EP3759411B1 - Tube bundle-type heat exchanger, tube base, and method for sealing same - Google Patents

Description

Aspects of the invention relate to a tubesheet for a tube bundle heat exchanger. The tube sheet in particular comprises a stack of several tube sheet plates with at least one passage opening for receiving a respective tube of the tube bundle heat exchanger. The through opening is sealed by means of at least one sealing ring. Further aspects relate to a tube bundle heat exchanger with such a tube sheet and a method for sealing a tube bundle heat exchanger, in particular in the region of the tube sheet.

Technical background:

Heat exchangers for highly corrosive use are typically built with tubes made of a corrosion-resistant material such as graphite, silicon carbide, glass or PTFE. The tubes contain a first fluid and are surrounded by a second fluid located in an inner housing area, so that a heat exchange between the first and the second fluid can take place through the tube walls. The inlets and outlets of the tubes are separated from the inner housing area by a tube sheet so that the incoming and outgoing first fluid cannot mix with the second fluid. Excellent sealing of the tube sheet is crucial for this.

The tube sheet of a typical heat exchanger of this type is typically constructed from one or more tube sheet plates with a plastic-coated metal core. The plastic sheathing can, for example, comprise a chemically resistant material such as PFA or PTFE in order to enable use with corrosive media (first and / or second fluid).

In contrast to heat exchangers made of metal, in which the tubes are connected to the tube sheets in a fluid-tight manner by welding and similar processes, this is not possible when using glass or silicon carbide tubes. Instead, the tubes are passed through openings in the tube sheet (in whole or in part) and have to be sealed in a complex manner.

For example, in the DE 197 14 423 C2 discloses a shell-and-tube heat exchanger with tube sheets made of plastic in two parts and with a metal plate inserted therein. In it, tubes arranged in bores are sealed between the individual tube sheets with the help of an O-ring. However, in such heat exchangers, the The sealing effect will decrease after a while. It is therefore desirable to improve the sealing effect.

As a further example, the DE 10 2010 005216 A1 a tube bundle heat exchanger according to the preamble of claim 1, with two-part plastic tube sheets, between which an intermediate plate is arranged. Compound sleeves can be inserted into the through-holes in the intermediate plate.

Previously known solutions have the disadvantage that they require a great deal of construction effort and yet the long-term stability of the seal is not always guaranteed.

Summary of the invention:

It is therefore an object of the invention to provide a shell and tube heat exchanger in which at least some of the above-mentioned disadvantages are reduced.

In particular, the simplest possible construction with the most reliable sealing effect possible should be made possible.

A tube sheet according to claim 1, a tube bundle heat exchanger according to claim 11, a method according to claim 14 and a use according to claim 15 are therefore proposed. Further advantageous aspects are shown in the dependent claims, the figures and the following description.

According to one aspect of the invention, a tube sheet for a tube bundle heat exchanger is provided. The tube sheet comprises a first tube sheet plate with a core and a plastic casing surrounding the core, a second tube sheet plate made of a temperature-resistant material (e.g. a graphite or ceramic plate), and a third tube sheet plate with a core and a plastic casing surrounding the core.

The first, second and third tube sheet plates are stacked in a stack, with the second tube sheet plate being arranged as an intermediate plate between the first and third tube sheet plates (20, 40) so that a first surface of the second tube sheet plate faces the first tube sheet plate and an opposite one second surface of the second tubesheet plate is directed towards the third tubesheet plate.

The stack has at least one through opening for receiving a respective tube of the tube bundle heat exchanger. The tube sheet also has for each of the at least one through-opening: at least one sealing ring each for sealing the respective tube, and at least one sealing seat each for receiving the at least one sealing ring, the sealing seat being a recess in the second tube sheet that immediately surrounds the respective through-opening in a ring-like manner .

Aspects of the invention have the advantage that a second tube sheet plate made of a temperature-resistant material is made available, and that a sealing seat for receiving the sealing ring is let into it. Such a sealing seat enables a reliable and long-term stable sealing of the tube sheet plate.

