Heat exchanger

Abstract

To reduce thermal stress generated due to freezing of working fluid in some part of a plurality of laminated type heat exchange sections when the freezing occurs.SOLUTION: A heat exchanger 1 includes: high-temperature supply main piping 40 in which high-temperature fluid to be supplied to each diffusion joining type laminated type heat exchange section 11 flows; high-temperature discharge main piping 50 in which the high-temperature fluid to be discharged from each laminated type heat exchange section 11 flows; low-temperature supply main piping 20 in which low-temperature fluid to be supplied to each laminated type heat exchange section 11 flows; low-temperature discharge main piping 30 in which the low-temperature fluid to be discharged from each laminated type heat exchange section 11 flows; a plurality of first connection pipes 41 for connecting the high-temperature supply main piping 50 and each high-temperature side supply header 14; a plurality of second connection pipes 51 for connecting the high-temperature discharge main piping 50 and each high-temperature side discharge header 15; a plurality of third connection pipes 21 for connecting the low-temperature supply main piping 20 and each low-temperature side supply header 12; and a plurality of fourth connection pipes 31 for connecting the low-temperature discharge main piping 30 and each low-temperature side discharge header 13.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heat exchanger. [Background technology]

[0002] Conventionally, a heat exchanger equipped with a laminated heat exchange section has been known (see, for example, Patent Document 1). This laminated heat exchange section has a low-temperature layer having a low-temperature flow path through which a low-temperature fluid to be heated flows, and a high-temperature layer laminated on the low-temperature layer and having a high-temperature flow path through which a high-temperature fluid to be heated flows.

[0003] In the heat exchanger, the low-temperature layer and the high-temperature layer are each made of a metal plate, and adjacent layers are bonded together by diffusion bonding. The stacked heat exchange section is provided with a low-temperature side supply header that supplies the low-temperature fluid to the low-temperature flow path, a low-temperature side collection header (low-temperature side discharge header) that discharges the low-temperature fluid after passing through the low-temperature flow path, a high-temperature side supply header that supplies the high-temperature fluid to the high-temperature flow path, and a high-temperature side collection header (high-temperature side discharge header) that discharges the high-temperature fluid after passing through the high-temperature flow path. In this way, heat exchange occurs in the stacked heat exchange section between the low-temperature fluid flowing through the low-temperature flow path and the high-temperature fluid flowing through the high-temperature flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6757150 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the diffusion-bonded heat exchanger shown in Patent Document 1, it is conceivable to increase the size of the laminated heat exchange section in order to increase the heat exchange capacity.

[0006] However, the size of the laminated heat exchanger is limited by the size of the diffusion bonding furnace used in its manufacture, making it difficult to construct a laminated heat exchanger that meets the demand for larger sizes in a single block (a block large enough to fit into the diffusion bonding furnace). While it is possible to increase the size of the diffusion bonding furnace, this would necessitate new capital investment, which would increase costs.

[0007] Therefore, one possible solution is to prepare multiple stacked heat exchange units of a size that can be manufactured using an existing diffusion bonding furnace, arrange these stacked heat exchange units in parallel, and join the outer peripheries of adjacent surfaces to each other by welding.

[0008] However, in this case, if the working fluid serving as the heat source freezes in some of the stacked heat exchange sections, the temperature of the stacked heat exchange sections will drop and the amount of thermal contraction will increase compared to the other stacked heat exchange sections that are not frozen, which may result in excessive thermal stress occurring in certain locations of the heat exchanger (for example, the welded portions that join the stacked heat exchange sections together).

[0009] The present invention has been made to solve the above-mentioned problems, and aims to reduce the thermal stress that occurs due to freezing when freezing of the working fluid occurs in some of the multiple stacked heat exchange sections. [Means for solving the problem]

[0010] A heat exchanger according to a first aspect of the present invention comprises a plurality of stacked heat exchange sections arranged in parallel with one another, each of the plurality of stacked heat exchange sections comprising a low-temperature layer having a low-temperature flow path through which a low-temperature fluid flows, and a high-temperature layer stacked on the low-temperature layer and having a high-temperature flow path through which a high-temperature fluid flows, with adjacent layers being joined together by diffusion bonding, and each of the plurality of stacked heat exchange sections is provided with a low-temperature side supply header that supplies the low-temperature fluid to the low-temperature flow path, a low-temperature side discharge header that discharges the low-temperature fluid after passing through the low-temperature flow path, a high-temperature side supply header that supplies the high-temperature fluid to the high-temperature flow path, and a high-temperature side discharge header that discharges the high-temperature fluid after passing through the high-temperature flow path, The system further includes a main hot supply pipe, a main high-temperature discharge pipe through which high-temperature fluid discharged from each of the stacked heat exchange units flows, a main low-temperature supply pipe through which low-temperature fluid supplied to each of the stacked heat exchange units flows, a main low-temperature discharge pipe through which low-temperature fluid discharged from each of the stacked heat exchange units flows, a plurality of first connecting pipes connecting the main high-temperature supply pipe to the high-temperature side supply headers of each of the stacked heat exchange units, a plurality of second connecting pipes connecting the main high-temperature discharge pipe to the high-temperature side discharge headers of each of the stacked heat exchange units, a plurality of third connecting pipes connecting the main low-temperature supply pipe to the low-temperature side supply headers of each of the stacked heat exchange units, and a plurality of fourth connecting pipes connecting the main low-temperature discharge pipe to the low-temperature side discharge headers of each of the stacked heat exchange units.

[0011] According to this configuration, by connecting the multiple stacked heat exchange units via the main pipes and connecting pipes without welding them to each other, the difference in thermal contraction between one stacked heat exchange unit and the other stacked heat exchange units, which occurs when freezing occurs in the stacked heat exchange units, can be absorbed by deformation of the main pipes and connecting pipes. Therefore, compared to the thermal stress at the welded portion that occurs when adjacent stacked heat exchange units are connected to each other by welding, the thermal stress occurring in the main pipes and connecting pipes can be reduced. Note that freezing of the stacked heat exchange units can occur, for example, when a high-temperature fluid flowing through a high-temperature passage solidifies due to the cold of a low-temperature fluid flowing through a low-temperature passage, but is not limited to this.

