Compressor unit

Abstract

When the temperature (TS1) acquired by the first temperature sensor is less than a first threshold temperature (T1), the control unit of the compressor unit controls the first switching unit such that the hydrogen gas is sent to the subsequent compression section without passing through the cooling unit. In this case, the return valve is controlled by referring to the suction temperature TS2 acquired by the second temperature sensor such that the suction temperature TS2 falls within a predetermined temperature range. The predetermined temperature range is set in a range higher than a reference temperature based on the liquefaction temperature of the air and less than 0 DEG C.

Description

Technical Field

[0001] The present invention relates to a reciprocating compressor unit. Background Art

[0002] In recent years, research into hydrogen as a fuel for power generation and automobiles has been underway for environmental reasons, leading to a growing demand for hydrogen. Furthermore, low-temperature boil-off gas (BOG) from sources like liquefied natural gas (LNG) and liquefied hydrogen (LH2) is recovered by compressors and supplied to demanding engines and other sources. The boil-off gas produced by LH2 is particularly cold. Therefore, direct intake of the boil-off gas by the compressor is subject to limitations such as the need to select materials suitable for extremely low temperatures, employ design considerations for thermal deformation, and implement rigorous thermal insulation.

[0003] Furthermore, Patent Document 1 below points out the following problem: "In recent years, hydrogen has attracted attention as a new energy source. It is envisioned that, when used as an energy source, hydrogen would be stored and transported in a liquefied state, similar to natural gas. However, hydrogen has a characteristic liquefaction temperature lower than that of air. Therefore, if equipment such as reciprocating compressors designed for natural gas, etc., were directly adapted for hydrogen, there is a risk of adverse effects caused by the extremely low temperature of liquefied hydrogen. For example, this could result in the formation of liquefied air around the equipment supplying liquefied hydrogen."

[0004] In this regard, the following patent document 1 provides the following explanation: "The reciprocating compressor contains a compression section for compressing gas in a container section. Moreover, the container section forms a vacuum region around the compression section. Thus, the compression section is thermally insulated from the external region based on the vacuum region. That is, even when extremely low-temperature gas is supplied to the compression section, the peripheral region of the reciprocating compressor will not be overcooled. Therefore, the generation of liquefied air can be suppressed."

[0005] However, it is generally very difficult to achieve high-performance thermal insulation for power machinery that is accompanied by vibration during operation or equipment that requires regular maintenance through inspection openings (for example, reciprocating compressors).

[0006] Patent Documents 2 and 3 below propose technologies for adjusting the intake gas temperature using a preheater for screw compressors. Furthermore, Patent Document 4 below discloses a reciprocating compressor and a heat exchanger for exchanging heat between boil-off gas before it is drawn into the compressor section and boil-off gas after it is discharged from the compressor section. However, since this heat exchanger is used to reliquefy boil-off gas compressed in the compressor section, boil-off gas cooled by a cooler located downstream of the compressor section is introduced into the heat exchanger.

[0007] On the other hand, the following problem is pointed out in Patent Document 5: "In the past, when BOG (boil-off gas) evaporated in an LNG cryogenic storage tank was compressed and supplied to factory equipment by a cryogenic gas multi-stage compressor, the temperature of the BOG tended to fluctuate over a wide range from more than 100 degrees below zero to room temperature. In particular, immediately after the multi-stage compressor was started, the suction side temperature would rise to near room temperature. If compression was continued in this manner, the output temperature would become higher than the allowable temperature, making it impossible to operate."

[0008] Since liquefied hydrogen has a lower boiling point than LNG, the problems it causes may be more serious than those disclosed in Patent Document 5. Reciprocating compressors that handle boil-off gas from liquefied hydrogen must operate over a wide temperature range, from cryogenic temperatures to room temperature.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-172870

[0012] Patent Document 2: Japanese Patent Publication No. 7085079

[0013] Patent Document 3: Japanese Patent Application Laid-Open No. 2001-65795

[0014] Patent Document 4: Japanese Patent Application Publication No. 2019-27590

[0015] Patent Document 5: Japanese Patent Application Laid-Open No. 4-12178 Summary of the Invention

[0016] An object of the present invention is to appropriately protect components of a reciprocating compressor unit that processes boil-off gas of liquefied hydrogen from wide temperature variations of the boil-off gas.

[0017] One aspect of the present invention relates to a reciprocating compressor unit that recovers boil-off gas, or hydrogen, from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand source, including at least one of an engine, a power generation device, and a boiler. The compressor unit includes multiple compression stages, a crank mechanism, a cooling unit, a first switching unit, a reflux unit, a first temperature sensor, a second temperature sensor, and a control unit.

[0018] The multiple compression sections compress the hydrogen gas sucked in from the intake flow channel. The crank mechanism drives the multiple compression sections. The cooling section is provided in an intermediate flow channel between the multiple compression sections. The first switching unit switches the inflow state of the hydrogen gas to the cooling section. The reflux section includes a reflux flow channel and a reflux valve. The reflux flow channel returns the hydrogen gas output to the output flow channel on the output side of the multiple compression sections, or the hydrogen gas flowing in the intermediate flow channel, to the intake flow channel. The reflux valve adjusts the reflux amount in the reflux flow channel. The first temperature sensor is arranged in the intermediate flow channel. The second temperature sensor is arranged between the connection part of the reflux flow channel in the intake flow channel and the first compression section of the first section among the multiple compression sections. The control section controls each of the first switching unit and the reflux valve.

[0019] In the compressor unit according to the first aspect, the first compression stage and each of the plurality of compression stages subsequent to the first compression stage include a cylinder, a piston, a piston rod, and a rod seal. The piston rod connects the piston to the crank mechanism. The rod seal seals between the piston rod and the cylinder.

[0020] The first compression stage is an air-cooled and oil-free compression stage.

[0021] The control unit performs the following control on the first switching unit and the return valve.

[0022] During startup, when temperature TS1 acquired by the first temperature sensor is equal to or greater than a predetermined first temperature threshold value T1 greater than 0° C., the control unit controls the first switching means to enter a first switching state. The first switching state is a state in which hydrogen gas output from the first compression stage flows to the cooling unit and is cooled by the cooling unit.

[0023] The control unit controls the first switching means to enter a second switching state when the temperature TS1 obtained by the first temperature sensor is less than the first temperature threshold T1. The second switching state is a state in which the hydrogen gas is sent to the compression stage downstream of the location where the cooling unit is provided, without passing through the cooling unit.

[0024] When the first switching unit is in the second switching state, the control unit controls the return valve with reference to the suction temperature TS2 acquired by the second temperature sensor so that the suction temperature TS2 falls within a predetermined temperature range.

[0025] In the compressor unit according to the above aspect, the predetermined temperature range is set to a range higher than a reference temperature based on the liquefaction temperature of air and lower than 0°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram schematically showing the configuration of a compressor unit according to the first embodiment.

[0027] Figure 2 This is a diagram schematically showing the configuration of the first compression stage in the compressor unit.

[0028] Figure 3 This is a diagram schematically showing the configuration of the subsequent compression stage in the compressor unit.

[0029] Figure 4 This is a flowchart showing the operation control executed by the control unit during the operation of the compressor unit.

[0030] Figure 5 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the first embodiment.

[0031] Figure 6 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the first embodiment.

[0032] Figure 7 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the first embodiment.

[0033] Figure 8 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the first embodiment.

[0034] Figure 9 This is a diagram schematically showing a partial configuration of a compressor unit according to the second embodiment.

[0035] Figure 10 This is a flowchart showing the operation control executed by the control unit during the operation of the compressor unit.

[0036] Figure 11 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the second embodiment.

[0037] Figure 12 This is a diagram schematically showing a partial configuration of a compressor unit according to a third embodiment.

[0038] Figure 13 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the third embodiment.

[0039] Figure 14 This is a diagram schematically showing a partial configuration of a compressor unit according to a fourth embodiment.

[0040] Figure 15 This is a flowchart showing the operation control executed by the control unit during the operation of the compressor unit.

[0041] Figure 16 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the fourth embodiment.

[0042] Figure 17 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the fourth embodiment.

[0043] Figure 18 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the fourth embodiment.

[0044] Figure 19 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the fourth embodiment.

[0045] Figure 20 This is a diagram schematically showing a partial configuration of a compressor unit according to the fifth embodiment.

[0046] Figure 21 This is a flowchart showing control of the adjustment unit in the operation control performed by the control unit during operation of the compressor group.

[0047] Figure 22 This is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the fifth embodiment.

[0048] Figure 23 This is a diagram schematically showing a partial configuration of a compressor unit according to another modified example.

[0049] Figure 24 This is a diagram schematically showing a partial configuration of a compressor unit according to another modified example. DETAILED DESCRIPTION

[0050] The following describes embodiments of the present invention with reference to the accompanying drawings. The embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for its basic configuration.

[0051] [First embodiment]

[0052] The compressor unit in this embodiment is a reciprocating compressor unit that recovers boil-off gas (hydrogen) from a liquefied hydrogen storage tank, compresses the recovered hydrogen, and supplies it to a demand side. The temperature of the boil-off gas is approximately -253°C.

[0053] like Figure 1As shown, the compressor unit 10 includes: a plurality of compression stages (a first compression stage 12 and a subsequent compression stage 14 ) for compressing hydrogen gas sucked into the flow path 21 ; and a crank mechanism 16 for driving the first compression stage 12 and the subsequent compression stage 14 .

