Cold energy utilization method and cold energy utilization apparatus

Abstract

The present invention makes it possible to effectively use the cold energy of a liquefied gas. A cold energy utilization apparatus 200 includes: a first heat exchange unit 300 that cools carbon dioxide N1 by heat exchange with an LNG; and a second heat exchange unit 400 that cools a brine N2 by heat exchange with the carbon dioxide N1. The cold energy utilization apparatus 200 is connected, upon use, to a plant 160 that includes a tank 110 for storing the LNG and a vaporizer 120 for vaporizing the LNG fed from the tank 110. The LNG is introduced from the tank 110 into the first heat exchange unit 300. The LNG introduced into the first heat exchange unit 300 is returned in a liquid state into the plant 160 on an upstream side of the vaporizer 120.

Description

Method and device for utilizing cold energy

[0001] The present invention relates to a method and an apparatus for utilizing cold energy.

[0002] Patent Document 1 discloses a vaporizer for vaporizing LNG (liquefied natural gas). The vaporizer is an open rack vaporizer (ORV) that includes multiple heat exchange panels, a lower manifold that connects the heat exchange panels in parallel at their lower ends, and an upper manifold that connects the heat exchange panels in parallel at their upper ends. Each heat exchange panel includes multiple heat transfer tubes extending vertically, a lower header pipe that connects the heat transfer tubes at their lower ends, and an upper header pipe that connects the heat transfer tubes at their upper ends. The vaporizer also includes a trough that stores seawater to be supplied to the outer surfaces of the heat transfer tubes, and seawater supply means that supplies seawater to the trough.

[0003] In such a vaporizer, LNG is introduced from the lower manifold into each heat transfer tube via a lower header pipe. Meanwhile, seawater stored in a trough by a seawater supply means overflows from the trough and hangs down while wetting the outer surfaces of the heat transfer tubes. The LNG introduced into the heat transfer tubes is heated and vaporized by seawater flowing outside the heat transfer tubes, becoming natural gas (NG), which rises inside the heat transfer tubes. This natural gas is then discharged to the upper manifold via an upper header pipe. In this way, the vaporizer of Patent Document 1 generates natural gas by heating and vaporizing LNG through heat exchange with seawater.

[0004] JP 2013-148253 A

[0005] In a typical plant, a tank for temporarily storing LNG is arranged upstream of the vaporizer of Patent Document 1, and the LNG delivered from this tank is vaporized by the vaporizer. Therefore, in such a plant, it is not possible to utilize the cold energy of the LNG stored in the tank, i.e., the LNG before it is vaporized by the vaporizer.

[0006] An object of the present invention is to provide a method and an apparatus for utilizing cold energy that can effectively utilize the cold energy of liquefied gas before it is vaporized.

[0007] Such an object can be achieved by the present invention described below.

[0008] (1) A method for utilizing cold energy, which is connected to a plant having a tank for storing liquefied gas, and which cools an object by heat exchange with the liquefied gas before it is stored in the tank.

[0009] (2) The plant has a receiving pipe that connects a carrier that transports the liquefied gas to the tank and guides the liquefied gas from the carrier to the tank, and the liquefied gas is introduced from the receiving pipe.

[0010] (3) The method for utilizing cold energy according to (1) above, comprising: a first heat exchange step of cooling a primary refrigerant by heat exchange with the liquefied gas; and a second heat exchange step of cooling a secondary refrigerant by heat exchange with the primary refrigerant.

[0011] (4) The method for utilizing cold energy according to (3) above, wherein the liquefied gas used in the first heat exchange step is returned to the plant in a liquid state.

[0012] (5) The method for utilizing cold energy according to (3) above, wherein the first heat exchange step includes: a primary refrigerant cooling step of cooling the primary refrigerant by heat exchange with the liquefied gas; and a condensing step of condensing the liquefied gas that has been at least partially gasified by the primary refrigerant cooling step.

[0013] (6) The method for utilizing cold energy according to (3) above, wherein the first heat exchange step further includes a decompression step of decompressing the liquefied gas prior to the primary refrigerant cooling step.

[0014] (7) The method for utilizing cold energy according to (5) above, wherein in the condensing step, the liquefied gas that has undergone the primary refrigerant cooling step is condensed by heat exchange with the liquefied gas that has not undergone the primary refrigerant cooling step.

[0015] (8) The method for utilizing cold energy according to (3) above, further comprising an object cooling step of cooling the object using the secondary refrigerant cooled in the second heat exchange step.

[0016] (9) The method for utilizing cold energy according to (8) above, further comprising a storage step of storing the object cooled in the object cooling step in a cooled state using the secondary refrigerant cooled in the second heat exchange step.

