US3503440A

US3503440A - Formed plate tube support

Info

Publication number: US3503440A
Application number: US785914A
Authority: US
Inventors: Nicholas D Romanos
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1968-12-23
Filing date: 1968-12-23
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31
Also published as: FR2030101A1; DE1961150A1; CH499747A; NL6919192A; BE743535A; BR6914753D0

Description

March 31, 1970 N. D. ROMANOS FORMED PLATE TUBE SUPPORT 4 Sheets-Sheet 1 Filed Dec. 23, 1968 A 7'TOENEY March 31 1970 N. D. ROMANOS 3,503,440

FORMED PLATE TUBE SUPPORT Filed Dec. 23. 1968 4 Sheets-Sheet 2 f INVENTOR. \fL NICHOLAS P- POMANOS FIG- - FIG-5 H. 0M4} ATTORNEY March 31, 1970 D .ROMANQS 3,503,440

FORMED PLATE TUBE SUPPORT Filed Dec. 23, 1968 4 Sheets-Sheet 5 INVENTOR. N/CHOLA5 P. ROMA/V05 ATT OENE Y March 31, 1970 N. D. ROMANOS FORMED PLATE TUBE SUPPORT 4 Sheets-Sheet 4.

Filed Dec. 23. 1968 1 2 \J m G M 2 w 4 a 8 u H a #6 w w F L gm J 1 F m INVENTOR. NICHOLAS P. ROMA/V05 BY 2 I z FIG /4 ATTORNEY United States Patent 3,503,440 FORMED PLATE TUBE SUPPORT Nicholas D. Romanos, Chattanooga, Tenn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Dec. 23, 1968, Ser. No. 785,914 Int. Cl. F28d 7/ 00; F28f 9/00; F22b 7/04 US. Cl. 165-162 6 Claims ABSTRACT OF THE DISCLOSURE Tube support structure especially adapted for supporting the free-standing, horizontally extending connecting portion between the depending legs of U-tubes arranged in the tube bundle of a shell and tube type heat exchanger against the effects of vibrations. The tube support structure consists of a plurality of plate members having mutually spaced, formed projections along both side edges thereof. The projections are oifset normal to the plane of the plate members to define U-shaped, tube-engaging receptacles adapted to retain the tubes along their connecting portions. The plate members are disposed in a row between each layer of tubes in the tube bundle and are anchored at their top and bottom ends to the tube bundle enclosure to secure the support structure with respect to the shell.

BACKGROUND OF THE INVENTION During recent years shell and tube type heat exchangers have been developed to provide a highly eflicient means for generating vapor. Such vapor generators provide a great amount of heating surface by means of a large number of small diameter tubes disposed in a tube bundle that substantially fills the vapor generating chamber formed by the enclosing shell. Vapor generators of this type commonly employ tube bundles formed of layers of U-shaped tubes, the ends of whose legs are secured to a tube sheet at one end of the shell while the horizontally extending bend portion connecting the legs is disposed uppermost in the chamber. A heating medium, such as high temperature Water, vapor, petroleum, or gas, among others, is passed through the tubes and gives up a portion of its heat to a vaporizable liquid that is circulated through the chamber about the tubes to emerge from the shell as saturated or superheated vapor.

Because such vapor generators, especially those of high capacity, are of considerable axial length, the tubes that comprise the tube bundle must be relatively long, thereby rendering them highly susceptible to flow and/ or mechanically induced vibrations. Such vibration is especially pronounced in the area of the bend portion of the tubes which is the furthest removed from the points of attachment of the tube ends to the tube sheet. In order to prevent the deleterious effects of vibration, such as damage to the tubes or other component parts of the generator, it is necessary that means be provided to support the tubes against vibration.

The tube support means should satisfy several criteria. It should properly space and secure tubes relative to each other. It should permit relative movement between the tubes and the shell in order to accommodate differential thermal expansion. It should not impair heat transfer between the heating medium and the liquid being vaporized. It should not substantially increase the pressure drop on the vaporizable fluid passing through the shell. And additionally, the tube support means cannot be so complex in design or expensive in fabrication as to render it economically infeasible.

