The paper discusses a theoretical model which was designed to: (1) provide insight into why, for liquid wastes, 'puffs' are very easily generated, and why their magnitudes and intensities increase with increasing kiln temperature and speed of rotation; and (2) predict how the generation of puffs in general is controlled by waste properties, sorbent properties, and kiln operating parameters. When containerized liquid wastes, bound on sorbents, are introduced into a rotary kiln in a batch mode, transient phenomena involving vaporization of the waste, and mass and heat transfer into the sorbent can allow a rapid release of water vapor into the kiln environment, a displacement of excess oxygen from the primary flame, and formation of a puff. This transient puff then travels to the afterburner and, if it is too large, can result in a failure mode of the incinerator system. Previous experimental work has been performed by EPA on a specially designed rotary kiln incinerator simulator.