JP2023027976A - Liquefied gas transfer system - Google Patents

Abstract

To provide a liquefied gas transfer system capable of making effective use of boil-off gas generated from liquefied gas in a simple construction.SOLUTION: The liquefied gas transfer system includes a reciprocating pump device 3 for pressurizing liquefied gas and boil-off gas in a storage tank 1, the reciprocating pump device 3 including a cylinder 14 having a gas pressurizing chamber 10 and a liquid pressurizing chamber 11 inside, a piston 17 arranged in the cylinder 14, and an actuator 18 connected to the piston 17 for applying reciprocating motion to the piston 17, the piston 17 being located between the gas pressurizing chamber 10 and the liquid pressurizing chamber 11, the piston 17 having a gas pressurizing face 21 facing the gas pressurizing chamber 10, and a liquid pressurizing face 22 facing the liquid pressurizing chamber 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquefied gas transfer system for transferring liquefied gas, such as liquefied natural gas (LNG) or liquid hydrogen, stored in a storage tank, in particular a pump for pumping liquefied gas and boil-off gas. It relates to a liquefied gas transfer system including an apparatus.

Natural gas is widely used for thermal power generation and as a raw material for chemicals. Moreover, hydrogen is expected as an energy that does not generate carbon dioxide that causes global warming. Applications of hydrogen for energy include fuel cells and turbine power generation. Since natural gas and hydrogen are in a gaseous state at normal temperature, natural gas and hydrogen are cooled and liquefied for their storage and transportation. Liquefied gases such as liquefied natural gas (LNG) and liquid hydrogen are transported to power plants, hydrogen stations, and the like by trucks.

Hydrogen stations include those that vaporize stored liquid hydrogen, pressurize it with a compressor, and supply hydrogen to fuel cell vehicles, etc., and those that vaporize stored liquid hydrogen, pressurize it with a pump, and then vaporize it to fuel cell vehicles, etc. There are some that supply hydrogen to The latter can increase the pressure of a larger amount of hydrogen than the former, so the entire hydrogen station requires less equipment.

FIG. 10 is a schematic diagram showing an example of a hydrogen station. Liquid hydrogen is transported to a hydrogen station by a vehicle (not shown) and stored in a storage tank 200 . The pump device 201 sends the liquid hydrogen in the storage tank 200 to the evaporator 202 , and the liquid hydrogen is turned into hydrogen gas by the evaporator 202 . The hydrogen gas is sent to the pressure accumulator 203 and the high pressure hydrogen gas is retained in the pressure accumulator 203 . Further, the hydrogen gas is sent to a dispenser 204 and supplied from the dispenser 204 to a fuel cell vehicle or the like.

JP 2008-196590 A

However, in the hydrogen station, vaporized hydrogen (boil-off gas: BOG) is generated due to heat input from the outside to the piping and storage tank 200 and heat input accompanying the operation of the pump device 201 . Since the boil-off gas is almost atmospheric pressure, it is difficult to use it again in the hydrogen station, and it is usually discarded in the air. Methods for reusing the generated boil-off gas include collecting it in a fuel cell and compressing the boil-off gas with a compressor and accumulating it in the system, but both require expensive capital investment. , the problem is that the installation area of the system increases. Such problems can occur not only with liquid hydrogen, but also with other types of liquefied gases such as liquefied natural gas.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a liquefied gas transfer system capable of effectively utilizing boil-off gas generated from liquefied gas with a simple configuration.

In one aspect, a liquefied gas transfer system for transferring liquefied gas in a storage tank, comprising a reciprocating pumping device for pressurizing said liquefied gas and boil-off gas in said holding tank, said reciprocating pumping device comprising: , a cylinder having a gas pressurization chamber and a liquid pressurization chamber therein; a piston arranged in the cylinder; and an actuator connected to the piston for reciprocating the piston, wherein the piston is , the piston is located between the gas pressurizing chamber and the liquid pressurizing chamber, and the piston has a gas pressurizing surface facing the gas pressurizing chamber and a liquid pressurizing surface facing the liquid pressurizing chamber. A liquefied gas transfer system is provided, comprising:

In one aspect, the piston includes a gas pressurizing piston having the gas pressurizing surface and a liquid pressurizing piston having the liquid pressurizing surface, and the reciprocating pump device includes the gas pressurizing piston and the liquid pressurizing surface. a connecting member that connects the pressurizing piston and reciprocally moves the gas pressurizing piston and the liquid pressurizing piston integrally; It further comprises an intermediate chamber located within.
In one aspect, the reciprocating pump device further includes a communication passage for communicating the intermediate chamber and the gas pressurization chamber, and a check valve arranged in the communication passage, wherein the check valve is , to allow unidirectional flow from the intermediate chamber to the gas pressurization chamber.
In one aspect, the cylinder has a boil-off gas inlet communicating with the intermediate chamber.
In one aspect, the communication channel extends through the gas pressurizing piston.
In one aspect, the communication channel is arranged outside the cylinder.
In one aspect, the cylinder has a boil-off gas introduction port that communicates with the gas pressurization chamber.
In one aspect, at least part of the actuator is located within the cylinder.
In one aspect, the location where the actuator is coupled to the piston is within the cylinder.
In one aspect, the reciprocating pump device further includes a relief valve communicating with the intermediate chamber.

In one aspect, the liquefied gas transfer system includes a first discharge line connected to the gas pressurization chamber, a second discharge line connected to the liquid pressurization chamber, and a It further comprises a connected cooling device.
In one aspect, the cooling device is a heat exchanger having a heating channel and a cooling channel adjacent to each other, the heating channel being connected to the first discharge line, and the cooling channel being the It is connected to the second discharge line.
In one aspect, the liquefied gas transfer system further comprises a pressure reducing device connected to the first discharge line and arranged downstream of the cooling device.
In one aspect, the liquefied gas transfer system further comprises a return line extending from the pressure reducing device to the holding tank.

According to the invention, a piston arranged in a cylinder can alternately pressurize a liquefied gas and a boil-off gas. Therefore, there is no need to provide a dedicated compressor for pressurizing the boil-off gas, and the installation area does not increase. The boil-off gas is pressurized by the piston into a supercritical fluid. A supercritical fluid can be reused by cooling it. Further, by reducing the pressure of the cooled supercritical fluid, the supercritical fluid can be made into a gas-liquid mixed fluid, and the liquefied gas can be recovered from the gas-liquid mixed fluid.

1 is a schematic diagram illustrating one embodiment of a liquefied gas transfer system; FIG. 2 is a Mollier diagram showing the state of hydrogen circulating in the liquefied gas transfer system; FIG. FIG. 3 is a schematic diagram showing another embodiment of a liquefied gas transfer system; FIG. 3 is a schematic diagram showing yet another embodiment of a liquefied gas transfer system; FIG. 3 is a schematic diagram showing another embodiment of a reciprocating pump device; FIG. 4 is a schematic diagram showing still another embodiment of a reciprocating pump device; FIG. 4 is a schematic diagram showing still another embodiment of a reciprocating pump device; FIG. 4 is a schematic diagram showing still another embodiment of a reciprocating pump device; FIG. 4 is a schematic diagram showing still another embodiment of a reciprocating pump device; 1 is a schematic diagram showing an example of a hydrogen station; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating one embodiment of a liquefied gas transfer system. The liquefied gas transfer system of the embodiment shown in FIG. 1 is a system for transferring liquid hydrogen as an example of liquefied gas. The present invention is not limited to transfer systems for liquid hydrogen, but can also be applied to transfer systems for other types of liquefied gases such as liquefied natural gas (LNG), liquefied ammonia, liquid nitrogen, liquefied ethylene gas, and liquefied petroleum gas. can. Liquid hydrogen is stored in a storage tank 1 . Most of the hydrogen in the storage tank 1 is in liquid form, but a small amount of heat from the ambient atmosphere is transferred to the liquid hydrogen through the walls of the storage tank 1 . As a result, some of the liquid hydrogen gasifies to form boil-off gas (BOG). Therefore, as shown in FIG. 1, the storage tank 1 contains liquefied gas (liquid hydrogen) and boil-off gas (hydrogen gas).

The liquefied gas transfer system includes a reciprocating pumping device 3 configured to aspirate and separately pressurize both boil-off gas and liquid hydrogen present in the storage tank 1, and couple the reciprocating pumping device 3 and the storage tank 1. It is equipped with a gas transfer line 5 and a liquid transfer line 6 which are connected to each other. The boil-off gas (BOG) in the storage tank 1 is transferred to the reciprocating pumping device 3 through the gas transfer line 5 and the liquid hydrogen in the storage tank 1 is transferred to the reciprocating pumping device 3 through the liquid transfer line 6 . A gas check valve 7 and a liquid check valve 8 are attached to the gas transfer line 5 and the liquid transfer line 6, respectively. These check valves 7 and 8 are configured to allow only one-way flow from the storage tank 1 to the reciprocating pump device 3 .

