Heat exchanger and hydrogen generation device

Abstract

Provided is a heat exchanger capable of maintaining sealing performance despite thermal expansion and contraction. This heat exchanger comprises an outer passage defining member, an inner passage defining member, and a partition member. The inner passage defining member constitutes an inner passage through which a first fluid flows. A space defined by the inner peripheral surface of the outer passage defining member and the outer peripheral surface of the inner passage defining member constitutes an outer passage. The partition member is configured to divide the outer passage into a first space and a second space at an end of the inner passage defining member. A second fluid flows in the first space, and an end of the inner passage defining member protrudes into the second space. The inner passage includes: an inversion part for inverting the flow direction of the first fluid; an upstream passage upstream of the inversion part; and a downstream passage downstream of the inversion part. The length of a first passage, which is one of the upstream passage and the downstream passage, is greater than the length of a second passage, which is the other passage.

Description

Heat exchanger and hydrogen production device

[0001] The present disclosure relates to a heat exchanger and a hydrogen production device.

[0002] For example, Patent Document 1 below describes a device for producing hydrogen from methane. In this device, methane is thermally decomposed into hydrogen and carbon in a reactor. Next, hydrogen is extracted from the mixture of methane and hydrogen flowing out of the reactor by a membrane separation device.

[0003] Japanese Patent Application Laid-Open No. 2019-73411

[0004] By the way, in order to thermally decompose methane in the above reactor, it is necessary to supply a large amount of thermal energy to methane. Therefore, a heat exchanger for heating methane is desired. In addition, since the mixture flowing out of the reactor is at an extremely high temperature, it is necessary to efficiently extract the thermal energy of the mixture in processing the mixture. Therefore, a heat exchanger for extracting heat from the mixture is desired.

[0005] Here, the heat exchanger for heating methane is required to withstand practical use at high temperatures while avoiding mixing of methane and the heating gas. Also, for the heat exchanger for cooling the mixture, it is required to withstand practical use at high temperatures while avoiding mixing of the mixture and the cooling gas.

[0006] The system comprises an outer passage partition member, an inner passage partition member, and a partition member, wherein the inner passage partition member is housed in a space partitioned by the inner circumferential surface of the outer passage partition member and constitutes an inner passage through which a first fluid flows, the space partitioned by the inner circumferential surface of the outer passage partition member and the outer circumferential surface of the inner passage partition member constitutes an outer passage, the partition member is configured to fix the inner passage partition member and divide the outer passage into a first space and a second space at the end of the inner passage partition member, the second fluid flows in the first space and the second space A heat exchanger in which the end of the inner passage partition member protrudes, the inner passage includes a reversal section that reverses the flow direction of the first fluid, an upstream passage upstream of the reversal section, and a downstream passage downstream of the reversal section, wherein the length of the first passage, which is one of the two passages of the upstream passage and the downstream passage, is set to be longer than the length of the other passage, the second passage, and the temperature of the first fluid in the first passage is lower than the temperature of the first fluid in the second passage due to heat exchange between the first fluid and the second fluid.

[0007] In the above configuration, the temperature of the first fluid in the first passage is lower than the temperature of the first fluid in the second passage. Therefore, the amount of thermal expansion per unit length in the flow direction of the first fluid of the inner passage partition member constituting the first passage is smaller than that of the inner passage partition member constituting the second passage. Therefore, by setting the length of the first passage to be longer than the length of the second passage, the amount of thermal expansion in the flow direction of the first fluid of the inner passage partition member constituting the first passage and the inner passage partition member constituting the second passage can be approximated. Thus, the second space can be sealed to the first space regardless of the thermal expansion and contraction of the inner passage partition member.

[0008] This is a block diagram showing the configuration of a hydrogen generator according to the first embodiment. This is a cross-sectional view showing the configuration of a heat exchanger in the hydrogen generator shown in Figure 1. This is a cross-sectional view of the heat exchanger shown in Figure 2, line 3-3. This is an enlarged view of a part of the heat exchanger shown in Figure 2. This is a cross-sectional view showing the configuration of a heat exchanger according to the second embodiment. This is a cross-sectional view of the heat exchanger shown in Figure 5, line 6-6. This is a diagram showing the procedures for maintenance of the heat exchanger shown in Figure 5.

