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.