Reciprocating compressor unit and method of operating a compressor unit

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 Art

[0002] In recent years, in consideration of the environment, it has been considered to use hydrogen as a fuel for power generation, automobiles, etc., and the demand for hydrogen has been increasing. Also, cryogenic boil-off gas (BOG) such as liquefied natural gas (LNG) and liquid hydrogen (LH2) is recovered by a compressor and supplied to a demand destination such as an engine. In particular, the boil-off gas generated from LH2 is extremely low in temperature. For this reason, if a configuration is adopted in which the compressor directly inhales the boil-off gas, there are restrictions such as the need to select materials suitable for extremely low temperatures, adopt design conditions considering the amount of thermal deformation, or perform strict heat treatment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the following problems are pointed out in Patent Document 1. "In recent years, hydrogen has attracted attention as a new energy source. Even when hydrogen is used as an energy source, it is assumed that it will be in a liquefied state during storage and transportation, like natural gas. However, hydrogen has the property that its liquefaction temperature is lower than that of air. Therefore, if equipment such as a reciprocating compressor for natural gas is directly applied to hydrogen, problems caused by extremely low-temperature liquid hydrogen may occur. For example, liquefied air may be generated around the device 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 cylinder portion disposed between the piston drive portion and the container portion and accommodating the piston rod. In the intermediate cylinder portion, a first intermediate chamber, a second intermediate chamber, and a rod packing chamber are formed in 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 normal-temperature hydrogen gas. The first intermediate chamber is filled with nitrogen gas. The vent is provided at a position corresponding to the second intermediate chamber.

[0005] It is disclosed that with such a structure, it is possible to suppress the leakage of hydrogen gas from the compression part to the piston drive part, and to ensure the operation of the piston drive part by suppressing the leakage of extremely low-temperature gas.

[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 may flow into the rod packing chamber. And when the nitrogen gas comes into contact with the extremely low-temperature hydrogen gas (the suction gas of the compressor), the nitrogen gas may liquefy.

[0007] Incidentally, the reciprocating compressor disclosed in Patent Document 2 has the following configuration. "The compressed gas branched from the discharge passage 7 is cooled by the gas cooler 23 and led into the cooling chamber 22 through the discharge passage side portion 28a of the cooling passage 28 in the packing case 10, thereby directly cooling the piston rod 1. Then, the compressed gas is returned to the suction passage 5 through the suction passage side portion 28b of the cooling passage 28 in the packing case 10." In Patent Document 2, since the purpose is to cool the piston rod 1, the compressed gas flows smoothly through the cooling chamber 22. Such a structure is not necessarily appropriate for the purpose of avoiding contact between nitrogen gas and extremely low-temperature hydrogen gas (the suction gas of the compressor).

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

Means for Solving the Problems

[0009] The compressor unit according to 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 part of the recovered hydrogen gas to a customer including at least one of an engine, a power generation facility, or a boiler. The compressor unit includes a compression stage that compresses hydrogen gas in a suction flow path, and a crank mechanism that drives the compression stage. The compression stage includes a cylinder part, a piston, a piston rod that connects the piston to the crank mechanism, a rod packing part that seals between the piston rod and the cylinder part, an adapter part that connects the cylinder part and a case of the crank mechanism, a nitrogen gas supply part that supplies nitrogen gas inside the adapter part, a leak gas discharge part that discharges hydrogen gas leaked to the rod packing part to the outside, and a hydrogen gas supply part that supplies hydrogen gas to the rod packing part. The rod packing part includes at least one packing ring part that contacts and seals the piston rod, a discharge passage that is connected to the leak gas discharge part and allows hydrogen gas, which is a part of the gas compressed in the cylinder part and leaks through the packing ring part, to flow into the leak gas discharge part, a gas seal part that forms a gas seal in a gap with the piston rod by supply of hydrogen gas from the hydrogen gas supply part on the crank mechanism side rather than the discharge passage, and at least one other packing ring part that is disposed between the gas seal part and the discharge passage. The pressure of hydrogen gas in the gas seal part is higher than the pressure of hydrogen gas in the leak gas discharge part.

[0010] In the compressor unit according to the present invention, a discharge passage is provided in the rod packing portion, and this discharge passage is connected to the leak gas discharge portion. Therefore, the hydrogen gas leaking through the packing ring portion is discharged to the outside through the discharge passage and the leak gas discharge portion. Further, a gas seal portion using hydrogen gas is provided in the rod packing portion on the crankcase side rather than the discharge passage side, and the pressure of the hydrogen gas in the gas seal portion is made higher than the pressure in the leak gas discharge portion. Thereby, it is possible to prevent the boil-off gas (suction gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder portion, from exceeding the gas seal portion and entering the adapter portion side and the crankcase side, and thereby prevent the liquefaction of nitrogen gas.

[0011] Also, in the gas seal of the rod packing portion, since hydrogen gas is used, even when the seal gas leaks into the cylinder portion, it is possible to prevent unexpected situations such as liquefaction that occur when cooled by the suction gas (hydrogen gas) compared to the case where 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 aspect, since the pressure of the hydrogen gas in the gas seal portion provided in the rod packing portion is higher than the pressure of the nitrogen gas in the adapter portion, it is possible to prevent the nitrogen gas supplied to the adapter portion from exceeding the gas seal portion provided in the rod packing portion. Therefore, it is more reliably prevented that the leaked gas of the boil-off gas (suction gas) of liquefied hydrogen, which is a low-temperature gas compressed in the cylinder portion, comes into direct contact with the nitrogen gas.

