JP7685902B2 - Cold heat recovery system and method for starting the cold heat recovery system - Google Patents

Description

This disclosure relates to a cold energy recovery system for recovering cold energy from liquefied gas, and a method for starting up the cold energy recovery system.

Liquefied gas (e.g., liquefied natural gas) is liquefied for the purpose of transportation or storage, and when it is supplied to a destination such as a city gas or thermal power plant, it is heated and vaporized using a heat medium such as seawater. When vaporizing liquefied gas, the cold energy of the liquefied gas is sometimes recovered rather than being dumped into seawater (e.g., Patent Document 1).

Patent Document 1 discloses a cold energy power generation cycle that recovers cold energy from liquefied natural gas as electricity. Known examples of this cold energy power generation cycle include the secondary medium Rankine cycle (see Patent Document 1). The secondary medium Rankine cycle system involves heating and evaporating a secondary medium circulating in a closed loop using seawater as a heat source in an evaporator, introducing this steam into a cold energy power generation turbine to generate power, and then cooling and condensing it using liquefied natural gas.

It is difficult to establish land-based LNG terminals to serve each of the LNG supply destinations, due to the costs involved in securing land, etc. For this reason, ships equipped with LNG storage facilities for storing LNG and regasification facilities for regasifying LNG are moored at sea, and the LNG regasified by the ship is sometimes sent via pipeline to onshore supply destinations or offshore power gauges (floating power plants).

Because ships have less expandability than land-based facilities, in order to install cold energy generation equipment, it is important to miniaturize the cold energy generation system, especially the heat exchanger. Examples of small heat exchangers include printed circuit heat exchangers (PCHEs) and plate heat exchangers.

Japanese Utility Model Application Publication No. 61-59803

If one heat exchange target is at a lower temperature than the freezing point of the other heat exchange target, one of the heat exchange targets may freeze during heat exchange in the heat exchanger, and the frozen heat exchange target may adhere to the surface of the heat exchanger and clog the heat exchanger. Small heat exchangers have a higher risk of clogging than large heat exchangers (e.g., shell-and-tube heat exchangers), and therefore have reliability issues.

In a cold energy power generation cycle, when the secondary medium circulating through the cold energy power generation cycle is cooled by liquefied natural gas in the heat exchanger, there is a risk that the heat exchanger will freeze. In particular, when the cold energy power generation cycle is started up, when the flow rate of the secondary medium circulating through the cold energy power generation cycle is small, the temperature of the secondary medium drops compared to normal operation, making it highly likely that the heat exchanger will freeze. In order to prevent the heat exchanger from freezing, it is possible to provide a heating line that preheats the liquefied natural gas supplied to the heat exchanger, but such a heating line is not preferable because it increases the size and cost of the system equipped with the cold energy power generation cycle.

In addition, in order to prevent the heat exchanger from freezing, it is possible to increase the flow rate of the secondary medium circulating through the cold power generation cycle when the cycle is started. However, when the cycle is stopped, the secondary medium may vaporize in the cold power generation cycle due to heat input from the surrounding air to the cycle. For this reason, when the cycle is started, the proportion of gaseous secondary medium in the circulation pump for circulating the secondary medium is larger than when the cycle is in steady operation. If the circulation rate of the circulation pump for circulating the secondary medium is increased, there is a problem that the possibility of startup failure due to gas getting caught in the circulation pump increases when the cycle is started.

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 that can suppress blockage of a heat exchanger when the cold heat recovery system is started, and a method for starting the cold heat recovery system.

A cold heat recovery system according to an embodiment of the present disclosure includes:
A cold energy 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 energy from the liquefied gas extracted from the liquefied gas storage device to a cold heat medium;
A cold heat recovery cycle configured to circulate the cold heat medium, the cold heat recovery cycle including at least a cold heat pump for feeding the cold heat medium provided downstream of the first heat exchanger;
A first gas-liquid separator is provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle and configured to separate the cold heat medium into a gas phase cold heat medium and a liquid phase cold heat medium;
a pump bypass line for extracting the gas-phase cold heat medium from the first gas-liquid separator and guiding the gas-phase cold heat medium to a downstream side of the cold heat pump and an upstream side of the first heat exchanger in the cold heat recovery cycle;
and a blowing means for blowing the gas-phase cold heat medium to the first heat exchanger through the pump bypass line.

A method for starting a cold heat recovery system according to an embodiment of the present disclosure includes:
A method for starting up a cold energy recovery system installed on a ship or floating body having a liquefied gas storage device configured to store liquefied gas, comprising:
The cold heat recovery system includes:
A first heat exchanger configured to transfer cold energy from the liquefied gas extracted from the liquefied gas storage device to a cold heat medium;
A cold heat recovery cycle configured to circulate the cold heat medium, the cold heat recovery cycle including a cold heat pump for feeding the cold heat medium, the cold heat recovery cycle being provided downstream of the first heat exchanger,
The method for starting the cold heat recovery system includes:
A gas-liquid separation step of separating the cold heat medium into a gas-phase cold heat medium and a liquid-phase cold heat medium by a gas-liquid separator provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle;
a blowing step of sending the gas-phase cold heat transfer medium separated in the gas-liquid separation step to the first heat exchanger by bypassing the cold heat pump;
A cooling step of sending the liquefied gas from the liquefied gas storage device to the first heat exchanger and cooling the gas-phase cold heat medium sent to the first heat exchanger in the blowing step by the liquefied gas;
and a cold heat pump driving step of driving the cold heat pump after the cooling step.

According to at least one embodiment of the present disclosure, a cold heat recovery system capable of suppressing blockage of a heat exchanger when the cold heat recovery system is started up, and a method for starting up the cold heat recovery system are provided.

1 is a schematic diagram illustrating a configuration of a ship or a floating body equipped with a cold heat recovery system according to a first embodiment of the present disclosure. FIG. 2 is a flow diagram of a startup method for a cold heat recovery system according to an embodiment of the present disclosure. FIG. 2 is an explanatory diagram for explaining an example of control in the cold heat recovery system according to an embodiment of the present disclosure. FIG. 11 is a schematic diagram illustrating the configuration of a ship or a floating body equipped with a cold energy recovery system according to a second embodiment of the present disclosure. FIG. 11 is a schematic diagram illustrating a configuration of a ship or a floating body equipped with a cold heat recovery system according to a third embodiment of the present disclosure. FIG. 13 is a schematic diagram illustrating the configuration of a ship or a floating body equipped with a cold energy recovery system according to a fourth embodiment of the present disclosure. FIG. 13 is a schematic diagram illustrating the configuration of a ship or a floating body equipped with a cold energy recovery system according to a fifth embodiment of the present disclosure. FIG. 2 is an explanatory diagram for explaining a control device of the cold heat recovery system according to an embodiment of the present disclosure.

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 components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise", "include", or "have" a certain element are not exclusive expressions excluding the presence of other elements.
In addition, the same components are denoted by the same reference numerals and the description thereof may be omitted.

(Ships, floating bodies)
FIG. 1 is a schematic diagram showing the configuration of a ship 2A or a floating body 2B equipped with a cold energy recovery system 1 according to a first embodiment of the present disclosure. As shown in FIG. 1, the cold energy recovery system 1 according to some embodiments is installed on a ship 2A or a floating body 2B. The ship 2A or the floating body 2B is a structure that can float on water. The ship 2A or the floating body 2B has a liquefied gas storage device (e.g., a liquefied gas tank) 21 configured to store liquefied gas, and the cold energy recovery system 1. In the illustrated embodiment, the ship 2A or the floating body 2B has a propeller (not shown) such as a propeller and a propulsion device (not shown) configured to drive the propulsion device, and is a structure configured to be self-propelled by driving the propulsion device. Note that the present disclosure is also applicable to a case where the ship 2A or the floating body 2B is a non-self-propelled structure that does not have a propulsion device for self-propulsion.

(Cold heat recovery system)
As shown in FIG. 1, the cold heat recovery system 1 comprises a first heat exchanger 11, a liquefied gas supply line 12 for supplying liquefied gas from a liquefied gas storage device 21 to the first heat exchanger 11, a vaporized gas supply line 13 for supplying vaporized gas produced by vaporizing the liquefied gas in the first heat exchanger 11, a cold heat recovery cycle 3 configured to circulate a cold heat medium that has been heat exchanged with the liquefied gas in the first heat exchanger 11, a second heat exchanger 14, and a first gas-liquid separator 5.

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

The following description will be given using liquefied natural gas (LNG) as a specific example of the liquefied gas supplied from the liquefied gas storage device 21, which is the supply source of the liquefied gas, and propane as a specific example of the cold heat medium circulating through the cold heat recovery cycle 3, but this disclosure is also applicable to cases where a liquefied gas other than liquefied natural gas (liquefied petroleum gas, liquefied hydrogen, etc.) is used as the liquefied gas supplied from the liquefied gas storage device 21. This disclosure is also applicable to cases where a heat medium other than propane (for example, an organic medium) is used as the cold heat medium flowing through the cold heat recovery cycle 3. The cold heat medium has a lower boiling point and freezing point than water.

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

In the first heat exchanger 11, heat exchange takes place between the liquefied gas flowing through the liquefied gas side flow passage 111 and the cold heat medium flowing through the first cold heat side flow passage 112, and the cold heat energy of the liquefied gas flowing through the liquefied gas side flow passage 111 is transferred to the cold heat medium flowing through the first cold heat side flow passage 112. As a result, the liquefied gas flowing through the liquefied gas side flow passage 111 is heated and vaporized, and the cold heat medium flowing through the first cold heat side flow passage 112 is cooled and condensed.

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

In the second heat exchanger 14, heat exchange takes place between the cold heat medium flowing through the second cold side flow passage 141 and the external water flowing through the heat medium side flow passage 142, and the thermal energy of the external water flowing through the heat medium side flow passage 142 is transferred to the cold heat medium flowing through the second cold side flow passage 141. As a result, the cold heat medium flowing through the second cold side flow passage 141 is heated and vaporized.

