Rotary reducing kiln seal

Abstract

A seal is disclosed between a stationary hood and an end of a rotary kiln enclosed thereby to prevent entrance of atmospheric air or the exit of process gas. The seal includes a first annular seal ring on a flange to rotate with the kiln, and a second and nonrotating annular seal ring mounted on an axially movable cylinder arranged around the kiln. The cylinder is part of a movable assembly that also cooperates with the kiln flange to define an annular chamber encompassing both seal rings and which is filled with a pressurized gas to prevent leakage between the rings. A thin annular flexible diaphragm around the kiln is circumferentially sealed on one end to the hood and on the other end to the movable cylinder. The diaphragm is sufficiently flexible to allow the cylinder and attached seal ring to move axially, as the kiln expands, to maintain an effective seal. A biased linkage pushes the two seal rings relatively together while thermal expansion of the kiln causes the diaphragm to fold and contraction causes the diaphragm to unfold. The diaphragm is shielded from high temperature kiln gases by an annular flexible wiper that projects inwardly of the movable cylinder to engage a stationary cylinder secured to the hood; and this wiper along with the diaphragm, hood and the stationary cylinder define a chamber filled with relatively cool pressurized gas to cool the diaphragm and resist leakage of high temperature kiln gas into the chamber defined in part by the flexible diaphragm.