Influence of the Oxide gas on thermal decomposing explosion of methyl nitrite based on instantaneous flame characterization

The decomposing explosion behavior and characteristics of methyl nitrite (MN) were investigated by analyzing the instantaneous flame of MN decomposition explosion in this work. The lowest explosion limit of MN decreases with the addition of nitric oxide, nitrous oxide and oxygen. The ternary diagrams of the explosive range for “methyl nitrite/nitrogen/oxide gas” mixtures at 40℃ and 100 kPa were acquired. The transient explosion process was characterized by high-speed video image and emission spectrum at 40℃ and 40 kPa. The results demonstrate that the decomposing explosion mainly includes dehydrogenation and oxidation of the carbonaceous species, reduction of nitric oxide and conversion of the OH radical, which can be divided into two reaction stages. The first stage is transient and lasts less than 50 ms, basically involving the generation of nitric oxide, methanol and formaldehyde, and most reactions of dehydrogenation and nitric oxide reduction. The second stage lasts more than 300 ms, and develops from the cool flame to the yellow flame, mainly involving the combustion reactions of hydrogen and carbon monoxide with the OH radical. The type and concentration of oxide gases affect the generation of key species HNO and OH radicals which in turn have an important impact on the evolution of the explosion.