In addition, the second tube sheet plate is arranged in a stack between two plastic-coated tube sheet plates (first and third tube sheet plate) and is protected from mechanical loads by them. This arrangement further increases the stability of the tube sheet. This arrangement as a stack makes it possible, in particular, to provide a tube sheet which combines the advantageous properties of the respective tube sheet plates.

Since the second tube sheet plate is constructed as a whole from a temperature-resistant material and preferably consists of the temperature-resistant material, the reliability of the sealing seat is increased even further. A particularly simple structure of the tube sheet can also be achieved in this way.

Description of further aspects of the invention:

Further preferred (i.e., optional) aspects of the invention are described below. For purposes of illustration, reference symbols relate to the figures described in more detail below, but do not limit the aspects to the embodiments shown there. Unless otherwise indicated, each aspect can be combined with any other aspect or any other embodiment described herein.

According to one aspect, the temperature-resistant material of the second tube sheet plate is defined in that the material has no substantial flow behavior for temperatures up to at least 250 ° C. For plastics, this condition is defined by a heat distortion temperature greater than 250 ° C, with the heat distortion temperature being determined in accordance with DIN EN ISO 75-2: 2013 (under a load of 0.45 MPa according to method B). Common plastics such as PFA and PTFE do not meet this requirement. The plastic PEEK is an exception, for which the deformation temperature is greater than 250 ° C. Plastics with a high filler content with dimensionally stable fillers can also meet the requirement. The above criterion applies analogously to non-plastics. Steel, ceramic, graphite, glass and other materials with similarly low flow properties at 250 ° C are always to be regarded as temperature-resistant, regardless of the above condition. The material of the second tube sheet plate is particularly preferably a ceramic.

According to a further aspect, the temperature-resistant material of the second tube sheet plate is therefore selected from the materials steel, ceramic, glass, plastic with a dimensional stability temperature of greater than 250 ° C. as defined above, in particular PEEK, and a mixture thereof (e.g. as a composite material).

According to a further aspect, the material of the second tube sheet plate has a thermal linear expansion α <20 μm / mK for any temperature between -50 ° C and 200 ° C. This ensures a secure seal fit even with temperature fluctuations.

According to a further aspect, the material of the second tubesheet plate has a modulus of elasticity> 300GPa. This ensures good flexural rigidity of the second tube sheet.

According to a further aspect, the core (22, 42) of the first and / or the third tube sheet plate each comprises or consists of at least one of a metal (e.g. a metal alloy) and a fiber composite material. The fiber composite material can be, for example, a carbon-based fiber composite material such as CFRP and / or CFC. The plastic casing (24, 44) of the first and / or the third tube sheet plate can each comprise at least one fluoropolymer such as PFA and / or PTFE. According to one aspect, the plastic casing (24, 44) is not made of a material that is temperature-resistant to a limited extent (e.g. does not meet the above definition of a temperature-resistant material).

According to a further aspect, the first and third tube sheet plates (20, 40) are constructed identically, as a result of which the number of different parts can be reduced.

According to a further aspect, the second tube sheet plate (30) is a graphite or ceramic plate, the ceramic preferably being a non-oxide ceramic such as SSiC, SiSiC, and / or SN. The second tube sheet plate can comprise or consist of the graphite or the ceramic. Advantages of these materials are their temperature resistance with simultaneous corrosion resistance, as well as advantageous mechanical properties in the stack.

According to a further aspect, the at least one through opening (14) is a plurality of through openings. According to a further aspect, the second tube sheet plate (30) is in one piece, so that the same monolithic material of the second tube sheet plate (30), e.g. graphite or ceramic, adjoins the plurality of through openings (14).

According to a further aspect, the at least one sealing seat (34, 38, 39) and / or the at least one sealing ring (52) is designed with a rectangular (in particular square), trapezoidal, conical, conical or partially oval cross-section. The cross section of the sealing seat can be open towards an inside of the respective through opening (14). Furthermore, one side of the seal seat can pass through a surface section of the first and the third tube sheet plate, respectively be educated. According to one section, at least two sides of the sealing seat are formed by a (recessed) surface section of the second tube sheet.

