JP7680856B2 - Cold heat recovery system and ship or floating structure - Google Patents

Description

This disclosure relates to a cold energy recovery system for recovering cold energy from liquefied gas, and to a ship or floating body equipped with 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 the cold energy of liquefied gas as electricity. Known examples of this cold energy power generation cycle include the secondary medium Rankine cycle system (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 order to achieve higher output, a combined cycle can be considered that combines the above-mentioned cold power generation cycle with a direct expansion turbine that is driven by the expansion energy of vaporized gas produced by vaporizing liquefied gas. In order to improve the output of this combined cycle, it is possible to heat the vaporized gas supplied to the direct expansion turbine with seawater to raise its temperature, but there is a risk that the heat exchanger that exchanges heat between the vaporized gas and seawater will become clogged.

In view of the above circumstances, an objective of at least one embodiment of the present disclosure is to provide a cold heat recovery system and a ship or floating body that can improve the output and reliability of 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 vaporize the liquefied gas;
a liquefied gas supply line for supplying the liquefied gas from the liquefied gas storage device to the first heat exchanger;
A cold heat recovery cycle configured to circulate a cold heat medium that has been heat exchanged with the liquefied gas in the first heat exchanger, the cold heat recovery cycle including a cold heat turbine configured to be driven by the cold heat medium;
The cold heat recovery system further includes a second heat exchanger configured to exchange heat between the cold heat medium flowing between the cold heat turbine and the first heat exchanger in the cold heat recovery cycle and external water introduced from outside the cold heat recovery system.

A ship or floating body according to one embodiment of the present disclosure is equipped with the above-mentioned cold heat recovery system.

At least one embodiment of the present disclosure provides a cold heat recovery system that can improve the output and reliability of the cold heat recovery system, and a ship or floating body equipped with the cold heat recovery system.

1 is a schematic diagram showing a configuration of a ship or a floating body equipped with a cold heat recovery system according to an embodiment of the present disclosure. FIG. 1 is a schematic diagram showing a configuration of a ship or a floating body equipped with a cold heat recovery system according to a comparative example. 1 is a schematic diagram showing a configuration of a ship or a floating body equipped with a cold heat recovery system according to an embodiment of the present disclosure. 1 is a schematic diagram showing a configuration of a ship or a floating body equipped with a 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 or a floating body equipped with a cold energy recovery system according to an embodiment of the present disclosure. As shown in FIG. 1, a cold energy recovery system 1 according to some embodiments is installed on a ship 10A or a floating body 10B. The ship 10A or the floating body 10B is a structure that can float on water and has a liquefied gas storage device (e.g., a liquefied gas tank) 11 configured to store liquefied gas. The ship 10A is a structure that has a propeller (not shown) such as a propeller and a propulsion device (not shown) configured to drive the propulsion device, and is configured to be self-propelled by driving the propulsion device. The floating body 10B is a structure that is not self-propelled and does not have a propulsion device for self-propulsion like the ship 10A.

(Cold heat recovery system)
1, the cold heat recovery system 1 includes a first heat exchanger (liquefied gas vaporizer) 12 configured to vaporize liquefied gas, a liquefied gas supply line 2 for supplying liquefied gas from a liquefied gas storage device 11 to the heat exchanger 12, a vaporized gas supply line 3 for supplying vaporized gas generated by vaporizing the liquefied gas in the heat exchanger 12, and a cold heat recovery cycle 4 configured to circulate the cold heat medium that has been heat exchanged with the liquefied gas in the heat exchanger 12. The vaporized gas is guided to a gas supply destination 13 through the vaporized gas supply line 3.

The following description will be given taking liquefied natural gas (LNG) as a specific example of the liquefied gas supplied from the liquefied gas storage device 11 and propane as a specific example of the cold heat medium flowing through the cold heat recovery cycle 4, but the present disclosure can also be applied when 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 11, and can also be applied when 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 4. The cold heat medium has a lower boiling point and freezing point than water.

(First Heat Exchanger)
The heat exchanger 12 is configured to perform heat exchange between the liquefied gas sent from the liquefied gas supply line 2 and the cold heat medium flowing in the cold heat recovery cycle 4. The heat exchanger 12 includes a one-side passage 121 through which the liquefied gas sent from the liquefied gas supply line 2 flows, and a other-side passage 122 through which the cold heat medium provided in the cold heat recovery cycle 4 flows. In the heat exchanger 12, heat exchange is performed between the one-side passage 121 and the other-side passage 122, and the cold energy of the liquefied gas flowing in the one-side passage 121 is recovered by the cold heat medium flowing in the other-side passage 122. As a result, the liquefied gas flowing in the one-side passage 121 is heated and vaporized. In addition, the cold heat medium flowing in the other-side passage 122 is cooled.

