JP2023044396A - power recovery system - Google Patents

Abstract

To provide a power recovery system that suppresses generation of cavitation in a pump part by suppressing gasification of working fluid in the pump part and normally drives a pump by suppressing suction of gas to the pump.SOLUTION: A power recovery system 1 is for recovering cold energy of liquefied gas as power via working fluid for heating the liquefied gas. The power recovery system 1 includes: a condenser 2; a gas-liquid separation tank 4; a pump 6 for cold; an evaporator 8; a turbine 10 for cold; and a first pipeline 31 for supplying the working fluid condensed by the condenser 2 to the gas-liquid separation tank 4, the first pipeline 31 configured so that an outflow port of the first pipeline 31 is located below a liquid surface of the gas-liquid separation tank 4.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a power recovery system for recovering cold energy of liquefied gas as power through a working fluid for heating the liquefied gas.

Liquefied gas (for example, liquefied natural gas) is liquefied for the purpose of transportation and storage, and when supplied to supply destinations such as city gas and thermal power generation, it is heated and vaporized by a heat medium such as seawater. . There is a power recovery system (for example, a cryogenic power generation cycle) that recovers cold energy as power instead of dumping it into sea water when liquefied gas is vaporized.

ORC (Organic Rankine Cycle) is known as a cryogenic power generation cycle of liquefied natural gas. ORC circulates in a closed loop and cools and condenses a low-temperature working fluid with a boiling point lower than that of water with liquefied natural gas in a condenser (condenser). It is a cycle process in which seawater is heated as a heat source to evaporate, and this steam is introduced into a cold-heat turbine to generate power.

In ORC, the temperature of the working fluid is lowered to the saturated vapor pressure in the condenser, but when the pressure is increased by the pump after that, the working fluid locally evaporates (gasifies) in the pump section and cavitation occurs. I have something to do. If cavitation occurs in the pump section, it may lead to damage to the pump. Also, if gas is sucked into the pump, there is a risk that the pump will not be able to operate normally.

Therefore, Patent Document 1 discloses an ORC device in which a liquid reservoir tank is installed between the condenser and the pump and a large water level head is provided between the liquid reservoir tank and the pump in order to suppress gasification in the pump section. ing. In the ORC device of Patent Document 1, the working fluid is introduced from the top (ceiling surface) of the liquid reservoir tank.

Japanese Patent No. 5608755

In order to further suppress gasification in the pump section with the technique disclosed in Patent Document 1, it is necessary to increase the capacity of the liquid reservoir tank and provide a large water level head between the liquid reservoir tank and the pump. However, since the ORC of the cryogenic power generation cycle uses a working fluid with a boiling point lower than the atmospheric temperature (for example, 25°C), the larger the capacity of the liquid reservoir tank, the larger the heat transfer area with the surrounding atmosphere. Since the working fluid stored in the pump is heated, bubbles are easily generated (gasified) in the pump section. In addition, since the temperature difference between the heated pump and the working fluid is large, the gasification is further facilitated.

In view of the circumstances described above, an object of at least one embodiment of the present disclosure is to suppress the gasification of the working fluid in the pump unit, thereby suppressing the occurrence of cavitation in the pump unit and preventing gas from being sucked into the pump. To provide a power recovery system capable of normally driving a pump by suppressing the

To achieve the above object, a power recovery system according to at least one embodiment of the present disclosure comprises:
A power recovery system for recovering cold energy of the liquefied gas as power through a working fluid for heating the liquefied gas,
a condenser configured to condense the working fluid by exchanging heat between the working fluid and the liquefied gas;
a gas-liquid separation tank configured to separate and store the working fluid condensed by the condenser into a liquid and a gas;
a cooling pump configured to increase the pressure of the liquid working fluid supplied from the gas-liquid separation tank;
an evaporator configured to evaporate the working fluid by exchanging heat between the working fluid pressurized by the cold heat pump and a heating fluid introduced from the outside of the cold heat recovery system;
a cooling turbine configured to be driven by the gaseous working fluid produced by the evaporator;
A first pipeline for supplying the working fluid condensed by the condenser to the gas-liquid separation tank, wherein an outlet of the first pipeline is positioned below the liquid surface of the gas-liquid separation tank. and a first conduit configured to locate.

According to the power recovery system of the present disclosure, by suppressing the gasification of the working fluid in the pump section, the occurrence of cavitation in the pump section is suppressed, and the suction of gas into the pump is suppressed to operate the pump normally. A power recovery system can be provided that can be driven.

1 is a schematic configuration diagram schematically showing the overall configuration of a power recovery system according to an embodiment of the present disclosure; FIG. 1 is a schematic configuration diagram schematically showing the overall configuration of a power recovery system according to an embodiment of the present disclosure; FIG. 1 is a schematic configuration diagram schematically showing the overall configuration of a power recovery system according to an embodiment of the present disclosure; FIG. 1 is a schematic configuration diagram schematically showing the overall configuration of a power recovery system according to an embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of a gas-liquid separation tank according to an embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of a gas-liquid separation tank according to an embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of a gas-liquid separation tank according to an embodiment of the present disclosure; FIG. 1 is a schematic cross-sectional view of a gas-liquid separation tank according to an embodiment of the present disclosure; FIG. 1 is a schematic diagram illustrating an example of a power recovery system installed on a floating structure on water according to an embodiment of the present disclosure; FIG. 1 is a schematic diagram showing an example of a case where a power recovery system according to an embodiment of the present disclosure is installed at a land-use liquefied gas terminal; FIG.

Several embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as the embodiment or shown in the drawings are not meant to limit the scope of the present disclosure, but are merely illustrative examples. do not have.
For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. The shape including the part etc. shall also be represented.
On the other hand, the expressions "comprising", "including", or "having" one component are not exclusive expressions excluding the presence of other components.
In addition, the same code|symbol may be attached|subjected about the same structure and description may be abbreviate|omitted.

(Application example of power recovery system)
FIG. 6A is a schematic diagram illustrating an example of a power recovery system 1 according to an embodiment of the present disclosure installed on a floating structure 101 on water.
A power recovery system 1 according to an embodiment of the present disclosure is installed on a floating structure 101 on water, as shown in FIG. 6A. The water floating structure 101 is a structure that can float on water. The water floating structure 101 includes a propulsion device configured to drive a propulsion device such as a propeller, and includes a ship capable of self-propelled by driving the propulsion device and a floating body without a propulsion device. . In the floating structure 101 on water, liquefied gas is stored, and the liquefied gas is heated with seawater or the like to be vaporized, and flowed into the engine 111 to obtain propulsion. When the liquefied gas is vaporized, the power recovery system 1 recovers cold energy as electric power instead of throwing it away in seawater.

FIG. 6B is a schematic diagram showing an example in which the power recovery system 1 according to an embodiment of the present disclosure is installed at a land-use liquefied gas terminal 102. As shown in FIG.
A power recovery system 1 according to an embodiment of the present disclosure is installed at a land-based LNG (liquefied gas) terminal 102, as shown in FIG. 6B. A land-based LNG (liquefied gas) terminal 102 receives and stores liquefied gas transported by LNG carriers. Then, when the liquefied gas is supplied to a liquefied gas supply destination 112 such as city gas or a thermal power plant, the liquefied gas is heated with seawater or the like to return to gas. When the liquefied gas is vaporized, the power recovery system 1 recovers cold energy as electric power instead of throwing it away in seawater.

