EP0731328A1 - Heat exchanger with U-tubes, provided with a damping and anti- blowout device for securing tubes - Google Patents

Abstract

The heat exchanger comprises a bundle of tubes (10) bent in a U shape, with a curved section between two straight legs. The tubes are arranged regularly, with all the legs parallel. A bundle envelope (4) surrounds the tube bundle and a number of antivibration bars (15) clamp between adjacent curved tube sections, forming an external bundle end. Connections (20) between these external bar ends, with a support (40), fixed to the bundle envelope, prevent movement. Thus only limited movement of the anti vibration bars and fixings is permitted on a direction parallel to the tube legs. The connections may each comprise a notched (21a) comb (21), receiving the bar ends, with a comb cover (22) and fixings (23).

Description

The invention relates to a heat exchanger comprising a bundle of U-bent tubes and anti-vibration bars between the bent parts of the tubes. The invention applies in particular to a steam generator of a pressurized water nuclear reactor.

The steam generators of pressurized water nuclear reactors comprise U-shaped bent tubes having two parallel straight branches crimped at their ends in a tubular plate.

The ends of the tubes being engaged in openings crossing the tube plate, regularly distributed in a rectangular or triangular distribution, the tubes of the bundle are thus maintained in a regular arrangement in which the straight branches are all parallel to each other and the tubes arranged in flat sheets parallel to each other in each of which the curved parts of the tubes have decreasing radii of curvature from the outside towards the inside of the sheet.

The curved parts of the tubes of each of the layers of the bundle have different radii of curvature and are juxtaposed so as to constitute a structure of substantially hemispherical shape called a bun, at the top of the bundle of the steam generator.

During operation of the steam generator, pressurized water at high temperature circulates in the bundle tubes and drinking water is brought into contact with the external exchange surface of the tubes along which it moves in the vertical direction by heating and then vaporizing, to come out as vapor at the top of the steam generator.

The circulation of fluids in contact with the tubes can cause vibrations which are likely to cause damage to the tubes if they are not maintained effectively.

The right part of the tubes is engaged in spacers located at regular distances from each other according to the height of the beam. These straight parts are therefore effectively maintained by rigid elements. The curved parts of the tubes of the bundle constituting the bun must also be maintained and generally used for this purpose anti-vibration bars which are interposed each between two plies of adjacent tubes of the bundle and arranged in substantially radial directions of the bun. These anti-vibration bars as described for example in patent US-A-3,007,679 are generally connected two by two of their ends inside the bun and placed angularly to form V-shaped structures.

The outer ends of the antivibration bars opposite their central part project from the tubes constituting the outer layer of the bun and are interconnected by connecting means ensuring the maintenance of the antivibration bars.

Various means of connecting the outer ends of the antivibration bars have been proposed using fastening elements placed above the upper surface of the bun.

It was first proposed as for example in US-A-3,007,679 to weld the ends of the anti-vibration bars on curved elements called pins arranged in meridian planes of the bun.

The fixing of the antivibration bars implementing welds which must be carried out in the vicinity of the tubes of the bundle creates a risk of deterioration at the level of the tubes.

Mechanical connection devices have therefore been proposed making it possible to connect the outer ends of the anti-vibration bars to fastening parts such as retaining rings arranged above the outer surface of the bun.

In patent FR 2 644 281 filed by FRAMATOME, provision has been made to install arches of substantially semi-circular shape on which are fixed brackets perpendicular to the arches and arranged opposite each end of the anti-vibration bar. A mechanical system makes it possible to connect the ends of each anti-vibration bar to the corresponding bracket.

Mechanical connection devices have also been proposed making it possible to connect the outer ends of the antivibration bars by mechanical connections arranged so as to group successive sets of ends of antivibration bars.

