| OCR Text |
Show experimentation. Incineration is carried out with a hydrocarbon fuel. One can therefore expect that many of the usual combustion byproducts will be partially fluorinated. Although the health effects of many of the possible effluents are unknown, some knowledge of the nature and quantities formed would certainly be useful. Evidence that this may be an important issue is provided by the toxicity of perfluoroisobutene. This is major product derived from the high temperature pyrolysis of perfluoroethylene8• Perfluoroethylene may well be an important product from the incomplete combustion of many highly fluorinated compounds. Interestingly, other unsaturated compounds such as perfluorinated propene and butene-2 do not appear to be particularly toxic. However for perfluoroisobutene the proposed exposure limit is 10 ppb9 • The paper will begin with a general discussion on the incineration of organIc compounds. The wide variety of conditions that can be encountered will be emphasized. This will be followed by a section on the high temperature thermodynamic and chemical kinetic properties of fluorinated organic compounds that are pertinent to their destruction. Particular attention will be focussed on the differences and similarities with their hydrocarbon and chlorinated analogs. A subsequent section will contain some results of simulations and is indicative of the information that is now obtainable and which can serve as guide for tests to validate incinerator behavior. INCINERATION Under the ideal conditions of a uniformly mixed sample of waste, fuel and oxidant with an appropriate stoichiometry, temperature and residence time, most organic compounds can be destroyed to whatever level that is desired and with no formation of products except that dictated by thermodynamics. For fluorinated compounds this means CO2, H20 and HF. This is in also in accord with kinetic considerations, although for perfluoromethane the decomposition parameters leads to such small rate constants that it would appear that decomposition may only occur in the flame zone. Failure to achieve such results is usually due to difficulties in attaining ideal situations in the operation of real systems. The physical picture is that of a stream of waste that is gradually being mixed with fuel 3 |
