Keywords

Coal combustion; Pyrolysis; Pressure; Swelling ratio; Reactivity

Abstract

A high-temperature, high-pressure flat-flame burner reactor was developed to prepare char at different pressures. This system achieves particle heating rates of 105 K/s, which better mimics industrial conditions than conventional drop tube or radiative flow reactors. Previous data at atmospheric pressure demonstrated a significant decrease in particle swelling during devolatilization as heating rates increased from 104 K/s (the typical drop tube heating rate) to 105 K/s. Pyrolysis experiments were performed at pressures from 1 to 15 atm at 1300 C for two bituminous coals and a lignite. Average swelling was determined from a combination of the mass release and the average density. The results indicate significantly lower swelling ratios at elevated pressures than reported in the literature. Scanning electron micrographs show that the bubbles in the bituminous coal particles popped before significant swelling at these elevated heating rates. Lignite particles exhibited shrinkage rather than swelling, but still showed a small effect of pressure. TGA oxidation reactivities were determined for the Pitt #8 and Knife River lignite char samples at their respective char preparation pressures. The oxidation reactivities of both the bituminous and lignite chars decreased with increasing pressure.

Original Publication Citation

Zeng, D., M. Clark, T. Gunderson, W. C. Hecker, and T. H. Fletcher, “Swelling Properties and Intrinsic Reactivities of Coal Chars Produced at Elevated Pressures and High Heating Rates,” Proceedings of the Combustion Institute, 30, 2213-2221 (2005).

Document Type

Peer-Reviewed Article

Publication Date

2005

Publisher

Elsevier

Language

English

College

Ira A. Fulton College of Engineering

Department

Chemical Engineering

University Standing at Time of Publication

Full Professor

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