Cold and heat recovery system and method for starting the cold and heat recovery system

Abstract

To provide a cold recovery system capable of suppressing clogging of a heat exchanger at start of the cold recovery system, and a starting method for the cold recovery system.SOLUTION: A cold recovery system 1 includes: a first heat exchanger 11 transferring cold energy from liquefied gas to a cold heating medium; a cold recovery cycle 3 including a cold pump 31 provided downstream of the first heat exchanger; a second heat exchanger 14 transferring thermal energy from a heating medium to the cold heating medium flowing between the cold pump and the first heat exchanger; a gas liquid separator 5 provided between the first heat exchanger and the cold pump and separating the cold heating medium into a gas phase and a liquid phase; a liquid return line 6 for returning the liquid phase cold heating medium from between the cold pump and the second heat exchanger to the gas liquid separator; and a third heat exchanger 7 transferring cold energy of the liquefied gas to the liquid cold heating medium to be returned to the gas liquid separator via the liquid return line or the cold heating medium present in the gas liquid separator.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a cold energy recovery system for recovering the cold energy of liquefied gas, and a method for starting the cold energy recovery system.

Background Art

[0002] Liquefied gas (e.g., liquefied natural gas) is liquefied for the purpose of transportation and storage, and when supplied to a supply destination such as city gas or a thermal power plant, it is heated and vaporized by a heat medium such as seawater. When vaporizing liquefied gas, there are cases where the cold energy of the liquefied gas is recovered instead of being discarded into seawater (e.g., Patent Document 1).

[0003] Patent Document 1 discloses a cold power generation cycle that recovers the cold energy of liquefied natural gas as electric power. As this cold power generation cycle, a secondary medium Rankine cycle method and the like are known (see Patent Document 1). The secondary medium Rankine cycle method is a method in which a secondary medium circulating in a closed loop is heated and evaporated using seawater as a heat source in an evaporator, the vapor is introduced into a turbine for cold power generation to obtain power, and then cooled and condensed with liquefied natural gas.

[0004] It is difficult to provide onshore LNG bases corresponding to each supply destination of liquefied natural gas because it is costly in terms of securing land and the like. For this reason, a ship equipped with an LNG storage facility for storing liquefied natural gas and a regasification facility for regasifying liquefied natural gas is moored at sea, and the liquefied natural gas regasified by the ship is sent via a pipeline to an onshore supply destination, an offshore power gauge (floating power plant), or the like.

[0005] Since a ship has less expandability than onshore facilities, in order to mount a cold power generation facility, miniaturization of the cold power generation system, particularly miniaturization of the heat exchanger, is important. Examples of small heat exchangers include printed circuit heat exchangers (PCHEs) and plate heat exchangers.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When one heat exchange target is at a lower temperature than the freezing point of the other heat exchange target, in the heat exchange in the heat exchanger, one heat exchange target may solidify, and the solidified heat exchange target may adhere to the surface of the heat exchanger, potentially blocking the heat exchanger. Compared with large heat exchangers (for example, shell-and-tube heat exchangers), small heat exchangers have a higher risk of blockage, so there are problems with reliability.

[0008] In a thermoelectric power generation cycle, when cooling the secondary medium circulating in the thermoelectric power generation cycle in the heat exchanger with liquefied natural gas, there is a risk of the heat exchanger freezing. Especially when starting a thermoelectric power generation cycle with a small flow rate of the secondary medium circulating in the thermoelectric power generation cycle, the temperature of the secondary medium drops compared to steady operation, so the heat exchanger is highly likely to freeze. To prevent the freezing of the heat exchanger, it is conceivable to provide a heating line for preheating the liquefied natural gas supplied to the heat exchanger, but such a heating line is not preferable because it leads to an increase in the size and cost of the system equipped with the thermoelectric power generation cycle.

[0009] In addition, in order to prevent the freezing of the heat exchanger, it is conceivable to increase the flow rate of the secondary medium that circulates through the thermoelectric power generation cycle when the thermoelectric power generation cycle is started. However, due to the heat input from the surrounding air to the thermoelectric power generation cycle when the thermoelectric power generation cycle stops, the secondary medium may vaporize in the thermoelectric power generation cycle. For this reason, at the start of the thermoelectric power generation cycle, the ratio of the gas phase of the secondary medium in the circulation pump for circulating the secondary medium is larger than that during the steady operation of the thermoelectric power generation cycle. If the circulation amount of the circulation pump for circulating the secondary medium is increased, there is a problem that the possibility of starting failure due to gas biting of the circulation pump increases at the start of the thermoelectric power generation cycle.

[0010] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a cold heat recovery system capable of suppressing blockage of a heat exchanger at the start of a cold heat recovery system, and a method for starting the cold heat recovery system.

Means for Solving the Problems

[0011] A cold heat recovery system according to an embodiment of the present disclosure is a cold heat recovery system installed on a ship or a floating body having a liquefied gas storage device configured to store liquefied gas, a first heat exchanger configured to transfer cold heat energy from the liquefied gas withdrawn from the liquefied gas storage device to a heat medium for cold heat, a cold heat recovery cycle configured to circulate the heat medium for cold heat, the cold heat recovery cycle including at least a cold heat pump for sending the heat medium for cold heat provided downstream of the first heat exchanger, a second heat exchanger configured to transfer heat energy from a heat medium to the heat medium for cold heat flowing downstream of the cold heat pump in the cold heat recovery cycle and upstream of the first heat exchanger, a gas-liquid separator provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle, configured to separate the heat medium for cold heat into a gas-phase heat medium for cold heat and a liquid-phase heat medium for cold heat A liquid return line for returning the liquid-phase heat medium for cold heat from the downstream side of the cold-heat pump in the cold-heat recovery cycle and upstream of the second heat exchanger to the gas-liquid separator; A third heat exchanger configured to transfer the cold-heat energy of the liquefied gas withdrawn from the liquefied gas storage device to either the liquid-phase heat medium for cold heat returned to the gas-liquid separator via the liquid return line or the heat medium for cold heat present inside the gas-liquid separator.

[0012] A method for starting a cold-heat recovery system according to an embodiment of the present disclosure is as follows: A method for starting a cold-heat recovery system installed on a ship or floating body having a liquefied gas storage device configured to store liquefied gas, The cold-heat recovery system includes: A first heat exchanger configured to transfer cold-heat energy from the liquefied gas withdrawn from the liquefied gas storage device to a heat medium for cold heat; A cold-heat recovery cycle configured to circulate the heat medium for cold heat, the cold-heat recovery cycle including at least a cold-heat pump for sending the heat medium for cold heat provided downstream of the first heat exchanger; A second heat exchanger configured to transfer heat energy from a heat medium to the heat medium for cold heat flowing downstream of the cold-heat pump in the cold-heat recovery cycle and upstream of the first heat exchanger; The method for starting the cold-heat recovery system includes: A gas-liquid separation step of separating the heat medium for cold heat into a gas-phase heat medium for cold heat and a liquid-phase heat medium for cold heat by a gas-liquid separator provided between the first heat exchanger and the cold-heat pump in the cold-heat recovery cycle; A circulation step of driving the cold-heat pump and returning the liquid-phase heat medium for cold heat separated in the gas-liquid separation step to the gas-liquid separator via a liquid return line connecting the downstream side of the cold-heat pump in the cold-heat recovery cycle and upstream of the second heat exchanger to the gas-liquid separator; In the circulation step, a cooling step of transferring and cooling the cold thermal energy of the liquefied gas extracted from the liquefied gas storage device to either the liquid-phase heat medium for cold heat returned to the gas-liquid separator through the liquid return line or the heat medium for cold heat present inside the gas-liquid separator is provided.

Advantages of the Invention

[0013] According to at least one embodiment of the present disclosure, there is provided a cold heat recovery system capable of suppressing blockage of a heat exchanger at the time of starting the cold heat recovery system, and a method for starting the cold heat recovery system.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0015] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure thereto, but are merely illustrative examples. For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent states in which there are tolerances or relative displacements with angles and distances that can obtain the same function. For example, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent states in which there are tolerances or differences that can obtain the same function. For example, expressions indicating shapes such as a rectangular shape or a cylindrical shape not only represent shapes such as a rectangular shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. On the other hand, the expressions "comprising", "including", or "having" for one component are not exclusive expressions that exclude the existence of other components. Note that the same reference numerals may be given to the same configurations and the description may be omitted.

[0016] (Ship, floating body) FIG. 1 is a schematic configuration diagram schematically showing the configuration of a ship 2A or a floating body 2B including a cold and heat recovery system 1 according to an embodiment of the present disclosure. The cold and heat recovery system 1 according to some embodiments is installed in a ship 2A or a floating body 2B as shown in FIG. 1. The ship 2A and the floating body 2B are structures that can float on water. The ship 2A and the floating body 2B have a liquefied gas storage device (for example, a liquefied gas tank) 21 configured to store liquefied gas and a cold and heat recovery system 1. In the illustrated embodiment, the ship 2A and the floating body 2B have a propeller (not shown) such as a propeller and a propulsion device (not shown) configured to drive the propeller, and are configured to be self-propelled by driving the propulsion device. The present disclosure is also applicable to a non-self-propelled structure that does not have a propulsion device for the ship 2A or the floating body 2B to self-propel.

[0017] (Cold and Heat Recovery System) As shown in FIG. 1, the cold and heat recovery system 1 includes a first heat exchanger 11, a liquefied gas supply line 12 for supplying liquefied gas from the liquefied gas storage device 21 to the first heat exchanger 11, a vaporized gas supply line 13 for supplying the vaporized gas generated by vaporization of the liquefied gas in the first heat exchanger 11, a cold and heat recovery cycle 3 configured to circulate a heat medium for cold and heat that has exchanged heat with the liquefied gas in the first heat exchanger 11, a second heat exchanger 14, and a gas-liquid separator 5.

