US2673101A - Joint construction - Google Patents

Description

March 23, 1954 MASLIN 2,673,101

JOINT CONSTRUCTION Filed Sept. 21, 1950 F'IGJ.

INVENTOR.

JOHN A. MASZLIN ATTORNEY.

Patented Mar. 23, 1954 JOINT CONSTRUCTION John A. Maslin, Claymont, Del., assignor to Allied Chemical & Dye Corporation, New York, N. Y., a corporation of New York Application September 21, 1950, Serial No. 186,029

1 Claim.

This invention relates to apparatus for treating solid material with a gas, particularly to apparatus for drying solid material.

The present improvements may be exemplified in connection with construction and operation of a rotary drum used to effect the final drying of material such as ammonium alum, potash alum or various salts. The material to be dried, after preliminary dewatering in, e. g. a centrifuge or filter, is usually introduced into one end of the rotary drum and drying gas such as heated or filtered air or heated inert gas such as carbon dioxide, depending upon the particular nature of the operation at hand, is charged into one end of the drum through a fixed conduit and flows through the drum in either coor countercurrent relation to the material being treated. Principally because of appreciable eccentric movement of the rotary drum, resulting from wear and tear and maladjustment of the drum on its supporting rollers and driving gears, it is difficult and often impossible to provide a gas and dust-tight joint between the rotary drum and the fixed gas inlet. Hence, to avoid dusting at this joint it has been the practice to operate the apparatus as a whole in such a way as to maintain a slight negative gas pressure at the gas inlet end of the dryer. Such a procedure requires the use not only of a blower to supply gas to the gas inlet end of the dryer but also an additional suction fan in the tail gas line of the dryer, the operation of which fan must be carefully adjusted in order to maintain the desired negative pressure at the gas inlet end of the dryer. Often, it is necessary to efiect drying by means of an inert gas to avoid oxidation of the material being dried. In this situation, when maintaining a negative pressure at the gas inlet end of the drum, it is not possible to avoid drawing in atmospheric air, i. e. false air through the joint between the rotary drum and the fixed gas inlet. Further, the atmosphere in many chemical plants contains impuritie which are sucked into the dryer and cause contamination of the product being dried. In any case when drying with hot air, such false air is objectionable because it does not have the desired drying potential and hence leakage thereof into the dryer reduces dryer capacity.

An object of this invention is to provide a simplified and gas-tight joint between a rotary drum used in processing operations and a stationary conduit connected therewith, which joint permits substantial eccentric movement between the drum and conduit while continuously main-- taining gas-tight relation therebetween.

The invention, its objects and advantages may be understood from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a side elevation of the drum and seal with the top portion thereof shown in section along plane l| of Fig. 3;

Fig. 2 is also a side elevation with a portion of the outer shell of the drum broken away along plane 2-4 of Fig. 3, to show certain internal features of the dryer seal;

Fig. 3 is a vertical section of the drum end taken along plane 3-43 of Fig. 2; and

Fig. 4 is an elevation of a drum with a modifled rotary seal fabricated according to one embodiment of the invention.

Referring now to the drawings and in particular Fig. 1 thereof, reference number In des ignates a rotary drum having an enlarged cylindrical section I l, a cylindrical end section I 2 of smaller diameter and a conically tapered section It therebetween. End section I2 is provided with a flange or diaphragm I6 having substantial radial dimension with respect to the drum, said flange being welded to and in gas tight relation with the end section and supported by several ribs ll. Flange It is provided with endwise planarly formed outwardly directed face 20 which is adapted to contact in sliding frictional engagement with another sealing face.

Plate 22 is disposed a short distance from flange l6 and is supported by brackets 25. Cylindrical conduit 2!, welded to end plate 22, is disposed within end section I 2 and substantially spaced apart from said end section to provide annular port 25 between said conduit and end section through which gas tends to flow. Rotation of conduit 2! and end plate 22 are prevented by supporting brackets 26.

Diaphragm or flange 2? is formed by the circumferential portion of plate 22 extending radially beyond conduit 2!. Disposed between flanges It and 27 is ring so which has substantial radial dimension and on the inward side of which is formed a second sealing face 3|, which face also has substantial radial dimension. The inner circumference of ring 36 is sufilciently large to provide a loose fit on conduit 2|. Ring 30 is carried by flange 2'! and conduit 2i, rotation of said ring with respect to said flange being prevented by means of multiple pins 32 which are Welded to ring 3d at 35, which pins extend through corresponding loosely fitting holes36 in flangezl. It is apparent that the means described, i. e. pins 32 and corresponding loosely fitting holes 36 in flange 21, permit freenaxial movement of the ring with respect to conduit 2 I. but prevent rotation of the ring.

