WO1992008941A1

WO1992008941A1 - Heat exchanger with ducts formed by plates

Info

Publication number: WO1992008941A1
Application number: PCT/FR1990/000824
Authority: WO
Inventors: Philippe Marchal; Christian Bonigen
Original assignee: Packinox S.A.
Priority date: 1989-05-22
Filing date: 1990-11-16
Publication date: 1992-05-29
Also published as: FR2647198B1; FR2647198A1

Abstract

The heat exchanger comprises an annular chamber (19) for circulating a first heat exchanging fluid, said chamber comprising an annular array of ducts (1) for circulating a second heat exchanging fluid, preferably in countercurrent to the first. Said ducts (1) are defined by walls which radiate outwardly from the centre and cooperate like those of a plate heat exchanger, said walls being made by folding corrugated plates over themselves lengthwise to form ducts (1) having a radially elongate section.

Description

PLATE DUCT HEAT EXCHANGER

The invention relates to a plate type heat exchanger.

In] es known plate heat exchangers exchange surfaces generally consist of a stack of parallel flat plates. These plates have undulations which increase the exchange coefficient and which guide the circulation of the two fluids from one end to the other of the plates. Such exchangers are not suitable for all applications. In certain cases, their use involves a high cost for the heat transfer, if only for fluids whose low specific masses lead to passage sections making distribution of the fluids difficult in the exchanger and between the plates.

The invention relates to the design of a heat exchanger in which the pressure losses linked to the mode of distribution of the fluids on the exchange surfaces are low compared to those which are linked to the heat exchange surfaces proper, even under low fluid pressures. It also aims to allow large exchange surfaces, whose size is reduced.

According to its main characteristic, the present invention relates to a heat exchanger, characterized in that it comprises an annular circulation chamber for a first heat exchange fluid in which are distributed longitudinal conduits for circulation of a second fluid heat exchange, preferably against the current of the first, and in that said conduits are limited by radial walls in radiating arrangement in said chamber and in cooperative relationship with each other like those of a plate exchanger, said walls being constituted by corrugated plates closing conduits of elongated section and flared radially.

REPLACEMENT SHEET The radiating arrangement of the walls and 3'obten¬ tion of conduits of elongated section make it possible to considerably increase the heat exchange surfaces between the two fluids, even at low pressure, while reducing the volume occupied by the exchange surface, which leads to a more compact exchanger than 3rd prior devices for the same exchange surface.

Said walls advantageously have longitudinal undulations forming ridges among which the crests of the undulations of a first wall of a duct are supported on crests of the undulations of a second wall of said duct.

The amplitude of the corrugations of the walls gradually increases from the edge of the wall proximal to the axis of the radiating arrangement to the edge of the distal wall of said axis, so as to provide conduits of elongated section increasing from one end of the conduit , proximal of said axis, to one end of the same duct, distal of said axis, between an internal ferrule and an external ferrule limiting the annular chamber.

In order to compensate for the variations in pressure drop in the same duct due to its increasing section, the longitudinal undulations of the walls are advantageously inclined alternately in one direction or another with respect to said proximal edges, and the angle of inclination is smaller for the corrugations of the wall close to its proximal edge of the axis, than for the corrugations close to its distal edge of the axis, the increase in the angle being able to be gradual as and the corrugation is close to said distal edge, or be produced by zones, the corrugations of a wall preferably being divided into three zones, the angles of inclination of the corrugations of the same zone being identical, and those of the corrugations of a following zone, progressing towards said distal edge, being superior. For manufacturing reasons it is preferred that the increase in

REPLACEMENT SHEET 3'ang3.e is carried out by zones, the undulations of a wall preferably being divided into three zones, the angles of incision of the undulations of the same zone are identical, and those of the undulations of a following zone, progressing towards said distal edge, are greater, the undulations all having an identical pitch.

According to an alternative embodiment of the corrugations, the variations in pressure drop in the same duct are advantageously compensated for by the fact that the longitudinal corrugations of said walls are inclined alternately in one direction or another with respect to said proximal edges. , and in that the pitch of the undulations of the same wall increases as the undulations are close to said distal edge of the duct, the angle of inclination of the undulations being identical for all the undulations of a same wall.

