EP0313038B1 - Method for the manufacture of a heat exchanger tube plate structure - Google Patents

Description

The invention relates to a method for producing a tube sheet structure of a heat exchanger according to the preamble of patent claim 1.

In a method known from DE-OS 33 10 061 for producing a pipe distributor arrangement or a distributor pipe of a heat exchanger, the tube sheet is to be composed of a large number of precisely pre-shaped or pre-profiled elements; According to the number and the desired spacing of the profile tubes of the matrix, the relevant layer-to-layer elements should be pre-deformed in such a way that they can enclose half of the arranged tube ends of the matrix in a form-fitting manner.

In the known case, it is considered disadvantageous that despite relatively precise manufacture of the relevant elements forming the layers, manufacturing tolerances have to be taken into account such that the total length of the base or pipe to be produced fluctuates with the sum of the thickness tolerance of the elements; in addition to floor or pipe length fluctuations, local perforation offsets compared to the normal profile pipe spacing and arrangement cannot be ruled out; Due to the massive shape specification of the elements, manufacturing tolerances cannot be avoided and can hardly be corrected, or can only be corrected with extremely expensive post-processing.

The above-mentioned perforation offsets as well as slight fluctuations in the perforation form require laborious fine adjustment or centering of the relevant tube ends of the matrix, especially since the later soldering of the tube ends in the layered base forces an extremely precise fit of the tube ends in order to avoid local solder material displacements as far as possible.

The invention is based on the object of specifying a method in which the tube ends of a profile tube matrix of a heat exchanger can be optimally integrally bonded into a floor or distributor tube structure which is to be created essentially free of predetermined solid component specifications.

In a method according to the preamble of patent claim 1, the stated object is achieved according to the invention by the features of the characterizing part of patent claim 1.

According to the invention, it is therefore provided that the rings forming the central tube plate are not made from solid material as already known, but from a fiber mesh. When joining the layers - formed from flat layers of heat exchanger tubes and the fiber rings representing the central tube plate - according to the invention, the fiber braid is compressed under the action of axial joining forces in such a way that it nestles completely around the enclosed heat exchanger tubes. The compression of the fiber structure is strongest locally where the surfaces of adjacent pipes are at the smallest distance from each other in the joining area of the heat exchanger pipe field.

Metallic material (metal matrix) is then infiltrated into this initially porous structure of the central tube sheet in this way, which fills the cavities of the fiber structure and also creates a material connection to the surfaces of the enclosed tubes and the fibers of the wickerwork.

The formation of the fiber rings can be designed in detail as follows.

Orientation of a certain proportion of fibers in the circumferential direction is desirable in order to absorb the high circumferential forces during operation of the heat exchanger which result from the internal pressure load on the central tube with the relevant heat exchanger base. Another part of the fiber structure should protrude like bristles from the side surfaces of said fiber ring. When they are joined, these bristle structures of adjacent rings penetrate each other and, after infiltrating the metallic matrix, transmit the forces in the longitudinal direction of the central tube; the bristle structures also ensure that the areas that are least compressed during assembly, in particular on the leading and trailing edges of the heat exchanger tubes, are filled correctly and with a sufficient volume of the fiber material.

The fiber material should preferably be heat-resistant in accordance with the temperature load on the component, but not necessarily resistant to oxidation and corrosion. The latter is not the case if the fibers are completely enclosed by the system of the matrix, so that they are protected against the entry of aggressive media. So metallic, but also ceramic and carbon fibers come into question.

For assembling the heat exchanger, it can also be advantageous to enclose the fiber rings with solid rings. The width of these rings corresponds to the closest local distances of the heat exchanger tubes in the field, so that the rings can ensure the required distances when they are joined or pressed together. Since they have to follow the corrugated track of the tube field in the circumferential direction, it is necessary to make them correspondingly flexible or to impress the corrugated shape on the rings before joining.

The infiltration of the fiber matrix can also be carried out as follows.