Here, the power recovery system 1 of the present disclosure has been described by taking liquefied natural gas (LNG) as a specific example of the above-described liquefied gas, but the present disclosure applies to liquefied gas other than liquefied natural gas (liquefied petroleum gas, liquid hydrogen, etc.).

(Overall Configuration of Power Recovery System 1)
1 to 4 are schematic configuration diagrams that schematically show the overall configuration of a power recovery system 1 according to an embodiment of the present disclosure.

A power recovery system 1 according to an embodiment of the present disclosure is a system for recovering cold energy of liquefied gas as power through a working fluid for heating the liquefied gas. As shown in FIGS. 1 to 4, the power recovery system 1 according to one embodiment of the present disclosure includes a condenser 2, a gas-liquid separation tank 4, a cooling pump 6, an evaporator 8, and a cooling turbine. 10 and. The condenser 2 , the gas-liquid separation tank 4 , the cooling pump 6 , the evaporator 8 , and the cooling turbine 10 are connected by a circulation flow path 3 . The power recovery system 1 is driven by the working fluid circulating in the circulation flow path 3 while changing its state to liquid or gas.

The condenser 2 is configured to condense the working fluid through heat exchange between the working fluid and the liquefied gas. Inside the condenser 2, there are provided a heating-side pipeline 21 into which the working fluid circulating in the circulation flow path 3 flows, and a heated-side pipeline 22 into which the liquefied gas introduced from the outside of the power recovery system 1 flows. and configured for heat exchange between the working fluid and the liquefied gas. In the condenser 2, the working fluid is cooled and condensed by heat exchange, and the liquefied gas is heated.

The circulation flow path 3 includes a first pipeline 31 connecting the condenser 2 and the gas-liquid separation tank 4, a second pipeline 32 connecting the gas-liquid separation tank 4 and the cooling pump 6, and a cooling pump. 6 and the evaporator 8; a fourth pipe 34 connecting the evaporator 8 and the cooling turbine 10; and a fifth pipe connecting the cooling turbine 10 and the condenser 2. a path 35; The working fluid circulates in the circulation passage 3 while changing its state to liquid or gas, and drives the power recovery system 1 .
In the following description, "upstream side" means the upstream side in the direction of flow of the working fluid flowing through the circulation channel 3, and "downstream side" means the direction of flow of the working fluid flowing through the circulation channel 3. means the downstream side of

The first pipe line 31 is arranged downstream of the condenser 2 and upstream of the gas-liquid separation tank 4 and connects the condenser 2 and the gas-liquid separation tank 4 . The upstream end of the first pipeline 31 is connected to the downstream end of the heating-side pipeline 21 of the condenser 2 . The downstream side of the first pipeline 31 is connected to the gas-liquid separation tank 4 . The liquid working fluid condensed by the condenser 2 flows through the first pipeline 31 and is supplied to the gas-liquid separation tank 4 .

The gas-liquid separation tank 4 is configured to separate the working fluid condensed by the condenser 2 into a liquid and a gas and store them. Inside the gas-liquid separation tank 4, a gas phase portion 42 composed of a gaseous working fluid is formed above the liquid surface 41 with a liquid surface 41 as a boundary, and a liquid phase portion 42 composed of a liquid working fluid is formed below the gas phase portion 42. A phase portion 43 is formed.

Further, the gas-liquid separation tank 4 is installed so that the ceiling surface 44 of the gas-liquid separation tank 4 is positioned below the condenser 2 in the vertical direction. In other words, the upstream end of the first pipeline 31 is positioned vertically above the downstream end of the first pipeline 31, and the working fluid flows through the first pipeline 31 by natural flow. is configured to

In the illustrated embodiment, the gas-liquid separation tank 4 has a cylindrical shape. However, the shape of the gas-liquid separation tank 4 is not particularly limited as long as it can separate and store the working fluid into liquid and gas. The shape of the gas-liquid separation tank 4 can be appropriately selected according to the embodiment, for example, a cylindrical shape, a spherical shape, a rectangular parallelepiped shape, or the like. When the gas-liquid separation tank 4 has a spherical shape, the ceiling surface 44 described above corresponds to the highest portion of the sphere, and the bottom surface 45 described later corresponds to the lowest portion of the sphere.

The temperature of the gas phase portion 42 of the gas-liquid separation tank 4 is equal to or higher than the saturated vapor temperature, and is slightly higher than the saturated vapor temperature due to external influence. The temperature of the liquid phase portion 43 of the gas-liquid separation tank 4 is affected by the gas phase portion 42 having a temperature equal to or higher than the saturated vapor temperature at the liquid surface 41. It has a temperature gradient such that the temperature becomes lower toward it.

The second pipe line 32 is arranged downstream of the gas-liquid separation tank 4 and upstream of the cooling pump 6 , and connects the gas-liquid separation tank 4 and the cooling pump 6 . The upstream end of the second pipe 32 is located in the liquid phase portion 43 of the gas-liquid separation tank 4 and is open so that the liquid working fluid can flow into the second pipe 32 . there is A downstream end of the second pipe line 32 is connected to a suction port of the cold pump 6 . The liquid working fluid stored in the liquid phase portion 43 of the gas-liquid separation tank 4 flows through the second pipe line 32 and is supplied to the cold/heat pump 6 .

The cold/heat pump 6 is configured to pressurize the liquid working fluid supplied from the gas-liquid separation tank 4 . The liquid working fluid that has flowed in from the suction port is pressurized by a pressurizing section (for example, an impeller) of the cooling pump 6 and flows out from the discharge port.
Also, the cooling pump 6 is installed below the bottom surface 45 of the gas-liquid separation tank 4 in the vertical direction. In other words, the upstream end of the second pipeline 32 is located vertically above the downstream end of the second pipeline 32 , and the working fluid flows between the liquid surface 41 and the suction port of the cooling/heating pump 6 . and the suction force of the cooling/heating pump 6, the air flows through the second pipe line 32. As shown in FIG.

The cooling pump 6 is not particularly limited as long as it can pressurize the working fluid. For example, a turbo pump (centrifugal pump, mixed flow pump, axial flow pump, etc.) or positive displacement pump (reciprocating pump, rotary pump) can be appropriately selected according to the embodiment.

The third pipe line 33 is arranged downstream of the cooling pump 6 and upstream of the evaporator 8 and connects the cooling pump 6 and the evaporator 8 . The upstream end of the third pipe line 33 is connected to the discharge port of the cold/heat pump. A downstream end of the third pipeline 33 is connected to an upstream end of a heated pipeline 81 of the evaporator 8 . The liquid working fluid pressurized by the cooling pump 6 flows through the third pipe 33 and is supplied to the evaporator 8 .

The evaporator 8 is configured to evaporate the working fluid by exchanging heat between the working fluid pressurized by the cold/heat pump 6 and the heating fluid introduced from the outside of the power recovery system 1 . Inside the evaporator 8, there are a heated side pipeline 81 into which the working fluid pressurized by the cooling pump 6 flows, and a heating side pipeline 82 into which the heating fluid introduced from the outside of the power recovery system 1 flows. and is configured for heat exchange between the working fluid and the heating fluid. In the evaporator 8, the working fluid is heated and evaporated by heat exchange, and the heated fluid is cooled.

