Simplified method for calculating SNCR system efficiency

Division of Boilers and Steam Generators, Institute of Power Engineering and Turbomachinery, Silesian University of Technology, Konarskiego 20, 44-100 Gliwice, Poland

^* Corresponding author: marek.pronobis@polsl.pl

Abstract

SNCR (Selective Non-Catalytic Reduction) technology is aimed at reducing NO_x emissions. SNCR efficiency is appropriately high only for the reaction temperature range called ‘the SNCR temperature window’. It is a narrow temperature range defined in various ways in the literature, which makes it difficult to evaluate the DeNO_x system’s efficiency. Therefore, this study attempts to approximate the relationship between SNCR system efficiency and the flue gas temperature. The approximation was performed on the basis of literature data and verified using data from an experiment. Measurements were performed in a Polish boiler with a maximum continuous rating of 230 t/h. The verified, evaluated function could be used to forecast efficiency of SNCR systems in existing units that use urea or ammonia as a reagent. The approximation results are polynomial functions that depend on flue gas temperature, which fit the literature data with the coefficient of determination R² = 0.83-0.86. Therefore, these equations could be used by the designer or operator of the boiler for preliminary determination of current SNCR system efficiency.