Devolatilization of coal by rapid heating
Coals were devolatized at rates comparable to those encountered in combustion and gasification processes. Rapid pyrolysis was attained with pulse heating equipment developed for this purpose. This technique permitted the heating time and the final temperature of the coal samples to be controlled. A rate of heating of approximately 10/sup 4/ /sup 0/C/sec was achieved. Coals encompassing a rank from subbituminous A to low volatile bituminous were studied. All bituminous coals exhibited devolatilization curves which were characteristically similar. Decomposition started at about 400/sup 0/C and increased to a maximum in the region 700-900/sup 0/C. Beyond the well-defined peak, an increase in volatiles reappeared only at or above 1100/sup 0/C. Devolatilization of subbituminous A coal differed markedly from this pattern. The products of devolatilization are gases, condensable material or tar, and residual char. Mass spectrometric analysis showed the gas to consist principally of H/sub 2/, CH/sub 4/, and CO. Higher hydrocarbons, up to C/sub 6/, were present in small quantities. The molecular weight of the gas was found to decrease with increase in both reaction temperature and rank of coal. The volume of gases generated from devolatilization increased progressively with increase in temperature, but displayed little variation with rank of coal. Distribution of volatile products between tar and gas was determined for some experimental conditions, and correlations were made between yields of these individual products and the parameters of temperature and rank of coal. Greater volatile yields were obtained from the lower rank coals and clearly were due to increased formation of tar relative to gas. The effect of raising the devolatilization temperature of the coal was to increase the amount of gas at the expense of the tar.
- Research Organization:
- Bureau of Mines, Pittsburgh
- OSTI ID:
- 7359804
- Journal Information:
- Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States), Vol. 18:1; Conference: 165. meeting of the American Chemical Society, Dallas, TX, USA, 8 Apr 1973; Other Information: See CONF-730403--P1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHARS
PRODUCTION
COAL
DEGASSING
PYROLYSIS
COAL GAS
COAL TAR
BITUMINOUS COAL
COAL RANK
HEATING
SUBBITUMINOUS COAL
TEMPERATURE EFFECTS
VERY HIGH TEMPERATURE
VOLATILITY
BLACK COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUELS
GASES
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
TAR
010406* - Coal & Coal Products- Pyrolysis & Cracking- (-1987)