Cooling system for low-temperature industry using cold heat of LNG liquefied gas

Abstract

The present invention relates to a cooling system for a low-temperature industry in which cold heat of LNG liquefied gas is used, and more specifically, is configured to cool a refrigerant by using the heat from vaporization of LNG liquefied gas and cool data centers and warehouses in a cold chain and the like by using the latent heat of the refrigerant, and thus can provide ease of maintenance and reduce the operating cost of the cooling system. According to the present invention, the refrigerant is sequentially cooled by using the vaporization heat of the LNG liquefied gas, and the liquefied gas is gradually increased in temperature using the latent heat of the refrigerant and thereby discharged as vaporized gas, thus having the effect of improving the cold heat utilization of the liquefied gas. Further, the refrigerant is liquefied by heat exchange between the vaporization heat of the LNG liquefied gas and the refrigerant, and the utilization of the latent heat of the refrigerant reduces power costs and carbon emissions as compared to conventional cooling systems using a refrigeration cycle, thus having the effect of improving environmental protection. In addition, a liquefied gas transfer line and a latent heat exchange unit are formed in a heat source-side area, and the cooling system is configured to be relatively simply connected to a relatively distant warehouse by a refrigerant circulation line, thus having the effect of improving product competitiveness, such as by reducing design and construction costs, and reliability.

Description

Cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas

[0001] The present invention relates to a cooling system for low-temperature industries utilizing the cold heat of LNG liquefied gas, and more specifically, to a system that utilizes the heat of vaporization of LNG liquefied gas to cool a refrigerant and utilizes the latent heat of the refrigerant to cool a logistics warehouse such as a data center and a cold chain, thereby enabling the convenience of maintenance of the cooling system and reduction of operating costs.

[0002] Typically, logistics warehouses for cold chain operations are equipped with cooling systems that include refrigerated / frozen warehouses for refrigerated or frozen storage of agricultural products, fish, meat, etc., and data centers require cooling systems for cooling large-capacity servers.

[0003] In recent cooling systems, LNG liquefied gas is used as an eco-friendly energy source, and LNG liquefied gas bases with a number of LNG liquefied gas storage tanks have been built on the coast to utilize the LNG liquefied gas.

[0004] LNG liquefied gas storage tanks store liquefied LNG gas, and in order to supply an appropriate amount of LNG gas to demanders, the liquefied gas is vaporized and then supplied to demanders (city gas lines, etc.). In line with eco-friendly, decentralized energy policies, the paradigm of energy use is changing, with a growing need for small-scale LNG satellite bases.

[0005] To vaporize the above LNG liquefied gas, a vaporizer is typically used, and the vaporizer receives water from the outside and exchanges heat to cause the LNG liquefied gas to undergo a phase change and be transmitted as a gas at room temperature.

[0006] To operate such a vaporizer, a large amount of water is required, and there was a problem in that a large amount of power was consumed for the liquid pump and driving to supply this large amount of water.

[0007] Additionally, a separate tank can be provided to supply water to the vaporizer and the water stored in this tank can be circulated to the vaporizer, but most often, seawater is used to vaporize LNG liquefied gas.

[0008] In addition, there was a problem that when circulating water stored in a tank to a vaporizer, a heater was required to heat the water stored in the tank, and electricity was also required to drive the heater, resulting in a huge amount of electricity consumption for the operation of the vaporizer.

[0009] Accordingly, as presented in Korean Patent No. 10-0981398, a cooling system was proposed that uses a sensible heat utilization system that does not involve phase change, where the secondary refrigerant circulates to the load side after heat exchange with LNG.

[0010] In this way, in the cooling system that was previously used, the temperature of the vaporized NG gas was raised to 0℃ or higher by using a seawater vaporizer, which had the problem of low heat recovery rate and difficulty in utilizing the heat of the liquefied gas.

[0011] In addition, the cooling system using sensible heat requires a secondary refrigerant, so lines, valves, and heat exchangers to store it must be installed in duplicate, which increases the cost of installation and management, and there is an inconvenience in increasing the temperature in stages.

[0012] In order to solve the problems of the prior art as described above, the present invention provides a cooling system for low-temperature industries utilizing the cold heat of LNG liquefied gas, which can sequentially cool a refrigerant by utilizing the heat of vaporization of LNG liquefied gas and increase the temperature of the liquefied gas by utilizing the latent heat in stages.

