Cold heat recovery system and ship or floating body

Abstract

To provide a cold heat recovery system and a ship or a floating body with the cold heat recovery system capable of increasing turbine output in the cold heat recovery system as a whole.SOLUTION: A cold heat recovery system includes: a first cold heat recovery cycle including a first expansion turbine and circulating a first heat medium; a second cold heat recovery cycle including a second expansion turbine and circulating a second heat medium; a first heat exchanger provided on the downstream side of the first expansion turbine on the first cold heat recovery cycle and transferring cold heat energy from a first fuel to the first heat medium; a second heat exchanger transferring cold heat energy from a second fuel to the first fuel flowing on the downstream side of the first heat exchanger and re-liquefying the first fuel; and a third heat exchanger provided on the downstream side of the second expansion turbine on the second cold heat recovery cycle and transferring cold heat energy to the second heat medium from the first fuel flowing on the downstream side of the second heat exchanger.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a cold energy recovery system for recovering cold energy from fuel, and to a ship or floating body equipped with the cold energy recovery system. [Background technology]

[0002] Methods have been proposed for recovering and utilizing the cold energy of low-temperature liquid fuels such as liquefied natural gas (LNG).

[0003] Patent Document 1 describes a floating facility equipped with a power generation device that generates electricity using LNG cryogenics. This power generation device includes a thermodynamic cycle that uses a heat transfer medium as a working fluid, and generates electricity using a generator connected to an expansion turbine driven by the heat transfer medium (working fluid) flowing through a circuit. In this thermodynamic cycle, engine cooling water, seawater, or the like is used as a high-temperature heat source that exchanges heat with the heat transfer medium in an evaporator, and LNG is used as a low-temperature heat source that exchanges heat with the heat transfer medium in a condenser. After being vaporized (regasified) in the condenser, the LNG is supplied to equipment that uses natural gas as fuel, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-147221 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, it has been proposed to use liquid fuels other than LNG, such as liquid hydrogen (LH2), as fuel for ships, etc., and it is conceivable to use multiple liquid fuels, such as LNG and liquid hydrogen, in combination on ships, etc. In this way, when using two types of liquid fuels in combination, it is desirable to recover the cryogenic energy of the liquid fuels while efficiently vaporizing these two types of liquid fuels.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a cold heat recovery system that can increase the overall output of the turbines in the cold heat recovery system, and a ship or floating body equipped with the cold heat recovery system. [Means for solving the problem]

[0007] A cold energy recovery system according to at least one embodiment of the present invention includes: a first fuel tank configured to store a first fuel in a liquid state; a second fuel tank configured to store a second fuel in a liquid state having a lower liquefaction temperature than the first fuel; a first fuel supply line for delivering the first fuel extracted from the first fuel tank; a second fuel supply line for delivering the second fuel extracted from the second fuel tank; A first refrigeration cycle configured to circulate a first heat medium, the first refrigeration cycle including a first expansion turbine for expanding the first heat medium in a gaseous state provided on the first refrigeration cycle; a first heat exchanger provided downstream of the first expansion turbine in the first cold energy recovery cycle and configured to transfer cold energy from the first fuel flowing through the first fuel supply line to the first heat medium; a second heat exchanger provided on the first fuel supply line downstream of the first heat exchanger and configured to transfer cold energy from the second fuel flowing in the second fuel supply line to the first fuel flowing in the first fuel supply line; A second refrigeration cycle configured to circulate a second heat medium, the second refrigeration cycle including a second expansion turbine for expanding the second heat medium in a gaseous state provided on the second refrigeration cycle; and a third heat exchanger provided downstream of the second expansion turbine in the second cold energy recovery cycle and configured to transfer cold energy from the first fuel flowing downstream of the second heat exchanger in the first fuel supply line to the second heat medium.

[0008] A ship or a floating vessel according to at least one embodiment of the present invention includes: The cold heat recovery system is provided. [Effects of the Invention]

[0009] According to at least one embodiment of the present invention, there is provided a cold recovery system capable of increasing the overall output of turbines in the cold recovery system, and a ship or floating body including the cold recovery system. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 2] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 3] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 4] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 5] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 6] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 7] 1 is a schematic diagram of a cold energy recovery system according to an embodiment. [Figure 8] 1 is a schematic diagram of a ship or floating body equipped with a cold energy recovery system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0012] (fuel tank, fuel supply line) 1 to 7 are schematic diagrams of a cold energy recovery system according to one embodiment. As shown in FIGS. 1 to 7, a cold energy recovery system 1 according to some embodiments includes a first fuel tank 11 configured to store a first fuel in a liquid state, a second fuel tank 12 configured to store a second fuel in a liquid state, a first fuel supply line 2 for sending the first fuel extracted from the first fuel tank 11, and a second fuel supply line 3 for sending the second fuel extracted from the second fuel tank 12. Hereinafter, the upstream side in the fluid flow direction will be simply referred to as the "upstream side," and the downstream side in the fluid flow direction will be simply referred to as the "downstream side."

[0013] The liquefaction temperature (or boiling point) of the second fuel is lower than the liquefaction temperature (or boiling point) of the first fuel. In other words, the liquefaction temperature of the first fuel is higher than the liquefaction temperature of the second fuel. The temperature of the second fuel in liquid state stored in the second fuel tank 12 is lower than the temperature of the first fuel in liquid state stored in the first fuel tank 11.

[0014] In some embodiments, the first fuel is natural gas (liquefaction temperature: approximately −163° C.), and the second fuel is hydrogen (liquefaction temperature: approximately −253° C.). In this case, the first fuel tank 11 stores liquefied natural gas (LNG) at approximately −163° C., and the second fuel tank 12 stores liquefied hydrogen (LH2) at approximately −253° C.

[0015] The first fuel supply line 2 comprises a first fuel supply system for sending the first fuel from the first fuel tank 11 to a supply destination of the first fuel (in the illustrated example, the combustion device 14). One side (upstream end) of the first fuel supply line 2 is connected to the first fuel tank 11, and the other side (downstream end) of the first fuel supply line 2 is connected to the supply destination of the first fuel. The first fuel supply line 2 includes a first fuel pump 21 for pumping the liquid first fuel provided on the first fuel supply line 2. The first fuel pump 21 extracts the liquid first fuel stored in the first fuel tank 11 into the first fuel supply line 2, and the first fuel is sent to the downstream side of the first fuel supply line 2.

[0016] The second fuel supply line 3 comprises a second fuel supply system for sending the second fuel from the second fuel tank 12 to a supply destination of the second fuel (in the illustrated example, the combustion device 14). One side (upstream end) of the second fuel supply line 3 is connected to the second fuel tank 12, and the other side (downstream end) of the second fuel supply line 3 is connected to a supply destination of the second fuel. The second fuel supply line 3 includes a second fuel pump 31 for pumping the liquid second fuel provided on the second fuel supply line 3. The second fuel pump 31 extracts the liquid second fuel stored in the second fuel tank 12 into the second fuel supply line 3, and the second fuel is sent to the downstream side of the second fuel supply line 3.

[0017] As shown in Figures 1 to 7, the cold energy recovery system 1 further includes a first cold energy recovery cycle 4, a second cold energy recovery cycle 5, a first heat exchanger 42 provided on the first fuel supply line 2, a second heat exchanger 13 provided downstream of the first heat exchanger 42 on the first fuel supply line 2, and a third heat exchanger 52 provided downstream of the second heat exchanger 13 on the first fuel supply line 2.

[0018] In the cold energy recovery system 1, the first fuel in a liquid state from the first fuel tank 11 is vaporized by heat exchange in the first heat exchanger 42. Furthermore, the first fuel in a gaseous state from the first heat exchanger 42 is liquefied by heat exchange in the second heat exchanger 13. Furthermore, the first fuel in a liquid state from the second heat exchanger 13 is vaporized by heat exchange in the third heat exchanger 52. The second fuel in a liquid state from the second fuel tank 12 is vaporized by a heat exchanger provided on the second fuel supply line 3, such as the second heat exchanger 13. The vaporized first fuel and second fuel in a gaseous state are heated to an appropriate temperature by a heater or the like as necessary, and then supplied as fuel to a supply destination (in the illustrated example, a combustion device 14) via the first fuel supply line 2 and the second fuel supply line 3.

[0019] (First cold and heat recovery cycle) The first cold heat recovery cycle 4 is made up of a circulation system configured to circulate a first heat medium. As shown in Figs. 1 to 7, the first cold heat recovery cycle 4 includes a first expansion turbine 41, a first pump 43, and a first evaporator 44, which are respectively provided on the first cold heat recovery cycle 4. The first cold heat recovery cycle 4, together with a first heat exchanger 42 provided on the first cold heat recovery cycle 4, constitutes a heat exchange cycle (organic Rankine cycle) using the first heat medium as a working medium.

[0020] The first pump 43 is provided downstream of the first heat exchanger 42 on the first cold energy recovery cycle 4. The first pump 43 is configured to increase the pressure of the first heat medium in liquid form condensed in the first heat exchanger 42. By driving the first pump 43, the first heat medium circulates on the first cold energy recovery cycle 4.

[0021] The first evaporator 44 is provided downstream of the first pump 43 in the first cold energy recovery cycle 4. A liquid first heat medium pressurized by the first pump 43 flows into the first evaporator 44. The first evaporator 44 is configured to evaporate the first heat medium by heat exchange between the heat medium (e.g., seawater) flowing through the heat medium supply line 9A and the first heat medium flowing through the first cold energy recovery cycle 4. The first heat medium that has been made into a gaseous state by the first evaporator 44 is guided to the first expansion turbine 41.

[0022] The first expansion turbine 41 is provided downstream of the first evaporator 44 and upstream of the first heat exchanger 42 in the first cold heat recovery cycle 4, and is configured to expand the first heat medium in a gaseous state. The first expansion turbine 41 is configured to expand the first heat medium in a gaseous state and recover turbine rotational power from the first heat medium. As shown in FIGS. 1 to 7, the first cold heat recovery cycle 4 may further include a first generator 45 connected to the first expansion turbine 41. The first generator 45 is configured to be rotationally driven by the rotational power recovered by the first expansion turbine 41 to generate electricity.

