US 3724887 A
An end seal for a rotary kiln having axial-reference centering means.
Description (OCR text may contain errors)
United States Patent 1191 Roberts 1451 Apr. 3, 1973 KILN SEAL  References Cited  Inventor: Edward S. Roberts, New York, NY. FOREIGN PATENTS OR APPLICATIONS [7 3] Assignee: Trea well Corpo tion, ew York, 1,201,999 1/1960 France ..263/32 NY. Filedl y 1971 Primary Examiner-John J. Camby  APPL No; 144,461 Attorney-Fannie, Edmonds, Morton, Taylor 8c Adams  US. Cl. ..287/l89.36, 34/242, 432/115  ABSTRACT  Int. Cl ..F27b 7/24 An end seal for a rotary kiln having axial-reference  Field of Search ..263/32 R, 33 R; 34/242 nterin means,
6 Claims, 2 Drawing Figures PATENTEUAPM r915 3.724 887 INVENTOR.
EDWARD S. ROBERTS g mg/jwam ATTORNEYS KILN SEAL BACKGROUND OF THE INVENTION Rotary kilns frequently require that an effective seal be maintained between stationary apparatus through which the kiln is fed or discharged and the rotating kiln itself. Such is necessary, for example, when an ap- I propriate atmosphere must be maintained within the kiln while the material therein is heated and processed.
Rotary kilns of this type may be extremely large, and may reach diameters of 15 feet or more and lengths of over 20 feet. Since the kiln end plate may be subject to considerable thermal expansion and contraction with consequent movement of the axis of rotation, sealing between the relatively moving parts becomes a difiicult problem. Various solutions have been proposed such as that of US. Pat. No. 1,460,764 involving the use of a stuffing box having resiliently biased packing rings or the use of a movable sealing ring proposed in US. Pat. No. 1,794,454. However, none of these seals solves in an entirely satisfactory manner, the complex problem of sealing large rotating kilns about an axis which is variable in position due to thermal expansion and contraction of the kiln.
It is the purpose of the present invention to provide a solution to this problem.
SUMMARY OF THE INVENTION In accordance with the present invention, an end seal for a rotary kiln comprises a first seal assembly or portion which is fixedly secured to and rotatable with the kiln inlet and a second seal assembly which is stationary with respect to the kiln and the rotary seal assembly. The stationary seal assembly has connected to it a plurality of rollers which support and center this seal assembly relative to the axis of the rotation of the kiln. Between the stationary and rotary portions of the seal is an annular seal element secured to the rotary portion of the seal and maintained in close sealing contact with the stationary portion of the seal by spring mounted shoe means.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation of a rotary kiln incorporating the seal of the present invention; and
FIG. 2 is a cross-section of essential parts of the seal of the present invention.
DESCRIPTION OF A PREFERRED EMBODIMENT With reference to the drawing and initially to FIG. 1 thereof, a rotary kiln incorporating the kiln seal of the invention has been illustrated. The kiln 10 is of the conventional cylindrical drum type having a refractory lining and internal gas-fired heating means (not shown). The kiln is supported at each end upon rollers 11 joumalled in trunnions 12, the rollers engaging circumferential ring supports 13. Rotation of the kiln 10 is accomplished by a motor 15 which drives the pinion l6 engaging a bull gear 17 secured to the kiln. Inlet and outlet housings 18 and 18 enclose respective feed and outlet transport mechanisms (not shown) for supplying the kiln with raw material and for withdrawing processed material therefrom. Seals 19 constructed according to the present invention are located about both the inlet and outlet of the kiln, the construction and function of which will now be described.
With reference to FIG. 2, a portion of an end plate 20 of the kiln 10 has been illustrated. The plate 20 is connected by suitable welding 20a to a generally cylindrical member 21 which defines the feed inlet opening to the kiln. The member 21 has its axis coincident with the axis of rotation of the kiln 10. Reinforcement 22 is secured to member 21 for strength and stiffening. Extending generally perpendicularly from the member 21 and welded thereto, is a large circular pate 23 (apertured for weight reduction) having an outer section 24 which has beveled machined edges 24a. This permits a plurality of centering rollers 26 having similarly inclined machined surfaces 26a to ride thereuponfor reasons which will be described.
A cylindrical member 27 extends outside and parallel to inlet member 21 and is welded at 27a to plate 23. Cylindrical member 27 is further secured to the end of inlet member 21 through intermediate support 28 by the welds shown at 28a. A seal mount 29 is welded to the cylinder 27. Secured to said seal mount by means of threaded studs 30, nuts 31 and washer 32 is a flat annular seal element 33. The seal element 33 is advantageously of a suitable longwearing, tough sheet material comprising fabric impregnated with teflon.
Thus far the elements described with exception of the roller 26 are rigidly secured to the inlet member 21 and rotate with the kiln.
The stationary portions of the seal will now be described. These include plate 36 which is connected by means of a flexible corrugated connection 36a or other flexible means in sealed relation to housing 18 for a feed mechanism (not shown). The plate 36 is fastened to an annular ring 38 by studs or bolts 39. Washer seal 40 prevents leakage between the plate 36 and ring 38. Another and opposing ring 41 extends radially outwardly and is slotted at 41a to receive the shaft 42a of roller 26, which is attached to slidable block mount 42b. Three such centering rollers 26 advantageously are provided equally spaced about the periphery of plate 23. The roller 26 can be adjusted radially by means of a screw 44 which is threaded through a nut 41b secured to the periphery of the ring 41 and which bears upon block 42b. Lock nut 47 prevents rotation of screw 44 once the positioning of the roller 26 has been made. The ring 41 is held against rotation (see FIG. 1) by an arm 48 engaging a stationary stop to prevent rotation of the ring 41 and of the elements connected thereto.
