JP2003106498A - LNG tank BOG reliquefaction recovery system - Google Patents

Abstract

(57) [Problem] To provide an inexpensive LNG tank BOG reliquefaction and recovery system that can effectively use existing equipment. SOLUTION: A BOG delivery line 8 is connected to an LNG tank 1.
Is connected to an air release line 3 for releasing the BOG generated in the above to the atmosphere and a refrigerator 9 for reliquefying the BOG with cold heat. Liquefied B for storing liquefied BOG in refrigerator 9
The OG tank 10 is connected. The liquefied BOG tank 10 is connected to the liquefied BO connected to the LNG receiving line 2.
A G transfer line 11 is connected to a booster line 12 that evaporates and boosts the liquefied BOG, and supplies the BOG boosted by the booster line 12 to the liquefied BOG tank 10 to increase the internal pressure of the liquefied BOG tank 10. Liquefied BOG
From the liquefied BOG tank 10 to the liquefied BOG transfer line 11
To send out.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to reliquefaction of boil-off gas (hereinafter abbreviated as “BOG”) generated in an LNG tank that stores liquefied natural gas (hereinafter abbreviated as “LNG”). , LNG tank BOG reliquefaction recovery system for recovering reliquefied liquefied BOG in an LNG tank.

[0002]

2. Description of the Related Art Conventionally, an automobile (hereinafter abbreviated as "CNG vehicle") that uses compressed natural gas (hereinafter abbreviated as "CNG") obtained by compressing natural gas as fuel has been put into practical use. CNG stand for supplying CNG to CNG vehicles is being constructed. In areas where gas conduits are not installed, CNG stands are replaced by LNG because gas cannot be obtained directly from the gas conduits.
Equipped with facilities. FIG. 4 shows a schematic configuration of the CNG stand 100 including the LNG equipment 101.

[0003] LNG is transported by LNG truck 102 or the like and received in LNG tank 103 of LNG facility 101. A vaporizer 105 is connected to the LNG tank 103 via a pump 104 to pump the LNG to the pump 10
After increasing the pressure to about 20 to 30 MPa at 4, the vaporizer 10
It vaporizes at 5. The CNG thus generated is stored in the gas storage device 106 and is supplied to the CNG vehicle 108 via the dispenser 107.

In the LNG tank 103, the LNG
Is stored at about −164 ° C., and is vaporized by heat entering from the outside to generate BOG. If the BOG is retained in the LNG tank 103, the internal pressure of the LNG tank 103 increases, and the LNG tank 103 needs to have high pressure resistance. It is necessary to prevent the internal pressure from becoming excessive.

At this point, BOG may be stored in the gas storage unit 106 or supplied to the CNG vehicle 108.
The pressure of BOG generated from the NG tank 103 is 1MP
Since it is less than a, it is substantially difficult. So BO
It is necessary to consume G in-house in the LNG facility 101 or dissipate it into the atmosphere.

[0006]

However, private consumption of BOG is limited to a very limited number of cases. However, if released to the atmosphere, it is a combustible material, which is dangerous for disaster prevention and leads to the destruction of the ozone layer. Further, since LNG is composed of a multi-component system such as methane and butane, there is a problem that the component of LNG stored in the LNG tank 103 changes due to the emission of BOG containing methane as a main component.

Therefore, it is conceivable to install the refrigerator in the LNG tank to reliquefy and collect the BOG generated in the LNG tank. FIG. 5 shows an example of the LNG tank BOG reliquefaction recovery system 110 in which the refrigerator 111 is installed inside the LNG tank 103. As shown in FIG. 5, the refrigerator 111 is attached to the top of the LNG tank 103 in which BOG accumulates, and the B generated in the LNG tank 103 is discharged.
OG is reliquefied by the cold heat of the refrigerator 111, and LN is liquefied by its own weight.
Drop it on the liquid surface of G and collect it.

