Plant tests of an on-line multiple-pipe pulverised coal mass flow measuring system

The CSIRO Division of Minerals has developed and successfully plant-tested a commercial prototype pulverised fuel (PF) mass flow measurement system on all four boiler feed lines from a single pulverising mill at Bayswater power station, in the Hunter Valley, NSW, Australia. The CSIRO PF mass flow measurement system utilises measurements of the attenuation and velocity of pulsed beams of 60 kHz ultrasound transmitted across the boiler pipes to determine the PF mass flow in each pipe. The system is used to detect non-uniform distribution of PF between boiler feed pipes. Using this information to balance the burners would lead to improved uniformity of combustion with the benefits of improved combustion efficiency, improved control of NOx emissions, reduced boiler tube erosion and reduced fouling and slagging. During calibration of the mass flow measurement system, PF was measured in the range 3.4–5.9% relative in individual pipes when compared with a beta-ray transmission gauge. A comparison of the mill gravimetric coal feed weighers with the cumulative PF flow measured by the PF mass flow measurement system showed agreement to within 1.8% relative over the primary air range 40–90%.