Energy utilization system

Abstract

To provide an energy utilization system that can improve energy efficiency.SOLUTION: An energy utilization system comprises: a liquefaction device for exchanging heat between liquefied hydrogen and first gas to vaporize the liquefied hydrogen, and liquefying the first gas by cold of the liquefied hydrogen to generate liquefied gas; and a heat engine for exchanging heat between hydrogen gas heat-exchanged with the first gas in the liquefaction device, and working fluid enclosed therein to increase the temperature of the hydrogen gas, and to be cooled by cold of the hydrogen gas. The liquefaction device increases the temperature of the hydrogen gas to the boiling point of the working fluid or higher by exchanging heat with the first gas.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to an energy utilization system.

Background Art

[0002] In recent years, there has been a movement to actively utilize liquefied hydrogen towards the realization of a hydrogen society. As a facility that utilizes liquefied hydrogen, for example, the hydrogen supply station described in Patent Document 1 can be cited. This hydrogen supply station effectively treats carbon dioxide gas by utilizing the cold heat of liquid hydrogen.

[0003] Also, liquefied hydrogen is used for driving a gas turbine. In this case, liquefied hydrogen is burned in the gas turbine. However, in order to burn liquefied hydrogen, it is necessary to raise the temperature of liquefied hydrogen at an extremely low temperature (melting point is about -259°C, boiling point is about -253°C) and vaporize it. In order to vaporize liquefied hydrogen, a method of heat exchanging liquefied hydrogen with the atmosphere or seawater is taken.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when heat exchanging liquefied hydrogen with the atmosphere or seawater, a large amount of cold heat is discharged, and it has been an issue that the energy efficiency is poor.

[0006] This disclosure has been made to solve the above problems, and an object thereof is to provide an energy utilization system capable of improving energy efficiency.

Means for Solving the Problems

[0007] To solve the above problems, the energy utilization system according to this disclosure comprises a liquefaction device that exchanges heat between liquefied hydrogen and a first gas to vaporize liquid hydrogen and liquefy the first gas by the coldness of the liquid hydrogen to generate liquefied gas, and a heat engine that exchanges heat between the hydrogen gas after heat exchange with the first gas in the liquefaction device and a working fluid sealed inside to raise the temperature of the hydrogen gas and cool it with the coldness of the hydrogen gas, wherein the liquefaction device raises the temperature of the hydrogen gas to above the boiling point of the working fluid by heat exchange with the first gas. [Effects of the Invention]

[0008] According to the energy utilization system of this disclosure, energy efficiency can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is an overall configuration diagram of an energy utilization system according to an embodiment of this disclosure. [Figure 2] This is an overall configuration diagram of a cooling and heating equipment according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] (Configuration of the energy utilization system) Hereinafter, the energy utilization system 100 according to the embodiment of this disclosure will be described with reference to Figures 1 and 2. As shown in Figure 1, the energy utilization system 100 comprises a supply source 1, a liquefied hydrogen base 2, a hydrogen gas turbine power generation system 3, a steam turbine power generation system 15, a compressor 4, a flare stack 5, and a return gas blower 6. Each component of the energy utilization system 100 is connected by piping L, forming a single cycle. Piping L includes a liquid pipe L1 and a gas pipe L2.

[0011] (source) Source 1 is, for example, a liquid hydrogen carrier 1a that transports liquefied hydrogen A1. The liquid hydrogen carrier 1a is moored, for example, at the mouth of a bay near the liquefied hydrogen base 2, which will be described later. The liquid hydrogen carrier 1a stores and transports liquefied hydrogen A1, for example, that is produced overseas using LNG (Liquefied Natural Gas).

[0012] (Liquefied hydrogen base) The liquefied hydrogen base 2 is equipped with a liquid water tank 7, a booster pump 8, and a cooling / heating equipment 9. The liquid water tank 7 is connected to the supply source 1 by a liquid pipe L1. Liquid hydrogen A1 supplied from the supply source 1 is stored in the liquid water tank 7. The liquid water tank 7 is connected to the booster pump 8 by the liquid pipe L1.