[0013] In addition, the present invention aims to provide a cooling system for low-temperature industries that utilizes the cold heat of LNG liquefied gas, which can improve environmental protection by liquefying the refrigerant by exchanging heat between the vaporization heat of LNG liquefied gas and the refrigerant and reducing electricity costs and carbon emissions by utilizing the latent heat of the refrigerant.

[0014] In addition, the present invention aims to provide a cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas, which can reduce design and construction costs by configuring a liquefied gas transfer line and a latent heat exchanger in a heat source area and connecting it relatively simply to a logistics warehouse located relatively far away with a refrigerant circulation line.

[0015] The present invention, which aims to solve such technical problems,

[0016] An LNG storage tank (10) connected to an LNG supply line (11) and storing liquefied gas;

[0017] An LNG transport line (20) that is connected to the above LNG storage tank (10) and LNG supply line (11), respectively, and receives liquefied gas from one selected direction and transports it toward the LNG outlet (27);

[0018] A first latent heat exchanger (40-1) connected to the first bypass line (30-1) provided in the above LNG transport line (20), heat-exchanging the liquefied gas and refrigerant transferred to the first bypass line (30-1) in the first refrigerant heat exchanger (41-1), transferring the liquefied refrigerant to the first refrigerant circulation line (45-1) connected to the first logistics warehouse (80-1), cooling the first logistics warehouse (80-1), and supplying the vaporized refrigerant to the first refrigerant heat exchanger (41-1) for circulation;

[0019] After the first latent heat exchanger (40-1), a second latent heat exchanger (40-2) is connected to a second bypass line (30-2) provided in an LNG transport line (20), and heat is exchanged between the liquefied gas and the refrigerant transferred to the second bypass line (30-2) in a second refrigerant heat exchanger (41-2), and the liquefied refrigerant is transferred to a second refrigerant circulation line (45-2) connected to a second logistics warehouse (80-2), and the second logistics warehouse (80-2) is cooled, and the vaporized refrigerant is supplied to the second refrigerant heat exchanger (41-2) for circulation;

[0020] After the above-mentioned secondary latent heat exchanger (40-2), a third latent heat exchanger (40-3) is connected to a third bypass line (30-3) provided in an LNG transport line (20), heat-exchanges the liquefied gas and refrigerant transferred to the third bypass line (30-3) in a third refrigerant heat exchanger (41-3), transfers the liquefied refrigerant to a third refrigerant circulation line (45-3) connected to a third logistics warehouse (80-3), cools the third logistics warehouse (80-3), and supplies the vaporized refrigerant to the third refrigerant heat exchanger (41-3) for circulation;

[0021] After the above-mentioned third latent heat exchanger (40-3), the fourth latent heat exchanger (40-4) is connected to the fourth bypass line (30-4) provided in the LNG transport line (20), and heat is exchanged between the vaporized gas and the refrigerant transferred to the fourth bypass line (30-4) in the refrigerant heat exchanger (41), and the liquefied refrigerant is transferred to the fourth refrigerant circulation line (45-4) connected to the fourth logistics warehouse (80-4), and the fourth latent heat exchanger (40-4) cools the fourth logistics warehouse (80-4) and supplies the vaporized refrigerant to the fourth refrigerant heat exchanger (41-4) for circulation;

[0022] It is configured to include an LNG discharge port (27) that is connected to the LNG transfer line (20) after the above-mentioned 4th latent heat exchanger (40-4) and discharges vaporized gas.

[0023] In addition, the latent heat exchange unit (40) may be configured such that the LPG liquefied gas is transferred from the first latent heat exchange unit to the fourth latent heat exchange unit and heat is exchanged therewith, thereby increasing the temperature of the liquefied gas step by step, and at least after the third latent heat exchange unit (40-3), the liquefied gas is vaporized with a temperature of at least -35°C or higher, and the vaporized gas is transferred to the LNG outlet (27).