However, such an LNG tank BOG reliquefaction recovery system 110 has the following problems.
That is, it was necessary to change the pressure resistance of the LNG tank 103, and it was not possible to easily install the LNG tank 103 in the existing LNG tank 103. Therefore, the existing LNG tank 1
There is a problem that a large design change of 03 is required, which leads to cost increase. Especially, general CNG stand 10
The LNG tank 103 of about 20 Kl used at 0 is
In many cases, line production is performed with general-purpose products, and the production cost of the LNG tank 103 is significantly increased. In addition, the LNG equipment 10 already installed on the CNG stand 100
When the BOG reliquefaction recovery system 110 is incorporated in the first LNG tank 103, it is difficult to retrofit the refrigerator 111 to the existing LNG tank 103.
Needs to be replaced with the LNG tank 103 containing the refrigerator 111, which causes a problem that the facility cost is high. Therefore,
It is desirable to externally attach a system for reliquefying and recovering BOG to the LNG tank.

On the other hand, the present inventors have proposed the refrigerator 111
Externally connected to the existing LNG tank 103. In this case, the BOG generated in the LNG tank 103 is sent to the external pipe and re-liquefied in the refrigerator 111.
The reliquefied liquefied BOG is stored in a tank and transferred to the LNG tank 103. However, in such a measure, it is necessary to send the liquefied BOG from the tank to the LNG tank 103 by a pump or the like, which increases the facility cost of the pump and the like and the maintenance cost, which causes a problem of cost increase.

Therefore, an object of the present invention is to provide an inexpensive LNG tank BOG reliquefaction recovery system which can effectively utilize the existing equipment.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 reliquefies BOG generated from an LNG tank storing LNG, and reliquefied liquefied BO.
In the LNG tank BOG reliquefaction recovery system for recovering G into the LNG tank, the BOG which is connected to the external pipe for discharging the BOG of the LNG tank and sends out the BOG
A delivery line, a cooling device connected to the BOG delivery line to cool and reliquefy the BOG, and a liquefied BO connected to the cooling device and storing the liquefied BOG reliquefied by the cooling device
G tank, a pressure increasing device for increasing the internal pressure of the liquefied BOG tank, and LNG for the liquefied BOG tank and the LNG tank.
And a liquefied BOG transfer line for transferring liquefied BOG, which is connected to an external pipe for receiving the liquefied BOG. To L
Transfer to an NG tank.

Therefore, according to the first aspect of the invention, the BOG delivery line and the liquefied BOG transfer line are respectively connected to the external pipe for discharging the BOG and the external pipe for receiving the LNG in the existing LNG tank. . Therefore, the present system does not need to change the design of the existing LNG tank and can be installed without modifying or replacing the existing LNG tank. LN
BOG generated from the G tank is sent out to the cooling device via the BOG sending line and reliquefied. The reliquefied liquefied BOG is stored in the liquefied BOG tank, and when the booster boosts the internal pressure of the liquefied BOG tank,
The liquid surface is pressurized and sent from the liquefied BOG tank to the liquefied BOG transfer line. And liquefied BOG is liquefied B
It flows into an external pipe for receiving LNG from the OG transfer line and is collected in the LNG tank. in this way,
Since the liquefied BOG can be switched between storage and transfer due to pressure fluctuations in the liquefied BOG tank, it is possible to reduce equipment costs such as pumps and maintenance costs. Therefore, according to the invention as set forth in claim 1, it is possible to effectively utilize the existing equipment and to reduce the equipment cost, maintenance cost, and the like to reduce the cost.

The invention described in claim 2 is the same as claim 1
The pressure booster is a pressure booster line that is connected to the lower part and the upper part of the liquefied BOG tank to vaporize and pressurize the liquefied BOG sent from the lower part of the liquefied BOG tank.

