GB2184223A

GB2184223A - Coiled tube heat exchanger

Info

Publication number: GB2184223A
Application number: GB08623394A
Authority: GB
Inventors: Heinrich Steins
Original assignee: Draack & Meyer Polytetra
Current assignee: Draack & Meyer Polytetra
Priority date: 1985-09-27
Filing date: 1986-09-29
Publication date: 1987-06-17
Also published as: FR2588071A1; DE3632777A1; FR2588071B3; GB8623394D0; CH671096A5; GB2184223B

Abstract

A heat exchanger suitable for use with corrosive media has at least one plastics non self-supporting tube 8, for example of fluoroplastics, guided in helical turns, which are circular or non-circular in plan view, by a supporting structure comprising at least one plate element (6) extending in the longitudinal direction of the pitch of the helical turns, and the helical turns passing through passages in the plate elements 8 which passages are positioned according to the pitch of the turns. In the form shown, the bend portions of the coil are supported by grooved supports (Figures 3, 4). The coil(s) may depend from a lid of a vessel in which the coil(s) are immersed (Figures 9, 10). <IMAGE>

Description

SPECIFICATION Heat exchanger The invention relates two a heat exchanger suitable for use with corrosive media.

Heat exchangers in the form of so-called "nest exchangers" are known wherein a plurality of flexible tubes ortubes extend parallel to one another between two head members. These nest exchangers thus comprise a plurality of inlets and outlets. The resulting large numbers of connections involves a certain riskduring maintenance or repair.

Furthermore, in the known nest exchangers flow is in only one direction, that isto say the medium flows in atone head member, th rough theflexibletubes, and out again at the other head member.

Furthermore, heat exchangers are known having tubes of metallic materials, for example titanium, disposed in theform of a helix. Such heat exchangers are used, for example, by immersion in a vessel which contains a medium to be heated or cooled, such as a liquid. In this case, the tubes are self-supporting. This has the advantage of satisfactory heat exchange with small space requirements.

Since tubes of plastic material for corrosive media, particularlythose on the basis offluoro-plastics, are not self-supporting, heat exchangers constructed helically have not hitherto been known. Heat exchangers using non- self-supporting plastics tubes are known with a worm-like, spiral or meandering flexible tube in a single plane. But it is a disadvantage in this case that the heat exchanger takes up a relatively large amount of space.

It is the object of the invention to provide a heat exchangerwhich is compact in construction so that it can be accommodated in a small space.

According to the invention, there is provided a heat exchanger suitable for use with corrosive media, having at least onetube of plastics material which isnonself-supporting,whereintheflexible tubeorthetube is guided in helical turns,which are circular or non-circular in plan view, buy a supporting structure, and the supporting structure comprises at least one plate elements which extend in the longitudinal direction ofthe pitch ofthe helical turns, wherein the helical turns pass through passages in the plate elements and the passages are positioned according to the pitch of the turns.

In a preferred form, the heat exchanger has a plurality of plate elements held spaced apart bya pluralityofspacing rods.

Preferably the plastics material isfluoroplastics.

The turns are held and/orsupported by the supporting structure which preferably likewise consists of plastics material, particularly of fluoroplastics,sothata compactformof construction is possible, usable with corrosive materials, with small space requirements.

In a preferred form of embodiment of the heat exchanger, it is provided that the non-circularturns are "elongated" in construction in such a manner that each individual turn comprises two regions disposed substantially parallel opposite one another and connected at each end by substantially semicircular portions offlexibletube. Forthis purpose, the invention provides that the supporting structure comprises head members, which are held by a plurality of spacing rods in the same direction and substantially equal in length, to reverse the flexible tube, and plate elements acting as supporting and spacing elements are disposed on the spacing rods at intervals between the head members.By this means, guiding oftheflexibletube is rendered posiblewith a plurality of portions of flexible tube disposed in the same direction, while the effect is achieved, bythe reversal oftheflexible tube at the head members in each case, that the portions of flexible tube are each part of a single continuousflexibletube.Thustheportionsof flexible tube can extend, for example, in a plurality of planes disposed at a short distance apart. The planes may be disposed parallel to one another or transversely to one another.In this manner, a heat exchanger is provided which is particularly suitable for application for which the use of heating rods or heating plates was hitherto necessary because a small volume is needed forthe heat exchanger as a result of the particularly compact form of construction which can be achieved according to the invention.

In an appropriate development ofthe invention it can be provided th at the head members comprise a plurality of return guides, provided side by side and/orone above the other,fortheflexibletube. The reversing guides are appropriately constructed in the form of groove-shaped beds for the flexible tube, separated from one another by webs and preferably extending over a reversing region of about 180 .