[0012] Furthermore, when a diffusion-bonded laminated heat exchanger is used as in the above configuration, the size of the laminated heat exchanger is limited by the size of the diffusion bonding furnace used in its manufacture, making it difficult to increase the size (i.e., improve the heat exchange capacity) in a single block. For this reason, it is necessary to arrange multiple laminated heat exchangers in parallel to improve the heat exchange capacity, and the configuration of the present invention is useful in such heat exchangers.

[0013] In a second aspect of the present invention, in the first aspect of the present invention, it is preferable that each of the first to fourth connecting pipes has at least one curved pipe portion.

[0014] According to this configuration, since at least one curved pipe section is provided in each of the first to fourth connecting pipes, when freezing occurs in a portion of the stacked-type heat exchange section, the difference in the amount of thermal contraction between the portion and the other stacked-type heat exchange sections can be absorbed by torsional deformation, bending deformation, etc. of the curved pipe section. In other words, the curved pipe section acts as a kind of spring, allowing (absorbing) deformation of the member due to thermal contraction. This makes it possible to further alleviate thermal stress occurring at the connection section of each connecting pipe with the main pipe than in the first invention.

[0015] In a third aspect of the present invention, in the second aspect of the present invention, it is preferable that the number of the bending pipe portions is two or more.

[0016] According to this configuration, by providing two or more curved pipe portions on each connecting pipe, the same effects as those of the second invention can be obtained more reliably.

[0017] In a fourth aspect of the present invention, in the second aspect of the present invention, it is preferable that the number of the bending tube portion is one.

[0018] According to this configuration, the number of curved pipe sections can be reduced as much as possible, simplifying the configuration of each connecting pipe, thereby simplifying the piping structure of the heat exchanger and improving economy.

[0019] In a fifth aspect of the invention, in the second aspect, it is preferable that the number of the bending pipe sections is two, and the directions of extension of the bending center lines of the two bending pipe sections are perpendicular to each other.

[0020] With this configuration, the bending center lines of the two curved pipe sections are perpendicular to each other, which improves the degree of freedom in absorbing the torsional moment acting on each connecting pipe due to the thermal stress. Here, the bending center line is a straight line that passes through the center of curvature of the flow path center line of each curved pipe section and is perpendicular to the plane that includes the flow path center line.

[0021] In a sixth invention, in any one of the first to fifth inventions, it is preferable that the low-temperature fluid flowing into the low-temperature flow path is liquid hydrogen or liquefied natural gas, and the high-temperature fluid flowing into the high-temperature flow path is gaseous carbon dioxide.

[0022] In this way, by using liquid hydrogen or liquefied natural gas as the cryogenic fluid and gaseous carbon dioxide as the high-temperature fluid, two functions, vaporization of liquefied natural gas and liquefaction of carbon dioxide, can be simultaneously achieved. However, in such heat exchangers, freezing (solidification) of carbon dioxide is likely to occur in the high-temperature flow path, making the configuration of this invention (first invention) particularly useful. Specifically, the temperature of liquefied natural gas used to cool carbon dioxide in a heat exchanger is, for example, −150°C to −160°C, and the temperature of liquid hydrogen is, for example, −250°C, which is significantly lower than the solidification temperature (approximately −56°C) of carbon dioxide at typical storage and transportation pressures (0.52 MPa to 3 MPa). Therefore, carbon dioxide flowing through the high-temperature flow path in a heat exchanger is likely to freeze (solidify) due to the cold energy of the cryogenic fluid. When the high-temperature flow path is blocked, the temperature of the laminated heat exchanger having the high-temperature flow path approaches the temperature of the cryogenic fluid flowing through the low-temperature flow path. As a result, a large difference in thermal contraction occurs between the stacked heat exchange unit and other stacked heat exchange units adjacent to it. In such a situation, for example, if the outer peripheries of adjacent faces of multiple stacked heat exchange units are connected to each other by welding, there is nothing to absorb the difference in thermal contraction between the adjacent blocks (stacked heat exchange units), and large thermal stress occurs at the welded joints. Therefore, the configuration of the present invention (first invention) that can absorb such a large difference in thermal contraction and release the thermal stress is particularly useful. [Effects of the Invention]

[0023] According to the present invention, when the cryogenic fluid freezes in some of the plurality of stacked heat exchange sections, the thermal stress caused by the freezing can be reduced. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a side view showing a schematic configuration of a heat exchanger according to the first embodiment. [Figure 2] FIG. 2 is a view taken in the direction of the arrow II in FIG. [Figure 3]Figure 3(a) is a view of the high temperature layer from the front, Figure 3(b) is a view of the low temperature layer from the front, and Figure 3(c) is a vertical cross-sectional view showing the stacked structure of the high temperature layer and the low temperature layer. [Figure 4] FIG. 4(a) is a side view seen from the front side showing a heat exchanger in a comparative example, and FIG. 4(b) is a schematic view of the entire heat exchanger excluding the high-temperature fluid outlet header seen from the right side. [Figure 5] FIG. 5 is a view corresponding to FIG. 1 and showing the second embodiment. [Figure 6] FIG. 6 is an enlarged perspective view of a portion VI in FIG. [Figure 7] FIG. 7 is a view corresponding to FIG. 5, showing a modification of the second embodiment. [Figure 8] FIG. 8 is an enlarged perspective view of part VIII in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0026] (Embodiment 1) The overall configuration of the heat exchanger 1 will be described with reference to Figures 1 and 2. Figure 1 is a side view showing a schematic configuration of the heat exchanger 1 in embodiment 1, and Figure 2 is a view seen from the direction of arrow II in Figure 1. In the following description, front, back, left, and right will follow the definitions of the directional axes shown in each figure, but these directional definitions are provided for the convenience of describing the heat exchanger 1 and do not limit the configuration of the present invention in any way.