[0018] (Cold and Heat Recovery Cycle) The cooling / heating recovery cycle 3 is configured to circulate a cooling / heating heat medium under an organic Rankine cycle. In the following description, the upstream side in the circulation direction of the cooling / heating heat medium in the cooling / heating recovery cycle 3 may be simply referred to as the upstream side, and the downstream side in the above circulation direction may be simply referred to as the downstream side. The cooling / heating recovery cycle 3 includes a cooling / heating pump 31 for sending the cooling / heating heat medium and a cooling / heating turbine 32 configured to be driven by the cooling / heating heat medium. The cooling / heating pump 31 is provided on the downstream side of the first heat exchanger 11 and on the upstream side of the second heat exchanger 14 in the cooling / heating recovery cycle 3. The cooling / heating turbine 32 is provided on the upstream side of the first heat exchanger 11 and on the downstream side of the second heat exchanger 14 in the cooling / heating recovery cycle 3.

[0019] Hereinafter, liquefied natural gas (LNG) will be taken as a specific example of the liquefied gas supplied from the liquefied gas storage device 21 which is a supply source of the liquefied gas, and propane will be taken as a specific example of the cooling / heating heat medium circulating in the cooling / heating recovery cycle 3 for explanation. However, the present disclosure is also applicable when a liquefied gas other than liquefied natural gas (liquefied petroleum gas, liquid hydrogen, etc.) is used as the liquefied gas supplied from the liquefied gas storage device 21. Further, the present disclosure is also applicable when a heat medium other than propane (for example, an organic medium) is used as the cooling / heating heat medium flowing through the cooling / heating recovery cycle 3. Note that the cooling / heating heat medium has a lower boiling point and freezing point than water.

[0020] (First Heat Exchanger) The first heat exchanger (liquefied gas vaporizer, cooling / heating side condenser) 11 is configured to perform heat exchange between the liquefied gas sent from the liquefied gas supply line 12 and the cooling / heating heat medium flowing on the downstream side of the cooling / heating turbine 32 and on the upstream side of the cooling / heating pump 31 in the cooling / heating recovery cycle 3. In the illustrated embodiment, the first heat exchanger 11 includes a first liquefied gas side flow path 111 through which the liquefied gas sent from the liquefied gas supply line 12 flows and a first cooling / heating side flow path 112 through which the cooling / heating heat medium circulating in the cooling / heating recovery cycle 3 flows. The liquefied gas flowing through the first liquefied gas side flow path 111 is at a lower temperature than the cooling / heating heat medium flowing through the first cooling / heating side flow path 112.

[0021] In the first heat exchanger 11, heat exchange is performed between the liquefied gas flowing through the first liquefied gas side flow path 111 and the heat medium for cold heat flowing through the first cold heat side flow path 112, and the cold heat energy of the liquefied gas flowing through the first liquefied gas side flow path 111 is transmitted to the heat medium for cold heat flowing through the first cold heat side flow path 112. As a result, the liquefied gas flowing through the first liquefied gas side flow path 111 is heated and vaporized, and the heat medium for cold heat flowing through the first cold heat side flow path 112 is cooled and condensed.

[0022] (Second heat exchanger) The second heat exchanger (cold heat side evaporator) 14 is configured to perform heat exchange between the external water (heat medium) introduced from outside the cold heat recovery system 1 and the heat medium for cold heat flowing in the cold heat recovery cycle 3 on the downstream side of the cold heat pump 31 and on the upstream side of the cold heat turbine 32. In the illustrated embodiment, the second heat exchanger 14 includes a second cold heat side flow path 141 through which the heat medium for cold heat flows and a heat medium side flow path 142 through which the external water flows. The second cold heat side flow path 141 (second heat exchanger 14) is provided in the cold heat recovery cycle 3 on the downstream side of the cold heat pump 31 and on the upstream side of the cold heat turbine 32. The external water flowing through the heat medium side flow path 142 is at a higher temperature than the heat medium for cold heat flowing through the second cold heat side flow path 141.

[0023] In the second heat exchanger 14, heat exchange is performed between the heat medium for cold heat flowing through the second cold heat side flow path 141 and the external water flowing through the heat medium side flow path 142, and the heat energy of the external water flowing through the heat medium side flow path 142 is transmitted to the heat medium for cold heat flowing through the second cold heat side flow path 141. As a result, the heat medium for cold heat flowing through the second cold heat side flow path 141 is heated and vaporized.

[0024] (Liquefied gas supply system) One side (the upstream end) of the liquefied gas supply line 12 is connected to the liquefied gas storage device 21, and the other side (the downstream end) of the liquefied gas supply line 12 is connected to the upstream end (the gas inlet of the first heat exchanger 11) of the first liquefied gas side flow path 111. One side (the upstream end) of the vaporized gas supply line 13 is connected to the downstream end (the gas outlet of the first heat exchanger 11) of the first liquefied gas side flow path 111, and the other side (the downstream end) of the vaporized gas supply line 13 is connected to the supply destination 22 of the vaporized gas. Note that the supply destination 22 of the vaporized gas may be a facility provided outside the ship 2A or the floating body 2B (for example, an onshore power generation facility or a gas storage facility), or a facility mounted on the ship 2A or the floating body 2B.

[0025] The cold heat recovery system 1 further includes a liquefied gas pump 15 provided in the liquefied gas supply line 12. The liquefied gas pump 15 has a rotor blade (not shown) provided in the liquefied gas supply line 12, and by rotating this rotor blade by power supplied to the liquefied gas pump 15 or the like, the liquefied gas is sent to the downstream side of the liquefied gas supply line 12 (the side where the first heat exchanger 11 is located). By driving the liquefied gas pump 15, the liquefied gas stored in the liquefied gas storage device 21 is extracted into the liquefied gas supply line 12 and sent through the liquefied gas supply line 12 to the first liquefied gas side flow path 111 of the first heat exchanger 11. The vaporized gas generated by the vaporization of the liquefied gas in the first liquefied gas side flow path 111 of the first heat exchanger 11 is sent by the liquefied gas pump 15 through the vaporized gas supply line 13 to the supply destination 22 of the gas.

[0026] (External water supply system) The cold heat recovery system 1 further includes an external water supply line 42 for supplying external water from the external water supply source 41 to a heat exchanger (the second heat exchanger 14) that uses the external water of the cold heat recovery system 1 as a heat medium, an external water discharge line 44 for discharging the external water discharged from the heat exchanger that uses the external water as a heat medium to the external water discharge destination 43, and an external water pump 45 provided in the external water supply line 42.

[0027] One side (upstream end) of the external water supply line 42 is connected to the external water supply source 41, and the other side (downstream end) of the external water supply line 42 is connected to the upstream end of the heat medium side flow path 142 (the heat medium inlet of the second heat exchanger 14). One side (upstream end) of the external water discharge line 44 is connected to the downstream end of the heat medium side flow path 142 (the heat medium outlet of the second heat exchanger 14), and the other side (downstream end) of the external water discharge line 44 is connected to the external water discharge destination 43. The external water may be water that can heat the heat exchange object as a heat medium in the heat exchanger (water at a temperature higher than the heat exchange object), and may be normal temperature water. The external water is preferably water that is easily available on the ship 2A or the floating body 2B (for example, seawater outside the ship or engine cooling water that has cooled the engine of the ship 2A).

[0028] The external water supply source 41 may be a water intake provided on the ship 2A or the floating body 2B for taking in external water (for example, seawater) from outside the ship 2A or the floating body 2B, or may be a facility (for example, a water storage tank) provided inside the ship 2A or the floating body 2B. Further, the external water discharge destination 43 may be a drain port provided on the ship 2A or the floating body 2B for discharging external water to the outside of the ship 2A or the floating body 2B, or may be a facility (for example, a drainage tank) provided inside the ship 2A or the floating body 2B.

[0029] The external water pump 45 has a moving blade (not shown) provided in the external water supply line 42, and by rotating this moving blade by power supplied to the external water pump 45 or the like, it is configured to send external water to the downstream side of the external water supply line 42 (the side where the second heat exchanger 14 is located). By driving the external water pump 45, external water is extracted from the external water supply source 41 into the external water supply line 42, and the external water is sent through the external water supply line 42 to a heat exchanger (the second heat exchanger 14) using the external water as a heat medium.

[0030] (Cooling and heating heat medium circulation system) As shown in FIG. 1, the cooling / heating recovery cycle 3 further includes a first connection line 33 and a second connection line 34. The first connection line 33 connects the downstream end of the first cooling / heating side flow path 112 (the outlet of the cooling / heating heat medium of the first heat exchanger 11) and the upstream end of the second cooling / heating side flow path 141 (the inlet of the cooling / heating heat medium of the second heat exchanger 14). The above-described cooling / heating pump 31 is provided in the first connection line 33. The second connection line 34 connects the downstream end of the second cooling / heating side flow path 141 (the outlet of the cooling / heating heat medium of the second heat exchanger 14) and the upstream end of the first cooling / heating side flow path 112 (the inlet of the cooling / heating heat medium of the first heat exchanger 11). The above-described cooling / heating turbine 32 is provided in the second connection line 34.