[0024] In addition, the latent heat exchanger (40) may be arranged in a heat source zone (Z1) where an LNG storage tank (10) is located, and a load zone (Z3) equipped with a plurality of logistics warehouses (80) may be arranged at a distance of at least 200 m from the LNG storage tank (10), and a line connection zone (Z2) in which a refrigerant circulation line (45) connects between the heat source zone (Z1) and the load zone (Z3) may be further arranged.

[0025] In addition, the latent heat exchanger (40) may be configured such that a refrigerant heat exchanger (41) is placed in a heat source zone (Z1) where an LNG storage tank (10) is located, a refrigerant liquid receiver (42) is placed in a load zone (Z3) equipped with a plurality of logistics warehouses (80) at a distance of at least 200 m from the LNG storage tank (10), and a line connection zone (Z2) in which a refrigerant circulation line (45) connects between the heat source zone (Z1) and the load zone (Z3) may be further placed.

[0026] In addition, the refrigerant heat exchanger (41) may be configured to be equipped with a refrigerant liquid tank (42) to temporarily store high-pressure refrigerant gas liquefied in the refrigerant heat exchanger (41) and supply the liquefied refrigerant toward the logistics warehouse (80) through a liquid pump.

[0027] In addition, the first latent heat exchanger (40-1) is configured such that the liquefied gas supplied through the first bypass line (30-1) at a temperature lower than at least -150°C is heat-exchanged with the refrigerant in the first refrigerant heat exchanger (41-1) and the liquefied gas passes through the refrigerant at a temperature higher than at least -134°C, and the refrigerant is heat-exchanged with the liquefied gas and has a temperature lower than at least -72°C, and the liquefied refrigerant cools the first logistics warehouse (80-1) and the vaporized refrigerant is circulated in the first refrigerant heat exchanger (41-1).

[0028] The secondary latent heat exchanger (40-2) is configured such that the liquefied gas supplied through the second bypass line (30-2) at a temperature higher than at least -134°C and lower than -100°C is heat-exchanged with the refrigerant in the second refrigerant heat exchanger (41-2) and the liquefied gas passes through the refrigerant at a temperature higher than at least -87°C, and the refrigerant is heat-exchanged with the liquefied gas and has a temperature lower than at least -45°C, and the liquefied refrigerant cools the second logistics warehouse (80-2) and the vaporized refrigerant is circulated to the second refrigerant heat exchanger (41-2).

[0029] The third latent heat exchanger (40-3) is configured such that liquefied gas supplied through the third bypass line (30-3) at a temperature higher than at least -87°C and lower than -50°C exchanges heat with the refrigerant in the third refrigerant heat exchanger (41-3) and passes through the vaporized gas having a temperature higher than at least -35°C, and the refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least -12°C, and the liquefied refrigerant cools the third logistics warehouse (80-3) and the vaporized refrigerant is circulated to the third refrigerant heat exchanger (41-3).

[0030] The fourth latent heat exchanger (40-4) can be configured such that the vaporized gas supplied through the fourth bypass line (30-4) at a temperature higher than at least -35°C and lower than 0°C is heat-exchanged with the refrigerant in the fourth refrigerant heat exchanger (41-4) and passes through the vaporized gas having a temperature lower than at least 15°C, the refrigerant is heat-exchanged with the liquefied gas and has a temperature lower than at least 18°C, the liquefied refrigerant cools the fourth logistics warehouse (80-4), and the vaporized refrigerant is circulated through the fourth refrigerant heat exchanger (41-4).

[0031] In addition, the refrigerant can be configured to be selectively filled in each refrigerant circulation line among environmentally friendly refrigerant gases such as R-32, R-407C, R-410A, and R744.

[0032] In addition, a second control valve (35) that controls the transfer of liquefied gas and vaporized gas to the latent heat exchanger (40) according to the set temperature of the logistics warehouse may be configured in the above-mentioned bypass line (30).

[0033] In addition, the LNG transport line (20) may be provided with a first stop valve (23) that is arranged between the inlet and outlet of the bypass line (30) and closes the LNG transport line (20) according to the set pressure of the liquefied gas or vaporized gas to bypass the liquefied gas or vaporized gas to the latent heat exchanger (40) and allows the liquefied gas or vaporized gas to pass through the bypass line (30), or opens the LNG transport line (20) while the second stop valve (35) of the bypass line (30) is closed.