(Liquefied gas supply system)
One side (upstream end) of the liquefied gas supply line 12 is connected to the liquefied gas storage device 21, and the other side (downstream end) of the liquefied gas supply line 12 is connected to the upstream end (gas inlet of the first heat exchanger 11) of the liquefied gas side flow path 111. One side (upstream end) of the vaporized gas supply line 13 is connected to the downstream end (liquefied gas outlet of the first heat exchanger 11) of the liquefied gas side flow path 111, and the other side (downstream end) of the vaporized gas supply line 13 is connected to a vaporized gas supply destination 22. The vaporized gas supply destination 22 may be a facility (e.g., a power generation facility or a gas storage facility on land) provided outside the ship 2A or the float 2B, or may be a facility mounted on the ship 2A or the float 2B.

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 moving blade (not shown) provided in the liquefied gas supply line 12, and is configured to send liquefied gas to the downstream side of the liquefied gas supply line 12 (the side where the first heat exchanger 11 is located) by rotating the moving blade by power supplied to the liquefied gas pump 15. By driving the liquefied gas pump 15, the liquefied gas stored in the liquefied gas storage device 21 is extracted to the liquefied gas supply line 12 and sent to the liquefied gas side flow path 111 of the first heat exchanger 11 through the liquefied gas supply line 12. The vaporized gas generated by vaporizing the liquefied gas in the liquefied gas side flow path 111 of the first heat exchanger 11 is sent to the gas supply destination 22 through the vaporized gas supply line 13 by the liquefied gas pump 15.

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

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 (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 (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 target as a heat medium in the heat exchanger (water with a higher temperature than the heat exchange target), and may be water at room temperature. The external water is preferably water that is easily available on the ship 2A or the float 2B (for example, overboard water such as seawater or engine cooling water that cools the engine of the ship 2A).

The external water supply source 41 may be a water intake provided on the ship 2A or the float 2B to take in external water (e.g., seawater) from outside the ship 2A or the float 2B, or may be equipment (e.g., a water tank) provided inside the ship 2A or the float 2B. The external water discharge destination 43 may be a drainage outlet provided on the ship 2A or the float 2B to discharge external water to the outside of the ship 2A or the float 2B, or may be equipment (e.g., a drainage tank) provided inside the ship 2A or the float 2B.

The external water pump 45 has a moving blade (not shown) provided on the external water supply line 42, and 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 rotating the moving blade using electricity or the like supplied to the external water pump 45. By driving the external water pump 45, external water is extracted from the external water supply source 41 to the external water supply line 42 and sent through the external water supply line 42 to the heat exchanger (second heat exchanger 14) that uses the external water as a heat medium.

(Cold heat medium circulation system)
As shown in FIG. 1, the cold energy recovery cycle 3 further includes a first connection line 33 and a second connection line (main line) 34. The first connection line 33 connects the downstream end of the first cold energy side flow passage 112 (the outlet of the cold energy medium of the first heat exchanger 11) and the upstream end of the second cold energy side flow passage 141 (the inlet of the cold energy medium of the second heat exchanger 14). The first connection line 33 is provided with the cold energy pump 31 described above. The second connection line 34 connects the downstream end of the second cold energy side flow passage 141 (the outlet of the cold energy medium of the second heat exchanger 14) and the upstream end of the first cold energy side flow passage 112 (the inlet of the cold energy medium of the first heat exchanger 11). The second connection line 34 is provided with the cold energy turbine 32 described above.

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

The first gas-liquid separator 5 includes a main body 52 configured to define an internal space 51 into which the cold heat medium sent from the first cold side flow path 112 (first heat exchanger 11) through the first connection line 33 is introduced, an inlet 53 for introducing the cold heat medium into the internal space 51, a liquid phase outlet 54 for discharging the liquid phase cold heat medium from the internal space 51 to the outside of the first gas-liquid separator 5, and a gas phase outlet 55 for discharging the gas phase cold heat medium from the internal space 51 to the outside of the first gas-liquid separator 5.

The internal space 51 includes a lower storage space 51B in which a liquid-phase cold heat transfer medium is stored, and an upper storage space 51A in which a gas-phase cold heat transfer medium is stored, the upper storage space 51A being provided above the lower storage space 51B and in communication with the lower storage space 51B. The liquid-phase outlet 54 is in communication with the lower storage space 51B. The gas-phase outlet 55 is in communication with the upper storage space 51A.

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

The cold heat medium cooled in the first heat exchanger 11 is led to the first gas-liquid separator 5 through the first upper connection line 33A. The cold heat medium that flows into the internal space 51 from the inlet 53 separates into a liquid phase and a gas phase in the internal space 51.

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

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

(Heat pump related equipment)
1, the cold heat recovery cycle 3 may further include a liquid return line 35 for returning the liquid-phase cold heat medium to the first gas-liquid separator 5 from the downstream side of the cold heat pump 31 and the upstream side of the second heat exchanger 14 in the cold heat recovery cycle 3, and a first flow rate control valve 36 provided between a connection part P1 with the upstream end of the liquid return line 35 in the cold heat recovery cycle 3 and the second heat exchanger 14. The first flow rate control valve 36 is configured to be able to adjust the flow rate of the liquid-phase cold heat medium guided to the second heat exchanger 14.

In the illustrated embodiment, the first gas-liquid separator 5 further includes a liquid return port 56 for introducing the liquid-phase cold heat medium from the liquid return line 35 into the internal space 51. The liquid return port 56 is connected to the internal space 51. One side (upstream end) of the liquid return line 35 is connected to the connection part P1 of the first lower connection line 33C, and the other side (downstream end) of the liquid return line 35 is connected to the liquid return port 56. The first flow rate control valve 36 is provided downstream of the connection part P1 of the first lower connection line 33C. The first flow rate control valve 36 can adjust the flow rate of the cold heat medium supplied downstream of the valve body (to the second heat exchanger 14 side) by moving a valve body (not shown) that opens and closes the flow path of the cold heat medium. The first flow rate control valve 36 may be an on-off valve whose opening degree can be adjusted to fully closed or 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 between these.

(Cold Heat Turbine)
The cold heat turbine 32 is introduced with a cold heat medium, which is pressurized by the cold heat pump 31 and heated by the second heat exchanger 14, as a working fluid. The cold heat turbine 32 includes a rotating shaft 321, a turbine blade 322 attached to the rotating shaft 321, and a casing 323 that rotatably houses the turbine blade 322. The casing 323 is formed with an inlet 324 for introducing the cold heat medium into the inside of the casing 323, and a discharge port 325 for discharging the cold heat medium that has passed through the turbine blade 322 to the outside of the casing 323. The cold heat turbine 32 is configured to rotate the turbine blade 322 by the energy of the cold heat medium introduced into the inside of the casing 323 through the inlet 324. The cold heat medium that has passed through the turbine blade 322 is discharged to the outside of the casing 323 through the discharge port 325.

The cold heat recovery cycle 3 is configured to recover the rotational force generated by the turbine blades 322 as power. In the illustrated embodiment, the cold heat recovery cycle 3 further includes a cold heat generator 326 configured to generate power by driving the cold heat turbine 32. The cold heat generator 326 is mechanically connected to the rotating shaft 321 and configured to convert the rotational force of the turbine blades 322 into electric power. Note that in some other embodiments, the cold heat recovery cycle 3 may recover the rotational force generated by the turbine blades 322 as power directly through a power transmission device (e.g., a coupling, a belt, a pulley, etc.) rather than converting it into electric power.

The second connection line 34 described above includes a second upper connection line 34A that connects the downstream end of the second cold-side flow passage 141 to the inlet 324 of the cold-side turbine 32, and a second lower connection line 34B that connects the outlet 325 of the cold-side turbine 32 to the upstream end of the first cold-side flow passage 112.

(Cold heat turbine related equipment)
As shown in FIG. 1 , the cold energy recovery cycle 3 further includes a turbine bypass line 37 that connects the upstream and downstream sides of the cold energy turbine 32 of the second connection line 34, bypassing the cold energy turbine 32, a second flow control valve 38, and a third flow control valve 39.

One side (upstream end) of the turbine bypass line 37 is connected to the branch point P2 of the second upper stage connection line 34A, and the other side (downstream end) of the turbine bypass line 37 is connected to the junction P3 of the second lower stage connection line 34B. The second flow control valve 38 is provided downstream (toward the cold heat turbine 32) of the branch point P2 of the second upper stage connection line 34A. The third flow control valve 39 is provided in the turbine bypass line 37. Each of the second flow control valve 38 and the third flow control valve 39 can adjust the flow rate of the cold heat medium supplied downstream of the valve body by moving a valve body (not shown) that opens and closes the flow path of the cold heat medium. Each of the second flow rate control valve 38 and the third flow rate control valve 39 may be an on-off valve whose opening degree can be adjusted to fully closed or fully open, or may be an opening degree adjustment valve whose opening degree can be adjusted to fully closed, fully open, or at least one intermediate opening degree between these.

For example, by opening the second flow control valve 38 (fully open or intermediate opening) and fully closing the third flow control valve 39, the cold heat medium can be sent to the first heat exchanger 11 via the cold heat turbine 32. Also, by fully closing the second flow control valve 38 and opening the third flow control valve 39 (fully open or intermediate opening), the cold heat medium can be sent to the first heat exchanger 11 via the turbine bypass line 37.

(Pump bypass line, air blowing means)
1, the cold heat recovery system 1 according to some embodiments further includes a pump bypass line 6 for extracting the gas-phase cold heat medium from the first gas-liquid separator 5 and guiding the gas-phase cold heat medium downstream of the cold heat pump 31 and upstream of the first heat exchanger 11 in the cold heat recovery cycle 3, and a blower 7 for sending the gas-phase cold heat medium to the first heat exchanger 11 via the pump bypass line 6. The blower 7 sends the gas-phase cold heat medium extracted from the first gas-liquid separator 5 to the pump bypass line 6 to the first heat exchanger 11.