The reciprocating pump device 3 includes a cylinder 14 having a gas pressurizing chamber 10 and a liquid pressurizing chamber 11 therein, a piston 17 arranged in the cylinder 14 , and connected to the piston 17 to reciprocate the piston 17 within the cylinder 14 . It has an actuator 18 for movement. The piston 17 is positioned between the gas pressurization chamber 10 and the liquid pressurization chamber 11 . The entire actuator 18 is arranged within the cylinder 14 . Therefore, no piston rod extending from the piston 17 to the outside of the cylinder 14 is provided. The actuator 18 of this embodiment is a linear motor including a permanent magnet 18A and a coil 18B, but the specific configuration of the actuator 18 is not limited to this embodiment. For example, actuator 18 may be a hydraulic cylinder, a combination of a crank mechanism and an electric motor, or the like.

The cylinder 14 is a sealed container and has a structure that does not allow leakage of hydrogen introduced therein. The entire piston 17 is located within the cylinder 14 . The piston 17 has a gas pressurizing surface 21 facing the gas pressurizing chamber 10 and a liquid pressurizing surface 22 facing the liquid pressurizing chamber 11 . More specifically, the piston 17 has a gas pressurizing piston 24 having a gas pressurizing surface 21 and a liquid pressurizing piston 25 having a liquid pressurizing surface 22 . The gas pressurizing piston 24 and the liquid pressurizing piston 25 are connected by a connecting member 30, and the gas pressurizing piston 24 and the liquid pressurizing piston 25 reciprocate integrally.

The reciprocating pumping device 3 comprises a seal attached to the side of the piston 17 . More specifically, a first seal 26 is attached to the side surface of the gas pressurizing piston 24 , and a second seal 27 is attached to the side surface of the liquid pressurizing piston 25 . The first seal 26 closes the gap between the side surface of the gas pressurizing piston 24 and the inner surface of the cylinder 14, and the second seal 27 closes the gap between the side surface of the liquid pressurizing piston 25 and the inner surface of the cylinder 14. It has a blocking function.

The reciprocating pump device 3 has an intermediate chamber 32 located within the cylinder 14 . The intermediate chamber 32 is located between the gas pressurizing piston 24 and the liquid pressurizing piston 25 and reciprocates integrally with the gas pressurizing piston 24 and the liquid pressurizing piston 25 . The intermediate chamber 32 is positioned between the gas pressurization chamber 10 and the liquid pressurization chamber 11 . The cylinder 14 has a boil-off gas inlet 33 communicating with the intermediate chamber 32 . A boil-off gas inlet 33 is formed in the wall of the cylinder 14 forming the intermediate chamber 32 . The gas transfer line 5 communicates with the intermediate chamber 32 through the boil-off gas inlet 33 . One end of the gas transfer line 5 is connected to the upper portion of the storage tank 1 , and the other end of the gas transfer line 5 is connected to the boil-off gas inlet 33 of the cylinder 14 and communicates with the intermediate chamber 32 .

The entire actuator 18 is arranged within the cylinder 14 . More specifically, the entire actuator 18 is located within the intermediate chamber 32 . The permanent magnet 18A of the actuator 18 is fixed to the connecting member 30 in the intermediate chamber 32, and the permanent magnet 18A reciprocates integrally with the connecting member 30 and the piston 17. As shown in FIG. A coil 18B of the actuator 18 is fixed inside the cylinder 14 .

The intermediate chamber 32 is positioned between the gas pressurization chamber 10 and the liquid pressurization chamber 11 . The reciprocating pump device 3 further includes a communication passage 35 for communicating the intermediate chamber 32 and the gas pressurizing chamber 10 , and a check valve 36 arranged in the communication passage 35 . In this embodiment, the communication channel 35 is formed in the gas pressurizing piston 24 and extends through the gas pressurizing piston 24 . One end of the communication channel 35 communicates with the intermediate chamber 32 , and the other end of the communication channel 35 communicates with the gas pressurization chamber 10 . The check valve 36 is arranged inside the gas pressurizing piston 24 . The communication channel 35 and the check valve 36 reciprocate integrally with the gas pressurizing piston 24 . The check valve 36 is configured to allow only one-way flow from the intermediate chamber 32 to the gas pressurization chamber 10 .