[0017] (10) The method for utilizing cold energy according to (8) above, wherein in the second heat exchange step, a part of the secondary refrigerant is frozen to form a slurry.

[0018] (11) The method for utilizing cold energy according to (9), wherein the object is a cold storage material, the object cooling step freezes the unfrozen cold storage material, and the storage step stores the cold storage material in a frozen state.

[0019] (12) The method for utilizing cold energy according to (1) above, wherein the liquefied gas is liquefied natural gas or liquefied petroleum gas.

[0020] (13) A cold energy utilization device that is used in connection with a plant having a tank for storing liquefied gas, and that cools an object by heat exchange with the liquefied gas before it is stored in the tank.

[0021] According to the cold energy utilization method and cold energy utilization device of the present invention, it is possible to cool various objects using the cold energy of liquefied gas before vaporization, which has not been used until now. Therefore, the cold energy of liquefied gas can be effectively utilized without being wasted. Furthermore, by effectively utilizing the cold energy that has not been used until now, consumption of other energy sources can be reduced, thereby reducing the environmental load.

[0022] FIG. 1 is an overall configuration diagram of a cold energy utilization device according to a first embodiment. FIG. 2 is a diagram showing a second heat exchange unit. FIG. 3 is a diagram showing a cooling device. FIG. 4 is a diagram showing a cooling device. FIG. 5 is a diagram showing a storage device. FIG. 6 is a diagram showing an example of a method of using a cold storage material. FIG. 7 is a diagram showing an example of a method of using a cold storage material. FIG. 8 is an overall configuration diagram of a cold energy utilization device according to a second embodiment. FIG. 9 is a cross-sectional view showing a second heat exchanger according to a third embodiment.

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for utilizing cold energy according to the present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

[0024] The liquefied gas used in the cold energy utilization method and cold energy utilization device of the present invention is not particularly limited, but is typically LNG (liquefied natural gas) or LPG (liquefied petroleum gas). These are particularly consumed in large quantities among liquefied gases, and therefore a large amount of cold energy is wasted. This makes the cold energy utilization method and cold energy utilization device more beneficial. However, the liquefied gas may be anything other than LNG or LPG, such as ammonia gas or hydrogen gas. For convenience of explanation, the following embodiments will be described using LNG as the liquefied gas, but other liquefied gases can be used in the same manner.

[0025] First Embodiment First, a brief description will be given of a method for supplying natural gas (NG) in Japan. Japan relies on imports for most of its NG. Furthermore, since there are no pipelines between Japan and its NG producing countries, the NG is imported by sea. In order to improve transportation efficiency, the NG is converted into LNG (liquefied natural gas) at approximately -162°C in a liquefaction plant installed in a natural gas field, and then transported to a receiving terminal 100 using an LNG tanker T (mobile body).

[0026] 1 , a receiving terminal 100 is equipped with a plant 160, which mainly includes a tank 110 for temporarily storing LNG transported by an LNG tanker T, a receiving pipe 170 for guiding LNG from the LNG tanker T to the tank 110, a vaporizer 120 for vaporizing the LNG stored in the tank 110 to produce a required amount of NG, a pipeline 130 connecting the tank 110 and the vaporizer 120, a pump 140 disposed in the pipeline 130 for delivering the LNG in the tank 110 to the vaporizer 120, and an odorizer 150 for adding an odor to the NG produced by the vaporizer 120. Although not shown, the NG odorized by the odorizer 150 is sent through gas pipes to gas holders installed in various locations such as urban areas, where it is stored, and is then sent from the gas holders through gas pipes to each contracted party.

[0027] The illustrated receiving terminal 100 extends from land to the ocean and has a pier where large LNG tankers can be docked, with a receiving pipe 170 extending to the tip of the pier. By connecting the receiving pipe 170 to the LNG tanker T docked at the pier, the LNG tanker T and the tank 110 are connected by the receiving pipe 170, and LNG is guided from the LNG tanker T to the tank 110 through the receiving pipe 170.

[0028] As shown in Fig. 1, the cold energy utilization device 200 is used by being connected to the plant 160. In particular, the cold energy utilization device 200 is connected midway through the receiving pipe 170. The cold energy utilization device 200 has a first heat exchange unit 300 that cools a primary refrigerant by heat exchange with LNG introduced from the receiving pipe 170, a second heat exchange unit 400 that cools a secondary refrigerant by heat exchange with the primary refrigerant, a cooling device 500 that cools an object by heat exchange with the secondary refrigerant, and a storage device 600 that maintains the cooled state of the object cooled by the cooling device 500 using the secondary refrigerant.