In FR-A-2,664,965, filed by FRAMATOME, a wedging device has been proposed comprising connecting means between the outer ends of anti-vibration bars arranged in sets of at least two bars in which the bars are aligned and have aligned through openings, one of which is tapped. The connecting means of the anti-vibration bars comprise a pin which is inserted into the aligned openings of the set of anti-vibration bars and into the bore of spacers which are each inserted between two successive anti-vibration bars. The spindle which has a threaded end is screwed into the tapped opening of an anti-vibration bar located at the end of the row. The spindle is also secured to a rotation blocking element which can be welded to a spacer. Such a device has advantages over previously known mechanical devices but requires the use of pins whose length is adapted to the number of bars and to the length of the row of anti-vibration bars, the ends of which are assembled together. In some cases, it is necessary to use a very long spindle, which can have drawbacks with regard to the installation conditions and the mechanical strength of the spindle.

In patent FR 93 / 12.514, filed by FRAMATOME, an anti-vibration wedging device has been proposed comprising connecting means between the outer ends of the anti-vibration bars arranged in sets of at least two bars in which the bars are aligned and comprise aligned through openings. The connecting means between the ends of the anti-vibration bars include a screw whose head is intended to come to bear on a first anti-vibration bar and whose threaded rod is screwed into a spacer. The spacer is fixed either in a second spacer, or in a threaded fixing element, by a threaded part. The threaded parts of the screw and the spacer pass through the anti-vibration bars through aligned openings.

The disadvantage of these anti-vibration devices which have just been mentioned is that they have a large number of mechanical elements to be assembled, which lengthens the assembly time and creates a risk of dispersion of certain elements during assembly, during operation and during maintenance operations.

All anti-vibration wedging devices comprising anti-vibration bars require an anti-take-off device to keep them inside the bun.

In the patent US-A-3,007,679 already cited, we used anti-take-off stirrups constituted by U-shaped parts welded on the pins and trapping several tubes of the tube bundle inside the U so as to make the pins and anti-vibration bars integral with the tubes.

Anti-theft stirrups are also used in patents FR 2 644 281, FR-A-2 664 965 and FR 93 / 12.514, their fixing being ensured by mechanical means in order to avoid welding.

However, the anti-take-off stirrups have the drawback of maintaining the anti-vibration device, by making the retaining force bear on certain tubes of the bundle, the tubes being a sensitive element in the operation of the steam generator, we therefore sought to carry out the restraint effort from elements other than the tubes

In FR-A-91-14655 filed by the company FRAMATOME, means of fixing the anti-vibration bars have been proposed to prevent their ejection outside the bundle in the steam generator in service, which comprise an elongated structure fixed on the spacer plate of the steam generator closest to the curved parts of the tubes constituting the bun. The elongated structure generally constituted in the form of a rail is fixed on the upper face of the spacer plate, in a direction perpendicular to the plies of tubes, inside the central free space constituting the water street of the generator. steam. The elongated fixing structure comprises, at each of the spaces between two pairs of plies of adjacent tubes, at least one notch in which the internal part of the anti-vibration bar can be engaged.

This anti-theft device while eliminating the aforementioned drawback of making the effort bear retained on the tubes, requires during assembly operations a fairly long installation, taking into account the positioning of the anti-vibration bars in a large number of notches and does not ensure complete support in position of the anti-vibration device.

The object of the invention is therefore to propose a heat exchanger comprising a bundle of U-bent tubes so as to have two straight branches and a curved part between the two straight branches, the bundle tubes being located in a regular arrangement in which the straight branches are all parallel to each other and the tubes arranged in planar plies parallel to each other, a bundle envelope surrounding the bundle of tubes, a plurality of anti-vibration bars interposed between the adjacent plies of the tubes in their curved part, to present an end outside the bundle, connecting means between the outer end parts of the anti-vibration bars and an anti-take-off device which does not bring the retaining force onto the bundle tubes, which is d '' simpler mounting than known devices and which ensures complete retention of the anti-vibration bars ires and their means of connection.

For this purpose, all of said connecting means is connected to at least one support integral with the bundle envelope so as to constitute the anti-theft device of the anti-vibration bars allowing limited movement of the set of anti-vibration bars and of their connecting means in a direction parallel to the straight branches of the tubes.

