Compressor unit

Abstract

The compressor unit includes a compression section that compresses the boil-off gas, i.e., hydrogen, from the liquid hydrogen storage tank. The compression section includes: a cylinder portion; a piston; a piston rod connecting the piston to the crank mechanism; a cover part disposed on the outside of the cylinder part; a nitrogen gas supply unit that supplies nitrogen gas to a heat-insulating space between the cover unit and the cylinder unit; and a control unit that controls the nitrogen gas supply unit such that nitrogen gas is supplied into the heat-insulating space while the hydrogen gas is compressed by the compression section.

Description

Technical Field

[0001] This invention relates to reciprocating compressor units. Background Technology

[0002] In recent years, research has been conducted on using hydrogen as a fuel for power generation and automobiles, driven by environmental concerns, leading to an increasing demand for hydrogen. Furthermore, conventional methods utilize compressors to recover low-temperature boil-off gases (BOG) such as liquefied natural gas (LNG) and liquid hydrogen (LH2) for supply to power generation and other demand-side applications. In particular, the boil-off gas produced from LH2 has an extremely low temperature. Therefore, if a structure is used where the compressor directly draws in the boil-off gas, it requires the selection of materials suitable for extremely low temperatures, or design conditions that take into account thermal deformation, or the implementation of stringent insulation measures, which presents limitations.

[0003] Patent Document 1 points out the following problem: "In recent years, hydrogen has received much attention as a new energy source. It is envisioned that hydrogen, when used as an energy source, will be stored and transported in a liquefied state, just like natural gas. However, hydrogen has the characteristic that its liquefaction temperature is lower than that of air. Therefore, if equipment such as reciprocating compressors designed for natural gas is directly applied to hydrogen, adverse conditions may occur due to the extremely low temperature of the liquid hydrogen. For example, liquefied air may be generated around the device that supplies liquid hydrogen and its evaporated gas." As mentioned above, the issue of preventing adverse conditions caused by extremely low-temperature liquid hydrogen is being studied. Specifically, a container section is formed around the compression section to create a vacuum region. However, to maintain the vacuum state, sealing units are required in the container section for the cover used for internal inspection and the connection between the gas entering and exiting the compression section. Furthermore, since the inside of the container section is a vacuum state, the necessary strength (plate thickness) and reinforcement are required to withstand the pressure difference between the external pressure (atmospheric pressure) and the internal pressure. This sacrifices maintainability. In addition, various measures are needed, such as installing a base for supporting the working cylinder inside the container section.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2020-172870. Summary of the Invention

[0005] The main objective of this invention is to eliminate oxygen liquefaction, where oxygen is one of the main components of air and also a combustion-supporting gas. Another objective of this invention is to facilitate maintenance in reciprocating compressors.

[0006] One aspect of the present invention relates to a reciprocating compressor unit that recovers evaporated gas, i.e., hydrogen, from a liquid hydrogen storage tank and supplies at least a portion of the hydrogen to a demander including at least one of an engine, a power generation device, and a boiler. The compressor unit includes: a compression section configured to compress hydrogen flowing from the liquid hydrogen storage tank and flowing in an intake path; and a crank mechanism configured to drive the compression section. The compression section includes: a cylinder; a piston; a cover disposed outside the cylinder; a nitrogen supply section configured to supply nitrogen to an insulating space between the cover and the cylinder; and a nitrogen discharge section configured to discharge nitrogen from the insulating space. The compressor unit further includes: a control section configured to control the nitrogen supply section such that nitrogen is supplied to the insulating space during the compression of hydrogen in the compression section. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the structure of the compressor unit according to the first embodiment.

[0008] Figure 2 This is a schematic diagram showing the structure of the compressor unit involved in a variation of the first embodiment.

[0009] Figure 3 This is a schematic diagram illustrating the structure of a compressor unit involved in other variations of the first embodiment.

[0010] Figure 4 This is a schematic diagram showing the structure of the compressor unit involved in the second embodiment.

[0011] Figure 5 This is a schematic diagram illustrating the structure of the compressor unit involved in a variation of the second embodiment. Detailed Implementation

[0012] Hereinafter, embodiments will be described with reference to the accompanying drawings. Furthermore, the following embodiments are merely examples embodying the present invention and do not limit the scope of the invention.

[0013] (First Embodiment) The compressor unit according to this embodiment recovers boil-off gas, i.e., hydrogen, from a liquid hydrogen storage tank, compresses the recovered hydrogen, and supplies it to the demand side. Therefore, hydrogen supply can be performed efficiently. The hydrogen, i.e., the boil-off gas, is approximately -253°C. The demand side includes at least one of an engine, a power generation facility, and a boiler. However, in addition to these, the demand side may also include, for example, equipment other than gas combustion equipment, flame equipment, exhaust ports, etc., that "utilize gas as an energy source." Furthermore, the hydrogen discharged from the compressor unit does not necessarily need to be directly supplied to the demand side. Therefore, for example, it can be filled into a gas storage tank and then supplied to the demand side by various means, such as transporting the gas storage tank or using gas piping connected to the gas storage tank.

