Drying unit and reliquefaction system including the same

Abstract

A drying unit according to one aspect of the present invention is a drying unit included in a re-liquefaction system for re-liquefying evaporated gas generated from liquefied gas, and comprises: a nitrogen supply unit connected to a target device included in the re-liquefaction system for supplying nitrogen; and a purging unit connected to the target device for discharging moisture; wherein the purging unit comprises a flange connected at one end to the target device and a valve connected to the other end of the flange, and the valve may be connected to at least one of a dew point meter and a pressure gauge.

Description

Technology Field

[0001] The present invention relates to a drying unit and a re-liquefaction system including the same. Background Technology

[0002] Due to recent technological developments, liquefied gases such as Liquefied Natural Gas and Liquefied Petroleum Gas are being widely used to replace gasoline and diesel.

[0003] Liquefied natural gas is produced by cooling and liquefying methane obtained by refining natural gas extracted from gas fields; it is a colorless, transparent liquid with almost no pollutants and a high calorific value, making it an excellent fuel. On the other hand, liquefied petroleum gas consists of propane (C3H8) and butane (C4H8) that are produced along with petroleum from oil fields. 10 It is a fuel made by compressing a gas with ) as its main component into a liquid at room temperature. Like liquefied natural gas, liquefied petroleum gas is colorless and odorless and is widely used as fuel for household, commercial, industrial, and automotive use.

[0004] Such liquefied gases are stored in liquefied gas storage tanks installed on land or in liquefied gas storage tanks equipped on ships that are means of transport navigating the ocean. Liquefied natural gas is reduced to 1 / 600 of its volume upon liquefaction, and liquefied petroleum gas is reduced to 1 / 260 of the volume for propane and 1 / 230 of the volume for butane upon liquefaction, thus having the advantage of high storage efficiency. The temperature and pressure required to operate an engine that uses such liquefied gases as fuel may differ from the state of the liquefied gas stored in the tank.

[0005] In addition, when LNG is stored in liquid form, heat penetration into the tank causes some of the LNG to vaporize, generating boil-off gas (BOG). Since this boil-off gas can cause problems in the liquefied gas processing system, the problem was previously addressed by discharging and burning the boil-off gas externally (previously, the boil-off gas was simply discharged externally to lower tank pressure and eliminate the risk of tank damage). However, this method causes environmental pollution and resource waste. Therefore, a system for re-liquefying the boil-off gas and delivering it to the tank is being researched and developed.

[0006] Meanwhile, if the equipment of the reliquefaction system contains internal moisture, the moisture may condense and damage the equipment. Therefore, it is necessary to remove moisture from the equipment of the reliquefaction system.

[0007] To dry the equipment of the re-liquefaction system, a method is used in which the inside of the re-liquefaction equipment is depressurized to lower the boiling point and cause water to evaporate, and then nitrogen is injected to form a vacuum and discharge the water inside the re-liquefaction equipment to the outside.

[0008] A nitrogen supply unit is used to purge cargo system equipment, such as gas-liquid separators and piping for liquefied gas and boil-off gas, for nitrogen injection. Since this nitrogen supply unit is positioned at specific locations to supply nitrogen only to those specific locations and the nitrogen is discharged to the outside only from those specific locations, moisture may not be removed from some equipment throughout the re-liquefaction system.

[0009] Therefore, equipment is required that is connected to a re-liquefaction system and can dry the equipment included in the re-liquefaction system. The problem to be solved

[0010] The present invention was created to solve the problems of the prior art as described above, and the purpose of the present invention is to provide a drying unit that can supply nitrogen locally and discharge moisture by connecting it to a re-liquefaction system.

[0011] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0012] A drying unit according to one aspect of the present invention is a drying unit included in a re-liquefaction system for re-liquefying evaporated gas generated from liquefied gas, and comprises: a nitrogen supply unit connected to a target device included in the re-liquefaction system for supplying nitrogen; and a purging unit connected to the target device for discharging moisture; wherein the purging unit comprises a flange connected at one end to the target device and a valve connected to the other end of the flange, and the valve may be connected to at least one of a dew point meter and a pressure gauge.

[0013] Specifically, the target device is provided in a sealed area, and the valve can be connected to a hose extending outside the sealed area.

