Contents Notes |
The filterability of fly ashes emitted by coal-burning power stations is described, including that of several ashes generated by low sulfur western U.S. coal combustion that are best controlled by fabric filtration. Chemical and mineralogical analyses of the coals were examined to determine possible relationships between coal and ash properties and filtration behavior. Both fly ash size and coal ash content correlated strongly with the fly ash specific resistance coefficient, Kb2s. Weaker, but discernible, correlations were shown for electrical charge behavior and method of coal firing. Coal sulfur content, ash fusion properties, and chemical structures originally expected to influence particle size showed no clear-cut effects on filtration characteristics. The relevant literature on pulse jet filter theory and applications was assessed to develop coherent guidelines for designing predictive filter models. The effects of jet size and location, jet air volume, and the intensity and duration of the jet pulses were related to pressure loss. Energy transfer from the jet pulse to the fabric was explored in terms of jet pressures, solenoid valve action, the ratio of pulse volume to bag volume, and the kinetic properties of the felt bags. Finally, predictive equations were developed for estimating pressure loss over a broad range of collector design and operating parameters. |