[0023] In the first cold energy recovery cycle 4, the first expansion turbine 41 can output power using cold energy recovered from the first fuel in the first heat exchanger 42. Furthermore, if the first cold energy recovery cycle 4 includes a first generator 45, the power output by the first expansion turbine 41 can be converted into electric power.

[0024] (1st heat exchanger) The first heat exchanger 42 is provided downstream of the first fuel pump 21 on the first fuel supply line 2. The first heat exchanger 42 is also provided downstream of the first expansion turbine 41 and upstream of the first pump 43 on the first cold energy recovery cycle 4. The first heat exchanger 42 is configured to function as an evaporator for evaporating the first fuel on the first fuel supply line 2, and to function as a condenser for condensing the first heat medium in the first cold energy recovery cycle 4.

[0025] The first heat exchanger 42 is configured to transfer cold energy from the first fuel flowing through the first fuel supply line 2 to the first heat medium flowing through the first cold energy recovery cycle 4. The first heat exchanger 42 has a first fuel side flow path provided on the first fuel supply line 2 through which the first fuel flows, and a first heat medium side flow path provided on the first cold energy recovery cycle 4 through which a first heat medium with a higher temperature than the first fuel flowing through the first fuel side flow path flows. The first heat exchanger 42 is configured to be able to exchange heat between the first fuel side flow path and the first heat medium side flow path.

[0026] In the first heat exchanger 42, the first fuel flowing through the first fuel-side flow path is heated by the first heat medium flowing through the first heat medium-side flow path and evaporates. Also, in the first heat exchanger 42, the first heat medium flowing through the first heat medium-side flow path is cooled by the first fuel flowing through the first fuel-side flow path and condenses. Note that the first fuel from the first fuel tank 11 flows into the first heat exchanger 42 in a liquid state.

[0027] (Second cold and heat recovery cycle) The second cold energy recovery cycle 5 is made up of a circulation system configured to circulate a second heat medium. As shown in FIGS. 1 to 7, the second cold energy recovery cycle 5 includes a second expansion turbine 51, a second pump 53, and a second evaporator 54, which are respectively provided on the second cold energy recovery cycle 5. The second cold energy recovery cycle 5, together with a third heat exchanger 52 provided on the second cold energy recovery cycle 5, constitutes a heat exchange cycle (organic Rankine cycle) using the second heat medium as a working medium.

[0028] The second pump 53 is provided downstream of the third heat exchanger 52 on the second cold energy recovery cycle 5. The second pump 53 is configured to increase the pressure of the second heat medium in liquid form condensed in the third heat exchanger 52. By driving the second pump 53, the second heat medium circulates on the second cold energy recovery cycle 5.

[0029] The second evaporator 54 is provided downstream of the second pump 53 in the second cold energy recovery cycle 5. The second heat medium in liquid form, pressurized by the second pump 53, flows into the second evaporator 54. The second evaporator 54 is configured to evaporate the second heat medium by heat exchange between the heat medium (e.g., seawater) flowing through the heat medium supply line 9B and the second heat medium flowing through the second cold energy recovery cycle 5. The second heat medium that has been made into a gaseous state by the second evaporator 54 is guided to the second expansion turbine 51.

[0030] The second expansion turbine 51 is provided downstream of the second evaporator 54 and upstream of the third heat exchanger 52 in the second cold energy recovery cycle 5, and is configured to expand the second heat medium in a gaseous state. The second expansion turbine 51 is configured to expand the second heat medium in a gaseous state and recover turbine rotational power from the second heat medium. As shown in FIGS. 1 to 7, the second cold energy recovery cycle 5 may further include a second generator 55 connected to the second expansion turbine 51. The second generator 55 is configured to be rotationally driven by the rotational power recovered by the second expansion turbine 51 to generate electricity.

[0031] In the second cold energy recovery cycle 5, the second expansion turbine 51 can output power using cold energy recovered from the first fuel in the third heat exchanger 52. Furthermore, if the second cold energy recovery cycle 5 includes a second generator 55, the power output by the second expansion turbine 51 can be converted into electric power.

[0032] (Third heat exchanger) The third heat exchanger 52 is provided downstream of the second heat exchanger 13 on the first fuel supply line 2. The third heat exchanger 52 is also provided downstream of the second expansion turbine 51 and upstream of the second pump 53 on the second cold energy recovery cycle 5. The third heat exchanger 52 is configured to function as an evaporator for evaporating the first fuel on the first fuel supply line 2, and to function as a condenser for condensing the second heat medium in the second cold energy recovery cycle 5.

[0033] The third heat exchanger 52 is configured to transfer cold energy from the first fuel flowing through the first fuel supply line 2 to the second heat medium flowing through the second cold energy recovery cycle 5. The third heat exchanger 52 has a first fuel side flow path provided on the first fuel supply line 2 through which the first fuel flows, and a second heat medium side flow path provided on the second cold energy recovery cycle 5 through which a second heat medium with a higher temperature than the first fuel flowing through the first fuel side flow path flows. The third heat exchanger 52 is configured to be able to exchange heat between the first fuel side flow path and the second heat medium side flow path.

[0034] In the third heat exchanger 52, the first fuel flowing through the first fuel side flow path is heated by the second heat medium flowing through the second heat medium side flow path and evaporates. Also, in the third heat exchanger 52, the second heat medium flowing through the second heat medium side flow path is cooled by the first fuel flowing through the first fuel side flow path and condenses. The first fuel from the second heat exchanger 13 flows into the third heat exchanger 52 in a liquid state.

[0035] (Second heat exchanger) The second heat exchanger 13 is provided on the first fuel supply line 2 downstream of the first heat exchanger 42 and upstream of the third heat exchanger 52. The second heat exchanger 13 is also provided on the second fuel supply line 3 downstream of the second fuel pump 31. The second heat exchanger 13 is configured to function as a condenser for condensing the first fuel on the first fuel supply line 2, and to function as a heater for heating the second fuel on the second fuel supply line 3. The first fuel is re-liquefied by the second heat exchanger 13.

[0036] The second heat exchanger 13 is configured to transfer cold energy from the second fuel flowing through the second fuel supply line 3 to the first fuel flowing through the first fuel supply line 2. The second heat exchanger 13 has a first fuel side flow passage provided on the first fuel supply line 2 through which the first fuel flows, and a second fuel side flow passage provided on the first fuel supply line 2 through which a second fuel flows that has a lower temperature than the first fuel flowing through the first fuel side flow passage. The second heat exchanger 13 is configured to be able to exchange heat between the first fuel side flow passage and the second fuel side flow passage.

[0037] In the second heat exchanger 13, the first fuel flowing through the first fuel side flow path is cooled and condensed by the second fuel flowing through the second fuel side flow path, and the second fuel flowing through the second fuel side flow path is heated by the first fuel flowing through the first fuel side flow path.

[0038] 1 to 4, the second fuel from the second fuel tank 12 flows into the second heat exchanger 13 in a liquid state. The second heat exchanger 13 is configured to function as an evaporator for evaporating the second fuel on the second fuel supply line 3. In the embodiment shown in FIGS. 5 to 7, the second fuel from the second fuel tank 12 flows into the second heat exchanger 13 in a gas state.

[0039] As shown in Figures 1 to 7, a cold energy recovery system 1 according to some embodiments includes a first fuel tank 11, a second fuel tank 12, a first fuel supply line 2, a second fuel supply line 3, a first cold energy recovery cycle 4 including a first expansion turbine 41, a first heat exchanger 42, a second heat exchanger 13, a second cold energy recovery cycle 5 including a second expansion turbine 51, and a third heat exchanger 52.

[0040] According to the above configuration, by reliquefying the first fuel, two cold energy recovery cycles 4 and 5 that utilize the latent heat of the first fuel can be driven. Specifically, by transferring the cold energy of the first fuel to the first heat medium in the first heat exchanger 42, the cold energy of the first fuel can be used as a cold energy source for the first cold energy recovery cycle 4. By transferring the cold energy of the second fuel to the first fuel in the second heat exchanger 13, the first fuel vaporized by heat exchange in the first heat exchanger 42 can be reliquefied. By transferring the cold energy of the reliquefied first fuel to the second heat medium in the third heat exchanger 52, the cold energy of the first fuel can be used as a cold energy source for the second cold energy recovery cycle 5. Therefore, according to the above configuration, by reliquefying the first fuel, cold energy can also be recovered in the second expansion turbine 51, and therefore the overall turbine output of the cold energy recovery system 1 can be increased compared to when the first fuel is not reliquefied.

[0041] Furthermore, according to the above configuration, the first fuel and the second fuel in a liquid state are each vaporized by heat exchange with another medium in the heat exchangers (second heat exchanger 13, third heat exchanger 52, etc.) included in the cold energy recovery system 1. That is, the cold energy recovery system 1 can efficiently vaporize both the first fuel and the second fuel as liquid fuels. Therefore, according to the above configuration, the cold energy of the liquid fuels can be recovered while efficiently vaporizing the two types of liquid fuels.

[0042] (Combustion equipment) 1 to 7, the above-described cold energy recovery system 1 further includes a combustion device (e.g., a gas turbine) 14 configured to combust the first fuel and the second fuel. The combustion device 14 is connected to a downstream end of the first fuel supply line 2 provided downstream of the third heat exchanger 52 of the first fuel supply line 2, and is connected to a downstream end of the second fuel supply line 3 provided downstream of the second heat exchanger 13 of the second fuel supply line 3.

[0043] 1 to 7, the first fuel supply line 2 and the second fuel supply line 3 join together downstream of the third heat exchanger 52 of the first fuel supply line 2 and downstream of the second heat exchanger 13 of the second fuel supply line 3. A mixed fuel obtained by mixing the first fuel in a gaseous state (e.g., natural gas) and the second fuel in a gaseous state (e.g., hydrogen) is supplied to the combustion device 14. Note that in some other embodiments, the cold heat recovery system 1 may be configured so that the supply destination of the first fuel in a gaseous state is different from the supply destination of the second fuel in a gaseous state.

