reactor ◽  
Consecutive Reaction ◽  
Wide Range

A comprehensive kinetic model for methanation of syngas on Ni-Mo-SiO2catalyst was developed on a fixed bed reactor data. The CO and H2conversion, methane selectivity and yield were obtained in a wide range of operating conditions including 300 < T < 450°C, 1 < H2/CO <4 and 0.1 < P < 1.5 MPa with the total weight hourly space velocity (WHSV) of 60000 ml/h/g. A 6-step reaction scheme defined to the description of a reaction network that considers both catalytic and gas-phase as well as primary and consecutive reaction steps to predict the performance of the syngas methantion. Orthogonal design method was adopted to select test points with temperature, pressure and feed compositions as factors and the kinetic rates involved Langmuir – Hinshelwood equation kinetic model. The kinetic rate parameters were estimated using the Least Square Method by MATLAB. Comparing the experimental and model predicted data showed that presented model has a reasonable fit between the experimental data and the predicted values with average absolute relative deviation of ±9.8%.

Thermochemical equilibrium modeling approach for carbon-rich feedstock gasification validated against laboratory and large-scale experiments

2020 ◽  
Author(s):  
Christopher Otto ◽  
Thomas Kempka
Keyword(s):  
Synthesis Gas ◽  
Reactive Transport ◽  
Large Scale ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Equilibrium Modeling ◽  
Modeling Approach ◽  
Wide Range ◽  
Thermochemical Equilibrium

&lt;p&gt;In the present study, a pre-existing stoichiometric equilibrium model based on direct minimization of Gibbs free energy has been further developed and applied to estimate the equilibrium composition of synthesis gases produced by the gasification of carbon-rich feedstock (e.g., coal, municipal waste or biomass) in a fixed-bed reactor [1]. Our modeling approach is validated against thermodynamic models, laboratory gasification and demonstration-scale experiments reported in the literature. The simulated synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas compositions derived from feedstock gasification, considering varying feedstock and oxidizer compositions as well as pressures and temperatures. Furthermore, the developed model can be easily integrated with numerical flow and transport simulators to simulate reactive transport of a multi-componentgas phase.&lt;/p&gt;&lt;p&gt;[1] Otto and Kempka, Synthesis gas composition prediction for underground coal gasification using a thermochemical equilibrium modeling approach, Energies (in review)&lt;/p&gt;

Experimental and Model Based Study of the Hydrogenation of Acrolein to Allyl Alcohol

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
Christof Hamel ◽  
Michael Bron ◽  
Peter Claus ◽  
Andreas Seidel-Morgenstern
Keyword(s):  
Allyl Alcohol ◽  
Membrane Reactor ◽  
Fixed Bed ◽  
Packed Bed ◽  
Membrane Reactors ◽  
Fixed Bed Reactor ◽  
Reactor Model ◽  
Multi Stage ◽  
Parallel Reactions ◽  
Kinetics Of

The hydrogenation of acrolein was investigated experimentally in a fixed-bed reactor (FBR) using several classical and a newly developed hydrogenation catalyst. The aim was to evaluate selectivity and yield with respect to the desired product allyl alcohol. The kinetics of the two main parallel reactions of acrolein hydrogenation were quantified for a supported silver catalyst which offered the highest performance. In a second part the reaction kinetics identified were used in a theoretical study applying a simplified isothermal 1D reactor model in order to analyse the hydrogenation of acrolein performed in single- and multi-stage packed bed membrane reactors (PBMR). The goal of the simulations was to evaluate the potential of dosing one reactant in a distributed manner using one or several membrane reactor stages. The results achieved indicate that the membrane reactor concept possesses the potential to provide improved yields of allyl alcohol compared to conventional co-feed fixed-bed operation.

Development of a Kinetic Model for Modeling the Industrial VGO Hydrocracker Accompanied By Deactivation

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Azita Barkhordari ◽  
Shohreh Fatemi ◽  
Mahdi Daneshpayeh ◽  
Hossain Zamani
Keyword(s):  
Experimental Data ◽  
Kinetic Model ◽  
Catalyst Deactivation ◽  
Fixed Bed ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Wide Range ◽  
Silica Alumina ◽  
Parallel Reactions

Two types of kinetic modeling, continuous and discrete lump model were studied and compared in this research in order to model the industrial scale VGO hydrocracking process. The experimental data obtained from a pilot-scale fixed bed reactor over Ni-Mo/Silica-Alumina catalyst in a wide range of operating conditions was used for prediction and tuning the kinetic parameters using Genetic algorithm. In this study, the discrete lump model with four parallel reactions to four lumped products showed more convergence to the experimental data than the continuous lump model. Afterward, the discrete kinetic model was used to simulate the vacuum gas oil (VGO) industrial hydrocracking reaction accompanied by catalyst deactivation. The activity of the catalyst was taken as a time dependent variable and the first year of operational data were used to derive the deactivation parameter. The refinery test runs spanning over the last two and half years of operation were used to validate the model and interpret the simulation results. A comparison between the industrial and the predicted data showed that there is a good agreement between them and the presented model provides a reasonable fit to estimate the product yields of LPG, naphtha, kerosene, diesel.

Design of a continuous flow immobilized-cell reactor for biosynthetical production of L-aspartic acid

1985 ◽  
Vol 50 (10) ◽  
pp. 2122-2133 ◽  
Author(s):  
Jindřich Zahradník ◽  
Marie Fialová ◽  
Jan Škoda ◽  
Helena Škodová
Keyword(s):  
Aspartic Acid ◽  
Continuous Flow ◽  
Immobilized Cells ◽  
Scale Up ◽  
Fixed Bed ◽  
Packed Bed ◽  
Fixed Bed Reactor ◽  
Experimental Program ◽  
Design Parameters ◽  
Immobilized Cell

An experimental study was carried out aimed at establishing a data base for an optimum design of a continuous flow fixed-bed reactor for biotransformation of ammonium fumarate to L-aspartic acid catalyzed by immobilized cells of the strain Escherichia alcalescens dispar group. The experimental program included studies of the effect of reactor geometry, catalytic particle size, and packed bed arrangement on reactor hydrodynamics and on the rate of substrate conversion. An expression for the effective reaction rate was derived including the effect of mass transfer and conditions of the safe conversion-data scale-up were defined. Suggestions for the design of a pilot plant reactor (100 t/year) were formulated and decisive design parameters of such reactor were estimated for several variants of problem formulation.

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