EP2131131A1

EP2131131A1 - Heat exchanger

Info

Publication number: EP2131131A1
Application number: EP08157756A
Authority: EP
Inventors: Freddy Wollants
Original assignee: Scambia Industrial Developments AG
Current assignee: Scambia Industrial Developments AG
Priority date: 2008-06-06
Filing date: 2008-06-06
Publication date: 2009-12-09

Abstract

A heat exchanger (1;3) comprises at least one group of tubes (20;40) the one ends of which are connected to a first manifold (21;41) and the other ends of which are connected to a second manifold (22,42). Each such group of tubes forms a separate module (2;4) comprising a row of laterally adjacently arranged tubes (20;40) the ends of which are connected to the first (21;41) and second (22;42) manifolds, respectively, with the separate modules (2;4) being arranged one after the other, and with manifolds (21,22;41,42) of adjacently arranged modules being connected to one another through at least one connecting channel piece (25;45) in a manner so as to form a series arrangement of modules (2;4).

Description

The present invention deals with a heat exchanger according to independent claim 1.
Heat exchangers are known in various fields of applications, for example in air conditioning, in heatings or in heat recuperators of gas tubines, as well as in many further fields of applications. For example, a heat exchanger of a heating is shown in US 2008/0061160 . A heat exchanger of an air conditioning for a vehicle is known, for example, from DE 102 60 030 .
Heat exchangers are also used, for example, to extract heat out of exhaust and bring it into the ranking cycle fluid. In particular in gas turbines, the heat of the hot exhaust gas stream that exits the turbine is used to pre-heat the input gas stream by means of a heat exchanger. In order to heat the thus pre-heated gas stream to the desired temperature of the input gas stream for the gas turbine, only a smaller amount of heat is required thus raising the efficiency of the gas turbine.
However, such known heat exhanger is constructed as an entire block of a large number of tubes which are connected to one another by collectors (manifolds) at their upper and lower ends. The block comprises an array of rows and columns of tubes. In case one of the tubes of such block is leaking, this cannot be identified during assembly of the block and, once assembly has been finished, it is either extremely difficult to find out which one of the tubes is leaking (if possible at all), and even the leaking tube can be identified it may be extremely difficult to repair if possible at all. In case the leak cannot be found or repaired, the entire block is inoperable and cannot be used.
Therefore, it is an object of the present invention to provide a heat exchange apparatus which is simple in construction and which avoids the disadvantages mentioned above.
This object is achieved by a heat exchanger as it is specified by the features of independent claim 1. Further embodiments of the said heat exchanger are the subject of the dependent claims.
In particular, the heat exchanger according to the invention comprises at least one group of tubes the one ends of which are connected to a first manifold and the other ends of which are connected to a second manifold. Each such group of tubes forms a separate module comprising a row of laterally adjacently arranged tubes the ends of which are connected to the first and second manifolds, respectively. The separate modules are arranged one after the other, and manifolds of adjacently arranged modules are connected to one another through at least one connecting channel piece in a manner so as to form a series arrangement of modules.
The modular construction with each such module comprising a row of laterally adjacently arranged tubes allows to easily test each module for its working capability and in case the module is found to be leaking or otherwise inoperable it can be either repaired - if possible - or another module can that works well can be used. Accordingly, it is possible to assemble an entire heat exchanger block that will work well since the single modules are tested prior to assembly of the modules which are arranged one after the other by connecting the manifolds of the respective module to the respective manifold of the preceding module and of the subsequent module, respectively, with the aid of the connecting channel pieces. This can be performed by welding, for example. The connection of the manifolds allows good mixing of the fluid flowing through the individual tubes of a module so that the temperature of the fluid contained in a manifold of a particular module is evenly distributed. Also, if one of the tubes of a module gets blocked for any reason (e.g. due to plugging) the fluid will flow through the remaining tubes of the module.