The prior art is replete with tube support structures that adequately provide support for straight, vertical tubes Patented Mar. 31, 1970 or for the vertical legs of U-tubes arranged in the heat exchanger, but such arrangements cannot be successfully adapted to support the horizontally extending bend portion of U-shaped tubes. T-ube supports for supporting this portion of a U-tube tube bundle have commonly taken the form of strips or plates disposed in bearing relation between adjacent layers of tubes. Such form of support is undesirable for the reason that it provides support for the tubes in only a single plane. When additional strips are added to support the tube in the other plane, the structure presents a substantially impervious barrier to cross flow of the vaporizable fluid flowing through the tube bundle, thereby reducing the heat transfer efliciency of the unit as well as increasing the amount of pressure drop experienced by the flowing fluid.

It is to the improvement of such tube support structures that the present invention is directed.

SUMMARY OF THE INVENTION The present invention provides tube support stmcture especially adapted for spacedly supporting the horizontally extending connection portion of inverted U-tubes arranged in the tube bundle of a shell and tube type vapor generator. The tube support structure is so-constructed as to provide both lateral and vertical spacing between adjacent tubes of the tube bundle in a manner as to not seriously impede longitudinal and cross flow of vaporizable fluid through the tube bundle in the region of the tube support structure.

In general terms, the tube support structure of the present invention comprises a plurality of vertically elongated, thin plate members that are disposed between adjacent layers of tubes and located in a row extending transversely of the axis of the tube bundle. Each of the plate members is provided along its oppositely spaced side edges with lateral projections, portions of which are offset normal to the plane of the plate member to form generally U-shaped receptacles for engaging the tubes of the adjacent tube layer. The projections are disposed on alternate spacing along the side edges of the plate members such that alternate tubes in each tube layer are received in receptacles emanating from alternate sides of the plate members. By reason of this construction, ample flow area is provided through the plane of the tube support structure so as to produce only an insignificant impedance to cross flow of the vaporizable fluid flowing through this region of the tube bundle. Addi tionally, the offset portions of the projections are formed of a length that corresponds to the diameter of the tubes such that their end edges engage the rear surface of the adjacent plate member in order that all of the plate members are in mutual abutment, and the surface of the tubes enclosed in the receptacles is thus engaged by the tube support structure at four equally spaced points about their circumference thus to fix the tubes position both laterally and vertically.

Thus, by means of the disclosed tube support structure, all of the above-mentioned criteria are satisfied. The tubes are properly spaced and supported with respect to one another in both the lateral and vertical directions. Provision is made in the construction to secure the tube support structure with respect to the shell in a manner that enables thermally induced relative movement between the tubes and the shell to occur. Because the receptacles are disposed on staggered spacing along the laterally spaced side edges of the plate members, both longitudinal and cross flow of vaporizable fluid through the region occupied by the tube support structure is permitted, thereby enhancing the transfer of heat between the heating medium conducted through the tubes and the vaporizable fluid in which the tubes are immersed. Also, by reason of the improved constructions ability to reduce the amount of flow restriction presented by the tube support structure, the amount of pressure expended by the vaporizable fluid in flowing through the vapor generator is considerably reduced as compared with fluid flowing through the vapor generators employing tube support structure of the prior art.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevation of a shell and tube type vapor generator having a tube bundle incorporating the tube support structure of the present invention;

FIGURE 2 is a partial elevational section taken along line 22 of FIGURE 1;

FIGURE 3 is an elevational view taken along line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged detail view of a portion of the structure shown in FIGURE 2;

FIGURE 5 is an enlarged detail view of a portion of the structure shown in FIGURE 3;

FIGURE 6 is an isometric representation of a typical plate member of the tube support structure of the present invention;

FIGURE 7 is a plan section taken along line 77 of FIGURE 1;

FIGURE 8 is a plan view taken along line 88 of FIGURE 1;

FIGURE 9 is a plan view taken along line 99 of FIGURE 1;

FIGURES 10 and 11 are enlarged detail views of a portion of the structure shown in FIGURE 3;

FIGURES 12 and 13 are views illustrating the tie pin employed in the present invention; and

