Compressor Unit

Abstract

To provide a reciprocating type compressor unit that can appropriately protect its components from a wide range of temperature changes of boil-off gas of liquefied hydrogen.SOLUTION: In a compressor unit 10, demander switching means CV1 is controlled so that hydrogen gas discharged from a subsequent compression stage 14 is discharged to a low-pressure demander D2 from a low-pressure gas discharge passage 53 when a temperature TS1 acquired by an intermediate temperature sensor 46 is equal to or higher than a temperature threshold T1 higher than 0°C at the time of startup. The demander switching means CV1 is controlled so that the hydrogen gas flows to a high-pressure demander D1 when the detected temperature TS1 is lower than the temperature threshold T1. A control unit 50 controls a spill-back valve 18b so that a detected temperature TS2 is within a predetermined temperature range. The temperature range is set in a range higher than a reference temperature based on a liquefaction temperature of air, and lower than 0°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-172870 [Patent Document 2] Patent No. 7085079 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-65795 [Patent Document 4] Japanese Patent Application Publication No. 2019-27590 [Patent Document 5] Japanese Patent Application Publication No. 4-12178 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, Patent Document 1 points out the following problem: "In recent years, hydrogen has been attracting attention as a new energy source. When using hydrogen as an energy source, it is expected that it will be stored and transported in a liquefied state, just like natural gas. However, hydrogen has the characteristic that its liquefaction temperature is lower than that of air. Therefore, if equipment such as reciprocating compressors designed for natural gas, etc., is applied to hydrogen as is, there is a possibility that problems will arise due to the extremely low temperature of liquid hydrogen. For example, liquefied air will be generated around the equipment to which liquid hydrogen is supplied."

[0005] In response to this, Patent Document 1 explains that "In this reciprocating compressor, the compression unit that compresses the gas is housed in a container. This container forms a vacuum region around the compression unit. This means that the compression unit is thermally insulated from the external region by the vacuum region. In other words, even when cryogenic gas is provided to the compression unit, the region around the reciprocating compressor is not excessively cooled. Therefore, the generation of liquefied air can be suppressed." However, in general, it is very difficult to achieve high-performance insulation for moving machines that vibrate during operation or for equipment (such as reciprocating compressors) that require regular maintenance through an inspection opening.

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

[0007] On the other hand, Patent Document 5 also points out the following problem: "Conventionally, when BOG (boil-off gas) evaporated in an LNG low-temperature storage tank is compressed in a low-temperature gas multi-stage compressor and supplied to a plant, the temperature of the BOG is prone to fluctuate over a wide range, from minus 100 degrees to room temperature. In particular, immediately after the start-up of the multi-stage compressor, the suction side temperature rises to near room temperature, and if this is compressed as is, the discharge temperature will exceed the allowable temperature, making operation impossible."

[0008] Since liquefied hydrogen has a lower boiling point than LNG, the problem disclosed in Patent Document 5 can become even more serious. Reciprocating compressors that handle boil-off gas from liquefied hydrogen need to be able to handle a wide temperature range, from cryogenic temperatures to room temperature.

[0009] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to appropriately protect the components of a reciprocating compressor unit that handles boil-off gas of liquefied hydrogen from wide temperature changes of the boil-off gas. [Means for solving the problem]

[0010] A compressor unit according to one aspect of the present invention is a reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a high-pressure demand destination (D1) including at least one of an engine, a power generation facility, and a boiler. The compressor unit according to this aspect includes a plurality of compression stages, a crank mechanism, a spillback unit (SB1), a low-pressure gas discharge path, a demand destination switching means (CV1), a check valve, a first temperature sensor, a second temperature sensor, and a control unit.

[0011] The multiple compression stages compress hydrogen gas drawn in through the intake passage. The crank mechanism drives the multiple compression stages. The spillback unit (SB1) includes a spillback passage that returns hydrogen gas discharged into the discharge passage on the discharge side of the multiple compression stages or hydrogen gas flowing through an intermediate passage between the multiple compression stages to the intake passage, and a spillback valve that adjusts the amount of spillback in the spillback passage. The low-pressure gas discharge passage branches from a branch point provided in the intermediate passage or the discharge passage and is capable of discharging hydrogen gas to a low-pressure demand destination (D2) that can process hydrogen gas at a pressure lower than that required by the high-pressure demand destination (D1). The demand destination switching means (CV1) is provided in the low-pressure gas discharge passage or the branch point. The check valve is located downstream of the branch point. The first temperature sensor is located upstream of the branch point in the intermediate passage or the discharge passage. The second temperature sensor is disposed in the suction passage between a connection portion of the spillback passage and a first compression stage that is the forefront of the plurality of compression stages. The control unit controls the demand destination switching means (CV1) and the spillback valve.

[0012] In the compressor unit according to this aspect, when the temperature TS1 acquired by the first temperature sensor is equal to or greater than a predetermined first temperature threshold T1 greater than 0°C during startup, the control unit controls the destination switching means (CV1) to enter a first switching state in which hydrogen gas is circulated through the low-pressure gas discharge path. Furthermore, when the temperature TS1 acquired by the first temperature sensor becomes less than the first temperature threshold T1, the control unit controls the destination switching means (CV1) to enter a second switching state in which hydrogen gas is sent to the discharge path toward the high-pressure destination (D1). Furthermore, when the destination switching means (CV1) is in the second switching state, the control unit references a suction temperature TS2 acquired by the second temperature sensor and controls the spillback valve so that the suction temperature TS2 is within a predetermined temperature range.

[0013] 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.

[0014] In the above embodiment, the compressor unit can be protected in an environment where the BOG (hydrogen gas) is at a low temperature, and can also be protected during startup when the BOG (hydrogen gas) is at a normal temperature.

[0015] In a reciprocating compressor, BOG is discharged from the compressor at a pressure corresponding to the pressure of the demand destination. Under this premise, in the above embodiment, even if the hydrogen gas in the piping on the liquid hydrogen storage tank side has risen to a positive temperature range (room temperature) at startup, the control unit switches the demand destination switching means (CV1) to the first switching state so that the hydrogen gas discharged from the compression stage is sent to the low-pressure demand destination (D2). Therefore, by discharging hydrogen gas to a low-pressure demand destination that processes hydrogen gas at a relatively low pressure, the compression ratio in the compression stage can be kept low, preventing an excessive temperature rise in the hydrogen gas due to compression and pressure increase in the compression stage. In other words, the compression stage can be protected. Furthermore, even if the hydrogen gas in the piping is at room temperature at the time of unit startup, discharging hydrogen gas from the compression stage to the low-pressure demand destination as described above allows the compressor unit to be quickly started up.

[0016] On the other hand, in the above aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit controls the spillback valve so that the suction temperature TS2 falls within the predetermined temperature range, and the hydrogen gas returned to the suction flow path by the spillback unit can keep the suction temperature TS2 within the predetermined temperature range. In the above aspect, the predetermined temperature range is set to a range higher than a reference temperature based on the liquefaction temperature of air, so that liquefaction of oxygen, a combustion-supporting gas, can be prevented from occurring on the outer surface of the suction unit of the first compression stage or around a device to which hydrogen gas is supplied.

[0017] In the compressor unit according to the above aspect, the check valve may be provided in the discharge flow path, and the branch point may be provided in the discharge flow path at a position upstream of the check valve.

[0018] In the above embodiment, a specific configuration is adopted in which a check valve is provided in the discharge flow path and a branch point is provided at a position upstream of the check valve in the discharge flow path, but the control unit switches the demand destination switching means (CV1) between the first switching state and the second switching state based on the first temperature TS1, and when the demand destination switching means (CV1) is in the second switching state, controls the spillback valve based on the suction temperature TS2, so the same effect as in the above embodiment can be obtained.

[0019] In addition, in the above-described aspect, a check valve is provided in the discharge flow path, which prevents backflow of hydrogen gas from the discharge flow path to the compression stage, thereby more appropriately protecting the compressor.

[0020] The compressor unit according to the above aspect may further include a preheater, a third temperature sensor, and a flow rate adjustment device (FCV1). The preheater may be capable of exchanging heat between hydrogen gas before being drawn into the first compression stage and hydrogen gas after being discharged into the discharge flow path. The third temperature sensor may be disposed downstream of the preheater in the discharge flow path. The flow rate adjustment device (FCV1) may be capable of adjusting the flow rate of hydrogen gas into the preheater.

[0021] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may increase the amount of hydrogen gas flowing into the preheater so that heating of the hydrogen gas in the suction passage by the preheater is given priority over heating by the spillback unit (SB1), while controlling the flow rate adjustment means (FCV1) so that a temperature TS3 downstream of the preheater acquired by the third temperature sensor does not fall below a threshold value. Furthermore, when the suction temperature TS2 is lower than the predetermined temperature range, the control unit may control the flow rate adjustment means (FCV1) and the spillback valve so that the suction temperature TS2 falls within the predetermined temperature range.

[0022] In the above-described embodiment, the heating of the hydrogen gas in the suction passage by the preheater takes priority over heating by the spillback section, and if heating is insufficient, heating by the spillback section is used to compensate. This minimizes the loss of power required to return the compressed gas to the suction side compared to when heating is only performed by the spillback section. Therefore, in the above-described embodiment, the suction temperature can be managed within a certain range while suppressing a decrease in processing efficiency.

[0023] In addition, in the above embodiment, the temperature TS3 of the hydrogen gas downstream of the preheater is obtained by the third temperature sensor, and the control unit controls the flow rate adjustment means (FCV1) based on the temperature TS3 of the hydrogen gas obtained by the third temperature sensor, thereby preventing excessive temperature drops in the hydrogen gas supplied to the demand destination.

[0024] The compressor unit according to the above aspect may further include a preheater, a third temperature sensor, and a flow rate adjustment device (FCV1). The preheater may be capable of exchanging heat between hydrogen gas before being drawn into the first compression stage and hydrogen gas flowing through the intermediate flow path. The third temperature sensor may be disposed downstream of the preheater in the intermediate flow path. The flow rate adjustment device (FCV1) may be capable of adjusting the flow rate of hydrogen gas into the preheater.

[0025] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may increase the inflow rate of hydrogen gas to the preheater so that heating of the hydrogen gas in the suction passage by the preheater can be given priority over heating by the spillback unit (SB1), and may control the flow rate adjustment means (FCV1) so that a temperature TS3 downstream of the preheater acquired by the third temperature sensor does not fall below a threshold value. Furthermore, when the suction temperature TS2 is lower than the predetermined temperature range, the control unit may control the flow rate adjustment means (FCV1) and the spillback valve so that the suction temperature TS2 falls within the predetermined temperature range.

[0026] The above-mentioned aspect includes a preheater capable of heat exchange between hydrogen gas before being drawn into the first compression stage and hydrogen gas flowing through the intermediate flow path. Furthermore, in the above-mentioned aspect, heating of hydrogen gas in the suction flow path by the preheater takes priority over heating by the spillback section, and if heating is insufficient, heating by the spillback section is used to compensate. This minimizes the loss of power required to return compressed gas to the suction side compared to when heating is only performed by the spillback section. Therefore, in the above-mentioned aspect, the suction temperature can be maintained within a certain range while suppressing a decrease in processing efficiency.

[0027] In addition, in the above embodiment, the temperature TS3 of the hydrogen gas downstream of the preheater is obtained by the third temperature sensor, and the control unit controls the flow rate adjustment means (FCV1) based on the temperature TS3 of the hydrogen gas obtained by the third temperature sensor, thereby preventing excessive temperature drops in the hydrogen gas supplied to the demand destination.

[0028] In the compressor unit according to the above aspect, the check valve may be provided in the discharge flow path, and the branch point may be provided upstream of the check valve in the discharge flow path. The compressor unit according to this aspect may further include another low-pressure gas discharge path and a second destination switching means (CV2). The other low-pressure gas discharge path may be a path that branches off from another branch point provided in the intermediate flow path and is capable of discharging hydrogen gas to another low-pressure destination (D3) that can process hydrogen gas at a pressure lower than that required by the high-pressure destination (D1). The second destination switching means (CV2) may be provided in the other low-pressure gas discharge path or the other branch point.

