US2986911A

US2986911A - Pressure sealing device

Info

Publication number: US2986911A
Application number: US728459A
Authority: US
Inventors: Robert C Jackson
Original assignee: Chemstrand Corp
Current assignee: Solutia Inc
Priority date: 1958-04-14
Filing date: 1958-04-14
Publication date: 1961-06-06
Anticipated expiration: 1978-06-06
Also published as: GB844594A; CH372034A; BE577675A; NL238051A; NL127508C; FR1220553A

Description

June 6, 1961 R. C. JACKSON PRESSURE SEALING DEVICE Filed April 14, 1958 ATTORNE Y3 strand Corporation, Decatur, Ala., a corporation of Delaware Filed Apr. 14, 1958, Ser. No. 728,459 1 Claim. (Cl. 68-5) This invention relates to a sealing device and more particularly to a sealing device which permits material to be continuously conveyed without leakage between adjacent regions characterized by a pressure differential.

In the processing of textile material, particularly filamentary material formed from a synthetic composition such as an acrylonitn'le polymer or the like, it is often highly desirable to subject the material to fluid treatment under pressurized conditions. For instance, in the processing of wet spun filamentary acrylic material, a heatrelaxing or annealing operation is generally performed on the material preferably while it is in the form of an elongated rope or tow. As is well known, this annealing operation relieves the molecular strains in the filaments which have been introduced therein by such a filament straining operation as stretching and the like, necessary for imparting sufiicient tensile strength to the filaments to render them suitable for textile end uses. Unless these molecular strains are relieved, the acrylic filaments are prone to fibrillate or split off into fibrils when subjected to abrasion and in fabric form these fibrils cause the fabric to assume a light color at the point of abrasion, giving the illusion of wear.

In one arrangement for carrying out such an annealing treatment, a batch-type operation is employed in which the material is loaded into autoclaves or similar pressure vessels wherein it is subjected to a pressurized heating medium such as steam for an extended period of time while in a relaxed condition. It can be understood that such a batch-type annealing operation is time consuming and is generally expensive both from the standpoint of time and labor expended as well as the initial investment in the bulky apparatus required. As such filamentary material is generally spun in continuous rope or tow form, it lends itself readily to a continuous type of annealing operation. However, conveying the tow continuously between a high pressure region such as that required for carrying out the annealing treatment and a region of low or atmospheric pressure presents serious problems in equipment design. With the relatively high steam temperatures and pressures required in the annealing operation, steam leakage from the high pressure region at the point in the wall of a pressurized chamber through which the tow is passing has been extremely diflicult, if not impossible, to prevent. Even with the use of available steam sealing devices, leakage often occurs to an undesirable extent. Furthermore, prior sealing devices have been subject to rapid deterioration and frequent breakdown increasing the maintenance and operating costs to an unreasonable extent.

Accordingly, a primary object of this invention is to provide a new and novel device for eliminating leakage from a pressurized region through which continuously moving material is conveyed.

Another object of this invention is to provide a new and novel sealing device for eliminating leakage from a pressurized chamber in the interior of which an annealing operation is to be carried out on a continuously moving tow of synthetic material.

A further object of this invention is to provide a new and novel sealing device which permits the movement of a filamentary tow composed of synthetic material such as that formed from acrylonitrile polymers or the like States Patent 6) i Patented June 6, 1961 through a pressurized region with substantially no attendant decrease in its pressure level.

This invention further contemplates the provision of a new and novel apparatus for continuously moving a filamentary tow through a pressurized chamber with virtually no reduction in chamber pressure due to leakage at the points of entrance and exit.

A still further object of this invention is to provide a new and novel sealing device which may be positioned adjacent the material entrance or exit openings in the wall of a pressurized chamber and which responds to the pressure in the chamber by moving into pressure sealing engagement with continuously moving belts between which a tow of synthetic filamentary material is sandwiched to prevent leakage through the wall openings from said chamber.

A still further object of this invention is to provide a new and novel pressure sealing device which is simple in construction, inexpensive to manufacture, and which gives uninterrupted service over extended periods of time without the danger of breakdown.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings.

