Analysis of steady-state reaction fronts in a porous medium

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · AIChE Journal (American Institute of Chemical Engineers); (United States)

DOI:https://doi.org/10.1002/aic.690391011· OSTI ID:5997269

Escobedo, F; Viljoen, H J ^[1]

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1. Univ. of Nebraska, Lincoln, NE (United States). Dept. of Chemical Engineering

Reactions in porous media form an important part of several technologies. Examples of reactions in porous media are found in catalytic reactors, gas-solid combustion synthesis (SHS), coal gasification, combustion in oil shale, catalyst regeneration, and porous radiant burners (PRB). A pseudo homogeneous model is used to analyze the steady state of a sharp reaction front in a porous medium. The reaction rate is described by the flame sheet approximation, and an asymptotic matching analysis is used to determine the temperature, conversion and position of the reaction front. Both adiabatic and nonadiabatic operations are considered, and the effect of radiation is included in the adiabatic case. The results show that there exists a maximum molar flux before blowout occurs. The critical molar flux is decreased by higher activation energies, but it is increased by higher rate constants and flame temperatures. Radiation further stabilizes the flame against blowout. Expressions are provided for the flame temperature, reactant conversion and the conditions when blowout occur. It is also shown that under certain conditions the front has two steady-state positions.

• OSTI ID: 5997269
• Journal Information: AIChE Journal (American Institute of Chemical Engineers); (United States), Journal Name: AIChE Journal (American Institute of Chemical Engineers); (United States) Vol. 39:10; ISSN 0001-1541; ISSN AICEAC
• Country of Publication: United States
• Language: English

Related Subjects

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010404 -- Coal
Lignite
& Peat-- Gasification
04 OIL SHALES AND TAR SANDS
040401 -- Oil Shales & Tar Sands-- In Situ Methods
True & Modified
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
BITUMINOUS MATERIALS
BLOWOFF
CARBONACEOUS MATERIALS
CATALYSTS
CHEMICAL REACTIONS
COAL GASIFICATION
COMBUSTION
ENERGY SOURCES
FLAME PROPAGATION
FLAMES
FOSSIL FUELS
FUELS
GASIFICATION
HEATERS
IN-SITU COMBUSTION
IN-SITU PROCESSING
MATERIALS
MATHEMATICAL MODELS
OIL SHALES
OXIDATION
POROUS MATERIALS
PROCESSING
RADIANT HEATERS
REGENERATION
ROCKS
SEDIMENTARY ROCKS
SHALES
STEADY-STATE CONDITIONS
THERMOCHEMICAL PROCESSES