Manufacturing method for establishing a welded connection between the inner tube of a tube bundle and a tube support plate of a product-to-product tube bundle heat exchanger, auxiliary device, product-to-product tube bundle heat exchanger and tube bundle

Abstract

The invention relates to a production method for producing a welded connection between an inner tube (16) and a tube support plate for a product-to-product tube bundle heat exchanger using an auxiliary device (50), the method comprising the following steps (iv) to (vi) and (viii): (iv) during the time period for welding all the inner tubes (16), the end side of the tube support plate is pressed against the end side of the inner tube (16) in the direction of the inner tube longitudinal axis (R) of the inner tube (16) by means of a first positive connection, the first positive connection acting radially and axially and respectively oriented toward each other, the inner hole of the plate side and the inner tube (16) being pressed against the end side of the inner tube (16) in the direction of the inner tube longitudinal axis (R) of the inner tube (16). The inner holes on the tube side have inner diameters of the same size; (v) a corresponding necessary number (n) of inner tubes (16) are fixed to each other immovably as a whole according to the tube layout pattern by a second form lock (F2) of an auxiliary device (50), wherein the second form lock is designed to be releasable; (vi) a circumferential circular weld is realized along a track starting from the inner holes on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside, wherein the weld width of the circumferential circular weld at least covers the axial form lock depth of the first form lock; (vii) the auxiliary device (50) is loosened and removed from the welded tube arrangement system.

Description

Technical Field

[0001] The invention relates to a production method for producing a welded connection between inner tubes and tube support plates of a tube bundle for a product-to-product tube bundle heat exchanger with auxiliary devices, the respective tube support plates being welded with their end sides facing the inner tubes. The method is carried out in a manner known per se with the following steps: (i) the inner tubes are oriented with the corresponding plate-side inner holes provided in the tube support plate so that the inner tubes and the plate-side inner holes are aligned with each other; (ii) the corresponding inner tubes and the tube support plate are fixed relative to each other in an initial position not welded by means of a positive fit, which acts radially and directed in opposite directions, wherein more than one plate-side inner hole is pre-arranged and thus a tube layout pattern is determined by the tube support plate for the corresponding inner tubes arranged parallel to each other; (iii) the corresponding necessary number of inner tubes are fixed as a whole in a manner not displaceable relative to each other and in a corresponding positive fit to the tube support plate according to the tube layout pattern by means of the auxiliary devices;

[0002] Furthermore, the invention relates to an auxiliary device for such a production method, a tube bundle welded using such a production method or such an auxiliary device, and a product-to-product tube bundle heat exchanger having at least one such tube bundle. Background Art

[0003] In the food and beverage industry, different types of heat exchangers are used to thermally treat food products. Depending on the food product to be treated, a corresponding selection is made, for example, a plate or tube heat exchanger with different embodiments. Tubular heat exchangers are used for low-viscosity products, such as milk and other dairy products, beverages and fruit juices, as well as for products with medium to high viscosity, such as concentrates, soups or desserts, and also for products that additionally contain fibers and / or pulp. Usually, the product flows through a so-called inner tube for thermal treatment, and a heat transfer medium, for example steam or water, flows around the inner tube from the outside in a housing, preferably an outer shell tube, surrounding the inner tube, preferably in countercurrent.

[0004] A particularly energy-efficient embodiment of the known tubular heat exchanger is the so-called tube bundle heat exchanger (see FIG. 1 ). This heat exchanger consists of a plurality of tube bundles ( FIGS. 2 a, 2 b, 3 ), each of which has a plurality of inner tubes connected in parallel, which have a common inlet and a common outlet for the product. Each group of inner tubes or so-called inner tube sets is surrounded by an outer shell tube, which is provided near its ends with pipe connections for a heat transfer medium which radially enters or exits the outer shell tube. The heat transfer medium preferably flows through the outer shell tube in counterflow to the tube flow in the inner tube, i.e. the product flow.

[0005] The inner tube is passed through the plate-side inner hole of the so-called tube support plate (FIG. 3) on both sides and at the end and is connected to the tube support plate at its tube end and at its end facing away from the inner tube (front side of the tube support plate), preferably by a circumferential circular weld. Instead of a welded connection, other integral connections with or without additional material can also be used. Thus, there is a circumferential annular gap between the outer side of the inner tube and the corresponding plate-side inner hole in the tube support plate, which extends from the circumferential integral connection between the inner tube and the tube support plate through the tube support plate to the inner space of the tube bundle or the outer shell tube that is loaded with the heat transfer medium. This circumferential annular gap is of no importance as long as the heat transfer medium remains only one heat transfer medium, such as water or steam, and is not replaced by the food product.

[0006] However, if a so-called product-to-product heat transfer is to be carried out in a tube bundle heat exchanger in order to achieve a better heat transfer efficiency, the aforementioned surrounding gap is critical, since the product may be adhering there. In the most favorable case, these products can only be cleaned by particularly intensive and prolonged excessive cleaning with a through-flow, the so-called CIP (CIP: cleaning in place), the purpose of which is to convert the surrounding annular gap to a microbiologically insensitive state for the subsequent product flow.

[0007] In particular for heat transfer systems operating regeneratively, in which the heat generated, for example, when cooling the final product, is used to preheat the product to be processed, it is known that a higher energy efficiency or economy is achieved for a product-to-product (PP) heat transfer compared to a product-to-heat-transfer-medium-to-product (PWP) heat transfer, since the heat transfer is improved due to the greater logarithmic temperature difference and the higher flow velocity of the product flow (better Reynolds number) and the heat exchange surface can thus be reduced. In addition, due to the higher Reynolds number, tube bundles with greater tube lengths can be realized, thereby achieving a cost reduction.

[0008] In known forms, tube bundle heat exchangers are suitable for product-to-product heat exchange only at the expense of excessive cleaning from the point of view of hygiene or even aesthetics. It has therefore been proposed (JP 2020 117 121) to carry out an additional circular seam weld on the back side of the tube support plate, i.e. on the end side of the tube support plate facing the inner tube, in order to thereby close the critical annular gap to prevent product ingress. The disadvantage of the correspondingly circumferential circular welds on the front side of the tube support plate and additionally on the back side is that a closed annular cavity or annular gap is formed between the two circular welds or between two other types of material-locked connections, which constitutes a risk for food safety if the circular welds or material-locked connections are not manufactured in a flawless and pore-free manner. A check in this regard can only be carried out with difficulty or not at all. There is a risk that microorganisms will grow in the closed annular cavity, which can re-contaminate subsequent products.

[0009] DE 23 41 808 A1 describes a heat exchanger having opposite head plates with holes, which connect matching inner tubes to each other so that they are congruent. The diameter of the inner tube is equal to the diameter of the corresponding head plate. The head plate is designed in the form of a projection in the peripheral area of ​​the hole and facing the inner tube. The projection and the inner tube are connected to each other by a butt weld over the entire wall thickness of the inner tube, where the butt weld is designed as an orbital weld from the inside of the inner tube. During the welding process, the inner tube is fixed relative to the head plate by a suitable retaining mechanism.

