Shell and tube heat exchanger

Abstract

The invention relates to a shell and tube heat exchanger (100), comprising a plurality of tubes (110), a tube sheet (120), a shell (150), an inlet chamber (130), an outlet chamber (140), a shell inlet (152) and a shell outlet (152), wherein the inlet chamber (130) is connected, via the plurality of tubes (110), to the outlet chamber (140), establishing a fluid path for a first fluid (a), wherein the plurality of tubes (110) is connected to the tube sheet (120), wherein the tube sheet (120) forms a part of the inlet chamber (130) and / or the outlet chamber (140), wherein the shell (150) comprises the shell inlet (152) and the shell outlet (154) and encloses the plurality of tubes (110), establishing a fluid path for a second fluid (b), wherein the shell (150) comprises a first shell part (150.1) and a second shell part (150.2), wherein the first shell part (150.1) is arranged at the tube sheet (120) and comprises a first flange (156.1) at a side remote from the tube sheet (120), wherein the second shell part (150.2) comprises a second flange (156.2), and wherein the second shell part (150.2) is mounted, via its second flange (156.2), to the first shell part (150.1), at its first flange (156.1).

Description

[0001] The present invention relates to a shell and tube heat exchanger, e.g., a U tube shell and tube heat exchanger, to a method of heating a fluid, using such shell and tube heat exchanger, and to a method of manufacturing such shell and tube heat exchanger.Background

[0002] In a wide variety of applications, fluids are cooled or heated. In gas generation plants, for example, the gases often reach very high temperatures that are too high for further use, so they have to be cooled down. Likewise, in various applications, cooling of gases or gas mixtures may be necessary to reduce subsequent compression work. Cold fluids or even cryogenic fluids, e.g., liquid natural gas (LNG), often have to be heated or vaporized for further use.

[0003] A common technique for cooling or heating fluids is the use of heat exchangers, in particular, so-called shell and tube heat exchangers. Shell and tube heat exchangers generally have a plurality of tubes, usually of very small diameter, which are enclosed by a shell. A fluid to be cooled or heated can be passed through the tubes (i.e., in tube-side channels), and the cooling or heating fluid can be passed through the shell.

[0004] Further, such shell and tube heat exchangers typically comprise a tube sheet to which the tubes are connected, such that the tubes can be held in place. In such shell and tube heat exchangers, the shell typically is mounted to the tube sheet via a flange of the shell. This, for example, does not only allow easy manufacturing but also removing the tubes from the shell.

[0005] Depending on the temperature changes in the fluids, temperature variations can occur which lead the deformations and leakage at the flange. It is therefore an object of the present invention to provide an improved shell and tube heat exchanger.Disclosure of the invention

[0006] This object is achieved by providing a shell and tube heat exchanger, a method of heating fluid, and method of manufacturing such a shell and tube heat exchanger with the features of the independent claims. Embodiments of the invention are the subject of the dependent claims and of the description that follows.

[0007] The invention relates to shell and tube heat exchangers and using them to heat fluids. A particular use is using a shell and tube heat exchanger as vaporizer to vaporize cryogenic fluids like liquid natural gas (LNG).

[0008] The shell and tube heat exchanger comprises a plurality of tubes, a tube sheet, a shell, an inlet chamber, an outlet chamber, a shell inlet and a shell outlet. The inlet chamber is connected, via the plurality of tubes, to the outlet chamber. In this way, a fluid path for a first fluid is established. The first fluid can be fed into the inlet chamber (via a respective inlet, e.g., a valve), then the first fluid is routed through the plurality of tubes and then reaches the outlet chamber. From the outlet chamber, the first fluid can be withdrawn (via a respective outlet, e.g., a valve).

[0009] The plurality of tubes is connected (or mounted) to the tube sheet. For example, the tube sheet (typically, a disc) can comprise holes into which the tubes are mounted. Such tube sheet allows holding the tubes in place. The tube sheet forms a part of the inlet chamber and / or the outlet chamber.

[0010] In an embodiment, the shell and tube heat exchanger is configured as a U tube shell and tube heat exchanger. In this case, the tube sheet forms a part of the inlet chamber and the outlet chamber. In other words, the inlet chamber and the outlet chamber are both arranged at the same side, e.g., next to each other. The tubes are then mounted with both ends to the tube sheet; this requires the tubes making a U-turn.