Disposed between ring 30 and flange 21 and around conduit 2| is continuous flexible compression member 31, preferably having substantial rigidity, e. g. a continuous flexible compressible rubber tube. This tube exerts axial expansive force against adjacent surfaces of ring 30 and flange 21. The axial expansive force exerted by rubber tube 3! causes a gas-tight but removable contact between tube 31 and the inner face 40 of flange 21, and also a gas-tight but removable contact with the outer surface 39 of ring 30. This axial expansive force exerted by rubber tube 31 against ring 38 forces together the two sealing faces 20 and 3| of flange I and ring 30 respectively, thereby closing port 25 to flow of gas therethrough. It will be noted that use of a continuous rubber tube according to the illustrated embodiment of my invention serves a double purpose, i. e. preventing passage of gas through the opening between ring 3% and flange 21, and also exerting pressure against ring 39 to cause gas-tight contact between surfaces 2!) and 3|. Although, e. g. spring devices may be supplied to supplement the axial force exerted by the tube, the simplest construction and hence a preferred embodiment of the invention comprises use of the expansive force in the rubber tube 31 as the only means for urging together the two sealing faces and 3|.

The size of opening in the port 25, represented by the distance between inner wall 4| of end section [2 and outer wall 42 of conduit 2| is sufficiently great to accommodate, as desired, substantial eccentric motion between rotating drum Ill and fixed conduit 2|. By reason of such eccentric motion the rotative movement between sealing faces 20 and 3| is accompanied by substantial radial movement. It is a particular advantage of my present invention that the free space allowed between surfaces 4| and 42 in conjunction with the ready self-adjustability of the compressed rubber tube 3'! permits of substantial eccentric movement between the drum and the conduit while still maintaining gas-tight contact between flange 21 and tube 3?, tube 3'! and rin 30, and between ring 3?. and flange 15, thereby completely sealing off the port and preventing flow of gas through the port.

Conduit 2| communicates with smaller gas inlet conduit 45 and is preferably welded thereto, through which inlet conduit treating gas may be introduced via conduit 2| into drum I0. Screw conveyor 45 is supplied to feed solid material to be treated, e. g. wet material to be dried, to drum in.

Operation of the apparatus is as follows: Solid material is introduced to rotating drum Ill through screw conveyor 45. Treating gas, e. g. hot gas to be used in drying wet solid material, passes through conduit 46 into conduit 2|, thence through the open space in rotating drum Ill. The solid material tends to accumulate in the cylindrical section II of drum It], i. e. at the bottom of the slope of conical section l5, and is thence moved through the drum. Flow of gas through port 25 is meanwhile prevented by the sliding gas-tight contact between sealing faces 20 and 3|, and the stationary contact between rotary tube 31 on the one hand and ring 3%] and flange 2'! on the other hand. Rotation of ring 30 is prevented by multiple pins 32 extending through holes 33. Constant contact between sealing faces .20 .and 3| is assured by the expansive force in rubber tube 3! bearing against ring 30 and the axial self-adjustability of ring 30 effected by the loose position of pins 32 in holes 36.

In preferred structures of the present invention, end section l2 and conduit 2| are of sufficient length to provide annular port 25 having substantial axial length. The purpose of this structure is to maintain the locale of the solid material undergoing treatment as far removed as possible from the sealing faces 20 and 3| thereby to minimize the possibility of inclusion of solid material between said sealing faces, possibly resulting in deterioration of or excessive friction between the faces. As drum i0 rotates it lifts and drops solid material through the gas space therein. To further remove solids (potential abrasives) from sealing faces 20 and 3| the portion of drum |0 adjacent to and inward from end section I2 is preferably formed in conical tapered shape as at l5. In the latter structure, solid material entering conduit 2! through screw conveyor 45 quickly slides down the slope of the lower portion of tapered section is and is thereby quickly removed to the cylindrical portion H of drum l0. Hence, all the solid material passing through the gas space in drum IE! is substantially confined to cylindrical portion In and removed from the inward end of conduit 2| by dis tance represented by the axial dimension of tapered section l5.

To assist further in preventing contact between solid material and sealing faces 20 and 3|, according to a preferred embodiment of the invention, an Archimedes spiral 41 is secured, preferably welded, to the inner face 4| of end section I2.

As shown in Fig. 3, the rotation of the drum as viewed endwise is counterclockwise. TheArchimedes spiral is formed in the shape of a righthand thread. By this means the axially pitched construction of the spiral in cooperation with rotation of the drum tends to move any solid material which might possibly find its way toward the region of the sealing faces, inwardly away from said sealing faces. Adequate free space exists between innermost surface 48 of spiral 41 and surface 42 of conduit 2| to permit eccentric motion as described above.