These tube beds prevent the plastics flexible tube, which is comparatively "soft" in comparison with other materials, from collapsing underthermal loading, particularly as atight reversal oftheflexible tubes (about 180 ) would be critical without a supporting bed.

According to a furtherfeature ofthe invention, it can be provided that the plate elements are constructed in the form of plates or discs. This improvement involves a particularly simple construction and renders possible an effective and protective holding oftheflexibletube.

Since an outer protective web is formed as a result ofthe passages constructed intheform of openings, contact between the flexible tube and the bottom or the wall of a vessel receiving the heat exchanger is prevented as a result.

According to a further feature ofthe invention, it can be provided that the spacing rods engage through openings in the supporting and spacing elements and are each located by means of clamping and/or screw elements. It is particularly appropriate if the spacing rods comprise clamping groovesto receive clamping elements.

It may a Iso be providedthatthespacing rods are divided in the longitudinal direction and are connected by screw connections atthe end faces adjacentto one another.

In afurtherdevelopmentofthe invention, it can be provided that the spacing rods are screwed to the head members.

According to a furtherfeature ofthe invention, it can be provided that a supporting leg is provided on at least one head member. Such a supporting leg prevents direct contact between the turns of the flexible tube and the bottom orwallsofvesselsorthe like receiving the heat exchangers. It is naturally also possible to mountthe heat exchanger on such a supporting leg. In this manner a vertical installation is possible and in addition,the supporting leg can serveasaspacing means,forexampletokeepthe heat exchanger outside the silt region covering the bottom in a silted-up bath.

Afurther advantage of the invention consists in the fact that a plurality of heat exchangers according to the invention can easily be bunched together in cascade form.

Afurtherdevelopmentoftheinvention relates to a heat exchangerwherein at least one plastics flexible tube ortube is guided in turns which are circular in plan view likethewinding of a helical spring and is held by a supporting structure. In this case, the supporting structure comprises a plurality of strut-shaped flexible-tube holding means which extend radially round an imaginarycentral longitudinal axis and are disposed in the direction of this axis and which are mounted on an end holding means (for example a cover) at least atone oftheir common end faces. The strut-shaped flexible-tube holding means are constructed in the form of holding plates which are provided with bores forthe passageoftheflexibletubeandaresupportedin relation to one another by spacers.

It is an advantage that, as a result of the supporting structure,theflexibletube ortube ortheflexible tubes ortubes are offered stability and support in an arrangement in theform of helical lines with circular turns so that a compact heat exchanger is provided which can be accommodated in a narrow space. The end holding means is preferably constructed in the form of a coverwith connections or passages forthe flexible tubes ortubes. The cover can easily be adapted to the opening of a vessel in which the heat exchanger is to be introduced. In this manner, a compactunitofsimple construction results.

In further development ofthe invention,the strut-shaped flexible-tube holding means can be constructed in the form of holding plates which are provided with boresforthe passage oftheflexible tube and which are supported in relation to one another by spacers. The spacers are preferably constructed in the form of segments of a circle.

In a further development ofthe invention, holding means are provided to mou ntthe strut-shaped flexible-tube holding means on the end holding means and are in turn connected to the end holding means,forexamplethecover.

If the holding means are mounted directly on the end holding means preferably constructed in the form of a cover, then theflexible-tube arrangement in the form of a helical linefollows directly on the "under side" of the cover. Such a heat exchanger is appropriate if the container into which it is to be introduced is completelyfilled with a medium to be heated or cooled.

It is also possible, however, to provide that the flexible-tube holding means are mounted on the end holding means,thatistosaypreferablythecover, through extension elements. The extension elements may possibly themselves be made adjustable in length. In this manner, the heat exchanger may be disposed with spacing from the end holding means. This is appropriate if the heat exchanger is to be immersed in a vessel which is filled not completely but only partially with a medium to be heated orcooled.

There is naturally also the easy possibility of providing an end holding means at both ends ofthe supporting structure.

The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawings.

Figure 1 shows a diagrammatic side view of a heat exchanger according to the invention; Figure2 shows a plan view ofthe arrangement according to Figure 1; FigureSshowsa plan view of a head member, partially in section; Figure 4shows a side view of the head member shown in Figure 3; Figure5shows a sideviewofa supporting and spacing element of plate-shaped construction substantially on the line V-V in Figure 2; Figure 6shows a side view of a spacing rod; Figure 7shows a diagrammatic illustration of an embodiment of the connection between a spacing rod and a plate-shaped supporting and spacing element; Figure 8shows a clamping element used forthe connection in an arrangement as shown in Figure 7, in end view and sideview; Figure9showsadiagrammaticsideviewofa further embodiment ofthe invention;; Figure 10 shows a side view of a yet further embodiment ofthe invention wherein the heat exchanger is mounted, via extension elements, on an end holding means constructed intheform of a cover; Figure 11 shows a view of the holding meansfor theform of embodiment shown in Figure9 in an exploded view; and Figure 12 shows a view of the holding means with extension elementsforthe embodiment shown in Figure 10, in an exploded view.