[0011] The shell comprises the shell inlet (e.g., a valve) and the shell outlet (e.g., a valve), and encloses the plurality of tubes. In this way a fluid path for a second fluid is established. The second fluid can be fed into the shell via the shell inlet, then the second fluid is routed through the shell (i.e., the inside of the shell), passing the tubes, and then reaches the shell outlet, such that the second fluid can be withdrawn. In this way, heat between the first fluid and the second fluid (when both are routed through their respective path) can be exchanged.

[0012] For vaporizing a cryogenic fluid, for example, the cryogenic fluid is used as the first fluid, i.e., routed through the tubes. Water or glycol water or a steam thereof, for example, can be used as the second fluid, i.e., being routed through the shell. In the shell, baffles or other barriers can be place in order to generate a desired path for the second fluid.

[0013] The shell comprises a first shell part and a second shell part. The first shell part is arranged at the tube sheet and comprises a first flange at a side remote from the tube sheet. The first shell part can be fixedly connected to the tube sheet, e.g., via welding or the like. Alternatively, the first shell part and the tube sheet can be made of a single piece. In any case, the first flange is spaced apart from the tube sheet.

[0014] The second shell part comprises a second flange, and the second shell part is mounted, via its second flange, to the first shell part, at its first flange. The tube heat exchanger can comprise a gasket, which is arranged between the first flange and the second flange. Such gasket, e.g., made of copper, helps providing a tight connection. The second shell part can be mounted, via its second flange, to the first shell part, at its first flange, releasably, e.g., by means of fixing means like clamps or screws or the like. In this way, the tubes can be removed from the shell or the second shell part, respectively.

[0015] In this way, the actual connecting region (where the gasket is, i.e., between the two flanges) is spaced apart from the tube sheet. If, in case of temperature variations of the tube sheet, the influence of deformations resulting from that, will have less to no influence to the actual connecting region. This is in contrast to where the shell is mounted, via a flange, directly to the tube sheet (where the tube sheet is used as flange, for example). Leakage can thus be prevented or, at least reduced.

[0016] Further advantages and embodiments of the invention will be apparent from the description and the accompanying drawing. The invention is illustrated schematically by means of embodiments in the drawing and is described below with reference to the drawing.

[0017] Short description of the figures Fig. 1illustrates a shell and tube heat exchanger according to an embodiment of the invention; Figs. 2a, 2billustrate a part of the shell and tube heat exchanger of Fig. 1 in different situations; Fig. 3illustrates part of another shell and tube heat exchanger; and Fig. 4illustrates a shell and tube heat exchanger according to another embodiment of the invention.

[0018] Detailed description of the figures

[0019] Fig. 1 schematically illustrates a shell and tube heat exchanger 100 according to an embodiment of the invention. The shell and tube heat exchanger 100 comprises a plurality of tubes 110, a tube sheet 120, a shell 150, an inlet chamber 130, an outlet chamber 140, a shell inlet 152 and a shell outlet 154.

[0020] The inlet chamber 130 is connected, via the plurality of tubes 110, to the outlet chamber 140. In this way, a fluid path for a first fluid a is established. The first fluid a can be fed into the inlet chamber 130, via a respective inlet 134, e.g., a valve; then the first fluid a is routed through the plurality of tubes 110 and then reaches the outlet chamber 140. From the outlet chamber 140r, the first fluid a can be withdrawn via a respective outlet 142, e.g., a valve. The mentioned fluid path for the first fluid a is indicated with a dotted line between the solid lines with arrows for the first fluid a.

[0021] The plurality of tubes 110 is connected (or mounted) to the tube sheet 120. For example, the tube sheet 120 has the form of disc and comprises holes into which the tubes 110 are mounted. Such tube sheet 110 allows holding the tubes in place. The tube sheet 110 forms a part of the inlet chamber 130 and the outlet chamber 140.

[0022] In the example of Fig. 1, the shell and tube heat exchanger 100 is configured as a U tube shell and tube heat exchanger. In this case, the inlet chamber 130 and the outlet chamber 140 are both arranged at the same side (in Fig. 1, the left side) and next to each other. The tubes are mounted with both ends each to the tube sheet 120; this requires the tubes making a U-turn as can be seen in the right side of Fig. 1. The outlet chamber 140 can, for example, be a cylindric tube or pipe with a rounded cover (at the let side in Fig. 1), whereby the inlet chamber 130 is formed inside this cylindric tube, using a separating sheet or plate.

[0023] It is noted that only three tubes 110 are shown in Fig. 1, for illustrating purposes. Typical shell and tube heat exchangers can have, e.g., between 10 and several thousands of such tubes. Further note that the view shown in Fig. 1 is a sectional view.

