Cold energy power generation system

Abstract

To improve output of a cold heat power generation system 10.SOLUTION: A cold heat power generation system 10 comprises: a liquefaction section 16 which liquefies a gaseous intermediate medium with cold heat of liquefied gas; an intermediate medium holding tank 17 which holds the liquid intermediate medium liquefied through the liquefaction section 16; a liquid pump 13 which pumps and sends the liquid intermediate medium sucked from the intermediate medium holding tank 17; a heat exchanger 14 which evaporates the intermediate medium pumped and sent out with the liquid pump 13; and an expansion turbine 15 which is connected to a generator 18 and driven with the intermediate medium evaporated through the heat exchanger 14. The liquefaction section 16 is a laminated micro channel heat exchanger 20 formed by laminating plates respectively having flow passages and is also a countercurrent type heat exchanger performing heat exchange between the liquefied gas and gaseous intermediate medium flowing in directions opposite to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cold energy power generation system. [Background technology]

[0002] A power generation system using a Rankine cycle is known as a method for utilizing the cold energy of liquefied gas. In this type of power generation system, an intermediate medium such as liquefied propane (LPG) or chlorofluorocarbons is condensed using the cold energy of the liquefied gas. The condensed intermediate medium is then vaporized using a hot heat source such as seawater, and the vaporized intermediate medium drives a turbine. In the power generation system disclosed in Patent Document 1 listed below, as shown in FIG. 19, a condenser 91 that exchanges heat between the low-temperature liquefied gas and the intermediate medium is configured as a shell-and-tube heat exchanger. In a shell-and-tube heat exchanger, the intermediate medium liquefied in the shell 91a may adhere to the outer surface of the heat transfer tube 91b through which the low-temperature liquefied gas flows. In this case, the intermediate medium adhering to the heat transfer tube 91b may be cooled by the liquefied gas through the heat transfer tube 91b and become supercooled, resulting in a decrease in power generation. In other words, when excessive supercooling of the intermediate medium occurs, eliminating the supercooling requires reducing the flow rate of the intermediate medium in the evaporator 93, which exchanges heat between the heat source and the intermediate medium, to raise the intermediate medium temperature. In this case, the flow rate of the circulating intermediate medium decreases, resulting in a decrease in the amount of power generated. In Patent Document 1 listed below, to avoid excessive supercooling, a branch pipe 95 is provided that diverts a portion of the gaseous intermediate medium flowing from the turbine 94 before it flows into the condenser 91, and a tank-like contact tower 96 is provided that mixes the diverted gaseous intermediate medium flowing through the branch pipe 95 with the liquid intermediate medium flowing from the condenser 91. By bypassing the condenser 91, a portion of the intermediate medium is avoided from being excessively supercooled. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 62-037209 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the tank-shaped contact tower 96 disclosed in Patent Document 1, uneven mixing occurs when the gaseous intermediate medium is mixed with the liquid intermediate medium, which can cause an intermediate medium with a low degree of supercooling to flow out of the contact tower 96. This can lead to a situation where the amount of intermediate medium circulated must be reduced to avoid a supercooled state. Therefore, even if a configuration is adopted in which part of the gaseous intermediate medium is bypassed by the condenser 91 and then mixed with the liquid intermediate medium, it can lead to a situation in which the amount of power generation cannot be improved.

[0005] Therefore, the present invention has been made in consideration of the above-mentioned conventional technology, and its object is to improve the amount of power generation in a cold energy power generation system that drives an expansion turbine with an intermediate medium. [Means for solving the problem]

[0006] In order to achieve the above object, the cold energy power generation system of the present invention includes a liquefaction unit that exchanges heat between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold energy of the liquefied gas, an intermediate medium holding tank that holds the liquid intermediate medium liquefied in the liquefaction unit, a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank, a heat exchanger that vaporizes the liquid intermediate medium discharged by the liquid pump, and an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger. a branch passage for diverting a portion of the gaseous intermediate medium vaporized in the expansion turbine before it flows into the liquefaction section; The liquefaction section is configured by a stacked microchannel heat exchanger having a configuration in which plates, each having a flow path formed therein, are stacked, and is of a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other to exchange heat. The flow paths of the stacked microchannel heat exchanger include a high-temperature side flow path into which the gaseous intermediate medium flows and a low-temperature side flow path into which the liquefied gas flows, and the stacked microchannel heat exchanger is provided with a communicating flow path that connects the branch path to the high-temperature side flow path.

[0007] In the present invention, the liquefaction unit that exchanges heat between the liquefied gas and the gaseous intermediate medium is a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions, allowing heat exchange between the two to occur even when there is a large temperature difference between the liquefied gas and the gaseous intermediate medium. Furthermore, unlike shell-and-tube heat exchangers, the intermediate medium does not adhere to the heat transfer tubes and become excessively supercooled. Therefore, compared to when the liquefaction unit is configured using a shell-and-tube heat exchanger, the flow rate of the intermediate medium flowing into the expansion turbine can be increased, resulting in increased power generation.

[0009] moreover A portion of the gaseous intermediate medium vaporized in the expansion turbine is diverted by the branching passage before flowing into the liquefaction section, and this diverted gaseous intermediate medium is merged with the intermediate medium flowing through the high-temperature flow path of the stacked microchannel heat exchanger that constitutes the liquefaction section. Therefore, even if the amount of cold supplied from the liquefied gas to the intermediate medium increases due to an increase in the liquefied gas flow rate, the intermediate medium can be prevented from being cooled too much at the outlet of the liquefaction section, and freezing of the intermediate medium can be prevented.

[0010] The cold energy power generation system according to the present invention includes a liquefaction unit that exchanges heat between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold energy of the liquefied gas, an intermediate medium holding tank that holds the liquid intermediate medium liquefied in the liquefaction unit, a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank, a heat exchanger that vaporizes the liquid intermediate medium discharged by the liquid pump, and an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger. a branching passage that branches a portion of the gaseous intermediate medium vaporized in the expansion turbine before flowing into the liquefaction section; and a mixing section that merges the gaseous intermediate medium that has flowed through the branching passage with the liquid intermediate medium that has flowed out from the liquefaction section. The liquefaction section is configured by a stacked microchannel heat exchanger having a configuration in which plates, each having a flow path formed therein, are stacked, and is of a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other to exchange heat. The mixing section is composed of a stacked microchannel mixer having a configuration in which plates in which flow paths are formed are stacked. R, The flow path of the laminated microchannel mixer includes a liquid flow path through which the liquid intermediate medium flowing out from the liquefaction section flows. R, The stacked microchannel mixer is provided with a communication flow path that connects the branch path to the liquid flow path. R .

