Optimal control cooling system utilizing cold energy of LNG liquefied gas

Abstract

The present invention relates to an optimally controlled cooling system utilizing cold energy of LNG liquefied gas and, more specifically, to an optimally controlled cooling system utilizing cold energy of LNG liquefied gas, which has been invented to improve maintenance convenience and reduce operating costs of the cooling system, by configuring the system to cool a first refrigerant by utilizing vaporization heat of LNG liquefied gas, to cool the first refrigerant by utilizing latent heat of the first refrigerant, and to cool data centers and logistics warehouses such as cold-chain facilities. According to the present invention, the first refrigerant is cooled and sequentially cooled by utilizing cold energy of LNG liquefied gas, the second refrigerant is sequentially cooled by utilizing latent heat of the first refrigerant, and the temperature of the liquefied gas is raised through heat exchange between the first refrigerant and the second refrigerant and heat exchange between the first refrigerant and the liquefied gas so that the liquefied gas is discharged as vaporized gas, thereby improving cold energy utilization of the liquefied gas. In addition, the first refrigerant is liquefied by performing heat exchange between vaporization heat of the LNG liquefied gas and the first refrigerant, and the second refrigerant is liquefied by the latent heat of the first refrigerant and utilized to cool a warehouse, thereby reducing power costs and carbon emissions to improve environmental protection. Moreover, by providing a liquefied gas transfer line and freezing and refrigerating heat exchangers in a heat source side area, and providing a relatively simple connection of a circulation line to a freezing auxiliary heat exchanger of a logistics warehouse that is relatively far away, there is an effect of improving product competitiveness and reliability, such as reducing design and construction costs.

Description

Optimal control cooling system utilizing the cold energy of LNG liquefied gas

[0001] The present invention relates to an optimal control cooling system 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 first refrigerant, utilizes the latent heat of the first refrigerant to cool the first refrigerant, and cools 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. 1 0-0981398, a cooling system was proposed that uses a sensible heat utilization system that does not involve a phase change in the secondary refrigerant that 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, which requires the installation of duplicate lines, valves, and heat exchangers to store it, 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 an optimal control cooling system utilizing the cold heat of LNG liquefied gas, which can cool a first refrigerant by utilizing the heat of vaporization of LNG liquefied gas, sequentially cool a second refrigerant by utilizing the latent heat of the first refrigerant, and increase the temperature of the liquefied gas through heat exchange between the first refrigerant and the second refrigerant and heat exchange between the first refrigerant and the liquefied gas.

[0013] In addition, the present invention aims to provide an optimal control cooling system utilizing the cold heat of LNG liquefied gas, which can improve environmental protection by reducing electricity costs and carbon emissions by exchanging heat between the vaporization heat of LNG liquefied gas and a first refrigerant to liquefy the first refrigerant, and liquefying a second refrigerant with the latent heat of the first refrigerant to use it for cooling a logistics warehouse.

[0014] In addition, the present invention aims to provide an optimal control cooling system utilizing the cold heat of LNG liquefied gas, which can reduce design and construction costs by configuring a liquefied gas transfer line and a refrigeration and cooling heat exchanger in a heat source area and connecting it relatively simply to a refrigeration auxiliary heat exchanger in a relatively distant logistics warehouse through a 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 refrigeration heat exchanger (40-1) and a second refrigeration heat exchanger (40-2) installed in front of the above LNG transport line (20) to sequentially exchange heat with the transported liquefied gas and increase its temperature to vaporized gas;

[0019] A first latent heat refrigeration circulation line (30) configured to circulate and supply the first refrigerant, which has been liquefied through heat exchange in the first refrigeration heat exchanger (40-1), in a vaporized state to the second refrigeration heat exchanger (40-2);

[0020] A plurality of refrigeration auxiliary heat exchangers (41) each connected to a plurality of bypass lines (31) provided in the first latent heat refrigeration circulation line (30) and exchanging heat with the first refrigerant liquefied by heat exchange in the first refrigeration heat exchanger (40-1);

