CA2779323A1 - Heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger, in particular for a synthesis gas installation, for the heat exchange between a first and a second medium (W, G), comprising a shell (10), which is made to extend along a longitudinal axis (L) and bounds a shell space (M) for receiving the first medium (W), a tube space (R), which is surrounded by the shell space (M), for receiving the second medium (W), and a pass baffle (20), which is arranged in the shell space (M) and made to extend along the longitudinal axis (L), for directing the first medium (W), carried in the shell space (M), along the longitudinal axis (L). According to the invention, it is provided that the pass baffle (20) is welded to the shell (10).

Description

HEAT EXCHANGER
Summary of the Invention The invention relates to a heat exchanger, in particular for a synthesis gas installation, for the (indirect) heat exchange between a first and a second flowing medium, in particular in the form of feed water and synthesis gas. In particular, the invention relates to a heat exchanger comprising: a shell which extends along a longitudinal axis and bounds a shell space for receiving the first medium, a tube space, surrounded by the shell space, for receiving the second medium, and a pass baffle, which is arranged in the shell space and extends along the longitudinal axis, for directing the first medium, carried in the shell space, along the longitudinal axis.
Such a heat exchanger has at least one pressure-bearing shell, which is made to extend along a longitudinal axis and bounds a shell space for receiving the first medium, and also has a tube space, which is surrounded by the shell space and in which the second medium is conducted, so that the second medium, carried in the tube space, can enter into indirect heat exchange with the first medium, on the shell side. To allow the first medium to be conducted through the shell space (and back) along the longitudinal axis, a longitudinal directing panel is provided, made to extend in the manner of a sheet along the longitudinal axis and generally produced from a metal (pass baffle).
In other words, the pass baffle divides the shell space into two portions, a first portion and a second portion, that run parallel to one another along the longitudinal axis, in order to extend the flow path of the first medium in the shell space and thereby intensify the heat exchange. Such a heat exchanger is known, for example, from US 4,778,005.
It is of great importance here that, when the heat exchanger is operating in the way intended, as far as possible there are no bypassing flows that reduce the effectiveness of the heat exchange. In the case of the known heat exchanger, there is particularly the problem that, when there is a failure of the sealing of the pass baffles with respect to the surrounding shell, such bypassing flows of the first medium can occur, leading to a significantly lower heat exchange of the first medium in the shell space, which correspondingly reduces the effectiveness of the heat exchange.
Such a heat exchanger is therefore not suitable in particular for applications at high pressures (for example in synthesis gas installations).
Against this background, one aspect of the present invention is to provide a heat exchanger that is improved with respect to the aforementioned problem.

