阅读说明：本技术 往复运动压缩机 (Reciprocating compressor ) 是由 鹈饲幸治 松原洋辅 于 2020-02-10 设计创作，主要内容包括：往复运动压缩机(1A)具备：压缩部(2),其通过活塞(6)压缩经由吸入阀(36)吸入到缸体(4)的气体,并且经由排出阀(51)排出被压缩的气体；活塞驱动部(3),其经由与活塞(6)连结的活塞杆(9),对活塞(6)提供使活塞(6)往复运动的力；以及壳体(17),其收容压缩部(2),在压缩部(2)的周围形成真空区域。(A reciprocating compressor (1A) is provided with: a compression unit (2) that compresses gas, which is sucked into the cylinder (4) via a suction valve (36), by a piston (6), and discharges the compressed gas via a discharge valve (51); a piston drive unit (3) that provides a force for reciprocating the piston (6) to the piston (6) via a piston rod (9) connected to the piston (6); and a housing (17) that houses the compression section (2) and forms a vacuum region around the compression section (2).)

1. A reciprocating compressor is provided with:

a compression part compressing gas sucked into the cylinder through the suction valve by the piston and discharging the compressed gas through the discharge valve;

a piston driving unit that supplies a force for reciprocating the piston to the piston via a rod connected to the piston; and

and a container part which accommodates the compression part and forms a vacuum region around the compression part.

2. The reciprocating compressor of claim 1,

the container portion has:

a housing forming the vacuum region; and

a cylinder holding portion disposed between the housing and the cylinder,

a side surface of the cylinder is separated from an inner surface of the housing facing the side surface of the cylinder,

a first end of the cylinder holding portion is provided on a side surface of the cylinder,

the second end of the cylinder holding portion is provided to an inner surface of the housing.

3. The reciprocating compressor of claim 1,

further provided with:

an intermediate cylinder portion disposed between the piston driving portion and the container portion, and accommodating the rod; and

and a heat resistance portion disposed between the compression portion and the intermediate cylinder portion.

4. The reciprocating compressor of claim 1,

the suction valve is provided in the cylinder and is capable of switching between an open state in which the gas is allowed to enter and exit the cylinder and a closed state in which the gas is prohibited from entering and exiting the cylinder according to the internal pressure of the cylinder,

the suction valve further includes a pressure relief device that is disposed on an outer surface side of the container portion and that forcibly switches the closed state of the suction valve to the open state upon receiving a supply of compressed gas.

5. The reciprocating compressor of claim 1,

further comprising an intermediate cylinder portion disposed between the piston driving portion and the container portion and accommodating the rod,

the intermediate cylinder portion forms a first intermediate chamber, a second intermediate chamber, and a third intermediate chamber,

the first intermediate chamber, the second intermediate chamber, and the third intermediate chamber are arranged in this order in a direction from the piston drive unit toward the container unit,

the internal pressure of the first intermediate chamber is higher than the internal pressures of the second intermediate chamber and the third intermediate chamber.

6. The reciprocating compressor of claim 1,

the liquefaction temperature of the gas is lower than the liquefaction temperature of oxygen or the liquefaction temperature of nitrogen.

Technical Field

The present disclosure relates to reciprocating compressors.

Background

The liquefied gas is stored in a tank for storage or transportation. The liquefaction temperature of the gas is generally lower than the atmospheric temperature. Therefore, the liquefied gas contained in the tank is vaporized inside the tank by the heat input to the tank. The gasified Gas is called Boil Off Gas (BOG). The vaporized gas (BOG) increases the internal pressure of the tank. Therefore, the internal pressure of the tank is controlled to a predetermined value by compressing the vaporized gas. The compressed and gasified gas is sent under pressure to another facility.

Patent document 1 discloses a pressure control apparatus. The apparatus controls the internal pressure of a tank storing cryogenic liquefied gas. The plant is provided with a BOG compressor which compresses the boil-off gas to a desired pressure. Patent document 1 exemplifies a reciprocating compressor as a BOG compressor.

Patent document 1: japanese patent laid-open No. 2008-232351

In recent years, hydrogen has attracted attention as a new energy source. Even when hydrogen is used as an energy source, the hydrogen is liquefied during storage and transportation as in natural gas. However, the liquefaction temperature of hydrogen is lower than that of air. Therefore, if equipment such as a reciprocating compressor to which natural gas or the like is applied to hydrogen as it is, there is a possibility that a problem may occur due to liquid hydrogen having an extremely low temperature. For example, liquefied air is generated around a device to which liquid hydrogen is supplied.

Disclosure of Invention

Accordingly, the present disclosure describes a reciprocating compressor capable of suppressing the generation of liquefied air.

A reciprocating compressor according to an aspect of the present disclosure includes: a compression part compressing gas sucked into the cylinder through the suction valve by the piston and discharging the compressed gas through the discharge valve; a piston driving unit that supplies a force for reciprocating the piston to the piston via a rod connected to the piston; and a container portion that accommodates the compression portion and forms a vacuum region around the compression portion.

A reciprocating compressor as one embodiment of the present disclosure can suppress the generation of liquefied air.

Drawings

FIG. 1 is a schematic diagram of a BOG compression system having an embodiment of a reciprocating compressor.

Fig. 2 is a side view of a cross section of the reciprocating compressor.

Fig. 3 is a front view of a cross section of the reciprocating compressor.

Fig. 4 is a sectional view showing a part of fig. 2 in an enlarged manner.

Fig. 5 is a sectional view showing the suction mechanism.

Detailed Description

A reciprocating compressor according to an aspect of the present disclosure includes: a compression part compressing gas sucked into the cylinder through the suction valve by the piston and discharging the compressed gas through the discharge valve; a piston driving unit that supplies a force for reciprocating the piston to the piston via a rod connected to the piston; and a container portion that accommodates the compression portion and forms a vacuum region around the compression portion.