[0029] In the compressor unit according to this aspect, the control unit is When the destination switching means (CV1) is in the first switching state, the control unit may control the second destination switching means (CV2) to distribute the hydrogen gas in the intermediate flow path to the other low-pressure gas discharge path. Furthermore, when the destination switching means (CV1) is in the second switching state, the control unit may control the second destination switching means (CV2) to send the hydrogen gas to the discharge flow path toward the high-pressure destination (D1).

[0030] In the above embodiment, the control unit controls the two demand destination switching means (CV1), (CV2) to switch between a first switching state and a second switching state, and hydrogen gas can be discharged not only to the low-pressure gas discharge path but also to other low-pressure gas discharge paths, so the pressure of hydrogen gas in the intermediate flow path can be reduced compared to a case where other low-pressure gas discharge paths are not provided. Therefore, in the above embodiment, the suction pressure of the compression stage located downstream of the intermediate flow path can be reduced, and the power required for startup can be reduced.

[0031] In the compressor unit according to the above aspect, the check valve may be provided in the discharge flow path, and the branch point may be provided at a position upstream of the check valve in the discharge flow path. The compressor unit according to this aspect may further include another low-pressure gas discharge path, a second destination switching means (CV2), and an adjustment means. The other low-pressure gas discharge path may be a path that branches off from another branch point in the intermediate flow path and is capable of discharging hydrogen gas to another low-pressure destination (D3) that can process hydrogen gas at a pressure lower than that required by the high-pressure destination (D1). The second destination switching means (CV2) may be provided in the other low-pressure gas discharge path or the other branch point. The adjustment means may adjust the amount of hydrogen gas processed by subsequent compression stages, excluding the first compression stage, among the plurality of compression stages.

[0032] In the compressor unit according to this embodiment, when the demand destination switching means (CV1) is in the second switching state, the control unit may control the second demand destination switching means (CV2) so that hydrogen gas is discharged to the other low-pressure gas discharge path in accordance with the demand amount of the other low-pressure demand destination (D3) or the fluctuation in the demand amount of the high-pressure demand destination (D1), while controlling the adjustment means so that the throughput of the subsequent compression stage is adjusted.

[0033] In the above embodiment, when the required amount (demanded amount) of hydrogen gas at a high-pressure demand destination is reduced, hydrogen gas is discharged to another low-pressure demand destination, thereby balancing the amount of boil-off gas generated from the liquid hydrogen storage tank and the amount of hydrogen gas delivered by the compressor unit, thereby maintaining a constant pressure in the liquid hydrogen storage tank.

[0034] Furthermore, in the above aspect, since the adjusting means is provided, the suction pressure of the subsequent compression stage can be kept substantially constant. Therefore, in the above aspect, the pressure balance of each subsequent compression stage can be always kept constant, and high compressor reliability can be achieved. In other words, if it is not possible to keep the pressure balance of the subsequent compression stages constant, it is necessary to provide a compressor with a large margin that can absorb such changes. However, in the above aspect, there is no need to provide a compressor with a large margin.

[0035] In the compressor unit according to the above aspect, the adjustment means may include a second spillback section (SB2). When the spillback section (SB1) returns the hydrogen gas discharged to the discharge passage to the suction passage, the second spillback section (SB2) may include a second spillback passage that returns hydrogen gas from an upstream side of a branching point on the discharge passage where the spillback passage branches to the suction side of the subsequent compression stage, and a spillback valve that adjusts the amount of spillback in the second spillback passage.

[0036] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may control the second spillback valve so that a flow rate corresponding to the fluctuation in the demand amount of the other low-pressure demand destination (D3) or the demand amount of the high-pressure demand destination (D1) is returned to the suction side of the subsequent compression stage.

[0037] In the above embodiment, since the second spillback section is provided, even if the demand amount from the high-pressure demand destination (D1) decreases, the suction pressure of the subsequent compression stage can be kept substantially constant by returning the compressed hydrogen gas to the suction side of the subsequent compression stage by the second spillback section. Therefore, in the above embodiment, the pressure balance of each subsequent compression stage is always constant, and high reliability of the compressor can be achieved.

[0038] In the compressor unit according to the above aspect, the adjustment means may include a second spillback section (SB2). When the spillback section (SB1) returns hydrogen gas flowing through the intermediate flow path to the suction flow path, the spillback section (SB1) may include a second spillback flow path that returns hydrogen gas discharged from a compression stage located downstream of a branching point on the intermediate flow path from which the spillback flow path branches to a side upstream of the compression stage, and a second spillback valve that adjusts the amount of spillback in the second spillback flow path.

[0039] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may control the second spillback valve so that a flow rate equivalent to the return amount of the spillback section (SB1) is returned upstream of the compression stage.

[0040] In the above aspect, since the second spillback section is provided, even if the throughput of the compression stage decreases due to the return of hydrogen gas to the suction flow path by the spillback section, the suction pressure of the compression stage can be kept approximately constant by returning the compressed hydrogen gas to the upstream side of the compression stage by the second spillback section, thereby achieving high reliability of the compressor.

[0041] In the compressor unit according to the above aspect, the adjusting means may include an on / off type intake valve unloader, and the on / off type intake valve unloader may be attached to a cylinder portion of the subsequent compression stage.

[0042] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may control the suction valve unloader so that a flow rate corresponding to the demand amount of the other low-pressure demand destination (D3) or the fluctuation in the demand amount of the high-pressure demand destination (D1) is returned to the suction side of the subsequent compression stage.

[0043] In the above embodiment, since the second spillback section is provided, even if the demand amount from the high-pressure demand destination (D1) decreases, the suction pressure of the subsequent compression stage can be kept substantially constant by returning the compressed hydrogen gas to the suction side of the subsequent compression stage by the second spillback section. Therefore, in the above embodiment, the pressure balance of each subsequent compression stage is always constant, and high reliability of the compressor can be achieved.

[0044] In the compressor unit according to the above aspect, the adjusting means may include a stepless capacity adjusting device. The stepless capacity adjusting device may include a suction valve unloader and a drive device. The suction valve unloader may be attached to a cylinder portion of the subsequent compression stage. The drive device may be a hydraulic or electric drive device that opens and closes the suction valve unloader.

[0045] In the compressor unit according to this aspect, when the demand destination switching means (CV1) is in the second switching state, the control unit may adjust the throughput of the subsequent compression stage by controlling the timing at which the suction valve unloader operates in conjunction with the rotational movement of the crankshaft so that hydrogen gas sucked from inside the cylinder unit to the suction side is returned in accordance with a flow rate corresponding to the requested amount of the other low-pressure demand destination (D3) or the fluctuation in the requested amount of the high-pressure demand destination (D1).

[0046] In the above embodiment, since another low-pressure gas discharge path is provided and the adjusting means is configured to include an intake valve unloader, when the demand destination switching means (CV1) is in the second switching state, the control unit can control the capacity adjusting device to return part of the hydrogen gas inside the cylinder to the intake side. Therefore, in the above embodiment, the amount of hydrogen gas processed in the subsequent compression stage can be reduced, further reducing power.

[0047] A compressor unit according to another aspect of the present invention is a reciprocating compressor unit that recovers hydrogen gas, which is boil-off gas, from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a high-pressure demand destination (D1) including at least one of an engine, a power generation facility, and a boiler. The compressor unit according to this aspect includes a plurality of compression stages, a crank mechanism, a spillback unit (SB1), a low-pressure gas discharge path, a demand destination switching means (CV1), a check valve, a first temperature sensor, a second temperature sensor, a pressure sensor, and a control unit.

[0048] The multiple compression stages compress hydrogen gas drawn in through an intake passage. The crank mechanism drives the multiple compression stages. The spillback unit (SB1) includes a spillback passage that returns hydrogen gas discharged into a discharge passage on the discharge side of the multiple compression stages or hydrogen gas flowing through an intermediate passage between the multiple compression stages to the intake passage, and a spillback valve that adjusts the amount of spillback in the spillback passage. The low-pressure gas discharge passage is a passage that branches off from a branch point provided in the intermediate passage and is capable of discharging hydrogen gas to a low-pressure demand destination (D2) that can process hydrogen gas at a pressure lower than that required by the high-pressure demand destination (D1). The demand destination switching means (CV1) is provided in the low-pressure gas discharge passage or the branch point. The check valve is provided in the intermediate passage downstream of the branch point. The first temperature sensor is arranged in the intermediate passage upstream of the branch point. The second temperature sensor is connected to a connection point of the spillback passage in the intake passage. Located at the front stage of the plurality of compression stages The pressure sensor is provided in the low-pressure gas discharge passage, and the control unit controls the demand destination switching means (CV1) and the spillback valve.

[0049] In the compressor unit according to this aspect, when the temperature TS1 acquired by the first temperature sensor is equal to or greater than a predetermined first temperature threshold T1 that is greater than 0°C during startup, the control unit: The first compression stageThe control unit controls the demand destination switching means (CV1) to a first switching state in which hydrogen gas discharged from the low-pressure gas discharge path is circulated through the low-pressure gas discharge path. When the temperature TS1 acquired by the first temperature sensor becomes less than the first temperature threshold T1, the control unit controls the demand destination switching means (CV1) to a third switching state in which hydrogen gas is circulated through both the low-pressure gas discharge path and a portion of the intermediate flow path downstream of the branch point. When the demand destination switching means (CV1) is in the third switching state, the control unit controls the demand destination switching means (CV1) so that the pressure PS2 acquired by the pressure sensor falls within a predetermined range, and controls the spillback 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.

[0050] 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.

[0051] In the above aspect, even if the hydrogen gas in the piping on the liquid hydrogen storage tank side rises to a positive temperature range (room temperature) during startup, the control unit controls the destination switching means (CV1) to enter a first switching state in which hydrogen gas is delivered both downstream of the branch point in the intermediate flow path and from the branch point to the low-pressure destination (D2). Therefore, in the above aspect, the compression ratio in the compression stage is kept low compared to when hydrogen gas is delivered only to the high-pressure destination (D1) from the discharge flow path, preventing excessive temperature rise of the hydrogen gas due to compression and temperature increase in the compression stage. In other words, the compression stage can be protected. Furthermore, even if the hydrogen gas in the piping is at room temperature during startup of the unit, delivery of hydrogen gas to both the high-pressure destination (D1) and the low-pressure destination (D2) as described above allows for rapid startup of the compressor unit.

[0052] On the other hand, in the above aspect, when the demand destination switching means (CV1) is in the third switching state, the control unit controls the demand destination switching means (CV1) so that the acquired hydrogen gas pressure PS2 is within a predetermined range, and the control unit controls the spillback valve so that the suction temperature TS2 is within the above-mentioned predetermined temperature range, thereby protecting the compressor unit in an environment where the hydrogen gas is at a low temperature.

[0053] The compressor unit according to the above aspect may further include an adjusting means and a second pressure sensor. The adjusting means may adjust the amount of hydrogen gas processed by subsequent compression stages excluding the first compression stage among the plurality of compression stages. The second pressure sensor may be provided in the intermediate flow path between the first compression stage and the subsequent compression stage.

[0054] In the compressor unit of this embodiment, when the demand destination switching means (CV1) is in the third switching state, the control unit may control the adjustment means so that the throughput of the subsequent compression stage is adjusted in accordance with the amount of change in pressure PS1 in the intermediate flow path acquired by the second pressure sensor.

