US3305012A

US3305012A - Heat exchanger bundle

Info

Publication number: US3305012A
Application number: US449259A
Authority: US
Inventors: Henry W Allen
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-04-19
Filing date: 1965-04-19
Publication date: 1967-02-21
Anticipated expiration: 1984-02-21

Description

Feb. 21, 1967 H. w. ALLEIN 3,305,012

HEAT EXCHANGER BUNDLE Filed April 19, 1965 INVENTOR ATTORNEYS United States Patent This invention relates to tubular heat exchangers such as are in general use in refining and chemical industries and in steam generating plants, and has more particularly to do with the junction of the tubes with the tube sheets and the tube retainer members of such exchangers.

, The invention constitutes a further novel development of the invention disclosed in the co-pending application of Celestin Victor Belanger, Serial No. 28,482, filed July 9, 1962, maturing as United States Patent No. 3,181,606, of May 4, 1965, and owned by the assignee of the present application. In that case, there was disclosed the concept of the use of O-rings disposed in counterbores in the tube sheet, surrounding the respective tube ends, and sealing the relatively close tolerances between the tube walls, the walls of the counterbores of the tube sheets, and the adjacent faces of the retainer members. As indicated in that patent, these O-rings are of uniform cross section throughout their circular extent, whatever the specific semicross-sectional configuration might be, whether circular, square, quad, or other shape. The criterion, of course, is that the material from which the O-ring is made be elastic-and'capable of distortion or flowing within the recess or counterbore in which it is positioned in order to effectively seal the fine tolerance clearances between the interfitting elements mentioned.

The general object of the invention is to provide novel and improved sealed junctions for the tubes of exchanger bundles, which alford safeguards from deleterious results of any longitudinal displacement of the tubes as through expansion and contraction, and also which permits the continued utilization of used or worn tube sheets, thus effecting economics in manufacture and maintenance of the exchangers to which these novel provisions may be applied.

The invention, in its preferred embodiments, contemplates the provision of annular sleeves, bushings, or rings preferably of a metal which is the equivalent of that used in the manufacture of the tubing and tube sheets and I0- tary plates or fittings; these rings being closely fitted to the tube ends but relatively movable and disposed upon either or both sides of the position of the elastic O-rings, depending upon the particular condition present or circumstance to be overcome.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which certain embodiments of the invention are illustrated by way of example.

In the drawings:

FIGURE 1 is a fragmentary somewhat diagrammatic view in longitudinal section through one of the tubes of an exchanger bundle, and suggesting the tube end seating and sealing connections usable to prevent dislocation of the seal at the tube ends upon the occurrence of longitudinal expansion or contraction or displacement;

FIGURE 2 is a fragmentary sectional view of the lefthand end of such an installation showing the approximate position and condition of the O-ring upon the existence of predominant pressure from within the tubes;

FIGURE 3 is a view similar toFIGURE 1 and showing the condition of the O-rings at both ends of the tube upon the occurrence of predominant pressure externally of the tubes and with a tube which not only may have been subject to expansion or contraction conditions but may also be shorter than usual and displaced toward the left;

aaoaeiz Patented Feb. 21, 1967 FIGURE 4 is a view similar to the right-hand end portion of FIGURE 3 showing what would occur upon the displacement of a shortened tube in a left-hand direction without the provision of the novel expansion ring;

FIGURE 5 is a fragmentary sectional view of the vicinity of the left-hand end of a tube showing a connection comprising another embodiment of the invention in which a ring is employed as a tube centering expedient; and

FIGURE 6 is a similar view showing the employment of two metal rings for accomplishing both of the purposes toward which the invention is oriented.

In essence the basic provisions of the present invention involve the use of rigid cylindrical rings in association with elastic distortable O-rings within a counterbore constituting an enlargement of the hole through the tube sheet through which the ends of the tubes extend, this novel provision being capable of accomplishing two functions either separately or in combination.

FIGURE 1 of the drawings illustrates the embodiment in which the rigid ring performs the function of preventing the destruction or loss of the soft fiowable O-ring in cases where expansion or contraction or other longitudinal displacement of the tube might occur.

In this figure, one of the tubes of the tube bundle of an exchanger is indicated at 10 and its right and left-hand ends are disposedrespectively through openings 11 and 12 in the oppositely positioned

tube sheets

15 and 16.

At 17 and 18 are shownconventional retainer members 'which are secured in juxta-position to the

tube sheets

15 and 16 and may take any suitable or conventional form, whether as continuous plates substantially co-terminous "with the sheetsor as individual retainer elements each associated with one or more of the tubes of the bundle.