Therefore, according to the invention described in claim 2, in addition to the function of the invention described in claim 1, the booster line has a liquefied B
The liquefied BOG flowing from the bottom of the OG tank is vaporized,
The BOG is supplied to the upper part of the liquefied BOG tank. In the liquefied BOG tank, the internal pressure is increased by the BOG supplied from the pressure increase line, and the liquefied BOG is sent to the liquefied BOG transfer line. Therefore, in the invention described in claim 2, the liquefied BOG stored in the liquefied BOG tank is LNG under its own pressure.
Since it is collected in the tank, equipment costs, maintenance costs, etc. can be suppressed more than in the invention according to claim 1.

The invention described in claim 3 is the same as that of claim 2
The invention according to claim 1, further comprising: a first valve provided on the BOG delivery line, a second valve provided on the liquefied BOG transfer line, and a third valve provided on the pressurization line. When storing the liquefied BOG, the first valve is opened while the second valve and the third valve are closed,
When transferring the liquefied BOG, the second valve and the third valve are opened while the first valve is closed.

Therefore, in the invention described in claim 3, in addition to the function of the invention described in claim 2, when the second and third valves are closed and only the first valve is opened, B generated in LNG is generated.
The OG is sent out to the cooling device via the BOG sending line to be reliquefied and stored in the liquefied BOG tank. When the first valve is closed and the second and third valves are opened,
BOG generated in the LNG tank is no longer sent to the cooling device. On the other hand, the liquefied BOG flowing from the liquefied BOG tank is vaporized, and the pressurized BOG is supplied to the liquefied BOG tank, and the liquefied BOG is sent to the liquefied BOG transfer line. Therefore, in addition to the effect of the invention described in claim 2, the invention described in claim 3 can easily switch the storage and transfer of the liquefied BOG simply by opening and closing the first to third valves. Excellent operability.

The invention according to claim 4 is the same as claim 1.
The invention according to any one of claims 1 to 3 is characterized in that a liquid amount detection device for detecting the liquid amount of the liquefied BOG stored in the liquefied BOG tank is provided. Therefore, in the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the liquefied BOG confirms the prescribed liquid amount based on the liquid amount detection device. Therefore, it is very safe.

The invention described in claim 5 is the same as claim 1.
The invention according to any one of claims 4 to 4 is characterized by comprising an automatic switching control device for switching between storage and transfer of the liquefied BOG based on a detection result of the liquid amount detection device. Therefore, in the invention described in claim 5,
In addition to the action and effect of the invention according to any one of claims 4 to 4, when the liquefied BOG reaches a prescribed liquid amount, the liquefied BOG is automatically transferred to the LNG tank, so that the liquefied BOG can be easily managed. become.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The LNG tank BO of the present invention will be described below.
An embodiment of the G reliquefaction recovery system will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an LNG tank BOG reliquefaction recovery system 7. In LNG tank 1,
External piping LNG receiving line 2 and atmospheric emission line 3
Are connected. The LNG receiving line 2 is for receiving LNG from an LNG truck or the like (not shown), and the atmospheric diffusion line 3 is a BNG generated in the LNG tank 1.
It is for releasing OG into the atmosphere. The LNG receiving line 2 is provided with a valve 4. On the other hand, a valve 6 is provided in the atmospheric diffusion line 3, and by opening and closing the valve 6, the atmospheric diffusion process can be performed when the internal pressure of the LNG tank 1 abnormally rises.

The LNG tank BOG reliquefaction recovery system of the present embodiment (hereinafter abbreviated as "recovery system").
7 is installed in the existing equipment by being connected to the LNG receiving line 2 and the atmospheric diffusion line 3. That is, in the “collection system” 7, the BOG sending line 8 is
It is connected to the atmospheric diffusion line 3 on the upstream side of the valve 6. The BOG delivery line 8 has a refrigerator 9 as a cooling device.
To send the BOG to the refrigerator 9. A liquefied BOG tank 10, which will be described later, is connected to the refrigerator 9. The liquefied BOG tank 10 contains liquefied BOG.
The transfer line 11 is connected, and the liquefied BOG transfer line 11 is connected to the LNG receiving line 2 on the downstream side of the valve 4.
Connected to. Therefore, BOG generated from LNG
Is collected in the LNG tank 1 through the air diffusion line 3, the “collection system” 7, and the LNG receiving line 2.

