Impact of incinerator internal hydrodynamics on hazardous organic waste destruction efficiency

The results of a study concerning the influence of internal hydrodynamics o f incinerators on the principal organic hazardous constituents (POHCs) dest ruction efficiency are presented in this paper. A model of two tanks-in-ser ies is used to describe internal hydrodynamics of incinerators via residenc e time distributions (RTD). Two cases corresponding, respectively, to the p resence of a short-circuit and a deadwater zone within the internal flow ar e examined in detail. The results indicate that the incinerability ranking, based on plug-flow laboratory experiments for thermal stability determinat ion, is disrupted. Temperatures required to obtain a conversion rate of 99. 99% in a perturbed flow are higher. Simple relationships allow calculation of the temperature requirement deviation from the plug-flow case knowing th e kinetic parameters of the waste combustion and the characteristics of the reactor hydrodynamics. This study shows that the selection of compounds to be spiked in the waste feed of an incinerator during a trial burn should be coupled to a direct de termination of the residence time distribution of the incinerator itself fo r a proper selection of the compound that is more difficult to burn than an y other organic expected in the actual waste. Methane, chlorobenzene and methyl chloride, which are characterized by a hi gh stability whatever the species residence time distribution in the incine rator, are good candidates for trial burns. (C) 2000 Elsevier Science Ltd. All rights reserved.