[0011] In the present invention, the liquefaction unit that exchanges heat between the liquefied gas and the gaseous intermediate medium is a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions, allowing heat exchange between the two to occur even when there is a large temperature difference between the liquefied gas and the gaseous intermediate medium. Furthermore, unlike shell-and-tube heat exchangers, the intermediate medium does not adhere to the heat transfer tubes and become excessively supercooled. Therefore, compared to when the liquefaction unit is configured using a shell-and-tube heat exchanger, the flow rate of the intermediate medium flowing into the expansion turbine can be increased, resulting in increased power generation. moreoverBecause the mixing section, which mixes the gaseous intermediate medium flowing through the branched channel with the liquid intermediate medium flowing out from the liquefaction section, is composed of a laminated microchannel mixer, the liquid intermediate medium introduced into the mixing section from the liquefaction section flows through each liquid flow path within the laminated microchannel mixer. Therefore, uneven mixing is unlikely to occur when the gaseous intermediate medium flowing through the branched channel is mixed with the liquid intermediate medium in the liquid flow path of the laminated microchannel mixer through the communicating flow path. Furthermore, a configuration is adopted in which a portion of the gaseous intermediate medium vaporized by the expansion turbine is diverted before flowing into the liquefaction section, and this portion of the intermediate medium is mixed with the liquid intermediate medium flowing out from the liquefaction section. This prevents the liquid intermediate medium introduced from the liquefaction section and the gaseous intermediate medium introduced from the branched channel from coming into uniform contact with each other, thereby preventing the gaseous intermediate medium from flowing into the intermediate medium holding tank without being completely liquefied and being sucked into the pump.

[0012] The flow paths of the stacked microchannel heat exchanger may include a high-temperature flow path into which the gaseous intermediate medium flows and a low-temperature flow path into which the liquefied gas flows. In this case, a connecting path may be provided to connect the branch path to the stacked microchannel heat exchanger, and the stacked microchannel heat exchanger may be provided with a second communication path that connects the connecting path to the high-temperature flow path.

[0013] In this configuration, a portion of the gaseous intermediate medium vaporized in the expansion turbine is diverted by the branching passage before flowing into the liquefaction section. One portion of the diverted intermediate medium flows into the mixing section, and the other portion of the diverted intermediate medium is introduced into the stacked microchannel heat exchanger constituting the liquefaction section through the connecting passage. The intermediate medium flowing through this connecting passage is merged with the intermediate medium flowing through the high-temperature flow passage. Therefore, even if the amount of cold supplied from the liquefied gas to the intermediate medium increases, such as when the liquefied gas flow rate increases, the intermediate medium can be prevented from being overcooled at the outlet of the liquefaction section and freezing can be prevented.

[0014] The stacked microchannel heat exchanger constituting the liquefaction section and the stacked microchannel mixer constituting the mixing section may be integrated together, which can reduce the manufacturing costs of the liquefaction section and the mixing section.

[0015] The cold-thermal power generation system of the present invention includes a liquefaction unit that exchanges heat between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold energy of the liquefied gas, an intermediate medium holding tank that holds the intermediate medium liquefied in the liquefaction unit, a liquid pump that pressurizes and discharges the liquid intermediate medium drawn from the intermediate medium holding tank, a heat exchanger that vaporizes the liquid intermediate medium discharged by the liquid pump, an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger, a branch channel that diverts a portion of the gaseous intermediate medium vaporized in the expansion turbine before it flows into the liquefaction unit, and a mixer that mixes the gaseous intermediate medium flowing through the branch channel with the liquid intermediate medium flowing out of the liquefaction unit. The mixer is configured as a stacked microchannel mixer configured by stacking plates with flow paths formed therein. The flow paths of the stacked microchannel mixer include a liquid flow path through which the liquid intermediate medium flowing out of the liquefaction unit flows. The stacked microchannel mixer is provided with a communication flow path that connects the branch path to the liquid flow path.

[0016] In the present invention, the mixing section that mixes the gaseous intermediate medium flowing through the branch channel with the liquid intermediate medium flowing out from the liquefaction section is composed of a laminated microchannel mixer. Therefore, the liquid intermediate medium introduced into the mixing section from the liquefaction section flows through each flow path in the laminated microchannel mixer. Therefore, uneven mixing is unlikely to occur when the gaseous intermediate medium flowing through the branch channel is mixed with the liquid intermediate medium in the flow path of the laminated microchannel mixer through the communicating flow path. Furthermore, a configuration is adopted in which a portion of the gaseous intermediate medium vaporized in the expansion turbine is diverted before flowing into the liquefaction section, and this portion of the intermediate medium is mixed with the liquid intermediate medium flowing out from the liquefaction section. This prevents the liquid intermediate medium introduced from the liquefaction section and the gaseous intermediate medium introduced from the branch channel from coming into uniform contact with each other, thereby preventing the gaseous intermediate medium from flowing into the intermediate medium holding tank without being completely liquefied and being sucked into the pump.

[0017] The cold-energy power generation system may also be provided with a pump control unit that adjusts the discharge flow rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump. In addition, the cold-thermal power generation system of the present invention comprises a liquefaction unit that exchanges heat between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold heat of the liquefied gas; an intermediate medium holding tank that holds the liquid intermediate medium liquefied in the liquefaction unit; a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank; a heat exchanger that vaporizes the liquid intermediate medium discharged by the liquid pump; and an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger, wherein the liquefaction unit is composed of a stacked microchannel heat exchanger configured by stacking plates each having a flow path formed therein, and is of a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other while exchanging heat, and a pump control unit that adjusts the discharge flow rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump.

[0018] In this embodiment, the gaseous intermediate medium can be prevented from being sucked into the liquid pump, thereby preventing cavitation in the liquid pump.

