Reciprocating compressor unit and compressor unit operating method

Abstract

To realize a seal structure suitable for a compressor unit for dealing with boil-off gas.SOLUTION: A compressor unit comprises a rod packing part 36 for sealing a part between a piston rod 33 and a cylinder part, and a leak gas discharge part 66 for discharging hydrogen gas leaked to the rod packing part 36, to the outside. The rod packing part 36 comprises: a packing ring part 41; a discharge passage 52 for allowing the hydrogen gas leaked through the packing ring 41, to flow into the leak gas discharge part 66; a gas seal part 54 for forming a gas seal in a clearance 50 between itself and the piston rod 33 by using the hydrogen gas at a position closer to the side of a crank mechanism than the discharge passage 52; and a packing ring part 43 arranged between the gas seal part 54 and the discharge passage 52. The pressure of the hydrogen gas in the gas seal part 54 is higher than the pressure of the hydrogen gas in the leak gas discharge part 66.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a reciprocating compressor unit and a method for operating the compressor unit. [Background technology]

[0002] In recent years, with environmental considerations in mind, hydrogen has been considered for use as a fuel for power generation and automobiles, and the demand for hydrogen is increasing. In addition, low-temperature boil-off gas (BOG) from liquefied natural gas (LNG) and liquid hydrogen (LH2) is recovered using compressors and supplied to engines and other users. The boil-off gas generated from LH2, in particular, is extremely low in temperature. Therefore, if a compressor is designed to directly draw in the boil-off gas, it is subject to constraints such as the need to select materials suitable for extremely low temperatures, adopt design conditions that take into account the amount of thermal deformation, and implement strict insulation treatment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-172870 [Patent Document 2] Japanese Patent Application Publication No. 7-119634 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, Patent Document 1 points out the following problem: "In recent years, hydrogen has been attracting attention as a new energy source. When using hydrogen as an energy source, it is expected that it 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, etc., is applied to hydrogen as is, there is a possibility that problems will arise due to the extremely low temperature of liquid hydrogen. For example, liquefied air will be generated around the equipment to which liquid hydrogen is supplied." For this reason, Patent Document 1 proposes various structures for reciprocating compressors. For example, the reciprocating compressor includes an intermediate cylindrical portion disposed between a piston drive portion and a container portion and accommodating a piston rod. The intermediate cylindrical portion is formed with a first intermediate chamber, a second intermediate chamber, and a rod packing chamber, in that order from the piston drive portion side. The internal pressure of the first intermediate chamber is higher than the internal pressures of the second intermediate chamber and the rod packing chamber. The rod packing chamber is filled with hydrogen gas at room temperature. The first intermediate chamber is filled with nitrogen gas. A vent is provided at a position corresponding to the second intermediate chamber.

[0005] It is disclosed that this structure makes it possible to prevent hydrogen gas from leaking from the compression section to the piston drive section, and that by preventing the leakage of cryogenic gas, the piston drive section can be operated reliably.

[0006] However, even if the internal pressure of the first intermediate chamber is made higher than the internal pressures of the second intermediate chamber and the rod packing chamber, there is a risk that the nitrogen gas in the first intermediate chamber will flow into the rod packing chamber. If the nitrogen gas comes into contact with the cryogenic hydrogen gas (the suction gas of the compressor), the nitrogen gas may be liquefied.

[0007] Incidentally, the reciprocating compressor disclosed in Patent Document 2 has the following configuration: "The compressed gas branched off from the discharge passage 7 is cooled by the gas cooler 23 and introduced into the cooling chamber 22 via the discharge passage side portion 28a of the cooling passage 28 in the packing case 10, thereby directly cooling the piston rod 1, and then the compressed gas is returned to the suction passage 5 via the suction passage side portion 28b of the cooling passage 28 in the packing case 10." In Patent Document 2, the compressed gas flows smoothly through the cooling chamber 22 because the purpose is to cool the piston rod 1. This structure is not necessarily suitable for the purpose of avoiding contact between nitrogen gas and cryogenic hydrogen gas (the intake gas of the compressor).

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to realize a seal structure that is preferable for a reciprocating compressor unit that handles boil-off gas of liquefied hydrogen. [Means for solving the problem]

[0009] The compressor unit of the present invention is a reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a demand destination including at least one of an engine, a power generation facility, and a boiler, and includes: a compression stage that compresses hydrogen gas in an intake passage; and a crank mechanism that drives the compression stage. The compression stage includes a cylinder portion, a piston, a piston rod that connects the piston to the crank mechanism, a rod packing that seals between the piston rod and the cylinder portion, an adapter portion that connects the cylinder portion to a case of the crank mechanism, a nitrogen gas supply portion that supplies nitrogen gas into the adapter portion, a leak gas discharge portion that discharges hydrogen gas that has leaked into the rod packing portion to the outside, and a hydrogen gas supply portion that supplies hydrogen gas to the rod packing portion. The rod packing unit includes at least one packing ring that contacts and seals with the piston rod, a discharge passage connected to the leak gas discharge unit and that allows hydrogen gas that is part of the gas compressed in the cylinder unit and leaks through the packing ring to flow into the leak gas discharge unit, a gas seal that forms a gas seal in a gap between the piston rod and the rod packing unit on the crank mechanism side of the discharge passage by supplying hydrogen gas from the hydrogen gas supply unit, and at least one other packing ring that is disposed between the gas seal and the discharge passage. The pressure of the hydrogen gas in the gas seal unit is higher than the pressure of the hydrogen gas in the leak gas discharge unit.

[0010] In the compressor unit according to the present invention, a discharge passage is provided in the rod packing portion and connected to the leak gas discharge portion, so that hydrogen gas leaked through the packing ring portion is discharged to the outside via the discharge passage and the leak gas discharge portion. Furthermore, a hydrogen gas gas seal portion is provided in the rod packing portion closer to the crankcase than the discharge passage, so that the pressure of the hydrogen gas in the gas seal portion is higher than the pressure in the leak gas discharge portion. This prevents boil-off gas (suction gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder portion, from passing over the gas seal portion and entering the adapter portion and crankcase, thereby preventing liquefaction of nitrogen gas.

[0011] In addition, because hydrogen gas is used for the gas seal of the rod packing section, even if the seal gas leaks into the cylinder section, unexpected events such as liquefaction caused by cooling by the intake gas (hydrogen gas) can be prevented compared to when a different type of gas is used as the seal gas.