The compression part of the compressed gas of the reciprocating compressor is accommodated in the container part. The container portion forms a vacuum region around the compression portion. As a result, the compression portion is thermally insulated from the outer region by the vacuum region. That is, even when extremely low-temperature gas is supplied to the compression portion, the peripheral region of the reciprocating compressor is not excessively cooled. Therefore, the generation of liquefied air can be suppressed.

In one embodiment, the container portion may include a housing forming the vacuum region, and a cylinder holding portion disposed between the housing and the cylinder. The side surface of the cylinder may also be spaced apart from the inner surface of the housing facing the side surface of the cylinder. The first end of the cylinder holding portion may be provided on a side surface of the cylinder. The second end of the cylinder holding portion may be provided on the inner surface of the housing. According to the above configuration, the cylinder can be appropriately supported. As a result, vibration caused by the reciprocating motion of the piston can be received.

The reciprocating compressor according to one aspect may further include an intermediate cylindrical portion disposed between the piston driving portion and the container portion and configured to accommodate the rod, and a heat-resistant portion disposed between the compression portion and the intermediate cylindrical portion. According to the above configuration, the compression section and the intermediate cylinder section can be thermally insulated from each other. As a result, even when extremely low-temperature gas is supplied to the compression section, the influence of heat of the compression section can be suppressed from reaching the intermediate cylinder section. That is, even when a gas having a very low temperature is supplied to the compression section, the intermediate cylinder section is not excessively cooled. Therefore, the generation of liquefied air can be suppressed.

In one aspect, the suction valve may be provided in the cylinder, and may be switched between an open state allowing entry and exit of the gas into and out of the cylinder and a closed state prohibiting entry and exit of the gas in accordance with an internal pressure of the cylinder, and the suction valve may further include a pressure relief device that is disposed on an outer surface side of the tank portion and forcibly switches the closed state of the suction valve to the open state upon supply of the compressed gas. The pressure relief device is arranged outside the container part. The portion other than the container portion is insulated from the compression portion. Therefore, the pressure relief device is not affected by the heat of the compression portion. As a result, the pressure relief device can be reliably operated.

The reciprocating compressor according to one aspect may further include an intermediate cylindrical portion that is disposed between the piston driving portion and the container portion and that accommodates the rod. The intermediate cylinder portion may form a first intermediate chamber, a second intermediate chamber, and a third intermediate chamber. The first intermediate chamber, the second intermediate chamber, and the third intermediate chamber may be arranged in this order in a direction from the piston driving portion toward the container portion. The internal pressure of the first intermediate chamber may be higher than the internal pressures of the second intermediate chamber and the third intermediate chamber. According to the above configuration, the first intermediate chamber, the second intermediate chamber, and the third intermediate chamber are formed between the compression unit and the piston driving unit. The internal pressure of the first intermediate chamber provided on the piston drive unit side is higher than that of the second intermediate chamber and the third intermediate chamber. As a result, the gas leakage from the compression section to the piston driving section can be suppressed by the pressure difference. Therefore, leakage of extremely low temperature gas is suppressed. As a result, the piston driving unit can be reliably operated.

In one embodiment, the liquefaction temperature of the gas may be lower than the liquefaction temperature of oxygen or the liquefaction temperature of nitrogen. A reciprocating compressor of one mode can be suitably applied to such gas.

Hereinafter, a mode for implementing the reciprocating compressor of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

Fig. 1 shows an boil-off gas compression system having reciprocating compressors 1A, 1B. The boil-off gas compression system is referred to as the "BOG compression system 100" in the following description. The BOG compression system 100 is installed in a receiving site, a storage site, and the like that target hydrogen. The storage base is provided with a tank for storing liquid hydrogen. Inside the tank, hydrogen gas is generated by vaporization of the liquid hydrogen. The BOG compression system 100 is used for compression of the hydrogen.

In the following description, the BOG compression system 100 will be described with reference to hydrogen gas. However, the gas to be subjected to the BOG compression system 100 is not limited to hydrogen. The BOG compression system 100 can also be applied to gaseous fuels such as natural gas, propane gas, and the like. That is, the BOG compression system 100 can be applied to a system that generates BOG. Specifically, the BOG compression system 100 can be suitably used for a system that targets a gas having a liquefaction temperature lower than that of air. Air contains primarily oxygen and nitrogen. Therefore, the BOG compression system 100 can be suitably used for a system targeting a gas having a liquefaction temperature lower than the liquefaction temperature of oxygen or the liquefaction temperature of nitrogen. Examples of such a gas include the above-mentioned hydrogen and helium. In the present disclosure, the simple description of "gas" refers to a gaseous fuel that is also included in natural gas and the like in a broad sense. The term "gas" refers to, in a narrow sense, hydrogen gas or the like having a liquefaction temperature lower than that of air among the gas fuels.

The BOG compression system 100 has two reciprocating compressors 1A, 1B. The reciprocating compressor 1A sucks hydrogen gas from a tank, for example. Next, the reciprocating compressor 1A compresses the sucked hydrogen gas. Then, the reciprocating compressor 1A supplies the compressed hydrogen gas to the other reciprocating compressor 1B. The other reciprocating compressor 1B further compresses the hydrogen gas and then discharges the compressed hydrogen gas. That is, the BOG compression system 100 is a two-stage compression system that further compresses the gas compressed by one reciprocating compressor 1A by the other reciprocating compressor 1B. The reciprocating compressors 1A, 1B have a compression section 2 and a piston drive section 3. Further, the number of reciprocating compressors that the BOG compression system 100 has may be appropriately selected according to the performance required of the BOG compression system 100. For example, the BOG compression system 100 may be a three-stage type including three reciprocating compressors, or may be a four-stage type including four reciprocating compressors. Further, for example, the BOG compression system 100 may be a three-stage system including four reciprocating compressors.