[0031] (Gas-liquid separator) The gas-liquid separator 5 is configured to separate the cooling / heating heat medium into a gas phase and a liquid phase. The gas-liquid separator 5 is provided on the downstream side of the first cooling / heating side flow path 112 (the first heat exchanger 11) and on the upstream side of the cooling / heating pump 31 in the cooling / heating recovery cycle 3. Specifically, the gas-liquid separator 5 is provided on the upstream side of the cooling / heating pump 31 in the first connection line 33.

[0032] The gas-liquid separator 5 includes a main body portion 52 configured to define an internal space 51 into which the cooling / heating heat medium sent from the first cooling / heating side flow path 112 (the first heat exchanger 11) through the first connection line 33 is introduced, an inlet 53 for introducing the cooling / heating heat medium into the internal space 51, and a liquid phase discharge port 54 for discharging the liquid-phase cooling / heating heat medium from the internal space 51 to the outside of the gas-liquid separator 5.

[0033] The internal space 51 includes a lower storage space 51B in which the liquid-phase cooling / heating heat medium is stored, and an upper storage space 51A in which the gas-phase cooling / heating heat medium communicated with the lower storage space 51B is stored above the lower storage space 51B. The liquid phase discharge port 54 communicates with the lower storage space 51B.

[0034] The above-described first connection line 33 includes a first upper connection line 33A that connects the downstream end of the first cold and hot side flow path 112 and the introduction port 53, a first middle connection line 33B that connects the liquid phase discharge port 54 and the pump inlet 311 of the cold and hot pump 31, and a first lower connection line 33C that connects the pump outlet 312 of the cold and hot pump 31 and the upstream end of the second cold and hot side flow path 141.

[0035] The cold and hot heat medium cooled by the first heat exchanger 11 is guided to the gas-liquid separator 5 through the first upper connection line 33A. The cold and hot heat medium flowing into the internal space 51 from the introduction port 53 is separated into a liquid phase and a gas phase in the internal space 51.

[0036] (Cold and hot pump) The cold and hot pump 31 is configured to send the cold and hot heat medium to the downstream side of the cold and hot recovery cycle 3 (the side where the second heat exchanger 14 is located). The cold and hot pump 31 has a moving blade (not shown) provided in the first connection line 33, and by rotating this moving blade by the electric power supplied to the cold and hot pump 31 or the like, it is configured to send the liquid-phase cold and hot heat medium to the downstream side of the first connection line 33.

[0037] By driving the cold and hot pump 31, the liquid-phase cold and hot heat medium stored in the lower storage space 51B is guided to the cold and hot pump 31 through the liquid phase discharge port 54 and the first middle connection line 33B and is pressurized by the cold and hot pump 31. The liquid-phase cold and hot heat medium pressurized by the cold and hot pump 31 is sent by the cold and hot pump 31 to the second cold and hot side flow path 141 (the second heat exchanger 14) through the first lower connection line 33C.

[0038] (Cold and hot pump related equipment) As shown in FIG. 1, the cooling and heating recovery system 1 further includes a liquid return line 6 for returning the liquid-phase cooling and heating heat medium from a position downstream of the cooling and heating pump 31 and upstream of the second heat exchanger 14 in the cooling and heating recovery cycle 3 to the gas-liquid separator 5, and a first flow rate adjustment valve 35 provided between a connection portion P1 between the upstream end of the liquid return line 6 in the cooling and heating recovery cycle 3 and the second heat exchanger 14. The first flow rate adjustment valve 35 is configured to be able to adjust the flow rate of the liquid-phase cooling and heating heat medium guided to the second heat exchanger 14.

[0039] In the illustrated embodiment, the gas-liquid separator 5 further includes a liquid return port 55 for introducing the liquid-phase cooling and heating heat medium from the liquid return line 6 into the internal space 51. The liquid return port 55 communicates with the internal space 51. One side (upstream end) of the liquid return line 6 is connected to the connection portion P1 of the first lower connection line 33C, and the other side (downstream end) of the liquid return line 6 is connected to the liquid return port 55. The first flow rate adjustment valve 35 is provided downstream of the connection portion P1 of the first lower connection line 33C. The first flow rate adjustment valve 35 can adjust the flow rate of the cooling and heating heat medium supplied to the downstream side (the second heat exchanger 14 side) of the valve body by moving a valve body (not shown) that opens and closes the flow path of the cooling and heating heat medium. Note that the first flow rate adjustment valve 35 may be an on-off valve whose opening can be adjusted between fully closed and fully open, or an opening adjustment valve whose opening can be adjusted between fully closed, fully open, and at least one intermediate opening between them.

[0040] (Cooling and heating turbine) In the turbine 32 for cooling and heating, a heat medium for cooling and heating that has been pressurized by the pump 31 for cooling and heating and whose temperature has been raised by the second heat exchanger 14 is introduced as a working fluid. The turbine 32 for cooling and heating includes a rotating shaft 321, turbine blades 322 attached to the rotating shaft 321, and a casing 323 that rotatably houses the turbine blades 322. In the casing 323, an inlet 324 for introducing the heat medium for cooling and heating into the interior of the casing 323 and an outlet 325 for discharging the heat medium for cooling and heating that has passed through the turbine blades 322 to the outside of the casing 323 are formed. The turbine 32 for cooling and heating is configured to rotate the turbine blades 322 by the energy of the heat medium for cooling and heating introduced into the interior of the casing 323 through the inlet 324. The heat medium for cooling and heating that has passed through the turbine blades 322 is discharged to the outside of the casing 323 through the outlet 325.

[0041] The cooling and heating recovery cycle 3 is configured to recover the rotational force generated by the turbine blades 322 as power. In the illustrated embodiment, the cooling and heating recovery cycle 3 further includes a generator 326 for cooling and heating that is configured to generate electricity by driving the turbine 32 for cooling and heating. The generator 326 for cooling and heating is mechanically connected to the rotating shaft 321 and is configured to convert the rotational force of the turbine blades 322 into electric power. In some other embodiments, the cooling and heating recovery cycle 3 may recover the rotational force generated by the turbine blades 322 as power directly through a power transmission device (for example, a coupling, a belt, a pulley, etc.) instead of converting it into electric power.

[0042] The second connection line 34 described above includes a second upper connection line 34A that connects the downstream end of the second cooling and heating side flow path 141 and the inlet 324 of the turbine 32 for cooling and heating, and a second lower connection line 34B that connects the outlet 325 of the turbine 32 for cooling and heating and the upstream end of the first cooling and heating side flow path 112.

[0043] (Equipment related to the turbine for cooling and heating) As shown in FIG. 1, the cooling and heating recovery cycle 3 further includes a turbine bypass line 36 that connects the upstream side and the downstream side of the cooling and heating turbine 32 of the second connection line 34 by bypassing the cooling and heating turbine 32, a turbine side flow control valve 37, and a turbine bypass side flow control valve 38.

[0044] One side (upstream end) of the turbine bypass line 36 is connected to the branch portion P2 of the second upper connection line 34A, and the other side (downstream end) of the turbine bypass line 36 is connected to the confluence portion P3 of the second lower connection line 34B. The turbine side flow control valve 37 is provided on the downstream side (toward the cooling and heating turbine 32) of the branch portion P2 of the second upper connection line 34A. The turbine bypass side flow control valve 38 is provided on the turbine bypass line 36. Each of the turbine side flow control valve 37 and the turbine bypass side flow control valve 38 can adjust the flow rate of the cooling and heating heat medium supplied to the downstream side of the valve body by moving a valve body (not shown) that opens and closes the flow path of the cooling and heating heat medium. Note that each of the turbine side flow control valve 37 and the turbine bypass side flow control valve 38 may be an on-off valve whose opening degree can be adjusted between fully closed and fully open, or an opening degree control valve whose opening degree can be adjusted between fully closed, fully open, and at least one intermediate opening degree therebetween.

[0045] By opening the turbine side flow control valve 37 (fully open or intermediate opening degree) and closing the turbine bypass side flow control valve 38, the cooling and heating heat medium can be sent to the first heat exchanger 11 via the cooling and heating turbine 32. Also, by closing the turbine side flow control valve 37 and opening the turbine bypass side flow control valve 38 (fully open or intermediate opening degree), the cooling and heating heat medium can be sent to the first heat exchanger 11 via the turbine bypass line 36.

[0046] (Third heat exchanger) As shown in FIG. 1, the cold and heat recovery system 1 according to some embodiments further includes a third heat exchanger 7 configured to transfer the cold and heat energy of the liquefied gas withdrawn from the liquefied gas storage device 21 to either the liquid-phase heat medium for cold and heat returning to the gas-liquid separator 5 via the liquid return line 6 or the heat medium for cold and heat existing inside the gas-liquid separator 5.

[0047] The third heat exchanger (pre-cooler) 7 is configured to perform heat exchange between the liquefied gas withdrawn from the liquefied gas storage device 21 and the heat medium for cold and heat circulating via the gas-liquid separator 5 and the liquid return line 6. In the embodiment shown in FIG. 1, the third heat exchanger 7 (7A) includes a third cold and heat side flow path 71 through which the heat medium for cold and heat flowing in the liquid return line 6 flows, and a second liquefied gas side flow path 72 through which the liquefied gas flows. The heat medium for cold and heat flowing through the third cold and heat side flow path 71 is at a higher temperature than the liquefied gas flowing through the second liquefied gas side flow path 72.

[0048] In the third heat exchanger 7 (7A), heat exchange is performed between the heat medium for cold and heat flowing through the third cold and heat side flow path 71 and the liquefied gas flowing through the second liquefied gas side flow path 72, and the cold and heat energy of the liquefied gas flowing through the second liquefied gas side flow path 72 is transferred to the heat medium for cold and heat flowing through the third cold and heat side flow path 71. Thereby, the heat medium for cold and heat flowing through the third cold and heat side flow path 71 is cooled.

