CA1176626A

CA1176626A - Heat exchanger

Info

Publication number: CA1176626A
Application number: CA000404104A
Authority: CA
Inventors: Karl Reither; Rudolf Neuber
Original assignee: KUNSTSTOFFTECHNIK KG
Current assignee: KUNSTSTOFFTECHNIK KG
Priority date: 1981-06-02
Filing date: 1982-05-31
Publication date: 1984-10-23
Also published as: JPS5896A; DE3121838C2; DE3121838A1

Abstract

Abstract A heat exchanger is assembled from a plurality of tube-pieces, which are made of a thermoplastic material, and are arranged parallel to each other, and spaced apart, one from another, with tubular end-pieces connecting these tube-pieces. In this design, the tube-pieces are com-bined to form groups of four, and these groups are combin-ed, in their turn, to form tube-bundles. The spacings between the tubes of a tube-bundle are guaranteed by means of retaining plates, which are loosely pushed on, in a manner permitting shifting. A plurality of these tube-bundles can be superimposed to form a high-capacity heat exchanger, and these tube-bundles can be securely con-nected to each other by means of the retaining plates.
The process for manufacturing a heat exchanger of this type can take place in three steps:
1) Combination of four tube-pieces to form a tube-group.
2) Combination of a plurality of tube-groups, placed side-by-side, to form a tube-bundle.
3) Combination of a plurality of superimposed tube-bundles, to form a large heat exchanger.
(Fig.1)

Description

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1~th May,1982 D/Wi.

Kunststofftechnik KG
5210 Troisdorf , "Heat exchanger and process for its manufacture"
_____________ The invention relates to a heat exchanger be-tween a first liquid, on the one side, and a second liquid, or a gas or gas-mixture, on the other side, and to a process for its manufacture.
Heat exchangers are known, which comprise a plurality of straight tubes, arranged parallel to each other and at a distance one from another, through which the first liquid flows, and which are externally flooded by the second liquid, or by the gas or gas-mixture.
Depending on the application, all the tubes of a heat exchanger o~ this ~ype are connected in series, or else two or more tubes are, in each case, connected in paraIlel, and these groups are then connected in . ~
series. If, in order to produce an effective heat exchanger, it~is desired to locate as many tube-pieces as possible in a confined space, the connection of the ends of the tube-pieces, by means of appropriate tubular end-pieces, creates considerable difficulties, because a connection which is proof against leakage of liquid car. be produced only when, in producing the connection,

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free access is available to the joint, around the entire periphery of the tube-esld. This becomes particularl~
difficult when it is desired to manu~acture a heat exchanger of this type from plastic tubes, because the tube-p1eces are flooded, internally and/or externally, by aggressi~e media, which prohibit the use of metal tubes. Depending on the plastic used, a welded connection or a glued connection then comes into con-sideration~ the production of which poses problems, due to the small clearances between the ~ubes, which are even greater than in the case of metal tubes.
In heat exchangers of this type, particular difficulties can result if a joint proves to be leaky only after completion of the manufacture of the entire heat exchanger, or if a joint develops a leak at a later time. In general~ a subsequent leak-sealing operation inside the confined tube-bundle is no longer possible. In such an event, the entire heat exchanger must frequently be rejected, because a repair gives rise to higher costs than building-a completely new unit~
The object underlying the invention is to develop the design of a heat exchanger of the above-mentioned type, in which the tube-pieces and connections are made from a thermoplastic material, in such a manner that the manufacture of the heat exchanger is considerably simplified, and is thereby rendered less expensive, while, at the same time, the occurrence of leaky connections is virtually prevented, or is at least discovered immediately.