A heat exchanger illustrated diagrammatically in Figure 1 and Figure 2 comprises a supporting structure with head members 2 and 3 at the ends which head members are held atthe end faces bya pluralityofspacing rods 4, 5which are parallel and substantially equal in length and are disposed spaced apart from one another. Supporting and spacing elements 6 of plate-shaped construction are mounted on the spacing rods at intervals between the head members 2 and 3. As can be seen from Figure4 in particular, the head members 2,3 comprise a plurality of reversing guides 7, disposed one above the other and/or side by side, to receive a flexible tube 8.

The reversing guides 7 are constructed, in the embodimentshown,intheform of groove-shaped beds forthe flexible tube, which are separated from one another by webs 9.

The supporting and spacing elements of plate-shaped construction comprise bores 10, the diameter of which corresponds to the external diameter of the spacing rods 4,5. In the embodiment shown, four bores 10 are provided disposed with spacing apart. Accordingly the arrangement shown comprisesfourspacing rods 4,5 of which onlytwo spacing rods are visible in Figure 2.The connection ofthe spacing rods to the plate-shaped supporting and spacing elements 6 is effected by means of clamping elements 11 which are of slit construction and engage in grooves 12 which are distributed over the length ofthe spacing rods so that the spacing between two grooves l2correspondingtothe thicknes ofthe supporting and spacing elements 6 of plate-shaped construction.

At the ends, the spacing rods comprise tapped bores 13 attheirend faces. The securing ofthe head members 2 and 3 is effected by means of screws (not illustrated) which engage in correspondingly constructed screw holes 14 in the head members.

The head members then bearagainstsupporting and spacing elementsattheends,which elements are located at the inside by clamping elements 11.

The above supporting structure, consisting of plastics material, serves to receive a flexible tube 8 which - as can be seen from Figure 1 and Figure 2 comprises regions guided parallel to one another in turns disposed close together, one above the other, with reversing regionstaken round the head members 2,3 atthe ends. In the embodiment shown, the ends A and B ofthe flexible tube are both at one end.

The end B of the flexible tube could naturally also be disposed at the opposite side. Theflexibletube 9, - beginning with the top or bottom turn - is taken through passages 15 in the supporting and spacing elements 6, which passages are each disposed at substantially the same height, and is received in the head members by the groove-shaped tube beds 7.

Both the supporting structure andtheflexibletube consist of plastics material, particularly of fluoroplastics.

In further embodiments shown In Figures 9 to 12, a supporting structure designated as a whole by 21 comprises holding plates 22, 23 and 24as well as a further holding plate (not illustrated in Figure 9). The holding plates are positioned round an imaginary central longitudinal axis 25 in its longitudinal direction and extend radially outwards, that is to say, in the embodiment shown, with four plates in a cross-shaped arrangement when viewed in a section across the central longitudinal axis 25.

The holding plates are supported in relation to one another by spacers 28 and 29 which are constructed intheform ofsegmentsofa circle. Provided inthe strut-shaped flexible-tube holding means constructed in the form of holding plates are a plurality of bores through which flexible tubes or tubes (not illustrated) of plastics material, particularlyfluoroplastics, can be arranged in the form of a helical line, that isto say, in principle, in the mannerofan immersion heater. In the example of embodiment shown, the supporting structure serves to receive two plastics flexible tubes/tubes to be disposed in the form of helical lines.Accordingly, fourflexible-tube connections 31,32,33 and 34 are provided.The flexible tubes are diagrammatically designated by 35,36,37 and 38.

Thearrangementoftheflexibletubesintheform of a helical line is not illustrated forthe sake of greater clarity.

The flexible-tube connections 31 to 34 are mounted on an end holding means 39 constructed in the form ofacoverand are constructed so that connecting flexible tubes can betaken furtherfrom the top ofthe cover (as shown in Figure 9). Holding means 40, one of which is illustrated on a largerscale in Figure 11, are provided to connectthe strut-shaped flexible-tube holding means 22,23,24 ofthe supporting structure to the cover 39. The holding means 40 comprise a bolt41 with an external thread 42 on which a nut 43 can be screwed afterthe bolt41 has been passed through the cover 39 from the underside.The head 44, which isthenatthe under side of the cover, comprises a slit 45 which is so constructed that one of the holding plates22,23, 24 can be introduced into the slit and be located by means of a screw which engages through a transverse bore 46.

The heat exchanger shown in Figure 9 may, for example, be immersed in a vessel with a liquid, the cover39closingtheupperopening inthevessel.