The reciprocating compressors 1A and 1B are only arranged differently, and have a common detailed structure. Hereinafter, one reciprocating compressor 1A (left side of the drawing) will be described in detail, and the other reciprocating compressor 1B (right side of the drawing) will not be described.

The compression section 2 includes a cylinder 4, a piston 6, an intake mechanism 7, and a discharge mechanism 8. The cylinder 4 and the piston 6 form compression spaces P1, P2 for compressing gas. For example, the compression unit 2 has two compression spaces P1 and P2. The suction mechanism 7 and the discharge mechanism 8 are provided to be able to suck and discharge gas into and from the compression spaces P1 and P2, respectively. An end of a piston rod 9 is connected to the piston 6. The other end of the piston rod 9 is connected to the piston driving unit 3.

The piston drive unit 3 has a crankshaft 11. The crankshaft 11 converts rotational motion provided from the drive source 12 into reciprocating motion of the piston rod 9. The piston drive unit 3 includes a crank case 13, a crosshead 14, and a connecting rod 16 in addition to the crankshaft 11.

As shown in fig. 2, the reciprocating compressor 1A includes a container portion 15, an intermediate cylinder portion 18, and a casing heat insulator 19, in addition to the compression portion 2 and the piston driving portion 3.

The shape of the cylinder 4 of the compression section 2 can be appropriately selected according to the required performance and conditions. For example, the cylinder 4 may be in the shape of a cube or a cylinder. In the present disclosure, the shape of the cylinder 4 is described as a cube. The cylinder 4 is disposed such that the center axis of the cylinder 4 is along the horizontal direction. The cylinder tip end portion 4a has an opening. The opening is hermetically closed by a cover 4H. A gap valve may be provided in the cover 4H. The cylinder base end portion 4b is fixed to the container portion 15. More specifically, the casing insulator 19 (heat resistance portion) is sandwiched between the cylinder base end portion 4b and the container portion 15. The casing insulator 19 suppresses heat transfer between the cylinder 4 and the container portion 15. As the case insulator 19, for example, a fiber-reinforced resin for thermal insulation such as a glass fiber-reinforced resin can be used.

The container portion 15 has a housing 17 and a cylinder holder 21. The housing 17 forms a housing space S that houses the compression section 2. The housing space S is depressurized and is in a so-called vacuum state. A vacuum pump not shown is connected to the container portion 15. The vacuum pump operates as required in the operation of the reciprocating compressor 1A. The evacuation operation of the vacuum pump may be continuous or intermittent. The vacuum state means that the internal pressure of the housing 17 is lower than the atmospheric pressure. That is, when defining the vacuum state, specific values of the internal pressure and the degree of vacuum are not particularly limited. The housing space S formed by the housing 17 insulates the compression section 2 from the atmospheric environment. Therefore, the case 17 forms a heat insulating portion around the compression portion 2. In short, the vacuum state of the housing space S may be a state in which a desired heat insulating effect can be exhibited.

In the present disclosure, the reciprocating compressors 1A and 1B are provided with the tank parts 15, respectively, as an example. For example, the container portion 15 need not be provided in all of the reciprocating compressors 1A, 1B of the BOG compression system 100. For example, in the BOG compression system 100, only the primary reciprocating compressor 1A may be provided with the tank unit 15, and the tank unit 15 may be omitted in the reciprocating compressor 1B.

The housing 17 is, for example, cylindrical in shape. The housing 17 has a housing distal end portion 17a, a housing proximal end portion 17b, and a housing peripheral wall 17 c. A space enclosed by the case distal end portion 17a, the case proximal end portion 17b, and the case peripheral wall 17c is an accommodation space S. The case base end portion 17b is fixed to the cylinder 4 via a case insulator 19. The length of the housing 17 in the axial direction is longer than the length of the cylinder 4 in the axial direction. Therefore, a gap is formed between the housing distal end portion 17a and the cylinder distal end portion 4 a. The diameter of the housing 17 is larger than the height and width of the cylinder 4. Further, the center axis of the cylinder 4 substantially overlaps the center axis of the housing 17. Therefore, a gap is also formed between the housing peripheral wall 17c and the cylinder upper surface 4 c. Similarly, a gap is also formed between the housing peripheral wall 17c and the cylinder lower surface 4 d. These gaps are vacuum areas formed around the cylinder 4.

The cylinder base end portion 4b is fixed to the housing 17. In this way, the cylinder tip end portion 4a, the cylinder upper surface 4c, and the cylinder lower surface 4d are separated from the housing 17. This state is a cantilever state with the cylinder base end portion 4b as a support end. Thus, the distal end side of the cylinder 4 is supported by the cylinder bracket 21.

A cylinder holder 21 is disposed at the distal end portion of the cylinder 4. The cylinder holder 21 vertically supports the end portion of the cylinder 4. The cylinder frame 21 has an outer vessel frame 26, an inner lower vessel frame 27A, and an inner upper vessel frame 27B. The outer vessel bracket 26, the lower inner vessel bracket 27A, and the upper inner vessel bracket 27B are disposed on the same reference line along the vertical direction. However, the "arrangement on the same reference line" is not limited to a configuration in which the axes of the outer vessel frame 26, the lower inner vessel frame 27A, and the upper inner vessel frame 27B exactly coincide with a common reference axis. As long as the outer vessel bracket 26, the lower inner vessel bracket 27A, and the upper inner vessel bracket 27B are configured to be able to appropriately transmit the weight of the cylinder block 4 to the foundation 200.