[0014] like Figure 1 As shown, the compressor unit 10 includes: a compression section 12 for compressing hydrogen; and a crank mechanism 14 for driving the compression section 12. The hydrogen compressed in the compression section 12 is discharged into a discharge path 18. The hydrogen compressed in the compression section 12 and flowing through the discharge path 18 is supplied to a demand side (not shown).

[0015] Alternatively, a subsequent compression section (not shown) can be provided on the discharge side of compression section 12. In this case, the hydrogen gas, after being compressed in compression section 12 and further compressed in the subsequent compression section, is sent to the demand side.

[0016] The compression section 12 is connected to the liquid hydrogen storage tank 23 via the suction flow path 21. Therefore, the liquefied gas, i.e., the vaporized gas (BOG), generated in the liquid hydrogen storage tank 23 is drawn into the compression section 12 through the suction flow path 21. In addition, the suction flow path 21 does not need to be directly connected to the liquid hydrogen storage tank 23; it is sufficient to allow the vaporized gas generated in the liquid hydrogen storage tank 23 to flow.

[0017] The compression section 12 includes a reciprocating compression mechanism. Specifically, the compression section 12 includes: a cylinder 31; a piston 32 disposed within the cylinder 31; and a piston rod 33 connected to the piston 32. The piston rod 33 is connected to a crank mechanism 14. Hydrogen gas is compressed within the compression chamber 34 of the cylinder 31 by the reciprocating movement of the piston 32 within the cylinder 31.

[0018] The compression section 12 can be a transversely positioned type where the piston 32 slides horizontally. In this case, the suction valve 21a, located between the portion of the cylinder 31 connecting the suction flow path 21 and the compression chamber 34, is positioned upwards in the direction of gravity, while the discharge valve 18a, located between the compression chamber 34 and the portion of the cylinder 31 connecting the discharge flow path 18, is positioned downwards in the direction of gravity. Alternatively, the compression section 12 can also be a longitudinally positioned type where the piston 32 slides vertically.

[0019] Although Figure 1 The diagram shows a double-acting compression section 12, but a single-acting compression section 12 can also be used. Furthermore, the compression section 12 does not necessarily need to be a single-cylinder structure; it can also be a structure with multiple compression units connected in parallel. That is, the compression section 12 can be configured such that hydrogen gas is compressed and pressurized by pistons 32 in multiple cylinder sections 31 connected in parallel.

[0020] A cover portion 25 is disposed on the outer side of the cylinder portion 31 in such a way that a space is formed between the cover portion 31 and the cylinder portion 31. In this embodiment, the cover portion 25 includes an outer cylindrical member 26 that forms a space between the cover portion 31 and the cylinder portion 31 by being fixed to the cylinder portion 31.

[0021] The outer cylinder component 26 is formed using a non-deformable component such as a metal component. The outer cylinder component 26 is mounted to the cylinder portion 31, forming a space of a specified size around the cylinder portion 31. Nitrogen gas is introduced into this space as described later. Therefore, this space functions as a heat-insulating space 28 to eliminate oxygen around the cylinder portion 31 and isolate it from heat from the outside air (atmosphere). That is, by providing a heat-insulating space 28 around the portion forming the compression chamber 34, it is possible to prevent oxygen in the outside air from liquefying around the cylinder portion 31. Because the outer cylinder component 26 is made of a non-deformable component, the shape of the heat-insulating space 28 is maintained at a specified shape.

[0022] The outer cylinder member 26 is, for example, mounted on the rear cover 31a, which is part of the cylinder section 31. However, the outer cylinder member 26 does not need to be fixed to the rear cover 31a; it can be mounted on any part of the cylinder section 31 as long as it can form a heat insulation space 28.

[0023] The outer cylinder member 26 has openings through which the pipe forming the discharge flow path 18 (connected to the cylinder section 31) passes, and also has openings through which the pipe forming the suction flow path 21 (connected to the cylinder section 31) passes. Gaps and / or holes (hereinafter referred to as "leakage portions 29") are intentionally provided between these pipes and the openings. Furthermore, the outer cylinder member 26 also has an opening (not shown) through which the support member of the cylinder section 31 passes. Leakage portions 29 are also intentionally provided between the support member and the opening. In the compression section 12, these leakage portions 29, together with the discharge channel section 48 described later, function as nitrogen discharge portions for discharging nitrogen from the interior of the insulation space 28. Alternatively, other leakage portions (not shown) may be added to the outer cylinder member 26 to properly discharge the internal nitrogen.