[0021] A second latent heat refrigeration circulation line (33) that cools the logistics warehouse (80) by liquefying the second refrigerant through heat exchange in the above-mentioned refrigeration auxiliary heat exchanger (41) and supplies the liquefied second refrigerant to the refrigeration auxiliary heat exchanger (41) for circulating;

[0022] A refrigerated heat exchanger (44) installed at the rear of the above LNG transport line (20) and exchanging heat with the transported vaporized gas;

[0023] A latent heat refrigeration circulation line (35) that refrigerates the logistics warehouse (80) by liquefying the third refrigerant through heat exchange in the above refrigeration heat exchanger (44) and supplies the vaporized third refrigerant to the refrigeration heat exchanger (44) for circulation;

[0024] It is configured to include an LNG discharge port (27) that is connected to the LNG transfer line (20) after the above-mentioned refrigeration heat exchanger (44) and discharges vaporized gas.

[0025] In addition, the LNG liquefied gas can be configured to undergo heat exchange in stages through the above-mentioned refrigeration heat exchanger (40), and the vaporized gas having a temperature of at least -35°C or higher can be supplied to the refrigeration heat exchanger (44).

[0026] In addition, the above-mentioned refrigeration heat exchanger (40) and the refrigeration heat exchanger (44) are arranged in a heat source side zone (Z1) where an LNG storage tank (10) is located, and a plurality of refrigerated and frozen logistics warehouses (80) are provided at a distance of at least 200 m from the LNG storage tank (10), and a load side zone (Z3) equipped with a refrigeration auxiliary heat exchanger (41) for cooling the refrigerated logistics warehouses is arranged, and a line connection zone (Z2) in which a refrigeration circulation line and a refrigeration circulation line are connected between the heat source side zone (Z1) and the load side zone (Z3) can be configured.

[0027] In addition, a plurality of refrigeration heat exchangers (40) may be installed in the LNG transport line (20), and are configured to receive liquefied gas at a temperature lower than -150°C from the primary refrigeration heat exchanger (40) provided in the front, and discharge the vaporized LNG gas at a temperature of at least -35°C or higher from the nth refrigeration heat exchanger (40) provided in the rear to the refrigeration heat exchanger (44).

[0028] In addition, the refrigeration auxiliary heat exchanger (41) is configured such that the first refrigeration auxiliary heat exchanger, the second refrigeration auxiliary heat exchanger, and the third refrigeration auxiliary heat exchanger are each connected to the first latent heat refrigeration circulation line (30) through a bypass line (31), and the first refrigeration auxiliary heat exchanger (41-1) heat-exchanges the first refrigerant and the second refrigerant, which are transferred to the bypass line (31) of the first latent heat refrigeration circulation line (30) at a temperature lower than at least -85°C, so that the second refrigerant is liquefied to have a temperature lower than at least -72°C and cools the first logistics warehouse (80-1), and the vaporized second refrigerant is circulated back to the first refrigeration auxiliary heat exchanger (41-1).

[0029] The second refrigeration auxiliary heat exchanger (41-2) is configured to exchange heat between the first refrigerant and the second refrigerant, which are transferred to the bypass line (31) provided in the first latent heat refrigeration circulation line (30) and have a temperature lower than at least -81°C, so that the second refrigerant is liquefied to have a temperature lower than at least -45°C and cools the second logistics warehouse (80-2), and the vaporized second refrigerant is circulated back to the second refrigeration auxiliary heat exchanger (41-2).

[0030] The third refrigeration auxiliary heat exchanger (41-3) may be configured to exchange heat between the first refrigerant and the second refrigerant, which are transferred to the bypass line (31) provided in the first latent heat refrigeration circulation line (30) and have a temperature lower than at least -66°C, so that the second refrigerant is liquefied and has a temperature lower than at least -12°C to cool the third logistics warehouse (80-3), and the vaporized second refrigerant is circulated back to the third refrigeration auxiliary heat exchanger (41-3).