The conduits advantageously consist of a metal plate which is formed by explosion and which is folded back on itself to form two facing walls limiting the same conduit and welded at the end to close this conduit, preferably according to the proximal generatrix of the conduit .

Between two fluids of different pressures, it is preferable to circulate the high pressure fluid in the annular chamber outside the conduits in order to avoid the risks of deformation of the conduits on their longitudinal edges, the forces of pressure exerting a push on the outside of the distal rounding formed by the fold. On the other hand, the fact that the crests of the corrugations bear one on the other makes it possible to reduce the thickness of the sheet used and thus the weight of the exchanger, insofar as the risks of deformation of the sheets are reduced. ducts in the case of an external pressure greater than the internal pressure.

The plate advantageously has on its periphery a frame with a smooth surface including two edges.

SUBSTITUTE SHEET 3ongitudinaux are intended to come into leaktight support 3 'one on the other when 3a plate is folded and constitute 3es known proximal edges of the walls; and in a central part, a 3ongitudinal zone with a smooth surface, intended to allow the folding of the plate, which constitute said distal edges of the walls. The corrugations are preferably recessed and projecting alternately by their ridges with respect to said surround around the plate.

The conduits thus produced make it possible not only to organize the circulation of the second fluid in the conduits, but also the circulation of the first fluid in the annular chamber, between the conduits, in particular because of the favorable consequences brought about by the fact that the crests of the corrugations radiating walls of two adjacent conduits bear advantageously on one another.

The annular chamber of the exchanger according to the invention is advantageously closed at each of its ends by an annular disc further constituting means for assembling the conduits, each disc having in its section a series of openings in radiating arrangement. , each opening being intended to receive one end of a conduit, each end section of a conduit being in leaktight support by welding against an opening of said disc.

The entire bundle of conduits is thus held mechanically by two annular discs which also help organize the circulation of fluids.

According to other characteristics of the invention:

- The exchanger advantageously comprises means for organizing the circulation of a first thermal fluid in said annular chamber from means for connection to conduits for supplying and discharging said first fluid, and means for organizing the circulation of a second heat exchange fluid in said circu3ation conduits from means for connection to supply and evacuation conduits of said second fluid;

- Said means for circulating the first fluid advantageously comprise a first hollow cylinder delimiting, in a median section, the internal wall of said annular chamber and two end sections of which connect said median section with said connection means for the first fluid , said means for connection to the discharge conduit being at an opposite end of the cylinder from one end of the latter in connection with said means for connection to the supply conduit, said end sections preferably having a conical shape whose the section decreases as it is close to said connection means;

- Said median section is divided by a solid disc preferably curved and has in its wall, on either side of the separation provided by said disc, a series of openings in radiating arrangement opening into said annular chamber between said conduits circulation so as to connect the two end sections via said annular chamber;

- Said walls comprise at each of their ends means for guiding the first fluid from an opening of said series towards said annular chamber, each wall comprising two end sectors whose profile constitutes said guide means; the profile of said end sectors is free of undulations and has a series of pins capable of cooperating with pins of an adjacent wall so as to avoid deformation of the walls; said end sectors have corrugations oriented so as to connect an opening with the longitudinal corrugations of the wall; and said means of circulation of the second fluid advantageously comprise a second hollow cylinder, closed at its ends, delimiting, in a median section, the external wall of 3 said annu ary chamber and of which two end sections put in 3iaison 3.es ses connection means for 3rd second fluid by 3 intermediary of the circulation conduits, and of the two annular discs, said means of connection to the evacuation conduit being preferably formed in the side wall of one of the end sections and said means of connection to the intake conduit being of preferably arranged in the side wall of the other end section.

The volume of the exchanger which is not occupied by the exchange surface, that is to say the annular chamber and the circulation conduits, is used for the distribution of the fluids.

The second fluid is preferably the low pressure fluid and it has the best circulation plan in the exchanger with direct inputs-outputs in the conduits from the connection means, by means of the end sections which are themselves large volume.

The first fluid, which is preferably the high pressure fluid, must circulate between the conduits in the annular chamber by virtue of the solid disc dividing the median section of the first hollow cylinder.