[0055] In the above aspect, when the demand destination switching means (CV1) is in the third switching state, the control unit is configured to control the adjustment means to reduce the amount of hydrogen gas processed in the subsequent compression stage, thereby reducing the power required for the subsequent compression stage. [Effects of the Invention]

[0056] In the compressor unit according to each of the above aspects, the components can be appropriately protected from a wide range of temperature changes of the boil-off gas of liquefied hydrogen. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a compressor unit according to a first embodiment. [Figure 2]4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 3] FIG. 4 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the first embodiment. [Figure 4] FIG. 4 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the first embodiment. [Figure 5] FIG. 6 is a diagram schematically illustrating a partial configuration of a compressor unit according to a second embodiment. [Figure 6] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 7] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the second embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a third embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the third embodiment. [Figure 10] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a fourth embodiment. [Figure 11] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 12] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the fourth embodiment. [Figure 13] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a fifth embodiment. [Figure 14] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 15] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 16] FIG. 13 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the fifth embodiment. [Figure 17]4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 18] FIG. 13 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the fifth embodiment. [Figure 19] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 20] FIG. 13 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the fifth embodiment. [Figure 21] FIG. 10 is a diagram schematically illustrating a partial configuration of a compressor unit according to a sixth embodiment. [Figure 22] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 23] FIG. 13 is a diagram schematically illustrating a partial configuration of a compressor unit according to a seventh embodiment. [Figure 24] 4 is a flowchart showing operation control executed by a control unit during operation of the compressor unit. [Figure 25] FIG. 13 is a diagram schematically showing a partial configuration of a compressor unit according to a modified example of the seventh embodiment. [Figure 26] FIG. 4 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the first embodiment. [Figure 27] FIG. 4 is a diagram schematically illustrating a partial configuration of a compressor unit according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0058] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0059] (First embodiment) The compressor unit according to this embodiment is a reciprocating compressor unit that is configured to recover boil-off gas (hydrogen gas) from a liquid hydrogen storage tank, compress the recovered hydrogen gas, and supply it to a consumer. The boil-off gas (hydrogen gas) has a temperature of approximately -253°C.

[0060] As shown in FIG. 1, the compressor unit 10 includes multiple compression stages (a first compression stage 12, a subsequent compression stage 14) that compress hydrogen gas in an intake passage 21, and a crank mechanism 16 that drives the first compression stage 12 and the subsequent compression stage 14.

[0061] The first compression stage 12 is connected to the liquid hydrogen storage tank 23 via the suction passage 21. Therefore, boil-off gas of the liquefied gas generated in the liquid hydrogen storage tank 23 is sucked into the first compression stage 12 through the suction passage 21.

[0062] The first compression stage 12 is configured by a reciprocating compression mechanism. The first compression stage 12 has a piston that reciprocates within a cylinder portion, and is connected to the crank mechanism 16 via a piston rod connected to the piston. The first compression stage 12 may be configured by an oil-free compression mechanism that does not use lubricating oil. The first compression stage 12 may also be a compression stage with a double-acting structure, or may be a compression stage with a single-acting structure.

[0063] 1, the first compression stage 12 is shown as a single trapezoid for convenience, but the first compression stage 12 may be configured such that the hydrogen gas is compressed and pressurized by the reciprocating motion of pistons in multiple cylinders. This also applies to other embodiments.

[0064] The subsequent compression stage 14 is connected to the first compression stage 12 via an intermediate flow path 22, and is a compression mechanism for further compressing the hydrogen gas compressed in the first compression stage 12. The hydrogen gas compressed in the subsequent compression stage 14 is then discharged to a discharge flow path 24. The hydrogen gas flowing through the discharge flow path 24 is sent to a high-pressure destination D1 or a low-pressure destination D2 by switching using a destination switching means CV1. The hydrogen gas discharged from the compressor unit does not necessarily have to be supplied directly to the high-pressure destination D1, and may be filled into a cylinder or the like and then supplied to the high-pressure destination D1 by various means, such as transporting the cylinder or using a gas pipe connected to the cylinder.

[0065] The high-pressure demand destination D1 includes at least one of an engine, a power generation facility, or a boiler, and in addition, includes facilities that release gas into the atmosphere, such as a flare facility and a vent. It may be possible.

[0066] The low-pressure demand destination D2 is a facility that can process hydrogen gas at a pressure lower than the pressure of hydrogen gas required by the high-pressure demand destination D1. The low-pressure demand destination D2 may include, for example, facilities that utilize gas as an energy source, such as engines, power generation facilities, and boilers, as well as facilities that utilize gas at approximately atmospheric pressure, such as flare facilities and vents.

[0067] The subsequent compression stage 14 is also configured by a reciprocating compression mechanism, similar to the first compression stage 12. The subsequent compression stage 14 also has a piston that reciprocates within a cylinder, and is connected to the crank mechanism 16 via a piston rod connected to the piston.

[0068] The subsequent compression stage 14 may be connected to a leak gas discharge section that returns leak gas generated in the compression stage 14 to the suction flow path 21. Although the subsequent compression stage 14 is shown as a single trapezoid in FIG. 1 for convenience, the subsequent compression stage 14 does not necessarily have to be a single-stage type, and may have multiple compression mechanisms. In other words, the subsequent compression stage 14 may be configured so that hydrogen gas is sequentially compressed and pressurized by the reciprocating motion of pistons in multiple cylinder sections connected in series. The same applies to other embodiments. In the subsequent compression stage 14, the compression stage that discharges room-temperature hydrogen gas may be either oil-free or lubricated.

[0069] As shown in FIG. 1, the compressor unit 10 includes a spillback section SB1 that returns a portion of the hydrogen gas discharged from the subsequent compression stage 14 to the discharge passage 24 to the suction passage 21. The spillback section SB1 includes a spillback passage 18a and a spillback valve 18b, which is an adjustable valve disposed in the spillback passage 18a. One end of the spillback passage 18a is connected to the discharge passage 24, and the other end is connected to the suction passage 21. In other words, the hydrogen gas that flows through the spillback passage 18a merges with hydrogen gas from the liquid hydrogen storage tank 23 in the suction passage 21. The spillback valve 18b adjusts the amount of spillback in the spillback passage 18a.

[0070] The compressor unit 10 also includes a branch point P B and a low-pressure gas discharge passage 53 branching at the branch point P and connected to the low-pressure demand destination D2, and a demand destination switching means CV1 for switching the supply destination of the hydrogen gas discharged from the subsequent compression stage 14 between the high-pressure demand destination D1 and the low-pressure demand destination D2. B is located upstream of the point where the spillback flow path 18a is connected to the discharge flow path 24. B The check valve 54 may be provided downstream of the connection point of the spillback flow path 18a. BThis valve allows hydrogen gas to flow from the high-pressure demand destination D1 to the branch point P B This can prevent the gas from flowing back into the low-pressure gas discharge path 53.

[0071] The demand destination switching means CV1 is configured by a control valve 56a that can be opened and closed and the degree of opening can be adjusted, and in this embodiment, as an example, it is provided in the low pressure gas discharge path 53. However, the demand destination switching means CV1 is provided at the branch point P B Alternatively, the branch point P B The demand destination switching means CV1 may be provided at a location downstream of the regulator valve 56a. In this embodiment, the demand destination switching means CV1 is configured by the regulator valve 56a, but this is not limited to this. For example, it is also possible to use the demand destination switching means CV1 configured by an on-off valve that can take two positions, fully open and fully closed.

[0072] The demand destination switching means CV1 switches between a state in which the hydrogen gas discharged from the subsequent compression stage 14 is sent to the high-pressure demand destination D1 (second switching state) and a state in which the hydrogen gas is sent to the low-pressure demand destination D2 (first switching state). The hydrogen gas flow path can be switched between a normal state and a normal state.

[0073] 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 disposed in the intake passage 21 between the connection portion of the spillback passage 18a and the first compression stage 12. Therefore, when hydrogen gas flows through the spillback passage 18a, the upstream temperature sensor 45 can acquire the temperature TS2 of the hydrogen gas that is obtained after the hydrogen gas from the liquid hydrogen storage tank 23 is combined with the hydrogen gas from the spillback passage 18a and is taken into the first compression stage 12.

[0074] The intermediate temperature sensor 46 is connected to the first compression stage 12. Subsequent Compression StageThe intermediate temperature sensor 46 is disposed in the intermediate flow path 22 connecting the intermediate flow path 14 and the hydrogen gas supply passage 14. Therefore, the intermediate temperature sensor 46 can acquire the temperature TS1 of the hydrogen gas flowing through the intermediate flow path 22.

[0075] The upstream temperature sensor 45 and the intermediate temperature sensor 46 each send the acquired temperature information to the control unit 50. The control unit 50 is configured with a microprocessor including an MPU / CPU, ASIC, ROM, RAM, etc., and controls various operations of the compressor unit 10 by executing firmware, etc., pre-stored in the memory. The functions of the control unit 50 include a first control unit 50a and a second control unit 50b. The first control unit 50a is a functional unit configured to control the demand destination switching means CV1 by referring 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 spillback valve 18b by referring to the hydrogen gas temperature TS2 acquired by the upstream temperature sensor 45.

[0076] Here, the operational control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to FIG.

[0077] The control unit 50 determines whether the compressor unit 10 is already in operation or, if not in operation, whether or not there is a command to operate the compressor unit 10.

[0078] When a start command is issued to the compressor unit 10, the control unit 50 operates the crank mechanism 16, thereby driving the first compression stage 12 and the subsequent compression stage 14 (step ST1). In the first compression stage 12 and the subsequent compression stage 14, the pistons reciprocate within the cylinders due to the operation of the crank mechanism 16. As a result, in the first compression stage 12, hydrogen gas in the suction passage 21 is sucked into the first compression stage 12, and in the subsequent compression stage 14, hydrogen gas in the intermediate passage 22 is sucked into the subsequent compression stage 14, thereby compressing the hydrogen gas.

[0079] When the compressor unit 10 is started up, the temperature TS1 of the hydrogen gas flowing through the intermediate flow path 22 (discharged from the first compression stage 12) is acquired by the intermediate temperature sensor (first temperature sensor) 46. At this time, the control unit 50 refers to the temperature TS1 and determines whether the temperature TS1 is equal to or greater than a predetermined first temperature threshold T1 (step ST2). Here, the predetermined first temperature threshold T1 is a temperature greater than 0°C.

[0080] If the control unit 50 determines YES in step ST2 (TS1≧threshold value T1), the first control unit 50a controls the demand destination switching means CV1 so that the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows into the low-pressure gas discharge path 53 (step ST3). As a result, the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 passes through the low-pressure gas discharge path 53 and is sent to the low-pressure demand destination D2 (first switching state). That is, in the compressor unit 10, at the time of startup (step ST2: YES), the piping downstream of the first compression stage 12 If the hydrogen gas inside is at room temperature or higher (step ST2: YES), the compressed hydrogen gas is sent not to the high-pressure demand destination D1 but to the low-pressure demand destination D2 (step ST3). This makes it possible to protect the compressor from an excessive rise in discharge temperature due to boosting the pressure to a high level when the temperature of the intake gas of the subsequent compression stage 14 is high during startup.

[0081] On the other hand, if the control unit 50 determines NO (TS1<threshold value T1) in step ST2, the first control unit 50a controls the destination switching means CV1 so that the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows to the high-pressure destination D1 (step ST4). That is, the supply destination of the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 is switched from the low-pressure destination D2 to the high-pressure destination D1 (second switching state). Note that the first switching state corresponds to the start-up of the compressor unit 10, whereas the second switching state corresponds to the steady operation of the compressor unit 10.

[0082] During steady operation of the compressor unit 10, 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 is able to start spillback control while referring to the suction temperature TS2 (step ST5). That is, when the demand destination switching means CV1 is in the second switching state (step ST4), if the suction temperature TS2 is within a predetermined temperature range (T TH1 ≦TS2≦T TH2 The hydrogen gas in the intake passage 21 is heated so that

[0083] More specifically, TS2 <T TH1 In this case, the second control unit 50b controls the spillback valve 18b to return a portion of the gas in the discharge passage 24 to the suction passage 21, or to increase the amount of gas returned, thereby keeping the suction temperature TS2 within the above temperature range. TH2 In this case, the operation of returning a part of the gas in the discharge flow path 24 to the suction flow path 21 is not performed, or the amount of gas returned is reduced.

[0084] 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 TH1 and upper limit T TH2 is set to a temperature higher than the reference temperature and lower than 0°C.

[0085] As described above, when the second control unit 50b opens the spillback valve 18b and executes the spillback control (executes step ST5), the hydrogen gas from the liquid hydrogen storage tank 23 is not introduced directly into the first compression stage 12, but the hydrogen gas compressed in the subsequent compression stage 14 is joined and heated, and the heated hydrogen gas is introduced into the first compression stage 12. Moreover, when the intake temperature TS2 is higher than the lower limit T TH1Since the temperature is adjusted to the above range, it is possible to prevent the first compression stage 12 from being exposed to extremely low temperature hydrogen gas (a temperature lower than the predetermined temperature range), and it is also possible to prevent the density of the hydrogen gas drawn into the first compression stage 12 from becoming excessively high.