[0024] The compression section 12 includes: a rod seal portion 36 disposed in the cylinder portion 31; a hollow adapter portion 37 disposed adjacent to and connected to the cylinder portion 31; and a crankcase 38 that houses a portion of the crank mechanism 14, namely the crankshaft.

[0025] The coupling portion 37 is formed in a cylindrical shape, and a piston rod 33 is disposed within the space of the coupling portion 37. One end of the coupling portion 37 in the longitudinal direction is connected to the cylinder portion 31. The other end of the coupling portion 37 in the longitudinal direction is connected to the crankcase 38. A partition wall 40 is provided at this other end to separate the internal space of the coupling portion 37 from the space within the crankcase 38.

[0026] The rod seal portion 36 is fixed to the rear cover 31a. The rod seal portion 36 is provided to prevent hydrogen gas in the compression chamber 34 from leaking from the cylinder portion 31 through the gap between the rear cover 31a and the piston rod 33.

[0027] The coupling part 37 includes a partition 44 that divides the internal space into a space on the side of the compression chamber 34 (first space 37a) and a space on the side of the crank mechanism 14 (second space 37b). The piston rod 33 also passes through the partition 44. A sealing part 44a is provided around the periphery of the through hole through which the piston rod 33 passes in the partition 44.

[0028] The compression section 12 includes a nitrogen supply unit 46 that supplies nitrogen to the insulation space 28. The nitrogen supply unit 46 has a supply passage 46a fixed to the outer cylinder member 26 with an opening into the insulation space 28; and a valve, i.e., a supply valve 46b, disposed in the supply passage 46a. The supply passage 46a is connected to a nitrogen source 47, from which nitrogen is supplied. The supply valve 46b is, for example, an on-off valve that opens and closes based on commands from the control unit 50 described later.

[0029] The compression section 12 includes a discharge passage 48 for discharging nitrogen gas from the insulation space 28. The discharge passage 48 has a discharge pipe 48a fixed to the outer cylinder member 26 with an opening into the insulation space 28, and a valve, i.e., a discharge valve 48b, disposed on the discharge pipe 48a. The discharge pipe 48a can be open to the atmosphere or connected to a schematic tank with an internal pressure equivalent to atmospheric pressure. The discharge pipe 48a also functions as a pressure equalization unit to make the insulation space 28 substantially equal to atmospheric pressure. Additionally, the leakage section 29 is also part of the pressure equalization unit.

[0030] The discharge valve 48b is formed, for example, by a switch valve that opens and closes based on instructions from the control unit 50 described later. Alternatively, the discharge valve 48a may be omitted.

[0031] The compression section 12 includes a hydrogen supply section 59 that supplies hydrogen to a first space 37a within the coupling section 37, and a nitrogen supply section 60 that supplies nitrogen to a second space 37b within the coupling section 37. Specifically, the hydrogen supply section 59 supplies hydrogen to the space closest to the compression chamber 34 among the plurality of spaces in the coupling section 37. Therefore, hydrogen is present in the space closest to the compression chamber 34 during the operation of the compression section 12. Furthermore, the nitrogen supply section 60 supplies nitrogen to the space closest to the crank mechanism 14 among the plurality of spaces in the coupling section 37. Therefore, nitrogen is present in the space closest to the crank mechanism 14 during the operation of the compression section 12.

[0032] The hydrogen supply unit 59 has a hydrogen flow path 59a connected to the hydrogen source 61. The hydrogen source 61 contains hydrogen at room temperature. The hydrogen flow path 59a is connected to the outer peripheral wall of the first space 37a formed in the connector section 37. The hydrogen supply unit 59 supplies hydrogen from the hydrogen source 61 to the first space 37a within the connector section 37 through the hydrogen flow path 59a. Therefore, it can be said that the temperature of the hydrogen in the first space 37a is higher than the liquefaction temperature of nitrogen in the second space 37b.

[0033] The nitrogen supply unit 60 has a nitrogen flow path 60a connected to the nitrogen source 62. The nitrogen flow path 60a is connected to the outer peripheral wall of the junction section 37 where the second space 37b is formed. The nitrogen supply unit 60 supplies nitrogen from the nitrogen source 62 into the second space 37b within the junction section 37 through the nitrogen flow path 60a. The nitrogen source 62 contains nitrogen at room temperature.

[0034] A hydrogen valve, namely hydrogen valve 59b, is provided in the hydrogen supply section 59 hydrogen flow path 59a to adjust the pressure of the hydrogen flowing through the hydrogen flow path 59a. A nitrogen valve, namely nitrogen valve 60b, is provided in the nitrogen flow path 60a to adjust the pressure of the nitrogen flowing through the nitrogen flow path 60a.