[0049] (Liquefied gas introduction system for pre-cooler) As shown in FIG. 1, the cold and heat recovery system 1 further includes a liquefied gas introduction line 81 for guiding the liquefied gas from the liquefied gas storage device 21 to the third heat exchanger 7, and a gas discharge line 82 for guiding the vaporized gas obtained by vaporizing the liquefied gas from the third heat exchanger 7.

[0050] In the embodiment shown in FIG. 1, one side (upstream end) of the liquefied gas introduction line 81 is connected to a connection position P4 on the downstream side of the liquefied gas pump 15 in the liquefied gas supply line 12. The other side (downstream end) of the liquefied gas introduction line 81 is connected to the upstream end (gas inlet of the third heat exchanger 7) of the second liquefied gas side flow path 72. One side (upstream end) of the gas discharge line 82 (82A) is connected to the downstream end (gas outlet of the third heat exchanger 7) of the second liquefied gas side flow path 72. The other side (downstream end) of the gas discharge line 82 (82A) is connected to the connection position P5 of the vaporized gas supply line 13.

[0051] By driving the liquefied gas pump 15, the liquefied gas stored in the liquefied gas storage device 21 is extracted into the liquefied gas supply line 12, and is sent through the portion upstream of the connection position P4 in the liquefied gas supply line 12 and the liquefied gas introduction line 81 to the second liquefied gas side flow path 72 of the third heat exchanger 7.

[0052] The vaporized gas generated by the vaporization of the liquefied gas in the second liquefied gas side flow path 72 of the third heat exchanger 7 is sent by the liquefied gas pump 15 to the gas supply destination 22 through the portion downstream of the connection position P5 in the gas discharge line 82 (82A) and the vaporized gas supply line 13.

[0053] In the embodiment shown in FIG. 1, the cold heat recovery system 1 further includes a second flow rate adjustment valve 83, a third flow rate adjustment valve 84, a fourth flow rate adjustment valve 85, and a fifth flow rate adjustment valve 86. The second flow rate adjustment valve 83 is an opening degree adjustment valve whose opening degree can be adjusted to fully closed, fully open, and at least one intermediate opening degree therebetween. Each of the flow rate adjustment valves 84, 85, and 86 may be an on-off valve whose opening degree can be adjusted to fully closed and fully open, or may be an opening degree adjustment valve whose opening degree can be adjusted to fully closed, fully open, and at least one intermediate opening degree therebetween.

[0054] The second flow rate adjustment valve 83 is provided in the liquefied gas introduction line 81 and is configured to be able to adjust the flow rate of the liquefied gas led to the third heat exchanger 7. The third flow rate adjustment valve 84 is provided on the downstream side of the connection position P4 of the liquefied gas supply line 12 and is configured to be able to adjust the flow rate of the liquefied gas led to the first heat exchanger 11. By opening the second flow rate adjustment valve 83 (fully open or intermediate opening degree) and closing the third flow rate adjustment valve 84, the liquefied gas can be sent from the liquefied gas storage device 21 to the third heat exchanger 7 by the liquefied gas pump 15. Also, by closing the second flow rate adjustment valve 83 and opening the third flow rate adjustment valve 84 (fully open or intermediate opening degree), the liquefied gas can be sent from the liquefied gas storage device 21 to the first heat exchanger 11 by the liquefied gas pump 15.

[0055] The fourth flow rate adjustment valve 85 is provided on the upstream side of the connection position P5 of the vaporized gas supply line 13 and is configured to be able to adjust the flow rate of the vaporized gas led to the gas supply destination 22. The fifth flow rate adjustment valve 86 is provided in the gas discharge line 82 and is configured to be able to adjust the flow rate of the vaporized gas led to the gas supply destination 22. By opening the fourth flow rate adjustment valve 85 (fully open or intermediate opening degree) and closing the fifth flow rate adjustment valve 86, the heat medium for cold can be sent from the first heat exchanger 11 to the gas supply destination 22 by the liquefied gas pump 15. Also, by closing the fourth flow rate adjustment valve 85 and opening the fifth flow rate adjustment valve 86 (fully open or intermediate opening degree), the heat medium for cold can be sent from the third heat exchanger 7 to the gas supply destination 22 by the liquefied gas pump 15.

[0056] (Method for starting the cold heat recovery system) FIG. 2 is a flowchart of a method for starting a cold heat recovery system according to an embodiment of the present disclosure. FIG. 3 is an explanatory diagram for explaining an example of control in a cold heat recovery system according to an embodiment of the present disclosure. As shown in FIGS. 2 and 3, the period from the start-up of the cold heat recovery system 1 to the steady operation of the cold heat recovery system 1 is divided into a first period (pre-cooling period) T1, a second period (transition period) T2, and a third period (cold heat recovery period) T3. The second period T2 is a period after the first period T1 and a period before the third period T3.

[0057] In the first period T1, the liquefied gas withdrawn from the liquefied gas storage device 21 is sent to the third heat exchanger 7. In the third period T3, the liquefied gas withdrawn from the liquefied gas storage device 21 is sent to the first heat exchanger 11. In the second period T2, the destination of the liquefied gas withdrawn from the liquefied gas storage device 21 is changed from the third heat exchanger 7 to the first heat exchanger 11.

[0058] As shown in FIG. 2, the startup method 100 of the cold heat recovery system 1 according to some embodiments includes a gas-liquid separation step S101, a circulation step S102, and a cooling step S103.

[0059] In the gas-liquid separation step S101, the cold heat transfer medium is separated into a gas phase and a liquid phase by the above-described gas-liquid separator 5. The gas-liquid separation step S101 is continuously performed during the period from the startup of the cold heat recovery system 1 to the steady operation and during the steady operation.

[0060] Due to the heat input from the ambient air to the cold heat recovery cycle 3 and the gas-liquid separator 5 when the cold heat recovery system 1 stops, the cold heat transfer medium in the cold heat recovery cycle 3 may vaporize. Therefore, at the startup of the cold heat recovery system 1, compared with the steady operation of the cold heat recovery system 1, the ratio of the gas-phase cold heat transfer medium in the cold heat recovery cycle 3, such as the gas-liquid separator 5 and the cold heat pump 31, is larger than that in the first heat exchanger 11 and downstream of the second heat exchanger 14. If the ratio of the gas-phase cold heat transfer medium in the cold heat pump 31 is large, there is a risk of capacity reduction due to gas biting of the cold heat pump 31.

[0061] In the circulation step S102, the cold and heat pump 31 is driven, and the liquid-phase cold and heat medium separated in the gas-liquid separation step S101 is returned to the gas-liquid separator 5 through the liquid return line 6. As a result, the liquid-phase cold and heat medium circulates through the gas-liquid separator 5, the cold and heat pump 31, and the liquid return line 6. The circulation step S102 starts in the first period T1 and continues until the second period T2.

[0062] Specifically, in the circulation step S102, with the first flow rate adjustment valve 35 fully closed, the cold and heat pump 31 is driven, and the liquid-phase cold and heat medium is withdrawn from the gas-liquid separator 5 through the liquid-phase discharge port 54. The liquid-phase cold and heat medium withdrawn from the gas-liquid separator 5 passes through the upstream side of the connection part P1 of the first middle connection line 33B, the cold and heat pump 31, and the first lower connection line 33C from the cold and heat pump 31 and then through the liquid return line 6, and is then sent to the gas-liquid separator 5.

[0063] The cooling step S103 includes a cooling step S103 of transferring the cold energy of the liquefied gas withdrawn from the liquefied gas storage device 21 to either the liquid-phase cold and heat medium returned to the gas-liquid separator 5 through the liquid return line 6 in the circulation step S102 or the cold and heat medium existing inside the gas-liquid separator 5 to cool it.

[0064] In the cooling step S103, the liquefied gas is sent from the liquefied gas storage device 21 to the third heat exchanger 7, and the cold and heat medium is cooled by the liquefied gas in the third heat exchanger 7. As a result, the liquid-phase cold and heat medium circulating through the gas-liquid separator 5, the cold and heat pump 31, and the liquid return line 6 is cooled. In the illustrated embodiment, the cooling step S103 starts after the circulation step S102 in the first period T1. As shown in FIG. 3, the driving of the liquefied gas pump 15 is performed after the driving of the cold and heat pump 31.

[0065] Specifically, in the cooling step S103, the second flow rate adjustment valve 83 and the fifth flow rate adjustment valve 86 are opened (fully opened or at an intermediate opening degree), and the liquefied gas pump 15 is driven with the third flow rate adjustment valve 84 and the fourth flow rate adjustment valve 85 fully closed. As a result, liquefied gas can be sent from the liquefied gas storage device 21 to the third heat exchanger 7, and vaporized gas can be sent from the third heat exchanger 7 to the gas supply destination 22.

[0066] In the cooling step S103, the liquid-phase heat medium for cold heat circulating in the gas-liquid separator 5, the cold heat pump 31, and the liquid return line 6 is cooled, so that the temperature inside the gas-liquid separator 5 can be lowered, and thus the vapor-phase heat medium for cold heat existing inside the gas-liquid separator 5 can be condensed. As a result, the proportion of the liquid-phase heat medium for cold heat can be increased at an early stage on the downstream side of the first heat exchanger 11 and on the upstream side of the second heat exchanger 14 in the cold heat recovery cycle 3 such as the gas-liquid separator 5 and the cold heat pump 31. By increasing the proportion of the liquid-phase heat medium for cold heat in the cold heat pump 31, the reduction in capacity due to gas biting of the cold heat pump 31 can be suppressed, and thus the capacity of the cold heat pump 31 can be exerted from an early stage.