Note that the above-mentioned heated fluid may be any medium having a higher temperature than the working fluid pressurized by the cold/heat pump 6, such as steam, hot water, seawater, or engine cooling water introduced from the outside of the power recovery system 1. . In this embodiment, the cooling water of the engine 111 of the floating structure 101 described above is used as the heating fluid. Since the cooling water for the engine 111 has a higher temperature than seawater or the like, the heat exchange efficiency in the evaporator 8 can be increased compared to the case where seawater or the like is used as the heating fluid.

The fourth pipeline 34 is arranged downstream of the evaporator 8 and upstream of the cold turbine 10 and connects the evaporator 8 and the cold turbine 10 . The upstream end of the fourth pipeline 34 is connected to the downstream end of the heated pipeline 81 of the evaporator 8 . A downstream end of the fourth pipe 34 is connected to an inlet of the cold turbine 10 . The gaseous working fluid heat-exchanged and heated in the evaporator 8 flows through the fourth pipeline 34 and is supplied to the cold/heat turbine 10 .

The cold turbine 10 is configured to be driven by the gaseous working fluid produced by the evaporator 8 . The cold turbine 10 has, for example, a rotating shaft and an impeller composed of at least one moving blade provided on the rotating shaft. is configured to

A generator 12 is connected to the rotary shaft of the cold turbine 10 . The generator 12 is configured to generate power using the driving force of the cold turbine 10 as a driving source.
That is, the power recovery system 1 includes the cold turbine 10 and the generator 12, so that the cold energy of the liquefied gas can be recovered as power (electric power).

The fifth pipeline 35 is arranged downstream of the cold turbine 10 and upstream of the condenser 2 , and connects the cold turbine 10 and the condenser 2 . The upstream end of the fifth pipeline 35 is connected to the outflow of the cold turbine 10 . A downstream end of the fifth pipeline 35 is connected to an upstream end of the heating-side pipeline 21 of the condenser 2 . The gaseous working fluid that has driven the cold turbine 10 flows through the fifth pipe 35 and is supplied to the condenser 2 .

(Position of outflow port 311 of first pipeline 31)
5A-5D are schematic cross-sectional views of a gas-liquid separation tank 4 according to one embodiment of the present disclosure.
In the power recovery system 1 according to one embodiment of the present disclosure, as shown in FIGS. is configured to

Since the outflow port 311 of the first pipe 31 is located below the liquid surface 41 of the gas-liquid separation tank 4, the working fluid condensed by the condenser 2 is not in the gas phase portion 42 but in the liquid It will be supplied directly to the phase section 43 . Therefore, when the outflow port 311 of the first pipe line 31 is positioned above the liquid surface 41 of the gas-liquid separation tank 4, that is, when the working fluid condensed by the condenser 2 passes through the gas phase portion 42, Since the working fluid is not warmed in the gas phase portion 42 as compared with the case where the working fluid is supplied to the liquid phase portion 43 by heating, the working fluid can be supplied to the liquid phase portion 43 in a low temperature state. Also, when the liquid working fluid is supplied from the gas-liquid separation tank 4 to the cooling pump 6, it can be supplied in a low temperature state. can be suppressed. As a result, it is possible to suppress the occurrence of cavitation in the pump portion of the cold pump 6 and to suppress gas from being sucked into the cold pump 6 so that the cold pump 6 can be driven normally.

In one embodiment, as shown in FIGS. 5A to 5D, the outlet 311 of the first pipe line 31 is configured to be positioned below the middle of the gas-liquid separation tank 4 in the vertical direction. good.

Generally, the liquid level 41 of the gas-liquid separation tank 4 is located above the intermediate position (50% position). Therefore, according to such a configuration, the working fluid condensed by the condenser 2 is provided not in the gas phase portion 42 of the gas-liquid separation tank 4 but in the liquid phase portion 43 of the gas-liquid separation tank 4. The working fluid is directly supplied to the gas-liquid separation tank 4 from the outflow port 311 of the first pipeline 31 .

In one embodiment, as described above, the second pipe line 32 is further provided to supply the liquid working fluid stored in the gas-liquid separation tank 4 to the cold/heat pump 6 . 5A to 5D, in the vertical direction of the gas-liquid separation tank 4, when the position of the bottom surface 45 is defined as the 0% position and the position of the ceiling surface 44 is defined as the 100% position, the first pipe Outlet 311 of channel 31 and inlet 321 of second conduit 32 are located in the range of 0% to 25%.

According to such a configuration, the outlet 311 of the first pipe 31 and the inlet 321 of the second pipe 32 are in the range of 0% to 25% in the vertical direction of the gas-liquid separation tank 4 (that is, the bottom surface 45 side). Therefore, the working fluid that has flowed out from the outlet 311 of the first pipe line 31 to the liquid phase portion 43 is maintained at a low temperature without being warmed in the vertically upper liquid phase portion 43 where the temperature of the working fluid is high. As it is, it flows into the inflow port 321 of the second pipe line 32 and is supplied to the cold/heat pump 6 . As a result, gasification of the working fluid in the pump portion of the cold/heat pump 6 can be suppressed.

In one embodiment, the first pipeline 31 and the second pipeline 32 are inserted through the gas-liquid separation tank 4 from the bottom surface 45 as shown in FIG. 5A. The first pipeline 31 and the second pipeline 32 extend vertically upward from the bottom surface 45 through the liquid phase portion 43 below the liquid surface 41 .

In one embodiment, the first pipeline 31 and the second pipeline 32 are inserted through the gas-liquid separation tank 4 from the side 46 as shown in FIG. 5B. The first pipeline 31 and the second pipeline 32 extend in the liquid phase portion 43 below the liquid surface 41 in the horizontal direction from the side surface 46 .

In some embodiments, as shown in FIGS. 5C and 5D , the first pipe line 31 is inserted into the gas-liquid separation tank 4 from above the liquid level 41 of the gas-liquid separation tank 4 and is 41 includes an internal conduit 31B extending downwardly. The outflow port 311 described above is formed at the downstream end of the internal pipe line 31B.

According to such a configuration, since the first pipe line 31 is inserted into the gas-liquid separation tank 4 from above the liquid surface 41 of the gas-liquid separation tank 4 , the gas-liquid separation tank 4 is inserted from below the liquid surface 41 . The distance that the first pipe 31 is exposed to the air having a temperature higher than that of the working fluid condensed by the condenser 2 is reduced as compared with the case where the first pipe 31 is inserted through the first pipe 31 . Therefore, outside the gas-liquid separation tank 4, the working fluid in the first pipe line 31 can be prevented from being heated by heat input from the outside.

In one embodiment, as shown in FIG. 5C, the first conduit 31 is arranged inside the gas-liquid separation tank 4 with an external conduit 31A arranged outside the gas-liquid separation tank 4. and an internal conduit 31B. The first pipe line 31 is inserted through the gas-liquid separation tank 4 from the ceiling surface 44 . The internal conduit 31B extends vertically downward from the ceiling surface 44 to the liquid phase portion 43 below the liquid surface 41 .

