Compressor unit

Abstract

The compressor unit comprises: a compression unit comprising a reciprocating compression mechanism that compresses hydrogen gas; a cooler; a preheater; a backflow part; an adjustment unit; and a control unit. The suction flow path is provided with: a first path part that passes through the preheater; and a second path section that does not pass through the preheater. The adjustment means adjusts the flow rate of the hydrogen gas flowing through the first path section and adjusts the flow rate of the hydrogen gas flowing through the second path section. The control unit controls the adjustment means such that the suction temperature of the compression unit is within a predetermined temperature range. The predetermined temperature range is higher than a reference temperature based on the liquefaction temperature of the air.

Description

Technical Field

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

[0002] In the past, low-temperature boil-off gas (BOG) from liquefied natural gas (LNG) and liquefied hydrogen (LH2) was recovered by compressors and supplied to demanding parties such as engines. In particular, boil-off gas generated by LH2 is extremely low in temperature. Therefore, if the boil-off gas is directly sucked in by the compressor, it will be subject to the following restrictions: materials suitable for extremely low temperatures must be selected, design conditions that take into account thermal deformation must be adopted, or strict insulation treatment must be implemented.

[0003] In addition, the following patent document 1 points out the following problem. "In recent years, hydrogen has attracted much attention as a new energy source. When hydrogen is used as an energy source, it is expected to be in a liquefied state like natural gas during storage and transportation. However, hydrogen has the characteristic that its liquefaction temperature is lower than that of air. Therefore, if equipment such as reciprocating compressors for natural gas, etc. is directly applied to hydrogen, it is possible that adverse conditions will occur due to extremely low temperature liquefied hydrogen. For example, liquefied air will be generated around the device that supplies liquefied hydrogen."

[0004] That is, Patent Document 1 discusses the problem of preventing adverse conditions caused by extremely low temperature liquefied hydrogen. In addition, in a device for supplying extremely low temperature fluid, a device that is easy to implement high-performance thermal insulation on piping, etc. (such as a device with a vacuum area), but there is also the following problem: it is very difficult to implement high-performance thermal insulation, such as machinery accompanied by vibration during operation or equipment that must be regularly maintained through an inspection opening (such as a reciprocating compressor, etc.).

[0005] It is known that a heat exchanger capable of heating the evaporated gas before being sucked into the compressor is provided as disclosed in the following patent documents 2 to 4. On the other hand, if the intake gas is overheated, the compression power will increase due to the expansion of the gas volume and cause power (energy) loss, so it is required to control the intake temperature within an appropriate range.

[0006] like Fig.12As shown, in the compressor unit disclosed in the following patent document 2, a heat exchanger 104 is provided for heating the evaporated gas before being sucked into the compressor unit 102 by using the evaporated gas discharged from the compressor unit 102. In this compressor unit, the flow rate flowing in the heat exchanger 104 can be changed according to the gas processing amount. However, since a structure is adopted in which the total amount of evaporated gas extracted from the tank 100 flows into the heat exchanger 104, this is only to change the flow rate in the heat exchanger 104 according to the gas processing amount in the compressor unit 102. Therefore, it is impossible to adjust the flow rate flowing in the heat exchanger 104 in such a way that the temperature of the gas sucked into the compressor unit 102 becomes a specified temperature.

[0007] In this regard, in the compressor unit disclosed in the following patent document 3, Fig.13 As shown, a bypass pipe 114 is provided that bypasses the heat exchanger 112. By opening and closing a valve 114a provided in the bypass pipe 114, the amount of gas passing through the heat exchanger 112 can be adjusted. Therefore, by opening and closing the valve 114a, it may be possible to adjust the temperature of the evaporated gas sucked into the compression section 116. However, in the compressor unit of Patent Document 3, even when the valve 114a is in a fully opened state, the evaporated gas may flow into the heat exchanger 112 due to the pressure loss of the valve 114a itself. Therefore, it is difficult to control the temperature of the gas sucked into the compression section 116 to be within an appropriate range.

[0008] In addition, if Fig.14 As shown, in the following patent document 4, a heat exchanger 123 is also shown for performing heat exchange between the evaporated gas before being sucked into the compression section 121 and the evaporated gas after being discharged from the compression section 121. However, the heat exchanger 123 is a heat exchanger for reliquefying the evaporated gas compressed by the compression section 121. Therefore, the evaporated gas cooled by the cooler 125 arranged downstream of the compression section 121 is introduced into the heat exchanger 123. Therefore, in patent document 4, it is disadvantageous from the point of view of sufficiently warming the evaporated gas sucked into the compression section 121. Moreover, in patent document 4, since it is difficult for the temperature of the gas sucked into the compression section 121 to be too high as in patent document 3, it does not consider adjusting the temperature of the evaporated gas sucked into the compression section 121.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent document 1: Japanese Patent Publication No. 2020-172870

[0012] Patent Document 2: Japanese Patent Publication No. 2001-65795

[0013] Patent Document 3: Japanese Patent Publication No. 3-92700

[0014] Patent Document 4: Japanese Patent Publication No. 2019-27590 Summary of the invention

[0015] An object of the present invention is to appropriately manage the temperature of hydrogen gas, which is boil-off gas sucked into a reciprocating compressor unit, in a compressor unit.

[0016] A compressor unit according to one aspect of the present invention recovers boil-off gas, i.e., hydrogen, from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand side including at least one of an engine, a power generation device, and a boiler, and includes: a compression unit composed of a reciprocating compression mechanism, which compresses the hydrogen flowing in the suction flow channel and discharges the compressed hydrogen to the discharge flow channel; a water-cooled or air-cooled cooler, which cools the hydrogen discharged to the discharge flow channel; a preheater, which can heat-exchange the hydrogen before being sucked into the compression unit with the hydrogen discharged from the compression unit, i.e., the hydrogen flowing toward the cooler; and a reflux unit, which includes a reflux flow channel for returning the hydrogen discharged from the compression unit to a portion of the suction flow channel located downstream or upstream of the preheater. The discharge flow channel or the suction flow channel has a first path portion and a second path portion that are divided into two branches along the flow direction of the hydrogen and then merge with each other, the first path portion passes through the preheater, and on the other hand, the second path portion does not pass through the preheater. The compressor unit further includes: an adjustment unit that adjusts the flow rate of hydrogen gas flowing through the first path portion and adjusts the flow rate of hydrogen gas flowing through the second path portion; and a control unit that controls the adjustment unit so that the temperature of hydrogen gas sucked into the compression unit, that is, the suction temperature, is within a predetermined temperature range. The predetermined temperature range is higher than a reference temperature based on the liquefaction temperature of air. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram schematically showing the configuration of a compressor unit according to the first embodiment.