Although preferred structure of the present invention comprises an annular port of substantial axial length as illustrated in Figs. 1 and 2, outstanding advantages of the invention may be obtained according to an illustrative embodiment of the invention shown in Fig. 4, wherein an annular port 50 of insubstantial axial length is provided. According to the latter embodiment, flange It, ring 50, rubber tube 3'1 and flange 2'! are provided. Hence, continuous sealing of port 50 is afforded by virtue of the continuous contact between faces 2i) and 3! and between tube 37 and ring 363 and flange 21, and the ready selfadjustability of rubber tube 31 to each of the various positions of the drum in rotation about its axis. Allowance for substantial eccentric movement between drum in and conduit 2| is provided by the size of port 50 and the adaptability of flange It and ring 39 to relative eccentric movement. Hence, the structure described in Fig. 4 is included within the scope of my invention.

Although the drum has been described above as being rotatable and the conduit as being stationary, it is within the scope of the development to apply the principle of the invention to any two adjacent members, one being rotatable with respect to the other and associated and arranged and substantially spaced apart and in non-fluid tight relation to provide a port through which fluid may egress or ingress therebetween. The two members may be of the same or different size, and one may or may not project into the other. Generally then, there is provided a first diaphragm associated in fluid-tight relation with one of the members and having a first sealing face, a second diaphragm associated in fluidtight relation with the other of said members and the ring and axially compressible member (in contact with the ring and one of the diaphragms) therebetween. Structure in which either member or both of the members is rotatable or structure in which either of the members carries with it the ring and rubber tube described above is Within the scope of the invention. However, for reasons of simplicity of construction it is preferred to provide the member, e. g. the conduit, of smaller diameter mounted to a substantial extent within the other member (e. g. the drum end) and furnish the conduit with the ring and rubber tube and the drum end with the sealing face corresponding with face of flange It. The continuous rubber tube surrounding con-- duit 2| has been described as a part of the rare ferred structure; however, any continuous flexi ble compression member may be substituted, preferably such a member having substantial rigidity.

Although sealing faces 20 and 3| have been illustrated as being substantially perpendicular to the axes of conduit 21 and drum l8, it would be feasible to supply flange it and ring 33 having sealing faces disposed at somewhat of an angle to said axes, the important factor being that said sealing faces have substantial radial dimensions so that rubber tube 37, acting in a substantially axial direction, will tend to maintain suflicient pressur between said faces to afford desired gastight contact. Use of means other than the Archimedes spiral in annular port for preventing entry of solid material in the region of sealing faces 20 and 3!, e. g. use of blasts of air or other gas in port 25 directed inwardly toward drum I0 comes within the purview of the invention.

Although the foregoing description has been limited to use of a gas as a treating medium in drum ID the invention may be exploited and many advantages realized by applying the same to apparatus for handling fluids, e. g. liquid, as the treating material to prevent ingress of fluid to or egress of fluid from the apparatus through a port formed between two members having relative rotative motion.

I claim:

In apparatus for treating solid material with a gas providing a rotatable drum having a coaxial cylindrical end section and a fixed cylindrical conduit extending into and concentrically spaced apart from said end section in non-gastight relation to provide an annular compartment in communication with the interior of said drum, a first flange formed on the outer end of said cylindrical end section and extending radially outwardly, a second flange secured to said conduit axially spaced from said first flange and extending radially outwardly, a fluid-tight seal between said drum and conduit comprising an annular ring loosely disposed non-engageably around said conduit adjacent said first flange to have a face co-extensive with at least a portion of said first flange face, said ring and first flange providing the only relatively rotatable and frictionally engaged fluid-tight faces in the seal, a continuous tubular flexible compressible member compressibly disposed between and in fluid-tight engagement with opposed faces of said ring and said second flange, the compressive force of said member maintaining said ring and said first flange in fluid-tight rotation-permitting engagement and providing a fluid-tight seal between said ring and said second flange, and a plurality of pins secured to said sealing ring and slidably extending through openings in said second flange, said pins preventing relative rotational movement of said ring and second flange while permittlng limited movement of said ring axially of said conduit with flexing of said compressible member.

JOHN A. MASLIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 373,825 Gleich et a1 Nov. 29, 1887 1,548,333 Scott Aug. 4, 1925 2,038,299 Kohlhagen Apr. 21, 1936 2,291,801 Feucht Aug. 4, 1942 2,381,432 Bratton Aug. 7, 1945 2,402,224 Hornbostel June 18, 1946 2,455,539 Wahl Dec. 7, 1948 2,460,746 Guthrie et a1 Feb. 1, 1949 2,473,710 Jillson June 21, 1949 2,522,993 Coffey Sept. 19, 1950

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