[0067] In the illustrated embodiment, as shown in FIG. 2, the startup method 100 of the cold heat recovery system 1 further includes an opening valve step S104 in which the first flow rate adjustment valve 35 is opened (changed from fully closed to fully opened or an intermediate opening degree) after the start of the cooling step S103, and the cold heat pump 31 sends the heat medium for cold heat to the first heat exchanger 11; a changing step S105 in which after the opening valve step S104, the sending destination of the liquefied gas withdrawn from the liquefied gas storage device 21 is changed from the third heat exchanger 7 to the first heat exchanger 11; a cold heat turbine driving step S106 in which after the changing step S105, the heat medium for cold heat is guided to the cold heat turbine 32 and the cold heat turbine 32 is driven; and an external water pump driving step S107 in which the external water pump 45 is driven before the opening valve step S104.

[0068] The valve opening step S104 is performed, for example, when the temperature inside the gas-liquid separator 5 becomes equal to or lower than a predetermined temperature (the temperature at which the heat medium for cooling and heating condenses). After the temperature inside the gas-liquid separator 5 becomes equal to or lower than the predetermined temperature, by adjusting the second flow rate adjustment valve 83, the temperature inside the gas-liquid separator 5 is maintained within a predetermined range with the predetermined temperature as the upper limit. The liquid-phase heat medium for cooling and heating that has passed through the first flow rate adjustment valve 35 is heated and vaporized in the second heat exchanger 14, and then sent to the first heat exchanger 11.

[0069] Specifically, the liquid-phase heat medium for cooling and heating that has passed through the first flow rate adjustment valve 35 passes through the downstream side of the first flow rate adjustment valve 35 in the first lower connection line 33C, the second heat medium side flow path 141 (the second heat exchanger 14), the upstream side of the branch portion P2 in the second upper connection line 34A, and the downstream side of the confluence portion P3 of the turbine bypass line 36 and the second lower connection line 34B, and then is sent to the first heat medium side flow path 112 (the first heat exchanger 11). As shown in FIG. 3, in the first period T1 and the second period T2, the turbine side flow rate adjustment valve 37 is fully closed and the turbine bypass side flow rate adjustment valve 38 is opened (fully opened or at an intermediate opening degree), so that the heat medium for cooling and heating is sent to the first heat exchanger 11 via the turbine bypass line 36.

[0070] Before the valve opening step S104, the external water pump 45 is driven (S107), and external water is supplied to the heat medium side flow path 142 of the second heat exchanger 14. The liquid-phase heat medium for cooling and heating that has passed through the first flow rate adjustment valve 35 is heated and vaporized by the external water (heat medium) in the second heat exchanger 14. Before the execution of the change step S105, heat exchange between the liquefied gas and the heat medium for cooling and heating does not occur in the first heat exchanger 11. The gas-phase heat medium for cooling and heating that has passed through the first heat exchanger 11 condenses in the gas-liquid separator 5 whose inside is cooled by the third heat exchanger 7.

[0071] In addition, in the valve opening step S104, by adjusting the opening degree of the first flow rate adjustment valve 35, the amount of the liquid-phase heat medium for cooling and heating inside the gas-liquid separator 5 can be stabilized.

[0072] In the above-mentioned second period T2, by executing the change step S105, the destination of the liquefied gas withdrawn from the liquefied gas storage device 21 is changed from the third heat exchanger 7 to the first heat exchanger 11. In the above-mentioned third period T3, the cold heat turbine driving step S106 is performed. That is, the cold heat turbine driving step S106 is performed after the change step S105.

[0073] The change step S105 is performed, for example, when the flow rate of the heat medium for cold heat in the liquid phase circulated by the cold heat pump 31 (the storage amount of the heat medium for cold heat in the liquid phase in the lower storage space 51B) reaches a certain amount or more and can be sent to the first heat exchanger 11 by the cold heat pump 31. In the change step S105, as shown in FIG. 3, the second flow rate adjustment valve 83 and the fifth flow rate adjustment valve 86 are closed (changed from fully open or intermediate opening to fully closed), and the third flow rate adjustment valve 84 and the fourth flow rate adjustment valve 85 are opened (changed from fully closed to fully open or intermediate opening). Thereby, the liquefied gas can be sent from the liquefied gas storage device 21 to the first heat exchanger 11, and the vaporized gas can be sent from the first heat exchanger 11 to the gas supply destination 22. After the execution of the change step S105, heat exchange between the liquefied gas and the heat medium for cold heat is performed in the first heat exchanger 11.

[0074] In the cold heat turbine driving step S106, as shown in FIG. 3, the turbine side flow rate adjustment valve 37 is opened (changed from fully closed to fully open or intermediate opening), and the turbine bypass side flow rate adjustment valve 38 is closed (changed from fully open or intermediate opening to fully closed). Thereby, the heat medium for cold heat pressurized by the cold heat pump 31 and heated in the second heat exchanger 14 is introduced into the cold heat turbine 32, and the turbine blades 322 of the cold heat turbine 32 rotate, so that the cold heat turbine 32 is driven.

[0075] According to the above method, the liquid-phase heat medium for cooling and heating that circulates through the gas-liquid separator 5, the cooling and heating pump 31, and the liquid return line 6 is cooled by the liquefied gas in the third heat exchanger 7 (cooling step S103), so that the proportion of the liquid-phase heat medium for cooling and heating can be increased earlier on the downstream side of the first heat exchanger 11 in the cooling and heating recovery cycle 3 such as the gas-liquid separator 5 and the cooling and heating pump 31. By increasing the proportion of the liquid-phase heat medium for cooling and heating in the cooling and heating pump 31, the reduction in capacity due to gas entrainment in the cooling and heating pump 31 can be suppressed, so that the capacity of the cooling and heating pump 31 can be exerted from the early stage. As a result, the cooling and heating recovery system 1 can be shifted to steady operation earlier.

[0076] Also, according to the above method, since the heat exchange in the first heat exchanger 11 does not occur until the flow rate of the heat medium for cooling and heating supplied to the first heat exchanger 11 reaches a large flow rate that does not cause blockage of the first heat exchanger 11, blockage of the first heat exchanger 11 at the start of the cooling and heating recovery system 1 can be suppressed.

[0077] The cooling and heating recovery system 1 according to some embodiments includes, as shown in FIG. 1, the first heat exchanger 11 described above, the second heat exchanger 14 described above, the cooling and heating recovery cycle 3 described above, the gas-liquid separator 5 described above, the liquid return line 6 described above, and the third heat exchanger 7 described above.

[0078] According to the above configuration, the liquid-phase heat medium for cooling and heating that circulates through the gas-liquid separator 5, the cooling and heating pump 31, and the liquid return line 6 is cooled by the liquefied gas in the third heat exchanger 7, so that the proportion of the liquid-phase heat medium for cooling and heating can be increased earlier on the downstream side of the first heat exchanger 11 in the cooling and heating recovery cycle 3 such as the gas-liquid separator 5 and the cooling and heating pump 31. By increasing the proportion of the liquid-phase heat medium for cooling and heating in the cooling and heating pump 31, the reduction in capacity due to gas entrainment in the cooling and heating pump 31 can be suppressed, so that the capacity of the cooling and heating pump 31 can be exerted from the early stage. As a result, the cooling and heating recovery system 1 can be shifted to steady operation earlier.

[0079] Further, according to the above configuration, until the flow rate of the heat medium for cold heat supplied to the first heat exchanger 11 reaches a large flow rate that does not cause blockage of the first heat exchanger 11, heat exchange in the first heat exchanger 11 is not performed, thereby suppressing blockage of the first heat exchanger 11 at the start of the cold heat recovery system 1.

[0080] In some embodiments, as shown in FIG. 1, the above-described cold heat recovery system 1 includes the above-described first flow rate adjustment valve 35. According to the above configuration, by closing the first flow rate adjustment valve 35, a closed circuit including the gas-liquid separator 5, the cold heat pump 31, and the liquid return line 6 can be formed. By cooling the heat medium for cold heat circulating in this closed circuit with liquefied gas in the third heat exchanger 7, the temperature inside the gas-liquid separator 5 can be lowered to a predetermined temperature or lower earlier than when cooling the heat medium for cold heat circulating in a cold heat recovery cycle 3 wider than the closed circuit. As a result, the cold heat recovery system 1 can be quickly shifted to steady operation.

[0081] In some embodiments, as shown in FIG. 1, the above-described third heat exchanger 7 (7A) is configured to transfer the cold heat energy of the liquefied gas extracted from the liquefied gas storage device 21 to the liquid-phase heat medium for cold heat flowing through the liquid return line 6. According to the above configuration, since the third heat exchanger 7 (7A) can cool the heat medium for cold heat flowing through the liquid return line 6 with liquefied gas, the temperature inside the gas-liquid separator 5 can be lowered to a predetermined temperature or lower earlier. As a result, the cold heat recovery system 1 can be quickly shifted to steady operation.

[0082] Each of FIGS. 4 to 8 is a schematic configuration diagram schematically showing the configuration of a ship or a floating body including a cold heat recovery system according to an embodiment of the present disclosure. In some embodiments, as shown in FIG. 4, the above-described liquid return line 6 includes a first liquid return line 6A provided with the third heat exchanger 7 and a second liquid return line 6B that bypasses the third heat exchanger 7.

