Detection of NS at steady state concentration in the reaction zone of the combustion of methane doped with ammonia and a fuel sulfur such as HS suggests that NS may be an important reactive intermediate in burning of hydrocarbon flames in a reducing atmosphere, which is relevant to coal pyrolysis and combustion.
Fossil fuels contain bound nitrogen, which releases elevated levels of nitric oxide emissions during combustion. NO emissions can be controlled by denitrification of the fuel source, combustion chamber modification, or both. One developing technique is the reburning of NO, which is reduced to N. These fuels also contain variable amounts of sulfur, which is oxidized to SO. Therefore, understanding the reactivity of NO and SO is crucial to the process of reburning. The experimental apparatus to test this involved a primary flame for producing combustion products, which were mixed with NO and SO to mimic coal burning byproducts. This mixture was fed into the burner at atmospheric pressure. 1-2% decrease in NO concentration is observed at various percentages of total fuel inlet (reburn ratio) in the presence of 0.1% SO, which is attributed to the formation of HS, HS, and the resulting reaction with NO, giving rise to NS. Reaction: HS + NO > NS + OH.