Double-tube heat exchanger, manufacturing method, use, and hydrogen station

Abstract

The present invention relates to a double-tube heat exchanger for heating cryogenic fluids, particularly cryogenic hydrogen, having an outer tube and an inner tube disposed within the outer tube, wherein the inner tube is configured for the passage of the cryogenic fluid, and the intermediate space between the inner tube and the outer tube is configured for the passage of a heat exchange medium, and the double-tube heat exchanger further has an intermediate component (240), the intermediate component surrounds the inner tube and is disposed in the intermediate space, and the intermediate component (240) has a longitudinal axis (L) and a minimum The intermediate component (240) has a substantially cylindrical base (242) with a through opening (246) along its longitudinal axis (L), through which an inner tube is guided, and the intermediate component (240) has fins (244) on the outer surface of the base (242) that extend at least substantially parallel to the longitudinal axis (L) and are oriented radially with respect to the longitudinal axis (L), and the intermediate component (240) is clamped to the inner tube.

Description

[Technical Field]

[0001] The present invention relates to a double-pipe heat exchanger for heating cryogenic fluids, in particular cryogenic hydrogen, a method for manufacturing such a double-pipe heat exchanger, the use of such a double-pipe heat exchanger, and a hydrogen station equipped with such a double-pipe heat exchanger.

[0002] In applications or devices where cryogenic fluids such as hydrogen are used, it is frequently necessary to heat the cryogenic fluid. One example thereof is a hydrogen station, in which hydrogen is present for the time being in a liquid state, for example at about -253°C, and needs to be heated before being filled into vehicles.

[0003] For heating fluids, a heat exchanger (or heat transmitter) can generally be used. One type of heat exchanger is the so-called double-pipe heat exchanger, in which an inner pipe is surrounded by an outer pipe. The fluid to be heated can be guided, for example, in the inner pipe, whereas the heat exchange medium can be guided in the intermediate space between the inner pipe and the outer pipe.

[0004] However, various problems arise when double-pipe heat exchangers are used in cryogenic applications, especially cryogenic high-pressure applications. Due to the high pressure (PN1000, i.e., up to 1000 bar at room temperature), the wall thickness of the inner pipe (in which hydrogen is guided, for example) has to be very large, which results in high thermal resistance and increased requirements for the product as well as increased costs when manufacturing and connecting pipes, especially welded seams. Due to the extremely low temperature in the inner pipe (down to -253°C for cryogenic hydrogen), the gaseous or liquid heat transfer fluid in the annular region (intermediate space) of the double pipe freezes severely.

[0005] This can or frequently does result in clogging of the pipes, increased pressure loss, and reduced heat transfer between the media.

[0006] Another type of heat exchanger is the so-called medium-air heat exchanger, or more specifically, the hydrogen-air heat exchanger. However, various problems can arise with this type of heat exchanger as well. Due to its low heat transfer coefficient, very large dimensions are usually not permissible, for example, in applications such as hydrogen refueling stations. Due to freezing, continuous operation is usually impossible, so redundant heat exchangers are used for reheating. Similarly, steam clouds in the heat exchanger are usually unacceptable, for example, in applications such as hydrogen refueling stations. Furthermore, if the hydrogen temperature is low, a considerable amount of energy may be lost in the air and become unavailable in the processes of the station connected downstream, which increases electricity costs and, consequently, reduces the overall efficiency of the hydrogen refueling station.

[0007] Given this background, the challenge is to heat cryogenic fluids, particularly cryogenic hydrogen, in the most cost-effective and energy-efficient way possible.

[0008] Disclosure of the invention This problem is solved by a double-tube heat exchanger having the features of the independent claim, a method for manufacturing a double-tube heat exchanger, the use of a double-tube heat exchanger, and a hydrogen station. Preferred configurations are the subject of the dependent claims and the following description.

[0009] Advantages of the invention This invention addresses the heating of cryogenic fluids, particularly cryogenic hydrogen, using a heat exchanger, and specifically addresses the applications of heat exchangers in hydrogen refueling stations.

[0010] The present invention relates in one embodiment to a double-tube heat exchanger for heating cryogenic fluids, particularly cryogenic hydrogen. The double-tube heat exchanger has an outer tube and an inner tube located inside the outer tube. Typically, the inner tube is arranged concentrically within the outer tube. The inner tube is configured for the flow of the cryogenic fluid, while the intermediate space between the inner and outer tubes is configured for the flow of a heat exchange medium.