[0044] According to the above configuration, the first fuel introduced to the combustion device 14 is vaporized by recovering cold energy in a heat exchanger (such as the third heat exchanger 52) provided on the first fuel supply line 2. The second fuel introduced to the combustion device 14 is vaporized by recovering cold energy in a heat exchanger (such as the second heat exchanger 13) provided on the second fuel supply line 3. The cold energy recovery system 1 can recover the cold energy of the first fuel and the second fuel as turbine output. Furthermore, the cold energy recovery system 1 can use the vaporized first fuel and second fuel as fuel in the combustion device 14. In this case, the first fuel and the second fuel can be prevented from being supplied to the combustion device 14 without being sufficiently vaporized, thereby preventing breakdowns and malfunctions of the combustion device 14.

[0045] (1st fuel side heater) As shown in FIGS. 1 to 7, the above-described cold energy recovery system 1 may further include a first fuel-side heater 22 for heating the first fuel provided on the first fuel supply line 2. The first fuel-side heater 22 is provided on the first fuel supply line 2 downstream of the third heat exchanger 52 and upstream of the junction with the second fuel supply line 3. The first fuel-side heater 22 heats the gaseous first fuel to an appropriate temperature before supplying the first fuel to a supply destination of the first fuel. The first fuel-side heater 22 may be configured to heat the first fuel by exchanging heat between a heat medium (e.g., seawater) flowing through the heat medium supply line 9C and the first fuel flowing through the first fuel supply line 2.

[0046] (Second fuel side heater) As shown in FIGS. 1 to 7, the above-described cold energy recovery system 1 may further include a second fuel-side heater 32 for heating the second fuel provided on the second fuel supply line 3. The second fuel-side heater 32 is provided on the second fuel supply line 3 downstream of the second heat exchanger 13 and upstream of the junction with the first fuel supply line 2. The second fuel-side heater 32 heats the gaseous second fuel to an appropriate temperature before supplying the second fuel to a supply destination of the second fuel. The second fuel-side heater 32 may be configured to heat the second fuel by exchanging heat between a heat medium (e.g., seawater) flowing through the heat medium supply line 9D and the second fuel flowing through the second fuel supply line 3.

[0047] 2 to 4, the above-described cold energy recovery system 1 further includes a third cold energy recovery cycle 6, a fourth heat exchanger 15 provided downstream of the third heat exchanger 52 on the first fuel supply line 2, and a fifth heat exchanger 62 provided downstream of the fourth heat exchanger 15 on the first fuel supply line 2. The fifth heat exchanger 62 is provided upstream of the first fuel-side heater 22 on the first fuel supply line 2.

[0048] In the cold energy recovery system 1 of this embodiment, the first fuel in a gaseous state from the third heat exchanger 52 is liquefied by heat exchange in the fourth heat exchanger 15. Furthermore, the first fuel in a liquid state from the fourth heat exchanger 15 is vaporized by heat exchange in the fifth heat exchanger 62.

[0049] (Third cold and heat recovery cycle) The third cold heat recovery cycle 6 is made up of a circulation system configured to circulate a third heat medium (for example, seawater, etc.). As shown in Figures 2 to 4, the third cold heat recovery cycle 6 includes a third expansion turbine 61, a third pump 63, and a third evaporator 64, which are respectively provided on the third cold heat recovery cycle 6. The third cold heat recovery cycle 6, together with a fifth heat exchanger 62 provided on the third cold heat recovery cycle 6, constitutes a heat exchange cycle (organic Rankine cycle) using the third heat medium as a working medium.

[0050] The third pump 63 is provided downstream of the fifth heat exchanger 62 on the third cold energy recovery cycle 6. The third pump 63 is configured to increase the pressure of the liquid third heat medium condensed in the fifth heat exchanger 62. By driving the third pump 63, the third heat medium circulates on the third cold energy recovery cycle 6.

[0051] The third evaporator 64 is provided downstream of the third pump 63 in the third cold heat recovery cycle 6. A liquid third heat medium pressurized by the third pump 63 flows into the third evaporator 64. The third evaporator 64 is configured to evaporate the third heat medium by heat exchange between the heat medium (e.g., seawater) flowing through the heat medium supply line 9E and the third heat medium flowing through the third cold heat recovery cycle 6. The third heat medium that has been made into a gaseous state by the third evaporator 64 is guided to the third expansion turbine 61.

[0052] The third expansion turbine 61 is provided downstream of the third evaporator 64 and upstream of the fifth heat exchanger 62 in the third cold energy recovery cycle 6, and is configured to expand the third heat medium in a gaseous state. The third expansion turbine 61 is configured to expand the third heat medium in a gaseous state and recover turbine rotational power from the third heat medium. As shown in FIGS. 2 to 4, the third cold energy recovery cycle 6 may further include a third generator 65 connected to the third expansion turbine 61. The third generator 65 is configured to be rotationally driven by the rotational power recovered by the third expansion turbine 61 to generate electricity.

[0053] In the third cold energy recovery cycle 6, the third expansion turbine 61 can output power using cold energy recovered from the first fuel in the fifth heat exchanger 62. Furthermore, if the third cold energy recovery cycle 6 includes a third generator 65, the power output by the third expansion turbine 61 can be converted into electric power.

[0054] (5th heat exchanger) The fifth heat exchanger 62 is provided downstream of the fourth heat exchanger 15 on the first fuel supply line 2. The fifth heat exchanger 62 is also provided downstream of the third expansion turbine 61 and upstream of the third pump 63 on the third cold energy recovery cycle 6. The fifth heat exchanger 62 is configured to function as an evaporator for evaporating the first fuel on the first fuel supply line 2, and to function as a condenser for condensing the third heat medium in the third cold energy recovery cycle 6.

[0055] The fifth heat exchanger 62 is configured to transfer cold energy from the first fuel flowing through the first fuel supply line 2 to the third heat medium flowing through the third cold energy recovery cycle 6. The fifth heat exchanger 62 has a first fuel side flow path provided on the first fuel supply line 2 and through which the first fuel flows, and a third heat medium side flow path provided on the third cold energy recovery cycle 6 and through which a third heat medium flows, the third heat medium having a higher temperature than the first fuel flowing through the first fuel side flow path. The fifth heat exchanger 62 is configured to be able to exchange heat between the first fuel side flow path and the third heat medium side flow path.

[0056] In the fifth heat exchanger 62, the first fuel flowing through the first fuel side flow path is heated by the third heat medium flowing through the third heat medium side flow path and evaporates. Also, in the fifth heat exchanger 62, the third heat medium flowing through the third heat medium side flow path is cooled by the first fuel flowing through the first fuel side flow path and condenses. The first fuel from the fourth heat exchanger 15 flows into the fifth heat exchanger 62 in a liquid state.

[0057] (4th heat exchanger) The fourth heat exchanger 15 is provided on the first fuel supply line 2 downstream of the third heat exchanger 52 and upstream of the fifth heat exchanger 62. The fourth heat exchanger 15 is also provided on the second fuel supply line 3 downstream of the second heat exchanger 13. The fourth heat exchanger 15 is configured to function as a condenser for condensing the first fuel on the first fuel supply line 2, and to function as a heater for heating the second fuel on the second fuel supply line 3. The first fuel is re-liquefied by the fourth heat exchanger 15. The fourth heat exchanger 15 is also provided on the second fuel supply line 3 upstream of the second fuel-side heater 32.

[0058] The fourth heat exchanger 15 is configured to transfer cold energy from the second fuel flowing through the second fuel supply line 3 to the first fuel flowing through the first fuel supply line 2. The fourth heat exchanger 15 has a first fuel side flow passage provided on the first fuel supply line 2 through which the first fuel flows, and a second fuel side flow passage provided on the second fuel supply line 3 through which a second fuel having a lower temperature than the first fuel flowing through the first fuel side flow passage flows. The fourth heat exchanger 15 is configured to be able to exchange heat between the first fuel side flow passage and the second fuel side flow passage.

[0059] In the fourth heat exchanger 15, the first fuel flowing through the first fuel side flow path is cooled and condensed by the second fuel flowing through the second fuel side flow path. In addition, in the fourth heat exchanger 15, the second fuel flowing through the second fuel side flow path is heated by the first fuel flowing through the first fuel side flow path. The second fuel from the second heat exchanger 13 flows into the fourth heat exchanger 15 in a gaseous state.

[0060] According to the above configuration, when the second fuel stored in the second fuel tank 12 has sufficient cold energy, the first fuel can be reliquefied twice, thereby driving the three cold energy recovery cycles 4, 5, and 6 that utilize the latent heat of the first fuel. Specifically, the cold energy of the second fuel is transferred to the first fuel in the fourth heat exchanger 15, thereby reliquefying the first fuel that has been vaporized by heat exchange in the third heat exchanger 52. The cold energy of the reliquefied first fuel is transferred to the third heat medium in the fourth heat exchanger 15, thereby allowing the cold energy of the first fuel to be used as a cold source for the third cold energy recovery cycle 6. Therefore, according to the above configuration, by reliquefying the first fuel twice, cold energy can also be recovered in the third expansion turbine 61, thereby increasing the overall turbine output of the cold energy recovery system 1 compared to when the first fuel is reliquefied once.

[0061] (First bypass line, flow control valve) In some embodiments, the above-described cold energy recovery system 1 further includes a first bypass line 33 and a flow rate adjustment valve 34, as shown in Fig. 3. The first bypass line 33 is configured to guide the second fuel from an upstream side of the second heat exchanger 13 on the second fuel supply line 3 to the fourth heat exchanger 15, bypassing the second heat exchanger 13. One end (upstream end) of the first bypass line 33 is connected to a location on the second fuel supply line 3 downstream of the second fuel pump 31 and upstream of the second heat exchanger 13. The other end (downstream end) of the first bypass line 33 may be connected to the fourth heat exchanger 15 provided on the second fuel supply line 3, or may be connected to a location on the second fuel supply line 3 downstream of the second heat exchanger 13 and upstream of the fourth heat exchanger 15.