[0018] Figure 2 It is a diagram schematically showing the configuration of a compressor unit according to the first embodiment.

[0019] Figure 3 This is a diagram schematically showing the configuration of a compressor unit according to a modified example of the first embodiment.

[0020] Figure 4 It is a diagram for explaining the control operation of the control unit in the compressor unit according to the first embodiment.

[0021] Figure 5 This is a diagram schematically showing the configuration of a compressor unit according to a modified example of the first embodiment.

[0022] Figure 6 It is a diagram for explaining the control operation of the control unit in the compressor unit according to the modification of the first embodiment.

[0023] Figure 7 This is a diagram schematically showing the configuration of a compressor unit according to a modified example of the first embodiment.

[0024] Figure 8 This is a diagram schematically showing the configuration of a compressor unit according to the second embodiment.

[0025] Fig. 9 This is a diagram schematically showing the configuration of a compressor unit according to a third embodiment.

[0026] Fig.10 It is a diagram schematically showing the structure of a compressor unit according to a fourth embodiment.

[0027] Fig.11 It is a diagram schematically showing the configuration of a compressor unit according to the fifth embodiment.

[0028] Fig.12 This is a diagram schematically showing a conventional compressor unit.

[0029] Fig.13 This is a diagram schematically showing a conventional compressor unit.

[0030] Fig.14 This is a diagram schematically showing a conventional compressor unit. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments will be described with reference to the drawings.

[0032] (First embodiment)

[0033] The compressor unit involved in this embodiment is configured to recover the flammable boil-off gas, i.e., hydrogen, below 0°C from the liquefied hydrogen storage tank, and compress and supply the recovered hydrogen to the demand side. The boil-off gas, i.e., hydrogen, is about -250°C. The demand side includes power generation equipment, boilers, and engines of ships, etc.

[0034] like Figure 1 As shown, the compressor unit 10 includes: a compressor 12 for compressing hydrogen; a cooler 14 for cooling the hydrogen compressed by the compressor 12; and a preheater 16 for heating the hydrogen before being sucked into the compressor 12.

[0035] The compressor 12 is connected to the liquefied hydrogen storage tank 23 through the suction passage 21. Therefore, the boil-off gas of the liquefied gas generated in the liquefied hydrogen storage tank 23 is sucked into the compressor 12 through the suction passage 21. The compressor 12 is composed of a reciprocating compression mechanism. Figure 2 As shown, the compression section 12 has a cylinder 211, a piston 212, a piston connecting rod 213, a pair of suction valves 214, and a pair of discharge valves 215. The piston 212 and the piston connecting rod 213 are connected to a crank mechanism (not shown). The piston 212 moves back and forth in the cylinder 211, and the hydrogen is compressed in the compression chamber. Figure 2 , a double-acting structure of the compression section 12 is shown, but the compression section 12 may also be a single-acting structure.

[0036] In addition, Figure 1 In the figure, the compression part 12 is shown as a trapezoid for convenience, but the compression part 12 is not necessarily a single-stage type, and it can also be composed of multiple compression stages. That is, the compression part 12 can adopt a structure in which the hydrogen gas is compressed sequentially by pistons 212 in multiple cylinders 211 connected in series to increase the pressure. This is also the same in other embodiments described later.

[0037] The suction flow path 21 is provided with a heat insulating material 26 for suppressing heat input from the outside air. The heat insulating material 26 may be omitted. In addition, a heat insulating material (not shown) may be provided in the discharge flow path 25 through which the hydrogen gas discharged from the compression unit 12 flows.

[0038] The cooler 14 is disposed in the discharge flow passage 25. The cooler 14 may be water-cooled or air-cooled. The hydrogen gas cooled by the cooler 14 is sent to the demand side 28.

[0039] The preheater 16 is configured to heat the hydrogen before being sucked into the compression section 12 by exchanging heat with the hydrogen after being discharged from the compression section 12. The preheater 16 is connected to a portion of the discharge flow passage 25 that is located upstream of the cooler 14. In the preheater 16, the hydrogen flowing in the suction flow passage 21 toward the compression section 12 is heated by the hydrogen flowing to the cooler 14. Therefore, unlike the configuration in which the hydrogen is heated by the hydrogen cooled by the cooler 14, the hydrogen can be heated efficiently.

[0040] The preheater 16 is connected to the first path portion 29a in the discharge flow passage 25. That is, the discharge flow passage 25 includes: an upstream path portion 29b; a first path portion 29a and a second path portion 29c that are bifurcated from the upstream path portion 29b and then merged with each other; and a downstream path portion 29d that allows the hydrogen gas merged from the first path portion 29a and the second path portion 29c to flow. The upstream path portion 29b is connected to the compression portion 12. The downstream path portion 29d extends to the demand end 28.

[0041] Since the first path portion 29a passes through the preheater 16, at least a portion of the hydrogen gas discharged from the compressor 12 can flow into the preheater 16. Since the preheater 16 is also connected to the suction flow path 21, the hydrogen gas flowing in the suction flow path 21 can be heated based on the hydrogen gas flowing in the first path portion 29a. On the other hand, the second path portion 29c does not pass through the preheater 16.

[0042] The cooler 14 is connected to the downstream path portion 29d. That is, in the discharge flow path 25, the cooler 14 is arranged on the downstream side with respect to the preheater 16. Therefore, the preheater 16 heats the hydrogen gas flowing in the intake flow path 21 based on the hydrogen gas before being cooled by the cooler 14.

