Devolatilization studies on coals in a fixed bed reactor

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:7180930

Gokhale, A J

A laboratory scale fixed bed coal gasifier was designed to simulate the conditions existing in the devolatilization zone of an air blown Lurgi type fixed bed coal gasifier. Devolatilization behavior of a subbituminous and a bituminous coal was studied at 350 to 550/sub 0/C and at 30, 300, and 375 psig. Three feed coal particle sizes, (-2,+1), (-4,+3), and (-9,+6) mm, were studied. The feed gas was a synthetic mixture of composition similar to that leaving the gasification zone of a fixed bed gasifier and contained 30% by volume of steam. Devolatilization runs were conducted for 5, 10, 20, and 30 minute durations and the inlet and exit gas streams were analyzed. The tar samples were analyzed on a capillary gas chromatograph for individual components and thirty such components were quantified. The molecular weights of tar samples showed a maximum between 300 and 500. A first order kinetic model was applied to the total weight loss data and this yielded activation energies in the range 4 to 11 kcal/mol. For the subbituminous coal differential equations for concentration profiles for tar and gas inside the coal particle were solved numerically. From these calculations it was found that the pressure build-up (due to evolution of tar and gas) inside the coal particle was higher for larger particles, at a given external pressure, but decreased with external pressure. The concentration of tar inside the particle did not appear to be sensitive to low pressures (around 1 atm), but increased in the higher range of pressure (above 20 atm) and also with particle size. The devolatilization of the bituminous coal resulted in more than double the amount of tar as compared to that from the subbituminous coal.

• Research Organization: Western Biological Labs., Culver City, CA (USA)
• OSTI ID: 7180930
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
ACTIVATION ENERGY
BENCH-SCALE EXPERIMENTS
BITUMINOUS COAL
BLACK COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTION KINETICS
CHROMATOGRAPHY
COAL
COAL GAS
COAL GASIFICATION
COAL TAR
DEVOLATILIZATION
ENERGY
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUELS
GAS CHROMATOGRAPHY
GAS GENERATORS
GASES
GASIFICATION
KINETICS
MATERIALS
MATHEMATICAL MODELS
MOLECULAR WEIGHT
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PACKED BED
PARTICLE SIZE
REACTION KINETICS
SEPARATION PROCESSES
SIZE
STEAM
SUBBITUMINOUS COAL
TAR
THERMOCHEMICAL PROCESSES
TIME DEPENDENCE