JP2003232499A - Method and device for subcooling low-temperature liquefied gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture low-temperature subcooled liquefied gas used in a performance test of equipment for treating low-temperature liquefied gas, at a low cost. <P>SOLUTION: A gas ejector 9 is connected through a vaporized gas exhaust line 5 to a low-temperature storage tank 4 for receiving and storing the low- temperature liquefied gas 3. The gas ejector 9 is supplied with dry air or driving gas 8 compressing the vaporized gas of liquefied gas not containing moisture, and the vaporized gas 3a in the low-temperature storage tank 4 is exhausted to decompress the interior of the low-temperature storage tank 4. A part of the low-temperature liquefied gas 3 is evaporated to subcool the low-temperature liquefied gas 3 with heat of vaporization. Agitating gas 16 is blown in to agitate the low-temperature liquefied gas 3 in the low-temperature storage tank 4 to uniformize the temperature of delivered low-temperature subcooled liquefied gas 3b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to LN ₂ , LO ₂ , and L.
The present invention relates to a low-temperature liquefied gas supercooling method and device for producing a low-temperature supercooled liquefied gas used in a test device for confirming the performance of a device or a device that handles low-temperature liquefied gas such as H ₂ .

[0002]

2. Description of the Related Art When conducting a test for confirming the performance of a device or equipment handling low-temperature liquefied gas, it is necessary to have a low-temperature supercooled liquefied gas cooled to a temperature lower than the intended temperature of the low-temperature liquefied gas. Become. As one method for producing such a low-temperature supercooled liquefied gas, for example, the vaporized gas in the low-temperature storage tank storing the low-temperature liquefied gas is discharged by a mechanical vacuum pump to reduce the pressure in the tank, There is a method of evaporating the low-temperature liquefied gas from the surface by the action and lowering the temperature of the low-temperature liquefied gas by the latent heat of vaporization to obtain the low-temperature supercooled liquefied gas.

[0003]

However, -100 ° C
In the case of a vacuum pump capable of sucking and discharging the following low-temperature vaporized gas, it has a special specification and is very expensive. In the case of the low temperature supercooled liquefied gas used for the test, the temperature is required to be uniform, but it is obtained by cooling by the latent heat of vaporization by simply lowering the pressure in the low temperature storage tank with a vacuum pump. The low-temperature supercooled liquefied gas has a temperature gradient in the low-temperature storage tank, and thus has a problem that it does not have a uniform temperature.

Therefore, the present invention makes it possible to supercool the low-temperature liquefied gas without using an expensive special vacuum pump, and to send the produced low-temperature supercooled liquefied gas at a uniform temperature. An object of the present invention is to provide a method and an apparatus for supercooling a low temperature liquefied gas that can be used.

[0005]

In order to solve the above problems, the present invention decompresses the inside of a low temperature storage tank storing low temperature liquefied gas by a gas ejector to evaporate a part of the low temperature liquefied gas. A method and apparatus for supercooling a low-temperature liquefied gas that supercools the low-temperature liquefied gas with latent heat.

When the vaporized gas in the low temperature storage tank is discharged by the gas ejector, the low temperature liquefied gas is vaporized by depressurizing the inside of the low temperature storage tank. Therefore, the low temperature liquefied gas is cooled by the latent heat of vaporization at that time. It can be a low temperature supercooled liquefied gas. At this time, since the gas ejector having no movable part is much cheaper than the vacuum pump of the special specification, the low temperature subcooled liquefied gas can be manufactured at a low cost.

Further, by using dry air or a vaporized gas of a liquefied gas that does not contain water as a driving gas for the gas ejector, the temperature of the gas ejector itself becomes low due to the vaporized gas of a low temperature. Also, it is possible to prevent freezing in the gas ejector, and to prevent clogging due to freezing.

Further, the low-temperature liquefied gas in the low-temperature storage tank is blown with a vaporized gas having the same composition as the low-temperature liquefied gas to stir the low-temperature liquefied gas, or the low-temperature liquefied gas in the low-temperature storage tank is mixed with the upper layer. By circulating it between the lower layer and the lower layer, the temperature of the supercooled liquefied gas in the low temperature storage tank can be made uniform.

