US3802831A

US3802831A - Rotary kiln chain hanger

Info

Publication number: US3802831A
Application number: US00344533A
Authority: US
Inventors: J Woodward
Original assignee: Southwestern Portland Cement Co
Current assignee: Southwestern Portland Cement Co
Priority date: 1973-03-26
Filing date: 1973-03-26
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

An improved hanger for supporting a heat exchange chain in a rotary kiln and a method of connecting the chain thereto in a manner effective to prolong the service life of the chain by automatically and incrementally rotating the supporting end link about its own axis during a revolution of the kiln thereby to avoid concentrated wear of the link and premature failure.

Description

United States Patent Woodward Apr. 9, 1974 [54] ROTARY KILN CHAIN HANGER 1,910,873 5/1933 Zahn 432/l I8 [75] Inventor: Jackson H. Woodward, Apple Valley Cahf' Primary Examiner-John J. Camby [73] Assignee: Southwestern Portland Cement Attorney, 8 83 an Brace Company, Los Angeles, Calif.

[22] Filed: Mar. 26, 1973 211 App]. No.: 344,533 [57] ABSTRACT An improved hanger for supporting a heat exchange [52] US. Cl. 432/28, 432/1 18 hain in a rotary kiln and a method of connecting the [5 l Int. Cl. chain [hereto in a manner effective to prolong the er- Field Of Search l vice life of the chain by automatically and incremen- 86 tally rotating the supporting end link about its own axis during a revolution of the kiln thereby to avoid References Cited concentrated wear of the link and premature failure.

UNITED STATES PATENTS 3,526,394 9/1970 Howell, Jr 432/I18 7 Claims, 3 Drawing Figures ROTARY KILN CHAIN HANGER This invention relates to a heat exchange chain for use in a rotary kiln, and more particularly to an improved hanger for connecting the end link of such a chain to the sidewall of the kiln.

It has long been common practice to equip rotary kilns, as for example of the type employed to manufacture cement clinker, with a multiplicity of heat exchange chains distributed about the entire inner periphery of the kiln at close intervals therealong. In this manner there is provided curtains of such chains major portions of which become embedded in the mass of raw material being converted to clinker after being heated by the hot gasses passing along the interior of the kiln. This provides very effective means for transfering the heat from the heated links into the mass of material as the latter is tumbled back upon itself along the power portion of the kiln during kiln rotation.

Those skilled in this art are aware of the long stand-- ing problem associated with the use of such chains and the fact that one or more links at the end of the chain attached to the kiln wall fail prematurely and long prior to the failure of the remaining links of the chain. In consequence, it has been necessary to take kilns out of operation for costly reconditioning and replacement of worn chains. This is a very costly and time consuming operation.

The foregoing and other shortcomings characteristic of the operation of rotary kilns over many decades, are circumvented by the present invention and the service life of the heat exchange chains is greatly prolonged. This is accomplished by an improved chain-hanger having an overall length at least as great, and preferably somewhat greater, than the thickest encrustation of raw material which collects over a period of time on the interior of the kiln before shutdown is necessary. Desirably but not necessarily, the hanger is constructed with an eyelet at either end with one eyelet used to pivotally support the hanger on the kiln wall and the other being interlinked with the end link of the chain. At least the latter of these eyelets is designed to support the adjacent end link of the chain in a plane extending transversely of the kiln. This mode of support permits and facilitates rotation of the end link about its own axis while major portions of the chain are submerged in the material undergoing treatment while shifting the point of contact between the end link and the hanger eyelet.

Accordingly it is a primary object of the presentinvention to provide an improved hanger for use in a rotary kiln to secure one end of a heat exchange chain to the kiln wall.

Another object of the invention is the provision of a kiln heat exchange chain hanger automatically providing for incremental rotation of the chain link interlinked therewith about the link axis during revolution of the kiln.

Another object of the invention is the provision of an improved method of suspending a heat exchange chain in a rotary kiln to increase the service life thereof and to promote the periodic incremental rotationof the link about its own axis.