[0019] The cold-energy power generation system may also be provided with a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump.

[0020] In this embodiment, the gaseous intermediate medium can be prevented from being sucked into the liquid pump, thereby preventing cavitation in the liquid pump.

[0021] The cold-energy power generation system may also be provided with a flow rate control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is higher than the freezing point of the intermediate medium.

[0022] In this embodiment, the temperature of the liquid intermediate medium at the outlet side of the liquefaction section is maintained at a temperature higher than the freezing point of the intermediate medium, so that the intermediate medium can be prevented from freezing even if it exchanges heat with liquefied gas in the liquefaction section.

[0023] The cold-energy power generation system may include a pump control unit that adjusts the output rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure on the suction side of the liquid pump, and a flow rate control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is higher than the freezing point of the intermediate medium.

[0024] In this embodiment, the temperature of the liquid intermediate medium at the outlet side of the liquefaction section is maintained at a temperature higher than the freezing point of the intermediate medium, so that the intermediate medium can be prevented from freezing even if it exchanges heat with liquefied gas in the liquefaction section.

[0025] The cold-energy power generation system may also be provided with a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump and higher than the freezing point of the intermediate medium.

[0026] In this embodiment, the temperature of the liquid intermediate medium at the outlet side of the liquefaction section is maintained higher than the freezing point of the intermediate medium, so that the intermediate medium can be prevented from freezing even when heat is exchanged with the liquefied gas in the liquefaction section, and cavitation in the liquid pump can also be prevented. [Effects of the Invention]

[0027] As described above, according to the present invention, it is possible to improve the amount of power generation in a cold energy power generation system that drives an expansion turbine with an intermediate medium. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram schematically illustrating a cold energy power generation system according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a schematic configuration of a stacked microchannel heat exchanger that constitutes a liquefaction unit provided in the cryogenic power generation system. [Figure 3] 4 is a diagram for explaining the relationship between the amount of heat exchange and the temperature of the intermediate medium and the liquefied gas in the liquefaction section. FIG. [Figure 4] FIG. 4 is a diagram schematically illustrating a cold energy power generation system according to a second embodiment. [Figure 5] FIG. 2 is a diagram illustrating a schematic configuration of a stacked microchannel heat exchanger that constitutes a liquefaction unit provided in the cryogenic power generation system. [Figure 6] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a modified example of the second embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a modified example of the second embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a third embodiment. [Figure 9] FIG. 2 is a diagram illustrating a schematic configuration of a stacked microchannel mixer that constitutes a mixing section provided in the cold-heat power generation system. [Figure 10] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a modified example of the third embodiment. [Figure 11] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a modified example of the third embodiment. [Figure 12] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a fourth embodiment. [Figure 13] FIG. 2 is a diagram showing a schematic configuration of a stacked microchannel device provided in the cold energy power generation system. [Figure 14]FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a fifth embodiment. [Figure 15] FIG. 2 is a diagram illustrating a schematic configuration of a stacked microchannel heat exchanger that constitutes a liquefaction unit provided in the cryogenic power generation system. [Figure 16] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a sixth embodiment. [Figure 17] FIG. 2 is a diagram showing a schematic configuration of a stacked microchannel device provided in the cold energy power generation system. [Figure 18] FIG. 10 is a diagram schematically illustrating a cold energy power generation system according to a seventh embodiment. [Figure 19] FIG. 1 is a diagram illustrating a conventional power generation system. DETAILED DESCRIPTION OF THE INVENTION

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] (First embodiment) The cold energy power generation system according to the first embodiment is a system that extracts electric power while exchanging heat between a liquefied gas and a heat source medium via an intermediate medium. As shown in Fig. 1, the cold energy power generation system 10 includes a circulation flow path 12 in which an intermediate medium is sealed. In this cold energy power generation system 10, the intermediate medium circulates through the circulation flow path 12 while undergoing a phase change, thereby performing a Rankine cycle. For example, propane, chlorofluorocarbon, or the like is used as the intermediate medium.

[0031] A liquid pump 13, a heat exchanger 14, an expansion turbine 15, a liquefaction section 16, and an intermediate medium holding tank 17 are provided in this order in the circulation flow path 12. The liquid pump 13 sucks in the intermediate medium in the circulation flow path 12 and pressurizes the sucked intermediate medium. As the liquid pump 13, a centrifugal pump having an impeller as a rotor, a gear pump having a rotor formed by a pair of gears, or the like is used.

[0032] The heat exchanger 14 exchanges heat between the liquid intermediate medium pressurized by the liquid pump 13 and the heat source medium, thereby vaporizing the intermediate medium. As the heat source medium, a fluid such as seawater, industrial water, hot water, or steam can be used.

[0033] The expansion turbine 15 has a structure in which a rotor (not shown) is disposed in a casing, and is configured so that the rotor rotates as the vaporized intermediate medium expands. A generator 18 is connected to the rotor of the expansion turbine 15, and the generator 18 is driven by the rotor rotating as the gaseous intermediate medium expands in the expansion turbine 15. This generates electricity.

[0034] The liquefaction section 16 condenses the gaseous intermediate medium discharged from the expansion turbine 15 using the cold heat of the liquefied gas to turn it into a liquid intermediate medium. Examples of the liquefied gas include liquefied natural gas and liquid hydrogen.

[0035] The liquefaction section 16 is configured with a stacked microchannel heat exchanger 20, which is configured by stacking plates, each having a flow path formed therein. That is, as shown in FIGS. 2(a) to 2(c), the liquefaction section 16 includes a high-temperature side plate 21 having a plurality of high-temperature side flow paths 21a and a low-temperature side plate 22 having a plurality of low-temperature side flow paths 22a, and is configured by stacking the plurality of high-temperature side plates 21 and the plurality of low-temperature side plates 22. The plurality of high-temperature side plates 21 and the plurality of low-temperature side plates 22 may be stacked so that the high-temperature side plates 21 and the low-temperature side plates 22 alternate with each other, or a partition plate (not shown) may be interposed between the high-temperature side plate 21 and the low-temperature side plate 22. Each plate is made of metal and is joined to each other. A gaseous intermediate medium flows into each high-temperature side flow path 21a from the circulation flow path 12. A liquefied gas flows into each low-temperature side flow path 22a from a liquefied gas supply path 23.

