JP2003090496A - Lng pressurizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large size storage tank of low temperature liquefied gas such as LNG capable of performing pressurization and transferring without using an LNG pump although a low pressure type storage tank of the low temperature liquefied gas such as the LNG required the LNG pump installed for LNG transfer, and has a problem that the LNG in the LNG pump is vaporized and causes trouble in operation, and furthermore, a pressurization type storage tank requires an increase of a thickness of a storage tank main body in order to increase a pressurizing pressure. SOLUTION: A pressurized tank 2 which is connected by an LNG storage tank 1, an LNG discharge pipe 5, and a depressurizing pipe 6 is provided in a periphery of a lower part of the LNG storage tank 1. An inside of the pressurized tank 2 is depressurized and the LNG is allowed to flow in from the LNG storage tank 1, and the inside of the pressurized tank 2 is pressurized and the LNG is discharged. The pressurization and transferring of the LNG are performed by repeating pressurization and depressurization of the inside of the pressurized tank 2.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure increasing device for pressurizing a low-temperature liquefied gas such as liquefied natural gas (hereinafter referred to as LNG) and transferring it from a storage tank. It is. 2. Description of the Related Art Conventionally, in order to transfer LNG in a storage tank, in the case of a low-pressure storage tank, an LNG pump is put into an LNG liquid to pressurize and transfer LNG. In the case of a pressurized storage tank, the entire storage tank is pressurized to transfer LNG. [0003] However, in a low-pressure storage tank, an LNG pump must be installed for LNG transfer. In the installation of the LNG pump, abnormal vibration is constantly monitored to diagnose a failure. In addition to the labor and expense required for maintenance, such as the operation, there is a problem that LNG in the pump is vaporized and hinders operation. Also, in the pressurized storage tank, if the pressure is to be increased, the wall pressure of the storage tank body must be increased, and it is difficult to increase the size. The present invention is intended to realize a pressurized LNG boosting method in a large LNG storage tank. [0004] In order to solve the above-mentioned problems, the present invention provides a pressurized tank connected to an LNG storage tank 1 near the lower part of the LNG storage tank 1 by an LNG discharge pipe 5 and a pressure reducing pipe 6. 2, the pressurized tank 2 is provided with a pressurized pipe 34 so that the pressure in the pressurized tank 2 can be increased, and LNG is discharged through the pressurized discharge pipe 7. [0005] The pressure reducing valve 61 is opened to reduce the pressure in the pressurized tank 2, the discharge valve 51 is opened and the LNG 11 is placed in the pressurized tank 2.
After the discharge valve 51 and the pressure reducing valve 61 are closed, the pressurizing valve 31 and the pressure adjusting valve 33 are opened, and the pressurizing tank 2 is pressurized. The LNG pressurized in the pressurized tank 2 is discharged from the pressurized discharge pipe 7. After the LNG in the pressurized tank 2 is further discharged, the pressurized valve 31 and the pressurized adjusting valve 33 are closed, the pressure in the pressurized tank 2 is reduced by the same procedure, and the LNG is again discharged from the LNG storage tank 1 into the pressurized tank 2. And pressurizes the inside of the pressurizing tank 2 to discharge LNG.
By repeating such an operation, the pressure of the LNG 11 in the LNG storage tank 1 is increased and transferred. Embodiments of the present invention will be described below with reference to the drawings. The LNG booster of the present invention, as shown in FIG.
The LNG storage tank 1 is provided with a pressurized tank 2 connected by an LNG discharge pipe 5 and a decompressing pipe 6.
And pressurizing the pressurized tank 2, and further, a pressurized discharging pipe 7 is provided so that LNG in the pressurized tank 2 can be discharged. The LNG discharging pipe 5 is provided with a discharging valve 51, the pressure reducing pipe 6 is provided with a pressure reducing valve 61, the pressure in the pressurized tank 2 is reduced by opening the pressure reducing valve 61, and the discharge valve 51 is further opened. The LNG 11 in the LNG storage tank 1 flows into the pressurized tank 2. The pressurizing valve 34, the pressurizing evaporator 3