The modification ofthe invention described below with referenceto Figure 10 and Figure 12 differsfrom the embodiment shown in Figure 9 and Figure 11 only by holding means of a different formation for the connection between the supporting structure 21 and the cover39. As can be seen from Figure 10, the holding means designated there by47 are adapted for longitudinal adjustment in the direction ofthe arrow C. Here three holding plates 22,23,24 are seated in slits 45' in an element 48 which comprises a bore 49 with an internal tap 50 in which an external thread 51 of an extension member 52 can be screwed which is in turn pushed, with its upper end comprising an external thread 53, through the cover 49 where it can be secured from above buy a nut 54.

The other parts according to Figure 10 correspond to the parts described with reference to Figure 9 and are thereforenotexplained again.Theform of embodiment shown in Figure 10 is suitable when the medium to be heated orcooled does not fill the whole container in which the heat exchanger is to be inserted, but only a portion of the container. By means of the extension elements, the arrangement can be selected so thatthe actual heat exchanger is immersed in the medium.

Claims

1. A heat exchanger suitable for use with corrosive media, having at least one tube of plastics material which is non self-supporting, wherein the flexible tube orthetube (8 or35to 38) is guided in helical turns, which are circular or non-circular in plan view, by a supporting structure, and the supporting structurecomprises at leastone plate elements (6 or 22 to 24) which extend in the longitudinal direction ofthe pitch ofthe helical turns, wherein the helical turns pass through passages (15 or 30) in the plate elements and the passages are positioned according to the pitch oftheturns.

2. A heat exchanger as claimed in Claim 1 wherein a plurality of plate elements are held spaced apart by a plurality of spacing rods (4,5).

3. A heat exchanger as claimed in Claim 1, wherein the supporting structure comprises head members (2, 3),which are held bya pluralityof spacing rods (4,5) which lie parallel and are substantially equal in length, said tube passing around the head members to reverse its direction.

4. Aheatexchanger as claimed in Claims2 and3 wherein the rods serve to hold both the plate elements and the head elements.

5. A heat exchanger as claimed in Claim 3 or4, wherein in that the head members (2,3) comprise a plurality of reversing guides forthe tube, which are provided side by side or one above the other.

6. A heat exchanger as claimed in Claim 5, wherein the reversing guides are constructed in the form of groove-shaped beds (7) for the tube, which are separated from one another by webs (9).

7. A heat exchanger as claimed in Claim 6, wherein the beds (7) forthetube extend over a reversing region of about 180".

8. A heat exchanger as claimed in any preceding Claim wherein the plate element(s) (6) are in theform of plates or discs.

9. A heatexchangeras claimed in any of Claims 2 to 8, wherein the spacing rods (4,5) passthrough openings (10) in the supporting and spacing elements and are each located by means of clamping elements (11) and/or screw elements.

10. A heat exchanger as claimed in Claim 9, wherein the spacing rods comprise clamping grooves (12) to receive the clamping elements (11).

11. A heat exchanger as claimed in any of Claims 2to 10, wherein the spacing rods (4,5) are divided in the longitudinal direction and are connected by screw connections at the end faces adjacent to one another.

12. A heat exchanger as claimed in one ofthe Claims 1 to 11, wherein the spacing rods (4,5) are screwed to the head members(2,3).

13. A heat exchanger as claimed in any of Claims 1 to 12, wherein a supporting-leg device is provided which can be fitted to the heat exchanger (1) laterally or atthe end.

14. A heat exchangeras claimed in Claim 1, wherein the supporting structure (21) comprises a plurality offlat elongate tube holding means (22,23, 24) which are disposed radially round an imaginary central longitudinal axis, extend parallel to the direction of this axis, and are mounted on an end holding means (cover 39) at least at one oftheir common end faces, and wherein the holding means have bores (30) forthe passage of the tube, and are supported in relation to one another by spacers (28, 29).

15. A heat exchanger as claimed in Claim 14, wherein the end holding means is constructed in the form of a cover (39) with connections (31 to 34) or passagesforthetubes/tubes.

16. A heat exchanger as claimed in Claim 14 or 15, wherein the spacers are constructed in the form of segments of a circle.

17. A heat exchanger as claimed in one ofthe Claims 14to 16, wherein thetube holding means are secured, at their end face adjacent to the end holding means (39), to holding means (40) which in turn are connected to the end holding means (39).

18. A heat exchanger as claimed in Claim 17, wherein the extension holding means (40) are mounted directly on the end holding means (39) or on the plurality of end holding means provided atthe end.

19. A heat exchangeras claimed in Claim 17, wherein the tube holding means is mounted on the end holding means (39) through extension elements (47) which may be adjustable in length.

20. Aheatexchangersubstantiallyasherein described with reference to the drawings.