Total Emittances of Ash Deposit Layers in a Power-Plant Boiler System

Abstract

Total emittance behavior of thermal radiation is investigated experimentally on ash deposit layers in a power-plant boiler system far lowquality coal powder combustion. The total emittances are measured at 570-1270K. The deposit layers of more than 1mm in thickness are found to be diffuse and opaque for the infrared radiation. The emittances range from 0.5 to 0.9. The emittances decrease with an increase in temperature, while the pulverized deposit layers which are sintered at higher than 1000K show a clear hysteresis phenomenon of the emittance. The emittances of the sintered layers are much higher than those of the unsintered layers.