SOLID-WASTE INCINERATION IN ROTARY KILNS

Rotary kilns are used to dispose of many solid wastes and sludges and to thermally treat contaminated soils. In this communication the fates of hydrocarbon and metal species are examined with a view toward opti mization of new kiln designs and maximizing existing unit throughout w hile minimizing pollutant emissions. Initially, process fundamentals a re considered to characterize the controlling phenomena. Pilot- and la rge-scale data are then examined to define practical system complexiti es. Finally, techniques for data scale-up and performance prediction a re summarized. Temperature is clearly the most important parameter wit h respect to the fate of both metal and hydrocarbon species; hence, he at transfer is often rate limiting. High temperatures favor hydrocarbo n evolution, but can also enhance the formation of toxic metal fumes. Both the solid composition and the moisture content can significantly influence the time at temperature required for hydrocarbon destruction and metal vaporization. Improving bed mixing helps contaminant releas e but can also aggravate puffing tendencies with batch charging. Full- scale performance predictions currently require a combination of small scale data and computer modeling. Future work needs to focus on verif ication of large-scale predictions for complex mixtures and sludges so that expensive trial burns can be minimized.