Upon further study of the specification and appended claims, other aspects and advantages of the invention will become apparent.
These aspects are achieved by a heat exchanger wherein the pass baffle is welded to the shell.
In accordance with the invention, the pass baffle of the heat exchanger is welded directly to the shell (i.e. is connected directly to the shell by means of a welded connection which may comprise a number of weld seams). This welded connection is impermeable in particular to the first medium, so that the first medium cannot pass from the first portion of the heat exchanger into the second portion of the heat exchanger by way of that welded connection. This solution according to the invention consequently makes it possible in principle to reduce the risk of so-called bypassing flows, and therefore have much better control over the process.
The shell preferably has a first shell part, which is made to extend along the longitudinal axis, and a second shell part, which is made to extend along the longitudinal axis and lies opposite the first shell part transversely in relation to the longitudinal axis.
The two shell parts are connected (welded) to one another by way of the pass baffle.
The shell parts are preferably parts in the form of half shells, in particular in the form of halves of a cylindrical shell (of a straight hollow-circular cylinder).
The pass baffle is preferably formed such that it is made to extend longitudinally along the longitudinal axis and thereby preferably has a sheet-like rectangular form, with two peripheral regions lying opposite one another transversely in relation to the longitudinal axis and running along the longitudinal axis. These two peripheral regions, respectively, have a first side, which faces the first shell part, and a second side, which is remote from the first side and faces the second shell part.
The two shell parts preferably respectively have a first end face, which is made to extend along the longitudinal axis. The first shell part is preferably connected by its first end face, made to extend along the longitudinal axis, to the first side of the first peripheral region by way of a first weld seam. The second shell part is preferably connected by its first end face, made to extend along the longitudinal axis, to the second side of the first peripheral region of the pass baffle by way of a second weld seam. In the same way, the second end faces of the two shell parts may also be respectively connected to the second peripheral region of the pass baffle.
The weld seams preferably completely fill intermediate spaces between the end faces of the shell parts and the respective peripheral regions of the pass baffle. That is, in a cross-sectional plane running perpendicularly in relation to the longitudinal axis of the shell, the weld seams connected to the peripheral region of the pass baffle are respectively formed continuously (in one piece), so that the weld seams respectively have an outer side and an inner side. The outer side faces an outer space surrounding the shell, is adjacent thereto and goes over into an outer side of the respectively assigned shell part of the shell. The inner side faces the shell space, is adjacent thereto and goes over into an inner side of the respectively assigned shell part of the shell that faces the shell space and goes over into the respectively adjacent side of the pass baffle.
In this case, in a cross-sectional plane running perpendicularly in relation to the longitudinal axis of the shell, the weld seams in question may initially narrow towards the shell space and widen again, in particular in a step-shaped manner, in the region of an inner side, facing the shell space, of the respectively assigned shell part, so that the weld seams concerned respectively reach around a periphery of the respectively assigned end face of a shell part.
Furthermore, the thickness of the pass baffle may be narrowed towards an outer periphery, i.e. in particular at the two peripheral regions, that is to say between end faces opposite from one another of the shell parts, or as an alternative to this the pass baffle may have a constant thickness in the region of the peripheral regions.
For stiffening the shell, in particular for strengthening the connection between the shell parts of the shell, the heat exchanger has at least one stiffening ring, which runs around on the shell transversely in relation to the longitudinal axis and, in particular, is welded to the shell. It is preferably provided that the at least one stiffening ring reaches around the shell or, as an alternative to this, that the shell reaches around the stiffening ring, i.e. runs around on an inner side, facing the shell space, of the shell or of the two shell parts.
The pass baffle thus divides the shell space into a first portion, which is made to extend along the longitudinal axis, and a second portion, which is made to extend parallel thereto and lies opposite to the first shell portion. These two portions are connected to one another in a flow-directing manner preferably in the region of a first end portion of the shell space. The two portions of the shell space preferably also respectively surround an assigned part of the tube space (for example the tubes of a tube bundle respectively running in the portion concerned), so that the first medium, carried in the two portions, can enter into indirect heat exchange with the second medium, carried in the respectively assigned part of the tube space.

For introducing the first medium into the first portion of the shell space, an inlet, for example in the form of a connection piece, is preferably provided on the shell, at a second end portion of the shell space that lies opposite from the first end portion of the shell space along the longitudinal axis. Furthermore, provided opposite from that on the shell, at the second end portion of the shell space, is an outlet, by way of which the first medium can be withdrawn from the second portion of the shell space. The first medium, introduced into the first portion, can consequently flow along a first direction to the first end portion of the shell space and then flow along an opposite second direction in the second portion (back) to the outlet for withdrawing the first medium.
In order to be able to deflect the flow of the first medium perpendicularly in relation to the longitudinal axis, so that for example a cross-counterflow is possible with respect to the second medium that is conducted in the tube space, there are preferably provided a number of sheet-like cross baffles, which are arranged in the two portions of the shell space and correspondingly extend respectively perpendicularly away from the pass baffle, and are thereby preferably oriented perpendicularly in relation to the longitudinal axis. Neighboring cross baffles are preferably respectively arranged offset in relation to one another, so that the first medium flows through the two portions of the shell space in a meandering manner. The cross baffles are preferably fixed to the pass baffle, to be precise in particular by welding. In principle, the cross baffles may be variably distributed or arranged in the shell space (depending on the application).
The tube space preferably has a tube bundle, arranged in the shell space, or is formed by such a tube bundle, the tube bundle having at least a first tube, running along the longitudinal axis, and at least a second tube, running along the longitudinal axis, which tubes are connected to one another (in one piece) by way of a U-shaped tube portion in the region of the first end portion of the shell space. The two tubes are anchored at a respective free end, lying opposite from the U-shaped tube portion, in a tube sheet of the tube bundle that is made to extend perpendicularly in relation to the longitudinal axis, and particularly bounds the shell space and separates it from a head of the heat exchanger. The tube bundle preferably has a plurality of such pairs of first and second tubes connected by way of a plurality U-shaped tube portions.
The head of the heat exchanger is preferably divided into an inlet chamber and an outlet chamber, it being possible for the second medium to be introduced into the tube space or the tube bundle by way of the inlet chamber and by way of the tube sheet, and it being possible for the second medium to be drawn off from the tube space and out of the heat exchanger by way of the outlet chamber. An inlet, particularly provided on the shell, is connected to the inlet chamber in a flow-directing manner and is intended for introducing the second medium into the inlet chamber. In addition, an outlet, particularly provided on the shell, is connected to the outlet chamber in a flow-directing manner and is intended for withdrawing the second medium from the outlet chamber.