FIGURE 14 is a plan section taken along line 1414 of FIGURE 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGURE 1 of the drawings, there is shown a shell and tube type vapor generator 10 incorporating tube support structure constructed according to the present invention. The vapor generator 10 comprises a vertically elongated pressure vessel defined by a lower cylindrical shell 12 and a larger diameter, upper cylindrical shell 14 integrally connected with the lower shell by means of a frusto-conical transition member 16. The ends of the vessel are closed, at the bottom by means of hemisphericallyformed closure head 18 and at the top by a dome-shaped cover 20 containing a vapor outlet nozzle 22. The interior of the pressure vessel contains

baflle plate members

24, 26, and 28 that cooperate with the wall of the shells to form an inner vapor generation chamber 30 and an outer, annular downcomer passage 32. At the lower end of the lower shell 12, and intermediate it and closure head 18, is disposed a tube sheet 34 that extends transversely of the center line of the vessel and connects with the wall of the shell. The tube sheet 34 contains a plurality of tube openings 36 adapted to fixedly receive the ends of U- shaped heat exchange tubes 38' that form a longitudinally extending tube bundle 40 substantially filling the lower region of the vapor generation chamber 30. The tube openings 36 extend through the tube sheet 34 to place the tubes 38 in fluid communication with a heating fluid chamber 42 that occupies that region of the vessel enclosed between the closure head 18 and the tube sheet 34 and which is divided into inlet and

outlet portions

44 and 46, respectively, by means of a diametral plate 48. The tubes 38 of the tube bundle 40 are arranged such that their opposite ends communicate with one of the respective portions of the chamber 42 for the through-flow of heating fluid through the tubes. The chamber 42 is connected to a source of heating fluid (not shown) by means of inlet and outlet nozzles 50 and 52, respectively, that communicate with the

respective chamber portions

44 and 46 and thereby effect circulation of heating fluid through the tubes. Feedwater is supplied to the unit through an inlet nozzle 54 that is shown penetrating the upper shell 14. A ring header 56 connects with the nOZZle 54 and serves to distribute feedwater passed through the nozzle about the circurnference of the downcomer passage 32 discharging it into the passage by means of downwardly-directed discharge ports 58 that are spacedly disposed about the lower surface of the header. Flow of the feedwater from the downcomer passage 32 into the vapor generation chamber 30 is effected by the spaced relationship that exists between the lower end of the baflle plate 24 and the upper surface of the tube sheet 34.

Within the vapor generation chamber 30 the feedwater is caused to flow in heat exchange relation with the tubes 38 where heat is extracted from the heating fluid circulated therethrough to cause some of the feedwater to be transformed into vapor. The so-created vapor-liquid mixture flows to the upper region of the vapor generation chamber 30 which is formed as a mixture collection chamber 60 as defined by the cooperation between the bafile plates 26 and 28. From the mixture collection chamber 60 the flowing mixture is passed to vapor-liquid separator apparatus, a multiplicity of such separators indicated as 62 being mounted upon baflle plate 28 and communicating with the chamber 60 by means of openings 63 provided in the plate. The separators 62 may be of any well-known construction and are arranged to discharge separated liquid downwardly upon the baffle plate 28 from whence it is returned to the downcomer passage 32 to be mixed with the incoming feedwater and recirculated through the unit. The separated vapor, on the other hand, is discharged from the separators in the upward direction and passes through appropriate contact drying apparatus 64, from whence it is passed out the vapor outlet nozzle 22 to a point of use.

As in common in vapor generators of the disclosed type, the U-tubes that comprise the tube bundle 40 each include a pair of straight, vertically extending leg portions 66 interconnected by a horizontally-extending connecting portion 68. In the tube bundle 40 of the unit disclosed herein, the great majority of the tubes 38 have connecting portions 68 that are generally straight. Those tubes, however, that lie in the innermost tube rows may be formed, as shown, with connecting portions that are generally arcuate in shape. All of the tubes 38 are small diameter, thin walled tubes that are arranged, as shown in FIGURE 2, in closely spaced layers with each layer containing a plurality of parallel tubes. In order to provide maximum heat transfer effectiveness, the tube layers of the present arrangement are disposed such that the tubes therein have their centers located on a triangular pitch. Such arrangement, as can be seen from FIGURES 8 and 9, places the tubes of each tube layer in alignment with spaces between the tubes of the adjacent layer, thereby to expose a greater amount of heating surface to the flowing vaporizable fluid.