One side (upstream end) 61 of the pump bypass line 6 is connected to the gas phase discharge port 55 of the first gas-liquid separator 5, and the other side (downstream end) 62 of the pump bypass line 6 is connected to either the second connection line 34 or the turbine bypass line 37 downstream of the first flow control valve 36 of the first lower stage connection line 33C.

In the embodiment shown in FIG. 1, the other side (downstream end) 62 of the pump bypass line 6 is connected to a connection position P4 downstream of the first flow control valve 36 of the first lower stage connection line 33C.

In the illustrated embodiment, the blower 7 includes a blower 7A provided downstream of the third flow control valve 39 of the turbine bypass line 37. The blower 7A is configured to send a gas-phase cold heat medium to the downstream side of the turbine bypass line 37. In the illustrated embodiment, the blower 7A includes a rotating shaft 71, a rotor blade 72 attached to the rotating shaft 71, a casing 73 that rotatably houses the rotor blade 72, and an electric motor 74 configured to supply a driving force to the rotor blade 72 to rotate the rotor blade 72.

The rotor blades 72 are disposed downstream of the third flow control valve 39 of the turbine bypass line 37. The casing 73 is formed with an inlet 731 for introducing the gas-phase cold heat medium into the inside of the casing 73, and a discharge port 732 for discharging the gas-phase cold heat medium that has passed through the rotor blades 72 to the outside of the casing 73. The electric motor 74 is mechanically connected to the rotating shaft 71. The rotor blades 72 are rotated by the driving force generated by the electric motor 74 being transmitted via the rotating shaft 71.

(How to start the cold energy recovery system)
FIG. 2 is a flow diagram of a start-up method of a cold energy 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 energy recovery system according to an embodiment of the present disclosure. As shown in FIG. 2 and FIG. 3, the period from the start-up of the cold energy recovery system 1 to the steady operation of the cold energy recovery system 1 is divided into a first period (gas phase circulation period) T1, a second period (phase transition period) T2, and a third period (liquid phase circulation period) T3. The second period T2 is a period after the first period T1 and a period before the third period T3.

In the first period T1, the gas phase cold heat medium extracted from the first gas-liquid separator 5 in the cold heat recovery cycle 3 is circulated. In the third period T3, the liquid phase cold heat medium extracted from the first gas-liquid separator 5 in the cold heat recovery cycle 3 is circulated. In the second period T2, the cold heat medium circulating in the cold heat recovery cycle 3 is changed from the gas phase (gas phase extracted from the first gas-liquid separator 5) to the liquid phase (liquid phase extracted from the first gas-liquid separator 5).

As shown in FIG. 2, the startup method 100 of the cold energy recovery system 1 according to some embodiments includes a gas-liquid separation step S101, a blowing step S102, a cooling step S103, and a cold energy pump driving step S104.

In the gas-liquid separation step S101, the cold heat medium is separated into a gas phase and a liquid phase by the first gas-liquid separator 5 described above. The gas-liquid separation step S101 is performed continuously during the period from the start-up of the cold heat recovery system 1 until the system reaches steady operation and during steady operation.

When the cold heat recovery system 1 is stopped, heat input from the surrounding air to the cold heat recovery cycle 3 and the first gas-liquid separator 5 may cause the cold heat medium to vaporize in the cold heat recovery cycle 3. For this reason, when the cold heat recovery system 1 is started, the proportion of the gas phase cold heat medium in the second heat exchanger 14 downstream of the first heat exchanger 11 in the cold heat recovery cycle 3, such as the first gas-liquid separator 5 and the cold heat pump 31, is larger than when the cold heat recovery system 1 is in steady operation. If the proportion of the gas phase cold heat medium in the cold heat pump 31 is large, there is a risk of a decrease in the performance of the cold heat pump 31 due to gas entrapment.

In the blowing step S102, the gas-phase cold heat medium separated in the gas-liquid separation step S101 is sent to the first heat exchanger 11, bypassing the cold heat pump 31. In the illustrated embodiment, the above-mentioned blower 7A (blower means 7) is driven to extract the gas-phase cold heat medium from the first gas-liquid separator 5 to the pump bypass line 6. The gas-phase cold heat medium extracted by the blower 7A is sent to the first cold side flow path 112 (first heat exchanger 11) by the blower 7A. The cold heat medium sent to the first cold side flow path 112 is sent to the first gas-liquid separator 5 after passing through the first upper connection line 33A.

Specifically, the gas-phase cold heat medium extracted from the first gas-liquid separator 5 by the blower 7A passes through the pump bypass line 6, downstream of the connection position P4 of the first lower stage connection line 33C, the second cold side flow path 141 (second heat exchanger 14), upstream of the branch point P2 of the second upper stage connection line 34A, and downstream of the junction point P3 of the turbine bypass line 37 and the second lower stage connection line 34B, before being sent to the first cold side flow path 112 (first heat exchanger 11).

The air blowing step S102 is started in the first period T1 and continues until the second period T2. As shown in FIG. 3, in the first period T1 and the second period T2, the second flow control valve 38 is fully closed and the third flow control valve 39 is opened (fully open or intermediate opening), so that the cold heat medium is sent to the first heat exchanger 11 via the turbine bypass line 37.

In the cooling step S103, liquefied gas is sent from the liquefied gas storage device 21 to the first heat exchanger 11, and the gas-phase cold heat medium sent to the first heat exchanger 11 in the air blowing step S102 is cooled by the liquefied gas. In the illustrated embodiment, the liquefied gas pump 15 is driven to send liquefied gas from the liquefied gas storage device 21 to the liquefied gas side flow path 111 (first heat exchanger 11) via the liquefied gas supply line 12. The cooling step S103 is started after the air blowing step S102 in the first period T1.

By cooling and condensing the gas-phase cold heat medium circulating through the cold heat recovery cycle 3 via the pump bypass line 6 with liquefied gas in the first heat exchanger 11, the proportion of the liquid-phase cold heat medium can be increased early on downstream of the first heat exchanger 11 and upstream of the second heat exchanger 14 in the cold heat recovery cycle 3, such as the first 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 performance reduction due to gas entrapment in the cold heat pump 31 can be suppressed, allowing the cold heat pump 31 to demonstrate its performance early on.

In the cold heat pump driving step S104, the cold heat pump 31 is driven after the cooling step S103. As shown in FIG. 3, the cold heat pump 31 is driven after the liquefied gas pump 15 is driven. At the start of the cold heat pump driving step S104 (when the cold heat pump 31 starts to be driven), it is preferable that the first flow control valve 36 is fully closed. At the start of the cold heat pump driving step S104, the amount of cold heat medium that can be sent to the first heat exchanger 11 by the cold heat pump 31 is small, which may lead to blockage of the first heat exchanger 11.

When the first flow rate control valve 36 is fully closed, the cold heat pump 31 is driven to circulate the liquid-phase cold heat medium through the first gas-liquid separator 5, the cold heat pump 31, and the liquid return line 35. Specifically, when the first flow rate control valve 36 is fully closed, the cold heat pump 31 is driven to extract the liquid-phase cold heat medium from the first gas-liquid separator 5 through the liquid-phase outlet 54. The liquid-phase cold heat medium extracted from the first gas-liquid separator 5 is sent from the cold heat pump 31 to the first middle stage connection line 33B, the cold heat pump 31, the upstream side of the connection part P1 of the first lower stage connection line 33C, and through the liquid return line 35, and then to the first gas-liquid separator 5.

In the illustrated embodiment, as shown in FIG. 2, the start-up method 100 of the cold energy recovery system 1 further includes a valve opening step S105 in which the first flow control valve 36 is opened (changed from fully closed to fully open or intermediate opening) after the start of the cold energy pump driving step S104, and the cold energy pump 31 sends the liquid phase cold energy medium to the second heat exchanger 14, a blower means stopping step S106 in which the blower 7A (blower means 7) is stopped after the valve opening step S105, a cold energy turbine driving step S107 in which the cold energy medium is guided to the cold energy turbine 32 after the valve opening step S105 and drives the cold energy turbine 32, and an external water pump driving step S108 in which the external water pump 45 is driven before the valve opening step S105.

The valve opening step S105 is performed, for example, when the liquid-phase cold heat medium is circulated by the cold heat pump 31 and the flow rate of the cold heat medium that can be sent to the first heat exchanger 11 by the cold heat pump 31 (the amount of liquid-phase cold heat medium stored in the lower storage space 51B) reaches or exceeds a certain amount. The liquid-phase cold heat medium that has passed through the first flow control valve 36 is heated in the second heat exchanger 14 and vaporized before being sent to the first heat exchanger 11.

Specifically, the liquid-phase cold heat transfer medium that has passed through the first flow control valve 36 passes through the downstream side of the first flow control valve 36 of the first lower stage connection line 33C, the second cold side flow path 141 (second heat exchanger 14), the upstream side of the branch point P2 of the second upper stage connection line 34A, and the downstream side of the junction point P3 of the turbine bypass line 37 and the second lower stage connection line 34B, before being sent to the first cold side flow path 112 (first heat exchanger 11).

Before the valve opening step S105, the external water pump 45 is driven (S108), and external water is supplied to the heat medium side flow path 142 of the second heat exchanger 14. The liquid-phase cold heat medium that has passed through the first flow rate control valve 36 is heated and vaporized by the external water (heat medium) in the second heat exchanger 14. As shown in Figures 2 and 3, the external water pump 45 may be driven (S108) before the air blowing step S102. In this case, the cold heat medium flowing through the second heat exchanger 14 via the pump bypass line 6 is heated by the external water, thereby suppressing blockage in the first heat exchanger 11.