[0036] In the liquefaction section 16, heat exchange occurs between the gaseous intermediate medium flowing through the high-temperature side flow path 21a and the liquefied gas flowing through the low-temperature side flow path 22a, causing the gaseous intermediate medium to condense. Meanwhile, the liquefied gas is vaporized by the heat exchange, and this vaporized gas flows out into the gas path 24.

[0037] In the liquefaction section 16, a high-temperature side flow path 21a and a low-temperature side flow path 22a are set so that the liquefied gas and the intermediate medium flow in opposite directions. In other words, the liquefaction section 16 is composed of a counterflow stacked microchannel heat exchanger 20.

[0038] Note that "opposite directions" as used herein is not limited to the case where the liquefied gas and the intermediate medium flow in a straight line in opposite directions, but also includes the case where at least one of the liquefied gas and the intermediate medium flows in a meandering manner and the two flow in opposite directions as a whole. For example, the liquefied gas may flow from top to bottom in Fig. 2(b) while meandering from side to side, and the intermediate medium may flow from bottom to top in Fig. 2(c) while meandering from side to side.

[0039] Because the liquefaction section 16 is configured using a counterflow stacked microchannel heat exchanger 20, heat exchange between the liquefied gas and the gaseous intermediate medium can be performed even when the temperature difference between them is large. Specifically, FIG. 3 shows the relationship between the heat exchange amount in the liquefaction section 16 and the temperatures of the intermediate medium and liquefied gas. The horizontal axis represents the heat exchange amount. As the liquefied gas flows through the low-temperature side flow path 22a, it receives heat from the intermediate medium, gradually increasing in temperature as the amount of heat received increases. The relationship between the amount of heat received and the temperature change of the liquefied gas at this time is shown in FIG. 3. Meanwhile, as the intermediate medium flows through the high-temperature side flow path 21a, it releases heat to the liquefied gas, gradually decreasing in temperature. The relationship between the amount of heat released and the temperature change of the intermediate medium at this time is also shown in FIG. 3. A large temperature difference can be achieved between the temperature of the liquefied gas when it flows into the liquefaction section 16 (the temperature at the left end of FIG. 3) and the temperature of the intermediate medium when it flows into the liquefaction section 16 (the temperature at the right end of FIG. 3). Moreover, because the intermediate medium flows through the high-temperature side flow path 21a without remaining in the high-temperature side flow path 21a, the intermediate medium is not supercooled. Therefore, there is no need to reduce the discharge flow rate from the liquid pump 13 to suppress supercooling. Therefore, the flow rate of the intermediate medium flowing into the expansion turbine 15 can be increased, and the amount of power generation can be increased.

[0040] The liquid intermediate medium condensed in the liquefaction section 16 is stored in the intermediate medium holding tank 17. The liquid intermediate medium stored in the intermediate medium holding tank 17 is sucked by the liquid pump 13.

[0041] In the cold power generation system 10, when the liquid pump 13 is operated, the liquid intermediate medium is discharged from the liquid pump 13, and this liquid intermediate medium flows into the heat exchanger 14 through the circulation flow path 12. In the heat exchanger 14, the liquid intermediate medium is heated by the heat source medium and evaporates, becoming a gaseous intermediate medium. The gaseous intermediate medium is introduced into the expansion turbine 15 and drives the rotor. As a result, the gaseous intermediate medium expands and its temperature drops. Meanwhile, as the rotor is driven, power is generated in the generator 18, and the heat of the heat source medium can be recovered as electricity.

[0042] The gaseous intermediate medium, which has been cooled and pressurized in the expansion turbine 15, flows into the liquefaction section 16. In the liquefaction section 16, the intermediate medium is cooled by the liquefied gas and condenses to become a liquid intermediate medium. At this time, the intermediate medium and the liquefied gas flow in opposite directions and exchange heat. After flowing out of the liquefaction section 16, the liquid intermediate medium is stored in the intermediate medium storage tank 17. The intermediate medium stored in the intermediate medium storage tank 17 is sucked into the liquid pump 13. The intermediate medium is circulated in this manner in the circulation flow path 12.

[0043] As described above, in this embodiment, the stacked microchannel heat exchanger 20 constituting the liquefaction unit 16, which exchanges heat between the liquefied gas and the gaseous intermediate medium, is a counterflow type in which the liquefied gas and the gaseous intermediate medium flow in opposite directions. Therefore, heat exchange between the liquefied gas and the gaseous intermediate medium can be performed even when there is a large temperature difference between them. Furthermore, unlike a shell-and-tube heat exchanger, the intermediate medium does not adhere to the heat transfer tubes and become excessively supercooled. Therefore, compared to a case in which the liquefaction unit 16 is composed of a shell-and-tube heat exchanger, the flow rate of the intermediate medium flowing into the expansion turbine 15 can be increased, resulting in increased power generation.

[0044] (Second embodiment) 4 shows the second embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0045] The cold energy power generation system 10 of the second embodiment differs from the first embodiment in that a branch passage 28 is connected to the circulation flow path 12. Specifically, one end (upstream end) of the branch passage 28 is connected to a flow path between the expansion turbine 15 and the liquefaction section 16 in the circulation flow path 12. Therefore, the gaseous intermediate medium flowing out from the expansion turbine 15 flows into the branch passage 28. The other end (downstream end) of the branch passage 28 is connected to the stacked microchannel heat exchanger 20 that constitutes the liquefaction section 16.

[0046] As shown in Figures 5(a), (c), and (d), the stacked microchannel heat exchanger 20 is provided with a communicating flow path 30 connected to the high-temperature side flow path 21a, and the branch path 28 is connected to this communicating flow path 30.

[0047] The communicating flow path 30 includes an adjacent flow path 30a formed in an adjacent plate 31 adjacent to the high-temperature-side plate 21 having the high-temperature-side flow path 21a, and an extension flow path 30b extending from the adjacent plate 31 to the high-temperature-side plate 21 so as to bridge the adjacent flow path 30a and the high-temperature-side flow path 21a. The branching flow path 28 is connected to the adjacent flow path 30a, so that the branching flow path 28 communicates with the high-temperature-side flow path 21a through the communicating flow path 30. Therefore, the gaseous intermediate medium that has flowed through the branching flow path 28 merges with the gaseous or liquid intermediate medium flowing through the high-temperature-side flow path 21a.

