The paper describes mechanisms coverning transients from the batch incineration of liquid wastes in rotary kilns. When containerized liquid wastes, bound on sorbents, are introduced into a rotary kiln in a batch mode, transient phenomena involving heat transfer into, and waste mass transfer out of, the sorbent can promote the rapid release of waste vapor into the kiln environment. This rapid vapor release can deplete and displace excess oxygen from the primary flame, and form a puff, which can result in temporary failure of the incinerator. Parametric studies on a specially designed rotary kiln incinerator simulator showed that puffs are very easily generated even with small quantities of wastes and at excess air values exceeding 100%. Furthrmore, their magnitudes and intensities increase with increasing kiln tempere and rotation speed. A theoretical model describing simultaneous heat and mass transfer into a sorbent aggregate, coupled with vapor-pressure-driven waste vaporization within the sorbent aggregate, was combined with a fragmentation model and was able qualitatively to predict experimentally observed effects relating to puff duration, kiln rotation speed and temperature, and stoichiometric oxygen requirement of the waste. The model was extrapolated to conditions beyond the experimental test matrix.