[0054] The first compression stage 12 is connected to the liquefied hydrogen storage tank 23 via the suction flow path 21 . Therefore, boil-off gas of the liquefied gas generated in the liquefied hydrogen storage tank 23 is sucked into the first compression stage 12 through the suction flow path 21 .

[0055] The first compression section 12 has a reciprocating compression mechanism. Figure 2 As shown, the first compression stage 12 includes a piston 212 disposed within a cylinder 211, a piston rod 213 connected to the piston 212, a pair of intake valves 214, and a pair of output valves 215. Compression chambers 216 are formed within the cylinder 211 between the front cover 211a and the piston 212, and between the rear cover 211b and the piston 212. The first compression stage 12 is configured as an air-cooled compression stage and has an oil-free compression mechanism that does not use lubricating oil.

[0056] A rod seal 217 is provided on the rear cover 211b of the cylinder 211 to prevent hydrogen gas from leaking from the compression chamber 216. Rod seal 217 is configured to seal between the piston rod 213 and the cylinder 211. Rod seal 217 includes a seal ring 217a disposed to surround the piston rod 213 and a housing 217b that holds the seal ring 217a.

[0057] The piston 212 is connected to the crank mechanism 16 via the piston rod 213. As the piston 212 reciprocates in the cylinder 211, hydrogen gas is compressed in the compression chamber 216. Figure 2 , a double-acting structure of the first compression section 12 is shown, but the first compression section 12 may also adopt a single-acting structure.

[0058] In addition, Figure 1 In the figure, the first compression section 12 is represented by a trapezoid for convenience, but the first compression section 12 may have a plurality of cylinder sections 211. That is, the first compression section 12 may be constructed such that hydrogen is compressed and pressurized based on the reciprocating movement of each piston 212 in a plurality of cylinder sections 211 connected in parallel. In addition, a compression mechanism having a plurality of compression sections may be provided between the suction flow channel 21 and the intermediate flow channel 22. That is, the first compression section 12 may be constructed such that hydrogen is compressed and pressurized in sequence based on each piston 212 in a plurality of cylinder sections 211. This is also the case in other embodiments described later.

[0059] The subsequent compression section 14 is connected to the first compression section 12 via the intermediate flow channel 22, and is equipped with a compression mechanism for further compressing the hydrogen output from the first compression section 12. The hydrogen compressed by the subsequent compression section 14 is output to the output flow channel 24. The hydrogen flowing into the output flow channel 24 is transported to the demand end D1. The hydrogen output from the compressor unit does not necessarily have to be directly supplied to the demand end D1. The hydrogen can also be supplied to the demand end D1 by various means such as transporting the gas cylinder or gas piping connected to the gas cylinder after filling the hydrogen into a gas cylinder, for example. The high-pressure demand end D1 includes at least one of an engine, a power generation device and a boiler, but in addition to these devices, it can also include equipment such as flame equipment and a gas relief valve that discharges gas to the atmosphere.

[0060] like Figure 3 As shown, similar to the first compression stage 12, the subsequent compression stage 14 includes a reciprocating compression mechanism. The piston 212 of the subsequent compression stage 14 is also connected to the crank mechanism 16 via a piston rod 213. The subsequent compression stage 14 is also provided with a leakage gas discharge portion 29 that returns leakage gas from the rod seal 217 to the suction flow passage 21. The leakage gas discharge portion 29 can include a pipe member that is provided to connect the rod seal 217 and the suction flow passage 21.

[0061] In addition, Figure 1 For convenience, the subsequent compression stage 14 is represented by a trapezoid. However, the subsequent compression stage 14 does not necessarily have to employ a single-stage compression mechanism; a multi-stage compression mechanism may also be employed. Specifically, the subsequent compression stage 14 may be configured such that hydrogen gas is sequentially compressed and pressurized within multiple cylinders 211 based on the reciprocating motion of the pistons 212. This applies to other embodiments as well. Within the subsequent compression stage 14, the compression stage that outputs hydrogen gas at room temperature may employ either a non-oiled or lubricated system.

[0062] like Figure 1 As shown, the compressor unit 10 includes: a reflux section SB1, which returns a portion of the hydrogen gas output from the subsequent compression section 14 to the output flow channel 24 to the intake flow channel 21. The reflux section SB1 includes: a reflux flow channel 18a; and a reflux valve 18b, which is arranged in the reflux flow channel 18a and includes a valve capable of adjusting the opening. One end of the reflux flow channel 18a is connected to the output flow channel 24, and the other end is connected to the intake flow channel 21. In other words, the hydrogen gas flowing in the reflux flow channel 18a merges with the hydrogen gas from the liquefied hydrogen storage tank 23 in the intake flow channel 21. The reflux valve 18b adjusts the reflux amount in the reflux flow channel 18a.

[0063] The compressor unit 10 includes a cooling unit 58 disposed in the intermediate flow passage 22 between the first compression stage 12 and the subsequent compression stage 14. The intermediate flow passage 22 has branched flow passages (a first flow passage 22a and a second flow passage 22b) at a midpoint thereof, and the cooling unit 58 is disposed in one of the flow passages (the first flow passage 22a).

[0064] A first switching unit CV1 is provided at the branch point of the first flow channel 22a and the second flow channel 22b on the intermediate flow channel 22. However, the first switching unit CV1 can be provided in the first flow channel 22a or in the second flow channel 22b. In the present embodiment, as an example, the first switching unit CV1 includes a three-way valve 59a. The first switching unit CV1 is capable of switching the flow path of hydrogen between a first switching state and a second switching state. The first switching state is a state in which the hydrogen output from the first compression section 12 is circulated to the cooling portion 58 and cooled by the cooling portion 58, and the hydrogen is caused to flow into the subsequent compression section 14. The second switching state is a state in which the hydrogen output from the first compression section 12 does not pass through the cooling portion 58 and flows into the subsequent compression section 14. In the present embodiment, the first switching unit CV1 including the three-way valve 59a is used as an example, but is not limited to this. For example, an on-off valve capable of taking two positions, fully open and fully closed, or a regulating valve capable of adjusting the hydrogen flow rate to the first flow channel 22a and the hydrogen flow rate to the second flow channel 22b may be used.

[0065] The compressor unit 10 includes an upstream temperature sensor (second temperature sensor) 45 and an intermediate temperature sensor (first temperature sensor) 46. The upstream temperature sensor 45 is a temperature sensor that detects the temperature of the hydrogen gas flowing in the intake flow channel 21. The upstream temperature sensor 45 is arranged in the intake flow channel 21 between the connection portion of the return flow channel 18a and the first compression stage 12. Therefore, when hydrogen gas flows in the return flow channel 18a, the upstream temperature sensor 45 can obtain the temperature TS2 of the hydrogen gas that is drawn into the first compression stage 12 after the hydrogen gas from the return flow channel 18a merges with the hydrogen gas from the liquefied hydrogen storage tank 23.

[0066] The intermediate temperature sensor 46 is a temperature sensor that detects the temperature of the hydrogen gas flowing through the intermediate flow channel 22. The intermediate temperature sensor 46 is located in the intermediate flow channel 22 between the first compression stage 12 and the branch point between the first flow channel 22a and the second flow channel 22b in the intermediate flow channel 22. Therefore, the intermediate temperature sensor 46 can obtain the temperature of the hydrogen gas flowing through the intermediate flow channel 22.

[0067] The upstream temperature sensor 45 and the intermediate temperature sensor 46 each transmit the acquired temperature information to the control unit 50. The control unit 50 is configured as a microprocessor including an MPU / CPU, an ASIC, a ROM, a RAM, etc., and controls the various operations of the compressor unit 10 by executing firmware, etc. pre-stored in the memory. The control unit 50 includes a first control unit 50a and a second control unit 50b as its functions. The first control unit 50a is a functional unit configured to control the first switching unit 59 with reference to the hydrogen gas temperature TS1 acquired by the intermediate temperature sensor 46. The second control unit 50b is a functional unit configured to control the recirculation valve 18b with reference to the hydrogen gas temperature TS2 acquired by the upstream temperature sensor 45.

[0068] Here, refer to Figure 4 The operation control performed by the controller 50 during the operation of the compressor unit 10 according to the present embodiment will be described.

[0069] The control unit 50 determines whether the compressor unit 10 is already being driven, and if it is determined that the compressor unit 10 is not being driven, determines whether there is a start-up instruction.

[0070] When a start command is issued for the compressor unit 10, the control unit 50 activates the crank mechanism 16, thereby driving the first compression stage 12 and the subsequent compression stage 14 (step ST1). The operation of the crank mechanism 16 causes the piston 212 to reciprocate within the cylinder 211 of the first compression stage 12 and the subsequent compression stage 14. As a result, hydrogen gas from the intake passage 21 is drawn into the first compression stage 12, and hydrogen gas from the intermediate passage 22 is drawn into the subsequent compression stage 14, compressing the hydrogen gas.

[0071] During the startup of the compressor unit 10, the temperature TS1 of the hydrogen gas flowing in the intermediate flow passage 22 (output from the first compression stage 12) is measured by the intermediate temperature sensor (first temperature sensor) 46. At this time, the control unit 50 refers to the temperature TS1 to determine whether the temperature TS1 is greater than a predetermined first temperature threshold T1 (step ST2). Here, the first temperature threshold T1 is a temperature greater than 0°C.

