EXPERIMENTAL AND NUMERICAL-STUDIES OF PIC FORMATION DURING CHLOROCARBON COMBUSTION - DEVELOPMENT OF A FAILURE MODE DIAGNOSTIC SYSTEM FOR HAZARDOUS-WASTE INCINERATORS

The major concern regarding organic emissions from hazardous waste inc ineration systems is the formation of products of incomplete combustio n (PICs). Previous studies have shed light on the mechanisms of format ion and emission of PICs, showing that the formation of these by-produ cts is highly dependent upon the local ratio of fuel and oxidant, and that their amount and composition are sensitive to both turbulent mixi ng and chemical kinetic constraints. PIC emissions are closely related to the fluctuations in mixture ratio that result from the turbulent m ixing process. Experimental and modeling studies are carried out in or der to develop a fault diagnostic system for commercial hazardous wast e combustors. The experimental facility has been designed to investiga te the effects of both mixing and chemical kinetics on product formati on. It consists of a Toroidal Jet-Stirred Combustor (TJSC) followed by a Plug Flow Reactor (PFR). An injector positioned at the PFR entrance allows one to inject a selected species directly into the PFR. A mixt ure of hydrocarbons and chlorocarbons is used as a hazardous waste sur rogate. Benzene is injected into the PFR in order to investigate the c ombined effects of turbulent mixing and chemical kinetic inhibition on PIC emissions. The development of the fault diagnostics is approached by establishing a relationship between the PIC speciation measured in the exhaust and the kinetic and/or mixing failure mode that has led t o the emissions. Finally, a numerical simulation of the turbulent reac ting flow is attempted by incorporating a highly simplified reaction m echanism in a commercial CFD code. Results for injection of benzene in to the PFR are compared to experimental data.