[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 partitions its interior into a space on the compression chamber side and a space on the crank mechanism side. Also, the other hydrogen gas supply unit supplies hydrogen gas to the space on the compression chamber side, the nitrogen gas supply unit supplies 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 aspect, since the adapter unit includes a partition unit, contact between the low-temperature boil-off gas (suction gas) and nitrogen gas can be more reliably prevented. Since the temperature of the hydrogen gas in the space on the compression chamber side supplied by the other hydrogen gas supply unit is higher than the liquefaction temperature of the nitrogen gas in the space on the crank mechanism side, liquefaction of the nitrogen gas can be prevented.

[0016] The compression stage may further include 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 pressure P1 of the hydrogen gas in the gas seal part, the pressure P2 of the hydrogen gas in the space on the compression chamber side of the adapter unit, and the pressure P3 of the nitrogen gas in the space on the crank mechanism side.

[0017] In this aspect, since nitrogen gas does not flow from the space on the crank mechanism side into the space on the compression chamber side, nitrogen gas does not flow into the rod packing part. Therefore, liquefaction of the nitrogen gas can be prevented.

[0018] The adapter part is provided with a nitrogen gas supply port and a discharge port on the outer peripheral wall forming the space on the crank mechanism side, and may further include discharge side pressure adjusting means capable of discharging nitrogen gas when the pressure at the discharge port becomes a predetermined pressure or more. In this case, the compression stage may further include supply side pressure adjusting means for adjusting the pressure of at least one of the hydrogen gas supply part, the other hydrogen gas supply part, and the nitrogen gas supply part so that the relationship of pressure P1 > pressure P3 > pressure P2 is established among the pressure P1 of hydrogen gas in the gas seal part, the pressure P2 of hydrogen gas in the space on the compression chamber side of the adapter part, and the pressure P3 in the space on the crank chamber side.

[0019] In this aspect, it is possible to more actively prevent leakage of hydrogen gas, which is a combustible gas, to the crankcase side.

[0020] The leak gas discharge part may be connected to the suction flow path to return the leaked hydrogen gas to the suction flow path. In this case, the compression stage may further include a feed line that connects the hydrogen gas supply part and the discharge flow path and sends a part of the hydrogen gas discharged from the compression stage to the gas seal part.

[0021] In this aspect, the leaked hydrogen gas can be recovered. Also, it is not necessary to separately prepare hydrogen gas for gas sealing.

[0022] The compressor unit according to 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 part of the recovered hydrogen gas to a demand destination including at least one of an engine, a power generation facility, or a boiler. The compressor unit includes a compression stage that compresses hydrogen gas in a suction passage, and a crank mechanism that drives the compression stage. The compression stage includes a cylinder part, a piston, a piston rod that connects the piston to the crank mechanism, a rod packing part that seals between the piston rod and the cylinder part, an adapter part that connects the cylinder part and a case of the crank mechanism, a nitrogen gas supply part that supplies nitrogen gas inside the adapter part, a hydrogen gas supply part that supplies hydrogen gas to another part inside the adapter part, and a leak gas discharge part that discharges hydrogen gas leaked to the rod packing part to the outside. The rod packing part includes at least one packing ring part that contacts and seals the piston rod, a discharge passage that is connected to the leak gas discharge part and allows hydrogen gas, which is a part of the gas compressed in the cylinder part and leaked through the packing ring part, to flow into the leak gas discharge part, and at least one other packing ring part that is disposed closer to the crank mechanism side than the discharge passage. The adapter part includes at least one partition part that partitions the inside into a plurality of spaces. The hydrogen gas supply part supplies hydrogen gas to a space located closest to the compression chamber inside the adapter part. The nitrogen gas supply part supplies nitrogen gas to at least one space located closer to the crank mechanism side than the space located closest to the compression chamber inside the adapter part. The pressure of hydrogen gas in the space located closest to the compression chamber is higher than the pressure of hydrogen gas in the leak gas discharge part.

[0023] In the compressor unit according to the present invention, the pressure of the hydrogen gas in the space located closest to the compression chamber inside the adapter unit, which is supplied by the hydrogen gas supply unit, is higher than the pressure of the hydrogen gas in the leak gas discharge unit. Therefore, it is possible to prevent the hydrogen gas leaking into the rod packing unit from entering the space closest to the compression chamber side in the adapter unit. As a result, it is possible to prevent the boil-off gas of liquefied hydrogen, which is a low-temperature gas, from directly contacting the nitrogen gas and prevent the liquefaction of the 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 the gap between the piston rod by supplying hydrogen gas from the other hydrogen gas supply unit on the crank mechanism side rather than the discharge passage. Further, a part of at least one of the other packing ring units may be present 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 unit can prevent leak gas from the cylinder unit.

[0026] The adapter unit may include two partition parts that partition the inside into three spaces. In this case, the hydrogen gas supply unit supplies hydrogen gas to the space located closest to the compression chamber side inside the adapter unit, the nitrogen gas supply unit supplies nitrogen gas to the space located closest to the crank mechanism side inside the adapter unit, and a vent discharge unit that discharges the gas inside the intermediate chamber to the outside may be provided in the intermediate chamber of the adapter unit. Further, the pressure of the hydrogen gas in the space closest to the compression chamber side and the pressure of the nitrogen gas in the space located closest to the crank mechanism side may be set to be higher than the pressure inside the intermediate chamber.

