Summary

The accepted criterion for flow of slag required for its removal from entrained flow coal fired gasifiers is the slag viscosity, with laboratory measurements of the viscosity of homogeneous (fully liquid) slags prepared from ash being used to establish the suitability of particular coals for the technology, and the necessity for adding flux during firing to lower viscosity. This Communication raises issues related to the direct application of the viscosity measurements, by examining the nature of slags sampled from pilot-scale gasifiers which has revealed their non-homogeneous nature.