[0034] According to the present invention, the heat of vaporization of LNG liquefied gas is utilized to sequentially cool the refrigerant, and the latent heat of the refrigerant is utilized in stages to raise the temperature of the liquefied gas and discharge it as vaporized gas, thereby improving the cold heat utilization of the liquefied gas.

[0035] In addition, by exchanging heat between the vaporization heat of LNG liquefied gas and the refrigerant, the refrigerant is liquefied, and by utilizing the latent heat of the refrigerant, compared to a cooling system using a conventional refrigeration cycle, there is an effect of improving environmental protection by reducing power costs and carbon emissions.

[0036] In addition, it has the effect of improving product competitiveness and reliability by configuring a liquefied gas transfer line and latent heat exchanger in the heat source area and configuring it to be connected relatively simply to a logistics warehouse and refrigerant circulation line that are relatively far away, thereby reducing design and construction costs.

[0037] Figure 1 is a schematic diagram showing the configuration of a first embodiment of a cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas according to the present invention.

[0038] Figure 2 is a schematic diagram showing the configuration of a second embodiment of a cooling system for low-temperature industry utilizing the cold energy of LNG liquefied gas of the present invention.

[0039] The present invention relates to a cooling system for low-temperature industries utilizing the cold heat of LNG liquefied gas, which utilizes the heat of vaporization of LNG liquefied gas to cool a refrigerant and utilizes the latent heat of the refrigerant to cool logistics warehouses such as data centers and cold chains, thereby enabling the convenience of maintenance of the cooling system and reduction of operating costs.

[0040] The present invention is susceptible to various modifications and takes various forms, and embodiments are described in detail herein. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood that all modifications, equivalents, and alternatives fall within the spirit and technical scope of the present invention.

[0041]

[0042] Hereinafter, the features of a cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas according to the present invention will be understood through embodiments described in detail with reference to the attached drawings.

[0043]

[0044] First, as shown in Fig. 1, the first embodiment of the low-temperature industrial cooling system utilizing the cold energy of LNG liquefied gas is largely divided into a heat source side zone (Z1) equipped with an LNG storage tank (10), a load side zone (Z3) equipped with a logistics warehouse (80), and a line connection zone (Z2) connecting the heat source side zone (Z1) and the load side zone (Z3), which are arranged at a distance of about 200 m to 2 km for safety reasons, and refrigerant is filled in the pipes installed in the line connection zone (Z2).

[0045] The refrigerant applied to the present invention condenses the vaporized refrigerant while increasing the temperature of the liquefied gas through heat exchange between the refrigerant heat of the LNG liquefied gas and the vaporized refrigerant in the refrigerant heat exchanger (41), and when the condensed liquefied refrigerant is supplied to the logistics warehouse and the refrigerant evaporates, it cools the air through the heat of vaporization (latent heat generated when a phase change occurs while maintaining equilibrium without showing changes in the pressure and temperature of the refrigerant) that takes away the heat of the surroundings. At this time, the refrigerant used can be an optimal refrigerant that evaporates at an appropriate pressure to be operated and has a low global warming potential (GWP), and any one of the environmentally friendly refrigerant gases R-32, R-407C, R-410A, and R744 is selected and configured to be filled in each refrigerant circulation line.

[0046] The above refrigerant is a refrigerant that can replace the existing freon gas, and has the characteristics of being harmless to the human body, non-irritating, and not affecting the ozone layer depletion and global warming effect because it does not contain chlorine. The above refrigerant is a refrigerant that easily evaporates at the temperature and pressure to be used and has a low global warming coefficient. Since the composition of such a refrigerant is already known, a detailed description will be omitted, and since it can be applied in various ways according to the needs of those working in the relevant industry, it is not limited to a specific one.

[0047] To explain this in more detail, an LNG storage tank (10) is provided in the heat source area (Z1), and LNG liquefied gas of low temperature and high pressure (-150℃, 76 to 78 bar) is supplied through an LNG supply line (11) by a ship, etc., and an LNG transfer line (20) is connected to the LNG storage tank (10) by a pipe, and the liquefied gas is discharged toward the LNG discharge port (27) of the LNG transfer line (20) by driving a liquid pump.