[0013] The booster pump 8 pressurizes the liquefied hydrogen A1 supplied from the liquid water tank 7. The booster pump 8 is connected to the refrigeration equipment 9 by a liquid pipe L1. The liquefied hydrogen A1 pressurized by the booster pump 8 is heated to approximately -253°C, near its melting point.

[0014] (Cold heat utilization equipment) The cooling and heat utilization equipment 9 vaporizes liquefied hydrogen A1 to produce hydrogen gas A2, and also utilizes the cooling energy of the liquefied hydrogen A1 produced in the process. Details of the configuration of the cooling and heat utilization equipment 9 will be described later.

[0015] (Hydrogen gas turbine power generation system) The hydrogen gas turbine power generation system 3 is connected to the cooling equipment 9 by a gas pipe L2. The hydrogen gas turbine power generation system 3 comprises a hydrogen gas turbine 3a and a generator 3b. The hydrogen gas turbine 3a is driven by burning hydrogen gas A2 produced in the cooling equipment 9. The generator 3b is driven by the driving force of the hydrogen gas turbine 3a and generates electricity.

[0016] A large amount of heat is exhausted from the hydrogen gas turbine power generation system 3. The exhaust heat generated in the hydrogen gas turbine 3a (about 500°C to 600°C) is utilized by the turbine generator 13 described later and the steam turbine power generation system 15 provided downstream of the hydrogen gas turbine 3a.

[0017] The steam turbine power generation system 15 includes a steam turbine 15a and a generator 15b. The steam turbine 15a is driven by utilizing the exhaust heat of the hydrogen gas turbine 3a. The generator 15b is driven by the driving force of the steam turbine 15a to generate electricity. The exhaust heat of the steam turbine power generation system 15 is utilized by the heat engine 21 described later.

[0018] A part of the hydrogen gas A2 generated in the cold heat utilization facility 9 described above is returned to the supply source 1 through the gas pipe L2. Hereinafter, the gas pipe L2 that returns a part of the hydrogen gas A2 and the combustion gas to the supply source 1 is referred to as the return pipe L3. In this return pipe L3, for example, a compressor 4, a flare stack 5, and a return gas blower 6 are arranged in order from the upstream side. The compressor 4 boosts the pressure of the hydrogen gas A2 flowing through the return pipe L3. The flare stack 5 burns the surplus gas flowing through the return pipe L3 to render it harmless and discharges it into the atmosphere. The return gas blower 6 sends the hydrogen gas A2 from within the liquefied hydrogen base 2 to the supply source 1 to suppress the pressure drop in the gas phase region of the supply source 1. In the illustrated example, the return pipe L3 is connected to the gas phase region of the liquid water tank 7 by another gas pipe L2 between the flare stack 5 and the return gas blower 6. These various devices and facilities arranged in the return pipe L3 are merely examples.

[0019] (Configuration of the cold heat utilization facility) Next, the configuration of the cold heat utilization facility 9 will be mainly described with reference to FIG. 2. The cold heat utilization facility 9 cascades and utilizes the cold heat of the liquefied hydrogen A1 supplied from the supply source 1 in stages. The cold heat utilization facility 9 of this embodiment has a two-stage configuration including a first facility 10 and a second facility 20.

[0020] (The first facility) The first facility 10 utilizes the cold heat of the liquefied hydrogen A1 supplied from the supply source 1. In the case of this embodiment, the first facility 10 utilizes the cold heat in the first temperature range from -253°C to -180°C of the liquefied hydrogen A1. The first facility 10 includes a liquefaction device 11, a tank 12, and a turbine generator 13.

