JP2003090497A - Gas pressure type lng transfer 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 type transfer of LNG without using an LNG pump although there are problems that conventionally an electric LNG pump is put in LNG liquid, and the LNG or the like is boosted and is transferred in order to transfer the low temperature liquefied gas such as the LNG in a large size low pressure type storage tank, however labor and cost are required for maintenance management such as constant monitoring of abnormal vibration and failure diagnosis in installing the electric LNG pump, and also the LNG in the pump is vaporized and causes trouble in operation. SOLUTION: A pressurized tank 2, which is connected by a pressurizing discharge pipe 5, and a pressurizing and depressurizing pipe 34 and is provided with a submerged valve 21, is provided in an inside 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 pressurized tank 2 is pressurized and the LNG is discharged. The transfer of the LNG is 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 an apparatus for pressurizing a low-temperature liquefied gas such as liquefied natural gas (hereinafter referred to as LNG) and transferring it from a storage tank or the like. . 2. Description of the Related Art Conventionally, in order to transfer LNG in a large-sized low-pressure storage tank, an electric LNG pump is charged into the LNG liquid, and LNG or the like is pressurized and transferred. [0003] However, the electric LNG
In the installation of the pump, not only maintenance and management are required, such as constantly monitoring abnormal vibrations and performing fault diagnosis, but also there is a problem that LNG in the pump is vaporized and hinders operation. An object of the present invention is to realize a pressurized LNG transfer method without using an LNG pump in a large low-pressure LNG storage tank. [0004] In order to solve the above-mentioned problems, the present invention provides a submerged valve 21 which is opened and closed by a submerged valve driving device 22 in an LNG storage tank 1, a pressurized discharge pipe 5, and a pump. Pressure reducing tube 3
4 is installed, and L is controlled by a submerged valve 21.
The LNG 11 in the NG storage tank 1 is allowed to flow into the pressure tank 2, and the pressure in the pressure tank 2 is increased by the pressurizing and depressurizing pipe 34.
G is paid out. [0005] The pressure reducing valve 61 is opened to reduce the pressure in the pressure tank 2, the submerged valve 21 is opened and the LNG 1
After the submerged valve 1 and the pressure reducing valve 61 are closed, the pressurizing valve 33 is opened to pressurize the inside of the pressure tank 2. Subsequently, the discharge valve 51 is opened to discharge LNG in the pressure tank 2. The LNG pressurized in the pressure tank 2 is discharged from the pressurized discharge pipe 5 to the discharge tank 7. Further, after the LNG in the pressure tank 2 is discharged, the pressure in the pressure tank 2 is reduced by the same procedure, the LNG 11 flows into the pressure tank 2 from the LNG storage tank 1 again, and the pressure in the pressure tank 2 is further increased to discharge the LNG. . By repeating such an operation, the LNG 11 in the LNG storage tank 1 is transferred. Embodiments of the present invention will be described below with reference to the drawings. The LNG transfer device of the present invention, as shown in FIG.
The pressure tank 2 is installed in the LNG storage tank 1 and the pressure tank 2
A submerged valve 21 is provided at the lower part, and LNG 11 is provided in the pressure tank 2.
And a pressure reducing pipe 34 is connected so that the pressure in the pressure tank 2 can be reduced and reduced. Further, a pressure discharging pipe 5 is provided to discharge LNG in the pressure tank 2. The pressure reducing pipe 6 is provided with a pressure reducing valve 61.
By opening 1, the pressure in the pressure tank 2 is reduced, and by further opening the submerged valve 21, the LNG 11 in the LNG storage tank 1 flows into the pressure tank 2. [0008] The pressurizing pipe 35 is connected to the lower part of the dispensing tank 7,
An evaporation control valve 31, a pressure evaporator 32, and a pressure valve 33 are provided. The pressurizing pipe 35 is pressurized by the vaporized gas obtained by vaporizing LNG by the pressurized evaporator 32. By opening the pressurizing valve 33, the vaporized gas flows into the pressure tank 2 and pressurizes the pressure tank 2. A discharge valve 51 is provided in the pressurized discharge pipe 5, and the pressure L in the pressure tank 2 is increased by opening the discharge valve 51.
