A study of byproduct formation from 1,1,1-trichloroethane thermal destruction.

摘要

This work investigates combustion byproduct emissions from 1,1,1-trichloroethane (1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar}) during one potential hazardous waste incinerator failure mode, the penetration of waste droplets through the flame to the cooler post-flame region. Laboratory-scale experiments and chemical kinetic modeling assist in studying the byproducts formed, their formation and destruction pathways, their blending strategies, and their contribution to exhaust toxicity. An FTIR spectrometer measures species concentrations for 1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar} injected as a gas, a liquid, or a mixture with alkanes into the post-flame region of a turbulent combustion-driven reactor. 1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar} decomposes to form its equilibrium products CO{dollar}sb2{dollar} and HCl via the intermediates, 1,1-dichloroethylene (1,1-C{dollar}rmsb2Hsb2Clsb2{dollar}), phosgene (COCl{dollar}sb2{dollar}), acetylene (C{dollar}sb2{dollar}H{dollar}sb2{dollar}), and carbon monoxide (CO). A series of experiments confirms that COCl{dollar}sb2{dollar} is a product of gas-phase reactions and not a product of photolysis reactions, heterogenous wall reactions, or reactions of CO and Cl{dollar}sb2{dollar}. Injecting the 1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar} as a liquid spray or as a gaseous jet produces no significant differences in byproduct levels. The addition of the alkane additives, heptane and dodecane, to 1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar} produces two principal effects: an increase in C{dollar}rmsb2Hsb4{dollar}, C{dollar}rmsb2Hsb2{dollar} and CO levels for injection temperatures between 950 to 1040 K, and a decrease in 1,1-C{dollar}rmsb2Hsb2Clsb2{dollar}, COCl{dollar}sb2{dollar}, C{dollar}rmsb2Hsb2{dollar}, and CO levels for injection temperatures greater than 1050 K. The breakdown of the injected alkane causes the former effect; the additional heat of combustion of the alkane additives, released during the oxidation of CO, causes the later.; Combustion byproducts can make a significant contribution to exhaust toxicity, defined as the sum of all species concentrations weighted by their toxicity. Although 1,1,1-C{dollar}rmsb2Hsb3Clsb3{dollar} emissions decrease steadily with increasing reactor temperatures, the toxicity increases due to the formation of the carcinogen 1,1-C{dollar}rmsb2Hsb2Clsb2{dollar} and the acute toxin COCl{dollar}sb2{dollar}. Only the high temperature destruction of these intermediates reduces the exhaust toxicity.