3 -~71~6;~6 The object is achieved, according to the in~en-tion, when the straight tube~pieces, which are made of a thermoplastic material, are arranged in groups, each comprising four tubes, their ends being connected, one - to another, in a manner proof against leakage of liquid, by tubular end-pieces ~hich are approximately U-shaped and are made of the same plastic, and when several tube-groups of this type are combined to form a tube-bundle, which is f.itted with connecting tube-sections ~or supply-ing and discharging the first liquid, the cohesion between the tube-pieces and the tube-groups being ensured by retaining plates, which are distributed over the length of the tube-pieces, are provided with holes, and are loosely pushed on to the tube-pieces in a manner per-mitting shifting.
`: While the manufacturing process will be dis-j ~ cussed again in more detail in the text which follows, it should already be pointed out, at this point, that the groups, which each possess four straight tube-pieces ~:~ and are combined by means of the tubular end-pieces, : : can be manufactured and stored, prior to.final assembly, .
as pre-manufactured assemblies, it also being possible, if desired, to carry out a leak-test on the joints.
In any case, the construction of a tube-bundle from tube-groups of this type, and the production of the joints at the tubular end-pieces, are greatly simplified by the fact that the resiliently flexible tubes can, after pushing the retaining plates together, be bent far apart from each other, thereby enabling ~76~;~6 the connections to be produced in a convenient manner.
The connections are preferably effected by welding, provided that the plastic is suitable for this technique, or by glueing. In order to be able to hold the four tube-pieces of a group at small distances one from another, and thereby to be able to accommodate a large number of tubes in a given space, the tubular end-pieces are nested into each other, in each case in pairs, the one tubular end-piece engaging around the bend of the other.
A tube-bundle of this type, assembled from several tube-groups, is already suitable for use as a heat exchanger, for example by placing it, or suspending it, in baths which must be held at a specified temperature.
On the other hand, a tube-bundle of this type can be installed in a duct, and can be flooded, at right angles to the tube axis, by a stream of air or gas. If, in the case of an application of this type, it is desired to increase the number of the tube-pieces, and thereby to increase the total heat-exchange area, it is proposed that a heat exchanger be assembled from several superimposed tube-bundles 9 the retaining plates then additionally bringing about the cohesion of the superimposed tube bundles, over and above their func-tion as spreaders. For this purpose, the retaining plates are provided with grooves at their ends, and are pushed into corresponding rebated ledges on the longitudinal edges of supports, whi~h are securely located, at in-tervals, on a base plate. A heat exchanger of this ~/

1~76626 type, comprising several tube-bundles, then possesses, in addition, a casing, which is provided with flange~
at both its ends, and which can be inserted into an appropriate duct for carrying air or gas.
The invention further relates to a process for manufacturing a heat exchanger of the abovementioned type. This process pushing two tubular end-pieces, engaging one around the other, on to the four tube-pieces of each tube-group, at one end thereof, and connecting these tubular end pieces to the tube-pieces, the retaining plates then being pushed on to the other, free,ends ofthb tube-pieces of allthe tube-groups of a tube-bundle,the tubularend~pieces t~enbeing slippedon tothe free ends of the tube-pieces and being connected thereto, and, finally, the connecting--tube-sections being slipped on to the two tube-ends which rem~in open, and being connected thereto, the connections being produced by welding or glueing, depending on the plastic used.
If the process is initially carried out only as far as the manufacture of tube-groups, as an intermediate product,a comparativelylarge number of thesetube-grou~s can be stored, if appropriate in several commonly used lengths, and called up as needed. The second part of the process then comprises the assembly of tube-bundles from tube-groups of this type. The tube-bundles, manufactured in this way, can also be put into intermediate storage, and can either be installed singly, for example for ~arming or cooling baths~ or can be installe~ as multiple assemblies, depending on 2~;