[0012] In the compressor unit, the pressure of the hydrogen gas in the gas seal portion may be higher than the pressure of the nitrogen gas in the adapter portion.

[0013] In this embodiment, the pressure of the hydrogen gas in the gas seal provided in the rod packing is higher than the pressure of the nitrogen gas in the adapter, so that the nitrogen gas being supplied to the adapter can be prevented from overflowing the gas seal provided in the rod packing. Therefore, direct contact between the nitrogen gas and leaked boil-off gas (intake gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder, is more reliably prevented.

[0014] The compression stage may further include another hydrogen gas supply unit capable of supplying hydrogen gas. In this case, the adapter unit may include a partition unit that divides the interior thereof into a space on the compression chamber side and a space on the crank mechanism side, and the other hydrogen gas supply unit may supply hydrogen gas to the space on the compression chamber side, and the nitrogen gas supply unit may supply nitrogen gas to the space on the crank mechanism side, and the temperature of the hydrogen gas in the space on the compression chamber side may be higher than the liquefaction temperature of the nitrogen gas in the space on the crank mechanism side.

[0015] In this embodiment, the adapter unit is provided with a partition, which more reliably prevents contact between the low-temperature boil-off gas (suction gas) and the nitrogen gas. The temperature of the hydrogen gas supplied by the other hydrogen gas supply unit in the space on the compression chamber side is higher than the liquefaction temperature of the nitrogen gas in the space on the crank mechanism side, which prevents the nitrogen gas from liquefying.

[0016] The compression stage may further include a pressure adjusting means for adjusting the pressure of at least one of the hydrogen gas supply unit, the other hydrogen gas supply unit, and the nitrogen gas supply unit so that the relationship of pressure P1 > pressure P2 > pressure P3 holds among the hydrogen gas pressure P1 in the gas seal unit, the hydrogen gas pressure P2 in the space on the compression chamber side of the adapter unit, and the nitrogen gas pressure P3 in the space on the crank mechanism side.

[0017] In this embodiment, nitrogen gas does not flow from the space on the crank mechanism side to the space on the compression chamber side, so nitrogen gas does not flow into the rod packing portion, thereby preventing the nitrogen gas from liquefying.

[0018] The adapter portion may be provided with a nitrogen gas supply port and a discharge port on an outer peripheral wall defining the space on the crank mechanism side, and may further include a discharge-side pressure adjustment means capable of releasing nitrogen gas when the pressure at the discharge port reaches or exceeds a predetermined pressure. In this case, the compression stage may further include a supply-side pressure adjustment means that adjusts the pressure of at least one of the hydrogen gas supply portion, the other hydrogen gas supply portion, and the nitrogen gas supply portion so that a relationship of pressure P1 > pressure P3 > pressure P2 is established among a hydrogen gas pressure P1 in the gas seal portion, a hydrogen gas pressure P2 in the space on the compression chamber side of the adapter portion, and a pressure P3 in the space on the crank chamber side.

[0019] In this embodiment, it is possible to more actively prevent hydrogen gas, which is a flammable gas, from leaking into the crankcase.

[0020] The leaked gas discharge unit may be connected to the suction passage and return leaked hydrogen gas to the suction passage. In this case, the compression stage may further include a feed line connecting the hydrogen gas supply unit and the discharge passage and sending a portion of the hydrogen gas discharged from the compression stage to the gas seal unit.

[0021] In this embodiment, leaked hydrogen gas can be collected, and there is no need to prepare a separate hydrogen gas for gas sealing.

[0022] The compressor unit of the present invention is a reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a demand destination including at least one of an engine, a power generation facility, and a boiler, and includes: a compression stage that compresses hydrogen gas in an intake passage; and a crank mechanism that drives the compression stage. The compression stage includes a cylinder portion, a piston, a piston rod that connects the piston to the crank mechanism, a rod packing that seals between the piston rod and the cylinder portion, an adapter portion that connects the cylinder portion to a case of the crank mechanism, a nitrogen gas supply portion that supplies nitrogen gas into the adapter portion, a hydrogen gas supply portion that supplies hydrogen gas to other portions inside the adapter portion, and a leak gas discharge portion that discharges hydrogen gas that has leaked into the rod packing portion to the outside. The rod packing portion includes at least one packing ring portion that contacts and seals the piston rod, a discharge passage connected to the leak gas discharge portion and that allows hydrogen gas, which is part of the gas compressed in the cylinder portion and leaks through the packing ring portion, to flow into the leak gas discharge portion, and at least one other packing ring portion that is located closer to the crank mechanism than the discharge passage.The adapter portion includes at least one partition portion that divides the interior into a plurality of spaces, the hydrogen gas supply portion supplies hydrogen gas to a space located closest to the compression chamber inside the adapter portion, and the nitrogen gas supply portion supplies nitrogen gas to at least one space located closer to the crank mechanism than the space located closest to the compression chamber inside the adapter portion, and the pressure of the hydrogen gas in the space closest to the compression chamber is higher than the pressure of the hydrogen gas in the leak gas discharge portion.

[0023] In the compressor unit according to the present invention, the pressure of hydrogen gas supplied by the hydrogen gas supply unit in the space inside the adapter closest to the compression chamber is higher than the pressure of hydrogen gas in the leak gas discharge unit. This prevents hydrogen gas leaked to the rod packing from entering the space inside the adapter closest to the compression chamber. This prevents boil-off gas of liquefied hydrogen, which is a low-temperature gas, from coming into direct contact with nitrogen gas, thereby preventing liquefaction of nitrogen gas.

[0024] The compression stage may further include another hydrogen gas supply unit that supplies hydrogen gas to the rod packing unit. In this case, the rod packing unit may further include a gas seal unit that forms a gas seal in a gap between the piston rod and the rod packing unit by supplying hydrogen gas from the another hydrogen gas supply unit to a position closer to the crank mechanism than the discharge passage. Also, a portion of the at least one other packing ring unit may be located between the gas seal unit and the discharge passage, and the pressure of the hydrogen gas in the gas seal unit may be higher than the pressure of the hydrogen gas in the leak gas discharge unit.

[0025] In this aspect, the gas seal portion can prevent gas from leaking from inside the cylinder portion.