Another object of the invention is to provide a heat exchanger comprising a bundle of U-bent tubes so as to have two branches straight and a curved part between the two straight branches, the tubes of the bundle being located in a regular arrangement in which the straight branches are all parallel to each other and the tubes arranged in flat sheets parallel to each other, a bundle envelope surrounding the bundle of tubes, a plurality of anti-vibration bars inserted between the adjacent plies of the tubes in their curved part, so as to present an end outside the bundle and connecting means between the external end parts of the anti-vibration bars in a plurality sets of at least two bars in which the bars are aligned, designed to limit the number of connecting pieces and to facilitate assembly.

• un peigne possédant des encoches aptes à recevoir les extrémités des barres antivibratoires,
• un couvercle de peigne destiné à fermer les espaces constitués par les encoches,
• des moyens de fixation du couvercle sur le peigne.

For this purpose, the connection means comprise, for each of the sets of aligned anti-vibration bars:

• a comb having notches capable of receiving the ends of the anti-vibration bars,
• a comb cover intended to close the spaces formed by the notches,
• means for fixing the cover to the comb.

In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the appended figures, a steam generator of a pressurized water nuclear reactor and a setting device according to the invention associated with this steam generator.

Figure 1 is an elevational view in partial section through a vertical plane of a steam generator of a pressurized water nuclear reactor.

FIG. 2 is a schematic sectional view of the upper part of the bun in a plane perpendicular to that of FIG. 1.

FIG. 3A is a detailed sectional view of FIG. 1 showing the ends of the anti-vibration bars on a part of the bun with a schematic representation of the connection means in the case of a steam generator having an array of square pitch tubes.

FIG. 3B is a view similar to the view in FIG. 3A, in the case of a steam generator having a bundle of tubes with triangular pitch.

Figure 4 is a perspective view of a portion of the tube support device according to the invention showing the connecting means and the anti-flight device.

FIG. 4A is a detailed view of a support pad for the connection means on a tube.

Figure 5 is a perspective view of a detail of the tube support device.

Figure 5A is a sectional view of a detail of the central comb.

Figure 6 is a sectional view showing the anti-theft device.

In FIG. 1, we see a steam generator of a pressurized water nuclear reactor generally designated by the reference 1.

The steam generator comprises an outer casing 2 representing a lower part 2a having the shape of a cylindrical shell in which the bundle of tubes 3 of the steam generator is disposed, inside a bundle casing 4. The part upper 2b of the envelope 2 of the steam generator 1 has a diameter greater than the diameter of the lower part 2a and contains means for separating and drying the steam produced in contact with the bundle 3.

The lower end portion of the shell 2a of the casing 2 is integral with a tubular plate 5 of very thick which is crossed by openings in which the bundle tubes 3 are introduced and fixed by welding and crimping (mechanical or hydraulic for example). On the tube plate 5 is also fixed, opposite the shell 2a of the casing 2, a hemispherical casing 6 delimiting the water box of the steam generator in two parts separated by a partition 7.

Each of the two parts of the water box is connected by a tube to the primary circuit of the nuclear reactor in which the water circulates under cooling pressure of the reactor core.

The bundle 3 consists of tubes 10 which are bent and have a U-shape. Each of the tubes 10 comprises two rectilinear branches 10a, 10b and a substantially semi-circular curved part 10c between the straight branches 10a and 10b.

The ends of the branches 10a and 10b are engaged and crimped in openings passing through the tubular plate 5, on either side of the partition 7.

The straight branches 10a, 10b of the tubes 10 of the bundle are also engaged in openings passing through spacer plates 8 arranged spaced apart according to the height of the bundle. The network of openings of each of the spacer plates reproduces the network of openings of the tubular plate 5, so that the branches 10a and 10b are maintained in parallel arrangements.