[0011] As is common for double-tube heat exchangers, a double-tube heat exchanger may have an inlet opening for a cryogenic fluid connected to the inner tube, and an outlet opening for a cryogenic fluid also connected to the inner tube. Furthermore, a double-tube heat exchanger may have an inlet opening for a heat exchange medium connected to an intermediate space, and an outlet opening for a heat exchange medium also connected to an intermediate space.

[0012] Furthermore, the double-tube heat exchanger has an intermediate component (or so-called internal component) that surrounds the inner tube and is located in the intermediate space. The intermediate component has a base that is at least substantially cylindrical with a longitudinal axis, the base having a through-opening along the longitudinal axis, through which the inner tube is guided. On the outer surface of the base, the intermediate component has fins (or ribs) that extend at least substantially parallel to the longitudinal axis (of the base) and are oriented radially with respect to the longitudinal axis. Furthermore, the intermediate component is clamped to the inner tube.

[0013] The intermediate component enables efficient heat transfer between the cryogenic fluid to be heated and the heat exchange medium, thus enabling efficient and low-cost heating of cryogenic fluids using a double-tube heat exchanger. Because the intermediate component is clamped to the inner tube and not welded, the double-tube heat exchanger can also be used to heat cryogenic fluids at high pressures, such as 500 bar or more, or 900 bar or more (all calculated at room temperature). That is, the double-tube heat exchanger, or at least the inner tube, can be designed for PN500, PN900, or PN1000 (pressure resistance of 500 bar, 900 bar, or 1000 bar at room temperature, respectively). The clamp ensures a secure and good thermal bond between the inner tube and the intermediate component.

[0014] The fins or ribs on the intermediate components allow for more efficient heat transfer while simultaneously enabling a smaller design. For example, the number of fins can be selected depending on the situation or application, and according to the required or desired heat transfer.

[0015] It is preferable when the fins are integrally formed with the substrate. This allows for a stable and robust intermediate component and efficient and good heat transfer between the fins and the substrate. Special steel is particularly well suited as the material for the fins and / or substrate. That is, the fins and / or substrate can have special steel, or even be manufactured from special steel. Special steel allows for sufficiently simple processing, has sufficiently good thermal conductivity and heat capacity, and is also suitable for cryogenic temperatures down to -253°C.

[0016] In one embodiment, the base has a gap that extends at least substantially parallel to the longitudinal axis and is oriented radially with respect to the longitudinal axis, the gap extending radially through the base from the through-opening outward. Thus, the outer surface of the base is not a perfect cylinder, and the base has a C-shaped cross-section. This allows, on the one hand, to easily introduce the inner tube into the through-opening, and on the other hand, to subsequently clamp the base or intermediate component tightly to the inner tube. In particular, the intermediate component has one or more clamping means, especially bolts, for clamping the base in the gap region, so that the intermediate component is clamped to the inner tube. For this purpose, the base may have, for example, one or more through-holes for the clamping means or bolts, the one or more through-holes extending beyond the gap. Thus, in the case of bolts, the gap can be reduced during clamping, thereby ensuring that the base is securely clamped to the inner tube.

[0017] In one embodiment, the substrate further has another gap extending at least substantially parallel to the longitudinal axis and oriented radially with respect to the longitudinal axis, the other gap extending radially outward from the through-opening through only a portion of the substrate. This other gap is oriented at least substantially parallel to the (previous) gap. This allows for easier and better clamping of intermediate components or the substrate in the inner tube and improves heat transfer even when the pressure of the cryogenic fluid in the inner tube is high.

[0018] In one embodiment, the ratio of the diameter of the substrate to the diameter of the through-opening is between 1.5 and 10, particularly between 2 and 5, in the direction perpendicular to the longitudinal axis. In one embodiment, the ratio of the diameter of the intermediate components, including the fins, to the diameter of the substrate is between 1.1 and 2, particularly between 1.1 and 1.5, in the direction perpendicular to the longitudinal axis. The specific values ​​to be selected for these ratios (especially the first ratio), i.e., the thickness of the substrate, can be made to depend on the required thermal resistance to prevent freezing. The number and dimensions (i.e., the second ratio) of fins or ribs can be made to depend on the required heating area. However, even with the aforementioned values ​​of the ratios, good efficiency can be achieved, even at high pressures, particularly for cryogenic fluids such as hydrogen, where heating is important.

[0019] Tubes with longitudinal ribs are typically used in applications involving viscous liquids. Fins were added to achieve a smaller design. The internal components are clamped, allowing for use in high-pressure systems.

