JPS621492A - Method for supplying extremely low temperature medium - Google Patents

Abstract

PURPOSE:To contrive to simplify an apparatus, by flashing an extremely low temp. medium to once storing the same and subsequently injecting said medium in the liquid phase of a liquid to be cooled while supplying the gas obtained by flashing along the circumference of the extremely low temp. medium jet stream. CONSTITUTION:LNG supplied through a LNG supply base pipe 38 is flashed by a throttle 37 and once stored in a flash tank 36. LNG stored in the flash tank 36 passes through a valve 35 and subsequently injected toward sea water 3 in a crystallization boiler 1 from a nozzle orifice 28A through the passing hole 27 of a nozzle 28. NG formed in the gaseous phase of the flash tank 36 enters a natural gas supply port 26 while the amount thereof is adjusted by the throttle 40 of a natural gas supply pipe 39 to be injected in the sea water 3 of the crystallization boiler 3 as a jet stream. The natural gas flowing out from a jet orifice 25 is injected along the circumference of the LNG jet stream ejected from the nozzle orifice 28A.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for supplying a cryogenic medium, such as when supplying cryogenic LNG (liquefied natural gas) to seawater for the purpose of seawater desalination. Available.

[Background Art and Problems Therein] LNG is imported at extremely low temperatures (-161, 5°C) and is used after being vaporized by heat exchange with seawater.

As a technology that utilizes the cold energy of LNG, so-called seawater desalination technology is known, which uses the heat of vaporization of LNG to crystallize ice in seawater, and then separates, washes, and melts the ice from seawater to produce fresh water. Among these seawater desalination technologies, there are two methods for directly exchanging heat between LNG and seawater: a method in which LNG is sprayed from the gas phase in a crystal canister containing seawater, that is, from above the seawater surface; Directly into the phase, that is, directly into seawater
There are two main types of methods: G injection.

In the latter method, a nozzle is attached to the bottom of a crystallization can into which seawater has been injected, and LNG is spouted into the seawater through this nozzle, and the seawater in the crystallization can is cooled and crystallized by INNG, forming fine ice crystal grains. After forming a floating slurry, this is washed and transferred to a melting tank. However, when LNG is directly injected into seawater, interface blocks (
There is a problem where ice blocks) occur.

Therefore, in order to prevent this, the blocking gas is ejected around the LNG jetting flow, and the blocking gas jetting flow is spouted into the seawater while surrounding the LNG jetting flow.

Such equipment requires a shutoff gas to prevent direct contact between LNG and seawater, and conventionally, a vaporizer, a blower, etc. have been required to obtain this shutoff gas.

[Object of the Invention] An object of the present invention is to provide a cryogenic medium supply method that does not require the above-mentioned equipment for obtaining the cutoff gas and that simplifies the apparatus.

[Means and actions to destroy the problem] Therefore,
In the present invention, it has been discovered that the amount of the shutoff gas can be within about 5% of the cryogenic medium ejected into the liquid to be cooled, and the shutoff gas is obtained by flashing the cryogenic medium.

Specifically, when the cryogenic medium is ejected into the liquid phase of the liquid to be cooled, the cryogenic medium is flashed and stored once, and then ejected into the liquid phase of the liquid to be cooled, while the liquid obtained by the flash is The above objective is achieved by supplying the collected gas along the periphery of the cryogenic medium jet.

[Example] Fig. 1 shows an example in which the method according to the present invention is applied to a crystal canister of a seawater desalination apparatus using LNG cold energy. In the figure, seawater 3 is injected into the crystal canister l through a seawater injection pipe 2, and a gas phase communication pipe 4 is installed on the wall of the gas phase section.
Slurry outlet pipes 5 are connected to the walls of the liquid phase portion, respectively. Further, a nozzle device 2'l is attached to the bottom of the crystal can 1.

As shown in FIG. 2, the nozzle device 21 includes a cylindrical nozzle attachment tube 22 attached to the bottom of the crystal can 1 and communicating between the inside and outside of the can. An outlet plate 23 is fitted onto the end surface of the nozzle mounting tube 22 on the inside of the can, and is fitted concentrically with the axis of the nozzle mounting tube 22, and is removably attached to the end surface of the can with a plurality of setscrews. A support flange 24 is integrally formed on the end face of. At the center of the outlet plate 23, there is formed a tapered spout 25 whose diameter gradually decreases toward the inside of the can.

Furthermore, a natural gas supply port 26 for introducing natural gas as a shutoff gas is formed on the side surface of the nozzle mounting pipe 22, and LNG as a cryogenic medium is formed in the center of the nozzle mounting pipe 22 in the direction of the central axis. A nozzle 28 having a flow hole 27 is housed therein. The nozzle 28 is provided with a plurality of (eight in this example) natural gas flow holes 29 at a position slightly below the nozzle port 28A at its tip, that is, on the outer periphery between the outlet plate 23 and the natural gas supply port 26. Flanges 30 arranged at intervals are integrally formed, and a flange 31 is integrally formed at the outer end of the can. The flange 31 is connected to the support flange 24 and the support flange 2.
4 and a fixed 7 flange 33 attached via a plurality of bolts 32.

