1 October 1997
(b) Once inside the chamber, the material is slowly tumbled by the rotating action at a
rate of 0.75 to 2.50 rpm. Material is destroyed as it moves along the length of the drum, which has
a nominal length-to-diameter ratio of 2:1 to 5:1. Typically, the supplemental heat burner in the
primary chamber provides much of the heat required to destroy the waste. Residence time in the
chamber is changed by adjusting the angle (tilt of the horizontal axis) of the cylinder.
(2) Secondary Combustion. Residue ash tumbles off the kiln into the ash-collection pit in
the secondary chamber. Combustion gases pass through the secondary chambers in the same
manner as the fixed-hearth retort furnace.
(3) Capacity. Typical capacity for packaged rotary kilns is less than that for packaged retort
furnaces of the same physical size.
c. Modular Rotary Kiln.
(1) The rotary kiln incinerator size of interest to military bases is often a two-package, large-
scale, modularized version of the packaged incinerator. One package or module is the rotating
cylinder primary combustion chamber and its associated charging system. The second package is
the stationary secondary chamber unit described above. The modular rotary kilns may differ in
configuration and provide greater capacity than packaged rotary kilns; however, they operate in the
same manner at capacities up to 5000 lb/h. Seldom are these units operated in multiple-unit
facilities. Figure 4-4 illustrates a typical modular rotary kiln unit with heat recovery.
(2) Large-scale, multiple-module, rotary kiln systems, using individual truck-trailer mounted
modules for each subsystem, are used extensively for decontaminating soils and for destroying
large batches of difficult to burn wastes. Throughput for such modular systems is usually less than
d. Field Erected Rotary Chamber Systems.
(1) Application. Large-scale rotary kilns have been used for the routine destruction of
municipal-type wastes. Rotary kilns generate larger amounts of particulate when burning municipal.
(2) Field-Erected Incinerator Systems Incorporating Rotary Chambers. Several incinerator
manufacturers use rotary chambers in place of moving grates in the primary combustion sections of
(a) Volund System. The Volund incinerator uses a refractory-lined rotary kiln in the final
two stages of primary combustion. Two moving grates are used for the drying and initial
volatilization /combustion stage. The partially burned material is then moved into the rotary kiln for
completion of primary combustion and final burndown of the char. Gases, vapors, and particulates
generated upstream of the kiln are partially burned in the kiln, and final destruction is completed in
the secondary combustion chamber/boiler section. All other aspects of the incinerator and its
operation are similar to other field-erected, furnace-type incinerators.
(b) O'Connor-Westinghouse System. This system uses an all-steel-pipe, inclined,
rotary-cylinder, primary-combustion chamber. Water-filled pipes make up the rotating, inclined,
horizontal, cylindrical chamber. The pipes are spaced and attached in a manner that allows primary