During the above-mentioned second period T2, the cold heat pump driving step S104, the valve opening step S105, and the blower means stopping step S106 are executed to change the cold heat medium circulating in the cold heat recovery cycle 3 from a gas phase (gas phase extracted from the first gas-liquid separator 5) to a liquid phase (liquid phase extracted from the first gas-liquid separator 5). During the above-mentioned third period T3, the cold heat turbine driving step S107 is executed. That is, the cold heat turbine driving step S107 is executed after the blower means stopping step S106.

In the cold-heat turbine drive step S107, as shown in FIG. 3, the second flow control valve 38 is opened (changed from fully closed to fully open or intermediate opening) and the third flow control valve 39 is closed (changed from fully open or intermediate opening to fully closed). As a result, the cold-heat heat medium pressurized by the cold-heat pump 31 and heated by 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, driving the cold-heat turbine 32.

According to the above method, the gas-phase cold heat medium separated in the gas-liquid separation step S101 is sent to the first heat exchanger 11 (air blowing step S102) bypassing the cold heat pump 31, so that the gas-phase cold heat medium can be circulated in the cold heat recovery cycle 3. Since the gas-phase cold heat medium is less likely to cause blockage in the first heat exchanger 11 than the liquid-phase cold heat medium, blockage of the first heat exchanger 11 can be suppressed when the cold heat recovery system 1 is started up.

In addition, according to the above method, the gas-phase cold heat medium circulating in the cold heat recovery cycle 3 is cooled by liquefied gas in the first heat exchanger 11 (cooling step S103) and condensed, so that the proportion of the liquid-phase cold heat medium can be increased early on downstream of the first heat exchanger 11 in the cold heat recovery cycle 3, such as the first 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 performance decrease due to gas entrapment in the cold heat pump 31 can be suppressed, so that the cold heat pump 31 can be driven early (cold heat pump drive step S104) and the performance of the cold heat pump 31 can be exerted early. As a result, the cold heat recovery system 1 can be transitioned to steady operation early.

As shown in FIG. 1, the cold heat recovery system 1 according to some embodiments includes the first heat exchanger 11 described above, the cold heat recovery cycle 3 described above, the first gas-liquid separator 5 described above, the pump bypass line 6 described above, and the blower means 7.

According to the above configuration, the gas-phase cold heat medium separated in the first gas-liquid separator 5 is sent to the first heat exchanger 11 via the pump bypass line 6 by the air blowing means 7, so that the gas-phase cold heat medium can be circulated in the cold heat recovery cycle 3. Since the gas-phase cold heat medium is less likely to cause blockage in the first heat exchanger 11 than the liquid-phase cold heat medium, blockage of the first heat exchanger 11 can be suppressed when the cold heat recovery system 1 is started up.

In addition, according to the above configuration, the gas-phase cold heat medium circulating through the cold heat recovery cycle 3 when the cold heat recovery system 1 is started is cooled and condensed by the liquefied gas in the first heat exchanger 11, so that the proportion of the liquid-phase cold heat medium can be increased early on downstream of the first heat exchanger 11 in the cold heat recovery cycle 3, such as the first 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 performance reduction due to gas entrapment of the cold heat pump 31 can be suppressed, so that the performance of the cold heat pump 31 can be exerted early on. This allows the cold heat recovery system 1 to transition to steady operation early on.

(Specific example 1 of pump bypass line connection position)
In some embodiments, as shown in Fig. 1, the above-mentioned pump bypass line 6 is connected upstream of the second heat exchanger 14 in the cold heat recovery cycle 3. In this case, even if the cold heat pump 31 is driven and a liquid-phase cold heat medium is fed downstream of the cold heat pump 31, the liquid-phase cold heat medium is vaporized in the second heat exchanger 14, so that the gas-phase cold heat medium flows downstream of the second heat exchanger 14 in the same manner as before the cold heat pump 31 is driven. Therefore, during the period from the start of the cold heat recovery system 1 to the steady operation, a transient change in the cold heat medium flowing downstream of the second heat exchanger 14 and upstream of the first heat exchanger 11 can be suppressed.

In addition, with the above configuration, even after the cold heat pump 31 is driven, the gas-phase cold heat medium flows downstream of the second heat exchanger 14 and upstream of the first heat exchanger 11, so there is no need to suddenly stop the blower means 7, and the cold heat recovery cycle 3 can be gradually transitioned to steady operation. Therefore, with the above configuration, it is possible to improve the reliability of the cold heat recovery system 1 during the period from startup to steady operation.

(Specific example 2 of pump bypass line connection position)
4 is a schematic diagram showing a configuration of a ship or a floating body equipped with a cold energy recovery system according to a second embodiment of the present disclosure. In some embodiments, as shown in FIG. 4, the above-mentioned pump bypass line 6 is connected downstream of the second heat exchanger 14 in the cold energy recovery cycle 3 and upstream of the cold energy turbine 32.

In the embodiment shown in FIG. 4, the other side (downstream end) 62 of the pump bypass line 6 is connected to a connection position P5 upstream of the branch point P2 of the second upper stage connection line 34A. In the embodiment shown in FIG. 4, in the above-mentioned blowing step S102, the gas-phase cold heat medium extracted from the first gas-liquid separator 5 by the blower 7A passes between the pump bypass line 6, the connection position P5 and the branch point P2 of the second upper stage connection line 34A, the turbine bypass line 37, and the downstream side of the junction point P3 of the second lower stage connection line 34B, and then is sent to the first cold side flow path 112 (first heat exchanger 11).

According to the above configuration, the pump bypass line 6 is connected downstream of the second heat exchanger 14 in the cold heat recovery cycle 3 and upstream of the cold heat turbine 32. In this case, even if the cold heat pump 31 is driven and the liquid phase cold heat medium is sent downstream of the cold heat pump 31, the liquid phase cold heat medium is vaporized in the second heat exchanger 14, so that the gas phase cold heat medium flows downstream of the second heat exchanger 14 as before the cold heat pump 31 is driven. Therefore, the inflow of the liquid phase cold heat medium into the pump bypass line 6 can be suppressed compared to when the pump bypass line 6 is connected upstream of the second heat exchanger 14 in the cold heat recovery cycle 3. This stabilizes the phase of the cold heat medium flowing through the pump bypass line 6 during the period from startup to steady-state operation of the cold heat recovery system 1, and suppresses the volumetric change of the cold heat medium flowing through the pump bypass line 6, making it possible to gradually transition the cold heat recovery system 1 to steady-state operation. In addition, with the above configuration, the control devices (e.g., valves) and measuring devices provided in the pump bypass line 6 can be of single-phase specification (gas-phase specification), which reduces the cost of the devices in the cold heat recovery system 1.

In some embodiments, as shown in FIG. 4, the pump bypass line 6 is connected downstream of the second heat exchanger 14 in the cold heat recovery cycle 3 and upstream of the cold heat turbine 32. The cold heat recovery system 1 further includes a check valve 63 provided in the pump bypass line 6 and configured to allow only a flow from the first gas-liquid separator 5 toward the cold heat recovery cycle 3.

The check valve 63 allows the cold heat medium to flow from one side 61 to the other side 62 of the pump bypass line 6, but is configured to close if the cold heat medium attempts to flow from the other side 62 to one side 61 of the pump bypass line 6.

According to the above configuration, the check valve 63 can prevent the gas-phase cold heat medium heated in the second heat exchanger 14 from flowing back through the pump bypass line 6 into the first gas-liquid separator 5. In this case, the gas-phase cold heat medium flowing back through the pump bypass line 6 can prevent the cooling of the first gas-liquid separator 5 from being delayed, so the cold heat recovery system 1 can be quickly transitioned to steady-state operation.

In some embodiments, as shown in Figures 1 and 4, the cold heat recovery cycle 3 includes the second connection line (main line) 34 and the turbine bypass line 37, and the blower 7A is provided in the turbine bypass line 37.

According to the above configuration, the blower means 7 provided in the turbine bypass line 37 can send the gas-phase cold heat medium separated in the first gas-liquid separator 5 to the first heat exchanger 11 via the turbine bypass line 37 (bypassing the cold heat turbine 32). This can suppress pressure loss in the cold heat turbine 32, so that the performance of the blower means 7 can be effectively demonstrated when the cold heat recovery system 1 is started. In addition, according to the above configuration, when the cold heat turbine 32 is driven, the cold heat medium can be sent to the first heat exchanger 11 without passing through the turbine bypass line 37. This can suppress pressure loss in the blower 7A, so that the performance of the cold heat turbine 32 can be effectively demonstrated during steady operation of the cold heat recovery system 1.

(Second Gas-Liquid Separator)
FIG. 5 is a schematic diagram illustrating a configuration of a ship or a floating body equipped with a cold energy recovery system according to a third embodiment of the present disclosure.
In some embodiments, as shown in Fig. 5, the pump bypass line 6 is connected downstream of the second heat exchanger 14 in the cold heat recovery cycle 3 and upstream of the cold heat turbine 32. The cold heat recovery cycle 3 includes the second connection line (main line) 34 and the turbine bypass line 37, and the blower 7A is provided in the turbine bypass line 37. The cold heat recovery system 1 further includes a second gas-liquid separator 8 configured to separate the cold heat medium into a gas phase and a liquid phase. The second gas-liquid separator 8 is provided either between the connection position P5 and the branch point P2 in the second connection line 34, or upstream of the blower 7 in the turbine bypass line 37.

In the embodiment shown in FIG. 5, the second gas-liquid separator 8 is provided upstream of the branch point P2 in the second upper connection line 34A. The second gas-liquid separator 8 includes a main body 82 configured to define an internal space 81 into which the cold heat medium sent from the pump bypass line 6 or the second heat exchanger 14 is introduced, a first inlet 83 for introducing the cold heat medium from the second heat exchanger 14 into the internal space 81, a second inlet 84 for introducing the cold heat medium from the pump bypass line 6 into the internal space 81, and a gas phase outlet 85 for discharging the gas phase cold heat medium from the internal space 81 to the outside of the second gas-liquid separator 8.