[0014] Specifically, the hose can discharge moisture at a pressure 0.1 to 1 bar lower than the back pressure formed when discharging moisture to the outside of the sealed area.

[0015] Specifically, the purging unit is detachable from the target device.

[0016] Specifically, the target device may be at least one of a heat exchanger, a separator, a filter, a compressor, a lubricating oil separator, a cooler, an expansion tank, a flash drum, and a line through which evaporated gas or refrigerant is delivered.

[0017] A re-liquefaction system according to one aspect of the present invention may include the drying unit. Effects of the invention

[0018] The drying unit of the present invention has the following effects.

[0019] The drying unit according to the present invention includes a nitrogen supply unit and a purging unit, and the nitrogen supply unit and the purging unit may be connected to a reliquefaction system by including a flange, so that it is possible to locally dry the reliquefaction system.

[0020] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0021] FIG. 1 is a schematic diagram of a re-liquefaction system according to one embodiment of the present invention. Figure 2 is a photograph showing a nitrogen supply unit according to one embodiment of the present invention. FIG. 3 is a photograph showing a purging section according to one embodiment of the present invention. Specific details for implementing the invention

[0022] The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. It should be noted that in assigning reference numerals to the components of each drawing in this specification, identical components are assigned the same number whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the invention.

[0023] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0024] FIG. 1 is a schematic diagram of a reliquefaction system according to one embodiment of the present invention. FIG. 2 is a photograph showing a nitrogen supply unit according to one embodiment of the present invention. FIG. 3 is a photograph showing a purging unit according to one embodiment of the present invention.

[0025] Referring to FIG. 1, a re-liquefaction system (1) according to one embodiment of the present invention includes a heat exchanger (100), and the heat exchanger (100) can liquefy evaporated gas delivered from a cargo tank (not shown) through a cargo line (L1). The evaporated gas delivered to the heat exchanger (100) can be compressed in a compressor (not shown) and then supplied to the heat exchanger (100).

[0026] At this time, the liquefied evaporated gas from the heat exchanger (100) can be separated through the flash drum (900) and transferred to the cargo tank. The gaseous refrigerant in the flash drum (900) can be supplied back to the compressor with a certain high pressure.

[0027] In the lines included in the re-liquefaction system (1) of the present invention, the refrigerant circulates, and each line shares the refrigerant with one another through a shared line. Therefore, each line may not form a perfect closed circuit, and in the connected lines, some of the refrigerant may be mixed or divided.

[0028] The refrigerant can be delivered to the heat exchanger (100) along the refrigerant line (L2). The refrigerant can go down to the heat exchanger (100) along the refrigerant line (L2) inside the heat exchanger (100). At this time, the refrigerant can be cooled while passing through the pressure reducing valve (V2) provided in the refrigerant line (L2).

[0029] The refrigerant can be transferred back to the heat exchanger (100) along the refrigerant line (L2), and can pass through the heat exchanger (100) and be transferred to the compressor (500) along the compression line (L3). The compressor (500) can be operated by a motor (510).

[0030] The refrigerant passing through the compressor (500) is transferred to the lubricating oil separator (600), and the lubricating oil is separated from the refrigerant in the lubricating oil separator (600) and transferred to an oil section (not shown in the symbol) located below the lubricating oil separator (600).

[0031] The refrigerant can be separated from the lubricating oil and delivered to the cooler (710, 720) along the cooler line (L4). The cooler (710, 720) includes a first cooler (710) and a second cooler (720), and the first cooler (710) and the second cooler (720) can be configured in parallel.

[0032] The refrigerant cooled in the first cooler (710) and the second cooler (720) can be transferred to the heat exchanger (100) along the cooler line (L4).

[0033] The cooler line (L4) branches off from the downstream of the first cooler (710) and the second cooler (720), and the branch line (L5) formed therein can be connected to the compression line (L3) and can be connected to the expansion tank line (L6) which is connected to the expansion tank (800).

[0034] Meanwhile, the refrigerant delivered to the heat exchanger (100) along the cooler line (L4) can be delivered to the separator (200) along the filter line (L7). The refrigerant that has passed through the separator (200) can pass through the first filter (300) and the second filter (400).