(Liquefied gas supply line, vaporized gas supply line)
The liquefied gas supply line 2 includes a liquefied gas flow path 20 having one side connected to the liquefied gas storage device 11 and the other side connected to the upstream end of one side passage 121 of the heat exchanger 12. The vaporized gas supply line 3 includes a vaporized gas flow path 30 having one side connected to the downstream end of the one side passage 121 of the heat exchanger 12 and the other side connected to a supply destination 13 of the vaporized gas. The one side passage 121 of the heat exchanger 12 includes a flow path (pipe) connecting the liquefied gas flow path 20 and the vaporized gas flow path 30. Each of the one side passage 121 of the heat exchanger 12, the liquefied gas flow path 20, and the vaporized gas flow path 30 is configured to be able to flow liquefied gas or vaporized gas obtained by vaporizing the liquefied gas. The supply destination 13 of the vaporized gas may be equipment provided outside the ship 10A or the float 10B (for example, a power generation equipment or a gas storage equipment on land, or may be equipment mounted on the ship 10A or the float 10B).

(Gas pump)
The liquefied gas supply line 2 further includes a gas pump 21 provided in the liquefied gas flow path 20. The gas pump 21 is configured to send liquefied gas to the downstream side of the liquefied gas flow path 20 (i.e., the side where the heat exchanger 12 is located). In the illustrated embodiment, the gas pump 21 includes a rotor blade 211 provided in the liquefied gas flow path 20 and an electric motor 212 configured to supply the rotor blade 211 with a driving force for rotating the rotor blade 211. By driving the gas pump 21, the liquefied gas stored in the liquefied gas storage device 11 is extracted to the liquefied gas supply line 2 and sent to the heat exchanger 12 through the liquefied gas supply line 2. The vaporized gas generated by vaporizing the liquefied gas in the heat exchanger 12 is sent to the supply destination 13 through the vaporized gas supply line 3 by the gas pump 21.

(Cold heat recovery cycle)
The cold heat recovery cycle 4 is configured to circulate the cold heat medium under an organic Rankine cycle. The cold heat recovery cycle 4 includes a cold heat flow path 40 for circulating the cold heat medium that has been heat exchanged with the liquefied gas, a cold heat turbine 5 configured to be driven by the cold heat energy of the cold heat medium, a cold heat pump 41 configured to compress the cold heat medium, and a cold heat heater 42 configured to heat the cold heat medium compressed by the cold heat pump 41.

The other side passage 122 of the heat exchanger 12 is provided on the cold heat recovery cycle 4 and is connected to the cold heat flow path 40 so that the cold heat medium can flow. The heat exchanger 12 functions as a cold heat cooler in the cold heat recovery cycle 4. The cold heat cooler (heat exchanger 12) is configured to cool the cold heat medium expanded by the cold heat turbine 5 using the cold energy of the liquefied gas.

The cold heat turbine 5 is provided downstream of the one-side passage 421 of the cold heat heater 42 and upstream of the other-side passage 122 of the heat exchanger 12 in the cold heat recovery cycle 4. The cold heat pump 41 is provided downstream of the other-side passage 122 of the heat exchanger 12 and upstream of the one-side passage 421 of the cold heat heater 42 in the cold heat recovery cycle 4. Note that "upstream side" means the upstream side in the flow direction of the heat medium (cold heat medium), and "downstream side" means the downstream side in the flow direction of the heat medium (cold heat medium).

(Heat and cold pump)
The cold heat pump 41 is configured to send a cold heat medium to the downstream side of the cold heat recovery cycle 4 (i.e., the side where the cold heat heater 42 is located). In the illustrated embodiment, the cold heat pump 41 includes a rotor blade 411 provided in the cold heat flow path 40, and an electric motor 412 configured to supply the rotor blade 411 with a driving force for rotating the rotor blade 411. By driving the cold heat pump 41, the cold heat medium circulates through the other side passage 122 of the heat exchanger 12 and the cold heat flow path 40. The cold heat medium cooled in the heat exchanger 12 is compressed by the cold heat pump 41 and then guided to the cold heat heater 42. The cold heat medium heated in the cold heat heater 42 is introduced into the cold heat turbine 5. In some embodiments, the cold heat recovery cycle 4 may be configured to liquefy the cold heat medium by cooling in the heat exchanger 12 and to vaporize the cold heat medium by heating in the cold heat heater 42.

(heater for cold/heat)
The cold heat heater 42 is configured to perform heat exchange between the cold heat medium flowing through the cold heat recovery cycle 4 and external water introduced from outside the cold heat recovery system 1. The cold heat heater 42 includes a one-side passage 421 through which the cold heat medium flows and a second-side passage 422 through which the external water flows. The one-side passage 421 of the cold heat heater 42 is provided on the cold heat recovery cycle 4 and is connected to the cold heat flow path 40 so that the cold heat medium can flow. In the cold heat heater 42, heat exchange is performed between the one-side passage 421 and the other-side passage 422, and the thermal energy of the external water flowing through the other-side passage 422 is recovered by the cold heat medium flowing through the one-side passage 421. As a result, the cold heat medium flowing through the one-side passage 421 is heated. The cold heat heater 42 raises the temperature of the cold heat medium introduced into the cold heat turbine 5.