[0083] In the illustrated embodiment, one side (upstream end) of the first liquid return line 6A is connected to the connection portion P1 of the first lower connection line 33C, and the other side (downstream end) is connected to the liquid return port 55. One side (upstream end) of the second liquid return line 6B is connected to the branch portion P6 located upstream of the third heat exchanger 7 of the first liquid return line 6A, and the other side (downstream end) is connected to the confluence portion P7 located downstream of the third heat exchanger 7 of the first liquid return line 6A.

[0084] As shown in FIG. 4, the above-described liquid return line 6 may further include a first on-off valve 61 provided between the branch portion P6 of the first liquid return line 6A and the third heat exchanger 7, and a second on-off valve 62 provided in the second liquid return line 6B. By opening the first on-off valve 61 and fully closing the second on-off valve 62, the circulating heat medium for cold heat passes through the third heat exchanger 7. By fully closing the first on-off valve 61 and opening the second on-off valve 62, the circulating heat medium for cold heat passes through the second liquid return line 6B (bypassing the third heat exchanger 7).

[0085] During the steady operation of the cold heat recovery system 1, the cold heat pump 31 is rotated at a steady rotation speed. Even after the execution of the valve opening step S104, the heat medium for cold heat is circulated through the liquid return line 6.

[0086] According to the above configuration, when it is not necessary to cool the heat medium for cold heat by the third heat exchanger 7 (for example, during steady operation), by causing the circulating heat medium for cold heat to pass through the second liquid return line 6B (bypassing the third heat exchanger 7), the pressure loss in the third heat exchanger 7 can be suppressed, so that the performance of the cold heat recovery cycle 3 can be effectively exhibited during the steady operation of the cold heat recovery system 1.

[0087] In some embodiments, as shown in FIG. 5, the third heat exchanger 7 (7B) is configured to transfer the cold heat energy of the liquefied gas withdrawn from the liquefied gas storage device 21 to the heat medium for cold heat existing inside the gas-liquid separator 5.

[0088] In the embodiment shown in FIG. 5, the third heat exchanger 7 (7B) includes a third liquefied gas side flow path 73 through which the liquefied gas disposed in the internal space 51 of the gas-liquid separator 5 flows. As shown in FIG. 5, the third liquefied gas side flow path 73 may be a pipe through which the liquefied gas can flow inside, and the outer surface thereof faces the internal space 51.

[0089] The other side (downstream end) of the liquefied gas introduction line 81 is connected to the upstream end of the third liquefied gas side flow path 73 (gas inlet of the third heat exchanger 7). One side (upstream end) of the gas discharge line 82 is connected to the downstream end of the third liquefied gas side flow path 73 (gas outlet of the third heat exchanger 7). The heat medium for cold heat existing in the internal space 51 is at a higher temperature than the liquefied gas flowing through the third liquefied gas side flow path 73.

[0090] In the third heat exchanger 7 (7B), heat exchange is performed between the heat medium for cold heat existing in the internal space 51 and the liquefied gas flowing through the third liquefied gas side flow path 73, and the cold heat energy of the liquefied gas flowing through the third liquefied gas side flow path 73 is transmitted to the heat medium for cold heat existing in the internal space 51. Thereby, the heat medium for cold heat existing in the internal space 51 is cooled.

[0091] According to the above configuration, the third heat exchanger 7 (7B) can cool the heat medium for cold heat existing inside the gas-liquid separator 5 with the liquefied gas, so that the temperature inside the gas-liquid separator 5 can be quickly lowered below a predetermined temperature. Thereby, the cold heat recovery system 1 can be quickly shifted to steady operation.

[0092] In some embodiments, as shown in FIGS. 1, 4, 6, and 7, the above-described gas supply destination 22 includes the main engine 22A of the ship 2A or the floating body 2B. The main engine 22A is configured to generate a driving force (propulsive force) for driving a propeller (not shown) or the like by the energy of the supplied vaporized gas. The above-described vaporized gas supply line 13 includes a fuel supply line 13A for supplying the liquefied gas vaporized in the first heat exchanger 11 to the main engine 22A of the ship 2A or the floating body 2B.

[0093] In the embodiments shown in FIGS. 1 and 4, the above-described gas discharge line 82 (82A) includes a flow path for guiding the vaporized gas obtained by vaporizing the liquefied gas from the third heat exchanger 7 to the main engine 22A. In this case, the vaporized gas that has passed through the third heat exchanger 7 is guided to the main engine 22A via the gas discharge line 82 (82A) or the like.

[0094] In the embodiments shown in FIGS. 6 and 7, the gas discharge line 82 includes a start-up gas supply line 82B for guiding the vaporized gas obtained by vaporizing the liquefied gas from the third heat exchanger 7 to a gas combustion device 23 configured separately from the main engine 22A. The gas combustion device 23 is configured to burn the supplied gas. One side (downstream end) of the start-up gas supply line 82B is connected to the gas inlet of the gas combustion device 23.

[0095] In the embodiment shown in FIG. 6, the other side (upstream end) of the start-up gas supply line 82B is connected to the downstream end of the second liquefied gas side flow path 72 (the gas outlet of the third heat exchanger 7). In the embodiment shown in FIG. 7, the other side (upstream end) of the start-up gas supply line 82B is connected to the downstream end of the third liquefied gas side flow path 73 (the gas outlet of the third heat exchanger 7).

[0096] When the cold and heat recovery system 1 is started up, since the flow rate of the heat medium for cold and heat that circulates through the cold and heat recovery cycle 3 is small, liquefied gas is supplied to the main engine 22A without being sufficiently vaporized, which may cause a failure or malfunction of the main engine 22A. According to the configuration shown in FIGS. 6 and 7, when the cold and heat recovery system 1 is started up, vaporized gas or liquefied gas can be guided to the gas combustion device 23 via the start-up gas supply line 82B and burned in the gas combustion device 23. Thereby, it is possible to suppress the supply of liquefied gas to the main engine 22A without being sufficiently vaporized, so that a failure or malfunction of the main engine 22A can be suppressed. Further, according to the configuration shown in FIGS. 6 and 7, when the cold and heat recovery system 1 is started up, since it is not necessary to completely vaporize the liquefied gas in the third heat exchanger 7, the cold and heat recovery cycle 3 and the external water pump 45 can be driven from an early stage. Thereby, the cold and heat recovery system 1 can be shifted to steady operation at an early stage.

[0097] (Bypass line of the second heat exchanger) In some embodiments, as shown in FIG. 8, the above-described cold and heat recovery system 1 may be configured such that heat exchange between the heat medium for cold and heat and external water in the second heat exchanger 14 is not performed when the external water pump 45 is in a driving state. In the illustrated embodiment, the cold and heat recovery system 1 further includes a heat exchanger-side bypass line 46 that bypasses the second heat exchanger 14 and connects the external water supply line 42 and the external water discharge line 44. One side (upstream end) of the heat exchanger-side bypass line 46 is connected to the branch portion P8 of the external water supply line 42. The other side (downstream end) of the heat exchanger-side bypass line 46 is connected to the confluence portion P9 of the external water discharge line 44.

[0098] The above-described heat and cold recovery system 1 may further include a first external water side on-off valve 47 provided downstream of the branch portion P8 of the external water supply line 42, and a second external water side on-off valve 48 provided in the heat exchanger side bypass line 46. By opening the first external water side on-off valve 47 and fully closing the second external water side on-off valve 48, the external water passes through the second heat exchanger 14. By fully closing the first external water side on-off valve 47 and opening the second external water side on-off valve 48, the external water passes through the heat exchanger side bypass line 46 (bypassing the second heat exchanger 14).

[0099] After starting the drive of the external water pump 45, a period is required until the external water pump 45 shifts to a steady state. During this period, the flow rate of the external water supplied to the second heat exchanger 14 is not stable, so there is a risk that the heating of the heat medium for heat and cold to the second heat exchanger 14 is not stable. By causing the external water to pass through the heat exchanger side bypass line 46 during the period until the external water pump 45 shifts to a steady state, stable operation becomes possible when the heat and cold recovery system 1 shifts to steady operation. In the startup method 100 of the above-described heat and cold recovery system 1, the external water may be caused to pass through the heat exchanger side bypass line 46 for a predetermined period from the start of the external water pump drive step S107. The valve opening step S104 may be started during the above-described predetermined period.

[0100] Note that the heat and cold recovery system 1 may include a bypass line that bypasses the second heat exchanger 14 and connects a portion downstream of the connection portion P1 of the first lower connection line 33C and a portion upstream of the branch portion P2 of the second upper connection line 34A instead of the heat exchanger side bypass line 46.

[0101] (Control device) FIG. 9 is an explanatory diagram for explaining a control device of a cold and heat recovery system according to an embodiment of the present disclosure. In some embodiments, as shown in FIG. 9, the cold and heat recovery system 1 is configured to be able to acquire the temperature of the heat medium for cold and heat inside the gas-liquid separator 5 (in the illustrated example, a temperature sensor) 87, and a valve opening control device 88 that controls the opening of the second flow rate adjustment valve 83 so that the temperature of the heat medium for cold and heat acquired by the temperature acquisition device 87 falls within a predetermined range. By increasing the opening of the second flow rate adjustment valve 83 by the valve opening control device 88, the flow rate of the liquefied gas supplied to the third heat exchanger 7 can be increased, and thus the inside of the gas-liquid separator 5 can be cooled accordingly.

