Abstract: An exhaust gas stream containing oxides of nitrogen and sulfur from a fossil fuel fired boiler, a fired process heater, or a chemical process are diverted from a stack prior to emission to the atmosphere through a duct system to a mixer where an oxidant, such as ozone, is added to the exhaust gas at a preselected molar ratio for a preselected residence time to transform the oxides to higher order nitrogen oxides. The oxidized contaminants are treated with a reagent solution. The reagent solution absorbs the oxidized contaminants and unreacted oxidant in the exhaust gas stream. Nitrogen and sulfur oxides in the gas steam are transformed to dilute acids which are neutralized to form salts suitable for discharge to a municipal waste water treatment plant or landfill disposal. The salt solution is also useful as a fertilizer or in the manufacture of fertilizers. The treated exhaust gas is then emitted from an exhaust stack containing NO.sub.x and SO.sub.

Abstract: Exhaust gases containing oxides of nitrogen and sulfur from a fired process heater, a fossil fuel fired boiler, or a chemical process are diverted from a stack prior to admission to the atmosphere through a duct system containing heat exchangers that reduce the exhaust gas from an elevated temperature, if any, to about ambient temperature. Any heat extracted from the exhaust gas may be transferred to the boiler feed water which would serve to reduce the energy cost of operating a boiler. Once the exhaust gas is cooled to about ambient temperature, the gas is then mixed with an oxidant, such as ozone, at a preselected molar ratio to transform the oxides to higher orders of nitrogen and sulfur oxides to increase the absorbability of the nitrogen and sulfur oxides in a reagent solution. The reagent absorbs the oxidized contaminants from the exhaust gas. The oxides are transformed to dilute acids which are then neutralized to form salts that are acceptable for discharge to a municipal waste water treatment plant.

Abstract: Exhaust gases containing oxides of nitrogen and sulfur from a fired process heater, a fossil fuel fired boiler, or a chemical process are diverted from a stack prior to admission to the atmosphere through a duct system containing heat exchangers that reduce the exhaust gas from an elevated temperature, if any, to about ambient temperature. Any heat extracted from the exhaust gas may be transferred to the boiler feed water which would serve to reduce the energy cost of operating a boiler. Once the exhaust gas is cooled to about ambient temperature, the gas is then mixed with an oxidant, such as ozone, at a preselected molar ratio to transform the oxides to higher orders of nitrogen and sulfur oxides to increase the absorbability of the nitrogen and sulfur oxides in a reagent solution. The reagent absorbs the oxidized contaminants from the exhaust gas. The oxides are transformed to dilute acids which are then neutralized to form salts that are acceptable for discharge to a municipal waste water treatment plant.

Abstract: An apparatus and method for retarding the formation of a slag ring on the inner wall of a rotary lime kiln where coal combustion gases are used to provide heat in the calcining chamber of a rotary lime kiln. The inner wall of the kiln, at a predetermined location where a slag ring would tend to form, is cooled so as to cool the dispersed slag prior to contact with the inner wall of the calcining chamber sufficiently to prevent adherence of the slag to the inner wall. Cooling chambers or a cooling channel may be provided in the refractory lining forming the inner wall, or transpiration devices may be provided to inject coolant into the calcining chamber, at the predetermined location, to cool the slag and prevent adherence thereof to the inner wall.

Abstract: A method and apparatus for calcining limestone to produce lime wherein coal is combusted to provide heat for the calcination. The coal is combusted in a two stage combustion unit, with at least seventy-five percent of the slag formed by the coal combustion removed from the first stage of the combustion unit. Residual gases and fuel are further combusted in the second stage of the two stage combustor, with hot combustion gases therefrom, having the molten slag removed, fed directly to the calcining chamber of a rotary lime kiln. The coal may be carbonized to form a char and a fuel gas for use in the two stage combustor.