In order to absorb the thermal expansions in the exchanger, at least one of said end sections of the first cylinder is advantageously linked to said connection means for the first fluid, by means of a metal expansion bellows, and said sections of end of the second cylinder are each closed by means of an annular dome whose central orifice surrounds said connection means for the first fluid.

In the case of a vertical arrangement of the exchanger, it is suspended from a support by one or more attachment points or carried by brackets or skirts. In this case, an expansion bellows is

REPLACEMENT SHEET preferably arranged at 3 'lower end of 3' exchanger, 3rd upper end section of the first cylinder then being directly welded to the connection means for the first fluid with which it cooperates.

In order to ensure sealing and to compensate for thermal expansions between the means for circulating the second fluid and said annular chamber, an annular metal membrane, of internal diameter somewhat less than the internal diameter of said external cylinder is advantageously welded, of a part on the face of each annular disc opposite to the annular chamber and on the other hand on the internal wall of said external cylinder opposite said disc.

According to one embodiment of the invention, intended for an application of exchangers for preheating the charge of catalytic reforming units, the exchanger according to the invention advantageously comprises an annular ring for injecting a constituent in the first fluid, said crown being parallel to the section of said annular chamber and having perforations directed towards one of the open ends of the median section of said internal cylinder.

The exchanger according to the invention thus comprises two separate supply means for two constituents of the first fluid, one of the constituents preferably being in the vapor phase and serves as a propellant for the second constituent preferably in the liquid phase, so as to produce mixing the two constituents of the first fluid inside the exchanger and allowing a homogeneous circulation of the first heat exchange fluid in said annular chamber between the conduits. The means for supplying the first component are arranged so as to introduce the latter into the exchanger at the level of said crown, the second component being injected by said crown.

The injection of the liquid charge into a recycling gas is thus carried out via the

REPLACEMENT SHEET annular ring close to the heat exchange surfaces, and no longer outside the exchanger or on the connection means, which makes it possible to obtain a good entrainment of the liquid phase and a good distribution of the liquid charge in all the intervals between the ducts of the annular chamber.

According to a particularly advantageous alternative embodiment of a 3 ′ exchanger according to the invention:

- Said means for circulating the first fluid comprise a ferrule delimiting in a median section, the external wall of said annular chamber, a second hollow cylinder of diameter greater than said ferrule, coaxial with the latter and delimiting in an median section an annular space dispensing the first fluid, two end sections of said second cylinder connecting said middle section with said connection means for the first fluid; and said space is divided by an annular membrane, said ferrule comprising in its wall, on either side of the separation formed by said membrane and preferably near each end of the median section, a series of openings in radiating arrangement opening into said annular chamber between said conduits so as to connect the two connection means via the annular chamber; and said means for circulating the second fluid comprise a first hollow cylinder delimiting in a median section, the internal wall of said annular chamber, and at least one end section of which connects said means of connection to the supply conduit for the second fluid with the circulation conduits via a series of openings opening into a space delimited by an end section of said ferrule, a second end section of said ferrule connecting said conduits with said means connecting to the exhaust duct and said first cylinder being closed at both ends of its median section.

H-EŒL.LEDEREMPLACEMENT We will now describe in detail a particular embodiment of the invention which will make it better understand its essential characteristics and the advantages, it being understood however that this embodiment is chosen by way of example and that it is in no way limiting. Its description is illustrated by the appended drawings, in which:

- Figure 1 shows in longitu¬ dinal perspective a conduit for circulation of an exchange fluid according to the invention; 2 shows in partially exploded view the means of assembling the conduits according to the invention;

- Figure 3 shows an elevational view in partial section of an exchanger according to the invention.

- Figure 4 shows in section, along line A-A 'of Figure 3, a variant for a particular application in the field of petrochemicals where the exchanger is associated with a catalytic reformer;

- Figure 5 shows an elevational view in partial section of a variant of an exchanger according to the invention.

The conduit 1 shown in Figure 1 is made up of a metal plate formed by explosion which is folded back on itself in its longitudinal direction so as to provide a conduit of elongated section. The plate has on its periphery a frame with a smooth surface consisting of two longitudinal edges 2 and 3 and two transverse edges 4 and 5. The two longitudinal edges 2 and 3 come to bear one on the other during the folding of the plate and they are then joined by welding 6 over the entire length of the plate.

