Concentration measurement with thermal probe for pulverized coal in the pneumatic pipeline of power plant

The concentration measurement of pulverized coal in a pneumatic pipeline is a challenging issue in power plant. A thermal probe manufactured with abrasion-proof steel was developed for coal concentration measurement in such a situation. The probe generates 15 W of heat. This method is based on the heat transfer between the thermal probe and the gas-solid two-phase flow. Experiments were conducted in a horizontal pneumatic pipeline to assess the accuracy of the thermal probe, where the gas was air and the solid was pulverized coal with mean diameter of 65 µm. The wall temperature of the thermal probe was found to be dependent on both coal powder concentration and air velocity. A new heat transfer correlation was proposed in terms of the modified Reynolds and Nusselt numbers for the gas-solid two-phase flow across the thermal probe. In the range of coal powder concentration from 0.1 to 0.65 kg/kg, the standard deviation is 0.01 kg/kg for the thermal probe. The thermal probe has potential application for concentration measurement of pulverized coal in the pneumatic pipelines of power plants.