[0027] The heat exchanger 1 performs heat exchange between liquefied natural gas (hereinafter referred to as LNG), which is an example of a low-temperature fluid, and gaseous carbon dioxide, which is an example of a high-temperature fluid, thereby vaporizing the LNG and liquefying the carbon dioxide.

[0028] Specifically, the heat exchanger 1 has four heat exchange units 10, a low-temperature main supply pipe 20, a low-temperature main discharge pipe 30, a high-temperature main supply pipe 40, a high-temperature main discharge pipe 50, four low-temperature supply connection pipes 21, four low-temperature discharge connection pipes 31, four high-temperature supply connection pipes 41, and four high-temperature discharge connection pipes 51.

[0029] The four heat exchange units 10 are arranged in parallel at intervals in the front-rear direction.

[0030] The low-temperature supply main pipe 20 receives LNG supplied from an LNG supply source provided outside the heat exchanger 1 and supplies it to each heat exchange unit 10 via four low-temperature supply connection pipes 21 .

[0031] The low-temperature discharge main pipe 30 receives liquefied natural gas (hereinafter referred to as NG) vaporized in each heat exchange unit 10 via four low-temperature discharge connection pipes 31, merges the gas, and then discharges the gas outside the heat exchanger 1.

[0032] The high-temperature supply main pipe 40 receives gaseous carbon dioxide supplied from a CO 2 supply source provided outside the heat exchanger 1 and supplies it to each heat exchange unit 10 via four high-temperature supply connection pipes 41.

[0033] The high-temperature discharge main pipe 50 receives the carbon dioxide liquefied in each heat exchange unit 10 via four high-temperature discharge connection pipes 51, joins the carbon dioxide, and then discharges the carbon dioxide to the outside of the heat exchanger 1.

[0034] [Configuration of each heat exchange unit] Each heat exchange unit 10 is composed of a stacked microchannel heat exchanger.

[0035] Specifically, each heat exchange unit 10 includes a diffusion-bonded laminated heat exchange section 11 in which low-temperature layers 111 and high-temperature layers 112 (see FIG. 3 described later) are alternately laminated adjacent to each other, and headers 12, 13, 14, and 15 fixed to the laminated heat exchange section 11. In this example, the low-temperature layers 111 and the high-temperature layers 112 are alternately laminated in the front-to-rear direction (see FIG. 3(c) described later).

[0036] The headers include a low-temperature side supply header 12 that distributes LNG to multiple low-temperature flow paths 111a, a high-temperature side supply header 14 that distributes gaseous carbon dioxide to multiple high-temperature flow paths 112a, a low-temperature side discharge header 13 that combines and discharges the LNG that has flowed through the multiple low-temperature flow paths 111a, and a high-temperature side discharge header 15 that combines and discharges the carbon dioxide that has flowed through the multiple high-temperature flow paths 112a.

[0037] The low-temperature side supply header 12 is made of a hollow case body arranged to cover the lower end surface of the stacked heat exchange section 11. A receiving port 12a for receiving LNG is formed in the center of the lower end of the low-temperature side supply header 12.

[0038] The low-temperature side discharge header 13 is made of a hollow case body arranged to cover the upper end surface of the stacked heat exchanger unit 11. A discharge port 13a for discharging NG is formed in the center of the upper end of the low-temperature side discharge header 13.

[0039] The high-temperature side supply header 14 is made of a semi-cylindrical hollow case body that is arranged to extend in the front-to-rear direction (the direction perpendicular to the plane of the paper in FIG. 1) on the left side of the upper end of the stacked heat exchange section 11. An inlet 14a for receiving gaseous carbon dioxide is formed in the center of the high-temperature side supply header 14 in the vertical direction and in the center of the front-to-rear direction.

[0040] The high-temperature side discharge header 15 is made of a semi-cylindrical hollow case body that is arranged to extend in the front-to-rear direction (the direction perpendicular to the plane of the paper in FIG. 1) on the right side of the lower end of the stacked heat exchange section 11. An outlet 15a for discharging liquefied carbon dioxide is formed in the center of the high-temperature side discharge header 15 in the vertical direction and in the center of the front-to-rear direction.

[0041] Figure 3(a) is a view of the high temperature layer 112 from the front side, Figure 3(b) is a view of the low temperature layer 111 from the front side, and Figure 3(c) is a vertical cross-sectional view showing the stacked structure of the high temperature layer 112 and the low temperature layer 111.

[0042] The low-temperature layer 111 is provided with multiple low-temperature flow paths 111a into which LNG is introduced. The multiple low-temperature flow paths 111a are arranged adjacent to each other in the left-right direction and extend linearly in the up-down direction. An inlet 111b located at the bottom of each low-temperature flow path 111a opens into the interior space of the low-temperature supply header 12, and an outlet 111c located at the upper end of each low-temperature flow path 111a opens into the interior space of the low-temperature discharge header 13. Therefore, LNG in the low-temperature supply header 12 flows into the low-temperature flow path 111a. While flowing through the low-temperature flow path 111a, the LNG exchanges heat with carbon dioxide flowing through the high-temperature flow path 112a, vaporizing it into NG, which then flows into the low-temperature discharge header 13. The NG that has flowed into the low-temperature discharge header 13 is discharged from the outlet 13a of the low-temperature discharge header 13 into the low-temperature discharge connecting pipe 31. The shape of the low-temperature flow path 111a is not limited to a linear shape, and various shapes such as a zigzag or wave shape can be adopted. Furthermore, the inlet 111b and the outlet 111c do not necessarily have to be open in the vertical direction, and for example, either or both of the inlet 111b and the outlet 111c may be open in the horizontal direction.