The internal space 81 includes a lower storage space 81B in which a liquid-phase cold heat transfer medium is stored, and an upper storage space 81A in which a gas-phase cold heat transfer medium is stored, the upper storage space 81A being provided above the lower storage space 81B and in communication with the lower storage space 81B. Each of the first inlet 83, the second inlet 84, and the gas-phase outlet 85 is in communication with the upper storage space 81A.

The cold heat medium heated in the second heat exchanger 14 is led to the second gas-liquid separator 8 through the upstream portion of the second upper connection line 34A from the second gas-liquid separator 8. The other side (downstream end) 62 of the pump bypass line 6 is connected to the second inlet 84. The gas phase cold heat medium stored in the first gas-liquid separator 5 is led to the second gas-liquid separator 8 through the pump bypass line 6. The gas phase cold heat medium that flows into the internal space 81 from the first inlet 83 or the second inlet 84 is separated into a liquid phase in the internal space 81. The gas phase cold heat medium from which the liquid phase has been separated in the second gas-liquid separator 8 flows downstream of the second gas-liquid separator 8 of the second upper connection line 34A.

When the cold heat recovery system 1 is started (specifically, during the second period T2), for example, when the cold heat medium circulating through the cold heat recovery cycle 3 is changed from gas phase to liquid phase, if the liquid component of the cold heat medium suddenly flows into the turbine bypass line 37, it may cause a malfunction of the blower 7A. According to the above configuration, the second gas-liquid separator 8 separates the cold heat medium into gas phase and liquid phase, which prevents the liquid component of the cold heat medium from flowing into the turbine bypass line 37 and causing a malfunction of the blower 7A, thereby improving the reliability of the cold heat recovery system 1.

The second gas-liquid separator 8 may be configured to discharge the liquid-phase cold heat medium stored in the lower storage space 81B to the outside of the second gas-liquid separator 8. As shown in FIG. 5, the second gas-liquid separator 8 may include a liquid delivery line 86 for delivering the liquid-phase cold heat medium stored in the lower storage space 81B to the internal space 51 of the first gas-liquid separator 5. The liquid delivery line 86 includes a flow path connecting the lower storage space 81B and the internal space 51.

(Specific example 3 of pump bypass line connection position)
Fig. 6 is a schematic diagram showing the configuration of a ship or a floating body equipped with a cold energy recovery system according to a fourth embodiment of the present disclosure. In some embodiments, as shown in Fig. 6, the above-mentioned pump bypass line 6 is connected downstream of the cold energy turbine 32 in the cold energy recovery cycle 3. A blower 7B (blower means 7) is provided in the pump bypass line 6.

In the embodiment shown in FIG. 6, the other side (downstream end) 62 of the pump bypass line 6 is connected to a connection position P6 of the second lower stage connection line 34B. As shown in FIG. 6, the turbine bypass line 37 may merge with the pump bypass line 6 at a junction P7, and may share a line 37A from the junction P7 to the connection position P6 with the pump bypass line 6.

In the illustrated embodiment, the blower 7 includes a blower 7B provided upstream of the junction P7 of the pump bypass line 6. The blower 7B is configured to send a gas-phase cold heat medium to the downstream side of the pump bypass line 6. In the illustrated embodiment, the blower 7B includes, like the blower 7A described above, a rotating shaft 71, a rotor blade 72 attached to the rotating shaft 71, a casing 73 that rotatably houses the rotor blade 72, and an electric motor 74 configured to supply a driving force to the rotor blade 72 to rotate the rotor blade 72.

The rotor blades 72 are disposed upstream of the junction P7 of the pump bypass line 6. The casing 73 is formed with an inlet 731 for introducing the gas-phase cold heat medium into the inside of the casing 73, and a discharge port 732 for discharging the gas-phase cold heat medium that has passed through the rotor blades 72 to the outside of the casing 73. The electric motor 74 is mechanically connected to the rotating shaft 71. The rotor blades 72 are rotated by the driving force generated by the electric motor 74 being transmitted via the rotating shaft 71.

The pump bypass line 6 includes a first pump bypass line 6A that connects the gas phase discharge port 55 of the first gas-liquid separator 5 to the inlet 731 of the blower 7B, and a second pump bypass line 6B that connects the discharge port 732 of the blower 7B to the connection position P6 of the second lower connection line 34B.

In the embodiment shown in FIG. 6, in the above-mentioned blowing step S102, the blower 7B is driven to extract the gas-phase cold heat medium from the first gas-liquid separator 5 to the pump bypass line 6. The gas-phase cold heat medium extracted by the blower 7B passes downstream of the connection position P6 of the pump bypass line 6 and the second lower connection line 34B, and is then sent to the first cold side flow path 112 (first heat exchanger 11) by the blower 7B. The cold heat medium sent to the first cold side flow path 112 passes through the first upper connection line 33A and is then sent to the first gas-liquid separator 5.

When the cold heat medium circulating in the cold heat recovery cycle 3 is changed from gaseous to liquid phase, the pressure of the gaseous cold heat medium introduced into the blower means 7 increases suddenly, and the operating point of the blower means 7 changes suddenly, which may damage the blower means 7. According to the above configuration, by connecting the pump bypass line 6 downstream of the cold heat turbine 32, it is possible to prevent the cold heat medium that has passed through the second heat exchanger 14 from flowing directly into the pump bypass line 6. This makes it possible to prevent sudden changes in the operating point of the blower 7B (blower means 7) provided in the pump bypass line 6, thereby reducing the risk of damage to the blower 7B. In addition, the pressure resistance required of the blower 7B can be reduced, thereby reducing the cost of the blower 7B.

In some embodiments, as shown in FIG. 6, the above-mentioned pump bypass line 6 is connected downstream of the cold energy turbine 32 in the cold energy recovery cycle 3. The blower 7B is provided in the pump bypass line 6. The above-mentioned cold energy recovery system 1 further includes a return line 64 that connects the downstream side and the upstream side of the blowing means 7 of the pump bypass line 6, bypassing the blower 7B. One side of the return line 64 is connected to the branching point P8 of the second pump bypass line 6B, and the other side of the return line 64 is connected to the junction point P9 of the first pump bypass line 6A.

According to the above configuration, when the blower 7B is stopped, the cold heat medium may flow back through the pump bypass line 6. When the cold heat medium flows back through the pump bypass line 6, the return line 64 has a smaller pressure loss than the line in which the blower 7B is installed, so the cold heat medium can be routed through the return line 64. By preventing the backflow of the cold heat medium from flowing back into the blower 7B, the steady operation of the blower 7B can be maintained for a long period of time, and damage caused by surging of the blower 7B can be suppressed. This improves the reliability of the cold heat recovery system 1.

(Pressure reducing valve)
In some embodiments, as shown in FIG. 6, the pressure reducing valve 65 may be provided downstream of the branch point P8 of the second pump bypass line 6B. In the embodiment shown in FIG. 6, the pressure reducing valve 65 is provided upstream of the connection position with the junction point P7 in the second pump bypass line 6B. According to the above configuration, the pressure reducing valve 65 can prevent the high-pressure cold heat medium that has passed through the second heat exchanger 14 from flowing upstream of the pressure reducing valve 65 of the second pump bypass line 6B. This effectively prevents a sudden change in the operating point of the blower 7B (blowing means 7), effectively reducing the risk of damage to the blower 7B. In addition, the pressure resistance required of the blower 7B can be reduced, thereby reducing the cost of the blower 7B.

(Specific example 3 of pump bypass line connection position)
FIG. 7 is a schematic diagram illustrating a configuration of a ship or a floating body equipped with a cold energy recovery system according to a fifth embodiment of the present disclosure.
7, the pump bypass line 6 includes a first line 6C connected from the first gas-liquid separator 5 to a first connection position P10 downstream of the cold energy turbine 32 in the cold energy recovery cycle 3, a second line 6D extending from the first connection position P10 to a branch position P11 upstream of the cold energy turbine 32 in the cold energy recovery cycle 3, and a third line 6E extending from the branch position P11 to a second connection position P12 downstream of the first connection position P10 in the cold energy recovery cycle 3, bypassing the cold energy turbine 32. The cold energy turbine 32 provided in the second line 6D is configured to function as the blowing means 7 by rotating in the reverse direction.

In the illustrated embodiment, the cold energy generator 326 is configured to convert the rotational force of the turbine blades 322 into electric power when the turbine blades 322 rotate in one direction in the rotational direction (forward rotation). The cold energy generator 326 also functions as an inverter motor, and is configured to generate a rotational force that rotates the turbine blades 322 in the other direction in the rotational direction (opposite to the one side) (reverse rotation) when electric power is supplied.

In the above-described startup method 100 of the cold heat recovery system 1, the cold heat turbine 32 functions as the blowing means 7 from the start of the blowing step S102 to the blowing means stopping step S106. By rotating the cold heat turbine 32 in the reverse direction, a gas-phase cold heat medium can be sent to the downstream side of the pump bypass line 6.

In the illustrated embodiment, one side (upstream end) 61 of the first line 6C is connected to the gas phase outlet 55 of the first gas-liquid separator 5, and one side (downstream end) 62 of the third line 6E is connected to the junction P3 (second connection position P12) of the second lower stage connection line 34B. The other side (downstream end) of the first line 6C is connected to the first connection position P10 upstream of the junction P3 of the second lower stage connection line 34B. The second line 6D is a shared line with the part downstream of the branch P2 (P11) of the second upper stage connection line 34A and the part upstream of the junction P3 (P10) of the second lower stage connection line 34B. The third line 6E is a shared line with the turbine bypass line 37.