[0048] The stacked microchannel heat exchanger 20 is provided with a temperature regulator 33 that measures the temperature of the intermediate medium flowing through the high-temperature side flow path 21a and outputs a signal corresponding to the measured temperature. The high-temperature side flow path 21a has an extended portion at its intermediate portion that extends outside the high-temperature side plate 21, and the measurement end of the temperature regulator 33 is provided at this extended portion. Note that if the measurement end of the temperature regulator 33 can be disposed within the high-temperature side plate 21, this extended portion can be omitted. Instead of the temperature regulator 33, a temperature sensor (not shown) may be provided, and a controller (not shown) that controls signal output according to the temperature measured by the temperature sensor may be provided.

[0049] The branch path 28 allows the gaseous intermediate medium to flow upstream of the temperature measurement unit where the measurement end of the temperature regulator 33 is located in the high-temperature-side flow path 21a. A flow rate control valve 34 is provided in the branch path 28. The flow rate control valve 34 is electrically connected to the temperature regulator 33, and a signal output from the temperature regulator 33 is used to control the flow rate control valve 34 so that the measured temperature becomes a predetermined temperature. The flow rate control valve 34 adjusts its opening in response to the signal, thereby adjusting the flow rate of the intermediate medium diverted from the circulation flow path 12 to the branch path 28, thereby controlling the temperature of the liquid intermediate medium flowing out of the liquefaction unit 16 to a predetermined temperature. This predetermined temperature may be, for example, a temperature higher than the freezing point of the intermediate medium. In this case, the temperature regulator 33 and the flow rate control valve 34 function as a flow rate control unit that adjusts the flow rate of the gaseous intermediate medium flowing through the branch path 28 so that the temperature of the intermediate medium downstream of the liquefaction unit 16 becomes a temperature higher than the freezing point of the intermediate medium. In this case, the temperature of the liquid intermediate medium at the outlet side of the liquefaction section 16 is maintained at a temperature higher than the freezing point of the intermediate medium, so that the intermediate medium can be prevented from freezing even if heat exchange with liquefied gas occurs in the liquefaction section 16.

[0050] The predetermined temperature may be a temperature that is lower by a predetermined set temperature than the saturation temperature of the intermediate medium corresponding to the pressure measurement value on the suction side of liquid pump 13. In this case, the predetermined set temperature is approximately several degrees. In this case, as shown in FIG. 6, a pressure gauge 36 is provided on the suction side of liquid pump 13, and a temperature sensor 37 is provided instead of temperature regulator 33. Temperature sensor 37 may detect the temperature of the intermediate medium in liquefaction unit 16, or may detect the temperature of the intermediate medium flowing out from liquefaction unit 16. A flow control unit 38 is provided that controls flow control valve 34 in response to signals output from temperature sensor 37 and pressure gauge 36. Flow control unit 38 controls flow control valve 34 so that the temperature detected by temperature sensor 37 is lower than the saturation temperature of the intermediate medium corresponding to the pressure detected by pressure gauge 36. This configuration prevents gaseous intermediate medium from being sucked into liquid pump 13, thereby preventing cavitation in liquid pump 13.

[0051] 7, a pump control unit 39 that adjusts the discharge flow rate of liquid pump 13 may be provided instead of or in addition to the configuration that controls the flow rate of branch line 28 with flow rate adjustment valve 34. Pump control unit 39 is configured to adjust the discharge rate of liquid pump 13 so that the temperature detected by temperature sensor 37 is lower than the saturation temperature of the intermediate medium corresponding to the measurement value of pressure gauge 36. This configuration makes it possible to prevent gaseous intermediate medium from being sucked into liquid pump 13, thereby preventing cavitation in liquid pump 13.

[0052] Furthermore, for example, when the flow rate of the liquefied gas is stable, it is possible to omit the configuration for controlling the flow rate through the branch passage 28 by the flow rate adjustment valve 34.

[0053] Although a description of other configurations, actions, and effects will be omitted, the description of the first embodiment can be applied to the second embodiment.

[0054] (Third embodiment) 8 shows the third embodiment. Note that the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0055] In the second embodiment, the gaseous intermediate medium that has flowed through the branch path 28 is made to flow into the liquefaction section 16, whereas the cold energy power generation system 10 of the third embodiment differs in that the gaseous intermediate medium that has flowed through the branch path 28 merges with the liquid intermediate medium that has flowed out of the liquefaction section 16.

[0056] Specifically, a mixing section 42 is provided in the circulation flow path 12 at a location between the liquefaction section 16 and the intermediate medium holding tank 17. The mixing section 42 is a section for merging the gaseous intermediate medium diverted to the branch path 28 with the liquid intermediate medium that has flowed out of the liquefaction section 16, and is composed of a stacked microchannel mixer 43.

[0057] 9(a) to 9(c), the stacked microchannel mixer 43 has a main plate 44 having a plurality of liquid flow paths 44a for flowing a liquid intermediate medium, and a confluence plate 45 stacked on the main plate 44. Each plate is made of metal and is joined to each other.

[0058] The junction plate 45 and the main plate 44 have a communication flow path 47 for flowing the gaseous intermediate medium introduced through the branch path 28. The communication flow path 47 includes a gas flow path 47a formed in the junction plate 45 and an extension flow path 47b extending from the junction plate 45 to the main plate 44 so as to bridge this gas flow path 47a and the liquid flow path 44a of the main plate 44. Since the branch path 28 is connected to the gas flow path 47a, the branch path 28 is in communication with the liquid flow path 44a through the communication flow path 47. Therefore, the gaseous intermediate medium that has flowed through the branch path 28 merges through the communication flow path 47 with the liquid intermediate medium flowing through the liquid flow path 44a.