[0021] (Liquefaction device) The liquefaction device 11 is supplied with the liquefied hydrogen A1 pressurized by the booster pump 8. The temperature of the liquefied hydrogen A1 supplied to the liquefaction device 11 is approximately -253°C near the boiling point. Also, a first gas A3 is supplied to the liquefaction device 11 from the outside. The liquefaction device 11 exchanges heat between the liquefied hydrogen A1 and the first gas A3 to vaporize the liquid hydrogen. The liquefaction device 11 raises the temperature of the hydrogen gas A2 to above the boiling point of the working fluid A5 described later by heat exchange with the first gas A3. In the case of this embodiment, the liquefied hydrogen A1 is heated to about -180°C by the liquefaction device 11. As a result, the liquefied hydrogen A1 vaporizes to generate the hydrogen gas A2.

[0022] On the other hand, the liquefaction device 11 liquefies the first gas A3 by the cold heat of the liquid hydrogen to generate a liquefied gas A4. In this embodiment, the first gas A3 is air, and the liquefaction device 11 exchanges heat between the liquefied hydrogen A1 and air to generate liquefied air. The liquefaction device 11 takes in air as the first gas A3 from the atmosphere and generates liquefied air by the driving power supplied from the outside. The liquefaction device 11 of this embodiment is a general industrial air liquefaction device. The liquefaction device 11 is connected to the tank 12 by a liquid pipe L1.

[0023] (Tank) The tank 12 stores the liquefied gas A4 generated by the liquefaction device 11. The tank 12 is a so-called heat-insulated tank and can store the generated liquefied gas A4 in a liquid phase state. The tank 12 is in contact with the turbine generator 13.

[0024] (Turbine generator) The turbine generator 13 is supplied with liquefied gas A4 from the tank 12. The turbine generator 13 is driven by the liquefied gas A4 stored in the tank 12. The turbine generator 13 is also connected to the hydrogen gas turbine power generation system 3 and can utilize the waste heat of the hydrogen gas turbine power generation system 3. In this embodiment, the turbine generator 13 is driven by heating the liquefied gas A4 using the waste heat of the hydrogen gas turbine power generation system 3 and using the expansion pressure generated at that time. The liquefied gas A4 used to drive the turbine generator 13 becomes a gas and is exhausted into the atmosphere. A second facility 20 is provided downstream of the first facility 10 described above.

[0025] (Second equipment) The second equipment 20 further utilizes the cold energy after it has been used by the first equipment 10. In this embodiment, the second equipment 20 utilizes the cold energy of liquefied hydrogen A1 in a second temperature range from -180°C to near ambient temperature (for example, 0°C). The second equipment 20 comprises a heat engine 21 and a regenerative heat exchanger 22.

[0026] (Heat engine) The heat engine 21 is connected to the liquefaction device 11 by a gas pipe L2. Working fluid A5 is sealed inside the heat engine 21. In this embodiment, working fluid A5 is air, and the heat engine 21 exchanges heat between the working fluid A5 and the hydrogen gas A2, which has undergone heat exchange with the first gas A3 in the liquefaction device 11, thereby raising the temperature of the hydrogen gas A2. In this embodiment, the heat engine 21 raises the temperature of the hydrogen gas A2 to around 0°C.

[0027] On the other hand, the heat engine 21 is cooled by the cold energy of hydrogen gas A2. In other words, hydrogen gas A2 is used to cool the heat engine 21. This cools the working fluid A5 sealed inside the heat engine 21. In addition to the cold energy of hydrogen gas A2, the heat engine 21 also utilizes the waste heat from the hydrogen gas turbine power generation system 3 via the steam turbine power generation system 15.

[0028] The heat engine 21 in this embodiment is a Stirling engine 21a. The heat engine 21 includes a cooling section 23, a heating section 24, a fin structure 25, and an operating section 26.

[0029] (cooling section) The cooling unit 23 is connected to the liquefaction device 11 by a gas pipe L2. Hydrogen gas A2 is supplied to the cooling unit 23 from the liquefaction device 11. The cooling unit 23 has a cooling chamber 23a and a cooling piston 23b. The cooling chamber 23a is covered by the cooling piston 23b and filled with working fluid A5. The cooling unit 23 performs heat exchange between the working fluid A5 in the cooling chamber 23a and the hydrogen gas A2, cooling the working fluid A5 with the coldness of the hydrogen gas A2. As a result, the working fluid A5 in the cooling chamber 23a condenses, and the cooling piston 23b moves.