[0035] In the separator (200), the liquid refrigerant and the gaseous refrigerant are separated, and the liquid refrigerant can be transferred to the heat exchanger (100) after passing through the pressure reducing valve (V1), and the refrigerant can be combined with the refrigerant in the refrigerant line (L2). The gaseous refrigerant can be transferred to the heat exchanger (100) through the first filter (300) and the second filter (300).

[0036] Meanwhile, during the drying process, the inside of the equipment of the re-liquefaction system (1) is first made into a vacuum (2.6 mbar A), and when the boiling point changes to about -10°C in the vacuum state, water evaporates, and then nitrogen is injected and the vacuum is made again.

[0037] Since the nitrogen supply unit and the purging unit provided in the re-liquefaction system (1) are fixedly installed in a portion of the area, moisture can be removed in the area close to the nitrogen supply unit and the purging unit, and moisture cannot be removed in the area far from the nitrogen supply unit and the purging unit.

[0038] A re-liquefaction system (1) according to one embodiment of the present invention may include a detachable drying unit, and the drying unit may include a nitrogen supply unit (N) and a purging unit (P).

[0039] The nitrogen supply unit (N) is a device that supplies nitrogen to the equipment of the re-liquefaction system (1), and is not limited to any type or form, as long as it can supply nitrogen to the re-liquefaction system (1), such as a storage container in which nitrogen gas is stored or a nitrogen gas generator that generates nitrogen gas.

[0040] Referring to FIG. 2, the nitrogen supply unit (N) may include a flange and a hose, and may be connected to the piping of the reliquefaction system (1) through the flange and hose.

[0041] The purging unit (P) is a device that discharges nitrogen, water, etc. to the outside from the re-liquefaction system (1). Referring to FIG. 3, the purging unit (P) may be composed of a flange, a valve, and a hose. The purging unit (P) is composed of a flange, a valve, and a hose as a single unit and can perform the function of discharging nitrogen, water, etc. to the outside by being connected to a device of the re-liquefaction system (1). It may include a pump to lower the pressure inside the device of the re-liquefaction system (1), and the hose may be connected to the pump.

[0042] One end of the flange can be connected to a target device of the re-liquefaction system (1), and the other end can be connected to and disconnected from a valve. The target device may be at least one of a heat exchanger, a separator, a filter, a compressor, a lubricating oil separator, a cooler, an expansion tank, a flash drum, and a line through which evaporated gas or refrigerant is delivered, and the present invention is not limited thereto, and any device included in the re-liquefaction system (1) may be included in the target device.

[0043] The valve may be connected to at least one hose, and the hose may be connected to a dew point or extended outside the compressor room.

[0044] A dew point meter can measure the dew point in the device of the re-liquefaction system (1). During the drying process, the inside of the equipment of the re-liquefaction system (1) is first made into a vacuum (2.6 mbar A), and when the boiling point changes to about -10°C in a vacuum state, moisture evaporates, at which point nitrogen is injected and the vacuum is created again. After creating a vacuum, the dew point can be measured using a dew point meter to confirm whether moisture has been removed from the device of the re-liquefaction system (1).

[0045] In addition to the dew point meter, the hose can be connected to a pressure gauge. Since the pressure changes as moisture evaporates, the pressure gauge can check whether moisture has been removed from the device of the reliquefaction system (1) by checking whether the device of the reliquefaction system (1) is maintained in a vacuum state.

[0046] If it is determined through a dew point meter or pressure gauge that moisture has not been removed from the device of the re-liquefaction system (1), the drying process may be repeated.

[0047] In addition, the device of the re-liquefaction system (1) is generally installed inside the compressor room, but there is a risk that workers inside the compressor room may suffocate when nitrogen is discharged from the compressor room, which is a sealed space. Therefore, the hose of the purging unit (P) can be extended outside the compressor room to discharge the nitrogen discharged from the purging unit (P) to the outside.

[0048] The hose may be a 1-inch hose. The hose is capable of purging at a pressure 0.1 to 1 bar lower than that formed when nitrogen is discharged to the outside of the compressor room, and preferably at a pressure 0.2 to 0.3 bar lower. The hose may have a diameter smaller than a 1-inch hose, in which case an additional hose may be provided.

[0049] Referring to FIG. 1, at least one nitrogen supply unit (N) may be provided in the re-liquefaction system (1). For example, a first nitrogen supply unit (N1) may be provided downstream of the cooler (710, 720) on the cooler line (L4), a second nitrogen supply unit (N2) may be provided on the compression line (L3), and a third nitrogen supply unit (N3) may be provided on the expansion tank line (L6).