[0027] In this aspect, even if nitrogen gas leaks from the space closest to the crank mechanism side into the intermediate chamber, it is difficult for this nitrogen gas to reach the space closest to the compression chamber side, so that the entry of nitrogen into the cylinder part can be more reliably prevented.

[0028] The leak gas discharge part may be connected to the suction flow path to return the leaked hydrogen gas to the suction flow path. In this case, the compression stage may further include a feed line that connects the other hydrogen gas supply part and the discharge flow path and sends a part of the hydrogen gas discharged from the compression stage to the gas seal part.

[0029] In this aspect, the leaked hydrogen gas can be recovered. Also, it is not necessary to separately prepare hydrogen gas for gas sealing.

[0030] The supply of nitrogen gas into the adapter part by the nitrogen gas supply part may be performed not only during the operation of the compression stage but also during the stop of the compression stage.

[0031] In this aspect, the cylinder part, piston, and piston rod, which are components of the compression stage, become low-temperature during operation, and even when the compressor unit stops, they do not immediately return to normal temperature but remain in a low-temperature state for a long time. On the other hand, when the supply of nitrogen gas is stopped, air may enter the space on the crank mechanism side of the adapter part. When the piston rod is in a low-temperature state and air enters the space on the crank mechanism side, condensation may occur on the piston rod. In that case, rusting of internal parts and adhesion of condensation to the surface of the piston rod may cause the packing ring to lose its sealing function. However, since nitrogen gas is supplied not only during the operation of the compression stage but also during the stop, rusting of internal parts and deterioration of the sealing function can be prevented.

Effect of the Invention

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

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0034] Hereinafter, the modes for carrying out the present invention will be described in detail with reference to the 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 demand destination. The boil-off gas, which is hydrogen gas, is at approximately -253°C. The demand destinations include at least one of an engine, a power generation facility, or a boiler. In addition to these, for example, facilities other than those that utilize gas such as gas combustion facilities, flare facilities, and vents as an energy source may be included. Further, the hydrogen gas discharged from the compressor unit does not necessarily have to be directly supplied to the demand destination. For example, after being filled into cylinders or the like, it may be supplied to the demand destination by various means such as transporting the cylinders or gas pipes connected to the cylinders.

[0036] As shown in FIG. 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 includes a second compression stage 16 for further compressing the hydrogen gas compressed by the compression stage 12. That is, the hydrogen gas compressed by the compression stage 12 is discharged into the discharge flow path 18, and the second compression stage 16 is provided in this discharge flow path 18. The hydrogen gas compressed by the second compression stage 16 is supplied to the demand destination 20.

[0037] The compression stage 12 is connected to the liquid hydrogen storage tank 23 via a suction flow path 21. Therefore, the 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 flow path 21.

[0038] The crank mechanism 14 drives these compression stage 12 and the second compression stage 16 collectively. Note that the configuration is not limited to this. For example, the second compression stage 16 may be omitted, and the crank mechanism 14 may be configured to drive only one compression stage 12. Further, 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 includes a spillback portion 25 for returning the hydrogen gas discharged from the compression stage 12 to the suction passage 21, and a second spillback portion 27 for returning the hydrogen gas discharged from the second compression stage 16 to the suction passage 21.

[0040] The spillback portion 25 has a spillback passage 25a and a spillback valve 25b composed of a valve with an adjustable opening degree disposed in the spillback passage 25a. One end of the spillback passage 25a is connected to a portion of the discharge passage 18 upstream of the second compression stage 16, and the other end is connected to the suction passage 21. By controlling the spillback valve 25b, the pressure and flow rate of the hydrogen gas inhaled into the second compression stage 16 are adjusted. Note that the spillback portion 25 can be omitted.

[0041] The second spillback portion 27 has a second spillback passage 27a and a second spillback valve 27b composed of a valve with an adjustable opening degree disposed in the second spillback passage 27a. One end of the second spillback passage 27a is connected to a portion of the discharge passage 18 downstream of the second compression stage 16, and the other end is connected to the suction passage 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 when the main purpose is to equalize the pressure between the suction passage 21 and the discharge passage 18 when the compressor unit 10 stops, a manual valve or an ON - OFF valve may be adopted as the second spillback valve 27b.

[0042] As shown in FIG. 2, the compression stage 12 is constituted 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. As the piston 32 reciprocates within the cylinder portion 31, the hydrogen gas is compressed within the compression chamber 34.

[0043] In addition, although FIG. 2 shows the compression stage 12 of a double-acting structure, a single-acting structure may be adopted for the compression stage 12. Further, the compression stage 12 does not necessarily have to be constituted by a single cylinder, and may be constituted by a plurality of parallel compression stages. That is, the compression stage 12 may be configured such that hydrogen gas is compressed and pressurized by pistons 32 in a plurality of cylinder parts 31 connected in parallel, respectively.

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

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

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

[0047] As shown in FIG. 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 still other packing ring portion (third packing ring portion 45), and still another 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 arranged on the side opposite to 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 arranged on the side opposite to 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] Note that FIG. 3 shows a configuration in which a plurality of first packing ring portions 41 are provided in each of the plurality of first case portions 42, a plurality of second packing ring portions 43 are provided in one second case portion 44, and a plurality of third packing ring portions 45 are provided in one third case portion 46, but the configuration is not limited thereto. For example, a configuration in which one packing ring portion 41, 43, 45 is provided in each of the case portions 42, 44, 46 may be used. By arranging a plurality of packing ring portions 41, 43, 45 in each of the case portions 42, 44, 46, the sealing performance can be further improved, making it more suitable for a high-pressure compression stage.