Because the distance between the secured ends of the tubes 38 in the tube sheet 34 and the top of the tube bundle 40 is of considerable magnitude as compared with the diameter of the tubes, means must be provided for spacedly supporting the tubes in order to protect them against damage caused by flow-induced and/or mechanically-induced vibration and also to impart sufiicient rigidity to the tubes in order to maintain their spaced relationship in the tube bundle. In the disclosed arrangement, a plurality of axially-spaced, horizontally-extending plates 70 are disposed throughout a substantial portion of the height of the tube bundle 40 and operate to spacedly support the straight leg portion 66 of tubes 38. These spacer plates 70, being of well-known construction, have surfaces that, as shown in FIGURE 8, contain a plurality of aligned openings 72 through which the leg portions 66 of the tubes 38 are passed. A number of small diameter openings 74 are disposed about each of the tube openings 72 and serve to effect longitudinal flow of vaporizable fluid through the planes of the plates. Vertical support for the plate 70 is provided by appropriate connector means that attach the plates at circumferentially spaced positions about their outer peripheral edges to the inner surface of the bafile plate 24. Additional support for these plates may be provided intermediate their span by their attachment to tie rods 76 that connect at their lower ends to the tube sheet 34 and which extend longitudinally of the vapor generation chamber 30 for the principal purpose of supporting tube support structure attachment plates 112 as described hereinafter.

According to the present invention means are provided to spacedly support the horizontally-extending connection portions 68 of the inverted U-tubes 38 in the upper region of the tube bundle 40. In FIGURE 1 of the drawings, five laterally spaced tube support structures 80 constructed according to the invention are shown. It should be understood, however, that a greater or less number of tube support structures can be employed in heat exchangers having varying tube bundle dimensions. The tube support structures 80 illustrated inthe drawings are all identically formed such that, for the sake of brevity, only one such structure will be described in detail herein.

The tube support structure 80 comprises a plurality of vertically elongated, thin, fiat plate members 82 disposed each between adjacent layers of tubes 38 in the tube bundle 40. The plate members 82 are disposed in a transverse row across the width of the tube bundle as viewed in FIG- URE 2 and extend perpendicularly of the connecting portions 68 of the tubes between upper and lower structural support members as hereinafter described. Each of the plate members 82 is provided on its opposite side edges 84 and 86 with alternately spaced tube receptacles 88 adapted to supportingly space the tubes of each tube layer from one another. The receptacles 88 are defined by projections 90 which are lateral, coplanar extensions of the plate member 82 having forwardly ofiset opposing arms 92 formed from oppositely spaced portion of the projections 90 that are bent at right angles to the plane thereof. Ideally, the arms 92 are formed of a length substantially equal to or slightly greater than the diameter of the tubes 38, thereby to permit them to abut the rear surface of an adjacent plate member at their end edges when the tube support structures are assembled within the tube bundle.

The plate members 82 of the tube support structures 80 are assembled in staggered relation as shown in FIGURE 9 for reasons hereinafter set forth and are suspendedly mounted within the unit by means of mounting assemblies indicated generally in the respective figures as 94. These assemblies each consist of a horizontally disposed struc tural member such as I-beam 96, that extends across the width of the vapor generation chamber 30 in overlying relation to its associated tube support structure 80 and having its opposite ends fixedly secured at the inner surface of the chamber defining plate, here shown as baffie plate 26, as by means of welding or otherwise. A suspension plate 98 is slideably secured to the underside of the I-beam 96 by means of oppositely spaced angle members 100 attached to the lower flange of the I-beam and whose depending legs form a guideway that receives the upper edge of the plate 98. Within the space defined by the angle members 100 a slight clearance is provided between the upper end of the suspension plate 98 and the lower flange of beam 96 to accommodate thermally induced movement of the tube support structures. Connection between the plate 98 and angles 100 is effected by means of threaded connectors 102 that extend through circular openings in the angles and slotted openings in the plate (both of which are not shown).