Brief Description of the Drawings Further details and advantages of the invention are to be explained with the following description of the Figures of exemplary embodiments on the basis of the figures, in which:

Figure 1 shows a schematic sectional view of a heat exchanger according to the invention;

Figure 2 shows a section through the shell space of the heat exchanger according to Figure 1 along the line II-II of Figure 1;

Figure 3 shows a partly sectioned view of the heat exchanger shown in Figures and 2 along the line III-III of Figure 1;
Figure 4 shows a sectional view in the manner of a detail of the heat exchanger shown in Figures 1 to 3;

Figure 5 shows a detail of Figure 3 or 4;
Figure 6 shows a detail of Figure 3 or 4 in an alternative embodiment;

Figure 7 shows a sectional view of a heat exchanger according to the invention, fitted with a stiffening ring, along the line VII-VII of Figure 1; and Figure 8 shows a sectional view of a modification of the heat exchanger shown in Figure 7 along the line Vill-Vill of Figure 1.

Figure 1 shows in conjunction with Figures 2 to 8 a heat exchanger 1, with a pressure-bearing shell 10, which is made to extend along a longitudinal axis L, which runs horizontally - with respect to a state of the heat exchanger 1 arranged as shown.
The shell 10 is preferably given the form of a hollow circular cylinder (possibly apart from at the free ends of the heat exchanger 1), so that the longitudinal axis L is in particular correspondingly a cylinder axis.
The shell 10 defines a shell space M for receiving a first medium W, which is particularly water. The shell space M thereby encloses a tube space R of the heat exchanger 1, which is designed for receiving a second medium G, which is particularly a synthesis gas, so that that second medium G can enter into indirect heat exchange with the first medium W, carried in the shell space M.
The tube space R is in this case formed by a tube bundle, which has a plurality of first and second tubes 61, 62, which are respectively connected to one another by way of a U-shaped tube portion 63 and are respectively anchored by free ends 611 and 621 in a tube sheet 6 of the tube bundle R. In the case of a hollow circular-cylindrical shell 10, the tube sheet 6 is correspondingly given the form of a circular sheet (disc-shaped).
The tube sheet 6 bounds the shell space M and separates from it a head K of the heat exchanger 1, which is divided into an inlet chamber 301 and an outlet chamber 302 by means of a wall 312 made to extend along the longitudinal axis L. The head K
of the heat exchanger 1 is also bounded by a sheet 70, which can be fastened to the shell 10, for example by way of a flange, and lies opposite the tube sheet 6 along the longitudinal axis L.
The shell 10 of the heat exchanger 1 is mounted on an underlying surface by way of connection pieces 50, it being possible for one of the connection pieces 50 to form a sliding bearing for the shell 10 to compensate for thermally induced stresses.
For directing the first medium W along the longitudinal axis, the shell space M is divided along that longitudinal axis L by a sheet-like rectangular pass baffle 20 into a first portion 201 and a parallel second portion 202, that communicates with the first portion 201. The two portions 201, 202 are connected to one another in the region of a first end portion 2 of the shell space M that lies opposite from the tube sheet 6 along the longitudinal axis L. The pass baffle 20 also divides the shell 10 into a first and a second shell part 101, 102, which are made to extend along the longitudinal axis L
and respectively have the form of a half shell. In particular, the two shell parts 101, 102 are formed mirror-symmetrically in relation to one another, that is to say, for example, each forming half of a cylindrical shell.