In a preferred embodiment, an intermediate tab is inserted during folding between the two longitudinal edges 2 and 3, thereby facilitating welding.

REPLACEMENT SHEET The plate also has a longitudinal median zone with a smooth surface 7 intended to allow p iage of the plate.

The plate shown in Figure 1 is a sheet whose deformations were obtained by explosion forming. To manufacture such a plate, a plastic counter-mold is produced from a matrix and then a sheet is pressed on this counter-mold which is deformed by the counter-mold during the explosion. The deformations that the plate undergoes are such that it has longitudinal undulations 8 on the two surfaces included between the middle zone with smooth surface 7 and the two longitudinal edges 2 and 3 limited by the transverse edges 4 and 5. These two symmetrical surfaces are intended to form two walls of a conduit 1.

On each of the walls 9 and 10, the amplitude of the corrugations 8 increases from the longitudinal edge 2 or 3 limiting the wall respectively 9 or 10, to the middle zone with smooth surface 7. The pitch between the corrugations is kept identical.

When the plate is folded as shown in Figure 1, each corrugation of the wall 9 carries, by its crest, on a corrugation of the wall 10. The regular increase in the amplitude of the corrugations allows to obtain a conduit 1 whose the section is increasing from the longitudinal edges 2 and 3 to the middle zone 7.

The longitudinal corrugations 8 are inclined alternately in one direction or another with respect to the longitudinal edges 2 and 3 _" and in order to compensate for the variation in section of the duct due to the amplitude of the corrugations, the angle d 'inclination is lower for the corrugations of the plate close to the longitudinal edges 2 and 3 than for the corrugations close to the middle zone with smooth surface 7. For manufacturing reasons, these are divided into three sectors or

REPLACEMENT SHEET zones, respectively 11, 12 and 13, on each surface 9 and 10. The angles of inclination of the undulations of sector 11 being identical, but less than the angles of inclination of the undulations of sector 12 which are all 5 identical, and respectively less than the angles of inclination of the undulations of the sector 13.

It is quite obvious that according to another method of manufacturing the plates, the increase in the angle of inclination of the corrugations can be progressive as the corrugation approaches the center of the plate, and that the difference in friction resulting from the variation of the hydraulic diameter in the duct produced can be compensated by a variation of the pitch of the undulations associated or not with the variation of the angle of inclination.

The plate has at each of its transverse edges 4.5 a smooth sector 35 constituting means for guiding the fluids, as will be seen below.

The conduits 1 thus produced are assembled in a radiating arrangement by means of two annular discs 14 and 15 as shown in FIG. 2. The longitudinal edges 2 and 3 of the plates constitute the proximal edges of the walls of the conduits, and the middle zone 7 , the distal edges of the same walls.

- Each of the two discs 14 and 15 has a series of openings 16 in radiating arrangement, each of these openings being intended to receive a radial end of a duct 1. The two transverse edges 4 and 5 of a duct 1 constituting its ends are engaged 0 each in an opening 16 of one of the disks 14 and 15 respectively, then welded around the periphery of this opening.

The discs 14 and 15 are thin because they have no pressure force to take up as will be seen below.

Once this assembly has been carried out, a

REPLACEMENT SHEET conduit bundle of radially elongated section in radiating arrangement.

The spacing between two adjacent openings which delimits the spacing between two neighboring conduits is dimensioned so that the undulations of a conduit bear by their crests on the crests of the undulations of the two conduits which are adjacent to it.

An exchanger according to the invention is shown in FIG. 3, it comprises two cylindrical ferrules 17 and 18, a first hollow cylinder or internal cylinder 17 delimiting in a median section the internal wall of an annular chamber 19 whose external wall is delimited by the median section of a second hollow cylinder or external cylinder 18 coaxial with the cylinder 17. A bundle of conduits 1 in radiating arrangement between two discs 14 and 15 is inserted in the annular chamber 19 and thus defines the volume of heat exchange between two fluids, a first high pressure fluid circulating in the annular chamber between the conduits, and a second low pressure fluid circulating in the conduits 1.

