The effect of coal quality on the combustion performance of two Canadian thermal coals

Abstract

The expanded use of Canadian thermal coals for electricity generation highly depends on both the composition and quality control of coal. Purchase of off-specification, substitute coals or lack of consistency in supplies of a design coal often cause severe operational problems in utility boilers. To minimize the risks in utilizing coals with unpredictable burning properties, combustion experiments were conducted in a pilot-scale research boiler to evaluate the influence of changes in coal quality on the combustion, ash deposition and emission characteristics of two Canadian thermal coals which had not been used previously as a boiler fuel. One, a lignite coal with highly variable ash and moisture content, was highly reactive but required admixing of three different seams to optimize resource recovery. The other, an oxidized bituminous coal selected for its relatively low reactivity, was successfully burned by blending with a more reactive coal from a different deposit. The pilot-scale trials, by closely simulating utility boiler conditions, provided advance information on potential combustion-related problems prior to commercial use.