Process for removing No.sub.x and So.sub.x from exhaust gas

A process for removing nitrogen oxides from an exhaust gas stream comprising the steps of,

• directing an exhaust gas stream containing nitrogen oxide contaminants at an elevated temperature from a process system to an exhaust duct,
• conveying the exhaust gas stream throuch the exhaust duct,
• mixing ozone in stoichiometric excess with the exhaust gas to oxidize the nitrogen oxide contaminants to convert nitrogen oxides in the exhaust gas stream to equimolar ratios of NO.sub.2 and NO.sub.3,
• transforming NO.sub.2 and NO.sub.3 in the presence of ozone to N.sub.2 O.sub.5,
• mixing a reagent liquid with the exhaust gas stream to convert N.sub.2 O.sub.5 to dilute acids of nitrogen and to neutralize the acids to nitrogen salts, and
• thereafter discharging the exhaust gas stream substantially free of nitrogen oxide contaminants from the exhaust duct.

A process for removing nitrogen and sulfur oxides from an exhaust stream comprising the steps of,

• directing an exhaust gas stream containing contaminants including nitrogen oxides and sulfur oxides at an elevated temperature from a process system to an exhaust duct,
• conveying the exhaust gas stream through the exhaust duct,
• mixing ozone in stoichiometric excess with the exhaust gas in a molar ratio in the range between about 0.2 to 2.8 moles of ozone to each mole of nitrogen oxide to convert the nitrogen oxides to equimolar amounts of NO.sub.2 and NO.sub.3.
• oxidizing the contaminants in the exhaust gas stream to increase the absorbability of the nitrogen oxides and sulfur oxides in water,
• maintaining the exhaust gas in contact with an excess amount of ozone for a preselected period of time,
• monitoring the residence time of the exhaust gas in contact with ozone to ensure substantially complete conversion of the nitrogen oxides in the exhaust gas to either NO.sub.5 or equimolar proportions of NO.sub.2 and NO.sub.3 with a marginal amount of unreacted ozone remaining in contact with the exhaust gas,
• admixing the sulfur oxides, excess ozone, oxidized contaminants containing N.sub.2 O.sub.5 and equimolar quantities of NO.sub.2 and NO.sub.3 with a reagent spray to convert N.sub.2 O.sub.5, NO.sub.2 and NO.sub.3 and sulfur oxides to dilute acids including HNO.sub.3, H.sub.2 SO.sub.3 and H.sub.2 SO.sub.4,
• absorbing the admixture of reagent spray containing the dilute acids including HNO.sub.3, H.sub.2 SO.sub.3, and H.sub.2 SO.sub.4 and excess ozone into liquid water,
• converting the dilute acids to salts including nitrates, sulfites and sulfates for removal from the exhaust gas stream,
• converting ozone dissolved in the reagent into oxygen with sulfite, and
• thereafter discharging the exhaust gas stream at about ambient temperature substantially free of the contaminants from the exhaust duct.