Abstract: The apparatus receives a source of air and a sulfur-bearing source. The apparatus can condition the gas within an electrostatic precipitator of an industrial plant. The apparatus has a sulfur vessel having an output and an input. The sulfur vessel communicates with the sulfur-bearing source and the source of air, for at least providing gaseous, oxidized sulfur. The apparatus includes a supply of liquid, oxidized sulfur and the sulfur vessel includes an evaporator communicating with the supply of liquid, oxidized sulfur for evaporating it. Also included is a converter having an outlet and having an inlet communicating with the output of the sulfur vessel for converting the gaseous, oxidized sulfur into a conditioning medium. The apparatus also includes a sensor, a modulator and a delivery system. The sensor is connected to the outlet of the converter for providing a converted temperature signal signifying the temperature of the outlet of the converter.

Abstract: Apparatus and method for precipitation of fly ash from flue gas of a coal burner wherein liquid sulfur is burned to form SO.sub.2. The SO.sub.2 is converted to SO.sub.3 and injected into the flue gas. The sulfur burning process is modulated and controlled.