US 3526394 A
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Sept. 1, 1970 H. D. HOWELL, JR
INSERT BEARINGS FOR KILN CHAIN BRACKETS Filed Sept. 18, 1968 m l/ A/To/e HAPPY 0. Hon/544,12
United States Patent O 3,526,394 INSERT BEARINGS FOR KILN CHAIN BRACKETS Harry D. Howell, Jr., Colton, Calif., assignor to Hanford Foundry Co., San Bernardino, Calif., a corporation of California Filed Sept. 18, 1968, Ser. No. 760,425 Int. Cl. F27b 7/00 US. Cl. 263-33 4 Claims ABSTRACT OF THE DISCLOSURE A non-rotatable easily renewable insert bushing in a supporting bracket for chain-holding shackles in a cement kiln, made of wear-resisting high temperature resisting alloy to insure long service life corresponding to the long service life of a cement kiln, or for easy renewal if the kiln is temporarily shut down for quick repair.
BACKGROUND OF THE INVENTION In the operation of elongated rotary kilns for heating, for example, component mixtures of portland cement, either in the wet process or in the dry process, heated gases are passed through the rotary kiln counter-currently to the flow of the mixture. Chlrtains of hanging chains have heretofore been used to serve principally as heat exchanger means, the hanging chains being heated by the passing hot gases in the upper portion of the kiln, and transferring their heat to the mass of mixture in the bottom portion of the kiln where a succession of collapsed chain units are dragged through the mixture. The chains also perform a mixing and turbulizing function in the cement mixture. A succession of chain curtains is provided throughout a selected temperature zone in the kiln, prior to the sintering zone, this temperature zone being usually in the range from about 1000 to 1800 F.
The chains are usually in length about three-fourths of the inside diameter of the lined kiln, and are mounted on a metal ring bracket welded to the inside of the shell and extending inwardly through the refractory lining. Holes are provided in the edge of the bracket adjacent the refractory lining, shackles and bolts being used to fasten the chain ends to the brackets. The brackets are preferably segmental instead of a full circle, to facilitate repairs. The present invention relates to the means for attachment of the chain ends to the brackets.
SUMMARY One object of the invention is to provide means for increasing the life of the brackets on which kiln chains are mounted. Another object is to provide replaceable wear-resistant insert sleeve bearings in the holes in the brackets on which kiln chains are mounted. Another object is to provide an assembly of heatand wear-resistant alloy steel brackets, bracket insert bearings, shackles and shackle pins upon which heat transferring chains in a rotary kiln are mounted.
BRIEF DESCRIPTION OF THE DRAWINGS These and other objects are attained by my invention which will be understood from the following description, reference being made to the accompanying drawings in which:
FIG. 1 is a vertical cross-sectional view of a rotary cement kiln showing in elevation the ring supporting bracket and representative chains;
FIG. 2 is an enlarged segment of the bracket as mounted inside the kiln shell;
FIG. 3 is an enlarged cross-sectional view taken on the line 33 of FIG. 2;
3,526,394 Patented Sept. 1, 1970 DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, a rotary kiln 11 has a steel shell 12 within which is a refractory lining 13. Segmental brackets 14 are attached by welding 15 to the inside surface of the shell, in circles. A plurality of circles is provided for the suspension of a large number of curtains of chains 16 constituting an efiective heat exchanger in which the hot gas of the kiln passes through the chain curtains to heat the chains, the heat being then conducted to the mass of powder in the bottom of the kiln by the collapsed chains as they are dragged through the mass of powder, as the kiln slowly rotates.
The steel segmental brackets 14 are of radial length to extend beyond the inner surface of the refractory lining 13, and each segment is provided with a hole or holes 17 in which a removable bearing may be inserted. The removable bearing is preferably in two end-to-end halfmembers 18 and 19 which are inserted from the two sides of the bracket 14. Integral segment keys 21 on the bushings are provided, and these engage the key slots 20 in the bracket and prevent the rotational movement of the bushings.
The half bearing inserts 18 and 19 are held in the hole 17 by the U-shaped shackle 25, which is provided on its legs 26 and 27 with bolt holes 28 which are adapted to receive the shackle bolt 29 having an integral head 30 on one end and a threaded nut 31 fitting on the threaded other end 32 of the bolt 29. The shackle bolt 29 in the assembly passes through the bearing inserts 18 and 19, holding the assembly together, the first or end link 33 of a chain 16 being loosely held on the curved portion 34 of the shackle.
The bearing insert halves 18 and 19 are readily replaced by removing the shackle bolt 29. Heretofore, the curved portions 34 of the shackles have been held in holes in the brackets with the first chain link on the bolt, and when the holes become worn through, the chains drop into the lower portion of the kiln and are discharged or become entangled with other chains and impede the heat transfer function of the chain system. It has been necessary, heretofore, to replace an entire bracket, or weld a repair piece onto the defective bracket. A long life without shutdowns and repairs results from the use of the replaceable insert bearing halves 18 and 19, which are cast from wear-resistant alloy steel (such as 25 percent chromium and 12 percent nickel alloy steel). The shackle bolts are also preferably :made of wear-resistant steel. The alloys for the shackle, the bearing inserts and the bolt may be selected to give the minimum amount of friction or galling, since these rubbing parts operate in the dry abrasive dust of the cement kiln. Cast steel alloy chain rings are also preferred because of their longer life when the alloy is selected for greatest heat and wear resistance. The brackets may also be made from cast alloy steel, to give improved life.
The objectives set forth in the beginning are attained by my invention.
1. In a heat transfer chain curtain structure for a rotary kiln, the combination comprising a key-hole apertured chain holding bracket, a pair of insert bearings having peripheral key members adapted to fit said key-hole aperture, a U-shaped shackle having legs disposed adjacent the outer ends of said insert bearings and having the end link of a length of chain engaged in the curved portion of said shackle, and a shackle-bolt rotatably mounted in said insert bearings and removably engaged with the ends of the legs of said shackle.
2. In a heat transfer chain curtain for a rotary kiln, the combination comprising an apertured chain holding bracket, an insert bearing non-rotatably mounted in the aperture of said bracket, a U-shaped shackle Whose legs engage the faces of said bracket adjacent said aperture and the ends of said bearing, and a shackle bolt in said bearing and engaging the legs of said shackle, said bolt being removable, all parts of the combination being made of cast alloy steel.
3. In a heat transfer chain curtain structure for a rotary kiln, the combination comprising a chain-holding bracket mounted on the inside surface of the kiln shell,
said bracket having an aperture therethrough including a key slot adapted to receive a removable insert hearing means, and
an insert bearing means engaged in said aperture, said bearing means having integral key means for preventing rotation of said bearing in said aperture.
4. The chain-holding bracket defined in claim 3, in which said bearing means consists of a pair of cylindrical bearing members having integral peripheral key means, said members being disposed in end-to-end relation in said bracket aperture.
References Cited UNITED STATES PATENTS 1,378,941 5/ 1921 Fahrenwald 5978 2,230,601 2/ 1941 Puerner et al. 3,441,301 4/1969 Cale 308-27 JOHN J. CAMBY, Primary Examiner U.S. Cl. X.R. 5978, 86; 30827