Furthermore, by providing a plurality of gas ejector systems so that a plurality of gas ejectors can be switched and used, even if the gas ejector cannot be used, the gas of another system cannot be used. Operation can be continued using the ejector.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a low-temperature liquefied gas 3 such as LN ₂ supplied from a liquefied-gas lorry receiving facility 1 through a low-temperature liquefied gas supply line 2 is stored in a low-temperature storage tank 4. The vaporized gas discharge line 5 for discharging the vaporized gas 3a evaporated inside is connected to the top of the low temperature storage tank 4, and the vaporized gas discharge line 5 is driven through the driving gas supply line 7. Low temperature storage tank through the vaporized gas discharge line 5 by connecting to the intake port of the gas ejector 9 connected to the gas supply device 6 and supplying the drive gas 8 from the drive gas supply device 6 to the gas ejector 9. The low temperature storage tank 4 is decompressed by discharging the vaporized gas 3a in the low temperature liquefied gas 4 and the low temperature liquefied gas 3 is positively vaporized. The low temperature liquefied gas 3 in the tank 4 can be supercooled. In addition, the exhaust gas line 10 connected to the exhaust port of the gas ejector 9 is guided to the exhaust gas treatment device (flare stack) 11, and the supplied driving gas 8 and the vaporized gas 3a sucked from the low temperature storage tank 4 are mixed. Exhaust gas treatment device 11 for passing gas through exhaust gas line 10
So that the low temperature supercooled liquefied gas 3b produced by supercooling the low temperature liquefied gas 3 is sent to the low temperature storage tank 4 to the low temperature subcooled liquefied gas test apparatus 12 which is the destination. A low-temperature subcooled liquefied gas delivery line 13 is installed through the tank top so that the inlet end is open at the tank bottom. Further, a stirring gas supply line 14 having a plurality of nozzles 14a at the tip portion and connected to a stirring gas supply device 15 is inserted into the low temperature storage tank 4 from the top, and the nozzle 14 at the tip portion is inserted.
a is positioned in the low temperature liquefied gas 3 in the low temperature storage tank 4, and the stirring gas 16 supplied from the stirring gas supply device 15 is passed through the stirring gas supply line 14 and supplied from the nozzle 14a to the low temperature liquefied gas 3. By blowing in,
The low temperature liquefied gas 3 is agitated to obtain a uniform temperature.

The driving gas 8 to be supplied to the gas ejector 9 is dry air from which water has been removed, or
N ₂ gas is used as the vaporized gas of the liquefied gas that does not contain water. As the stirring gas 16 blown into the low-temperature liquefied gas 3, a vaporized gas having the same composition as the low-temperature liquefied gas 3, that is, in the present embodiment, the low-temperature liquefied gas 3 is LN ₂ , so N ₂ gas is used. Try to use it.

When the low-temperature supercooled liquefied gas 3b is sent to the low-temperature supercooled liquefied gas test device 12 to perform a performance test of equipment or the like, the low-temperature liquefied gas from the low-temperature liquefied gas tanker receiving facility 1 is previously stored in the low-temperature storage tank 4. The low-temperature liquefied gas 3 is supplied through the supply line 2 so that the planned amount of the low-temperature liquefied gas 3 is received in the low-temperature storage tank 4, and when the pressure in the low-temperature storage tank 4 stabilizes in this state, the gas ejector By driving the driving gas supply device 6 of 9 and supplying the driving gas 8 to the gas ejector 9 through the driving gas supply line 7, the vaporized gas 3a of the low temperature liquefied gas 3 in the low temperature storage tank 4 is vaporized. Suction is performed through the gas discharge line 5 so that the inside of the low temperature storage tank 4 is depressurized.

During the depressurization operation of the low temperature storage tank 4 as described above, the supply flow rate of the driving gas 8 to the gas ejector 9 is controlled so that the pressure of the low temperature storage tank 4 becomes constant.
The pressure in the low temperature storage tank 4 is controlled to a pressure corresponding to the target temperature of the low temperature subcooled liquefied gas 3b. Simultaneously with this control, the temperature of the low temperature liquefied gas 3 stored in the low temperature storage tank 4 is monitored and kept at a constant pressure for about 12 to 24 hours. At this time, the low-temperature liquefied gas 3 in the low-temperature storage tank 4 has a temperature distribution in the height direction as it is vaporized from the surface. Therefore, in order to minimize this temperature distribution, the stirring gas supply device is provided. The stirring gas 16 supplied from the stirring gas supply line 14 from 15 is blown into the low temperature liquefied gas 3 from the nozzle 14a at the tip, and the low temperature liquefied gas 3 is stirred by the bubbling action by the blowing.