The retainer members are provided with

holes

19 and 20 which must of course be of somewhat smaller diameter than the external diameter of the tube 10 so that the tube may be properly retained within the bundle by abutment with the inward surface of the

retainer members

17 and 18.

In the illustrative embodiment of FIGURE 1, the interfitting of the end of the tube 10 within the opening 11 is of a rather fine tolerance, generally to be expected in new and unworn constructions.

The tube 10 is shown in normal centered position where it is spaced slightly from the retainer members at each end, and fitted around the end portions of the tube 10 and disposed within the

counterbores

22 and 23 are the rigid

cylindrical rings

25 and 26. The outer diameter of the rings approximates the diameter of the counterbores and alfords a snug fit therebetween. Similarly, the inner diameters of-the

rings

25 and 26 fit snugly around the end portions of the tube 10.

I Inwardly .of the

rings

25 and 26 and disposed within the counterbores arethe soft elastic deformable O-

rings

30 and 31. These O-rings are of such inner and outer diameters as to fit snugly between the wall of the

counterbores

22 and 23 and the outer walls of the ends of the tube 10, with either a barely tangential contact, or under a slight degree of radial compression.

Although the O-

rings

30 and 31 are shown as being of circular semi-cross-section, they may be of any cross- ,sectional configuration suitable for the structure contem- 3 adequately seals the junction at 40 between the walls of the hole 11 in the tube sheet 15 and the outer wall of the tube 10. It will of course be understood that a similar distortion of the O-ring 31 at the opposite end of the bundle will occur under these conditions.

Proceeding to FIGURE 3 of the drawings, it will be understood from this showing what occurs when the predominant fluid pressure is exteriorly of the tube system represented by the tube 10. Under such conditions, fluid pressure would be through the slight clearance between the walls of the hole 11 and the outer surface of the tube 10 into the counterbore 22 and serve to move and distort the elastic O-ring 30 as shown at the left-hand end of FIGURE 3, so that the ring will flow into and seal the corners represented at 45 and 46 and respectively located at the junction of the outer surface of the rigid cylindrical ring 25 and the inner wall of the counterbore 22, and between the inner surface of the ring 25 and the outer surface of the tube 10. In this situation the O-ring serves to seal two points of possible leakage of fluid pressure.

Under the influence of fluid pressure in the direction just described, the

rigid rings

25 and 26 could move to the outer portions of the

counterbores

22 and 23 as suggested and abut the inner faces of the

retainer elements

17 and 18, and an inspection of the right-hand end of FIGURE 3 of the drawings will reveal how the

rigid rings

25 and 26 act as expansion compensating elements when the tube 10 expands, contracts, or is displaced longitudinally of the bundle.

For this purpose, each of the

rings

25 and 26 must 'be of a width or axial dimension such that it is somewhat greater than any space 50 which might occur between one end of the tube 10 and the face of one of the

retainer elements

17 or 18 when the tube is of a minimum length as compared with the full distance between the inward faces of the

elements

17 and 18 and shifted laterally into abutment with one of these faces.

In FIGURE 4 there is illustrated what would occur under such conditions of contraction, expansion, or displacement were the

rings

25 and 26 not provided. In this figure corresponding parts at the right-hand end of the bundle are indicated by similar reference characters as in FIGURE 3 but with a prime added. As in the case of FIGURE 3, the pressure is externally of the tubes 10' and in the absence of the rigid ring 26, the O-ring 31' is shown in process of flowing around the end of the tube 10, and under a relatively great external pressure the tube would be distorted and damaged and squirted or blown out through the tube 10' or through the opening 20' in the retainer element 18'. The provision illustrated in FIGURE 3 of the drawings in accordance with the principles of the present invention precludes such damage or destruction of the bundle as suggested in FIGURE 4.

In FIGURE there is illustrated a further function and utility of the broad principles of the present invention. This embodiment is particularly applicable to making it possible to greatly extend the life of tube sheets of an exchanger even if the opening 11 into which the tube fits is enlarged as indicated at 11A in FIGURE 5. These old worn sheets may be employed by deepening the counterbore 22, if necessary, and inserting the rigid cylindrical ring 60 within the counterbore inwardly of the sealing O-ring 30.

In FIGURE 5 the arrangement is similar to that shown in FIGURE 5 of the Belanger patent where the opening 19 in the retainer member 17 is somewhat enlarged as at 19A, the enlarged counterbore portion 19A being of a diameter to snugly receive the extreme end portion of the tube 10.