The liquefied BOG tank 10 is connected to a pressure boosting line 12, which is a pressure boosting device, at its upper and lower portions. The pressurization line 12 includes a vaporization section 12a for vaporizing the liquefied BOG sent from the lower portion of the liquefied BOG tank 10.
BOG tank for liquefying BOG vaporized in the vaporization section 12a
It is composed of a withdrawal unit 12b for withdrawing money to the upper part of 0. Further, in the payout unit 12b of the boosting line 12, the BOG
LNG tank 1 and liquefied BOG branched from the delivery line 8
Pressure equalizing line 5 for equalizing the internal pressure of the tank 10.
Are connected.

Then, the BOG delivery line 8 and the liquefied BOG
First to fourth valves 13 to 16 are provided in the transfer line 11, the vaporizing section 12 a of the pressurizing line 12, and the pressure equalizing line 5. The first to fourth valves 13 to 16 are electromagnetic proportional on-off valves that are connected to a control device (not shown) and operate to open and close by switching between energization and de-energization.

The liquefied BOG tank 10 described above will be described. FIG. 2 is a schematic configuration diagram of the liquefied BOG tank 10. The liquefied BOG tank 10 has a double structure in which an inner layer 17 made of stainless steel is provided inside an outer layer 18 made of high-tensile steel or stainless steel. A line 20 into which the liquefied BOG reliquefied in the refrigerator 9 flows is connected to the inner layer 17, while a liquefied BOG transfer line 11 is inserted so that the tip portion does not contact the bottom portion. Also, the inner layer 17
The vaporization part 12a of the boosting line 12 is connected to the lower part of the pumping line 12, and the payout part 12b of the boosting line 12 is connected to the upper part thereof. The vaporization part 12 a of the pressurization line 12 is taken out from the lower part of the inner layer 17 to the upper part of the liquefied BOG tank 10 through a space formed between the inner layer 17 and the outer layer 18. A pressure holding coil (not shown) is attached to the inner wall of the outer layer 18 in order to vaporize the liquefied BOG supplied from the lower portion of the liquefied BOG tank 10. The outer layer 18 is provided in the space formed between the inner layer 17 and the outer layer 18.
In order to minimize the evaporation of the liquefied BOG due to the heat of the outside air surrounding it, heat insulation is provided.

The liquefied BOG tank 10 is arranged on the liquid amount detection device 19. The liquid amount detection device 19 measures the weight of the liquefied BOG tank 10 and detects the liquid amount of the liquefied BOG stored in the inner layer 17. The liquid amount detection device 19 is connected to a control device (not shown) to which the first to fourth valves 13 to 16 are connected, and manages the detection result. The control device (not shown) stores a program for controlling the operating state of the refrigerator 9 and the open / close valve states of the first to fourth valves 13 to 16 based on the detection result of the liquid amount detection device 19. . FIG. 3 is a diagram showing an operating state of the refrigerator 9 and open / close valve states of the first to fourth valves 13 to 16, where “◯” indicates an open state and “x” indicates a closed state. .

In the present embodiment, as shown in FIG. 3, the control device (not shown) operates the refrigerator 9 when the liquid amount detecting device 19 does not detect the prescribed liquid amount, and
The first valve 13 and the fourth valve 16 are controlled to the open state, and the second valve 14 and the third valve 15 are controlled to the closed state. Further, the control device (not shown) is the liquid amount detection device 1
When 9 detects the specified liquid amount, the operation of the refrigerator 9 is stopped and the first valve 13 and the fourth valve 16
To the closed state, and the second valve 14 and the third valve 1
Control valve 5 in the open state. Further, the control device (not shown) stops the operation of the refrigerator 9 while the "recovery system" 7 is in the standby state, and also controls the first to third valves 13 to.
The valve 15 is controlled to be closed, and the fourth valve 16 is controlled to be opened.