One end of an LNG supply pipe 34 communicating with the flow hole 27 of the nozzle 28 is connected to the center of the fixed flange 33 . The LNG supply pipe 34 is provided with a valve 35 in the middle, and the other end communicates with the bottom surface of the flash tank 36. An LNG supply base pipe 38 having a throttle 37 in the middle is connected to the flash tank 36, and a natural gas supply pipe 3 connected to the natural gas supply port 26 is connected to the upper surface of the flash tank 36.
9 are connected. In the middle of the natural gas supply pipe 39,
A throttle 40 and a valve 41 are inserted.

Next, the operation of this embodiment will be explained. LNG supply main pipe 38
The LNG supplied through the tank is flashed through a throttle 37 and temporarily stored in a flash tank 36. The LNG stored in the flash tank 36 passes through the valve 35 of the LNG supply pipe 34, passes through the flow hole 27 of the nozzle 28, and is ejected from the nozzle port 28A into the seawater 3 in the crystal can 1.

On the other hand, NG generated in the gas phase of the flash tank 36
enters the natural gas supply port 26 through the valve 41 while the gas amount is adjusted by the throttle 40 of the natural gas supply pipe 39;
The spout 2 passes through the natural gas distribution hole 29 provided in the collar 30.
5 becomes a jet that gains momentum and is ejected into the seawater 3 of the crystal can 1.

At this time, the natural gas flowing out from the nozzle 25
Since the LNG jet is ejected along the periphery of the LNG jet coming out from the nozzle port 28A of the nozzle 28, direct contact between LNG and seawater can be blocked, and the occurrence of boundary blocks near the nozzle port 28A of the nozzle 28 can be prevented. .

Therefore, according to the present embodiment, in spouting LNG into the seawater 3, the LNG is flashed and stored in the flash tank 36, and then spouted into the seawater 3.
Since the natural gas generated in the flash tank 36 by the flash is spouted out along the periphery of the LNG jet stream, the blower that is conventionally required for shutoff gas is removed.
It is possible to eliminate the need for a vaporizer or a vaporizer. Incidentally, this configuration was possible because it was found through experiments that the amount of natural gas needed to be within 5% of the amount of LNG supplied.

In addition, since the collar 30 supports the nozzle 28 in close contact with the inner wall of the nozzle mounting pipe 22, the centering of the nozzle tip is always maintained reliably, which allows the natural gas heat flowing from the natural gas supply pipe 39 to It is possible to prevent bending deformation of the nozzle due to uneven contact of the nozzle, and vibration of the nozzle due to high-speed jet flow and gas bubbles near the spout 25. Moreover, the natural gas flow velocity is equalized over the entire circumference of the spout 25 by the natural gas distribution hole 29 provided in the collar 30,
Even if the amount of inflow from the natural gas supply pipe 39 increases, it is difficult to drift, and as a result, the above-mentioned effect on the LNG jet from the nozzle port 28A can be maintained well.

In addition, although the above embodiment describes the case where it is applied to seawater desalination technology using LNG cold energy, the present invention is applicable not only to the above case but also to an LNG vaporization device to reduce the size of the device. Further, the present invention can be applied even when a cryogenic medium other than LNG is supplied to a liquid to be cooled other than seawater.

Further, the position where the nozzle device 21 is attached is not limited to the bottom of the crystal can 1 described in the above embodiment, but may be any wall located in the liquid phase.

In addition, the flash tank 36 is flushed with LNG.
The means for storing the water in the water is not limited to the throttle 37 described in the above embodiment, but may be, for example, a valve or the like.

[Effects of the Invention] As described above, according to the present invention, LNG is once flushed, and the natural gas generated by this flashing is
Since the NG gas is supplied along the circumference of the NG jet stream, it is possible to eliminate the need for blowers, vaporizers, etc. that were conventionally required to obtain the shutoff gas, and the fruiting device can be made smaller and less expensive. can contribute to

[Brief Description of the Drawings] The figures show an example in which the method of the present invention is applied to a crystal canister for seawater desalination.
The figure is a sectional view showing the nozzle device. l...crystal can, 3...seawater, 35...bulb, 3
6...Flash tank, 37.40...Aperture.

Claims (1)

[Claims] (1) When ejecting the cryogenic medium into the liquid phase of the liquid to be cooled, the cryogenic medium is flashed and stored once, and then ejected into the liquid phase of the liquid to be cooled. A method for supplying a cryogenic medium, comprising supplying gas along the periphery of a cryogenic medium jet stream.