As shown in FIG. 7, the above-mentioned cold energy recovery system 1 may further include a first on-off valve 91 provided between the junction P3 (P10) of the second lower connection line 34B and the second connection position P12, and a second on-off valve 92 provided upstream of the branch point P2 (P11) of the second upper connection line 34A.

In the above-mentioned air blowing step S102, the first on-off valve 91 and the second on-off valve 92 are fully closed, and air is blown by the reversely rotating cold-heat turbine 32. The gas-phase cold-heat medium extracted from the first gas-liquid separator 5 passes downstream of the junction P3 of the first line 6C, the second line 6D, the third line 6E, and the second lower connection line 34B, and is then sent to the first cold-heat side flow path 112 (first heat exchanger 11).

According to the above configuration, by making the cold energy turbine 32 function as the blowing means 7, a dedicated blowing means for sending the gas-phase cold energy medium through the pump bypass line 6 is not required, which reduces the cost of the equipment in the cold energy recovery system 1.

In some embodiments, as shown in Figures 1 and 4 to 7, the gas supply destination 22 described above includes a main engine 22A of a ship 2A or a float 2B. The main engine 22A is configured to generate a driving force (propulsion force) for driving a propeller or other thruster (not shown) by using the energy of the vaporized gas supplied. The vaporized gas supply line 13 described above 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 float 2B.

The above-mentioned cold heat recovery system 1 further includes a branch line 24 that branches off from the fuel supply line 13A and supplies the liquefied gas (vaporized gas) vaporized in the first heat exchanger 11 to a destination other than the main engine 22A, and a gas combustion device 23 that is configured separately from the main engine 22A and connected to the branch line 24. One side (upstream end) of the branch line 24 is connected to a branch portion 25 of the fuel supply line 13A, and the other side (downstream end) is connected to a gas inlet of the gas combustion device 23. The gas combustion device 23 is configured to combust the supplied gas.

The above-mentioned cold heat recovery system 1 may further include a third on-off valve 26 provided downstream of the branch 25 of the fuel supply line 13A and a fourth on-off valve 27 provided in the branch line 24. When the cold heat recovery system 1 is started, the third on-off valve 26 is fully closed and the fourth on-off valve 27 is open. Therefore, the gas sent from the first heat exchanger 11 is sent to the gas combustion device 23. After the blower means stop step S106 is executed, when the flow rate of the cold heat medium circulating in the cold heat recovery cycle 3 is secured, the fourth on-off valve 27 is fully closed and the third on-off valve 26 is opened. As a result, the gas sent from the first heat exchanger 11 is sent to the main engine 22A.

When the cold heat recovery system 1 is started, the flow rate of the cold heat medium circulating through the cold heat recovery cycle 3 is small, so the liquefied gas is supplied to the main engine 22A without being fully vaporized, which may cause the main engine 22A to break down or malfunction. With the above configuration, when the cold heat recovery system 1 is started, the vaporized gas and liquefied gas can be guided to the gas combustion device 23 via the branch line 24 and combusted in the gas combustion device 23. This prevents the liquefied gas from being supplied to the main engine 22A without being fully vaporized, thereby preventing the main engine 22A from breaking down or malfunctioning.

(Control device)
8 is an explanatory diagram for explaining a control device of a cold heat recovery system according to an embodiment of the present disclosure. In some embodiments, the cold heat recovery system 1 further includes a liquid level acquisition device (in the illustrated example, a liquid level sensor) 93 configured to acquire the liquid level WL of the cold heat medium inside the first gas-liquid separator 5, and a cold heat pump control device 94 that drives the cold heat pump 31 when the liquid level WL acquired by the liquid level acquisition device 93 exceeds a threshold value TH. The above-mentioned startup method 100 of the cold heat recovery system 1 further includes a liquid level acquisition step S109 for acquiring the liquid level WL of the liquid phase cold heat medium stored inside the first gas-liquid separator 5, and when the liquid level WL acquired in the liquid level acquisition step S109 exceeds the threshold value TH, the cold heat pump drive step S104 is performed.

In the illustrated embodiment, the cold heat pump control device 94 is mounted on a control device 9 configured to control the operation of the pumps provided in the cold heat recovery system 1 and the opening degree of the valves provided in the cold heat recovery system 1. The pumps (such as the cold heat pump 31) provided in the cold heat recovery system 1 are configured to be driven or stopped in response to an operation instruction from the control device 9. The valves (such as the first flow control valve 36) provided in the cold heat recovery system 1 are configured to be able to adjust their opening degree in response to an opening degree instruction from the control device 9. The cold heat recovery system 1 is equipped with a control device 9. Some steps in the start-up method 100 may be performed by the control device 9. Some steps in the start-up method 100 may be performed using devices or equipment other than the control device 9, or may be performed manually.

The control device 9 is an electronic control unit for controlling the cold energy recovery system 1. The control device 9 is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, storage devices such as an external storage device, an I/O interface, a communication interface, etc. The control device 9 may realize control of the cold energy pump control device 94 by, for example, having the CPU operate (e.g., perform data calculations) according to instructions of a program loaded into the main storage device of the memory.

According to the above configuration and method, when the liquid level WL of the liquid-phase cold heat medium stored inside the first gas-liquid separator 5 exceeds the threshold value TH, the proportion of the liquid-phase cold heat medium in the cold heat pump 31 is sufficiently large. By using the liquid level WL as a judgment criterion, it is possible to effectively suppress the performance degradation of the cold heat pump 31 due to gas entrapment.

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

The contents described in the above-mentioned embodiments can be understood, for example, as follows:

1) A cold heat recovery system (1) according to at least one embodiment of the present disclosure,
A cold energy 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 energy from the liquefied gas extracted from the liquefied gas storage device (21) to a cold heat medium;
A cold heat recovery cycle (3) configured to circulate the cold heat medium, the cold heat recovery cycle (3) including at least a cold heat pump (31) for feeding the cold heat medium, the cold heat recovery cycle (3) being provided downstream of the first heat exchanger (21);
a first gas-liquid separator (5) provided between the first heat exchanger (11) and the cold heat pump (31) in the cold heat recovery cycle (3) and configured to separate the cold heat medium into a gas phase cold heat medium and a liquid phase cold heat medium;
a pump bypass line (6) for extracting the gas-phase cold heat medium from the first gas-liquid separator (5) and guiding the gas-phase cold heat medium to a downstream side of the cold heat pump (31) and an upstream side of the first heat exchanger (11) in the cold heat recovery cycle (3);
and a blowing means (7) for sending the gas-phase cold heat transfer medium to the first heat exchanger (11) through the pump bypass line (6).

According to the configuration of 1) above, the gas-phase cold heat medium separated in the first gas-liquid separator (5) is sent to the first heat exchanger (11) via the pump bypass line (6) by the air blowing means (7), so that the gas-phase cold heat medium can be circulated in the cold heat recovery cycle (3). Since the gas-phase cold heat medium is less likely to cause blockage in the first heat exchanger (11) than the liquid-phase cold heat medium, blockage of the first heat exchanger (11) can be suppressed when the cold heat recovery system (1) is started up.

In addition, according to the configuration of 1) above, when the cold heat recovery system (1) is started, the gas-phase cold heat medium circulating in the cold heat recovery cycle (3) is cooled and condensed by liquefied gas in the first heat exchanger (11), so that the proportion of the liquid-phase cold heat medium can be increased early on downstream of the first heat exchanger (11) in the cold heat recovery cycle (3), such as the gas-liquid separator and the cold heat pump. By increasing the proportion of the liquid-phase cold heat medium in the cold heat pump, the performance decrease due to gas entrapment in the cold heat pump (31) can be suppressed, so that the performance of the cold heat pump (31) can be exerted early on. This allows the cold heat recovery system to transition to steady-state operation early on.

2) In some embodiments, the cold heat recovery system (1) described in 1) above,
The cold heat recovery cycle (3) further includes a cold heat turbine (32) configured to be driven by the cold heat medium provided upstream of the first heat exchanger (11),
The cold heat recovery system (1) further includes a second heat exchanger (14) configured to transfer thermal energy from a heat medium to the cold heat medium flowing downstream of the cold heat pump (31) and upstream of the cold heat turbine (32) in the cold heat recovery cycle (3);
The pump bypass line (6) is connected upstream of the second heat exchanger (14) in the cold heat recovery cycle (3).

According to the configuration of 2), the pump bypass line (6) is connected upstream of the second heat exchanger (14) in the cold heat recovery cycle (3). In this case, even if the cold heat pump (31) is driven and the liquid phase cold heat medium is fed downstream of the cold heat pump (31), the liquid phase cold heat medium is vaporized in the second heat exchanger (14), so that the gas phase cold heat medium flows downstream of the second heat exchanger (14) in the same manner as before the cold heat pump (31) is driven. Therefore, during the period from the start of the cold heat recovery system (1) to the steady operation, the transient change of the cold heat medium flowing downstream of the second heat exchanger (14) and upstream of the first heat exchanger (11) can be suppressed. In addition, even after the cold heat pump (31) is driven, the gas-phase cold heat medium flows downstream of the second heat exchanger (14) and upstream of the first heat exchanger (11), so there is no need to suddenly stop the blower means (7), and the cold heat recovery cycle (3) can be gradually shifted to steady operation. Therefore, according to the configuration of 2) above, the reliability of the cold heat recovery system (1) can be improved during the period from startup to steady operation.

3) In some embodiments, the cold heat recovery system (1) described in 1) above,
The cold heat recovery cycle (3) further includes a cold heat turbine (32) configured to be driven by the cold heat medium provided upstream of the first heat exchanger (11),
The cold heat recovery system (1) further includes a second heat exchanger (14) configured to transfer thermal energy from a heat medium to the cold heat medium flowing downstream of the cold heat pump (31) and upstream of the cold heat turbine (32) in the cold heat recovery cycle (3);
The pump bypass line (6) is connected downstream of the second heat exchanger (14) and upstream of the cold energy turbine (32) in the cold energy recovery cycle (3).