The outer container holder 26 is disposed outside the housing 17. More specifically, the container outer holder 26 is disposed between the outer peripheral surface of the housing peripheral wall 17c and the base 200. In other words, the upper end of the container outer holder 26 is fixed to the outer peripheral surface of the housing peripheral wall 17 c. The lower end of the outer container bracket 26 is fixed to the base 200.

Lower inner container support 27A is disposed inside housing 17. More specifically, the lower inner casing bracket 27A is disposed between the inner peripheral surface of the casing peripheral wall 17c and the cylinder lower surface 4 d. The lower inner container support 27A is disposed on the outer container support 26 via the housing peripheral wall 17 c. According to this configuration, the weight of the compression part 2 is transmitted to the base 200 via the lower in-container bracket 27A, the housing peripheral wall 17c, and the out-container bracket 26.

As shown in fig. 3, lower inner vessel bracket 27A has outer peripheral seat 28 (second end portion), inner peripheral seat 29 (first end portion), and elastic portion 31. The outer peripheral base 28 is fixed to the inner peripheral surface of the housing peripheral wall 17 c. The inner peripheral base 29 is fixed to the cylinder lower surface 4 d. The elastic portion 31 is sandwiched between the outer peripheral base 28 and the inner peripheral base 29. The elastic portion 31 allows relative movement of the inner peripheral base 29 with respect to the outer peripheral base 28. For example, the elastic portion 31 allows the movement of the inner peripheral base 29 in the vertical direction with respect to the outer peripheral base 28.

Inner peripheral base 29 has a base portion 32 and a base coupling portion 33. The pedestal base 32 is fixed to the cylinder lower surface 4 d. The base connecting portion 33 is fixed to the elastic portion 31. At least one of the base portion 32 and the base connecting portion 33 may be a heat insulating member. For example, the entire or a part of the pedestal connection portion 33 may be made of a heat insulating resin material. The connection portions of the pedestal base 32 and the pedestal connection portion 33 are not fixed to each other. Specifically, base main surface 32s of base 32 is in contact with coupling main surface 33s of base coupling portion 33. The cross-sectional shape of the base main surface 32s is triangular. The ridge of the base main surface 32s extends in the moving direction of the piston 6. The cross section of the connecting main surface 33s is valley-shaped. With this configuration, the base connection portion 33 can move relative to the base portion 32 in the movement direction of the piston 6.

Due to the reciprocating motion of piston 6, base 32 vibrates with respect to base connection portion 33. Further, the vibration can be reduced by the friction between the base main surface 32s and the coupling main surface 33 s. More specifically, the lower container inner bracket 27A follows the relative movement of the cylinder 4. Further, the weight of the cylinder 4 is appropriately applied to the lower vessel inner bracket 27A. As a result, the pressing force and the frictional force can be obtained. Therefore, the vibration in the reciprocating direction caused by the action of the piston 6 is suppressed.

By allowing this relative movement, thermal deformation due to the temperature difference between the compression portion 2 and the container portion 15 can be tolerated. For example, if hydrogen gas is supplied to the compression portion 2, the cylinder 4 is cooled and may contract in the moving direction of the piston 6. That is, the relative positional relationship between the compression part 2 and the container part 15 changes. In the lower tank inner support 27A, the base 32 on the cylinder 4 side is movable relative to the base connecting portion 33 on the housing 17 side. Therefore, deformation of the cylinder 4 is allowed by the relative movement of the base 32 with respect to the base coupling portion 33. Therefore, the reciprocating compressor 1A can reduce unnecessary stress generated by thermal deformation due to a temperature difference. Further, the relative positional relationship changes in a direction (for example, a vertical direction) intersecting the moving direction of the piston 6 also due to thermal deformation caused by a temperature difference between the compression portion 2 and the container portion 15. This change in direction is permitted by the elastic portion 31.

The configurations of the base portion 32 and the base coupling portion 33 are not limited to the above-described configurations. More specifically, the structure of the base main surface 32s and the connecting main surface 33s is not limited to the above structure. For example, the relationship between the irregularities of the base main surface and the connection main surface may be reversed. The base main surface may be a convex curved surface, and the coupling main surface may be a concave curved surface. The base main surface and the coupling main surface may have a guide structure. Specifically, a guide structure extending in the axial direction may be provided at a connecting portion between the base portion and the base connecting portion. At least one ridge is provided on the pedestal base. On the other hand, at least one guide groove is provided in the pedestal connection portion. The ridge has a cross-sectional shape substantially equal to that of the guide groove, and the ridge is fitted into the guide groove. Thus, the ridge can slide in the axial direction. On the other hand, the ridge cannot move in a direction intersecting the axial direction.

The weight of the lower in-vessel bracket 27A and the outer-vessel bracket 26 supporting the compression part 2 has been described. That is, the lower inner vessel bracket 27A constitutes a cylinder holding portion. The interior of the housing 17 is depressurized. Therefore, an external force caused by atmospheric pressure acts on the housing 17. For example, the external force acts in the direction of the crush can peripheral wall 17 c. Therefore, as a member that reacts to this external force, not only the lower in-vessel bracket 27A but also the upper in-vessel bracket 27B is provided. As with the lower inner vessel bracket 27A, the upper inner vessel bracket 27B also functions to suppress vibration caused by the operation of the piston 6 by the pressing force of the elastic body.

The upper inner-tank bracket 27B is disposed inside the casing 17. More specifically, the upper tank inner bracket 27B is disposed between the inner peripheral surface of the case peripheral wall 17c and the cylinder upper surface 4 c. The upper inner vessel support 27B is disposed above the outer vessel support 26, as with the lower inner vessel support 27A. Further, the upper inner vessel support 27B has the same structure as the lower inner vessel support 27A. Therefore, a detailed description of the upper in-vessel bracket 27B is omitted.

The compression section 2 has a piston rod seal 22 in addition to the cylinder 4, the piston 6, the suction mechanism 7, and the discharge mechanism 8.