In general, the objects of the invention are accomplished by providing a sealing device including a sealing member which is arranged to be positioned within a region of high pressure such as the interior of a pressurized chamber, vessel, or the like. The sealing member is provided with passage means for accommodating a continuously moving strip of material such as a filamentary tow or the like. Means are provided for supporting the sealing member in the high pressure region or chamber with its passage means communicating with an opening or passage in a wall which defines the region of high pressure so that a pressure differential between the passage means and high pressure region is produced. Means are also provided for advancing the filamentary tow continuously through the cooperating wall opening and sealing member passage means so that the tow may be moved through the region of high pressure. During the movement of the tow, the sealing member passage means yieldingly opens against the pressure in said high pressure region and intimately engages to tow passing therethroug-h so that leakage of pressure from the high pressure region through the sealing member passage means and wall opening is substantially eliminated.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claim. The invention itself, however, both as to its organization and method of operation, may be best understood by reference to the following description taken in conjunction with the accompanying drawings:

FIGURE 1 is a side View partially in section of material advancing apparatus with which the invention is incorporated; I

FIGURE 2 is an enlarged perspective view of the sealing device of the invention partially broken away to illustrate its supporting means;

FIGURE 3 is a sectional view taken substantially along line 3'3 of FIGURE 1; and

FIGURE 4 is a plan view of the pressure sealing device of the invention.

Referring now to FIGURE 1, there is shown a pres- As generally illustrative of the invention, the sealing device 11 is used in conveying tow 12 between a region of low or atmospheric pressure designated generally by the numeral 13, and a high pressureregion designated generally by the numeral 14. In the specific embodiment illustrated, the region 14 is preferably the interior of a pressure chamber or vessel (not shown) having a wall, a portion of which has been designated by the numeral 16. This chamber is of a type which may be conveniently used to carry out an annealing operation on synthetic filamentary material such as wet spun acrylic tow in a manner to be explained hereinafter. An example of an annealing chamber with which the sealing device of the instant invention may be satisfactorily employed is disclosed and claimed in the copending joint patent application of the present inventor and James P. Richeson, Serial No. 728,460, filed April 14, 1958.

As shown best in FIGURES 2-4, the sealing device 11 comprises a sealing member designated generally by the numeral 17 which is preferably composed of a resilient material such as neoprene rubber or the like. The sealing member 17 contains a central portion or web 18 terminating at each end in

portions

19, 21, extending substantially transverse to the axis of the Web 18 and preferably formed integrally with the web as shown. Although the

end portions

19, 21 may be of the same size, in the preferred embodiment end portion 21 is reduced somewhat in size from that of end portion 19.

Passage means for the tow 12 have been provided in the sealing device 11 which, in the specific embodiment, comprises a longitudinally extending, inner bore or slit 22 throughout the length of the web 18, the ends of which open on the outwardly facing surfaces of the

end portions

19, 21. The slit 22 is of suflicient width, as shown best in FIGURE 2, to accommodate the filamentary tow 12. For instance, the width of the slit 22 may be approximately 6 inches to accommodate a tow 12 laterally spread to substantially the same width. In order to form the slit 22, the web 18 is preferably cut or otherwise split internally so that the overlying Walls of the slit 22 normally move into slit-closing relationship.

Means have been provided for supporting the sealing member 17 within the high pressure region 14 so that one end of the web slit 22 communicates with an opening or passage 23 (FIGURE 1) in the chamber wall 16. Furthermore, the web 18 is positioned in a relatively unrestrained condition. That is, web 18 is arranged to be held in the position shown by rigidly securing the

end portions

19, 21 whereby the web may be deformed or constricted in a manner to be explained hereinafter by means of the high pressure in region 14 during the passage of the tow 12 through the slit 22.

More specifically, as shown in FIGURE 3, a mounting plate 24 is provided having a central opening 26. In order to position plate 24 on the sealing member 17, one end of the sealing member, preferably the smaller end portion 21, is inserted through the plate opening 26 so that the plate 24 may be positioned in contact with the inwardly facing surface of the end portion 19 as shown in FIGURES l, 4. Corresponding openings 27, 28 are provided within the end portion 19 and mounting plate 24, respectively, for accommodating mounting bolts 30 (FIGURE 3), the ends of which are received within appropriately threaded recesses 31 in the chamber wall 16 as shown in FIGURE 4. Thus, the end portion 19 of sealing member 17 may be securely held in a slightly compressed condition between the wall 16 and plate 24 with the end of slit 22 in communication with the wall opening 23 as shown in FIGURE 1. It should be understood that the wall opening 23 is of approximately the same width as slit 22 so that leakage of pressure from the interior 14 through the wall opening 23 is prevented by the sealing engagement between end portion 19 and the surface of wall 16 when the end portion 19 is compressed by the mounting plate 24.