[0043] The discharge flow path 25 is provided with a regulating unit 31 for regulating the flow rate of the hydrogen gas flowing through the first path portion 29a and regulating the flow rate of the hydrogen gas flowing through the second path portion 29c. Figure 1 In the example shown, the adjustment unit 31 has a three-way valve 31a provided at a branch point between the first path portion 29a and the second path portion 29c. The three-way valve 31a is configured to distribute the hydrogen gas flowing in the upstream path portion 29b to the first path portion 29a and the second path portion 29c. Therefore, by changing the direction or position of the valve body (not shown) of the three-way valve 31a, the three-way valve 31a can change the distribution ratio between the first path portion 29a and the second path portion 29c from a state where the total amount of the flow flowing in the upstream path portion 29b flows to the first path portion 29a (the valve on the second path portion 29c side is closed) to a state where the total amount of the flow flowing in the upstream path portion 29b flows to the second path portion 29c (the valves on the first path portion 29a side and the preheater 16 side are closed).

[0044] In addition, Figure 1 In the structure, the three-way valve 31a is arranged at the position connecting the upstream path portion 29b, the first path portion 29a and the second path portion 29c. Alternatively, the three-way valve 31a can be arranged at the position connecting the first path portion 29a, the second path portion 29c and the downstream path portion 29d.

[0045] The compressor unit 10 is provided with a reflux section 33 for returning the hydrogen gas discharged from the compression section 12 to the intake flow passage 21. The reflux section 33 includes a reflux flow passage 33a and a reflux valve 33b which is arranged in the reflux flow passage 33a and has a valve capable of adjusting the opening. One end of the reflux flow passage 33a is connected to a portion of the discharge flow passage 25 which is located downstream relative to the cooler 14, and the other end is connected to a portion of the intake flow passage 21 which is located downstream relative to the preheater 16. That is, the hydrogen gas flowing in the reflux flow passage 33a merges with the hydrogen gas that has passed through the preheater 16 between the preheater 16 and the compression section 12 in the intake flow passage 21. The portion of the reflux flow passage 33a which is located downstream relative to the reflux valve 33b is provided with an insulating material 34 for suppressing heat input from the outside air. However, the insulating material 34 can be omitted. In addition, as Figure 3 As shown, the other end of the return flow passage 33 a may be connected to a portion of the suction flow passage 21 located upstream of the preheater 16 .

[0046] The discharge flow path 25 is provided with a pressure sensor 36 for detecting the pressure of the hydrogen gas flowing in the discharge flow path 25. The pressure sensor 36 is located downstream of a connection portion of the discharge flow path 25 with respect to the return flow path 33a.

[0047] The suction flow passage 21 is provided with a temperature sensor 37 for detecting the temperature of the hydrogen gas flowing in the suction flow passage 21. The temperature sensor 37 is arranged between the connection portion of the return flow passage 33a and the compression portion 12 in the suction flow passage 21. Therefore, the temperature sensor 37 can obtain the temperature of the hydrogen gas heated by the preheater 16 (when the hydrogen gas flows in the return flow passage 33a, it is the hydrogen gas after merging with the hydrogen gas from the return flow passage 33a).

[0048] The pressure sensor 36 outputs a signal indicating the detected pressure, and the temperature sensor 37 outputs a signal indicating the acquired temperature. The signal from the pressure sensor 36 and the signal from the temperature sensor 37 are input to the controller 39. The controller 39 is a computer that controls various actions of the compressor unit 10. The functions of the controller 39 executed by the computer include: a control unit 39a and a reflux control unit 39b. The control unit 39a is a functional unit configured to control the adjustment unit 31 while referring to the temperature acquired by the temperature sensor 37 as the temperature of the hydrogen gas sucked into the compression unit 12, that is, the suction temperature. The reflux control unit 39b is a functional unit configured to control the reflux valve 33b based on the detected pressure of the pressure sensor 36.

[0049] Here, refer to Figure 4The control operation by the control unit 39a will be described. The control unit 39a first determines whether the intake temperature (temperature T) is equal to or lower than a predetermined target temperature T1 (step ST13). The target temperature T1 is set to a temperature higher than a reference temperature described later.

[0050] When the suction temperature (temperature T) is lower than the target temperature T1, the control unit 39a controls the adjustment unit 31 in such a manner that the flow rate bypassing the preheater 16 is reduced and the flow rate flowing to the preheater 16 is increased (step ST14). That is, the three-way valve 31a as the adjustment unit 31 is controlled in such a manner that the opening degree on the second path portion 29c side is reduced and the opening degree on the first path portion 29a side is increased. As a result, in the preheater 16, the heating amount of the hydrogen gas flowing in the suction flow path 21 is increased, and therefore the suction temperature (temperature T) is increased.

[0051] On the other hand, when the suction temperature (temperature T) is higher than the target temperature T1, the control unit 39a controls the adjustment unit 31 in such a manner that the flow rate bypassing the preheater 16 is increased and the flow rate flowing to the preheater 16 is reduced (step ST15). That is, the three-way valve 31a as the adjustment unit 31 is controlled in such a manner that the opening degree on the second path portion 29c side is increased and the opening degree on the first path portion 29a side is reduced. As a result, in the preheater 16, the heating amount of the hydrogen gas flowing in the suction flow channel 21 is reduced, and therefore the suction temperature (temperature T) is reduced. That is, the control unit 39a controls the adjustment unit 31 in such a manner that the suction temperature is within a predetermined temperature range. This temperature range is higher than the specified reference temperature.

[0052] The reference temperature is set according to the liquefaction temperature of the air. Specifically, the reference temperature is preferably the liquefaction temperature of the air. However, if the outer surface of the component (cylinder 211, etc.) in the compression section 12 that contacts the external air is higher than the liquefaction temperature of the air, the reference temperature may be set to be lower than the liquefaction temperature of the air. In addition, the reference temperature may be set in such a way that the temperature of the outer surface of the piping and / or instrument equipment of the intake flow channel 21 is higher than the liquefaction temperature of the air. Thus, even if the air around the compression section 12 and / or the intake flow channel 21 is cooled due to the cold energy of the hydrogen, the air can be prevented from liquefying.

