Modeling a fluidized-bed coal gasification reactor
A steady-state model has been developed to simulate the North Carolina State University pilot-scale fluidized bed coal gasification reactor. The model involves instantaneous devolatilization of coal in the free-board region and char combustion and gasification in the fluidized bed. A two-phase representation of the fluidized bed incorporates the phenomena of jetting, bubbling, slugging, and mass and heat transfer between phases. The model has the ability to predict both concentration and temperature profiles, the latter being useful in the prediction of possible clinker formation at hot spots within the bed. The model has been successfully used to simulate the gasification of a devoltailized Western Kentucky bituminous coal and a New Mexico subbituminous coal. Effects of the molar steam/carbon feed ratio, molar oxygen/carbon feed ratio, fluidized bed height, and pressure on gasifer performance have been studied parametrically with the two-phase model. The molar steam/carbon feed ratio has moderate negative effects on the reactor performance. The approach to water-gas shift equilibrium is favored by lowering the steam/carbon ratio and/or raising oxygen/carbon ratio. The effects of moderate change sin bed height and pressure on the gasifier performance are small, implying that the reactor can be operated at any bed height and pressure near the targeted operating conditions without significantly affecting the gasifier output. Organic sulfur distributions in a New Mexico subbituminous coal and a Texas lignite have been determined by a nonisothermal technique. A three-stage well-mixed bed model incorporating the hydrodesulfurization kinetics of Yergey et al. was used to correlate the evolution rate of H{sub 2}S from coal or char during gasification.
- Research Organization:
- North Carolina State Univ., Raleigh, NC (USA)
- OSTI ID:
- 5633307
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL GASIFICATION
MATHEMATICAL MODELS
BITUMINOUS COAL
BUBBLES
CARBON
CARBON OXYSULFIDE
CHARS
CHEMICAL REACTION KINETICS
COMBUSTION
DESULFURIZATION
DEVOLATILIZATION
DIMENSIONS
FLUIDIZED BEDS
GAS GENERATORS
HEAT TRANSFER
HYDROGEN SULFIDES
KENTUCKY
LIGNITE
MASS TRANSFER
NEW MEXICO
NORTH CAROLINA
OXYGEN
PERFORMANCE TESTING
PRESSURE DEPENDENCE
QUANTITY RATIO
STEAM
SUBBITUMINOUS COAL
SULFUR CONTENT
SYNTHESIS
TEMPERATURE DISTRIBUTION
TEXAS
BLACK COAL
BROWN COAL
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
ELEMENTS
ENERGY SOURCES
ENERGY TRANSFER
FEDERAL REGION IV
FEDERAL REGION VI
FOSSIL FUELS
FUELS
GASIFICATION
HYDROGEN COMPOUNDS
KINETICS
MATERIALS
NONMETALS
NORTH AMERICA
OXIDATION
PYROLYSIS PRODUCTS
REACTION KINETICS
SULFIDES
SULFUR COMPOUNDS
TESTING
THERMOCHEMICAL PROCESSES
USA
010404* - Coal
Lignite
& Peat- Gasification