[0049] The first case portion 42, the second case portion 44, and the third case portion 46 are arranged in the direction in which the piston rod 33 extends and are disposed within 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 the flange portion 47.

[0050] In each of the first case part 42, the second case part 44, and the third case part 46, a through-hole for penetrating the piston rod 33 is formed, and a gap 50 is formed between the peripheral portion partitioning the through-hole in 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, respectively.

[0051] The packing ring parts 41, 43, 45 are arranged side by side in the extending direction of the piston rod 33 and are arranged so as to surround the piston rod 33. The packing ring parts 41, 43, 45 are deformed so as to be in close contact with the outer peripheral surface of the piston rod 33 by high-pressure hydrogen gas. Note that the packing ring parts 41, 43, 45 may be formed to have a size that is in close contact with the outer peripheral surface of the piston rod 33 even when no pressure of high-pressure hydrogen gas is applied, or may be configured to be in close contact with the outer peripheral surface by being pressed by a spring.

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

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

[0054] As shown in FIG. 2, the adapter portion 37 includes a partition portion 56 that partitions 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). The piston rod 33 also penetrates through this partition portion 56. A seal portion 56a is provided at the peripheral edge of the through-hole that penetrates the piston rod 33 in the partition portion 56.

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

[0056] The first hydrogen gas supply portion 58 has a hydrogen flow passage 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 portion 54 in the rod packing portion 36 through this hydrogen flow passage 58a. The first hydrogen gas supply portion 58 supplies hydrogen gas to the gap 50 where packing ring portions exist on both sides (that is, the gap 50 between the first packing ring portion 41 and the second packing ring portion 43). The hydrogen gas source 61 stores hydrogen gas at normal 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 forms the first space 37a in the adapter unit 37. The second hydrogen gas supply unit 59 supplies hydrogen gas from the hydrogen gas source 61 into the first space 37a in the adapter unit 37 through the second hydrogen flow path 59a. Therefore, 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 the 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 into the second space 37b in the adapter unit 37 through this nitrogen flow path 60a. The nitrogen gas source 62 stores nitrogen gas at normal temperature.

[0059] A first hydrogen valve 58b, which is a valve for adjusting the pressure of the hydrogen gas flowing through the hydrogen flow path 58a, is provided in the hydrogen flow path 58a. A second hydrogen valve 59b, which is a valve for adjusting the pressure of the hydrogen gas flowing through the second hydrogen flow path 59a, is provided in the second hydrogen flow path 59a of the second hydrogen gas supply unit 59. A nitrogen valve 60b, which is a valve for adjusting the pressure of the nitrogen gas flowing through the nitrogen flow path 60a, is provided in the nitrogen flow path 60a.

[0060] The first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b constitute a pressure adjusting means 63 for adjusting at least one of the pressure of the hydrogen gas supplied by the first hydrogen gas supply section 58, the pressure of the hydrogen gas supplied by the second hydrogen gas supply section 59, and the pressure of the nitrogen gas supplied by the nitrogen gas supply section 60. For example, when the pressure of the hydrogen gas in the gas seal section 54 is defined as pressure P1, the pressure of the hydrogen gas in the first space 37a in the adapter section 37 is defined as pressure P2, and the pressure of the nitrogen gas in the second space 37b in the adapter section 37 is defined as 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 is established. That is, since the pressure in the first space 37a into which the normal-temperature hydrogen gas is introduced is higher than the pressure in the second space 37b into which the nitrogen gas is introduced, the nitrogen gas in the second space 37b is prevented from entering the first space 37a. Further, since the pressure in the gas seal section 54 is higher than the pressure in the first space 37a, even if the nitrogen gas were to enter the first space 37a by chance, this nitrogen gas is prevented from entering the rod packing section 36.

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

[0062] The leak gas discharge portion 66 is constituted by a pipe member connected to the rod packing portion 36 so as to communicate with the discharge passage 52 (FIG. 3) provided in the rod packing portion 36. The leak gas discharge portion 66 is connected to the suction passage 21 for allowing hydrogen gas to flow into the compression chamber 34 of the compression stage 12. Since the discharge passage 52 communicates with the leak gas discharge portion 66, the hydrogen gas that has leaked from the compression chamber 34 and passed through the first packing ring portion 41 can be returned to the suction passage 21 through the discharge passage 52 and the leak gas discharge portion 66. A check valve 69 for preventing the hydrogen gas from flowing toward the rod packing portion 36 is provided in the leak gas discharge portion 66. Note that the leak gas discharge portion 66 may be connected to the vent 70 instead of being connected to the suction passage 21 of the compression stage 12. Also, in the second compression stage 16 as well, a leak gas discharge portion may be provided so as to communicate with a discharge passage provided in the rod packing portion in the same manner as in the compression stage 12. The leak gas discharge portion is connected to the suction passage 21.

[0063] The first discharge portion 67 is connected to the adapter portion 37 so as to open into the first space 37a. That is, one end of the first discharge portion 67 is connected to a discharge port formed in the outer peripheral wall of the adapter portion 37 that forms the first space 37a. The other end of the first discharge portion 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. Note that the first discharge portion 67 may be connected to the vent 70 instead of being connected to the suction passage 21 of the compression stage 12.