[0010] US Pat. No. 2,996,600 A describes a welded connection between a tube and a tube support plate in the context of a tubular heat exchanger. The tube has an inner diameter that corresponds to the diameter of a hole in the tube support plate that is assigned to the tube. The tube and the tube support plate are welded to each other in such a way that the inner diameter of the tube and the diameter of the hole are aligned with each other. In this connection, the necessary orientation and centering of the tube on the tube support plate is achieved by means of a recess in the tube support plate, into which the tube is embedded. A solution opposite to this principle is also disclosed, in which a recess is provided on the tube end to be connected, which surrounds the journal in the tube support plate surrounding the hole from the outside. The corresponding form-locking area between the tube and the tube support plate is welded in a single layer and continuously from the inside of the inner diameter of the tube and from the hole in the tube support plate by means of a welding tool that moves in a circular motion along a track, starting from the inside of the inner diameter of the tube and from the hole in the tube support plate, from the radial inside to the radial outside.

[0011] FR 2 349 395 A discloses a device for fixing a tube in a tube sheet by means of so-called internal hole welding, wherein the tube is inserted into a hole in the tube sheet at a certain distance and a welding electrode is inserted into the hole and the interior of the tube, the welding electrode performing a rotational movement relative to the edge of the tube and relative to the hole. This produces a weld seam that connects the entire wall thickness of the tube to the corner region of the solid tube sheet facing the tube.

[0012] WO 2014 060 425 A1 or the corresponding US 2015 / 267 973 A1 discloses various proposals on how the connection in question between the inner tubes of a tube bundle of a tube bundle heat exchanger and a tube support plate can be designed while avoiding a circumferential annular gap between the outer side of the inner tube and the opening of the tube support plate.

[0013] DE 15 01 463 A discloses a device for horizontally assembling a heat exchanger, in which a tube bundle held together by retaining elements is introduced into a shell of the heat exchanger open on both sides, the tubes of the tube bundle being introduced with their tube ends into matching holes in the tube base. After assembly and during operation of the heat exchanger, the retaining elements obviously remain on or in the tube bundle.

[0014] No features are disclosed regarding embedding the tubes of the tube bundle in the tube base and connecting them to the tube base (e.g., by welding). It can be assumed that the individual tubes of the tube bundle are connected by passing through matching holes in the tube base and, at the open tube end, are connected by material bonding to the end side of the tube base facing away from the tubes, possibly by welding. As already discussed above, a welded connection in this regard results in a critical annular gap between the outer diameter of the respective tube and the inner diameter of the hole in the tube base for receiving it.

[0015] The features of the prior art given above in combination with one another form the general basis for the subject matter of the present invention for the design of the welded connection between the inner tube and the tube support plate (US Pat. No. 2,996,600 A) and for the holders or auxiliary devices for holding the tubes of a tube bundle together (DE 15 01 463 A). Summary of the invention

[0016] Starting from the prior art described above, the object of the present invention is to provide a manufacturing method of the generic type which, by means of auxiliary devices, ensures that the welded connection between the inner tubes of a tube bundle for a product-to-product tube bundle heat exchanger and the tube support plate is achieved more reliably, dimensionally accurately and with highly reproducible quality from the standpoint of hygiene and cleanliness. Furthermore, the object of the present invention is to specify an auxiliary device for carrying out the manufacturing method according to the invention.

[0017] The object is achieved by the manufacturing method according to the invention. The invention also relates to an auxiliary device for the manufacturing method. The invention also relates to a tube bundle. The invention also relates to a product-to-product tube bundle heat exchanger according to the invention having at least one tube bundle.

[0018] The invention is based on a production method for producing a welded connection between inner tubes and tube support plates of a tube bundle for a product-to-product tube bundle heat exchanger with auxiliary devices, the respective tube support plates being welded with their end sides facing the inner tubes, the method being carried out in the following steps (i) to (iii) known per se:

[0019] (i) aligning the inner tube with the corresponding plate-side inner hole provided in the tube support plate so that the inner tube and the plate-side inner hole are aligned with each other, that is, their rotation axes extend coaxially;

[0020] (ii) in an initial, unwelded position, the respective inner tube and the tube support plate are fixed relative to one another by means of a positive fit which acts radially and in a direction directed toward one another, presupposes inner holes on more than one plate side and thereby defines a tube layout pattern for the associated inner tubes arranged parallel to one another by means of the tube support plate;

[0021] The radial fixation acts in two directions, while the axial fixation is limited to the fact that the inner tube is in contact with the tube support plate in one direction and can be released from the tube support plate in the opposite direction.

[0022] (iii) By means of auxiliary devices, the corresponding necessary number n of inner tubes are fixed immovably relative to one another as a whole and to the tube support plate in a corresponding form-fitting manner, depending on the tube arrangement pattern. The tube support plate determines the tube arrangement pattern by providing more than one inner hole for arranging matching inner tubes arranged parallel to one another. The number n of possible inner tubes is two or more, preferably n=7 inner tubes are provided, wherein one inner tube is arranged centrally in the tube support plate and the other inner tubes are arranged evenly distributed on a single pitch circle, which extends concentrically with the center of the tube support plate. The auxiliary devices serve to fix the inner tubes immovably relative to one another.

[0023] In the manufacturing method according to the invention, the inventive concept is to propose a solution not only for a single inner tube in the sense of the proposed object, as is known in the prior art, but also for a group or a set of inner tubes extending parallel to one another according to a continuous welding process, which processes all the inner tubes of the group in sequence.

[0024] According to the production method, the object of the present invention is achieved by the following additional steps (iv) to (viii).

[0025] (iv) During the time period for welding all inner tubes, the end side of the tube support plate is pressed against the end side of the inner tube in the direction of the inner tube longitudinal axis of the inner tube by means of a first positive fit, which acts radially and axially and is respectively oriented toward each other, and the inner hole on the plate side and the inner hole on the tube side of the inner tube have the same inner diameter. This pressing avoids or minimizes the formation of undesired gaps between the inner tube and the end side of the tube support plate, which may be caused by the heat input during welding.

[0026] (v) The correspondingly necessary number n of inner tubes are fixed to each other as a whole in an immovable manner according to the tube layout pattern by means of a second positive connection of the auxiliary device, which second positive connection is designed to be releasable. The second positive connection preferably does not require the use of non-positive locking components, and this design also includes an inner tube that is optionally located in the center.

[0027] (vi) A circumferential circular weld is realized along the path starting from the inner opening on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside, the weld width of which covers at least the axial form-fitting depth of the first form-fit.