[0072] If the control unit 50 determines "yes" in step ST2 (temperature TS1 ≥ threshold value T1), the first control unit 50a controls the first switching unit CV1 to allow the hydrogen gas output from the first compression stage 12 to flow into the first flow path 22a (step ST3). As a result, the hydrogen gas output from the first compression stage 12 is cooled by the cooling unit 53 and sent to the subsequent compression stage 14 (first switching state).

[0073] On the other hand, if the control unit 50 determines "No" in step ST2 (temperature TS1 < threshold value T1), the first control unit 50a controls the first switching unit CV1 so that the hydrogen gas output from the first compression stage 12 flows to the second flow channel 22b without passing through the first flow channel 22a (step ST4). In other words, the first control unit 50a controls the first switching unit CV1 to stop the flow of hydrogen gas into the cooling unit 58. As a result, the hydrogen gas output from the first compression stage 12 flows to the subsequent compression stage 14 without passing through the cooling unit 58 (second switching state).

[0074] When the compressor unit 10 is driven, the temperature (suction temperature) TS2 of the hydrogen gas sucked into the first compression stage 12 is acquired by the upstream temperature sensor (second temperature sensor) 45. The control unit 50 starts the reflux control (step ST5) with reference to the suction temperature TS2. <T TH1 In this case, the second control unit 50b controls the return valve 18b to return part of the gas in the output flow path 24 to the intake flow path 21. As a result, when the first switching unit CV1 is in the second switching state, the hydrogen gas in the intake flow path 21 is heated so that the intake temperature TS2 falls within the predetermined temperature range (T TH1 ≤Temperature TS2≤T TH2 ).

[0075] More specifically, at temperature TS2 <T TH1 In the case of , the second control unit 50b controls the return valve 18b to return part of the gas in the output flow channel 24 to the suction flow channel 21, or to increase the amount of gas returned. In this way, the suction temperature TS2 falls within the above temperature range. In addition, when the temperature TS2>T TH2 In this case, the operation of returning a portion of the gas in the discharge flow path 24 to the suction flow path 21 is not performed, or the amount of the gas returned is reduced.

[0076] Here, the predetermined temperature range is set to a range higher than a reference temperature based on the liquefaction temperature of air and lower than 0° C. That is, the lower limit value T of the predetermined temperature range is set to TH1 and upper limit value T TH2 It is set in a range higher than the reference temperature and lower than 0°C.

[0077] When the second control unit 50b opens the return valve 18b as described above (step ST5 is executed), the hydrogen gas from the liquefied hydrogen storage tank 23 is not directly introduced into the first compression stage 12 but is combined with the hydrogen gas compressed by the subsequent compression stage 14, and the heated hydrogen gas is introduced into the first compression stage 12. Therefore, the first compression stage 12 can be prevented from being exposed to extremely low temperatures (less than T TH1The hydrogen gas of the temperature of the inhalation is in contact with the hydrogen gas of the temperature of the inhalation. TH1 The above-mentioned manner is adjusted, so it is possible to prevent the liquefaction of oxygen. TH2 Since the density of the hydrogen gas sucked into the first compression stage 12 is adjusted as follows, it is also possible to prevent the density of the hydrogen gas sucked into the first compression stage 12 from becoming too low.

[0078] The compressor unit 10 having the above-mentioned structure can operate even when the hydrogen gas in the intermediate flow path 22 rises to a positive temperature range or when the hydrogen gas in the suction flow path 21 is lower than the lower limit temperature T TH1 Specifically, when the hydrogen gas in the intermediate flow passage 22 of the compressor unit 10 rises to a positive temperature, the cooling unit 58 cools the hydrogen gas output from the first compression stage 12, preventing the excessively heated hydrogen gas from being delivered to the subsequent compression stage 14. In other words, the subsequent compression stage 14 can be protected. Furthermore, even during startup, the compressor unit 10 can be quickly started because the hydrogen gas cooled by the cooling unit 58 is delivered to the subsequent compression stage 14.

[0079] Furthermore, in the compressor unit 10, when the first switching unit CV1 is in the second switching state, the intake temperature TS2 of the hydrogen gas sucked into the first compression stage 12 is adjusted within the above-mentioned predetermined temperature range based on the hydrogen gas returned to the intake flow path 21 by the reflux portion SB1. Therefore, by setting the temperature of the hydrogen gas sucked into the first compression stage 12 to the above-mentioned lower limit temperature T TH1 As described above, it is possible to avoid liquefaction of oxygen used as the combustion-supporting gas.

[0080] Furthermore, in the compressor unit 10, the first compression stage 12 employs an oil-free design, thereby avoiding the risk of oil freezing. Furthermore, while the pressure in subsequent compression stages increases, hydrogen is more likely to leak. However, hydrogen leaking from the subsequent compression stage 14 is recovered into the suction flow passage 21 via the leaked gas discharge portion 29. Consequently, in the compressor unit 10, product loss (hydrogen loss) during compression can be reduced.

[0081] Furthermore, if the compressor unit 10 is used, efficient hydrogen recovery and supply can be achieved.

[0082] exist Figure 1 In the compressor unit 10 shown in FIG. 1 , a three-way valve 59a is used as an example of the first switching unit CV1 for switching the first flow channel 22a and the second flow channel 22b in the intermediate flow channel 22. However, the specific example of the first switching unit CV1 is not limited thereto. Figure 5As shown, the first switching unit CV1 may be configured to include a first regulating valve 59b provided in the first flow path 22a and a second regulating valve 59c provided in the second flow path 22b.

[0083] In addition, Figure 1 In the compressor unit 10 shown, the subsequent compression stage 14 uses a compression mechanism having one stage, but a compression mechanism having multiple stages may also be used. Figure 6 As shown, the subsequent compression section 14 may be formed by including a subsequent first compression section 14a and a subsequent second compression section 14b. In the case of adopting this structure, for example, Figure 7 As shown, the intermediate temperature sensor 46 may be disposed in the third flow passage 22c between the subsequent first compression stage 14a and the subsequent second compression stage 14b in the intermediate flow passage 22. In this case, the temperature of the hydrogen gas output from the first compression stage 12 can be estimated using the intermediate temperature sensor 46 disposed downstream of the subsequent first compression stage 14a.

[0084] In addition, Figure 1 In the compressor unit 10 shown in FIG. 1 , the cooling portion 58 is provided on the intermediate flow passage 22 between the first compression stage 12 and the subsequent compression stage 14 , but the location of the cooling portion 58 is not limited thereto. Figure 8 As shown, a branched flow channel (first flow channel 22a and second flow channel 22b) can be provided in the portion between the subsequent first compression section 14a and the subsequent second compression section 14b of the subsequent compression section 14 in the intermediate flow channel 22, and a cooling portion 58 can be provided in the first flow channel 22a. In addition, the first switching unit CV1 can also adopt Figure 5 The method shown.

[0085] [Second embodiment]

[0086] like Figure 9 As shown, the compressor unit 10 according to the second embodiment differs from the first embodiment in that it includes a preheater 71. The preheater 71 enables the hydrogen flowing in the suction flow path 21 (hydrogen sucked into the first compression stage 12) to perform heat exchange with the hydrogen output from the subsequent compression stage 14 to the output flow path 24. Figure 9 In the present invention, the same components as those in the first embodiment are denoted by the same reference numerals and descriptions of the overlapping components are omitted below.

[0087] like Figure 9As shown, the outlet flow channel 24 has branched flow channels (first flow channel 24a and second flow channel 24b) at a location upstream of the location where it connects to the return flow channel 18a. The preheater 71 is disposed between one of the flow channels (first flow channel 24a) and the intake flow channel 21. Thus, the preheater 71 can perform heat exchange between the hydrogen gas flowing in the first flow channel 24a of the outlet flow channel 24 and the hydrogen gas flowing in the intake flow channel 21.

[0088] A flow control unit FCV1 is provided at the branch point between the first flow channel 24a and the second flow channel 24b on the output flow channel 24. However, the flow control unit FCV1 can be provided in either the first flow channel 24a or the second flow channel 24b. In the present embodiment, as an example, the flow control unit FCV1 includes a three-way valve 72a. Therefore, in the present embodiment, the hydrogen gas output from the subsequent compression stage 14 can be caused to flow to either the first flow channel 24a or the second flow channel 24b, and the amount of hydrogen gas flowing to the first flow channel 24a can be adjusted while causing the hydrogen gas to flow to both the first flow channel 24a and the second flow channel 24b.

[0089] The compressor unit 10 according to this embodiment further includes a downstream temperature sensor (third temperature sensor) 48 disposed in the discharge flow passage 24 downstream of the preheater 71. The downstream temperature sensor 48 can obtain the temperature of the hydrogen gas flowing in the portion of the discharge flow passage 24 downstream of the preheater 71. The temperature information obtained by the downstream temperature sensor 48 is transmitted to the control unit 50.

[0090] In the compressor unit 10 , the control unit 50 includes a first control unit 50a and a second control unit 50b as its functions, and further includes a third control unit 50c . The third control unit 50c is a functional unit configured to control the flow control unit FCV1 with reference to the hydrogen gas temperature TS3 obtained by the downstream temperature sensor 48 .

[0091] Here, refer to Figure 10 The operation control performed by the controller 50 during the operation of the compressor unit 10 according to the present embodiment will be described. In the following description, a portion of the description overlapping with that of the first embodiment will be omitted.