[0031] In addition, the first refrigerant and the second refrigerant can be configured to be filled in the first latent heat refrigeration circulation line (30), the second latent heat refrigeration circulation line (33), and the latent heat refrigeration circulation line (35) by selecting from among environmentally friendly refrigerant gases R-32, R-407C, R-410A, and R744.

[0032] In addition, a control valve (23) that controls the transfer of the first refrigerant to the refrigeration auxiliary heat exchanger (41) according to the set temperature of the logistics warehouse may be configured in the above-mentioned bypass line (31).

[0033] In addition, the LNG transport line (20) may be further provided with a shut-off valve (23) in the direction of the outlet of the refrigeration heat exchanger (40), so that when the liquefied gas is heated to a set temperature, the shut-off valve (23) may be opened to transport it to the refrigeration heat exchanger (44).

[0034] In addition, the latent heat refrigeration circulation line (35) may be configured with a heat pump (60) that detects the temperature of the vaporized refrigerant and operates when the temperature is lower than the set temperature, thereby causing a phase change of the third refrigerant to have a temperature higher than at least 18°C.

[0035] In addition, in the latent heat refrigeration circulation line (35), a bypass pipe (70) that connects the transfer and recovery line in the line connection zone (Z2) can be further formed, so that the third refrigerant that has been heat-exchanged by operating the valve member provided in the transfer and recovery line and the bypass pipe (70) can be recovered in the line connection zone (Z2).

[0036] According to the present invention, the cold heat of LNG liquefied gas is utilized to cool the first refrigerant, and the second refrigerant is sequentially cooled by utilizing the latent heat of the first refrigerant, and the temperature of the liquefied gas is increased through heat exchange between the first refrigerant and the second refrigerant and heat exchange between the first refrigerant and the liquefied gas, thereby allowing it to be discharged as vaporized gas, thereby improving the cold heat utilization of the liquefied gas.

[0037] In addition, by exchanging heat between the vaporization heat of LNG liquefied gas and the first refrigerant to liquefy the first refrigerant, and by liquefying the second refrigerant with the latent heat of the first refrigerant and utilizing it for cooling the logistics warehouse, there is an effect of improving environmental protection by reducing electricity costs and carbon emissions.

[0038] In addition, it is possible to configure a liquefied gas transfer line and a refrigeration and cooling heat exchanger in the heat source area and to connect it relatively simply to a refrigeration auxiliary heat exchanger in a relatively distant logistics warehouse through a circulation line, thereby reducing design and construction costs and improving product competitiveness and reliability.

[0039] Figure 1 is a schematic diagram showing the configuration of an optimal control cooling system utilizing the cold energy of LNG liquefied gas according to the present invention.

[0040] Figure 2 is a schematic diagram showing an exemplary configuration of an optimal control cooling system utilizing the cold energy of LNG liquefied gas according to the present invention.

[0041] The present invention relates to an optimal control cooling system utilizing the cold heat of LNG liquefied gas, which utilizes the heat of vaporization of LNG liquefied gas to cool a first refrigerant, utilizes the latent heat of the first refrigerant to cool the first refrigerant, and is configured 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 reducing operating costs.

[0042] 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.

[0043]

[0044] Hereinafter, the features of the optimal control cooling system 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.

[0045]

[0046] First, as shown in Fig. 1, the optimal control 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).

[0047] The first refrigerant applied to the present invention is configured to exchange heat with LNG liquefied gas to raise the temperature of the liquefied gas, and the second refrigerant is configured to exchange heat with the first refrigerant to raise the temperature of the first refrigerant, and the condensed refrigerant is condensed while raising the temperature of the liquefied gas through heat exchange between the liquefied refrigerant and the vaporized refrigerant in the heat exchanger, and the condensed liquefied refrigerant is supplied to the logistics warehouse to cool 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 when the refrigerant evaporates. 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 supplied to each of the first latent heat refrigeration circulation line (30), the second latent heat refrigeration circulation line (33), and the latent heat refrigeration circulation line (35). It is configured to be filled.