[0062] The flow rate control valve 34 is provided on the second fuel supply line 3 between the connection position of the upstream end of the first bypass line 33 and the second heat exchanger 13, and is configured to be able to adjust the flow rate of the second fuel passing through the flow rate control valve 34. In one embodiment, the flow rate control valve 34 is configured to be able to adjust its opening to fully closed, fully open, or at least one intermediate opening between fully closed and fully open. By reducing the opening rate of the flow rate control valve 34, it is possible to increase the amount of the second fuel flowing through the first bypass line 33 compared to when the opening rate of the flow rate control valve 34 is large. By increasing the opening rate of the flow rate control valve 34, it is possible to increase the amount of the second fuel passing through the flow rate control valve 34 and guided to the second heat exchanger 13 compared to when the opening rate of the flow rate control valve 34 is small.

[0063] According to the above configuration, by reducing the opening degree of the flow rate control valve 34, at least a portion of the second fuel can be guided to the fourth heat exchanger 15 through the first bypass line 33. Since the cold energy of the second fuel guided to the fourth heat exchanger 15 through the first bypass line 33 is not recovered in the second heat exchanger 13, the degree of subcooling of the first fuel that has passed through the fourth heat exchanger 15 can be increased. By increasing the degree of subcooling of the first fuel that has passed through the fourth heat exchanger 15, the amount of cold energy recovered by the third expansion turbine 61 that uses the cold energy of the first fuel that has passed through the fourth heat exchanger 15 as a cold energy source can be increased compared to when the first bypass line 33 is not provided.

[0064] (Problems when the hydrogen content in the fuel mixture is low) The higher the mixing ratio of hydrogen (second fuel) in the mixed fuel supplied to the combustion device 14, the higher the nitrogen oxide emission rate in the combustion device 14. Therefore, there is a risk that the mixing ratio of hydrogen (second fuel) in the mixed fuel will be limited to comply with nitrogen oxide emission regulations. For example, when the ship 10A or floating body 10B that is equipped with and powered by the cold energy recovery system 1 navigates in waters with strict nitrogen oxide emission regulations, it is necessary to intentionally lower the mixing ratio of hydrogen (second fuel) in the mixed fuel. When the mixing ratio of hydrogen (second fuel) in the mixed fuel is low, the cold energy of the second fuel cannot sufficiently cool the first fuel, and there is a risk that the degree of subcooling of the first fuel that has passed through the fourth heat exchanger 15 will be small.

[0065] (Control of the cold energy recovery system by the control device shown in Figure 3) 3, the above-described cold energy recovery system 1 further includes a mixture ratio acquisition device 16 configured to acquire a mixture ratio of the first fuel and the second fuel introduced into the above-described combustion device 14, and a control device 17A configured to stop operation of either the first cold energy recovery cycle 4 or the second cold energy recovery cycle 5 when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value. The second fuel in this embodiment is made of hydrogen.

[0066] The mixture ratio acquisition device 16 may be a gas concentration meter, as shown in FIG. 3, that is attached to the combustion device 14 and is capable of measuring the concentrations of the first fuel and the second fuel contained in the mixed fuel supplied to the combustion device 14.

[0067] 3, the control device 17A includes a mixture ratio determination unit 171 that determines whether the mixture ratio of the second fuel (hydrogen) acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value, and a drive control unit 172 that stops the operation of either the first cold heat recovery cycle 4 or the second cold heat recovery cycle 5 when the mixture ratio determination unit 171 determines that the mixture ratio of the second fuel (hydrogen) is equal to or less than the predetermined value. The drive control unit 172 can stop the operation of the first cold heat recovery cycle 4 by issuing a stop command to the first pump 43 and stopping the operation of the first pump 43. The drive control unit 172 can also stop the operation of the second cold heat recovery cycle 5 by issuing a stop command to the second pump 53 and stopping the operation of the second pump 53. When stopping the operation of the first cold heat recovery cycle 4 or the second cold heat recovery cycle 5, the drive control unit 172 may instruct the flow rate adjustment valve 34 to fully close. By fully closing the flow control valve 34, the supply of the second fuel to the second heat exchanger 13 is stopped, and heat exchange between the first fuel and the second fuel in the second heat exchanger 13 is not performed.

[0068] When the mixture ratio determination unit 171 determines that the mixture ratio of the second fuel (hydrogen) is equal to or lower than a predetermined value, the drive control unit 172 of the control device 17A may stop the operation of the third cold heat recovery cycle 6 instead of stopping the operation of either the first cold heat recovery cycle 4 or the second cold heat recovery cycle 5. In this case, the drive control unit 172 issues a stop instruction to the third pump 63 to stop the operation of the third pump 63, thereby stopping the operation of the third cold heat recovery cycle 6.

[0069] The control device 17A is an electronic control unit for controlling the devices included in the cold energy recovery system 1. The control device 17A is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, a storage device such as an external storage device, an I / O interface, a communication interface, etc. The control device 17A may realize control of the above-mentioned respective parts 171 and 172 of the control device 17A by the CPU operating (for example, calculating data) according to instructions of a program loaded into the main storage device of the memory, for example.

[0070] According to the above configuration, the control device 17A stops the operation of either the first cold energy recovery cycle 4 or the second cold energy recovery cycle 5 when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value, thereby making it possible to increase the degree of supercooling of the first fuel that has passed through the fourth heat exchanger 15 even when the mixture ratio of hydrogen (second fuel) in the mixed fuel is low. The cold energy recovery system 1 can be stably operated even when the mixture ratio of hydrogen (second fuel) in the mixed fuel is low.

[0071] Furthermore, according to the above configuration, the cold energy recovery system 1 can adjust the degree of subcooling of the first fuel that has passed through the fourth heat exchanger 15 by adjusting the opening degree of the flow rate adjustment valve 34, without adjusting the pressure in the third cold energy recovery cycle 6. Therefore, the cold energy recovery system 1 including the first bypass line 33 and the flow rate adjustment valve 34 can suppress the complexity of the operation control of the third cold energy recovery cycle 6.

[0072] (Control of the cold energy recovery system by the control device shown in Figure 4) In some embodiments, the cold energy recovery system 1 includes the above-described mixture ratio acquisition device 16 and a control device 17B configured to stop operation of the third cold energy recovery cycle 6 when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value, as shown in Fig. 4. The second fuel in this embodiment is hydrogen. The cold energy recovery system 1 in this embodiment does not include the above-described first bypass line 33 and flow rate adjustment valve 34.

[0073] 4, the control device 17B includes a mixture ratio determination unit 171 that determines whether the mixture ratio of the second fuel (hydrogen) acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value, and a drive control unit 172 that stops the operation of the third cold heat recovery cycle 6 when the mixture ratio determination unit 171 determines that the mixture ratio of the second fuel (hydrogen) is equal to or less than the predetermined value. The drive control unit 172 can stop the operation of the third cold heat recovery cycle 6 by issuing a stop command to the third pump 63 and stopping the operation of the third pump 63.

[0074] The control device 17B is an electronic control unit for controlling the devices included in the cold energy recovery system 1. The control device 17B is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, a storage device such as an external storage device, an I / O interface, a communication interface, etc. The control device 17B may realize control of the above-mentioned respective parts 171 and 172 of the control device 17A by the CPU operating (for example, calculating data) according to instructions of a program loaded into the main storage device of the memory, for example.

[0075] According to the above configuration, when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device 16 is equal to or less than a predetermined value, the control device 17B stops the operation of the third cold energy recovery cycle 6, thereby eliminating the need to increase the degree of subcooling of the first fuel that has passed through the fourth heat exchanger 15. Even when the mixture ratio of hydrogen (second fuel) in the mixed fuel is low, the cold energy recovery system 1 can be stably operated by stopping the operation of the third cold energy recovery cycle 6.

[0076] In some embodiments, the above-mentioned cold energy recovery system 1 further includes a fourth cold energy recovery cycle 7 and a sixth heat exchanger 72 arranged upstream of the second heat exchanger 13 on the second fuel supply line 3, as shown in Figures 5 to 7.

[0077] In the cold energy recovery system 1 of this embodiment, the second fuel in a liquid state from the second fuel tank 12 is vaporized by heat exchange in the sixth heat exchanger 72. The second fuel from the sixth heat exchanger 72 flows into the second heat exchanger 13 in a gaseous state.

[0078] (4th cold and heat recovery cycle) The fourth cold energy recovery cycle 7 is made up of a circulation system configured to circulate a fourth heat medium. As shown in Figures 5 to 7, the fourth cold energy recovery cycle 7 includes a fourth expansion turbine 71, a fourth pump 73, and a fourth evaporator 74, which are respectively provided on the fourth cold energy recovery cycle 7. The fourth cold energy recovery cycle 7, together with a sixth heat exchanger 72 provided on the fourth cold energy recovery cycle 7, constitutes a heat exchange cycle (organic Rankine cycle) using the fourth heat medium as a working medium.

[0079] The fourth pump 73 is provided downstream of the sixth heat exchanger 72 on the fourth cold energy recovery cycle 7. The fourth pump 73 is configured to increase the pressure of the liquid fourth heat medium condensed in the sixth heat exchanger 72. By driving the fourth pump 73, the fourth heat medium circulates on the fourth cold energy recovery cycle 7.

[0080] The fourth evaporator 74 is provided downstream of the fourth pump 73 in the fourth cold heat recovery cycle 7. A liquid fourth heat medium pressurized by the fourth pump 73 flows into the fourth evaporator 74. In the embodiment shown in FIG. 5 , the fourth evaporator 74 is configured to evaporate the fourth heat medium by heat exchange between a heat medium (e.g., seawater) flowing through the heat medium supply line 9F and the fourth heat medium flowing through the fourth cold heat recovery cycle 7. The fourth heat medium that has been made into a gaseous state by the fourth evaporator 74 is guided to the fourth expansion turbine 71.