[0043] Meanwhile, the high-temperature layer 112 is provided with multiple high-temperature flow paths 112a into which gaseous carbon dioxide is introduced. The high-temperature flow paths 112a are zigzag flow paths that allow carbon dioxide to flow from top to bottom, reciprocating back and forth. An inlet 112b located at the upper end of the high-temperature flow path 112a opens into the internal space of the high-temperature supply header 14, and an outlet 112c located at the lower end of the high-temperature flow path 112a opens into the internal space of the high-temperature discharge header 15. Therefore, LNG in the high-temperature supply header 14 flows into the high-temperature flow path 112a. While flowing through the high-temperature flow path 112a, the LNG is liquefied by heat exchange with LNG flowing through the low-temperature flow path 111a, and then flows into the high-temperature discharge header 15. The liquid carbon dioxide that has flowed into the high-temperature discharge header 15 is discharged from the outlet 15a of the high-temperature discharge header 15 into the high-temperature discharge connecting pipe 51. The shape of the high-temperature flow path 112a is not limited to a zigzag shape, and various shapes such as a straight shape, a wavy shape, etc. Furthermore, the inlet 112b and the outlet 112c do not necessarily need to open in the left-right direction, and for example, both or either the inlet 112b and the outlet 112c may open in the up-down direction.

[0044] The low-temperature layer 111 is a flat layer including the plurality of low-temperature flow paths 111a, and the high-temperature layer 112 is a flat layer including the plurality of high-temperature flow paths 112a. In this example, the low-temperature layer 111 and the high-temperature layer 112 are each formed by forming recessed grooves that form the low-temperature flow paths 111a and the high-temperature flow paths 112a on the surface of a single metal plate. The metal plate that forms the low-temperature layer 111 and the metal plate that forms the high-temperature layer 112 are laminated together and diffusion-bonded to form an integrated structure.

[0045] Here, diffusion bonding is a method of joining metal plates together by bringing them into close contact with each other and applying pressure at a temperature below the melting point of the material that makes up the metal plates, to an extent that causes minimal plastic deformation, thereby utilizing the diffusion of atoms that occurs between the joining surfaces.

[0046] In addition, in this embodiment, the low temperature layer 111 and the high temperature layer 112 are both made of a single metal plate, but this is not limiting and they may be made, for example, by diffusion bonding a plurality of metal plates. That is, for example, the low temperature layer 111 may be made of two metal plates and the high temperature layer 112 may be made of three metal plates.

[0047] [Piping structure details] Next, the connection structure of the piping provided in the heat exchanger 1 will be described with reference to FIGS.

[0048] As described above, the pipes provided in the heat exchanger 1 include the low-temperature supply main pipe 20, the low-temperature discharge main pipe 30, the high-temperature supply main pipe 40, the high-temperature discharge main pipe 50, four low-temperature supply connecting pipes 21, four low-temperature discharge connecting pipes 31, four high-temperature supply connecting pipes 41, and four high-temperature discharge connecting pipes 51. The high-temperature supply connecting pipe 41 corresponds to the first connecting pipe, the high-temperature discharge connecting pipe 51 corresponds to the second connecting pipe, the low-temperature supply connecting pipe 21 corresponds to the third connecting pipe, and the low-temperature discharge connecting pipe 31 corresponds to the fourth connecting pipe.

[0049] The low-temperature supply main pipe 20 is located directly below each low-temperature side supply header 12 of the four heat exchange units 10 and extends horizontally in the front-to-rear direction. Connection holes 20a are formed in the low-temperature supply main pipe 20 at locations facing each low-temperature side supply header 12.

[0050] Each of the four low-temperature supply connection pipes 21 is a straight pipe extending vertically. Each low-temperature supply connection pipe 21 has an upper end connected to the inlet 12a of each low-temperature supply header 12 and a lower end connected to each connection hole 20a of the low-temperature supply main pipe 20.

[0051] The low-temperature discharge main pipe 30 is located directly above the low-temperature side discharge headers 13 of the four heat exchange units 10 and extends horizontally in the front-to-rear direction. Connection holes 30a are formed in the low-temperature discharge main pipe 30 at locations facing the low-temperature side discharge headers 13.

[0052] Each of the four low-temperature discharge connecting pipes 31 is a straight pipe extending vertically. Each low-temperature discharge connecting pipe 31 has an upper end connected to a corresponding connecting hole 30a of the low-temperature discharge main pipe 30 and a lower end connected to a discharge port 13a of a corresponding low-temperature side discharge header 13.

[0053] The high-temperature supply main pipe 40 extends horizontally in the front-to-rear direction, located to the left of each high-temperature supply header 14 of the four heat exchange units 10. Connection holes 40a are formed in the high-temperature supply main pipe 40 at locations facing each high-temperature supply header 14.

[0054] The four high-temperature supply connection pipes 41 are straight pipes extending in the left-right direction (perpendicular to the plane of FIG. 2). Each high-temperature supply connection pipe 41 has a left end connected to a corresponding connection hole 40a of the high-temperature supply main pipe 40 and a right end connected to the inlet 14a of each high-temperature side supply header 14 (see FIG. 1).

[0055] The high-temperature discharge main pipe 50 is located to the right of each high-temperature side discharge header 15 of the four heat exchange units 10 and extends horizontally in the front-to-rear direction. Connection holes 50a are formed in the high-temperature discharge main pipe 50 at locations facing each high-temperature side discharge header 15.

[0056] The four high-temperature discharge connecting pipes 51 are straight pipes extending in the left-right direction. Each high-temperature discharge connecting pipe 51 has a left end connected to the discharge port 15a of each high-temperature side discharge header 15 and a right end connected to each connection hole 50a of the high-temperature discharge main pipe 50 (see FIG. 1).

[0057] [Explanation and effects of comparative examples] The effects of the heat exchanger 1 configured as above will be described below in comparison with the comparative example shown in Fig. 4. In the comparative example shown in Fig. 4, the same components as those in the heat exchanger 1 of the present embodiment are designated by reference numerals increased by 300, and detailed descriptions thereof will be omitted where appropriate.

[0058] Figure 4(a) is a side view of the heat exchanger 301 in the comparative example, viewed from the front, and Figure 4(b) is a schematic view of the entire heat exchanger 301, excluding the high-temperature fluid outlet header 315, viewed from the right side.