[0048] 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.

[0049] 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 so that the liquefied gas is transferred toward the LNG discharge port (27) of the LNG transfer line (20) by driving a liquid pump.

[0050] 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 a valve for opening and closing a liquid pump line for pumping LNG 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.

[0051] In addition, in the load side zone (Z3), a plurality of logistics warehouses (80) are provided, and a second latent heat refrigeration circulation line (33) is connected to the freezers of the logistics warehouses, and a latent heat refrigeration circulation line (35) is connected to the refrigerators, so that the air inside the freezers and refrigerators is cooled by the heat of vaporization of the liquefied refrigerant introduced into the circulation line. 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.

[0052] And, in the LNG transport line (20), a plurality of refrigeration heat exchangers (40) can be arranged. In the present invention, the first refrigeration heat exchanger (40-1) and the second refrigeration heat exchanger (40-2) are respectively installed from the front to the rear of the LNG transport line (20), sequentially increasing the temperature of the supplied LNG liquefied gas (-150°C) so that the vaporized LNG gas has a temperature of at least -35°C and is transferred to the refrigeration heat exchanger (44).

[0053] The above first refrigeration heat exchanger (40-1) and the second refrigeration heat exchanger (40-2) are arranged in the heat source side zone (Z1) where the LNG storage tank (10) is located. In the present invention, the second refrigeration heat exchanger is configured to heat the liquefied gas to gaseous gas, but the present invention is not limited thereto. It may also include the liquefied gas being heated to gaseous gas by heat exchange through an nth refrigeration heat exchanger.

[0054] The first refrigeration heat exchanger (40-1) is installed in front of the LNG transport line (20) and heat-exchanges the transported liquefied gas (-150°C) with the first refrigerant, so that the liquefied first refrigerant has a temperature of at least -85°C or lower and is transported to the first latent heat refrigeration circulation line (30) connected to the load side section (Z3).

[0055] The first latent heat refrigeration circulation line (30) is configured so that the first refrigerant, which has been liquefied through heat exchange in the first refrigeration heat exchanger (40-1), is circulated and supplied in a vaporized state to the second refrigeration heat exchanger (40-2), and in the load side zone (Z3), a plurality of bypass lines (31) are configured with a refrigeration auxiliary heat exchanger (41) in the first latent heat refrigeration circulation line (30) to correspond to the freezers of a plurality of logistics warehouses (80).

[0056] The above-mentioned refrigeration auxiliary heat exchanger (41) is connected to a plurality of bypass lines (31) provided in the first latent heat refrigeration circulation line (30), so that the first refrigerant liquefied by heat exchange in the first refrigeration heat exchanger (40-1) circulates and exchanges heat with the second refrigerant circulated along the second latent heat refrigeration circulation line (33) connecting the refrigeration auxiliary heat exchanger (41) and the logistics warehouse (80), thereby gradually increasing the temperature of the first refrigerant and cooling the freezer of the logistics warehouse (80) by the liquefied and transported second refrigerant.

[0057] In the present invention, the refrigeration auxiliary heat exchanger (41) is installed in each of three bypass lines (31) provided in the first latent heat refrigeration circulation line (30), so that the second refrigerant liquefied through heat exchange in the refrigeration auxiliary heat exchanger (41) cools the logistics warehouse (80) through the second latent heat refrigeration circulation line (33), and the liquefied second refrigerant is re-supplied to the refrigeration auxiliary heat exchanger (41) and circulated, which is described as follows.

[0058] The above refrigeration auxiliary heat exchanger (41) is configured such that the first refrigeration auxiliary heat exchanger, the second refrigeration auxiliary heat exchanger, and the third refrigeration auxiliary heat exchanger are each connected through a bypass line (31) provided in the first latent heat refrigeration circulation line (30), and the refrigeration auxiliary heat exchanger (41) is connected to each freezer provided in the logistics warehouse (80) through the second latent heat refrigeration circulation line (33) to cool the freezer using a secondary refrigerant, but the present invention is not limited thereto, and the installation of a plurality of the above refrigeration auxiliary heat exchangers and freezers may also be included in the present invention.