[0009] <First Embodiment> The first embodiment will be described below with reference to the drawings. "Hydrogen Generator" Figure 1 shows the configuration of the hydrogen generator according to this embodiment.

[0010] The compressor 10 is configured to pressurize the raw material gas. The raw material gas is, for example, methane. The methane pressurized by the compressor 10 is thermally decomposed into hydrogen and carbon by reactors 12, 14, and 16. Each of the reactors 12, 14, and 16 is equipped with a device for heating its interior.

[0011] The methane pressurized by the compressor 10 is used not only as a raw material for hydrogen, but also as a heating gas to heat the methane used as a raw material gas. In other words, a portion of the methane pressurized by the compressor 10 is oxidized by compressed air in the combustors 20, 22, and 24 to become a high-temperature combustion gas.

[0012] The hydrogen raw material gas, which is part of the methane pressurized by the compressor 10, is first heated in the heat exchanger 30(1). The heat exchanger 30(1) is configured to exchange heat between the hydrogen-methane mixture that has flowed out of the reactor 16 and the methane. The heat exchanger 30(1) plays a role in cooling the hydrogen-methane mixture that has flowed out of the reactor 16.

[0013] The methane, which is the raw material gas heated by the heat exchanger 30(1), is further heated by the heat exchanger 30(2). The heat exchanger 30(2) is configured to exchange heat between the methane, which is the raw material gas, and the combustion gas produced in the combustor 20. The temperature of the methane heated by the heat exchanger 30(2) is, for example, 500 to 800°C.

[0014] The methane heated by the heat exchanger 30(2) is supplied to the reactor 12. The reactor 12 contains a catalyst to promote the thermal decomposition of methane. Heat is applied to the reactor 12 from around the space containing the catalyst. This may be achieved, for example, by the reactor 12 having a double-tube structure. That is, the reactor 12 may be configured such that, for example, the space containing the catalyst is partitioned by an inner tube, and combustion gas is passed between the outer circumference of the inner tube and the inner circumference of the outer tube. The temperature of the methane and catalyst in the reactor 12 is, for example, 600 to 900°C. A mixture of hydrogen produced by thermal decomposition and methane that has not been thermally decomposed flows out of the reactor 12.

[0015] The mixture flowing out of reactor 12 is heated by heat exchanger 30(3). Heat exchanger 30(3) is configured to exchange heat between the mixture flowing out of reactor 12 and the combustion gas produced in combustor 22. The temperature of the mixture heated in heat exchanger 30(3) is, for example, 500 to 800°C. The mixture heated in heat exchanger 30(3) is supplied to reactor 14. Reactor 14 contains a catalyst to promote the thermal decomposition of methane. Heat is applied to the reactor 14 from around the space containing the catalyst. The temperature of the methane and catalyst in reactor 14 is, for example, 600 to 900°C. A mixture of hydrogen produced by thermal decomposition and methane that has not been thermally decomposed flows out of reactor 14.

[0016] The mixture flowing out of reactor 14 is heated by heat exchanger 30(4). Heat exchanger 30(4) is configured to exchange heat between the mixture flowing out of reactor 14 and the combustion gas produced in combustor 24. The temperature of the mixture heated in heat exchanger 30(4) is, for example, 500 to 800°C. The mixture heated in heat exchanger 30(4) is supplied to reactor 16. Reactor 16 contains a catalyst to promote the thermal decomposition of methane. Heat is applied to reactor 16 from the surrounding space where the catalyst is contained. A mixture of hydrogen produced by thermal decomposition and methane that has not been thermally decomposed flows out of reactor 16.

[0017] "Configuration of Heat Exchanger 30" Figure 2 shows examples of heat exchangers 30(1) to 30(4). In the following, the term "heat exchanger 30" may be used as a general term for heat exchangers 30(1) to 30(4). In Figure 2, the x and y axes are axes parallel to the horizontal plane. The z axis is an axis perpendicular to the horizontal plane. In particular, the positive z-axis direction indicates upward.