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

[0065] An opening / closing valve 68a is provided in the second discharge section 68. The opening / closing valve 68a constitutes a discharge-side pressure adjustment means for discharging nitrogen gas when the pressure at the nitrogen gas discharge port in the adapter section 37 reaches a pressure equal to or higher than a predetermined pressure. Therefore, when the pressure in the second space 37b in the adapter section 37 becomes equal to or higher than the predetermined pressure, the opening / closing valve 68a opens, and the nitrogen gas in the second space 37b is discharged to the vent 70. That is, the opening / closing valve 68a may be constituted by a relief valve.

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

[0067] While the crank mechanism 14 is being driven, the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b are open. For this reason, hydrogen gas is supplied from the first hydrogen gas supply section 58 to the gas seal section 54, hydrogen gas is supplied from the second hydrogen gas supply section 59 to the first space 37a in the adapter section 37, and nitrogen gas is supplied from the nitrogen gas supply section 60 to the first space 37a in the adapter section 37 (step ST12). At this time, the relationship of pressure P1 (pressure of hydrogen gas in the gas seal section 54) > pressure P2 (pressure of hydrogen gas in the first space 37a in the adapter section 37) > pressure P3 (pressure of nitrogen gas in the second space 37b in the adapter section 37) holds. Therefore, it is possible to prevent nitrogen gas from entering the first space 37a from the second space 37b. Further, even if nitrogen gas should happen to enter the first space 37a, it is possible to prevent the nitrogen gas from entering the rod packing section 36.

[0068] When receiving a command to stop the compressor unit 10, 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, the supply of nitrogen gas into the adapter unit 37 is performed not only during the operation of the compression stage 12 but also during the stop of the compression stage 12. 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. For this reason, 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. Therefore, in order to prevent the atmosphere from entering the second space 37b during the stop of the compression stage 12, the supply of nitrogen gas is continued.

[0069] During the stop of the compression stage 12, it is determined whether 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 is continued. On the other hand, when it returns to normal temperature, since the problem of condensation no longer occurs, it is determined whether the temperature at a predetermined location of the compression stage 12 has returned to a predetermined temperature (for example, a temperature at which it is estimated that no condensation occurs on the piston rod 33). When 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 the supply of hydrogen gas may be continued or stopped while the nitrogen gas is being supplied. Also, the supply of nitrogen gas during the stop of the compressor unit 10 may be continuously performed, but even in that case, it may be stopped during maintenance or the like.

[0070] As described above, in the present embodiment, the discharge passage 52 is provided in the rod packing portion 36, and this discharge passage 52 is connected to the leak gas discharge portion 66. Therefore, the hydrogen gas 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. Further, a gas seal portion 54 by hydrogen gas is provided in the rod packing portion 36 on the crankcase 38 side rather than 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. Thereby, it is possible to prevent the boil-off gas (inlet gas) of the liquefied hydrogen, which is the low-temperature gas compressed in the cylinder portion 31, from penetrating beyond the gas seal portion 54 to the adapter portion 37 side and the crankcase 38 side, and thereby prevent the liquefaction of nitrogen gas.

[0071] Further, in the gas seal 54a of the rod packing portion 36, since hydrogen gas is used, even when the seal gas leaks into the cylinder portion 31, it is possible to prevent unexpected situations such as liquefaction that occur when cooled by the inlet gas (hydrogen gas) compared to the case where a different type of gas is used as the seal gas.

[0072] Further, in the present 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. Therefore, it is possible to prevent the nitrogen gas supplied to the adapter portion 37 from overcoming the gas seal portion 54 provided in the rod packing portion 36. Therefore, it is more reliably prevented that the leaked gas of the boil-off gas (inlet gas) of the liquefied hydrogen, which is the low-temperature gas compressed in the cylinder portion 31, and the nitrogen gas come into direct contact with each other.

[0073] Further, in the present embodiment, not only is the space in the adapter portion 37 partitioned into a first space 37a and a second space 37b by the partition portion 56, but also the temperature of the hydrogen gas in the first space 37a supplied by the second hydrogen gas supply portion 59 is higher than the liquefaction temperature of the nitrogen gas in the second space 37b. Therefore, it is possible to prevent the liquefaction of nitrogen gas.

[0074] Further, in the present 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, since nitrogen gas does not flow from the second space 37b into the first space 37a, nitrogen gas does not flow into the rod packing portion 36. Therefore, liquefaction of nitrogen gas can be prevented.

[0075] Also, as long as the pressure in the second space 37b does not become excessive, the on-off valve 68a of the second discharge portion 68 is closed, and it is configured to hold nitrogen gas in the second space 37b of the adapter portion 37. Thereby, the consumption amount of nitrogen gas can be reduced compared to that of continuous purging.

[0076] Further, the cylinder portion 31, the piston 32, and the piston rod 33, which are components of the compression stage 12, become low-temperature during operation, and even when the compressor unit 10 stops, they do not immediately return to room temperature, but remain in a low-temperature state for a long time. On the other hand, when the supply of nitrogen gas is stopped, air may enter the second space 37b of the adapter portion 37. When air enters the second space 37b with the piston rod 33 in a low-temperature state, condensation may occur on the piston rod 33. In that case, rusting of internal components and adhesion of condensation to the surface of the piston rod 33 may cause the packing ring portions 41, 43, 45 to lose their sealing function. However, since nitrogen gas is supplied not only during the operation of the compression stage 12 but also during the stop, rusting of internal components and deterioration of the sealing function can be prevented.