[0028] The welding is preferably carried out without additional material and in a protective gas atmosphere suitable for the materials to be connected. The axial form-locking depth is coordinated with the weld seam width obtained under the given welding and wall thickness conditions. The axial form-locking depth must not exceed the possible weld seam width. A circumferential round weld is a weld seam that is designed to be closed, that is to say without local interruptions.

[0029] (vii) The inner tube is welded successively to the tube support plate. In the arrangement position which the inner tube once takes up and which is immovably fixed by auxiliary devices, all the welded connections associated therewith are carried out.

[0030] (vii) Loosening and removing auxiliary devices from welded pipe arrangements.

[0031] In order to minimize material stresses during the course of the welding process involving all welded connections, the welding sequence is arranged such that, if there is an inner tube arranged centrally in the tube support plate, this central inner tube is first welded to the tube support plate and subsequently the outer inner tubes arranged around the central inner tube on a pitch circle are welded to the tube support plate in a relative order.

[0032] The invention is based on a method-related auxiliary device for a production method for producing a welded connection between the inner tubes of a tube bundle for a product-to-product tube bundle heat exchanger and a tube support plate, the welded connection being designed in a manner known per se:

[0033] The inner tube is connected with its tube-side inner bore in a plane perpendicular to the longitudinal axis of the inner tube to the end facing the inner tube of a disk-shaped tube support plate which has a plate-side inner bore.

[0034] The tube-side inner opening and the plate-side inner opening have inner diameters of the same size and are oriented in alignment with one another.

[0035] In the unwelded initial position, the inner tube and the tube support plate are fixed to one another by means of a first form fit, which acts radially and axially and in each case in a manner oriented toward one another.

[0036] A circumferential circular weld is produced along the path starting from the inner opening on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside.

[0037] At least the axial form-fitting depth of the first form-fit is covered by the weld seam width of the circumferential circular weld seam.

[0038] The object of the invention is achieved with the auxiliary device according to the invention for the production method according to the invention by the following features:

[0039] In the region of the auxiliary device, a first and a second retaining ring half are provided, which form a closed ring.

[0040] The retaining ring halves come into contact in a dividing plane which runs through the center of the auxiliary device and in which the retaining ring halves form a second, non-displaceable form fit with one another.

[0041] The tube support plate determines the tube layout pattern for the inner tubes arranged parallel to one another by providing more than one inner hole on the plate side provided.

[0042] The tube layout pattern is reflected in the retaining ring halves in such a way that the inner tubes arranged uniformly on a single pitch circle are each surrounded at most halfway by a retaining ring half, the opening of each surrounded contour facing the center of the retaining ring half. These conditions are met by corresponding dimensioning of the inner diameter of the retaining ring halves closed into a ring, which is dependent on the number of inner tubes located on the pitch circle.

[0043] The dividing plane also extends through at least one inner tube longitudinal axis lying on the pitch circle. This ensures that the retaining ring halves can surround and fix all inner tubes as a whole and that, after all inner tubes have been welded to the tube support plate, the retaining ring halves can be released and removed from the welded tube arrangement.

[0044] Holding means are provided which are each engaged displaceably in the holding ring halves on the circumference of the holding ring halves and oriented in a star shape toward the center.

[0045] The holding mechanisms are respectively tangential to adjacent inner tubes arranged on the pitch circle.

[0046] If necessary, the holding means fix the centrally arranged inner tube with their respective centrally facing end sides and themselves are each releasably fixed in this position.

[0047] The auxiliary device according to the invention, which is designed in accordance with the preceding features, is suitable for accommodating a tube arrangement having at least two inner tubes in a defined manner.

[0048] It is sufficient that the second form-fitting connection fixes the first and second retaining ring halves to each other in the radial direction. The fixing of the retaining ring halves to each other in the axial direction is expediently achieved in that, as provided above, the first and second retaining ring halves are detachably connected to each other by connecting means, such as connecting screws, which are arranged on the circumference of the first and second retaining ring halves and are arranged diametrically opposite to each other.

[0049] If the auxiliary device is in the closed position and it fixes a set number of inner tubes in this position, so that the inner tubes can be welded to the corresponding tube support plate according to the production method according to the invention, the retaining means that fix the inner tubes with a second positive fit are respectively fixed in an immovable manner in the corresponding retaining ring half itself by fixing means, such as fixing screws.

[0050] A particularly advantageous tube arrangement is characterized by the fact that seven inner tubes are provided, one inner tube being coaxially located in the center of the auxiliary device, six inner tubes being evenly distributed on the pitch circle, and the dividing plane additionally extending through two inner tubes arranged diametrically opposite one another. In this arrangement, the inner tube longitudinal axes of three adjacent inner tubes each form the corners of an equilateral triangle, whereby the radial distances of all adjacent inner tubes are equal, since all inner tubes generally have an outer diameter of the same size. Under these boundary conditions, the heat transfer and heat conduction conditions are approximately the same for all inner tubes, if the special flow conditions of the central inner tube relative to the other inner tubes located on the pitch circle are not taken into account.

[0051] The partial or complete offset of the circumferential circular weld into the tube support plate results in a discontinuous change in the connection cross section from the smaller connection cross section of the inner tube to the solid cross section of the tube support plate in a manner known per se. This change is disadvantageous in terms of strength.

[0052] With the production method according to the invention for producing a welded connection between an inner tube and a tube support plate and with the auxiliary device according to the invention, a tube bundle consisting of a plurality of inner tubes for a product-to-product tube bundle heat exchanger can be produced in accordance with the object of the invention and the disadvantageous cross-sectional changes mentioned above can be avoided. This is achieved in that the welded connection is designed as a circumferential circular weld seam and the tube support plate has a circumferential, axially extending, annular gap-shaped plate-side recess at a distance radially from the circumferential circular weld seam on the outside, which is designed so that the wall thickness of the tube support plate to be welded by the circumferential circular weld seam has a value of one to two times the tube wall thickness.

[0053] The invention provides that the method for producing a welded connection between an inner tube and a tube support plate can be carried out using the auxiliary device according to the invention in its proposed embodiment.

[0054] The manufacturing method according to the invention and the auxiliary device according to the invention are based on the welded connection according to the invention between the inner tube of the tube bundle for a product-to-product tube bundle heat exchanger and the tube support plate. This welded connection ensures that the above-mentioned circumferential annular gap between the outer diameter of the inner tube and the inner diameter of the corresponding plate-side inner bore, which is critical from the perspective of hygiene and cleaning, is avoided.