[0081] The fourth expansion turbine 71 is provided downstream of the fourth evaporator 74 and upstream of the sixth heat exchanger 72 in the fourth cold energy recovery cycle 7, and is configured to expand the fourth heat medium in a gaseous state. The fourth expansion turbine 71 is configured to expand the fourth heat medium in a gaseous state and recover turbine rotational power from the fourth heat medium. As shown in FIGS. 5 to 7, the fourth cold energy recovery cycle 7 may further include a fourth generator 75 connected to the fourth expansion turbine 71. The fourth generator 75 is configured to be rotationally driven by the rotational power recovered by the fourth expansion turbine 71 to generate electricity.

[0082] In the fourth cold energy recovery cycle 7, the fourth expansion turbine 71 can output power using cold energy recovered from the second fuel in the sixth heat exchanger 72. Furthermore, if the fourth cold energy recovery cycle 7 includes a fourth generator 75, the power output by the fourth expansion turbine 71 can be converted into electric power.

[0083] (6th heat exchanger) The sixth heat exchanger 72 is provided on the second fuel supply line 3 downstream of the second fuel pump 31 and upstream of the second heat exchanger 13. The sixth heat exchanger 72 is also provided on the fourth cold energy recovery cycle 7 downstream of the fourth expansion turbine 71 and upstream of the fourth pump 73. The sixth heat exchanger 72 is configured to function as an evaporator for evaporating the second fuel on the second fuel supply line 3, and to function as a condenser for condensing the fourth heat medium in the fourth cold energy recovery cycle 7.

[0084] The sixth heat exchanger 72 is configured to transfer cold energy from the second fuel flowing through the second fuel supply line 3 to the fourth heat medium flowing through the fourth cold energy recovery cycle 7. The sixth heat exchanger 72 has a second fuel side flow passage provided on the second fuel supply line 3 and through which the second fuel flows, and a fourth heat medium side flow passage provided on the fourth cold energy recovery cycle 7 and through which a fourth heat medium flows, the fourth heat medium having a higher temperature than the second fuel flowing through the second fuel side flow passage. The sixth heat exchanger 72 is configured to be able to exchange heat between the second fuel side flow passage and the fourth heat medium side flow passage.

[0085] In the sixth heat exchanger 72, the second fuel flowing through the second fuel side flow passage is heated by the fourth heat medium flowing through the fourth heat medium side flow passage and evaporates. Also, in the sixth heat exchanger 72, the fourth heat medium flowing through the fourth heat medium side flow passage is cooled by the second fuel flowing through the second fuel side flow passage and condenses. The second fuel from the second fuel pump 31 flows into the sixth heat exchanger 72 in a liquid state.

[0086] According to the above configuration, when the second fuel stored in the second fuel tank 12 has sufficient cold energy, it is possible to drive the cold energy recovery cycle 7 that utilizes the latent heat of the second fuel. Specifically, in the sixth heat exchanger 72, the cold energy of the second fuel is transferred to the fourth heat medium, so that the cold energy of the second fuel can be used as a cold source for the fourth cold energy recovery cycle 7. Therefore, according to the above configuration, cold energy can also be recovered in the fourth expansion turbine 71, and therefore the overall turbine output of the cold energy recovery system 1 can be increased.

[0087] In some embodiments, the above-described cold energy recovery system 1 further includes a fifth cold energy recovery cycle 8 configured to circulate a fifth heat medium having a higher freezing point than the fourth heat medium, as shown in Figures 6 and 7. The above-described fourth evaporator 74 is provided upstream of the fourth expansion turbine 71 in the fourth cold energy recovery cycle 7, and is configured to transfer thermal energy from the fifth heat medium flowing through the fifth cold energy recovery cycle 8 to the fourth heat medium. As shown in Figures 6 and 7, the cold energy recovery cycle for recovering cold energy from the second fuel may have a two-stage configuration consisting of the fourth cold energy recovery cycle 7 and the fifth cold energy recovery cycle 8.

[0088] (5th cold and heat recovery cycle) The fifth cold heat recovery cycle 8 is made up of a circulation system configured to circulate a fifth heat medium. As shown in Figures 6 and 7, the fifth cold heat recovery cycle 8 includes a fifth expansion turbine 81, a fifth pump 82, and a fifth evaporator 83, which are respectively provided on the fifth cold heat recovery cycle 8. The fifth cold heat recovery cycle 8, together with the fourth evaporator 74 provided on the fifth cold heat recovery cycle 8, constitutes a heat exchange cycle (organic Rankine cycle) using the fifth heat medium as a working medium.

[0089] The fifth pump 82 is provided downstream of the fourth evaporator 74 on the fifth cold energy recovery cycle 8. The fifth pump 82 is configured to increase the pressure of the liquid fifth heat medium condensed in the fourth evaporator 74. By driving the fifth pump 82, the fifth heat medium circulates on the fifth cold energy recovery cycle 8.

[0090] The fifth evaporator 83 is provided downstream of the fifth pump 82 in the fifth cold heat recovery cycle 8. A liquid fifth heat medium pressurized by the fifth pump 82 flows into the fifth evaporator 83. The fifth evaporator 83 is configured to evaporate the fifth heat medium by heat exchange between the heat medium (e.g., seawater) flowing through the heat medium supply line 9G and the fifth heat medium flowing through the fifth cold heat recovery cycle 8. The fifth heat medium that has been made into a gaseous state by the fifth evaporator 83 is guided to the fifth expansion turbine 81.

[0091] The fifth expansion turbine 81 is provided downstream of the fifth evaporator 83 and upstream of the fourth evaporator 74 in the fifth cold heat recovery cycle 8, and is configured to expand the fifth heat medium in a gaseous state. The fifth expansion turbine 81 is configured to expand the fifth heat medium in a gaseous state and recover rotational power of the turbine from the fifth heat medium. As shown in Figures 6 and 7, the fifth cold heat recovery cycle 8 may further include a fifth generator 84 connected to the fifth expansion turbine 81. The fifth generator 84 is configured to be rotationally driven by the rotational power recovered by the fifth expansion turbine 81 to generate electricity.

[0092] In the fifth cold energy recovery cycle 8, the fifth expansion turbine 81 can output power using cold energy recovered from the fourth heat medium in the fourth evaporator 74. Furthermore, when the fifth cold energy recovery cycle 8 includes a fifth generator 84, the power output by the fifth expansion turbine 81 can be converted into electric power.

[0093] (4th evaporator) In this embodiment, the fourth evaporator 74 is provided downstream of the fourth pump 73 and upstream of the fourth expansion turbine 71 in the fourth cold heat recovery cycle 7. The fourth evaporator 74 is also provided downstream of the fifth expansion turbine 81 and upstream of the fifth pump 82 in the fifth cold heat recovery cycle 8. The fourth evaporator 74 is configured to function as an evaporator for evaporating the fourth heat medium in the fourth cold heat recovery cycle 7, and to function as a condenser for condensing the fifth heat medium in the fifth cold heat recovery cycle 8.

[0094] The fourth evaporator 74 is configured to transfer cold energy from the fourth heat medium flowing through the fourth cold heat recovery cycle 7 to the fifth heat medium flowing through the fifth cold heat recovery cycle 8. The fourth evaporator 74 has a fourth heat medium side flow passage provided on the fourth cold heat recovery cycle 7 and through which the fourth heat medium flows, and a fifth heat medium side flow passage provided on the fifth cold heat recovery cycle 8 and through which a fifth heat medium with a higher temperature than the fourth heat medium flowing through the fourth heat medium side flow passage flows. The fourth evaporator 74 is configured to allow heat exchange between the fourth heat medium side flow passage and the fifth heat medium side flow passage.

[0095] In the fourth evaporator 74, the fourth heat medium flowing through the fourth heat medium-side flow path is heated by the fifth heat medium flowing through the fifth heat medium-side flow path and evaporates. Also, in the fourth evaporator 74, the fifth heat medium flowing through the fifth heat medium-side flow path is cooled by the fourth heat medium flowing through the fourth heat medium-side flow path and condenses.

[0096] When the second fuel stored in the second fuel tank 12 has sufficient cold energy, it is possible to drive two-stage cold energy recovery cycles 7 and 8 that utilize the latent heat of the second fuel. Specifically, in the fourth evaporator 74, the thermal energy of the fifth heat medium can be used as a heat source for the fourth cold energy recovery cycle 7, and the cold energy of the fourth heat medium can be used as a cold energy source for the fifth cold energy recovery cycle 8. Therefore, with the above configuration, cold energy can also be recovered in the fifth expansion turbine 81, and the overall turbine output of the cold energy recovery system 1 can be increased.

[0097] In some embodiments, the above-mentioned cold heat recovery system 1 further includes, as shown in FIG. 7, a second bypass line 85 provided on the fifth cold heat recovery cycle 8, the above-mentioned second fuel side heater (second fuel side first heater) 32 provided downstream of the second heat exchanger 13 on the second fuel supply line 3, and a second fuel side second heater 35 provided downstream of the second heat exchanger 13 on the second fuel supply line 3 and upstream of the second fuel side first heater 32.

[0098] (Second bypass line) The second bypass line 85 is configured to guide the fifth heat medium from downstream of the fifth expansion turbine 81 in the fifth cold heat recovery cycle 8, bypassing the fourth evaporator 74, to the fifth pump 82. One end (upstream end) of the second bypass line 85 is connected to a position downstream of the fifth expansion turbine 81 and upstream of the fourth evaporator 74 in the fifth cold heat recovery cycle 8, and the other end (downstream end) is connected to a position downstream of the fourth evaporator 74 and upstream of the fifth pump 82 in the fifth cold heat recovery cycle 8.

[0099] (Second fuel side second heater) The second fuel-side second heater 35 is configured to transfer thermal energy from the fifth heat medium flowing in the second bypass line 85 to the second fuel flowing in the second fuel supply line 3. The second fuel-side second heater 35 has a second fuel-side flow passage provided on the second fuel supply line 3 and through which the second fuel flows, and a fifth heat medium-side flow passage provided on the second bypass line 85 and through which a fifth heat medium with a higher temperature than the second fuel flowing in the second fuel-side flow passage flows. The second fuel-side second heater 35 is configured to allow heat exchange between the second fuel-side flow passage and the fifth heat medium-side flow passage.