[0053] The reflux control unit 39b controls the reflux valve 33b in such a way that the detection pressure of the pressure sensor 36 becomes a predetermined set pressure. That is, when the detection pressure of the pressure sensor 36 is higher than the set pressure, the reflux valve 33b is controlled in such a way that the opening of the reflux valve 33b is increased. As a result, the flow rate of hydrogen returned to the suction flow passage 21 among the hydrogen passing through the cooler 14 increases, and therefore, the pressure of the hydrogen supplied to the demand end 28 decreases. On the other hand, when the detection pressure is lower than the set pressure, the reflux valve 33b is controlled in such a way that the opening of the reflux valve 33b is reduced. As a result, the flow rate of hydrogen returned to the suction flow passage 21 among the hydrogen passing through the cooler 14 decreases, and therefore, the pressure of the hydrogen supplied to the demand end 28 increases. In addition, when the detection pressure is consistent with the set pressure, the opening of the reflux valve 33b does not change.

[0054] As described above, in the present embodiment, the flow rate of hydrogen passing through the preheater 16 is adjusted by the adjustment unit 31, and the flow rate of hydrogen not passing through the preheater 16 is also adjusted. In addition, the adjustment unit 31 is controlled in such a way that the temperature of the hydrogen gas sucked into the compressor 12 is within a specified temperature range. Therefore, the suction temperature of the compressor 12 can be properly managed. Moreover, by utilizing the heat of the hydrogen gas (exhaust gas) before flowing into the cooler 14, the suction temperature can be properly heated. In addition, since the connection portion of the reflux flow channel 33a connected to the suction flow channel 21 is located upstream relative to the temperature sensor 37, even if the detected gas temperature of the temperature sensor 37 changes due to the return of hydrogen to the suction flow channel 21 based on the reflux portion 33, the temperature of the hydrogen gas sucked into the compressor 12 can be within an appropriate range. Moreover, since the temperature of the hydrogen gas sucked into the compressor 12 can be made higher than the above-mentioned reference temperature, the liquefaction of oxygen as a combustion-aiding gas can be avoided.

[0055] In addition, in the present embodiment, the adjustment unit 31 includes the three-way valve 31a. Therefore, the flow rate of the hydrogen gas to the preheater 16 and the flow rate of the hydrogen gas not passing through the preheater 16 can be adjusted separately by one valve, which contributes to the simplification of the structure.

[0056] Furthermore, in the present embodiment, since the suction flow path 21 is provided with the heat insulating material 26 , it is possible to suppress unexpected heat input to the suction flow path 21 , thereby enabling more appropriate suction temperature control.

[0057] exist Figure 1 2 shows an example in which the adjustment unit 31 includes a three-way valve 31a, but the present invention is not limited to this. Figure 5 As shown, the adjustment unit 31 may include: a first valve 31 b provided in the first path portion 29 a and capable of adjusting the opening degree; and a second valve 31 c provided in the second path portion 29 c and capable of adjusting the opening degree.

[0058] Here, refer to Figure 6 To illustrate Figure 5 The control operation of the control unit 39a in the modified example shown in the figure. The operation of the reflux control unit 39b is also the same as that of the first embodiment, and the details thereof are omitted.

[0059] The control unit 39a determines whether the intake temperature (temperature T) obtained by the temperature sensor 37 is above the predetermined upper limit temperature T2 (step ST11). When the intake temperature (temperature T) is above the upper limit temperature T2, the control unit 39a controls the adjustment unit 31 to stop the flow of hydrogen in the first path portion 29a (step ST12). In this case, the first valve 31b is closed and the second valve 31c is fully opened. As a result, the flow of hydrogen discharged from the compression section 12 into the preheater 16 is stopped. Therefore, the hydrogen flowing in the intake flow channel 21 is not heated by the preheater 16 and is sucked into the compression section 12. Therefore, it is possible to prevent the temperature (intake temperature) of the hydrogen sucked into the compression section 12 from becoming too high.

[0060] On the other hand, when the suction temperature (temperature T) is lower than the upper limit temperature T2, Figure 4 Similarly, the control unit 39a determines whether the intake temperature (temperature T) is lower than the predetermined target temperature T1 (step ST13). At this time, the adjustment unit 31 is opened at least on the first path portion 29a side, so that at least a part of the hydrogen gas discharged from the compression unit 12 is introduced into the preheater 16. The target temperature T1 is a temperature lower than the upper limit temperature T2.

[0061] When the suction temperature (temperature T) is lower than the target temperature T1, the control unit 39a controls the adjustment unit 31 so as to reduce the flow rate bypassing the preheater 16 and increase the flow rate flowing to the preheater 16 (step ST14). That is, the second valve 31c is controlled so as to reduce the opening degree of the second valve 31c and the first valve 31b is controlled so as to increase the opening degree of the first valve 31b. As a result, the gas flow rate passing through the preheater 16 in the exhaust gas is increased and the gas flow rate bypassing the preheater 16 is reduced.

[0062] On the other hand, when the suction temperature (temperature T) is higher than the target temperature T1, the control unit 39a controls the adjustment unit 31 in such a manner that the flow rate bypassing the preheater 16 is increased and the flow rate flowing to the preheater 16 is reduced (step ST15). That is, the second valve 31c is controlled in such a manner that the opening of the second valve 31c is increased, and the first valve 31b is controlled in such a manner that the opening of the first valve 31b is reduced. As a result, the gas flow rate passing through the preheater 16 in the exhaust gas is reduced and the gas flow rate bypassing the preheater 16 is increased. That is, the flow of hydrogen discharged from the compressor 12 to the preheater 16 is adjusted so that the suction temperature is within a predetermined temperature range.

[0063] In addition, Figure 5 In the structure shown in the figure, the control operation of the control unit 39a can also be based on Figure 4 to be carried out (i.e., Figure 6 In the example, steps ST11 and ST12 may be omitted. Figure 1 In the configuration, the above-mentioned steps ST11 and ST12 can also be executed.

[0064] like Figure 7 As shown, the adjustment unit 31 may include: a valve 31d provided in the first path portion 29a and capable of adjusting the opening; and a throttle portion 31e provided in the second path portion 29c. The throttle portion 31e suppresses the flow rate of hydrogen gas flowing in the second path portion 29c. Therefore, when the valve 31d is fully opened, the approximate total amount of hydrogen gas discharged from the compression portion 12 flows in the first path portion 29a. On the other hand, when the valve 31d is closed, the total amount of hydrogen gas discharged from the compression portion 12 flows in the second path portion 29c.