The cylinder 14 has a liquefied gas inlet 38 communicating with the liquid pressurizing chamber 11 . The liquefied gas inlet 38 is formed in the wall of the cylinder 14 forming the liquid pressurizing chamber 11 . The liquid transfer line 6 communicates with the liquid pressurizing chamber 11 through the liquefied gas inlet 38 . One end of the liquid transfer line 6 is connected to the lower portion of the storage tank 1 , and the other end of the liquid transfer line 6 is connected to the cylinder 14 and communicates with the liquid pressurizing chamber 11 .

The liquefied gas transfer system includes a first discharge line 41 connected to the gas pressurization chamber 10, a second discharge line 42 connected to the liquid pressurization chamber 11, and a A first discharge side check valve 44 and a second discharge side check valve 45 attached to the second discharge line 42 are further provided. The boil-off gas (hydrogen gas) and liquid hydrogen pressurized by the reciprocating pump device 3 are discharged through the first discharge line 41 and the second discharge line 42 . The first discharge-side check valve 44 and the second discharge-side check valve 45 are configured to allow only the flow in the direction out of the reciprocating pump device 3 .

The operation of the reciprocating pump device 3 will be described below. When the piston 17 including the gas pressurizing piston 24 and the liquid pressurizing piston 25 moves within the cylinder 14, the boil-off gas (hydrogen gas) and liquid hydrogen in the storage tank 1 pass through the gas transfer line 5 and the liquid transfer line 6. are introduced into the intermediate chamber 32 and the liquid pressurizing chamber 11 respectively. More specifically, when piston 17 moves downward in FIG. Moving. As a result, the boil-off gas in the storage tank 1 is introduced into the intermediate chamber 32 through the gas transfer line 5 .

When piston 17 moves upward in FIG. 1, liquid hydrogen in storage tank 1 is introduced into liquid pressurization chamber 11 through liquid transfer line 6 . After that, when the piston 17 moves downward in FIG. is introduced into the intermediate chamber 32 through the . At the same time, the liquid hydrogen in the liquid pressurizing chamber 11 is pressurized by the liquid pressurizing piston 25 . Furthermore, when the piston 17 moves upward in FIG. The liquid is introduced into the pressurizing chamber 11 through the .

In this manner, as the piston 17 reciprocates, the boil-off gas and liquid hydrogen are alternately pressurized by the piston 17 and alternately discharged from the cylinder 14 . The pressure in the gas pressurization chamber 10 fluctuates greatly as the piston 17 reciprocates, but the pressure in the intermediate chamber 32 is maintained by the set pressure of the check valve 36 . As a result, the pressure in the storage tank 1 communicating with the intermediate chamber 32 can be adjusted.

When the liquid pressurizing piston 25 pressurizes the liquid hydrogen in the liquid pressurizing chamber 11 , part of the liquid hydrogen in contact with the second seal 27 gasifies into boil-off gas, and the boil-off gas flows into the intermediate chamber 32 . . This boil-off gas is mixed with the boil-off gas introduced from the storage tank 1 in the intermediate chamber 32 and flows into the gas pressurization chamber 10 through the communication passage 35 . Thus, the boil-off gas generated in the cylinder 14 does not leak from the cylinder 14 to the outside, and the boil-off gas can be recovered.

In particular, the entire actuator 18 is located within the cylinder 14 and the location where the actuator 18 is coupled to the piston 17 is within the cylinder 14 . Therefore, a piston rod passing through the cylinder 14 is unnecessary, and a seal for sealing a gap between the piston rod and the cylinder 14 is also unnecessary. Furthermore, the boil-off gas does not leak from the gap between the piston rod and the cylinder 14. - 特許庁

The liquefied gas transfer system further comprises a heat exchanger 50 as a cooling device connected to the first discharge line 41 and the second discharge line 42 . The boil-off gas and liquid hydrogen pressurized by the reciprocating pump device 3 are sent to the heat exchanger 50 through the first discharge line 41 and the second discharge line 42 . The heat exchanger 50 has heating channels 51 and cooling channels 52 adjacent to each other. The heating channel 51 is connected to the first discharge line 41 and the cooling channel 52 is connected to the second discharge line 42 . Within heat exchanger 50 , pressurized boil-off gas flows through heating channel 51 and pressurized liquid hydrogen flows through cooling channel 52 . Heat is exchanged between the pressurized boil-off gas in the heating channel 51 and the pressurized liquid hydrogen in the cooling channel 52 so that the pressurized boil-off gas is cooled and the liquid hydrogen is heated. The heated liquid hydrogen is sent to an evaporator (eg, evaporator 202 shown in FIG. 10) or the like.

