Electromagnetic techniques for measurements on coal combustors

A microwave interferometric technique for measuring the density in the free-board space of a fluid bed combustor is described. A method for measuring the unburnt coal content in the ashes of a coal combustor is proposed. In the first case, the density measurement is obtained by evaluating the phase shift of an electromagnetic wave which propagated through the space under test. In the second case, the unburnt coal content is obtained by processing the reflection coefficient measured at the input section of a suitable holder for the ashes. The experimental results obtained for both measuring methods show the validity of the methods