[0035] The hydrogen in the first space 37a and the nitrogen in the second space 37b are discharged to the exhaust port 70. In addition, the hydrogen in the first space 37a and the nitrogen in the second space 37b can be recovered into designated tanks, or they can be returned to the hydrogen source 61 and the nitrogen source 62, respectively.

[0036] Supply valve 46b and discharge valve 48b are communicatively connected to control unit 50. Control unit 50 controls supply valve 46b and discharge valve 48b as follows: when crank mechanism 14 drives piston 32, supply valve 46b and discharge valve 48b are opened; when piston 32 stops, supply valve 46b and discharge valve 48b are closed. That is, control unit 50 controls the opening of supply valve 46b and discharge valve 48b based on signals for driving crank mechanism 14.

[0037] Furthermore, hydrogen valve 59b and nitrogen valve 60b are communicatively connected to control unit 50. Control unit 50 controls hydrogen valve 59b and nitrogen valve 60b as follows: when driving piston 32, hydrogen valve 59b and nitrogen valve 60b are opened; when piston 32 stops, hydrogen valve 59b and nitrogen valve 60b are closed.

[0038] Here, the operation of the compressor unit 10 is explained. In the compressor unit 10, if the crank mechanism 14 is working, the piston 32 is working, and the evaporated gas, i.e., hydrogen, is drawn into the compression chamber 34 from the suction flow path 21 for hydrogen compression.

[0039] During the operation of the crank mechanism 14, the supply valve 46b, discharge valve 48b, hydrogen valve 59b, and nitrogen valve 60b are opened. Therefore, during the operation of the piston 32, nitrogen is continuously or intermittently supplied from the nitrogen supply section 46 to the heat-insulating space 28. The nitrogen in the heat-insulating space 28 is mainly released into the atmosphere through the discharge passage section 48, and also through the leakage section 29. Thus, during the compression of hydrogen in the compression section 12, nitrogen continuously flows through the heat-insulating space 28. Therefore, oxygen present around the cylinder section 31 before the compressor unit 10 is driven is discharged from the heat-insulating space 28, thus preventing oxygen liquefaction. Furthermore, it prevents nitrogen from being cooled and liquefied.

[0040] Furthermore, during the operation of the crank mechanism 14, hydrogen is supplied to the first space 37a within the coupling section 37 by the hydrogen supply unit 59, and nitrogen is supplied to the second space 37b within the coupling section 37 by the nitrogen supply unit 60. Therefore, it is possible to prevent nitrogen in the second space 37b from mixing with the hydrogen in the compression chamber 34 through the rod seal section 36.

[0041] As explained above, in this embodiment, since nitrogen gas fills the heat insulation space 28 between the cover 25 and the cylinder 31, the oxygen concentration in the air can be reduced to a great extent within the heat insulation space 28. Therefore, since the air around the cylinder 31 (outside air) can be prevented from being cooled by the low-temperature gas, i.e., the evaporated gas of liquid hydrogen (intake gas), the liquefaction of the combustion-supporting gas, i.e., oxygen, can be prevented.

[0042] Furthermore, during the compression of hydrogen in the compression section 12, nitrogen is continuously discharged from the heat-insulating space 28 through various nitrogen discharge sections, namely the discharge passage section 48 and the leakage section 29. Therefore, it is also possible to prevent the nitrogen from being cooled and liquefied.

[0043] Furthermore, the nitrogen venting section (or venting channel 48, leakage section 29) also functions as a pressure equalization unit, thus equalizing the internal and external pressures of the insulation space 28. Accordingly, maintainability is improved compared to structures that maintain a vacuum state within the insulation space 28. That is, since it is not necessary to maintain a vacuum state in the insulation space 28, there is no need to install equipment for maintaining a vacuum in the insulation space 28. Furthermore, the plate members of the outer cylinder member 26 do not need to be plate members with the thickness required to withstand pressure differentials. A large number of bolts for bearing pressure are not required at the openings provided in the outer cylinder member 26. Moreover, since a sealing function is not required, weight reduction is possible, and simplified structures can be used for components such as bolts and seals. Therefore, maintainability is improved, and large-scale applications can be easily addressed.

[0044] In this embodiment, since the coupling portion 37 has a partition portion 44, it is possible to more reliably prevent the low-temperature evaporating gas (inhalation gas) from contacting the nitrogen. Furthermore, since the temperature of the hydrogen in the space on the compression chamber 34 side, i.e., the first space 37a, is higher than the liquefaction temperature of the nitrogen in the space on the crank mechanism 14 side, i.e., the second space 37b, it is possible to prevent the nitrogen from liquefying.