[0048] Here, the LNG transport line (20) may be connected to the LNG supply line (11) by a valve so as to receive liquefied gas from one direction selected from the LNG storage tank (10) or the LNG supply line (11) and transport it toward the LNG outlet (27), and even if the valve for opening and closing the liquid pump line for pumping LPG gas to the supply line is not indicated in the attached drawing, the present invention may also include providing a liquid pump and valve, etc., in the line according to the request of a person working in the relevant industry.

[0049] In addition, in the load side zone (Z3), a plurality of logistics warehouses (80) are provided, and the freezers and refrigerators of the logistics warehouses are each connected to a refrigerant circulation line (45), so that the internal air is cooled by the heat of vaporization of the liquefied refrigerant introduced into the refrigerant circulation line (45). However, the configuration of the evaporator, etc. in the freezers and refrigerators can be applied in various ways according to the needs of workers in the relevant industry, and is not limited to a specific one.

[0050] And, in the LNG transport line (20), a plurality of latent heat exchangers (40) are arranged, and each is individually configured to be connected to the logistics warehouse (80) through a refrigerant circulation line (45), so as to sequentially increase the temperature of the supplied LNG liquefied gas (-150°C) and ultimately supply LPG gas in a gaseous state of 0 to 20°C to a demand source (city gas pipe, etc.) connected to the LNG outlet (27).

[0051] The above latent heat exchanger (40) is arranged in the heat source side zone (Z1) where the LNG storage tank (10) is located, and in the present invention, it is configured to heat the liquefied gas into a gaseous gas by configuring the first to fourth latent heat exchangers, but is not limited thereto, and may also include a configuration in which the liquefied gas is heated into a gaseous gas by exchanging heat through the nth latent heat exchanger.

[0052] The first latent heat exchanger (40-1) in FIG. 1 is connected to the first bypass line (30-1) provided in the LNG transport line (20), and heat-exchanges the liquefied gas and refrigerant transferred to the first bypass line (30-1) in the first refrigerant heat exchanger (41-1), transfers the liquefied refrigerant to the first refrigerant circulation line (45-1) connected to the first logistics warehouse (80-1), cools the first logistics warehouse (80-1), and supplies the vaporized refrigerant to the first refrigerant heat exchanger (41-1) for circulation.

[0053] In addition, the secondary latent heat exchanger (40-2) is connected to the second bypass line (30-2) provided in the LNG transport line (20) after the primary latent heat exchanger (40-1), and the liquefied gas and refrigerant transferred to the second bypass line (30-2) are heat-exchanged in the second refrigerant heat exchanger (41-2), and the liquefied refrigerant is transferred to the second refrigerant circulation line (45-2) connected to the second logistics warehouse (80-2), and the second logistics warehouse (80-2) is cooled, and the vaporized refrigerant is supplied to the second refrigerant heat exchanger (41-2) and circulated.

[0054] In addition, the 3rd latent heat exchanger (40-3) is connected to the 3rd bypass line (30-3) provided in the LNG transport line (20) after the 2nd latent heat exchanger (40-2), and the liquefied gas and refrigerant transferred to the 3rd bypass line (30-3) are heat-exchanged in the 3rd refrigerant heat exchanger (41-3), and the liquefied refrigerant is transferred to the 3rd refrigerant circulation line (45-3) connected to the 3rd logistics warehouse (80-3), and the 3rd logistics warehouse (80-3) is cooled and the vaporized refrigerant is supplied to the 3rd refrigerant heat exchanger (41-3) for circulation.

[0055] And, the 4th latent heat exchanger (40-4) is connected to the 4th bypass line (30-4) provided in the LNG transport line (20) after the 3rd latent heat exchanger (40-3), and the vaporized gas and refrigerant transferred to the 4th bypass line (30-4) are heat-exchanged in the refrigerant heat exchanger (41) to transfer the liquefied refrigerant to the 4th refrigerant circulation line (45-4) connected to the 4th logistics warehouse (80-4), and the 4th logistics warehouse (80-4) is cooled, and the vaporized refrigerant is supplied to the 4th refrigerant heat exchanger (41-4) for circulation.