[0020] The proposed design allows for the freezing of the heat exchange medium, so that fluids such as potassium formate and / or glycol can be used as the heat exchange medium, which makes the heating process using a double-tube heat exchanger safer compared to systems that use oil as the heat exchange medium, for example.

[0021] This type of heat exchange medium can be used to heat cryogenic fluids. As soon as the heat exchange medium cools, it can be stored and used in another process stage, for example, to cool hydrogen at another location, for example, to cool hydrogen at another part of a hydrogen station. This improves the overall efficiency of the system, i.e., the overall efficiency of the hydrogen station.

[0022] The present invention is schematically illustrated in the drawings based on embodiments, and will be described below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] [Figure 1] It is a schematic diagram of a double-pipe heat exchanger according to the present invention in one preferred embodiment. [Figure 2a] It is a schematic diagram of a part of a double-pipe heat exchanger according to the present invention in another preferred embodiment. [Figure 2b] It is a schematic diagram showing a part of the double-pipe heat exchanger according to the present invention shown in Fig. 2a from another perspective. [Figure 3] It is a schematic diagram of a hydrogen station according to the present invention in one preferred embodiment. DESCRIPTION OF EMBODIMENTS

[0024] Fig. 1 schematically shows, in a cross-sectional view, a double-pipe heat exchanger 100 according to the present invention in one preferred embodiment, which can be used for heating a cryogenic fluid a supplied to the double-pipe heat exchanger 100, for example, cryogenic hydrogen. Here, the basic principle of the double-pipe heat exchanger 100 corresponds to that of a conventional double-pipe heat exchanger.

[0025] The double-pipe heat exchanger 100 has an inner pipe 110 in which the cryogenic fluid a to be heated is guided or introduced. For this purpose, the cryogenic fluid a is supplied via an inlet opening 112, guided through the inner pipe 110 to an outlet opening 114, and flows out of the double-pipe heat exchanger 100 through the outlet opening 114. Each of the inlet opening 112 and the outlet opening 114 may, for example, be formed as a flange or formed as a part of a flange.

[0026] The double-pipe heat exchanger 100 further comprises an outer tube 120, and the inner tube 110 is arranged inside the outer tube 120, particularly in a concentric arrangement. Illustratively, a longitudinal axis L is shown, with respect to which the inner tube 110 and the outer tube 120 are arranged concentrically. The outer tube 120 may, for example, have flanges 126 and 128 at each end respectively, through which the inner tube 110 is guided.

[0027] An intermediate space 130 between the inner tube 110 and the outer tube 120 is configured for the flow of heat exchange medium b. For this purpose, the outer tube 120 may have an inlet opening 122 that allows the heat exchange medium b to be introduced into the intermediate space 130, and an outlet opening 124 that allows the heat exchange medium b to be discharged from the intermediate space 130 again. By way of example, the inlet opening 122 and the outlet opening 124 are arranged radially (with reference to the longitudinal axis L), and similarly, the inlet opening 122 and / or the outlet opening 124 may each be arranged on one of the flanges 126 and 128, and thus may particularly also be arranged in the longitudinal direction.

[0028] An intermediate component 140 is arranged in the intermediate space 130. The intermediate component 140 surrounds the inner tube 110 and has at least a substantially cylindrical base body, the base body being provided with a longitudinal axis that can correspond to the longitudinal axis L of the double-pipe heat exchanger 100.

[0029] The double-pipe heat exchanger 100 illustrated herein is merely used to exemplify the description of the present invention. That is, the double-pipe heat exchanger may have other configurations. For example, a plurality of separate outer tubes may be provided, the plurality of outer tubes being spaced apart from each other and surrounding one inner tube, in this case one relatively long inner tube, thereby forming a plurality of intermediate spaces, and one intermediate member may be arranged in each of the plurality of intermediate spaces. In this case, the heat exchange medium b can be guided, for example, from one intermediate space to a subsequent intermediate space. The relatively long inner tube can be bent multiple times, but the portion surrounded by the outer tube should be straight.

[0030] Figures 2a and 2b show a portion of a double-tube heat exchanger according to the present invention in one other preferred embodiment, particularly an intermediate component 240. The intermediate component 240 can, in particular, correspond to the intermediate component 140 shown in Figure 1. Figure 2a shows a cross-sectional view perpendicular to the longitudinal axis L, and Figure 2b shows a perspective view.