Attachment of the tube support structures 80 to their associated mounting assembly 94 is effected in a manner shown in FIGURES 2 and 3 wherein, in the disclosed arrangement, the suspension plate 98 is formed with the lower end edge 104 having the general configuration of the outline of the upper periphery of the tube bundle 40, and the upper ends of the tube support plate members 82 are fixedly secured at longitudinally spaced points along the length of the edge, as by means of welding. To facilitate the connection of the plate member 82 to the suspension plate 98, the upper ends of the former are provided with aligned vertical slots 106 to receive the lower end of the latter. At their lower ends the plate members of each tube support structure are provided with lower attachment apparatus, indicated generally as 108, for maintaining their mutually spaced relation while permitting the structures to undergo vertical movement with respect to the enclosing shell structure in response to thermal expansion and contraction of the U-tubes 38. Each attachment apparatus 108 comprises a relatively narrow, horizontally disposed

flat plate

110 or 110 that extends through the tube bundle 40 in underlying relation to its associated tube support structure 80 and having its opposite ends attached to the inner surface of the downcomer bafile plate 24 by appropriate means as shown in FIGURE 2. The plate 110, being located in a region of the tube bundle that contains tubes 38, is provided, as shown in FIGURE 9, with tube openings 112 to permit passage of the tubes through the plates. The plate, indicated as 110', since it extends through that region of the tube bundle that lies immediately below the bends 68 that form the connection portion of the innermost U-tubes 38, is in a region which is devoid of tubes and thus, as illustrated in FIG- URE 14, requires no tube openings. The plates 110 and 110' are all provided with oppositely spaced rows of small diameter openings 114 for the sliding reception of tie pins 116 as hereinafter described. The openings 11-4 in the plate 110 are disposed on staggered spacing in order to be accommodated by the plates in the spaces between adjacent tube openings 112. The pin openings 114 in the plate 110, on the other hand, being disposed in an otherwise imperforate plate, may be disposed in aligned tube rows as shown.

The tie pins 116 employed for connecting the ends of the plate members 82 to the

plates

110 and 110 in the disclosed arrangement are shown in FIGURES 12 and 13. Each tie pin 116 comprises a cylindrical shank por tion 118 of a diameter to be slidingly received in the pin opening 114 and an enlarged head portion 120. The head portion 120 is provided with opposed chordal flats 122 sized to be received within elongated slots 124 provided at the lower ends of the plate members 82 to facilitate welded attachment of the pins to the plate members. As shown, each plate member 82 is provided with a pair of oppositely spaced tie pins 116 to insure alignment of the plate members 82 within the narrow space defined between each row of tubes.

By means of the novel tube support structure of the present invention, there is provided a simple, inexpensive apparatus operative to effectively support the laterally extending portions of the U-tubes that occupy the upper region of a tube bundle against the damaging effects of flow-induced and/ or mechanically induced vibration. Examination of FIGURES 2 through 5 of the drawing indicates that with the tube support structure 80 assembled in the tube bundle 40, the receptacles 88 of each plate member 82 are adapted to receive and spacingly support the connecting portion '68 of each tube 38 in the associated tube layer. Vertical support for each tube, in both the upward and downward direction, is provided by the engagement of the tube by the opposed arms 92 of each receptacle. Lateral spacing of the tubes in each tube layer is provided by the engagement on opposite sides of the tubes by the opposing surfaces of adjacent plate members 82. The spaced relation between adjacent plate members 82 is augmented by the abutment of the rear surface of the adjacent plate member by the ends of the arms 92 of the next adjacent plate member. In the arrangement disclosed, thermally-induced, relative movement between the tubes of the tube bundle and the shell is accommodated by the floating connection provided between the tube support structures 80 and their associated support ele- 7

ments

96 and 110 or 110. Additionally, both heat transfer efliciency and fluid flow efiiciency are maintained at a high degree due to the presence of suflicient flow area through the tube support structures due to the alternately spaced disposition of the tube receptacles 88 along the side edges 84 and 86 of the plate members 82.

