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Ash Behavior during Combustion and Gasification

AUTHOR: David H Scott
DATE: November 1999

Internationally traded coal is readily available at relatively low cost from a variety of suppliers. In this competitive environment long established coal quality criteria are being re-examined. Potential suppliers are concerned that their product should not arbitrarily be excluded by inappropriate tests. On the other hadn, power station operators need to be confident that they can adequately predict the consequences of using an unfamiliar coal.

Slagging indices for coals based on bulk ash composition are now known to have limitations. The rapid increase in affordable electronic processing power applied to CCSEM and x-ray spectroscopy provided a more detailed knowledge of the composition and distribution of minerals within a coal. This showed that the behavior of excluded mineral matter was different from that of included mineral matter. New slagging indices have been proposed, based on traditional indices such as base/acid ratio but also incorporating additional information from CCSEM.