[0029] First, a description will be given of the first heat exchange unit 300. The first heat exchange unit 300 mainly includes a first heat exchanger 310 that exchanges heat between the LNG introduced from the plant 160 and a primary refrigerant, HFC (hydrofluorocarbon), and a condenser 320 that condenses the LNG vaporized in the first heat exchanger 310.

[0030] The first heat exchanger 310 has an outer pipe 311 and an inner pipe 312 disposed to penetrate the outer pipe 311. HFC is introduced into the outer pipe 311, and LNG is introduced into the inner pipe 312, whereby heat exchange occurs and the HFC is condensed.

[0031] The condenser 320 has the same configuration as the above-described first heat exchanger 310. That is, the condenser 320 has an outer pipe 321 and an inner pipe 322 arranged to penetrate the outer pipe 321. Gaseous LNG that has passed through the first heat exchanger 310 is introduced into the outer pipe 321, and liquid LNG that has not passed through the first heat exchanger 310 is introduced into the inner pipe 322, whereby heat exchange occurs between them and the gaseous LNG that has passed through the first heat exchanger 310 is condensed.

[0032] As shown in FIG. 1 , the receiving pipe 170 is connected to the inlet side of the inner pipe 312 by a pipe 331. A liquid feed pump 340 and an expansion valve 350 are provided in the pipe 331. The pipe 331 branches into a pipe 334 between the liquid feed pump 340 and the expansion valve 350, and the downstream side of the pipe 334 is connected to the inlet side of the inner pipe 322. In other words, the pipe 334 bypasses the receiving pipe 170 and the condenser 320 without passing through the first heat exchanger 310. A flow control valve 360 ​​that adjusts the amount of LNG supplied to the condenser 320 is provided in the pipe 334. The outlet side of the inner pipe 312 is connected to the inlet side of the outer pipe 321 by a pipe 332. The outlet sides of the outer pipe 321 and the inner pipe 322 are joined by a pipe 333 and then connected to the receiving pipe 170.

[0033] A first heat exchange step is performed in the first heat exchange unit 300 configured as described above. In the first heat exchange step, by operating the liquid feed pump 340, at least a portion of the LNG traveling through the receiving pipe 170 toward the tank 110 branches off into the pipe line 331 and flows through the pipe line 331. A portion of the LNG is depressurized by the expansion valve 350 and introduced into the inner pipe 312 of the first heat exchanger 310, and the remainder is introduced into the inner pipe 322 of the condenser 320 via the pipe line 334. At this time, the amount of LNG introduced into the inner pipe 322 is adjusted by the flow rate control valve 360. The LNG introduced into the inner pipe 312 vaporizes in the inner pipe 312 and absorbs heat from the gaseous HFC introduced into the outer pipe 311, and is discharged from the inner pipe 312 in an at least partially gasified state, in this embodiment, in an entirely gasified state. By reducing the pressure of the LNG using the expansion valve 350 before introducing it into the inner pipe 312, the LNG is more likely to vaporize in the inner pipe 312, improving cooling efficiency. Meanwhile, the HFC in the outer pipe 311 loses heat to the LNG introduced into the inner pipe 312, condenses, and liquefies, and is then discharged from the outer pipe 311. With this first heat exchanger 310, the ultra-low temperature LNG of -162°C is used, so that the HFC can be efficiently condensed and liquefied. This step is the depressurization step and the primary refrigerant cooling step.

[0034] The gaseous LNG discharged from the inner pipe 312 is introduced into the outer pipe 321 of the condenser 320 via the pipe 332. The liquid LNG directly introduced into the inner pipe 322 from the tank 110 via the pipe 334 absorbs heat from the gaseous LNG introduced into the outer pipe 321 and is discharged from the inner pipe 322 in a liquid state. Meanwhile, the gaseous LNG introduced into the outer pipe 321 absorbs heat from the liquid LNG introduced into the inner pipe 322, condenses, and is liquefied, and then discharged from the outer pipe 321. The liquid LNG discharged from the inner pipe 322 and the liquid LNG discharged from the outer pipe 321 merge midway through the pipe 333 and then merge into the receiving pipe 170. The condenser 320 described above allows the gasified LNG to be easily returned to a liquid state. This step is the condensation step.

[0035] For the sake of convenience, FIG. 1 shows gaseous (G) and liquid (L).