In one embodiment, as shown in FIG. 5D, the first conduit 31 is arranged inside the gas-liquid separation tank 4 with an external conduit 31A arranged outside the gas-liquid separation tank 4. and an internal conduit 31B. The first pipe line 31 is inserted through the gas-liquid separation tank 4 from the side surface 46 of the gas-liquid separation tank 4 . The internal pipeline 31B includes an internal horizontal pipeline 31B1 extending horizontally from the side surface 46 and a liquid phase below the liquid surface 41 extending vertically downward from the downstream end of the internal horizontal pipeline 31B1. It has an internal vertical conduit 31 B 2 that extends to the portion 43 .

In one embodiment, as shown in FIGS. 5A to 5D, in the vertical direction of the gas-liquid separation tank 4, the outlet 311 of the first conduit 31 is positioned above the inlet 321 of the second conduit 32. positioned.
According to such a configuration, even if bubbles are contained in the working fluid flowing through the first conduit 31 , the bubbles flowing out from the outlet 311 flow into the inlet 321 of the second conduit 32 . can be suppressed.

In some embodiments, the working fluids described above include fluids with boiling points below 0°C.

According to such a configuration, the power recovery system 1 can be operated by using a fluid with a boiling point of less than 0° C. as the working fluid. This working fluid includes, for example, propane, but it is also applicable when working fluid other than propane is used as the working fluid flowing through the circulation flow path 3 .

(Recirculation line 5)
In one embodiment, as shown in FIG. 2, the power recovery system 1 is branched from between the cooling pump 6 and the evaporator 8, and the working fluid pressurized by the cooling pump 6 is transferred to the gas-liquid separation tank 4. A recirculation line 5 is further provided for refluxing. As shown in FIGS. 5A and 5B, the outlet 51 of the recirculation pipe 5 is positioned below the liquid surface 41 of the gas-liquid separation tank 4 .

According to such a configuration, since the outlet 51 of the recirculation pipe 5 is located below the liquid surface 41 of the gas-liquid separation tank 4, the working fluid condensed by the condenser 2 is in the gas phase. It is supplied directly to the liquid phase portion 43 instead of to the portion 42 . Therefore, the working fluid that has flowed out from the outlet 51 of the recirculation pipe 5 to the liquid phase portion 43 is maintained at a low temperature without being warmed in the vertically upper gas phase portion 42 where the temperature of the working fluid is high. As it is, it flows into the inflow port 321 of the second pipe line 32 and is supplied to the cold/heat pump 6 . As a result, gasification of the working fluid in the pump portion of the cold/heat pump 6 can be suppressed.

In the embodiment shown in FIG. 2, the upstream end of the recirculation line 5 is connected to a third line 33 connecting the cold pump 6 and the evaporator 8 . Further, a valve 5V is provided on the downstream side of the upstream end of the recirculation pipe 5, and is configured to open and close the recirculation pipe 5. As shown in FIG. Further, the third pipeline 33 is provided with a valve 33V on the downstream side of the connection position with the upstream end of the recirculation pipeline 5, so that the third pipeline 33 can be opened and closed. .

When the cold pump 6 is started, the valve 33V is closed and the valve 5V is opened. As a result, the liquid working fluid stored in the gas-liquid separation tank 4 flows through the second pipeline 32 , is sucked into the cooling pump 6 , is pressurized, and is discharged to the third pipeline 33 . Then, it flows through the recirculation line 5 and is returned to the gas-liquid separation tank 4 again. In this manner, the liquid working fluid circulates between the gas-liquid separation tank 4 and the cooling pump 6 when the cooling pump 6 is activated.

After the cold pump 6 is started, when it reaches a predetermined operating state (during operation), the valve 33V is opened and the valve 5V is closed. As a result, the working fluid pressurized by the cold/heat pump 6 circulates through the circulation passage 3 without flowing through the recirculation pipe 5 .

In one embodiment, as described above, the outlet 51 of the recirculation pipe 5 is positioned in the liquid phase portion 43 below the liquid surface 41 of the gas-liquid separation tank 4 . Then, in the vertical direction of the gas-liquid separation tank 4, when the position of the bottom surface 45 is defined as the 0% position and the position of the ceiling surface 44 is defined as the 100% position, the outlet 51 of the recirculation pipe 5 is 0% to It should be located in the range of 25%.

According to such a configuration, the working fluid flowing out from the outlet 51 of the recirculation pipe 5 to the liquid phase portion 43 is not warmed in the vertically upper liquid phase portion 43 where the temperature of the working fluid becomes high. It flows into the inlet 321 of the second pipe line 32 and is supplied to the cooling/heating pump 6 while being maintained in a low temperature state. As a result, gasification of the working fluid in the pump portion of the cold/heat pump 6 can be suppressed.

In one embodiment, as shown in FIGS. 5A and 5B , the outlet 51 of the recirculation conduit 5 is positioned above the inlet 321 of the second conduit 32 in the vertical direction of the gas-liquid separation tank 4 . positioned.
According to such a configuration, even if bubbles are contained in the working fluid flowing through the recirculation conduit 5 , the bubbles flowing out from the outlet 51 flow into the inlet 321 of the second conduit 32 . can be suppressed.

In one embodiment, the recirculation line 5 passes through the gas-liquid separation tank 4 from the bottom surface 45, as shown in FIG. 5A. The recirculation line 5 extends vertically upward through the liquid phase 43 below the liquid surface 41 from the bottom surface 45 .

In one embodiment, the recirculation line 5 passes through the gas-liquid separation tank 4 from the side 46, as shown in FIG. 5B. The recirculation line 5 extends horizontally from the side 46 through the liquid phase 43 below the liquid level 41 .

In one embodiment, the outlet 51 of the recirculation line 5 is further from the inlet 321 of the second line 31 than the outlet 311 of the first line 31, as shown in FIGS. 5A, 5B. is located. That is, the outlet 311 of the first conduit 31 is located closer to the inlet 321 of the second conduit 31 than the outlet 51 of the recirculation conduit 5 is.
With such a configuration, the working fluid can be rapidly guided from the outlet 311 of the first conduit 31 to the inlet 321 of the second conduit 31 .

(First sub-pipeline 7)
In one embodiment, as shown in FIGS. 3 and 4, the power recovery system 1 comprises a first sub-line 7 for supplying the working fluid condensed by the condenser 2 to the gas-liquid separation tank 4. ing. 5A and 5B, the outflow port 71 of the first sub-pipe 7 is configured to be positioned above the liquid surface 41 of the gas-liquid separation tank 4. As shown in FIGS.

According to such a configuration, the gas phase portion 42 above the liquid level 41 of the gas-liquid separation tank 4 is located above the liquid level 41 of the gas-liquid separation tank 4 . is provided, the working fluid flowing in from the first sub-pipe 7 is directly supplied to the gas phase portion 42 . Therefore, the temperature of the gas phase portion 42 above the liquid surface 41 of the gas-liquid separation tank 4 is lowered, and a low saturated vapor pressure can be obtained. When the pressure (saturated vapor pressure) of the gas phase portion 42 above the liquid level 41 of the gas-liquid separation tank 4 is lowered, the pressure at the outlet of the cryogenic turbine 10 is also lowered, so the turbine efficiency can be improved. .

