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General CSTR model for coal combustors and gasifiers

Conference ·
OSTI ID:6228616
;
A continuous stirred tank reactor (CSTR) model has been developed for application to coal combustors and gasifiers. Allowed fuels include coal, char and prevaporized hydrocarbons or any combination thereof. Four classes of reaction are considered: (1) coal pyrolysis: coal pyrolysis is modeled with two competing reactions. An extension to previous models is incorporated to approximate the volatiles composition; (2) char reactions: char reactions with O/sub 2/, H/sub 2/O, and CO/sub 2/ use the shrinking core model with a developing ash layer. Char is segregated from the remaining reactants to determine the size distribution inside the reactor and thus predict the effective reaction rate. Char particle temperature does not necessarily equal gas temperature; (3) hydrocarbon oxidation reactions: hydrocarbons other than methane use a quasi-global mechanism, i.e. the hydrocarbon is assumed to decompose into CO and H/sub 2/ in the presence of oxygen. A two step model is used for paraffins and a one step model for aromatics; (4) elementary reactions: reactions for species other than coal, char or hydrocarbons are modeled via a set of elementary reaction steps. All steps are reversible. Methane is modeled by an elementary sequence rather than by the quasi-global model. The model has been tested for sensitivity to hydrocarbon, pyrolysis and char kinetics, plus coal type, particle temperature and particle size. Some interesting aspects of this investigation, including the influence of residence time distribution on char particle size distribution and thus reaction rate and the prediction of a very wide stability range for rich coal mixtures are discussed. Successful performance predictions for an experimental pulverized coal cyclone reactor are presented.
Research Organization:
Tennessee Univ., Knoxville (USA); Purdue Univ., Lafayette, IN (USA)
OSTI ID:
6228616
Report Number(s):
CONF-830358-4; ON: DE83902095
Country of Publication:
United States
Language:
English

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Related Subjects

01 COAL, LIGNITE, AND PEAT
010404 -- Coal
Lignite
& Peat-- Gasification
014000* -- Coal
Lignite
& Peat-- Combustion
42 ENGINEERING
421000 -- Engineering-- Combustion Systems
CARBONACEOUS MATERIALS
CHARS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
COAL
COAL FINES
COAL GASIFICATION
COMBUSTION
COMBUSTION KINETICS
COMBUSTORS
CYCLONE COMBUSTORS
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
GASIFICATION
HYDROCARBONS
KINETICS
MATERIALS
MATHEMATICAL MODELS
ORGANIC COMPOUNDS
OXIDATION
PYROLYSIS
PYROLYSIS PRODUCTS
REACTION KINETICS
THERMOCHEMICAL PROCESSES