[0036] The first heat exchange unit 300 configured as described above can return substantially all of the LNG borrowed from the plant 160 in liquid form to the plant 160. Therefore, the amount of LNG is not substantially reduced, and the production volume of LNG is not reduced. Furthermore, the cold energy of the LNG can be extracted without substantially consuming the LNG. This results in an excellent heat exchange unit with low environmental impact. Furthermore, since the first heat exchange unit 300 simply connects the pipeline 331 for borrowing LNG from the plant 160 and the pipeline 333 for returning the borrowed LNG to the plant 160 to the receiving piping 170, the processing process of the plant 160 can remain the same as before. Therefore, the first heat exchange unit 300 can be introduced into the existing plant 160 without requiring major repairs or modifications. Therefore, the introduction cost of the cold energy utilization device 200 is extremely low. Furthermore, in the condenser 320, the heat of the gaseous LNG introduced into the outer tube 321 is absorbed by the liquid LNG introduced into the inner tube 322, which also contributes to reducing the environmental load.

[0037] The first heat exchange unit 300 has been described above. However, the configuration of the first heat exchange unit 300 is not particularly limited as long as it can cool the HFC, which is the primary refrigerant, using LNG. The configuration of the condenser 320 is also not particularly limited as long as it can condense gasified LNG. The junction point between the pipeline 333 and the plant 160 is not particularly limited. For example, in the present embodiment, when liquid LNG is returned to the plant 160, it may be the tank 110 or between the tank 110 and the vaporizer 120. For example, the condenser 320 may be omitted and gaseous LNG may be returned to the plant 160. In this case, the junction point between the pipeline 333 and the plant 160 is not particularly limited. For example, it may be the tank 110, between the tank 110 and the vaporizer 120, or between the vaporizer 120 and the odorizer 150.

[0038] [Second Heat Exchange Unit 400] Next, the second heat exchange unit 400 will be described. As shown in FIG. 1 , the second heat exchange unit 400 mainly includes a second heat exchanger 410 that freezes a portion of the secondary refrigerant, an ethanol aqueous solution (referred to as "EtOH" in the figure), through heat exchange with the primary refrigerant, an HFC, to produce ice slurry I, and a storage tank 420 that stores the produced ice slurry I. The ice slurry I refers to sherbet-like ice in which fine ice crystals are mixed in an ethanol aqueous solution, and is also referred to as "slurry ice," "ice slurry," or "slurry ice." The ethanol concentration of the ethanol aqueous solution is not particularly limited, but is preferably 45% or higher, and more preferably 50% or higher, when used for the purpose of this embodiment (freezing and storage of the cold storage material 800, described below). This results in a freezing point of the ethanol aqueous solution of -35°C or lower. This lowers the temperature of the ice slurry I, which allows the cold storage material 800 to freeze more quickly, as described below.

[0039] As shown in FIG. 2 , the second heat exchanger 410 has an outer pipe 411 and an inner pipe 412 arranged coaxially inside the outer pipe 411. The outer pipe 411 and the inner pipe 412 are installed upright, with their axes facing vertically. In other words, the second heat exchanger 410 is a vertically placed double-pipe evaporator. The outer pipe 411 and the inner pipe 412 each have an inlet provided at their lower end and an outlet provided at their upper end. The liquid HFC condensed in the first heat exchanger 310 is introduced into the outer pipe 411, and the ethanol aqueous solution is introduced into the inner pipe 412, whereby heat exchange occurs and the ethanol aqueous solution is cooled.

[0040] Storage tank 420 has an inlet for introducing the ethanol aqueous solution cooled by second heat exchanger 410, and an outlet for discharging the ethanol aqueous solution in the tank toward second heat exchanger 410. Storage tank 420 also has an agitator (not shown) for agitating ice slurry I in the tank. Agitating ice slurry I with the agitator can prevent the ice slurry I from coagulating in storage tank 420.

[0041] The outlet side of outer pipe 411 is connected to the inlet side of outer pipe 311 by pipe 441, and the outlet side of outer pipe 311 is connected to the inlet side of outer pipe 411 by pipe 442. A liquid feed pump 450 and an expansion valve 460 are provided in pipe 442. The outlet side of inner pipe 412 is connected to the inlet side of storage tank 420 by pipe 443, and the outlet side of storage tank 420 is connected to the inlet side of inner pipe 412 by pipe 444. A liquid feed pump 470 is provided in pipe 444.

[0042] The second heat exchange unit 400 configured as described above performs a second heat exchange step. In the second heat exchange step, the liquid feed pump 450 operates to circulate the HFC between the outer pipe 411 and the outer pipe 311 via the pipes 441 and 442. The liquid HFC condensed in the first heat exchanger 310 is depressurized by the expansion valve 460 and then introduced into the outer pipe 411. The HFC introduced into the outer pipe 411 absorbs heat from the aqueous ethanol solution flowing through the inner pipe 412 while vaporizing within the pipe, and is discharged from the outer pipe 411 in a gasified state at least partially, and in this embodiment, entirely. The gaseous HFC discharged from the outer pipe 411 is again condensed and liquefied by the first heat exchanger 310. By circulating the HFC in this manner, the aqueous ethanol solution can be continuously cooled in the second heat exchanger 410. By reducing the pressure of the HFC by the expansion valve 460 before introducing it into the outer tube 411, the HFC becomes more likely to vaporize in the outer tube 411, and the cooling efficiency is improved.