[0018] As shown in Figure 2, the heat exchanger 30 includes an outer tube 40. The outer tube 40 is a U-shaped tube formed by bending a straight tube into a U-shape. Multiple heat transfer tubes 50 are housed in the space partitioned by the inner circumferential surface 40a of the outer tube 40. Each of the multiple heat transfer tubes 50 is a U-shaped tube formed by bending a straight tube into a U-shape. The heat transfer tubes 50 include a straight section 52, a bent section 54, and a straight section 56. The straight sections 52 and 56 are arranged parallel to each other in the axial direction. In addition, the portion of the outer tube 40 that faces the straight sections 52 and 56 in the horizontal direction is also arranged perpendicular to its axial direction.

[0019] The heat transfer tube 50 divides the inner passages with its inner surface. Methane flows through the inner passages of heat exchangers 30(1) and 30(2). A mixture of hydrogen and methane flowing out from reactors 12 and 14 flows through the inner passages of heat exchangers 30(3) and 30(4).

[0020] Figure 3 shows a cross-section of line 3-3 in Figure 2. As shown in Figure 3, in this embodiment, as an example, there are seven heat transfer tubes 50(1), 50(2), ... Returning to Figure 2, the outer passage is partitioned by the inner circumferential surface 40a of the outer tube 40 and the outer circumferential surface 50a of the heat transfer tube 50. A partition member 60 is provided at the end of the straight tube section 52 of the heat transfer tube 50. The partition member 60 divides the space partitioned by the inner circumferential surface 40a of the outer tube 40 and the outer circumferential surface 50a of the heat transfer tube 50 into a first space S1 and a second space S2. A partition member 62 is provided at the end of the straight tube section 56 of the heat transfer tube 50. The partition member 62 divides the space partitioned by the inner circumferential surface 40a of the outer tube 40 and the outer circumferential surface 50a of the heat transfer tube 50 into a first space S1 and a second space S2.

[0021] In the first space S1 of heat exchanger 30(1), the mixture flowing out from reactor 16 flows. In the first space S1 of each of heat exchangers 30(2) to 30(4), the combustion gas generated in each of the combustors 20 to 24 flows.

[0022] The ends of the heat transfer tube 50 are fixed by partition members 60 and 62. Thus, the heat transfer tube 50 is suspended by the partition members 60 and 62. Figure 4 shows an enlarged view of the area around partition member 60. Note that the configuration of partition member 62 is the same as that of partition member 62, so its explanation is omitted.

[0023] As shown in Figure 4, the partition member comprises plate-shaped members 60a and 60b. The plate-shaped member 60a has multiple holes into which each of the multiple heat transfer tubes 50 is inserted. Each of the multiple heat transfer tubes 50 is inserted into its assigned hole. Each of the multiple heat transfer tubes 50 is fixed to the plate-shaped member 60a by welding around the entire circumference of the hole. The plate-shaped member 60b is connected to the plate-shaped member 60a without any gaps around the entire circumference of its edge. The outer circumference of the plate-shaped member 60b is connected without any gaps to the cross section of the inner circumferential surface 40a of the outer tube 40 parallel to the y and z axes. With this configuration, the partition member 60 seals the first space S1 from the second space S2.

[0024] Returning to Figure 2, the outer tube 40 has an inlet / outlet compartment 42 near the partition member 60. The outer tube 40 also has an inlet / outlet compartment 44 near the partition member 62. In the heat exchanger 30(1), the inlet / outlet compartment 42 constitutes the inlet for the mixed gas flowing out of the reactor 16. In the heat exchanger 30(1), the inlet / outlet compartment 44 defines the outlet for the mixed gas flowing out of the reactor 16. On the other hand, in the heat exchanger 30(1), the end of the heat transfer tube 50 that protrudes from the partition member 60 into the second space S2 constitutes the outlet for methane. Also, in the heat exchanger 30(1), the end of the heat transfer tube 50 that protrudes from the partition member 62 into the second space S2 constitutes the inlet for methane.

[0025] In the heat exchanger 30(2), the inlet / outlet compartment 42 constitutes the inlet for the combustion gas generated in the combustor 20. In the heat exchanger 30(2), the inlet / outlet compartment 44 defines the outlet for the combustion gas generated in the combustor 20. On the other hand, in the heat exchanger 30(2), the end of the heat transfer tube 50 that protrudes from the partition member 60 into the second space S2 constitutes the outlet for methane. Also, in the heat exchanger 30(2), the end of the heat transfer tube 50 that protrudes from the partition member 62 into the second space S2 constitutes the inlet for methane.