[0030] (heating part) The heating unit 24 is connected to the steam turbine power generation system 15. The heating unit 24 is supplied with waste heat from the steam turbine power generation system 15. The steam turbine power generation system 15 supplies the heating unit 24 with waste heat (approximately 200°C) from the steam turbine 15a, which is driven by the waste heat of the hydrogen gas turbine 3a. In other words, in this embodiment, the heating unit 24 utilizes the waste heat of the hydrogen gas turbine power generation system 3 via the steam turbine power generation system 15. The heating unit 24 has a heating chamber 24a and a heating piston 24b. The heating chamber 24a is covered by the heating piston 24b and filled with working fluid A5. The heating unit 24 heats the working fluid A5 in the heating chamber 24a with waste heat from the steam turbine power generation system 15. As a result, the working fluid A5 in the heating chamber 24a expands, and the heating piston 24b moves. Furthermore, the heating chamber 24a is connected to the cooling chamber 23a, and the working fluid A5 can flow between the cooling chamber 23a and the heating chamber 24a. This flow of working fluid A5 moves the cooling piston 23b and the heating piston 24b, driving the heat engine 21.

[0031] (Fin structure) The fin structure 25 is provided in the region where heat exchange takes place with the working fluid A5 of the heat engine 21. The fin structure 25 increases the surface area for heat exchange in the heat engine 21 (hereinafter referred to as the heat transfer area), thereby improving the heat transfer performance of the heat engine 21. The fin structure 25 is made of graphene. In this embodiment, the fin structure 25 is provided in both the cooling section 23 and the heating section 24. The fin structure 25 in the cooling section 23 is referred to as the cooling-side fin structure 25a, and the fin structure 25 in the heating section 24 is referred to as the heating-side fin structure 25b.

[0032] The cooling fin structure 25a is provided on the outer surface of the cooling chamber 23a. Hydrogen gas A2 supplied from the liquefaction device 11 is supplied to the cooling fin structure 25a. The cooling fin structure 25a promotes heat exchange between the hydrogen gas A2 and the working fluid A5 in the cooling chamber 23a.

[0033] The heating-side fin structure 25b is provided on the outer surface of the heating chamber 24a. Gas containing waste heat from the steam turbine power generation system 15 is supplied to the heating-side fin structure 25b. The heating-side fin structure 25b facilitates heat exchange between these gases and the working fluid A5 in the heating chamber 24a.

[0034] (Operating part) The operating unit 26 operates by the condensation and expansion of the working fluid A5 in the cooling unit 23 and the heating unit 24. In this embodiment, the operating unit 26 is a generator. The operating unit 26 is connected to the cooling piston 23b of the cooling unit 23 and the heating piston 24b of the heating unit 24, and operates by the interlocking action of the cooling piston 23b and the heating piston 24b, generating electricity with the resulting power.

[0035] The heat engine 21 described above is connected to the hydrogen gas turbine power generation system 3 via a gas pipe L2 in the cooling section 23. Hydrogen gas A2 (approximately 0°C) that has undergone heat exchange with the working fluid A5 in the heat engine 21 is sent to the hydrogen gas turbine power generation system 3. Furthermore, a regenerative heat exchanger 22 is provided between the heat engine 21 and the hydrogen gas turbine power generation system 3.

[0036] (Regenerative heat exchanger) The regenerative heat exchanger 22 raises the temperature of hydrogen gas A2 to approximately ambient temperature. The hydrogen gas A2 heated in the regenerative heat exchanger 22 is sent to the hydrogen gas turbine power generation system 3 and used to drive the hydrogen gas turbine power generation system 3.

[0037] (Effects and Benefits) The energy utilization system 100 with the above configuration provides the following effects.