[0043] While the HFC is circulating in this manner, the liquid feed pump 470 is operated to circulate the ethanol aqueous solution between the inner pipe 412 and the storage tank 420 via the pipes 443 and 444. This causes the ethanol aqueous solution to be continuously cooled in the second heat exchanger 410, gradually generating fine ice in the ethanol aqueous solution, thereby producing ice slurry I. The produced ice slurry I is stored in the storage tank 420. With this second heat exchange unit 400, the ice slurry I can be produced efficiently.

[0044] If ice grows on the inner wall of inner pipe 412 during the production of ice slurry I, the circulation of the ethanol aqueous solution may slow down, potentially reducing the efficiency of production of ice slurry I. Therefore, inner pipe 412 may be provided with a rotating blade for scraping off ice adhering to the inner wall, or with an agitator for agitating the ethanol aqueous solution flowing inside inner pipe 412 to make it difficult for ice to adhere to the inner wall. Another effect is that these rotating blades or agitators cause convection in the ethanol aqueous solution flowing inside inner pipe 412, improving the efficiency of heat exchange between the HFC and the ethanol aqueous solution.

[0045] Although the second heat exchange unit 400 has been described above, the configuration of the second heat exchange unit 400 is not particularly limited as long as it can cool the secondary refrigerant using the primary refrigerant.

[0046] The primary refrigerant is not limited to HFC, and any refrigerant may be used as long as it can be cooled by LNG (liquefied gas) and can cool the secondary refrigerant. For example, natural refrigerants (gases) such as HCFC (hydrochlorofluorocarbon), HFO (hydrofluoroolefin), propane, propylene, butane, isobutane, hexafluoropropane, heptafluoropropane, ammonia, and carbon dioxide (carbon dioxide) may be used. For example, the primary refrigerant can be changed as appropriate depending on the types of liquefied gas and secondary refrigerant used in the cold energy utilization device 200.

[0047] The secondary refrigerant is not limited to an ethanol aqueous solution, and may be any refrigerant that can be cooled by the primary refrigerant and can cool an object. For example, various alcohols such as ethylene glycol and propylene glycol, or their aqueous solutions, sugar water, sodium chloride aqueous solution (brine water), calcium chloride aqueous solution, etc. may be used. For example, the secondary refrigerant can be changed as appropriate depending on the type of primary refrigerant and object used in the cold energy utilization device 200.

[0048] [Cooling Device 500] The cooling device 500 freezes the target cold storage material 800 by heat exchange with an ethanol aqueous solution. The cold storage material 800 is a container containing a cold pack, and the container may be a flexible soft type or a hard type. The cold storage material 800 is also called a cold insulator. The difference between a cold storage material and a cold insulator is not clear, but it is said that a cold storage material is one whose cold storage component is mostly water and freezes at a few degrees below freezing, while a cold storage material is one whose cold storage component uses chemicals and freezes at or below -10 degrees Celsius.

[0049] As shown in FIG. 3 , the cooling device 500 includes a cooling tank 510 in which ice slurry I is stored. Unfrozen cold storage material 800 is cooled and frozen by immersing it in the ice slurry I in the cooling tank 510. The ice slurry I (a partially frozen secondary refrigerant) maintains the temperature of the ice slurry I near the freezing point of the ethanol aqueous solution until the ice components melt due to the action of latent heat. Because the heat of fusion required to turn a solid into a liquid is higher than the specific heat of the liquid, the inside of the cooling tank 510 can be maintained at a low temperature for a longer period of time, allowing the cold storage material 800 to be efficiently frozen. This step is the object cooling step.

[0050] Cooling tank 510 is connected to storage tank 420 by pipes 521 and 522, and ice slurry I in storage tank 420 circulates between cooling tank 510 and ice slurry I. Specifically, the ethanol aqueous solution melted by heat exchange with cold storage material 800 is returned to storage tank 420 via pipe 521, and fresh ice slurry I in storage tank 420 is supplied to cooling tank 510 via pipe 522, thereby maintaining the ice slurry I in cooling tank 510 at a predetermined amount or more. Therefore, ice slurry I is not depleted from cooling tank 510, and unfrozen cold storage material 800 can be continuously and efficiently frozen.

