Selective Non-catalytic Reduction (SNCR) and its Efficiency with Respect to Various Combustion Parameters

Abstract

Nitrogen oxides, which are formed for example during the combustion process in coal power plants, have negative impact on the environment. It is one of the main components of greenhouse gases and together with sulfur oxides cause acid rains. When reducing the formation and discharge of nitrogen oxides, it is possible to proceed several technological processes. One of the methods that is used in practice for reducing these pollutants, is selective non-catalytic reduction (SNCR). Increasingly stringent emission limits forcing businesses to invest in a system for removing NOx. SNCR method is one of the cheapest, but sufficiently effective alternative to achieve these levels. This contribution describes the experimental tests of injecting a reducing agent into the flue gas stream. In this case a reducing agent (with the trade name Satamin) consisting of an aqueous urea solution and an additives. The tests were performed in the boiler K14 at the power plant in Ostrava - Trebovice, CZ. The aim of the tests was to reduce NOx emissions achieved by primary measures (e.g., adjusting the pressure of the boiler unit, low NOx pulverised coal burners, change media for grinding mill circuits) so that the flue gas at the outlet reaches3 3 approximately 190 mg/mN , because NOx emission limit specified by legislation is established to 200 mg/mN . Efficiency SNCR was determined based on the conversion rate of Satamin and the associated reduction of primary NOx to a final value measured at a chimney. The contribution shows and compares the impact of various factors (the concentration of CO in the flue gas stream, the primary value of NOx, the temperature in the combustion chamber, etc.) that affect, positively or negatively, the reaction process of Satamin and NOx according to the equations of Dvorák et al. (2010)