The external water may be water that can heat the heat exchange target as a heat medium in the heat exchanger (water that is hotter 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 10A or the float 10B (for example, outside the ship, such as seawater, or engine cooling water that cools the engine of the ship 10A).

(Cold Heat Turbine)
The cold heat turbine 5 includes a rotating shaft 51, turbine blades 52 attached to the rotating shaft 51, and a casing 53 that rotatably houses the rotating shaft 51 and the turbine blades 52. The cold heat turbine 5 is configured to rotate the turbine blades 52 by the energy of a cold heat medium introduced into the casing 53. The cold heat medium that has passed through the turbine blades 52 is discharged to the outside of the casing 53.

The cold heat recovery cycle 4 is configured to recover the rotational force of the turbine blades 52 as power. In the illustrated embodiment, the cold heat recovery cycle 4 further includes a cold heat generator 54 configured to generate power by driving the cold heat turbine 5. The cold heat generator 54 is mechanically connected to the rotating shaft 51 and configured to convert the rotational force of the turbine blades 52 into electric power. In some other embodiments, the cold heat recovery cycle 4 may recover the rotational force of the turbine blades 52 as power directly using a power transmission device (e.g., a coupling, a belt, a pulley, etc.) rather than converting it into electric power. The cold heat recovery cycle 4 may also include a bypass flow path 43 that bypasses the cold heat turbine 5.

(Vaporized gas turbine)
The cold energy recovery system 1 may include a vaporized gas turbine 6 configured to be driven by cold energy of a vaporized gas obtained by vaporizing a liquefied gas, as shown in Fig. 1. The vaporized gas turbine 6 includes a turbine blade 62 provided in a vaporized gas flow path 30. The vaporized gas turbine 6 is introduced with the vaporized gas heated in the first heat exchanger 12 after being pressurized by a gas pump 21. The vaporized gas supply line 3 includes an upstream vaporized gas supply line 3A for guiding the vaporized gas from the first heat exchanger 12 to the vaporized gas turbine 6, and a downstream vaporized gas supply line 3B for guiding the vaporized gas from the vaporized gas turbine 6 to a gas supply destination 13.

The vaporized gas turbine 6 includes a rotating shaft 61, the above-mentioned turbine blades 62 attached to the rotating shaft 61, and a casing 63 that rotatably houses the rotating shaft 61 and the turbine blades 62. The vaporized gas turbine 6 is configured to rotate the turbine blades 62 by the energy (expansion energy) of the vaporized gas introduced into the inside of the casing 63. In other words, the vaporized gas turbine 6 is composed of an expansion turbine that uses the vaporized gas as the working fluid. The vaporized gas that has passed through the turbine blades 62 is discharged to the outside of the casing 63.

The vaporized gas turbine 6 is configured to recover the rotational force of the turbine blades 62 as power. In the illustrated embodiment, the vaporized gas turbine 6 further includes a vaporized gas generator 64 configured to generate power by driving the turbine blades 62. The vaporized gas generator 64 is mechanically connected to the rotating shaft 61 and configured to convert the rotational force of the turbine blades 62 into electric power. In some other embodiments, the vaporized gas turbine 6 may recover the rotational force of the turbine blades 62 as power directly using a power transmission device (e.g., a coupling, a belt, a pulley, etc.) rather than converting it into electric power. The vaporized gas supply line 3 may also include a bypass flow path 31 that bypasses the vaporized gas turbine 6.

(Vaporized gas heater)
1, the cold heat recovery system 1 may include a vaporized gas heater 32 configured to perform heat exchange between the vaporized gas flowing through the vaporized gas supply line 3 and external water introduced from outside the cold heat recovery system 1. The vaporized gas heater 32 is provided on the downstream vaporized gas supply line 3B downstream of the vaporized gas turbine 6.

The vaporized gas heater 32 includes a one-side passage 321 through which the vaporized gas flows, and a second-side passage 322 through which the external water flows. The one-side passage 321 of the vaporized gas heater 32 is provided on the vaporized gas supply line 3 and is connected to the vaporized gas flow path 30 so that the vaporized gas can flow. In the vaporized gas heater 32, heat exchange is performed between the one-side passage 321 and the other-side passage 322, and the thermal energy of the external water flowing through the other-side passage 322 is recovered by the vaporized gas flowing through the one-side passage 321. This heats the vaporized gas flowing through the one-side passage 321. By heating the vaporized gas with the vaporized gas heater 32, the vaporized gas can be heated to a temperature required at the gas supply destination 13.

(Second Heat Exchanger)
1, the cold heat recovery system 1 includes a second heat exchanger 14 configured to perform heat exchange between a cold heat medium flowing between the cold heat turbine 5 and the first heat exchanger 12 in the cold heat recovery cycle 4 and external water introduced from outside the cold heat recovery system 1. The second heat exchanger 14 includes a one-side passage 141 through which the cold heat medium flows and a second-side passage 142 through which the external water flows, which are provided downstream of the cold heat turbine 5 and the bypass flow path 43 and upstream of the first heat exchanger 12 in the cold heat recovery cycle 4. The one-side passage 141 of the second heat exchanger 14 is provided on the cold heat recovery cycle 4 and is connected to the cold heat flow path 40 so that the cold heat medium can flow.