[0059] The above first refrigeration auxiliary heat exchanger (41-1) is connected to the most forward bypass line (31) of the first latent heat refrigeration circulation line (30), and heat-exchanges the first refrigerant having a temperature lower than at least -85°C and the second refrigerant of the second latent heat refrigeration circulation line (33), so that the second refrigerant has a temperature lower than at least -72°C and is liquefied to provide the first logistics warehouse (80-1) with ultra-low temperature freezing (-60 to -65°C), and the vaporized second refrigerant is supplied to the first refrigeration auxiliary heat exchanger (41-1) again for circulation.

[0060] In addition, the second refrigeration auxiliary heat exchanger (41-2) is configured to heat-exchange the first refrigerant having a temperature lower than at least -81°C, which is transferred to the bypass line (31) of the first latent heat refrigeration circulation line after the first refrigeration auxiliary heat exchanger, with the second refrigerant of the second latent heat refrigeration circulation line (33), so that the second refrigerant has a temperature lower than at least -45°C and is liquefied to freeze (-40 to -20°C) the second logistics warehouse (80-2), and the vaporized second refrigerant is supplied to the second refrigeration auxiliary heat exchanger (41-2) again for circulation.

[0061] In addition, the third refrigeration auxiliary heat exchanger (41-3) may be configured to heat-exchange the first refrigerant having a temperature lower than at least -66°C, which is transferred to the bypass line (31) of the first latent heat refrigeration circulation line after the second refrigeration auxiliary heat exchanger, with the second refrigerant of the second latent heat refrigeration circulation line (33), so that the second refrigerant has a temperature lower than at least -12°C and is liquefied to freeze or refrigerate (-5 to 5°C) the third logistics warehouse (80-3), and the vaporized second refrigerant is circulated back to the third refrigeration auxiliary heat exchanger (41-3).

[0062] Here, the bypass line (31) may be configured with a control valve that controls the transfer of the first refrigerant to the refrigeration auxiliary heat exchanger (41) according to the set temperature of the logistics warehouse, and a control valve may also be arranged between the inlet and outlet of the bypass line (31) in the first latent heat refrigeration circulation line so as to close the first latent heat refrigeration circulation line according to the set temperature of the first refrigerant and bypass the first refrigerant to the bypass line (31), or the control valve of the bypass line (31) may be closed and the control valve of the first latent heat refrigeration circulation line may be opened so as to allow the first refrigerant to pass.

[0063] In addition, the aforementioned refrigeration heat exchanger (40) and refrigeration auxiliary heat exchanger (41) are each equipped with a refrigerant liquid reservoir (42) to temporarily store the high-pressure refrigerant liquefied in the heat exchanger and to stably circulate it through the circulation line via a liquid pump.

[0064] And, at the rear of the LNG transport line (20), a refrigeration heat exchanger (44) is installed in the heat source side zone (Z1), and the liquefied third refrigerant is refrigerated by heat exchange with the LNG gas vaporized through heat exchange in the aforementioned refrigeration heat exchanger (40) and vaporized while refrigerating the refrigerator of the logistics warehouse (80) provided in the load side zone (Z3) through the latent heat refrigeration circulation line (35), and the vaporized third refrigerant is configured to be circulated back to the refrigeration heat exchanger.

[0065] At this time, it is preferable that the LNG transport line (20) is further provided with a shut-off valve (23) in the direction of the outlet of the refrigeration heat exchanger (40), so that when the LNG gas is heated to a set temperature (-35°C), the shut-off valve (23) is opened to transport it to the refrigeration heat exchanger (44).