[0092] In the steady-state operation state (temperature TS1 < threshold value T1), the control unit 50 controls the first switching unit CV1 to stop the flow of hydrogen gas into the cooling unit 58 (step ST4). The control steps up to this point are the same as those in the first embodiment.

[0093] The control portion 50 refers to the suction temperature TS2 acquired by the upstream temperature sensor 45 and starts the preheater control (step ST6). That is, at the temperature TS2 <T TH1In this case, the third control unit 50c controls the flow control unit FCV1 so that the hydrogen gas output from the subsequent compression stage 14 flows into the first flow path 24a and passes through the preheater 71 (step ST6). The control unit 50 then determines whether the temperature TS3 obtained by the downstream temperature sensor 48 while the hydrogen gas passes through the preheater 71 is greater than the temperature T TH3 (Step ST7). If the control unit 50 determines "Yes" in step ST7 (temperature TS3>T TH3 ), the third control unit 50c maintains the state of allowing hydrogen to flow into the preheater 71. Thus, heat exchange in the preheater 71 is continued. TH2 In this case, preheater control is not performed.

[0094] On the other hand, if the control unit 50 determines "No" in step ST7 (temperature TS3 ≤ T TH3 ), the flow rate regulating unit FCV1 is controlled so that the inflow of hydrogen gas to the preheater 71 is constant (step ST8), and then the reflux control is started (step ST5). That is, the second control unit 50b controls the reflux valve 18b so that part of the gas in the output flow channel 24 is returned to the intake flow channel 21. Thus, when the judgment result of step ST7 is "No", in addition to heating the hydrogen gas by the preheater 71, heating of the hydrogen gas using the reflux unit SB1 is also performed. As a result, the intake temperature TS2 is adjusted to the lower limit value T of the predetermined temperature range. TH1 above.

[0095] In the compressor unit 10 having the above-described structure, when the first switching unit CV1 is in the second switching state (when the compressor unit 10 is in a steady-state operation state), the heating of the hydrogen gas in the suction flow passage 21 by the preheater 71 is performed in priority over the heating by the reflux unit SB1. Moreover, in the compressor unit 10, in the event of insufficient heating, compensation control is performed by the heating by the reflux unit SB1. Thus, the compressor unit 10 involved in this embodiment can minimize the power loss caused by returning the hydrogen gas compressed in the subsequent compression section 14 to the suction flow passage 21. Thus, the temperature of the hydrogen gas sent to the subsequent compression section 14 can be managed within a constant range while suppressing a decrease in processing efficiency.

[0096] Furthermore, in the compressor unit 10, a downstream temperature sensor 48 is disposed downstream of the preheater 71 in the outlet flow path 24. By using the detected temperature TS3 obtained by the downstream temperature sensor 48 to manage the temperature of the hydrogen gas downstream of the preheater 71, the compressor unit 10 can suppress excessive temperature drops in the hydrogen gas supplied to the demand side. This can result in the elimination of the need for expensive low-temperature specifications for the piping supplying the demand side.

[0097] Furthermore, if the compressor unit 10 is used, efficient recovery and supply of hydrogen can be achieved.

[0098] In addition, Figure 9 In the compressor unit 10 shown in FIG. 1 , as an example, the output flow path 24 is branched into the first flow path 24a and the second flow path 24b and the preheater 71 is provided in the first flow path 24a. However, the arrangement of the preheater 71 is not limited to this. For example, the following may also be adopted: Figure 11 As shown, the intake flow channel 21 is branched into a first flow channel 21a and a second flow channel 21b, and a preheater 71 is provided between one of the branched flow channels (the first flow channel 21a) and the output flow channel 24. In this case, a flow control unit FCV1 capable of adjusting the amount of hydrogen gas flowing into the preheater 71 may be provided at, for example, the branch point between the first flow channel 21a and the second flow channel 21b in the intake flow channel 21.

[0099] In addition, Figure 9 In the compressor unit 10 shown, as an example, a configuration is adopted in which two compression stages are provided, namely, the first compression stage 12 and the subsequent compression stage 14. However, the configuration is not limited thereto. For example, one or more compression stages may be added between the subsequent compression stage 14 and the flow control unit FCV1. Figure 11 In the illustrated compressor unit 10 , one or more compression stages may be added between the subsequent compression stage 14 and the preheater 71 .

[0100] [Third embodiment]

[0101] like Figure 12 As shown, the compressor unit 10 according to the third embodiment differs from the second embodiment in that a preheater 71 capable of performing heat exchange between hydrogen gases is provided between the intermediate flow channel 22 and the suction flow channel 21. Figure 12 In the present invention, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and redundant descriptions are omitted below.

[0102] In the compressor unit 10, the intermediate flow passage 22 includes a first flow passage 22a and a second flow passage 22b, as well as a fourth flow passage 22d. The fourth flow passage 22d branches off from the first flow passage 22a and the second flow passage 22b in the intermediate flow passage 22. In the compressor unit 10 according to this embodiment, a preheater 71 is provided between the fourth flow passage 22d in the intermediate flow passage 22 and the suction flow passage 21.

[0103] The first switching unit CV1 includes a first regulating valve 59b disposed in the first flow passage 22a; a second regulating valve 59c disposed in the second flow passage 22b; and a third regulating valve 59d disposed in the fourth flow passage 22d. Therefore, in the compressor unit 10, hydrogen gas output from the first compression stage 12 selectively flows to the first flow passage 22a, the second flow passage 22b, and the fourth flow passage 22d based on the control of the first regulating valve 59b, the second regulating valve 59c, and the third regulating valve 59d. In this embodiment, regulating valves 59b, 59c, and 59d are disposed in the first flow passage 22a, the second flow passage 22b, and the fourth flow passage 22d, respectively. However, simple on / off valves that simply open and close may also be provided in each of these channels.

[0104] Although not shown in the figure, the first control unit 50a of the control unit 50 (see Figure 1 etc.) can respectively control the first regulating valve 59b, the second regulating valve 59c, and the third regulating valve 59d included in the first switching unit CV1.

[0105] In the compressor unit 10 according to the present embodiment, the downstream temperature sensor 48 is arranged on the downstream side of the preheater 71 and the cooling portion 58 in the intermediate flow passage 22 .

[0106] In the operation of the compressor unit 10 according to this embodiment, the control unit 50 performs the same control as in the second embodiment. Figure 10 The controls are the same as those described.

[0107] In the compressor unit 10 having the above-described configuration, when the first switching unit CV1 (first control valve 59a, second control valve 59b, and third control valve 59d) is in the second switching state, the hydrogen gas flowing through the intake passage 21 is heated by both the preheater 71 and the reflux unit SB1. Therefore, in the compressor unit 10, the power loss associated with returning the compressed hydrogen gas to the intake side of the first compression stage 12 can be minimized, compared to a case where the hydrogen gas in the intake passage 21 is heated solely by the reflux unit SB1. Furthermore, in the compressor unit 10, since the gas flowing through the fourth passage 22d is cooled by the preheater 71, the intake gas temperature of the subsequent compression stage 14 decreases. Consequently, the power of the subsequent compression stage also decreases. This allows the intake temperature TS2 of the hydrogen gas into the first compression stage 12 to be maintained within a constant range while suppressing a decrease in processing efficiency.

[0108] Furthermore, in the compressor train 10, a downstream temperature sensor 48 is disposed downstream of the preheater 71 in the intermediate flow passage 22. The temperature downstream of the preheater 71 is managed using the detected temperature TS3 obtained by the downstream temperature sensor 48. This prevents the temperature of the hydrogen gas drawn into the subsequent compression stage 14 from becoming excessively low in the compressor train 10.

[0109] Furthermore, if the compressor unit 10 is used, efficient recovery and supply of hydrogen can be achieved.

[0110] In addition, Figure 12 In the compressor unit 10 shown in FIG. 1 , as an example, a configuration is adopted in which a fourth flow channel 22d is provided in the intermediate flow channel 22, which is independent of the first flow channel 22a and the second flow channel 22b, and a preheater 71 is provided between the fourth flow channel 22d and the suction flow channel 21. However, the configuration of the preheater 71 is not limited to this. For example, a configuration may also be adopted in which: Figure 13 As shown, the intake flow channel 21 is branched into a first flow channel 21a and a second flow channel 21b, and a preheater 71 is provided between one of the branched flow channels (the first flow channel 21a) and the second flow channel 22b of the intermediate flow channel 22. In this case, a flow rate adjustment unit 72 capable of adjusting the amount of hydrogen gas flowing into the preheater 71 may be provided at, for example, the branch point between the first flow channel 21a and the second flow channel 21b in the intake flow channel 21.

[0111] In addition, Figure 12 The illustrated compressor unit 10 employs, as an example, a configuration comprising two compression stages: a first compression stage 12 and a subsequent compression stage 14. However, the configuration is not limited thereto. For example, one or more compression stages may be added between the subsequent compression stage 14 and the connection portion of the return flow passage 18a in the output flow passage 24.

[0112] [Fourth embodiment]

[0113] like Figure 14 As shown, the compressor unit 10 involved in the fourth embodiment is different from the first embodiment described above in that it is provided with a low-pressure gas discharge path 53 and an adjustment unit 41. The low-pressure gas discharge path 53 is a flow path that can discharge hydrogen to the intermediate section demand end D2. The adjustment unit 41 is a unit for adjusting the hydrogen processing capacity of the subsequent compression section 14. Figure 14 In the present invention, the same components as those in the first embodiment are denoted by the same reference numerals and descriptions of the overlapping components are omitted below.