[0038] In this embodiment, the energy utilization system 100 comprises a liquefaction device 11 and a heat engine 21. The liquefaction device 11 exchanges heat between liquid hydrogen A1 and a first gas A3, vaporizing the liquid hydrogen and simultaneously liquefying the first gas A3 with the cold energy of the liquid hydrogen to produce liquefied gas A4. The heat engine 21 exchanges heat between the hydrogen gas A2, which has undergone heat exchange with the first gas A3 in the liquefaction device 11, and the working fluid A5 sealed inside, raising the temperature of the hydrogen gas A2 and cooling it with the cold energy of the hydrogen gas A2. Furthermore, the liquefaction device 11 raises the temperature of the hydrogen gas A2 to above the boiling point of the working fluid A5 through heat exchange with the first gas A3.

[0039] As a result, the energy utilization system 100 can generate liquefied gas A4 by cascading the cold energy of liquefied hydrogen A1 in stages, and at the same time drive the heat engine 21. Therefore, the cold energy of liquefied hydrogen A1 can be utilized efficiently, and energy efficiency can be improved.

[0040] For example, in this embodiment, if the heat engine 21 is a Stirling engine 21a with working fluid A5 sealed inside, it is necessary to avoid the working fluid A5 (air in this embodiment) condensing and hindering the operation of the heat engine 21. In other words, it is necessary to avoid the temperature falling below the melting point of air and causing the heat engine 21 to freeze. For these reasons, the temperature of the hydrogen gas A2 used to cool the air is limited to above the boiling point of air. The boiling points of oxygen and nitrogen, the main components of air, are approximately -183°C and -196°C, respectively, so the boiling point of air is between -196°C and -183°C. In this embodiment, the hydrogen gas A2 is heated to -180°C, above the boiling point of air, by the liquefaction device 11, so the hydrogen gas A2 supplied to the heat engine 21 does not condense the air in the heat engine 21 and hinder its operation. Thus, according to this embodiment, the cold energy of liquefied hydrogen A1 can be efficiently utilized without hindering the operation of the heat engine 21.

[0041] In this embodiment, both the first gas A3 and the working fluid A5 are air, and the liquefaction device 11 generates liquefied air by exchanging heat between liquefied hydrogen A1 and air.

[0042] Air is readily available. Therefore, according to this embodiment, the cost of the energy utilization system 100 can be reduced. In addition, the liquefied gas A4 produced in the liquefaction device 11 is liquefied air. In the conventional method of producing liquefied air by cryogenic separation, a large amount of electricity is required. However, in this embodiment, since liquefied air can be produced using the cold energy of the liquefied hydrogen A1 that would otherwise be exhausted, the electricity costs associated with cryogenic separation are eliminated.

[0043] Furthermore, the generated liquefied air has various uses. For example, it can be sold externally, or it can be purified and used as a raw material gas. For instance, the generated liquefied air can be separated into liquid oxygen and liquid nitrogen for industrial use. It can also be used for liquefied air rocket propulsion. In this way, by utilizing the generated liquefied air, overall costs can be reduced.

[0044] In this embodiment, the energy utilization system 100 further includes a hydrogen gas turbine power generation system 3 that is driven by burning hydrogen gas A2 after it has undergone heat exchange with the working fluid A5 in the heat engine 21. The heat engine 21 utilizes the cold energy of the hydrogen gas A2 as well as the waste heat from the hydrogen gas turbine power generation system 3.

[0045] Thus, according to this embodiment, the heat engine 21 can be driven by utilizing the waste heat from the hydrogen gas turbine power generation system 3, which would otherwise be discarded. This further improves energy efficiency. Furthermore, in this embodiment, the heat engine 21 utilizes the waste heat of the hydrogen gas turbine power generation system 3 via the steam turbine power generation system 15. This allows the waste heat of the hydrogen gas turbine 3a (approximately 500°C to 600°C) to be used to drive the steam turbine 15a, and then the waste heat of the steam turbine 15a (approximately 200°C) to be directed to the heat engine 21. This allows the waste heat of the hydrogen gas turbine power generation system 3 to be cooled to a temperature suitable for driving the heat engine 21 before being directed to the heat engine 21. Therefore, the waste heat of the hydrogen gas turbine power generation system 3 can be utilized in two stages, through the steam turbine power generation system 15 and the heat engine 21, thereby improving energy efficiency. Furthermore, since the waste heat at approximately 200°C is effective as a high-temperature heat source for the low-temperature hydrogen in the heat engine 21 as in this embodiment, the heat engine 21 can be driven efficiently.