NG is dispensed to the dispensing tank 7. Next, an example of use of the gas pressure type LNG transfer device of the present invention will be described in detail. L provided in LNG storage tank 1
The NG receiving pipe 4 receives the LNG 11. Further, the opening of the pressure control valve 31 is adjusted so that the pressure in the pressure pipe 35 becomes constant. LN flowing into pressurized evaporator 32
G evaporates and expands to increase the pressure in the pressure tube 35. Two dispensing tanks 7 are provided. One dispensing tank 7 receives the LNG 11 in the LNG storage tank 1, and the other dispensing tank 7 dispenses LNG to the vaporizer 73. The two discharge tanks 7 alternately receive the LNG from the LNG storage tank 1 and discharge the LNG to the vaporizer 73. In the discharge tank 7 receiving LNG from the LNG storage tank 1, the BOG discharge valve 92 is opened,
The BOG compressor 91 is operated to reduce the pressure in the discharge tank 7 to a constant pressure. Also, LN is sent to the other vaporizer 73.
In the dispensing tank 7 that dispenses G, the dispensing tank pressurizing valve 81 is opened to pressurize the dispensing tank 7. In the above state, first, the pressure reducing valve 61 is opened to lower the pressure in the pressure tank 2 to the same or less than the pressure in the LNG storage tank 1. Subsequently, the submerged valve 21 is opened and LN
Due to the pressure difference between the G storage tank 1 and the pressure tank 2, the LNG storage tank 1
LNG 11 in the tank is caused to flow into the pressure tank 2. In addition,
The decompression pipe 6 may be connected to the upper part of the LNG storage tank 1 so that the gas at the time of decompression can be collected in the LNG storage tank 1. With the pressure tank 2 filled with LNG, the submerged valve 21 and the pressure reducing valve 61 are closed. continue,
The pressure valve 33 is opened to increase the pressure in the pressure tank 2. In this state, the discharge valve 51 connected to the discharge tank 7 receiving LNG is opened, and the LNG in the pressure tank 2 is sent out to the discharge tank 7 receiving LNG. After the LNG in the pressure tank 2 is discharged, the pressure valve 33 and the discharge valve 51 are closed, and the pressure reducing valve 61 is discharged.
Is opened, and the pressure in the pressure tank 2 is reduced. Subsequently, the submerged valve 2
1, the LNG 11 in the LNG storage tank 1 is allowed to flow into the pressure tank 2 again. Further, the pressure in the pressure tank 2 is increased, and L
NG is dispensed from the pressure dispensing pipe 5. By repeating the above operation, the LNG 11 in the LNG storage tank 1 is transferred to the discharge tank 7. In the other discharging tank 7, the discharging tank pressurizing valve 81 is opened to pressurize the discharging tank 7, and the vaporizing discharging valve 75 is further opened to send the LNG in the discharging tank 7 to the vaporizing device 73. The LNG sent to the vaporizer 73 is vaporized by external heat and sent to the vaporized gas pipe 74. After the dispensing of LNG from the dispensing tank 7, the dispensing valve 51 and the vaporizing dispensing valve 75 are closed, and the BOG is discharged.
The discharge valve 92 is opened, the BOG compressor 91 is operated, and the pressure in the discharge tank 7 is reduced. After the pressure in the dispensing tank 7 decreases, the LNG 11 in the LNG storage tank 1 is transferred to the dispensing tank 7 by the above-described procedure. According to the present invention, as described above, the pressure tank 2 for pressurizing is provided inside the large LNG storage tank, and the LNG
Pressure can be increased and decreased by opening and closing the valve, the use of an expensive LNG pump having a complicated structure can be avoided, and there is no need to constantly monitor abnormal vibrations and perform failure diagnosis. There is an advantage that LNG does not vaporize and hinder driving.

[Brief description of the drawings] FIG. 1 is an explanatory diagram of the present invention. [Explanation of symbols] 1 LNG storage tank 2 Pressure tank 21 Submerged valve 33 Pressure valve 51 Dispensing valve 61 Pressure reducing valve

Claims (1)

Claims: 1. A pressure tank 2 installed in an LNG storage tank 1.
By depressurizing the inside, low temperature liquefied gas such as LNG
A device that flows in from the NG storage tank 1, discharges the pressurized low-temperature liquefied gas by pressurizing the pressure tank 2, and transfers the low-temperature liquefied gas by repeating depressurization and pressurization in the pressure tank 2. .