[0114] Intermediate demand side D2 is a facility capable of handling hydrogen at a lower pressure than that requested by demand side D1. Intermediate demand side D2 may include, for example, engines, power generation equipment, boilers, and other equipment that utilizes gas as energy. In addition to these, it may also include equipment that utilizes gas at approximately atmospheric pressure, such as flame equipment and gas relief valves.

[0115] The low-pressure gas discharge path 53 is located in the intermediate flow channel 22 at the branch point P B Branch. Branch point P B As long as it is between the first compression stage 12 and the subsequent compression stage 14 , it may be provided at any position in the intermediate flow channel 22 including the first flow channel 22 a and the second flow channel 22 b .

[0116] Furthermore, a pressure sensor 47 is disposed in the intermediate flow channel 22 . The pressure sensor 47 acquires the pressure PS1 of the hydrogen gas in the intermediate flow channel 22 and transmits the acquired pressure information to the control unit 50 .

[0117] The compressor unit 10 is provided with a third switching unit CV3 for switching the flow state of hydrogen gas in the low-pressure gas discharge path 53. The third switching unit CV3 includes an on-off valve 56a and, in this embodiment, is provided in the low-pressure gas discharge path 53 as an example. When the first switching unit CV1 is in the second switching state, the third switching unit CV3 mutually adjusts the amount of hydrogen gas supplied to the subsequent compression stage 14 and the amount of hydrogen gas supplied to the low-pressure gas discharge path 53.

[0118] In addition, in this embodiment, as an example, the third switching unit CV3 including the on-off valve 56a is adopted, but the present invention is not limited thereto. For example, the third switching unit CV3 including a three-way valve or the like may be adopted.

[0119] Pressure sensor 49 is located downstream of third switching unit CV3 in low-pressure gas discharge path 53. Pressure sensor 49 detects the pressure PS2 of hydrogen gas flowing in low-pressure gas discharge path 53 toward intermediate stage demand end D2 and transmits this pressure information to control unit 50.

[0120] The adjustment unit 41 is at the branch point P B The adjustment unit 41 adjusts the gas processing capacity by a method other than adjusting the rotation speed of the crank mechanism 16. In this embodiment, as an example, the adjustment unit 41 is composed of a reflux unit (second reflux unit SB2) that adjusts the hydrogen processing capacity by adjusting the gas flow rate sent from the subsequent compression stage 14 to the demand end 26.

[0121] The second recirculation section SB2 includes a second recirculation passage 43a and a second recirculation valve 43b, which is arranged in the second recirculation passage 43a and has an adjustable opening. One end of the second recirculation passage 43a is connected to the output passage 24 upstream of the recirculation passage 18. The other end is connected to the intermediate passage 22. Therefore, a portion of the hydrogen gas output from the subsequent compression stage 14 is returned to the intermediate passage 22, i.e., the suction side of the subsequent compression stage 14. The second recirculation valve 43b adjusts the amount of recirculation in the second recirculation passage 43a.

[0122] The control unit 50 receives inputs regarding the respective hydrogen demand amounts from the demand end D1 and the intermediate section demand end D2. Furthermore, the control unit 50 includes, as its functions, a first control unit 50a and a second control unit 50b, as well as a fourth control unit 50d and a fifth control unit 50e. The fourth control unit 50d is configured to control the third switching unit CV3 based on the hydrogen demand amount input from the intermediate section demand end D2 or the amount of change in the hydrogen demand amount input from the demand end D1. The fifth control unit 50e is configured to control the second return valve 43b based on the hydrogen demand amount input from the intermediate section demand end D2 or the amount of change in the hydrogen demand amount input from the demand end D1.

[0123] Here, refer to Figure 15 The operation control performed by the controller 50 during the operation of the compressor unit 10 according to the present embodiment will be described. Note that, in the following description, a portion of the description that overlaps with that of the first embodiment will be omitted.

[0124] In the steady-state operation state (temperature TS1 < threshold value T1), the control unit 50 controls the first switching unit CV1 to stop the flow of hydrogen gas into the cooling unit 58 (step ST4). The control steps up to this point are the same as those in the first embodiment.

[0125] The control unit 50 starts the recirculation control (step ST5) while referring to the intake temperature TS2 acquired by the upstream temperature sensor 45. That is, at the temperature TS2 <T TH1 In this case, the first control unit 50a controls the return valve 18b so that a portion of the hydrogen gas output from the subsequent compression stage 14 is returned to the intake passage 21 (step ST5). As a result, the hydrogen gas in the intake passage 21 is heated so that the temperature of the hydrogen gas flowing in the intake passage 21 (intake temperature TS2) falls within the predetermined temperature range (T TH1 ≤Temperature TS2≤T TH2 ). In addition, at temperature TS2>T TH2 In this case, the operation of returning a portion of the gas in the discharge flow path 24 to the suction flow path 21 is not performed, or the amount of the gas returned is reduced.

[0126] Furthermore, in this embodiment, the control unit 50 controls the third switching unit CV3 in parallel with the execution of step ST5, so that the hydrogen flowing in the intermediate flow channel 22 is discharged to the intermediate stage demand end D2 through the low-pressure gas discharge path 53 (step ST11). Furthermore, in this embodiment, the control unit 50 controls the adjustment unit 41 (second return valve 43b) in parallel with the execution of steps ST5 and ST11, so that a portion of the hydrogen output from the subsequent compression stage 14 is returned to the intermediate flow channel 22 (step ST12). Furthermore, as described above, the control of the third switching unit CV3 and the adjustment unit 41 is executed based on the amount of hydrogen demanded from the intermediate stage demand end D2 or the amount of change in the amount of hydrogen demanded from the demand end D1.

[0127] In the compressor unit 10 having the above configuration, during steady-state operation (when the first switching element CV1 is in the second switching state), if the required amount of hydrogen gas (demand) at the demand end D1 is reduced, the hydrogen gas is discharged to the intermediate demand end D2. Thus, in the compressor unit 10, the pressure in the liquefied hydrogen storage tank 23 can be maintained constant by balancing the amount of boil-off gas (hydrogen gas) generated from the liquefied hydrogen storage tank 23 with the amount of hydrogen gas delivered by the first compression stage 12.

[0128] Furthermore, in the compressor unit 10, the hydrogen processing rate in the subsequent compression stage 14 is reduced based on the adjustment unit 41 (second reflux section SB2). This suppresses the compression ratio of the subsequent compression stage 14 in the compressor unit 10, reducing the hydrogen processing rate in the subsequent compression stage 14. This also reduces the power of the subsequent compression stage 14 in the compressor unit 10.

[0129] Furthermore, if the compressor unit 10 is used, efficient recovery and supply of hydrogen can be achieved.

[0130] exist Figure 14In the compressor unit 10 shown in FIG. 1 , the subsequent compression section 14 adopts a compression mechanism having one section, but the subsequent compression section 14 may also adopt a compression mechanism having multiple sections. Figure 16 As shown, the subsequent compression stage 14 may also be configured by including a subsequent first compression stage 14a and a subsequent second compression stage 14b. In this configuration, one end of the second return flow channel 43a may be connected to the third flow channel 22c between the subsequent first compression stage 14a and the subsequent second compression stage 14b in the intermediate flow channel 22. In this case, a portion of the hydrogen gas output from the subsequent first compression stage 14a is returned to the suction side of the subsequent first compression stage 14a.

[0131] In addition, when the subsequent compression section 14 has a subsequent first compression section 14a and a subsequent second compression section 14b, as shown in FIG. Figure 17 As shown, one end of the second return flow channel 43a can be connected to the output flow channel 24, and the other end can be connected to a portion upstream of the subsequent first compression stage 14a in the intermediate flow channel 22. In this case, a portion of the hydrogen gas output from the subsequent second compression stage 14b is returned to the suction side of the subsequent first compression stage 14a.

[0132] In addition, when the subsequent compression section 14 has a subsequent first compression section 14a and a subsequent second compression section 14b, as shown in FIG. Figure 18 As shown, a second reflux portion SB2 may be provided for each of the subsequent first compression stage 14a and the subsequent second compression stage 14b. In this case, a portion of the hydrogen gas output from the subsequent first compression stage 14a to the third flow passage 22c returns to the suction side of the subsequent first compression stage 14a, and a portion of the hydrogen gas output from the subsequent second compression stage 14b to the output flow passage 24 returns to the third flow passage 22c.

[0133] In addition, from Figures 16 to 18 In the compressor unit 10 shown in FIG. 1 , a configuration is adopted in which the low-pressure gas discharge path 53 branches from a portion upstream of the subsequent first compression stage 14a in the intermediate flow passage 22. However, the branch point P at which the low-pressure gas discharge path 53 branches is not specified. B The location is not limited to this. For example, Figure 19 As shown, the low-pressure gas discharge path 53 may also be connected to the branch point P on the third flow channel 22c between the subsequent first compression stage 14a and the subsequent second compression stage 14b in the intermediate flow channel 22. B In addition, Figure 19 In the compressor unit 10 shown in FIG. 1 , as an example, the branch point P in the third flow path 22c can be BThe intermediate cooling section 74 is provided at the upstream side of the first compression section 14a. Thus, the hydrogen gas heated by the compression in the subsequent first compression section 14a can be cooled and sent to the subsequent second compression section 14b. In this case, the adjustment unit 41 adjusts the two compression sections 14a and 14b of the subsequent compression section relative to the branch point P. B The hydrogen processing capacity of the compression section 14b located on the downstream side.

