Pyrolysis And Oxidation Of Suflur Mustard Simulants
The r eaction kinetics of diethyl sulfide (C 2H5 -S-C2H5 ) and ethyl methyl sulfide (C2H5 -S-CH3), simulants for the chemical warfare agent, sulfur mustard (ClC 2H4 -SC2H4Cl), was studied at high temperatures under highly diluted conditions. This work has been undertaken with the goals to understand the destruction of sulfur mustard simulants at early stages and explore routes relevant to emissions under off -design incineration modes, such as fuel rich conditions due to inhomogeneous mixing. The studies were conducted in an atmospheric pressure, turbulent flow reactor with a Reynolds number of approximately 5000, at four different operating temperatures between 630 [MASCULINE ORDINAL INDICATOR] and 740 [MASCULINE ORDINAL INDICATOR] These experiments, with an initial loading of the C C. simulants of 150/100 ppm, involved either a nitrogen carrier gas for pyrolysis experiments or a nitrogen- oxygen carrier gas (including approximately stoichiometric conditions and fuel -lean conditions with an equivalence ratio of approximately 0.1) for oxidation experiments. On -line, extractive sampling in conjunction with analysis by fourier transform infra -red (FT -IR) spectrometry and gas chromatography/mass spectrometry (GC/MS) was performed to quantify species composition at four specific locations along the centerline of the turbulent flow reactor. Species concentrations were represented as a function of residence time in the reactor. For the pyrolysis of diethyl sulfide, a destruction efficiency of 70% was observed for the 740 [MASCULINE ORDINAL INDICATOR] operating condition at a residence time of 0.06 second. Ethyl ene, C ethane, and methane were detected at significant levels. In the oxidation experiments, the destruction of diethyl sulfide was significantly enhanced. Complete destruction was observed in the 740 [MASCULINE ORDINAL INDICATOR] operating condition at a residence time of 0.06 secon d C with low O2 loading and in the 740 [MASCULINE ORDINAL INDICATOR] operating condition at a residence time of 0.03 C second with high O 2 loading. Carbon monoxide, carbon dioxide, formaldehyde as well as the pyrolysis product species, were detected in the oxidation experiments. The experimental investigations of diethyl sulfide were complemented by mechanism development along with thermochemical properties. The present model of H-C-S-O system consists of approximately 1000 elementary reactions among 300 species. Mechanism predictions reproduced the experimental results satisfactorily. Rate of production analysis under several conditions in the present work showed that the initiation of diethyl sulfide destruction is through unimolecular dissociation via C S bond cleavage. Once the radical pool is established, hydrogen abstraction becomes primary destruction routes. [beta] -scission of the derived radicals forms thioaldehydes and subsequent multi -hydrogen abstractions and [beta] -scissions convert thioaldehydes to sulfur dioxide. Sensitivity analysis indicated that the reactions, having important effects on radical pools, to which mechanism predictions are the most sensitive. Destruction of ethyl methyl sulfide was observed to be significantly slower than that of diethyl sulfide under the same conditi ons as those for diethyl sulfide and similar products were experimentally observed as those from diethyl sulfide. The kinetic mechanism is still under development. The formation of the products was explained by a scheme by analogy to that of diethyl sulfid e. Significantly slower rates of pyrolysis of ethyl methyl sulfide were explained by the different destruction efficiencies including lower hydrogen abstraction rates, and lower hydrogen atom production as a result of thermal decomposition pathways.
Gouldin, Frederick Caskey; Davis, Harry Floyd
Ph.D. of Mechanical Engineering
Doctor of Philosophy
dissertation or thesis