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

What is claimed is:

1. In heat exchange apparatus of the type including a tube bundle housed within a pressure shell, said tube bundle comprising a plurality of spaced tube layers each including a row of aligned, mutually spaced, parallel heat exchange tubes, the improvement comprising tube support structure for suspendedly supporting the tubes of said tube bundle in mutually spaced relation, said tube support structure comprising:

(a) elongated plate members having laterally spaced side edges engagingly disposed between each of said tube layers, said plate members being alignedly arranged along a plane intersecting the planes of said tube layers;

(b) a plurality of tube receptacles alternately vertically spaced along the side edges of said plate members, said tube receptacles comprising lateral, coplanar projections of said plate members having forwardly offset, opposing arms formed from oppositely spaced portions of said projections for supportingly engaging the tubes of said tube bundle; and

(c) means for attaching said plate members in mutually fixed relation.

2. Tube support structure as recited in claim 1 wherein the armsI of said tube receptacles have their end edges in abutting relation with thenext adjacent plate member.

3. In combination, a shell and tube type heat exchanger comprising:

(a) a substantially closed vessel;

(b) a bundle of inverted, generally U-shaped heat exchange tubes housed in said vessel, said heat exchange tubes being disposed in mutually spaced layers each including a row of aligned, mutually spaced, parallel tubes;

(c) a tube sheet disposed transversely of the axis of said vessel and containing tube seats for attaching the ends of said tubes;

((1) bafile plate means concentrically disposed between the wall of said vessel and said tube bundle defining an inner vapor generation chamber and an annular downcomer passage;

(e) means for passing heating fluid through said tubes;

(f) means for passing vaporizable fluid through said vapor generation chamber in heat exchange relation with said heating fluid;

(g) tube support structure for suspendedly supporting the connecting portions of the tubes of said tube bundle in mutually spaced relation, said structure including:

(i) vertically elongated plate members having laterally spaced side edges spacingly disposed between each of said tube layers, said plate members being arranged in a row intersecting the planes of said tube layers;

(ii) a plurality of formed tube receptacles alternately vertically spaced along the side edges of said plate members, said tube receptacles including means for supportingly engaging the connecting portions of the tubes of the next adjacent tube layer and comprising lateral, coplanar projections of said plate members having forwardly offset, opposing arms formed from oppositely spaced portions of said projections; and

(iii) means for connecting said plate members in mutually fixed relation.

4. The combination recited in claim 3 wherein the arms of said tube receptacles have their end edges in abutting relation with the next adjacent plate member.

5. The combination recited in either of claims 3 or 4 wherein said plate member attaching means comprises:

(a) structural means disposed above the upper extent of said tube bundle and extending transversely of said vapor generation chamber in parallel, overlying relation to said tube support structure;

(b) means for attaching the opposed ends of said structural means in fixed relation to said vessel;

(c) a vertically elongated suspension plate extending substantially collaterally with said tube support structure;

(d) means for fixedly attaching the upper ends of said plate members to said suspension plate; and

(e) means for connecting said suspension plate to said structural means for expansible movement therebetween.

6. The combination recited in claim 5 including means for securing the lower ends of said plate members in mutually spaced relation, said means comprising:

(a) an attachment plate fixedly secured with respect to said vessel in underlying relation to said tube support structure;

(b) means forming longitudinally spaced openings in said attachment plate; and

(c) tie pin means fixedly secured to the lower end of each of said plate members, each of said tie pin means having a shank portion slidably received in an associated opening.

References Cited UNITED STATES PATENTS 2,175,555 10/1939 Brown 122510 2,508,247 5/1950 Giauque 160 X 2,980,404 4/1961 Andersen et al. 165172 3,199,582 8/1965 Vogt et a1. 165-69 3,262.428 7/1966 Romanos 122-34 3,286,767 11/1966 Evans 165163 X FOREIGN PATENTS 1,517,138 2/1968 France.

ROBERT A. OLEARY, Primary Examiner A. W. DAVIS, Assistant Examiner U.S. Cl. X.R.