[0134] In addition, from Figures 16 to 19 In the compressor unit 10 shown in the figures, a leaked gas discharge portion 29 is provided for each of the subsequent first compression stage 14a and the subsequent second compression stage 14b included in the subsequent compression stage 14. However, in the compressor unit 10, the leaked gas discharge portion 29 may be provided for some of the multiple compression stages included in the subsequent compression stage 14.

[0135] [Fifth embodiment]

[0136] like Figure 20 As shown, in the compressor unit 10 involved in this embodiment, it is possible to adopt: by using the open-close type suction valve unloader 61 and the Figure 19 The adjustment unit 41 is constructed by the same second recirculation portion SB2 as shown.

[0137] like Figure 21 As shown, during the control of the adjustment unit 41, when the control unit 50 determines that the state (valve opening) of the second return valve 43b input to the control unit 50 is greater than the opening threshold b1 (step ST41: "Yes"), the load of the subsequent compression stage 14 is reduced (step ST42). The opening threshold b1 is a preset threshold. The state of the second return valve 43b exceeding the opening threshold b1 indicates a high reflux volume. In this case, the reduction in the load of the subsequent compression stage 14 is executed by controlling the intake valve unloader 61. For example, the load of the subsequent compression stage 14 is reduced from 100% to 50%.

[0138] If the control unit 50 determines that the opening of the second return valve 43b is less than the opening threshold value b2 (step ST43: "YES"), it controls the suction valve unloader 61 to increase the load of the subsequent compression stage 14 (for example, from 50% to 100%) (step ST44). This reduces power by reducing the load of the subsequent compression stage 14 when the return flow rate is excessive.

[0139] like Figure 22 As shown, the compressor unit 10 may include a stepless capacity adjustment device 64 b as the adjustment unit 41 provided in the subsequent compression stage 14 .

[0140] The stepless capacity adjustment device 64b comprises an intake valve unloader 61b, a drive device 62b, and a detector 63b for detecting the rotation of the crank mechanism. The intake valve unloader 61b is driven by a hydraulic or electric drive device 62b, enabling it to maintain or release the open position of the intake valve plate at a higher speed than the time required for the piston to reciprocate. Furthermore, the control unit performs computational processing to estimate the piston position based on a signal from the detector 63b, located in the crank mechanism.

[0141] In the cylinder portion of the subsequent compression stage 14, an intake valve, located between the intake passage and the compression chamber, includes a valve plate that opens and closes the gas passage, and a valve body that houses the valve plate. Similar to a check valve, this intake valve is configured so that when the upstream pressure is higher than the downstream pressure, the valve plate opens due to the pressure differential. However, when the downstream pressure is higher, gas does not flow.

[0142] When the intake valve unloader 61b is actuated, the intake valve plate remains open, rendering it unable to function as a check valve. Furthermore, when the unloader is not actuated and the piston is in the intake stroke, the pressure in the compression chamber is lower than that in the intake passage. Therefore, the intake valve is open, allowing gas to enter the compression chamber. When the piston is in the compression stroke, the pressure in the compression chamber is higher than that in the intake passage. Consequently, the intake valve is closed.

[0143] At the beginning of the compression stroke, the suction valve is maintained in an open state by the stepless capacity adjustment device 64b. In this case, a portion of the gas introduced into the compression chamber returns to the suction passage. The suction valve is released from the open state and becomes closed midway through the compression stroke. In this case, when it becomes closed, the gas remaining in the compression chamber is compressed and discharged. The closed state of the suction valve is released during the next piston suction stroke, after the drive unit is driven again and the piston's compression stroke begins. The opening and closing action of the suction valve is repeated in conjunction with the reciprocating motion of the piston as described above.

[0144] If the suction valve's release timing is accelerated, the delivery volume increases; if it is delayed, the delivery volume decreases. Therefore, the stepless capacity adjustment device 64b can achieve the same function as the second return valve. Furthermore, since the compressed gas volume is adjusted, the power reduction effect is significant.

[0145] [Other Modifications]

[0146] The embodiments disclosed this time should be interpreted in all respects as illustrative and non-restrictive. The present invention is not limited to the embodiments described above, and various changes and improvements can be made without departing from the spirit of the present invention.

[0147] For example, Figure 23 As shown, in the compressor unit 10, the reflux portion SB1 can be configured to return a portion of the hydrogen flowing in the third flow channel 22c to the suction flow channel 21. Thus, based on the reflux portion SB1, a portion of the hydrogen flowing between the two adjacent subsequent compression sections 14 (the subsequent first compression section 14a and the subsequent second compression section 14b) in the intermediate flow channel 22 can be returned to the suction flow channel 21. Even in this case, the first compression section 12 can be prevented from coming into contact with the extremely low temperature hydrogen. In the compressor unit 10, the number of subsequent compression sections 14 can be more than 3, and the reflux portion SB1 can be provided on any intermediate flow channel between the subsequent compression sections 14.

[0148] like Figure 24 As shown, in the compressor unit 10, a fourth flow channel 22d that branches independently from the third flow channel 22c can be provided in the intermediate flow channel 22. In this case, the preheater 71 can be arranged so that the hydrogen flowing in the suction flow channel 21 (hydrogen sucked into the first compression stage 12) and the hydrogen flowing in the fourth flow channel 22d can exchange heat. Figure 23 The number of subsequent compression stages 14 may be more than 3, and a preheater 71 may be provided on any intermediate flow passage between the subsequent compression stages 14 .

[0149] [Summarize]

[0150] A reciprocating compressor unit according to one embodiment of the present invention recovers boil-off gas (hydrogen) from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand source, including at least one of an engine, a power generation device, and a boiler. The compressor unit includes multiple compression stages, a crank mechanism, a cooling unit, a first switching unit, a reflux unit, a first temperature sensor, a second temperature sensor, and a control unit.

[0151] The multiple compression sections compress the hydrogen gas sucked in from the intake flow channel. The crank mechanism drives the multiple compression sections. The cooling section is provided in an intermediate flow channel between the multiple compression sections. The first switching unit switches the inflow state of the hydrogen gas to the cooling section. The reflux section includes a reflux flow channel and a reflux valve. The reflux flow channel returns the hydrogen gas output to the output flow channel on the output side of the multiple compression sections, or the hydrogen gas flowing in the intermediate flow channel, to the intake flow channel. The reflux valve adjusts the reflux amount in the reflux flow channel. The first temperature sensor is arranged in the intermediate flow channel. The second temperature sensor is arranged between the connection part of the reflux flow channel in the intake flow channel and the first compression section of the first section among the multiple compression sections. The control section controls each of the first switching unit and the reflux valve.

[0152] In the compressor unit according to the present technical solution, the first compression stage and each of the plurality of compression stages subsequent to the first compression stage include a cylinder, a piston, a piston rod, and a rod seal. The piston rod connects the piston to the crank mechanism. The rod seal seals the piston rod and the cylinder.

[0153] The first compression stage is an air-cooled and oil-free compression stage.

[0154] The control unit performs the following control on the first switching unit and the return valve.

[0155] During startup, when temperature TS1 acquired by the first temperature sensor is equal to or greater than a predetermined first temperature threshold value T1 greater than 0° C., the control unit controls the first switching means to enter a first switching state. The first switching state is a state in which hydrogen gas output from the first compression stage flows to the cooling unit and is cooled by the cooling unit.

[0156] The control unit controls the first switching means to enter a second switching state when the temperature TS1 obtained by the first temperature sensor is less than the first temperature threshold T1. The second switching state is a state in which the hydrogen gas is sent to the compression stage downstream of the location where the cooling unit is provided, without passing through the cooling unit.

[0157] When the first switching unit is in the second switching state, the control unit controls the return valve with reference to the suction temperature TS2 acquired by the second temperature sensor so that the suction temperature TS2 falls within a predetermined temperature range.

[0158] In the compressor unit according to the present invention, the predetermined temperature range is set to a range higher than a reference temperature based on the liquefaction temperature of air and lower than 0°C.

[0159] In the above technical solution, the compressor unit can be protected in a low temperature environment. More specifically, during startup and when the hydrogen in the piping on the side of the liquefied hydrogen storage tank rises to a positive temperature zone, the hydrogen located upstream relative to the cooling unit in the intermediate flow channel can be cooled by the cooling unit, so as to prevent the overheated hydrogen from being transported to the compression section (subsequent compression section) on the downstream side. That is, in the compressor unit, the subsequent compression section can be protected. In addition, in the compressor unit, even during startup and when the first switching unit is in the first switching state, since the hydrogen in the predetermined temperature range is transported to the compression section on the downstream side, the startup work of the compressor unit can be carried out quickly.

[0160] Furthermore, in the compressor unit according to the above technical solution, when the first switching unit is in the second switching state, the hydrogen gas returned to the intake flow path via the reflux portion can be used to adjust the intake temperature TS2 of the hydrogen gas drawn into the first compression stage. Therefore, in the compressor unit, by setting the temperature range of the hydrogen gas drawn into the first compression stage to be higher than a reference temperature based on the liquefaction temperature of air, liquefaction of oxygen gas used as an auxiliary combustion gas can be avoided.

[0161] Furthermore, in the compressor unit according to the above technical solution, since the first compression stage is of the oil-free type, the risk of oil freezing can be avoided.