As shown in fig. 4, a part of the rod seal 22 is disposed in a seal hole 4p having an opening at the cylinder base end 4 b. The piston rod seal 22 allows a reciprocating movement of the piston rod 9 relative to the cylinder 4. In addition, the piston rod seal 22 maintains the compression spaces P1, P2 airtight. The rod seal 22 functions as a seal portion for suppressing leakage of gas from the cylinder 4.

The piston rod seal 22 has a plurality of seal units 23A, 23B, 23C and an insulating ring 24. The seal units 23A, 23B, 23C have a seal housing 23h and at least one seal ring 23 r. The material, shape, and number of the seal rings 23r may be appropriately selected according to the sealing performance required for the piston rod seal 22. As a material of the seal ring 23r, for example, teflon (registered trademark) can also be used. The seal units 23A, 23B, and 23C are stacked in the axial direction thereof, and constitute the rod seal 22. In this laminated structure, not only the seal units 23A, 23B, and 23C but also the heat insulating ring 24 are included.

The seal unit 23A is disposed in the seal hole 4p of the cylinder 4. The seal unit 23A can be said to be disposed inside the housing 17. The "inside of the housing 17" mentioned here means in other words a portion affected by the temperature of the gas. That is, the seal unit 23A is exposed to an extremely low temperature environment.

On the other hand, the seal units 23B and 23C are disposed outside the seal hole 4 p. The seal unit 23B may also be regarded as a part of the housing 17. The seal unit 23C may be regarded as a part of the intermediate cylinder portion 18. The seal units 23B and 23C are disposed outside the housing 17. The "outside of the housing 17" mentioned here means in other words a portion which is hardly affected by the gas temperature. That is, the seal units 23B, 23C are insulated from an extremely low temperature environment.

The above-described "inside of the housing 17" and "outside of the housing 17" can be distinguished by the insulating ring 24. That is, the seal unit 23A disposed "inside the casing 17" is disposed on the cylinder 4 side of the heat insulating ring 24. The seal units 23B and 23C disposed "outside the casing 17" are disposed on the intermediate cylinder portion 18 side of the heat insulating ring 24. In the example of fig. 4, the insulation ring 24 is part of the housing insulation 19. That is, the heat insulating ring 24 is disposed between the cylinder base end portion 4b and the housing 17. Furthermore, the heat shield ring 24 may be another component independent of the housing heat shield 19. In this case, the heat insulating ring 24 may be disposed in the seal hole 4p of the cylinder 4.

As shown in fig. 2, the suction mechanism 7 guides the gas to the inside of the cylinder 4. As an example, the gas to be inhaled is hydrogen at minus 245 ℃. The suction mechanism 7 includes an expansion joint 34, a suction valve 36, and a decompressor (unloader)38 (see fig. 5). The expansion joint 34 is disposed between the cylinder 4 and the housing 17. More specifically, one end of the expansion joint 34 is connected to the suction cover 17N of the housing 17. The other end of the expansion joint 34 is connected to the cylinder upper surface 4 c. A hole 34h constituting a gas path is provided inside the expansion joint 34. The hole 34h is connected to a gas introduction hole 4n provided in the cylinder 4. The gas introduction hole 4n is provided with a suction valve 36. The suction valve 36 switches between a state (open state) in which gas is allowed to be sucked and a state (closed state) in which gas is not allowed to be sucked according to the internal pressure of the compression spaces P1, P2.

As shown in fig. 5, the suction valve 36 opens or closes the gas flow path in accordance with the internal pressure of the cylinder 4. The suction valve 36 has a valve support 39, a valve plate 41, and a valve seat 42. The valve support 39, the valve plate 41, and the valve seat 42 constitute a control valve. The valve plate 41 is disposed between the valve support 39 and the valve seat 42 and is movable therebetween. When the valve plate 41 is in contact with the valve seat 42, the suction valve 36 is in the closed state. On the other hand, when the valve plate 41 is in contact with the valve support 39, the suction valve 36 is in an open state. The open configuration and the closed configuration are switched according to the internal pressure of the compression spaces P1, P2. For example, the suction valve 36 is in an open state allowing gas to enter and exit when the internal pressure of the compression spaces P1 and P2 decreases (suction). On the other hand, when the internal pressure of the compression spaces P1, P2 rises (compresses), the suction valve 36 takes a closed state in which the entry and exit of gas are prohibited.

As shown in fig. 2, the discharge mechanism 8 discharges gas from the inside of the cylinder 4. For example, as an example, the gas to be discharged is hydrogen at minus 200 ℃. The discharge mechanism 8 has an expansion joint 49 and a discharge valve 51. The expansion joint 49 is disposed between the cylinder 4 and the housing 17. More specifically, one end of the expansion joint 49 is connected to the discharge cover 17M of the housing 17. The other end of the expansion joint 49 is connected to the cylinder lower surface 4 d. The through hole 49h of the expansion joint 49 is connected to the gas discharge hole 4m provided in the cylinder 4. The gas discharge hole 4m is provided with a discharge valve 51.

The discharge valve 51 has a valve support 39, a valve plate 41, a valve seat 42, and a spring 43, as with the suction valve 36. However, the relationship between the internal pressure and the opening/closing state of the compression spaces P1 and P2 is different from that of the intake valve 36. That is, the discharge valve 51 assumes the closed state when the internal pressure of the compression spaces P1, P2 decreases (suction). On the other hand, the discharge valve 51 assumes an open state when the internal pressure of the compression spaces P1, P2 rises (compresses).

The reciprocating compressor 1A includes a pressure relief device 38 (see fig. 5) as a capacity adjustment mechanism. A pressure relief device 38 is mounted to the suction valve 36.