[0055] Furthermore, the object of the present invention is to optimize the tube bundle according to the invention produced by means of the welded connection according to the invention according to a further embodiment. Basically, this embodiment is characterized by:

[0056] the inner tube is connected with its tube-side inner bore in a plane perpendicular to the longitudinal axis of the inner tube to the end facing the inner tube of a disk-shaped tube support plate, which has a plate-side inner bore,

[0057] The inner holes on the tube side and the inner holes on the plate side have the same inner diameter and are aligned with each other,

[0058] In the unwelded initial position, the inner tube and the tube support plate are fixed to one another by means of a first form-fitting connection, which acts radially and axially and in each case in a direction directed toward one another,

[0059] · Producing a circumferential circular weld along the path starting from the inner hole on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside,

[0060] The weld seam width of the circumferential circular weld seam covers at least the axial form-fitting depth of the first form-fitting connection, and

[0061] The circumferential circular weld seam is positioned such that the weld seam width, viewed from the side of the inner tube, engages at most with an axial positive-locking depth into the tube support plate.

[0062] If the circumferential circular weld is positioned so that the weld width, viewed from the side of the inner tube, engages at most to the axial positive locking depth in the tube support plate, the tube support plate is sunk or bored only by the outer diameter of the inner tube and at most to the positive locking depth. This quantitative design ensures that there is no longer any gap between the outer diameter of the inner tube and the inner hole in the tube support plate that is not covered by the circumferential circular weld. A sunk below the positive locking depth causes a portion of the width of the circumferential circular weld to be displaced into the tube region upstream of the tube support plate.

[0063] In this context, another known proposal also provides a remedy for the disadvantageous cross-sectional changes and in particular improves the strength properties under alternating mechanical and / or thermal loads. This proposal provides that the circumferential round weld is positioned at a first positively interlocking, front axial positively interlocking distance from the tube support plate, which is tapered in this region to a wall thickness of one to two times the tube wall thickness.

[0064] Furthermore, the invention makes it possible to produce a product-to-product tube bundle heat exchanger comprising at least one tube bundle which is respectively welded according to one of its proposed embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] A detailed description of the invention can be derived from the following description and the illustrations in the drawings. The invention can be implemented in different embodiments of a manufacturing method of the type described. In addition, the invention can be implemented in different embodiments of an auxiliary device according to the invention for the manufacturing method according to the invention. A manufacturing method for a product-to-product tube bundle heat exchanger in which a welded connection is established between the inner tube and the tube support plate by means of an auxiliary device, a welded tube bundle and a product-to-product tube bundle heat exchanger comprising at least one tube bundle also form part of the subject matter of the invention. The manufacturing method, the auxiliary device, the tube bundle and the product-to-product tube bundle heat exchanger are described below with reference to the drawings based on a preferred embodiment. Among them:

[0066] FIG1 shows a schematic perspective view of a tube bundle heat exchanger according to the prior art;

[0067] 2a shows a perspective view of a tube bundle according to the prior art, which has inner tubes and is a representation looking toward the end side of the tube support plate facing away from the inner tubes (front side) and toward the end side of the inner tubes (rear side);

[0068] FIG. 2 b shows the tube bundle according to FIG. 2 a in a perspective view viewed from the opposite direction relative to FIG. 2 a ;

[0069] 3 shows a tube bundle according to the prior art according to FIGS. 2 a and 2 b in a meridian section, which is embedded in a housing for supplying and removing a heat transfer medium;

[0070] FIG4 shows a meridian cross section of a first welded connection between an inner tube and a tube support plate according to the prior art in combination with a welding tool;

[0071] FIG. 4 a shows in an enlarged view a second design according to the prior art, which is an alternative to the design of the first welded connection according to FIG. 4 ;

[0072] FIG. 4 b shows in an enlarged view a third design according to the prior art, which is an alternative to the design of the first welded connection according to FIG. 4 ;

[0073] Figure 5 A meridian section of a welded connection according to the invention between an inner tube and a tube support plate is shown in combination with a fourth embodiment according to the invention and a welding tool;

[0074] 6 shows a meridian cross section of a fifth design of the design of the first welded connection according to the prior art of FIG. 4 ;

[0075] Figure 7 A perspective view shows an embodiment of a tube support plate according to the invention for seven inner tubes;

[0076] Figure 7a A perspective view showing the tube support plate according to Figure 7 Meridian section view of the section marked with "CC" in the figure;

[0077] Figure 7b Use a view to show Figure 7a Meridian cross-sectional view of the tube support plate;

[0078] Figure 8 A perspective view shows an overall view of a closed auxiliary device without an inner tube according to the present invention;

[0079] Fig. 9 Use perspective diagram to show Figure 8 An overall view of a closed auxiliary device with an inner tube secured therein; and

[0080] Fig.10 Corresponding to Fig. 9 The viewing direction indicated by "G" in FIG. Fig. 9 View of the closed assistive device. DETAILED DESCRIPTION

[0081] FIG. 1 shows an embodiment of a tube bundle heat exchanger 100 according to the prior art, in which a plurality of tube bundles 10 are usually connected in series in terms of flow technology by means of connecting elbows 5. The tube bundle 10 according to the prior art consists of a set of multiple inner tubes 16 (see FIGS. 2a, 2b), which extend parallel to one another and are also connected in parallel in terms of flow technology, and which are respectively passed through inner holes 17 (FIG. 3) on the respective plate sides of the first and second tube support plates 12, 14 at the end side and supported there, and are welded to the tube support plates 12, 14 circumferentially on the tube outer diameter of their tube ends on the end faces (front faces) of the tube support plates 12, 14 facing the inner tubes 16. The inner tubes 16 of each set are arranged in outer tubes or outer shell tubes 15 (FIG. 1, 3). Products, such as foods, are guided through the inner tubes 16, and a so-called heat transfer medium, such as water or steam, flows around the outer sides of the inner tubes 16 inside the outer tubes 15. 2 a , 2 b furthermore show in each case an annular gap S which is formed between the outer diameter of each inner tube 16 and the respectively associated plate-side inner opening 17 in the tube support plates 12 , 14 .

[0082] The tube bundle 10 known from the prior art (FIG. 3 - only the components relevant here are marked; see also DE 94 03 913 U1) consists in its broken-away central part of an outer tube 15 (or housing) defining an outer channel 15*, with a housing flange (not marked with respect to the position in the figure) arranged on the left side on the fixed bearing side and a housing flange (not marked) arranged on the left side on the floating bearing side. A first housing with a second inlet 22 is connected to the housing flange on the floating bearing side, and a second housing with a second outlet 24 is connected to the housing flange on the fixed bearing side. A number n of inner tubes 16 extending through the outer channel 15* parallel to the axis of the outer tube 15 and jointly forming an inner channel 16* are supported at the ends in a left tube support plate 12 forming part of the fixed bearing and in a right tube support plate 14 forming part of the floating bearing, and are welded on their outer diameter to the end faces of the respectively associated tube support plates 12, 14 facing the inner tubes 16 by means of a circumferential weld seam SN. This overall arrangement is introduced into the outer tube 15 via an opening (not shown in detail) in the second housing and is clamped to the second housing via the exchanger flange on the fixed bearing side, which accommodates the first inlet 18, with a seal inserted in each case. The inner tube longitudinal axis of the inner tube 16 is designated by R, which has a tube-side inner bore 16a with an inner diameter D. The tube support plates 12, 14 on the fixed bearing side and the floating bearing side each have a plate rotation axis A, which are arranged coaxially with each other and, for the central inner tube 16, also extend coaxially with its inner tube longitudinal axis R. The tube support plate 14 on the floating bearing side is connected to the floating bearing side pipe connection, which accommodates the first outlet 20.