[0026] The adapter portion may include two partitions that divide the interior into three spaces. In this case, the hydrogen gas supply unit may supply hydrogen gas to the space inside the adapter portion closest to the compression chamber, and the nitrogen gas supply unit may supply nitrogen gas to the space inside the adapter portion closest to the crank mechanism, and the intermediate chamber of the adapter portion may be provided with a vent that discharges gas inside the intermediate chamber to the outside. Furthermore, the pressure of the hydrogen gas in the space closest to the compression chamber and the pressure of the nitrogen gas in the space closest to the crank mechanism may be set to be higher than the pressure inside the intermediate chamber.

[0027] In this embodiment, even if nitrogen gas leaks from the space closest to the crank mechanism into the intermediate chamber, this nitrogen gas is less likely to reach the space closest to the compression chamber, thereby more reliably preventing nitrogen from entering the cylinder section.

[0028] The leaked gas discharge unit may be connected to the suction passage and return leaked hydrogen gas to the suction passage. In this case, the compression stage may further include a feed line connecting the separate hydrogen gas supply unit to the discharge passage and sending a portion of the hydrogen gas discharged from the compression stage to the gas seal unit.

[0029] In this embodiment, leaked hydrogen gas can be collected, and there is no need to prepare a separate hydrogen gas for gas sealing.

[0030] The nitrogen gas supply unit may supply nitrogen gas to the inside of the adapter unit not only while the compression stage is in operation, but also while the compression stage is stopped.

[0031] In this configuration, the components of the compression stage, including the cylinder, piston, and piston rod, become cold during operation and remain cold for a long time even when the compressor unit is stopped, rather than immediately returning to normal temperature. Meanwhile, when the supply of nitrogen gas is stopped, atmospheric air may enter the space on the crank mechanism side of the adapter. If atmospheric air enters the space on the crank mechanism side while the piston rod remains cold, condensation may form on the piston rod. This can cause rust on internal components and impair the sealing function of the packing ring due to condensation on the surface of the piston rod. However, because nitrogen gas is supplied not only during operation of the compression stage but also when the compressor unit is stopped, rust on internal components and deterioration of sealing function can be prevented. [Effects of the Invention]

[0032] As described above, according to the present invention, a seal structure that is preferable for a reciprocating compressor unit that handles boil-off gas of liquefied hydrogen can be realized. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a diagram schematically illustrating an overall configuration of a compressor unit according to a first embodiment. [Figure 2] FIG. 2 is a diagram schematically illustrating a compression stage provided in the compressor unit. [Figure 3] 10A and 10B are diagrams showing the configuration of a rod packing portion provided in the compression stage. [Figure 4] 5A and 5B are diagrams for explaining the operation of the compressor unit. [Figure 5] FIG. 4 is a diagram schematically showing the overall configuration of a compressor unit according to a modified example of the first embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating the overall configuration of a compressor unit according to a second embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating the overall configuration of a compressor unit according to a third embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating an overall configuration of a compressor unit according to a modified example of the third embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating an overall configuration of a compressor unit according to a modified example of the third embodiment. [Figure 10] FIG. 10 is a diagram schematically illustrating an overall configuration of a compressor unit according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0035] (First embodiment) The compressor unit according to this embodiment is configured to recover hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank, compress the recovered hydrogen gas, and supply it to a consumer. The boil-off gas, which is hydrogen gas, has a temperature of approximately −253°C. Consumers include at least one of an engine, a power generation facility, and a boiler, but may also include facilities other than those that utilize gas as an energy source, such as gas combustion facilities, flare facilities, and vents. The hydrogen gas discharged from the compressor unit does not necessarily have to be supplied directly to a consumer; it may be filled into a cylinder or the like and then supplied to the consumer by various means, such as transporting the cylinder or using gas piping connected to the cylinder.

[0036] 1, the compressor unit 10 includes a compression stage 12 for compressing hydrogen gas and a crank mechanism 14 for driving the compression stage 12. The compressor unit 10 also includes a second compression stage 16 for further compressing the hydrogen gas compressed in the compression stage 12. That is, the hydrogen gas compressed in the compression stage 12 is discharged to a discharge flow path 18, and the second compression stage 16 is provided in this discharge flow path 18. The hydrogen gas compressed in the second compression stage 16 is supplied to a consumer 20.

[0037] The compression stage 12 is connected to a liquid hydrogen storage tank 23 via a suction passage 21. Therefore, boil-off gas of the liquefied gas generated in the liquid hydrogen storage tank 23 is sucked into the compression stage 12 through the suction passage 21.

[0038] The crank mechanism 14 drives the compression stage 12 and the second compression stage 16 collectively. However, the present invention is not limited to this configuration, and for example, the second compression stage 16 may be omitted, and the crank mechanism 14 may drive only one compression stage 12. Furthermore, the compressor unit 10 may be provided with one or more compression stages subsequent to the second compression stage 16.

[0039] The compressor unit 10 is equipped with a spillback section 25 for returning hydrogen gas discharged from the compression stage 12 to the suction flow path 21, and a second spillback section 27 for returning hydrogen gas discharged from the second compression stage 16 to the suction flow path 21.

[0040] The spillback unit 25 has a spillback flow path 25a and a spillback valve 25b, which is an adjustable valve disposed in the spillback flow path 25a. One end of the spillback flow path 25a is connected to a portion of the discharge flow path 18 upstream of the second compression stage 16, and the other end is connected to the suction flow path 21. By controlling the spillback valve 25b, the pressure and flow rate of the hydrogen gas sucked into the second compression stage 16 are adjusted. It is possible to omit the spillback unit 25.

[0041] The second spillback section 27 has a second spillback flow path 27a and a second spillback valve 27b, which is an adjustable valve disposed in the second spillback flow path 27a. One end of the second spillback flow path 27a is connected to a portion of the discharge flow path 18 downstream of the second compression stage 16, and the other end is connected to the suction flow path 21. By controlling the second spillback valve 27b, the pressure and flow rate of the hydrogen gas supplied to the demand destination 20 are adjusted. Note that if the main purpose is to equalize the pressure between the suction flow path 21 and the discharge flow path 18 when the compressor unit 10 is stopped, a manual valve or an ON-OFF valve may be used as the second spillback valve 27b.