[0086] The compressor unit 10 having the above-described configuration is protected in an environment where the boil-off gas (hydrogen gas) is at a low temperature, and is also protected during startup when the boil-off gas (hydrogen gas) is at room temperature.

[0087] In a reciprocating compressor, boil-off gas (hydrogen gas) is discharged from the compressor at a pressure corresponding to the pressure of the supply destination of the boil-off gas. Under this premise, in the compressor unit 10 according to this embodiment, even if the hydrogen gas in the piping on the liquid hydrogen storage tank 23 side has risen to a positive temperature range (room temperature) at the time of startup, the hydrogen gas is discharged from the subsequent compression stage 14. The control unit 50 is configured to switch the demand destination switching means CV1 to the first switching state so that the discharged hydrogen gas flows to the low-pressure demand destination D2. Therefore, by discharging the hydrogen gas toward the low-pressure demand destination D2, which processes the hydrogen gas at a relatively low pressure, the compression ratio in the compression stages 12, 14 can be kept low, and an excessive temperature rise in the hydrogen gas caused by compressing and heating the hydrogen gas in the compression stages 12, 14 can be prevented. In other words, the compression stages 12, 14 can be protected.

[0088] Furthermore, even if the hydrogen gas in the piping on the liquid hydrogen storage tank 23 side is at room temperature when the compressor unit 10 is started up, the compressor unit 10 can be started up quickly by discharging the hydrogen gas from the compression stages 12, 14 toward the low-pressure demand destination D2 as described above.

[0089] On the other hand, in the compressor unit 10 according to this embodiment, when the demand destination switching means CV1 is in the second switching state, the hydrogen gas returned by the spillback section SB1 to the suction flow path 21 keeps the suction temperature TS2 within the above-mentioned predetermined temperature range (T TH1 ≦TS2≦T TH2) in the compressor unit 10. TH1 is set in a range higher than the reference temperature based on the liquefaction temperature of air, it is possible to prevent liquefaction of oxygen, which is a combustion-supporting gas, on the outer surface of the intake part of the first compression stage 12 or around the device to which hydrogen gas is supplied.

[0090] In addition, the compressor unit 10 is provided with a check valve 54 in the discharge flow path 24, which prevents backflow of hydrogen gas from the high-pressure demand destination D1 in the discharge flow path 24 to the subsequent compression stage 14, thereby appropriately protecting the compressor (first compression stage 12 and subsequent compression stage 14).

[0091] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0092] Although the compressor unit shown in Fig. 1 has a single-stage compression mechanism, the subsequent compression stage 14 may have multiple stages of compression mechanisms. For example, as shown in Fig. 3, the subsequent compression stage 14 may be configured with a first subsequent compression stage 14a and a second subsequent compression stage 14b. However, the subsequent compression stage 14 may have three or more stages of compression mechanisms. In other words, the compressor unit 10 as a whole may have four or more stages of compression mechanisms.

[0093] 1, the intermediate temperature sensor (first temperature sensor) 46 is arranged in the intermediate flow path 22, but the position at which the intermediate temperature sensor 46 is arranged is not limited to this. For example, as shown in FIG. 4, B The intermediate temperature sensor 46 may be disposed at a location upstream of the intermediate temperature sensor 46. In this case, the temperature of the hydrogen gas in the intermediate flow path 22 can be estimated by the intermediate temperature sensor 46 disposed in the discharge flow path 24, and the judgment in step ST2 can be made using the estimated temperature of the hydrogen gas in the intermediate flow path 22.

[0094] (Second embodiment) As shown in Fig. 5, the compressor unit 10 according to the second embodiment differs from the first embodiment in that it includes a preheater 71 that allows heat exchange between the hydrogen gas flowing through the suction passage 21 (the hydrogen gas sucked into the first compression stage 12) and the hydrogen gas discharged from the subsequent compression stage 14 to the discharge passage 24. In Fig. 5, the same components as those in the first embodiment are denoted by the same reference numerals, and hereinafter, explanations of overlapping parts will be omitted.

[0095] 5, discharge flow path 24 has first flow path 24a and second flow path 24b, which are flow paths branching from each other, upstream of the location where spillback flow path 18a is connected, and preheater 71 is provided between first flow path 24a, which is one of the flow paths, and suction flow path 21. This allows heat exchange in preheater 71 between hydrogen gas flowing through first flow path 24a and hydrogen gas flowing through suction flow path 21.

[0096] A flow rate adjustment device FCV1 is provided at the branch point of the first flow path 24a and the second flow path 24b in the discharge flow path 24. In this embodiment, the flow rate adjustment device FCV1 is configured as a three-way valve 72a, as an example, and is capable of directing the hydrogen gas discharged from the subsequent compression stage 14 to either the first flow path 24a or the second flow path 24b, or of directing the hydrogen gas to both the first flow path 24a and the second flow path 24b while adjusting the amount of hydrogen gas flowing through the first flow path 24a. However, the flow rate adjustment device FCV1 is not limited to the three-way valve 72a, as long as it can appropriately divide the hydrogen gas between the first flow path 24a and the second flow path 24b.

[0097] The compressor unit 10 according to this embodiment also includes a downstream temperature sensor (third temperature sensor) 48 disposed downstream of the preheater 71 in the discharge flow path 24. The downstream temperature sensor 48 can acquire a temperature TS3 of the hydrogen gas flowing in the portion of the discharge flow path 24 downstream of the preheater 71. The temperature information acquired by the downstream temperature sensor 48 is sent to the control unit 50.

[0098] In the compressor unit 10, the functions of the control unit 50 include a first control unit 50a, a second control unit 50b, and a third control unit 50c. The third control unit 50c is a functional unit configured to control the flow rate control means FCV1 by referring to the temperature TS3 of the hydrogen gas acquired by the downstream temperature sensor 48.

[0099] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 6. In the following description, the operation of the control unit 50 at startup (steps ST1 to ST3) is the same as in the first embodiment, and therefore the description thereof will be omitted.

[0100] When the steady operation state is reached (TS1<threshold value T1, NO in step ST2), the control unit 50 controls the demand destination switching means CV1 so that hydrogen gas flows toward the high-pressure demand destination D1 (step ST4).

[0101] The control unit 50 starts the preheater control while referring to the suction temperature TS2 acquired by the upstream temperature sensor 45 (step ST6). <T TH1 In this case, the third control unit 50c controls the flow rate adjusting means FCV1 so that the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows into the first flow path 24a and passes through the preheater 71 (step ST6). Then, the control unit 50 determines whether the temperature TS3 acquired by the downstream temperature sensor 48 is equal to or greater than the temperature T TH3 (Step ST7). If the control unit 50 judges that TS3 is greater than T TH3 ), the third control unit 50c continues the state in which hydrogen gas flows into the preheater 71. Heat exchange in the preheater 71 is continuously performed. TH2 If so, the preheater control is not performed.

[0102] On the other hand, if the control unit 50 determines in step ST7 that the result is NO (TS3≦T TH3), the flow rate adjusting means FCV1 is controlled so that the amount of hydrogen gas flowing into the preheater 71 is fixed (step ST8), and then spillback control is initiated (step ST5). That is, the second control unit 50b controls the spillback valve 18b so that a portion of the gas in the discharge flow path 24 is returned to the suction flow path 21. In this way, when the determination is NO in step ST7, in addition to heating the hydrogen gas by the preheater 71, heating of the hydrogen gas using the spillback unit SB1 is executed. As a result, the suction temperature TS2 is set to the lower limit T of the predetermined temperature range. TH1 It is adjusted so that it is equal to or greater than this.

[0103] In the compressor unit 10 having the above-described configuration, the heating of the hydrogen gas in the intake passage 21 by the preheater 71 is performed in the spillback section. SB1 If heating is insufficient, the spillback section SB1 is used to supplement the heating. This minimizes the loss of power required to return hydrogen gas to the suction side compared to when only heating is performed by the spillback section SB1. Therefore, the compressor unit 10 can manage the suction temperature TS2 within a certain range while suppressing a decrease in processing efficiency.

[0104] Furthermore, in the compressor unit 10, the downstream temperature sensor 48 acquires the temperature TS3 of the hydrogen gas downstream of the preheater 71 in the discharge flow path 24, and the third control unit 50c controls the flow rate control means FCV1 based on the temperature TS3 of the hydrogen gas acquired by the downstream temperature sensor 48, thereby preventing excessive temperature drops in the hydrogen gas supplied to the high-pressure demand destination D1.

[0105] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0106] 5 shows an example of a configuration in which the discharge 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, but the arrangement of the preheater 71 is not limited to this. For example, as shown in FIG. 7, the suction flow path 21 may be branched into the first flow path 21a and the second flow path 21b and the preheater 71 may be provided between one of the branched flow paths (the first flow path 21a) and the discharge flow path 24. In this case, a flow rate adjusting means FCV1 capable of adjusting the amount of hydrogen gas flowing into the preheater 71 may be provided at the branch point of the suction flow path 21 between the first flow path 21a and the second flow path 21b.

[0107] 5 and 7, the subsequent compression stage 14 has a single compression mechanism, but may have multiple compression mechanisms. That is, the compressor unit 10 as a whole may have three or more compression mechanisms.

[0108] (Third embodiment) As shown in Fig. 8, the compressor unit 10 according to the third embodiment differs from the second embodiment in that a preheater 71 is provided to enable heat exchange between hydrogen gases between the intermediate flow path 22 and the suction flow path 21. In Fig. 8, the same components as those in the second embodiment are denoted by the same reference numerals, and hereinafter, explanations of overlapping parts will be omitted.

[0109] In the compressor unit 10, the intermediate flow path 22 is configured to branch into a first flow path 22a and a second flow path 22b at a location downstream of the position where the intermediate temperature sensor 46 is disposed. In the compressor unit 10 according to this embodiment, a preheater 71 is provided in the intermediate flow path 22 between the first flow path 22a and the suction flow path 21.

[0110] The flow rate adjusting means FCV1 is provided at a branch point between the first flow path 22a and the second flow path 22b in the intermediate flow path 22. In the compressor unit 10, a downstream temperature sensor 48 is disposed between the preheater 71 and the subsequent compression stage 14. The downstream temperature sensor 48 acquires a temperature TS3 of the hydrogen gas taken into the subsequent compression stage 14.

[0111] In the operation of the compressor unit 10 according to this embodiment, the control unit 50 executes the same control as in the second embodiment, that is, the same control as that described with reference to FIG.

[0112] The compressor unit 10 having the above-described configuration is provided with a preheater 71 capable of exchanging heat between the hydrogen gas before being sucked into the first compression stage 12 and the hydrogen gas flowing through the intermediate flow path 22. As in the second embodiment, the compressor unit 10 also controls the heating of the hydrogen gas in the suction flow path 21 by the preheater 71 to take priority over heating by the spillback section SB1, and if the heating is insufficient, the heating by the spillback section SB1 is used to make up for the lack of heating. This minimizes the loss of power required to return the compressed hydrogen gas to the suction side compared to when only heating by the spillback section SB1 is performed. Furthermore, the inlet of the subsequent compression stage 14 (specifically, the second-stage compression mechanism located after the first compression stage 12) As the gas temperature decreases, the gas volume decreases and the compression power in the subsequent compression stage 14 also decreases. Therefore, in the compressor unit 10, the suction temperature TS2 can be managed within a certain range while suppressing a decrease in processing efficiency.

[0113] Furthermore, in the compressor unit 10, the downstream temperature sensor 48 acquires the temperature TS3 of the hydrogen gas downstream of the preheater 71 in the intermediate flow path 22, and the third control unit 50c controls the flow rate control means FCV1 based on the temperature TS3 of the hydrogen gas acquired by the downstream temperature sensor 48, thereby preventing excessive temperature drops in the hydrogen gas supplied to the high-pressure demand destination D1.