[0077] In the present embodiment, the inside of the adapter portion 37 is partitioned into a first space 37a and a second space 37b by a partition portion 56, and a second hydrogen gas supply portion 59 for supplying hydrogen gas to the first space 37a is provided, but it is not limited to this. For example, as shown in FIG. 5, the partition portion 56 and the second hydrogen gas supply portion 59 may be omitted, and the nitrogen gas supply portion 60 may be configured to supply nitrogen gas to the space inside the adapter portion 37.

[0078] Also, in the above-described 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 it is not limited thereto. 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] Also, in the above-described 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, it 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. That is, the first hydrogen valve 58b, the second hydrogen valve 59b, and the nitrogen valve 60b may constitute supply-side pressure adjusting means for adjusting 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, it is possible to more actively prevent the leakage of hydrogen gas, which is a combustible gas, to the crankcase 38 side. That is, since the pressure in the second space 37b is higher than the pressure in the first space 37a, it is possible to prevent the hydrogen gas in the first space 37a from leaking to the crankcase 38 side.

[0080] Even in this case, as long as the pressure in the second space 37b does not become excessive, the on-off valve 68a of the second discharge portion 68 is closed. Therefore, since nitrogen gas can be held in the second space 37b of the adapter portion 37, the consumption amount of nitrogen gas can be reduced compared to that of constant purging.

[0081] In this embodiment, a first discharge unit 67 for discharging hydrogen gas in the first space 37a and a second discharge unit 68 for discharging nitrogen gas in the second space 37b are provided, but the first discharge unit 67 and the second discharge unit 68 may be omitted. That is, the first space 37a may have a sealed structure, and the hydrogen gas flowing into the first space 37a may not be discharged, and the pressure in the first space 37a may be maintained at a predetermined pressure. Further, the second space 37b may have a sealed structure, and the nitrogen gas in the second space 37b may not be discharged, and the pressure in the second space 37b may be maintained at a predetermined pressure. Even in this case, the pressure adjusting means 63 is adjusted so that the above-described pressure relationship is maintained. This configuration can also be applied to the second embodiment, the third embodiment, and modifications thereof described later.

[0082] (Second Embodiment) FIG. 6 shows the second embodiment. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0083] In the second embodiment, a feed line 72 that connects the hydrogen flow path 58a of the first hydrogen gas supply unit 58 and the discharge flow path 18 is provided. 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. By the feed line 72, a part of the hydrogen gas discharged from the compression stage 12 to the discharge flow path 18 can be sent to the gas seal unit 54. Further, 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 the vent 70.

[0084] Therefore, the leaked hydrogen gas can be recovered. Further, it is not necessary to separately prepare hydrogen gas for the gas seal 54a.

[0085] Note that descriptions of other configurations, operations, and effects are omitted, but the description of the first embodiment can be applied to the second embodiment.

[0086] (Third Embodiment) FIG. 7 shows the third embodiment. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are 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 in the rod packing unit 36 is omitted. That is, in the third embodiment, a nitrogen gas supply unit 60 that supplies nitrogen gas inside the adapter unit 37, a hydrogen gas supply unit 74 that supplies hydrogen gas to other parts inside the adapter unit 37, and a leak gas discharge unit 66 that discharges the hydrogen gas leaked into the rod packing unit 36 to the outside are provided. The hydrogen gas supply unit 74 supplies hydrogen gas to a space (first space 37a) located on the most compression chamber side inside the adapter unit 37. The nitrogen gas supply unit 60 supplies nitrogen gas to at least one space (second space 37b) located on the crank mechanism side of the first space 37a inside the adapter unit 37. In FIG. 7, a configuration with one partition portion 56 provided is shown, so one second space 37b is formed. However, for example, two partition portions 56 may be provided to form two second spaces 37b. In this case, nitrogen gas is supplied to the two second spaces 37b respectively.

[0088] A hydrogen valve 74b, which is a valve for adjusting the pressure of the 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 is adjusted so that the pressure of the hydrogen gas in the first space 37a is higher than the pressure of the hydrogen gas in the leak gas discharge unit 66. Thereby, even if the hydrogen gas in the compression chamber 34 leaks into the rod packing unit 36, it is possible to prevent this hydrogen gas from entering the adapter.

[0089] Therefore, in the present embodiment, the pressure of the hydrogen gas in the first space 37a within the adapter portion 37 supplied by the hydrogen gas supply portion 74 is higher than the pressure of the hydrogen gas within the leak gas discharge portion 66. For this reason, it is possible to prevent the hydrogen gas that has leaked to the rod packing portion 36 from entering the space (first space 37a) on the most compressor chamber side in the adapter portion 37. As a result, it is possible to prevent the boil-off gas of liquefied hydrogen, which is a cryogenic gas, from directly contacting the nitrogen gas, and to prevent the liquefaction of the nitrogen gas.

[0090] In addition, in the third embodiment, as shown in FIG. 8, the compression stage 12 may include another hydrogen gas supply portion 76 that supplies hydrogen gas to the rod packing portion 36. This another hydrogen gas supply portion 76 has a separate flow path 76a that leads to the rod packing portion 36, and a gas seal 54a is formed in the gap 50 between the outer peripheral surface of the piston rod 33 and the third case portion 46 on the crank mechanism 14 side rather than the discharge passage 52 by the hydrogen gas supplied through this separate flow path 76a.