[0066] That is, the liquefied gas of the LNG transport line (20) is configured to be vaporized at a temperature of at least -35°C or higher after passing through at least the refrigeration heat exchanger (40) and then transferred to the refrigeration heat exchanger (44), and the third refrigerant cools the refrigerator of the logistics warehouse of the load side zone (Z3) connected to the refrigeration heat exchanger (44) and the latent heat refrigeration circulation line (35), and the LNG vaporized gas heat-exchanged in the refrigeration heat exchanger (44) is discharged to the LNG outlet (27) and supplied to demanders such as city gas and fuel cell power generation.

[0067]

[0068] An example of the 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 in stages to a primary refrigeration heat exchanger (40) and a secondary refrigeration heat exchanger (40) 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).

[0069] In addition, the first refrigeration heat exchanger (40) is connected to the first latent heat refrigeration circulation line (30) and heat-exchanges the LNG liquefied gas and the first refrigerant so that the liquefied gas has a temperature higher than at least -111°C and passes through it and is transferred to the second refrigeration heat exchanger (40). The first refrigerant exchanges heat with the liquefied gas and has a temperature lower than at least -85°C and is phase-changed into a liquefied refrigerant, passes through the load-side zone (Z3), and exchanges heat with the second refrigerant in the refrigeration auxiliary heat exchanger (41) so that it is vaporized to at least -12°C and then is supplied to the second refrigeration heat exchanger (40) so that the liquefied gas has a temperature higher than -111°C and is transferred so that the liquefied gas has a temperature of -35°C and is phase-changed into a vaporized gas.

[0070]

[0071] Meanwhile, in the first refrigerant heat exchanger (40), the heat-exchanged first refrigerant has a temperature lower than at least -85°C and is phase-changed into a liquefied refrigerant, and is transferred to a plurality of refrigeration auxiliary heat exchangers (41) provided in the load side section (Z3) to cool the freezer of the logistics warehouse by the heat of vaporization, and the vaporized refrigerant (-12°C) is circulated and transferred again to the first refrigeration heat exchanger (40-1).

[0072] The refrigeration auxiliary heat exchanger (41) is connected to the logistics warehouse (80) by the second latent heat refrigeration circulation line (33). The first refrigeration auxiliary heat exchanger (41-1) heat-exchanges the second refrigerant with the first refrigerant (-85°C) so that the first refrigerant has a temperature higher than at least -81°C and passes through it. The second refrigerant has a temperature lower than at least -72°C and is phase-changed into a liquefied refrigerant to ultra-low-temperature freeze the freezer of the logistics warehouse (80), and the vaporized refrigerant is transferred back to the first refrigeration auxiliary heat exchanger (41-1).

[0073] The second refrigeration auxiliary heat exchanger (41-2) exchanges heat with the second refrigerant with the first refrigerant having a temperature higher than at least -81°C transferred through the bypass line (31), so that the first refrigerant passes through with a temperature higher than at least -66°C, and the second refrigerant is phase-changed into a liquefied refrigerant having a temperature lower than at least -45°C to freeze the freezer of the logistics warehouse (80), and the vaporized refrigerant is transferred back to the second refrigeration auxiliary heat exchanger (41-2).

[0074] The third refrigeration auxiliary heat exchanger (41-3) heat-exchanges the second refrigerant with the first refrigerant having a temperature higher than at least -66°C transferred through the bypass line (31), so that the vaporized first refrigerant having a temperature higher than at least -12°C passes through, and the second refrigerant undergoes a phase change into a liquefied refrigerant having a temperature lower than at least -12°C, thereby freezing the freezer and refrigerator of the logistics warehouse (80), and the vaporized refrigerant is transferred back to the third refrigeration auxiliary heat exchanger (41-3).