[0031] The intermediate component 240 has a base body 242, which has a through-opening 246, for example, a hole, along the longitudinal axis L, as shown in Figure 1, through which the inner tube is guided. Furthermore, the intermediate component 240 has fins 244 on the outer surface of the base body 242 that extend at least substantially parallel to the longitudinal axis L and are oriented radially with respect to the longitudinal axis. The fins 244 can be arranged, for example, evenly distributed on the circumferential surface. The thickness or width b of the fins 244 in the circumferential direction can be selected as needed.

[0032] The number of fins 244 is shown here exemplarily as 24, but can be similarly selected as needed. The fins can be formed integrally with the base. For this purpose, fins can be formed from a complete cylinder, for example, by machining a suitable area. However, it is also conceivable to attach the fins to the base, for example, by welding.

[0033] Furthermore, the base body 242 has a gap 248 that extends at least substantially parallel to the longitudinal axis L and is oriented radially with respect to the longitudinal axis L, and this gap 248 extends radially outward through the through-opening 246 and through the base body 242. Exemplarily, the base body 242 has another gap 248 that extends at least substantially parallel to the longitudinal axis L and is oriented radially with respect to the longitudinal axis L, and this other gap extends radially outward from the through-opening 242 through only a portion of the thickness of the base body, for example, up to half the thickness, and is oriented at least substantially parallel to the gap 248. Another gap 250 can be considered, for example, an extension of gap 248.

[0034] When manufacturing the intermediate component, the through-opening 246 can be created, for example, as a hole in the base 242, and the gap 248 and another gap 250 can be introduced into the base 242, for example, by providing grooves in the radial direction.

[0035] Furthermore, the base 242 has, exemplarily, three through holes 252 for bolts 260 to be used as clamping means. The through holes 252 extend beyond the gap 248, as can be seen particularly in Figure 2a. The bolts 260 can be inserted into each through hole 252 and tightened after the inner tube is inserted into the through hole 246 to clamp the base 242 or intermediate part 240 to the inner tube. In this case, for example, the bolts can be used with nuts, and similarly, it is conceivable that some of the through holes have corresponding threads.

[0036] Similarly, as can be seen in Figures 2a and 2b, in the region of the through hole, the base body 242 can be appropriately shaped, for example, by forming appropriate recesses so that bolts or, generally, clamping means can be attached or introduced in an appropriate manner. Exemplary, such a recess 254 is shown in Figure 2a.

[0037] Figure 2a shows the diameter d1 of the through-opening 246, the diameter d2 of the base 242, and the diameter d3 of the intermediate component 240 including the fins 244. Here, the ratio of d2 to d1 may be, for example, between 1.5 and 10, particularly between 2 and 5. The ratio of d3 to d2 may be, for example, between 1.1 and 2, particularly between 1.1 and 1.5. However, as mentioned above, specific values ​​can be selected according to the demand and desired heat transfer.

[0038] Similarly, the length of the intermediate component along the longitudinal axis L can be selected according to the demand; however, a length slightly shorter than the intermediate space 130 (see Figure 1) formed by the outer tube is considered preferable.

[0039] The apparatus 100 according to the present invention is shown as one preferred embodiment, and the method according to the present invention can also be carried out using this apparatus 100. This is a simplified method scheme. Herein, in particular, a specific example of the apparatus 100 formed as a hydrogen station is shown together with an ion compressor as a compressor 130 and a filling system 140. Although only one vehicle 150 is shown exemplary, the apparatus 100 can be used to fill multiple vehicles with hydrogen simultaneously.

[0040] Figure 3 schematically shows a hydrogen station 300 according to the present invention in one preferred embodiment. The hydrogen station 300 exemplary includes a storage system 310 for cryogenic hydrogen and a dispenser or supply device 330 to which a vehicle 340 can be connected. Cryogenic hydrogen a is delivered from the storage system 310 to the dispenser 330 and from there to the vehicle 340 or a tank in the vehicle 340.

[0041] Typically, heating of cryogenic hydrogen a is required here, and for this purpose, the hydrogen station 300 may have, for example, a double-tube heat exchanger 320 through which cryogenic hydrogen a is guided in order to heat the cryogenic hydrogen a. An example of the double-tube heat exchanger 320 is the double-tube heat exchanger shown in Figure 1. This enables efficient and low-cost operation of the hydrogen station 300.