The pass baffle 20 thereby also divides the tube bundle R into a first part and a second part. The first portion 201 of the shell space M surrounds the first part of the tube space or the tube bundle R, and the second portion 202 of the shell space M
surrounds the second part of the tube space or the tube bundle R. The free ends 611, 621 of the first and second tubes of the tube bundle R are accommodated here in the tube sheet 6 in such a way that the second medium G can be admitted to the tube bundle R by way of the tube sheet 6. For this purpose, the second medium G can be fed by way of an inlet 310, which is provided on the head K and opens out into the inlet chamber 301 (hot side of the heat exchanger 1), into the inlet chamber 301 and from there into the first tubes 61 of the tube bundle R (for example at about 300 C
in the case of a synthesis gas G). The second medium G then flows along the longitudinal axis L of the heat exchanger 1 towards the first end portion 2 of the shell space M, where the first tubes 61 go over by way of the respectively assigned U-shaped tube portions 63 into the second tubes 62 of the tube bundle R. The second medium G is then returned through the second tubes 62 to the tube sheet 6 and enters the outlet chamber 302, from which the second medium G can be withdrawn from the heat exchanger 1 by way of an outlet 311 (hot side, synthesis gas G at about 200 C).
The first medium W is thus carried in particular in cross-counterflow in relation to the second medium G. Provided for this purpose in the region of the tube sheet 6, at a second end portion 3 of the shell space M that lies opposite from the first end portion 2 of the shell space M, is an inlet 210 (cold side of the heat exchanger 1). By way of inlet 210 the first medium W (feed water at for example 100 C) can be introduced into the shell space M, so that it flows along a direction E, heading towards the first end portion 2, to that first end portion 2 in the first portion 201 of the shell space M, and then flows back in the second portion 202 along a direction E', opposite in comparison with the first direction E, to the second end portion 3 of the shell space M. Provided there on the shell 10, adjacent to the tube sheet 6 (opposite the inlet 210) is an outlet 211 (cold side of the heat exchanger 1), by way of which the first medium W can be withdrawn from the shell space M (for example said feed water at about 250 C).
In order to be able also to conduct (divert) the first medium W in the shell space M transversely in relation to the longitudinal axis L, and correspondingly bring about a meandering flow of the first medium W in the first and second portions 201, 202 of the shell space M, there preferably extend perpendicularly away from the pass baffle 20 a plurality of cross baffles 40, which respectively connect the pass baffle 20 to an opposite inner side of the shell 10.