[0059] In this configuration, the mixing section 42, which mixes the gaseous intermediate medium flowing through the branch path 28 with the liquid intermediate medium flowing out from the liquefaction section 16, is composed of a laminated microchannel mixer 43. The liquid intermediate medium introduced into the mixing section 42 from the liquefaction section 16 flows through each liquid flow path 44a in the laminated microchannel mixer 43. Therefore, uneven mixing is unlikely to occur when the gaseous intermediate medium flowing through the branch path 28 is mixed with the liquid intermediate medium in the liquid flow path 44a of the laminated microchannel mixer 43 through the communicating flow path 47. In addition, a configuration is adopted in which a portion of the gaseous intermediate medium vaporized in the expansion turbine 15 is diverted before flowing into the liquefaction section 16, and this portion of the intermediate medium is merged with the liquid intermediate medium flowing out from the liquefaction section 16. This prevents the liquid intermediate medium introduced from the liquefaction section 16 and the gaseous intermediate medium introduced from the branch path 28 from coming into even contact with each other, resulting in the gaseous intermediate medium flowing into the intermediate medium holding tank 17 without being completely liquefied and being sucked into the pump.

[0060] 8, a temperature regulator 333 may be provided downstream of the mixing section 42. The temperature regulator 33 is electrically connected to the flow rate control valve 34, and controls the flow rate control valve 34 so that the measured temperature becomes a predetermined temperature.

[0061] 10, in the third embodiment, a flow rate control unit 38 may control the flow rate adjustment valve 34 in response to signals output from a temperature sensor 37 and a pressure gauge 36. The flow rate control unit 38 controls the flow rate adjustment valve 34 so that the temperature detected by the temperature sensor 37 is lower than the saturation temperature of the intermediate medium corresponding to the pressure detected by the pressure gauge 36. With this configuration, it is possible to prevent the gaseous intermediate medium from being sucked into the liquid pump 13, thereby preventing cavitation in the liquid pump 13.

[0062] 11, a pump control unit 39 may be provided to adjust the discharge flow rate of liquid pump 13, instead of or in addition to the configuration in which flow rate adjustment valve 34 controls the flow rate of branch line 28. In this case, a temperature sensor 37 is provided to detect the temperature of the intermediate medium flowing through liquefaction unit 16, the intermediate medium flowing out of liquefaction unit 16, or the intermediate medium flowing out of mixing unit 42, and a pressure gauge 36 is provided to detect the pressure of the intermediate medium on the suction side of liquid pump 13. Pump control unit 39 is configured to adjust the discharge rate of liquid pump 13 so that the temperature detected by temperature sensor 37 is lower than the saturation temperature of the intermediate medium corresponding to the measurement value of pressure gauge 36. This configuration prevents gaseous intermediate medium from being sucked into liquid pump 13, thereby preventing cavitation in liquid pump 13.

[0063] Although the description of other configurations, actions, and effects will be omitted, the descriptions of the first and second embodiments can be applied to the third embodiment.

[0064] (Fourth embodiment) 12 shows the fourth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0065] The cold energy power generation system 10 of the fourth embodiment differs from the third embodiment in that the stacked microchannel heat exchanger 20 constituting the liquefaction section 16 shown in the third embodiment and the stacked microchannel mixer 43 constituting the mixing section 42 are integrally formed. As shown in Fig. 12, the mixing section 42 is located in a position between the liquefaction section 16 and the intermediate medium holding tank 17 in the circulation flow path 12, and the stacked microchannel mixer 43 constituting the mixing section 42 and the stacked microchannel heat exchanger 20 constituting the liquefaction section 16 are integrally formed by a stacked microchannel device 50.

[0066] Specifically, as shown in Figures 13(a) to (d), the stacked microchannel device 50 has a first plate 51 in which a flow path is formed up to the middle position in the longitudinal direction, a second plate 52 in which a flow path is formed throughout the entire longitudinal direction, and a third plate 53 including a confluence plate 45, and these plates 51, 52, and 53 are stacked together.

[0067] The first plate 51 is made up of a plate portion 51a that constitutes the low-temperature side plate 22 of the liquefaction section 16, and a plate portion 51b that is continuous with the low-temperature side plate 22 without forming a flow path.

[0068] The second plate 52 is composed of a plate portion 52a that constitutes the high-temperature side plate 21 of the liquefaction section 16 and a plate portion 52b that constitutes the main plate 44 of the mixing section 42. In other words, the second plate 52 has a flow path formed therein that connects the high-temperature side flow path 21a of the liquefaction section 16 and the liquid flow path 44a of the mixing section 42 so that they are continuous with each other.

[0069] The third plate 53 is composed of a plate portion 53a where no flow passages are formed and a plate portion 53b that constitutes the confluence plate 45. A gas flow passage 47a is formed in the confluence plate 45. An extension flow passage 47b that extends from the third plate 53 to the main plate 44 of the second plate 52 is formed in the plate portion 53b that constitutes the confluence plate 45 and the plate portion 52b of the second plate 52 so as to bridge the gas flow passage 47a and the high-temperature-side flow passage 21a. The extension flow passage 47b and the gas flow passage 47a form a communication flow passage 47 that connects the branch passage 28 to the liquid flow passage 44a.

[0070] According to this embodiment, the manufacturing costs of the liquefaction section 16 and the mixing section 42 can be reduced.

[0071] 13(c) shows a configuration in which the temperature regulator 33 is provided, the temperature regulator 33 may be omitted. Although a description of other configurations, actions, and effects will be omitted, the descriptions of the first to third embodiments can be applied to the fourth embodiment.

[0072] (Fifth embodiment) 14 shows the fifth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0073] The cold energy power generation system 10 of the fifth embodiment has the same configuration as the third embodiment, except that the branch path 28 has a connection path 55 that guides a portion of the gaseous intermediate medium flowing through the branch path 28 to the liquefaction section 16. The connection path 55 branches off from the middle of the branch path 28 and communicates with the high-temperature side flow path 21a in the stacked microchannel heat exchanger 20 that constitutes the liquefaction section 16.

[0074] 15(a) to 15(d), the stacked microchannel heat exchanger 20 is provided with a second communication passage 57 that connects the connection passage 55 to the high-temperature-side passage 21a. The second communication passage 57 includes a second adjacent passage 57a formed in the adjacent plate 31 adjacent to the high-temperature-side plate 21 having the high-temperature-side passage 21a, and a second extension passage 57b that extends from the adjacent plate 31 to the high-temperature-side plate 21 to bridge the second adjacent passage 57a and the high-temperature-side passage 21a. The connection passage 55 is connected to the second adjacent passage 57a, so that the connection passage 55 communicates with the high-temperature-side passage 21a through the second communication passage 57. Therefore, the gaseous intermediate medium that flows through the connection passage 55 merges with the gaseous or liquid intermediate medium flowing through the high-temperature-side passage 21a.