The cold heat medium that has passed through the cold heat turbine 5 or the bypass flow path 43 flows through the one-side passage 141 of the second heat exchanger 14 and is then guided to the other-side passage 122 of the first heat exchanger 12. In the second heat exchanger 14, heat exchange takes place between the one-side passage 141 and the other-side passage 142, and the thermal energy of the external water flowing through the other-side passage 142 is recovered by the cold heat medium flowing through the one-side passage 141. This heats up the cold heat medium flowing through the one-side passage 141. The second heat exchanger 14 raises the temperature of the cold heat medium introduced into the other-side passage 122 of the first heat exchanger 12.

(External water supply line, external water discharge line)
The cold heat recovery system 1 includes an external water supply line 8 for supplying external water from an external water supply source 16 to heat exchangers (the second heat exchanger 14, the cold heat heater 42, and the vaporized gas heater 32) that use the external water of the cold heat recovery system 1 as a heat medium, and an external water discharge line 9 for discharging the external water discharged from the heat exchangers that use the external water as a heat medium to an external water discharge destination 17.

As shown in FIG. 1, the external water supply line 8 includes a first external water supply flow path 81 connecting the external water supply source 16 and the second heat exchanger, a second external water supply flow path 82 connecting the external water supply source 16 and the cold heater 42, a third external water supply flow path 83 connecting the external water supply source 16 and the vaporized gas heater 32, and an external water pump 84 configured to send external water to the downstream side of the external water supply line 8 (i.e., the side where the heat exchanger using the external water as a heat medium is located). In the illustrated embodiment, the first external water supply flow path 81, the second external water supply flow path 82, and the third external water supply flow path 83 form a shared flow path 86 upstream of the branching portion 85. The external water pump 84 includes a rotor blade 841 provided in the shared flow path 86, and an electric motor 842 configured to supply the rotor blade 841 with a driving force to rotate the rotor blade 841. By driving the external water pump 84, external water is extracted from the external water supply source 16 to the external water supply line 8 and sent through the external water supply line 8 to a heat exchanger using the external water as a heat medium. By providing the external water pump 84 in the shared flow path 86, the cold heat recovery system 1 can be prevented from becoming larger, more complicated, and more expensive. In some other embodiments, the external water supply line 8 may be configured without the shared flow path 86, and the first external water supply flow path 81, the second external water supply flow path 82, and the third external water supply flow path 83 may each be connected to a different external water supply source 16.

1, the external water discharge line 9 includes a first external water discharge flow path 91 connecting the second heat exchanger 14 and the external water discharge destination 17A (17), a second external water discharge flow path 92 connecting the cold heater 42 and the external water discharge destination 17B, and a third external water discharge flow path 93 connecting the vaporized gas heater 32 and the external water discharge destination 17C. The external water discharge destination 17A may be the same as at least one of the discharge destinations 17B or 17C. The first external water discharge flow path 91 may be configured to share a portion with at least one of the second external water discharge flow path 92 or the third external water discharge flow path 93.

(Comparative Example of Cold Heat Recovery Cycle)
2 is a schematic diagram showing the configuration of a ship or a floating body equipped with a cold energy recovery system according to a comparative example. The cold energy recovery system 01 according to the comparative example is equipped with a third heat exchanger 15 instead of the second heat exchanger 14 described above. The cold energy recovery system 01 also includes the first heat exchanger 12 described above, the liquefied gas supply line 2 described above, the vaporized gas supply line 3 described above, the cold energy recovery cycle 4 including the cold energy turbine 5 described above, and the vaporized gas turbine 6 described above.

The third heat exchanger 15 is provided on the upstream vaporized gas supply line 3A upstream of the vaporized gas turbine 6. The third heat exchanger 15 is configured to perform heat exchange between the vaporized gas flowing through the upstream vaporized gas supply line 3A and external water introduced from outside the cold heat recovery system 1. The third heat exchanger 15 includes a one-side passage 151 through which the vaporized gas flows and a second-side passage 152 through which the external water flows. The one-side passage 151 of the third heat exchanger 15 is provided on the upstream vaporized gas supply line 3A and is connected to the vaporized gas flow path 30 so that the vaporized gas can flow through it. In the third heat exchanger 15, heat exchange is performed between the one-side passage 151 and the other-side passage 152, and the thermal energy of the external water flowing through the other-side passage 152 is recovered to the vaporized gas flowing through the one-side passage 151. As a result, the vaporized gas flowing through the one-side passage 151 is heated. By heating the vaporized gas using the third heat exchanger 15, the temperature of the vaporized gas at the inlet of the vaporized gas turbine 6 can be increased.

The cold heat recovery system 01 according to the comparative example includes an external water supply line 08 and an external water discharge line 09. The external water supply line 08 includes a fourth external water supply flow path 87 connecting the external water supply source 16 and the third heat exchanger 15, the second external water supply flow path 82 described above, the third external water supply flow path 83 described above, and the external water pump 84 described above. The external water discharge line 09 includes a fourth external water discharge flow path 94 connecting the third heat exchanger 15 and the external water discharge destination 17D, the second external water discharge flow path 92 described above, and the third external water discharge flow path 93 described above.