As shown in fig. 5, the pressure relief device 38 has a yoke bar 44, a yoke plate 46, a yoke lever 61, and a lever driving portion 48. The end of the yoke 44 is pressed against the valve plate 41. The base end of the yoke bar 44 is fixed to the yoke plate 46. The yoke plate 46 is a circular plate, and a yoke lever 61 is fixed to the center thereof. The yoke rod 61 is arranged such that the axis of the yoke rod 61 extends in a direction orthogonal to the reciprocation axis. The base end of the yoke lever 61 protrudes from the housing peripheral wall 17 c. The base end of the yoke lever 61 is housed in the lever driving portion 48. The lever driving portion 48 is provided on the outer peripheral surface of the housing peripheral wall 17 c. The lever driving portion 48 controls the position of the yoke lever 61. The rod driving section 48 has, for example, a diaphragm 48 a. The position of the yoke 61 is controlled by controlling the pressure differential across the diaphragm 48 a. The pressure difference is controlled by the compressed gas supplied to one side of the diaphragm 48 a.

The yoke lever 61 has a first lever 63, a heat insulating lever 62, a break 65, and a second lever 64. These components are arranged in order from the outside of the housing 17 toward the cylinder 4. The upper end of the first rod 63 is the upper end of the yoke rod 61. The upper end of the first rod 63 is in contact with the diaphragm 48 a. The lower end of the first rod 63 is connected to the insulating rod 62. The heat insulating rod 62 insulates heat between a first rod 63 disposed on the housing 17 side and a second rod 64 disposed on the cylinder 4 side. The upper end of the insulating rod 62 is connected to the lower end of the first rod 63. The lower end of the insulating rod 62 is connected to the block 65. The blocking portion 65 can block the first rod 63 and the heat insulating rod 62 from the second rod 64. For example, when hydrogen gas is supplied to the cylinder 4, the cylinder 4 is thermally contracted. As a result, the relative distance between the cylinder 4 and the housing 17 changes. If the yoke lever 61 is an integral rod, tensile stress acts on the rod. Therefore, in order to cope with the increase in the relative distance between the cylinder 4 and the housing 17, the blocking portion 65 is provided as a structure for blocking the first rod 63 and the heat insulating rod 62 from the second rod 64. The upper portion of the block 65 is connected to the insulating rod 62. The lower portion of the interruption portion 65 is connected to the upper end of the second rod 64. The upper end of the second rod 64 is connected to the lower end of the interruption portion 65. The lower end of the second rod 64 is the lower end of the yoke lever 61, and is connected to the yoke plate 46.

As shown in fig. 4, the suction valve 36 is closed when the internal pressure of the compression spaces P1, P2 rises (compression). When the internal pressure of the compression spaces P1, P2 rises, the pressure relief device 38 forcibly releases the closed state. Specifically, when the internal pressure of the compression spaces P1, P2 rises, the valve plate 41 contacts the valve seat 42. When the capacity control is required, the pressure relief device 38 releases the contact with the valve seat 42 by pressing the valve plate 41. As a result, since the compression of the gas in the cylinder 4 becomes impossible, the internal pressure does not rise. Since the discharge valve 51 to be opened due to the increase of the internal pressure of the compression spaces P1, P2 is not opened, the compressed gas is not supplied. Therefore, the capacity of the reciprocating compressor 1A can be adjusted.

The intermediate cylinder 18 is disposed between the housing 17 and the piston driving unit 3. The intermediate tubular portion 18 may also be supported by the bracket 40, for example. The intermediate cylinder 18 accommodates the piston rod 9. The intermediate tubular portion 18 has a front intermediate tubular 52 and a rear intermediate tubular 53. The front intermediate cylinder 52 is disposed on the housing 17 side. The rear intermediate cylinder 53 is disposed on the piston driving portion 3 side. The intermediate tube portion 18 may be formed by integrating the front intermediate tube 52 and the rear intermediate tube 53. The front intermediate tube 52 is fixed to the case base end portion 17 b. The front intermediate tube 52 is also fixed to the rear intermediate tube 53.

The front intermediate tube 52 has a hole 52a provided at the tip end portion and a hole 52b provided at the rear end portion. The inner diameter of the holes 52a, 52b is larger than the outer diameter of the piston rod 9. The seal unit 23C is fitted into the hole 52 a. That is, the piston rod 9 is inserted through the seal unit 23C at the distal end surface. In addition, a desired member such as a seal unit may be disposed in the hole 52 b.

The front intermediate barrel 52 forms a rod seal chamber 52R. The rod seal chamber 52R is filled with the same gas as the gas supplied to the compression unit 2. For example, in the case where the gas supplied to the compression portion 2 is hydrogen gas, the rod seal chamber 52R is filled with hydrogen gas at normal temperature. The front intermediate cylinder 52 has a vent hole 52B for controlling the pressure of the rod seal chamber 52R.

The internal space of the rear intermediate tube 53 is partitioned by a partition wall 53W. As a result, the rear intermediate cylinder 53 has a first intermediate chamber 53E and a second intermediate chamber 53F. The first intermediate chamber 53E and the second intermediate chamber 53F are aligned in the axial direction of the piston rod 9. The first intermediate chamber 53E is provided on the piston driving portion 3 side. The second intermediate chamber 53F is provided on the front intermediate cylinder 52 side. The rear intermediate tube 53 has holes 53a, 53b, 53 c. The above-mentioned holes 53a, 53b, 53c are used for the piston rod 9. Like the holes 52a, 52b, the inner diameters of the holes 53a, 53b, 53c are larger than the outer diameter of the piston rod 9. The holes 53a, 53b, 53c are coaxial with each other. The holes 53a, 53b, and 53c are also coaxial with the holes 52a and 52b of the front intermediate tube 52. Further, a seal unit 55C is fitted into the hole 53 a. A seal unit 55A is fitted into the hole 53 b. A seal unit 55B is fitted into the hole 53 c.