[0042] 2, the compression stage 12 is configured by a reciprocating compression mechanism. That is, the compression stage 12 includes a cylinder portion 31, a piston 32 disposed in the cylinder portion 31, and a piston rod 33 connected to the piston 32. The piston rod 33 is connected to the crank mechanism 14. The piston 32 reciprocates within the cylinder portion 31, thereby compressing hydrogen gas within a compression chamber 34.

[0043] 2 shows the compression stage 12 having a double-acting structure, the compression stage 12 may also have a single-acting structure. Furthermore, the compression stage 12 does not necessarily have to be composed of a single cylinder, but may be composed of multiple compression stages connected in parallel. In other words, the compression stage 12 may be configured such that hydrogen gas is compressed and pressurized by pistons 32 in multiple cylinder sections 31 connected in parallel.

[0044] The compression stage 12 includes a rod packing portion 36 provided in the cylinder portion 31, an adapter portion 37 arranged adjacent to the cylinder portion 31 and connected to the cylinder portion 31, and a crankcase 38 that houses a crankshaft that is part of the crank mechanism 14.

[0045] The adapter part 37 is formed in a cylindrical shape, and the piston rod 33 is disposed in the space inside the adapter part 37. One longitudinal end of the adapter part 37 is connected to the cylinder part 31. The other longitudinal end of the adapter part 37 is connected to the crankcase 38. A partition wall 40 is provided at this other end, separating the internal space of the adapter part 37 from the space inside the crankcase 38.

[0046] The rod packing portion 36 is fixed to the rear head 31a, which is part of the cylinder portion 31, and is provided to prevent hydrogen gas in the compression chamber 34 from leaking out of the cylinder portion 31 through the gap between the rear head 31a and the piston rod 33. The rear head 31a is provided with a through-hole (not shown) through which the piston rod 33 passes, and the rod packing portion 36 is housed in this through-hole.

[0047] 3, the rod packing portion 36 includes at least one packing ring portion (first packing ring portion 41), a case portion (first case portion 42) that houses the first packing ring portion 41, at least one other packing ring portion (second packing ring portion 43), another case portion (second case portion 44) that houses the second packing ring portion 43, at least one further packing ring portion (third packing ring portion 45), and another further case portion (third case portion 46) that houses the third packing ring portion 45. The second packing ring portion 43 and the second case portion 44 are disposed on the opposite side of the compression chamber 34 (the crank mechanism 14 side) with respect to the first packing ring portion 41 and the first case portion 42, and the third packing ring portion 45 and the third case portion 46 are disposed on the opposite side of the compression chamber 34 (the crank mechanism 14 side) with respect to the second packing ring portion 43 and the second case portion 44.

[0048] 3 shows a configuration in which a plurality of first case portions 42 are each provided with a plurality of first packing ring portions 41, a single second case portion 44 is provided with a plurality of second packing ring portions 43, and a single third case portion 46 is provided with a plurality of third packing ring portions 45, but this configuration is not limited to this. For example, a configuration in which a single packing ring portion 41, 43, 45 is provided in each of the case portions 42, 44, 46 may also be used. By providing a plurality of packing ring portions 41, 43, 45 in each of the case portions 42, 44, 46, it is possible to further improve sealing performance, making it more suitable for high-pressure compression stages.

[0049] The first case portion 42, the second case portion 44, and the third case portion 46 are aligned in the direction in which the piston rod 33 extends, and are disposed in the through-hole of the rear head 31a. In this state, the first case portion 42, the second case portion 44, and the third case portion 46 are attached to the rear head 31a from the crank mechanism 14 side by flange portions 47.

[0050] Each of the first case part 42, the second case part 44 and the third case part 46 has a through hole formed therein for allowing the piston rod 33 to pass therethrough, and a gap 50 is formed between the peripheral edge part defining the through hole in each of the first case part 42, the second case part 44 and the third case part 46 and the outer peripheral surface of the piston rod 33.

[0051] The packing ring portions 41, 43, and 45 are aligned in the extension direction of the piston rod 33 and are disposed so as to surround the piston rod 33. The packing ring portions 41, 43, and 45 are deformed by high-pressure hydrogen gas so as to fit closely to the outer peripheral surface of the piston rod 33. Note that the packing ring portions 41, 43, and 45 may be formed to a size that fits closely to the outer peripheral surface of the piston rod 33 even when no pressure of high-pressure hydrogen gas is applied, or may be configured so as to fit closely to the outer peripheral surface by being pressed by a spring.

[0052] A discharge passage 52 is provided in the rod packing portion 36 so as to pass between the first packing ring portion 41 and the second packing ring portion 43. The discharge passage 52 is a passage for allowing hydrogen gas that has passed through the first packing ring portion 41 and leaked to the second packing ring portion 43 side to flow into a leak gas discharge portion 66 (described later), and opens into a gap 50 between the second case portion 44 and the outer peripheral surface of the piston rod 33. The discharge passage 52 is connected to the leak gas discharge portion 66 (described later), and allows hydrogen gas that has leaked into the gap 50 between the second case portion 44 and the outer peripheral surface of the piston rod 33 to flow into the leak gas discharge portion 66 (described later).

[0053] The rod packing portion 36 is also provided with a gas seal portion 54. The gas seal portion 54 forms a gas seal 54a in the gap 50 between the outer circumferential surface of the piston rod 33 and the third case portion 46 by using hydrogen gas from a first hydrogen gas supply portion 58 (see FIG. 2) described below. The gas seal portion 54 has an introduction passage 54b formed in the third case portion 46 and connected to a hydrogen flow passage 58a of the first hydrogen gas supply portion 58 described below. The third packing ring portion 45 is located on the opposite side of the gas seal 54a to the second packing ring portion 43 and the first packing ring portion 41. The gas seal 54a is located closer to the adapter portion 37 (first space 37a side) than the discharge passage 52.

[0054] 2, adapter portion 37 has a partition portion 56 that divides the internal space into a space on the compression chamber 34 side (first space 37a) and a space on the crank mechanism 14 side (second space 37b). Piston rod 33 also passes through this partition portion 56. A seal portion 56a is provided on the periphery of a through hole in partition portion 56, through which piston rod 33 passes.