[0026] In the heat exchanger 30(3), the inlet / outlet compartment 42 constitutes the inlet for the combustion gas generated in the combustor 22. In the heat exchanger 30(3), the inlet / outlet compartment 44 defines the outlet for the combustion gas generated in the combustor 22. On the other hand, in the heat exchanger 30(3), the end of the heat transfer tube 50 that protrudes from the partition member 60 into the second space S2 constitutes the outlet for the hydrogen-methane mixture flowing out of the reactor 12. Also, in the heat exchanger 30(3), the end of the heat transfer tube 50 that protrudes from the partition member 62 into the second space S2 constitutes the inlet for the hydrogen-methane mixture flowing out of the reactor 12.

[0027] In the heat exchanger 30(4), the inlet / outlet compartment 42 constitutes the inlet for the combustion gas generated in the combustor 24. In the heat exchanger 30(4), the inlet / outlet compartment 44 constitutes the outlet for the combustion gas generated in the combustor 24. On the other hand, in the heat exchanger 30(4), the end of the heat transfer tube 50 that protrudes from the partition member 60 into the second space S2 constitutes the outlet for the hydrogen-methane mixture flowing out of the reactor 14. Also, in the heat exchanger 30(4), the end of the heat transfer tube 50 that protrudes from the partition member 62 into the second space S2 constitutes the inlet for the hydrogen-methane mixture flowing out of the reactor 14.

[0028] "Operation and Effects of This Embodiment" For example, in the heat exchanger 30(1), the mixed gas flowing out from the reactor 16 flows into the first space S1 through the space partitioned by the inlet / outlet compartment 42, and then heats the methane in the heat transfer tube 50. The mixed gas then flows out to the outside through the space partitioned by the inlet / outlet compartment 44. On the other hand, in the heat exchanger 30(1), the raw material methane flows into the internal passage partitioned by the heat transfer tube 50 from the end of the heat transfer tube 50 that protrudes from the partition member 62 into the second space S2. The methane then receives heat from the mixed gas as it flows through the internal passage. The methane then flows out of the heat transfer tube from the end of the heat transfer tube 50 that protrudes from the partition member 60 into the second space S2.

[0029] Therefore, the temperature of methane is higher downstream of the heat transfer tube 50 compared to upstream of the heat transfer tube 50. Due to the temperature difference of the methane, the amount of expansion per unit length in the flow direction of methane is greater in the straight tube section 52 than in the straight tube section 56. In this embodiment, the length L2 of the straight tube section 56 is longer than the length L1 of the straight tube section 52. This reduces the difference between the amount of thermal expansion of the straight tube section 52 and the amount of thermal expansion of the straight tube section 56. It is desirable to set the length L1 of the straight tube section 52 and the length L2 of the straight tube section 56 to values ​​such that the amount of thermal expansion of the straight tube section 52 and the amount of thermal expansion of the straight tube section 56 are equal at the normal operating temperature of the heat exchanger 30(1).

[0030] As described above, the following effects and advantages can be obtained with respect to this embodiment: (1) Multiple heat transfer tubes 50 are housed in the first space S1. Therefore, compared to the case where the same volume is secured by multiple heat transfer tubes 50 with a single heat transfer tube 50, the surface area of ​​the heat transfer tubes 50 can be increased. Therefore, the heat exchange efficiency between the fluid inside the heat transfer tubes 50 and the fluid in the first space S1 can be increased.

[0031] Furthermore, since the multiple heat transfer tubes 50 are independent of each other, they can be easily displaced freely. Therefore, the difference between the amount of thermal expansion of the straight tube section 52 and the amount of thermal expansion of the straight tube section 56 can be easily absorbed by the slight deformation of the heat transfer tubes 50.

[0032] (2) The axial directions of the straight pipe sections 52 and 56 are positioned vertically. This suppresses bending of the straight pipe sections 52 and 56 due to the action of gravity. Note that "the axial directions of the straight pipe sections 52 and 56 are positioned vertically" refers to the arrangement when the pipes are at a predetermined temperature, such as room temperature. That is, if the actual temperature changes from the predetermined temperature, a difference will occur between the amount of expansion of the straight pipe section 52 and the amount of expansion of the straight pipe section 56, and the heat transfer tube 50 will deform slightly to compensate for this difference. This deformation may cause the axial directions of the straight pipe sections 52 and 56 to deviate from the vertical direction.