The first intermediate chamber 53E is filled with nitrogen gas. The first intermediate chamber 53E receives a supply of nitrogen gas from the gas supply unit in order to maintain the internal pressure. For example, nitrogen gas is supplied from the supply portion 53S to the first intermediate chamber 53E. The gas supply unit controls the internal pressure of the first intermediate chamber 53E to a desired pressure. For example, in the case where nitrogen gas leaks from the seal units 55A, 55B, the internal pressure drops. At this time, the gas supply unit supplies nitrogen gas to the first intermediate chamber 53E, using the decrease in internal pressure as a trigger.

Since the seal unit 55A is present between the first intermediate chamber 53E and the second intermediate chamber 53F, it is desirable that no nitrogen gas should be present. However, the seal unit 55A allows the reciprocating motion of the piston rod 9 while maintaining airtightness of the first intermediate chamber 53E and the second intermediate chamber 53F with each other. Therefore, there is also a case where the nitrogen gas slightly moves between the first intermediate chamber 53E and the second intermediate chamber 53F.

Therefore, the internal pressure of the first intermediate chamber 53E is set to be higher than the internal pressure of the second intermediate chamber 53F, for example. By setting the internal pressure of the first intermediate chamber 53E to be higher than the internal pressure of the second intermediate chamber 53F, the direction of movement of the nitrogen gas between the first intermediate chamber 53E and the second intermediate chamber 53F can be determined. That is, the movement of the nitrogen gas can be defined as a flow from the first intermediate chamber 53E, the internal pressure of which is relatively high, to the second intermediate chamber 53F, the internal pressure of which is relatively low. With this configuration, the extremely low temperature gas compressed by the cylinder 4 can be suppressed from moving from the second intermediate chamber 53F to the first intermediate chamber 53E. In addition, hydrogen may leak from the rod seal chamber 52R to the second intermediate chamber 53F. The rear intermediate cylinder 53 has a vent hole 53B for discharging a mixed gas containing hydrogen and nitrogen. The vent port 53B is provided at a position corresponding to the second intermediate chamber 53F. Further, the rear intermediate cylinder 53 may have an oil drain portion for discharging oil leaking from the crankcase 13.

The reciprocating compressor 1A includes a casing 17, a cylinder block bracket 21, a casing heat insulator 19, a pressure relief device 38, and an intermediate cylinder 18 as characteristic components. The operational effects of the respective components will be described below.

The reciprocating compressor 1A has a compression section 2, a piston drive section 3, and a housing 17. The compression section 2 compresses the gas sucked into the cylinder 4 through the suction valve 36 by the piston 6, and discharges the compressed gas through the discharge valve 51. The piston driving unit 3 supplies a force for reciprocating the piston 6 to the piston 6 via a piston rod 9 connected to the piston 6. The housing 17 accommodates the compression part 2, and forms a vacuum region around the compression part 2.

The compression portion 2 of the compressed gas of the reciprocating compressor 1A is housed in the casing 17. The housing 17 forms a vacuum region around the compression unit 2. As a result, the compression section 2 is insulated from the region where the reciprocating compressor 1A is disposed by the vacuum region. Therefore, even when extremely low-temperature gas is supplied to the compression section 2, the region in which the reciprocating compressor 1A is disposed is suppressed from being excessively cooled. Therefore, the generation of liquefied air can be suppressed.

By housing the compression unit 2 in the casing 17 as a vacuum container, the operation efficiency of the compressor can be improved.

By using a vacuum container for heat insulation of the compression portion 2, it is not necessary to use a foam-based heat insulator for heat insulation of the compression portion 2. The foamed heat insulating material cannot ensure the performance at the temperature below minus 200 ℃. On the other hand, according to the case 17, a desired heat insulating performance can be obtained without being affected by the use temperature environment. Further, since the outer shape of the compression portion 2 is complicated, the foam heat insulating material is less likely to adhere to the surface of the compression portion 2. On the other hand, according to the case 17, a heat insulating region (vacuum region) can be formed around the compression portion 2 without being affected by the outer shape of the compression portion 2. Further, the foam-based heat insulator is not suitable for repeated exposure to an environment of extremely low temperature and normal temperature. If a gap exists between the foam heat insulator and the compression portion, liquefied air may permeate therethrough. Moreover, there are also cases where the saturated air evaporates. If the above-described permeation and evaporation are repeated, the foam-based heat insulating material is likely to deteriorate. In addition, when maintenance and installation of the compression portion 2 are performed, it is necessary to remove and install again the foam-based heat insulator. On the other hand, the case 17 can be suitably used for these problems.

Container portion 15 has a housing 17 and a lower inner container support 27A. The housing 17 forms a vacuum region. The lower inner vessel bracket 27A is disposed between the housing 17 and the cylinder 4. An inner peripheral base 29 of the lower tank inner bracket 27A is provided on the cylinder lower surface 4 d. Outer peripheral seat 28 of lower tank inner bracket 27A is provided on the inner surface of case 17. According to the above configuration, the cylinder 4 can be appropriately supported. As a result, vibration caused by the reciprocating motion of the piston 6 can be received.

The reciprocating compressor 1A further includes a casing heat insulator 19. The casing heat insulator 19 is disposed between the cylinder 4 and the casing 17. The cylinder base end portion 4b is connected to the housing base end portion 17 b. The casing insulator 19 is sandwiched between the cylinder base end portion 4b and the casing base end portion 17 b. According to the above configuration, the cylinder 4 and the housing 17 can be thermally insulated from each other. As a result, even when the gas having the extremely low temperature is supplied to the cylinder 4, the influence of the heat of the cylinder 4 can be suppressed from being applied to the housing 17. Therefore, the region where the reciprocating compressor 1A is disposed is further suppressed from being excessively cooled.