[0091] A separate valve 76b composed of a valve with an adjustable opening degree is provided in the separate flow path 76a. The separate valve 76b is adjusted so that the pressure of the hydrogen gas within the gas seal portion 54 becomes higher than the pressure of the hydrogen gas within the leak gas discharge portion 66. That is, the pressure of the gas seal 54a formed by the gas seal portion 54 becomes higher than the pressure within the discharge passage 52 located on the compressor chamber 34 side rather than the gas seal 54a. Therefore, even if the hydrogen gas has passed through the first packing ring portion 41 after leaking from within the compressor chamber 34, it is possible to prevent it from passing through the gas seal 54a.

[0092] In the third embodiment, as shown in FIG. 9, a feed line 72 that connects the hydrogen flow path 74a of the hydrogen gas supply portion 74 and the discharge flow path 18 may be provided. By means of the feed line 72, a part of the hydrogen gas discharged from the compression stage 12 to the discharge flow path 18 can be sent to the gas seal portion 54.

[0093] As shown in FIG. 10, the space within the adapter section 37 may be partitioned into three spaces by two partition sections 56. The hydrogen gas supply section 74 supplies hydrogen gas to the space (first space 37a) located closest to the compression chamber 34 within the adapter section 37. The hydrogen gas supply section 74 is provided with a hydrogen valve 74b composed of a valve with adjustable opening degree.

[0094] Also, in the configuration of FIG. 10, another hydrogen gas supply section 76 for supplying hydrogen gas to the rod packing section 36 is provided. The other hydrogen gas supply section 76 is provided with another valve 76b composed of a valve with adjustable opening degree.

[0095] The nitrogen gas supply section 60 supplies nitrogen gas to the space (second space 37b) located closest to the crank mechanism 14 within the adapter section 37. The nitrogen gas supply section 60 is provided with a nitrogen valve 60b composed of a valve with adjustable opening degree. An exhaust vent section 77 for discharging the gas inside the intermediate chamber 37c to the outside is provided in the intermediate chamber 37c between the first space 37a and the second space 37b. The exhaust vent section 77 is provided with a valve 77a that opens when the pressure within the intermediate chamber 37c exceeds a predetermined pressure.

[0096] Further, at least one of the hydrogen valve 74b and the nitrogen valve 60b is adjusted such that the pressure of the hydrogen gas within the first space 37a and the pressure of the nitrogen gas within the second space 37b become higher than the pressure within the intermediate chamber 37c. Therefore, even if nitrogen gas were to flow into the intermediate chamber 37c, it is possible to prevent the nitrogen gas from entering the first space 37a.

[0097] In the present embodiment, even if nitrogen gas leaks from the space located closest to the crank mechanism side into the intermediate chamber 37c, it is difficult for this nitrogen gas to be transmitted to the space closest to the compression chamber side, thus more reliably preventing the mixing of nitrogen into the cylinder section 31.

[0098] Note that although the descriptions of other configurations, operations, and effects are omitted, the descriptions of the first and second embodiments can be incorporated into the third embodiment.

[0099] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The present invention is not limited to the above embodiments, and various changes, improvements, etc. are possible without departing from the spirit thereof.

Explanation of Signs

[0100] 10: Compressor unit 12: Compression stage 14: Crank mechanism 18: Discharge flow path 20: Destination 21: Suction flow path 23: Liquid hydrogen storage tank 31: Cylinder part 32: Piston 33: Piston rod 34: Compression chamber 36: Rod packing part 37: Adapter part 37a: First space 37b: Second space 37c: Intermediate chamber 38: Crank case 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 part 58: First hydrogen gas supply part 59: Second hydrogen gas supply part 60: Nitrogen gas supply part 63: Pressure adjusting means 66: Leak gas discharge part 70: Vent 72: Feed line 74: Hydrogen gas supply part 76: Hydrogen gas supply part 77: Vent discharge part

Claims

1. A reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a part of the recovered hydrogen gas to a customer including at least one of an engine, a power generation facility, or a boiler, a compression stage that compresses hydrogen gas in a suction passage, a crank mechanism that drives the compression stage, and is provided with The compression stage includes a cylinder part, a piston, a piston rod that connects the piston to the crank mechanism, a rod packing part that seals between the piston rod and the cylinder part, an adapter part that connects the cylinder part and the case of the crank mechanism, a nitrogen gas supply part that supplies nitrogen gas inside the adapter part, a leak gas discharge part that discharges hydrogen gas leaked to the rod packing part to the outside, a hydrogen gas supply part that supplies hydrogen gas to the rod packing part, and is provided with The rod packing part includes at least one packing ring part that contacts and seals the piston rod, a discharge passage that is connected to the leak gas discharge part and allows hydrogen gas, which is a part of the gas compressed in the cylinder part and leaked through the packing ring part, to flow into the leak gas discharge part, a gas seal part that forms a gas seal in a gap with the piston rod by supplying hydrogen gas from the hydrogen gas supply part on the side of the crank mechanism rather than the discharge passage, at least one other packing ring part disposed between the gas seal part and the discharge passage, and is provided with The pressure of hydrogen gas in the gas seal part is higher than the pressure of hydrogen gas in the leak gas discharge part. Compressor unit.