In this embodiment, the heat exchanger 50 is provided as a cooling device for cooling the pressurized boil-off gas, but as long as the pressurized boil-off gas can be cooled, the type of cooling device It is not particularly limited. For example, a refrigerator in which a refrigerant circulates may be used as the cooling device.

The liquefied gas transfer system further comprises a pressure reducing device 55 connected to the first discharge line 41 . The decompression device 55 is arranged downstream of the heat exchanger 50 as a cooling device. The decompression device 55 is a device for reducing the pressure of the pressurized and cooled boil-off gas that has passed through the heat exchanger 50 as a cooling device to atmospheric pressure, and its specific configuration is as long as it can exhibit its intended function. is not particularly limited. For example, examples of the decompression device 55 include an expander and a Joule-Thomson valve.

The liquefied gas transfer system further comprises a return line 60 extending from the pressure reducer 55 to the top of the storage tank 1 . When the pressure of the pressurized and cooled boil-off gas is reduced to atmospheric pressure by the decompression device 55, the boil-off gas becomes a gas-liquid mixed fluid. This gas-liquid mixed fluid is returned to the storage tank 1 through the return line 60 . Liquid hydrogen (liquefied gas) contained in the gas-liquid mixed fluid is mixed with liquid hydrogen held in the storage tank 1 . Hydrogen gas contained in the gas-liquid mixed fluid is mixed with boil-off gas (hydrogen gas) held in the storage tank 1 .

In this way, part of the boil-off gas sent from the storage tank 1 to the reciprocating pump device 3 forms liquid hydrogen (liquefied gas) and is recovered in the storage tank 1 . According to this embodiment, part of the boil-off gas that was discarded into the atmosphere in a conventional system can be regenerated into liquefied gas. Also, a piston 17 located within a single cylinder 14 can alternately pressurize liquefied gas and boil-off gas. Therefore, there is no need to provide a dedicated compressor for pressurizing the boil-off gas, and the installation area does not increase.

FIG. 2 is a Mollier diagram showing the state of hydrogen circulating in the liquefied gas transfer system shown in FIG. The vertical axis represents the pressure of hydrogen, and the horizontal axis represents the specific enthalpy of hydrogen. A process from point A to point B in FIG. As a result of this compression step, the boil-off gas is transferred from the gas phase to the supercritical state. The boil-off gas in a supercritical state is hereinafter referred to as a supercritical fluid.

The process from point B to point C in FIG. 2 is a process of cooling the supercritical fluid with a heat exchanger 50 as a cooling device. As a result of this cooling step, the temperature of the supercritical fluid is lowered while the pressure of the supercritical fluid is maintained. The process from point C to point D in FIG. As a result of this decompression process, the supercritical fluid becomes a gas-liquid mixed fluid. The mass ratio of liquid hydrogen (liquefied gas) and hydrogen gas (boil-off gas) in the gas-liquid mixed fluid corresponds to the ratio of lengths L2 and L1 shown in FIG.

As described above, the boil-off gas is pressurized by piston 17 to become a supercritical fluid. A supercritical fluid can be reused by cooling it. Furthermore, by reducing the pressure of the cooled supercritical fluid, the supercritical fluid can be made into a gas-liquid mixed fluid, and the liquefied gas can be recovered from the gas-liquid mixed fluid.

As shown in FIGS. 3 and 4, the decompression device 55 may be omitted. In the embodiment shown in FIG. 3, the boil-off gas (supercritical fluid) pressurized and cooled by the heat exchanger 50 as a cooling device is returned to the storage tank 1 through the return line 60, and contributes to maintaining the pressure of In the embodiment shown in FIG. 4, the boil-off gas (supercritical fluid) pressurized and cooled by the heat exchanger 50 as a cooling device is supplied to a hydrogen station dispenser or pressure accumulator (for example, the dispenser 204 or pressure accumulator shown in FIG. 10). 203), etc., and supplied to a fuel cell vehicle or the like via a dispenser.