[0059] In the heat exchanger 301 of the comparative example, four stacked heat exchange sections 311 are arranged adjacent to each other in the front-to-rear direction. In this heat exchanger 301, adjacent stacked heat exchange sections 311 are connected by welding. The thick lines in FIG. 4(b) indicate welded portions W (so-called bead portions) formed along the boundaries between the adjacent stacked heat exchange sections 311. In the figure, reference numeral 312 denotes a low-temperature side supply header, reference numeral 313 denotes a low-temperature side discharge header, reference numeral 314 denotes a high-temperature side supply header, and reference numeral 315 denotes a high-temperature side discharge header.

[0060] In a heat exchanger 301 constructed by welding four stacked heat exchange sections 311 together to form a single block, as in this comparative example, if freezing of the working fluid (e.g., carbon dioxide) occurs in one of the four stacked heat exchange sections 311, there is a risk that excessive thermal stress will occur in the welded portion W due to a large difference in the amount of thermal contraction between that stacked heat exchange section 311 and the other stacked heat exchange sections 311.

[0061] As an example, consider the case in which carbon dioxide freezes in the high-temperature flow path 112a of the second stacked heat exchanger 311 from the right in FIG. 4(b). There are various factors that can cause carbon dioxide to freeze, but one possible cause is that the wall temperature at the outlet of the high-temperature flow path 112a drops below the solidification temperature of carbon dioxide due to the cold energy of LNG. When carbon dioxide freezes in the high-temperature flow path 112a, the flow of carbon dioxide through the high-temperature flow path 112a is blocked, and the temperature of the stacked heat exchanger 311 where the freezing occurred becomes approximately equal to the temperature of the LNG (e.g., −150°C to 160°C) flowing through the low-temperature flow path 111a. Therefore, the temperature of the stacked heat exchanger 311 where the freezing occurred drops significantly compared to the other three stacked heat exchangers 311. As a result, the stacked heat exchanger 311 where the freezing occurred thermally contracts in the vertical direction as indicated by the thick arrows in FIG. 4. This thermal contraction causes a problem in that excessive thermal stress acts on the welded portion W between the heat exchange portion 311 and the stacked heat exchange portions 311 on either side of it. If the welded portion W covered by the headers 312, 313 is damaged due to thermal fatigue caused by repeated excessive thermal stress, it is necessary to remove the headers 312, 313 and then re-weld the damaged welded portion W. As a result, it is necessary to stop operation of the entire plant, including the heat exchanger 301, for an extended period of time to carry out recovery work, which may result in losses in time and cost.

[0062] In contrast to this, in this embodiment, instead of welding the four stacked heat exchange sections 11 together to form one block, the stacked heat exchange sections 11 are connected via piping while being separated from each other using the above-mentioned piping structure.

[0063] Specifically, in this embodiment, the heat exchanger 1 includes a high-temperature supply main pipe 40 through which gaseous carbon dioxide supplied to each stacked heat exchange section 11 flows, a high-temperature discharge main pipe 50 through which liquefied carbon dioxide discharged from each stacked heat exchange section 11 flows, a low-temperature supply main pipe 20 through which LNG supplied to each stacked heat exchange section 11 flows, a low-temperature discharge main pipe through which NG discharged from each stacked heat exchange section 11 flows, and four high-temperature supply pipes connecting the high-temperature supply main pipe 40 to the high-temperature side supply headers 14 of each stacked heat exchange section 11. It is configured with a connecting pipe 41 (an example of a first connecting pipe), four high-temperature discharge connecting pipes 51 (an example of a second connecting pipe) that connect the high-temperature discharge main pipe 50 to the high-temperature side discharge headers 15 of each stacked heat exchange section 11, four low-temperature supply connecting pipes 21 (an example of a third connecting pipe) that connect the low-temperature supply main pipe 20 to the low-temperature side supply headers 12 of each stacked heat exchange section 11, and four low-temperature discharge connecting pipes 31 (an example of a fourth connecting pipe) that connect the low-temperature discharge main pipe 30 to the low-temperature side discharge headers 13 of each stacked heat exchange section 11.

[0064] According to this configuration, the four stacked heat exchange sections 11 are connected using the main pipes 20, 30, 40, 50 and their branch pipes, the connecting pipes 21, 31, 41, 51, so that even if freezing occurs in some of the stacked heat exchange sections 11, the resulting thermal stress can be released by deformation of the main pipes 20, 30, 40, 50 and the connecting pipes 21, 31, 41, 51. Therefore, the welded portions W (bead portions) formed along the boundaries between adjacent stacked heat exchange sections 11 as in the comparative example can be eliminated, thereby preventing the generation of excessive thermal stress.

[0065] Furthermore, when a diffusion-bonded laminated heat exchange section 11 is used as in the above embodiment, the size of the laminated heat exchange section 11 is limited by the size of the diffusion bonding furnace used in its manufacture, making it difficult to increase the size (i.e., improve the heat exchange capacity) in a single block. For this reason, it is desirable to arrange multiple laminated heat exchange sections 11 in parallel to improve the heat exchange capacity, and in such a heat exchanger 1, the configuration of this embodiment is useful because it can release thermal stress caused by the temperature difference between the laminated heat exchange sections 11 and the other laminated heat exchange sections 11 when freezing occurs in some of the laminated heat exchange sections 11.

[0066] In the heat exchanger 1 of the above embodiment, the low-temperature fluid is LNG, and the high-temperature fluid is carbon dioxide.

