Analytical Characterization of Coals
Abstract
Faster and more efficient methods of analyzing coal are needed to
enable better decision making concerning combustion conditions at
facilities using coal as a primary fuel. Infrared spectroscopy
and thermoqravimetry are potentially excellent tools for
characterizing and analyzing coals of varying rank, which is
primarily a function of carbon content. In addition, chemical
composition of a coal of a given rank can be analyzed for various
degrees of combustion. These techniques have been developed for
samples of interest in electrical power generation.
Samples have been chosen with varying carbon content: 1. Beulah
Zap Lignite (73% C), 2. Illinois #6 High Volatile Bituminous (77%
C), 3. Lewiston-Stockton High Volatile Bituminous (81% C), 4.
Pocahontas #3 Low Volatile Bituminous (91% C). Initial studies
are comparative in nature for the virgin materials. Additional
studies monitor modifications induced by accelerated weathering
and oxidation. Diffuse reflectance infrared spectroscopy yields
specific chemical composition data to bolster the non-specific
thermogravimetric analysis.
This preliminary work leads to several conclusions. Initial
combustion temperatures increase with rank. Changes in mass
between 100 and 200°C are a strong function of the moisture
content of the sample. Oxygen insertion occurs in high carbon
content samples burned at low temperatures. Absorbance peaks in
the infrared spectra are correlated with oxygen and hydrogen
content.