Next, the "collection system" having the above structure
The operation of No. 7 will be described. When the BOG generated in the LNG tank 1 has not reached the predetermined pressure, the fourth valve 1
Only 6 is opened, and the first to third valves 13 to 15 are closed to stand by. Further, in the air diffusion line 3, the valve 6 is closed to prevent a change in the LNG component. Therefore, BOG generated in LNG
Is sent to the atmospheric diffusion line 3, the BOG sending line 8 and the pressure equalizing line 5, and further, the payback unit 1 of the pressurizing line 12
Since it is supplied to the liquefied BOG tank 10 from 2b, the LN
The internal pressures of the G tank 1 and the liquefied BOG tank 10 are equalized. Since the first valve 13 is closed, B
The OG is not sent to the refrigerator 9. In addition, the operation of the refrigerator 9 is stopped, and wasteful use of electric power or the like for operating the refrigerator 9 is avoided.

When the BOG in the LNG tank 1 reaches a predetermined pressure, the refrigerator 9 starts operating. Also, while the first valve 13 is switched from the closed state to the open state,
The second valve 14 and the third valve 15 maintain the closed state, and the fourth valve 16 maintains the open state. L
The BOG generated in the NG tank 1 flows into the refrigerator 9 by itself, is reliquefied, and is filled in the liquefied BOG tank 10.

Since the second valve 14 is controlled to be closed, the liquefied BOG is blocked by the second valve 14 and is not transferred from the liquefied BOG transfer line 11 to the LNG receiving line 2. Further, since the third valve 15 is controlled to be in the closed state and the fourth valve 16 is controlled to be in the open state, a part of the BOG sent to the BOG sending line 8 passes through the fourth valve 16 and is evened. Although it flows into the pressure line 5, it is blocked by the third valve 15. Therefore, the BOG flowing into the pressure equalizing line 5 flows into the liquefied BOG tank 10 from the payout portion 12b of the pressurizing line 12, and the internal pressure of the pressure equalizing line 5, the payout portion 12b of the pressurizing line 12 and the liquefied BOG tank 10 is changed to the LNG tank. Make the internal pressure equal to 1.

In this way, the liquefied BOG is liquefied
When the tank 10 is continuously filled, the liquefied BOG reaches the specified liquid amount. At this time, the liquid amount detection device 19 is
Detects that it has reached a prescribed liquid amount, and sends that fact to a control device (not shown). The control device (not shown) stops the refrigerator 9 and also controls the first to fourth valves 13 to 16
The on / off valve state of is automatically switched. That is, the first valve 13 and the fourth valve 16 are automatically switched from the open state to the closed state, and the second valve 14 and the third valve 16 are automatically switched.
The valve 15 is automatically switched from the closed state to the open state. As a result, the BOG generated in the LNG tank 1 is
The liquefied BOG is no longer sent to the refrigerator 9, and the liquefied BOG becomes liquefied BO.
The G tank 10 is no longer filled.

On the other hand, the liquefied BOG stored in the liquefied BOG tank 10 is opened by opening the third valve 15.
Flow into the vaporizing section 12a of the pressure rising line 12, and are vaporized by heat input such as outside air temperature by a pressure-holding coil (not shown) installed in the space between the inner layer 17 and the outer layer 18, and the fourth valve 16 of the pressure equalizing line 5 Downstream side and withdrawal section 12 of pressurization line 12
Boost b. The boosted BOG is supplied to the inner layer 17 of the liquefied BOG tank 10 and pressurizes the liquid surface of the liquefied BOG in the inner layer 17. Therefore, the liquefied BOG is sent from the liquefied BOG tank 10 to the liquefied BOG transfer line 11, passes through the second valve 14, and passes through the LNG receiving line 2 at the L level.
It merges with NG and is received in LNG tank 1 together with LNG.