In one embodiment of the heat exchanger according to the inveniton, the tubes of the respective modules extend in an essentially longitudinal direction such that the one ends of these tubes are connected to an upper manifold while the other ends of these tubes are connected to a lower manifold. The upper manifold of the respective module is connected through at least one of the at least one connecting channel pieces to the upper manifold of the preceding module while the lower manifold of the same module is connected to the lower manifold of the subsequent module through at least one of the at least one connecting channel pieces, or vice versa (meaning that the upper manifold of the respective module is connected to the upper manifold of the subsequent module while the lower manifold of the same module is connected to the lower maniforld of the preceding module). This is an easy and reliable manner of realizing the series arrangement of the separate individual modules.
In a further embodiment of the heat exchanger according to the invention, the upper and lower manifolds of the respective modules are each connected to the respective upper or lower manifolds of the preceding or subsequent module through a pair of connecting channel pieces. This provides for an improved connection of the respective manifolds while at the same time providing for one redundant connection. Also, from a mechanical point of view this provides for additional stability of the connection of the modules to one another.
In particular, in accordance with a further embodiment of the heat exchanger according to the invention, those pairs of connecting channel pieces connecting the upper manifolds are arranged in a zig-zag configuration, and those pairs of connecting channel pieces connecting the lower manifolds are arranged in a zig-zag configuration, too. The zig-zag arrangement allows easy access to the respective connecting channel pieces should this turn out to be necessary (e.g. if one of the connecting channel pieces turns out to be defective during assembly).
In a further embodiment of the heat exchanger according to the invention, the tubes extending in the essentially longitudinal direction comprise a pre-bent portion so as to allow them to deform during thermal expansion. In particular in high temperature applications, as this is the case in the field of gas turbines, the tubes through which the hot fluid is flowing are heated and may bend due to the thermal expansion of the material the tubes are made of. This prevents that thermal stress may occur to an extent that would result in damage to the tubes due to their disability to deform (e.g. the tubes are strictly straight and are welded to the respective manifolds at both ends of the tubes). Rather, due to the pre-bent portion the tubes may bend in the desired direction thus avoiding the above-described damages to occur.
In a further embodiment of the heat exchanger according to the invention, individual modules are connected to one another only through the connecting channel pieces. This is a kind of mechanical connection which is flexible at least to a certain extent since it allows for some lateral movement relative to one another of two modules which are arranged one after the other.
In a further embodiment of the heat exchanger according to the invention, the tubes of the respective modules are essentially U-shaped, with the one ends of the U-shaped tubes being connected to a first upper manifold while the other ends of the tubes being connected to a second upper manifold. The second upper manifold of the respective module is arranged in front of or behind the first upper manifold of that module, respectively. In addition, the second upper manifold of the respective module is connected to the first upper manifold of the subsequent module or to the first upper manifold of the preceding module, respectively. This alternative construction with the tubes having an essentially U-shape is advantageous inasmuch as the afore-mentioned stress due to thermal expansion can be compensated for by an elongation of the two legs of the U-shaped tubes in the longitudinal direction. This elongation of the legs of the U-shaped tubes is not constrained since the tubes are not welded to a manifold at their lower end.
Further advantageous aspects of the heat exchanger according to the invention will become apparent from the following description of embodiments of the heat exchanger with the aid of the drawings in which:

Fig. 1: shows a perspective view of a first embodiment of a heat exchanger according to the invention,
Fig. 2: shows a perspective view of a single module of the heat exchanger of Fig. 1,
Fig. 3: shows a sectional view of the heat exchanger of Fig. 1,
Fig. 4: shows a perspective view of a second embodiment of a heat exchanger according to the invention,
Fig. 5: shows a perspective view of a single module of the heat exchanger of Fig. 4,
Fig. 6: shows a lateral side view of the module of Fig. 5,
Fig. 7: shows a top view of the heat exchanger of Fig. 4, and
Fig. 8: shows a schematic sectional view of the heat exchanger of Fig. 4.