[0083] Depending on the arrangement of the respective tube bundle 10 in the tube bundle heat exchanger 100 and its respective wiring arrangement, the first product P1 to be heat treated can flow through the inner tube 16 from left to right via the first inlet 18 to the first outlet 20 or vice versa, with respect to the position in the figure. In the respective adjacent tube bundles 10 connected in series with the previously described tube bundles via the connecting elbows 5, the relationship between the inlet and outlet is respectively reversed accordingly.

[0084] The outer channel 15* can be loaded with a heat transfer medium, such as water or steam. In so-called product-to-product heat exchange, the heat transfer medium is the second product P2. The flow through the outer channel 15* can be from the second inlet 22 to the second outlet 24 or vice versa. Depending on the orientation of the inner tube 16 and the flow distribution in the inner channel 15*, heat exchange in cocurrent or countercurrent occurs.

[0085] In product-to-product heat exchange, the annular gap S already discussed in conjunction with FIGS. 2a , 2b is cleaning critical, since a second product which may enter here during the product run can only be completely cleaned by excessive CIP cleaning or, under particularly difficult conditions, cannot be adequately cleaned even until the next product run.

[0086] Welding connection

[0087] If the welded connection between the inner tube 16 and the tube support plates 12, 14 is designed as shown with reference to the first welded connection in FIG. 4 and known per se, the annular gap disclosed in FIGS. 2a, 2b and 3 is eliminated. The first welded connection is characterized in that the inner tube 16 is connected with its tube-side inner bore 16a in a plane perpendicular to the inner tube longitudinal axis R to the end face of the disk-shaped tube support plates 12, 14 facing the inner tube 16. The tube-side inner bore 16a and the plate-side inner bore 17 preferably have the same inner diameter D and are aligned with each other. The circumferential circular weld 36 is positioned relative to the tube support plates 12, 14 at a preceding axial positive locking distance B2 of the first positive locking F1, and the tube support plates 12, 14 are necked down in this region to the tube wall thickness d.

[0088] In the unwelded initial position, the inner tube 16 and the tube support plates 12, 14 are fixed to each other by a first positive connection F1 which acts radially and axially and is respectively directed toward each other. For this purpose, the tubular constrictions of the tube support plates 12, 14 have a plate-side inner recess 26 which is oriented coaxially to the inner tube longitudinal axis R and has an axial positive connection depth B1 in the axial direction and which surrounds the tube-side outer recess 32 on the outside and coaxially, which has the same positive connection depth B1.

[0089] The welding tool 40 is introduced into the inner hole 17 on the plate side in the direction of the inner tube axis R until it reaches the planned position of the weld seam 36, and the welding electrode 42 oriented perpendicularly to the inner holes 17, 16a on the plate side and the tube side is used to realize the circumferential circular weld seam 36 in an orbital movement U, and the weld seam is preferably completed in a single layer and continuously from the radial inside to the radial outside. Here, the weld seam width b of the circumferential circular weld seam 36 is set so that it covers the axial form-fitting depth B1 of the first form-fitting F1.

[0090] In each welding process and in the entire welding sequence for all welding of a set of inner tubes 15 to be welded to the associated tube support plates 12 , 14 , the inner tubes 16 and the tube support plates 12 , 14 are pressed against one another with a pressing force PR.

[0091] The inner tube used with an inner diameter D, a tube wall thickness d and an inner tube length L is usually an elongated thin-walled inner tube 16, which is to be welded to the tube support plates 12, 14, which are usually solid and have a plate wall thickness B. The corresponding specific quantitative dimensions depend on the size of the tube bundle 10 and its heat transfer properties and can therefore be considered generally and only roughly given by the following dimensional relationship:

[0092] D / d>10; L / D>100 and B / d>10.

[0093] FIG. 4a shows a second welded connection according to the prior art between an inner tube 16 with an inner hole 16a and a tube support plate 12, 14 with a plate-side inner hole 17 of equal diameter. In the unwelded initial state, the inner tube 16 with a tube wall thickness d and the tube support plates 12, 14 are fixed to each other by a first form-locking F1, which acts radially and axially and is respectively directed toward each other. For this purpose, the tube support plates 12, 14 with their upstream axial form-locking distance B2 have a plate-side outer recess 28 oriented coaxially with respect to the inner tube axis R, which has a recess wall thickness a, which has an axial form-locking depth B1 in the axial direction and which engages coaxially on the inside with a tube-side inner recess 30, which has the same form-locking depth B1.

[0094] 4b shows a third welded connection according to the prior art between an inner tube 16 with an inner bore 16a and a tube support plate 12, 14 with a plate-side inner bore 17 of equal diameter. Here, in order to achieve a first positive connection F1, a plate-side inner recess 26 is provided only in the constriction of the tube support plate 12, 14, which coaxially surrounds the complete tube wall thickness d on the outside with an axial positive connection depth B1, wherein the radial dimension of the wall thickness of the constriction extending over the preceding axial positive connection distance B2 exceeds the tube wall thickness d by the recess wall thickness a.

[0095] The first to third welded connections of FIGS. 4 , 4 a and 4 b are again characterized in that the circumferential circular weld 36 is positioned relative to the tube support plates 12 , 14 at a preceding axial positive locking distance of the first positive locking F1, and the tube support plates 12 , 14 are necked down in this region to one to two times the tube wall thickness d.

[0096] In the fourth welding connection ( Figure 5 ) and the fifth welded connection according to the prior art (FIG. 6), in order to achieve the first form-locking F1, the inner tube 16 having the same inner diameter D in its tube-side inner hole 16a as the plate-side inner hole 17 in the tube support plates 12, 14 is embedded in the end faces of the tube support plates 12, 14 with the full tube wall thickness d and with the axial form-locking depth B1.

[0097] 6 , the axial positive locking depth B1 of the plate-side recess 26 is maximum and is dimensioned such that the necessary weld seam width b completely covers the axial positive locking depth B1 and is thus completely embedded in the tube support plates 12, 13, as viewed from the side of the inner tube 16. This state results from the fact that the circumferential circular weld seam 36 is positioned such that the weld seam width b, as viewed from the side of the inner tube 16, is embedded in the tube support plates 12, 14 at a maximum axial positive locking depth.

[0098] In accordance with Figure 5 In the embodiment, the axial form-fitting depth B1 of the plate-side recess 26 is dimensioned so that the necessary weld width b of the circumferential circular weld 36 is only partially located inside the tube support plates 12, 14 and another part covers a section of the inner tube 16 exposed on the outside.