In the cold heat recovery system 1 shown in FIG. 1, the cold heat medium is heated by the second heat exchanger 14, so the temperature of the cold heat medium supplied to the first heat exchanger 12 is higher than in the cold heat recovery system 01 according to the comparative example. By increasing the temperature of the cold heat medium supplied to the first heat exchanger 12, the amount of heat exchange between the liquefied gas and the cold heat medium in the first heat exchanger 12 can be increased. As a result, in the cold heat recovery system 1 shown in FIG. 1, the temperature of the vaporized gas at the outlet of the first heat exchanger 12 is higher than in the cold heat recovery system 01 according to the comparative example.

As shown in FIG. 1, the cold heat recovery system 1 according to some embodiments includes the first heat exchanger 12 described above, the liquefied gas supply line 2 described above, the cold heat recovery cycle 4 including the cold heat turbine 5 described above, and the second heat exchanger 14 described above.

According to the above configuration, the second heat exchanger 14 exchanges heat between the cold heat medium flowing between the cold heat turbine 5 and the first heat exchanger 12 in the cold heat recovery cycle 4 and the external water, and the cold heat medium is heated. Therefore, the temperature of the cold heat medium supplied to the first heat exchanger 12 is higher than that of the cold heat recovery system 01 according to the comparative example. The first heat exchanger 12 exchanges heat between the cold heat medium after heating in the second heat exchanger 14 and the liquefied gas, and the liquefied gas is heated. By preheating the cold heat medium guided to the first heat exchanger 12 in the second heat exchanger 14, the amount of heat exchange between the cold heat medium and the liquefied gas in the first heat exchanger 12 can be increased compared to the cold heat recovery system 01 according to the comparative example, and the cold energy recovered by the cold heat medium from the liquefied gas can be increased. This allows the output of the cold energy turbine 5 to be increased, and thus the output of the cold energy recovery system 1 to be increased.

In addition, by preheating the cold heat medium introduced into the first heat exchanger 12 in the second heat exchanger 14, the cold heat medium can be prevented from solidifying during heat exchange between the cold heat medium and the liquefied gas in the first heat exchanger 12. As a result, compared to the cold heat recovery system 01 in the comparative example, the cold heat medium solidified in the first heat exchanger 12 can be prevented from freezing and blocking the first heat exchanger 12. This improves the reliability of the cold heat recovery system 1 when a small heat exchanger is used for the first heat exchanger 12.

In some embodiments, as shown in FIG. 1, the above-mentioned cold heat recovery system 1 further includes, in addition to the liquefied gas supply line 2, the cold heat recovery cycle 4, the first heat exchanger 12 and the second heat exchanger 14, the above-mentioned vaporized gas supply line 3 (upstream vaporized gas supply line 3A) and the above-mentioned vaporized gas turbine 6.

According to the above configuration, vaporized gas is supplied from the first heat exchanger 12 to the vaporized gas turbine 6 through the vaporized gas supply line 3 (upstream vaporized gas supply line 3A). By preheating the cold heat medium guided to the first heat exchanger 12 in the second heat exchanger 14, the amount of heat exchange between the cold heat medium and the liquefied gas in the first heat exchanger 12 can be increased, and the cold energy recovered from the liquefied gas by the cold heat medium can be increased. This makes it possible to increase the temperature of the vaporized gas at the inlet of the vaporized gas turbine 6, thereby increasing the output of the vaporized gas turbine 6 and, ultimately, the output of the cold energy recovery system 1.

The output generated by the cold heat recovery system 1 shown in FIG. 1 is expressed by subtracting the total power consumption of the pumps (gas pump 21, cold heat pump 41, and external water pump 84) of the cold heat recovery system 1 from the total power generated by the generators (cold heat generator 54 and vaporized gas generator 64) of the cold heat recovery system 1. The cold heat recovery system 1 can generate more power from the cold heat generator 54 and vaporized gas generator 64 than the cold heat recovery system 01 in the comparative example. Therefore, the output generated by the cold heat recovery system 1 is greater than the output generated by the cold heat recovery system 01 in the comparative example.

In addition, since the first heat exchanger 12 and the second heat exchanger 14 can increase the temperature of the vaporized gas at the inlet of the vaporized gas turbine 6, it is not necessary to provide a heat exchanger (third heat exchanger 15 shown in FIG. 2) in the upstream vaporized gas supply line 3A for preheating the vaporized gas to be supplied to the vaporized gas turbine 6. In this case, there is no risk of blockage of the heat exchanger, and the reliability of the cold heat recovery system 1 can be improved.

In some embodiments, the external water in the cold heat recovery system 1 described above includes seawater. In the illustrated embodiment, as shown in FIG. 1, the external water source 16 comprises a water intake provided on the ship 10A or the float 10B for introducing water (such as seawater) outside the ship. The external water discharge destination 17 (17A, 17B, 17C, 17D) comprises a discharge outlet provided on the ship 10A or the float 10B for discharging water outside the ship.

