Effects of preoxidation on rapid pyrolysis behavior and resultant char structure of caking coals

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

OSTI ID:6577033

Maloney, D J

An experimental investigation was conducted to determine the effects of mild preoxidation on subsequent rapid pyrolysis behavior of bituminous coals. Resulting char properties (surface area, morphology, C/H ratios, reactivity in air) were then analyzed to ascertain the effects of preoxidation on overall coal gasification potential. Two highly caking bituminous coals, and preoxidized samples of each coal (up to 2.5% oxygen added by wt.), were pyrolyzed in an entrained flow tube furnace (> 10/sup 4/ K/s heating rate) at temperatures between 1073 and 1273 K with heat treatment times up to 0.270s. Complementary slow pyrolysis (12 K/min) experiments were conducted to determine the effects of pyrolysis conditions on subsequent char properties. Volatile yields during rapid pyrolysis are found to increase signficantly with increasing temperature and approach asymptotic levels within 0.1 to 0.2 s. Chars produced by rapid heating of the unoxidized coals have classical cenosphere structures with particle diameters 2 times larger than the starting coals and apparent densities less than 0.1 g/cc. Corresponding micropore surface areas were found to be signficantly (2 to 3 times) higher than those observed for the parent coals. At the levels of oxidation employed, neither coal forms the cenosphere structures produced by the unoxidized precursors; however, some thermoplastic behavior is evident.

• OSTI ID: 6577033
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404 -- Coal
Lignite
& Peat-- Gasification
010407* -- Coal & Coal Products-- Solvent Extraction-- (-1987)
BITUMINOUS COAL
BLACK COAL
CARBONACEOUS MATERIALS
CHARS
CHEMICAL REACTIONS
COAL
COAL GASIFICATION
DECOMPOSITION
DENSITY
ENERGY SOURCES
FOSSIL FUELS
FUELS
GASIFICATION
MATERIALS
OXIDATION
PHYSICAL PROPERTIES
PYROLYSIS
PYROLYSIS PRODUCTS
THERMOCHEMICAL PROCESSES
VERY HIGH TEMPERATURE