[0114] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0115] Although the compressor unit 10 shown in FIG. 8 has a single-stage compression mechanism, the subsequent compression stage 14 may have a multiple-stage compression mechanism. For example, as shown in FIG. 9, the subsequent compression stage 14 may be configured with a first subsequent compression stage 14a and a second subsequent compression stage 14b. In this case, a portion of the intermediate flow path 22 between the first subsequent compression stage 14a and the second subsequent compression stage 14b may be branched into a first flow path 22a and a second flow path 22b. The flow rate control device FCV1 may be provided at the branch point between the first flow path 22a and the second flow path 22b, for example. When this configuration is adopted, heat exchange is possible between the hydrogen gas discharged from the first subsequent compression stage 14a and the hydrogen gas flowing through the suction flow path 21.

[0116] However, the subsequent compression stage 14 may have a compression mechanism of three or more stages. That is, the compressor unit 10 may be provided with a compression mechanism of four or more stages as a whole. In the case of a configuration having a compression mechanism of four or more stages like this, a preheater 71 may be provided in the intermediate flow path 22 at a position on the suction side of the compression mechanism of the final stage.

[0117] (Fourth embodiment) The compressor unit 10 according to the fourth embodiment shown in Fig. 10 further includes a second low-pressure gas discharge passage 83, which is another low-pressure gas discharge passage. The second low-pressure gas discharge passage 83 is connected to a second branch point P B It branches at 2 and is connected to a second low-pressure demand destination (another low-pressure demand destination) D3.

[0118] The compressor unit 10 according to the fourth embodiment differs from the first embodiment in that, at startup, hydrogen gas is sent to a low-pressure demand destination D2 and a second low-pressure demand destination D3. In Fig. 10, the same components as those in the first embodiment are denoted by the same reference numerals, and explanations of overlapping parts will be omitted below.

[0119] The second low-pressure demand destination D3 is a facility that can process hydrogen gas at a pressure lower than the pressure of hydrogen gas required by the high-pressure demand destination D1. The second low-pressure demand destination D3 may include, for example, facilities that utilize gas as an energy source, such as engines, power generation facilities, and boilers, as well as facilities that utilize gas at approximately atmospheric pressure, such as flare facilities and vents.

[0120] The compressor unit 10 has a flow path for the hydrogen gas discharged from the first compression stage 12 and a flow path for the subsequent compression stage 14. Second low pressure gas discharge channel The system further includes second demand destination switching means CV2, which is another demand destination switching means for switching between the second low-pressure gas discharge passage 83 and the second low-pressure gas discharge passage 83. In this embodiment, the second demand destination switching means CV2 is configured by an adjustment valve 86a, as an example, and is provided in the second low-pressure gas discharge passage 83. Note that, although this embodiment employs second demand destination switching means CV2 configured by an adjustment valve 86a whose opening degree is adjustable, this is not limiting. For example, it is also possible to employ second demand destination switching means CV2 configured by an on-off valve that can be positioned in two positions, fully open and fully closed.

[0121] In the compressor unit 10, the functions of the control unit 50 include a fourth control unit 50d in addition to the first control unit 50a and the second control unit 50b. The fourth control unit 50d is a functional unit configured to control the second demand destination switching means CV2 by referring to the hydrogen gas temperature TS1 acquired by the intermediate temperature sensor 46.

[0122] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 11. In the following description, some of the description overlapping with the first embodiment will be omitted.

[0123] If the control unit 50 determines YES in step ST2 (TS1≧threshold T1), that is, at startup, the first control unit 50a controls the destination switching means CV1 to the first switching state so that the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows to the low-pressure destination D2. Furthermore, the fourth control unit 50d controls the second destination switching means CV2 so that a portion of the hydrogen gas discharged from the first compression stage 12 to the intermediate flow path 22 flows to the second low-pressure destination D3 (step ST9). Thus, in the first switching state in which the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows through the low-pressure gas discharge path 53 to the low-pressure destination D2, a portion of the hydrogen gas discharged from the first compression stage 12 to the intermediate flow path 22 flows through the second low-pressure gas discharge path 83 to the second low-pressure destination D3.

[0124] On the other hand, if the control unit 50 determines NO in step ST2 (TS1<threshold value T1), it controls the destination switching means CV1 and the second destination switching means CV2 so that the hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows to the high-pressure destination D1 (step ST10). That is, when the steady operation state is reached, the hydrogen gas compressed in the first compression stage 12 and the subsequent compression stage 14 is sent to the high-pressure destination D1 (second switching state). In the steady operation state, step ST5 (the step of starting spillback control) executed by the second control unit 50b is the same as in the first embodiment.

[0125] In the compressor unit 10 having the above configuration, the control unit 50 controls the demand destination switching means CV1 to switch between a first switching state and a second switching state, and in the first switching state, hydrogen gas can be discharged not only to the low-pressure gas discharge path 53 but also to the second low-pressure gas discharge path (another low-pressure gas discharge path) 83. The compressor unit 10 according to this embodiment can reduce the pressure of hydrogen gas in the intermediate flow path 22 compared to a unit not including the second low-pressure gas discharge path 83. Therefore, in the compressor unit 10, the suction pressure of the subsequent compression stage 14 arranged downstream of the intermediate flow path 22 can be reduced, and the power required for startup can be reduced.

[0126] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0127] In the compressor unit 10 shown in FIG. 10, the subsequent compression stage 14 has a single compression mechanism, but may have a multiple-stage compression mechanism. For example, as shown in FIG. 12, the subsequent compression stage 14 may be configured with a first subsequent compression stage 14a and a second subsequent compression stage 14b. Here, in the compressor unit 10 shown in FIG. 12, the gas flow path between the first compression stage 12 and the second subsequent compression stage 14b is the intermediate flow path 22. When this configuration is adopted, the branch point P at which the low-pressure gas discharge path 53 branches off is B may be disposed in the intermediate flow path 22 between the subsequent first compression stage 14a and the subsequent second compression stage 14b instead of in the discharge flow path 24.

[0128] However, the subsequent compression stage 14 may have a compression mechanism of three or more stages. In other words, the compressor unit 10 may have a compression mechanism of four or more stages as a whole. In this case, too, the gas flow path between the first compression stage 12 and the final compression mechanism of the compression mechanisms constituting the subsequent compression stage 14 is the intermediate flow path 22. In this configuration having compression mechanisms of four or more stages, a branch point P B may be placed.

[0129] (Fifth embodiment) The configuration of the compressor unit 10 according to the fifth embodiment shown in Fig. 13 differs from the compressor unit 10 according to the fourth embodiment shown in Fig. 10 in that the structure of the subsequent compression stage 14 is different. Furthermore, the processing of hydrogen gas by the compressor unit 10 differs from the processing of the compressor unit 10 according to the fourth embodiment in that hydrogen gas is sent only to the low-pressure demand destination D2 during startup, and is sent to the second low-pressure demand destination D3 and the high-pressure demand destination D1 during steady operation. Other points are the same as those of the fourth embodiment, and the same components as those of the fourth embodiment are designated by the same reference numerals, and hereinafter, explanations of overlapping parts will be omitted.

[0130] The compressor unit 10 is provided with an adjustment means 41 that adjusts the amount of hydrogen gas processed by the subsequent compression stage 14. The adjustment means 41 adjusts the gas processing amount by a method other than adjusting the rotation speed of the crank mechanism 16, and in this embodiment, as an example, is configured by attaching an on / off type suction valve unloader 61 to the cylinder portion of the subsequent compression stage 14, which adjusts the gas flow rate sent toward the high-pressure demand destination D1.

[0131] The compressor unit 10 also includes an intermediate pressure sensor (second pressure sensor) 47, a discharge channel pressure sensor (pressure sensor) 49, and a discharge channel pressure sensor (fourth pressure sensor) 87. The intermediate pressure sensor 47 is disposed on the suction side of the subsequent compression stage 14 in the intermediate flow path 22, and acquires the pressure PS1 of the hydrogen gas flowing through that portion. The discharge channel pressure sensor 87 is disposed in the discharge flow path 24, and acquires the pressure PS4 of the hydrogen gas flowing through the discharge flow path 24. The discharge channel pressure sensor 49 is disposed in the second low-pressure gas discharge path 83, and acquires the pressure PS2 of the hydrogen gas flowing through the second low-pressure gas discharge path 83. Each of the pressure sensors 47, 87, 49 sends the acquired pressure information to the control unit 50.

[0132] The functions of the control unit 50 include a first control unit 50a, a second control unit 50b, a fourth control unit 50d, and a fifth control unit 50e. The control unit 50 receives the pressure PS4 of the high-pressure demand destination D1, the pressure PS2 of the second low-pressure demand destination D3, and the inlet pressure PS1 of the subsequent compression stage 14, as well as set values ​​for the intermediate pressure range (pressure thresholds a1 and a2). The fifth control unit 50e is a functional unit configured to control the suction valve unloader 61, which is the adjustment means 41, so that the inlet pressure PS1 of the subsequent compression stage 14, which changes depending on fluctuations in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1, falls within a preset range.

[0133] The cylinder section of the subsequent compression stage 14 has two chambers: a push compression chamber that compresses during the piston's push stroke and a pull compression chamber that compresses during the piston's pull stroke. A capacity adjustment device is provided to load and unload each compression chamber individually. Loading both chambers results in 100% loading, while loading only one chamber results in 50% loading. The fifth control unit 50e sends a load or unload command to the suction valve unloader based on the pressure at the inlet of the subsequent compression stage 14 acquired by the second pressure sensor 47.

[0134] In compressor unit 10, when the supply amount to second low-pressure demand destination D3 increases, the amount of gas processed in subsequent compression stage 14 decreases compared to when there is no supply, and the pressure at the inlet of subsequent compression stage 14 decreases. That is, the differential pressure between the inlet and outlet of subsequent compression stage 14 increases as the supply amount to the second low-pressure demand destination increases, increasing the load acting on internal parts such as the piston that reciprocates in the cylinder of the compression stage for compression.

[0135] When the inlet pressure PS1 of the subsequent compression stage 14 falls below a preset pressure threshold a1, the load of the subsequent compression stage 14 can be reduced from 100% to 50%, thereby increasing the inlet pressure PS1 and reducing the load on the internal components. Furthermore, when the inlet pressure PS1 rises above a preset pressure threshold a2 under a 50% load, this is equivalent to an increase in the discharge pressure of the first compression stage 12, and the load on the first compression stage 12 can be reduced by increasing the load of the subsequent compression stage 14 to 100%.

[0136] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 14. In the following description, some of the description overlapping with the first embodiment will be omitted.

[0137] If the control unit 50 determines YES in step ST2 (TS1≧threshold T1), the first control unit 50a controls the demand destination switching means (CV1) to enter the first switching state. Note that at startup, the second demand destination switching means (CV2) is closed to prevent hydrogen gas from flowing to the second low-pressure demand destination D3. As a result, hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows only to the low-pressure demand destination D2 (step ST3). As a result, hydrogen gas discharged from the subsequent compression stage 14 to the discharge flow path 24 flows through the low-pressure gas discharge path 53 to the low-pressure demand destination D2 (first switching state).

[0138] When the steady operation state is reached (TS1<threshold value T1, NO in step ST2), the control unit 50 controls the demand destination switching means CV1 to the second switching state so that hydrogen gas is supplied to the high-pressure demand destination D1 (step ST4). Then, the second control unit 50b controls the spillback valve 18b to start spillback control (step ST5).

[0139] Furthermore, the fourth control unit 50d and the fifth control unit 50e control the second destination switching means CV2 and the adjustment means 41 (suction valve unloader) in accordance with the fluctuation in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1 (step ST11). That is, the fourth control unit 50d controls the second destination switching means CV2 so that hydrogen gas is discharged to the second low-pressure gas discharge line 83 in accordance with the fluctuation in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1. The fifth control unit 50e controls the adjustment means 41 so that the inlet pressure PS1 of the subsequent compression stage 14 falls within a preset threshold range. Specifically, the load is changed by the suction valve unloader 61.

[0140] The load change of the suction valve unloader 61 will be described in detail with reference to Figure 15. If the demand amount of the second low-pressure demand destination D3 increases (in other words, the demand amount of the high-pressure demand destination D1 decreases), that is, if the pressure PS1 detected by the intermediate pressure sensor 47 decreases and falls below the pressure threshold a1 (YES in step ST21), the load is changed from 100% to 50% by the suction valve unloading (step ST22). At 50% load, if the demand amount of the second low-pressure demand destination D3 decreases (in other words, the demand amount of the high-pressure demand destination D1 increases), that is, if the pressure PS1 detected by the intermediate pressure sensor 47 increases and exceeds the pressure threshold a2 (YES in step ST23), the load is changed from 50% to 100% by the suction valve unloader 61 (step ST24). If the amount of the second low-pressure demand destination D3 is not changed and is changed in accordance with the demand amount of the high-pressure demand destination D1, the amount of spillback by the spillback section SB1 may be adjusted.