[0100] In the second fuel side second heater 35, the second fuel flowing through the second fuel side flow passage is heated by the fifth heat medium flowing through the fifth heat medium side flow passage.

[0101] According to the above configuration, a part of the fifth heat medium discharged from the fifth expansion turbine 81 in the fifth cold heat recovery cycle 8 is supplied to the second fuel-side second heater 35 via the second bypass line 85, so that the second fuel can be appropriately heated by heat exchange with the fifth heat medium in the second fuel-side second heater 35. This makes it possible to suppress freezing of the heat medium in the second fuel-side first heater 32 provided downstream of the second fuel-side second heater 35 in the second fuel supply line 3.

[0102] In some embodiments, the first fuel is made of natural gas, and the second fuel is made of hydrogen. In this case, the liquid first fuel (natural gas) stored in the first fuel tank 11 and the liquid second fuel (hydrogen) stored in the second fuel tank 12 have sufficient cold energy, so that the turbines of the multiple cold recovery cycles in the cold recovery system 1 can be driven by this cold energy. This allows the overall output of the turbines in the cold recovery system 1 to be increased.

[0103] (ship or floating body) FIG. 8 is a schematic diagram of a ship or floating body equipped with a cold energy recovery system according to one embodiment. As shown in Fig. 8, a ship 10A or a floating body 10B according to some embodiments is equipped with the above-described cold energy recovery system 1. According to the above configuration, in the cold energy recovery system 1, the cold energy of the first fuel and the second fuel can be used as a cold energy source for multiple cold energy recovery cycles. Because the ship 10A or the floating body 10B is equipped with the cold energy recovery system 1, the overall output of the turbines (41, 51, etc.) can be increased compared to when the ship 10A or the floating body 10B is not equipped with the cold energy recovery system 1.

[0104] In addition, each of the cold heat recovery cycles 4 to 8 provided in the cold heat recovery system 1 may use the power (rotational force) recovered by the expansion turbine installed on that cold heat recovery cycle directly as power via a power transmission device (e.g., a coupling, belt, pulley, etc.) rather than converting the power (rotational force) recovered into electricity.

[0105] Each of the first, second, third, fourth, and fifth heat media has a boiling point and a freezing point lower than that of water. The heat media flowing through the heat medium supply lines 9A to 9G are preferably seawater or engine cooling water heated by cooling the engine, which can be easily obtained on the ship 10A or the floating body 10B. The present disclosure is also applicable to cases where the first fuel is a fuel other than natural gas or where the second fuel is a fuel other than hydrogen.

[0106] In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0107] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0108] The contents of the above-described embodiments can be understood, for example, as follows.

[0109] 1) At least one embodiment of the cold energy recovery system (1) of the present disclosure includes: a first fuel tank (11) configured to store a first fuel in a liquid state; a second fuel tank (12) configured to store a second fuel in a liquid state having a lower liquefaction temperature than the first fuel; a first fuel supply line (2) for delivering the first fuel extracted from the first fuel tank (11); a second fuel supply line (3) for delivering the second fuel extracted from the second fuel tank (12); a first cold heat recovery cycle (4) configured to circulate a first heat medium, the first cold heat recovery cycle (4) including a first expansion turbine (41) for expanding the first heat medium in a gaseous state provided on the first cold heat recovery cycle (4); a first heat exchanger (42) provided downstream of the first expansion turbine (41) in the first cold energy recovery cycle (4), and configured to transfer cold energy from the first fuel flowing through the first fuel supply line (2) to the first heat medium; a second heat exchanger (13) provided on the first fuel supply line (2) downstream of the first heat exchanger (42) and configured to transfer cold energy from the second fuel flowing in the second fuel supply line (3) to the first fuel flowing in the first fuel supply line (2); a second cold heat recovery cycle (5) configured to circulate a second heat medium, the second cold heat recovery cycle (5) including a second expansion turbine (51) for expanding the second heat medium in a gaseous state provided on the second cold heat recovery cycle (5); and a third heat exchanger (52) provided downstream of the second expansion turbine (51) on the second cold energy recovery cycle (5) and configured to transfer cold energy from the first fuel flowing downstream of the second heat exchanger (13) in the first fuel supply line (2) to the second heat medium.

[0110] According to the above configuration 1), by re-liquefying the first fuel, two cold energy recovery cycles (4, 5) that utilize the latent heat of the first fuel can be driven. Specifically, in the first heat exchanger (42), the cold energy of the first fuel is transferred to the first heat medium, so that the cold energy of the first fuel can be used as a cold source for the first cold energy recovery cycle (4). In the second heat exchanger (13), the cold energy of the second fuel is transferred to the first fuel, so that the first fuel vaporized by the heat exchange in the first heat exchanger (42) can be re-liquefied. In the third heat exchanger (52), the cold energy of the re-liquefied first fuel is transferred to the second heat medium, so that the cold energy of the first fuel can be used as a cold source for the second cold energy recovery cycle (5). Therefore, according to the above configuration 1), by re-liquefying the first fuel, it becomes possible to recover cold energy in the second expansion turbine (51), and therefore the overall output of the turbines (41, 51) of the cold energy recovery system (1) can be increased compared to when the first fuel is not re-liquefied.

[0111] 2) In some embodiments, the cold energy recovery system (1) described in 1) above, The combustion device (14) is configured to combust the first fuel and the second fuel, and is connected to the first fuel supply line (2) downstream of the third heat exchanger (52) and to the second fuel supply line (3) downstream of the second heat exchanger (13).

[0112] According to the above configuration 2), the first fuel introduced to the combustion device (14) is vaporized by recovering cold energy in the third heat exchanger (52). The second fuel introduced to the combustion device (14) is vaporized by recovering cold energy in the second heat exchanger (13). The vaporized first fuel and second fuel can be used as fuel in the combustion device (14). In this case, the first fuel and second fuel can be prevented from being supplied to the combustion device (14) without being sufficiently vaporized, thereby preventing breakdowns and malfunctions of the combustion device (14).

[0113] 3) In some embodiments, the cold energy recovery system (1) described in 1) or 2) above, The first cold energy recovery cycle (4) a first pump (43) provided downstream of the first heat exchanger (42) in the first cold energy recovery cycle (4) for increasing the pressure of the first heat medium; a first evaporator (44) disposed downstream of the first pump (43) in the first cold heat recovery cycle (4) for evaporating the first heat medium, The second cold energy recovery cycle (5) a second pump (53) provided downstream of the third heat exchanger (52) in the second cold energy recovery cycle (5) for increasing the pressure of the second heat medium; The system further includes a second evaporator (54) provided downstream of the second pump (53) in the second cold heat recovery cycle (5) for evaporating the second heat medium.

[0114] According to the above configuration 3), the first cold energy recovery cycle (4) and the first heat exchanger (42) constitute a heat exchange cycle (organic Rankine cycle) using the first heat medium as a working medium, so that the first expansion turbine (41) can be driven by cold energy recovered from the first fuel. The second cold energy recovery cycle (5) and the third heat exchanger (52) constitute a heat exchange cycle (organic Rankine cycle) using the second heat medium as a working medium, so that the second expansion turbine (51) can be driven by cold energy recovered from the first fuel. Therefore, according to the above configuration 3), the first expansion turbine (41) and the second expansion turbine (51) can convert the cold energy recovered from the first fuel into power.

[0115] 4) In some embodiments, the cold energy recovery system (1) according to any one of 1) to 3) above, a fourth heat exchanger (15) provided on the first fuel supply line (2) downstream of the third heat exchanger (52) and configured to transfer cold energy from the second fuel flowing downstream of the second heat exchanger (13) in the second fuel supply line (3) to the first fuel flowing in the first fuel supply line (2); a third refrigeration cycle (6) configured to circulate a third heat medium, the third refrigeration cycle (6) including a third expansion turbine (61) for expanding the third heat medium in a gaseous state provided on the third refrigeration cycle (6); and a fifth heat exchanger (62) provided downstream of the third expansion turbine (61) in the third cold energy recovery cycle (6) and configured to transfer cold energy from the first fuel flowing downstream of the fourth heat exchanger (15) in the first fuel supply line (2) to the third heat medium.

[0116] According to the configuration 4), when the second fuel stored in the second fuel tank (12) has sufficient cold energy, the first fuel can be reliquefied twice, thereby driving three cold energy recovery cycles (4, 5, 6) that utilize the latent heat of the first fuel. Specifically, the cold energy of the second fuel is transferred to the first fuel in the fourth heat exchanger (15), thereby reliquefying the first fuel that has been vaporized by heat exchange in the third heat exchanger (52). The cold energy of the reliquefied first fuel is transferred to the third heat medium in the fourth heat exchanger (15), thereby enabling the cold energy of the first fuel to be used as a cold source for the third cold energy recovery cycle (6). Therefore, according to the above configuration 4), by re-liquefying the first fuel twice, it becomes possible to recover cold energy in the third expansion turbine (61), and therefore it is possible to increase the overall output of the turbines (41, 51, 61) of the cold energy recovery system (1) compared to when the first fuel is re-liquefied once.

[0117] 5) In some embodiments, the cold energy recovery system (1) described in 4) above, The third cold energy recovery cycle (6) a third pump (63) provided downstream of the fifth heat exchanger (62) in the third cold heat recovery cycle (6) for increasing the pressure of the third heat medium; The system further includes a third evaporator (64) provided downstream of the third pump (63) in the third cold heat recovery cycle (6) for evaporating the third heat medium.

[0118] According to the configuration of 5), the third cold energy recovery cycle (6), together with the fifth heat exchanger (62), constitutes a heat exchange cycle (organic Rankine cycle) using the third heat medium as a working medium, so that the third expansion turbine (61) can be driven by cold energy recovered from the first fuel. Therefore, according to the configuration of 5), the third expansion turbine (61) can convert the cold energy recovered from the first fuel into power.