In one embodiment, as shown in FIGS. 3 and 4, the upstream end of the first secondary line 7 is connected to the first line 31 connecting the condenser 2 and the gas-liquid separation tank 4. . The downstream side of the first sub-pipe line 7 is connected to the gas-liquid separation tank 4 from above the gas-liquid separation tank 4 in the vertical direction (above the liquid surface 41). 5A and 5B, the outflow port 71 of the first sub-pipe line 7 is positioned in the gas phase portion 42 above the liquid surface 41 of the gas-liquid separation tank 4. As shown in FIGS.

Moreover, in one embodiment, as shown in FIG. 5A, the first sub-pipe line 7 is inserted through the gas-liquid separation tank 4 from the ceiling surface 44 . The first sub-pipe line 7 extends downward in the vertical direction from the ceiling surface 44 through the gas phase portion 42 above the liquid surface 41 .

In one embodiment, as shown in FIG. 5B, the first secondary line 7 is inserted through the gas-liquid separation tank 4 from the side 46 . The first sub-pipe 7 extends horizontally from the side surface 46 through the gas phase portion 43 above the liquid surface 41 .

(control device 9, first valve 31V, second valve 7V)
In one embodiment, as shown in FIGS. 3 and 4, the power recovery system 1 includes a first valve 31V capable of adjusting the flow rate of the working fluid flowing through the first conduit 31, and a first secondary conduit 7. It includes a second valve 7V capable of adjusting the flow rate of the flowing working fluid, and a control device 9 capable of controlling the opening degrees of each of the first valve 31V and the second valve 7V. The control device 9 controls the temperature T1 of the gas phase portion 42 above the liquid surface 41 of the gas-liquid separation tank 4 and the liquid working fluid flowing out of the gas-liquid separation tank 4 and before being sucked into the cooling pump 6. The valve opening degrees of the first valve 31V and the second valve 7V are adjusted so that the difference ΔT from the liquid temperature T2 is larger than the first threshold and smaller than the second threshold, which is larger than the first threshold. configured to control.

According to such a configuration, the difference ΔT is controlled between the first threshold and the second threshold. When the difference ΔT is smaller than the first threshold value, the temperature difference between the liquid temperature T2 and the temperature T1 of the gas phase portion 42, which is the saturation temperature, becomes small. Gasification is facilitated at the time of inflow or even a slight heating at the pump portion of the cooling/heating pump 6 . On the other hand, when the difference ΔT is larger than the second threshold, the temperature T1 of the gas phase portion 42 is high, the gas phase portion 42 has a high saturated steam pressure, and the turbine efficiency of the cold turbine 10 may decrease. be. Therefore, by using the difference ΔT as a control parameter and performing control by setting the first threshold value and the second threshold value for the difference ΔT, it is possible to increase the turbine efficiency without causing gasification of the working fluid.

The second valve 7V is provided in the first sub-pipeline 7 and can control the flow rate of the working fluid flowing through the first sub-pipeline 7 . In addition, the first valve 31V is provided in the first pipe 31 downstream of the connection position with the upstream end of the first sub-pipe 7, and the flow rate of the working fluid flowing through the first pipe 31 is can be controlled. Also, the first valve 31V and the second valve 7V are connected to an actuator (such as a motor) so that the valve opening can be automatically adjusted.

When the temperature T1 rises, the gas phase portion 42 has a high saturated steam pressure, and the pressure at the outlet of the cold/heat turbine 10 rises, which may reduce the turbine efficiency. Further, when the liquid temperature T2 rises, the temperature of the working fluid supplied to the cooling pump 6 rises, so there is a possibility that the working fluid is likely to gasify in the pump portion of the cooling pump 6 .

In order to lower the temperature T1, the second valve 7V is opened and the first valve 31V is closed so that more of the liquid working fluid condensed by the condenser 2 flows through the first sub-pipe 7. Adjust the direction. As a result, the amount of working fluid supplied from the outflow port 71 of the first sub-pipe line 7 to the gas phase portion 42 of the gas-liquid separation tank 4 increases, so that the temperature T1 can be lowered.
However, by adjusting the second valve 7V in the opening direction and the first valve 31V in the closing direction, the amount of working fluid flowing through the first pipe 31 is reduced. As a result, the working fluid is less likely to be supplied from the outflow port 311 of the first pipe line 31 to the liquid phase portion 43 of the gas-liquid separation tank 4, and the liquid temperature T2 of the liquid phase portion 43 of the gas-liquid separation tank 4 rises. .

On the other hand, in order to lower the liquid temperature T2, the second valve 7V is closed and the first valve 31V should be adjusted in the valve opening direction. As a result, the amount of working fluid supplied to the liquid phase portion 43 from the outlet 311 of the first conduit 31 is increased, so that the liquid temperature T2 can be lowered.
However, by adjusting the second valve 7V in the closing direction and the first valve 31V in the opening direction, the amount of working fluid flowing through the first sub-line 7 is reduced. As a result, the working fluid is less likely to be supplied from the outflow port 71 of the first sub-pipe line 7 to the gas phase portion 42 of the gas-liquid separation tank 4, and the temperature T1 of the gas phase portion 42 of the gas-liquid separation tank 4 rises. .

That is, the temperature T1 and the liquid temperature T2 are in a trade-off relationship such that when the temperature T1 is lowered, the liquid temperature T2 rises, and when the liquid temperature T2 is lowered, the temperature T1 rises. Therefore, a first threshold value and a second threshold value are provided for the difference ΔT between the temperature T1 and the liquid temperature T2.

When the temperature T1 rises, the temperature difference between the temperature T1 and the liquid temperature T2 increases, so the difference ΔT increases. Then, the second valve 7V is adjusted in the closing direction and the first valve 31V is adjusted in the opening direction so that the difference ΔT does not exceed the second threshold value. Thereby, the temperature T1 can be lowered, the difference ΔT can be reduced, and the difference ΔT can be maintained to be smaller than the second threshold.

Further, when the liquid temperature T2 rises, the difference ΔT becomes smaller because the temperature difference between the temperature T1 and the liquid temperature T2 becomes smaller. Then, the second valve 7V is adjusted in the closing direction and the first valve 31V is adjusted in the opening direction so that the difference ΔT does not become smaller than the first threshold value. As a result, the liquid temperature T2 can be lowered, the difference ΔT can be increased, and the difference ΔT can be maintained larger than the first threshold value.

The control device 9 is an electronic control unit for controlling the valve opening degrees of the first valve 31V and the second valve 7V, and includes a CPU (processor) (not shown), memories such as ROM and RAM, and storage devices such as external storage devices. , an I/O interface, a communication interface, and the like. Then, for example, the CPU operates (for example, calculates data) according to the instructions of the program loaded in the main storage device of the memory, thereby realizing valve opening degree control of the first valve 31V and the second valve 7V, which will be described later. may

In one embodiment, as shown in FIG. 4, a first sensor 131 is installed in the gas phase section 42 of the gas-liquid separation tank 4 so as to measure and transmit the temperature T1 to the controller 9 . The second sensor 132 is installed in the vicinity of the cooling/heating pump 6 in the second pipe line 32 so as to measure the liquid temperature T2 and transmit it to the control device 9 . The first sensor 131 and the second sensor 132 continuously transmit the measured temperature T1 and liquid temperature T2 to the control device 9 as signals through a wired or wireless communication line.