[0141] In particular, when the demand from second low-pressure demand destination D3 increases, compressor unit 10 prevents an excessive drop in the pressure at the inlet of subsequent compression stage 14, thereby preventing excessive differential pressure from acting on its internal components. In other words, without this control, it would be necessary to provide a compressor with a large margin to absorb such changes, but compressor unit 10 allows for a smaller margin.

[0142] The compressor unit 10 shown in Fig. 16 is provided with, for example, an adjustment means 41 different from that shown in Fig. 13. In this embodiment, as an example, the adjustment means 41 is configured by a spillback section (second spillback section) SB2 that adjusts the processing amount of hydrogen gas so that the gas flow rate sent from the subsequent compression stage 14 toward the high-pressure demand destination D1 is adjusted.

[0143] The second spillback section SB2 has a second spillback flow path 43a and an adjustable-opening second spillback valve 43b disposed in the second spillback flow path 43a. One end of the second spillback flow path 43a is connected to a portion of the discharge flow path 24 upstream of the position where the check valve 54 is disposed, and the other end is connected to the intermediate flow path 22. Therefore, a portion of the hydrogen gas discharged from the subsequent compression stage 14 is returned to the suction side of the subsequent compression stage 14 in the intermediate flow path 22. The second spillback valve 43b adjusts the amount of spillback in the second spillback flow path 43a.

[0144] The compressor unit 10 also includes an intermediate pressure sensor (second pressure sensor) 47, a discharge channel pressure sensor (pressure sensor) 49, and a discharge channel pressure sensor (fourth pressure sensor) 87. The intermediate pressure sensor 47 is disposed in the intermediate flow path 22 at a position on the suction side of the subsequent compression stage 14, and acquires the pressure PS1 of the hydrogen gas flowing through that portion. The discharge channel pressure sensor 87 is disposed in the discharge flow path 24, and acquires the pressure PS4 of the hydrogen gas flowing through the discharge flow path 24. The discharge channel pressure sensor 49 is disposed in the second low-pressure gas discharge path 83, and acquires the pressure PS2 of the hydrogen gas flowing through the second low-pressure gas discharge path 83. Each of the pressure sensors 47, 87, 49 sends the acquired pressure information to the control unit 50.

[0145] The functions of the control unit 50 include a first control unit 50a, a second control unit 50b, a fourth control unit 50d, and a fifth control unit 50e. The control unit 50 is also provided with a pressure PS4 of the high pressure demand destination D1, a pressure PS2 of the second low pressure demand destination D3, and Subsequent Compression Stage The fifth control unit 50e is configured to input the pressure PS1 at the inlet of the subsequent compression stage 14, and further input the intermediate pressure setting values ​​(pressure threshold a1 and pressure threshold a2). The fifth control unit 50e is a functional unit configured to control the adjustment means 41 (second spillback valve 43b) so that the pressure PS1 at the inlet of the subsequent compression stage 14, which changes depending on the amount of gas required by the second low-pressure demand destination D3 or the amount of gas required by the high-pressure demand destination D1, becomes a preset value. The setting value of the inlet pressure of the subsequent compression stage 14 may be calculated from the values ​​of PS4 and PS2.

[0146] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 14. In the following description, some of the description overlapping with the first embodiment will be omitted.

[0147] When the steady operation state is reached (TS1<threshold value T1, NO in step ST2), the control unit 50 controls the demand destination switching means CV1 so that hydrogen gas is supplied to the high-pressure demand destination D1 (step ST4). Then, the second control unit 50b controls the spillback valve 18b to start spillback control (step ST5).

[0148] Furthermore, the fourth control unit 50d and the fifth control unit 50e control the second destination switching means CV2 and the adjustment means 41 (second spillback valve 43b) in accordance with the fluctuation in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1 (step ST11). That is, the fourth control unit 50d controls the second destination switching means CV2 so that hydrogen gas is discharged to the second low-pressure gas discharge path 83 in accordance with the fluctuation in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1. The fifth control unit 50e adjusts the opening of the second spillback valve 43b so that the gas throughput in the subsequent compression stage 14 is adjusted.

[0149] The opening adjustment of the second spillback valve 43b will be described in detail with reference to FIG. 17. When the demand volume of the second low-pressure demand destination D3 increases (in other words, the demand volume of the high-pressure demand destination D1 decreases), i.e., when the pressure PS1 detected by the intermediate pressure sensor 47 decreases and falls below the pressure threshold a11 (YES in step ST31), the amount of spillback by the second spillback unit SB2 is increased (step ST32). When the demand volume of the second low-pressure demand destination D3 decreases (in other words, when the demand volume of the high-pressure demand destination D1 increases), i.e., when the pressure PS1 detected by the intermediate pressure sensor 47 increases and exceeds the pressure threshold a2 (YES in step ST33), the amount of spillback by the second spillback unit SB2 is reduced (step ST34). If the demand volume of the second low-pressure demand destination D3 is not changed but is changed according to the demand volume of the high-pressure demand destination D1, the amount of spillback by the spillback unit SB1 may be adjusted.

[0150] As described above, in response to fluctuations in the gas demand amount of the second low-pressure demand destination D3 or the high-pressure demand destination D1, the suction pressure of the subsequent compression stage 14 is kept approximately constant by discharging hydrogen gas to the second low-pressure demand destination D3 and adjusting the gas processing amount in the subsequent compression stage 14 by the second spillback section SB2.

[0151] In the compressor unit 10 having the above-described configuration, when the required amount (demanded amount) of hydrogen gas at the high-pressure demand destination D1 is reduced, hydrogen gas is discharged to the second low-pressure demand destination D3, thereby balancing the amount of boil-off gas (hydrogen gas) generated from the liquid hydrogen storage tank 23 with the amount of hydrogen gas delivered from the compressor unit 10, thereby making it possible to maintain a constant pressure in the liquid hydrogen storage tank 23.

[0152] Furthermore, since the compressor unit 10 is provided with the adjustment means 41 (second spillback section SB2), the suction pressure of the subsequent compression stage 14 can be kept substantially constant. Therefore, in the compressor unit 10, the pressure balance of each subsequent compression stage can be kept constant at all times, and high compressor reliability can be obtained. In other words, if it is not possible to keep the pressure balance of the subsequent compression stage 14 constant, it is necessary to provide a compressor with a large margin that is sufficient to absorb the change, but the compressor unit 10 does not need to provide a compressor with a large margin.

[0153] Furthermore, the use of the compressor unit 10 enables efficient recovery and supply of hydrogen gas. Furthermore, by using the gas that has been compressed and heated by the compressor as a heat source to heat the extremely low temperature intake gas to an appropriate temperature, it is possible to prevent excess CO2 emissions compared to installing a heater that uses the heat from the combustion of fossil fuels, for example, upstream of the compressor.

[0154] As shown in FIG. 18, the compressor unit 10 may have an adjustment means 41 configured by using an on / off type suction valve unloader 61 similar to that shown in FIG. 13 in combination with a second spillback section SB2 similar to that shown in FIG. 16.

[0155] As shown in FIG. 19, in the control of the adjusting means 41, when the state (valve opening) of the second spillback valve 43b input to the control unit 50 becomes larger than a preset opening threshold b1 ( Spillback amount When the opening of the second spillback valve 43b becomes smaller than the opening threshold b2 (Yes in step ST43), the suction valve unloader 61 is controlled to increase the load of the subsequent compression stage 14 (from 50% to 100%) (step ST44). In this way, when spillback is excessive, power can be reduced by reducing the load of the subsequent compression stage 14.

[0156] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0157] As shown in FIG. 20, the compressor unit 10 may include a stepless capacity adjuster 64b provided in the subsequent compression stage 14 as the adjusting means 41.

[0158] The stepless capacity adjuster 64b has a suction valve unloader 61b, a drive unit 62b, and a detector 63b that detects the rotation of the crank mechanism. The suction valve unloader 61b is driven by a hydraulic or electric drive unit 62b, and can maintain or release the open state of the suction valve plate faster than the time it takes for the piston to reciprocate. In addition, the control unit performs calculations to estimate the piston position based on a signal sent from the detector 63b installed in the crank mechanism.

[0159] The intake valve installed in the cylinder section of the subsequent compression stage 14 between the intake passage and the compression chamber is composed of a valve plate that opens and closes the gas passage and a valve body that houses it.Like a check valve, if the upstream pressure is higher than the downstream pressure, the valve plate opens due to the pressure difference, but if the downstream pressure is higher, gas does not flow.

[0160] When the suction valve unloader 61b is driven, the valve plate of the suction valve is kept open, preventing it from functioning as a check valve. When the piston goes through the suction stroke without the unloader being driven, the pressure in the compression chamber drops below the suction passage, causing the suction valve to open and gas to be introduced into the compression chamber. When the piston goes through the compression stroke, the pressure in the compression chamber rises above the suction passage, causing the suction valve to close.

[0161] At the beginning of the compression stroke, the stepless capacity adjuster 64b maintains the open state, returning some of the gas introduced into the compression chamber to the suction passage, and then cancels the open state midway through the compression stroke, closing the suction valve and compressing and discharging the gas remaining in the compression chamber.The drive unit is again driven during the next piston suction stroke, and the open state is canceled once the piston's compression stroke begins.This process is repeated in accordance with the reciprocating motion of the piston.

[0162] If the release timing is made earlier, the discharge volume increases, and if it is made later, the discharge volume decreases, so it can perform the same function as a second spillback valve.In addition, since the amount of gas to be compressed is adjusted, the effect of reducing power consumption is significant.

[0163] Furthermore, when the subsequent compression stage 14 has a configuration including multiple compression mechanisms as shown in FIG. 12, the second spillback portion 43 and the capacity adjustment device 64b may be provided for at least one of the compression mechanisms.

[0164] (Sixth embodiment) Next, a compressor unit 10 according to a sixth embodiment will be described with reference to Fig. 21. The configuration of the compressor unit 10 differs from that of the compressor unit 10 according to the first embodiment shown in Fig. 1 in that the low-pressure gas discharge channel 53 is located in the intermediate flow path 22. Furthermore, with regard to the processing of hydrogen gas, the compressor unit 10 differs from the compressor unit 10 according to the first embodiment in that hydrogen gas is supplied to the low-pressure demand destination D2 via the low-pressure gas discharge channel 53 both at startup and during steady operation. In Fig. 21, the same components as those in the first embodiment are denoted by the same reference numerals, and hereinafter, description of overlapping parts will be omitted.

[0165] In the compressor unit 10 according to this embodiment, the low-pressure gas discharge passage 53 branches off at a branch point P Bis disposed downstream of the position where the intermediate temperature sensor 46 is disposed in the intermediate flow path 22. Furthermore, an intermediate pressure sensor 47 is disposed at a downstream position in the intermediate flow path 22. The intermediate pressure sensor 47 acquires the pressure PS1 of the hydrogen gas taken into the subsequent compression stage 14 and sends it to the control unit 50.

[0166] The compressor unit 10 also includes a discharge line pressure sensor 49. The discharge line pressure sensor 49 is disposed downstream of the position where the demand destination switching means CV1 is provided in the low-pressure gas discharge line 53. The discharge line pressure sensor 49 acquires the pressure PS2 of the hydrogen gas discharged to the low-pressure demand destination D2 through the low-pressure gas discharge line 53, and sends it to the control unit 50.

[0167] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 22. In the following description, some of the description overlapping with the first embodiment will be omitted.

[0168] When the control unit 50 determines that the temperature TS1 of the hydrogen gas flowing through the intermediate flow path 22 (discharged from the first compression stage 12) is equal to or greater than the threshold value T1 at the time of startup of the compressor unit 10, the first control unit 50a controls the demand destination switching means CV1 so that the hydrogen gas discharged from the first compression stage 12 to the intermediate flow path 22 flows to the low-pressure gas discharge path 53 (steps ST1 to ST3). That is, a first switching state is configured in which the hydrogen gas is sent to the low-pressure demand destination D2.

