Abstract: A boiler conveys an exhaust gas stream to a heat recovery device. The heat recovery device includes an air straightener, a heat recovery unit or feedwater heater, and a catalyst assembly positioned between the air straightener and the feedwater heater. The catalyst assembly has a catalyst drawer or bed that holds a quantity of catalyst materials for removing contaminants from the exhaust gas stream. The air straightener has a plurality of baffles that are arranged in a manner that optimizes the performance of the catalyst drawer or bed. The baffles also prevent condensation from leaking from the feedwater heater into the boiler. The feedwater heater recovers a quantity of heat from the exhaust gas stream.

Abstract: A boiler conveys an exhaust gas stream to a heat recovery device. The heat recovery device includes an air straightener, a heat recovery unit or feedwater heater, and a catalyst assembly postioned between the air straightener and the feedwater heater. The catalyst assembly has a catalyst drawer or bed that holds a quantity of catalyst materials for removing contaminants from the exhaust gas stream. The air straightener has a plurality of baffles that are arranged in a manner that optimizes the performance of the catalyst drawer or bed. The baffles also prevent condensation from leaking from the feedwater heater into the boiler. The feedwater heater recovers a quantity of heat from the exhaust gas stream.

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: Exhaust gases from a process fired boiler are diverted from a stack prior to emission to the atmosphere through a duct system to a plurality of series connected heat exchangers. The exhaust gases are progressively reduced from an elevated temperature, for example in the range between about 350.degree.-525.degree. F., in stages to an ambient temperature of about 50.degree. F. At each stage heat from the exhaust gases is transferred from the gases to another medium, such as water, which is fed back to the boiler to reduce the energy cost of operating the boiler. At ambient temperature the exhaust gases are subjected to an atomized spray of a reagent solution that absorbs the contaminants in the exhaust gases. Absorption of the contaminants into solution with the atomized reagent spray is promoted by contact of the spray and exhaust gases on the surface of a fibrous batting.