According to the configuration of 3), the pump bypass line (6) is connected downstream of the second heat exchanger (14) and upstream of the cold heat turbine (32) in the cold heat recovery cycle (3). In this case, even if the cold heat pump (31) is driven and the liquid phase cold heat medium is sent downstream of the cold heat pump (31), the liquid phase cold heat medium is vaporized in the second heat exchanger (14), so that the gas phase cold heat medium flows downstream of the second heat exchanger (14) in the same manner as before the cold heat pump (31) is driven. Therefore, the inflow of the liquid phase cold heat medium into the pump bypass line (6) can be suppressed compared to the case where the pump bypass line (6) is connected upstream of the second heat exchanger (14) in the cold heat recovery cycle (3). This stabilizes the phase of the cold heat medium flowing through the pump bypass line (6) during the period from startup to steady-state operation of the cold heat recovery system (1), and suppresses the volumetric change of the cold heat medium flowing through the pump bypass line (6), making it possible to gradually transition the cold heat recovery system (1) to steady-state operation. In addition, according to the configuration of 3) above, the control devices (e.g., valves) and measuring devices provided in the pump bypass line (6) can be of single-phase specification (gas-phase specification), which reduces the cost of the devices in the cold heat recovery system (1).

4) In some embodiments, the cold heat recovery system (1) according to 3) above,
The system further includes a check valve (63) provided in the pump bypass line (6) and configured to allow only a flow from the first gas-liquid separator (5) toward the cold heat recovery cycle (3).

According to the configuration of 4) above, the check valve (63) can prevent the gas-phase cold heat medium heated in the second heat exchanger (14) from flowing back through the pump bypass line (6) and into the first gas-liquid separator (5). In this case, the cooling of the first gas-liquid separator (5) can be prevented from being delayed by the gas-phase cold heat medium flowing back through the pump bypass line (6), so that the cold heat recovery system (1) can be quickly shifted to steady-state operation.

5) In some embodiments, the cold heat recovery system (1) described in 2) above,
The cold heat recovery cycle (3) is
a main line (second connection line 34) that connects the second heat exchanger (14) and the first heat exchanger (11) and has the cold turbine (32) provided between the second heat exchanger (14) and the first heat exchanger (11);
a turbine bypass line (37) connecting the upstream side and downstream side of the cold-heat turbine (32) of the main line (34) by bypassing the cold-heat turbine (32),
The blowing means (7) was provided in the turbine bypass line (37).

According to the configuration of 5) above, the blower means (7) provided in the turbine bypass line (37) can send the gas-phase cold heat medium separated in the first gas-liquid separator (5) to the first heat exchanger (11) via the turbine bypass line (37). This can suppress pressure loss in the cold heat turbine 32, so that the performance of the blower means (7) can be effectively demonstrated when the cold heat recovery system (1) is started up.

6) In some embodiments, the cold heat recovery system (1) described in 3) or 4) above,
The cold heat recovery cycle (3) is
a main line (second connection line 34) that connects the second heat exchanger (14) and the first heat exchanger (11) and has the cold turbine (32) provided between the second heat exchanger (14) and the first heat exchanger (11);
a turbine bypass line (37) connecting the upstream side and downstream side of the cold-heat turbine (32) of the main line (34) by bypassing the cold-heat turbine (32),
The blowing means (7) was provided in the turbine bypass line (37).

According to the configuration of 6) above, the blower means (7) provided in the turbine bypass line (37) can send the gas-phase cold heat medium separated in the first gas-liquid separator (5) to the first heat exchanger (11) via the turbine bypass line (37). This can suppress pressure loss in the cold turbine (32), so that the performance of the blower means (7) can be effectively demonstrated when the cold heat recovery system (1) is started up.

7) In some embodiments, the cold heat recovery system (1) according to 6) above,
The system further includes a second gas-liquid separator (8) that is provided either between a connection position (P5) of the pump bypass line (6) in the main line (34) and a connection position (branch portion P2) of the main line (34) with the upstream end of the turbine bypass line (37), or on the upstream side of the blowing means (7) of the turbine bypass line (37), and is configured to separate the cold-heat medium into a gas-phase cold-heat medium and a liquid-phase cold-heat medium.

When the cold heat medium circulating in the cold heat recovery cycle (3) is changed from gaseous to liquid phase, if the liquid of the cold heat medium suddenly flows into the turbine bypass line (37), it may cause a breakdown of the blower means (7). According to the configuration of 7) above, the second gas-liquid separator (8) separates the cold heat medium into gaseous and liquid phases, which prevents the liquid of the cold heat medium from flowing into the turbine bypass line (37) and causing a breakdown of the blower means (7), thereby improving the reliability of the cold heat recovery system (1).

8) In some embodiments, the cold heat recovery system (1) described in 1) above,
The cold heat recovery cycle (3) further includes a cold heat turbine (32) configured to be driven by the cold heat medium provided upstream of the first heat exchanger (11),
The pump bypass line (6) is connected downstream of the cold energy turbine (32) in the cold energy recovery cycle (3);
The blowing means (7) was provided in the pump bypass line (6).

When the cold heat medium circulating in the cold heat recovery cycle 3 is changed from gaseous to liquid phase, the pressure of the gaseous cold heat medium introduced into the blowing means (7) increases suddenly, and the operating point of the blowing means (7) changes suddenly, which may damage the blowing means (7). According to the configuration of 8) above, by connecting the pump bypass line (6) downstream of the cold heat turbine (32), it is possible to prevent the cold heat medium that has passed through the second heat exchanger (14) from flowing directly into the pump bypass line (6). This makes it possible to prevent sudden changes in the operating point of the blowing means (7) provided in the pump bypass line (6), thereby reducing the risk of damage to the blowing means (7). In addition, the pressure resistance performance required of the blowing means (7) can be reduced, thereby reducing the cost of the blowing means (7).

9) In some embodiments, the cold heat recovery system (1) according to 8) above,
The system further includes a return line (64) that connects the downstream side and upstream side of the blowing means (7) of the pump bypass line (6) in a manner that bypasses the blowing means (7).

According to the configuration of 9) above, when the cold heat medium flows back through the pump bypass line (6), the return line (64) has a smaller pressure loss than the line in which the blowing means (7) is provided, so the cold heat medium can be routed through the return line (64). By preventing the backflow of the cold heat medium from flowing back into the blowing means (7), the steady operation of the blowing means (7) can be maintained for a long period of time, and damage caused by surging of the blowing means (7) can be prevented. This improves the reliability of the cold heat recovery system (1).

10) In some embodiments, the cold heat recovery system (1) described in 1) above,
The cold heat recovery cycle (3) further includes a cold heat turbine (32) driven by the cold heat medium provided upstream of the first heat exchanger (11),
The pump bypass line (6)
a first line (6C) connected from the first gas-liquid separator (5) to a first connection position (P10) downstream of the cold energy turbine (32) in the cold energy recovery cycle (3);
In the cold heat recovery cycle (3), a second line (6D) extending from the first connection position (P10) to a branch position (P11) upstream of the cold heat turbine (32);
a third line (6E) connected from the branching position (P11) to a second connection position (P12) downstream of the first connection position (P10) in the cold energy recovery cycle (3), bypassing the cold energy turbine (3);
The cold turbine (32) is configured to function as the blower (7) by rotating in a reverse direction.

According to the configuration of 10) above, by making the cold energy turbine (32) function as the blowing means (7), a dedicated blowing means for sending the gas-phase cold energy medium through the pump bypass line (6) is not required, so the cost of the equipment in the cold energy recovery system 1 can be reduced.

11) In some embodiments, the cold heat recovery system (1) according to any one of 1) to 10) above,
a fuel supply line (13A) for supplying the liquefied gas vaporized in the first heat exchanger (11) to a main engine (22A) of the ship (2A) or the floating body (2B);
a branch line (24) branching off from the fuel supply line (13A) for supplying the liquefied gas vaporized in the first heat exchanger (11) to a supply destination (23) other than the main engine (22A);
The plant further includes a gas combustion device (23) that is configured separately from the main engine (22A) and is connected to the branch line (24).

When the cold heat recovery system (1) is started, the flow rate of the cold heat medium circulating through the cold heat recovery cycle (3) is small, so the liquefied gas is supplied to the main engine (22A) without being fully vaporized, which may cause the main engine (22A) to malfunction. According to the configuration of 11) above, when the cold heat recovery system (1) is started, the vaporized gas and liquefied gas can be guided to the gas combustion device (23) via the branch line (24) and combusted in the gas combustion device (23). This makes it possible to prevent the liquefied gas from being supplied to the main engine (22A) without being fully vaporized, thereby preventing the main engine (22A) from malfunctioning or failing to operate properly.

12) A method for starting up a cold energy recovery system (1) according to at least one embodiment of the present disclosure (100) includes:
A method (100) for starting up a cold energy 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, comprising:
The cold heat recovery system (1) comprises:
A first heat exchanger (11) configured to transfer cold energy from the liquefied gas extracted from the liquefied gas storage device (21) to a cold heat medium;
a cold heat recovery cycle (3) configured to circulate the cold heat transfer medium, the cold heat recovery cycle (3) including a cold heat pump (31) for feeding the cold heat transfer medium, the cold heat recovery cycle (3) being provided downstream of the first heat exchanger (11);
The method for starting the cold heat recovery system (100) includes:
a gas-liquid separation step (S101) of separating the cold heat medium into a gas-phase cold heat medium and a liquid-phase cold heat medium 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);
A blowing step (S102) of sending the gas-phase cold heat medium separated in the gas-liquid separation step (S101) to the first heat exchanger (11) by bypassing the cold heat pump (31);
a cooling step (S103) of sending the liquefied gas from the liquefied gas storage device (21) to the first heat exchanger (11) and cooling the gas-phase cold heat medium sent to the first heat exchanger (11) in the blowing step (S102) by the liquefied gas;
and a cold heat pump driving step (S104) of driving the cold heat pump (31) after the cooling step (S103).

