Thermal analysis of coal under conditions of rapid heating
Thesis/Dissertation
·
OSTI ID:6888022
The effects of preoxidation and two-stage heating on the pyrolysis behavior of coal under conditions of rapid heating have been investigated using the heat loss compensation grid (HLCG) calorimeter. A subbituminous coal and preoxidized samples of coal (up to 0.7% oxygen added by wt.) were rapidly pyrolyzed to 900 K with a 400 K/s heating rate, and the enthalpy changes were measured. The results show that the pyrolysis in the temperature range from 298 to 900 K is endothermic process. One-third of total energy supplied to pyrolyze coal is consumed by the pyrolysis reaction. The mild preoxidation reduces the endothermicity of subsequent pyrolysis. Resulting thermophysical properties of coal, such as pyroheat, specific pyroheat, and heats of pyrolysis, decrease as the degree of preoxidation increases. The volatile yields increase with the level of preoxidation. The volatile yields increase with the heating rate, and this effect is enhanced with the level of preoxidation. After the initial 5 hrs oxidation, the volatile yields of preoxidized coals under rapid heating condition exceed the ASTM proximate volatile matter. The two-stage heating causes a reduction of the volatile yields as well as reduction of the heats of pyrolysis. Their degrees of reduction are different for each of the properties and each of the stages. The mass and energy balances of pyrolysis are strongly affected by the path being taken.
- Research Organization:
- Pennsylvania State Univ., University Park (USA)
- OSTI ID:
- 6888022
- Country of Publication:
- United States
- Language:
- English
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