the requirement. On installation, the tube~bundles are already checked for leak-tightness, for example by pressurising them under water.
The process for manufacturing a heat exchanger from a plurality cf tube-bundles of this type then takes a very simp~le form, according to the invention, in that the tube-bundle retaining plates, which are provided, according to the invention,with grooves at -their ends, are pushed into -the rebated ledges of supports, which are attached, in an appropriate arrangement, to the baseplate ofa duct-section which is still open.
Finally, the side wall is fitted, the connecting tube-sections projecting through openings in the side wall, and these through-passages are rendered leak-proof.
The connecting tube-sections of the tube-bundles are then connected to each other by means of manifold lines.
In the text below, the invention, in illustrative embodiments, is explained in more detail, by reference to the drawing, in which:
Fig.l shows a partially broken-open plan view of a ; heat exchanger, according to the invention, inserted into an air duct;
Fig.2 shows a view of the heat exchanger in Fig.l, seen in the direction of the arrow 4, but with the connecting duct removed;
Fig.3 shows a partial representation of the base plate of the heat exchanger in Figs.l and 2, in perspective, prior to assembly;
Fig~ 4 shows an enlarged representation of the portion 7 1~L7~Z6 of Fig.3, marked with the arrow IV;
Fig.5 shows a further enlarged partial representation, approximately actual-size, o~ the tubular end-pieces at the end of a tube-group;
Fig.6 shows a diagrammatically simplified sectional representation through a bath, into which a tube-bundlè has been inser-ted, as a heat exchanger, and Fig.7 shows a ba-th, with a tube-bundle suspended therein, at one side, as a heat exchanger.
- The heat exchanger, assembled, according to Figs 1 to 5, from a plurali-ty of superimposed tube-bundles, is located, according to Fig.l in the draught through a duct 2,3, to which a stream of air containing acid vapours is fed, at L~, and led away at 5. In the illustrative embodîment described, it is intended that the acid-laden stream of air should be cooled, from a comparatively high temperature, to room temperature. This cooling is carried out by heat-exchange with the cold water, which is supplied by the manifold line 14, at 15, flows through the tubes 11, and is drawn off, at 18, by the manifold line 17. From the manifold line 14, a plurality of lines lead, via connecting tube-sections 13, to the tubes 11 of the hea-t exchanger, as can be recognised from Fig.l, in conjunction with Fig.2. These tubes are contained within tube-bundles 12, which are assembled, in each case, from several groups 19~ each comprising four individual tubes (see also Fig.5).
In Fig~l, the tubes of the uppermost tube-bundle can be recognised in -the broken-open portion of the cover ~17~

plate, while the side view, in Fig.2, shows the position o~ the tube-bundles, one above another. In this Figure, however, only the two uppermost tube-bundles 12 are represented in their entirety, in order to simplify the drawing t while the tube-bundles located underneath are indicatedS in each case, only by in-dividual tubes 11.
` In Figs. 4 and 5 the four tubes of a tube-group are nlarked with the reference numbers 29,30,31 and 32. In order to retain the spacings between these tubes, they are led through holes 27 in retaining plates 25,26. A total of four retaining plates, of this type, are represented in Fig.l~ where they bear the reference numbers 7,8,9 and 13.
As can be seen from Figs. 1 to 4~ the four retaining plates o~ the tube-bundles of the heat ex-changer represented in Fig.l are provided, at their ends, with grooves, into which corresponding rebated ledges of supports 21,22,23,24 engage, these supports being attached, perpendicularly, to the baseplate 20.
As already noted, the superimposed retaining plates are marked, in Figs. 3 and 4, with the reference numbers 25 and 26, while the four retaining plates of the uppermost tube-bundle according to Fig.l are marked with the reference numbers 7,~,9 and 10.
Figure 5 shows a particularly space-saving design of the tubular end-pieces 33 and 3L~. Thus, the longer and wider tubular end piece 33 surrounds the bend of the other tubular end-piece 34 and, on the other ~ ~,, .
_ g ~