1. In vacuum ovens, a lance-like cast crockery is passed inside the resulting central tube over its inner jacket and the molten matrix material is injected which, due to the capillary action, fills the fiber structure, binds with fibers and tube surfaces and solidifies. For this purpose, it may be necessary to previously close the tube ends of the heat exchanger matrix that extend into the interior of the central tube, in order to process them after the completion of the manufacturing process and thus to reopen them.

2. The above-mentioned massive ring, which surrounds the fiber structure on the outside, as well as a corresponding, if necessary, corresponding, arranged on the inside diameter of the fiber structure massive ring similar construction can also be made of a material that becomes molten when heated in the furnace like a solder and by capillary action in the fiber structure penetrates to fill the matrix volume and make the bonds.

Pipes of the matrix and fibers or fiber braiding can be subjected to a surface pretreatment in all cases in order to achieve improved wetting and integration into the matrix.

The above-mentioned statements are based on the basic idea of the invention according to claim 1 with objective clarification of further refinements of the method according to claim 1 within the scope of claims 2 to 17.

• Fig. 1 die perspektivische Darstellung eines bekannten und für die Durchführung des erfindungsgemäßen Verfahrens geeigneten Profilrohr-Wärmetauschers in Kreuz-Gegenstrom-Bauweise,
• Fig. 2 einen Profilausschnitt (geradschenkeliger Bereich) aus der Matrix des Wärmetauschers nach Fig.1,
• Fig. 3 ein grob vorjustiertes, in die Zeichnungsebene projiziertes Profilrohrfeld für die Matrix des Wärmetauschers nach Fig. 1 mit in gleichmäßigen Abständen zwischen benachbarten Profilrohrenden lose angeordneten Faserbündeln im Rahmen einer Ausgangsphase des Herstellverfahrens für eine Boden- oder Zentralrohrausbildung,
• Fig. 4 die perspektivische Darstellung eines Faserbündelabschnitts,
• Fig. 5 ein aus der Ausgangsstufe des betreffenden Verfahrens nach Fig. 3 durch Pressung und Verformung der betreffenden Faserbündel unter jeweiliger Profilrohrendumschließung ausgebildeter Abschnitt eines Wärmetauscherbodens mit regulärer gewünschter gegenseitiger Profilrohrbeabstandung im Feld,
• Fig. 6 ein im Wege der Pressung und Verformung nach Fig. 5 hergestelltes zylindrisches Sammel-oder Verteilerrohr mit beidseitig zwischen benachbarten Faserbündeln ins Rohrinnere einmündenden Profilrohrenden der Matrix, hier im Wege einer örtlich freigelegten Seitenansicht der betreffenden Profilrohrenden in Kombination mit einem innenliegenden zylindrischen Faserbündel verdeutlicht,
• Fig. 7 die nach Fig. 5 hergestellte Bodenstruktur unter Verwendung zusätzlicher, hier entlang der Bodenaußenseite sich gewellt zwischen den Profilrohrenden erstreckenden metallischen Zwischenringen und
• Fig. 8 eine gemäß Fig. 6 dargestellte Weiterentwicklung des Verfahrensgegenstandes unter Verwendung jeweils äußerer und innerer metallischer Zwischenringe an gemäß Fig. 5 verformten und gepressten Faserbündeln zwecks Ausbildung einer zylindrischen Sammel- oder Verteilerrohrstruktur.

The invention is further explained, for example, with the aid of the drawings; show it:

• 1 is a perspective view of a known profile tube heat exchanger in a cross-countercurrent design which is suitable for carrying out the method according to the invention,
• 2 shows a profile section (straight-leg region) from the matrix of the heat exchanger according to FIG. 1,
• 3 shows a roughly pre-adjusted profile tube field for the matrix of the heat exchanger according to FIG. 1, projected into the plane of the drawing, with fiber bundles loosely arranged at uniform intervals between adjacent profile tube ends as part of an initial phase of the manufacturing process for bottom or central tube formation,
• 4 shows the perspective illustration of a fiber bundle section,
• 5 shows a section of a heat exchanger base which is formed from the initial stage of the relevant method according to FIG. 3 by pressing and deforming the relevant fiber bundle with the respective profile tube end enclosure, with a regular desired mutual profile tube spacing in the field,
• Fig. 6 shows a cylindrical manifold or distributor tube produced by pressing and deforming according to Fig. 5 with profile tube ends of the matrix opening into the tube interior between adjacent fiber bundles, here illustrated by means of a locally exposed side view of the relevant profile tube ends in combination with an internal cylindrical fiber bundle ,
• Fig. 7, the bottom structure produced according to Fig. 5 using additional, here along the bottom outside corrugated between the profile tube ends extending metallic intermediate rings and
• FIG. 8 shows a further development of the subject of the method shown in FIG. 6 using outer and inner metallic intermediate rings on fiber bundles deformed and pressed according to FIG. 5 to form a cylindrical header or distributor pipe structure.

Fig. 1 illustrates a heat exchanger 1 for guiding gases of very different temperatures, the cross-countercurrent matrix 2 in the hot gas flow G consists of separate compressed air lines 3 (Fig. 2), which on the one hand to a first stationary pipe guide 4 for the supply of cold compressed air D in the matrix 2 (cold) and on the other hand connected to a second stationary pipe guide 5, from which the compressed air D (hot) heated via the matrix 2 can be fed to a consumer. The two pipe guides 4, 5 are arranged separately from one another and integrated in a common header pipe 6. Each profile tube 3 of the matrix 2 - starting from its tube-side connections to the first 4 and second tube guide 5 of the header tube 6 - should initially run parallel to a laterally extended header tube meridian plane before it turns into a common, U deflecting the compressed air D by 180 _° -shaped wiring harness merges. The matrix 2 should also flow through the hot gas G transversely to the elongated manifold meridian plane and while ensuring the permissible hot gas blockage between the adjacent profile tubes 3.

As can be seen in particular from FIG. 2, the profile tubes 3 of the matrix lying on the upstream and downstream sides in the hot gas flow direction G with streamlined pointed ends have a lenticular cross section; the profile tubes 3, which each run parallel to a common matrix transverse plane, engage with one another on the upstream and downstream side of the profile tapering, utilizing the expansions which form as a result of these tapering; each profile tube 3 of the matrix 2 (FIG. 2) also contains two compressed air channels 8, 9 separated from one another by a profile web 7, which have triangular flow cross sections in the sense of the two tapered outer wall sections of the profile tubes 3 concerned.

In the heat exchanger described at the outset, as is known from DE-PS 29 07 810, two or more separate manifolds or manifolds for the compressed air supply into the matrix can also be used instead of the common manifold 6, essentially arranged one above the other or next to one another 2 or for the compressed air discharge (hot) from the matrix 2.

The invention therefore relates to the manufacture of the relevant floor structure 10, but in particular to the manufacture of the header pipe 6 together with the floor structure 10 or the manufacture of one or more header or distributor pipes in a heat exchanger of the cross-countercurrent construction discussed at the beginning.

A method for producing a tube sheet structure 10 or a header tube 6 of a heat exchanger using strip-shaped layers 11, 12 or 12, 13 (FIG. 5) is thus specified, between which tube ends of the profile tubes 3 of the matrix 2 are firmly integrated in a fluid-tight manner; the strip-shaped layers 11, 12; 12, 13 are to be produced from fibers which are initially bundled uniformly (fiber bundles 11 ', 12'; 12 _' , 13') between the tube ends of adjacent rows of profile tubes (tubes 3) and are thus deformed under pressure (arrow direction P, P ') They should form an initially porous bottom structure (Fig. 5) under half-sided pipe wrapping, into which a metallic material is then infiltrated in a molten state, in which all fibers including the pipe ends are integrally bonded.

4, the fiber bundles, e.g. 12 ', composed of interwoven fiber layers with main fibers 14 running in the circumferential direction of the tube sheet structure and transverse fibers 15 running transversely thereto, such that the latter - after the pressing and deformation phase (FIG. 5) have been completed - engage in a bristle-like manner essentially outside the tube encapsulation areas.