According to the above configuration, the cold heat recovery system 1 is mounted on a ship 10A or a floating body 10B, and therefore seawater is easily available. The cold heat recovery system 1 uses seawater, which is easily available, as a heat medium for the cold heat medium in heat exchangers such as the second heat exchanger 14 and the cold heat heater 42, and does not require the installation of storage facilities for storing the heat medium for the cold heat medium, thereby preventing the cold heat recovery system 1 from becoming too large, complicated, or expensive.

FIG. 3 is a schematic diagram illustrating a configuration of a ship or a floating body equipped with a cold energy recovery system according to an embodiment of the present disclosure.
3, the above-mentioned cold energy recovery system 1 further includes a heat medium replenishment line 24 branched from the liquefied gas supply line 2 and connected to the cold energy recovery cycle 4. In the illustrated embodiment, the heat medium replenishment line 24 includes a replenishment passage 25 having one side 251 connected to the liquefied gas supply line 2 downstream of the gas pump 21 and the other side 252 connected downstream of the first heat exchanger 12 in the cold energy recovery cycle 4 and upstream of the cold energy pump 41, and a valve 26 configured to open and close the replenishment passage 25.

In the illustrated embodiment, the cold heat recovery cycle 4 includes a storage device 44 for storing the cold heat medium (in the illustrated example, liquefied gas) downstream of the connection of the heat medium refill line 24 and upstream of the cold heat pump 41. The cold heat recovery system 1 includes a liquid level acquisition device 71 configured to acquire the liquid level of the cold heat medium stored in the storage device 44, and an opening/closing control device 72 that controls the opening and closing of the valve 26 according to the liquid level acquired by the liquid level acquisition device 71. For example, the opening/closing control device 72 instructs the valve 26 to close the refill flow path 25 when the liquid level of the cold heat medium acquired by the liquid level acquisition device 71 is equal to or higher than a threshold value. During operation of the cold heat recovery cycle 4, the cold heat medium in the storage device 44 may become low due to, for example, leakage to the outside of the cold heat recovery cycle 4. When the liquid level of the cold heat transfer medium acquired by the liquid level acquisition device 71 falls below the threshold value, the opening/closing control device 72 instructs the valve 26 to open the refill passage 25. When the valve 26 is opened, the pressure difference between the liquefied gas supply line 2 connected to the heat transfer medium refill line 24 and the cold heat recovery cycle 4 causes liquefied gas to be sent from the liquefied gas supply line 2 to the cold heat recovery cycle 4 through the refill passage 25.

According to the above configuration, it is possible to introduce liquefied gas from the liquefied gas supply line 2 to the cold heat recovery cycle 4 as a cold heat medium through the heat medium refill line 24 connecting the liquefied gas supply line 2 and the cold heat recovery cycle 4. In this case, it is easier to refill the cold heat medium compared to when the cold heat medium is something other than liquefied gas. In addition, since there is no need to provide a separate storage facility for the cold heat medium for refilling, the cold heat recovery system 1 can be prevented from becoming large, complicated, and expensive. In addition, by using a liquefied gas with a low freezing point as the cold heat medium, the minimum temperature of the cold heat medium in the cold heat recovery cycle 4 can be lowered, and the performance of the cold heat recovery cycle 4 can be improved. By using a liquefied gas with a smaller specific volume than propane gas, etc. as the cold heat medium, the amount of circulation in the cold heat recovery cycle 4 can be reduced, and the equipment of the cold heat recovery cycle 4, such as the cold heat turbine 5, can be made smaller. This prevents the cold heat recovery system 1 from becoming large and expensive.

In some embodiments, as shown in FIG. 3, the cold heat recovery cycle 4 of the cold heat recovery system 1 includes the cold heat pump 41 described above for feeding the cold heat medium. The cold heat pump 41 is configured to pressurize at least a portion of the cold heat medium (liquefied gas) to a supercritical state. In the illustrated embodiment, the cold heat medium (liquefied gas) is in a high-pressure liquid state downstream of the first heat exchanger 12 and upstream of the cold heat pump 41 in the cold heat recovery cycle 4. At least a portion of the cold heat medium supplied to the cold heat turbine 5 is in a supercritical state by being pressurized by the cold heat pump 41.

According to the above configuration, at least a portion of the cold heat medium can be pressurized to a supercritical state by the cold heat pump 41. In this case, by bringing the cold heat medium to a supercritical state, the volume density of the cold heat medium can be increased, and the cold heat recovery cycle 4 equipment such as the cold heat turbine 5 can be made smaller. This makes it possible to prevent the cold heat recovery system 1 from becoming larger and more expensive.