The control device 9 performs feedback control so that the difference ΔT between the temperature T1 and the liquid temperature T2 is larger than the first threshold and smaller than the second threshold. Specifically, the control device 9 calculates the valve opening degrees of the first valve 31V and the second valve 7V such that the difference ΔT is larger than the first threshold value and smaller than the second threshold value. Then, the command signal is output to the first valve 31V and the second valve 7V. The first valve 31V and the second valve 7V adjust valve opening based on the input command signal. By repeating this series of controls at predetermined time intervals, the difference ΔT is maintained at a value larger than the first threshold and smaller than the second threshold.

(Second recirculation line 15)
In one embodiment, as shown in FIG. 2, the power recovery system 1 includes a second recirculation line that branches off from the recirculation line 5 and returns the working fluid pressurized by the cold pump 6 to the condenser 2. 15, the first recirculation valve 16V capable of adjusting the flow rate of the working fluid flowing through the second recirculation line 15, and the recirculation line 5 downstream of the branch position of the second recirculation line 15. It further includes a second recirculation valve 17V capable of adjusting the flow rate of the flowing working fluid, and a controller 9 capable of controlling the valve opening degrees of each of the first recirculation valve 16V and the second recirculation valve 17V.

Then, when the liquid temperature of the working fluid pressurized by the cooling pump 6 is below a predetermined temperature (third threshold), the control device 9 removes the working fluid pressurized by the cooling pump 6 from the gas-liquid separation tank 4 to the gas-liquid separation tank 4 . and when the liquid temperature of the working fluid pressurized by the cooling pump 6 exceeds a predetermined temperature (third threshold), the working fluid pressurized by the cooling pump 6 is returned to the condenser 2. Thus, it is configured to control the respective valve opening degrees of the first recirculation valve 16V and the second recirculation valve 17V.

When the temperature of the working fluid rises to a predetermined temperature or higher due to the heat input from the cooling pump 6, the working fluid whose temperature has risen is returned to the gas-liquid separation tank 4, whereupon it is stored in the gas-liquid separation tank 4. There is a possibility that the temperature of the working fluid is increased. Therefore, according to such a configuration, when the temperature of the working fluid rises to a predetermined temperature (third threshold value) or higher due to heat input from the cooling pump 6, the working fluid is returned to the condenser 2, By supplying the working fluid to the gas-liquid separation tank 4 after the temperature is lowered by the condenser, it is possible to suppress the temperature rise of the working fluid stored in the gas-liquid separation tank 4 .

In the embodiment shown in FIG. 2, the first return valve 16V is provided in the second recirculation line 15 and can control the flow rate of working fluid flowing through the second recirculation line 15 . In addition, the second recirculation valve 17V is provided downstream of the branching position of the recirculation pipe 5 with the second recirculation pipe 15, and the gas flows through the recirculation pipe 5 downstream of the branching position. The flow rate of working fluid can be controlled. Also, the first recirculation valve 16V and the second recirculation valve 17V are connected to an actuator (such as a motor) so as to automatically adjust the valve opening. In addition, the temperature of the working fluid flowing through the recirculation pipe 5 (liquid pressure of the working fluid pressurized by the cooling/heating pump 6 A third sensor 133 capable of measuring temperature) is installed. The third sensor 133 continuously transmits the temperature of the working fluid measured to the control device 9 as a signal through a wired or wireless communication line.

(Gas vent pipe 11)
In one embodiment, as shown in FIG. 4 , the power recovery system 1 includes a gas vent pipe 11 branched from the first pipe line 31 to remove gaseous working fluid that has not been condensed in the condenser 2. A gas vent pipe 11 for discharging to the outside of the first pipeline 31 is further provided.

According to such a configuration, when the working fluid is not sufficiently liquefied in the condenser 2, the first pipeline 31 is provided with the gas vent pipe 11, so that the gas in the first pipeline 31 is discharged to the outside. can be discharged. Therefore, it is possible to suppress the inflow of gas into the liquid phase portion 43 located below the liquid surface 41 of the gas-liquid separation tank 4 and the intake of gas into the cold/heat pump 6 portion.

In the embodiment shown in FIG. 4, the gas vent pipe 11 branches off from the first pipeline 31 and extends upward in the vertical direction. The downstream end of the gas vent pipe 11 is located above the liquid surface 41 of the gas-liquid separation tank 4 in the vertical direction.

Moreover, in the embodiment shown in FIG. 4 , the downstream end of the gas vent pipe 11 is connected to the exhaust gas pipeline 14 . The exhaust gas line 14 connects the gas vent pipe 11 and the gas-liquid separation tank 4 . The downstream side of the exhaust gas pipe 14 is connected to the gas-liquid separation tank 4 from above the liquid surface 41 of the gas-liquid separation tank 4 in the vertical direction, as shown in FIGS. 5A and 5B. Further, the outflow port 141 of the exhaust gas pipe line 14 is provided so as to be positioned in the gas phase portion 42 above the liquid surface 41 of the gas-liquid separation tank 4 . According to such a configuration, the gaseous working fluid discharged to the outside of the first conduit 31 can be circulated within the power recovery system 1 without being discharged to the outside of the power recovery system 1 . Therefore, loss of the working fluid circulating in the power recovery system 1 can be suppressed.

Further, in one embodiment, as shown in FIG. 5A, the exhaust gas pipeline 14 is inserted through the gas-liquid separation tank 4 from the ceiling surface 44 . The exhaust gas pipe 14 extends downward in the vertical direction from the ceiling surface 44 through the gas phase portion 42 above the liquid surface 41 .

In one embodiment, as shown in FIG. 5B, exhaust gas line 14 passes through gas-liquid separation tank 4 from side 46 . The exhaust gas pipe 14 extends horizontally from the side surface 46 through the gas phase portion 43 above the liquid surface 41 .

The present disclosure is not limited to the above-described embodiments, and includes modifications of the above-described embodiments and modes in which these modes are combined as appropriate.

The contents described in the several embodiments described above are understood as follows, for example.

1) A power recovery system (1) according to one aspect includes:
A power recovery system (1) for recovering cold energy of the liquefied gas as power through a working fluid for heating the liquefied gas,
a condenser (2) configured to condense the working fluid by exchanging heat between the working fluid and the liquefied gas;
a gas-liquid separation tank (4) configured to separate and store the working fluid condensed in the condenser (2) into a liquid and a gas;
a cooling pump (6) configured to pressurize the liquid working fluid supplied from the gas-liquid separation tank (4);
An evaporator (8) configured to evaporate the working fluid by exchanging heat between the working fluid pressurized by the cooling pump (6) and heating fluid introduced from the outside of the power recovery system. and,
a cryogenic turbine (10) configured to be driven by the gaseous working fluid produced in the evaporator (8);
A first pipeline (31) for supplying the working fluid condensed by the condenser (2) to the gas-liquid separation tank, wherein an outlet (311) of the first pipeline (31) is A first pipe line (31) configured to be positioned below the liquid surface (41) of the gas-liquid separation tank (4).

