Ensuring Technological Indicators for Nitrogen Oxide Emissions during Solid-Fuel Combustion in a High-Power Steam Boiler

Abstract

Organic fuel combustion products are one of the main sources of air pollution. When burning fossil fuels, pollutants harmful to human health, such as nitrogen and sulfur oxides, fly ash with particles of unburned fuel, carbon oxides, polycyclic aromatic hydrocarbons, and metal oxides, are released into the atmosphere. The largest emissions of pollutants into the atmosphere are accompanied by the combustion of solid fuels. In 2014, significant changes took place in the environmental legislation of the Russian Federation [1], which oblige energy enterprises to comply not only with sanitary and hygienic standards but also with technical and technological standards. To maintain technological indicators for specific NO_x emissions on boiler equipment at the regulatory level, it will be necessary to fully apply primary methods for suppressing the formation of nitrogen oxides, use low-toxic burners and fuel combustion schemes, and, in some cases, expensive gas purification from NO_x will be required. Based on statistical data, the BKZ-420-140 (E-420-140) boiler was selected as a prototype for research. When BKZ-420-140 boilers in the factory version operate using vortex burners when burning brown coal, the concentration of nitrogen oxides in the flue gases is more than 800 mg/m³, which significantly exceeds current standards. In order to reduce emissions of nitrogen oxides while ensuring high operating efficiency of boiler equipment, a solid-fuel combustion scheme using direct-flow burners and nozzles has been proposed for this boiler. It is shown that it will be possible to increase the economic and environmental efficiency of BKZ-420-140 boilers’ operation by implementing the developed solid-fuel combustion scheme using direct-flow burners and nozzles on them.