Observations on Waste Destruction in Liquid Injection Incinerators

Abstract

Various factors affecting the performance of a subscale liquid injection incinerator simulator are discussed. The mechanisms by which waste escapes incineration within the spray flame are investigated for variations in atomization quality, flame stoichiometry. and the initial waste concentration in the feed. A turbulent spray flame reactor is fired on No.2 fuel oil which is doped with an equimolar mixture of various compounds. including chloroform, chIoro benzene, acrylonitrile, benzene, and I, I, I-trichloroeth-ane, In spite of the fact that the compounds all are initially at the same concentration, certain operating conditions repeatedly yield a consistent ranking in the extent of compound destruction. This "destructability" ranking is an important tool in identifying the mechanisms responsible for compound release. In the present work we identify two mechanisms as potential explanations for the compound release behaviour. The findings are applied to the problem of using CO and unburned hydrocarbon emissions as indirect indicators of waste destruction performance. The results also offer insight into the correlation between waste destruction efficiency and initial waste concentration in the feed that has been observed in field data.

Assessment of Atomization Quality with Respect to Burnout for the Incineration of Organically Contaminated Waste Waters

“…This source of emissions is important for liquid wastes which contain thermally very stable species, e.g., benzene or chlorobenzene (Taylor et al, 1990;Caroll et al, 1992). In case of poor mixing, cold and/or fuel rich coherent eddys (i.e., parcels) can prevent complete burnout (Seeker, 1990;Kramlich, 1990). In cold parcels slow reaction kinetics allows only partial oxidation of the fuel, and in fuel rich parcels unburnt hydrocarbons (HC) and carbon monoxide (CO) can persist even if thermochemical equilibrium is reached.…”

“…In case of poor atomization large droplets can escape the flame and must evaporate and be oxidized in the burnout zone. If temperatures are low, for instance due to heat extraction or a small heat of combustion, the available residence time in the burnout zone might be too short for complete evaporation and subsequent oxidation of the hydrocarbons and carbon monoxide (Kramlich, 1990;Mulholland et al, 1991). Oxidation kinetics limit burnout at temperatures below approximately 900°C (depending on composition and available residence time) due to the exponential dependence of reaction rates on temperature.…”