In order to retain the sealing member 17 in the operative position of FIGURE 1 on the wall 16, spacing means such as a plurality of upper and

lower spacers

33, 34, respectively, are secured at one end by means such as welding or the like to the mounting plate 24. The

spacers

33, 34, are preferably rectangular in cross-section as shown best in FIGURES 2, 3, and are provided with

retaining bars

36, 37, respectively, suitably secured to the corresponding ends of the spacers opposite the mounting plate 24.

The

retaining bars

36, 37, are arranged to engage the inwardly facing surface of the end portion 21 on the opposite surface of which is positioned clamping bars 38, 39. The clamping bars 38, 39 are arranged to cooperate with the

retaining bars

36, 37, respectively, so as to clampingly engage marginal portions of the end portion 21 and securely hold the end portion 21 to the corresponding ends of the

spacers

33, 34 as shown in FIGURE 2. In this manner, the central portion or web 18 of sealing member 17 is positioned in a relatively unrestrained condition between the fixedly held

end portions

19, 21, and may respond freely to any deforming or constricting force developed by a pressure differential existing between the interior of the slit 22 and the high pressure region 14.

As previously discussed, the filamentary tow 12 may be continuously conveyed through wall opening 23 and slit 22 of member 17 by any suitable means. For example, the tow 12 alone may be pulled or advanced through the sealing device 11 by any conventional tow advancing means and, in the specific embodiment, the tow advancing means includes a pair of

continuous belts

44, 46, which are preferably formed of relatively thin material such as sheet steel or the like, and are sufiiciently wide to be snugly accommodated within the slit 22 as shown in FIGURE 3. For instance, as discussed above, the belts may be approximately 6 inches wide and are preferably between 0.005 and 0.030 inch in thickness so as to flex freely.

In order to drive

belts

44, 46, each belt is associated with a pair of rolls or pulleys which are positioned on opposite sides of the wall 16. More specifically, belt 44 is positioned on rolls 47, 48 rotatably mounted on shafts 49, 51, and belt 46 is positioned on rolls 52, 53, rotatably mounted on

shafts

54, 56, respectively. Both of the rolls associated with each belt may be driven, if desired, but preferably only one is driven by any suitable means (not shown) and the driven rolls in each belt are suitably connected for simultaneous rotation so that the

belts

44, 46 will travel at the same speed. As shown in FIGURE 1, the

belts

44, 46 are arranged to move in overlying relationship along a portion designated generally by the numeral 57.

As can be seen, in the specific construction illustrated in FIGURE 1, the

belts

44, 46 are arranged to travel in the direction of arrows H and move together into the pressurized chamber interior 14 through the centermost wall opening 23. Each belt subsequently moves out of the chamber interior 14 through one of the remote wall openings 23 spaced along the wall 16 from the centermost opening. As previously described, in order to prevent the leakage of pressurized fluid such as steam from the chamber interior 14, a pressure sealing device 11 is also supported on wall 16 adjacent each of the remote openings 23 each of which accommodates one of the

belts

44, 46 during its movement from the chamber interior 14.

In the operation of the apparatus shown in FIGURE 1, the tow 12 is fed to the nip of rolls 47, 52 so that it moves subsequently into sandwiched relationship with

belts

44, 46 in a three-ply assembly. This three-ply assembly is conveyed in the direction of arrow I through the centrally arranged wall opening 23 and slit 22 of the sealing device 11 and into the chamber interior 14. The tow subsequently emerges from the belts as they separate adjacent the nip of the

rolls

48, 53, and each belt returns to the exterior 13 through a similar sealing device 11 positioned adjacent each of the remote openings 23 as shown in FIGURE 1. When the apparatus of FIGURE 1 is employed in the annealing of a filamentary tow composed of wet spun" acrylic filaments, it is desirable to subject this tow to steam under pressure (preferably steam, at a temperature of between 135 to 155 C. and at a pressure of between 35 to 50 pounds per square inch) and the sealing device 11 is particularly adaptable for facilitating the conveying of such a tow into the chamber interior 14 which is supplied with pressurized steam in any suitable manner. As is well known, the tow is generally maintained in a relaxed or tension-free condition while in the region 14 by any suitable means in order to obtain the desired annealing action in which the molecular strains in the tow filaments are relieved.

As can be seen, the passage of the three-ply assembly consisting of the

tow belts

44, 46, and the tow 12 through the slit 22 of the centermost sealing device 11, forces the slit 22 to yieldingly open as shown in FIGURE 3. The opposed surfaces of the relatively thin

flexible belts

44, 46 move into close, confining relationship with the filaments in tow 12 with a minimum of free space therebetween and the yielding walls of slit 22 closely surround the outer surface of the belts. As previously described, the belt material and thickness is selected so as to permit the belts to flex sufliciently and fill any voids or valleys which might be present in the tow between the filaments.

