Sulfur-burning recommended for precipitator gas conditioning

Gas conditioning means injecting small quantities of SO/sub 3/ into the flue gas. This reduces the electrical resistivity of fly ash and makes the dust easier to collect in a precipitator. This makes it possible to increase electrostatic precipitator collection efficiency on fly ash from low-sulfur coal. Several types of commercial SO/sub 3/ gas conditioning systems, i.e., direct injection or evaporation of liquid SO/sub 3/, catalytic conversion of SO/sub 2/, vaporization of sulfuric acid, and sulfur burning followed by the catalytic conversion of SO/sub 2/ to SO/sub 3/, are described. Each system was built and tested, and compared for performance, capital investment, and operating cost. Sulfur-burning is the recommended method for conditioning power plant flue gas to improve electrostatic precipitator performance because: sulfur, being inert, is easily stored and handled; the only location of a corrosion or hazard problem is upstream of the catalytic converter; it has the lowest operating costs, and the capital cost is low and very competitive with the other approaches. (LCL)