[0162] The compressor unit according to the above technical solution may further include a preheater, a third temperature sensor, and a flow control unit. The preheater is capable of performing heat exchange between the hydrogen gas before being drawn into the first compression stage and the hydrogen gas output to the output flow channel or the hydrogen gas flowing in the intermediate flow channel. The third temperature sensor is disposed downstream of the preheater in the output flow channel. The flow control unit is capable of adjusting the flow of hydrogen gas into the preheater.

[0163] The control unit may perform the following control on the flow rate adjustment unit and the return valve when the first switching unit is in the second switching state.

[0164] The control unit can increase the inflow of hydrogen into the preheater in the second switching state so that the heating of the hydrogen in the intake flow path by the preheater is performed preferentially over the heating by the reflux unit, and control the flow adjustment unit so that the temperature TS3 on the downstream side of the preheater obtained by the third temperature sensor does not fall below a threshold value.

[0165] In the second switching state, when the suction temperature TS2 is lower than or equal to a set temperature, the control unit may control the flow rate adjustment unit and the return valve so that the suction temperature TS2 falls within a predetermined temperature range.

[0166] In the compressor unit according to the above-described technical solution, in the second switching state, heating to the suction temperature TS2 by the preheater is prioritized over heating by the reflux unit. If heating is insufficient, the preheater is used to compensate. This minimizes the power loss associated with returning the compressed hydrogen gas to the suction side of the first compression stage, and allows the hydrogen gas suction temperature to be maintained within a constant range in subsequent compression stages while suppressing a decrease in processing efficiency.

[0167] In the compressor unit, a third temperature sensor is disposed downstream of the preheater, and the temperature of the hydrogen gas downstream of the preheater is managed using the temperature TS3 detected by the third temperature sensor.

[0168] The compressor unit according to the above technical solution may further include a preheater and a third temperature sensor. The preheater is capable of exchanging heat between the hydrogen gas before being drawn into the first compression stage and the hydrogen gas flowing in the intermediate flow channel between the first compression stage and the subsequent compression stage. The third temperature sensor is disposed downstream of the preheater in the intermediate flow channel.

[0169] In addition, in the compressor group involved in the above technical solution, the first switching unit can be constructed as follows: it can switch the hydrogen output from the first compression section to any one of a hydrogen flow state to the cooling part, a hydrogen flow state directly to the subsequent compression section, and a hydrogen flow state to the preheater.

[0170] Furthermore, in the compressor unit according to the above-mentioned technical solution, the control unit may perform the following control on the return valve and the first switching unit when the first switching unit is in the second switching state.

[0171] The control unit may control the reflux valve and the first switching unit in the second switching state so that the hydrogen gas in the intake flow passage is within the predetermined temperature range by heating the hydrogen gas in the intake flow passage by the reflux unit and heating the hydrogen gas by the preheater.

[0172] In the second switching state, when the temperature TS3 on the downstream side of the preheater obtained by the third temperature sensor is lower than a threshold, the control unit may control the first switching unit so that the flow of hydrogen into the preheater does not further increase.

[0173] In the compressor unit according to the above technical solution, when the first switching unit is in the second switching state, in addition to heating the hydrogen gas in the intake passage by the reflux unit, the preheater also performs heating. Therefore, compared to heating by the reflux unit alone, the combined use of the preheater minimizes the power loss associated with returning the compressed hydrogen to the intake side of the subsequent compression stage. Consequently, in the above compressor unit, the intake temperature of the hydrogen gas into the subsequent compression stage can be managed within a constant range while suppressing a decrease in processing efficiency.

[0174] Furthermore, in the compressor train, a third temperature sensor is disposed downstream of the preheater, and the temperature downstream of the preheater is managed using the temperature TS3 detected by the third temperature sensor.

[0175] The compressor unit according to the above technical solution may further include a low-pressure gas discharge path, a third switching unit, and an adjustment unit. The low-pressure gas discharge path branches from a branch point provided in the intermediate flow channel and is capable of discharging hydrogen to an intermediate section demand end, which is capable of processing hydrogen at a lower pressure than that required by the demand end. The third switching unit is provided in the low-pressure gas discharge path or the branch point. The adjustment unit adjusts the hydrogen processing capacity of the subsequent compression stage.

[0176] In the compressor unit involved in the above technical solution, the control unit can control the third switching unit in parallel with the control of the return valve when the first switching unit is in the second switching state, so that hydrogen is discharged to the low-pressure gas discharge path according to the demand at the demand end of the intermediate section or the change in the demand at the demand end, and control the adjustment unit to adjust the processing capacity of the subsequent compression section.

[0177] In the compressor unit according to the above technical solution, when the required amount (demanded amount) on the demand side is reduced, the amount of boil-off gas (hydrogen) generated from the liquefied hydrogen storage tank and the amount of hydrogen delivered from the first compression stage can be balanced by discharging hydrogen to the intermediate stage demand side. As a result, the pressure in the liquefied hydrogen storage tank can be maintained constant in the compressor unit.

[0178] Furthermore, in the above-mentioned compressor train, the compression ratio of the subsequent compression stage can be suppressed by reducing the hydrogen processing capacity of the subsequent compression stage through the adjustment unit. Thus, in the above-mentioned compressor train, the hydrogen processing capacity of the subsequent compression stage can be reduced, and the power of the subsequent compression stage can be reduced.

[0179] In the compressor unit involved in the above technical solution, the subsequent compression section may include more than two compression sections. In addition, the compressor unit involved in the above technical solution may further include: a low-pressure gas discharge path, a third switching unit, and an adjustment unit. The low-pressure gas discharge path branches off from a branch point provided in the intermediate flow channel, and is capable of discharging hydrogen to the intermediate section demand end, and the intermediate section demand end is capable of processing hydrogen with a lower pressure than the hydrogen required by the demand end. The third switching unit is provided in the low-pressure gas discharge path or the branch point. The adjustment unit adjusts the hydrogen processing capacity of the compression section located on the downstream side relative to the branch point among the two or more compression sections included in the subsequent compression section.

[0180] In the compressor unit involved in the above technical solution, the control unit can control the third switching unit in parallel with the control of the return valve when the first switching unit is in the second switching state, so that hydrogen is discharged to the low-pressure gas discharge path according to the demand at the demand end of the intermediate section or the change in the demand at the demand end, and control the adjustment unit to adjust the processing capacity of the compression section located on the downstream side in the subsequent compression section.

[0181] In the compressor unit according to the above technical solution, when the required amount (demanded amount) on the demand side is reduced, the amount of boil-off gas (hydrogen) generated from the liquefied hydrogen storage tank and the amount of hydrogen delivered from the first compression stage can be balanced by discharging hydrogen to the intermediate stage demand side. As a result, the pressure in the liquefied hydrogen storage tank can be maintained constant in the compressor unit.

[0182] Furthermore, in the compressor train, the amount of hydrogen flowing to the downstream compression stage can be reduced by the adjustment unit. Thus, in the compressor train, by suppressing the compression ratio of the downstream compression stage among subsequent compression stages, the amount of hydrogen processed by that compression stage can be reduced, thereby reducing the power of the compression stage.

[0183] In the compressor unit according to the above technical solution, the adjustment unit may include a second reflux portion. The second reflux portion includes: a second reflux flow passage located upstream of the reflux flow passage for returning hydrogen gas to the suction side of the subsequent compression stage; and a second reflux valve for adjusting the reflux amount in the second reflux flow passage.

[0184] In the compressor unit involved in the above technical solution, the control unit can control the second return valve when the first switching unit is in the second switching state, so that a flow rate equivalent to the demand amount at the demand end of the intermediate section or the change in the demand amount at the demand end is returned to the suction side of the subsequent compression section through the second return unit.

[0185] In the compressor unit according to the above technical solution, when the required amount (demanded amount) on the demand side is reduced, the amount of hydrogen gas returned to the suction side of the subsequent compression stage can be reduced through the second reflux portion. Thus, in the above compressor unit, the amount of boil-off gas (hydrogen gas) generated from the liquefied hydrogen storage tank and the amount of hydrogen gas delivered from the first compression stage can be balanced, and the amount of hydrogen gas processed by the subsequent compression stage can be reduced, thereby reducing the power of the subsequent compression stage.

[0186] In the compressor unit according to the above technical solution, the adjustment unit may further include: an on-off type suction valve unloader installed in the cylinder portion of the subsequent compression stage.

[0187] In the compressor unit according to the above technical solution, the control unit may perform the following control on the suction valve unloader when the first switching unit is in the second switching state.

[0188] In the second switching state, when the opening of the second return valve is greater than a preset opening threshold b1, the control unit may control the suction valve unloader to reduce the load of the subsequent compression stage.

[0189] In the second switching state, when the opening degree of the second return valve is less than an opening degree threshold b2, the control unit may control the suction valve unloader to increase the load of the subsequent compression stage.

[0190] In the compressor unit according to the above technical solution, since the second reflux section is provided, even if the demand at the high-pressure demand end (D1) is reduced, the compressed hydrogen is returned to the suction side of the subsequent compression stage via the second reflux section. Thus, in the compressor unit according to the above technical solution, the suction pressure of the subsequent compression stage can be maintained substantially constant. Therefore, in the compressor unit according to the above technical solution, the pressure balance of each stage in the subsequent compression stage is always constant, thereby achieving high compressor reliability.