~L~766Z6 g _ hand, is bent inwards, in a manner such that the four openings of these two tubular end-pieces, which receive the ends of the four tube-pieces 29,30,31,32 are located close beside one another In the illustrative embodiment, the tube-pieces and the tubular end-pieces are manufactured from hard PVC, as are the manifold lines. Hard polyethylene, polypropylene and polyvinylidene flu~ride have been used in other examples. Depending on the material, the connectlons are produced by glueing or welding.
Two illustrative embodiments for warming chemical baths are represented in Figs. 6 and 7. In Fig~6, the bath 36, which is to be warmed, is located in a tank 35, a tube-bundle 37, with connecting tubes 38 and 40, being inserted on to the bottom of this tank. Hot water is supplied, at 39, and, after having exchanged h~at with the bath fluid, is led away again at 41.
A tank 43, with a bath liquid 42, is represented in Fig.7. A tube-bundle 44, with supply lines 45 and 46 is introduced into the bath vertically, in contact with a side wall of the tank 43.
The retaining plates, which are loosely pushed on to the tube-pieces, allow thermal expansion of the tubes, without any resulting lateral bending of the tube-pieces or portions thereof.

Claims

THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Heat exchanger between a first liquid, on the one side, and a second liquid, or a gas or gas-mixture, on the other side, comprising a plurality of straight tubes, arranged parallel to each other and at a distance one from another, through which the first liquid flows, and which are connected in parallel and/or in series, and are externally flooded by the second liquid, or by the gas or gas-mixture, characterised in that straight tube-pieces (11; 29, 30, 31, 32), which are made of a thermoplastic material, are arranged in groups (19), each group comprising four tubes, their ends being connected, one to another, in a manner proof against leakage of liquid, by tubular end-pieces (33, 34), which are approximately U-shaped and are made of the same plastic, and in that several tube-groups (19) of this type are combined to form a tube-bundle, which is fitted with connecting tube-sections (13,16) for supplying and discharging the first liquid, the cohesion between the tube pieces and the tube-groups being ensured by retaining plates (7,8,9,10; 25,26), which are distributed over the length of the tube-pieces, are provided with holes (27), and are loosely pushed on to the tube-pieces in a manner permitting shifting.

2. Heat exchanger according to Claim 1, characterised in that the tubular end-pieces (33,34) are pushed on to the tube-pieces (11; 29,30,31,32) and are welded to the latter.

3. Heat exchanger according to Claim 1, characterised in that the tubular end-pieces (33,34) are pushed on to the tube-pieces (11; 29,30,31,32) and are glued to the latter.

4. Heat exchanger according to Claims 1 to 3, characterised in that, in each case, two tubular end-pieces which are pushed on to four adjacent tube-pieces, and are attached thereto, are arranged, one within the other, in a manner such that the one tubular end-piece (33) engages around the bend of the other (34).

5. Heat exchanger according to claim 1, which is assembled from several tube-bundles which are placed one upon another, characterised in that the retaining plates (25,26) are provided, at their ends, with grooves, and are pushed into rebated ledges on the longitudinal edges of supports (21,22,23,24) which are securely erected, at intervals, on abase plate (20).

6. Process for manufacturing a heat exchanger according to Claim 1, characterised in that two tubular end-pieces (33,34), engaging one around the other, are pushed on to the four tube-pieces (29,30,319 32) of each tube-group (19), at one end thereof, and are connected to the tube-pieces, the retaining plates (25,26) are then pushed on to the other, free,ends of the tube-pieces of all the tube-groups of a tube-bundle, the tubular end-pieces are then slipped on to the free ends of the tube-pieces and are connected thereto, and, finally, the connecting tube-sections (13,16) are slipped on to the two tube-ends which remain open, and are connected thereto, the connections being produced by welding or glueing, depending on the plastic used.

7. Process according to Claim 6, for manufacturing a heat exchanger according to Claim 5, characterised in that supports(21,22,23,24) are attached, at intervals, to the base plate (20) of a duct section (6), which is provided, on both sides, with connection flanges and is initially open at the top and at one side, these supports standing perpendicularly relative to the base plate, several tube-bundles, produced according to Claim 6, are then pushed, one above another, on to and between these supports, a cover plate and the missing side wall are then fitted, the connecting tube-sections (13,16) projecting through openings in the side wall and, finally, the through-passages for the connection-sections are rendered leak-proof and the connecting tube-sections of the tube-bundles are then connected by means of manifold lines (14,17).