THERMAL-DESTRUCTION BEHAVIOR OF SELECTED WASTE COMPOUNDS UNDER SHORT-TIME, HIGH QUENCH RATE CONDITIONS

Emission of waste compounds and byproducts from thermal treatment syst ems is generally recognized to be due to limitations in the transport processes. A relatively small fraction of the feed material experience s an environment in which complete waste destruction cannot occur with in the time available. These environments involve low temperatures, sh ort times (i.e., high quench rates), oxygen-starved conditions, and po ssibly combinations of these. The research reported here examines wast e compound destruction under the short reaction times that are represe ntative of flame zone extinction processes. An externally fired stirre d reactor system is used to study the behavior of toluene, chlorobenze ne, 1,2-dichloroethane, 1,1,1-trichloroethane, and chloroform. Each of these is added to the reactor at a rate equivalent to a concentration of 10,000 ppm of carbon atoms. Major byproducts include the light par affin and olefin hydrocarbons and species that are specific to the ind ividual parent compounds. Tests also evaluated the influence of reacto r residence time and initial concentration on toluene behavior, and a published mechanism for toluene destruction was compared with the data . Additional tests focused on mixture effects (toluene and 1,1,1-trich loroethane fired together). At 1200-1350 K, 1,1,1-trichloroethane fire d alone results in no measurable emissions. In a mixture, however, the presence of toluene prevents the complete destruction of the more rea ctive 1,1,1-trichloroethane under these same conditions. Kinetic analy sis shows that the additional free radicals generated by the toluene a ct in a complex way to increase 1,1,1-trichloroethane concentrations i n the reactor, illustrating the difficulties encountered in predicting the behavior of complex waste mixtures.