The cross baffles 40 are in this case particularly arranged offset in relation to one another transversely in relation to the longitudinal axis L according to Figure 2, so that passages are formed between the cross baffles 40 and the inner side of the enclosing shell 10, thereby forcing the first medium W to flow not only along the longitudinal axis L
but at the same time also back and forth transversely in relation to the longitudinal axis L, as is indicated in Figure 2 by the arrows (cf. also Figures 3 and 4).
The connection between the pass baffle 20 and the first and second shell parts 101, 102 is specifically formed in particular in the way corresponding to Figures 5 and 6.
Accordingly, the two shell parts 101, 102, respectively, each have a first end face 103, 104, made to extend along the longitudinal axis L, and a second end face (not shown in Figures 5 and 6; see 105, 106, respectively, in Figures 7-8). The first end face (103, 104) is in this case brought to lie against a respectively facing first or second side 21 a, 21 b of a first outer peripheral region 21 of the pass baffle 20 made to extend along the longitudinal axis L, those two sides 21 a, 21b facing away from one another. The two second end faces 105, 106 correspondingly, lie on both sides of a second outer peripheral region 22 (not shown in Figures 5 and 6) of the pass baffle 20 on a first and second side, respectively, of that second peripheral region 22, which sides in turn face away from one another (cf. also Figures 7 and 8). The second peripheral region 22 of the pass baffle 20 runs parallel to the first peripheral region 21. The pass baffle 20 is consequently arranged transversely in relation to the longitudinal axis L
between the two shell parts 101, 102.
For forming a sealed connection between the pass baffle 20 and the two shell parts 101, 102 along the longitudinal axis L, the first and second end faces 103, 104 and 105, 106, respectively, are then welded to the respectively assigned side 21 a, 21 b of the respective peripheral region 21, 22, so that a first, second, third and fourth weld seam 31-34 result (cf. Figures 7 and 8). These four weld seams are respectively formed continuously in a direction oriented perpendicularly in relation to the longitudinal axis L.
Hereafter, only the first and second weld seams 31, 32 according to Figures 5 and 6 are described. The third and fourth weld seams 33, 34 are of an analogous form (cf. Figures 7 and 8).
In the present case, "continuously" with respect to the weld seams means that the first and second end faces 103-106 are connected to the first and second peripheral regions 21, 22, respectively, particularly over their full surface area by way of the assigned weld seams 31-34, so that a stable, sealed connection of the shell parts 101, 102, that can absorb and withstand the pressure exerted on the shell parts 101, 102 by the first medium W conducted in the shell space M, is ensured all the way along the longitudinal axis L. Correspondingly, the first and second weld seams 31, 32, respectively, have an outwardly facing outer side 31a, 32a, which goes over into an outer side 101 a, 102a of the assigned shell part 101 and 102, respectively.
In the same way, the two weld seams 31, 32 each have an inner side 31 b, 32b, which goes over into a respectively assigned inner side 101b, 102b of the corresponding shell part 101, 102 and into an adjacent first side 20a and an adjacent second side 20b of the pass baffle 20.
According to Figure 5, the first and second weld seams 31, 32 narrow in cross section towards the shell space M, a step particularly being formed, respectively on the inner side 101b, 102b of the assigned shell part 101, 102, so that the weld seams 31, 32 reach behind the respectively assigned inner side 101b and 102b of the shell part 101, 102 concerned. Other cross-sectional forms are also conceivable.
Figure 6 shows an alternative embodiment, in which, as a difference from Figure 5, the pass baffle 20 has a constant thickness in the region of the first and second peripheral regions 21, 22. By contrast, the first and second peripheral regions 21, 22 according to Figure 5 are narrowed in the region of the weld seams 31, 32 respectively towards an outer space A surrounding the heat exchanger 11. This allows the effective connecting area between the pass baffle 20 on the one hand and the shell parts 101, 102 on the other hand to be increased.
Finally, as shown in Figures 7 and 8, the heat exchanger 1 may additionally have stiffening rings 80 for the shell 10.
According to Figures 7, it is provided that such stiffening rings 80 reach around the shell 10 transversely in relation to the longitudinal axis L, that is to say run around from the outer space A. For stiffening the shell 10, the stiffening ring or rings 80 are in this case preferably welded around the periphery or at discrete points to the shell 10 or the shell parts. The stiffening rings 80 can in this case absorb the load exerted on the shell 10 from the shell space M and support the weld seams 31 to 34.
As an alternative to this, according to Figure 8 there is the possibility that the stiffening rings 80 run around the inside of the shell 10 transversely in relation to the longitudinal axis L and are welded to it around the periphery or at discrete points. In this case, corresponding clearances may be provided on the pass baffle 20, through which the stiffening rings 80 are led. Furthermore, according to Figure 8, in a cross-sectional plane running perpendicularly in relation to the longitudinal axis, weld seams 31, 34 may extend as far as the stiffening rings 80 and correspondingly connect them to the shell 10 and/or pass baffle 20.
In comparison with the known technical teaching, throughputs in the range of particularly 80-100 m3/h can be achieved with the solution according to the invention, for 5 example, in a synthesis gas installation. The present connection between the pass baffle and the shell 10 leads to increased reliability of the process and ensures a more effective heat exchange between the tube side and the shell side of the heat exchanger 1.
Apart from synthesis gas installations, the heat exchanger 1 according to the 10 invention may also be used in refineries or power generating plants.
Specifically in the refinery area, a low risk of bypassing flows is desired. Other industries in the heat exchanger area may of course similarly use the invention.
The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
The entire disclosure[s] of all applications, patents and publications, cited herein and of corresponding German Application No. 10 2011 103 635.4 filed June 8, 2011, are incorporated by reference herein.

