|Publication number||US3545534 A|
|Publication date||Dec 8, 1970|
|Filing date||Nov 29, 1968|
|Priority date||Dec 1, 1967|
|Also published as||DE1811586A1|
|Publication number||US 3545534 A, US 3545534A, US-A-3545534, US3545534 A, US3545534A|
|Inventors||Harold John Coles|
|Original Assignee||Atomic Power Constr Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (25), Classifications (10)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent Inventors Harold John Coles Kenton, Harrow, England; Assignee Atomic Power Constructions Limited, Sutton, Surrey, England, a British company Appl. No. 779,898 Filed Nov. 29, 1968 Patented Dec. 8, 1970 Priority Dec. 1, 1967 Great Britain No. 54900/67 HEAT EXCHANGERS 4 Claims, 15 Drawing Figs.
US. Cl. 165/67. 122/510, 165/162, 165/163 Int. Cl. F281 9/00 Field of Search 165/ l 62, 67, 1631; 122/510  References Cited UNITED STATES PATENTS 1,852,363, 4/1932 Parent 165/162 2,980,404 4/1961 Andersen et al 165/ l 62X 3,286,767 1 l/ 1966 Evans 165/162X Primary Examiner-Albert W. Davis, Jr. Attorney-Holcombe, Wetherill & Brisebois ABSTRACT: A heat exchanger comprising helically wound tubes mounted upon a support structure comprising striplike support members apertured and slottedl at intervals along their length, and attachment members which are mounted upon the support members by entering arms on the attachment members through the slots and sliding the former to a desired position on the support member. The attachment members have supporting surfaces .for receiving the tubes and a boss which fits into an aperture intoan adjacent support member.
1. HEAT'Excr ANGERs BACKGROUND To THE INvENIIoN I unit volume, such heat exchangers have found only limited application because the cost of assembly is prohibitively high. The tubes must be supported to. maintain them in a required,
.fixed relationship and it is known to use a support assembly comprising three support platesdisposed radially with respect to the axis of the helically wound tubes. Each plate has a matrix of holes drilled in it at spaces corresponding to the helix lead and to thelateral spacing of adjacent helices. The radially innermost tube helixi s fitted by rotating it axially and feeding its leading end in succession through the corresponding holes in the three support plates. A weld or some other mechanical lock is formed, at each hole, between tube and plate, and the process is repeated for each tube helix until the entire heat exchanger has been built up. Such a method is clearly extremely time-consumingand therefore costly.
Similar problems arise in heat exchangers whose tubes are in other configurations than helical although sometimes in a less acute form. w I v e It is an object of the present invention to provide a construction of heat exchanger which is easier and cheaper to assemble than the construction just described.
SUMMARY OF THE INVENTION A heat exchanger according to the invention comprises a plurality of tubes, a plurality of support members arranged substantially transversely of the tubes and. a plurality of attachment members securing the tubes to the support members, the tubes being arranged in parallel layers with support members between adjacent layers, and the attachment mem bers of one layer of tubes beingused to carry the support members of the next adjacent layer of tubes.
The attachment members may comprise clips adapted to I secure one, two or more adjacent tubes to the support.
The heat exchanger may comprise a plurality of tubes, a plurality of support members, arranged substantially transversely of the tubes and a plurality of attachment members securing the tubes to the support members. In one example of the invention the tubes are provided substantially in the form of helices.
The terrir helix is not used in a strictly mathematical sense but is intended to cover any generally helical configuration whether of circular transverse cross section or square, rectangular, elliptical or other shape. Moreover, a tube of helical form may be deliberately distorted in different directions at successive points of support along its length, in order to induce position retaining stressing atthe support points in order to derive a position retention force; such systems are described in greater'detail in copending application 37398168.
The attachment membersmay consist of clips having one or w more curved parts which engage thetube and a base part which is secured to the support member. The clip may be. of integral construction or the curved part or parts may be separate from the base part.
The or each curvedpartmay be resilient. Preferably, each clip is so formed that it has a surface for receiving a support memberof the next adjacent group. For
' sembly, FIGS. 10, 11 and 12 are front,
example the support members may be strips apertured at regular intervals in which case the clips may have bosses, a support The tubes may contain fissile material in which case the heat exchanger becomes a fuel element which may be helical. In this case heat is exchanged between the fissile material and coolant circulated past the tubes.