According to the power recovery system according to the present disclosure, since the outflow port of the first pipe is positioned below the liquid surface of the gas-liquid separation tank, the working fluid condensed by the condenser is It is supplied directly to the liquid phase, not to the liquid phase. Therefore, when the outlet of the first pipe is positioned above the liquid surface of the gas-liquid separation tank, that is, when the working fluid condensed by the condenser is supplied to the liquid phase through the gas phase, Since the working fluid is not heated in the gas phase as compared with the case where the working fluid is heated, the working fluid can be supplied to the liquid phase while maintaining a low temperature. Also, when the liquid working fluid is supplied from the gas-liquid separation tank to the cooling pump, it can be supplied in a low temperature state, thereby suppressing gasification of the working fluid in the pump section of the cooling pump. can do As a result, it is possible to suppress the occurrence of cavitation in the pump portion of the cold pump, and to suppress gas from being sucked into the cold pump so that the cold pump can be driven normally.

2) A power recovery system according to another aspect is the power recovery system (1) according to 1), wherein the liquid working fluid stored in the gas-liquid separation tank (4) is transferred to the cooling/heating pump (6). further comprising a second conduit (32) configured to supply to
In the vertical direction of the gas-liquid separation tank (4), when the position of the bottom surface is defined as the 0% position and the position of the ceiling surface is defined as the 100% position,
The outlet (311) of the first conduit (31) and the inlet (321) of the second conduit (32) are configured to be positioned in the range of 0% to 25%.

According to such a configuration, the outlet of the first pipe and the inlet of the second pipe are located in the range of 0% to 25% (that is, the bottom side) in the vertical direction of the gas-liquid separation tank 4. ing. For this reason, the working fluid that has flowed out from the outlet of the first conduit to the liquid phase portion is not warmed in the vertically upper liquid phase portion where the temperature of the working fluid is high, and is maintained in a low temperature state. It flows into the inflow port of the second pipeline and is supplied to the cold/heat pump. As a result, gasification of the working fluid in the pump portion of the cold/heat pump can be suppressed.

3) A power recovery system according to still another aspect is the power recovery system (1) according to 1) or 2), wherein the working fluid contains a fluid having a boiling point of less than 0°C.

According to such a configuration, the present power recovery system can be operated by using a fluid with a boiling point of less than 0° C. as the working fluid. Examples of the working fluid include propane, but the working fluid other than propane can also be used as the working fluid flowing through the circulation flow path.

4) A power recovery system according to still another aspect is the power recovery system (1) according to any one of 1) to 3), wherein the cold/heat pump (6) and the evaporator (8) and a recirculation pipe (5) for returning the working fluid pressurized by the cooling pump (6) to the gas-liquid separation tank (4),
The outlet (51) of the recirculation line (5) is located below the liquid level of the gas-liquid separation tank (4).

According to such a configuration, since the outlet of the recirculation pipe is located below the liquid surface of the gas-liquid separation tank, the working fluid condensed by the condenser is not in the gas phase, but in the gas phase. It will be supplied directly to the liquid phase. Therefore, the working fluid that has flowed out from the outlet of the recirculation pipe to the liquid phase portion is not warmed in the vertically upper liquid phase portion where the temperature of the working fluid is high, and is maintained at a low temperature. It flows into the inflow port of 2 pipelines and is supplied to the cooling pump. As a result, gasification of the working fluid in the pump portion of the cold/heat pump can be suppressed.

5) A power recovery system according to still another aspect is the power recovery system (1) according to 4),
a second recirculation line (15) branching from the recirculation line (5) and returning the working fluid pressurized by the cooling pump (6) to the condenser (2);
a first recirculation valve (16V) capable of adjusting the flow rate of the working fluid flowing through the second recirculation line (15);
a second recirculation valve (17V) capable of adjusting the flow rate of the working fluid flowing downstream of the branch position of the second recirculation line (15) in the recirculation line (5);
further comprising a control device (9) capable of controlling respective valve opening degrees of the first recirculation valve (16V) and the second recirculation valve (17V),
The control device (9) is
When the liquid temperature of the working fluid pressurized by the cooling pump (6) is below a predetermined temperature, the working fluid pressurized by the cooling pump (6) is transferred to the gas-liquid separation tank (4). reflux, and
When the liquid temperature of the working fluid pressurized by the cooling pump (6) exceeds the predetermined temperature, the working fluid pressurized by the cooling pump (6) is returned to the condenser (2). The valve opening degree of each of the first recirculation valve (16V) and the second recirculation valve (17V) is controlled so as to cause

When the temperature of the working fluid rises to a predetermined temperature or higher due to the heat input from the cold/heat pump, when the working fluid whose temperature rises is returned to the gas-liquid separation tank, the working fluid stored in the gas-liquid separation tank is reduced. There is a risk of raising the temperature. Therefore, according to such a configuration, when the temperature of the working fluid rises to a predetermined temperature (third threshold value) or higher due to the heat input from the cooling pump, the working fluid is returned to the condenser 2 and condensed. By supplying the working fluid to the gas-liquid separation tank after reducing the temperature in the vessel, it is possible to suppress the temperature rise of the working fluid stored in the gas-liquid separation tank.

6) A power recovery system according to still another aspect is the power recovery system (1) according to any one of 1) to 5), wherein the working fluid condensed by the condenser (2) is A first sub-pipeline (7) for supplying to the gas-liquid separation tank (4), wherein an outlet (71) of the first sub-pipeline (7) is connected to the gas-liquid separation tank (4) It further comprises a first sub-pipeline (7) configured to be positioned above the liquid level (41) of the liquid.

According to such a configuration, since the gas phase portion above the liquid surface of the gas-liquid separation tank is provided with the outflow port of the first sub-pipe above the liquid surface of the gas-liquid separation tank, The working fluid flowing in from the first sub-pipe is directly supplied to the gas phase portion. Therefore, the temperature of the gas phase portion above the liquid level in the gas-liquid separation tank is lowered, and a low saturated vapor pressure can be obtained. When the pressure (saturated vapor pressure) of the gas phase portion above the liquid surface of the gas-liquid separation tank is lowered, the pressure at the outlet of the chiller turbine is also lowered, so the turbine efficiency can be improved.

7) A power recovery system according to still another aspect is the power recovery system according to 6),
a first valve (31V) capable of adjusting the flow rate of the working fluid flowing through the first conduit (31);
a second valve (7V) capable of adjusting the flow rate of the working fluid flowing through the first sub-line (7);
a control device (9) capable of controlling the respective valve opening degrees of the first valve (31V) and the second valve (7V);
The control device (9) controls the temperature T1 of the gas phase above the liquid level (41) of the gas-liquid separation tank (4) and the cooling pump (4). 6) is such that the difference ΔT between the liquid temperature T2 of the liquid working fluid before being sucked is greater than a first threshold value and less than a second threshold value that is greater than the first threshold value. It is configured to control the respective valve opening degrees of the first valve (31V) and the second valve (7V).