[0065] In the case of this configuration, the control unit 39a performs Figure 6 The same control action. Figure 6 In step ST12, the valve 31d of the first path portion 29a is closed. As a result, the flow of hydrogen discharged from the compression section 12 into the preheater 16 is stopped. Furthermore, in step ST14, the valve 31d is controlled in such a manner that the opening of the valve 31d is increased. As a result, the gas flow through the preheater 16 is increased and the gas flow through the throttling section 31e is reduced. Furthermore, in step ST15, the valve 31d is controlled in such a manner that the opening of the valve 31d is reduced. As a result, the gas flow through the preheater 16 is reduced and the gas flow through the throttling section 31e is increased. That is, the flow of hydrogen discharged from the compression section 12 into the preheater 16 is adjusted so that the intake temperature is within a predetermined temperature range. Furthermore, in Figure 7 In the structure shown, the control unit 39a can be Figure 4 Same control action.

[0066] (Second embodiment)

[0067] Figure 8 Here, the same components as those of the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

[0068] In the first embodiment, the exhaust flow passage 25 has the first path portion 29a and the second path portion 29c, whereas in the second embodiment, the suction flow passage 21 has the first path portion 29a and the second path portion 29c. That is, the suction flow passage 21 has: an upstream path portion 29b; the first path portion 29a and the second path portion 29c that are bifurcated from the upstream path portion 29b and then merged with each other; and a downstream path portion 29d that allows the hydrogen gas merged from the first path portion 29a and the second path portion 29c to flow.

[0069] The upstream path portion 29b is connected to the liquefied hydrogen storage tank 23. The downstream path portion 29d is connected to the compression unit 12. The first path portion 29a passes through the preheater 16, and the second path portion 29c bypasses the preheater 16.

[0070] One end of the return flow passage 33a is connected to a portion of the discharge flow passage 25 located downstream of the cooler 14, and the other end is connected to a portion of the suction flow passage 21 located downstream of the preheater 16. That is, the other end of the return flow passage 33a is connected to the downstream path portion 29d in the suction flow passage 21.

[0071] The adjustment unit 31 includes: a first valve 31b provided in the first path portion 29a and capable of adjusting the opening; and a second valve 31c provided in the second path portion 29c and capable of adjusting the opening. In this case, when the suction temperature (temperature T) is higher than the upper limit temperature T2, Figure 6 In step ST12, the first valve 31b is closed and the second valve 31c is fully opened. As a result, the hydrogen gas from the liquefied hydrogen storage tank 23 to the compressor 12 does not flow into the preheater 16. Therefore, the hydrogen gas is not heated by the preheater 16 before flowing into the compressor 12.

[0072] In addition, when the suction temperature (temperature T) is lower than the target temperature T1, Figure 6In step ST14, the second valve 31c is controlled in such a manner that the opening of the second valve 31c is reduced, and the first valve 31b is controlled in such a manner that the opening of the first valve 31b is increased. As a result, the gas flow rate passing through the preheater 16 is increased and the gas flow rate bypassing the preheater 16 is reduced. In addition, in step ST15 when the intake temperature (temperature T) is higher than the target temperature T1, the second valve 31c is controlled in such a manner that the opening of the second valve 31c is increased, and the first valve 31b is controlled in such a manner that the opening of the first valve 31b is reduced. As a result, the gas flow rate passing through the preheater 16 is reduced, and the gas flow rate bypassing the preheater 16 is increased. That is, the inflow of hydrogen into the preheater 16 is adjusted in such a manner that the intake temperature is within a predetermined temperature range.

[0073] In addition, Figure 8 , an example is shown in which the adjustment unit 31 includes the first valve 31b and the second valve 31c, but the adjustment unit 31 may also include a three-way valve provided at the branch point between the first path portion 29a and the second path portion 29c. In addition, the adjustment unit 31 may also include: a valve provided in the first path portion 29a; and a throttle portion provided in the second path portion 29c.

[0074] Description of other configurations, functions, and effects is omitted, but the description of the first embodiment can be applied to the second embodiment.

[0075] (Third embodiment)

[0076] Fig. 9 Here, the same components as those of the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

[0077] The third embodiment further includes a second compressor 42 for compressing the hydrogen gas cooled by the cooler 14 and a second cooler 44 for cooling the hydrogen gas compressed by the second compressor 42 .

[0078] The cooler 14, the second compressor 42 and the second cooler 44 are provided in the discharge flow passage 25. The second compressor 42 is composed of a reciprocating compression mechanism. That is, the second compressor 42 has a cylinder, a piston, a piston connecting rod, a pair of suction valves, and a pair of discharge valves in the same manner as the compressor 12. Fig. 9 In FIG. 4 , the second compression section 42 is shown as a trapezoid for convenience. However, the second compression section 42 is not necessarily a single-stage type, and may be composed of a plurality of compression stages.

[0079] The second compressor 42 is driven by a crank mechanism common to the compressor 12. In other words, the second compressor 42 forms a single multi-stage reciprocating compressor together with the compressor 12. In addition, the second compressor 42 may be formed as a reciprocating compressor independent of the compressor 12.

[0080] The cooler 14 functions as an intermediate cooler for cooling the hydrogen gas sucked into the second compressor 42, and the second cooler 44 functions as an aftercooler for cooling the hydrogen gas discharged from the second compressor 42. The second cooler 44 may be water-cooled like the cooler 14, or air-cooled. The hydrogen gas cooled by the second cooler 44 is sent to the demand end 28.

[0081] The reflux section 33 includes a first reflux section 45 and a second reflux section 46. In addition, the reflux section 33 may be configured to include only the second reflux section 46. That is, the first reflux section 45 as an intermediate stage reflux section may be omitted.

[0082] The first recirculation section 45 includes: a first recirculation channel 45a; and a first recirculation valve 45b, which is composed of a valve arranged in the first recirculation channel 45a and capable of adjusting the opening. One end of the first recirculation channel 45a is connected to the portion between the cooler 14 and the second compression section 42 in the discharge channel 25, and the other end is connected to the portion of the suction channel 21 located downstream relative to the preheater 16. The portion of the first recirculation channel 45a located downstream relative to the first recirculation valve 45b is provided with an insulating material 48 for suppressing heat input from the outside air. However, the insulating material 48 can be omitted. In addition, the other end of the first recirculation channel 45a can be connected to the portion of the suction channel 21 located upstream relative to the preheater 16.

