Hot precipitators operate reliably with high-resistivity fly ash

One solution to the problem of reducing SO/sub 2/ emissions from power plants is to burn fuels containing less sulfur. However, in most cases, burning low-sulfur fuels increases the electrical resistivity of fly ash, particularly fly ash at relatively low temperatures. This higher and unpredictable resistivity at lower temperatures, coupled with the high collection efficiencies (99.5 to 99.9 percent) demanded by mass emission and opacity codes, can spell trouble for low-temperature precipitators. That's why pollution control engineers are leaning toward precipitators operating above 650/sup 0/F where resistivity is not dependent on sulfur level. Other processes related to power generation, in addition to the conventional collection of fly ash, also require high-temperature gas cleaning. Coal gasification processes, which produce fuel gas for power generation in either a conventional steam electric power plant or in a combined cycle system, depend upon high-temperature gas cleaning. High-temperature catalytic conversion of SO/sub 2/ to SO/sub 3/ requires high-temperature, high-efficiency electrostatic precipitation. Seed recovery in MHD generation depends upon high-temperature operation. Electrostatic precipitation appears to be the most promising method for gas cleaning in this process.