In addition, the network of openings of the tubular plate 5 and of the spacer plates 8 comprises rectilinear rows in which the straight branches of tubes 10 are engaged, the curved part 10c of which has a decreasing radius of curvature from the outside towards the inside the beam. The bundle tubes thus constitute successive layers 12 which are visible in particular in FIG. 2. In each of the layers, the radii of curvature of the curved parts 10c or tube hangers are decreasing from the outside to the inside, that is to say from top to bottom; in addition, the radius of curvature of the outer tube of the sheet having the maximum radius of curvature decreases from the inner central part towards the outside of the bundle.

As a result, the bun 9 constituted by the hangers 10c juxtaposed with the tubes 10 has a substantially hemispherical shape. The networks of engagement openings of the tubes of the tube plate 5 and of the spacer plates 8 are interrupted at the central part of the plates in a diametrical direction, so as to delimit a free space or street of water 11 at the central part of the beam between the branches of the tubes having the smallest radii of curvature under the small hangers which are aligned in the diametrical direction of the water street 11.

The steam generator 1 comprises a torus 13 disposed above the upper part of the bundle envelope 4 in which the bun 9 is placed.

When the steam generator is in operation, pressurized water for cooling the reactor enters one of the compartments of the water box so as to be distributed inside the branches 10a of the tubes 10 of the bundle opening into this entry compartment. The pressurized water circulates inside the tubes to exit into the second compartment of the water box through the second branches 10b of the tubes 10. The water recovered at the outlet of the tubes of the bundle is returned to the reactor vessel nuclear via a primary circuit pipe.

The feed water introduced into the envelope of the steam generator 2 through the feed toroid 13 circulates from top to bottom in an annular space formed between the bundle envelope 4 and the outer casing 2 of the steam generator then enters the inside of the bundle casing 4 to come into contact with the tubes 10 above the upper face of the tube plate 5. The supply water circulates from bottom to top inside the bundle, in contact with the tubes and heats up then vaporizes by heat exchange with pressurized water circulating inside the tubes. The vapor formed in contact with the bundle tubes is sent to the upper part 2b of the steam generator to be dried and then discharged through the upper end 14 of the steam generator.

The bundle tubes inside each of the flat plies of tubes 12 are placed so as to have a certain spacing and the plies are also arranged with respect to each other, with a certain spacing. The steam generator feed water can thus circulate in contact with the entire external surface of the tubes.

The water circulating at high speed in contact with the surface of the tubes generates vibrations of these tubes 10 whose straight branches are perfectly maintained by the spacer plates 8.

To maintain the hangers 10c of the tubes, inside the bun 9, there are anti-vibration bars 15 in each of the free spaces between two adjacent sheets 12, so that the branches of the anti-vibration bars are placed in radial directions and that two successive branches along the outline of the hangers 10c make between them a substantially constant angle.

There are generally between two adjacent plies 12 of the bundle, three anti-vibration bars 15 in the shape of a V comprising as a whole six branches placed with a substantially constant angular distribution.

The outer ends 15b of the branches of the anti-vibration bars project from the upper surface of the bun and allow the fixing of the anti-vibration bars.

Thereafter, an anti-vibration bar will designate any branch of a V-shaped assembly 15.

In Figures 3A and 3B, there is shown in a sectional view of the plies of tubes in their upper part, part of a wedging assembly according to the invention, in the case of a bundle of tubes held in an arrangement with square mesh network and in the case of a bundle of tubes held in a triangular mesh network arrangement, respectively.

The bundle tubes are held in a regular network arrangement by the openings of the tube plate 5 and by the through openings of the spacer plates 8 which comprise networks of similar openings.

The arrangement of the tubes in the case of a triangular mesh network results in particular in a smaller space between the successive layers of tubes than in the case of a square mesh network.

The device according to the invention applies as well in the case of a network of tight tubes with triangular meshes as in the case of a network with square meshes.

In FIGS. 3A and 3B, the corresponding elements bear the same references with, however, the sign ' (prime) in the case of the elements in Figure 3B relating to a triangular mesh network.