[0099] In order to avoid discontinuous and, in the present case, abrupt changes in the cross-sectional profile of the wall thickness to be welded, Figure 5 The fourth welded connection according to the invention is further modified compared to the fifth welded connection according to the prior art according to FIG. 6 in that the tube support plates 12, 14 have a circumferential, axially extending, annular gap-like plate-side recess 34 radially spaced apart from the circumferential circular weld seam 36 on the outside. The recess is designed in its radial distance from the weld seam 36 and in its radial width so that the wall thickness of the tube support plates 12, 14 to be welded with the circumferential circular weld seam 36 has a value of one to two times the tube wall thickness d (see also Figure 7a , 7b ).

[0100] method

[0101] 4, 4a, 4b, 5 and 6 described in the first to fifth embodiments of the welded connection expediently utilize the manufacturing method according to the invention by the auxiliary device 50 ( Figure 8 , 9 The starting point of the manufacturing method is that the tube support plates 12, 14 are provided with a tube layout pattern M ( Figure 7 ) for arranging matching inner tubes 16 arranged parallel to each other. The plate rotation axis A of each tube support plate 12, 14 does not necessarily have to be occupied by an inner tube 16. In this case, if the only possible pitch circle cannot accommodate more inner tubes 16 to be arranged on the pitch circle under the given heat transfer conditions ( Fig.10 ; Multiple settings of the pitch circle cannot be achieved using the proposed auxiliary device 50), and there is a limiting extreme value for the number n of inner tubes 16.

[0102] The auxiliary device 50 uses the second form-fitting F2 to fix the required number n of inner tubes 16 to each other in an integrally immovable manner according to the tube layout mode M and to the tube support plates 12, 14 in an immovable manner in the corresponding first form-fitting F1 ( Fig. 9 , 10 During the time period for welding all the inner tubes 16, the tube support plates 12, 14 are pressed against the inner tubes 16 in the direction of the inner tube longitudinal axis R with a pressing force PR ( Fig. 9 ; tube support plates 12, 14 are not shown) and the inner tube 16 is welded to the tube support plates 12, 14 in sequence.

[0103] In this context, an advantageous welding sequence is provided, in which the central inner tube 16 is first welded to the tube support plates 12 , 14 , if present, and then the outer inner tubes 16 arranged around the central inner tube 16 on the pitch circle T are respectively welded to the tube support plates in a relative sequence.

[0104] Auxiliary devices

[0105] The auxiliary device 50 ( Figure 8 , 9 , 10) A welding connection is realized, and the welding connection is designed as follows:

[0106] The inner tube 16 is connected with its tube-side inner bore 16 a in a plane perpendicular to the inner tube longitudinal axis R to the end faces of the disk-shaped tube support plates 12 , 14 facing the inner tube 16 and having plate-side inner bores 17 .

[0107] The tube-side inner opening 16 a and the plate-side inner opening 17 have an inner diameter D of the same size and are oriented in alignment with one another.

[0108] In the unwelded initial position, the inner tube 16 and the tube support plates 12 , 14 are fixed to one another by means of a first form fit F1 , which acts radially and axially and in each case in a direction directed toward one another.

[0109] A circumferential round weld seam 36 is realized along the path starting from the inner opening 17 , 16 a on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside.

[0110] At least the axial form-fitting depth B1 of the first form-fitting F1 is covered by the weld seam width b of the circumferential circular weld seam 36 .

[0111] The auxiliary device 50 comprises a first and a second retaining ring half 50.1, 50.2, which form a closed ring after being spliced ​​together. The retaining ring halves 50.1, 50.2 are in contact with each other in a separation plane E, which extends through the center Z of the auxiliary device 50, and in this separation plane E, the retaining ring halves 50.1, 50.2 are connected by a separation plane contour 50.1a and a separation plane corresponding contour 50.2a ( Figure 8 , 10 ) form a second, immovable form-fitting connection F2 with each other.

[0112] The second positive connection F2 preferably fixes the first and second retaining ring halves 50.1, 50.2 to each other in the radial direction. The first and second retaining ring halves 50.1, 50.2 are also advantageously connected to each other detachably by connecting means 56 arranged on the periphery of the first and second retaining ring halves 50.1, 50.2, for example connecting screws arranged diametrically opposite. As a result, the radially oriented second positive connection F2 is additionally fixed and prevents the retaining ring halves 50.1, 50.2 from axially moving relative to each other.

[0113] The tube support plates 12, 14 define a tube layout pattern M (M) for the inner tubes 16 arranged parallel to each other by providing more than one inner hole 17 arranged on the plate side therein. Figure 7 , 7a , 7b). The tube layout pattern M is reflected in the retaining ring halves 50.1, 50.2 in such a way that the inner tubes 16, which are preferably arranged uniformly distributed on a single pitch circle T, are each surrounded by at most half of the retaining ring halves 50.1, 50.2 ( Fig.10), accordingly realizing the opening of the surrounding contour toward the center Z of the auxiliary device 50. The dividing plane E additionally extends through at least one inner tube longitudinal axis R of the inner tube 16 which is located on the pitch circle T. A retaining means 52 is provided, preferably a cylindrical retaining pin, which is respectively embedded in the retaining ring halves 50.1, 50.2 on the periphery of the retaining ring halves 50.1, 50.2 and movably along the retaining ring axis r with the retaining means axis r oriented in a star shape toward the center Z. The retaining means 52 is tangential to the adjacent inner tube 16 arranged on the pitch circle T on both sides with its circumferential surface. In addition, if necessary, the retaining means 52 fixes the inner tube 16 arranged at the center Z with its corresponding end side facing the center Z and itself can be releasably fixed in this position ( Fig.10 The holding means 52 are fixed immovably by means of fixing means 54 in the respective matching holding ring halves 50.1, 50.2, preferably by means of fixing screws.

[0114] Based on the particularly advantageous pipe layout Figure 7 , 7a In the embodiment of 7b, seven plate-side inner holes 17 are provided, wherein one plate-side inner hole 17 is coaxially arranged relative to the plate rotation axis A, and six plate-side inner holes 17 are evenly distributed on the pitch circle T ( Figure 8 , 9 , 10). In this case, the separation plane E also extends through the inner tubes 16 or inner holes 17 of the plate sides which are arranged opposite each other ( Fig.10 ).

[0115] The fixing of the inner tubes 16 in the auxiliary device 50 by the holding means 52 can be carried out in a manner other than that described above, for example by means of a movable and fixable shaped block, which can be inserted in the axial direction from the side of the auxiliary device 50 facing away from the tube support plates 12, 14 into the annular, releasably separable auxiliary device 50 between the inner tubes 16 and fixes the inner tubes 16 immovably to one another. During the welding operation sequence, the auxiliary device 50 fixes the set of inner tubes 16 immovably relative to one another by means of the second form fit F2 and at the same time adjusts the inner tubes 16 as a whole in the first form fit F1 relative to the tube support plates 12, 14 and presses them against the tube support plates with a pressing force PR, each embodiment of which makes it possible to carry out the production method according to the invention for realizing a welded connection between the inner tubes 16 of the tube bundle 10 for a product-to-product tube bundle heat exchanger 100 and the tube support plates 12, 14.

