Prediction of Electrostatic Precipitation Performance

The collection efficiency of fly ash from Australian thermal coals in electrostatic precipitators (ESPs) is sometimes marginal in regard to satisfying emission limits with the installed ESP equipment. The prediction of ESP performance of a coal is presently less reliable than most other aspects of power plant performance.

The objective of this project was to improve the capability to predict the ESP performance of a coal from either coal quality data or laboratory-scale testing of the ash.

The project relied largely on a database and available samples of coal and fly ash held by the Combustion Technology Centre operated by ALS Coal at Riverview Queensland.

Fair prediction accuracy from coal properties was obtained from methods developed in this project. Improved accuracy may be possible if direct measures of fly ash particle size distribution and electrical resistivity were available, but the intention of this project was to enable predictions to be made when no fly ash is available for measurement of size and resistivity.

The project pointed to a moderately good correlation between the fly ash properties of size and resistivity with those of ash prepared in a laboratory furnace. The results were not statistically convincing because of the small number of samples, and it is intuitively unlikely that these properties would be the same for such widely differing ash formation conditions. Nevertheless the results may justify further investigation.