[0083] The second recirculation section 46 includes: a second recirculation channel 46a; and a second recirculation valve 46b, which is composed of a valve arranged in the second recirculation channel 46a and capable of adjusting the opening. One end of the second recirculation channel 46a is connected to a portion of the discharge channel 25 located on the downstream side relative to the second cooler 44, and the other end is connected to a portion of the suction channel 21 located on the downstream side relative to the preheater 16. The portion of the second recirculation channel 46a located on the downstream side relative to the second recirculation valve 46b is provided with an insulating material 49 for suppressing heat input from the outside air. However, the insulating material 49 can be omitted. In addition, the other end of the second recirculation channel 46a can be connected to a portion of the suction channel 21 located on the upstream side relative to the preheater 16.

[0084] The discharge flow path 25 is provided with a second pressure sensor 51 for detecting the pressure of the hydrogen gas after passing through the second cooler 44. The second pressure sensor 51 is located downstream of a connection portion of the discharge flow path 25 with the second recirculation flow path 46a.

[0085] The return control unit 39 b controls the first return valve 45 b based on the detection pressure of the pressure sensor 36 , and controls the second return valve 46 b based on the detection pressure of the second pressure sensor 51 .

[0086] Fig. 9 In the example shown in FIG. 1 , the adjustment unit 31 includes a three-way valve 31a, but the adjustment unit 31 may also be Figure 5 The case shown in FIG. 1 is similarly provided with: a first valve provided in the first path portion 29a and capable of adjusting the opening; and a second valve provided in the second path portion 29c and capable of adjusting the opening. Figure 7 The illustrated case is similarly provided with a valve provided in the first path portion 29a and capable of adjusting the opening degree, and a throttle portion provided in the second path portion 29c.

[0087] exist Fig. 9 In the example shown in FIG. 1 , the discharge flow path 25 includes the first path portion 29a and the second path portion 29c. However, the discharge flow path 25 may be replaced with the first path portion 29a and the second path portion 29c. Figure 8 In the illustrated case, the suction flow path 21 also includes the first path portion 29 a and the second path portion 29 c .

[0088] Description of other configurations, functions, and effects will be omitted, but the description of the first and second embodiments can be incorporated into the third embodiment.

[0089] (Fourth embodiment)

[0090] Fig.10 Here, the same components as those of the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

[0091] The fourth embodiment further includes a pre-stage compressor 55 for compressing hydrogen gas before being compressed by the compressor 12 , an intermediate cooler 57 for cooling the hydrogen gas compressed by the pre-stage compressor 55 , and an intermediate reflux unit 59 .

[0092] The front stage compressor 55 and the intermediate stage cooler 57 are provided in the suction passage 21. The front stage compressor 55 is composed of a reciprocating compression mechanism. That is, the front stage compressor 55 has a cylinder, a piston, a piston connecting rod, a pair of suction valves, and a pair of discharge valves in the same manner as the compressor 12. Fig.10In the figure, the front stage compression section 55 is represented by a trapezoid for convenience, but the front stage compression section 55 is not necessarily a single-stage type, and it can also be composed of a plurality of compression stages.

[0093] The front stage compression unit 55 is driven by a crank mechanism shared with the compression unit 12. In other words, the front stage compression unit 55 and the compression unit 12 together constitute a single multi-stage reciprocating compressor. In addition, the front stage compression unit 55 may also be constituted as a reciprocating compressor independent of the compression unit 12.

[0094] A heat insulating material 26 for suppressing heat input from the outside air is provided in the portion of the intake flow path 21 from the liquefied hydrogen storage tank 23 to the pre-stage compression unit 55 .

[0095] The intermediate stage cooler 57 functions as an intermediate cooler for cooling the hydrogen gas before being sucked into the compressor 12, and the cooler 14 functions as an aftercooler for cooling the hydrogen gas discharged from the compressor 12. The intermediate stage cooler 57 may be water-cooled like the cooler 14, or may be air-cooled. The hydrogen gas cooled by the cooler 14 is sent to the demand end 28.

[0096] The intermediate stage return section 59 includes an intermediate stage return flow passage 59a and an intermediate stage return valve 59b, which is a valve arranged in the intermediate stage return flow passage 59a and capable of adjusting the opening degree. One end of the intermediate stage return flow passage 59a is connected to a portion between the intermediate stage cooler 57 and the compression section 12 in the suction flow passage 21, and the other end is connected to a portion between the preheater 16 and the pre-stage compression section 55 in the suction flow passage 21. A portion of the intermediate stage return flow passage 59a located downstream of the intermediate stage return valve 59b is provided with an insulating material 48 for suppressing heat input from the outside air.

[0097] The suction flow passage 21 is provided with an intermediate stage pressure sensor 61 for detecting the pressure of the hydrogen gas after passing through the intermediate stage cooler 57. The intermediate stage pressure sensor 61 is located downstream of the connection portion of the intermediate stage return flow passage 59a in the suction flow passage 21. Therefore, the intermediate stage pressure sensor 61 can detect the pressure of the hydrogen gas sucked into the compression unit 12.

[0098] The return control section 39 b controls the intermediate stage return valve 59 b based on the detection pressure of the intermediate stage pressure sensor 61 and controls the return valve 33 b based on the detection pressure of the pressure sensor 36 .

[0099] Description of other configurations, functions, and effects will be omitted, but the description of the first to third embodiments can be applied to the fourth embodiment.

[0100] (Fifth embodiment)

[0101] Fig.11 Here, the same components as those of the first to fourth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

[0102] In the first embodiment, the temperature sensor 37 is located in the suction flow path 21 and directly detects the suction temperature. In contrast, in the fifth embodiment, the temperature sensor 37 is configured to be located in the discharge flow path 25 and detect the discharge temperature. The temperature sensor 37 is arranged in the upstream path portion 29b in the discharge flow path 25. That is, the temperature sensor 37 is arranged between the preheater 16 and the compression unit 12 in the discharge flow path 25.