FIG. 5 is a schematic diagram showing another embodiment of the reciprocating pump device 3. As shown in FIG. The configuration and operation of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to FIG. In the embodiment shown in FIG. 5, the communication channel 35 is arranged outside the cylinder 14 . A check valve 36 is also located outside the cylinder 14 . One end of the communication channel 35 is connected to the wall of the cylinder 14 forming the intermediate chamber 32 , and the other end of the communication channel 35 is connected to the wall of the cylinder 14 forming the gas pressurization chamber 10 . . As in the embodiment described with reference to FIG. 1, the boil-off gas in the storage tank 1 is introduced into the intermediate chamber 32 as the piston 17 reciprocates, flows through the communication passage 35, and is pressurized. Flow into chamber 10 .

FIG. 6 is a schematic diagram showing still another embodiment of the reciprocating pump device 3. As shown in FIG. The configuration and operation of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to FIG. In the embodiment shown in FIG. 6, a portion of actuator 18 is located within cylinder 14 and another portion is located outside cylinder 14 . Specifically, the actuator 18 includes a permanent magnet 18A fixed to a connecting member 30 connecting the gas pressurizing piston 24 and the liquid pressurizing piston 25, and a coil 18B arranged outside the cylinder 14. . The permanent magnet 18A is arranged in the intermediate chamber 32 of the cylinder 14 and reciprocates integrally with the piston 17 and the connecting member 30 . The coil 18B is positioned outside the permanent magnet 18A.

In the embodiment shown in FIG. 6, the position where the actuator 18 is connected to the piston 17 is also within the cylinder 14 . Therefore, a piston rod passing through the cylinder 14 is unnecessary, and a seal for sealing a gap between the piston rod and the cylinder 14 is also unnecessary. Furthermore, the boil-off gas does not leak from the gap between the piston rod and the cylinder 14. - 特許庁

FIG. 7 is a schematic diagram showing still another embodiment of the reciprocating pump device 3. As shown in FIG. The configuration and operation of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to FIG. In the embodiment shown in FIG. 7 , the cylinder 14 has a boil-off gas introduction port 33 that communicates with the gas pressurization chamber 10 . The boil-off gas introduction port 33 is formed in the wall of the cylinder 14 forming the gas pressurization chamber 10 . The gas transfer line 5 is connected to the boil-off gas inlet 33 . Therefore, the boil-off gas in the storage tank 1 is introduced directly into the gas pressurization chamber 10 through the gas transfer line 5 .

In the embodiment shown in FIG. 7, the boil-off gas in the storage tank 1 is not introduced into the intermediate chamber 32, but otherwise the boil-off gas flow is the same as in the embodiment shown in FIG. The communication channel 35 and the check valve 36 are similarly provided in the embodiment shown in FIG. This is for guiding the hydrogen gas leaking from the liquid pressurizing chamber 11 to the gas pressurizing chamber 10 through the communication channel 35 .

FIG. 8 is a schematic diagram showing still another embodiment of the reciprocating pump device 3. As shown in FIG. The configuration and operation of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to FIG. 7, so redundant description thereof will be omitted. In the embodiment shown in FIG. 8, the reciprocating pump device comprises a relief valve 61 communicating with intermediate chamber 32 . In this embodiment, the communication channel 35 and the check valve 36 are not provided.

The liquid hydrogen that has leaked from the liquid pressurizing chamber 11 to the intermediate chamber 32 through the second seal 27 becomes hydrogen gas, and the pressure in the intermediate chamber 32 rises. The relief valve 61 is configured to open when the pressure in the intermediate chamber 32 exceeds a set value to release the hydrogen gas in the intermediate chamber 32 to the outside of the cylinder 14 .

FIG. 9 is a schematic diagram showing still another embodiment of the reciprocating pump device 3. As shown in FIG. The configuration and operation of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to FIG. In the embodiment shown in FIG. 9 the actuator 18 is arranged outside the cylinder 14 . Piston 17 is connected to actuator 18 by a piston rod 63 that passes through cylinder 14 . The reciprocating pump device 3 has a seal 64 that seals the gap between the piston rod and the cylinder 14 .