The rigid cylindrical ring 60, which in accordance with its function now being described, may be called a centering ring, has an outer diameter approximating the diameter of the counterbore 22 and an inner diameter approximating the outer diameter of the tube and serves to center the tube properly regardless of the wear which might have occu red to th bore 1 A- In this embodiment the O-ring very obviously performs the usual sealing function in whatever direction the preponderance of fluid pressure exerts itself. If the pressure is from without the tube system, exerted through the clearance 11A and around the ring 60, the O-ring will seal the corner 65 between the surfaces of the sheet 15 and the retainer 17 and the corner 66 between the outer surface of the tube 10 and the counterbore 19A of the retainer 17. Under a predominance of fluid pressure from within the tube system the O-ring would of course move into contact with the rigid centering ring 60 and seal the corner 68 between the wall of the counterbore 22 and the outer surface of the ring 60, and the corner 69 between the inner surface of the ring 60 and the outer surface of the tube 10.

Now in order to provide against both deleterious eventualities described, two rigid cylindrical rings may be provided within the counterbore of the tube sheet, one upon either side of the O-ring. This arrangement is illustrated in FIGURE 6 of the drawings where the tube 10 enters the possibly enlarged passageway 11A and passes through the counterbore 22 in the tube sheet 15. The retainer member 17 is provided with the usual opening 19 which in this instance is not counterbored and is of a smaller diameter than the outside diameter of the tube 10. The O-ring 30 is disposed between the rigid cylindrical expansion ring 25 and the inwardly disposed rigid cylindrical centering ring 60 and it is quite obvious that upon the occurrence of a predominance of fluid pressure either internally or externally of the tube system the O- ring will move toward one or the other of the rings 25 and 60 and perform the sealing functions as described in the case of the use of the separate rings.

From the above, numerous advantages of the present invention will be apparent. I

In connection with the utilization of the rigid cylindrical rings as centering devices as in FIGURES 5 and 6 it can be pointed out that tube sheets of an average heat exchanger cost somewhere in the neighborhood of $2,500.00 a pair and many hundreds of them are discarded every day in the chemical and refining industries. The considerable economy effected by the present invention is thus illustrated when it is realized that the metal centering rings can be furnished at an average cost of about three cents apiece. These rings may be made of material of durability appropriate to the function to be performed by the exchanger but would usually be made of metal compatible with the metal of the various parts of the tube bundle, for example, of brass, copper, or steel.

Previous attempts to accommodate tubes to worn tube sheets have usually involved the use of expanders for the tubes or rolling the tubes to fit the enlarged worn holes in the sheets, but it was found that each time the tubes were replaced, the expanders increased the diameter of the tube hole in the sheet to a point where the tubes could not be rolled to fit and were too large for the O-rings to seal the opening between the tube and the tube sheet.

In the utilization of the rigid cylindrical ring as an expansion accommodating element as in FIGURES 1, 2, 3, and 6 of the drawings, it will be noted that the counterboring in the retainer elements, as at 19A, can be eliminated, thus efiecting further economies in construction.

It is understood that various changes and modifications may be made in the embodiments illustrated and described herein without departing from the scope of the invention as defined by the following claims.

Having thus described the inventon, what is claimed as new and desired to be secured by Letters Patent is:

1. In a heat exchanger device of the class described, which includes within its usual assembly of parts: a shell; a tube bundle comprising tubes, tube sheets, and retainer plates, said tubes having ends extending through said tube sheets, and said retainer plates applied to the outer surfaces of said tube sheets; and fluid inlet and outlet connections: the improvement which comprises the tube and tube sheet connection whereinthe tube sheet is provided with a hole passing therethrough into which an end of the tube extends, a counterbore extending into said tube sheet from the side opposite to that into which the tube extends, said counterbore constituting a coaxial enlargement of said hole and having a cylindrical Wall surrounding said tube end; a rigid cylindrical ring disposed within said counter bore and having an outside diameter providing a snug fit of small tolerance within the wall of said coutnerbore and an inside diameter providing a similarly snug fit onto the tube end; and an elastic deformable O-ring disposed within said counterbore alongside of said rigid cylindrical ring and of a thickness for contact of its outer and inner diametrical boundaries respectively with the cylindrical wall of the counterbore and the outer surface of the tube end in normal relaxed condition, said counterbore being of greater axial length than that of said rigid ring and said deformable O-ring, whereupon upon subjection of the bundle to a preponderance of fluid pressure upon either the inside or the outside of the tubes, the O-ring will effectively seal the junctions of the surfaces concerned whether of the tube, the tube sheet, or the rigid cylindrical ring.

2. The device as set forth in claim 1 in which said retainer member is secured in closed proximity to the outside face of the tube sheet and is provided with an opening substantially coaxial with said tube and of a diameter less than the outside diameter of the tube, whereby communication is established from the inside of the tube through said retainer plate; the O-ring being positioned exteriorly of the said rigid cylindrical ring within said counterbore and serving also to seal off small tolerance clearances between the tube and said retainer member and between the tube sheet and said retainer member.