[0055] The compression stage 12 includes a hydrogen gas supply unit (first hydrogen gas supply unit 58) that supplies hydrogen gas to the rod packing unit 36, another hydrogen gas supply unit (second hydrogen gas supply unit 59) that supplies hydrogen gas to the first space 37a in the adapter unit 37, and a nitrogen gas supply unit 60 that supplies nitrogen gas to the second space 37b in the adapter unit 37.

[0056] The first hydrogen gas supply unit 58 has a hydrogen flow path 58a connected to a hydrogen gas source 61, and is configured to supply hydrogen gas from the hydrogen gas source 61 to the gas seal unit 54 in the rod packing unit 36 ​​through this hydrogen flow path 58a. The first hydrogen gas supply unit 58 supplies hydrogen gas to a gap 50 having packing ring units on both sides (i.e., the gap 50 between the first packing ring unit 41 and the second packing ring unit 43). The hydrogen gas source 61 contains hydrogen gas at room temperature.

[0057] The second hydrogen gas supply unit 59 has a second hydrogen flow path 59a connected to the hydrogen flow path 58a. The second hydrogen flow path 59a is connected to a supply port formed in the outer peripheral wall that defines the first space 37a in the adapter unit 37. The second hydrogen gas supply unit 59 supplies hydrogen gas from a hydrogen gas source 61 through the second hydrogen flow path 59a to the first space 37a in the adapter unit 37. For this reason, it can be said that the temperature of the hydrogen gas in the first space 37a is higher than the liquefaction temperature of the nitrogen gas in the second space 37b.

[0058] The nitrogen gas supply unit 60 has a nitrogen flow path 60a connected to a nitrogen gas source 62. The nitrogen flow path 60a is connected to a supply port formed in the outer peripheral wall that forms the second space 37b in the adapter unit 37. The nitrogen gas supply unit 60 supplies nitrogen gas from the nitrogen gas source 62 to the second space 37b in the adapter unit 37 through this nitrogen flow path 60a. The nitrogen gas source 62 contains nitrogen gas at room temperature.

[0059] The hydrogen flow path 58a is provided with a first hydrogen valve 58b, which is a valve that adjusts the pressure of hydrogen gas flowing through the hydrogen flow path 58a, the second hydrogen flow path 59a of the second hydrogen gas supply unit 59 is provided with a second hydrogen valve 59b, which is a valve that adjusts the pressure of hydrogen gas flowing through the second hydrogen flow path 59a, and the nitrogen flow path 60a is provided with a nitrogen valve 60b, which is a valve that adjusts the pressure of nitrogen gas flowing through the nitrogen flow path 60a.

[0060] The first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b constitute a pressure adjustment means 63 that adjusts at least one of the pressure of the hydrogen gas supplied by the first hydrogen gas supply unit 58, the pressure of the hydrogen gas supplied by the second hydrogen gas supply unit 59, and the pressure of the nitrogen gas supplied by the nitrogen gas supply unit 60. For example, if the pressure of the hydrogen gas in the gas seal unit 54 is pressure P1, the pressure of the hydrogen gas in the first space 37a in the adapter unit 37 is pressure P2, and the pressure of the nitrogen gas in the second space 37b in the adapter unit 37 is pressure P3, at least one of the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b is adjusted so that the relationship of pressure P1 > pressure P2 > pressure P3 holds. In other words, the pressure in the first space 37a, into which room-temperature hydrogen gas is introduced, is higher than the pressure in the second space 37b, into which nitrogen gas is introduced, preventing the nitrogen gas in the second space 37b from entering the first space 37a. Furthermore, since the pressure inside the gas seal portion 54 is higher than the pressure inside the first space 37a, even if nitrogen gas were to enter the first space 37a, this nitrogen gas is prevented from entering the rod packing portion 36.

[0061] The compression stage 12 includes a leak gas discharge section 66 that discharges leak gas (hydrogen gas) from the rod packing section 36, a first discharge section 67 that discharges hydrogen gas in the first space 37a, and a second discharge section 68 that discharges nitrogen gas in the second space 37b.

[0062] The leak gas discharge section 66 is configured by a pipe member connected to the rod packing section 36 so as to communicate with the discharge passage 52 (FIG. 3) provided in the rod packing section 36. The leak gas discharge section 66 is connected to the suction passage 21 for allowing hydrogen gas to flow into the compression chamber 34 of the compression stage 12. Because the discharge passage 52 is in communication with the leak gas discharge section 66, hydrogen gas that leaks from the compression chamber 34 and passes through the first packing ring section 41 can be returned to the suction passage 21 through the discharge passage 52 and the leak gas discharge section 66. The leak gas discharge section 66 is provided with a check valve 69 that prevents hydrogen gas from flowing toward the rod packing section 36. The leak gas discharge section 66 may be connected to a vent 70 instead of being connected to the suction passage 21 of the compression stage 12. As with the compression stage 12, the second compression stage 16 may also be provided with a leak gas discharge section that communicates with the discharge passage provided in the rod packing section. The leak gas discharge part is connected to the suction flow path 21 .

[0063] The first discharge part 67 is connected to the adapter part 37 so as to open to the first space 37a. That is, one end of the first discharge part 67 is connected to an outlet formed in the outer peripheral wall that defines the first space 37a in the adapter part 37. The other end of the first discharge part 67 is connected to the suction passage 21 of the compression stage 12. Therefore, the hydrogen gas in the first space 37a can be returned to the compression chamber 34 through the suction passage 21. The first discharge part 67 may be connected to a vent 70 instead of being connected to the suction passage 21 of the compression stage 12.

[0064] The second discharge part 68 is connected to the adaptor part 37 so as to open into the second space 37b. That is, one end of the second discharge part 68 is connected to a discharge port formed in the outer peripheral wall that forms the second space 37b in the adaptor part 37, and the other end of the second discharge part 68 is connected to the vent 70. The second discharge part 68 may also serve to collect drainage generated in the second space 37b, and in this case, the second discharge part 68 may be provided with a drain pot or the like.

[0065] An on-off valve 68a is provided in the second discharge part 68. The on-off valve 68a constitutes a discharge-side pressure adjustment means that discharges nitrogen gas when the pressure at the nitrogen gas discharge port in the adapter part 37 reaches or exceeds a predetermined pressure. Therefore, when the pressure in the second space 37b in the adapter part 37 reaches or exceeds the predetermined pressure, the on-off valve 68a opens, and the nitrogen gas in the second space 37b is discharged to the vent 70. In other words, the on-off valve 68a may be constituted by a relief valve.