[0024] The shell 150 comprises the shell inlet 152, e.g., a valve, and the shell outlet 154, e.g., a valve, and encloses the plurality of tubes 110. In this way a fluid path for a second fluid b bis established. The second fluid can be fed into the shell 150 via the shell inlet 152, then the second fluid is routed through the shell (i.e., the inside of the shell), passing the tubes 110, and then reaches the shell outlet 154, such that the second fluid b can be withdrawn. The mentioned fluid path for the second fluid b is indicated with a dotted line between the solid lines with arrows for the second fluid b.

[0025] In this way, heat between the first fluid a and the second fluid b, when both are routed through their respective path, can be exchanged. A preferred use of the shell and tube heat exchanger 100 is for vaporizing a cryogenic fluid like liquid natural gas (LNG). IN this case, the cryogenic fluid is used as the first fluid a, and a heating fluid like glycol water or steam is used as the second fluid b.

[0026] The shell 150 comprises a first shell part 150.1 and a second shell part 150.2. The first shell part 150.1 is arranged at the tube sheet 120 and comprises a first flange 156.1 at a side remote from the tube sheet 120 (at the right side, in Fig. 1). The first shell part 150.1 can be fixedly connected to the tube sheet 120, e.g., via welding or the like. Alternatively, the first shell part 150.1 and the tube 120 sheet can be made of a single piece. In any case, the first flange 156.1 is spaced apart from the tube sheet 120.

[0027] The second shell p150.2 art comprises a second flange 156.2, and the second shell part 150.2 is mounted, via its second flange 1562, to the first shell part 150.1, at its first flange 156.1.

[0028] This is illustrated in more detail in Figs. 2a and 2b. Fig. 2a illustrates the tube sheet 120 (or part of it) and the first shell part 150.1 comprising the first flange 156.1 on the left side. The second shell part 150.2 (or part of it) comprising the second flange 156.2 is illustrated on the right side. For illustrating purposes, the first flange 156.1 and the second flange 156.2 are separated from each other, like when the tube sheet 120 (with the tubes mounted to it) are removed from the second shell part 150.2.

[0029] However, the distance between the first flange 156.1 and the tube sheet 120 is clearly visible.

[0030] Fig. 2b illustrates the components of Fig. 2a being mounted to one another. The first flange 156.1 and the second flange 156.2 are arranged next to each other. In addition, a (separate) gasket can be arranged between these two flanges. Also, the surfaces of the two flanges, which surfaces face each other, can be configured such that when mounted to one another, a tight seal is formed. In addition, a clamping means 260 for holding or fixing the two flanges to another is illustrated. Several of such clamping means can be used; also, other types of fixing means like screws could be used (then, e.g., having threads and / or holes in the flanges)

[0031] When the shell and tube heat exchanger 100 is used for vaporizing a cryogenic fluid, for example, there will occur a temperature variation along the tube sheet. The cryogenic fluid at low temperature of, e.g., -160°C or lower, enters the inlet chamber 130 and then the tubes 110 connected to the tube sheet where the tube sheet forms part of the inlet chamber. This is the lower part of the tube sheet 120 in Fig. 1 (note that this can, for example, be the lower half of the disc-shaped tube sheet; Fig. 1 shows a sectional view).

[0032] After the fluid has been routed through the tubes and, thus, having been heated or vaporized, the fluid leaves the tubes at a high temperature of, e.g., 0°C or similar, and enters the outlet chamber 140. This is the upper part of the tube sheet 120 in Fig. 1 (note that this can, for example, be the upper half of the disc-shaped tube sheet). Thus, a strong temperature variation from the top of the tube sheet to the bottom (when seen in Fig. 1) occurs.

[0033] In addition, the heating fluid provided inside the shell 150, typically, has a very high temperature of, e.g., 150°C or the like. Whereas the temperature variation mentioned above is valid for the side of the inlet and outlet chamber (left side in Fig. 1) of the tube sheet, there will be a high temperature at the shell side (right side in Fig. 1) of the tube sheet. This in turn, results in a strong temperature variation through the tube sheet (from the left to the right side in Fig. 1).

[0034] The mentioned temperature variations, in turn, result in deformations of the tube sheet. In that the mounting region, i.e., the first flange 156.1, is spaced apart from the tube sheet, such deformation will have no to less effect at the first flange.