One method of assembling a heat exchanger embodying the invention comprises the steps of temporarily positioning a first group of support members entering a first substantially helically wound tube over the first group, securing the first helix to the support members of the first group, positioning a second group of support members round and spaced from the first tube, entering a second substantially helically wound tube over the second group, and securing the second tube to the support members of the second group.
According to thismethodthe heat exchanger is built outwards by starting at an innermost point, adding intermediate tubes and fixing the outermost tubcfllast of all.
Alternatively, construction may proceed in an inward direction. The first tube to be positioned would thus be the outermost one. This method comprises the steps of temporarily positioning a first group of support members, entering a first substantially helically wound tube into the first group, securing the first tube to the support members of the first group, entering a second group of support'members into the first helix, entering a second substantially helically wound tube into the second group of support members, and securing the second tube to the support members of the second group. 7
If a helixjntermediate between the inner and outer helixes is chosen as the starting point, construction may be carried out by the use of both methods concurrently or sequentially. It should be noted that the choice of construction method is not necessarily related to the type of attachmentu'sed for fixing the tube to the support strip.
' BRIEFnEscRIPTIoN'oETIIE DRAWINGS FIG. 1 is an end view of a first embodiment in diagrammatic form only, a 7
FIG. 2 is a section on the line'II-III of FIG. 1,
FIGS. 3 and 4 are front and side views respectively of part of a support member,
FIG. 5 is a section on the line V-V of FIG. 3,
FIGS. 6, 7 and 8 are top, side and front views respectively of an attachment member,
FIG. 9 is a side view of part of the: first embodiment after asplan and side views respectively of part of another-form of attachment member,
FIGS. 13, 14 are side and front views respectively of another part of the other form of attachment member, and
FIG. 15 is a side view of part of the second embodiment after assembly. 1
DESCRIFIION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show an assembled heat exchanger in diagrammatic form only. The heat exchanger comprises an outer cylindrical shell 1 and an inner cylindrical shell 2 interconnected at their ends by three radial beams 3. The annulus defined by the shells l, 2 contains a plurality of coaxial heli cally wound tubes 4 each of whichis supported by a group of support members each comprising an elongated strip 5 suspended from the uppermost beams 3. Each tube is attached to the support member of its supporting group by attachment means not shown in FIGS. 1 and 2.
It should be noted that the various helically wound tubes may or may not be interconnected, that they may be of differing lead, that is, helix angle, although the pitches are preferably the same, and they may or may not extend the full length of the boilers. It is not necessary that the helices should all be wound in the same direction. I
Referring first to FIGS. 3 4 and 5, each elongated support member comprises along stainless steel strip 6 having holes 7 drilled through it at regularly-spaced intervals. In section the strip is stepped along each long side as at 8 in FIG. 5 and the known as Nimonic 80A has curved tube grips which extend from a central part 1 l which is slotted as at 12, theends of the part being intume'd as at 13. The face of the clip is stepped as at 14 and has a central boss 15 beveled at 16 whose height is just slightly less than the maximum thickness of strip 6.
To assemble the heat exchanger, the innermost helically wound tube is dealt with first. Three strips 6 are to be used to support the helix and these strips are held temporarily in the positions they will occupy on completion of the entire assembly. The helix is'then slid down over the three strips and temporarily supported in position. Tube support clips are then engaged with the helix by springing the grips 10 over adjacent turns of the helix close to the point of attachment to the support plate and thenmounted upon the latter by passing the inturned ends 13 through a convenient slot 9 and sliding the clip along the strip until the attachment point is reached. This process is repeated until all the turns are clipped to each support plate every time they pass it. This is shown in FIG. 9 where adjacent turns 17, 18, 19 and 20 of the helix are clipped b'y clips 21 and 22 to a support strip 23.
t The three further support strips are now assembled by positioning them so that the bosses 15 of the clips already in position mate with the holes 7 of the further strips. The further support strips are now attached, preferably by welding, to the bossesofthe innermost layer of clips. The next innermost I j-xhelix is then slid over the three further support strips and fixed to thela'tter by further clips. This is shown in FIG. 9. Adjacent turns of the next innermost helix are shown at 24, 25 and 26 and are'clipped to support strip 27 by clips 28, 29 the support I strip 27 having been welded to the bosses of clips 21, 22 as indicated at 30.