[0056] Here, the bypass line (30) is provided with a second stop valve (35) that controls the transfer of liquefied gas and vaporized gas to the latent heat exchanger (40) according to the set temperature of the logistics warehouse, and the LNG transfer line (20) is further provided with a first stop valve (23) that is arranged between the inlet and outlet of the bypass line (30) to close the LNG transfer line (20) according to the set pressure of the liquefied gas or vaporized gas to bypass the liquefied gas or vaporized gas to the latent heat exchanger (40) or to open the LNG transfer line (20) to pass the liquefied gas or vaporized gas when the second stop valve (35) of the bypass line (30) is closed.

[0057] In addition, the aforementioned refrigerant heat exchanger (41) is each equipped with a refrigerant liquid tank (42) to temporarily store the high-pressure refrigerant gas liquefied in the refrigerant heat exchanger (41) and to stably supply the liquefied gas toward the logistics warehouse (80) through a liquid pump.

[0058] Accordingly, the liquefied gas is configured to be vaporized at a temperature of at least -35°C or higher after at least the third latent heat exchanger (40-3) and discharged as vaporized gas through the LNG outlet (27) to be supplied to demanders such as city gas and fuel cell power generation.

[0059]

[0060] And, as shown in FIG. 2, the second embodiment of the present invention may also include a configuration in which, in terms of the overall configuration, the refrigerant heat exchanger (41) is arranged in the heat source side zone (Z1) and the refrigerant liquid collector (42) is arranged in the load side zone (Z3) equipped with a logistics warehouse (80), while having the same configuration as that described in the first embodiment.

[0061] In addition, in the second embodiment, the LNG transfer line (20) is configured to be connected only from the fourth latent heat exchanger (40-4) to the fourth bypass line (30-4), so that the low-temperature liquefied or vaporized gas heat-exchanged in the first to third latent heat exchangers is heated and transferred to the LNG outlet (27), which is also included in the present invention.

[0062]

[0063] An example of use of a logistics warehouse cooling system configured as described above is described, and LNG liquefied gas having a temperature of -150°C is transferred to a primary latent heat exchanger (40-1) through an LNG transfer line (20). Depending on the temperature and pressure, the LNG liquefied gas can be directly transferred to the LNG transfer line (20) by opening a valve connected to the LNG supply line (11), or transferred by driving a liquid pump in an LNG storage tank (10).

[0064] In addition, the first latent heat exchange unit (40-1) is provided with a second stop valve (35) that operates at a set temperature in the first bypass line, which is the inlet direction, when the first bypass line (30-1) is connected to the LNG transfer line (20). The LNG transfer line (20) is configured with a first stop valve (23) disposed between the inlet and the outlet of the bypass line, so that the first stop valve (23) is closed and the second stop valve (35) is opened according to the set temperature and pressure to transfer the liquefied gas to the bypass line (30), or the first stop valve (23) is opened and the second stop valve (35) is closed to allow the liquefied gas to pass through the latent heat exchange unit.

[0065] Accordingly, the liquefied gas is transferred to the first refrigerant heat exchanger (41-1) through the first bypass line (30-1) at a temperature lower than at least -150°C, and heat is exchanged with the gaseous refrigerant, and the liquefied gas passes through while having a temperature higher than at least -134°C, and the refrigerant exchanges heat with the liquefied gas, and is phase-changed into a liquefied refrigerant at a temperature lower than at least -72°C, and is transferred to the first logistics warehouse (80-1) to cool the first logistics warehouse by the heat of vaporization, and the vaporized refrigerant is circulated back to the first refrigerant heat exchanger (41-1).

[0066] The secondary latent heat exchanger (40-2) opens the second stop valve (35) when the liquefied gas supplied through the second bypass line (30-2) has a temperature higher than at least -134°C and lower than -100°C, and the liquefied gas passes through the second refrigerant heat exchanger (41-2) by exchanging heat with the refrigerant, and the liquefied gas has a temperature higher than at least -87°C, and the refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least -45°C, and the liquefied refrigerant cools the second logistics warehouse (80-2), and the vaporized refrigerant is circulated back to the second refrigerant heat exchanger (41-2).