[0050] At least one purging section (P) may be provided in the re-liquefaction system (1). For example, a first purging section (P1) may be provided downstream of the separator (30) on the filter line (L7), a second purging section (P2) may be provided downstream of the heat exchanger (100) on the refrigerant line (L2), a third purging section (P3) may be provided in the oil section (not shown in the symbol), and a fourth purging section (P4) may be provided on the lubricating oil separator line (L8) connecting the filter (300, 400) and the lubricating oil separator (600).

[0051] The locations where the nitrogen supply unit (N) and the purging unit (P) are provided are examples of locations where moisture is not removed. The first nitrogen supply unit (N1) to the third nitrogen supply unit (N3) and the first purging unit (P1) to the fourth purging unit (P4) may be provided, and additional nitrogen supply units (N) and purging units (P) may be provided.

[0052] Depending on the location where the nitrogen supply unit (N) is installed, the arrangement of the purging unit (P) may vary, and conversely, depending on the location where the purging unit (P) is installed, the arrangement of the nitrogen supply unit (N) may vary. For example, the nitrogen supply unit (N) and the purging unit (P) may be arranged in pairs, and it is preferable for the nitrogen supply unit (N) and the purging unit (P) to be arranged in close proximity to each other. For example, if nitrogen is supplied from the first nitrogen supply unit (N1), purging may occur in the first purging unit (P1) or the second purging unit (P2), and as another example, if nitrogen is supplied from the second nitrogen supply unit (N2), purging may occur in the third purging unit (P3) or the fourth purging unit (P4).

[0053] As such, since the drying unit (N, P) according to one embodiment of the present invention is detachable from the device of the re-liquefaction system (1), moisture can be removed by supplying nitrogen to an area where moisture has not been removed and purging.

[0054] In addition, while removing moisture, the status of moisture removal can be checked in real time by measuring the dew point or pressure.

[0055] The present invention is not limited to the embodiments described above, and it is obvious that it may include a combination of the above embodiments or a combination of at least one of the above embodiments and known technology as another embodiment.

[0056] Although the present invention has been described above with reference to embodiments, this is merely illustrative and does not limit the invention. Those skilled in the art will understand that various combinations, modifications, and applications not exemplified in the embodiments are possible without departing from the essential technical content of the embodiments. Therefore, technical details regarding modifications and applications that can be easily derived from the embodiments of the present invention should be interpreted as being included in the present invention. Explanation of the symbols

[0057] 100: Heat exchanger 200: Separator 300: 1st filter 400: 2nd filter 500: Compressor 510: Motor 600: Lubricant separator 710: 1st cooler 720: 2nd Cooler 800: Expansion Tank 900: Flashdrum L1: Cargo Line L2: Refrigerant Line L3: Compression line L4: Cooler line L5: Branch line L6: Expansion tank line L7: Filter line L8: Lubricating oil separator line N: Nitrogen supply unit N1: 1st nitrogen supply unit N2: 2nd nitrogen supply unit N3: 3rd nitrogen supply unit P: Purging Unit P1: 1st Purging Unit P2: 2nd Purging Section P3: 3rd Purging Section P4: 4th Purging Section

Claims

Claim 1 A drying unit included in a reliquefaction system for reliquefying evaporated gas generated from liquefied gas, comprising: a nitrogen supply unit connected to a target device included in the reliquefaction system for supplying nitrogen; and a purging unit connected to the target device for discharging moisture; wherein the purging unit comprises a flange connected at one end to the target device and a valve connected to the other end of the flange, wherein the valve is connected to at least one of a dew point meter and a pressure gauge, wherein the target device is provided in a sealed area, and the valve is connected to a hose extending outside the sealed area, and wherein the purging unit is detachable from the target device and, when discharging moisture from the sealed area, back pressure is formed to enable purging at a low pressure of 0.1 to 1 bar. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 In claim 1, the target device comprises a drying unit that is at least one of a heat exchanger, a separator, a filter, a compressor, a lubricating oil separator, a cooler, an expansion tank, a flash drum, and a line through which evaporated gas or refrigerant is delivered. Claim 6 A re-liquefaction system comprising the drying unit according to either claim 1 or claim 5.

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