Abstract: A gas conditioning system for reducing the electrical resistance of finely-divided fly ash particles entrained within a flue gas stream resulting from the burning of low sulfur coal and for enhancing the removal of the fly ash particles by electrostatic precipitation wherein an acid conditioning agent, e.g., sulfuric acid, is passed through a vaporizing coil mounted within an enclosure defining a mixing chamber downstream from the coil and is vaporized by a stream of hot air passing over the coil and into the mixing chamber. The vaporized acid exits the coil and mixes with the hot air in the mixing chamber and the resulting mixture is injected into the flue gas stream so that the acid vapor can condense on the fly ash particles.

Abstract: Discharge electrodes in electrostatic precipitators are protected from erosion caused by power arcs in the area along their length which is closest to the ground electrode plates by a shroud of high temperature insulating plastic such as Teflon. The shroud is formed in two longitudinally slidable interlocking sections which completely surround and insulate the electrode wire but can be assembled to the wire without disturbing its ends.

Abstract: In order to reduce the electrical resistance of entrained fine particles of fly ash resulting from the burning of low sulfur coal and to enhance the efficiency of their collection by an electrical precipitator means, there is a conditioning of the particles carried in the flue gas stream by having a very fine mist of H.sub.2 SO.sub.4 condensed and adsorbed on the particles themselves. Sulfuric acid is mixed with air in an acoustic nozzle to form a mist having a mean particle size of less than 10 microns which is injected uniformly into the flue gas stream at a zone ahead of the precipitator unit so that the acid can condense on the particles. The acid is preferably transported through the apparatus at ambient temperature and then heated just prior to injection to a temperature less than its vaporization temperature.