2. The compressor unit according to claim 1, wherein the pressure of hydrogen gas in the gas seal portion is higher than the pressure of nitrogen gas in the adapter portion.

3. The compression stage further includes another hydrogen gas supply unit capable of supplying hydrogen gas. The adapter portion includes a partition portion that partitions its interior into a space on the compression chamber side and a space on the crank mechanism side. The other hydrogen gas supply unit supplies hydrogen gas to the space on the compression chamber side. The nitrogen gas supply unit supplies nitrogen gas to the space on the crank mechanism side. The compressor unit according to claim 1 or 2, wherein the temperature of hydrogen gas in the space on the compression chamber side is higher than the liquefaction temperature of nitrogen gas in the space on the crank mechanism side.

4. The compression stage Further includes pressure adjusting means for adjusting at least one of the hydrogen gas supply unit, the other hydrogen gas supply unit, and the nitrogen gas supply unit so that a relationship of pressure P1 > pressure P2 > pressure P3 is established among the pressure P1 of hydrogen gas in the gas seal portion, the pressure P2 of hydrogen gas in the space on the compression chamber side of the adapter portion, and the pressure P3 of nitrogen gas in the space on the crank mechanism side. The compressor unit according to claim 3.

5. The adapter portion A nitrogen gas supply port and a discharge port are provided on the outer peripheral wall forming the space on the crank mechanism side. Further includes discharge side pressure adjusting means capable of discharging nitrogen gas when the pressure of the discharge port becomes equal to or higher than a predetermined pressure. The compression stage Between the pressure P1 of hydrogen gas in the gas seal portion, the pressure P2 of hydrogen gas in the space on the compression chamber side of the adapter portion, and the pressure P3 in the space on the crank chamber side, a supply-side pressure adjusting means for adjusting the pressure of at least one of the hydrogen gas supply portion, the other hydrogen gas supply portion, and the nitrogen gas supply portion is further provided so that the relationship of pressure P1 > pressure P3 > pressure P2 is established. The compressor unit according to claim 3.

6. The leak gas discharge portion is connected to the suction flow path and returns the leaked hydrogen gas to the suction flow path. The compression stage further includes a feed line that connects the hydrogen gas supply portion and the discharge flow path and sends a part of the hydrogen gas discharged from the compression stage to the gas seal portion. The compressor unit according to claim 1.

7. A reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a part of it to a demand destination including at least one of an engine, a power generation facility, or a boiler. A compression stage that compresses the hydrogen gas in the suction flow path. A crank mechanism that drives the compression stage. It is provided with. The compression stage is A cylinder portion. A piston. A piston rod that connects 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 the case of the crank mechanism. A nitrogen gas supply portion that supplies nitrogen gas inside the adapter portion. A hydrogen gas supply portion that supplies hydrogen gas to other parts inside the adapter portion. A leak gas discharge portion that discharges the hydrogen gas leaked to the rod packing portion to the outside. It is provided with. The rod packing portion is At least one packing ring portion that contacts and seals the piston rod A discharge passage that is connected to the leak gas discharge portion and allows a part of the gas compressed in the cylinder portion, which is hydrogen gas that has leaked through the packing ring portion, to flow into the leak gas discharge portion At least one other packing ring portion disposed closer to the crank mechanism side than the discharge passage Comprising The adapter portion includes at least one partition portion that partitions the interior into a plurality of spaces The hydrogen gas supply portion supplies hydrogen gas to the space located closest to the compression chamber inside the adapter portion The nitrogen gas supply portion supplies nitrogen gas to at least one space located closer to the crank mechanism side than the space located closest to the compression chamber inside the adapter portion A compressor unit in which 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 Claim 8 The compression stage Further comprises another hydrogen gas supply portion that supplies hydrogen gas to the rod packing portion The rod packing portion By supplying hydrogen gas from the another hydrogen gas supply portion closer to the crank mechanism side than the discharge passage, further comprises a gas seal portion that forms a gas seal in the gap with the piston rod A part of the at least one other packing ring portion exists between the gas seal portion and the discharge passage The compressor unit according to claim 7, wherein the pressure of the hydrogen gas in the gas seal portion is higher than the pressure of the hydrogen gas in the leak gas discharge portion Claim 9 The adapter portion includes two partition portions that partition the interior into three spaces The hydrogen gas supply unit supplies hydrogen gas to the space located closest to the compression chamber inside the adapter unit, and the nitrogen gas supply unit supplies nitrogen gas to the space located closest to the crank mechanism inside the adapter unit. A vent discharge portion for discharging the gas inside the intermediate chamber to the outside is provided in the intermediate chamber of the adapter unit. The pressure of the hydrogen gas in the space closest to the compression chamber and the pressure of the nitrogen gas in the space located closest to the crank mechanism are set to be higher than the pressure inside the intermediate chamber. The compressor unit according to claim 7.

10. The leak gas discharge portion is connected to the suction flow path and returns the leaked hydrogen gas to the suction flow path. The compression stage further includes a feed line that connects the separate hydrogen gas supply unit and the discharge flow path and sends a part of the hydrogen gas discharged from the compression stage to the gas seal portion. The compressor unit according to claim 8.

11. The supply of nitrogen gas into the adapter unit by the nitrogen gas supply unit is performed not only during the operation of the compression stage but also during the stop of the compression stage. The operation method of the compressor unit according to claim 1 or 7.

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