The lever driving portion 48 of the pressure relief device 38 provided in the suction valve 36 is disposed on the outer peripheral surface side of the housing 17. According to this structure, the lever driving portion 48 is disposed outside the housing 17. The portion outside the housing 17 is insulated from the compression part 2 by a vacuum region. Therefore, the pressure relief device 38 can be reliably operated without being affected by the heat of the compression portion 2. Specifically, the pressure relief device 38 receives compressed gas for driving the diaphragm. Examples of the compressed gas include compressed air and compressed nitrogen. According to the above configuration, the decompressor 38 is not affected by the heat of the compression section 2. As a result, the compressed air is not liquefied. Therefore, the pressure relief device 38 can be reliably operated.

The reciprocating compressor 1A further includes an intermediate cylindrical portion 18. The intermediate cylindrical portion 18 is disposed between the piston driving portion 3 and the container portion 15. The intermediate cylinder 18 accommodates the piston rod 9. The intermediate cylinder portion 18 forms a first intermediate chamber 53E, a second intermediate chamber 53F, and a rod seal chamber 52R. The first intermediate chamber 53E, the second intermediate chamber 53F, and the rod seal chamber 52R are arranged in this order from the piston driving unit 3 toward the housing 17, as are the first intermediate chamber 53E, the second intermediate chamber 53F, and the rod seal chamber 52R. The internal pressure of the first intermediate chamber 53E is higher than the internal pressures of the second intermediate chamber 53F and the third intermediate chamber.

According to the above configuration, the first intermediate chamber 53E, the second intermediate chamber 53F, and the rod seal chamber 52R are formed between the compression unit 2 and the piston driving unit 3. The internal pressure of the first intermediate chamber 53E provided on the piston driving portion 3 side is higher than the internal pressure of the second intermediate chamber 53F and the rod seal chamber 52R. As a result, the gas leakage from the compression section 2 to the piston driving section 3 can be suppressed by this pressure difference. By suppressing leakage of the extremely low temperature gas, the piston driving unit 3 can be reliably operated.

Three chambers are provided between the compression section 2 and the piston driving section 3. With this configuration, the distance from the compression unit 2 to the piston driving unit 3 can be increased. As a result, the influence of heat of the compression portion 2 is less likely to be exerted on the piston driving portion 3. Therefore, the piston driving unit 3 can be reliably operated.

In the above, the reciprocating compressors 1A, 1B of the present disclosure are explained. However, the reciprocating compressors 1A, 1B of the present disclosure may be implemented in various ways without being limited to the above-described embodiments.

For example, the cylinder block 4 of the reciprocating compressor 1A is not directly fixed to the intermediate cylinder portion 18. A casing heat insulator 19 and a casing base end portion 17b of the casing 17 are sandwiched between the cylinder 4 and the intermediate cylindrical portion 18. For example, the cylinder block 4 of the reciprocating compressor may be fixed to the intermediate cylinder portion 18 without the housing 17. In this case, a heat insulator serving as a heat resistance portion is disposed between the cylinder 4 and the intermediate cylindrical portion 18. In other words, the heat resistor portions are in contact with the cylinder 4 and the intermediate cylinder portion 18, respectively. The structure in which the heat-resistant portion is disposed between the compression portion 2 and the intermediate cylindrical portion 18 may be a structure in which only the heat-resistant portion is interposed between the compression portion 2 and the intermediate cylindrical portion 18. As in the embodiment, the heat-resistant portion and other components (the case base end portion 17b of the case 17) may be interposed between the compression portion 2 and the intermediate cylindrical portion 18.

In the above description, the configuration of supplying the nitrogen gas to the first intermediate chamber 53E is exemplified as the configuration of restricting the movement direction of the gas in the intermediate cylindrical portion 18. The structure for restricting the movement direction of the gas is not limited to this structure. The structure for restricting the movement direction of the gas may be a structure capable of restricting the movement direction of the nitrogen gas by pressure control. For example, instead of supplying nitrogen gas to the first intermediate chamber 53E, nitrogen gas may be supplied to the seal unit 55A. In this configuration, the pressure of the nitrogen gas supplied to the seal unit 55A is also set to be higher than the internal pressure of the second intermediate chamber 53F.

In the above description, the diaphragm 48a driven by compressed gas is exemplified as the driving mechanism of the depressurizer 38. The driving mechanism of the depressurizer 38 is not limited to this structure. For example, as the driving mechanism of the pressure relief device 38, a cylinder driven by compressed gas may be provided instead of the diaphragm 48 a.

Description of reference numerals:

1A, 1B … reciprocating compressor; 2 … compression part; 3 … piston driving part; 4 … cylinders; 6 … piston; 7 … inhalation mechanism; 8 … discharge mechanism; 9 … piston rod; 11 … crankshaft; 12 … driving source; 13 … crankcase; 14 … crosshead; 15 … container portion; 16 … connecting rod; 17 … a housing; 17N … suction cap; 17M … discharge cap; 18 … an intermediate barrel portion; 19 … casing insulation; 21 … cylinder support; 22 … piston rod seal; 23A, 23B, 23C … seal element; 24 … heat insulating ring; 26 … container external support; 27a … lower in-container support; 27B … inner container support; 28 … peripheral pedestals; 29 … inner peripheral pedestal; 31 … elastic part; 32 … pedestal base; 33 … seat connecting part; 34 … expansion joints; 36 … suction valve; 38 … pressure relief; a 48 … lever drive section; 49 … expansion joints; 51 … discharge valve; 52 … front middle barrel; vent 52B, 53B …; 52R … rod seal chamber; 53 … rear middle tube; 53S … supply unit; 53W … dividing wall; 61 … yoke lever; 100 … BOG compression system; 200 … basis; p1, P2 … compression spaces; s … accommodating space.