In Figs. 1-3 a first embodiment of a heat exchanger according to the invention and its components are shown. The first embodiment of the heat exchanger 1 shown in Fig. 1 in its assembled state comprises a plurality of separate individual modules 2, with each separate module 2 comprising a plurality of tubes 20, an upper manifold 21 and a lower manifold 22. The separate modules 2 are arranged one after the other.
Heat exchanger 1 further comprises an inlet 10 for the fluid, e.g. water, to be heated as well as an outlet 11 for the heated fluid, e.g. steam. As can be seen from Fig. 1 and starting from that side where the outlet 11 is arranged, the lower manifold 22 of the first separate module 2 is connected to the lower manifold 22 of the second separate module 2 through two connecting channel pieces 25. The upper manifold 21 of the second separate module 2 is connected to the upper manifold 21 of the third separate module 2 through two connecting channel pieces 25, too. This goes on in like manner meaning, that the lower manifold 22 of the third separate module 2 is connected to the lower manifold 22 of the fourth separate module 2 through two connecting channel pieces 25, the upper manifold 21 of the fourth separate module 2 is connected to the upper manifold 21 of the fifth separate module 2 through two connecting channel pieces, and so on. Thus, a series arrangement of modules 2 is formed. The connecting channel pieces 25 are arranged in a zig-zag arrangement so that they are easily accessible.
Within one single module 2, the upper ends of the tubes 20 are connected to the upper manifold 21 of the said module 2 while the lower ends of the tubes 20 are connected to the lower manifold 22 of the said module 2, respectively. Upper and lower manifolds 20,21 are arranged on respective upper and lower flanges 210,220. The tubes 20 extend through respective holes provided for each of the tubes 20 in flanges 210,220, as well as through corresponding holes provided in the upper and lower manifolds 21,22, respectively. The upper ends and lower ends of the tubes 20 can be connected to the upper manifold 21 and to the lower manifold 22 as well as to the flanges 210,220, respectively, through welding, e.g. through TIG-welding.
A separate module 2 of the heat exchanger 1 of Fig. 1 is shown in Fig. 2 prior to assembly. Module 2 comprises a row of laterally adjacently arranged tubes 20, in the embodiment shown module 2 comprises two rows of laterally adjacently arranged tubes 20. As can be seen from Fig. 1 and Fig. 2, tubes 20 extend essentially in the longitudinal direction and comprise at least one pre-bent portion 200 so as to allow them to deform in a desired direction during thermal expansion and to prevent them to get damaged at their weldings due to too high thermal stress. Upper manifold 21 and lower manifold 22 are each provided with two collared openings 211,221, to which the connecting channel pieces 25 can be attached, e.g. through welding.
From the sectional view of the heat exchanger 1 shown in Fig. 3 the working principle of heat exchanger 1 becomes evident. Hot gas, e.g. exhaust gas coming from a gas turbine (not shown) or from any other exhaust flows through the heat exchanger as indicated by the respective arrows HG. At the same time a "cold" fluid to be heated, e.g. water, flows through inlet 10 and through the respective tubes 20. This is also indicated by respective arrows CF. Each time the hot gas HG comes into contact with the tubes 20 through the which the initially cold fluid CF flows, heat is transferred from the hot gas HG through the walls of the tubes 20 to the initially cold fluid CF which is now indicated as fluid F, thus cooling down the hot gas HG until it reaches its lowest temperature when exiting heat exchanger 1 as comparatively "cold gas" CG, as is indicated by the respective arrows in Fig. 3. At the same time, fluid F is heated until it reaches its highest temperature and exits heat exchanger 1 through outlet 11 as hot fluid HF, e.g as superheated steam.
Fig. 3 shows in more detail, that fluid F first enters the module 2 arranged at the right hand end through its upper manifold 21, and then flows downwards through the tubes 20 into the lower manifold 22 of this module 2. The fluid F then further flows through the connecting channel pieces 25 into the lower manifold 22 of the subsequent module 2, which is arranged directly adjacently of the said module 2 (on the left in Fig. 3). From the lower manifold 22 of this module 2, the fluid flows upwards through the tubes 22 into the upper manifold 21 of the said module 2, and from this upper manifold 21, the fluid F flows through the connecting channel pieces 25 into the upper manifold of the subsequent module 2, and so on, until finally the fluid F exits heat exchanger 1 through its outlet 11. The manifolds 21,22 allow for a good intermixing of the fluid so as to achieve a more or less even uniform temperature of the fluid F in the respective manifold. Also, if one of the the tubes 20 may become clogged for any reason, the fluid may continue to flow through the other tubes 20 of the said module 2 without causing problems.
As can be seen from Fig. 1, the individual modules 2 of heat exchanger 1 are connected to one another only through the connecting channel pieces 25, thus allowing the modules 2 to move to some extent laterally relative to one another.