[0045] In this embodiment, the compression section 12 can be horizontally positioned. In this case, when the lower side is designated as the intake side, the support portion of the cylinder 31 is positioned on the lower intake side. In this case, the effects of icing and thermal contraction around the support portion may increase. Furthermore, even if nitrogen liquefies on the outer surface of the cylinder 31, the liquid is vaporized as it flows to the lower, higher-temperature exhaust side. To address this, when the intake valve 21a is positioned on the upper side in the direction of gravity, the support portion is positioned on the higher-temperature exhaust side. Therefore, the effects of icing and thermal contraction can be mitigated.

[0046] Furthermore, in this embodiment, the supply valve 46b is formed as a switching valve, but it is not limited to this; it may also be formed as an electrically operated valve capable of adjusting its opening. In this case, such as Figure 2 As shown, a temperature sensor 52 can also be provided to detect the temperature of nitrogen in the discharge pipe 48a of the discharge channel 48 or the temperature of nitrogen in the insulation space 28. When the temperature sensor 52 is provided to detect the temperature of nitrogen in the insulation space 28, the temperature sensor 52 is preferably positioned near the suction flow path 21 or the suction valve 21a so that the temperature of nitrogen in the insulation space 28 near the suction flow path 21 or the suction valve 21a can be detected.

[0047] Furthermore, the control unit 50 can also be configured to control the opening of the supply valve 46b based on the temperature detected by the temperature sensor 52. Specifically, when the temperature detected by the temperature sensor 52 is below a threshold value assumed based on the liquefaction temperature of nitrogen (i.e., set based on the liquefaction temperature of nitrogen), the control unit 50 controls the supply valve 46b to increase the amount of nitrogen supplied to the insulation space 28. In other words, in cases where there is a possibility of nitrogen being discharged from the piping 48a or liquefaction of nitrogen in the insulation space 28, the nitrogen supply unit 46 supplies a larger flow rate of nitrogen to the insulation space 28. Accordingly, nitrogen liquefaction can be prevented.

[0048] In this embodiment, such as Figure 1 As shown, a partition 44 is provided in the connector portion 37, but it is not limited to this. Figure 3 As shown, two or more partitions 44 can be provided.

[0049] In this embodiment, if nitrogen gas is sufficiently discharged through the discharge channel 48, there is no need to actively provide the leakage section 29. Furthermore, the leakage section 29 can function as both a nitrogen leakage section and a pressure equalization unit by adjusting its size and number; therefore, the discharge channel 48 can also be omitted.

[0050] (Second Implementation) In the first embodiment, the cover 25 is formed of an outer cylinder member 26 made of a material that is not easily deformed; in contrast, in the second embodiment, such as Figure 4 As shown, the cover portion 25 is formed by a sheet member 74 that covers the heat insulation material 72 installed on the cylinder portion 31. Furthermore, the same reference numerals are used for the same constituent elements as in the first embodiment, and their detailed descriptions are omitted.

[0051] In the second embodiment, a heat-insulating material 72 is provided to cover the cylinder portion 31. The heat-insulating material 72 can be arbitrarily wound around the cylinder portion 31. The heat-insulating material 72 is a cotton-like or sponge-like component such as glass wool, and by being arranged to cover the entire outer surface of the cylinder portion 31, it is difficult for heat from the outside air to be transferred to the cylinder portion 31. The heat-insulating material 72 is wound around the cylinder portion 31 and secured using a tape (not shown in the figure). Furthermore, the heat-insulating material 72 can be a pre-formed component, or it can be combined with a pre-formed component.

[0052] The sheet member 74 covering the insulation material 72 is made of a lighter and more flexible material compared to the outer cylinder member 26, which is made of metal or the like. In other words, the sheet member 74 only needs to have the function of preventing the insulation material 72 from being exposed to the outside, and therefore does not need to be a rigid member that forms a space of a specified size.

[0053] A moisture-proof sheet 75 may also be provided inside the heat insulation material 72. That is, the moisture-proof sheet 75 may be wrapped around the outer surface of the cylinder portion 31, and the heat insulation material 72 may be provided to cover the moisture-proof sheet 75. Alternatively, a moisture-proof sheet 75 may be provided on the heat insulation material 72, and a heat insulation material 72 may be provided on its outer side. In this case, the sheet member 74 may be provided to cover the outer heat insulation material 72. In other words, the moisture-proof sheet 75 and the heat insulation material 72 may also be a multi-layer structure.

[0054] In the second embodiment, nitrogen gas is supplied to the inner space of the sheet member 74, and heat insulation material 72 is disposed in this space. Therefore, the inner space of the sheet member 74 functions as a heat insulation space 28 for thermally isolating the cylinder 31 from the outside air.

[0055] The sheet component 74 is waterproof. In addition, the sheet component 74 may also be breathable to expel nitrogen gas from the insulation space 28.