[0046] In this embodiment, the energy utilization system 100 further comprises a tank 12 and a turbine generator 13. The tank 12 stores the liquefied gas A4 produced by the liquefaction device 11. The turbine generator 13 is driven by the liquefied gas A4 stored in the tank 12.

[0047] This allows for the use of liquefied gas A4 stored in tank 12 to generate electricity. Therefore, when the amount of electricity generated fluctuates (for example, in solar power generation, when the amount of electricity generated decreases due to shorter daylight hours), the amount of electricity generated can be compensated for. Thus, energy efficiency can be further improved.

[0048] In this embodiment, the heat engine 21 has a fin structure 25 made of graphene in the region where heat exchange is performed with the working fluid A5.

[0049] Graphene has a higher thermal conductivity compared to metals such as iron. Therefore, according to this embodiment, the heat transfer performance of the heat engine 21 can be improved. Thus, energy efficiency can be further improved.

[0050] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. In the above embodiment, the heat engine 21 is described as a Stirling engine 21a, but it is not limited to this. The heat engine 21 may be, for example, an engine utilizing a Brayton cycle.

[0051] In the above embodiment, the first gas A3 and the working fluid A5 were both air, but this is not the only option. The first gas A3 and the working fluid A5 may be oxygen, nitrogen, or neon. Furthermore, the first gas A3 and the working fluid A5 do not need to be exactly the same.

[0052] In the above embodiment, the case in which the cooling and heating equipment 9 has a two-stage configuration comprising a first equipment 10 and a second equipment 20 has been described, but it is not limited to this. The cooling and heating equipment 9 may be configured in three or more stages. For example, the first equipment 10 may be further divided into multiple stages, and the second equipment 20 may be further divided into multiple stages.

[0053] In the above embodiment, the case in which the steam turbine power generation system 15 is located downstream of the hydrogen gas turbine power generation system 3 was described, but the steam turbine power generation system 15 is not necessarily required. In this case, the waste heat (approximately 500°C to 600°C) from the hydrogen gas turbine power generation system 3 is supplied directly to the heat engine 21.

[0054] <Note> The energy utilization system 100 described in each embodiment can be understood, for example, as follows:

[0055] (1) The energy utilization system 100 according to the first embodiment comprises a liquefaction device 11 that exchanges heat between liquid hydrogen A1 and a first gas A3 to vaporize liquid hydrogen and liquefy the first gas A3 by the cold energy of the liquid hydrogen to produce liquefied gas A4, and a heat engine 21 that exchanges heat between the hydrogen gas A2 after heat exchange with the first gas A3 in the liquefaction device 11 and a working fluid A5 sealed inside to raise the temperature of the hydrogen gas A2 and is cooled by the cold energy of the hydrogen gas A2, wherein the liquefaction device 11 raises the temperature of the hydrogen gas A2 to above the boiling point of the working fluid A5 by heat exchange with the first gas A3.

[0056] As a result, the energy utilization system 100 can generate liquefied gas A4 by utilizing the cold energy of liquefied hydrogen A1 in a stepwise cascading manner, and at the same time drive the heat engine 21.

[0057] (2) The energy utilization system 100 of the second embodiment is the energy utilization system 100 according to embodiment (1), wherein the first gas A3 and the working fluid A5 are both air, and the liquefaction device 11 may generate liquefied air by exchanging heat between liquefied hydrogen A1 and air.

[0058] Air is readily available. Therefore, according to this embodiment, the cost of the energy utilization system 100 can be reduced. In addition, the liquefied gas A4 produced in the liquefaction device 11 is liquefied air. The liquefied air can be sold externally, or it can be purified and used as a raw material gas. Therefore, by utilizing the produced liquefied air, the overall cost can be reduced.

