Research on a thermal probe method for the measurement of pulverized-coal concentration in a pulverized-coal transport system of a power plant

The measurement of pulverized coal concentration represents one of the problems requiring an urgent solution in the ama of gas-solid two-phase flows. The authors have developed a measuring system incorporating thermal probes. The feasibility of measuring pulverized coal concentration by the system was investigated. In consideration of the thermal relaxation effect in two-phase flows a calculation formula is proposed based on a revised Reynolds number and Nusselt number. The test data obtained by using the above two revised numbers to correlate the gas-solid two-phase flow round the thermal probes have shown that the gas-solid two-phase flow and single-phase one have an identical heat exchange relation. On the basis of this mechanism the thermal probe measurement method has made it possible to keep the relative deviation of pulverized-coal concentration measurement results within ± 15%.