[0169] When the control unit 50 determines that the steady operation state has been reached (TS1<threshold value T1), the first control unit 50a controls the destination switching means CV1 so that hydrogen gas flows to both the high-pressure demand destination D1 and the low-pressure demand destination D2 (step ST12). That is, in the compressor unit 10 according to this embodiment, in executing step ST12, the opening of the destination switching means CV1 constituted by the adjustment valve 56a is adjusted to control the flow of hydrogen gas to both the high-pressure demand destination D1 and the low-pressure demand destination D2.

[0170] In a state where hydrogen gas is being delivered to both the high-pressure demand destination D1 and the low-pressure demand destination D2 (third switching state), the control unit 50 determines whether the pressure PS2 acquired by the discharge passage pressure sensor 49 is within a preset range (step ST13). If the control unit 50 determines NO in step ST13 (P TH1 ≧PS2 or PS2>P TH2 ), the first control unit 50a controls the demand destination switching means CV1 so that the pressure PS2 falls within the above-mentioned preset range (step ST14).

[0171] On the other hand, if the control unit 50 determines YES in step ST13 (P TH1 <PS2≦P TH2 ), spillback control is performed while referring to the suction temperature TS2 acquired by the upstream temperature sensor 45 (step ST5). <T TH1 In this case, the second control unit 50b controls the spillback valve 18b to return part of the gas in the discharge passage 24 to the suction passage 21. As a result, when the demand destination switching means CV1 is in the third switching state, the suction temperature TS2 is kept within a predetermined temperature range (T TH1 ≦TS2≦T TH2 ) the hydrogen gas in the intake passage 21 is heated so that TS2>T TH2 In this case, the operation of returning a part of the gas in the discharge flow path 24 to the suction flow path 21 is not performed. Here, the predetermined temperature range is set to a range higher than the reference temperature based on the liquefaction temperature of air and lower than 0°C, as in the first embodiment. That is, the lower limit value T TH1 and upper limit T TH2 is set to a temperature higher than the reference temperature and lower than 0°C.

[0172] The compressor unit 10 having the above-described configuration can appropriately protect its components from a wide range of temperature changes in the boil-off gas (hydrogen gas) from the liquid hydrogen storage tank 23. That is, the compressor unit 10 is configured to control the destination switching means CV1 to enter the first switching state in which hydrogen gas flows to the low-pressure destination D2, even if the hydrogen gas in the piping on the liquid hydrogen storage tank 23 side rises into a positive temperature range at startup. Therefore, the compressor unit 10 can keep the compression ratio of the subsequent compression stage 14 lower than when hydrogen gas flows only from the discharge flow path 24 to the high-pressure destination D1, thereby preventing an excessive temperature rise in the hydrogen gas caused by compressing and heating the hydrogen gas in the subsequent compression stage 14. That is, the subsequent compression stage 14 can be protected. Furthermore, the compressor unit 10 can be quickly started up.

[0173] On the other hand, in the compressor unit 10, when the demand destination switching means CV1 is in the third switching state, the first control unit 50a controls the demand destination switching means CV1 so that the pressure PS2 acquired by the discharge path pressure sensor 49 is within a predetermined range, and the second control unit 50b controls the spillback valve 18b so that the suction temperature TS2 acquired by the upstream temperature sensor 45 is within the above-mentioned predetermined temperature range, thereby protecting the compressor unit 10 in an environment where the hydrogen gas is at a low temperature.

[0174] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0175] In the compressor unit 10 shown in FIG. 21, the subsequent compression stage 14 has a single-stage compression mechanism, but may have a multi-stage compression mechanism.

[0176] (Seventh embodiment) As shown in Fig. 23, the compressor unit 10 according to the seventh embodiment differs from the sixth embodiment in that it is provided with an adjustment means 41 that adjusts the amount of hydrogen gas processed by the subsequent compression stage 14. In Fig. 23, the same components as those in the sixth embodiment are denoted by the same reference numerals, and hereinafter, explanations of overlapping parts will be omitted.

[0177] The adjustment means 41 adjusts the amount of hydrogen gas processed by the subsequent compression stage 14. The adjustment means 41 adjusts the gas processing amount by a method other than adjusting the rotation speed of the crank mechanism 16, and in this embodiment, as an example, is configured by a spillback unit (second spillback unit SB2) that adjusts the amount of hydrogen gas processed so as to adjust the gas flow rate sent from the subsequent compression stage 14 to the high-pressure demand destination D1.

[0178] The second spillback section SB2 has a second spillback passage 43a and an adjustable-opening second spillback valve 43b disposed in the second spillback passage 43a. One end of the second spillback passage 43a is connected to a portion of the discharge passage 24 upstream of the connection portion of the spillback passage 18a, and the other end is connected to the intermediate passage 22. Therefore, a portion of the hydrogen gas discharged from the subsequent compression stage 14 is returned to the suction side of the subsequent compression stage 14 in the intermediate passage 22. The second spillback valve 43b adjusts the amount of spillback in the second spillback passage 43a.

[0179] The functions of the control unit 50 include a fifth control unit 50e in addition to the first control unit 50a and the second control unit 50b. The fifth control unit 50e is a functional unit configured to control the adjustment means 41 (second spillback valve 43b) in accordance with the amount of change in the pressure PS1 acquired by the intermediate pressure sensor 47.

[0180] Here, the operation control executed by the control unit 50 in the operation of the compressor unit 10 according to this embodiment will be described with reference to Fig. 24. In the following description, descriptions that overlap with those in the sixth embodiment will be omitted.

[0181] When the control unit 50 determines that the steady operation state has been reached (TS1<threshold value T1), the first control unit 50a controls the demand destination switching means CV1 so that hydrogen gas flows to both the high-pressure demand destination D1 and the low-pressure demand destination D2 (step ST12). In the compressor unit 10 according to this embodiment, after the first control unit 50a executes step ST12, the fifth control unit 50e controls the adjustment means 41 (second spillback valve 43b) in accordance with the amount of change in pressure PS1 (step ST15). In this way, the fifth control unit 50e controls the second spillback valve 43b in accordance with the amount of change in pressure PS1, thereby adjusting the throughput of the subsequent compression stage 14. This embodiment differs from the sixth embodiment in that the fifth control unit 50e controls the adjustment means 41 (second spillback valve 43b).

[0182] The controls from step ST15 onwards in the operation of the compressor unit 10 according to this embodiment are the same as those in the sixth embodiment.

[0183] In the compressor unit 10 having the above configuration, when the demand destination switching means CV1 is in the third switching state, the fifth control unit 50e is provided with the adjustment means 41 (second spillback valve 43b), so the suction pressure of the subsequent compression stage 14 can be kept approximately constant. Therefore, in the compressor unit 10, the pressure balance of each subsequent compression stage can be always kept constant, and high compressor reliability can be obtained. In other words, if the pressure balance in the subsequent compression stage 14 cannot be kept constant, it is necessary to provide a compressor with a large margin that is enough to absorb the change, but the compressor unit 10 does not need to provide a compressor with a large margin.

[0184] Furthermore, if the compressor unit 10 is employed, it is possible to efficiently recover and supply hydrogen gas.

[0185] In the compressor unit 10 shown in FIG. 23, the subsequent compression stage 14 is a single-stage compression mechanism. However, the compressor may have a multi-stage compression mechanism. In this case, the adjusting means 41 may be provided for each of the multi-stage compression mechanisms, or one adjusting means 41 may be provided for the multi-stage compression mechanisms.

[0186] 23 includes a second spillback portion SB2 as an example of the adjustment means 41, but the adjustment means 41 is not limited to this. For example, as shown in FIG. 25, the adjustment means 41 may include a stepless capacity adjustment device 64b provided in the subsequent compression stage 14. The stepless capacity adjustment device 64b may be configured to include a suction valve unloader 61b, a drive device 62b, and a detector 63b that detects rotation of the crank mechanism, as described above.

[0187] Furthermore, when the subsequent compression stage 14 has a configuration including a multiple-stage compression mechanism as described above, Adjustment means Even as 41 Stepless capacity adjuster 64b may be provided in each compression mechanism or in some of the compression mechanisms.

[0188] Furthermore, the second spillback section SB2 employed in the compressor unit 10 shown in FIG. 23 and the capacity adjustment device 64b employed in the compressor unit 10 shown in FIG. 25 may be provided in parallel with the subsequent compression stage 14.

[0189] (Variation) The configuration of the compressor unit 10 according to a modified example of the first embodiment will be described with reference to Fig. 26. Note that Fig. 26 omits some of the configuration that is the same as that of the first embodiment. Also, in the following, description of overlapping parts will be omitted.

[0190] In the compressor unit 10 according to this modification, the subsequent compression stage 14 may have a compression mechanism with multiple stages. Specifically, in the compressor unit 10 according to this modification, the subsequent compression stage 14 may be configured with a first subsequent compression stage 14a and a second subsequent compression stage 14b. However, the subsequent compression stage 14 may have a compression mechanism with three or more stages. In other words, the compressor unit 10 as a whole may be provided with a compression mechanism with four or more stages.

[0191] Furthermore, in the compressor unit 10 according to this modification, a spillback passage 18a may be connected to a location between the subsequent first compression stage 14a and the subsequent second compression stage 14b in the intermediate passage 22. This allows a portion of the hydrogen gas heated in the subsequent first compression stage 14a to be returned to the suction passage 21 via the spillback section SB1.

[0192] Furthermore, an intermediate cooler unit 74 may be provided in the intermediate flow path 22 at a location between the subsequent first compression stage 14a and the subsequent second compression stage 14b. This allows the hydrogen gas whose temperature has increased due to compression in the subsequent first compression stage 14a to be cooled and sent to the subsequent second compression stage 14b, thereby protecting the subsequent second compression stage 14b.

[0193] The configuration of the compressor unit 10 according to another modified example of the first embodiment will be described with reference to Fig. 27. Note that Fig. 27 omits some of the configuration that is the same as that of the first embodiment. Also, in the following, description of overlapping parts will be omitted.

[0194] 26, the compressor unit 10 according to this modification has a subsequent compression stage 14 including a first subsequent compression stage 14a and a second subsequent compression stage 14b. The subsequent compression stage 14 may have a compression mechanism with three or more stages.

[0195] In addition, a spillback flow path 18a is connected to a location between the subsequent first compression stage 14a and the subsequent second compression stage 14b in the intermediate flow path 22. This allows a portion of the hydrogen gas heated in the subsequent first compression stage 14a to be returned to the suction flow path 21 via the spillback section SB1.

[0196] The compressor unit 10 further includes a second spillback section SB2 serving as adjustment means 41, located downstream of the branching portion of the spillback passage 18a in the intermediate passage 22. In detail, the second spillback section SB2 includes a second spillback passage 43a that returns hydrogen gas discharged from the subsequent second compression stage 14b, which is located downstream of the branching portion of the spillback passage 18a in the intermediate passage 22, to the upstream side of the subsequent second compression stage 14b (strictly speaking, to the suction side of the subsequent second compression stage 14b), and a second spillback valve 43b that adjusts the amount of spillback in the second spillback passage 43a.

[0197] When the demand destination switching means (CV1) is in the second switching state, the control unit 50 controls the second spillback valve 43b so that a flow rate equivalent to the return amount of the spillback section SB1 is returned to the upstream side of the subsequent second compression stage 14b, thereby making it possible to maintain a constant pressure balance in the subsequent second compression stage 14b.

[0198] 27, the spillback flow path 18a may be connected to the intermediate flow path 22 at a location between the first compression stage 12 and the subsequent first compression stage 14a. In this case, the second spillback flow path 43a may be configured to return the hydrogen gas discharged from the subsequent first compression stage 14a to the upstream side of the subsequent first compression stage 14a. The second spillback flow path 43a may also be configured to return the hydrogen gas discharged from the subsequent second compression stage 14b to the upstream side of the subsequent first compression stage 14a.