[0102] In the illustrated embodiment, the valve opening control device 88 is mounted on a control device 9 configured to perform operation control of a pump included in the cold and heat recovery system 1 and opening control of a valve included in the cold and heat recovery system 1. The pump (such as the cold and heat pump 31) included in the cold and heat recovery system 1 is configured to be driven and stopped in response to an operation instruction from the control device 9. The valve (such as the first flow rate adjustment valve 35) included in the cold and heat recovery system 1 is configured to be able to adjust its opening in response to an opening instruction from the control device 9. The cold and heat recovery system 1 includes the control device 9. Note that some steps in the startup method 100 may be performed by the control device 9. Also, some steps in the startup method 100 may be performed using devices and equipment other than the control device 9, or may be performed manually.

[0103] The control device 9 is an electronic control unit for controlling the cold and heat recovery system 1. The control device 9 is configured as a microcomputer including a CPU (processor) not shown, a memory such as a ROM and a RAM, a storage device such as an external storage device, an I / O interface, a communication interface, and the like. The control device 9 may realize the control in the valve opening control device 88 by the CPU operating (for example, performing data calculation, etc.) according to the instructions of a program loaded into the main storage device of the memory.

[0104] According to the above configuration, by controlling the opening degree of the second flow rate adjustment valve 83 with the valve opening degree control device 88 and maintaining the temperature of the heat medium for cold heat within a predetermined range by the temperature acquisition device 87, it is possible to suppress the early reduction in the capacity due to gas biting of the cold heat pump 31, and to stabilize the temperature of the heat medium for cold heat flowing through the circulation cycle including the gas-liquid separator 5, the cold heat pump 31, and the liquid return line 6 and the cold heat recovery cycle 3 at an early stage. As a result, steps such as the valve opening step S104 and the change step S105 can be executed earlier, so that the cold heat recovery system 1 can be shifted to steady operation earlier.

[0105] The present disclosure is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0106] The content described in some of the above-described embodiments is understood as follows, for example.

[0107] 1) The cold heat recovery system (1) according to at least one embodiment of the present disclosure is a cold heat recovery system (1) installed on a ship (2A) or a floating body (2B) having a liquefied gas storage device (21) configured to store liquefied gas, a first heat exchanger (11) configured to transfer cold heat energy from the liquefied gas withdrawn from the liquefied gas storage device (21) to a heat medium for cold heat, a cold heat recovery cycle (3) configured to circulate the heat medium for cold heat, the cold heat recovery cycle (3) including at least a cold heat pump (31) for sending the heat medium for cold heat provided downstream of the first heat exchanger (11), a second heat exchanger (14) configured to transfer heat energy from a heat medium to the heat medium for cold heat flowing downstream of the cold heat pump (31) in the cold heat recovery cycle (3) and upstream of the first heat exchanger (11), A gas-liquid separator (5) provided between the first heat exchanger (11) and the cold heat pump (31) in the cold and heat recovery cycle (3), configured to separate the cold heat medium into a gaseous cold heat medium and a liquid-phase cold heat medium; A liquid return line (6) for returning the liquid-phase cold heat medium to the gas-liquid separator (5) from a downstream side of the cold heat pump (31) and an upstream side of the second heat exchanger (14) in the cold and heat recovery cycle (3); A third heat exchanger (7) configured to transfer the cold energy of the liquefied gas extracted from the liquefied gas storage device (21) to either the liquid-phase cold heat medium returned to the gas-liquid separator (5) via the liquid return line (6) or the cold heat medium present inside the gas-liquid separator (5).

[0108] According to the configuration of 1) above, the liquid-phase cold heat medium circulating through the gas-liquid separator (5), the cold heat pump (31), and the liquid return line (6) is cooled by the liquefied gas in the third heat exchanger (7), so that the proportion of the liquid-phase cold heat medium can be increased at an early stage on the downstream side of the first heat exchanger (11) in the cold and heat recovery cycle (3) such as the gas-liquid separator (5) and the cold heat pump (31). By increasing the proportion of the liquid-phase cold heat medium in the cold heat pump (31), the reduction in capacity due to gas biting of the cold heat pump (31) can be suppressed, so that the capacity of the cold heat pump (31) can be exerted from an early stage. As a result, the cold and heat recovery system (1) can be shifted to steady operation at an early stage.

[0109] Also, according to the configuration of 1) above, until the flow rate of the cold heat medium supplied to the first heat exchanger (11) reaches a large flow rate that does not cause blockage of the first heat exchanger (11), by not performing heat exchange in the first heat exchanger (11), blockage of the first heat exchanger (11) at the start of the cold and heat recovery system (1) can be suppressed.

[0110] 2) In some embodiments, it is the cold and heat recovery system (1) described in 1) above, The third heat exchanger (7) is configured to transfer the cooling energy of the liquefied gas extracted from the liquefied gas storage device (21) to the liquid-phase heat transfer medium for cooling flowing through the liquid return line (6).

[0111] According to the configuration of 2) above, the third heat exchanger (7) can cool the heat transfer medium for cooling flowing through the liquid return line (6) with the liquefied gas, so that the temperature inside the gas-liquid separator (5) can be quickly lowered below a predetermined temperature. As a result, the cold heat recovery system (1) can be quickly shifted to steady operation.

[0112] 3) In some embodiments, it is the cold heat recovery system (1) described in 1) above, The third heat exchanger (7) is configured to transfer the cooling energy of the liquefied gas extracted from the liquefied gas storage device (21) to the heat transfer medium for cooling existing inside the gas-liquid separator (5).

[0113] According to the configuration of 3) above, the third heat exchanger (7) can cool the heat transfer medium for cooling existing inside the gas-liquid separator (5) with the liquefied gas, so that the temperature inside the gas-liquid separator (5) can be quickly lowered below a predetermined temperature. As a result, the cold heat recovery system (1) can be quickly shifted to steady operation.

[0114] 4) In some embodiments, it is the cold heat recovery system (1) described in 2) above, The liquid return line (6) includes a first liquid return line (6A) provided with the third heat exchanger (7), and a second liquid return line (6B) bypassing the third heat exchanger (7).

[0115] According to the configuration of 4) above, when it is not necessary to cool the heat medium for cold by the third heat exchanger (7), the circulating heat medium for cold is passed through the second liquid return line (6B) (bypassing the third heat exchanger (7)), so that the pressure loss in the third heat exchanger (7) can be suppressed. Therefore, the performance of the cold recovery cycle (3) can be effectively exerted during the steady operation of the cold recovery system (1).

[0116] 5) In some embodiments, it is the cold recovery system (1) described in any one of 1) to 4) above, a fuel supply line (13A) for supplying the liquefied gas vaporized in the first heat exchanger (11) to the main engine (22A) of the ship (2A) or the floating body (2B), and a start-up gas supply line (82B) for guiding the vaporized gas obtained by vaporizing the liquefied gas from the third heat exchanger (7) to a gas combustion device (23) configured separately from the main engine (22A).

[0117] At the start-up of the cold recovery system (1), since the flow rate of the heat medium for cold circulating in the cold recovery cycle (3) is small, the liquefied gas is supplied to the main engine (22A) without being sufficiently vaporized, which may cause a failure or malfunction of the main engine (22A). According to the configuration of 5) above, at the start-up of the cold recovery system (1), the vaporized gas and the liquefied gas can be guided to the gas combustion device (23) through the start-up gas supply line (82B) and burned in the gas combustion device (23). Thereby, it is possible to suppress the supply of the liquefied gas to the main engine (22A) without being sufficiently vaporized, so that the failure or malfunction of the main engine (22A) can be suppressed. Further, according to the configuration of 5) above, at the start-up of the cold recovery system (1), it is not necessary to completely vaporize the liquefied gas in the third heat exchanger (7), so that the cold recovery cycle 3 and the external water pump 45 can be driven from an early stage. Thereby, the cold recovery system (1) can be shifted to steady operation at an early stage.

[0118] 6) In some embodiments, there is provided a cold and heat recovery system (1) according to any one of 1) to 5) above, a first flow rate adjustment valve (35) is further provided between a connection part (P1) with an upstream end of the liquid return line (6) in the cold and heat recovery cycle (3) and the second heat exchanger (14), and is configured to be able to adjust a flow rate of the liquid-phase heat medium for cold and heat that is guided to the second heat exchanger (14).

[0119] According to the configuration of 6) above, by closing the first flow rate adjustment valve (35), a closed circuit including the gas-liquid separator (5), the pump for cold and heat (31), and the liquid return line (6) can be formed. By cooling the heat medium for cold and heat circulating in this closed circuit with liquefied gas in the third heat exchanger (7), compared with the case of cooling the heat medium for cold and heat circulating in a wider cold and heat recovery cycle (3) than the closed circuit, the temperature inside the gas-liquid separator (5) can be quickly lowered to a predetermined temperature or lower. Thereby, the cold and heat recovery system (1) can be quickly shifted to steady operation.

[0120] 7) In some embodiments, there is provided a cold and heat recovery system (1) according to any one of 1) to 6) above, a liquefied gas introduction line (81) connecting the liquefied gas storage device (21) and the third heat exchanger (7), a second flow rate adjustment valve (83) provided in the liquefied gas introduction line (81) and configured to be able to adjust a flow rate of the liquefied gas that is guided to the third heat exchanger, a temperature acquisition device (87) configured to be able to acquire a temperature of the heat medium for cold and heat inside the gas-liquid separator (5), and a valve opening degree control device (88) that controls an opening degree of the second flow rate adjustment valve (83) so that the temperature of the heat medium for cold and heat acquired by the temperature acquisition device (87) falls within a predetermined range.