According to the method of 12) above, the gas-phase cold heat medium separated in the gas-liquid separation step (S101) is sent to the first heat exchanger (11) (air blowing step S102) bypassing the cold heat pump (31), thereby circulating the gas-phase cold heat medium in the cold heat recovery cycle (3). Since the gas-phase cold heat medium is less likely to cause blockage in the first heat exchanger (11) than the liquid-phase cold heat medium, blockage of the first heat exchanger (11) can be suppressed when the cold heat recovery system (1) is started up.

According to the method of 12), the gas-phase cold heat medium circulating in the cold heat recovery cycle (3) is cooled by liquefied gas in the first heat exchanger (11) (cooling step S103) and condensed, so that the proportion of the liquid-phase cold heat medium can be increased early on downstream of the first heat exchanger (11) 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 cold heat medium in the cold heat pump (31), the performance decrease due to gas entrapment in the cold heat pump (31) can be suppressed, so that the cold heat pump (31) can be driven early (cold heat pump drive step S104), and the performance of the cold heat pump (31) can be exerted early. This allows the cold heat recovery cycle (1) to transition to steady operation early.

13) In some embodiments, a method (100) for starting up the cold heat recovery system (1) described in 12) above, comprising:
The method further includes a liquid level acquisition step (S109) of acquiring a liquid level of the liquid phase cold heat medium stored inside the gas-liquid separator (5),
When the liquid level acquired in the liquid level acquisition step (S109) exceeds a threshold value, the cold heating pump driving step (S104) is performed.

According to the method of 13) above, when the liquid level of the liquid-phase cold heat medium stored inside the first gas-liquid separator (5) exceeds a threshold value, the proportion of the liquid-phase cold heat medium in the cold heat pump (31) is sufficiently large. By using the liquid level as a judgment criterion, it is possible to effectively suppress the performance degradation of the cold heat pump (31) due to gas entrapment.

1 Cold energy recovery system 2A Ship 2B Floating body 3 Cold energy recovery cycle 5 First gas-liquid separator 6 Pump bypass line 6A First pump bypass line 6B Second pump bypass line 6C First line 6D Second line 6E Third line 7 Blowing means 7A, 7B Blower 8 Second gas-liquid separator 9 Control device 11 First heat exchanger 12 Liquefied gas supply line 13 Vaporized gas supply line 14 Second heat exchanger 15 Liquefied gas pump 21 Liquefied gas storage device 22 Gas supply destination 22A Main engine 23 Gas combustion device 24 Branch line 26 Third opening and closing valve 27 Fourth opening and closing valve 31 Cold energy pump 32 Cold energy turbine 33 First connection line 33A First upper stage connection line 33B First middle stage connection line 33C First lower stage connection line 34 Second connection line 34A Second upper stage connection line 34B Second lower stage connecting line 35 Liquid return line 36 First flow control valve 37 Turbine bypass line 38 Second flow control valve 39 Third 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 51 Internal space 51A Upper storage space 51B Lower storage space 52 Main body 53 Inlet 54 Liquid phase discharge port 55 Gas phase discharge port 56 Liquid return port 63 Check valve 64 Flow line 65 Pressure reducing valve 71 Rotating shaft 72 Moving blades 73 Casing 74 Electric motor 100 Method for starting cold heat recovery system S101 Gas-liquid separation step S102 Air blowing step S103 Cooling step S104 Cold heat pump driving step S105 Valve opening step S106 Air blowing means stopping step S107 Cold heat turbine driving step S108 External water pump drive step S109 Liquid level acquisition step T1 First period T2 Second period T3 Third period TH Threshold value WL Liquid level

Claims (13)

A cold energy 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 energy from the liquefied gas extracted from the liquefied gas storage device to a cold heat medium;
A cold heat recovery cycle configured to circulate the cold heat medium, the cold heat recovery cycle including at least a cold heat pump for feeding the cold heat medium provided downstream of the first heat exchanger;
A first gas-liquid separator is provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle and configured to separate the cold heat medium into a gas phase cold heat medium and a liquid phase cold heat medium;
a pump bypass line for extracting the gas-phase cold heat medium from the first gas-liquid separator and guiding the gas-phase cold heat medium to a downstream side of the cold heat pump and an upstream side of the first heat exchanger in the cold heat recovery cycle;
a blowing means for sending the gas-phase cold heat medium to the first heat exchanger through the pump bypass line. The cold heat recovery cycle further includes a cold heat turbine configured to be driven by the cold heat medium provided upstream of the first heat exchanger,
The cold heat recovery system further includes a second heat exchanger configured to transfer thermal energy from a heat medium to the cold heat medium flowing downstream of the cold heat pump and upstream of the cold heat turbine in the cold heat recovery cycle;
The pump bypass line is connected upstream of the second heat exchanger in the cold heat recovery cycle.
The cold heat recovery system according to claim 1 . The cold heat recovery cycle further includes a cold heat turbine configured to be driven by the cold heat medium provided upstream of the first heat exchanger,
The cold heat recovery system further includes a second heat exchanger configured to transfer thermal energy from a heat medium to the cold heat medium flowing downstream of the cold heat pump and upstream of the cold heat turbine in the cold heat recovery cycle;
The pump bypass line is connected downstream of the second heat exchanger in the cold heat recovery cycle and upstream of the cold heat turbine.
The cold heat recovery system according to claim 1 . a check valve provided in the pump bypass line and configured to allow only a flow from the first gas-liquid separator to the cold heat recovery cycle;
The cold heat recovery system according to claim 3 . The cold heat recovery cycle includes:
a main line connecting the second heat exchanger and the first heat exchanger, and having the cold turbine provided between the second heat exchanger and the first heat exchanger;
a turbine bypass line that connects the upstream side and downstream side of the main line relative to the low-temperature turbine, bypassing the low-temperature turbine;
The blowing means is provided in the turbine bypass line.
The cold heat recovery system according to claim 2 . The cold heat recovery cycle includes:
a main line connecting the second heat exchanger and the first heat exchanger, and having the cold turbine provided between the second heat exchanger and the first heat exchanger;
a turbine bypass line that connects the upstream side and downstream side of the main line relative to the low-temperature turbine, bypassing the low-temperature turbine;
The blowing means is provided in the turbine bypass line.
The cold heat recovery system according to claim 3 or 4. The cooling system further includes a second gas-liquid separator that is provided in the pump bypass line, between a connection position of the pump bypass line in the main line and a connection position of the upstream end of the turbine bypass line, or on the upstream side of the blowing means of the turbine bypass line, and is configured to separate the cold heat medium into a gas phase cold heat medium and a liquid phase cold heat medium.
The cold heat recovery system according to claim 6. The cold heat recovery cycle further includes a cold heat turbine configured to be driven by the cold heat medium provided upstream of the first heat exchanger,
the pump bypass line is connected downstream of the cold energy turbine in the cold energy recovery cycle,
The blowing means is provided in the pump bypass line.
The cold heat recovery system according to claim 1 . The pump bypass line further includes a return line that connects the downstream side and the upstream side of the blowing means, bypassing the blowing means.
The cold heat recovery system according to claim 8. The cold heat recovery cycle further includes a cold heat turbine that is driven by the cold heat medium and is provided upstream of the first heat exchanger,
The pump bypass line is
a first line connected from the first gas-liquid separator to a first connection position downstream of the cold energy turbine in the cold energy recovery cycle;
a second line extending from the first connection position to a branch position upstream of the cold heat turbine in the cold heat recovery cycle;
a third line extending from the branching position, bypassing the cold energy turbine, and connected to a second connection position downstream of the first connection position in the cold energy recovery cycle,
The cold turbine is configured to function as the blower by rotating in a reverse direction.
The cold heat recovery system according to claim 1 . a fuel supply line for supplying the liquefied gas vaporized in the first heat exchanger to a main engine of the ship or the floating body;
a branch line branching off from the fuel supply line for supplying the liquefied gas vaporized in the first heat exchanger to a destination other than the main engine;
a gas combustion device that is separate from the main engine and is connected to the branch line,
The cold heat recovery system according to any one of claims 1 to 10. A method for starting up a cold energy recovery system installed on a ship or floating body having a liquefied gas storage device configured to store liquefied gas, comprising:
The cold heat recovery system includes:
A first heat exchanger configured to transfer cold energy from the liquefied gas extracted from the liquefied gas storage device to a cold heat medium;
A cold heat recovery cycle configured to circulate the cold heat medium, the cold heat recovery cycle including a cold heat pump for feeding the cold heat medium, the cold heat recovery cycle being provided downstream of the first heat exchanger,
The method for starting the cold heat recovery system includes:
A gas-liquid separation step of separating the cold heat medium into a gas phase cold heat medium and a liquid phase cold heat medium by a gas-liquid separator provided between the first heat exchanger and the cold heat pump in the cold heat recovery cycle;
a blowing step of sending the gas-phase cold heat transfer medium separated in the gas-liquid separation step to the first heat exchanger by bypassing the cold heat pump;
A cooling step of sending the liquefied gas from the liquefied gas storage device to the first heat exchanger and cooling the gas-phase cold heat medium sent to the first heat exchanger in the blowing step by the liquefied gas;
and a cold heat pump driving step of driving the cold heat pump after the cooling step.
How to start a cold recovery system. The liquid level acquisition step further includes acquiring a liquid level of the liquid phase cold heat medium stored inside the gas-liquid separator,
When the liquid level acquired in the liquid level acquisition step exceeds a threshold value, the cold heating pump driving step is performed.
The method for starting up a cold energy recovery system according to claim 12.

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