The first cylinder 17 or internal cylinder is connected to one of its ends by means of a metal thermal expansion bellows 20, respective¬ ment to connection means 21 of a conduit for discharging the first exchange fluid thermal; means of connection 22 to a conduit for supplying the first fluid being connected by welding to another end of the internal cylinder 17.

The median section of the cylinder 17 has in its wall, at each of its ends, a series of openings 23, 24 in radiating arrangement which open into the annular chamber 19 between the conduits 1 in order to link the internal volume of the cylinder 17 with the annular chamber 19. The median section of the cylinder 17 is divided by a rounded domed disc 25 making it possible to force the first fluid to pass longitudinally through the chamber

REPLACEMENT SHEET annular 19. The disc 25 may possibly be planar, but its domed shape makes it possible to take up the pressure forces with a reduced thickness of the sheet constituting it.

The smooth sectors 35 of the plates constituting the conduits make it possible to guide the first fluid from the openings 23, 24 towards the longitudinal undulations 8 of the plates or vice versa. These smooth sectors 35 can be replaced by corrugated sectors whose orientation of the corrugations is such that the latter connect the openings 23, 24 and the longitudinal corrugations occupying the intervals between the conduits 1.

One can also provide in the case of sectors 35 free of ripple that these include pins capable of maintaining the spacing between the conduits and the spacing of the walls of the same conduit.

The second cylinder 18 or external cylinder is closed at each of its ends by an annular ring, respectively 26 and 27, the central opening of which is used for the passage of the connection means, respectively 21 and 22 of the first fluid.

The two cylinders 17 and 18 define, in their parts close to each of their ends, two annular end chambers 28 and 29 which make it possible to connect the interior of the conduits 1 with connection means, respectively 30 and 31, of the evacuation supply ducts for the second heat exchange fluid. These connection means are formed in the wall of the cylinder 18 and each open out respectively into one of the annular end chambers 28 or 29.

The end sections of the internal cylinder 17, delimiting the internal walls of the annular end chambers 28 and 29, have a conical shape due to the different diameter presented by the connection means 21 and 22 relative to the internal diameter of the middle section. of cylinder 17. During the operation of the 3 'exchanger, 3es two fluids circulate against the current 3' from one another. A first heat exchange fluid, preferably high pressure, for example enters the exchanger via the connection means 22, and is guided towards the annular chamber 19 by means of the series of openings 24 of the cylinder 17 This fluid emerges from this annular chamber through the series of openings 23 of the cylinder 17 and is evacuated via 3 'via the connection means 21. An opposite direction of circulation can just as easily be provided.

A second heat exchange fluid preferably low pressure is, for its part, supplied via the connection means 30, opposite the connection means 22, and enters the conduits 1 which open into the annular chamber end 28 into which the second fluid is introduced, to exit into the annular end chamber 29 and be evacuated via the connection means 31.

The low pressure fluid is the one which follows the most direct path in the exchanger so as to limit the pressure losses due to the circulation of the fluids compared to the exchange charge losses proper and thus increase the thermal efficiency of the 'exchanger.

The shape which is given to the conduits 1 allows them to take up the pressure forces with a minimum sheet thickness and the fact that the high pressure fluid circulates outside, it is not necessary that the outer wall of the median zones to smooth surface 7 constituting the distal edges of the walls of the conduits is in contact with the internal wall of the cylinder 18 delimiting the external wall of the annular chamber 19 of heat exchanges. The discs 14 and 15 can be of relatively small thickness insofar as they have little pressure force to take up due to a relatively small pressure difference between the faces of each

REPLACEMENT FEUTLLE disc and the small section of conduits.

It is also possible to provide a ferrule made of thin sheet metal which has an internal diameter somewhat greater than the diameter of the radiating arrangement of the conduits 1 and which is welded by one of its ends, preferably corresponding to the exit from the exchange zone of the first fluid, on the disc 14. This ferrule 37 being of a length less than the distance separating the two discs 14 and 15 so that the pressure of the first fluid, which is stronger when it enters the exchange zone than at its outlet, either applied via the ferrule to the distal edge of the conduits 1, thus limiting the leakage current between these distal edges and the external cylinder 18.