As a result, the temperature of the low temperature liquefied gas 3 in the low temperature storage tank 4 is reduced to a temperature near the temperature equilibrium with the pressure and becomes the low temperature subcooled liquefied gas 3b which is supercooled under atmospheric pressure. Therefore, by sending the low-temperature supercooled liquefied gas 3b to the low-temperature supercooled liquefied gas test device 12 through the low-temperature supercooled liquefied gas delivery line 13, it is possible to carry out a target performance test.

In the above, the gas ejector 9 having no moving parts used as a pressure reducing device in the low temperature storage tank 4.
Is widely used in the chemical plant industry and the like, and is inexpensive, so that the low-temperature subcooled liquefied gas 3b can be manufactured at a low cost as compared with the case of using a special-purpose vacuum pump. . Further, as the driving gas 8 for the gas ejector 9, since dry air without moisture or N ₂ gas without moisture is used, the temperature of the gas ejector 9 itself is reduced by the sucked low-temperature vaporized gas 3a. Even if the temperature decreases, it is possible to eliminate the risk of causing freezing and clogging due to freezing. Furthermore, the cold storage tank 4
Even if the inside pressure is simply reduced, the temperature of only the surface of the stored low-temperature liquefied gas 3 decreases and the temperature of the lower layer does not change much, but the stirring gas 16 is blown into the tank to stir it. The internal temperature can be made uniform. At this time, since the vaporized gas having the same composition as the stored low temperature liquefied gas 3 is used as the stirring gas 16, there is no possibility that the composition of the produced low temperature subcooled liquefied gas 3b is altered. .

Next, FIG. 2 shows another embodiment of the present invention. In the same configuration as that shown in FIG. 1, the temperature of the low temperature liquefied gas 3 in the low temperature storage tank 4 is changed to a stirring gas. Instead of making it uniform by agitation by blowing 16 in, a suction port 18a on the upstream side of the circulation pump of a circulation line 18 equipped with a circulation pump 17 is connected to the bottom side of the low temperature storage tank 4. A discharge port 18b which is connected and is located on the downstream side of the circulation pump of the circulation line 18.
Is provided with a low temperature liquefied gas circulation device 19 which is connected to the top side of the low temperature storage tank 4 so as to communicate therewith.

A low temperature liquefied gas circulation device 1 as shown in FIG.
By using 9, the low temperature liquefied gas 3 stored in the low temperature storage tank 4 can be circulated by operating the circulation pump 17 so as to be sucked from the lower layer and returned to the surface layer (upper layer). Liquefied gas 3 can be mixed efficiently,
It is possible to make the temperature more uniform.

Next, FIG. 3 shows another embodiment of the present invention. In the embodiment shown in FIG. 1, in addition to the system of the gas ejector 9, a gas ejector 9 is separately provided.
The system a is provided so that the gas ejectors 9 and 9a can be switched and used. That is, a three-way switching valve 20 is provided in the middle of the driving gas supply line 7 from the driving gas supply device 6, another driving gas supply line 7a is branched and connected, and the driving gas supply line 7a is supplied through the driving gas supply line 7a. The exhaust gas line 10a of the gas ejector 9a that is driven by the driving gas 8 is guided to the exhaust gas treatment device 11, and in the middle of the vaporized gas discharge line 5 connected to the low temperature storage tank 4, the three-way switching valve 2
1 is provided to branch and connect another vaporized gas discharge line 5a,
The vaporized gas discharge line 5a is connected to the gas ejector 9a.
It is connected to the intake port of.

As shown in FIG. 3, when dry air is used as the driving gas 8 and the inside of the low temperature storage tank 4 is decompressed by using one gas ejector 9 or 9a, the dry air is removed from the dry air. When the gas ejector 9 or 9a is clogged because the water is not completely removed, the pressure can be reduced by using the other gas ejector 9a or 9 system by switching the three-way switching valves 20 and 21. Since the operation can be continued, the reliability of the entire device can be improved.

