05/01632 Unidimensional heat transfer analysis of elephant grass and sugar cane bagasse slow pyrolysis in a fixed bed reactor

A gas heated steam reformer (GHR) which converts natural gas to synthesis gas for methanol or Fischer-Tropsch purposes has been modelled for steady state conditions. The model is in two dimensions and is made up of a fixed bed reactor model, representing one of the reactor tubes in the GHR, and an annulus model, representing the annular space on the shell side of the GHR where hot, fully converted syngas emits heat to the reactor tube. The annulus model is described and evaluated in this article. This is a plug flow model which involves heat transfer in radial direction caused by radiation and by turbulence. The gas radiation is modelled by the use of the discrete ordinates method and the effect on heat transfer from turbulence is modelled as an effective radial thermal conductivity. Both heat transfer mechanisms vary with the radial position. An additional annulus model, made in the commercial CFD code FLUENT and based on the k-? turbulence model and the discrete ordinates radiation model, is used to estimate effective radial thermal conductivities. These were implemented in the annulus model of the GHR model. The reactor and the annulus models were combined and linked by the wall temperature profile and the heat flux profile on the outer reactor tube wall. The simulation results were used to study the heat flux and temperature profiles along the reactor length and the radial temperature profiles in the annulus.

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Oxidative dehydrogenation of ethane to ethylene over phase-pure M1 MoVNbTeOx catalysts in a micro-channel reactor

Catalysis Science & Technology ◽

10.1039/c4cy01742k ◽

2015 ◽

Vol 5 (5) ◽

pp. 2807-2813 ◽

Cited By ~ 21

Author(s):

Bozhao Chu ◽

Lara Truter ◽

Tjeerd Alexander Nijhuis ◽

Yi Cheng

Keyword(s):

Heat Transfer ◽

Oxidative Dehydrogenation ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Micro Channel ◽

Channel Reactor ◽

Reaction Conditions ◽

Oxidative Dehydrogenation Of Ethane ◽

Phase Pure

Due to its excellent heat transfer ability, the micro-channel reactor with coated phase-pure M1 catalysts can achieve reactor productivity nearly 5 times higher than that of a traditional fixed-bed reactor under the same reaction conditions in oxidative dehydrogenation of ethane (ODHE).

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

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1771 ◽

2008 ◽

Vol 6 (1) ◽

Cited By ~ 2

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.

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