FIGS. 3A and 3B show the tubes 10 or 10 ′ of the network of tubes constituting the external layers of the bun of the steam generator.

The tubes 10 or 10 ′ constitute successive parallel plies between which the anti-vibration bars 15 or 15 ′ are interposed.

In the part of the bundle of tubes of the steam generator constituting the bun, the layers of tubes are formed by the upper bent portions of the juxtaposed tubes and with decreasing radii from the outside towards the inside of the bun.

The anti-vibration bars 15 have ends 15b projecting outside the bun and arranged in alignment with one another to form alignments of variable length.

The projecting ends 15b of the antivibration bars are connected together by connecting means 20 making it possible to ensure the connection of two or a greater number of antivibration bars constituting a set of aligned bars.

Likewise, the end parts of the anti-vibration bars 15 ′ interposed between the plies of tubes arranged in a triangular mesh network as shown in FIG. 3B can be connected by means of connection means 20 ′ making it possible to link together the ends of a set of two or more anti-vibration bars.

Reference will now be made to FIG. 4 to describe the connection means 20 of a wedging device according to the invention making it possible to connect the ends of the anti-vibration bars 15 to one another.

Each of the connecting means 20 consists of an elongated piece 21 called a comb and comprising notches 21a, of a closing bar constituting the cover 22 intended to be positioned on the notches 21a, and means for fixing the cover to the comb constituted by one or more screws 23. The notches 21a are dimensioned so as to receive the ends of the anti-vibration bars 15. A comb 21 has at least two notches to allow the connection of the anti-vibration bars. The central comb which turns out to be the most important can comprise for example, up to thirty notches.

In order to improve the retention of the ends of the anti-vibration bars 15 in the connecting means 20, preferential anti-vibration bars 15 are used which have notches in their end part. The notches of the antivibration bars 15 are positioned facing the notch of the comb so as to come to fit on the bottom of the notch of the comb, which ensures the effective maintenance of the end of the antivibration bar on the means of connection 20. In all cases, the depth and the width of the notches of the comb are dimensioned so that the section of the anti-vibration bar 15 situated in the notch 21a of the comb comes approximately to fill said notch.

The comb 21 has one or more tapped holes arranged between the notches on the face where the openings of the notches are located and intended to receive the connecting screws 23.

The cover 22 has the form of an elongated bar and has one or more holes for the passage of the connecting screws 23.

When the anti-vibration bars, the ends of which are aligned, are introduced into the notches 2la of the comb 21, the cover is fixed above the said notches by means of screws 23 which are introduced into the tapped holes of the comb. One or two welding points between the head of each screw 23 and the cover 22 of the comb 21 locks the screws 23 in rotation.

Finally, certain combs have complementary tapped holes arranged in the face where the openings of the notches are located and also in the end face of said combs, as will be explained below.

In order to ensure the correct positioning of the connection means 20 and the antivibration bars 15 with respect to the tubes 10 of the bundle and more particularly with respect to the bun 9, stops 24 composed of a shoe 25, a jumper 26 and d 'A screw 27, are installed on the combs and come to bear on certain tubes 10 located towards the outside of the bun 9. The detailed drawing of the stop 24 is shown in Figure 4A.

The shoe 25 has the shape of a small elongated plate, it has a rounded profile 25a recessed the size of the outside profile of a tube 10, this rounded profile represents the bearing surface on the tube; the width of said stop is slightly greater than the diameter of a tube except on a part where the stop has two recesses 25b; said abutment has an oblong hole between the two recesses, arranged lengthwise to allow adjustment of the position of the abutment during assembly.

The rider 26 has a section in the shape of an inverted U, its length is substantially that of the recesses of the shoe 25, it is equipped with an oblong hole and is positioned on the shoe 25, at the level of the recesses.

The screw 27 secures the shoe 25 and the rider 26 on the comb 21 by screwing into a threaded hole existing on the comb.