[0033] (3) Entrance and exit partitions 42 and 44 are provided at both ends of the first space S1. This ensures that the entrance and exit of the first space S1 can be secured without interfering with the entrance and exit of the heat transfer tube 50. <Second Embodiment> The second embodiment will be described below, with reference to the drawings, focusing on the differences from the first embodiment.

[0034] Figure 5 shows a heat exchanger 30 according to this embodiment. In Figure 5, the same reference numerals are used for members corresponding to those shown in Figure 2 for convenience. As shown in Figure 5, the heat transfer tube 50 of this embodiment includes a straight tube 52a, a confluence section 54a, and a straight tube 56a. The confluence section 54a is a part that reverses the flow direction of fluid flowing out of either the straight tube 52a or the straight tube 56a and allows it to flow into the other.

[0035] Here, the first space S1 contains multiple straight pipes 52a and 56a. The junction 54a is the part where the internal passages formed by the multiple straight pipes 52a and 56a are joined together.

[0036] Figure 6 shows the 6-6 cross-section of Figure 5. "Operation and Effects of this Embodiment" Due to the deterioration of the heat transfer tubes 50 over time, there may be a need to replace a part of the heat transfer tubes 50. In that case, as shown in Figure 7, the bent portion 46 of the outer tube 40 is removed. The exposed junction portion 54a is then removed from the straight tubes 52a and 56a. This makes it easy to remove the straight tubes 52a and 56a. In other words, the replacement work of the heat transfer tubes 50 can be carried out while keeping the space partitioned by the inner circumferential surface 40a of the outer tube 40 as small as possible.

[0037] <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the "Notes" column below is as follows. Below, the correspondence is shown for each solution number described in the "Notes" column. [1] The outer passage partition member corresponds to the outer pipe 40. The inner passage partition member corresponds to the heat transfer tube 50. The partition members correspond to the partition members 60 and 62. The reversal section corresponds to the bend 54 and the junction 54a. The first passage corresponds to the passage in the straight pipe section 56 in Figure 2 and the passage in the straight pipe 56a in Figure 6. The second passage corresponds to the passage in the straight pipe section 52 in Figure 2 and the passage in the straight pipe 52a in Figure 6. [2] The matters relating to solution 2 correspond to the fact that the heat transfer tubes 50 exemplified in Figure 2 are independent of each other. [3] The junction corresponds to the junction 54a. [4] The matters described in solution 4 correspond to the layouts described in Figures 2 and 5. [5] The matters described in Solution 5 correspond to the entrance and exit compartments 42 and 44. [6] Heat exchanger 30 corresponds to heat exchanger 30(1) and 30(2). [7] The first reactor and the second reactor correspond to reactors 12 and 14 or reactors 14 and 16, respectively. [8] Heat exchanger corresponds to heat exchanger 30(1).

[0038] <Other Embodiments> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0039] Regarding the outer passage partition member: The outer passage partition member is not limited to an outer tube 40 having a cylindrical shape. For example, it may be a rectangular parallelepiped-shaped member in which holes for housing the heat transfer tubes 50 are formed inside.

[0040] Regarding the inner passage partition member: The inner passage partition member does not necessarily have to be a cylindrical member. For example, the inner passage partition member may be a member with multiple protrusions on its outer surface.

[0041] - When arranging heat transfer tubes 50 in parallel, the number of heat transfer tubes 50 is not limited to seven. For example, the number of heat transfer tubes 50 may be six or less. Also, for example, the number of heat transfer tubes 50 may be eight or more. Note that arranging multiple heat transfer tubes 50 in parallel is not mandatory.

[0042] Regarding the first fluid, second fluid, first passage and second passage: In the heat exchanger 30(1), the inlet for the methane-hydrogen mixture flowing out of the reactor 16 may be on the inlet / outlet compartment 44 side.