The procedure is then repeated for each succeeding helix. FIG. 9 shows turns of two further helices 31, 32 secured by clips 33, 34 to support strips 35, 36 respectively.
' The inner shell is then inserted through the assembled helices, and the outer shell positioned round the helices. The radialbeams are then placed in position and secured to the shells and to the support strips.
The attachment clip need not be of integral construction and an alternative clip of two part construction will now be described.
The clip has a body part 37 shown in FIGS. 10, 11 and 12 having a slot 38 and intumed ends 39. A boss 40 extends centrally from face 41 of the body.
The grip portion of the clip is separate and is shown in FIGS. 13 and 14. It comprises a metal sheet 42 bent into the form of a shallow U and has a central hole 43.
clearance fit'between the clip body part 37 (or grips l0) and the support strip 44 in view of the risk of corrosion fretting occurring at the contactin surfaces. One wa in which this may be achieved IS to weld e body parts 37 or grips 10) to the support strips 44 at a number of staggered positions, and, at the remaining positions, to dispense'entirely with the stirrup" connection to the adjacent strip. Thus, all. potential fretting is eliminated, and, by leavingoutsome of the interconnections and staggering the remainder, a support system is built up which is flexible in the radial direction. This flexibility is desirable to prevent excessive stress, due to thermal expansion, being induced in the tubes. Such stress might otherwise occur because the thermal expansion of the support members (having a temperature range of room temperature to primary heat transfer temperature) is greater than that of the tubes (which have a temperature range of room temperature to secondary heat transfer temperature). The relative expansions of the tubes and support members will also depend on the ,difference between the thermal properties of the materials from which they are constructed. I
The embodiments described above are vertically orientated, but the invention is obviously applicable to any orientation; for example, ifthe axis was horizontal the tube support plates would either be considerably strengthened, or would be supported intermediate their ends.
The tube clips illustrated both hold adjacent turns of a helix; clearly each turn could have a single clip, or more than two adjacent turns could be supported by a single clip.
The invention has been described in relation to asystem in which the innermost coil is. positioned first; given a large It will be understood that regularity of the lead and pitch of the helices is not essential. The support system can readily beadapted to support helices of irregular lead and pitch.
1. A heat exchanger comprising in combination a first layer of tubes, a fust series of support members of elongated form disposed transversely with respect to the tubes of the first layer, first attachment members mounted on the support members and carrying the tubes of the first layer, a second layer of tubes, a second series of support members'of elongated form disposed transversely with respect to the tubes of the second layer, the support members of the second series Conveniently, the body of the clip is of stainless steel whilst I positive jointing operative has been performed up to this stage to assemble the two part clip.
The second row 46 of support strips is positioned by engaging the holes therein with the bosses 40. The bosses 40 are now welded to the second support strips 46, this weld thus forms the dual function of attaching the second support strips to the assembly, and of attaching to each other the two parts of the clip. lt may be preferable, for example when the external heat transfer fluid is a reactor coolant gas, and for where the boiler is relatively inaccessible, to avoid the loose or being carried by the first attachnient members, second attachment members mounted upon the support members of the second series and carrying the tubes of the second layer support members being of striplike form and having slots at spaced intervals along the length of the strip, and said attachment members having inturned parts adapted to be entered through said slots in order to mount the attachment members on the support member. s
2. A heat exchangeras claimed in claim 1 in which the support members are apertured at spaced intervals along their length, and in which the attachment members have bosses which locate in the apertures to enable the attachment'rnembers to carry support members.
3. A heat exchanger as claimed in claim 2 in which each attachment member consists of a curved part which engages a tube and a base part by which the attachment member is mounted upon a support member.
4. A heat exchanger as claimed in claim 2 in which each 'a't-f" tachment member consists of a first curved part which en-. gages a tube and a second base part separate from the first part and by means of which the attachment member is mounted upon a support member.
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|U.S. Classification||165/67, 122/510, 165/162, 165/163|
|International Classification||F28D7/02, F28F9/013|
|Cooperative Classification||F28F9/0132, F28D7/024|
|European Classification||F28D7/02D, F28F9/013D|