An annular metal membrane, with a diameter somewhat smaller than the diameter of the median section of the external cylinder 18, can be welded, on the one hand to one face of an annular disc 14 or 15, and on the other hand to the internal wall of the cylinder 18 of. so as to seal between the annular chamber 19 and the annular end chambers 28, 29. Each membrane is preferably placed on the face of each disc where the pressure is the lowest.

In the case of an application for an exchanger associated with a catalytic reformer, it is particularly advantageous to be able to ensure good distribution of the liquid phase of the first heat exchange fluid in the annular chamber 19 between the conduits. To this end, an annular ring 32 (Figure 4) is placed in the end section of the first cylinder 17 used for the supply of the first fluid. This ring, coaxial with the two cylinders 17 and 18, has on its face opposite the median section of the first cylinder 17, a series of perforations 33 connected via conduit 34 to the supply conduit for the first fluid by the connection means 21.

The recycling gas used in this type of application

REPLACEMENT SHEET cation is brought into the end section 36 of the internal cylinder directly by means of the connection means 21, and the liquid charge 3 is brought by means of the conduits 3 to the annular ring 3 and is injected into the recycling gas by means of the perforations 33 in the direction of the open end of the middle section of the cylinder 17. This gives a better distribution of the liquid charge in all the conduits and a good entrainment of the liquid phase of the first exchange fluid thermal.

The exchanger shown in FIG. 5 corresponds to an alternative embodiment of the invention in which the circulation of fluids from the supply means, respec¬ tively to the discharge means, to the exchange surfaces, respectively from the exchange surfaces, differs from the examples previously described.

A first heat exchange fluid, preferably high pressure, is brought into the annular chamber 19 via connection means 39 and a first series of openings 40 formed in a ferrule 41 externally delimiting the chamber 19. The first fluid leaves the exchanger via connection means 42 after having passed through a second series of openings 43 formed in the shell 41 at the opposite end of the first series 40.

A second heat exchange fluid, preferably low pressure, enters the exchanger via connection means 37 and is guided towards the inside of the conduits 1, to exit via connection means 38.

The annular chamber 19 is delimited internally by the median section of a first cylinder or internal cylinder 44 and externally by the median section of the ferrule 41. The exchanger is delimited externally by a second cylinder or external cylinder 45.

REPLACEMENT SHEET The space between the ferrule 41 and the third external cylinder 45 contributes to organizing the circulation of the first fluid, the series of openings 40 and 43 opening into this annular space on either side of an annular metallic membrane 46. The membrane 46 is intended to avoid mixing of the fluid entering the chamber 19 with the outgoing fluid.

Two annular discs 14 and 15 contribute to the organization of the circulation of fluids as in the previous examples.

The middle section of the internal cylinder 44 is closed at its two ends by solid disks 47, preferably domed, and at least one end section 48 of this cylinder connects the connection means 37 to the middle section. This end section 48 has a series of openings 49 which, by cooperating with a conical end section 50 of the ferrule 41, guide the fluid towards the interior of the conduits 1. Struts 51 pressing in one on the disk 15 and on the other hand either on the section 50 or on the section 48, provide sufficient rigidity to the assembly.

In the case of an application for an exchanger associated with a catalytic reformer, the gas charge is brought by the connection means 39 while the liquid charge is brought into 3a annular chamber 19 to be mixed there with the gas charge by the intermediate a conduit 52 coaxial with the cylinders and passing through the connection means 38 by means of evacuation of the second fluid. This duct 52 is closed at its upper end and has on its periphery a series of openings 53 suitable for cooperating with a series of openings 54 formed in the internal cylinder 44 for injecting the liquid charge into the chamber 19.

The conduit 52 can be linked to the cylinder 44 by lugs 55.

Two expansion bellows 56 and 57 connect

REPLACEMENT SHEET respectively the connection means 38 and 58 to 3a viro3e 41 and to the conduit 52.

Naturally, the invention is in no way limited by the third features which have been specified in the foregoing or by the details of the particular embodiment chosen to illustrate the invention. All kinds of variations can be made to the particular embodiment which has been described by way of example and to its constituent elements without thereby departing from the scope of the invention. The latter thus includes all the means constituting technical equivalents of the means described as well as their combinations.