The reciprocating pump device 3 of this embodiment can be applied when a very small amount of boil-off gas leakage from the cylinder 14 is allowed.

The embodiments described with reference to FIGS. 1 to 9 can be combined as appropriate. For example, any of the embodiments described with reference to FIGS. 5-9 may be applied to the embodiments described with reference to FIGS. 3 or 4. FIG.

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiments can be made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in its broadest scope in accordance with the technical spirit defined by the claims.

1 storage tank 3 reciprocating pump device 5 gas transfer line 6 liquid transfer line 7 gas check valve 8 liquid check valve 10 gas pressurization chamber 11 liquid pressurization chamber 14 cylinder 17 piston 18 actuator 18A permanent magnet 18B coil 21 gas pressurization surface 22 Liquid pressurizing surface 24 Gas pressurizing piston 25 Liquid pressurizing piston 26 First seal 27 Second seal 30 Connecting member 32 Intermediate chamber 33 Boil-off gas inlet 35 Communication passage 36 Check valve 38 Liquefied gas inlet 41 First discharge line 42 second discharge line 44 first discharge side check valve 45 second discharge side check valve 50 heat exchanger (cooling device)
51 heating channel 52 cooling channel 55 decompression device 60 return line 61 relief valve 63 piston rod 64 seal 200 storage tank 201 pump device 202 evaporator 203 pressure accumulator 204 dispenser

Claims (14)

A liquefied gas transfer system for transferring liquefied gas in a storage tank, comprising:
a reciprocating pumping device for pressurizing the liquefied gas and boil-off gas in the storage tank;
The reciprocating pump device comprises:
a cylinder having therein a gas pressurization chamber and a liquid pressurization chamber;
a piston disposed within the cylinder;
an actuator connected to the piston for reciprocating the piston;
The piston is positioned between the gas pressurization chamber and the liquid pressurization chamber,
The liquefied gas transfer system, wherein the piston has a gas pressurization surface facing the gas pressurization chamber and a liquid pressurization surface facing the liquid pressurization chamber. The piston has a gas pressurizing piston having the gas pressurizing surface and a liquid pressurizing piston having the liquid pressurizing surface,
The reciprocating pump device comprises:
a connecting member that connects the gas pressurizing piston and the liquid pressurizing piston and reciprocates the gas pressurizing piston and the liquid pressurizing piston together;
2. The liquefied gas transfer system of claim 1, further comprising an intermediate chamber positioned within said cylinder and between said gas pressurizing piston and said liquid pressurizing piston. The reciprocating pump device comprises:
a communication channel that communicates between the intermediate chamber and the gas pressurization chamber;
further comprising a check valve arranged in the communication channel,
3. The liquefied gas transfer system of claim 2, wherein the check valve is configured to allow unidirectional flow from the intermediate chamber to the gas pressurization chamber. 4. The liquefied gas transfer system of claim 3, wherein said cylinder has a boil-off gas inlet communicating with said intermediate chamber. 4. The liquefied gas transfer system according to claim 3, wherein said communication channel extends through said gas pressurizing piston. 4. The liquefied gas transfer system according to claim 3, wherein said communication channel is arranged outside said cylinder. 4. The liquefied gas transfer system according to any one of claims 1 to 3, wherein said cylinder has a boil-off gas introduction port communicating with said gas pressurization chamber. 8. A liquefied gas transfer system according to any preceding claim, wherein at least part of the actuator is located within the cylinder. 9. The liquefied gas transfer system of claim 8, wherein the location where the actuator is coupled to the piston is within the cylinder. 3. The liquefied gas transfer system of claim 2, wherein said reciprocating pumping device further comprises a relief valve communicating with said intermediate chamber. a first discharge line connected to the gas pressurization chamber;
a second discharge line connected to the liquid pressurizing chamber;
11. The liquefied gas transfer system of any one of claims 1-10, further comprising a cooling device connected to the first discharge line. the cooling device is a heat exchanger having a heating channel and a cooling channel adjacent to each other;
12. The liquefied gas transfer system of claim 11, wherein said heating channel is connected to said first discharge line and said cooling channel is connected to said second discharge line. 12. The liquefied gas transfer system of claim 11, further comprising a pressure reducing device connected to said first discharge line and located downstream of said cooling device. 14. The liquefied gas transfer system of claim 13, further comprising a return line extending from said pressure reducing device to said holding tank.

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