In the area of the mutual contact planes 16, the secondary fibers 15 of the adjacent fiber layers, e.g. 12, 13, intertwine like bristles. In particular, a complete interweaving of fibers should also be achieved in the respective profile end or tip areas. The aforementioned contact planes 16 are arranged in a longitudinally symmetrical alignment with the profile longitudinal center planes E.

7 and 8, the fiber bundles, e.g. 12 ', 13' (Fig. 3) layers, e.g. 12, 13 (FIG. 5) are covered entirely or partially by metallic ring elements 17, 18 (FIG. 7) or 18, 19 (FIG. 8) extending along the inside and / or outside of the floor structure.

The ring elements mentioned can e.g. can be provided to stiffen the floor or pipe structure, and to protect the fiber structures from local environmental influences such as temperature influences.

The ring elements mentioned can also be aids in the infiltration process in that they are intended to prevent the infiltration agent from flowing off. If e.g. the infiltration process of a molten metallic material from the outside of a tube sheet into the fiber material, the relevant ring elements, e.g. 19 (Fig. 8) can only be arranged on the inside of the tube sheet to prevent the metallic material from flowing away. After infiltration has been completed, the ring elements, e.g. 19 (Fig. 8) can be removed again.

In a further process training there is also the possibility that the metallic ring elements, e.g. 17, 18 (Fig. 7), while ensuring the required profile spacing, in the floor structure together with the fiber bundles 12 ', 13' (Fig. 3) are deformed, and accordingly corrugated deformed.

Instead of the joint pressing of fiber bundles and ring elements, it would also be possible for pre-shaped or corrugated metallic ring elements, e.g. 18, 19 (Fig. 8), before the metallic infiltration, on the inside and outside of the tube sheet onto the fiber layers, e.g. 12, to be put on.

According to a further advantageous variant of the method, the metallic ring elements, e.g. 18, 19 (FIG. 8), are manufactured from a solder material which ensures metallic infiltration. The ring elements, e.g. 18, 19 (FIG. 8) on the inside and outside of the porous tube sheet structure as elements corrugated in the sense of the profile tube profile (FIG. 7) are placed on the fiber bundles 12 '(FIG. 8).

An extremely practical handling of the infiltration process is seen in the fact that the tube sheet structure, which is equipped with metallic ring elements 17, 18 (FIG. 7) or 18, 19 (FIG. 8) made of a solder material, is heated in an oven for melt liquefaction and infiltration of the solder.

If, for example, no ring elements that extend the solder and composite material should be used, a metallic composite material (matrix) can be melted within a vacuum furnace via a lance-shaped casting tableware that sweeps the corrugated porous floor structure (FIG. 5) along the inside and outside of the tube sheet be injected.

In a further embodiment of the method, the ends of the profile tubes 3 of the matrix which are open on the inside of the tube sheet can be closed before metallic infiltration is carried out from the inside of the base structure and can be opened again by mechanical processing after the infiltration has been completed.

The fibers of the fiber bundles) 11 _' , 12' or 12 ', 13' (FIG. 3) can be made from a metallic material or from wires, from a ceramic material, for example from partially stabilized zirconium oxide or from carbon.

The metallic material infiltrated after the pressing and deformation phase can be made from an aluminum alloy.

Within the scope of the method, a circular cylindrical (Fig. 1, 6 or 8), square or rectangular header or distributor pipe of a cross-countercurrent heat exchanger can be used with the collector or distributor pipes, e.g. 6-fig. 1, U-shaped protruding profile tube matrix 2 are produced, the fiber bundles 11 ', 12' or 12 ', 13' (FIG. 3) being compressed to the desired length of header or distributor tube, including the required mutual profile tube spacing of the matrix 2, and the metallic infiltration, for example by means of the aforementioned crockery, can be carried out continuously over the entire circumference of the porous collecting or distribution pipe structure (FIG. 5).