List of designations 1 Heat exchanger 2 First end portion 3 Second end portion 6 Tube sheet Shell Pass baffle 20a First side 20b Second side 21 First peripheral region 21a First side 21b Second side 22 Second peripheral region 22a First side 22b Second side 31 First weld seam 31a Outer side 31b Inner side 32 Second weld seam 32a Outer side 32b Inner side 33 Third weld seam 34 Fourth weld seam 40 Cross baffles 50 Connection pieces 61 First tube 62 Second tube 63 U-shaped end portion 70 Sheet 80 Stiffening ring 101 First shell part 102 Second shell part 201 First portion 202 Second portion 210 Inlet 211 Outlet 301 Inlet chamber 302 Outlet chamber 310 Inlet 311 Outlet 312 Wall 611 Free end 621 Free end A Outer space E First direction E' Second direction G Second medium K Head L Longitudinal axis M Shell space R Tube space, tube bundle W First medium

Claims (16)

1. A heat exchanger for providing heat exchange between a first and a second medium (W, G), comprising:
- a shell (10), extending along a longitudinal axis (L), which bounds a shell space (M) for receiving a first medium (W), - a tube space (R), surrounded by said shell space (M), for receiving a second medium (G), and - a pass baffle (20), arranged in said shell space (M) and made to extend along said longitudinal axis (L), for directing first medium (W) carried in said shell space (M) along said longitudinal axis (L), wherein said pass baffle (20) is welded to said shell (10).

2. The heat exchanger according to Claim 1, wherein said shell (10) has a first shell part (101), which is made to extend along said longitudinal axis (L), and a second shell part (102), which is made to extend along said longitudinal axis (L) and lies opposite to said first shell part (101) transversely in relation to said longitudinal axis (L), the two shell parts (101, 102) being connected to one another with said pass baffle (20) interposed.

3. The heat exchanger according to Claim 2, wherein said pass baffle (20) has a first peripheral region (21) with a first side (21a), which faces said first shell part (101), and a second side (21b), which is remote from said first side (21a) and faces said second shell part (102), said first shell part (101) being connected by a first end face (103), made to extend along said longitudinal axis (L), to said first side (21a) of said first peripheral region (21) by way of a first weld seam (31), and said second shell part (102) being connected by a first end face (104), made to extend along said longitudinal axis (L), to said second side (21b) of said first peripheral region (21) of said pass baffle (20) by way of a second weld seam (32).

4. The heat exchanger according to Claim 3, wherein said pass baffle (20) has a second peripheral region (22) with a first side, which faces said first shell part (101), and a second side, which is remote from said first side and faces said second shell part (102), said first shell part (101) being connected by a second end face (105), made to extend along said longitudinal axis (L), to said first side of said second peripheral region (22) by way of a third weld seam (33), and said second shell part (102) being connected by a second end face (106), made to extend along said longitudinal axis (L), to said second side of said second peripheral region (22) of said pass baffle (20) by way of a fourth weld seam (34).

5. The heat exchanger according to Claim 4, wherein the two peripheral regions (21, 22) lie opposite one another transversely in relation to the longitudinal axis (L).

6. The heat exchanger according to any one of Claims 3 to 5, wherein said weld seams (31-34) are formed continuously in a cross-sectional plane running perpendicularly in relation to said longitudinal axis of said shell (10), so that said weld seams (31-34) respectively have an outer side (31a-34a), which faces an outer space (A) surrounding the shell (10), is adjacent thereto and goes over into an outer side (101a, 102a) of the respectively assigned shell part (101, 102) of said shell (10), and said weld seams (31-34) also respectively an inner side (31b-34b), which faces the shell space (M), is adjacent thereto and goes over into an inner side (101b, 102b) of the respectively assigned shell part (101, 102) of said shell (10) that faces said shell space (M) and goes over into a respectively assigned side (20a, 20b) of said pass baffle (20).