A second embodiment of the heat exchanger according to the invention and its components are shown in Figs. 4-8. The second embodiment of the heat exchanger 3 shown in Fig. 4 in its assembled state again comprises a plurality of separate individual modules 4, with each separate module comprising a plurality of U-shaped tubes 40, and two upper manifolds 41,42. The separate modules are arranged one after the other.
Heat exchanger 3 further comprises and inlet 30 for the fluid, e.g. water, to be heated as well as an outlet 31 for the heated fluid, e.g. steam. As can be seen from Fig. 4 and starting from that side where the outlet 31 is arranged, the second upper manifold 42 of the first separate module 4 is connected to the first upper manifold 41 of the second separate module 4 which is arranged behind the first separate module 4 through two connecting channel pieces 45, as this can be seen best in Fig. 7. This goes on in like manner, meaning that the second upper manifold 42 of the second separate module 4 is connected to the first upper manifold of the third separate module 4 through two connecing channel pieces 45, and so on. Thus, a series arrangement of modules 4 is formed. The connecting channel pieces 45 are again arranged in a manner such that they are easily accessible.
Within one single module 4, the respective ends of the U-shaped tubes 40 are connected to the first upper manifold 41 and to the second upper manifold 42 of the module 4. The first and second upper manifolds 41,42 are arranged on respective upper flanges 410,420. The U-shaped tubes 40 extend through respective holes provided for each of the tubes 40 in flanges 410,420 , as well as through corresponding holes in the upper and lower manifolds. The ends of the tubes 40 can be connected to the upper manifolds 40,41 as well as to the flanges 410,420, respectively, through welding, e.g. TIG-welding.
Also, guiding plates 43,44 are provided which provide for additional stability of the separate modules 4 (since the legs of the U-shaped tubes 40 may have considerable lengths) and which guide the tubes 40 during thermal expansing so that they expand in the longitudinal direction. The guiding plates 44 of the first separate module 4 may be connected to the guiding plates 43 of the second separate module 4, and so on, through respective welding spots 430, which are indicated in Fig. 4. This provides for additional stability to the entire heat exchanger 4.
A separate module 4 of the heat exchanger 4 of Fig. 4 is shown in a perspective view in Fig. 5 and in a lateral side view in Fig. 6. Module 4 comprises a row of laterally adjacently arranged tubes 40 having the afore-mentioned U-shape. In the embodiment shown, module 4 comprises two rows of U-shaped tubes 40, an "outer" row of tubes 40, and an "inner" row tubes 40. As can be seen, the ends of each tube 40 are connected to the first and second manifolds 41,42 laterally offset (staggered) relative to one another. The first and second upper manifolds 41,42 are each provided with two collared openings 411,421 , to which the connecting channel pieces 45 can be attached, e.g. through welding.
From the sectional view of the heat exchanger 4 shown in Fig. 8 the working principle of heat exchanger 4 becomes evident. Hot gas, e.g. exhaust gas coming from a gas turbine (not shown) flows through the heat exchanger as indicated by the respective arrows HG. At the same time, a "cold" fluid to be heated, e.g. water, flows through inlet 30 and through the respective tubes 40. This is also indicated by respective arrows CF. Each time hot gas HG comes into contact with the tubes 40 through which the initially cold fluid CF flows, heat is transferred from the hot gas HG through the walls of the tubes 40 to the initially cold fluid CF which is now indicated as fluid F, thus cooling down the hot gas HG until it reaches its lowest temperature when exiting heat exchanger 4 as comparatively "cold gas" CG, as this is indicated by the respective arrows in Fig. 8. At the same time fluid F is heated until it reaches it highest temperature and exits heat exchanger 4 through outlet 41 as superheated steam.
Fig. 8 shows, that fluid F first enters the module 4 arranged at the right hand end throug second upper manifold 42, then flows downwards through one leg of the tubes 40 to the lowermost end of the U-shaped tubes 40, and then continues to flow upwards through the other leg of the U-shaped tubes 40 into first upper manifold 41 of the said module 4. The fluid F then flows through the connecting channel pieces 45 into the second upper manifold 42 of the subsequent module 4, which is arranged directly adjacently of the said module 4 (on the left in Fig. 4). Then, the fluid continues to flow downwards through the one leg of the tubes 40 of that subsequent module 4 to the lowermost end of the U-shaped tubes 40, and then continues to flow upwards through the other leg of the U-shaped tubes 40 into the first manifold 41 of that subsequent module 4, and so on. Again, the manifolds 41,42 allow for a good intermixing of the fluid so as to achieve a more or less even uniform temperature of the fluid F in the respective manifold. Also, if one of the U-shaped tubes becomes clogged for any reason, the fluid may continue to flow through the other U-shaped tubes 40 of the said module 4 without causing problems.
Having described specific embodiments of the heat exchanger according to the invention, it is to be understood that these embodiments are not intended to limit the scope of protection to these embodiments, since many modifications to these embodiments are conceivable without departing from the spirit of the present invention. Accordingly, the scope of protection is intended to be defined by the appended claims.