[0119] 6) In some embodiments, the cold energy recovery system (1) described in 4) or 5) above, a first bypass line (33) for guiding the second fuel from a side upstream of the second heat exchanger (13) on the second fuel supply line (3) to the fourth heat exchanger (15) while bypassing the second heat exchanger (13); The fuel supply system further includes a flow rate control valve (34) provided on the second fuel supply line (3) between a connection position of the upstream end of the first bypass line (33) and the second heat exchanger (13), the flow rate control valve (34) being configured to be able to adjust the flow rate of the second fuel passing through the flow rate control valve (34).

[0120] According to the configuration 6), by reducing the opening degree of the flow rate control valve (34), at least a part of the second fuel can be guided to the fourth heat exchanger (15) through the first bypass line (33). Since the cold energy of the second fuel guided to the fourth heat exchanger (15) through the first bypass line (33) is not recovered in the second heat exchanger (13), the degree of subcooling of the first fuel that has passed through the fourth heat exchanger (15) can be increased. By increasing the degree of subcooling of the first fuel that has passed through the fourth heat exchanger (15), the amount of cold recovered by the third expansion turbine (61), which uses the cold energy of the first fuel that has passed through the fourth heat exchanger (15) as a cold source, can be increased compared to a case where the first bypass line (33) is not provided.

[0121] 7) In some embodiments, the cold energy recovery system (1) described in 6) above, the second fuel comprises hydrogen; The cold heat recovery system (1) comprises: a combustion device (14) configured to combust the first fuel and the second fuel, the combustion device (14) being connected to the first fuel supply line (2) downstream of the third heat exchanger (52) and connected to the second fuel supply line (3) downstream of the second heat exchanger (13); a mixture ratio acquisition device (16) configured to acquire a mixture ratio of the first fuel and the second fuel introduced into the combustion device (14); The system further includes a control device (17A) configured to stop operation of either the first cold energy recovery cycle (4) or the second cold energy recovery cycle (5) when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device (16) is equal to or less than a predetermined value.

[0122] The higher the mixing ratio of hydrogen (second fuel) in the mixed fuel supplied to the combustion device (14), the higher the nitrogen oxide emission rate in the combustion device (14). Therefore, the mixing ratio of hydrogen (second fuel) in the mixed fuel may be limited to comply with nitrogen oxide emission regulations. For example, when a ship (10A) or a floating body (10B) equipped with and powered by the cold energy recovery system (1) navigates in a sea area with strict nitrogen oxide emission regulations, it is necessary to intentionally reduce the mixing ratio of hydrogen (second fuel) in the mixed fuel. If the mixing ratio of hydrogen (second fuel) in the mixed fuel is low, the cold energy of the second fuel may not be able to sufficiently cool the first fuel, and the degree of subcooling of the first fuel passing through the fourth heat exchanger (15) may be reduced. According to the configuration of 7), when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device (16) is equal to or less than a predetermined value, the control device (17A) stops the operation of either the first cold energy recovery cycle (4) or the second cold energy recovery cycle (5), thereby increasing the degree of subcooling of the first fuel that has passed through the fourth heat exchanger (15). The cold energy recovery system (1) can be stably operated even when the mixture ratio of hydrogen (second fuel) in the mixed fuel is low.

[0123] According to the configuration of 7), the cold energy recovery system (1) can adjust the degree of subcooling of the first fuel that has passed through the fourth heat exchanger (15) by adjusting the opening of the flow rate control valve (34) without adjusting the pressure in the third cold energy recovery cycle (6). Therefore, the cold energy recovery system (1) including the first bypass line (33) and the flow rate control valve (34) can suppress the complexity of the operation control of the third cold energy recovery cycle (6).

[0124] 8) In some embodiments, the cold energy recovery system (1) according to any one of 4) to 6) above, the second fuel comprises hydrogen; The cold heat recovery system (1) comprises: a combustion device (14) configured to combust the first fuel and the second fuel, the combustion device (14) being connected to the first fuel supply line (2) downstream of the third heat exchanger (52) and connected to the second fuel supply line (3) downstream of the second heat exchanger (13); a mixture ratio acquisition device (16) configured to acquire a mixture ratio of the first fuel and the second fuel introduced into the combustion device (14); The fuel cell system further includes a control device (17B) configured to stop operation of the third cold energy recovery cycle when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device (16) is equal to or less than a predetermined value.

[0125] According to the configuration of 8), when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device (16) is equal to or less than a predetermined value, the control device (17B) stops the operation of the third cold energy recovery cycle (6), thereby eliminating the need to increase the degree of subcooling of the first fuel that has passed through the fourth heat exchanger (15). Even when the mixture ratio of hydrogen (second fuel) in the mixed fuel is low, the cold energy recovery system (1) can be stably operated by stopping the operation of the third cold energy recovery cycle (6).

[0126] 9) In some embodiments, the cold energy recovery system (1) according to any one of 1) to 8) above, a fourth refrigeration recovery cycle (7) configured to circulate a fourth heat medium, the fourth refrigeration recovery cycle (7) including a fourth expansion turbine (71) for expanding the fourth heat medium in a gaseous state provided on the fourth refrigeration recovery cycle (7); The system further includes a sixth heat exchanger (72) that is provided downstream of the fourth expansion turbine (71) in the fourth cold energy recovery cycle (7) and is configured to transfer cold energy from the second fuel that flows upstream of the second heat exchanger (13) in the second fuel supply line (3) to the fourth heat medium.

[0127] According to the configuration of 9), when the second fuel stored in the second fuel tank (12) has sufficient cold energy, the cold energy recovery cycle (7) that utilizes the latent heat of the second fuel can be driven. Specifically, in the sixth heat exchanger (72), the cold energy of the second fuel is transferred to the fourth heat medium, so that the cold energy of the second fuel can be used as a cold energy source for the fourth cold energy recovery cycle (7). Therefore, according to the configuration of 9), the fourth expansion turbine (71) can also recover cold energy, so that the overall output of the turbines (41, 51, 71, etc.) of the cold energy recovery system (1) can be increased.

[0128] 10) In some embodiments, the cold energy recovery system (1) described in 9) above, a fifth cold heat recovery cycle (8) configured to circulate a fifth heat medium having a freezing point higher than that of the fourth heat medium, the fifth cold heat recovery cycle (8) including a fifth expansion turbine (81) for expanding the fifth heat medium in a gaseous state provided on the fifth cold heat recovery cycle (8); The system further includes a fourth evaporator (74) that is provided upstream of the fourth expansion turbine (71) in the fourth cold energy recovery cycle (7) and is configured to transfer thermal energy from the fifth heat medium flowing downstream of the fifth expansion turbine (71) to the fourth heat medium in the fifth cold energy recovery cycle (8).

[0129] According to the configuration of 10), when the second fuel stored in the second fuel tank (12) has sufficient cold energy, it is possible to drive a two-stage cold energy recovery cycle (7, 8) that utilizes the latent heat of the second fuel. Specifically, in the fourth evaporator (74), the thermal energy of the fifth heat medium can be used as a heat source for the fourth cold energy recovery cycle (7), and the cold energy of the fourth heat medium can be used as a cold energy source for the fifth cold energy recovery cycle (8). Therefore, according to the configuration of 10), it is possible to recover cold energy also in the fifth expansion turbine (81), and therefore it is possible to increase the overall output of the turbines (41, 51, 71, 81, etc.) of the cold energy recovery system (1).

[0130] 11) In some embodiments, the cold energy recovery system (1) described in 10) above, The fourth cold energy recovery cycle (7) a fourth pump (73) for increasing the pressure of the fourth heat medium, the fourth pump (73) being provided downstream of the sixth heat exchanger (72) and upstream of the fourth evaporator (74) in the fourth cold energy recovery cycle (7); The fifth cold energy recovery cycle (8) a fifth pump (82) provided downstream of the fourth evaporator (74) in the fifth cold energy recovery cycle (8) for increasing the pressure of the fifth heat medium; The fifth refrigeration system further includes a fifth evaporator (83) provided downstream of the fifth pump (82) in the fifth cold heat recovery cycle (8) for evaporating the fifth heat medium.

[0131] According to the configuration of 11), the fourth cold energy recovery cycle (7), together with the sixth heat exchanger (72) and the fourth evaporator (74), constitutes a heat exchange cycle (organic Rankine cycle) using the fourth heat medium as a working medium. Therefore, the fourth expansion turbine (71) can be driven by cold energy recovered from the second fuel. The fifth cold energy recovery cycle (8), together with the fourth evaporator (74), constitutes a heat exchange cycle (organic Rankine cycle) using the fifth heat medium as a working medium. Therefore, the fifth expansion turbine (81) can be driven by cold energy recovered from the second fuel via the fourth heat medium. Therefore, according to the configuration of 11), the fourth expansion turbine (71) and the fifth expansion turbine (81) can convert cold energy recovered from the second fuel into power.

[0132] 12) In some embodiments, the cold energy recovery system (1) described in 11) above, a second bypass line (85) for guiding the fifth heat medium from a downstream side of the fifth expansion turbine (81) in the fifth cold heat recovery cycle (8) to the fifth pump (82) while bypassing the fourth evaporator (74); a second fuel-side first heater (32) for heating the second fuel, the second fuel-side first heater (32) being provided on the second fuel supply line (3) downstream of the second heat exchanger (13); a second fuel-side second heater (35) for heating the second fuel, the second fuel-side second heater (35) being provided on the second fuel supply line downstream of the second heat exchanger (13) and upstream of the second fuel-side first heater (32), The second fuel side second heater (35) is configured to transfer thermal energy from the fifth heat medium flowing in the second bypass line (85) to the second fuel flowing in the second fuel supply line (3).

