Decreases in the swelling and porosity of bituminous coals during devolatilization at high heating rates
- Brigham Young Univ, Provo, UT (United States)
Concern about comparability and validity of different methods for producing coal chars for reactivity experiments has led to research on the effect of devolatilization conditions on the char physical and chemical structure. Particle diameter and porosity changes during devolatilization significantly affect char oxidation rates. In particular, physical properties of chars prepared in drop tube reactors differ greatly from chars prepared in flat flame burner experiments. Recent data indicate that the presence of oxygen in the gas atmosphere has no effect on swelling until char oxidation has begun. The present research concentrates on the effects of heating rate, particle temperature and residence time on the swelling and porosity of a plastic coal, and compares these results with a nonplastic coal. The heating rate at which the transition from increasing swelling to decreasing swelling occurs is approximately 5 [times] 10[sup 3] K/s for swelling coals. Swelling coals also reach a maximum porosity near this heating rate. At low particle heating rates swelling gradually increases versus heating rate in contrast to a decline in a swelling at high heating rates in a narrow heating rate region of 2 [times] 10[sup 4] to 7 [times] 10[sup 4] K/s. Nonswelling bituminous and lignite coals continue to increase in porosity beyond the heating rate of 2 [times] 10[sup 4] K/s.
- OSTI ID:
- 6558805
- Report Number(s):
- CONF-940711-; CODEN: CBFMAO
- Journal Information:
- Combustion and Flame; (United States), Vol. 100:1-2; Conference: 25. international symposium on combustion, Irvine, CA (United States), 31 Jul - 5 Aug 1994; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BITUMINOUS COAL
DEVOLATILIZATION
POROSITY
SWELLING
CHARS
OXIDATION
LIGNITE
ACTIVATION ENERGY
DENSITY
PARTICLE SIZE
BLACK COAL
BROWN COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
ENERGY
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
PHYSICAL PROPERTIES
PYROLYSIS PRODUCTS
SIZE
014000* - Coal
Lignite
& Peat- Combustion
010600 - Coal
Lignite
& Peat- Properties & Composition