[0075] Therefore, in this embodiment, a portion of the gaseous intermediate medium vaporized in the expansion turbine 15 is diverted by the branch path 28 before flowing into the liquefaction unit 16, and a portion of this diverted intermediate medium passes through the connection path 55 and merges with the intermediate medium flowing through the high-temperature side flow path 21a of the stacked microchannel heat exchanger 20 that constitutes the liquefaction unit 16. The other portion of the diverted intermediate medium flows from the branch path 28 into the stacked microchannel mixer 43 that constitutes the mixing unit 42. Therefore, even if the amount of cold supplied from the liquefied gas to the intermediate medium increases, such as when the flow rate of the liquefied gas increases, the intermediate medium can be prevented from being cooled too much at the outlet of the liquefaction unit 16, and freezing of the intermediate medium can be prevented.

[0076] In the fifth embodiment, a flow rate control unit including a temperature regulator 33 and a flow rate adjustment valve 34 may be provided, similar to the configuration shown in Fig. 4. A flow rate control unit 38 may be provided, similar to the configuration shown in Fig. 6. A pump control unit 39 may be provided, similar to the configuration shown in Fig. 7.

[0077] Although the description of other configurations, actions and effects will be omitted, the descriptions of the first to fourth embodiments can be applied to the fifth embodiment.

[0078] (Sixth embodiment) 16 shows the sixth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0079] As shown in Figure 16, the cold energy power generation system 10 of the sixth embodiment differs from the cold energy power generation system 10 shown in the fifth embodiment in that the stacked microchannel heat exchanger 20 constituting the liquefaction section 16 and the stacked microchannel mixer 43 constituting the mixing section 42 are integrally formed to form a single stacked microchannel device 50.

[0080] Specifically, as shown in Figures 17(a) to (d), the stacked microchannel device 50 has a first plate 51 in which a flow path is formed up to the middle position in the longitudinal direction, a second plate 52 in which a flow path is formed over the entire longitudinal direction, and a third plate 53 including a confluence plate 45, and these plates are stacked.

[0081] The first plate 51 is made up of a plate portion 51a that constitutes the low-temperature side plate 22 of the liquefaction section 16, and a plate portion 51b that is continuous with the low-temperature side plate 22 without forming a flow path.

[0082] The second plate 52 is composed of a plate portion 52a that constitutes the high-temperature side plate 21 of the liquefaction section 16 and a plate portion 52b that constitutes the main plate 44 of the mixing section 42. In other words, the second plate 52 has a flow path that connects the high-temperature side flow path 21a of the liquefaction section 16 and the liquid flow path 44a of the mixing section 42. The third plate 53 is composed of a plate portion 53a that constitutes the adjacent plate 31 and a plate portion 53b that constitutes the merging plate 45.

[0083] A gas flow path 47a is formed in the adjacent plate 31, and a second adjacent flow path 57a is formed in the confluence plate 45. A second extension flow path 57b is formed in the plate portion 52a constituting the high-temperature side plate 21 and the plate portion 53a constituting the adjacent plate 31. The second extension flow path 57b extends from the adjacent plate 31 of the third plate 53 to the high-temperature side plate 21 of the second plate 52, bridging the second adjacent flow path 57a and the high-temperature side flow path 21a. A second communication flow path 57 is formed by the second extension flow path 57b and the second adjacent flow path 57a.

[0084] A gas flow path 47a is formed in the confluence plate 45. An extension flow path 47b is formed extending from the confluence plate 45 of the third plate 53 to the main plate 44 of the second plate 52 so as to bridge the gas flow path 47a and the liquid flow path 44a of the main plate 44. The extension flow path 47b and the gas flow path 47a form a communication flow path 47 that connects the branch path 28 to the liquid flow path 44a.

[0085] Although the description of other configurations, actions, and effects will be omitted, the descriptions of the first to fifth embodiments can be applied to the sixth embodiment.

[0086] (Seventh embodiment) 18 shows the seventh embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0087] In the cold energy power generation system 10 of the seventh embodiment, the liquefaction section 16 is configured by a stacked microchannel heat exchanger 20, but this stacked microchannel heat exchanger 20 differs from the third embodiment in that the intermediate medium and the liquefied gas do not flow in opposite directions. That is, in the stacked microchannel heat exchanger 20 that configures the liquefaction section 16, the intermediate medium and the liquefied gas flow in the same direction. On the other hand, the mixing section 42 is configured by a stacked microchannel mixer 43, which is the same as the third embodiment.

[0088] In this embodiment, the mixer 42, which mixes the gaseous intermediate medium flowing through the branch path 28 with the liquid intermediate medium flowing out from the liquefaction unit 16, is configured using a laminated microchannel mixer 43. Therefore, the liquid intermediate medium introduced into the mixer 42 from the liquefaction unit 16 flows through each flow path in the laminated microchannel mixer 43. Therefore, uneven mixing is unlikely to occur when the gaseous intermediate medium flowing through the branch path 28 is mixed with the liquid intermediate medium in the flow path of the laminated microchannel mixer 43 through the communication flow path 47. In addition, a configuration is adopted in which a portion of the gaseous intermediate medium vaporized in the expansion turbine 15 is diverted before flowing into the liquefaction unit 16, and this portion of the intermediate medium is mixed with the liquid intermediate medium flowing out from the liquefaction unit 16. Therefore, it is possible to prevent a situation in which the liquid intermediate medium introduced from the liquefaction unit 16 and the gaseous intermediate medium introduced from the branch path 28 cannot come into uniform contact with each other, resulting in the gaseous intermediate medium flowing into the intermediate medium holding tank 17 without being completely liquefied and being sucked into the pump.

[0089] Although the description of other configurations, actions, and effects will be omitted, the descriptions of the first to sixth embodiments can be applied to the seventh embodiment.