According to a further aspect, each of the at least one sealing ring (52) is at least two sealing rings. Each of the at least one sealing seat (34, 38) thus comprises at least one first and one second sealing seat. The first sealing seat (34) can be arranged as a depression in the first surface (32) of the second tube sheet plate (30), and the second sealing seat (38) can be arranged as a depression in the second surface (36) of the second tube sheet plate (30) being.

According to a further aspect, the sealing rings (52) are pressed in in the respective sealing seat (34, 38) between the second and the first tube sheet plate (30, 20) or the second and the third tube sheet plate (30, 40) in such a way that the sealing rings touch the respective plastic casing (24, 44) on at most one side, but preferably touch the material of the second tube sheet on at least two sides (one side of which is the side opposite the through opening).

According to a further aspect, the sealing seat (39) is arranged as a recess spaced from the first and second surfaces (32, 36) of the second tube sheet plate (30) in a side wall of the through opening (14).

According to a further aspect, the first, second and third tube sheet plates (20, 30, 40) are pressed against one another by clamping, e.g. by means of a flange and / or a tie rod. The force for pressing the tube sheet plates against one another is preferably introduced exclusively from an edge region of the tube sheet plates (20, 30, 40), e.g. through a flange. Otherwise, the tube sheet plates (20, 30, 40) are preferably mechanically decoupled. A sufficient clamping effect can be provided by the rigidity of the second tube sheet.

According to a further aspect, a tube bundle heat exchanger (1) with the tube sheet (10) described herein is provided. The tube bundle heat exchanger (1) comprises a tube (50) for each of the at least one passage opening (14), which passes completely or partially through the respective passage opening (at least as far as the second tube base plate) and which by means of the in the at least one sealing seat (34, 38 , 39) lying at least one sealing ring (52) is sealed. This does not rule out the presence of further through openings (e.g. for tie rods).

According to a further aspect, the tube (50) is a graphite, SiC or glass tube, that is to say comprises these materials or consists of them.

According to a further aspect, the tube bundle heat exchanger is intended for a strongly corrosive medium (e.g. strong acids such as hydrofluoric acid (HF), hydrochloric acid (HCl), Nitric acid (HNO ₃ ), or strong alkalis). The plastic casing (24, 44) is chemically resistant to the corrosive medium.

According to a further aspect, a method for sealing a tube bundle heat exchanger (1) is proposed. The method comprises the following steps: a tubesheet (10) according to one of claims 1 to 10 is provided; and at least one tube (50) of the tube bundle heat exchanger is passed through the corresponding through opening (14) and sealed by means of the at least one sealing ring (52) located in the at least one sealing seat (34, 38, 39). The method can be part of a manufacturing method for the tube bundle heat exchanger or a maintenance or repair method for the tube bundle heat exchanger.

Brief description of the figures:

• Figur 1 zeigt eine Querschnittsansicht eines Rohrbündelwärmeaustauscher mit einem Rohrboden gemäß einer Ausführungsform der Erfindung;
• Figur 2 zeigt eine vergrößerte Querschnittsansicht eines Rohrbodens gemäß einer weiteren Ausführungsform der Erfindung; und
• Figur 3 zeigt eine Querschnittsansicht der zweiten Rohrbodenplatte eines Rohrbodens gemäß einer weiteren Ausführungsform der Erfindung.

Furthermore, the invention is to be explained on the basis of exemplary embodiments shown in the figures, from which further advantages and modifications result. To do this, show:

• Figure 1 shows a cross-sectional view of a tube bundle heat exchanger with a tube sheet according to an embodiment of the invention;
• Figure 2 shows an enlarged cross-sectional view of a tube sheet according to a further embodiment of the invention; and
• Figure 3 shows a cross-sectional view of the second tube sheet plate of a tube sheet according to a further embodiment of the invention.

Detailed description of embodiments of the invention:

Regarding Figure 1 a shell-and-tube heat exchanger 1 according to an embodiment of the invention is described below. The tube bundle heat exchanger 1 has a housing 6, a tube sheet 10 with through openings 14, and tubes 50 which lead through the respective through openings 14.

In operation, the tubes 50 contain a first fluid and are supplied by an in an inner housing area (to the right of the tube sheet 10 in Fig. 1 ) located second fluid, so that a heat exchange between the first and the second fluid can take place through the tube walls. The inlets and outlets of the tubes 50 (to the left of the tube sheet 10 in Fig. 1 ) are separated by the tube sheet 10 from the inner housing area to the right of the tube sheet 10 and sealed therein as described below.