According to such a configuration, the difference ΔT is controlled between the first threshold and the second threshold. When the difference ΔT is smaller than the first threshold, the temperature difference between the liquid temperature T2 and the temperature T1 of the vapor phase portion, which is the saturation temperature, becomes small. Also, even a slight heating in the pump portion of the cold/heat pump facilitates gasification. On the other hand, when the difference ΔT is larger than the second threshold, the temperature T1 of the gas phase portion is high, the gas phase portion has a high saturated steam pressure, and the turbine efficiency of the cold turbine 10 may decrease. Therefore, by using the difference ΔT as a control parameter and performing control by setting the first threshold value and the second threshold value for the difference ΔT, it is possible to increase the turbine efficiency without causing gasification of the working fluid.

8) A power recovery system according to still another aspect is the power recovery system (1) according to any one of 1) to 7),
A degassing pipe (11) branched from the first pipe (31), wherein the gaseous working fluid that has not been condensed in the condenser (2) is discharged to the outside of the first pipe (31). It further comprises a vent pipe (11) for discharging to.

According to such a configuration, when the working fluid is not sufficiently liquefied in the condenser, the gas in the first pipeline can be discharged to the outside by providing the gas vent pipe in the first pipeline. can. Therefore, it is possible to suppress the inflow of gas into the liquid phase portion located below the liquid surface of the gas-liquid separation tank and the intake of gas into the cold/heat pump portion.

9) A power recovery system according to still another aspect is the power recovery system (1) according to any one of 1) to 8),
The first pipe line (31) is inserted into the gas-liquid separation tank (4) from above the liquid surface (41) of the gas-liquid separation tank (4) and extends downward from the liquid surface. and an internal conduit (31B) extending through.

According to such a configuration, since the first pipe line is inserted into the gas-liquid separation tank from above the liquid surface of the gas-liquid separation tank, it may be inserted into the gas-liquid separation tank from below the liquid surface. In comparison, the distance that the first conduit is exposed to ambient air at a higher temperature than the working fluid condensed by the condenser is reduced. Therefore, outside the gas-liquid separation tank, the working fluid in the first pipe can be prevented from being heated by heat input from the outside.

1 Power Recovery System 2 Condenser 3 Circulation Channel 4 Gas-Liquid Separation Tank 5 Recirculation Pipeline 5V Valve 6 Cooling Pump 7 First Subline 7V Second Valve 8 Evaporator 9 Controller 10 Cooling Turbine 11 Gas Vent Pipe 12 Generator 131 First sensor 132 Second sensor 133 Third sensor 14 Exhaust gas pipe 15 Second recirculation pipe 16V First return valve 17V Second return valve 21 Heating side pipe 22 Heated side pipe 31 1st pipeline 31V 1st valve 311 outlet 31A external pipeline 31B internal pipeline 31B1 internal horizontal pipeline 31B2 internal vertical pipeline 32 second pipeline 321 outlet 33 third pipeline 33V valve 34 fourth pipeline 35 5 pipeline 41 liquid surface 42 gas phase portion 43 liquid phase portion 44 ceiling surface 45 bottom surface 46 side surface 81 heated side pipeline 82 heating side pipeline 101 floating structure on water 111 engine 102 land LNG (liquefied gas) base 112 Destination

Claims (9)

A power recovery system for recovering cold energy of the liquefied gas as power through a working fluid for heating the liquefied gas,
a condenser configured to condense the working fluid by exchanging heat between the working fluid and the liquefied gas;
a gas-liquid separation tank configured to separate and store the working fluid condensed by the condenser into a liquid and a gas;
a cooling pump configured to increase the pressure of the liquid working fluid supplied from the gas-liquid separation tank;
an evaporator configured to evaporate the working fluid by exchanging heat between the working fluid pressurized by the cold heat pump and a heating fluid introduced from the outside of the cold heat recovery system;
a cooling turbine configured to be driven by the gaseous working fluid produced by the evaporator;
A first pipeline for supplying the working fluid condensed by the condenser to the gas-liquid separation tank, wherein an outlet of the first pipeline is below the liquid surface of the gas-liquid separation tank. a first conduit configured to be located in a power recovery system. further comprising a second pipeline configured to supply the liquid working fluid stored in the gas-liquid separation tank to the cooling pump;
In the vertical direction of the gas-liquid separation tank, when the position of the bottom surface is defined as the 0% position and the position of the ceiling surface is defined as the 100% position,
2. The power recovery system of claim 1, wherein the outlet of the first conduit and the inlet of the second conduit are positioned in a range of 0% to 25%. The working fluid comprises a fluid with a boiling point of less than 0°C.
A power recovery system according to claim 1 or 2. further comprising a recirculation pipeline that branches from between the cooling pump and the evaporator and returns the working fluid pressurized by the cooling pump to the gas-liquid separation tank;
4. The power recovery system according to any one of claims 1 to 3, wherein the outlet of the recirculation line is positioned below the liquid surface of the gas-liquid separation tank. a second recirculation line that branches off from the recirculation line and returns the working fluid pressurized by the cold/heat pump to the condenser;
a first recirculation valve capable of adjusting the flow rate of the working fluid flowing through the second recirculation line;
a second recirculation valve capable of adjusting the flow rate of the working fluid flowing downstream of the branch position of the second recirculation line in the recirculation line;
a control device capable of controlling the respective valve opening degrees of the first recirculation valve and the second recirculation valve;
The control device is
when the liquid temperature of the working fluid pressurized by the cooling pump is below a predetermined temperature, the working fluid pressurized by the cooling pump is returned to the gas-liquid separation tank;
When the liquid temperature of the working fluid pressurized by the cooling pump exceeds the predetermined temperature, the first recirculation valve is configured to return the working fluid pressurized by the cooling pump to the condenser. 5. The power recovery system of claim 4, configured to control the valve opening of each of the second return valve and the second return valve. a first sub-pipeline for supplying the working fluid condensed by the condenser to the gas-liquid separation pump, wherein an outlet of the first sub-pipeline is connected to the liquid surface of the gas-liquid separation tank; 6. The power recovery system according to any one of claims 1 to 5, further comprising a first sub-pipe line configured to be positioned above the first sub-pipeline. a first valve capable of adjusting the flow rate of the working fluid flowing through the first conduit;
a second valve capable of adjusting the flow rate of the working fluid flowing through the first sub-pipe;
a control device capable of controlling the respective valve opening degrees of the first valve and the second valve,
The control device controls the temperature T1 of the gas phase above the liquid surface of the gas-liquid separation tank and the liquid working fluid flowing out of the gas-liquid separation tank and before being sucked into the cooling pump. The valve opening degrees of the first valve and the second valve are adjusted such that the difference ΔT from the liquid temperature T2 is larger than a first threshold and smaller than a second threshold larger than the first threshold. 7. The power recovery system of claim 6, wherein the power recovery system is configured to control the Further comprising a gas vent pipe branched from the first pipeline for discharging the gaseous working fluid that has not been condensed in the condenser to the outside of the first pipeline,
A power recovery system according to any one of claims 1 to 7. The first pipeline includes an internal pipeline that is inserted into the gas-liquid separation tank from above the liquid surface of the gas-liquid separation tank and extends downward from the liquid surface,
A power recovery system according to any one of claims 1 to 8.

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