Western Coals—Laboratory Characterization and Field Evaluations of Cleaning Requirements

Abstract

Many discussions have pointed out the differences in the characteristics of eastern and western coals. Low rank western coals have higher moistures, lower calorific values, and the ash constituents are more basic. Slagging and fouling indexes based on the ash chemistry of eastern bituminous coals are not applicable for low rank western coals. These differences led to dissimilarities in the behavior of eastern and western coals, so we have directed our efforts toward a study of the behavior of low rank western coals and how they differ from eastern coals. Three nonroutine laboratory tests: (1) burning profiles, (2) coal ash sintering strengths, and (3) viscosity temperature relationship of coal ash were used to distinquish the difference in the behavior of these coals. Three generating stations were selected to compare slagging and fouling predictions with soot blower performance. The coals burned at these stations were: (1) a North Dakota lignite, (2) a Montana subbituminous coal, and (3) an Illinois bituminous coal. Excellent results were noted as the observed soot blower performance and the performance predicted by our evaluation of the slagging and fouling characteristics of the coals were in agreement.