Another object of the invention is the provision of an improved heat exchange chain hanger having provision for servicing the chain without need for digging into or removing any portion of the encrustation commonly accumulating on the inner sidewall of the kiln.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is a cross-sectional partly diagrammatic view through a rotary kiln having an illustrative embodiment of the invention hanger installed therein;

FIG. 2 is a fragmentary cross-sectional view on an enlarged scale taken along line 2-2 on FIG. 1; and

FIG. 3 is a fragmentary cross-sectional view through an upper portion of the kiln wall after an encrustation layer of substantial thickness has collected thereon.

Referring initially more particularly to FIG. 1, there is shown a typical rotary kiln 10 supported on idler rollers 11 for rotation about a generally horizontal axis. The main body shell 12 of the kiln is lined with refractory l3 and is provided with brackets 15 (FIG. 2) to which channel-shaped anchor rings 16 are attached, as by bolts 17. Rings 16 are spaced at intervals, such as 12-18 inches, for a major interior length of the kiln beginning particularly at the entrance end. Rings 16 are utilized to support a curtain of the

heat exchange chains

20,20 each chain being suspended from an individual elongated hanger 21 secured to ring 16.

Chains 20 and hangers 21 are formed of high strength suitable heat and corrosion resistant material, such as stainless steel. Typically, the individual annular chain links 22 may have an internal diameter of three inches' and a cross-section of seveneighths inch whereas hangers 21 have an overall length of approximately 1 foot and a cross-sectional dimension of 1- /1. inches each supporting a chain 20 weighing lbs. or more. The chains as here shown have a length somewhat less than the internal diameter of the kiln. Usually the lower end of the outstretched fully suspended chain barely clears the raw material 23, such as that conventionally employed to make cement clinker in a cement kiln.

Referring to FIG. 2, it will be noted that hanger 21 has an eyelet 25 at one end interlinked with a bolt 26 passing through the flanges of ring 16. Eyelet 27 at the lower end of the hanger is generally U-shaped and supports an assembly bolt 28 passing through the end link 29 of chain 20.

To be noted isthe fact that eyelet 27 is disposed to support end link 29 in a plane extending crosswise of the kiln. This arrangement facilitates incremental rotation of link 29 about its own axis during periods when the chain is not under tension as, for example, while the kiln is rotating counterclockwise from its 7 oclock position to the 2 or 3 oclock position. During this period the chains in this portion of the kiln are submerged in the tumbling raw material while the latter is being carried up along the lower righthand quadrant to a position from which it tumbles inwardly and downwardly over the underlying material. While this is occuring, 7

links 29 of each chain are jostled and moved through small increments thereby changing the point of contact between the [.D. of the ring and the supporting area of eyelet 27, namely its point of contact with bolt 28.

In operation, fuel and air are introduced into one end of the kiln and utilized to subject the raw material to heat treatment. The very hot gasses produced by the burning fuel and air mixture passes along the interior of the kiln and through a series of curtains formed by a multiplicity of heat exchange chains 20 so as to heat the chains to a high temperature. As the kiln is rotated counterclockwise, these heated chains fall onto the raw material and are subsequently submerged therein by other raw material tumbling and gravitating downwardly from the lower right hand quadrant of the kiln. In this manner, the raw material is brought into intimate contact with a large mass of highly heated chains.

As the kiln continues in operation day after day,.an accumulation of encrusted portions of the raw material collects in a layer 30. This layer increases in depth from day to day until the mid-length of the hangers is embedded therein as is clearly shown in FIG. 3. The hangers eventually become immobilized but eyelet 27 at the lower end remains exposed as doesthe uppermost link 29 of each of the chains 20. At all times, the end links of non-tensioned chains are free to rotate and shift position with each revolution of the kiln. This action distributes the worn zones and as well as the areas in which the temperature reaches a maximum between the chain and the hanger. In consequence, not only is the service life of the chain and particularly that of the end links 29 greatly extended, but should it become necessary for any reason to interrupt operation of the kiln for inspection or for repair ,or damage to the ceramic lining, the connector bolts 28 between the chains and hangers 21 are fully exposed and readily accessible for replacement of any chain. Thus, it is unnecessary to chip away any portion of the encrustation 30 to disconnect any one of the chains or to install a new one on any hanger which should be found without a heat exchange chain.