A weld between the rider 26 and the comb 21 ensures the final positioning of the shoe 25. A weld point between the screw head 27 and the rider 26 ensures the inessibility of the screw 27.

The connecting means 20 connecting the ends of the anti-vibration bars 15 located in the same meridian plane of the bun are all integral with one another by the fact that two successive connecting means 20 trap one end 15 b of the common anti-vibration bar 15 which is therefore located inserted into two successive combs 21.

In the case where the combs 21 have a sufficient number of notches, it is preferable to use two ends of anti-vibration bars 15 in common, inserted in two successive connecting means in order to obtain better rigidity of the assembly.

The ends of anti-vibration bars 15 connected to two successive connecting means then have two notches to be inserted into the notches of the two successive combs.

When all the connecting means 20 are installed, all the ends 15b of the anti-vibration bars 15 are positioned in one or two notches of the combs 21.

In the common case where there are three anti-vibration bars 15 in the form of V of different but identical openings between each ply of tubes, six sets of ends of anti-vibration bars 15 are thus connected substantially along meridians of the bun in planes perpendicular to the plane of the flat layers 12. The set of connecting means 20 of the same meridian is called the end connecting set. Each of these end linkage assemblies is integral with another end linkage assembly located on the antivibration bars of the same opening, but it is independent of the other 4 end linkage assemblies.

In order to ensure the connection between all of the end connection assemblies, arches 30 are arranged arranged in parallels of the hemispherical shape of the bun, arranged outside of the bun 9 and connecting together the various end connection assemblies .

The connection between the hoops 30 and the connecting means 20 is achieved by the fact that each hoop is connected to a comb 21 of each assembly for connecting the ends. The connection between a hoop 30 and a comb 21 is carried out by a screw 31 passing through the hoop 30 in which a hole has been arranged and which is screwed into the tapped hole located in the end face of the comb 21 and described above.

For example, there will be seven arches 30 to hold all the ends of the anti-vibration bars in a rigid assembly. The different arches 30 have different radii depending on their location above the bun.

There may exist a central arch 30 with a larger radius located in the plane of FIG. 2, its connection with the central comb 21 of each end connection assembly takes place in the middle of said comb.

Referring to Figure 5, there is shown the connection between a central comb 21 and the central arch 30.

The positioning of the bundle tubes and the anti-vibration bars can be carried out according to the method described in patent FR-A-2 603 364 from the company FRAMATOME. According to this method, the tubes are mounted in successive layers from the largest layer located in the center according to the plane of FIG. 1 towards the layers of decreasing size and progressively inserting the anti-vibration bars, when half of the beam is mounted, the steam generator is rotated 180 ° along its axis then located in a horizontal position and the other half of the bundle is mounted, starting from the largest dimension of the layer towards the decreasing sizes of layers.

In order to be able to install the central arch 30 and the central comb 21, there is a central comb composed of two half-combs, the longitudinal assembly of which is carried out by a dovetail type assembly as shown in FIG. 5A . Each half-comb is equipped with a support console 28 which is screwed with the cover 22 of the comb.

When we start the assembly phase of the tubes of the second half of the tubes, we insert the second half-comb on the first half-comb using the dovetail.

The support brackets 28 are mounted with the covers of each half-comb and have a tapped hole to receive a fixing screw. The hoop is fitted with lugs 29 which are fixed by means of a fixing screw, passing through the lug and being screwed into the tapped hole of the support brackets 28.

Referring now to FIGS. 4 and 6, it can be seen that the assembly of the anti-vibration wedging device constituted by the anti-vibration bars 15, the end connection assemblies and the arches 30, is held by an anti-flight device.

In fact, the previously described wedging device can move as a whole between the plies of tubes. The initial positioning of the device produced during assembly could be modified in particular during the operation of the steam generator. As indicated in the description of the invention, devices with anti-flight stirrups retained by the tubes or with a rail on the spacer plate located near the bun were used.