[0075] And, the LNG gas vaporized at a temperature of 35°C in the second refrigeration heat exchanger (40-2) is transferred to the refrigeration heat exchanger (44) equipped in the LNG transfer line (20), and in the refrigeration heat exchanger (44), the heat-exchanged third refrigerant is phase-changed into a liquefied refrigerant at a temperature lower than at least 18°C, and is vaporized while cooling the refrigerator equipped in the load-side zone (Z3), and the vaporized refrigerant is circulated and transferred again to the refrigeration heat exchanger (44), so that the LNG vaporized gas is transferred to the LNG outlet (27) at a temperature higher than at least 15°C.

[0076] As described above, by utilizing the cold energy of LNG liquefied gas to liquefy the first to third refrigerants and configuring the logistics warehouse to be cooled in stages through latent heat exchange of the refrigerants, environmental protection can be improved through the utilization of cold energy and reduction of electricity costs, and the design and construction costs can be reduced by simplifying the configuration of the refrigeration circulation line and the cooling circulation line, thereby improving product competitiveness and reliability.

[0077] And, as an embodiment of the present invention, as shown in FIG. 2, the temperature of the vaporized refrigerant in the latent heat refrigeration circulation line (35) is detected, and when it is below the set temperature, the heat pump (60) is driven, and the third refrigerant is phase-changed to have a temperature higher than at least 18°C, thereby improving the heat exchange efficiency of the LNG vaporized gas transported from the LNG transport line (20) to the LNG outlet (27).

[0078] In addition, the latent heat refrigeration circulation line (35) in which the heat pump (60) is arranged may further include a bypass pipe (70) that connects the transfer and recovery lines in the line connection zone (Z2), and the third refrigerant that has exchanged heat by operating the valve member provided in the transfer and recovery line and the bypass pipe (70) is recovered in the line connection zone (Z2) without cooling the refrigerator in the logistics warehouse.

[0079] Accordingly, the process of cooling the refrigerator in the logistics warehouse through the bypass pipe (70) and heat pump (60) of the latent heat refrigeration circulation line (35) is omitted, and the LNG vaporized gas of the LNG transport line (20) is heated to a set temperature and supplied to demanders such as city gas and fuel cell power generation connected to the LNG outlet (27).

[0080] 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 transport line that is connected to the above LNG storage tank and LNG supply line, respectively, and receives liquefied gas from one selected direction and transports it toward the LNG outlet; A first refrigeration heat exchanger and a second refrigeration heat exchanger installed in front of the above LNG transport line to sequentially exchange heat with the transported liquefied gas and increase its temperature to vaporized gas; A first latent heat refrigeration circulation line configured to circulate and supply the first refrigerant, which has been liquefied through heat exchange in the first refrigeration heat exchanger, in a vaporized state to the second refrigeration heat exchanger; A plurality of refrigeration auxiliary heat exchangers, each connected to a plurality of bypass lines provided in the first latent heat refrigeration circulation line, which exchange heat with the first refrigerant liquefied by heat exchange in the first refrigeration heat exchanger; A second latent heat refrigeration circulation line that cools the logistics warehouse by liquefying the second refrigerant through heat exchange in the above-mentioned refrigeration auxiliary heat exchanger and supplies the liquefied second refrigerant to the refrigeration auxiliary heat exchanger for circulating; A refrigerated heat exchanger installed at the rear of the above LNG transport line to exchange heat with the transported vaporized gas; A latent heat refrigeration circulation line that refrigerates a logistics warehouse by exchanging heat with a liquefied third refrigerant in the above refrigeration heat exchanger and supplies the vaporized third refrigerant to the refrigeration heat exchanger for circulation; An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized by including an LNG discharge port that is connected to an LNG transport line after a refrigeration heat exchanger and discharges vaporized gas.

2. In paragraph 1, An optimal control cooling system utilizing the cold heat of LNG liquefied gas, characterized in that the LNG liquefied gas is heat-exchanged step by step through the above refrigeration heat exchanger and the vaporized gas having a temperature of at least -35°C or higher is supplied to the refrigeration heat exchanger.

