Economic evaluation of fabric filtration versus electrostatic precipitation for ultrahigh particulate collection efficiency. Final report

The relative economics of electrostatic precipitators and fabric filters were studied for a variety of U.S. coals. The economic selection in each case was found to be dependent on the particulate emission limit to be met, the physical and chemical characteristics of the coal and fly ash, and the bag replacement schedule of the fabric filter. The studies were based on a 500 MW (net) pulverized-coal-fired power plant provided with a well-designed fly ash collector system of high reliability. For systems designed to meet the federal particulate emission limitation of 0.1 lb/10/sup 6/ BTU, the electrostatic precipitator had a clear advantage in one of the four cases. For systems designed to meet the more stringent New Mexico regulation of 0.05 lb/10/sup 6/ BTU, the fabric filter had a significant economic advantage in three of the four cases. If designs are based on obtaining a clear stack plume, the fabric filter has a significant advantage. The results clearly indicate that precipitator costs increase significantly as collection efficiency requirements are increased. Baghouse costs, on the other hand, remain essentially constant due to their inherently high collection efficiency. Baghouses become the economic choice for all coals, even low-resistivity eastern ones, when permissible emission levels drop much below the current NSPS of 0.1 lb/10/sup 6/ BTU. This conclusion must, of course, be tempered by the fact that no large, modern, pulverized coal units are presently operated with a baghouse, and therefore no accurate reliability record is available. This is especially critical to high sulfur coals where problems of corrosion have a greater probability of occurring than with low sulfur coal.