REPLACEMENT SHEET

Claims

1. Heat exchanger, characterized in that it comprises an annular chamber (19) for circulation of a first heat exchange fluid, in which are distributed longitudinal conduits (1) for circulation of a second exchange fluid thermal, preferably against the current of the first, and in that said conduits (1) are limited by radial walls (9,10) in radiating arrangement in said chamber (19) and in cooperating relationship with one another like those of a plate exchanger, said walls (9,10) being constituted by corrugated plates closing conduits (1) of elongated section and flared radially.

2. Heat exchanger according to claim 1, characterized in that said walls have longitudinal undulations (8), forming ridges among which the ridges of the undulations of a first wall (9) of a duct are supported on ridges undulations of a second wall (10) of said conduit (1).

3. Heat exchanger according to claim 1 or

2, characterized in that the amplitude of the undulations (8) of the walls increases progressively from the edge (2,3) of the wall proximal to the axis of the radiating arrangement to the edge (7) of the distal wall of said axis, so as to provide conduits (1) of elongated section increasing from one end of the conduit, proximal of said axis, to one end of the same conduit, distal of said axis.

4. Heat exchanger according to any one of claims 1 to 3, characterized in that said longitudinal corrugations (8) of said walls ε nt with inclination alternately in one direction or another with respect to said proximal edges, and in that l the angle of inclination is smaller for the undulations (8) of the wall (9,10) close to its edge (2,3) proximal to

REPLACEMENT SHEET the axis, that for the corrugations (8) close to its edge (7) distal from the axis, the increase in the angle being able to be progressive as the corrugation approaches said distal edge, or be carried out by zones, the undulations of a wall preferably being divided into three zones (11,12,13), the angles of inclination of the undulations of the same zone being identical, and those of the undulations of a following zone , progressing towards said distal edge, being superior.

5. Heat exchanger according to any one of claims 1 to 3, characterized in that said longitudinal undulations (8) of said walls are inclined alternately in one direction or another with respect to said proximal edges, and in that the pitch corrugations of the same wall increases as the corrugations are close to said distal edge of the duct, the angle of inclination of the corrugations being identical for all the corrugations of the same wall.

6. Heat exchanger according to any one of claims 1 to 5, characterized in that said annular chamber (19) is closed at each of its ends by an annular disc (14,15) further constituting means for assembling the conduits (1), each disc having in its section a series of openings (16) in radiating arrangement, each opening (16) being intended to receive one end of a conduit (1), each end section of a conduit being in sealing sealed abutment against an opening (16) of said disc (14,15).

7. Heat exchanger according to any one of claims 1 to 6, characterized in that it comprises means for organizing the circulation of a first thermal fluid in said annular chamber (19) from means for connection to conduits of '' (22; 39) and discharge (21; 42) of said first fluid, and means for organizing the circulation of a second heat exchange fluid in said circulation conduits (1) from

REPLACEMENT SHEET means for connection to supply (30; 37) and evacuation (31; 38) cudit second fluid conduits.

8. Heat exchanger according to claim 7, characterized in that said means for circulating the first fluid comprise a first hollow cylinder (17) delimiting, in a median section, the internal wall of said annular chamber (19) and two sections of which d end connect said middle section with said connection means for the first fluid (21,22), said connection means to the eva¬ cuation conduit (21) being at an opposite end of the cylinder from one end of that -this in connection with said connection means to the supply conduit (22), said end sections preferably having a conical shape whose section decreases as it is located near said connection means (21 , 22); and in that said median section is divided by a solid disc (25) preferably curved and comprises in its wall, on either side of the separation formed by said disc (25), a series of openings (23, 24) in a radiating arrangement opening in said annular chamber (19) between said circulation conduits (1) so as to connect the two end sections via said annular chamber (19).

9. Heat exchanger according to claim 7, characterized in that said means for circulating the first fluid comprise a ferrule (41) delimiting in a median section, the external wall of said annular chamber, a second hollow cylinder (45) of greater diameter to said ferrule, coaxial with the latter and delimiting in an median section an annular space for distribution of the first fluid, two sections of ends of said second cylinder (45) connecting said median section with said connecting means for the first fluid (39,42) and in that said space is divided by an annular membrane (46), said ferrule (41) having in its wall, on either side of the separation provided by

REPLACEMENT SHEET 3 said membrane and preferably near each end of the middle section, a series of openings (40,43) in radiating arrangement opening into 3 said annular chamber (19) between said conduits (1) so as to connect the two means connection through the annular chamber.