[0116] Discipline

[0117] The invention also claims a tube bundle 10 for a product-to-product tube bundle heat exchanger 100, such as the tube bundle known in its basic structure from the prior art and shown by way of example in FIG. 3 in conjunction with FIGS. 2a and 2b. In contrast to this known embodiment, the occurrence of a critical annular gap S is avoided in that the tube bundle 10 is welded in this region by means of a production method according to the invention for producing a welded connection between the inner tube 16 and the tube support plates 12, 14, wherein the welded connection is designed as a circumferential round weld seam 36 and the tube support plates 12, 14 have a circumferential, axially extending, annular gap-shaped plate-side recess 34 radially spaced apart from the circumferential round weld seam 36, wherein the recess 34 is designed such that the wall thickness of the tube support plates 12, 14 to be welded by means of the circumferential round weld seam 36 has a value of one to two times the tube wall thickness d.

[0118] The invention also claims a tube bundle 10 for a product-to-product tube bundle heat exchanger 100, such as the tube bundle known in its basic structure from the prior art and shown by way of example in FIG. 3 in conjunction with FIGS. 2a, 2b. In contrast to this known embodiment, the critical annular gap S is avoided in that the tube bundle 10 is welded in this region by means of the auxiliary device 50 according to the invention by means of the production method for producing the welded connection between the inner tube 16 and the tube support plates 12, 14.

[0119] The tube bundle 10 is welded using the production method according to the invention for producing a welded connection between the inner tubes 16 and the tube support plates 12 , 14 and by means of the auxiliary device 50 according to the invention, and comprises a welded connection which is designed as follows:

[0120] The inner tube 16 is connected with its tube-side inner hole 16a in a plane perpendicular to the inner tube longitudinal axis R to the end faces of the disk-shaped tube support plates 12, 14 facing the inner tube 16, said tube support plates having plate-side inner holes 17,

[0121] The tube-side inner hole 16a and the plate-side inner hole 17 have the same inner diameter D and are aligned with one another,

[0122] In the unwelded initial position, the inner tube 16 and the tube support plates 12 , 14 are fixed to one another by means of a first form fit F1 , which acts radially and axially and in each case in a direction directed toward one another,

[0123] A circumferential circular weld 36 is realized along the path starting from the inner opening 17 , 16 a on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside,

[0124] The weld seam width b of the circumferential circular weld seam 36 covers at least the axial form-fitting depth B1 of the first form-fitting F1 , and

[0125] The circumferential circular weld seam 36 is positioned such that the weld seam width b, viewed from the side of the inner tube 16 , engages at most with an axial form-fitting depth B1 into the tube support plates 12 , 14 .

[0126] The invention also claims a product-to-product tube bundle heat exchanger having at least one tube bundle 10, such as the tube bundle known in its basic structure from the prior art and shown by way of example in FIG. 3 in conjunction with FIGS. 2a and 2b. In contrast to this known embodiment, the critical annular gap S is avoided in that the tube bundles are each a tube bundle according to the invention and are welded in this region.

[0127] List of reference numerals of the abbreviations used

[0128] 100 Tube Bundle Heat Exchanger

[0129] 5 Connect the elbow

[0130] 10 Discipline

[0131] 12. First tube support plate

[0132] 14 Second tube support plate

[0133] 15 Outer tube (shell tube)

[0134] 15* External channel

[0135] 16 Inner tube

[0136] 16a Inner hole on the tube side

[0137] 16* Inner channel

[0138] 17 Inner hole on the plate side

[0139] 18 First Entrance

[0140] 20 First Exit

[0141] 22 Second Entrance

[0142] 24 Second Exit

[0143] 26 Recessed area on the side of the plate

[0144] 28 Outer recess on the side of the plate

[0145] 30 Recessed part on the tube side

[0146] 32 External recess on the tube side

[0147] 34 Notch on the side of the board

[0148] 36 Circumferential weld

[0149] 40 Welding tools

[0150] 42 Welding Electrode

[0151] 50 Auxiliary devices

[0152] 50.1 First retaining ring half

[0153] 50.1a Separation plane outline

[0154] 50.2 Second retaining ring half

[0155] 50.2a Separation plane corresponding to the contour

[0156] 52 Retention mechanism (retention pin)

[0157] 54 Fixing mechanism (fixing screw)

[0158] 56 Connection mechanism (connecting screw)

[0159] A Plate rotation axis

[0160] B board wall thickness

[0161] B1 Axial form-locking depth

[0162] B2 Axial positive locking distance of the front

[0163] D inner diameter

[0164] E Separation plane

[0165] F1 First form-locking

[0166] F2 Second form lock

[0167] L Inner tube length

[0168] M-tube layout mode

[0169] P1 First product

[0170] P2 Second product

[0171] PR Clamping force

[0172] R Inner tube longitudinal axis

[0173] S Annular gap

[0174] SN Weld

[0175] T Pitch circle

[0176] U Movement along the track

[0177] Z Center

[0178] a concave wall thickness

[0179] b Welding seam width

[0180] d Pipe wall thickness

[0181] n (number of inner tubes or inner holes)

[0182] r Maintain the longitudinal axis of the mechanism

[0183] D / d>10 The ratio of the inner diameter D of the inner tube 16 to the tube wall thickness d

[0184] L / D>100 The ratio of the inner tube length L to the inner diameter D of the inner tube 16 side

[0185] B / d>10 The ratio of plate wall thickness B to tube wall thickness d.