The above-described heat medium replenishment line 24 can be applied to a cold heat recovery system other than the cold heat recovery system 1 shown in Fig. 3. Fig. 4 is a schematic diagram showing a configuration of a ship or a floating body equipped with a cold heat recovery system according to an embodiment of the present disclosure.
4, the cold heat recovery system 1A according to some embodiments includes the above-mentioned first heat exchanger 12, the above-mentioned third heat exchanger 15, the above-mentioned liquefied gas supply line 2, the above-mentioned vaporized gas supply line 3, the above-mentioned cold heat recovery cycle 4 including the above-mentioned cold heat turbine 5, the above-mentioned vaporized gas turbine 6, the above-mentioned external water supply line 08, and the above-mentioned external water discharge line 09, similar to the cold heat recovery system 01 according to the comparative example. The cold heat recovery system 1A further includes the above-mentioned heat medium replenishment line 24.

In some other embodiments, the cold heat recovery system 1, 1A may not include the heat medium replenishment line 24 described above, and the cold heat medium circulating through the cold heat recovery cycle 4 may be a liquefied gas (liquefied natural gas, liquefied petroleum gas, liquid hydrogen, etc.).

As shown in Figures 1, 3, and 4, the ship 10A or the floating body 10B in some embodiments is equipped with the above-mentioned cold heat recovery system 1. According to the above configuration, the output and reliability of the cold heat recovery system 1 can be improved, thereby improving the output and reliability of the ship 10A or the floating body 10B equipped with the cold heat recovery system 1.

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 (10A) or a floating body (10B) having a liquefied gas storage device (11) configured to store liquefied gas,
a first heat exchanger (12) configured to vaporize the liquefied gas;
a liquefied gas supply line (2) for supplying the liquefied gas from the liquefied gas storage device (11) to the first heat exchanger (12);
a cold heat recovery cycle (4) configured to circulate a cold heat medium that has been heat exchanged with the liquefied gas in the first heat exchanger (12), the cold heat recovery cycle (4) including a cold heat turbine (5) configured to be driven by the cold heat medium;
and a second heat exchanger (14) configured to exchange heat between the cold heat medium flowing between the cold heat turbine (5) and the first heat exchanger (12) in the cold heat recovery cycle (4) and external water introduced from outside the cold heat recovery system (1).

According to the configuration of 1) above, the second heat exchanger (14) exchanges heat between the cold heat medium flowing between the cold heat turbine (5) and the first heat exchanger (12) in the cold heat recovery cycle (4) and the external water, thereby heating the cold heat medium. The first heat exchanger (12) exchanges heat between the cold heat medium after heating in the second heat exchanger (14) and the liquefied gas, thereby heating the liquefied gas. By preheating the cold heat medium introduced to the first heat exchanger (12) in the second heat exchanger (14), the amount of heat exchange between the cold heat medium and the liquefied gas in the first heat exchanger (12) can be increased, and the cold energy recovered by the cold heat medium from the liquefied gas can be increased. This can increase the output of the cold heat turbine (5), and therefore the output of the cold heat recovery system (1).

In addition, by preheating the cold heat medium introduced into the first heat exchanger (12) in the second heat exchanger (14), the cold heat medium can be prevented from solidifying during heat exchange between the cold heat medium and the liquefied gas in the first heat exchanger (12). This prevents the cold heat medium solidified in the first heat exchanger (12) from freezing and blocking the first heat exchanger (12). This improves the reliability of the cold heat recovery system (1) when a small heat exchanger is used for the first heat exchanger (12).

2) In some embodiments, the cold heat recovery system (1) described in 1) above,
The system further includes a heat medium replenishment line (24) branching off from the liquefied gas supply line (2) and connected to the cold heat recovery cycle (4).

According to the above configuration 2), it is possible to introduce liquefied gas, which is a heat medium, from the liquefied gas supply line (2) to the cold heat recovery cycle (4) through the heat medium refill line (24) that connects the liquefied gas supply line (2) and the cold heat recovery cycle (4). In this case, it is easier to refill the cold heat medium compared to when the cold heat medium is something other than liquefied gas. In addition, since there is no need to provide a separate storage facility for the cold heat medium for refilling, the cold heat recovery system (1) can be prevented from becoming larger, more complicated, and more expensive. In addition, by using a liquefied gas with a low freezing point as the cold heat medium, the minimum temperature of the cold heat medium in the cold heat recovery cycle (4) can be lowered, thereby improving the performance of the cold heat recovery cycle (4). By using a liquefied gas with a smaller specific volume than propane gas, etc. as the cold heat medium, the amount of circulation in the cold heat recovery cycle (4) can be reduced, and the equipment of the cold heat recovery cycle (4), such as the cold heat turbine (5), can be made smaller. This helps prevent the cold heat recovery system (1) from becoming too large or expensive.

3) In some embodiments, the cold heat recovery system (1) described in 2) above,
The cold heat recovery cycle (4) includes a cold heat pump (41) for pumping the cold heat medium, the cold heat pump (41) being configured to pressurize at least a portion of the cold heat medium to a supercritical state.

According to the configuration of 3) above, at least a portion of the cold heat medium can be pressurized to a supercritical state by the cold heat pump (41). In this case, by bringing the cold heat medium to a supercritical state, the volume density of the cold heat medium can be increased, and the cold heat recovery cycle (4) equipment such as the cold heat turbine (5) can be made smaller. This makes it possible to prevent the cold heat recovery system (1) from becoming larger and more expensive.