[0067] In this heat exchanger 1, carbon dioxide is likely to freeze (solidify) in the high-temperature flow path 112a, so the piping structure described above is particularly useful for reducing thermal stress in the heat exchanger 1. Specifically, the temperature of LNG used to cool carbon dioxide in the heat exchanger 1 is, for example, −150°C to −160°C, which is significantly lower than the solidification temperature (approximately −56°C) of carbon dioxide at typical pressures (0.52 MPa to 3 MPa) during storage and transportation. Therefore, carbon dioxide flowing through the high-temperature flow path 112a in the heat exchanger 1 is likely to freeze (solidify) due to the cold energy of the LNG. When the high-temperature flow path 112a is blocked, the temperature of the stacked heat exchange section 11 having the high-temperature flow path 112a approaches the temperature of the LNG flowing through the low-temperature flow path 111a, generating significant thermal stress due to the temperature difference between the stacked heat exchange section 11 and the other stacked heat exchange sections 11. Therefore, the configuration of this embodiment, which can release such significant thermal stress, is particularly useful.

[0068] (Embodiment 2) 5 is a view corresponding to FIG. 1 showing embodiment 2. In this embodiment, the shapes of the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, the high-temperature supply connecting pipe 41, and the high-temperature discharge connecting pipe 51 are different from those of embodiment 1. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0069] That is, in this embodiment, the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, the high-temperature supply connecting pipe 41, and the high-temperature discharge connecting pipe 51 are each configured with a curved intermediate portion in the pipe length direction. Also, since the shapes of the connecting pipes 21, 31, 41, and 51 are different from those in the first embodiment, the positions of the main pipes 20, 30, 40, and 50 are also different from those in the first embodiment.

[0070] [Layout of each main pipe] First, the layout of the main pipes 20, 30, 40, and 50 will be described in order with reference to FIG.

[0071] The low-temperature supply main pipe 20 is disposed at a position offset to the left of directly below the inlet 12a of the low-temperature side supply header 12. The low-temperature discharge main pipe 30 is disposed at a position offset to the right of the outlet 13a of the low-temperature side discharge header 13. The offset amount of this low-temperature supply main pipe 20 and the offset amount of the low-temperature side discharge header 13 are set to be equal, but are not limited to this.

[0072] The high-temperature supply main pipe 40 is disposed at a position offset upward from a position directly beside the inlet 14a of the high-temperature supply header 14. The high-temperature discharge main pipe 50 is disposed at a position offset downward from a position directly beside the outlet 15a of the high-temperature discharge header 15. The offset amount of the high-temperature supply main pipe 40 and the offset amount of the high-temperature discharge main pipe 50 are set to be equal, but are not limited to this.

[0073] [Configuration of each connecting pipe] Fig. 6 is an enlarged perspective view of part VI in Fig. 5. In this figure, the high-temperature discharge connecting pipe 51 is extracted and enlarged as an example, but the connection structures of the other low-temperature supply connecting pipes 21, 31, and 41 are also similar.

[0074] 6, the high-temperature discharge connecting pipe 51 has a first straight pipe section 51a extending vertically upward from the connecting hole 50a of the high-temperature discharge main pipe 50, a second straight pipe section 51b extending horizontally to the right from the discharge port 15a of the high-temperature side discharge header 15, and a curved pipe section 51c connecting the upper end of the first straight pipe section 51a to the right end of the first straight pipe section 51a. The curved pipe section 51c is configured as an elbow pipe with a bending angle of 90°. Note that this bending angle is not limited to 90° and may be any angle.

[0075] 5, the low-temperature supply connection pipe 21 has a first straight pipe section 21a extending horizontally to the right from the connection hole 20a of the low-temperature supply main pipe 20, a second straight pipe section 21b extending vertically downward from the inlet 12a of the low-temperature side supply header 12, and a curved pipe section 21c connecting the right end of the first straight pipe section 21a to the lower end of the second straight pipe section 21b. The curved pipe section 21c is configured as an elbow pipe with a bending angle of 90°. Note that this bending angle is not limited to 90° and may be any angle.

[0076] 5, the low-temperature discharge connecting pipe 31 has a first straight pipe section 31a extending horizontally to the left from the connecting hole 30a of the low-temperature discharge main pipe 30, a second straight pipe section 31b extending vertically upward from the discharge port 13a of the low-temperature side discharge header 13, and a curved pipe section 31c connecting the left end of the first straight pipe section 31a to the upper end of the second straight pipe section 31b. The curved pipe section 31c is configured as an elbow pipe with a bending angle of 90°. Note that this bending angle is not limited to 90° and may be any angle.

[0077] 5, the high-temperature supply connection pipe 41 has a first straight pipe section 41a extending vertically downward from the connection hole 40a of the high-temperature supply main pipe 40, a second straight pipe section 41b extending horizontally to the left from the inlet 14a of the high-temperature side supply header 14, and a curved pipe section 41c connecting the bottom end of the first straight pipe section 41a to the left end of the second straight pipe section 41b. The curved pipe section 41c is configured as an elbow pipe with a bending angle of 90°. Note that this bending angle is not limited to 90° and may be any angle.

[0078] (Action and effect) As described above, in this embodiment, the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, the high-temperature supply connecting pipe 41, and the high-temperature discharge connecting pipe 51 have curved pipe portions 21c, 31c, 41c, and 51c, respectively.

[0079] With this configuration, when freezing occurs in a portion of the stacked heat exchange section 11, thermal stress can be released by twisting or bending deformation of each curved pipe section 21c, 31c, 41c, 51c. In other words, the curved pipe sections 21c, 31c, 41c, 51c function as a kind of spring, allowing (absorbing) deformation of the members due to thermal stress. This alleviates stress concentration that occurs at the connection section of each connecting pipe 21, 31, 41, 51 with the main pipe 20, 30, 40, 50, thereby reducing thermal stress in each connecting pipe 21, 31, 41, 51.

[0080] (Modification of the second embodiment) 7 is a view equivalent to FIG. 5 showing a modification of the second embodiment. This embodiment differs from the second embodiment in that the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, the high-temperature supply connecting pipe 41, and the high-temperature discharge connecting pipe 51 each have a plurality of curved pipe sections in the middle of their pipe lengths. In FIG. 7, the same components as those in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0081] That is, in this modification, each of the connecting pipes 21, 31, 41, and 51 is configured to have two curved pipe portions.

