CLASSIFICATION OF METHODS FOR SANITARY PURIFICATION OF GASES FROM NITROGEN OXIDES

Abstract

Nitrogen oxides are among the most common and dangerous air pollutants. Their main amount is formed during hightemperature combustion of organic fuels in thermal power plants. Sources of nitrogen oxide emissions into the atmosphere differ in the amount of exhaust gases, the content of nitrogen compounds and other impurities, as well as the degree of oxidation of nitrogen oxide (II) (NO), temperature and pressure. In order to systematize the developed methods and conduct targeted research in this area, a classification of methods for sanitary purification of gases from nitrogen oxides was carried out. This classification is based on the ability of nitrogen oxides to oxidize, reduce, sorb and form substances that are easily regenerated under various conditions. The processes of NO oxidation using liquid, solid and gaseous oxidants were studied. Kinetic equations were obtained that describe the rate of this process depending on the concentration of solutions, temperature and pH of the medium. A high-temperature method has been developed in which thermal decomposition of nitrogen oxides occurs in the temperature range from 500 °C to 5000 °C using an arc plasmatron with a tungsten cathode and a copper anode. The catalytic properties of natural and artificial materials for increasing the rate of NO oxidation have been studied. It has been established that the reaction of heterogeneous catalytic oxidation of NO has a positive temperature coefficient. Catalysts capable of increasing the reaction rate by 1.5–2.5 times have been proposed. The considered purification methods can be used in the nitric acid industry during the operation of large units to achieve the maximum permissible concentration (MPC) standards in the surface layer of the atmosphere.