WASTE AND SORBENT PARAMETERS AFFECTING MECHANISMS OF TRANSIENT EMISSIONS FROM ROTARY KILN INCINERATION

When ''containerized'' liquid wastes, bound on sorbents, are introduce d into a rotary kiln in batch mode, transient phenomena involving heat transfer into, and waste mass transfer out of, the sorbent can promot e the rapid release of waste vapor into the kiln. This rapid vapor rel ease can cause depletion of available oxygen, and the formation of a ' 'puff'' which can result in a temporary failure of the incinerator sys tem. A systematic study has been completed examining the effect of was te and sorbent properties on the magnitudes of transient puffs in a la boratory scale rotary kiln simulator. Of primary importance were waste boiling point and waste stoichiometric oxygen requirement. Of seconda ry importance were sorbent parameters such as bulk void fraction, and the fraction of the adsorbed waste that was contained within the indiv idual sorbent particles. A theoretical model that utilizes a vaporizat ion/surface renewal approach can be used as a guide to explain experim ental results for several wastes on sawdust and corncob sorbents. Resi n sorbents, on the other hand, are extremely effective at controlling puffs because they appear to be able to bind the liquid waste tightly to the sorbent in such a way that it is not released by a vaporization process. This non-physical waste release process is not described by the current model. In general, the results suggest that the practice o f limiting containerized waste feed rates based on the heat of combust ion of a given container be modified to provide feed rate limitations based on the stoichiometric oxygen requirements and boiling point of w aste in a given container. This modified practice may enable container ized waste feed rates to be optimized, with a view to minimizing both the transient load on the afterburner and the transient emissions from the stack.