[0082] Fig. 8 is an enlarged perspective view of part VIII in Fig. 7. In this figure, the high-temperature discharge connecting pipe 51 is extracted and enlarged as an example, but the other low-temperature supply connecting pipe 21, low-temperature discharge connecting pipe 31, and high-temperature supply connecting pipe 41 also have the same connecting structure.

[0083] For ease of understanding, the high-temperature discharge connecting pipe 51 will be described in detail with reference to Figures 7 and 8, and then the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, and the high-temperature supply connecting pipe 41 will be described in detail with reference to Figure 7.

[0084] As shown in FIGS. 7 and 8, the high-temperature discharge connecting pipe 51 includes a first straight pipe section 51a extending vertically upward from the connecting hole 50a of the high-temperature discharge main pipe 50, a second straight pipe section 51b extending horizontally to the right from the discharge port 15a of the high-temperature side discharge header 15, a first curved pipe section 51d, and a second curved pipe section 51e. The first curved pipe section 51d is configured as an elbow pipe with a bending angle of 90°. One end of the first curved pipe section 51d is connected to the upper end of the first straight pipe section 51a. The bending center line C1 of the first curved pipe section 51d extends in the left-right direction. The second curved pipe section 51e is configured as an elbow pipe with a bending angle of 90°. The second curved pipe section 51e connects the other end (rear end) of the first curved pipe section 51d to the right end of the second straight pipe section 51b. The bending center line C2 of the second bent pipe section 51e extends in the vertical direction. That is, the extending direction of the bending center line C2 of the second bent pipe section 51e and the extending direction of the bending center line C1 of the first bent pipe section 51d are perpendicular to each other. Each bending center line C1, C2 is a straight line that passes through the center of curvature of the flow path center line of each bent pipe section 51d, 51e and is perpendicular to a plane including the flow path center line. That is, the first bent pipe section 51d is curved in an arc shape around the bending center line C1, and the second bent pipe section 51e is curved in an arc shape around the bending center line C2. The definition of the bending center line will be the same in the following description.

[0085] As shown only in FIG. 7 , the low-temperature supply connection pipe 21 includes a first straight pipe section 21a extending horizontally to the right from the connection hole 20a of the low-temperature supply main pipe 20, a second straight pipe section 21b extending vertically downward from the inlet 12a of the low-temperature side supply header 12, a first curved pipe section 21d, and a second curved pipe section 21e. The first curved pipe section 21d is an elbow pipe with a bending angle of 90°. One end of the first curved pipe section 21d is connected to the right end of the first straight pipe section 21a. The bending center line of the first curved pipe section 21d extends in the vertical direction. The second curved pipe section 21e is an elbow pipe with a bending angle of 90°. The second curved pipe section 21e connects the other end of the first curved pipe section 21d to the lower end of the second straight pipe section 21b. The bending center line of the second curved pipe section 21e extends in the horizontal direction. That is, the direction in which the bending center line of the second bending pipe section 21e extends is perpendicular to the direction in which the bending center line of the first bending pipe section 21d extends.

[0086] As shown only in FIG. 7 , the low-temperature discharge connecting pipe 31 includes a first straight pipe section 31a extending horizontally leftward from the connecting hole 30a of the low-temperature discharge main pipe 30, a second straight pipe section 31b extending vertically upward from the discharge port 13a of the low-temperature side discharge header 13, a first curved pipe section 31d, and a second curved pipe section 31e. The first curved pipe section 31c is an elbow pipe with a bending angle of 90°. One end of the first curved pipe section 31d is connected to the left end of the first straight pipe section 31a. The bending center line of the first curved pipe section 31d extends in the front-to-rear direction (the direction perpendicular to the plane of FIG. 7 ). The second curved pipe section 31e is an elbow pipe with a bending angle of 90°. The second curved pipe section 31e connects the other end of the first curved pipe section 51d to the upper end of the second straight pipe section 31b. The bending center line of the second bending pipe section 31e extends in the left-right direction, that is, the extending direction of the bending center line of the second bending pipe section 31e and the extending direction of the bending center line of the first bending pipe section 31d are perpendicular to each other.

[0087] As shown only in FIG. 7 , the high-temperature supply connection pipe 41 includes a first straight pipe section 41a extending vertically downward from the connection hole 40a of the high-temperature supply main pipe 40, a second straight pipe section 41b extending horizontally leftward from the inlet 14a of the high-temperature side supply header 14, a first curved pipe section 41d, and a second curved pipe section 41e. The first curved pipe section 41d is an elbow pipe with a bending angle of 90°. One end of the first curved pipe section 41d is connected to the lower end of the first straight pipe section 41a. The bending center line of the first curved pipe section 41d extends in the left-right direction. The second curved pipe section 41e is an elbow pipe with a bending angle of 90°. The second curved pipe section 41e connects the other end of the first curved pipe section 41d to the left end of the second straight pipe section 41b. The bending center line of the second curved pipe section 41e extends in the up-down direction. That is, the extending direction of the bending center line of the second bending pipe section 41e and the extending direction of the bending center line of the first bending pipe section 41d are perpendicular to each other.

[0088] (Action and effect) As described above, in the heat exchanger 1 of this modified example, the low-temperature supply connecting pipe 21, the low-temperature discharge connecting pipe 31, the high-temperature supply connecting pipe 41, and the high-temperature discharge connecting pipe 51 each have two curved pipe portions. That is, the low-temperature supply connecting pipe 21 has a first curved pipe portion 21d and a second curved pipe portion 21e, the low-temperature discharge connecting pipe 31 has a first curved pipe portion 31d and a second curved pipe portion 31e, the high-temperature supply connecting pipe 41 has a first curved pipe portion 41d and a second curved pipe portion 41e, and the high-temperature discharge connecting pipe 51 has a first curved pipe portion 51d and a second curved pipe portion 51e.

[0089] According to this configuration, by providing two curved pipe sections in each of the connecting pipes 21, 31, 41, and 51, it is possible to increase the elastic modulus of each of the connecting pipes 21, 31, 41, and 51 compared to when only one curved pipe section is provided. Therefore, it is possible to more reliably absorb deformation of components caused by thermal stress and reduce thermal stress in the heat exchanger 1 compared to the second embodiment.