[0056] The sheet member 74 has an opening through which the pipe forming the discharge flow path 18 passes, and also has an opening through which the pipe forming the suction flow path 21 passes. A leakage portion 29 (i.e., a hole or gap) is intentionally provided between these pipes and the openings. Alternatively, a leakage portion may be added to the sheet member 74 outside of the opening.

[0057] In the compressor unit 10, during the compression of hydrogen in the compression section, nitrogen is continuously or intermittently supplied from the nitrogen supply section 46 to the insulation space 28. The nitrogen within the insulation space 28 is released into the atmosphere through the leakage section 29. Furthermore, if the plate member 74 is ventilable, nitrogen can also be discharged entirely from the plate member 74. In this case, the plate member 74 itself functions as a nitrogen discharge section. As described above, by continuously flowing nitrogen through the insulation space 28, oxygen present around the cylinder section 31 before the compressor unit 10 is driven is discharged from the insulation space 28, thus preventing oxygen liquefaction. Furthermore, it also prevents nitrogen from being cooled and liquefied.

[0058] In the compressor unit 10, by adjusting the size and number of the leakage section 29, or by using a sheet component 74 with high air permeability, the leakage section 29 and the sheet component 74 themselves can function as nitrogen leakage sections, and can also function as pressure equalization units to make the pressure of the insulation space 28 substantially equal to atmospheric pressure.

[0059] In this embodiment, the cover 25 is formed by a sheet member 74 disposed to cover the heat insulation material 72. Therefore, compared to the case where the cover 25 is formed by the outer cylinder member 26 fixed to the cylinder 31, the burden of assembly and disassembly operations during maintenance can be reduced, and it is easier to cope with the large size of the cylinder 31 with a complex shape. That is, compared to the case where the cover 25 is formed by the outer cylinder member 26 made of metal, the components constituting the cover 25 can be made lighter, and maintainability is improved. In addition, the operation of covering the heat insulation material 72 with the sheet member 74 can be performed manually, so the burden of assembly and disassembly operations is reduced. Therefore, the burden of maintenance operations for the cylinder 31 can also be reduced. In addition, if nitrogen gas can be sufficiently discharged through the leakage part 29, the sheet member 74 can also be made of a non-permeable material.

[0060] In this embodiment, similar to the first embodiment, the supply valve 46b can also be formed by an electrically operated valve capable of adjusting its opening. In this case, such as Figure 5 As shown, a temperature sensor 52 can also be provided to detect the temperature of nitrogen in the discharge pipe 48a of the discharge channel 48 or the temperature of nitrogen in the insulation space 28. Furthermore, the control unit 50 is configured to control the supply valve 46b by changing the opening degree of the supply valve 46b based on the temperature detected by the temperature sensor 52. Specifically, when the temperature detected by the temperature sensor 52 is below a threshold value assumed based on the liquefaction temperature of nitrogen (i.e., set based on the liquefaction temperature of nitrogen), the control unit 50 controls the supply valve 46b to increase the amount of nitrogen supplied to the insulation space 28. In other words, in cases where liquefaction of nitrogen in the discharge pipe 48a or the insulation space 28 is possible, the nitrogen supply unit 46 supplies a larger flow rate of nitrogen to the insulation space 28. This prevents nitrogen liquefaction.

[0061] Other structures, functions, and effects are omitted from the description; the description of the first embodiment can be applied to the second embodiment. Furthermore, the present invention is not limited to the described embodiments, and various modifications and improvements can be made without departing from its spirit.

[0062] Here, the implementation method is described in summary.

[0063] (1) The compressor unit involved in the embodiment is a reciprocating compressor unit as follows: the compressor unit recovers evaporated gas, i.e., hydrogen, from a liquid hydrogen storage tank and supplies at least a portion of the hydrogen to a demander including at least one of an engine, a power generation device, and a boiler, and includes: a compression section configured to compress hydrogen flowing out of the liquid hydrogen storage tank and flowing in a suction flow path; and a crank mechanism configured to drive the compression section. The compression section includes: a cylinder; a piston; a cover disposed outside the cylinder; a nitrogen supply section configured to supply nitrogen to a heat-insulating space between the cover and the cylinder; and a nitrogen discharge section configured to discharge nitrogen from the heat-insulating space. The compressor unit further includes: a control section configured to control the nitrogen supply section such that nitrogen is supplied to the heat-insulating space during the compression of hydrogen in the compression section.

[0064] In the compressor unit, since nitrogen fills the insulation space between the cover and the cylinder, the oxygen concentration in the air within the insulation space can be minimized. Therefore, it prevents the air around the cylinder (outside air) from being cooled by the evaporation of the low-temperature gas, i.e., liquid hydrogen (intake gas), thus preventing the combustion gas, i.e., oxygen, from liquefying.