[0051] The cooling device 500 is also provided with shelves 530 that can be raised and lowered above the cooling tank 510. Unfrozen cold storage materials 800 are arranged on the shelves 530, and each shelf 530 is immersed in ice slurry I as shown in FIG. 4 , thereby making it possible to freeze multiple cold storage materials 800 in the shelves 530 collectively. This facilitates the freezing operation. Note that the operations of arranging the unfrozen cold storage materials 800 on the shelves 530, immersing the shelves 530 in ice slurry I, and recovering the frozen cold storage materials 800 from the shelves 530 may be performed by an operator or automatically by a machine.

[0052] The cooling device 500 has been described above, but the configuration of the cooling device 500 is not particularly limited as long as it can freeze the cold storage material 800 using the ice slurry I. For example, the storage tank 420 and the cooling tank 510 may not be connected, and an operator may transport the ice slurry I in the storage tank 420 to the cooling tank 510.

[0053] Furthermore, the object to be cooled with the ice slurry I is not limited to the cold storage material 800, but may be anything that requires cooling, such as liquids such as water and salt water, foods such as raw meat, seafood, vegetables, and fruits, organs, medicines, etc. Furthermore, the object does not need to be frozen.

[0054] [Storage Device 600] The storage device 600 is a freezer that uses the cold energy of the ice slurry I to maintain the frozen state of the regenerator material 800 frozen by the cooling device 500.

[0055] As shown in Figure 5, the storage device 600 has a storage chamber 610 that stores the frozen cold storage material 800, and a storage chamber 620 that is adjacent to the storage chamber 610 and stores the ice slurry I. A wall 630 that separates the storage chamber 610 from the storage chamber 620 is made of a material with a high thermal conductivity, such as aluminum or stainless steel. Therefore, the cold energy of the ice slurry I stored in the storage chamber 620 is efficiently transferred to the storage chamber 610 through the wall 630. This cools the storage chamber 610, and the frozen state of the cold storage material 800 in the storage chamber 610 is maintained. This step is the storage step.

[0056] The storage chamber 620 is connected to the storage tank 420 by pipes 641 and 642, and the ice slurry I in the storage tank 420 circulates between the storage chamber 620 and the ice slurry I. Specifically, the ethanol aqueous solution melted by heat exchange with the storage chamber 610 is returned to the storage tank 420 via pipe 641, and fresh ice slurry I in the storage tank 420 is supplied to the storage chamber 620 via pipe 642, thereby maintaining the ice slurry I in the storage chamber 620 at a predetermined amount or more. Therefore, the ice slurry I is not depleted from the storage chamber 620, the storage chamber 610 can be continuously and efficiently cooled, and the frozen state of the cold storage material 800 is more reliably maintained.

[0057] The storage device 600 has been described above, but the configuration of the storage device 600 is not particularly limited as long as it can maintain the frozen state of the cold storage material 800 using the ice slurry I. For example, similar to the cooling device 500, the cold storage material 800 may be immersed in the ice slurry I to maintain the frozen state of the cold storage material 800. Also, for example, the storage tank 420 and the storage chamber 620 may not be connected, and an operator may transport the ice slurry I in the storage tank 420 to the storage chamber 620. Also, the configuration may be such that the cold storage material 800 frozen in the cooling device 500 is automatically transported to the storage chamber 610 by a conveyor or the like.

[0058] In this way, the cooling device 500 and the storage device 600 consume ice slurry I to freeze and store the cold storage material 800. However, by generating ice slurry I in the second heat exchange unit 400 in an amount equal to or greater than this consumption, the ice slurry I in the cooling device 500 and the storage device 600 will not run out. Furthermore, the ethanol aqueous solution itself only repeatedly changes state between liquid and slurry within the device, and the absolute amount does not substantially decrease. In this way, by repeatedly generating and consuming ice slurry I within the device, there is no need to replenish the ethanol aqueous solution, making maintenance easier. Furthermore, the cold energy utilization device 200 has excellent energy efficiency.

[0059] The frozen ice storage material 800 stored in the storage device 600 in the above manner is transported to a required location using, for example, a refrigerated truck and used at the destination. The destination and use of the ice storage material 800 are not particularly limited, and examples include cooling food (suppressing temperature rise) and room air conditioning. Specifically, as shown in FIG. 6 , the frozen ice storage material 800 may be stored together with food F in an insulated case 700. This suppresses temperature rise in the food, allowing the food to remain fresh for a longer period of time. Furthermore, for example, as shown in FIG. 7 , the frozen ice storage material 800 may be placed in a building B. The room can be air-conditioned by introducing air cooled by the cold energy of the ice storage material 800 into the room. However, the method of cooling the food and the method of air-conditioning the room are not particularly limited.