[0043] - In the heat exchanger 30(1), a mixture of methane and hydrogen flowing out from the reactor 16 may be flowed into the heat transfer tubes 50. In other words, the first fluid in the heat exchanger 30(1) may be a mixture. In this case, the mixture is introduced from the end of the heat transfer tubes 50 closest to the partition member 60. Also, the inlet for methane into the heat exchanger 30(1) may be the inlet / outlet compartment 42. Alternatively, for example, the inlet for methane into the heat exchanger 30(1) may be the inlet / outlet compartment 44.

[0044] - In the heat exchanger 30(2), the inlet of the combustion gas generated in the combustor 20 may be on the side of the inlet / outlet partition section 44. - In the heat exchanger 30(2), the combustion gas may be made to flow in the heat transfer tube 50. In other words, in the heat exchanger 30(2), the first fluid may be the combustion gas. In this case, the combustion gas is made to flow in from the end portion of the heat transfer tube 50 closer to the partition member 60. Also, the inlet of methane into the heat exchanger 30(2) may be the inlet / outlet partition section 42. For example, the inlet of methane into the heat exchanger 30(2) may also be the inlet / outlet partition section 44.

[0045] - In the heat exchanger 30(3), the inlet of the combustion gas generated in the combustor 22 may be on the side of the inlet / outlet partition section 44. - In the heat exchanger 30(3), the combustion gas may be made to flow in the heat transfer tube 50. In other words, in the heat exchanger 30(3), the first fluid may be the combustion gas. In this case, the combustion gas is made to flow in from the end portion of the heat transfer tube 50 closer to the partition member 60. Also, the inlet of the mixture of methane and hydrogen into the heat exchanger 30(3) may be the inlet / outlet partition section 42. For example, the inlet of the mixture into the heat exchanger 30(3) may also be the inlet / outlet partition section 44.

[0046] - In the heat exchanger 30(4), the inlet of the combustion gas generated in the combustor 22 may be on the side of the inlet / outlet partition section 44. - In the heat exchanger 30(4), the combustion gas may be made to flow in the heat transfer tube 50. In other words, in the heat exchanger 30(4), the first fluid may be the combustion gas. In this case, the combustion gas is made to flow in from the end portion of the heat transfer tube 50 closer to the partition member 60. Also, the inlet of the mixture of methane and hydrogen into the heat exchanger 30(4) may be the inlet / outlet partition section 42. For example, the inlet of the mixture into the heat exchanger 30(4) may also be the inlet / outlet partition section 44.

[0047] "Regarding the axial direction of the heat transfer tube 50" - Regarding the portion of the heat transfer tube 50 where the axial direction does not change, the axial direction is not limited to the vertical direction. The coaxial direction may be, for example, a direction that intersects obliquely with respect to the horizontal direction.

[0048] "Regarding Hydrocarbons" - It is not essential that the hydrocarbon gas is methane. For example, it may be propane. In that case, the substances flowing out from the pyrolysis device include, in addition to hydrogen and carbon, methane, ethylene, propane, etc.

[0049] "Regarding Hydrogen Generation Device" - It is not essential that the hydrogen generation device has a structure in which three reactors 12, 14, and 16 are connected in series. The hydrogen generation device may have a structure in which two reactors or four or more reactors are connected in series.

[0050] - It is not essential that the hydrogen generation device has a structure in which a plurality of reactors are connected in series. The hydrogen generation device may include, for example, only a single reactor. Also, for example, the hydrogen generation device may have a structure in which a plurality of reactors are connected in parallel.

[0051] - It is not essential that the fuel of the combustor is the same hydrocarbon as the raw material gas of hydrogen, such as methane. For example, the generated hydrogen may be used. <Supplementary Note> Solution 1. An outer passage partitioning member, an inner passage partitioning member, and a partitioning member are provided. The inner passage partitioning member is accommodated in a space partitioned by the inner peripheral surface of the outer passage partitioning member and constitutes an inner passage through which a first fluid flows. The space partitioned by the inner peripheral surface of the outer passage partitioning member and the outer peripheral surface of the inner passage partitioning member constitutes an outer passage. The partitioning member is configured to fix the inner passage partitioning member and divide the outer passage into a first space and a second space at an end of the inner passage partitioning member. A second fluid flows in the first space. An end of the inner passage partitioning member protrudes into the second space. The inner passage includes an inversion portion that reverses the flow direction of the first fluid, an upstream passage upstream of the inversion portion, and a downstream passage downstream of the inversion portion. The length of a first passage, which is any one of the two passages of the upstream passage and the downstream passage, is set to be longer than the length of the other passage, which is a second passage. A heat exchanger in which the temperature of the first fluid in the first passage is lower than the temperature of the first fluid in the second passage due to heat exchange between the first fluid and the second fluid.