While the particular rotary kiln chain hanger herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodimentof the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.

I claim:

1. That improvement in a hanger for securing a heat exchange chain to a rotary kiln which comprises, a chain of interlinked annular metal links, elongated hanger means for securing one end of said chain to the interior sidewalls of a rotary kiln, said hanger means having a length adapted to be in excess of the thickness of an encrusted layer of the material undergoing treatment in the kiln and permitted to accumulate thereon, and means loosely connecting the end link of said chain to the inner free end of said hanger means in such manner that said end link is free and tends to rotate through a short arc as the kiln rotates about its own longitudinal axis thereby to shift the area of contact between the free end of said hanger means and the end link of said chain.

2. That improvement defined in claim 1 characterized in that said elongated hanger means includes eyelet means at either end thereof, one of said eyelet means being interlinked with the end link of said chain and the other of said eyelet means being interlinked with bracket means secured to the interior of said rotary kiln.

3. That improvement defined in claim 2 characterized in that one of said eyelet means includes removable fastener means extending transversely of the end of said hanger means.

4. That improvement as defined in claim 1 characterized in that said chain end link lies in a plane substantially normal to the rotational axis of said kiln whereby said end link tends to rotate in small increments about its own axis as the kiln rotates.

5. That improvement as defined in claim 1 characterized in that said hanger means includes eyelet means at each end thereof each including pivot pin means lying parallel to one another and to the rotary axis of said kiln and supporting said hanger means and said chain for pivotal movement in a common plane generally normal to the kiln axis of rotation.

6. That method of assuring incremental rotation of the suspension end link of a rotary kiln heat exchange chain about the axis of said end link despite the accumulation of encrustation on the interior of the kiln wall which method comprises, utilizing a chain having a substantially annular end link, int'erlinking said substantially annular end link of said chain to the eyelet at the free end ofa long hanger means with said end link lying in a plane generally normal to the rotary axis of the kiln, utilizing hanger means having a length such that its innermost end will lie inwardly of the thickest encrustation of clinker permitted to collect on the interior of the kiln before being removed, and supporting the other end of said hanger means from the interior of the kiln sidewall.

7. That method of prolonging the service life of a heat exchange chain in a rotary kiln which comprises connecting the annular end link of said chain to the interior of a rotary kiln by interlinking said end link in an eyelet at the inner end of a chain hanger secured to and projecting inwardly from the sidewall of the kiln for a distance in excess of the radial thickness of a clinker layer permitted to collect and with the plane of said eyelet lying generally parallel to the rotational axis of said kiln whereby said end link tends to rotate in small increments about its own axis during one revolution of the kiln.

met es

Claims

1. That improvement in a hanger for securing a heat exchange chain to a rotary kiln which comprises, a chain of interlinked annular metal links, enlongated hanger means for securing one end of said chain to the interior sidewalls of a rotary kiln, said hanger means having a length adapted to be in excess of the thickness of an encrusted layer of the material undergoing treatment in the kiln and permitted to accumulate thereon, and means loosely connecting the end link of said chain to the inner free end of said hanger means in such manner that said end link is free and tends to rotate through a short arc as the kiln rotates about its own longitudinal axis thereby to shift the area of contact between the free end of said hanger means and means end link of said chain.

6. That method of assuring incremental rotation of the suspension end link of a rotary kiln heat exchange chain about the axis of said end link despite the accumulation of encrustation on the interior of the kiln Wall which method comprises, utilizing a chain having a substantially annular end link, interlinking said substantially annular end link of said chain to the eyelet at the free end of a long hanger means with said end link lying in a plane generally normal to the rotary axis of the kiln, utilizing hanger means having a length such that its innermost end will lie inwardly of the thickest encrustation of clinker permitted to collect on the interior of the kiln before being removed, and supporting the other end of said hanger means from the interior of the kiln sidewall.