3. In paragraph 1, The above refrigeration heat exchanger and refrigeration heat exchanger are, An optimal control cooling system utilizing cold energy of LNG liquefied gas, characterized in that it is arranged in a heat source side area where an LNG storage tank is located, and a plurality of refrigerated and frozen logistics warehouses are provided at a distance of at least 200 m from the LNG storage tank, and a load side area equipped with a refrigeration auxiliary heat exchanger for cooling the frozen logistics warehouses is arranged, and a line connection area is configured in which a refrigeration circulation line and a refrigeration circulation line connect between the heat source side area and the load side area.

4. In paragraph 1, Refrigeration heat exchanger, An optimal control cooling system utilizing the cold heat of LNG liquefied gas, characterized in that multiple units are installed in an LNG transport line, liquefied gas at a temperature lower than -150°C is supplied from a primary refrigeration heat exchanger installed in the front, and LNG gas vaporized at a temperature higher than at least -35°C is discharged to a refrigeration heat exchanger in an nth refrigeration heat exchanger installed in the rear.

5. In paragraph 1, Refrigeration auxiliary heat exchanger, The first refrigeration auxiliary heat exchanger, the second refrigeration auxiliary heat exchanger, and the third refrigeration auxiliary heat exchanger are each connected to the first latent heat refrigeration circulation line through a bypass line. The first refrigeration auxiliary heat exchanger is configured to exchange heat between the first refrigerant and the second refrigerant, which are transferred to the bypass line of the first latent heat refrigeration circulation line and have a temperature lower than at least -85°C, so that the second refrigerant is liquefied to have a temperature lower than at least -72°C and cools the first logistics warehouse, and the vaporized second refrigerant is circulated back to the first refrigeration auxiliary heat exchanger. The second refrigeration auxiliary heat exchanger is configured to exchange heat between the first refrigerant and the second refrigerant, which are transferred to the bypass line provided in the first latent heat refrigeration circulation line and have a temperature lower than at least -81°C, so that the second refrigerant is liquefied to have a temperature lower than at least -45°C and cools the second logistics warehouse, and the vaporized second refrigerant is circulated back to the second refrigeration auxiliary heat exchanger. The third refrigeration auxiliary heat exchanger is characterized in that it exchanges heat between the first refrigerant and the second refrigerant, which are transferred to the bypass line provided in the first latent heat refrigeration circulation line and have a temperature lower than at least -66°C, so that the second refrigerant is liquefied to have a temperature lower than at least -12°C and cools the third logistics warehouse, and the vaporized second refrigerant is circulated back to the third refrigeration auxiliary heat exchanger, which is an optimal control cooling system utilizing the cold heat of LNG liquefied gas.

6. In paragraph 1, The above first and second refrigerants are, An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized by being configured to be filled in the first latent heat refrigeration circulation line, the second latent heat refrigeration circulation line, and the latent heat refrigeration circulation line by selecting from among environmentally friendly refrigerant gases R-32, R-407C, R-410A, and R744.

7. In paragraph 1, An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized in that the above bypass line comprises a control valve that controls the transfer of the first refrigerant to the refrigeration auxiliary heat exchanger according to the set temperature of the logistics warehouse.

8. In claim 1, In the above LNG transport line, An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized in that a shut-off valve is further provided in the outlet direction of the refrigeration heat exchanger, and when the liquefied gas is heated to a set temperature, the shut-off valve is opened to transfer the liquefied gas to the refrigeration heat exchanger.

9. In claim 1, In the above latent heat refrigeration circulation line, An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized in that a heat pump is configured to detect the temperature of the vaporized refrigerant and operate when the temperature is below a set temperature, thereby causing a phase change of the third refrigerant to have a temperature higher than at least 18°C.

10. In claim 1, In the above latent heat refrigeration circulation line, An optimal control cooling system utilizing the cold energy of LNG liquefied gas, characterized in that a bypass pipe connecting the transfer and recovery lines in the line connection area is further formed, and the third refrigerant that has been heat-exchanged by the operation of a valve member provided in the transfer and recovery line and the bypass pipe is recovered in the line connection area.

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