[0052] In the above configuration, the temperature of the first fluid in the first passage is lower than the temperature of the first fluid in the second passage. Therefore, the amount of thermal expansion per unit length in the flow direction of the first fluid of the inner passage partition member constituting the first passage is smaller than that of the inner passage partition member constituting the second passage. Therefore, by setting the length of the first passage to be longer than the length of the second passage, the amount of thermal expansion in the flow direction of the first fluid of the inner passage partition member constituting the first passage and the inner passage partition member constituting the second passage can be approximated. Thus, the second space can be sealed to the first space regardless of the thermal expansion and contraction of the inner passage partition member.

[0053] Solution 2. The heat exchanger according to claim 1 above, wherein the inner passage partitioning member comprises members that partition a plurality of inner passages, and the plurality of inner passages are configured independently of each other. In the above configuration, by providing a plurality of inner passages, the area of ​​the outer surface of the inner passage partitioning member that comes into contact with the second fluid can be increased compared to the case where the same volume is obtained by a single inner passage and a plurality of inner passages. Therefore, the heat exchange efficiency between the first fluid and the second fluid can be increased.

[0054] Furthermore, in the above configuration, since the multiple inner passages are independent of each other, the inner passage partition members that demarcate each of these inner passages can easily be displaced freely from one another. Therefore, it is easy to absorb the difference in the amount of thermal expansion in the flow direction of the first fluid between the inner passage partition members constituting the first passage and the inner passage partition members demarcating the second passage.

[0055] Solution 3. The heat exchanger according to claim 1, wherein the inner passage partitioning member comprises a member that partitions a plurality of inner passages, each of the plurality of inner passages comprises an upstream passage and a downstream passage partitioned by a straight pipe, and the reversing section constitutes a junction where the plurality of upstream passages and the plurality of downstream passages merge.

[0056] In the above configuration, the inner passage partition member can be replaced by removing the junction from the straight pipe and then removing the straight pipe. Therefore, the space partitioned by the inner circumferential surface of the outer passage partition member can be kept as small as possible while still allowing the replacement of the inner passage partition member to be carried out.

[0057] Solution 4. A heat exchanger according to any one of 1 to 3 above, wherein the inner passage partition member is fixed in such a way that it is suspended by the partition member. In the above configuration, compared to the case where the flow direction of the first fluid in the upstream and downstream passages is horizontal, the bending of the inner passage partition member due to the action of gravity can be suppressed.

[0058] Solution 5. The heat exchanger according to any one of 1 to 4 above, wherein the outer passage partitioning member comprises inlet / outlet partitioning portions that constitute the inlet / outlet of the second fluid at both ends of the first space. In the above configuration, the inlet / outlet of the second fluid can be secured without interfering with the inlet / outlet of the first fluid.

[0059] Solution 6. A hydrogen production apparatus comprising a heat exchanger and a reactor as described in any one of 1 to 5 above, wherein the reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, one of the two first fluids and the second fluid is the hydrocarbon, the other of the two first fluids and the second fluid is a high-temperature gas for heating the hydrocarbon, and the hydrocarbon heated by the heat exchanger is supplied to the reactor.

[0060] In the above configuration, the hydrocarbons in the reactor are required to be at a high temperature. In contrast, the above configuration allows the temperature of the hydrocarbons supplied to the reactor to be increased by the heat exchanger. However, in that case, the components inside the heat exchanger become hot. Therefore, the thermal expansion and contraction of the inner passage compartment members makes it difficult to maintain sealing performance. For this reason, the value of setting the lengths of the first and second passages is particularly great.

[0061] Solution 7. A hydrogen generation apparatus comprising a heat exchanger described in any one of 1 to 5 above, a first reactor, and a second reactor, wherein the first reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, the second reactor is configured to decompose hydrocarbons in a fluid discharged from the first reactor into hydrogen and carbon by a thermal decomposition reaction, one of the two fluids, the first fluid and the second fluid, is the fluid discharged from the first reactor, the other of the two fluids, is a high-temperature gas for heating the fluid discharged from the first reactor, and the fluid heated by the heat exchanger is supplied to the second reactor.

