Abstract

Selective Non-Catalytic Reduction (SNCR) of oxides of nitrogen (NOx) was studied experimentally by injecting different concentrations of aqueous urea solution in a pilot-scale Bio-fuel fired tunnel furnace at 3-4 % excess oxygen level and with low ppm of baseline NO_x ranging from 65 to 75 ppm within the investigated temperature range. The furnace simulated small-scale combustion systems where the operating temperatures are usually in the range of about 973 to 1323 K and NO_x emission level remains below 100 ppm. NO_x reductions were studied with the variation of different parameters such as injection temperature, residence time, Normalized Stoichiometric Ratio (NSR) of the reagent, carrier gas pressure, etc. A significant amount of NO_x reduction was achieved which was not pronounced by the previous researchers with urea SNCR for this low ppm of NO_x. With 5% plain urea solution, at an NSR of 4 as much as 54% reduction was achieved at 1128 K, whilst in the additive case the NO_x reduction was improved to as much as 69% at 1093 K.

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