Fault Detection in Coal Mills Used in Power Plants

In order to achieve high performance and efficiency of coal-fired power plants, it is highly important to control the coal flow into the boiler in the power plant. This means suppression of disturbances and force the coal mill to deliver the required coal flow, as well as monitor the coal mill in order to detect faults in the coal mill when they emerge. This paper deals with the second objective. Based on a simple dynamic model of the energy balance a residual is formed for the coal mill. An optimal unknown input observer is designed to estimate this residual. The estimated residual is following tested by measured data of a fault in a coal mill, it can hereby be concluded that this residual is very useful for detecting faults in the coal mill.