Rotary reducing kiln seal

In a generally horizontal rotary mineral reducing kiln having a stationary hood surrounding one end of the kiln, a sealing assembly for preventing the passage of gas through an annular clearance space between the hood and the kiln, the sealing assembly comprising:

• a. an annular flange secured to and extending radially outward from the kiln and axially spaced from the hood;
• b. a first annular seal ring secured concentrically on the flange to rotate with the flange and the kiln;
• c. an axially movable assembly comprising a cylinder spaced around the kiln between the hood and the first seal ring, a second annular seal ring concentrically connected to an end of the movable cylinder for engagement with the first seal ring, wall means connected to the movable cylinder are arranged with a portion thereof radially outward of the seal rings for cooperating with the annular flange on the kiln to define an annular chamber encompassing the first and second seal rings, and gas delivery means connected to the annular chamber for introducing pressurized purge gas into the annular chamber to prevent leakage of other gas between the first and second seal rings;
• d. an annular flexible diaphragm spaced around the kiln with an axial end thereof adjacent the cylinder of the floating assembly being circumferentially connected thereto in gas sealing relation, and an opposite end adjacent the hood being circumferentially connected to the hood in gas sealing relation;
• e. means engaging the movable assembly and biased to push the movable assembly toward the annular flange on the kiln and maintain the second seal ring in engagement with the first seal ring;
• whereby upon thermal expansion of the kiln the flange and first seal ring will push the movable assembly to fold the flexible diaphragm, upon contraction of the kiln the biased means will push the movable assembly to expand the flexible diaphragm and toward the first seal ring, and with an effective seal being thereby maintained under variable operating conditions;
• f. a cylindrical guide member which is circumferentially connected to the hood substantially concentric to the kiln and projects at least in part into an annular space between the outer periphery of the kiln and the inner periphery of the cylinder of the movable assembly;
• and
• g. an annular flexible wiper which is circumferentially connected to the movable cylinder and projects radially inward thereof into engagement with the other periphery of the cylindrical guide member to shield the flexible diaphragm from high temperature gases within the kiln.