[0067] In addition, in the case where the liquefied gas supplied through the third bypass line (30-3) has a temperature higher than at least -87°C and lower than -50°C, the second set-off valve (35) is opened to exchange heat with the refrigerant in the third refrigerant heat exchanger (41-3) so that the vaporized gas passes through with a temperature higher than at least -35°C, and the refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least -12°C, thereby cooling the third logistics warehouse (80-3), and the vaporized refrigerant is circulated back to the third refrigerant heat exchanger (41-3).

[0068] And, in the case where the vaporized gas supplied through the fourth bypass line (30-4) has a temperature higher than at least -35°C and lower than 0°C, the fourth latent heat exchanger (40-4) opens the second set-off valve (35) to exchange heat with the refrigerant in the fourth refrigerant heat exchanger (41-4) so ​​that the vaporized gas passes through with a temperature higher than at least 15°C, and the refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least 18°C, and the liquefied refrigerant cools the fourth logistics warehouse (80-4), and the vaporized refrigerant is circulated back to the fourth refrigerant heat exchanger (41-4).

[0069] As described above, by utilizing the cold heat of LNG liquefied gas to liquefy the refrigerant and configuring it to be gradually heated by the refrigerant, and by configuring it to cool the logistics warehouse using the latent heat of the refrigerant, environmental protection can be improved by utilizing the cold heat and reducing electricity costs, and by simplifying the configuration of the latent heat exchanger, design and construction costs can be reduced, thereby improving product competitiveness and reliability.

[0070] As described above, the above-described embodiments have described the most preferred examples of the present invention, but they are not limited to the above-described embodiments, and it is clear to those in the relevant industry that various modifications are possible within a scope that does not depart from the technical spirit of the present invention.

Claims

1. LNG storage tank connected to the LNG supply line and storing liquefied gas; An LNG transfer line that is connected to the above LNG storage tank and LNG supply line, respectively, and receives liquefied gas from a selected direction and transfers it toward the LNG outlet; A primary latent heat exchanger connected to a first bypass line provided in the above LNG transport line, heat-exchanging the liquefied gas and refrigerant transported to the first bypass line in a first refrigerant heat exchanger, transporting the liquefied refrigerant to a first refrigerant circulation line connected to a first logistics warehouse, cooling the first logistics warehouse, and supplying the vaporized refrigerant to the first refrigerant heat exchanger for circulation; After the first latent heat exchanger, a second latent heat exchanger is connected to a second bypass line provided in the LNG transport line, heat-exchanges the liquefied gas and refrigerant transported to the second bypass line in a second refrigerant heat exchanger, transports the liquefied refrigerant to a second refrigerant circulation line connected to a second logistics warehouse, cools the second logistics warehouse, and supplies the vaporized refrigerant to the second refrigerant heat exchanger for circulation; After the second latent heat exchanger, a third latent heat exchanger is connected to a third bypass line provided in the LNG transport line, heat is exchanged between the liquefied gas and the refrigerant transported to the third bypass line in a third refrigerant heat exchanger, and the liquefied refrigerant is transported to a third refrigerant circulation line connected to a third logistics warehouse, and the third latent heat exchanger cools the third logistics warehouse and supplies the vaporized refrigerant to the third refrigerant heat exchanger for circulation; After the third latent heat exchanger, a fourth latent heat exchanger is connected to a fourth bypass line provided in the LNG transport line, heat-exchanges the vaporized gas and refrigerant transported to the fourth bypass line in a refrigerant heat exchanger, transports the liquefied refrigerant to a fourth refrigerant circulation line connected to a fourth logistics warehouse, cools the fourth logistics warehouse, and supplies the vaporized refrigerant to the fourth refrigerant heat exchanger for circulation; A cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas, characterized by including an LNG discharge port that is connected to the LNG transfer line after the 4th latent heat exchanger and discharges the vaporized gas.

2. In paragraph 1, The above latent heat exchanger, A cooling system for low-temperature industries utilizing the cold heat of LNG liquefied gas, characterized in that LPG liquefied gas is transferred from the first latent heat exchanger to the fourth latent heat exchanger and heat is exchanged, so that the temperature of the liquefied gas increases step by step, and at least after the third latent heat exchanger, the liquefied gas is vaporized with a temperature of at least -35℃ or higher and the vaporized gas is transferred to the outlet.

