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Title: Experiments and Computational Modeling of Pulverized-Coal Ignition

Abstract

Under typical conditions of pulverized-coal combustion, which is characterized by fine particles heated at very high rates, there is currently a lack of certainty regarding the ignition mechanism of bituminous and lower rank coals. It is unclear whether ignition occurs first at the particle-oxygen interface (heterogeneous ignition) or if it occurs in the gas phase due to ignition of the devolatilization products (homogeneous ignition). There have been no previous studies aimed at determining the dependence of the ignition mechanism on variations in experimental conditions, such as particle size, oxygen concentration, and heating rate. There is a need to improve current mathematical models of ignition to realistically and accurately depict the particle-to-particle variations that exist within a coal sample to enable the extraction of useful reaction parameters from ignition studies, and to interpret ignition data in a more meaningful way. We examine fundamental aspects of coal ignition through experiments to determine the ignition mechanism of various coals by direct observation, and modeling of the ignition process to derive rate constants to provide a more insightful interpretation of data from ignition experiments. The heating source will be a pulsed, carbon-dioxide laser in which both the pulse energy and pulse duration are independentlymore » variable, allowing for a wide range of heating rates and particle temperatures � both of which are decoupled from each other and from the particle size. Laser-ignition experiments also offer the distinct advantage of easy optical access to the particles because of the absence of a furnace or radiating walls, and thus permit direct observation and particle temperature measurement. The ignition mechanism of different coals under various experimental conditions can therefore be easily determined by direct observation with high-speed photography. The ignition rate-constants, when the ignition occurs heterogeneously, and the particle heating rates will both be determined from analyses based on direct, particle-temperature measurements using two-color pyrometry.« less

Authors:
Publication Date:
Research Org.:
Federal Energy Technology Center, Morgantown, WV, and Pittsburgh, PA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
2115
Report Number(s):
DE-FG22-96PC96221-04
ON: DE00002115
DOE Contract Number:  
FG22-96PC96221
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
20 FOSSIL-FUELED POWER PLANTS; 01 COAL, LIGNITE, AND PEAT; Coal; Carbon Dioxide Lasers; Combustion Kinetics; Mathematical Models

Citation Formats

Chen, John C. Experiments and Computational Modeling of Pulverized-Coal Ignition. United States: N. p., 1998. Web. doi:10.2172/2115.
Chen, John C. Experiments and Computational Modeling of Pulverized-Coal Ignition. United States. https://doi.org/10.2172/2115
Chen, John C. 1998. "Experiments and Computational Modeling of Pulverized-Coal Ignition". United States. https://doi.org/10.2172/2115. https://www.osti.gov/servlets/purl/2115.
@article{osti_2115,
title = {Experiments and Computational Modeling of Pulverized-Coal Ignition},
author = {Chen, John C},
abstractNote = {Under typical conditions of pulverized-coal combustion, which is characterized by fine particles heated at very high rates, there is currently a lack of certainty regarding the ignition mechanism of bituminous and lower rank coals. It is unclear whether ignition occurs first at the particle-oxygen interface (heterogeneous ignition) or if it occurs in the gas phase due to ignition of the devolatilization products (homogeneous ignition). There have been no previous studies aimed at determining the dependence of the ignition mechanism on variations in experimental conditions, such as particle size, oxygen concentration, and heating rate. There is a need to improve current mathematical models of ignition to realistically and accurately depict the particle-to-particle variations that exist within a coal sample to enable the extraction of useful reaction parameters from ignition studies, and to interpret ignition data in a more meaningful way. We examine fundamental aspects of coal ignition through experiments to determine the ignition mechanism of various coals by direct observation, and modeling of the ignition process to derive rate constants to provide a more insightful interpretation of data from ignition experiments. The heating source will be a pulsed, carbon-dioxide laser in which both the pulse energy and pulse duration are independently variable, allowing for a wide range of heating rates and particle temperatures � both of which are decoupled from each other and from the particle size. Laser-ignition experiments also offer the distinct advantage of easy optical access to the particles because of the absence of a furnace or radiating walls, and thus permit direct observation and particle temperature measurement. The ignition mechanism of different coals under various experimental conditions can therefore be easily determined by direct observation with high-speed photography. The ignition rate-constants, when the ignition occurs heterogeneously, and the particle heating rates will both be determined from analyses based on direct, particle-temperature measurements using two-color pyrometry.},
doi = {10.2172/2115},
url = {https://www.osti.gov/biblio/2115}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Apr 30 00:00:00 EDT 1998},
month = {Thu Apr 30 00:00:00 EDT 1998}
}