The tube sheet 10 comprises a first tube sheet plate 20 with a core 22 and a plastic casing 24 surrounding the core, a second tube sheet plate 30 made of the temperature-resistant material already described above, and a third tube sheet plate 40 with a core 42 and a plastic casing 44 surrounding the core.

The three tube sheet plates 20, 30, 40 are stacked to form a stack, in which the second tube sheet plate 30 is arranged as an intermediate plate between the first and third tube sheet plates 20, 40. In other words, the first surface 32 of the second tube sheet plate is directed towards the first tube sheet plate 20 and the opposite second surface 36 of the second tube sheet plate is directed towards the third tube sheet plate 40.

In each of the through-openings 14, two sealing seats 34, 38, each with a sealing ring 52 received therein, are attached in order to seal the respective pipe 50. More precisely, the sealing seats 34, 38 are designed as depressions in the second tube sheet plate 30, which directly surrounds the through opening 14 in a ring-like manner. The rear surface opposite the through opening 14 and a side surface of the sealing seats 34, 38 is formed by the second tube sheet plate 30, and a further side surface of the sealing seats 34, 38 is formed by the first and third tube sheet plates 20, 40, more precisely by their plastic casing 24, 44 educated.

The fact that the sealing seats 34, 38 are designed as depressions in the second, temperature-stable tube sheet plate 30 enables a stable and reliable sealing effect.

The three tube sheet plates 20, 30 and 40 are pressed against one another by a pair of flanges of the housing 6 and thus clamped together. The clamping takes place by means of a bracing element (such as a tension element such as a screw), which is not shown, which is passed through the flanges and through the stack of tube sheet plates 20, 30 and 40 in order to press the flanges together and thus compress the stack. The bracing element extends here through a flange through-opening 16, which passes through the flanges and through the stack of the three tube sheet plates 20, 30 and 40.

The bracing elements are arranged exclusively in the edge area (flange area) of the tube sheet. In the interior of the housing 6, on the other hand, the tube sheet plates 20, 30, 40 are mechanically decoupled. Due to the bending stiffness of the tube sheet, in particular of the second tube sheet plate 30, bracing elements or connecting elements located further inside can be dispensed with and it can still be ensured that the tube sheet plates 20, 30, 40 are sufficiently pressed against one another.

Figure 2 shows an enlarged cross-sectional view of a tube sheet according to a further embodiment of the invention. This embodiment largely corresponds to the embodiment of FIG Figure 1 , and the description of the Figure 1 also applies here accordingly.

Only the cross-sectional shape of the sealing rings 52 and the associated sealing seats 34, 38 differ. In Figure 1 the sealing rings 52 and the sealing seats 34, 38 have a rectangular (square) cross-section, and in Figure 2 they have a trapezoidal cross-section. Other cross-sections described above are also possible.

Figure 3 shows a cross-sectional view of the second tube sheet plate 30 of a tube sheet according to a further embodiment of the invention. Apart from the illustrated design of the second tube sheet plate 30 (and in particular the sealing seat and the associated sealing rings), the embodiment corresponds to that in FIG Fig. 1 illustrated structure.

In the second tube sheet plate 30 according to FIG. 4, instead of the one in Fig. 1-3 shown two seal seats 34, 38 only a single seal seat 39 attached. The sealing seat 39 is attached to the side wall of the through opening 14 in an axially central section of the second tube sheet plate 30 and is thus spaced apart from the first and third tube sheet plates. According to FIG. 4, only a single sealing ring is provided per through opening. All sides of the sealing seat 39 are formed by the temperature-resistant material of the second tube sheet plate 30.

Unless otherwise shown, the embodiments of FIGS. 1-4 can have all of the further aspects described above. The embodiments and aspects serve only for illustration and are not intended to limit the scope of protection. The scope of protection is defined by the following claims.