Instead of the metallic rings mentioned at the outset, rings made of a suitable plastic, e.g. can be provided from a fiber-reinforced plastic or from a suitable ceramic material.

Claims (17)

1. A method of producing a tube plate structure of a heat exchanger composed of strip-like layers between which tube ends of a profile tube matrix are fluid-tightly and rigidly bonded, characterised in that the strip-like layers (12, 13) are produced from fibres which are disposed between the tube ends of adjacent rows of profile tubes and which are pressed so that they become so shaped that fitting closely half way round a tube they initially form a porous plate structure into which a metallic material is infiltrated in the molten state, the fibre structure being filled by capillary action and entering into a bond with fibres and tube surfaces and solidifying, all the fibres including the tube ends being bonded as a result of material flow.

2. A method according to Claim 1, characterised in that fibre bundles (12') of interconnected layers of fibres comprising main fibres (14) extending in the peripheral direction of the tube plate structure and subsidiary fibres (15) extending transversely thereto are so assembled that, when the pressing and moulding phases are completed, the latter inter-engage like bristles outside the areas which fit around the tubes.

3. A method according to Claim 1 or 2, characterised in that the layers (12) produced from fibre bundles (12') are entirely or partially masked by ring elements (18, 19) extending along the inside and/or outside of the plate structure.

4. A method according to Claim 3, characterised in that ring elements (18, 19) provided on the inside and outside of the plate structure are removed once metallic infiltration is complete.

5. A method according to Claim 3, characterised in that the ring elements (17, 18) are moulded together with the fibre bundles (12', 13'), ensuring the required profile gap in the plate structure.

6. A method according to Claim 3 or 4, characterised in that ring elements (18, 19) pre-shaped or undulating according to the final pattern of the profile tubes are fitted onto the fibre layers (12) on the inside or outside of the tube plate prior to metallic infiltration.

7. A method according to Claim 3 or 5, characterised in that the ring elements (18, 19) are produced from a solder material which guarantees metallic infiltration.

8. A method according to Claim 7, characterised in that the metallic ring elements (18, 19) produced from a solder material are fitted onto the fibre bundles (12') on the inside and outside of the porous tube plate structure to serve as undulating elements according to the pattern of the profile tubes.

9. A method according to Claim 7 or 8, characterised in that the tube plate structure provided with metallic ring elements which consist of a solder material are heated in an oven to liquefy and allow infiltration of the solder.

10. A method according to one or more of Claims 1 to 6, characterised in that the metallic composite material is injected in molten-fluid form along the inside or outside of the tube plate inside a vacuum oven, by means of a pouring apparatus of lance like construction adapted to coat the undulatingly shaped porous plate structure.

11. A method according to Claim 10, characterised in that the tube ends of the matrix which are open towards the inside of the tube plate are closed by metallic infiltration carried out from inside the plate structure and, once infiltration is complete, are opened again by mechanical machining.

12. A method according to one or more of Claims 1 to 11, characterised in that the fibres of the fibre bundles are made from a metallic material or from wires.

13. A method according to one or more of Claims 1 to 11, characterised in that the fibres of the fibre bundles are made from a ceramic material.

14. A method according to Claim 13, characterised in that the fibres of the fibre bundles are made from partially stabilised zirkonium oxide.

15. A method according to Claim 13 or 14, characterised in that the metallic material infiltrated after the moulding and shaping phases is produced from an aluminium alloy.

16. A method according to one or more of Claims 1 to 11, characterised in that the fibres of the fibre bundles are made from carbon.

17. A method according to one or more of Claims 1 to 16, characterised in that a circularly cylindrical, quadratic or rectangular collecting or distributing tube (6) of a cross-counter current heat exchanger with a profile tube matrix (2) projecting in a U-shape from collecting or distributor tubes (6) is produced over the tube plate structure, the fibre bundles (11', 12'; 12', 13') being compressed to the desired collecting or distributor tube length with the inclusion of the required distance between the profile tubes in the matrix (2), metallic infiltration being carried out over the entire periphery of the porous collecting or distributor tube structure.

Images