Effects of H₂O Dilution on NO_x Emissions of Methane-Added Ammonia Oxidation

Abstract

For the NH 3 /CH 4 combustion in a furnace, the reactant jets entrain the combustion products containing H 2 O, and the combustion occurs with H 2 O dilution. Previous literature indicates that the effect of H 2 O on NO x emissions from NH 3 /CH 4 oxidation is significant. This study systematically compares the oxidation of NH 3 / CH 4 using a jet-stirred reactor (JSR) with N 2 and H 2 O dilution. The impacts of temperature (T), equivalence ratio (Φ), H 2 O volume fraction (X Hd 2 O ), and the CH 4 /NH 3 ratio (by volume) are experimentally and numerically investigated. The NO generation is enhanced as the T or CH 4 /NH 3 ratio elevates, while it is hindered with higher Φ or X Hd 2 O . The concentration of N 2 O is comparable to NO concentration with T < 1375 K. At X Hd 2 O = 20%, the maximum N 2 O concentration is observed when T = 1325 K, Φ = 0.5, and CH 4 /NH 3 ratio = 0.33. The presence of 20% H 2 O leads to a reduction of 54.6% in NO and 47.3% in CO at T = 1375 K and Φ = 0.9. To minimize the NO x formation and NH 3 slip, the suggested conditions for NH 3 /CH 4 oxidation are identified. The presence of H 2 O significantly influences NO x formation in NH 3 /CH 4 oxidation, and this work provides new insights into NH 3 /CH 4 oxidation in the dilution of H 2 O.