[0060] The cold storage material 800 that has been used for cooling and melted is recovered by various means, frozen again by the cooling device 500, and stored in the frozen state in the storage device 600. By establishing a circulation cycle for the cold storage material 800 in this way, virtually no hardware (materials) are discarded, resulting in the cold energy utilization device 200 having an extremely small environmental impact. This further increases the value of the cold energy utilization device 200.

[0061] The above describes the cold energy utilization device 200. However, the configuration of the cold energy utilization device 200 is not particularly limited as long as it can cool the cold storage material 800 by heat exchange with the LNG before it is stored in the tank 110. For example, the primary refrigerant may be omitted, and heat exchange may be performed directly between the LNG introduced from the receiving pipe 170 and the secondary refrigerant. Furthermore, for example, a plurality of first heat exchangers 310, condensers 320, second heat exchangers 410, and storage tanks 420 may be provided in parallel or in series. This can increase processing capacity. Furthermore, the installation location of the cold energy utilization device 200 is not particularly limited, and it may be outside the receiving terminal 100, and of course, it may be in a country other than Japan.

[0062] Furthermore, the point at which the cold energy utilization device 200 is connected to the plant 160 is not particularly limited as long as it can use the LNG before it is introduced into the tank 110. For example, it may be connected between an LNG tanker and the receiving pipe 170, or between the receiving pipe 170 and the tank 110.

[0063] Second Embodiment A cold energy utilization device 200 according to this embodiment is similar to the cold energy utilization device 200 according to the first embodiment, except that it has a tank 180 for storing LNG. In the following description, the cold energy utilization device 200 according to this embodiment will be described mainly with respect to differences from the first embodiment, and a description of similar points will be omitted. In addition, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0064] As shown in FIG. 8 , in the cold energy utilization apparatus 200 of this embodiment, a tank 180 for temporarily storing LNG introduced from the receiving pipe 170 is provided in the pipeline 331, upstream of the liquid feed pump 340. Although this varies depending on the size of the receiving terminal 100 and the amount of LNG consumed, LNG is generally supplied from an LNG tanker approximately once a week or once every two weeks. Therefore, in the first embodiment described above, there is a risk that ice slurry I can only be produced at that timing. In contrast, by providing the tank 180 for temporarily storing LNG as in this embodiment, ice slurry I can be continuously produced using the LNG stored in the tank 180 even when LNG is not being supplied from the LNG tanker. This extends the operable time of the cold energy utilization apparatus 200.

[0065] The second embodiment can also achieve the same effects as the first embodiment.

[0066] Third Embodiment The cold energy utilization device 200 according to this embodiment is similar to the cold energy utilization device 200 according to the first embodiment, except for the configuration of the second heat exchanger 410. In the following description, the cold energy utilization device 200 according to this embodiment will be described mainly with reference to the differences from the first embodiment, and a description of similar points will be omitted. In the drawings of this embodiment, the same reference numerals are used to designate similar components to those in the above-described embodiments.

[0067] As shown in Figure 9, the second heat exchanger 410 is composed of a flake ice manufacturing device 900. The flake ice manufacturing device 900 is a device for producing flake ice and includes a drum 910, a rotating shaft 920, a spray unit 930, a blade 950, and a storage tank 970. A spiral pipe 911 through which HFC (primary refrigerant) circulates is embedded within the drum 910. The inner circumferential surface of the drum 910 is cooled by the HFC circulating within the pipe 911. The rotating shaft 920 is disposed on the central axis of the drum 910 and rotates about the central axis by a drive source (not shown), such as a motor.

[0068] The spray unit 930 is fixed to the rotating shaft 920 and rotates together with the rotating shaft 920. The spray unit 930 sprays salt water toward the inner circumferential surface of the drum 910. The salt water sprayed from the spray unit 930 adheres to the inner circumferential surface of the drum 910, which has been cooled by the HCF, and instantly freezes into ice. The blade 950 is fixed to the rotating shaft 920 and rotates together with the rotating shaft 920, thereby scraping off ice formed on the inner circumferential surface of the drum 910. The scraped ice then falls downward as flake ice and is stored in a storage tank 970 located directly below the drum 910. The flake ice stored in the storage tank 970 is then used for cooling in the cooling device 500 and the storage device 600.

[0069] The third embodiment can also achieve the same effects as the first embodiment.

[0070] The cold energy utilization method and cold energy utilization device of the present invention have been described above based on the illustrated embodiments, but the present invention is not limited to these, and the configuration of each part can be replaced with any configuration having a similar function. Furthermore, any other components or any steps may be added to the present invention. Furthermore, each embodiment may be combined as appropriate.

[0071] In addition, in the above-described embodiment, the second heat exchanger 410 is described as producing slurry ice and flake ice, but the form of the ice is not particularly limited, and may be, for example, cube-shaped or block-shaped ice.