[0133] According to the configuration of 12), a part of the fifth heat medium discharged from the fifth expansion turbine (81) in the fifth cold energy recovery cycle (8) is supplied to the second fuel-side second heater (35) through the second bypass line (85), so that the second fuel can be appropriately heated by heat exchange with the fifth heat medium in the second fuel-side second heater (35). This makes it possible to suppress freezing of the heat medium in the second fuel-side first heater (32) provided downstream of the second fuel-side second heater (35) in the second fuel supply line (3).

[0134] 13) In some embodiments, the cold energy recovery system (1) according to any one of 1) to 12) above, the first fuel comprises natural gas; The second fuel comprises hydrogen.

[0135] According to the configuration of 13) above, the liquid first fuel (natural gas) stored in the first fuel tank and the liquid second fuel (hydrogen) stored in the second fuel tank have sufficient cold energy, so that the overall output of the turbines (41, 51, etc.) of the cold energy recovery system (1) can be increased.

[0136] 14) A ship (10A) or a floating body (10B) according to at least one embodiment of the present disclosure includes: The cold energy recovery system (1) is provided as set forth in any one of 1) to 13).

[0137] According to the configuration of 14) above, in the cold energy recovery system 1, the cold energy of the first fuel and the second fuel can be used as a cold energy source for multiple cold energy recovery cycles 1. The ship or floating body described in 14) above is equipped with the cold energy recovery system 1, and therefore can increase the overall output of the turbines (41, 51, etc.) compared to when the ship or floating body is not equipped with the cold energy recovery system 1. [Explanation of symbols]

[0138] 1. Cold and heat recovery system 2. First fuel supply line 3 Second fuel supply line 4. First cold and heat recovery cycle 5 Second cold and heat recovery cycle 6. Third cold and heat recovery cycle 7 Fourth cold and heat recovery cycle 8. 5th cold and heat recovery cycle 9A~9G Heat transfer medium supply line 10A ship 10B Floating body 11. No. 1 fuel tank 12 Second fuel tank 13 Second heat exchanger 14 Combustion equipment 15 4th heat exchanger 16 Mixing ratio acquisition device 17A, 17B Control device 21 No. 1 fuel pump 22 1st fuel side heater 31 Second fuel pump 32 2nd fuel side 1st heater 33 First Bypass Line 34 Flow control valve 35 2nd fuel side 2nd heater 41 First expansion turbine 42 1st heat exchanger 43 First Pump 44 First evaporator 45 First Generator 51 Second expansion turbine 52 Third heat exchanger 53 Second Pump 54 Second evaporator 55 Second Generator 61 Third expansion turbine 62 5th heat exchanger 63 Third Pump 64 Third evaporator 65 Third Generator 71 Fourth expansion turbine 72 6th heat exchanger 73 4th Pump 74 4th evaporator 75 4th Generator 81 No. 5 expansion turbine 82 5th Pump 83 5th evaporator 84 5th Generator 85 Second Bypass Line 171 Mixing ratio determination section 172 Drive control unit

Claims

1. a first fuel tank configured to store a first fuel in a liquid state; a second fuel tank configured to store a second fuel in a liquid state having a lower liquefaction temperature than the first fuel; a first fuel supply line for delivering the first fuel extracted from the first fuel tank; a second fuel supply line for delivering the second fuel extracted from the second fuel tank; a first refrigeration recovery cycle configured to circulate a first heat medium, the first refrigeration recovery cycle including a first expansion turbine for expanding the first heat medium in a gaseous state provided on the first refrigeration recovery cycle; a first heat exchanger provided downstream of the first expansion turbine in the first cold energy recovery cycle and configured to transfer cold energy from the first fuel flowing through the first fuel supply line to the first heat medium; a second heat exchanger provided on the first fuel supply line downstream of the first heat exchanger and configured to transfer cold energy from the second fuel flowing in the second fuel supply line to the first fuel flowing in the first fuel supply line; a second refrigeration recovery cycle configured to circulate a second heat medium, the second refrigeration recovery cycle including a second expansion turbine for expanding the second heat medium in a gaseous state provided on the second refrigeration recovery cycle; a third heat exchanger provided downstream of the second expansion turbine in the second cold energy recovery cycle and configured to transfer cold energy from the first fuel flowing downstream of the second heat exchanger in the first fuel supply line to the second heat medium, Cold and heat recovery system.

2. a combustion device configured to combust the first fuel and the second fuel, the combustion device being connected to the first fuel supply line downstream of the third heat exchanger and the second fuel supply line downstream of the second heat exchanger; The cold energy recovery system according to claim 1 .

3. The first cold heat recovery cycle includes: a first pump provided downstream of the first heat exchanger in the first cold heat recovery cycle for increasing the pressure of the first heat medium; a first evaporator provided downstream of the first pump in the first cold heat recovery cycle for evaporating the first heat medium, The second cold heat recovery cycle is a second pump provided downstream of the third heat exchanger in the second cold heat recovery cycle for increasing the pressure of the second heat medium; a second evaporator provided downstream of the second pump in the second cold heat recovery cycle for evaporating the second heat medium, The cold energy recovery system according to claim 1 or 2.

4. a fourth heat exchanger provided on the first fuel supply line downstream of the third heat exchanger and configured to transfer cold energy from the second fuel flowing downstream of the second heat exchanger in the second fuel supply line to the first fuel flowing in the first fuel supply line; a third refrigeration recovery cycle configured to circulate a third heat medium, the third refrigeration recovery cycle including a third expansion turbine for expanding the third heat medium in a gaseous state provided on the third refrigeration recovery cycle; a fifth heat exchanger provided downstream of the third expansion turbine in the third cold energy recovery cycle and configured to transfer cold energy from the first fuel flowing downstream of the fourth heat exchanger in the first fuel supply line to the third heat medium, The cold energy recovery system according to any one of claims 1 to 3.

5. The third cold heat recovery cycle is a third pump provided downstream of the fifth heat exchanger in the third cold heat recovery cycle for increasing the pressure of the third heat medium; a third evaporator provided downstream of the third pump in the third cold heat recovery cycle for evaporating the third heat medium, The cold energy recovery system according to claim 4 .

6. a first bypass line for guiding the second fuel from a side upstream of the second heat exchanger on the second fuel supply line to the fourth heat exchanger, bypassing the second heat exchanger; a flow rate adjustment valve provided on the second fuel supply line between a connection position of an upstream end of the first bypass line and the second heat exchanger, the flow rate adjustment valve being configured to adjust a flow rate of the second fuel passing through the flow rate adjustment valve. The cold energy recovery system according to claim 4 or 5.

7. the second fuel comprises hydrogen; The cold heat recovery system includes: a combustion device configured to combust the first fuel and the second fuel, the combustion device being connected to the first fuel supply line downstream of the third heat exchanger and to the second fuel supply line downstream of the second heat exchanger; a mixture ratio acquisition device configured to acquire a mixture ratio of the first fuel and the second fuel introduced into the combustion device; a control device configured to stop operation of either the first cold heat recovery cycle or the second cold heat recovery cycle when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device is equal to or less than a predetermined value, The cold energy recovery system according to claim 6 .

8. the second fuel comprises hydrogen; The cold heat recovery system includes: a combustion device configured to combust the first fuel and the second fuel, the combustion device being connected to the first fuel supply line downstream of the third heat exchanger and to the second fuel supply line downstream of the second heat exchanger; a mixture ratio acquisition device configured to acquire a mixture ratio of the first fuel and the second fuel introduced into the combustion device; a control device configured to stop operation of the third cold energy recovery cycle when the mixture ratio of the second fuel acquired by the mixture ratio acquisition device is equal to or less than a predetermined value, The cold energy recovery system according to any one of claims 4 to 6.

9. a fourth refrigeration recovery cycle configured to circulate a fourth heat medium, the fourth refrigeration recovery cycle including a fourth expansion turbine for expanding the fourth heat medium in a gaseous state provided on the fourth refrigeration recovery cycle; a sixth heat exchanger provided downstream of the fourth expansion turbine in the fourth cold energy recovery cycle and configured to transfer cold energy from the second fuel flowing upstream of the second heat exchanger in the second fuel supply line to the fourth heat medium, The cold energy recovery system according to any one of claims 1 to 8.

10. a fifth refrigeration recovery cycle configured to circulate a fifth heat medium having a freezing point higher than that of the fourth heat medium, the fifth refrigeration recovery cycle including a fifth expansion turbine for expanding the fifth heat medium in a gaseous state provided on the fifth refrigeration recovery cycle; a fourth evaporator provided upstream of the fourth expansion turbine in the fourth cold energy recovery cycle and configured to transfer thermal energy from the fifth heat medium flowing downstream of the fifth expansion turbine in the fifth cold energy recovery cycle to the fourth heat medium, The cold heat recovery system according to claim 9.

11. The fourth cold heat recovery cycle is a fourth pump provided downstream of the sixth heat exchanger and upstream of the fourth evaporator in the fourth refrigeration recovery cycle for increasing the pressure of the fourth heat medium; The fifth cold heat recovery cycle is a fifth pump provided downstream of the fourth evaporator in the fifth cold heat recovery cycle for increasing the pressure of the fifth heat medium; a fifth evaporator provided downstream of the fifth pump in the fifth cold heat recovery cycle for evaporating the fifth heat medium, The cold energy recovery system according to claim 10.

12. a second bypass line for guiding the fifth heat medium from a downstream side of the fifth expansion turbine in the fifth cold heat recovery cycle to the fifth pump, bypassing the fourth evaporator; a second fuel-side first heater for heating the second fuel, the second fuel-side first heater being provided on the second fuel supply line downstream of the second heat exchanger; a second fuel side second heater for heating the second fuel, the second fuel side second heater being provided on the second fuel supply line downstream of the second heat exchanger and upstream of the second fuel side first heater, The second fuel side second heater is configured to heat the fifth heat medium flowing through the second bypass line. configured to transfer thermal energy to the second fuel flowing through the second fuel supply line; The cold energy recovery system according to claim 11.

13. the first fuel comprises natural gas; the second fuel consists of hydrogen; The cold energy recovery system according to any one of claims 1 to 12.

14. A system comprising the cold energy recovery system according to any one of claims 1 to 13. Ships or floating bodies.

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