The conception of complex flue gas cleaning from fly ash and oxides utilizing pulse corona discharge in electrostatic precipitator at high concentration of dust particles was developed by authors. When streamer corona develops in flue gas the following processes are developed: 1) When the conversion of SO2 is produced the acidic dew point increases. For coal boiler with the gas temperature of 140-160 °C only 15-20 ppm of SO3 is necessary for equals acidic dew point to gas temperature. The products of the SO2 conversion react with water vapor and form a sulfuric acid. 2) The H2SO4 molecules diffuse to dust particles and produce acid film that decreases the specific resistance of ash layer. These process would aid collection in an electrostatic precipitator by reducing back-corona. This method differs from chemical conditioning, and was called agentless Electrophysical Conditioning (EPC). 3) The vapors from flue gas condense on the dust particles. The SO2 molecules dissolve in the condensed liquid and form H2SO3 that is oxidized by oxygen up to H2SO4. Simultaneously NO dissolves producing HNO3. The acids formed are neutralized by the components of the fly ash. These processes decrease the concentration of NOx and SO2 in the flue gas and can improve the collection of small dust particles. The investigations of nanosecond corona in flue gases with high concentration of dust particle were performed. The experiments showed the possibility of conversion of SO2 to SO3 at high concentration of fly ash.. The surface structure, sorption and neutralization property of fly ash of low sulfur fuel have been studied also. In the paper the results of investigation of SO2, NO conversion and VOC removal by pulse corona are reported also. A special reactor was installed in the gas distribution section of the conventional ESP to develop EPC. Reactor has a module design with the single module average power about 25 kW, pulse voltage up to 100 kV, pulse length of 500-1500 ns. The tests have shown a reliable performance of the single nanosecond module.
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