[0035] For illustration purposes, Fig. 3 shows a tube sheet 320 and a flange 356 of a shell where the tube sheet 320 itself is used as flange mounted with the flange 356. The interface region between the tube sheet 320 and the flange 356 would be subject to such deformation

[0036] Fig. 4 illustrates a shell and tube heat exchanger according to another embodiment of the invention, by means of a simulation. A tube sheet 420, an inlet chamber 430, an outlet chamber 440 and a first flange part 450.1 are shown. In the simulation, a temperature variation as mentioned above has been simulated and resulting deformation of the components has been applied. Note that the deformation is strongly exaggerated for illustration purposes.

[0037] In line with the above mentioned temperature variations, the lower part of the tube sheet 420 is strongly deformed whereas the upper part is still deformed, although less. The first flange part 450.1, however, is deformed only very close to the tube sheet 420. Spaced apart, however, where the first flange will then be arranged, there will be no to very low deformation.

Claims

1. A shell and tube heat exchanger (100), comprising a plurality of tubes (110), a tube sheet (120), a shell (150), an inlet chamber (130), an outlet chamber (140), a shell inlet (152) and a shell outlet (152), wherein the inlet chamber (130) is connected, via the plurality of tubes (110), to the outlet chamber (140), establishing a fluid path for a first fluid (a), wherein the plurality of tubes (110) is connected to the tube sheet (120), wherein the tube sheet (120) forms a part of the inlet chamber (130) and / or the outlet chamber (140), wherein the shell (150) comprises the shell inlet (152) and the shell outlet (154) and encloses the plurality of tubes (110), establishing a fluid path for a second fluid (b), wherein the shell (150) comprises a first shell part (150.1) and a second shell part (150.2), wherein the first shell part (150.1) is arranged at the tube sheet (120) and comprises a first flange (156.1) at a side remote from the tube sheet (120), wherein the second shell part (150.2) comprises a second flange (156.2), and wherein the second shell part (150.2) is mounted, via its second flange (156.2), to the first shell part (150.1), at its first flange (156.1).

2. The shell and tube heat exchanger (100) of claim 1, configured as a U tube shell and tube heat exchanger, wherein the tube sheet (120) forms a part of the inlet chamber (130) and the outlet chamber (130).

3. The shell and tube heat exchanger (100) of claim 1 or 2, wherein the second shell part (150.2) is mounted, via its second flange, to the first shell part (150.2), at its first flange, releasably, preferably, by means of fixing means (260).

4. The shell and tube heat exchanger (100) of any one of the preceding claims, further comprising a gasket, wherein the gasket is arranged between the first flange and the second flange.

5. The shell and tube heat exchanger (100) of any one of the preceding claims, wherein the first shell part (150.1) is fixedly connected to the tube sheet (120), or wherein the first shell part and the tube sheet are made of a single piece.

6. The shell and tube heat exchanger (100) of any one of the preceding claims, configured as a vaporizer for cryogenic fluid.

7. A method of heating a fluid, using the shell and tube heat exchanger (100) of any one of the preceding claims, wherein the fluid is provided to the inlet chamber (130) as the first fluid (a), and wherein a heating fluid is provided to the shell inlet (152) as the second fluid (b).

8. The method of claim 7, wherein heating the fluid comprises vaporizing the fluid.

9. The method of claim 8, wherein the fluid is a cryogenic fluid, preferably, natural gas.

10. A method for manufacturing a shell and tube heat exchanger (100), said shell and tube heat exchanger (100) comprising a plurality of tubes (110), a tube sheet (120), a shell (150), an inlet chamber (130), an outlet chamber (140), a shell inlet (152) and a shell outlet (154), wherein the inlet chamber (130) is connected, via the plurality of tubes (110), to the outlet chamber (140), establishing a fluid path for a first fluid (a), wherein the plurality of tubes (110) is connected to the tube sheet (120), wherein the tube sheet (120) forms a part of the inlet chamber (130) and / or the outlet chamber (140), wherein the shell (150) comprises the shell inlet (152) and the shell outlet (154) and encloses the plurality of tubes (110), establishing a fluid path for a second fluid (b), comprising: Providing the shell (150) with a first shell part (150.1) and a second shell part (150.2), wherein the first shell part is arranged at the tube sheet and comprises a first flange at a side remote from the tube sheet, wherein the second shell part comprises a second flange, and Mounting the second shell part (150.2), via its second flange, to the first shell part (150.1), at its first flange.

11. The method of claim 10, wherein said shell and tube heat exchanger (100) is configured as a U tube shell and tube heat exchanger, wherein the tube sheet forms a part of the tube-sided inlet chamber and the tube-sided outlet chamber.

12. The method of claim 10 or 11, manufacturing the shell and tube heat exchanger (100) of any one of claims 1 to 6.

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