Claims

Heat exchanger (1;3) comprising at least one group of tubes (20;40) the one ends of which are connected to a first manifold (21;41) and the other ends of which are connected to a second manifold (22,42), characterized in that each such group of tubes forms a separate module (2;4) comprising a row of laterally adjacently arranged tubes (20;40) the ends of which are connected to the first (21;41) and second (22;42) manifolds, respectively, with the separate modules (2;4) being arranged one after the other, and with manifolds (21,22;41,42) of adjacently arranged modules being connected to one another through at least one connecting channel piece (25;45) in a manner so as to form a series arrangement of modules (2;4).
Heat exchanger according to claim 1, wherein the tubes (20) of the respective modules (2) extend in an essentially longitudinal direction such that the one ends of these tubes (20) are connected to an upper manifold (21) while the other ends of these tubes are connected to a lower manifold (22), and wherein the upper manifold (21) of the respective module (2) is connected through at least one of the at least one connecting channel pieces (25) to the upper manifold (21) of the preceding module (2) while the lower manifold (22) of the same module (2) is connected to the lower manifold (22) of the subsequent module (2) through at least one of the at least one connecting channel pieces (25), or vice versa.
Heat exchanger according to claim 2, wherein the upper and lower manifolds (21,22) of the respective modules (2) are each connected to the respective upper or lower manifolds (21,22) of the preceding or subsequent module (2) through a pair of connecting channel pieces (25).
Heat exchanger according to claim 3, wherein those pairs of connecting channel pieces (25) connecting the upper manifolds (21) are arranged in a zig-zag configuration, and wherein those pairs of connecting channel pieces (25) connecting the lower manifolds (22) are arranged in a zig-zag configuration, too.
Heat exchanger according to any one of claims 2 to 4, wherein the tubes (20) extending in the essentially longitudinal direction comprise a pre-bent portion (200) so as to allow them to deform during thermal expansion.
Heat exchanger according to any one of the preceding claims, wherein the individual modules (2) are connected to one another only through the connecting channel pieces (25).
Heat exchanger according to claim 1, wherein the tubes (40) of the respective modules (4) are essentially U-shaped, with the one ends of the U-shaped tubes (40) being connected to a first upper manifold (41) while the other ends of the tubes (40) being connected to a second upper manifold (42), with the second upper manifold (42) of the respective module (4) being arranged in front of or behind the first upper manifold (41) of that module (4), respectively, and with the second upper manifold (42) of the respective module (4) being connected to the first upper manifold (41) of the subsequent module (4) or to the first upper manifold (4) of the preceding module (4), respectively.