[0066] Here, we will explain the operation when stopping the compressor unit 10. As shown in Figure 4, in the compressor unit 10, when the crank mechanism 14 is operated, the piston 32 is operated, and hydrogen gas, which is boil-off gas, is sucked into the compression chamber 34 from the suction passage 21, and the hydrogen gas is compressed (step ST11).

[0067] While the crank mechanism 14 is driven, the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b are open. Therefore, the first hydrogen gas supply unit 58 supplies hydrogen gas to the gas seal unit 54, the second hydrogen gas supply unit 59 supplies hydrogen gas to the first space 37a in the adapter unit 37, and the nitrogen gas supply unit 60 supplies nitrogen gas to the first space 37a in the adapter unit 37 (step ST12). At this time, the relationship of pressure P1 (the pressure of hydrogen gas in the gas seal unit 54) > pressure P2 (the pressure of hydrogen gas in the first space 37a in the adapter unit 37) > pressure P3 (the pressure of nitrogen gas in the second space 37b in the adapter unit 37) is established. Therefore, nitrogen gas is prevented from entering the first space 37a from the second space 37b. Furthermore, even if nitrogen gas were to enter the first space 37a, the nitrogen gas would be prevented from entering the rod packing portion .

[0068] When the command to stop the compressor unit 10 is received, the compressor unit 10 stops operating (step ST13). At this time, the supply of nitrogen gas by the nitrogen gas supply unit 60 continues. That is, nitrogen gas is supplied to the inside of the adapter unit 37 not only while the compression stage 12 is operating, but also while the compression stage 12 is stopped. That is, the discharge pipe (not shown) connected to the discharge port of the space on the crank mechanism 14 side of the adapter unit 37 is often open to the atmosphere. Therefore, when the supply of nitrogen gas is stopped, the atmosphere may enter the space on the crank mechanism 14 side of the adapter unit 37. For this reason, the supply of nitrogen gas continues to prevent the atmosphere from entering the second space 37b while the compression stage 12 is stopped.

[0069] While the compression stage 12 is stopped, a determination is made as to whether or not to stop the supply of nitrogen gas by the nitrogen gas supply unit 60 (step ST14). That is, while the compression stage 12 is at a low temperature, the supply of nitrogen gas continues. However, since the problem of condensation will no longer occur when the temperature returns to room temperature, a determination is made as to whether or not the temperature at a predetermined location in the compression stage 12 has returned to a predetermined temperature (for example, a temperature at which condensation is not expected to occur on the piston rod 33). If the determination in step ST14 is YES, the supply of nitrogen gas by the nitrogen gas supply unit 60 is stopped (step ST15). Note that while nitrogen gas is being supplied, the supply of hydrogen gas may be continued or stopped. Furthermore, the supply of nitrogen gas may be continued at all times while the compressor unit 10 is stopped, but may also be stopped during maintenance, etc.

[0070] As described above, in this embodiment, the rod packing portion 36 is provided with the discharge passage 52, which is connected to the leak gas discharge portion 66. Therefore, hydrogen gas that has leaked through the first packing ring portion 41 is discharged to the outside of the rod packing portion 36 and the adapter portion 37 through the discharge passage 52 and the leak gas discharge portion 66. In addition, the rod packing portion 36 is provided with a gas seal portion 54 made of hydrogen gas on the crankcase 38 side of the discharge passage 52, and the pressure of the hydrogen gas in the gas seal portion 54 is made higher than the pressure in the leak gas discharge portion 66. This makes it possible to prevent boil-off gas (suction gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder portion 31, from passing over the gas seal portion 54 and entering the adapter portion 37 side or the crankcase 38 side, thereby preventing liquefaction of nitrogen gas.

[0071] Furthermore, because the gas seal 54a of the rod packing portion 36 uses hydrogen gas, even if the seal gas leaks into the cylinder portion 31, unexpected events such as liquefaction caused by cooling by the intake gas (hydrogen gas) can be prevented compared to when a different type of gas is used as the seal gas.

[0072] Furthermore, in this embodiment, the pressure of the hydrogen gas in the gas seal portion 54 provided in the rod packing portion 36 is higher than the pressure of the nitrogen gas in the adapter portion 37. This prevents the nitrogen gas being supplied to the adapter portion 37 from overflowing the gas seal portion 54 provided in the rod packing portion 36. This more reliably prevents the nitrogen gas from coming into direct contact with leaked boil-off gas (suction gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder portion 31.

[0073] Furthermore, in this embodiment, not only is the space within the adapter 37 divided into the first space 37a and the second space 37b by the partition 56, but the temperature of the hydrogen gas supplied by the second hydrogen gas supply unit 59 in the first space 37a is higher than the liquefaction temperature of the nitrogen gas in the second space 37b, thereby preventing liquefaction of the nitrogen gas.

[0074] In this embodiment, at least one of the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b is adjusted so that the relationship of pressure P1 > pressure P2 > pressure P3 is established. Therefore, nitrogen gas does not flow from the second space 37b into the first space 37a, and therefore does not flow into the rod packing portion 36. This prevents the nitrogen gas from liquefying.

[0075] Furthermore, unless the pressure in the second space 37b becomes excessive, the open / close valve 68a of the second discharge part 68 is closed, and nitrogen gas is retained in the second space 37b of the adapter part 37. This reduces the amount of nitrogen gas consumed compared to a system that is constantly purged.

[0076] Furthermore, the cylinder portion 31, piston 32, and piston rod 33, which are components of the compression stage 12, become cold during operation. Even when the compressor unit 10 is stopped, they do not immediately return to normal temperature but remain cold for a long time. Meanwhile, when the supply of nitrogen gas is stopped, atmospheric air may enter the second space 37b of the adapter portion 37. If atmospheric air enters the second space 37b while the piston rod 33 remains cold, condensation may form on the piston rod 33. This may cause rust on the internal components, or condensation on the surface of the piston rod 33 may impair the sealing function of the packing rings 41, 43, and 45. However, because nitrogen gas is supplied not only during operation of the compression stage 12 but also when the compressor unit 10 is stopped, rust on the internal components and deterioration of the sealing function can be prevented.