2. A pressure control valve 33 is provided. By opening the pressure valve 31, LNG in the pressure tank 2 is sent to the pressure evaporator 32. The LNG sent to the pressurized evaporator 32 is vaporized and expanded by external heat. Further, the pressure in the pressurized tank 2 is made constant by opening the pressurized control valve 33 and adjusting the opening. A discharge control valve 71 is provided on the pressurized discharge pipe 7,
The LNG pressurized in the force tank 2 is discharged by opening the discharge control valve 71. Next, an example of use of the LNG booster of the present invention will be described in detail. LNG 11 is received by the LNG receiving pipe 4 provided in the LNG storage tank 1. Also, LNG
The storage tank 1 is provided with a BOG discharge pipe 8, and the BOG discharge pipe 8 is provided with a BOG heater 82 and a BOG compressor 81.
By operating the G compressor 81, the boil-off gas generated in the LNG storage tank 1 is discharged, and the pressure in the LNG storage tank 1 is kept constant. In the above state, first, the pressure reducing valve 61 is opened to make the pressure in the pressurizing tank 2 the same as that of the LNG storage tank 1.
Subsequently, the discharge valve 51 is opened, and the LNG level in the LNG storage tank 1 is changed due to the liquid level pressure difference between the LNG storage tank 1 and the LNG in the pressurized tank 2.
G11 flows into the pressurized tank 2. In addition, the pressure reducing pipe 6
May be connected to another low-pressure line without connecting to the LNG storage tank 1 to reduce the pressure. When the pressurized tank 2 is filled with LNG, the discharge valve 51 and the pressure reducing valve 61 are closed. continue,
The pressurizing valve 31 and the pressurizing control valve 33 are opened, and the pressurizing tank 2
Increase pressure inside. In this state, the payout control valve 71 is opened,
The LNG in the pressurized tank 2 is sent to the vaporizer 72. L
The NG is vaporized by the external heat in the vaporizer 72, becomes a vaporized gas, and is sent out through the vaporized gas discharge pipe 9. Note that L
The NG may not be sent directly from the pressurized tank 2 to the vaporizer 72, but may be temporarily stored in a discharge tank or the like. After the LNG in the pressurized tank 2 is discharged, the pressurizing valve 31, the pressurizing control valve 33, and the discharging control valve 71
Is closed, the pressure reducing valve 61 is opened, and the pressure in the pressurized tank 2 is reduced. The dispensing valve 51 is opened to allow the LNG 11 in the LNG storage tank 1 to flow into the pressurized tank 2 again. By repeating the above operation, the pressure of the LNG 11 in the LNG storage tank 1 is increased,
Pay out further. As shown in FIG.
Two systems of NG boosters may be provided, and pressurization and depressurization may be alternately repeated to increase and discharge LNG. This makes it possible to continuously pay out LNG. According to the present invention, as described above, the pressurized tank 2 is provided outside the large LNG storage tank, and it is not necessary to pressurize the entire LNG storage tank in order to pay out the LNG 11. The body pressure of the storage tank body of storage tank 1 can be reduced, and LN
There is an advantage that the size of the G storage tank can be increased. Also,
It is possible to raise and discharge LNG by opening and closing the valve, avoid the use of an expensive LNG pump having a complicated structure, eliminate the need to constantly monitor abnormal vibrations and perform failure diagnosis, There is an advantage that the LNG does not vaporize and hinder driving.

[Brief description of the drawings] FIG. 1 is an explanatory diagram of the present invention. FIG. 2 is an explanatory diagram of an embodiment. [Explanation of symbols] 1 LNG storage tank 11 LNG 2 Pressurized tank 31 Pressure valve 33 Pressure control valve 51 Dispensing valve 61 Pressure reducing valve 71 Dispensing control valve

Claims (1)

Claims: 1. The pressure in a pressurized tank 2 is reduced to reduce
A low-temperature liquefied gas such as NG is caused to flow from the LNG storage tank 1, and the LNG is discharged in a state where the LNG is pressurized by pressurizing the pressurized tank 2. A pressurizing device that pressurizes and discharges liquefied gas.