7. The heat exchanger according to any one of Claims 3 to 6, wherein, in a cross-sectional plane running perpendicularly in relation to said longitudinal axis (L) of said shell (10), said weld seams (31, 34) initially narrow towards said shell space (M) and widen again in the region of an inner side (101b, 102b), facing said shell space (M), of the respectively assigned shell part (101, 102), so that said weld seams (31, 34) reach behind said inner sides (101b, 102b) of the respectively assigned shell part (101, 102).

8. The heat exchanger according to one of Claims 3 to 7, wherein said pass baffle (20) narrows at said peripheral regions (21, 22) towards an outer space (A) surrounding said shell (10).

9. The heat exchanger according to one of Claims 3 to 7, wherein said pass baffle has a constant thickness at said peripheral regions (21, 22).

10. The heat exchanger according to one of the preceding claims, wherein said heat exchanger (1) has at least one stiffening ring (80), which runs around on said shell (10) transversely in relation to the longitudinal axis (L) and in particular is welded to the shell (10), the at least one stiffening ring (80) particularly reaching around the shell (20) or the shell (10) reaching around the stiffening ring (80).

11. The heat exchanger according to one of the preceding claims, wherein said pass baffle (20) divides said shell space (M) into a first portion (201), which is made to extend along said longitudinal axis (L), and a second portion (202), which is made to extend along said longitudinal portion (L) and lies opposite said first portion (201), the two portions (201, 202) being connected to one another in a flow-directing manner particularly in the region of a first end portion (2) of said shell space (M), and the two portions (201, 202) respectively surrounding an assigned part of said tube space (R), so that first medium (W), carried in the two portions (201, 202), can enter into indirect heat exchange with second medium (G), carried in the respectively assigned part of said tube space (R).

12. The heat exchanger according to Claim 11, wherein an inlet (210), for introducing first medium (W) into said first portion (201) of said shell space (M), and an outlet (211), for withdrawing first medium (W) out of said second portion (202) of said shell space (M), are provided on said shell (10), at a second end portion (3) of said shell space (M) that lies opposite from said first end portion (2) of said shell space (M) along said longitudinal axis (L).

13. The heat exchanger according to one of the preceding claims, wherein heat exchanger (1) has a plurality of cross baffles (40), which are arranged in said shell space (M) and are designed and intended to deflect first medium (W), carried in said shell space (M) transversely in relation to said longitudinal axis (L), neighboring cross baffles (40) particularly being arranged offset in relation to one another, and said cross baffles (40) particularly extending respectively perpendicularly away from said pass baffle (20), and said cross baffles (40) particularly being fixed to said pass baffle (20), in particular welded to it.

14. The heat exchanger according to one of the preceding claims, wherein said tube space (R) of said heat exchanger (1) is formed by a tube bundle arranged in said shell space (M), said tube bundle (R) having at least a first tube (61), running along the longitudinal axis (L) and at least a second tube (62), running along the longitudinal axis, which tubes are connected to one another by way of a U-shaped tube portion (63), the two tubes (61, 62) being anchored at a respective free end (611, 621), lying opposite from said U-shaped tube portion (63), in a tube sheet (6) of said tube bundle (R).

15. The heat exchanger according to Claim 14, wherein said tube sheet (6) separates said shell space (M) from a head (K) of said heat exchanger (1).

16 16. The heat exchanger according to Claim 15, wherein said head (K) is divided into an inlet chamber (301) and an outlet chamber (302), wherein second medium (G) can be introduced into said tube space (R) by way of said inlet chamber (301), and wherein second medium (G) can be withdrawn from said tube space (R) and out of the heat exchanger (1) by way of said outlet chamber (302), an inlet (310), which is connected to the inlet chamber (301) and is provided for introducing second medium (G) into said inlet chamber (301), and an outlet (311), which is connected to the outlet chamber (302) and is provided for withdrawing second medium (G) out of said outlet chamber (302), particularly said inlet (310) and said outlet (311) being provided on said shell (10).