In the case of the present invention, supports 40 are used which are fixed to the bundle casing 4 and connected to the anti-vibration wedging device.

The anti-take-off device which we will describe could be used with an anti-vibration wedging device different from that described above and in particular at the level of the connections of the ends of the anti-vibration bars. The support 40 intended to ensure the anti-takeoff function consists of a metal tab 41 rigidly fixed, by welding on the bundle envelope 4. The support tab 41 has at its end opposite to the bundle envelope 4, a hinge 42 intended to receive a dowel 44. The dowel 44 is arranged in a direction parallel to the axis of the steam generator.

At each end of the arches 30 is disposed a lug 32, rigidly fixed by welding and integral with the arch.

In the most common case the steam generator is arranged with its axis in vertical position as shown in Figure 1. The following description is therefore made in this configuration. If the steam generator was in a horizontal position the terms of positioning should be adapted accordingly.

The tab 32 is substantially flat and disposed in a substantially horizontal position, below the hinge 42 and the support tab 41, which are located in the extension of one another with their lower faces located in the same horizontal plane 43.

The tab 32 has an opening 33 of dimensions slightly larger than that of the section of the plug 44.

The pin 44 longer than the length of the hinge 42 is introduced into the hinge 42 so as to protrude a few millimeters above the hinge 42, and several centimeters below the hinge 42 by crossing the opening of the tab 32. It is then welded, in the upper part, by a weld 45 on the upper face of the hinge 42 .

During assembly, there is a clearance J between the underside of the hinge 45, located in a horizontal plane 43 and the upper face of the tab 32. This clearance can be materialized by the provisional positioning of a wedge (not shown) between the aforementioned faces.

The clearance J during assembly, at room temperature decreases during operation at high temperature. A clearance J will therefore be produced so that there is still a weaker clearance under the operating conditions.

The device thus constituted with the supports makes it possible to ensure that the whole of the anti-vibration wedging device will be well maintained in a position close to that established during assembly, and limits both the vertical movement of the anti-vibration device upwards. steam generator and its tilting.

In order to allow the system sufficient freedom of movement, the opening 33 in the tab 32 is larger than the pin 44 and therefore allows limited movement of the support device in a horizontal plane.

Finally, to complete the device, a washer 46 is positioned at the lower end of the dowel 44 and fixed to said dowel by a weld 47, this makes it possible to ensure that the tab 32 of the hoop 30 can in no way case come out of its threaded position on the ankle 44.

The support device thus described is reproduced at the two ends of the arch 30. there are seven arches 30 as indicated previously, preferably fourteen supports will be installed distributed around the periphery of the bundle envelope 4.

The invention is not limited to the embodiment which has been described.

The device for fixing the ends of the anti-vibration bars could be produced according to a device already known and be associated with anti-theft supports such as that which has been described.

The anti-take-off device could be produced in a different way, on the condition of allowing the production of a limited clearance for the movement of all of the connecting means.

The anti-vibration bars may be of a different shape from that which has been described.

The invention applies in the case of any steam generator or heat exchanger comprising a regular network of tubes comprising curved parts between which are inserted anti-vibration bars.

Claims (16)