[0103] The functions of the controller 39 include: a calculation unit 39c that estimates the temperature of the suction side of the compression unit 12 based on the discharge temperature obtained by the temperature sensor 37. The calculation unit 39c is configured to derive the temperature of the suction side from the discharge temperature using a relationship, a mapping, etc. stored in the controller 39 that associates the discharge temperature with the temperature of the suction side. The relationship, for example, can be a relationship that assumes that hydrogen is adiabatically compressed in the compression unit 12 and that specifies the relationship between the suction pressure, the temperature of the suction side, the discharge pressure, and the discharge temperature. The mapping is a mapping based on data obtained from preliminary tests and is configured to associate the suction temperature with the discharge temperature. The control unit 39a refers to the temperature of the suction side estimated by the calculation unit 39c as the temperature of the hydrogen gas inhaled by the compression unit 12, that is, the suction temperature, and controls the adjustment unit 31.

[0104] exist Figure 4 In the flow shown in FIG. 1 , before step ST13 is executed, the suction temperature is estimated by the calculation unit 39c based on the discharge temperature. In step ST13, the suction temperature (temperature T) estimated by the calculation unit 39c is used. Figure 4 The process is the same.

[0105] Therefore, in the present embodiment, the flow rate of hydrogen gas passing through the preheater 16 is adjusted by the adjustment unit 31, and the flow rate of hydrogen gas not passing through the preheater 16 is also adjusted. In addition, the adjustment unit 31 is controlled so that the temperature of hydrogen gas sucked into the compressor 12 is within a specified temperature range. Therefore, the suction temperature of the compressor 12 can be appropriately managed. In addition, by utilizing the heat of the hydrogen gas (exhaust gas) before flowing into the cooler 14, the suction temperature can be appropriately heated.

[0106] In addition, Fig.11 In the example in which the adjustment unit 31 includes a three-way valve 31a, the adjustment unit 31 may also include a Figure 5The case shown in FIG. 1 is similarly provided with: a first valve 31b provided in the first path portion 29a and capable of adjusting the opening; and a second valve 31c provided in the second path portion 29c and capable of adjusting the opening. Figure 7 The illustrated case is similarly provided with a valve 31 d provided in the first path portion 29 a and capable of adjusting the opening degree, and a throttle portion 31 e provided in the second path portion 29 c .

[0107] exist Fig.11 In the embodiment, the discharge flow path 25 includes the first path portion 29a and the second path portion 29c, but the discharge flow path 25 may be replaced with the first path portion 29a and the second path portion 29c. Figure 8 In the case shown in FIG. 1 , the suction flow passage 21 has a first path portion 29a and a second path portion 29c. Fig. 9 In the case shown in FIG. 1 , the second compressor and the second cooler are also provided. In this case, the reflux section 33 may include a first reflux section and a second reflux section. Fig.10 The structure shown in FIG. 1 is similarly configured to include a pre-stage compression unit 55, an intermediate stage cooler 57, and an intermediate stage reflux unit 59. Fig.11 In the composition, it is also possible to Figure 6 The control actions shown.

[0108] Description of other configurations, functions, and effects is omitted, but the description of the first to fourth embodiments can be cited in the fifth embodiment.

[0109] The embodiments disclosed this time should be interpreted as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the claims and the meaning equivalent to the claims.

[0110] exist Figure 1 In the compressor unit 10 shown, the return valve 33b may be controlled based on the detection value of the pressure sensor provided in the suction flow passage 21. In addition, the return valve 33b may be controlled based on both the pressure sensor 36 and the pressure sensor provided in the suction flow passage 21. In addition, the return valve 33b may be controlled based on a flow sensor (disposed at a location where the pressure sensor 36 is disposed) instead of the pressure sensor 36. The same is true for the return valves in other embodiments.

[0111] Here, the embodiment is summarized.

[0112] (1) The compressor unit involved in the embodiment recovers boil-off gas, i.e., hydrogen, from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand side including at least one of an engine, a power generation device, and a boiler, and the compressor unit includes: a compression unit composed of a reciprocating compression mechanism, which compresses the hydrogen flowing in the suction flow channel and discharges the compressed hydrogen to the discharge flow channel; a water-cooled or air-cooled cooler, which cools the hydrogen discharged to the discharge flow channel; a preheater, which can heat-exchange the hydrogen before being sucked into the compression unit with the hydrogen discharged from the compression unit, i.e., the hydrogen flowing toward the cooler; and a reflux unit, which includes a reflux flow channel for returning the hydrogen discharged from the compression unit to a portion of the suction flow channel located downstream or upstream of the preheater. The discharge flow channel or the suction flow channel has a first path portion and a second path portion that are divided into two branches along the flow direction of the hydrogen and then merge with each other, the first path portion passes through the preheater, and the second path portion does not pass through the preheater. The compressor unit further includes: an adjustment unit that adjusts the flow rate of hydrogen gas flowing through the first path portion and adjusts the flow rate of hydrogen gas flowing through the second path portion; and a control unit that controls the adjustment unit so that the temperature of hydrogen gas sucked into the compression unit, that is, the suction temperature, is within a predetermined temperature range. The predetermined temperature range is higher than a reference temperature based on the liquefaction temperature of air.

[0113] In this compressor unit, the flow rate of hydrogen passing through the preheater and the flow rate of hydrogen not passing through the preheater are adjusted by an adjustment unit. Furthermore, the adjustment unit is controlled in such a way that the temperature of the hydrogen sucked into the compression part is within a specified temperature range. Therefore, the suction temperature of the compression part can be properly managed. In addition, by utilizing the heat of the hydrogen (exhaust gas) before flowing into the cooler, the suction temperature can be properly heated. Furthermore, the temperature range of the hydrogen sucked into the compression part can be made higher than a specified reference temperature, thereby avoiding the liquefaction of oxygen as a combustion-aiding gas.

[0114] (2) The compressor unit may further include: a temperature sensor, which is arranged in the suction flow passage between the connection portion of the return flow passage and the compression portion. In this case, the control portion may refer to the temperature acquired by the temperature sensor as the suction temperature. In this configuration, since the connection portion of the return flow passage connected to the suction flow passage is located upstream relative to the temperature sensor, even if the gas temperature detected by the temperature sensor changes due to the return of hydrogen to the suction flow passage based on the return portion, the temperature of the hydrogen gas sucked into the compression portion can be kept within an appropriate range.