Claims (15)

1. Tube sheet (10) for a shell and tube heat exchanger (1), the tube sheet comprising:

   - a first tube sheet plate (20) having a core (22) and a plastics sheath (24) surrounding the core,

   - a second tube sheet plate (30) made of a temperature-resistant material, and

   - a third tube sheet plate (40) having a core (42) and a plastics sheath (44) surrounding the core,

   the first, second and third tube sheet plates being stacked to form a stack,

   the second tube sheet plate (30) being arranged as an intermediate plate between the first and the third tube sheet plate (20, 40), such that a first surface (32) of the second tube sheet plate is directed to the first tube sheet plate (20) and an opposite second surface (36) of the second tube sheet plate is directed to the third tube sheet plate (40), and

   the stack having at least one through-opening (14) for receiving a relevant tube (50) of the shell and tube heat exchanger, and wherein

   the tube sheet further has, for each of the at least one through-opening (14):

   - at least one sealing ring (52) each for sealing the relevant pipe,

   - at least one seal seat (34, 38, 39) each for receiving the at least one sealing ring (52), the seal seat being a recess in the second tube sheet plate (30) that surrounds the relevant through-opening directly in an annular manner,
   characterised in that the temperature-resistant material has no substantial flow behaviour for temperatures up to at least 200°C and no substantial thermal expansion for temperatures between -50°C and 200°C.
2. Tube sheet for a shell and tube heat exchanger according to claim 1, wherein the core (22, 42) of the first and/or the third tube sheet plate in each case comprises at least one of a metal and a fibre composite material.
3. Tube sheet for a shell and tube heat exchanger according to either of the preceding claims, wherein the first and third tube sheet plates (20, 40) are of identical construction.
4. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein the second tube sheet plate (30) is a graphite or ceramic plate.
5. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein the at least one through-opening (14) is a plurality of through-openings, and wherein the second tube sheet plate (30) is formed in one piece, such that the same monolithic material of the second tube sheet plate (30) is adjacent to the plurality of through-openings (14).
6. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein the at least one sealing ring (52) is designed with a cross section which is rectangular, trapezoidal, conical, cone-shaped, or oval in portions.
7. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein each at least one sealing ring (52) is in each case at least two sealing rings, and wherein each at least one seal seat (34, 38) in each case comprises at least one first and one second seal seat, wherein the first seal seat (34) is arranged as a recess in the first surface (32) of the second tube sheet plate (30) and the second seal seat (38) is arranged as a recess in the second surface (36) of the second tube sheet plate (30).
8. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein the sealing rings (52) are pressed in the relevant seal seat (34, 38) between the second and the first tube sheet plates (30, 20) or the second and the third tube sheet plates (30, 40), respectively, such that the sealing rings contact the relevant plastics sheath (24, 44) on at most one side.
9. Tube sheet for a shell and tube heat exchanger according to any of claims 1 to 6, wherein the seal seat (39) is arranged in a lateral wall of the through-opening (14) as a recess spaced from the first and second surfaces (32, 36) of the second tube sheet plate (30).
10. Tube sheet for a shell and tube heat exchanger according to any of the preceding claims, wherein the first, second and third tube sheet plates (20, 30, 40) are pressed against one another by clamping.
11. Shell and tube heat exchanger (1) comprising the tube sheet (10) according to any of the preceding claims, and, for each at least one through-opening (14), a tube (50) which passes through the relevant through-opening and is sealed in by the at least one sealing ring (52) located in the at least one seal seat (34, 38, 39).
12. Shell and tube heat exchanger according to claim 11, wherein the tube (50) is a graphite tube, SiC tube or glass tube.
13. Use of the shell and tube heat exchanger according to either claim 11 or claim 12, wherein the shell and tube heat exchanger is provided for a corrosive medium and wherein the plastics sheath (24, 44) is chemically resistant to the corrosive medium.
14. Method for sealing a shell and tube heat exchanger (1), the method comprising:

    - providing a tube sheet (10) according to any of claims 1 to 10,

    - passing at least one tube (50) of the shell and tube heat exchanger through the corresponding through-opening (14) and sealing said tube by means of the at least one sealing ring (52) located in the at least one seal seat (34, 38, 39).
15. Use of the tube sheet (10) according to any of claims 1 to 10 for sealing the shell and tube heat exchanger (1).

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