10. Heat exchanger according to claim 8 or 9, characterized in that said walls comprise at each of their ends means for guiding the first fluid from an opening (23,24; 40,43) of said series towards said annular chamber ( 19), each wall having two end sectors (35) whose profile constitutes said guide means.

11. Heat exchanger according to claim 10, characterized in that the profile of said end sectors (35) is free of undulations and has a series of pins capable of cooperating with pins of an adjacent wall so as to avoid deformation of the walls.

12. Heat exchanger according to claim 10, characterized in that said end sectors (35) have corrugations oriented so as to connect an opening (23,24; 40,43) with the longitudinal corrugations of the wall.

13. Heat exchanger according to any one of claims 7, 8, 10 to 12, characterized in that said means for circulating the second fluid comprise a second hollow cylinder (18), closed at its ends, delimiting, in a median section , the outer wall of said annular chamber (19) and two end sections of which connect said connection means (30, 31) for the second fluid via the circulation conduits (1), and two annular discs (14,15), said means for connection to the discharge duct (31) preferably being formed in the side wall of one of the end sections and said means for connection to the supply duct (30) preferably being housed in the

REPLACEMENT SHEET 3atera3e wall of 3 'other end section.

14. Heat exchanger according to claim 13, characterized in that at least one of said end sections of the first cylinder (17) is linked to said

5 connection means (21, 22) for the first fluid, by means of a metal expansion bellows (20), and in that said end sections of the second cylinder (18) are each closed by means of a annular dome (26,27) including the central opening. surrounds said connecting means (21,22) for the first fluid.

15. Heat exchanger according to any one of claims 7, 8, 10 to 14, characterized in that it comprises a ferrule of length less than the distance separating said annular discs (14,15), welded by a

15 from its ends to one of the discs (14), said shell once carrying the heat exchanger under pressure on the distal edges of the conduits (1).

16. Heat exchanger according to any one of claims 7, 8, 10 to 15, characterized in that it

20 comprises means for sealing between the means for circulating the second fluid and said annular chamber (19), said means preferably being constituted by at least one annular metal membrane with an internal diameter somewhat less than the diameter

25 internal of said second cylinder (18) suitable for being welded on the one hand to one face of an annular disc (14,15) and on the other hand to the internal wall of said second cylinder (18) facing said disc (14 , 15) and preferably on the edge of said shell.

- * 17. The heat exchanger according to any one of claims 7, 9 to 12, characterized in that said means for circulating the second fluid comprise a first hollow cylinder (44) delimiting in a median section, the internal wall of said annular chamber (19)

35 and at least one end section (48) of which connects said connection means: sment to the supply duct (37) for a third second f3uide with the circu3ation conduits (1) via a series of openings (49) opening into a space delimited by an end section (50) of said ferrule (41), a second section end of said ferrule (41) connecting said conduits (1) with said connection means to the discharge conduit (38) and said first cylinder being closed at both ends of its median section.

18. Heat exchanger according to any one of claims 1 to 17, characterized in that it comprises means for injecting a constituent into the first fluid and in that said means preferably consist of an annular ring (32) parallel to the section of said annular chamber or of a conduit (52) coaxial with said first cylinder (44), said crown (32) or said conduit (52) having perforations (33; 53) suitable for cooperating with openings (23; 54) formed in the median section of said internal cylinder (17; 44).

19. Metal plate constituting a circulation duct of an exchanger according to any one of claims 1 to 18, characterized in that it is folded back on itself to form two facing walls limiting the same duct and welded at the end to close this duct, preferably along the proximal generatrix of the duct, said plate preferably being obtained by explosion forming.

20. Plate according to claim 19, characterized in that it has on its periphery a frame with a smooth surface, two longitudinal edges of which are intended to come into sealing abutment one on the other or preferably by means of an intermediate tab when the plate is folded and in a central part, a longitudinal area with a smooth surface, intended to allow the folding of the plate.

REPLACEMENT SHEET