[0121] According to the configuration of the above 7), the opening degree of the second flow rate adjustment valve (83) is controlled by the valve opening degree control device (88), and the temperature of the heat medium for cold heat obtained by the temperature acquisition device (87) is maintained within a predetermined range, so that the reduction in capacity due to gas biting of the cold heat pump (31) can be suppressed at an early stage, and the temperature of the heat medium for cold heat flowing through the circulation cycle including the gas-liquid separator (5), the cold heat pump (31) and the liquid return line (6) and the cold heat recovery cycle (3) can be stabilized at an early stage. Thereby, the cold heat recovery system (1) can be shifted to steady operation at an early stage.

[0122] 8) The startup method (100) of the cold heat recovery system according to at least one embodiment of the present disclosure is A startup method (100) of a cold heat recovery system (1) installed on a ship (2A) or a floating body (2B) having a liquefied gas storage device (21) configured to store liquefied gas, The cold heat recovery system (1) is A first heat exchanger (11) configured to transfer cold heat energy from the liquefied gas withdrawn from the liquefied gas storage device (21) to a heat medium for cold heat, A cold heat recovery cycle (3) configured to circulate the heat medium for cold heat, the cold heat recovery cycle (3) including at least a cold heat pump (31) for sending the heat medium for cold heat provided downstream of the first heat exchanger (11), A second heat exchanger (14) configured to transfer heat energy from the heat medium to the heat medium for cold heat flowing downstream of the cold heat pump (31) in the cold heat recovery cycle (3) and upstream of the first heat exchanger (11), The startup method (100) of the cold heat recovery system is A gas-liquid separation step (S101) of separating the heat medium for cold heat into a gaseous heat medium for cold heat and a liquid heat medium for cold heat by a gas-liquid separator (5) provided between the first heat exchanger (11) and the cold heat pump (31) in the cold heat recovery cycle (3), Drive the cold and heat pump (31), and return the liquid-phase cold and heat medium separated in the gas-liquid separation step (S101) to the gas-liquid separator (5) via a liquid return line (6) that connects the downstream side of the cold and heat pump (31) in the cold and heat recovery cycle (3) and the upstream side of the second heat exchanger (14) with the gas-liquid separator (5), in a circulation step (S102). In the circulation step (S102), a cooling step (S103) of transferring and cooling the cold energy of the liquefied gas extracted from the liquefied gas storage device (21) to either the liquid-phase cold and heat medium returned to the gas-liquid separator (5) via the liquid return line (6) or the cold and heat medium present inside the gas-liquid separator (5).

[0123] According to the method of 8) above, by cooling the liquid-phase cold and heat medium circulating through the gas-liquid separator (5), the cold and heat pump (31), and the liquid return line (6) with the liquefied gas (cooling step S103), the proportion of the liquid-phase cold and heat medium in the cold and heat recovery cycle (3) downstream of the first heat exchanger (11) such as the gas-liquid separator (5) and the cold and heat pump (31) can be increased at an early stage. By increasing the proportion of the liquid-phase cold and heat medium in the cold and heat pump (31), the reduction in capacity due to gas biting in the cold and heat pump (31) can be suppressed, so that the capacity of the cold and heat pump (31) can be exerted from an early stage. Thereby, the cold and heat recovery system (1) can be shifted to steady operation at an early stage.

[0124] Also, according to the method of 8) above, until the flow rate of the cold and heat medium supplied to the first heat exchanger (11) reaches a large flow rate that does not cause blockage of the first heat exchanger (11), heat exchange in the first heat exchanger (11) is not performed, so blockage of the first heat exchanger (11) at the start of the cold and heat recovery system (1) can be suppressed.

Explanation of Reference Numerals

[0125] 1 Cold and heat recovery system 2A Ship 2B Floating body 3 Heat recovery cycle 5 Gas-liquid separator 6 Liquid return line 7 Third heat exchanger 9 Control device 11 First heat exchanger 12 Liquefied gas supply line 13 Vaporized gas supply line 13A Fuel supply line 14 Second heat exchanger 15 Liquefied gas pump 21 Liquefied gas storage device 22 Gas supply destination 22A Main engine 31 Heat pump 32 Heat turbine 33 First connection line 33A First upper connection line 33B First middle connection line 33C First lower connection line 34 Second connection line 34A Second upper connection line 34B Second lower connection line 35 First flow control valve 36 Turbine bypass line 37 Turbine side flow control valve 38 Turbine bypass side flow control valve 41 External water supply source 42 External water supply line 43 External water discharge destination 44 External water discharge line 45 External water pump 46 Heat exchanger side bypass line 47 First external water side on-off valve 48 Second external water side on-off valve 51 Internal space 51A Upper storage space 51B Lower storage space 52 Body part 53 Inlet 54 Liquid phase discharge port 55 Liquid return port 61 First on-off valve 62 Second on-off valve 81 Liquefied gas introduction line 82 Gas discharge line 83 Second flow control valve 84 Third flow control valve 85 Fourth flow control valve 86 Fifth flow control valve 87 Temperature acquisition device 88 Valve opening control device 100 Starting method S101 Gas-liquid separation step S102 Circulation step S103 Cooling step S104 Valve opening step S105 Change step S106 Turbine drive step for cold and heat S107 Pump drive step for external water

Claims

1. A cold heat recovery system installed on a ship or floating body having a liquefied gas storage device configured to store liquefied gas, a first heat exchanger configured to transfer cold heat energy from the liquefied gas withdrawn from the liquefied gas storage device to a heat medium for cold heat; a cold heat recovery cycle configured to circulate the heat medium for cold heat, the cold heat recovery cycle including at least a cold heat pump for sending the heat medium for cold heat provided downstream of the first heat exchanger; a second heat exchanger configured to transfer heat energy from a heat medium to the heat medium for cold heat flowing downstream of the cold heat pump in the cold heat recovery cycle and upstream of the first heat exchanger; a gas-liquid separator provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle and configured to separate the heat medium for cold heat into a gaseous heat medium for cold heat and a liquid heat medium for cold heat; a liquid return line for returning the liquid heat medium for cold heat to the gas-liquid separator from downstream of the cold heat pump and upstream of the second heat exchanger in the cold heat recovery cycle; a third heat exchanger configured to transfer the cold heat energy of the liquefied gas withdrawn from the liquefied gas storage device to either the liquid heat medium for cold heat returned to the gas-liquid separator via the liquid return line or the heat medium for cold heat present inside the gas-liquid separator. A cold heat recovery system comprising:

2. The third heat exchanger is configured to transfer the cold heat energy of the liquefied gas withdrawn from the liquefied gas storage device to the liquid heat medium for cold heat flowing through the liquid return line. The cold heat recovery system according to Claim 1.

3. The third heat exchanger is configured to transfer the cold heat energy of the liquefied gas withdrawn from the liquefied gas storage device to the heat medium for cold heat present inside the gas-liquid separator. The cold heat recovery system according to Claim 1.

4. The liquid return line includes a first liquid return line provided with the third heat exchanger, and a second liquid return line bypassing the third heat exchanger. The cold heat recovery system according to Claim 2.

5. A fuel supply line for supplying the liquefied gas vaporized by the first heat exchanger to the main engine of the ship or the floating body A start-up gas supply line for guiding at least one of the liquefied gas or the vaporized gas obtained by vaporizing the liquefied gas from the third heat exchanger to a gas combustion device configured separately from the main engine, and The cold heat recovery system according to any one of claims 1 to 4.

6. A first flow rate adjustment valve provided between a connection portion with the upstream end of the liquid return line in the cold heat recovery cycle and the second heat exchanger and configured to be able to adjust the flow rate of the liquid-phase cold heat transfer medium guided to the second heat exchanger, and The cold heat recovery system according to any one of claims 1 to 5.

7. A liquefied gas introduction line connecting the liquefied gas storage device and the third heat exchanger, A second flow rate adjustment valve provided in the liquefied gas introduction line and configured to be able to adjust the flow rate of the liquefied gas guided to the third heat exchanger, A temperature acquisition device configured to be able to acquire the temperature of the cold heat transfer medium in the gas-liquid separator, A valve opening degree control device for controlling the opening degree of the second flow rate adjustment valve so that the temperature of the cold heat transfer medium acquired by the temperature acquisition device falls within a predetermined range, and The cold heat recovery system according to any one of claims 1 to 6.

8. A start-up method of a cold heat recovery system installed on a ship or a floating body having a liquefied gas storage device configured to store liquefied gas, wherein The cold heat recovery system is A first heat exchanger configured to transfer cold heat energy from the liquefied gas withdrawn from the liquefied gas storage device to a cold heat transfer medium, A cold heat recovery cycle configured to circulate the cold heat transfer medium, the cold heat recovery cycle including at least a cold heat pump for sending the cold heat transfer medium provided downstream of the first heat exchanger, A second heat exchanger configured to transfer heat energy from a heat medium to the cold heat transfer medium flowing downstream of the cold heat pump and upstream of the first heat exchanger in the cold heat recovery cycle, and The start-up method of the cold heat recovery system is A gas-liquid separation step of separating the cold heat transfer medium into a gaseous cold heat transfer medium and a liquid-phase cold heat transfer medium by a gas-liquid separator provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle, Drive the cold and heat pump, and return the liquid-phase cold and heat heat medium separated in the gas-liquid separation step to the gas-liquid separator through a liquid return line connecting the downstream side of the cold and heat pump in the cold and heat recovery cycle and the upstream side of the second heat exchanger with the gas-liquid separator, in a circulation step; In the circulation step, a cooling step of transferring and cooling the cold energy of the liquefied gas extracted from the liquefied gas storage device to either the liquid-phase cold and heat heat medium returned to the gas-liquid separator through the liquid return line or the cold and heat heat medium existing inside the gas-liquid separator. A method for starting a cold and heat recovery system.

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