Biomass gasification reaction velocities

Conference · Thu Sep 01 04:00:00 EDT 1983

OSTI ID:5794042

Reed, T B; Markson, M

The propagation of gaseous flames is determined by the flame velocity, V/sub f/ (the rate at which the flame propagates into the unburned fuel/oxidant). In the same way, gasification of solid fuels depends on the gasification reaction velocity (V/sub r), the rate at which the reaction interface can move into the unreacted solid fuel. We have developed a simple laboratory transparent downdraft gasifier for measuring this velocity for a variety of fuels and conditions. Air or oxygen is drawn down through a 5-cm-diameter quartz tube. If the reaction zone remains stationary in the tube, V/sub r/ is simply the volumetric feed rate. For some input conditions, the position of the incandescent reaction zone is quite stable in the quartz tube. This position depends on the relative rates of production of charcoal by pyrolysis of the biomass and gasification of the charcoal by the pyrolysis combustion gases and can move up or down, depending on conditions. In an uninsulated tube the zone may move down indicating that the char gasification rate exceeds the pyrolysis rate. Adding insulation to the tube increases the tendency for the zone to move up, indicating that the pyrolysis rate is faster than the gasification rate. In practical gasifiers it is necessary to stabilize the reaction front such that the propagation rate equals the feed rate. A number of methods of stabilizing this front have been found. We believe the data and observations presented here help form the basis for a model of downdraft biomass gasification which is significantly different from previous models, and we are continuing to gather data for this model.

• Research Organization: Solar Energy Research Inst., Golden, CO (USA)
• DOE Contract Number: AC02-77CH00178
• OSTI ID: 5794042
• Report Number(s): SERI/TP-234-1964; CONF-821051-6; ON: DE84000010
• Country of Publication: United States
• Language: English

Related Subjects

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10 SYNTHETIC FUELS
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BIOMASS
CHEMICAL REACTORS
CONTROL
DIAGRAMS
ENERGY SOURCES
FLAME PROPAGATION
FLUIDS
FUEL GAS
FUELS
GAS FUELS
GAS GENERATORS
GASES
GASIFICATION
KINETICS
MATHEMATICAL MODELS
REACTION KINETICS
RENEWABLE ENERGY SOURCES
SOLID FUELS
STABILITY
THERMOCHEMICAL PROCESSES