[0077] In this embodiment, the inside of the adapter 37 is divided into the first space 37a and the second space 37b by the partition 56, and a second hydrogen gas supply unit 59 that supplies hydrogen gas to the first space 37a is provided, but this is not limiting. For example, as shown in Fig. 5, the partition 56 and the second hydrogen gas supply unit 59 may be omitted, and nitrogen gas may be supplied to the space inside the adapter 37 by a nitrogen gas supply unit 60.

[0078] In the above embodiment, the pressure of the hydrogen gas in the gas seal portion 54 is adjusted to be higher than the pressure of the nitrogen gas in the adapter portion 37, but this is not limited to this. For example, if the pressure P2 of the hydrogen gas in the first space 37a is higher than the pressure P3 of the nitrogen gas in the second space 37b, the pressure P1 of the hydrogen gas in the gas seal portion 54 may be equal to or lower than the pressure P3 of the nitrogen gas in the adapter portion 37.

[0079] In the above embodiment, at least one of the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b is adjusted so that the relationship of pressure P1 > pressure P2 > pressure P3 is established. However, this is not limited thereto, and at least one of the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b may be adjusted so that the relationship of pressure P1 > pressure P3 > pressure P2 is established. In other words, the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b may constitute a supply-side pressure adjustment means that adjusts the pressure of at least one of the first hydrogen gas supply unit 58, the second hydrogen gas supply unit 59, and the nitrogen gas supply unit 60 so that the relationship of pressure P1 > pressure P3 > pressure P2 is established. In this case, leakage of hydrogen gas, which is a flammable gas, toward the crankcase 38 can be more actively prevented. That is, since the pressure in the second space 37b is higher than the pressure in the first space 37a, the hydrogen gas in the first space 37a can be prevented from leaking out to the crankcase .

[0080] Even in this case, unless the pressure in the second space 37b becomes excessive, the open / close valve 68a of the second discharge part 68 is closed. Therefore, nitrogen gas can be retained in the second space 37b of the adapter part 37, and the amount of nitrogen gas consumed can be reduced compared to a system that is constantly purged.

[0081] In this embodiment, a first exhaust port 67 that exhausts hydrogen gas from the first space 37a and a second exhaust port 68 that exhausts nitrogen gas from the second space 37b are provided. However, the first exhaust port 67 and the second exhaust port 68 may be omitted. That is, the first space 37a may have a sealed structure, so that hydrogen gas that flows into the first space 37a is not exhausted, and the pressure in the first space 37a may be maintained at a predetermined pressure. Alternatively, the second space 37b may have a sealed structure, so that nitrogen gas from the second space 37b is not exhausted, and the pressure in the second space 37b may be maintained at a predetermined pressure. Even in this case, the pressure adjustment means 63 is adjusted to maintain the above-described pressure relationship. This configuration can also be applied to the second and third embodiments and their modifications described below.

[0082] (Second embodiment) 6 shows the second embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0083] In the second embodiment, a feed line 72 is provided that connects the hydrogen flow path 58a of the first hydrogen gas supply unit 58 to the discharge flow path 18. That is, in the first embodiment, the hydrogen flow path 58a is connected to the hydrogen gas source 61, but in the second embodiment, the hydrogen flow path 58a is connected to the discharge flow path 18 via the feed line 72. The feed line 72 allows a portion of the hydrogen gas discharged from the compression stage 12 to the discharge flow path 18 to be sent to the gas seal unit 54. In addition, a leak gas discharge unit 66 that recovers leak gas from the rod packing unit 36 ​​is connected to the suction flow path 21 of the compression stage 12. However, the leak gas discharge unit 66 may be connected to a vent 70.

[0084] Therefore, the leaked hydrogen gas can be collected. Also, there is no need to prepare a separate hydrogen gas for the gas seal 54a.

[0085] Although the description of other configurations, actions, and effects will be omitted, the description of the first embodiment can be applied to the second embodiment.

[0086] (Third embodiment) 7 shows the third embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0087] In the third embodiment, the first hydrogen gas supply unit 58 that supplies hydrogen gas to the rod packing unit 36 ​​is omitted, and the gas seal unit 54 is omitted in the rod packing unit 36. That is, the third embodiment includes a nitrogen gas supply unit 60 that supplies nitrogen gas to the inside of the adapter unit 37, a hydrogen gas supply unit 74 that supplies hydrogen gas to other parts inside the adapter unit 37, and a leaked gas discharge unit 66 that discharges hydrogen gas that has leaked into the rod packing unit 36 ​​to the outside. The hydrogen gas supply unit 74 supplies hydrogen gas to a space (first space 37a) located closest to the compression chamber inside the adapter unit 37. The nitrogen gas supply unit 60 supplies nitrogen gas to at least one space (second space 37b) located closer to the crank mechanism than the first space 37a inside the adapter unit 37. Note that FIG. 7 shows a configuration in which one partition unit 56 is provided, thereby forming one second space 37b, but for example, two partition units 56 may be provided to form two second spaces 37b. In this case, nitrogen gas is supplied to each of the two second spaces 37b.

[0088] A hydrogen valve 74b, which is a valve that adjusts the pressure of hydrogen gas flowing through the hydrogen flow path 74a, is provided in the hydrogen flow path 74a of the hydrogen gas supply unit 74. The hydrogen valve 74b adjusts the pressure of hydrogen gas in the first space 37a to be higher than the pressure of hydrogen gas in the leak gas discharge unit 66. This prevents hydrogen gas from entering the adapter even if hydrogen gas leaks into the rod packing unit 36 ​​from within the compression chamber 34.

[0089] Therefore, in this embodiment, the pressure of the hydrogen gas in the first space 37a in the adapter portion 37 supplied by the hydrogen gas supply portion 74 is higher than the pressure of the hydrogen gas in the leak gas discharge portion 66. This prevents hydrogen gas leaked to the rod packing portion 36 from entering the space (first space 37a) closest to the compression chamber in the adapter portion 37. This prevents the boil-off gas of liquefied hydrogen, which is a low-temperature gas, from coming into direct contact with nitrogen gas, thereby preventing the nitrogen gas from being liquefied.