[0199] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0200] 10 Compressor unit 12 First compression stage 14 Subsequent Compression Stage 16 Crank mechanism 18a Spillback channel 18b Spillback valve 21 Suction passage 22 Intermediate flow path 23 Liquid hydrogen storage tank 24 Discharge flow path 41 Adjustment means 43a Second spillback channel 43b Second spillback valve 47 Intermediate pressure sensor (second pressure sensor) 48 Downstream temperature sensor (third temperature sensor) 49 Discharge channel pressure sensor (pressure sensor) 50 control section 53 Low-pressure gas exhaust 54 Check valve 61 Suction valve unloader 61b Suction valve unloader 64b Stepless capacity adjustment device 71 Preheater 83 Second low-pressure gas discharge channel (other low-pressure gas discharge channel) CV1 Demand switching method CV2 Second demand switching method D1 High voltage demand destination D2 Low-voltage demand destination D3 Second low-pressure demand destination (other low-pressure demand destination) FCV1 Flow rate adjustment means SB1 spillback section SB2 Second spillback section P B Branching point P B2 Second Branch (Another Branch)

Claims

1. A reciprocating compressor unit that recovers boil-off hydrogen gas from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a high-pressure demand destination (D1) including at least one of an engine, a power generation facility, or a boiler, a plurality of compression stages for compressing hydrogen gas drawn in through an intake passage; a crank mechanism that drives the plurality of compression stages; A spillback section (SB1) including a spillback flow path that returns hydrogen gas discharged into the discharge flow path on the discharge side of the plurality of compression stages or hydrogen gas flowing through an intermediate flow path between the plurality of compression stages to the suction flow path, and a spillback valve that adjusts the amount of spillback in the spillback flow path; a low-pressure gas discharge path that branches off from a branch point provided in the intermediate flow path or the discharge flow path and is capable of discharging hydrogen gas to a low-pressure demand destination (D2) that can process hydrogen gas at a pressure lower than that of hydrogen gas required by the high-pressure demand destination (D1); a demand destination switching means (CV1) provided in the low-pressure gas discharge path or the branch point; a check valve located downstream of the branch point; a first temperature sensor disposed upstream of the branch point in the intermediate flow path or the discharge flow path; a second temperature sensor disposed in the intake passage between a connection portion of the spillback passage and a first compression stage that is a frontmost stage of the plurality of compression stages; A control unit that controls the demand destination switching means (CV1) and the spillback valve; Equipped with The control unit When the temperature TS1 acquired by the first temperature sensor is equal to or higher than a predetermined first temperature threshold T1 greater than 0°C during startup, the demand destination switching means (CV1) is controlled to enter a first switching state in which hydrogen gas is circulated through the low-pressure gas discharge path; When the temperature TS1 acquired by the first temperature sensor becomes less than the first temperature threshold T1, the demand destination switching means (CV1) is controlled to enter a second switching state in which hydrogen gas is sent to the discharge flow path toward the high-pressure demand destination (D1); When the demand destination switching means (CV1) is in the second switching state, the suction temperature TS2 acquired by the second temperature sensor is referenced, and the spillback valve is controlled so that the suction temperature TS2 is within a predetermined temperature range; 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 check valve is provided in the discharge flow path, The compressor unit according to claim 1 , wherein the branch point is provided in the discharge flow path at a position upstream of the check valve.

3. a preheater capable of heat exchange between the hydrogen gas before being drawn into the first compression stage and the hydrogen gas after being discharged into the discharge flow path; a third temperature sensor disposed downstream of the preheater in the discharge flow path; a flow rate adjusting means (FCV1) capable of adjusting the inflow state of hydrogen gas into the preheater; Furthermore, The control unit When the demand destination switching means (CV1) is in the second switching state, increasing the amount of hydrogen gas flowing into the preheater so that heating of the hydrogen gas in the suction flow path by the preheater can be given priority over heating by the spillback section (SB1); and controlling the flow rate adjustment means (FCV1) so that the temperature TS3 downstream of the preheater acquired by the third temperature sensor does not become equal to or lower than a threshold value; 3. The compressor unit according to claim 2, wherein, when the suction temperature TS2 is lower than the predetermined temperature range, the flow rate control means (FCV1) and the spillback valve are controlled so that the suction temperature TS2 is within the predetermined temperature range.

4. a preheater capable of heat exchange between the hydrogen gas before being drawn into the first compression stage and the hydrogen gas flowing through the intermediate flow passage; a third temperature sensor disposed downstream of the preheater in the intermediate flow path; a flow rate adjusting means (FCV1) capable of adjusting the inflow state of hydrogen gas into the preheater; Furthermore, The control unit When the demand destination switching means (CV1) is in the second switching state, an inflow rate of hydrogen gas to the preheater is increased so that heating of the hydrogen gas in the suction flow path by the preheater can be given priority over heating by the spillback section (SB1), and the flow rate adjustment means (FCV1) is controlled so that the temperature TS3 downstream of the preheater acquired by the third temperature sensor does not become equal to or lower than a threshold value; 3. The compressor unit according to claim 2, wherein, when the suction temperature TS2 is lower than the predetermined temperature range, the flow rate control means (FCV1) and the spillback valve are controlled so that the suction temperature TS2 falls within the predetermined temperature range.

5. The check valve is provided in the discharge flow path, the branch point is provided upstream of the check valve in the discharge flow path, The compressor unit comprises: another low-pressure gas discharge path that branches off from another branch point provided in the intermediate flow path and is capable of discharging hydrogen gas to another low-pressure demand destination (D3) that can process hydrogen gas at a pressure lower than the hydrogen gas pressure required by the high-pressure demand destination (D1); a second demand destination switching means (CV2) provided in the other low-pressure gas discharge path or the other branch point; Furthermore, The control unit When the demand destination switching means (CV1) is in the first switching state, the second demand destination switching means (CV2) is controlled to cause the hydrogen gas in the intermediate flow path to flow through the other low-pressure gas discharge path; 2. The compressor unit according to claim 1, wherein when the demand destination switching means (CV1) is in the second switching state, the second demand destination switching means (CV2) is controlled so as to send hydrogen gas to the discharge flow path toward the high-pressure demand destination (D1).

6. The check valve is provided in the discharge flow path, the branch point is provided at a position upstream of the check valve in the discharge flow path, The compressor unit comprises: another low-pressure gas discharge path that branches off from another branch point in the intermediate flow path and is capable of discharging hydrogen gas to another low-pressure demand destination (D3) that can process hydrogen gas at a pressure lower than the hydrogen gas pressure required by the high-pressure demand destination (D1); a second demand destination switching means (CV2) provided in the other low-pressure gas discharge path or the other branch point; an adjusting means for adjusting the amount of hydrogen gas processed by subsequent compression stages other than the first compression stage among the plurality of compression stages; Furthermore, The control unit When the demand destination switching means (CV1) is in the second switching state, 2. The compressor unit according to claim 1, wherein the second demand destination switching means (CV2) is controlled so that hydrogen gas is discharged to the other low-pressure gas discharge path in accordance with fluctuations in the demand amount of the other low-pressure demand destination (D3) or the demand amount of the high-pressure demand destination (D1), while the adjustment means is controlled so that the throughput of the subsequent compression stage is adjusted.

7. In the case where the spillback portion (SB1) returns the hydrogen gas discharged into the discharge flow path to the suction flow path, The adjusting means is A second spillback flow path that returns hydrogen gas from the upstream side of the branching portion on the discharge flow path where the spillback flow path branches to the suction side of the subsequent compression stage, and a second spillback section (SB2) including a second spillback valve that adjusts the amount of spillback in the second spillback flow path, The control unit 7. The compressor unit according to claim 6, wherein when the demand destination switching means (CV1) is in the second switching state, the second spillback valve is controlled so that a flow rate corresponding to the fluctuation in the demand amount of the other low-pressure demand destination (D3) or the high-pressure demand destination (D1) is returned to the suction side of the subsequent compression stage.

8. When the spillback section (SB1) returns the hydrogen gas flowing through the intermediate flow path to the suction flow path, The adjusting means is A second spillback flow path that returns hydrogen gas discharged from a compression stage located downstream of a branching portion on the intermediate flow path where the spillback flow path branches to the upstream side of the compression stage, and a second spillback section (SB2) including a second spillback valve that adjusts the amount of spillback in the second spillback flow path, The control unit 7. The compressor unit according to claim 6, wherein when the demand destination switching means (CV1) is in the second switching state, the second spillback valve is controlled so that a flow rate corresponding to a return amount of the spillback section (SB1) is returned to a side upstream of the compression stage.

9. The adjusting means is an on-off type suction valve unloader attached to a cylinder portion of the subsequent compression stage; The control unit 7. The compressor unit according to claim 6, wherein when the demand destination switching means (CV1) is in the second switching state, the suction valve unloader is controlled so that a flow rate corresponding to the fluctuation in the demand amount of the other low-pressure demand destination (D3) or the high-pressure demand destination (D1) is returned to the suction side of the subsequent compression stage.

10. The adjusting means is a suction valve unloader attached to a cylinder portion of the subsequent compression stage; a hydraulic or electric drive device for opening and closing the suction valve unloader; A stepless capacity adjusting device consisting of The control unit 7. The compressor unit according to claim 6, wherein when the demand destination switching means (CV1) is in the second switching state, the throughput of the subsequent compression stage is adjusted by controlling the timing at which the suction valve unloader operates in conjunction with rotational movement of a crankshaft so that hydrogen gas drawn from inside the cylinder section to the suction side is returned in accordance with a flow rate corresponding to the requested amount of the other low-pressure demand destination (D3) or the requested amount of the high-pressure demand destination (D1).

11. A reciprocating compressor unit that recovers boil-off hydrogen gas from a liquid hydrogen storage tank and supplies at least a portion of the recovered hydrogen gas to a high-pressure demand destination (D1) including at least one of an engine, a power generation facility, or a boiler, a plurality of compression stages for compressing hydrogen gas drawn in through an intake passage; a crank mechanism that drives the plurality of compression stages; A spillback section (SB1) including a spillback flow path that returns hydrogen gas discharged into the discharge flow path on the discharge side of the plurality of compression stages or hydrogen gas flowing through an intermediate flow path between the plurality of compression stages to the suction flow path, and a spillback valve that adjusts the amount of spillback in the spillback flow path; a low-pressure gas discharge path that branches off from a branch point provided in the intermediate flow path and is capable of discharging hydrogen gas to a low-pressure demand destination (D2) that can process hydrogen gas at a pressure lower than that of hydrogen gas required by the high-pressure demand destination (D1); a demand destination switching means (CV1) provided in the low-pressure gas discharge path or the branch point; a check valve provided downstream of the branch point in the intermediate flow path; a first temperature sensor disposed upstream of the branch point in the intermediate flow path; a second temperature sensor disposed in the intake passage between a connection portion of the spillback passage and a first compression stage located at the front end of the plurality of compression stages; a pressure sensor provided in the low-pressure gas discharge path; A control unit that controls the demand destination switching means (CV1) and the spillback valve; Equipped with The control unit When the temperature TS1 acquired by the first temperature sensor is equal to or greater than a predetermined first temperature threshold T1 greater than 0°C during startup, the demand destination switching means (CV1) is controlled to enter a first switching state in which hydrogen gas discharged from the first compression stage is circulated through the low-pressure gas discharge path; When the temperature TS1 acquired by the first temperature sensor becomes less than the first temperature threshold T1, the demand destination switching means (CV1) is controlled to enter a third switching state in which hydrogen gas is circulated through both the low-pressure gas discharge path and the intermediate flow path downstream of the branch point; When the demand destination switching means (CV1) is in the third switching state, the demand destination switching means (CV1) is controlled so that the pressure PS2 acquired by the pressure sensor is within a predetermined range, and the spillback valve is controlled by referring to the suction temperature TS2 acquired by the second temperature sensor so that the suction temperature TS2 is within a predetermined temperature range, 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.

12. an adjusting means for adjusting the amount of hydrogen gas processed by subsequent compression stages other than the first compression stage among the plurality of compression stages; a second pressure sensor provided in the intermediate flow path between the first compression stage and the subsequent compression stage; Furthermore, 12. The compressor unit according to claim 11, wherein when the demand destination switching means (CV1) is in the third switching state, the control unit controls the adjustment means so that the throughput of the subsequent compression stage is adjusted in accordance with the amount of change in pressure PS1 in the intermediate flow path acquired by the second pressure sensor.

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