Intermediate the ring members 41 and 38 is an annular member 50 (U-shaped in cross-section) secured by studs or bolts 51 to ring 41 and by like studs or bolts (not shown) to ring 38, and maintained in sealing relation to members 38 and 41 by seals 53 and 54. Near their inner peripheries, the ring members 38 and 41 are provided with facing axially extruding flanges 38a and 41a which are grooved for receiving O-rings 55 and 56. These provide a seal between the members 38 and 41 and between two opposing shoes 57 and 58 which are urged toward each other and against the opposite faces of the seal 33 by springs 59 and 60. Oil under pressure may if desired be introduced into the annular space about the shoes 57, 58 through an inlet 61 to lubricate the seal and by its pressure on the shoes to aid in holding them against the seal element 33.
The invention further provides a wiper sealing element 62 secured to the ring 38 by studs and washer combination 62. The purpose of wiper element 62 is to prevent the dust from the housing 18 or kiln from penetrating into the interior of the seal. To further preclude such possibility, a positive gas pressure may be maintained within the seal by conducting a gas at above atmospheric pressure through the conduit 64 which opens to the interionof the seal at 64a.
The operation of the kiln seal is as follows: Each of the rollers 26 is first adjusted radially by setting screws 44 to bring rollers 26 into close contact with section 24 of plate 23. Thus, the stationary parts of the seal connected to ring41 are centered with respect to the kiln axis of rotation as determined by the circumference of section 24 which is a coincident reference extension of such axis.
The end wall 20 of the kiln may expand or contract due to thermal forces, thereby raising or lowering the axis of rotation of the kiln. However throughout such expansion and contraction the stationary portions of the seal 19, due to the interconnection through rollers 26 to the rotating portions, will continue to be centered with respect to the rotational axis of kiln 19. Effects of thermal expansion or contraction of the seal elements themselves are minimized, since both the stationary and rotating portions of the seal are connected directly or indirectly to the inlet member 21 which in turn is quite close to the rotational axis of the kiln. The seal elements are therefore divorced substantially from the large thermal expansion and contraction to which the kiln proper is subject.
It will be understood that the foregoing description has related to a particular embodiment of the invention and is therefore only representative. In order to appreciate fully the scope of the invention reference should be made to the appended claims.
What is claimed is:
l. A sea] for a rotary kiln having nozzle means defining an opening therein comprising a movable seal portion fixedly attached to said nozzle for rotation therewith, seal mounting means in said movable seal portion, a stationary seal portion, seal mounting means in said stationary portion, a seal element in sealing engagement with each mounting means, one of said seal mounting means permitting relative movement of said seal element between said rotating and stationary seal portions, and centering means comprising a circular plate connected to said rotation portion of the seal and extending perpendicular to the kiln axis, said stationary seal portion including a plurality of rollers contacting the periphery of said plate to transmit to said stationary seal portion radial movements of said rotating seal portion. 7
2. The seal according to claim 1 wherein said inlet nozzle is rigidly and perpendicularly secured to said rotating plate, said stationary seal portion includes a member extending parallel to said rotating plate mounting said rollers and means for adjusting said rollers radially with respect to said rotating plate.
3. The seal according to claim 1 wherein one seal element is an annular member of flexible wear-resistant sheet material secured to one of the seal mounting means and the other seal element comprises a pair of opposed annular shoes secured to the other seal mounting means and pressing against opposite faces of said flexible sheet material,
4. The seal according to claim 3 wherein said stationary seal portion supports the opposing shoe elements in fluid-tight engagement therewith, spring means maintain said shoes in contact with said flexible seal element, and means secure said flexible seal element in fluid-tight engagement with said rotating seal portion.
5. A seal for a rotary kiln having nozzle means defining an opening therein comprising a movable seal portion fixedly attached to said nozzle for rotation therewith, seal mounting means in said movable seal portion, a stationary seal portion, seal mounting means in said stationary portion, a seal element in sealing engagement with each mounting means, one of said seal mounting means permitting relative movement of said seal element between said rotating and stationary seal portions, means for maintaining said stationary seal portion in central relation to the axis of rotation of said kiln despite displacement of said axis with contraction and expansion of said kiln, a stationary housing for a kiln feed mechanism, and the like, and an inlet nozzle to said kiln, a part of the stationary portion of said seal being flexibly mounted to said housing for sealing the area between said housing and said inlet nozzle, the remainder of said stationary seal portion being connected to rollers which roll on the peripheral edge of a circular member which is fixed to, and substantially concentric with, said kiln, each of said stationary seal parts mounting one of said opposing shoe elements.
6. The seal according to claim 5 wherein a wiper seal is provided between the rotating seal portion and said stationary portion, and means are provided for introducing between said stationary and rotating seal portions and said seal element and said wiper seal a gaseous atmosphere at a positive pressure within said seal.