Plant trial of an ultrasonic gauge for the on-line measurement of pulverised coal mass flow

The CSIRO Division of Minerals has developed and successfully plant tested an ultrasonic gauge for the on-line measurement of the mass flow rate of pulverised coal in a power station. In its simplest form, the CSIRO ultrasonic mass flow gauge comprises one pair of ultrasonic transducers mounted on opposite sides of a burner feed pipe such that the ultrasonic beam is at about 60° to the coal flow direction, thus enabling coal density and flow velocity (and hence coal mass flow) to be determined using a single pair of transducers. The ultrasonic gauge has been tested on a boiler feed line at Bayswater Power station, NSW, Australia. The results obtained have shown that the ultrasonic technique can measure coal loading to within 3.9% relative error and velocity to within 1.3 m/s over a wide range of plant conditions The main incentive for developing a pulverised coal mass flow gauge is to detect non-uniform distribution of pulverised coal and air to burners served by a common pulveriser. Once detected on-line correction techniques could be developed which could result in improved combustion efficiency, reduced tube erosion and reduced fouling and slagging