The report gives results of a laboratory test demonstrating the feasibility of electrostatic precipitation at high temperatures (to 1366 K) and pressures (to 3550 kPa): corona currents were stable at all temperatures. Detailed current/voltage characteristics under negative and positive polarity were obtained in dry air, in a simulated combustion gas, and in a substitute fuel gas for each temperature and pressure level. Major effects of temperature, pressure, and electrode geometry on precipitator design characteristics (sparking voltages, corona starting voltages, and current levels) were evaluated. This work has established that no practical temperature or pressure limitation exists to the levels tested. A preliminary cost estimate is presented for a commercial-size precipitator design applied to a commercial fluidized-bed combustor and turbine system.

Prepared under contract no. 68-02-2104, program element no. EHE623A. Issued Nov. 1977. Includes bibliographical references.

The feasibility of electrostatic precipitation at temperatures and pressures varying from room conditions to 1366K and 3550 kPa, respectively, has been demonstrated in a laboratory wire-pipe electrode system. Subject to appropriate choices of polarity and pressure, stable corona discharges are obtained at all temperatures. Current-voltage characteristics for both polarities are reported for dry air, a simulated combustion gas, and a substitute fueld gas. The effects of temperature, pressure, and electrode geometry on sparkover voltages, corona-starting voltage and current are evealuated. It is recommended that this study be extended to pilot coal gasifiers and fluidized-bed combustors to obtain detailed design data, and permit determination of collection efficiencies and precipitate characteristics under actual operating conditions. A preliminary cost estimate is presented for a precipitator intended for use in connection with a commercial fluidized-bed combustor and turbine system.