Measurement and prediction of fly ash resistivity over a wide range of temperature

Resistivity is a key factor in the efficient and stable operation of electrostatic precipitators. Sixty types of typical industrial fly ashes were collected for this study. Subsequently, fly ash resistivity at the temperature range of 303-1073 K, and the chemical compositions, micrographs, and size distributions of the samples were measured. The joint influence of chemical composition and temperature on resistivity was also investigated. The main components of the fly ash samples were Fe (0.8-5.0%), K + Na + Li (0.3-5.1%), Ca + Mg (0.5-4.0%), and Al + Si (10-34%), respectively. Fe, K, and Na were highly sensitive to fly ash resistivity. Resistivity decreased with the increase in Fe, K, Na, and Li contents; by contrast, resistivity increased with Ca and Mg contents. The effects of Si and Al on fly ash resistivity were weak. Resistivity initially increased first and then decreased with the increase in temperature. Maximum resistivity was observed at 373-473 K. Based on the experimental data, a prediction model for fly ash resistivity over a wide range of temperature (303-1073 K) was established. The resistivity diagrams generated specifically for this study suggest that typical fly ash samples from different industries can be estimated using chemical composition and temperature data.