Therefore, the "collection system" of the present embodiment
7, the atmospheric diffusion line 3 and the LNG receiving line 2
In addition, the BOG delivery line 8 and the liquefied BOG transfer line 11
It can be incorporated into existing equipment simply by connecting the LNG tank 1 to the existing equipment, and there is no need to change the design of the existing LNG tank 1 or modify or replace the existing LNG tank 1. Therefore, the existing equipment can be effectively used. Moreover, liquefied BOG
By increasing the internal pressure of the tank 10, liquefaction B
Since OG is sent from the liquefied BOG tank 10 to the liquefied BOG transfer line 11, it is not necessary to use a pump or the like,
It is possible to reduce the cost by suppressing the equipment cost and maintenance cost.

Particularly, the liquefied BOG tank 10 is
The internal pressure is boosted by the BOG that vaporizes the liquefied BOG by the outside air temperature or the like by using a pressure-holding coil (not shown) provided in the G tank 10 to increase the internal pressure. No need to provide. Therefore, liquefied BO
The internal pressure of the G tank 10 can be increased by its own pressure,
Equipment costs and maintenance costs can be suppressed more effectively. Moreover, since the structure is simple, the entire system can be made compact.

Further, since the storage and transfer of the liquefied BOG can be easily switched by simply opening and closing the first to fourth valves 13 to 16, the operability is excellent. Further, the liquid amount can be confirmed by the liquid amount detecting device 19, which is excellent in safety. Further, when the liquefied BOG reaches a prescribed liquid amount, a control device (not shown) causes the first to fourth valves 13 to 16 to operate.
Since the on-off valve state is automatically switched, the liquefied BOG can be easily managed.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

(1) For example, in the above embodiment, the liquefied BOG in the liquefied BOG tank 10 is vaporized to increase the internal pressure. On the other hand, the liquefied BOG tank 10 may be provided with a pressure increasing device for increasing the internal pressure.

(2) For example, in the above embodiment, the pressure-holding coil provided in the liquefied BOG tank 10 is heated to the outside air temperature to vaporize the liquefied BOG in the pressure-increasing line 12 so that the pressure-increasing line 12 is discharged. Boosted. On the other hand, a heating device such as a heater may be attached on the boosting line 12 to heat the pressure.

(3) For example, in the above embodiment, the first
An electromagnetic proportional on-off valve was used as the fourth valves 13 to 16. On the other hand, an air operated on-off valve, a hydraulic on-off valve or the like may be used.

(4) For example, in the above embodiment, the control device (not shown) automatically opens and closes the first to fourth valves 13 to 16 based on the detection result of the liquid amount detection device 19,
The storage and transfer of liquefied BOG were switched. On the other hand, a manual valve may be used for the first to fourth valves 13 to 16, and the storage and transfer of the liquefied BOG may be manually switched.

(5) For example, in the above embodiment, the refrigerator 9 is provided outside the liquefied BOG tank 10. On the other hand, the refrigerator 9 may be provided in the liquefied BOG tank 10. As a result, the structure of the “collection system” 7 is further simplified, and the entire system can be made more compact.

(6) For example, in the above embodiment, only one liquefied BOG tank 10 is provided. On the other hand, by installing a plurality of liquefied BOG tanks 10,
When one of the liquefied BOG tanks 10 is completely filled with G, the liquefied BOG tank 10 may be switched to another liquefied BOG tank 10 by automatic operation or manual operation, and storage and transfer of the liquefied BOG tank may be switched by automatic operation or manual operation. .