[0065] Furthermore, maintainability is improved compared to the compressor disclosed in Patent Document 1. The compressor in Patent Document 1 requires a vacuum pump or similar device to be installed in the space between the cylinder and the container section to create a vacuum whenever a portion of the container section is opened for inspection and maintenance of the cylinder section. In other words, in the compressor unit according to this embodiment, since it is not necessary to create a vacuum in the insulation space, no equipment for creating a vacuum in the insulation space is required.

[0066] (2) The compressor unit may also include: a pressure equalization unit, used to make the pressure in the insulation space substantially equal to the atmospheric pressure.

[0067] In this technical solution, the insulation space is always at approximately atmospheric pressure. Therefore, as the covering part, there is no need to use plate components with the thickness required to withstand the pressure difference. Furthermore, there is no need to install a large number of pressure-bearing bolts at the openings in the covering part. Additionally, no sealing function is required. Therefore, lightweight design can be achieved, and the structure can be simplified using bolts, seals, etc. This improves maintainability and makes it easier to handle larger applications.

[0068] (3) The cover may also be formed of a metal outer cylinder member, which is fixed to the cylinder in such a way that the formation of the heat insulation space is maintained in a specified shape.

[0069] In this technical solution, since the covering part is formed by an outer cylinder member fixed to the cylinder, the shape of the heat insulation space is maintained in a specified shape.

[0070] (4) The nitrogen exhaust section may also include an exhaust channel section having: an exhaust pipe fixed to the outer cylinder member in such a way as to open into the insulation space; and a valve disposed on the exhaust pipe, i.e., an exhaust valve.

[0071] In this technical solution, during the compression of hydrogen in the compression section, nitrogen continuously flows through the heat-insulating space, thus preventing the nitrogen from being cooled and liquefied.

[0072] (5) The compressor unit may also include a temperature sensor configured to detect the temperature of nitrogen in the discharge passage. In this case, the control unit may also control the nitrogen supply unit by increasing the nitrogen supply if the temperature detected by the temperature sensor is below a threshold presumed based on the liquefaction temperature of nitrogen.

[0073] This technical solution can more reliably prevent nitrogen liquefaction and suppress excessive nitrogen consumption.

[0074] (6) The compressor unit may also include a cotton-like or sponge-like heat insulation material. In this case, the cover may also be formed by a sheet member arranged to cover the heat insulation material, and nitrogen may be supplied by the nitrogen supply unit to the heat insulation space inside the sheet member.

[0075] In this technical solution, there is no need for a container-shaped outer cylinder member covering the cylinder, as is the case where the cover is formed by an outer cylinder member fixed to the cylinder. Therefore, the burden of assembly and disassembly during maintenance can be reduced, and it is also easier to handle large-scale applications. That is, compared with the case where the cover is formed by a metal outer cylinder member, the components constituting the cover can be made lighter, thus improving maintainability. In addition, the inner side of the sheet member covering the heat insulation material functions as a heat insulation space, but this heat insulation space is not limited to a sealed space.

[0076] (7) The covering part may also be breathable. In this technical solution, since the nitrogen gas in the heat insulation space can be appropriately discharged to the outside, the expansion of the sheet component can be prevented.

[0077] (8) The compressor unit may also include a temperature sensor configured to detect the temperature of nitrogen in the insulation space. In this case, the control unit may also control the nitrogen supply unit by increasing the nitrogen supply if the temperature detected by the temperature sensor is below a threshold presumed based on the liquefaction temperature of nitrogen.

[0078] This technical solution can more reliably prevent nitrogen liquefaction and suppress excessive nitrogen consumption.

[0079] (9) The compression section may also further include: a coupling portion, a housing connecting the cylinder portion and the crank mechanism, wherein the coupling portion includes at least one partition that divides the space inside the coupling portion into a plurality of spaces. In this case, the space closest to the compression chamber among the plurality of spaces may contain hydrogen, the space closest to the crank mechanism among the plurality of spaces may contain nitrogen, and the temperature of the hydrogen in the space closest to the compression chamber is higher than the liquefaction temperature of the nitrogen in the space closest to the crank mechanism.

[0080] In this technical solution, since the coupling part has a partition, it is possible to more reliably prevent the low-temperature evaporating gas (intake gas) from contacting the nitrogen. Furthermore, since the temperature of the hydrogen in the space on the compression chamber side is higher than the liquefaction temperature of the nitrogen in the space on the crank mechanism side, liquefaction of the nitrogen can be prevented.

[0081] (10) The compression section may also be a transverse type in which the piston slides in the horizontal direction. In this case, the cylinder may also include: an intake valve located on the upper side in the direction of gravity; and an exhaust valve located on the lower side in the direction of gravity.

