The coal quality effect model (CQEM) is an effective tool that encompasses all components in the coal chain and represents the performance of coal-fired boilers with the use of solid engineering principles and historical cost analyses. The CQEM analyses individual plant component performance with respect to varying coal properties and predicts the plant limitations, maintenance strategies, material life expectancy and the coal distress and rejection levels.

The CQEM currently plays a vital role in assisting Eskom during its crisis period, especially with regard to wet coal. The modelled results have shown that the pulverisers or mills that perform a dual function (drying and grinding) exceed their drying capacity and reduce the throughput which results in load losses when a certain level of moisture in the coal is reached. The CQEM’s future potential application resides in evaluating coal quality and can be a training tool.