[0062] In the above configuration, the fluid supplied to the second reactor can be heated by the heat exchanger. However, in this case, the components inside the heat exchanger become hot. As a result, thermal expansion and contraction of the inner passage partition members makes it difficult to maintain sealing performance. Therefore, the value of setting the lengths of the first and second passages is particularly significant.

[0063] Solution 8. A hydrogen generation apparatus comprising a heat exchanger and a reactor as described in any one of 1 to 5 above, wherein the reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, and either the first fluid or the second fluid is the hydrocarbon supplied to the reactor, and the other of the first fluid or the second fluid is the fluid flowing out of the reactor.

[0064] In the above configuration, when cooling the fluid flowing out of the reactor, the heat absorbed from the fluid flowing out of the reactor can be effectively used to heat the hydrocarbon supplied to the reactor. However, in this case, the components inside the heat exchanger become hot. Therefore, the thermal expansion and contraction of the inner passage compartment members makes it difficult to maintain sealing performance. For this reason, the value of setting the lengths of the first and second passages is particularly significant.

Claims

1. The apparatus comprises an outer passage partition member, an inner passage partition member, and a partition member, wherein the inner passage partition member is housed in a space partitioned by the inner circumferential surface of the outer passage partition member and constitutes an inner passage through which a first fluid flows, the space partitioned by the inner circumferential surface of the outer passage partition member and the outer circumferential surface of the inner passage partition member constitutes an outer passage, the partition member is configured to fix the inner passage partition member and divide the outer passage into a first space and a second space at the end of the inner passage partition member, a second fluid flows in the first space, the end of the inner passage partition member protrudes into the second space, the inner passage includes a reversal section that reverses the flow direction of the first fluid, an upstream passage upstream of the reversal section, and a downstream passage downstream of the reversal section, the length of the first passage, which is one of the two passages of the upstream passage and the downstream passage, is set to be longer than the length of the second passage, which is the other passage. A heat exchanger in which the temperature of the first fluid in the first passage is lower than the temperature of the first fluid in the second passage due to heat exchange between the first fluid and the second fluid.

2. The heat exchanger according to claim 1, wherein the inner passage partitioning member comprises members that partition a plurality of inner passages, and the plurality of inner passages are configured independently of each other.

3. The heat exchanger according to claim 1, wherein the inner passage partitioning member comprises a member that partitions a plurality of inner passages, each of the plurality of inner passages comprises an upstream passage and a downstream passage partitioned by a straight pipe, and the reversing section constitutes a merging section where the plurality of upstream passages and the plurality of downstream passages merge.

4. The heat exchanger according to claim 1, wherein the inner passage partition member is fixed in such a manner that it is suspended by the partition member.

5. The heat exchanger according to claim 1, wherein the outer passage partitioning member comprises inlet and outlet partitioning portions that constitute the inlet and outlet of the second fluid at both ends of the first space.

6. A hydrogen production apparatus comprising a heat exchanger and a reactor according to claim 1, wherein the reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, one of the two fluids, the first fluid and the second fluid, is the hydrocarbon, the other of the two fluids, is a high-temperature gas for heating the hydrocarbon, and the hydrocarbon heated by the heat exchanger is supplied to the reactor.

7. A hydrogen generation apparatus comprising a heat exchanger according to claim 1, a first reactor, and a second reactor, wherein the first reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, the second reactor is configured to decompose hydrocarbons in a fluid discharged from the first reactor into hydrogen and carbon by a thermal decomposition reaction, either the first fluid or the second fluid is the fluid discharged from the first reactor, the other of the first fluid or the second fluid is a high-temperature gas for heating the fluid discharged from the first reactor, and the hydrogen generation apparatus is configured such that the fluid heated by the heat exchanger is supplied to the second reactor.

8. A hydrogen generation apparatus comprising a heat exchanger and a reactor according to claim 1, wherein the reactor is configured to decompose hydrocarbons into hydrogen and carbon by a thermal decomposition reaction, and either the first fluid or the second fluid is the hydrocarbon supplied to the reactor, and the other of the first fluid or the second fluid is a fluid flowing out of the reactor.

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