Heat exchanger comprising a bundle of tubes (10) bent in a U so as to present two straight branches (10a, 10b) and a curved part (10c) between the two straight branches (10a, 10b), the bundle tubes being located in a regular arrangement in which the straight branches (10a, 10b) are all parallel to one another and the tubes (10) arranged in planar plies parallel to each other, a bundle envelope (4) surrounding the bundle of tubes (10), a plurality of anti-vibration bars (15) interposed between the adjacent plies of the tubes in their curved part, so as to present an end outside the bundle, connecting means (20) between the outer end parts of the anti-vibration bars (15) and an anti-theft device characterized in that all of said connecting means (20) is connected to at least one support (40) integral with the bundle envelope (4) so as to consti kill the anti-theft device of the anti-vibration bars by allowing limited movement of all the anti-vibration bars and their connecting means in a direction parallel to the straight branches of the tubes. Heat exchanger according to claim 1, characterized in that the connecting means (20) of the ends of the anti-vibration bars (15) comprise: - first connecting means (20) connecting the ends of the bars situated substantially in planes perpendicular to the planes of the flat plies and constituting connection assemblies for the ends, - second connecting means connecting the connecting sets of the ends. Heat exchanger according to claim 2, characterized in that the second connecting means connecting the end connection assemblies comprise at least one hoop (30) disposed in a plane substantially parallel to the planes of the flat plies. Heat exchanger according to claim 3, characterized in that at least one hoop (30) is connected to the support (4a) integral with the bundle envelope. Heat exchanger according to any one of the preceding claims, characterized in that the anti-theft device also allows a limited relative displacement in all directions between each support (40) integral with the envelope and the connecting means (20) of the ends of the anti-vibration bars. Heat exchanger according to any one of the preceding claims, characterized in that the arch (30) comprises a tab (32) substantially horizontal with a window (33) in which is inserted a plug (44) substantially parallel to the straight branches of the tubes and integral with the support (40), said support being located on the same side of the tab as all of the connecting means. Heat exchanger according to claim 6, characterized in that the window (33) has larger internal dimensions than the external dimensions of the plug (44) in order to allow movement in the two dimensions located in the plane perpendicular to the straight branches tubes. Heat exchanger according to claim 6, characterized in that a cold clearance J is provided sufficient between the tab (32) of the arch (30) and the part of the support (40) located opposite the tab so that 'there is still a hot play during the operation of the heat exchanger. Heat exchanger comprising a bundle of tubes (10) bent in a U so as to present two straight branches (10a, 10b) and a curved part (10c) between the two straight branches (10a, 10b), the bundle tubes being located in a regular position in which the straight branches are all parallel to each other and the tubes (10 ) arranged in plane plies parallel to each other, a bundle envelope (4) surrounding the bundle of tubes (10), a plurality of anti-vibration bars (15) interposed between the adjacent plies of the tubes in their curved part, so as to present one end outside the bundle and connecting means (20) between the outer end parts of the anti-vibration bars (15) in a plurality of sets of at least two bars in which the bars are aligned, characterized by the fact that the connecting means (20) comprise, for each of the sets of aligned anti-vibration bars: - a comb (21) having notches (21a) capable of receiving the ends of the anti-vibration bars (15), - a comb cover (22) intended to close the spaces formed by the notches, - fixing means (23) of the cover on the comb. Heat exchanger according to claim 9, characterized in that the means for fixing the cover to the comb consist of tapped holes located in the comb and screws (23) which are placed in said tapped holes. Heat exchanger according to any one of claims 9 and 10, characterized in that the anti-vibration bars (15) have notches intended to be positioned facing the corresponding notches of the combs, so as to allow a maintenance preventing any relative movement between the antivibration bars and the connecting means (20). Heat exchanger according to any one of Claims 9 to 11, characterized in that the connection means (20) situated in the same plane perpendicular to the planes of the flat sheets are connected to one another by the ends of certain anti-vibration bars (15), which are inserted in two successive combs. Heat exchanger according to any one of claims 9 to 12, characterized in that the combs (21) are positioned relative to the tubes of the tube bundle by means of a support device (24) fixed on the comb and having a bearing surface which comes to cooperate with the external profile of certain tubes (10). Heat exchanger according to claim 13, characterized in that the support device (24) consists of a shoe (25) held on the comb (21) by a jumper (26) and fixed by a screw connection (27) . Heat exchanger according to any one of claims 9 to 14, characterized in that the end connection assemblies constituted by the successive connection means located in planes perpendicular to the planes of the flat layers are connected together by at least one hoop (30) parallel to the planes of the flat layers. Heat exchanger according to claim 15, characterized in that at least one hoop (30) is connected to a support (40) integral with the bundle envelope (4) so as to constitute an anti-theft device for the assembly anti-vibration bars.

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