Semi-dry ammonium desulfurization technology is proposed to meet the requirements of Directive 2010/75/EU on reducing sulfur dioxide emissions and obtaining dry product-ammonium sulfate. The peculiarity of this technology is the presence of a gas-phase reaction of sulfur dioxide with ammonia along with the absorption of SO 2 in drops of ammonia water. The efficiency of the absorption of sulfur dioxide by gaseous ammonia (up to 90%) has been experimentally proved, subject to the presence of water vapor in the gas, the volume concentration of which should exceed the volume concentration of ammonia.

A wet method for flue gas cleaning from ash and sulfur dioxide based on a wet venturi scrubber has been proposed An increase in the specific consumption of irrigation water in the Venturi tube of 0.7 kg/m3 and higher will allow reaching an output dust concentration below 20 mg/m 3 , while reducing the energy consumption of flue gas for droplet evaporation and fresh water consumption. The use of ammonia in wet desulfurization technology will allow the use of an existing wet scrubber while observing the SO 2 limit concentration of 200 mg/m 3 .

Purpose. Using mathematical modeling, to assess the feasibility of introducing a Selective Non-Catalytic Reduction (SNCR) system as a measure to reduce nitrogen oxide emissions from the production of iron ore pellets. To determine the peculiarities of using ammonia solution and urea solution as reagents for the SNCR process, the influence of the injection of these reagents on the temperature regime during iron pellet production, as well as assess the expected efficiency of the SNCR method for purification of exhaust gases from nitrogen oxides. Methodology. The research results have been obtained using CFD-modeling in the ANSYS Fluent software package. To model this process, a computational domain is constructed, which corresponds in size to the preheating zone (PRE zone) of the actual iron pellet production plant. Two series of calculations are performed for this domain: the first, without adding a reagent, and the second, with a urea solution as a reagent for the SNCR system. Findings. For the first series of calculations, the temperature field and the pressure field in the computational domain is obtained. Experimental research makes it possible to assert that the physical conditions of the mathematical model are close to those at a real plant for the production of pellets. In the second series of calculations, the temperature field in the computational domain is obtained and the influence of the reagent injection of the SNCR system is determined, namely, the temperature decrease in the PRE zone of the pellet production plant by 1025 . The expected efficiency of reduction of nitrogen oxides using a 50% urea solution is about 60%. Originality. It has been revealed that the process of urea solution evaporation is intense, which accelerates the beginning of urea decomposition and, accordingly, the reduction reaction of nitrogen oxides. The temperature drop in the zone of moisture evaporation does not exceed 1025 C. The reagent injection (50% urea solution) with a consumption of 219 kg/h does not significantly affect the temperature regime in the PRE zone. Modeling the chemical reactions of the SNCR process with the injection of 50% urea solution droplets through lances into the PRE zone chamber indicates a 60% reduction in nitrogen oxide emissions. Practical value. The introduction of the SNCR system at pellet production plant can reduce nitrogen oxide emissions, which will have a positive impact on the environmental situation in metallurgical regions.

Ammonia production using traditional Haber-Bosch technology using natural gas or coal emits large amounts of carbon dioxide and consumes a significant amount of electricity, its generation consumes a lot of fossil fuel and produces a large amount of emissions of pollutants and CO2. The transition to the production of "green" ammonia with the help of electricity from renewable energy sources and nuclear power plants will require a significant increase in their capacity. This will not only avoid CO2 emissions from NH3 production, but also avoid emissions of pollutants and greenhouse gases at thermal power plants by replacing their capacity with "green" capacity. Ammonia as a fuel has environmental advantages over traditional fuels, as it does not emit dust, sulfur dioxide, carbon monoxide and carbon dioxide. Only nitrogen oxides are formed, the emissions of which are reduced by the use of selective reduction technologies. Promising combustion of mixtures of ammonia and hydrogen. Co-combustion of coal and ammonia in existing boilers can significantly reduce emissions of pollutants and CO2. Bibl. 18, fig. 2, table. 2.

The need to reduce emissions of pollutants, in particular nitrogen oxides, as required by regulations in Ukraine, requires the use of modern technologies and methods for waste gas treatment at industrial enterprises. This is especially true of thermal power plants, which are powerful sources of nitrogen oxide emissions. The technological part of the wet or semi-dry method of purification is the area for the oxidation of nitrogen oxides to obtain easily soluble compounds. The paper presents the results of a study of the process of ozone oxidation of nitrogen oxides in a chemical reactor. Data for the analysis of the process were obtained by performing physical experiments on a laboratory installation and related calculations on a mathematical model. Studies of the oxidation process have shown that the required amount of ozone depends not only on the content of nitrogen monoxide, but also on the content of nitrogen dioxide. The process of conversion of nitrogen monoxide to a satisfactory level occurs at the initial value of the molar ratio of ozone to nitrogen monoxide in the range of 1.5…2. The conversion efficiency of nitrogen monoxide reaches 90% at a gas temperature less than 100 °C. To achieve high conversion efficiency at gas temperatures above 100 °C, it is necessary to increase the initial ozone content when the molar ratio exceeds 2. The analysis shows that the conversion efficiency of nitric oxide largely depends on the residence time of the gas mixture in the reaction zone. Due to lack of time under certain conditions, the efficiency decreases by approximately 46%. To increase it, it is necessary to accelerate the rate of oxidation reactions due to better mixing of gases by turbulence of the flow in the oxidizing reactor. Bibl. 6, Fig. 6, Tab. 3.