4) In some embodiments, the cold heat recovery system (1) according to any one of 1) to 3) above,
a vaporized gas turbine (6) configured to be driven by a vaporized gas obtained by vaporizing the liquefied gas;
The vaporized gas turbine further includes a vaporized gas supply line (upstream vaporized gas supply line 3A) for supplying the vaporized gas from the first heat exchanger (12) to the vaporized gas turbine (6).

According to the configuration of 4) above, the vaporized gas is supplied from the first heat exchanger (12) to the vaporized gas turbine (6) through the vaporized gas supply line (3A). By preheating the cold heat medium guided to the first heat exchanger (12) in the second heat exchanger (14), the amount of heat exchange between the cold heat medium in the first heat exchanger (12) and the liquefied gas can be increased, and the cold energy recovered from the liquefied gas by the cold heat medium can be increased. This makes it possible to increase the temperature of the vaporized gas at the inlet of the vaporized gas turbine (6), thereby increasing the output of the vaporized gas turbine (6), and thus increasing the output of the cold energy recovery system (1). In addition, since the first heat exchanger (12) and the second heat exchanger (14) can increase the temperature of the vaporized gas at the inlet of the vaporized gas turbine (6), it is not necessary to provide a heat exchanger in the vaporized gas supply line (3A) for preheating the vaporized gas to be supplied to the vaporized gas turbine (6). In this case, there is no risk of blockage of the heat exchanger, and the reliability of the cold heat recovery system (1) can be improved.

5) In some embodiments, the cold heat recovery system (1) according to any one of 1) to 4) above,
The external water includes seawater.

According to the configuration of 5) above, the cold heat recovery system (1) is mounted on a ship (10A) or a floating body (10B), and therefore seawater is easily available. The cold heat recovery system (1) uses seawater, which is easily available, as the heat medium for the cold heat medium in the first heat exchanger (12), and therefore does not require the provision of storage facilities for storing the heat medium for the cold heat medium, thereby preventing the cold heat recovery system (1) from becoming larger, more complicated, and more expensive.

6) A ship (10A) or a floating body (10B) according to at least one embodiment of the present disclosure,
The present invention is provided with a cold heat recovery system (1) according to any one of 1) to 5) above.

According to the configuration of 6) above, the output and reliability of the cold heat recovery system (1) can be improved, thereby improving the output and reliability of the ship (10A) or floating body (10B) equipped with the cold heat recovery system (1).

Reference Signs List 1, 1A Cold energy recovery system 01 Cold energy recovery system according to a comparative example 2 Liquefied gas supply line 3 Vaporized gas supply line 3A Upstream vaporized gas supply line 3B Downstream vaporized gas supply line 4 Cold energy recovery cycle 5 Cold energy turbine 6 Vaporized gas turbine 8, 08 External water supply line 9, 09 External water discharge line 10A Ship 10B Float 11 Liquefied gas storage device 12 First heat exchanger 13 Gas supply destination 14 Second heat exchanger 15 Third heat exchanger 16 External water supply source 17, 17A to 17D External water discharge destination 20 Liquefied gas flow path 21 Gas pump 24 Heat medium replenishment line 26 Valve 30 Vaporized gas flow path 32 Vaporized gas heater 40 Cold energy flow path 41 Cold energy pump 42 Cold energy heater 44 Storage device 51, 61 Rotating shaft 52, 62 Turbine blades 53, 63 Casing 54, 64 Generator 71 Liquid height acquisition device 72 Opening and closing control device 84 External water pump

Claims (5)

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 vaporize the liquefied gas;
a liquefied gas supply line for supplying the liquefied gas from the liquefied gas storage device to the first heat exchanger;
A cold heat recovery cycle configured to circulate a cold heat medium that has been heat exchanged with the liquefied gas in the first heat exchanger, the cold heat recovery cycle including a cold heat turbine configured to be driven by the cold heat medium;
a second heat exchanger configured to exchange heat between the cold heat medium flowing between the cold heat turbine and the first heat exchanger in the cold heat recovery cycle and external water introduced from outside the cold heat recovery system ;
Further comprising a heat medium replenishment line branching from the liquefied gas supply line and connected to the cold heat recovery cycle.
Cold and heat recovery system. The cold heat recovery cycle includes a cold heat pump for feeding the cold heat medium, the cold heat pump being configured to pressurize at least a portion of the cold heat medium to a supercritical state.
The cold heat recovery system according to claim 1 . a vaporized gas turbine configured to be driven by a vaporized gas obtained by vaporizing the liquefied gas;
a vaporized gas supply line for supplying the vaporized gas from the first heat exchanger to the vaporized gas turbine.
The cold heat recovery system according to claim 1 or 2 . The external water includes seawater.
The cold heat recovery system according to any one of claims 1 to 3 . The cold heat recovery system according to any one of claims 1 to 4 is provided.
Ships or floating bodies.

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