3. In paragraph 1, The above latent heat exchanger is placed in the heat source area where the LNG storage tank is located, A load-side area equipped with multiple logistics warehouses shall be placed at a distance of at least 200 m from the above LNG storage tank. A cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas, characterized in that a line connection section is further arranged to connect a refrigerant circulation line between the heat source section and the load section.

4. In paragraph 1, A cooling system for low-temperature industries utilizing cold energy from LNG liquefied gas, characterized in that the latent heat exchanger is configured such that a refrigerant heat exchanger is placed in a heat source side zone where an LNG storage tank is located, a refrigerant liquid receiver is placed in a load side zone having multiple logistics warehouses at a distance of at least 200 m from the LNG storage tank, and a line connection zone in which a refrigerant circulation line connects between the heat source side zone and the load side zone is further placed.

5. In paragraph 1, In the above refrigerant heat exchanger, A low-temperature industrial cooling system utilizing the cold energy of LNG liquefied gas, characterized in that each refrigerant receiver is equipped with a refrigerant liquid tank to temporarily store high-pressure refrigerant gas liquefied in a refrigerant heat exchanger and supply the refrigerant gas toward a logistics warehouse through a liquid pump.

6. In paragraph 1, The first latent heat exchanger is configured such that liquefied gas supplied through the first bypass line at a temperature lower than at least -150°C is heat-exchanged with a refrigerant in the first refrigerant heat exchanger and passes through the liquefied gas having a temperature higher than at least -134°C, and the refrigerant is heat-exchanged with the liquefied gas and has a temperature lower than at least -72°C, and the liquefied refrigerant cools the first logistics warehouse and the vaporized refrigerant is circulated through the first refrigerant heat exchanger. The secondary latent heat exchanger is configured such that liquefied gas supplied through the second bypass line at a temperature higher than at least -134°C and lower than -100°C exchanges heat with a refrigerant in the second refrigerant heat exchanger and passes the liquefied gas with a temperature higher than at least -87°C, and the refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least -45°C, and the liquefied refrigerant cools the second logistics warehouse and the vaporized refrigerant circulates through the second refrigerant heat exchanger. The third latent heat exchanger is configured such that the liquefied gas supplied through the third bypass line, which has a temperature higher than at least -87°C and lower than -50°C, exchanges heat with the refrigerant in the third refrigerant heat exchanger, and the vaporized gas passes through the refrigerant, which has a temperature higher than at least -35°C, and the refrigerant exchanges heat with the liquefied gas, and the liquefied refrigerant has a temperature lower than at least -12°C, and cools the third logistics warehouse, and the vaporized refrigerant is circulated through the third refrigerant heat exchanger. A cooling system for low-temperature industries utilizing cold heat from LNG liquefied gas, characterized in that the fourth latent heat exchanger is configured such that the vaporized gas supplied through the fourth bypass line, which has a temperature higher than at least -35°C and lower than 0°C, exchanges heat with the refrigerant in the fourth refrigerant heat exchanger, and the vaporized gas passes through the fourth refrigerant heat exchanger, and the refrigerant exchanges heat with the liquefied gas, and the liquefied refrigerant has a temperature lower than at least 18°C, and cools the fourth logistics warehouse, and the vaporized refrigerant is circulated through the fourth refrigerant heat exchanger.

7. In paragraph 1, The above refrigerant, A low-temperature industrial cooling system utilizing the cold energy of LNG liquefied gas, characterized by being configured to selectively charge each refrigerant circulation line with one of the environmentally friendly refrigerant gases R-32, R-407C, R-410A, and R744.

8. In paragraph 1, In the above detour line, A cooling system for low-temperature industries utilizing the cold energy of LNG liquefied gas, characterized by a second valve configured to control the transfer of liquefied gas and vaporized gas to the latent heat exchanger according to the set temperature of the logistics warehouse.

9. In paragraph 1, In the above LNG transport line, A cooling system for low-temperature industries utilizing cold energy from LNG liquefied gas, characterized in that a first stop valve is configured to close the LNG transfer line according to the set pressure of the liquefied gas or vaporized gas and divert the liquefied gas or vaporized gas to the bypass line to a latent heat exchanger, or to open the LNG transfer line and pass the liquefied gas or vaporized gas when the second stop valve of the bypass line is closed.

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