[0090] 8, the compression stage 12 may include a separate hydrogen gas supply unit 76 that supplies hydrogen gas to the rod packing unit 36. The separate hydrogen gas supply unit 76 has a separate flow path 76a that is connected to the rod packing unit 36, and the hydrogen gas supplied through the separate flow path 76a forms a gas seal 54a in the gap 50 between the outer circumferential surface of the piston rod 33 and the third case unit 46, on the crank mechanism 14 side of the discharge passage 52.

[0091] The separate flow path 76a is provided with a separate valve 76b, which is a valve with an adjustable opening. The separate valve 76b is adjusted so that the pressure of the hydrogen gas in the gas seal portion 54 is higher than the pressure of the hydrogen gas in the leak gas discharge portion 66. In other words, the pressure of the gas seal 54a formed by the gas seal portion 54 is higher than the pressure in the discharge passage 52, which is located closer to the compression chamber 34 than the gas seal 54a. Therefore, even if hydrogen gas leaks from the compression chamber 34 and then passes through the first packing ring portion 41, it can be prevented from passing through the gas seal 54a.

[0092] 9, a feed line 72 may be provided that connects a hydrogen flow path 74a of a hydrogen gas supply unit 74 to the discharge flow path 18. The feed line 72 allows a portion of the hydrogen gas discharged from the compression stage 12 to the discharge flow path 18 to be sent to the gas seal unit 54.

[0093] 10, the space inside the adapter part 37 may be divided into three spaces by two partition parts 56. The hydrogen gas supply part 74 supplies hydrogen gas to the space (first space 37a) located closest to the compression chamber 34 inside the adapter part 37. The hydrogen gas supply part 74 is provided with a hydrogen valve 74b, which is a valve with an adjustable opening.

[0094] 10, a separate hydrogen gas supply unit 76 is provided to supply hydrogen gas to the rod packing unit 36. The separate hydrogen gas supply unit 76 is provided with a separate valve 76b that is an adjustable valve.

[0095] The nitrogen gas supply unit 60 supplies nitrogen gas to the space (second space 37b) located closest to the crank mechanism 14 within the adapter unit 37. The nitrogen gas supply unit 60 is provided with a nitrogen valve 60b, which is a valve with an adjustable opening. The intermediate chamber 37c between the first space 37a and the second space 37b is provided with a vent discharge unit 77 that discharges gas inside the intermediate chamber 37c to the outside. The vent discharge unit 77 is provided with a valve 77a that opens when the pressure inside the intermediate chamber 37c exceeds a predetermined pressure.

[0096] Furthermore, at least one of the hydrogen valve 74b and the nitrogen valve 60b is adjusted so that the pressure of the hydrogen gas in the first space 37a and the pressure of the nitrogen gas in the second space 37b are higher than the pressure inside the intermediate chamber 37c. Therefore, even if nitrogen gas flows into the intermediate chamber 37c, the nitrogen gas can be prevented from entering the first space 37a.

[0097] In this embodiment, even if nitrogen gas leaks from the space closest to the crank mechanism into the intermediate chamber 37c, this nitrogen gas is less likely to reach the space closest to the compression chamber, thereby more reliably preventing nitrogen from entering the cylinder portion 31.

[0098] Although the description of other configurations, actions and effects will be omitted, the descriptions of the first and second embodiments can be applied to the third embodiment.

[0099] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0100] 10: Compressor unit 12: Compression stage 14: Crank mechanism 18: Discharge flow path 20: Demand destination 21: Suction passage 23: Liquid hydrogen storage tank 31: Cylinder section 32: Piston 33: Piston rod 34: Compression chamber 36: Rod packing part 37: Adapter part 37a: 1st space 37b:Second space 37c: Intermediate room 38: Crankcase 41: First packing ring part 43: Second packing ring part 45: Third packing ring part 50: Gap 52: Discharge passage 54: Gas seal part 54a: Gas seal 56: Partition 58: First hydrogen gas supply unit 59: Second hydrogen gas supply unit 60: Nitrogen gas supply unit 63: Pressure adjusting means 66: Leak gas exhaust 70: Vent 72: Feed line 74: Hydrogen gas supply unit 76: Hydrogen gas supply unit 77: Vent outlet

Claims

1. A compressor unit that draws in hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank, a compression stage for compressing hydrogen gas in an intake passage; a crank mechanism that drives the compression stage; Equipped with The compression stage comprises: A cylinder portion; The piston and a piston rod connecting the piston to the crank mechanism; a rod packing portion that seals between the piston rod and the cylinder portion; an adapter portion that connects the cylinder portion and a case of the crank mechanism; Equipped with the adapter portion includes at least one partition portion that divides the interior thereof into a plurality of spaces; The compression stage comprises: a hydrogen gas supply unit that supplies hydrogen gas to a space inside the adapter unit that is located closest to the compression chamber; a nitrogen gas supply unit that supplies nitrogen gas to at least one space located closer to the crank mechanism than the space located closest to the compression chamber within the adapter unit; a feed line connecting the hydrogen gas supply unit and a discharge flow path, and feeding a portion of the hydrogen gas discharged from the compression stage to the space located closest to the compression chamber; Furthermore, A compressor unit, wherein the temperature of the hydrogen gas in the space located closest to the compression chamber is higher than the liquefaction temperature of the nitrogen gas in at least one space located closer to the crank mechanism.

2. The compression stage comprises:

2. The compressor unit according to claim 1, further comprising a pressure adjusting means for adjusting the pressure of at least one of the hydrogen gas supply unit and the nitrogen gas supply unit so that a relationship of pressure P2 > pressure P3 is established between a hydrogen gas pressure P2 in the space located closest to the compression chamber and a nitrogen gas pressure P3 in the at least one space located on the crank mechanism side.

3. The adapter portion includes: The compressor unit according to claim 2 , wherein a nitrogen gas supply port and a nitrogen gas discharge port are provided in an outer peripheral wall that forms the at least one space located on the crank mechanism side.

4. the compression stage a first discharge portion connected to the adapter portion so as to open into the space located closest to the compression chamber, The compressor unit according to claim 1 , wherein the first discharge portion is connected to the suction passage or a vent.

5. the compression stage 4. The compressor unit according to claim 1, further comprising a seal portion on a periphery of the through hole in the partition portion through which the piston rod passes.

6. 2. The method for operating a compressor unit according to claim 1, wherein the nitrogen gas supply unit supplies nitrogen gas to the inside of the adapter unit not only while the compression stage is operating but also while the compression stage is stopped.

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