[0115] (3) The compressor unit recovers hydrogen, which is a flammable boil-off gas below 0°C, from the liquefied hydrogen storage tank. The compressor unit may further include: a temperature sensor disposed between the preheater and the compressor in the discharge flow passage; and a calculation unit that estimates the temperature of the suction side of the compressor based on the discharge temperature acquired by the temperature sensor. In this case, the control unit may refer to the temperature of the suction side estimated by the calculation unit as the suction temperature.

[0116] In this configuration, the flow rate of hydrogen passing through the preheater and the flow rate of hydrogen not passing through the preheater are adjusted by the adjustment unit. Furthermore, the adjustment unit is controlled in such a manner that the temperature of the hydrogen sucked into the compression section is within a specified temperature range. Therefore, the suction temperature of the compression section can be properly managed. In addition, by utilizing the heat of the hydrogen (exhaust gas) before flowing into the cooler, the suction temperature can be properly heated. Furthermore, the temperature range of the hydrogen sucked into the compression section can be made higher than a specified reference temperature, thereby avoiding the liquefaction of oxygen as a combustion-aiding gas.

[0117] (4) The adjustment unit may include a three-way valve provided at a branch point between the first path portion and the second path portion. In this configuration, the flow rate of hydrogen gas to the preheater and the flow rate of hydrogen gas not passing through the preheater can be adjusted separately with one valve, which helps to simplify the structure.

[0118] (5) The adjustment unit may include: a valve provided in the first path portion and capable of adjusting the opening degree; and a valve provided in the second path portion and capable of adjusting the opening degree.

[0119] (6) The adjustment unit may include: a valve provided in the first path portion and capable of adjusting the opening degree; and a throttle portion provided in the second path portion and configured to suppress a flow rate of the hydrogen gas.

[0120] (7) The control unit may control the adjustment unit so as to stop the flow of hydrogen gas in the first path portion when the intake temperature is equal to or higher than a predetermined upper limit temperature, and control the adjustment unit so as to keep the intake temperature within the predetermined temperature range when the intake temperature is lower than the upper limit temperature. In this configuration, the flow of hydrogen gas in the preheater is stopped when the intake temperature is equal to or higher than a predetermined upper limit temperature, so that the temperature of the hydrogen gas taken into the compression unit does not become too high.

[0121] (8) The suction flow path may include a heat insulating material for suppressing heat input from the outside air. In this configuration, by suppressing unexpected heat input to the suction flow path, the suction temperature control can be performed more appropriately.

[0122] As described above, in the compressor unit, the temperature of the hydrogen gas which is the boil-off gas sucked into the reciprocating compressor can be appropriately managed.

Claims

1. A compressor unit that recovers boil-off gas, i.e., hydrogen, from a liquefied hydrogen storage tank and supplies at least a portion of the hydrogen to a demand side including at least one of an engine, a power generation device, and a boiler, the compressor unit being characterized by comprising: A compression section composed of a reciprocating compression mechanism compresses the hydrogen gas flowing in the suction flow channel and discharges the compressed hydrogen gas to the discharge flow channel; a water-cooled or air-cooled cooler for cooling the hydrogen discharged to the discharge flow channel; a preheater capable of exchanging heat between the hydrogen gas before being sucked into the compressor and the hydrogen gas discharged from the compressor, i.e., the hydrogen gas flowing toward the cooler; as well as, The reflux section includes a reflux passage for returning the hydrogen gas discharged from the compression section to a portion of the suction passage located downstream or upstream of the preheater; wherein, The exhaust flow channel or the intake flow channel has a first path portion and a second path portion that are divided into two branches along the flow direction of the hydrogen gas and then merged with each other, the first path portion passes through the preheater, and the second path portion does not pass through the preheater. The compressor unit also includes: an adjusting unit that adjusts the flow rate of the hydrogen gas flowing through the first path portion and adjusts the flow rate of the hydrogen gas flowing through the second path portion; and The control unit controls the adjustment unit so that the temperature of the hydrogen gas sucked into the compression unit, that is, the suction temperature, is within a predetermined temperature range; wherein, The predetermined temperature range is higher than a reference temperature based on the liquefaction temperature of air.

2. The compressor unit according to claim 1, characterized in that Also includes: A temperature sensor is arranged in the suction flow passage between the connection portion of the return flow passage and the compression portion; wherein, The control unit refers to the temperature acquired by the temperature sensor as the intake temperature.

3. The compressor unit according to claim 1, characterized in that: The compressor unit recovers the flammable boil-off gas, i.e. hydrogen, which is below 0°C from the liquefied hydrogen storage tank. The compressor unit also includes: a temperature sensor disposed in the discharge flow passage between the preheater and the compression section; and A calculation unit estimates the temperature of the suction side of the compression unit according to the discharge temperature obtained by the temperature sensor; wherein, The control unit refers to the temperature of the suction side estimated by the calculation unit as the suction temperature.

4. The compressor unit according to any one of claims 1 to 3, characterized in that: The adjustment unit includes a three-way valve provided at a branch point between the first path portion and the second path portion.

5. The compressor unit according to any one of claims 1 to 3, characterized in that: The adjustment unit includes: a valve provided in the first path portion and capable of adjusting the opening degree; and a valve provided in the second path portion and capable of adjusting the opening degree.

6. The compressor unit according to any one of claims 1 to 3, characterized in that: The adjustment unit includes: a valve provided in the first path portion and capable of adjusting the opening degree; and a throttle portion provided in the second path portion and configured to suppress a flow rate of the hydrogen gas.

7. The compressor unit according to any one of claims 1 to 3, characterized in that: The control unit controls the adjustment unit to stop the flow of hydrogen gas in the first path portion when the intake temperature is equal to or higher than a predetermined upper limit temperature, and controls the adjustment unit to keep the intake temperature within the predetermined temperature range when the intake temperature is lower than the upper limit temperature.

8. The compressor unit according to any one of claims 1 to 3, characterized in that: The suction flow passage includes a heat insulating material for suppressing heat input from external air.

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