Although the embodiment of FIG. 3 shows the case where the gas ejector system has two systems, it may have three or more systems, and the case where it is applied to that shown in FIG. However, it goes without saying that it may be applied to the one shown in FIG. 2 and that various changes can be made without departing from the scope of the present invention.

[0022]

As described above, according to the method and apparatus for supercooling a low temperature liquefied gas of the present invention, the following excellent effects are exhibited. (1) A low-temperature storage tank that stores low-temperature liquefied gas is decompressed by a gas ejector to evaporate a part of the low-temperature liquefied gas and to supercool the low-temperature liquefied gas by its latent heat of vaporization. The low temperature supercooled liquefied gas can be produced at a lower cost than when using a pump. (2) As driving gas for the gas ejector, dry air,
Alternatively, by using the vaporized gas of liquefied gas that does not contain water, it is possible to prevent the occurrence of freezing and clogging accompanying it due to the temperature lowering of the gas ejector itself, and to perform stable decompression operation. it can. (3) In the low temperature liquefied gas in the low temperature storage tank, blow the vaporized gas of the same composition as the low temperature liquefied gas to stir the low temperature liquefied gas, or the low temperature liquefied gas in the low temperature storage tank as upper and lower layers. By circulating the liquefied gas between them, the temperature of the low temperature liquefied gas in the low temperature storage tank can be made uniform, and the low temperature subcooled liquefied gas having a uniform temperature can be sent out. (4) By providing multiple gas ejector systems so that multiple gas ejectors can be switched and used, even if one gas ejector cannot be used, another gas ejector can be used by switching. The reliability of the device can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a low-temperature liquefied gas supercooling device of the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the present invention.

FIG. 3 is a schematic diagram showing still another embodiment of the present invention.

[Explanation of symbols]

3 Low temperature liquefied gas 4 Cold storage tank 5,5a Vaporized gas discharge line 6 Drive gas supply device 8 driving gas 9,9a Gas ejector 16 Stirring gas (vaporized gas) 19 Low temperature liquefied gas circulation device

Claims (8)

[Claims] 1. A low-temperature storage tank that stores low-temperature liquefied gas is decompressed by a gas ejector to evaporate a part of the low-temperature liquefied gas, and the latent heat of vaporization supercools the low-temperature liquefied gas. Method for supercooling low temperature liquefied gas. 2. A gas for driving a gas ejector,
The supercooling method for low-temperature liquefied gas according to claim 1, wherein dry air or vaporized liquefied gas containing no water is used. 3. In the low temperature liquefied gas in the low temperature storage tank,
The method for supercooling a low-temperature liquefied gas according to claim 1 or 2, wherein a vaporized gas having the same composition as the low-temperature liquefied gas is blown to stir the low-temperature liquefied gas. 4. The supercooling method for low-temperature liquefied gas according to claim 1, wherein the low-temperature liquefied gas in the low-temperature storage tank is circulated between the upper layer and the lower layer. 5. A low temperature storage tank storing low temperature liquefied gas is connected to a vaporized gas discharge line, and a gas ejector connected to a driving gas supply device is connected to the vaporized gas discharge line, and the gas ejector is used. A supercooling device for a low temperature liquefied gas, characterized in that the inside of the low temperature storage tank is depressurized by sucking and discharging the vaporized gas in the low temperature storage tank to supercool the low temperature liquefied gas. 6. A stirring gas supply line for blowing a vaporized gas having the same composition as the low temperature liquefied gas stored in the low temperature storage tank into the low temperature liquefied gas as a stirring gas to stir the low temperature liquefied gas. The supercooling device for low temperature liquefied gas according to claim 5, which is installed in the low temperature liquefied gas in the low temperature storage tank. 7. A low-temperature liquefied gas circulating device for extracting low-temperature liquefied gas stored in a low-temperature storage tank from the lower part, returning it to the upper part in the low-temperature storage tank and circulating it between the upper layer and the lower layer is provided in the low-temperature storage tank. The subcooling device for the low temperature liquefied gas according to claim 5, which is provided. 8. A plurality of gas ejector systems are provided,
The supercooling device for a low temperature liquefied gas according to claim 5, 6 or 7, wherein a plurality of gas ejectors can be switched and used.