3. The device as set forth in claim 1 in which said retainer member is secured in close parallel proximity to the outside face of the tube sheet at each end of the bundle and each retainer member is provided with an opening substantially coaxial with said tube and of a diameter less than the outside diameter of the tube, whereby communication is established from the inside of the tube through said retainer member; the O-ring being positioned within said counterbore interiorly of said rigid cylindrical ring; and the. difference between the minimum length of the tube and the maximum longitudinal distance between the retainer plates at the opposite ends of the bundle being less than the axial dimension of one of said rigid cylindrical rings, whereby distortion and extrusion of an O-ring around the end of the tube within said counterbore under pressure from without the tube system is prevented.

4. The device as set forth in claim 2 in which the hole in the tube sheet through which the tube extends is of greater diameter than the outside diameter of the tube, as when a used worn tube sheet is rebored for continued use, whereby said rigid cylindrical ring acts as a tube centering means as well as a renewed sealing seat for said O-ring.

5. The device as set forth in claim 2 in which one of said rigid cylindrical rings is provided upon each side of the O-ring Within said counterbore, each cylindrical ring acting as an O-riug seat around the outer surface of the tube.

6. The device as set forth in claim 5 in which the hole in the tube sheet through which the tube extends is of greater diameter than the diameter of the tube, as when a used worn tube sheet is re-bored for continued use, whereby the inner one of said rigid cylindrical rings acts as a tube centering means as well as a renewed sealing seat for said O-ring, and the outer one of said rings functions as an expansion ring to prevent loss or damage to the O-ring due to any longitudinal displacement of the tube.

References Cited by the Examiner UNITED STATES PATENTS 2,488,807 11/1949 Currie 165-82 2,635,931 4/1953 May 2.85

2,904,315 9/1959 Pennella l-82 ROBERT A. OLEARY, Primary Examiner.

C. SUKALO, Assistant Examiner.

Claims

1. IN A HEAT EXCHANGER DEVICE OF THE CLASS DESCRIBED, WHICH INCLUDES WITHIN ITS USUAL ASSEMBLY OF PARTS: A SHELL; A TUBE BUNDLE COMPRISING TUBES, TUBE SHEETS, AND RETAINER PLATES, SAID TUBES HAVING ENDS EXTENDING THROUGH SAID TUBE SHEETS, AND SAID RETAINER PLATES APPLIED TO THE OUTER SURFACES OF SAID TUBE SHEETS; AND FLUID INLET AND OUTLET CONNECTIONS: THE IMPROVEMENT WHICH COMPRISES THE TUBE AND TUBE SHEET CONNECTION WHEREINTHE TUBE SHEET IS PROVIDED WITH A HOLE PASSING THERETHROUGH INTO WHICH AN END OF THE TUBE EXTENDS, A COUNTERBORE EXTENDING INTO SAID TUBE SHEET FROM THE SIDE OPPOSITE TO THAT INTO WHICH THE TUBE EXTENDS, SAID COUNTERBORE CONSTITUTING A COAXIAL ENLARGEMENT OF SAID HOLE AND HAVING A CYLINDRICAL WALL SURROUNDING SAID TUBE END; A RIGID CYLINDRICAL RING DISPOSED WITHIN SAID COUNTERBORE AND HAVING AN OUTSIDE DIAMETER PROVIDING A SNUG FIT OF SMALL TOLERANCE WITHIN THE WALL OF SAID COUNTERBORE AND AN INSIDE DIAMETER PROVIDING A SIMILARLY SNUG FIT ONTO THE TUBE END; AND AN ELASTIC DEFORMABLE O-RING DISPOSED WITHIN SAID COUNTERBORE ALONGSIDE OF SAID RIGID CYLINDRICAL RING AND OF A THICKNESS FOR CONTACT OF ITS OUTER AND INNER DIAMETRICAL BOUNDARIES RESPECTIVELY WITH THE CYLINDRICAL WALL OF THE COUNTERBORE AND THE OUTER SURFACE OF THE TUBE END IN NORMAL RELAXED CONDITION, SAID COUNTERBORE BEING OF GREATER AXIAL LENGTH THAN THAT OF SAID RIGID RING AND SAID DEFORMABLE O-RING, WHEREUPON UPON SUBJECTION OF THE BUNDLE TO A PREPONDERANCE OF FLUID PRESSURE UPON EITHER THE INSIDE OR THE OUTSIDE OF THE TUBES, THE O-RING WILL EFFECTIVELY SEAL THE JUNCTIONS OF THE SURFACES CONCERNED WHETHER OF THE TUBE, THE TUBE SHEET, OR THE RIGID CYLINDRICAL RING.