[0082] When the lower side of the cylinder is designated as the intake side, the support portion of the cylinder is located on the lower intake side, which has a lower temperature. Therefore, the effects of icing and thermal contraction around the support portion may increase. Furthermore, even if nitrogen liquefies on the outer surface of the cylinder, it is vaporized as it flows to the higher discharge side below. In contrast, with the structure where the intake valve is located on the upper side in the direction of gravity, as in this technical solution, the support portion is located on the higher discharge side, which has a higher temperature, thus mitigating the effects of icing and thermal contraction.

[0083] As explained above, according to this embodiment, oxygen liquefaction can be eliminated, wherein oxygen is one of the main components of air and also a combustion-supporting gas; and, in the reciprocating compressor, maintenance is easy.

[0084] This application is based on Japanese Patent Application No. 2023-134820, filed on August 22, 2023, the contents of which are incorporated herein by reference.

[0085] To illustrate the invention, it has been adequately and sufficiently described above with reference to the accompanying drawings and embodiments. However, it should be recognized that modifications and / or improvements to the above embodiments can be readily made by those skilled in the art. Therefore, any modified or improved embodiments implemented by those skilled in the art, as long as they do not depart from the scope of protection of the claims, are to be interpreted as being included within the scope of protection of the claims.

Claims

1. A compressor unit, characterized in that: The following are reciprocating compressor units: The compressor unit recovers evaporated gas, i.e., hydrogen, from a liquid hydrogen storage tank and supplies at least a portion of the hydrogen to a demander including at least one of an engine, a power generation unit, and a boiler, and includes: The compression section is configured to compress hydrogen gas flowing from the liquid hydrogen storage tank and flowing in the suction path; and A crank mechanism is configured to drive the compression section, wherein, The compression section includes: Cylinder section; piston; A cover portion is disposed on the outer side of the cylinder portion; A nitrogen supply unit is configured to supply nitrogen to the heat-insulating space between the cover and the cylinder; and The nitrogen venting section is configured to allow nitrogen gas to be vented from the insulation space, wherein... The compressor unit also includes: The control unit controls the nitrogen supply unit in such a way that nitrogen is supplied to the insulation space during the compression of hydrogen in the compression section.

2. The compressor unit according to claim 1, characterized in that... Also includes: The pressure equalization unit is used to make the pressure in the insulation space substantially equal to the atmospheric pressure.

3. The compressor unit according to claim 1 or 2, characterized in that, The cover is formed of a metal outer cylinder member, which is fixed to the cylinder in such a way that the formation of the heat insulation space maintains a specified shape.

4. The compressor unit according to claim 3, characterized in that, The nitrogen venting section includes a venting channel section having: a venting pipe fixed to the outer cylinder member in such a way as to open into the insulation space; and a valve disposed on the venting pipe, i.e., a venting valve.

5. The compressor unit according to claim 4, characterized in that... Also includes: A temperature sensor is configured to detect the temperature of nitrogen gas in the discharge channel, wherein... When the temperature detected by the temperature sensor is below a threshold presumed based on the liquefaction temperature of nitrogen, the control unit controls the nitrogen supply unit to increase the nitrogen supply amount.

6. The compressor unit according to claim 1 or 2, characterized in that... Also includes: Cotton-like or sponge-like thermal insulation materials, among which, The covering portion is formed of a sheet member configured to cover the thermal insulation material. Nitrogen gas is supplied from the nitrogen supply unit to the heat insulation space inside the sheet member.

7. The compressor unit according to claim 6, characterized in that, The covering is breathable.

8. The compressor unit according to claim 7, characterized in that... Also includes: A temperature sensor is configured to detect the temperature of nitrogen gas in the insulation space, wherein... When the temperature detected by the temperature sensor is below a threshold presumed based on the liquefaction temperature of nitrogen, the control unit controls the nitrogen supply unit to increase the nitrogen supply amount.

9. The compressor unit according to claim 1 or 2, characterized in that, The compression section further includes: a coupling portion, a housing connecting the cylinder portion and the crank mechanism, wherein, The connector portion includes at least one partition that divides the space inside the connector portion into multiple spaces. The space closest to the compression chamber among the plurality of spaces contains hydrogen gas, and the space closest to the crank mechanism among the plurality of spaces contains nitrogen gas. The temperature of hydrogen in the space closest to the compression chamber is higher than the liquefaction temperature of nitrogen in the space closest to the crank mechanism.

10. The compressor unit according to claim 1 or 2, characterized in that, The compression section is a transversely positioned type in which the piston slides in the horizontal direction. The cylinder section includes: The suction valve is located on the upper side in the direction of gravity; and The discharge valve is located on the lower side in the direction of gravity.

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