[0191] In the compressor unit according to the above technical solution, the adjustment unit may include a suction valve unloader, a drive device, and a stepless capacity adjustment device. The suction valve unloader is mounted on the cylinder portion of the subsequent compression stage. The drive device is hydraulic or electric and opens and closes the suction valve unloader. The stepless capacity adjustment device includes a control device that controls the period of operation of the suction valve unloader in conjunction with the rotational motion of the crankshaft.

[0192] In the compressor unit involved in the above technical solution, the control unit can control the capacity adjustment device in a manner that returns the inhaled hydrogen from the inside of the cylinder to the suction side according to a flow rate equivalent to the demand amount at the demand end of the intermediate section or the change in the demand amount at the demand end when the first switching unit is in the second switching state, thereby adjusting the processing capacity of the subsequent compression section.

[0193] In the compressor unit according to the above technical solution, in the second switching state, the operating period and duration of the suction valve unloader are controlled to return a portion of the hydrogen gas inside the cylinder to the suction side. Therefore, in the above compressor unit, the hydrogen gas processing capacity of the subsequent compression stage can be reduced, achieving further power reduction.

[0194] In the compressor unit according to the above technical solution, at least a portion of the subsequent compression stage includes a leakage gas discharge portion for returning leakage gas from the rod seal to the suction flow passage.

[0195] In the aforementioned compressor unit, the pressure increases in subsequent compression stages, making hydrogen more likely to leak. However, in the compressor unit according to the above technical solution, hydrogen leaked in the subsequent compression stages is recovered to the suction flow path via the leaked gas discharge unit. Therefore, the compressor unit according to the above technical solution can reduce the loss of product gas (hydrogen) during compression.

[0196] As described above, the compressor unit according to each of the above-mentioned aspects can appropriately protect its constituent devices from the wide temperature variation of the boil-off gas of liquefied hydrogen.

Claims

1. A compressor unit, characterized in that The following reciprocating compressor units: The compressor unit recovers boil-off gas, i.e., hydrogen, from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand side including at least one of an engine, a power generation device, and a boiler, and includes: Multiple compression sections compress the hydrogen gas sucked in from the suction flow channel; a crank mechanism for driving the plurality of compression sections; a cooling portion disposed in an intermediate flow channel between the plurality of compression sections; a first switching unit for switching a flow state of hydrogen gas into the cooling unit; a reflux portion comprising a reflux passage and a reflux valve, wherein the reflux passage returns the hydrogen gas output to the output passage on the output side of the plurality of compression stages or the hydrogen gas flowing in the intermediate passage to the suction passage, and the reflux valve adjusts the reflux amount in the reflux passage; A first temperature sensor is disposed in the intermediate flow channel; a second temperature sensor disposed between a connection portion of the return flow passage in the intake flow passage and a first compression stage that is the first stage among the plurality of compression stages; and A control unit controls each of the first switching unit and the return valve; wherein, The first compression stage and each of the plurality of compression stages other than the first compression stage include: Cylinder; piston; a piston rod connecting the piston to the crank mechanism; and A rod seal seals the piston rod and the cylinder; wherein, The first compression section is an air-cooled and oil-free compression section. The control unit performs the following control: During startup, when the temperature TS1 acquired by the first temperature sensor is greater than or equal to a predetermined first temperature threshold T1 greater than 0° C., controlling the first switching unit to enter a first switching state in which the hydrogen gas output from the first compression stage flows to the cooling unit and is cooled by the cooling unit; When the temperature TS1 acquired by the first temperature sensor is lower than the first temperature threshold T1, the first switching unit is controlled to be in a second switching state in which the hydrogen gas is sent to the compression stage downstream of the location where the cooling unit is provided, without passing through the cooling unit; and When the first switching unit is in the second switching state, the return valve is controlled with reference to the suction temperature TS2 acquired by the second temperature sensor so that the suction temperature TS2 falls within a predetermined temperature range, wherein: The predetermined temperature range is set to a range higher than a reference temperature based on the liquefaction temperature of air and lower than 0°C.

2. The compressor unit according to claim 1, characterized in that Also includes: a preheater for enabling heat exchange between the hydrogen gas drawn into the first compression stage and the hydrogen gas output to the output flow channel or the hydrogen gas flowing in the intermediate flow channel; a third temperature sensor disposed downstream of the preheater in the output flow channel; and A flow regulating unit is capable of regulating the flow state of hydrogen gas into the preheater; wherein, When the first switching unit is in the second switching state, the control unit performs the following control: The flow rate of hydrogen gas flowing into the preheater is increased so that the preheater gives priority to heating the hydrogen gas in the intake flow path over heating by the reflux unit, and the flow rate regulating unit is controlled so that the temperature TS3 on the downstream side of the preheater obtained by the third temperature sensor does not fall below a threshold value; and When the suction temperature TS2 is lower than the set temperature, the flow rate adjustment unit and the return valve are controlled so that the suction temperature TS2 falls within a predetermined temperature range.

3. The compressor unit according to claim 1, characterized in that Also includes: a preheater for enabling heat exchange between the hydrogen gas drawn into the first compression stage and the hydrogen gas flowing between the first compression stage and the subsequent compression stage in the intermediate flow channel; as well as, The third temperature sensor is arranged downstream of the preheater in the intermediate flow channel; wherein, The first switching unit is capable of switching the hydrogen gas output from the first compression stage to any one of a hydrogen gas flow state to the cooling portion, a hydrogen gas flow state directly to the subsequent compression stage, and a hydrogen gas flow state to the preheater. When the first switching unit is in the second switching state, the control unit performs the following control: controlling the reflux valve and the first switching unit so that the hydrogen gas in the intake flow path is brought within the predetermined temperature range by heating the hydrogen gas in the intake flow path by the reflux unit and heating the hydrogen gas in the preheater; and When the temperature TS3 on the downstream side of the preheater acquired by the third temperature sensor is lower than a threshold value, the first switching unit is controlled so that the flow of hydrogen into the preheater does not further increase.

4. The compressor unit according to claim 1, characterized in that Also includes: a low-pressure gas discharge path branching from a branch point provided in the intermediate flow channel and capable of discharging hydrogen to an intermediate section demand end, wherein the intermediate section demand end is capable of processing hydrogen at a lower pressure than the hydrogen required by the demand end; A third switching unit is provided in the low-pressure gas exhaust path or the branch point; and An adjustment unit adjusts the hydrogen processing capacity of the subsequent compression section; wherein, When the first switching unit is in the second switching state, the control unit controls the third switching unit in parallel with the control of the reflux valve, so that hydrogen is discharged to the low-pressure gas discharge path according to the demand at the demand end of the intermediate section or the change in the demand at the demand end, and controls the adjustment unit to adjust the processing capacity of the subsequent compression section.

5. The compressor unit according to claim 1, characterized in that The subsequent compression stage includes more than two compression stages, The compressor unit further comprises: a low-pressure gas discharge path branching from a branch point provided in the intermediate flow channel and capable of discharging hydrogen to an intermediate section demand end, wherein the intermediate section demand end is capable of processing hydrogen at a lower pressure than the hydrogen required by the demand end; A third switching unit is provided in the low-pressure gas exhaust path or the branch point; and An adjustment unit adjusts the hydrogen processing capacity of the compression section located downstream of the branch point among the two or more compression sections included in the subsequent compression section; wherein, When the first switching unit is in the second switching state, the control unit controls the third switching unit in parallel with the control of the reflux valve, so that hydrogen is discharged to the low-pressure gas discharge path according to the demand at the demand end of the intermediate section or the change in the demand at the demand end, and controls the adjustment unit to adjust the processing capacity of the compression section located on the downstream side in the subsequent compression section.

6. The compressor unit according to claim 4 or 5, characterized in that: The adjustment unit includes a second reflux unit, and the second reflux unit includes: a second reflux flow passage located upstream of the reflux flow passage and returning hydrogen to the suction side of the subsequent compression stage; and The second reflux valve adjusts the reflux amount in the second reflux flow passage, wherein: When the first switching unit is in the second switching state, the control unit controls the second return valve so that a flow rate equivalent to the demand amount at the demand end of the intermediate section or the change in the demand amount at the demand end is returned to the suction side of the subsequent compression section through the second return unit.

7. The compressor unit according to claim 6, characterized in that The adjustment unit further comprises: An open-close type suction valve unloader is installed on the cylinder portion of the subsequent compression section, wherein: When the first switching unit is in the second switching state, the control unit performs the following control: When the opening of the second return valve is greater than a preset opening threshold b1, the suction valve unloader is controlled to reduce the load of the subsequent compression section; and When the opening degree of the second return valve is less than the opening degree threshold b2, the suction valve unloader is controlled to increase the load of the subsequent compression stage.

8. The compressor unit according to claim 4 or 5, characterized in that: The adjustment unit comprises: A suction valve unloader is installed on the cylinder portion of the subsequent compression section; A hydraulic or electric drive device to open and close the suction valve unloader; and The stepless capacity adjustment device has a control device for controlling the operation period of the suction valve unloader in conjunction with the rotation of the crankshaft. When the first switching unit is in the second switching state, the control unit controls the capacity adjustment device in such a manner that the inhaled hydrogen gas is returned from the inside of the cylinder to the suction side according to a flow rate corresponding to the demand amount at the demand end of the intermediate section or the change in the demand amount at the demand end, thereby adjusting the processing capacity of the subsequent compression section.

9. The compressor unit according to claim 1, characterized in that At least a portion of the subsequent compression section has: The leaked gas discharge portion returns the leaked gas from the rod seal to the suction flow path.

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