[0090] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The present invention is not limited to the above-described embodiments, and various modifications and improvements are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0091] 10: Cold energy power generation system 13: Liquid pump 14:Heat exchanger 15: Expansion turbine 16: Liquefaction section 17: Intermediate medium holding tank 18: Generator 20: Stacked microchannel heat exchanger 21: High temperature plate 21a: High temperature side flow path 22: Low temperature plate 22a: Low temperature side flow path 28: Fork in the road 30: Connecting flow path 38: Flow control section 39: Pump control section 42: Mixing section 43: Stacked microchannel mixer 44: Main plate 44a:Liquid flow path 45: Merging plate 47: Connecting flow path 55: Connection road 57: Second communication channel

Claims

1. A liquefaction unit that performs heat exchange between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold heat of the liquefied gas; an intermediate medium holding tank for holding the liquid intermediate medium liquefied in the liquefaction unit; a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank; a heat exchanger that vaporizes the liquid intermediate medium pumped by the liquid pump; an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger; a branch passage for diverting a portion of the gaseous intermediate medium vaporized in the expansion turbine before it flows into the liquefaction section, the liquefaction unit is a counterflow type heat exchanger configured by stacking plates each having a flow path formed therein, and the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other while exchanging heat, the flow paths of the stacked microchannel heat exchanger include a high-temperature side flow path into which the gaseous intermediate medium flows and a low-temperature side flow path into which the liquefied gas flows; The stacked microchannel heat exchanger is provided with a communication passage that connects the branch passage to the high-temperature side passage.

2. A liquefaction unit that performs heat exchange between a liquefied gas and a gaseous intermediate medium and liquefies the gaseous intermediate medium using the cold heat of the liquefied gas; an intermediate medium holding tank for holding the liquid intermediate medium liquefied in the liquefaction unit; a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank; a heat exchanger that vaporizes the liquid intermediate medium pumped by the liquid pump; an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger; a branch passage for diverting a portion of the gaseous intermediate medium vaporized in the expansion turbine before it flows into the liquefaction section; a mixing section that mixes the gaseous intermediate medium that has flowed through the branch path with the liquid intermediate medium that has flowed out from the liquefaction section, the liquefaction unit is a counterflow type heat exchanger configured by stacking plates each having a flow path formed therein, and the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other while exchanging heat, the mixing section is configured by a stacked microchannel mixer configured by stacking plates in which flow paths are formed, the flow path of the laminated microchannel mixer includes a liquid flow path through which a liquid intermediate medium flowing out of the liquefaction section flows, The stacked microchannel mixer is provided with a communication passage that connects the branch passage to the liquid passage.

3. the flow paths of the stacked microchannel heat exchanger include a high-temperature side flow path into which the gaseous intermediate medium flows and a low-temperature side flow path into which the liquefied gas flows; a connecting passage connecting the branch passage to the stacked microchannel heat exchanger; The cold energy power generation system according to claim 2 , wherein the stacked microchannel heat exchanger is provided with a second communication passage that connects the connection passage to the high-temperature side passage.

4. The cold energy power generation system according to claim 2 , wherein the stacked microchannel heat exchanger constituting the liquefaction section and the stacked microchannel mixer constituting the mixing section are integrated together.

5. The cold energy power generation system according to claim 3 , wherein the stacked microchannel heat exchanger constituting the liquefaction section and the stacked microchannel mixer constituting the mixing section are integrated together.

6. a liquefaction unit that performs heat exchange between the liquefied gas and the gaseous intermediate medium and liquefies the gaseous intermediate medium by using the cold heat of the liquefied gas; an intermediate medium holding tank for holding the intermediate medium liquefied in the liquefaction unit; a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank; a heat exchanger that vaporizes the liquid intermediate medium pumped by the liquid pump; an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger; a branch passage for diverting a portion of the gaseous intermediate medium vaporized in the expansion turbine before it flows into the liquefaction section; a mixing section that mixes the gaseous intermediate medium that has flowed through the branch path with the liquid intermediate medium that has flowed out from the liquefaction section; Equipped with the mixing section is configured by a stacked microchannel mixer configured by stacking plates in which flow paths are formed, the flow path of the laminated microchannel mixer includes a liquid flow path through which a liquid intermediate medium flowing out of the liquefaction section flows, The stacked microchannel mixer is provided with a communication passage that connects the branch passage to the liquid passage.

7. A cold energy power generation system as described in any one of claims 1 to 6, further comprising a pump control unit that adjusts the discharge flow rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump.

8. A liquefaction unit that performs heat exchange between the liquefied gas and the gaseous intermediate medium and liquefies the gaseous intermediate medium by the cold heat of the liquefied gas; an intermediate medium holding tank for holding the liquid intermediate medium liquefied in the liquefaction unit; a liquid pump that pressurizes and discharges the liquid intermediate medium sucked from the intermediate medium holding tank; a heat exchanger that vaporizes the liquid intermediate medium pumped by the liquid pump; an expansion turbine connected to a generator and driven by the intermediate medium vaporized in the heat exchanger; the liquefaction unit is a counterflow type heat exchanger configured by stacking plates each having a flow path formed therein, and the liquefied gas and the gaseous intermediate medium flow in opposite directions to each other while exchanging heat, A cold energy power generation system comprising a pump control unit that adjusts the discharge flow rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure on the suction side of the liquid pump.

9. A cold energy power generation system as described in any one of claims 1 to 6, further comprising a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump.

10. A cold energy power generation system as described in claim 1, 3 or 5, which is provided with a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is higher than the freezing point of the intermediate medium.

11. a pump control unit that adjusts the discharge rate of the liquid pump so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than a saturation temperature of the intermediate medium corresponding to a measured value of pressure on the suction side of the liquid pump; A cold energy power generation system as described in claim 1, 3 or 5, further comprising a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is higher than the freezing point of the intermediate medium.

12. A cold energy power generation system as described in claim 1, 3 or 5, which is provided with a flow control unit that adjusts the flow rate of the gaseous intermediate medium passing through the branch path so that the temperature of the liquid intermediate medium flowing out of the liquefaction unit is lower than the saturation temperature of the intermediate medium corresponding to the measured pressure value on the suction side of the liquid pump and higher than the freezing point of the intermediate medium.

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