[0041]

As described above, according to the invention described in claim 1, it is connected to the external pipe for discharging the BOG of the LNG tank, and the BOG sending line for sending the BOG and the BOG sending line are provided. A cooling device connected to the cooling device to cool and reliquefy the BOG; a liquefied BOG tank connected to the cooling device to store the liquefied BOG reliquefied by the cooling device; and a booster device to increase the internal pressure of the liquefied BOG tank. , A liquefied BOG tank and a LNG tank connected to an external pipe for receiving LNG, and a liquefied BOG transfer line for transferring the liquefied BOG, and by increasing the internal pressure of the liquefied BOG tank, By transferring the stored liquefied BOG from the liquefied BOG tank to the LNG tank, it is possible to effectively utilize the existing equipment, and further, to install the equipment. It can be cheaper at a lower cost and maintenance expenses.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an LNG tank BOG reliquefaction recovery system according to an LNG tank BOG reliquefaction recovery system of the present embodiment.

FIG. 2 is also a schematic configuration diagram of a liquefied BOG tank.

[Fig. 3] Similarly, the operating state of the refrigerator and the first to fourth
It is a table | surface which shows the opening / closing valve state of a valve, "O" shows a valve opening state, "X" shows a valve closing state.

FIG. 4 is a schematic configuration diagram of a conventional CNG stand.

FIG. 5 is a diagram showing an example of a conventional LNG tank BOG reliquefaction recovery system.

[Explanation of symbols]

1 LNG tank 2 LNG receiving line 3 Atmospheric emission line 7 LNG tank BOG reliquefaction recovery system 8 BOG transmission line 9 refrigerator 10 Liquefied BOG tank 11 Liquefied BOG transfer line 12 boost line 13 First valve 14 Second valve 15 Third valve 19 Liquid level detector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nao Haruta             Aichi Prefecture Nagoya City Atsuta Ward Sakuradacho 19-18 East             Within Japan Gas Co., Ltd. F-term (reference) 3E073 AA01 DD03                 4D047 AA10 AB08 BA07 BA09 DA11

Claims (5)

[Claims] 1. An LNG tank BOG reliquefaction recovery system for reliquefying BOG generated from an LNG tank storing LNG and recovering the reliquefied liquefied BOG in the LNG tank, wherein BOG in the LNG tank is discharged. A BOG delivery line for sending out the BOG, a cooling device connected to the BOG delivery line for cooling and reliquefying the BOG, connected to the cooling device, and connected to an external pipe for A liquefied BOG tank for storing reliquefied liquefied BOG, a pressure increasing device for increasing the internal pressure of the liquefied BOG tank, the LNG in the liquefied BOG tank and the LNG tank,
The liquefied BOG is connected to an external pipe for receiving
A liquefied BOG transfer line for transferring the liquefied BOG stored in the liquefied BOG tank to the LNG tank by increasing the internal pressure of the liquefied BOG tank. LNG tank BOG reliquefaction recovery system characterized by: 2. The LNG tank BOG according to claim 1.
A reliquefaction recovery system, wherein the booster is a booster line that is connected to a lower part and an upper part of the liquefied BOG tank and vaporizes and pressurizes the liquefied BOG sent from the lower part of the liquefied BOG tank. Let L
NG tank BOG reliquefaction recovery system. 3. The LNG tank reliquefaction recovery system according to claim 2, wherein the first valve is provided on the BOG delivery line, and the second valve is provided on the liquefaction BOG transfer line. A third valve provided on the boosting line, and when the liquefied BOG is stored, the first valve is opened with the second valve and the third valve closed, and the liquefied BOG is stored. The LNG tank BOG reliquefaction recovery system, wherein the second valve and the third valve are opened while the first valve is closed when the LNG tank is transferred. 4. The LNG tank BOG reliquefaction recovery system according to claim 1, wherein the LNG tank BOG reliquefaction recovery system detects a liquid amount of the liquefied BOG stored in the liquefied BOG tank. LN having a device
G tank BOG reliquefaction recovery system. 5. The LNG tank BOG reliquefaction recovery system according to any one of claims 1 to 4, wherein the liquefied BO is detected based on a detection result of the liquid amount detection device.
An LNG tank BOG reliquefaction recovery system having an automatic switching control device for switching between G storage and transfer.