Abstract: A flue gas conditioning system (FGC) for conditioning the flue gas flowing in a flue from a boiler to an electrostatic precipitator by injecting sulfur trioxide into the flue gas upstream of the electrostatic precipitator. The FGC has a source (52) of granulated sulfur which is transported by a conveyor (54) to a sulfur furnace (60) where it is combusted in sulfur dioxide. The sulfur dioxide flows from the sulfur furnace (60) into a catalytic converter 62 which generates sulfur trioxide therefrom. The sulfur trioxide flows from the catalytic converter 62 into probes 64 which are mounted in the flue duct. Alternatively, the FGC has a source (70) of emulsoid sulfur which is pumped by a sulfur pump (72) to the inlet of an atomizing spray nozzle (200) which atomizes the emulsoid sulfur and sprays it into sulfur furnace (50).

Abstract: A flue gas conditioning system features a self-contained sulfur burner control loop that operates to maintain a constant desired temperature supply of sulfur dioxide in air by varying the rate of supply of sulfur fuel to the sulfur burner, and the absence of device in the sulfur flow path to measure or monitor sulfur flow rate. In the system, a conditioning agent demand signal operates either a means to supply the sulfur burner with a flow of air, or an air heater in the air flow path upstream of the sulfur burner, or both, to provide conditions that would increase or decrease the temperature of the sulfur burner output absent the self-contained sulfur burner control loop, and as a result of the operation of the self-contained sulfur burner control loop, systems of the invention can provide a demanded flow of sulfur dioxide and air at a substantially constant concentration and a desired temperature to a catalytic converter in response to a conditioning agent demand signal.

Abstract: An air pollution control system for injecting a conditioning agent into the flue gas of a power generator. The conditioning agent changes the resistivity of particulate matter in the flue gas, rendering the particulate matter more easily able to accept an electrostatic charge. Control of the conditioning gas injection rate is monitored by periodically sampling the average input power supplied to the power supplies of the electrostatic flue gas conditioning system. A proportional-integral controller receives the signal representing the difference between the average input power and a predetermined threshold signal. The control signal produced by the proportional integral controller causes incremental changes in the rate at which the conditioning agent, such as SO.sub.3, is added to the flue gas.