JPS6065997A - Device for reliquefying liquefied gas - Google Patents

Abstract

PURPOSE:To prevent the pressure of a liquefied gas reservoir from being boosted up, by disposing a device for boosting liquefied gas and an absorbing device for selectively absorbing impure component gas which has not been reliquefied in a reliquefying device, upstream of the reliquefying device. CONSTITUTION:Gas evaporated from LNG is introduced into an absorbing device 10 while it is maintained at a low temperature, and an absorbent for selectively absorbing thereinto nitrogen gas is disposed in the absorbing device 10. With this arrangement, only nitrogen gas in evaporated gas is absorbed in the absorbing device, and the remaining evaporated gas may be discharged from the absorbing device 10. The evaporated gas from the absorbing device 10 flows into a compressor 4 after cooling return gas through a het-exchanger 11, then is boosted up to a pressure necessary for circulation and cooled down in the heat- exchanger 11. The evaporated gas is then liquefied in a reliquefying device 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquefied gas reliquefaction device, and more particularly to a liquefied gas reliquefaction device that prevents pressure increase in a liquefied gas storage container.

FIG. 1 shows an example of a conventional liquefied gas reliquefaction device.
It is a conceptual diagram of an LNG reliquefaction device.

At LNG ground bases or I, N () tankers, etc.
Although the LMG 2 is stored in the heat insulating container 1, a portion of the LMG 2 evaporates (vaporizes) due to external heat input, and the pressure in the gas space 7 increases. In order to suppress this pressure increase within a certain limit, the vaporized gas is taken out of the container 1 through a pipe 3, heated with a heater 9, and then raised to sufficient circulation pressure with a compressor or fan 4, and then re-circulated. It is re-liquefied by a liquefier 5 and returned to the container 1 through a pipe line 6.

However, as a practical problem, LNG mainly contains nitrogen gas (GNs) as an impurity component, and because this nitrogen gas has a lower boiling point than LNG, it vaporizes relatively faster than LNG, making it difficult to reliquefy. LNG does not liquefy at the same temperature as when it liquefies. Therefore, in the conventional apparatus as shown in FIG. 1, nitrogen gas components gradually increase in the reliquefaction circulation systems 3 to 6 and the gas space 7, and if this continues, it becomes impossible to prevent the internal pressure from increasing. Therefore, the vaporized gas has to be appropriately dumped out of the system using the relief valve 8.

The present invention was made in order to eliminate the above-mentioned drawbacks, and its purpose is to prevent pressure increase in a liquefied gas storage container.

The above object is to provide a piping system in which vaporized gas led out from a liquefied gas storage container passes through a pressure booster and a reliquefaction device to increase the pressure, reliquefy it, and return it to the liquefied gas storage container, upstream of the reliquefaction device. This can be achieved by a liquefied gas reliquefaction device characterized in that an adsorption device for selectively adsorbing impurity component gases that are not reliquefied by the pressure booster and reliquefaction device in the liquefied gas is inserted.

The device of the present invention described above avoids releasing the vaporized gas of the stored liquefied gas and the vaporized gas of the impure components mixed therein as a mixture, and selectively releases only the vaporized gas of the impure components to the outside of the system. This book is unique in that an adsorption device filled with an adsorbent that selectively adsorbs vaporized gases of impurity components is added to the reliquefaction system to make it possible.

FIG. 2 is a conceptual diagram of an embodiment of the apparatus of the present invention.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts as in FIG.

The vaporized LNG gas is introduced into the adsorption device 10 at a low temperature. Since the adsorption device 10 is filled with an adsorbent (for example, Molecular Sheeps (trade name)) that selectively adsorbs nitrogen gas, only the nitrogen gas in the vaporized gas is adsorbed and leaves the adsorption device 10. Become.

The vaporized gas leaving the adsorption device 10 cools the return gas in the heat exchanger 11 (that is, is heated by the return gas), and then passes through the compressor 4.
The water enters the system, is pressurized to the pressure required for circulation, is cooled in the heat exchanger 11, and is further liquefied in the reliquefaction machine 5. At this time,
Since the nitrogen component in the vaporized gas is very low,
Most of it is reliquefied. The reliquefied gas and the remaining gas are returned to the container 1 via line 6.

Since the nitrogen gas in the system is removed by the adsorption device 10 in this way, the increase in the nitrogen gas component that causes the pressure increase in the gas space 7 is eliminated, and as in the case of FIG. Pressure increase phenomenon can be prevented.

Note that when the adsorbent in the adsorption device 10 becomes saturated, after closing the valve 12, the adsorbent is regenerated by heating or reducing the pressure by means not shown. The nitrogen gas released in step (B) is discharged out of the system by opening the valve 13. Or adsorption device 1
It is also possible to provide two or more zeros in parallel and operate continuously while switching between use and regeneration.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional liquefied gas reliquefaction device, and FIG. 2 is a diagram showing an embodiment of the device of the present invention. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] In a piping system in which the vaporized gas led out from the liquefied gas storage container passes through a pressure booster and a reliquefaction device to increase the pressure, reliquefy it, and return it to the liquefied gas storage container, upstream of the reliquefaction device, there is a pipe in the liquefied gas. A reliquefaction device for liquefied gas, characterized in that an adsorption device for selectively adsorbing impurity gases that are not reliquefied in the pressure booster and the reliquefaction device is inserted.