[0059] (3) The third embodiment of the energy utilization system 100 is an energy utilization system 100 according to embodiment (1) or (2), further comprising a hydrogen gas turbine power generation system 3 that is driven by burning hydrogen gas A2 after heat exchange with the working fluid A5 in the heat engine 21, and the heat engine 21 may utilize the waste heat of the hydrogen gas turbine power generation system 3 in addition to the cold energy of the hydrogen gas A2.

[0060] This will allow for even greater energy efficiency.

[0061] (4) The fourth embodiment of the energy utilization system 100 is an energy utilization system 100 according to any one embodiment of (1) to (3), which may further include a tank 12 for storing the liquefied gas A4 produced by the liquefaction device 11, and a turbine generator 13 driven by the liquefied gas A4 stored in the tank 12.

[0062] This allows for the use of liquefied gas A4 stored in tank 12 to generate electricity. Therefore, if the amount of electricity generated fluctuates, the amount of electricity generated can be compensated for.

[0063] (5) The fifth embodiment of the energy utilization system 100 is an energy utilization system 100 according to any one embodiment of (1) to (4), wherein the heat engine 21 may have a fin structure 25 made of graphene in the region in which the working fluid A5 is subjected to heat exchange.

[0064] Graphene has a higher thermal conductivity compared to metals such as iron. Therefore, according to this embodiment, the heat transfer performance of the heat engine 21 can be improved. [Explanation of symbols]

[0065] 1…Supply source, 1a…Liquid water carrier, 2…Liquid hydrogen base, 3…Hydrogen gas turbine power generation system, 3a…Hydrogen gas turbine, 3b…Generator, 4…Compressor, 5…Flare stack, 6…Return gas blower, 7…Liquid water tank, 8…Booster pump, 9…Cold energy utilization equipment, 10…First equipment, 11…Liquefaction device, 12…Tank, 13…Turbine generator, 15…Steam turbine power generation system, 15a…Steam turbine, 15b…Generator, 20…Second equipment, 21…Heat engine, 21a ...Stirling engine, 22...Regenerative heat exchanger, 23...Cooling section, 23a...Cooling chamber, 23b...Cooling piston, 24...Heating section, 24a...Heating chamber, 24b...Heating piston, 25...Fin structure, 25a...Cooling side fin structure, 25b...Heating side fin structure, 26...Operating section, 100...Energy utilization system, A1...Liquefied hydrogen, A2...Hydrogen gas, A3...First gas, A4...Liquefied gas, A5...Working fluid, L...Piping, L1...Liquid pipe, L2...Gas pipe, L3...Return pipe

Claims

1. A liquefaction apparatus that generates liquefied gas by exchanging heat between liquid hydrogen and a first gas, vaporizing the liquid hydrogen, and liquefying the first gas with the cold energy of the liquid hydrogen, A heat engine is provided in which the hydrogen gas, after heat exchange with the first gas in the liquefaction device, is heated and cooled by the cold energy of the hydrogen gas by exchanging heat with the working fluid sealed inside, thereby raising the temperature of the hydrogen gas. Equipped with, The liquefaction device is an energy utilization system that raises the temperature of hydrogen gas to above the boiling point of the working fluid by heat exchange with the first gas.

2. The first gas and the working fluid are both air. The energy utilization system according to claim 1, wherein the liquefaction device generates liquefied air by exchanging heat between liquefied hydrogen and air.

3. The system further comprises a hydrogen gas turbine power generation system that is driven by burning hydrogen gas after heat exchange has been performed with the working fluid in the heat engine, The energy utilization system according to claim 1 or 2, wherein the heat engine utilizes waste heat from the hydrogen gas turbine power generation system in addition to the cold energy of hydrogen gas.

4. A tank for storing the liquefied gas produced by the liquefaction device, A turbine generator driven by liquefied gas stored in the aforementioned tank, The energy utilization system according to claim 1 or 2, further comprising:

5. The energy utilization system according to claim 1 or 2, wherein the heat engine has a fin structure made of graphene in the region where heat exchange is performed with the working fluid.

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