Improved predictions of coal ash slagging during pulverised coal combustion

Coal ash slagging in pulverised coal combustion remains a major operational problem for the operators of utility boilers. The resulting loss in thermal efficiency, mechanical damage caused by falling deposits, and unscheduled outages all have serious economic consequences for an industry that is being forced to become increasingly competitive. This paper reviews the traditional methods which are used by fuel technologists to predict the slagging propensity of a coal ash, highlighting the reasons for the poor reliability and uncertainty associated with many of these methods. The development of new techniques for the characterisation of the coal mineral matter, the nature of the fly ash and deposits now provides the basis for new and improved predictions of the slagging propensity of a coal.