Correlating the Slagging of a Utility Boiler with Coal Characteristics

Abstract

This paper will describe how a utility was able to correlate intermittent slagging problems a boiler was experiencing with coal ash chemistry. The coal ash fusion temperatures alone were not sufficient to be able to separate the good versus poor performing coals. Further investigation revealed that the iron levels in the coal ash, and several indexes such as Base to Acid ratio, slagging factor and iron loading provided good bases for separating the coals that caused problems and those that did not. A total of nine coal supplies were burned in the boiler of which four caused furnace slagging problems. This utility experience further demonstrates the value of the ash chemistry data and the necessity of including more data than the fusion temperatures in coal specifications. The split between successful and unsuccessful coals is specific to this plant and should not be used universally. This work does demonstrate that ash chemistry can provide information for determining weather or not a coal can be successfully used at this plant.