[0090] Furthermore, in this modification, the extending direction of the bending center line of the first curved pipe section 21d of the low-temperature supply connecting pipe 21 and the bending center line of the second curved pipe section 21e are perpendicular to each other. Furthermore, the extending direction of the bending center line of the first curved pipe section 31d of the low-temperature discharge connecting pipe 31 and the bending center line of the second curved pipe section 31e are perpendicular to each other. The extending direction of the bending center line of the first curved pipe section 41d of the high-temperature supply connecting pipe 41 and the bending center line of the second curved pipe section 41e are perpendicular to each other. The extending direction of the bending center line of the first curved pipe section 51d of the high-temperature discharge connecting pipe 51 and the bending center line of the second curved pipe section 51e are perpendicular to each other.

[0091] According to this configuration, the extension directions of the bending center lines of the two curved pipe sections 21d, 21e (or 31d, 31e or 41d, 41e or 51d, 51e) are perpendicular to each other, thereby improving the degree of freedom in absorbing the torsional moment acting on each connecting pipe 21, 31, 41, 51 due to the thermal stress.

[0092] (Other embodiments) Although the heat exchanger 1 according to the embodiment of the present invention has been described above, the present invention is not limited to this, and the following embodiments can be adopted, for example.

[0093] (1) In the above-described embodiments and modifications, the number of the stacked heat exchange sections 11 is four, but this is not limitative. That is, the number of the stacked heat exchange sections 11 may be any number as long as it is two or more.

[0094] (2) In each of the above-described embodiments and variations, each stacked heat exchange section 11 is constructed by stacking a plurality of high-temperature layers 112 and a plurality of low-temperature layers 111 alternately adjacent to each other, but this is not limited to this, and the high-temperature layers 112 and the low-temperature layers 111 may be arranged in any stacking ratio, such as 1:2, 1:3, 2:1, or 3:1.

[0095] (3) In the above embodiments and modifications, LNG has been described as an example of a low-temperature fluid, but the present invention is not limited to this and may be, for example, liquid hydrogen, etc. Also, carbon dioxide has been described as an example of a high-temperature fluid, but the present invention is not limited to this and may be any fluid as long as it has a higher solidification temperature than the low-temperature fluid inlet. [Explanation of symbols]

[0096] 1: Heat exchanger 11: Stacked heat exchange section 12: Low temperature side supply header 13: Low temperature side discharge header 14: High temperature supply header 15: High temperature side discharge header 20: Low temperature supply main pipe 21: Low temperature supply connection pipe (third connection pipe) 21c: Curved pipe section 21d: First curved pipe section 21e: Second curved pipe section 30: Low temperature discharge main piping 31: Low temperature discharge connecting pipe (4th connecting pipe) 31c: Curved pipe section 31d: First curved pipe section 31e: Second curved pipe section 40: High temperature supply main piping 41: High temperature supply connecting pipe (first connecting pipe) 41c: Curved pipe section 41d: First curved pipe section 41e: Second curved pipe section 50: High temperature discharge main piping 51: High temperature discharge connection pipe (second connection pipe) 51c: Curved pipe section 51d: First curved pipe section 51e: Second curved pipe section 111: Low temperature layer 111a: Low temperature flow path 112: High temperature layer 112a: High temperature flow path C1: Bend centerline C2: Bend centerline

Claims

1. A plurality of stacked heat exchange units are arranged in parallel with each other, each of the plurality of laminated heat exchange units includes a low-temperature layer having a low-temperature flow path through which a low-temperature fluid flows, and a high-temperature layer laminated on the low-temperature layer and having a high-temperature flow path through which a high-temperature fluid flows, and adjacent layers are bonded to each other by diffusion bonding; Each of the plurality of stacked heat exchange units is provided with a low-temperature side supply header that supplies the low-temperature fluid to the low-temperature flow path, a low-temperature side discharge header that discharges the low-temperature fluid after passing through the low-temperature flow path, a high-temperature side supply header that supplies the high-temperature fluid to the high-temperature flow path, and a high-temperature side discharge header that discharges the high-temperature fluid after passing through the high-temperature flow path, a high-temperature supply main pipe through which a high-temperature fluid to be supplied to each of the stacked heat exchange units flows; a high-temperature discharge main pipe through which high-temperature fluid discharged from each of the stacked heat exchange units flows; a low-temperature supply main pipe through which a low-temperature fluid to be supplied to each of the stacked heat exchange units flows; a low-temperature discharge main pipe through which the low-temperature fluid discharged from each of the stacked heat exchange units flows; a plurality of first connecting pipes connecting the high-temperature supply main pipe and the high-temperature side supply headers of each of the stacked heat exchange units; a plurality of second connection pipes connecting the high-temperature discharge main pipe and the high-temperature side discharge headers of each of the stacked heat exchange units; a plurality of third connecting pipes connecting the low-temperature supply main pipe and the low-temperature side supply headers of each of the stacked heat exchange units; a plurality of fourth connecting pipes connecting the low-temperature discharge main pipe and the low-temperature side discharge headers of the stacked heat exchange sections;

2. The heat exchanger according to claim 1, A heat exchanger, wherein each of the first to fourth connecting pipes has at least one curved pipe portion.

3. 3. The heat exchanger according to claim 2, The number of the curved pipe portions is two or more.

4. 3. The heat exchanger according to claim 2, A heat exchanger, wherein the number of the curved pipe portions is one.

5. 3. The heat exchanger according to claim 2, The number of the bending pipe portions is two, The directions of extension of the bending center lines of the two curved pipe sections are perpendicular to each other.

6. 6. The heat exchanger according to claim 1, the cryogenic fluid flowing into the cryogenic flow path is liquid hydrogen or liquefied natural gas; A heat exchanger, wherein the high temperature fluid flowing into the high temperature flow path is gaseous carbon dioxide.

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