Claims

1. A production method for producing a welded connection between inner tubes (16) and tube support plates (12, 14) of a tube bundle (10) for a product-to-product tube bundle heat exchanger (100) using an auxiliary device (50), the respective tube support plates (12, 14) being welded with their end faces facing the inner tubes (16), the method being carried out in the following steps (i) to (iii): (i) orienting the inner tube (16) with the corresponding plate-side inner hole (17) provided in the tube support plate (12, 14) such that the inner tube (16) and the plate-side inner hole (17) are aligned with each other; (ii) fixing the respective inner tube (16) and the tube support plate (12, 14) relative to one another in an unwelded initial position by means of a positive fit, which acts in a radial direction and is directed toward one another, Predetermining more than one plate-side inner opening (17) and thereby determining a tube layout pattern (M) for the associated inner tubes (16) arranged parallel to one another via the tube support plates (12, 14); (iii) fixing the corresponding required number (n) of inner tubes (16) as a whole immovably to one another and to the tube support plates (12, 14) in a corresponding form-fitting manner by means of auxiliary devices (50) according to the tube layout pattern (M); It is characterized in that The following steps (iv) to (viii) are included: (iv) during the time period for welding all the inner tubes (16), the end faces of the tube support plates (12, 14) are pressed against the end faces of the inner tubes (16) in the direction of the inner tube longitudinal axis (R) of the inner tubes (16) by means of a first form fit (F1), which acts radially and axially and is respectively oriented towards each other, The inner hole (17) on the plate side and the inner hole (16a) on the tube side of the inner tube (16) have the same inner diameter (D). (v) fixing the corresponding necessary number (n) of inner tubes (16) as a whole in an unmovable manner relative to one another according to the tube layout pattern (M) by means of a second form-fitting (F2) of the auxiliary device (50), the second form-fitting being designed to be releasable; (vi) a circumferential circular weld (36) is realized along the path starting from the inner bore (17, 16a) on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside, the weld width (b) of the circumferential circular weld (36) covering at least the axial form-fitting depth (B1) of the first form-fitting (F1), (vii) welding the inner tube (16) to the tube support plates (12, 14) in sequence, and (viii) Loosening and removing the auxiliary device (50) from the welded pipe arrangement.

2. The manufacturing method according to claim 1, characterized in that: The welding sequence is arranged such that, if there is an inner tube (16) arranged centrally in the tube support plate (12, 14), this central inner tube is first welded to the tube support plate, and then the outer inner tubes (16) arranged around the central inner tube (16) on a pitch circle (T) are respectively welded to the tube support plate (12, 14) in a relative order.

3. An auxiliary device (50) for a production method for producing a welded connection between an inner tube (16) of a tube bundle (10) for a product-to-product tube bundle heat exchanger (100) and a tube support plate (12, 14), the welded connection being designed in a manner known per se: The inner tube (16) is connected with its tube-side inner hole (16a) in a plane perpendicular to the longitudinal axis (R) of the inner tube to the end side of a disk-shaped tube support plate (12, 14) facing the inner tube (16), the tube support plate having a plate-side inner hole (17). The tube-side inner hole (16a) and the plate-side inner hole (17) have an identical inner diameter (D) and are aligned with one another. In an unwelded initial position, the inner tube (16) and the tube support plates (12, 14) are fixed to one another by means of a first form-fit (F1), which acts radially and axially and is respectively directed toward one another. A circumferential circular weld (36) is realized along the path starting from the inner bore (17, 16a) on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside, and The weld seam width (b) of the circumferential circular weld seam (36) at least covers the axial form-fitting depth (B1) of the first form-fitting (F1), It is characterized in that There are first and second retaining ring halves, the first and second retaining ring halves forming a closed ring, The retaining ring halves come into contact in a separation plane (E) extending through the center (Z) of the auxiliary device (50) and in the separation plane (E) the retaining ring halves form a second, non-movable form-fit connection (F2) with one another, The tube support plates (12, 14) define a tube layout pattern (M) for arranging inner tubes (16) arranged parallel to one another by prearranging more than one inner hole (17) on the plate side. The tube layout pattern (M) is reflected in the retaining ring half in such a way that the inner tubes (16) arranged uniformly distributed on a single pitch circle (T) are each surrounded at most half by the retaining ring half, the opening of the correspondingly surrounded contour being oriented toward the center (Z) of the retaining ring half. The separation plane (E) additionally extends through at least one longitudinal axis (R) of the inner tube which lies on the pitch circle (T), A retaining device (52) is provided, which is respectively embedded in the retaining ring half (50.1, 50.2) on the periphery and oriented in a star shape toward the center (Z) so as to be displaceable. The retaining mechanisms (52) are respectively tangent to adjacent inner tubes (16) arranged on a pitch circle (T); and If necessary, the holding means (52) fix the inner tube (16) arranged at the center (Z) with their respective end faces facing the center (Z) and are themselves each releasably fixed in this position.

4. The auxiliary device (50) according to claim 3, characterized in that The second form-fitting connection ( F2 ) fixes the first and second retaining ring halves to one another in the radial direction.

5. The auxiliary device (50) according to claim 3 or 4, characterized in that: The retaining means (52) are each immovably fixed in an associated retaining ring half by means of a fixing means (54).

6. The auxiliary device (50) according to claim 3 or 4, characterized in that The first and second retaining ring halves are releasably connected to one another via connecting means (56) which are arranged on the circumference of the first and second retaining ring halves and are arranged diametrically opposite one another.

7. The auxiliary device (50) according to claim 3 or 4, characterized in that Seven inner tubes (16) are provided, wherein one inner tube (16) is coaxially located at the center (Z), and six inner tubes (16) are evenly distributed on the pitch circle (T); and The dividing plane (E) also extends through two inner tubes (16) which are arranged diametrically opposite each other.

8. A tube bundle (10) for a product-to-product tube bundle heat exchanger (100), the tube bundle being welded using a production method for producing a welded connection between an inner tube (16) and a tube support plate (12, 14) according to claim 1 or 2, the welded connection being designed as a circumferential round weld seam (36) and the tube support plate (12, 14) having a circumferential, axially extending, annular gap-shaped plate-side recess (34) radially spaced apart from the circumferential round weld seam (36), the recess being designed such that the wall thickness of the tube support plate (12, 14) to be welded using the circumferential round weld seam (36) has a value of one to two times the tube wall thickness (d).

9. The tube bundle (10) according to claim 8, characterized in that A production method for producing a welded connection between an inner tube (16) and a tube support plate (12, 14) is carried out using the auxiliary device (50) according to claim 3.

10. The tube bundle (10) according to claim 8 or 9, comprising inner tubes (16) and tube support plates (12, 14) and having welded connections between the inner tubes (16) and the tube support plates (12, 14), which are designed in a manner known per se: The inner tube (16) is connected with its tube-side inner hole (16a) in a plane perpendicular to the longitudinal axis (R) of the inner tube to the end side of a disk-shaped tube support plate (12, 14) facing the inner tube (16), the tube support plate having a plate-side inner hole (17). The tube-side inner hole (16a) and the plate-side inner hole (17) have an identical inner diameter (D) and are aligned with one another. In an unwelded initial position, the inner tube (16) and the tube support plates (12, 14) are fixed to one another by means of a first form-fit (F1), which acts radially and axially and is respectively directed toward one another. A circumferential circular weld (36) is realized along the path starting from the inner bore (17, 16a) on the plate side and the tube side in a single layer and continuously from the radial inside to the radial outside, The weld seam width (b) of the circumferential circular weld seam (36) covers at least the axial form-fitting depth (B1) of the first form-fitting (F1), and The circumferential circular weld seam (36) is positioned such that the weld seam width (b), viewed from the side of the inner tube (16), engages at most at an axial positive-locking depth (B1) into the tube support plates (12, 14).

11. A product-to-product tube bundle heat exchanger (100) comprising at least one tube bundle (10) according to any one of claims 8 to 10.

Images