[0072] The cold energy utilization method of the present invention is connected to a plant having a tank for storing liquefied gas, and cools an object by heat exchange with the liquefied gas before it is stored in the tank. The cold energy utilization device of the present invention is connected to a plant having a tank for storing liquefied gas, and cools an object by heat exchange with the liquefied gas before it is stored in the tank. According to this invention, various objects can be cooled using the cold energy of liquefied gas before it is vaporized, which has not been used before. Therefore, the cold energy of the liquefied gas can be effectively utilized without being wasted. Furthermore, by effectively utilizing the cold energy that has not been used before, consumption of other energy sources can be reduced, thereby reducing the environmental load. Therefore, the cold energy utilization method and cold energy utilization device of the present invention have industrial applicability.

[0073] 100...receiving terminal, 110...tank, 120...evaporator, 130...pipe, 140...pump, 150...odorizer, 160...plant, 170...receiving piping, 180...tank, 200...cold energy utilization device, 300...first heat exchange unit, 310...first heat exchanger, outer pipe...shell, 312...inner pipe, 320...condenser, 321...outer pipe, 322...inner pipe, 331...pipe, 332...pipe, 333...pipe, 333a...pipe, 333b...pipe, 333c...pipe, 334...pipe, 340...liquid feed pump, 350...expansion valve, 360...flow rate adjustment valve, 380...valve, 390...liquid feed pump, 400...second heat exchange unit, 4 10...second heat exchanger, 411...outer pipe, 412...inner pipe, 420...storage tank, 441...pipe, 442...pipe, 443...pipe, 444...pipe, 450...liquid feed pump, 460...expansion valve, 470...liquid feed pump, 500...cooling device, 510...cooling tank, 511...cooling tank, 521...pipe, 522...pipe, 530...shelf, 600...storage device, 610...storage room, 620...storage room, 630...wall, 641...pipe, 642...pipe, 700...thermal insulation case, 800...cold storage material, 900...flake ice production device, 910...drum, 911...piping, 920...rotating shaft, 930...spray section, 950...blade, 970...storage tank, I...ice slurry

Claims

1. A method for utilizing cold energy, which is connected to a plant having a tank for storing liquefied gas, and which cools an object by heat exchange with the liquefied gas before it is stored in the tank.

2. The method of utilizing cold energy as described in claim 1, wherein the plant has a receiving pipe that connects a carrier that transports the liquefied gas to the tank and guides the liquefied gas from the carrier to the tank, and the liquefied gas is introduced from the receiving pipe.

3. A method for utilizing cold energy as described in claim 1, comprising: a first heat exchange step of cooling a primary refrigerant by heat exchange with the liquefied gas; and a second heat exchange step of cooling a secondary refrigerant by heat exchange with the primary refrigerant.

4. A method for utilizing cold energy as described in claim 3, wherein the liquefied gas used in the first heat exchange step is returned to the plant in a liquid state.

5. The method for utilizing cold energy described in claim 3, wherein the first heat exchange step includes: a primary refrigerant cooling step of cooling the primary refrigerant by heat exchange with the liquefied gas; and a condensing step of condensing the liquefied gas, at least a portion of which has been gasified by the primary refrigerant cooling step.

6. A method for utilizing cold energy as described in claim 5, wherein the first heat exchange step further includes a depressurization step of depressurizing the liquefied gas prior to the primary refrigerant cooling step.

7. A method for utilizing cold energy as described in claim 5, wherein in the condensation step, the liquefied gas that has undergone the primary refrigerant cooling step is condensed by heat exchange with the liquefied gas that has not undergone the primary refrigerant cooling step.

8. The method for utilizing cold energy according to claim 3, further comprising an object cooling step of cooling the object using the secondary refrigerant cooled in the second heat exchange step.

9. A method for utilizing cold energy as described in claim 8, further comprising a storage step of storing the object cooled in the object cooling step in a cooled state using the secondary refrigerant cooled in the second heat exchange step.

10. A method for utilizing cold energy as described in claim 8, wherein in the second heat exchange step, a portion of the secondary refrigerant is frozen to form a slurry.

11. The method for utilizing cold energy as described in claim 9, wherein the object is a cold storage material, and in the object cooling step, the unfrozen cold storage material is frozen, and in the storage step, the cold storage material is stored in a frozen state.

12. The method for utilizing cold energy as described in claim 1, wherein the liquefied gas is liquefied natural gas or liquefied petroleum gas.

13. A cold energy utilization device that is connected to a plant having a tank for storing liquefied gas, and that cools an object by heat exchange with the liquefied gas before it is stored in the tank.

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