The close-fitting, intimate relationship between the inner surfaces of the slit 22 and the

belts

44, 46 and the similar relationship between the belts and the tow 12 provide a substantial degree of sealing action in sealing device 11 so as to prevent leakage of pressure from the chamber interior 14 through the wall opening 23.

However, an even more outstanding sealing action for a belt or for the three-ply assembly consisting of the two belts and the tow is obtained by means of the novel construction of the sealing device 11. As has been previously described, the sealing device 11 is supported on the wall 16 with its slit 22 in communication with the wall opening 23. Thus, when the slit 22 is passing either a belt or the belts and tow assembly, an initial slight or negligible flow of pressurized fluid or steam into slit 22 from region 14 will occur. This negligible passage of steam into the slit 22 results in a throttling action and, consequently, a pressure drop through the slit.

Thus, a pressure differential is created between the interior of the slit 22 and the high pressure region 14 which produces a constricting or squeezing action by the relatively unrestrained web 18 and, consequently, slit 22 around the

belts

44, 46, and tow 12 or a belt alone. As this constricting action occurs, the throttling action and therefore the pressure drop is increased to add further to the slit constricting forces developed. The outer surfaces of the web 18 are exposed to the high pressure region as a result of the novel supporting structure for the sealing member 17 shown best in FIGURE 2. Thus, an unusually high sealing action is obtained to provide a virtually leakproof sealing device, and the end portion 19 cooperates with the inner surface of wall 16 to prevent any leakage directly through the opening 23 from the interior 14.

Similarly, a sealing action is produced in the sealing devices 11 adjacent the remote wall openings 23 through which the individual belts pass as they return to the exterior 13 and the high pressure chamber interior 14 is maintained in a substantially sealed condition while the

belts

44, 46, together with the tow 12, move continuously between the

regions

13, 14. It should be understood,

however, that although a movement of the tow 12 into the high pressure region 14 has been shown, the sealing device of the invention is equally useful for removing tow from such a high pressure region through the chamber wall. In the preferred use of the sealing device 11, it is employed withsuitably arranged belts to continuously convey a tow of indefinite length through a pressurized chamber in which an annealing operation is performed.

Through the novel construction of the invention there has been provided a sealing device which enables material to be continuously conveyed between regions of high and low pressure while maintaining the high pressure region in a substantially sealed condition. The sealing device provided is of simple and inexpensive construction and is readily adaptable to not only many types of material conveying means such as belts, tubes, sheaths and the like, but also may be used for conveying the material alone through the high pressure region without affecting the eflicient sealing action of the device. Although thesealing device of the invention is particularly useful in the annealing or steam treatment of filamentary tow formed from a synthetic composition such as acrylonitrile polymers or the like, any suitable pressurized fluid may be satisfactorily handled by material conveying apparatus employing the sealing device of the invention. Furthermore, it can be seen that the

pressure regions

13, 14 may be at any pressure level as long as the region 14 in which the sealing device 11 is located is at a higher level than region 13. For instance, a vacuum might be imposed on region 13 with region 14 at atmospheric pressure.

While there has been described what at present is considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is the aim of the appended claim to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed is:

A sealing device for passing material between a high and a low pressure region having a wall therebetween comprising, in combination, a one-piece, resilient sealing member substantially H-shaped in cross section to provide a longitudinally extending web and an end portion at each end of said web, said sealing member having a centrally arranged, normally closed slit extending longitudinally therethrough, said wall having an opening for admitting said material therethrough, a mounting plate for securing one of said end portions to said wall with one end of said slit in communication with said wall opening whereby a pressure differential is produced between said slit and said high pressure region when said slit is opened, a plurality of longitudinally extending rigid spacers fixedly secured at one end to said mounting plate, and means for rigidly securing the other ends of said spacers to said other end portion to maintain said web in a substantially unrestrained condition whereby said slit is arranged to yieldingly open against the pressure in said high pressure region and pass continuously moving material therethrough in intimate sealing relationship therewith.

References Cited in the file of this patent UNITED STATES PATENTS 890,252 Thompson June 9, 1908 1,819,051 Wilson Aug. 18, 1931 2,522,071 Tait Sept. '12, 1950 2,708,843 Gibson May 24, 1955 2,736,632 Blau Feb. 28, 1956