The influence of primary measures for reducing NO_x emissions on energy steam boiler efficiency

Within Electric Power Utility of Serbia 1991. a thermal power plant "Kostolac B", power 2x350 MW started. Given the increased emissions of NO_x in combustion products, it is in consideration to reduce it by introducing primary measures in terms of burner reconstruction, redistribution of secondary air by furnace height and introduction of cold flue gas recirculation. Applying these measures directly affects not only the combustion process in the furnace but also the work efficiency of steam boiler. Namely, if the flue gas temperature in furnace outlet is lowered below the corresponding values, it will cause the superheater and reheater not to achieve the designed steam parameters. On the other hand, the use of cold recirculating flue gases has a beneficial effect on reducing NO_x and increases the work safety of the superheaters and reheaters, but reduces the steam boiler efficiency. In order to understand all these effects on the safety and efficiency of boiler operation, it was needed to create a software for thermal calculation of the observed steam boiler. Based on that software, this paper will display the impacts of introducing the measures for reduction of NO_x emissions on a safe and efficient operation of the steam boiler as a whole.