Claims

1. In a double-tube heat exchanger (100, 320) for heating a cryogenic fluid (a), particularly cryogenic hydrogen, having an outer tube (120) and an inner tube (110) disposed within the outer tube (120), The inner tube (110) is configured for the passage of the cryogenic fluid (a), and the intermediate space (130) between the inner tube (110) and the outer tube (120) is configured for the passage of the heat exchange medium (b). The double-tube type heat exchanger (100) further comprises intermediate components (140, 240), the intermediate components (140, 240) surrounding the inner tube (110) and arranged in the intermediate space (130), The intermediate parts (140, 240) have a base (242) that is at least substantially cylindrical and has a longitudinal axis (L), The base (242) has a through opening (246) along the longitudinal axis (L), and the inner tube (110) is guided through the through opening (246). The intermediate parts (140, 240) have fins (244) on the outer surface of the base body (242) that extend at least substantially parallel to the longitudinal axis (L) and are oriented radially with respect to the longitudinal axis (L). A double-tube type heat exchanger (100, 320) characterized in that the intermediate parts (140, 240) are clamped to the inner tube (110).

2. The double-tube heat exchanger (100, 320) according to claim 1, wherein the base body (242) has a gap (248) that extends at least substantially parallel to the longitudinal axis and is oriented radially with respect to the longitudinal axis, and the gap (248) extends radially through the base body from the through-opening toward the outside.

3. The double-tube type heat exchanger (100, 320) according to claim 2, characterized in that the intermediate parts (140, 240) have one or more clamping means (260), particularly bolts, and the intermediate parts are clamped to the inner tube by the base being clamped in the gap region using the clamping means (260).

4. The double-tube heat exchanger (100, 320) according to claim 3, characterized in that the base (242) has one or more through holes (252) for the clamping means, and the one or more through holes extend beyond the gap.

5. The double-tube heat exchanger (100, 320) according to any one of claims 2 to 4, wherein the base body (242) has another gap (250) that extends at least substantially parallel to the longitudinal axis and is oriented radially with respect to the longitudinal axis, and the other gap (250) extends radially outward from the through-opening through only a portion of the base body and is oriented at least substantially parallel to the gap.

6. The double-tube type heat exchanger (100, 320) according to any one of claims 1 to 5, characterized in that the fin (244) is integrally formed with the base (242).

7. The double-tube heat exchanger (100, 320) according to any one of claims 1 to 6, characterized in that the ratio of the diameter (d2) of the base body to the diameter (d1) of the through-opening is between 1.5 and 10, particularly between 2 and 5, in a direction perpendicular to the longitudinal axis.

8. The double-tube heat exchanger (100, 320) according to any one of claims 1 to 7, wherein the ratio of the diameter (d3) of the intermediate component including the fins to the diameter (d2) of the base is between 1.1 and 2, particularly between 1.1 and 1.5, in a direction perpendicular to the longitudinal axis.

9. The double-tube heat exchanger (100, 320) according to any one of claims 1 to 8, characterized in that the inner tube (110) is designed for at least PN500, and more particularly for at least PN900.

10. The double-tube heat exchanger (100) according to any one of claims 1 to 9, characterized in that the fins and / or the base body are made of special steel, and in particular are manufactured from special steel.

11. A method for manufacturing a double-tube heat exchanger (100, 320) for heating a cryogenic fluid (a), particularly cryogenic hydrogen, having an outer tube (120) and an inner tube (110) disposed within the outer tube (120), The inner tube (110) is provided for the passage of the cryogenic fluid, and the intermediate space (130) between the inner tube (110) and the outer tube (120) is provided for the passage of the heat exchange medium (b). Intermediate components (140, 240) are provided that surround the inner tube and are positioned within the intermediate space. The aforementioned intermediate parts (140, 240) have a base that is at least substantially tubular and has a longitudinal axis, The base has a through-opening along the longitudinal axis, and the inner tube is guided through the through-opening. The intermediate component has fins on the outer surface of the base body that extend at least substantially parallel to the longitudinal axis and are oriented radially with respect to the longitudinal axis. A method characterized in that the intermediate component is clamped to the inner tube.

12. The method according to claim 11 for manufacturing a double-tube heat exchanger (100, 320) according to any one of claims 1 to 10.

13. Use of a double-tube heat exchanger (100, 320) according to any one of claims 1 to 10 for or in a hydrogen station.

14. A hydrogen station (300) for filling a vehicle (340) with hydrogen (a), having a double-tube heat exchanger (100, 320) according to any one of claims 1 to 10 for heating hydrogen.

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