JPH08128596A - Gas evaporator and gas supplying method - Google Patents

Abstract

PURPOSE: To provide a gas evaporator and a gas supplying method which can immediately correspond to gas intermittent service as well as to improve thermal efficiency so that the extra energy consumption can be suppressed. CONSTITUTION: A gas evaporator is provided with a reservoir 11 which has double-wall structure formed by an inner wall 15 and an outer wall 16, and which is provided with an inlet 12 to supply liquefied gas thereto, an outlet 13 to send the vaporized gas outside the revervoir 11, and an inlet 18 and an outlet 19 to lead fluid for heating the liquefied gas to flow into/out from a clearance 17 between the inner wall 15 of the double-wall structure and the outer wall 16 thereof, and a means 21 to evacuate the clearance 17 between the inner wall 15 of the double-wall structure and the outer wall 16 thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas evaporator and a gas supply method. More specifically, the present invention relates to a gas evaporator and a gas supply method used to vaporize a gas that is liquefied and stored and supply the gas to a user (use equipment) at a desired pressure. The apparatus and method of the present invention comprises:
It is particularly suitable for use in the manufacture of semiconductors.

[0002]

2. Description of the Related Art Today, various gases are used in various industries. Of these gases, those that have a high boiling point and become liquid at room temperature are generally liquefied and supplied from the facilities of storage and transportation. For example, in semiconductor manufacturing processes, many liquefied gases such as dichlorosilanes, carbon tetrachloride, and tungsten hexafluoride are used.

In order to use such a liquefied gas after vaporizing it, conventionally, the liquefied gas cylinder / pipe is heated by an electric heater or a hot water heater to be vaporized, and the vaporized gas supply pipe is covered with a heat insulating material. Then, the method of keeping it warm has been taken. An electric heater is generally one in which an electric heating ribbon is wrapped around a pipe or a gas cylinder, and a hot water heater is used to heat a liquefied gas by supplying a hot water flow around the gas cylinder or pipe. It's being used.

[0004]

However, these vaporized gas generating methods are on / off controlled by electricity, hot water, etc. and have a small heat retaining effect, so that the thermal efficiency is low and a lot of energy is required. Further, in the case of combustible gas, directly heating the gas cylinder was very dangerous. Further, the hot water heater has a risk of water leakage or a problem that the reaction of leaked gas and water causes corrosion of pipes, cylinders and the like. In addition, the excessively vaporized gas may be reliquefied in the middle of the supply pipe to form a liquid pool in a part of the pipe system and block the pipe, thereby hindering normal gas supply.

In view of these problems, the present invention improves thermal efficiency and suppresses excessive energy consumption, and
It is an object of the present invention to provide a gas evaporation device and a gas supply method that can quickly respond to intermittent use of gas. It is also an object of the present invention to prevent the gas supply amount from being insufficient and the pressure from fluctuating due to the blockage of the pipe.

[0006]

A gas evaporation device of the present invention is a container having a double wall structure formed of an inner wall and an outer wall, and a liquefied gas for supplying the liquefied gas into the container. It has an inlet and a vaporized gas outlet for sending vaporized gas out of the container, and allows a fluid for heating the liquefied gas to flow in and out between the inner wall and the outer wall of the double wall structure. And a means for evacuating the gap between the inner wall and the outer wall of the double wall structure.

Further, according to the gas supply method of the present invention, the liquefied gas is put into a container having a double wall structure formed of an inner wall and an outer wall, and liquefied between the inner wall and the outer wall of the double wall structure. The liquefied gas in the container is heated by flowing the gas heating fluid, and when the liquefied gas reaches the specified temperature, the supply of the heating fluid is stopped and the space between the inner wall and the outer wall of the double wall structure is stopped. To keep the liquefied gas in the container warm, and if the temperature of the liquefied gas in the container drops, repeat the heating of the liquefied gas and the subsequent warming operation,
The gas vaporized in the container is supplied to the gas consuming facility (user).

The apparatus and method of the present invention will now be described with reference to FIG. As shown in this figure, the container 11 in the gas evaporator of the present invention comprises a liquefied gas inlet 12 and a vaporized gas outlet 13
Have. Liquefied gas is supplied to the container from a suitable liquefied gas reservoir such as a liquefied gas cylinder 24 through the liquefied gas inlet 12. The supply of the liquefied gas is stopped when the liquefied gas 14 in the container 11 reaches a predetermined amount. The liquefied gas storage device may be any one other than the cylinder 24 as long as it is suitable for storing liquefied gas, and may be, for example, a tank.

The container 11 also includes a gap 17 between the inner wall 15 and the outer wall 16.
Fluid inlet 18 so that the heating fluid can flow to
And a fluid outlet 19. As the heating fluid, a gas such as air or an inert gas (nitrogen or the like) can be used, or a liquid such as water may be used. However, when a liquid is used, the supply of the heating fluid is stopped in order to keep the liquefied gas 14 in the container that has reached a predetermined temperature by heating, and the gap 17 between the inner wall 15 and the outer wall 16 is stopped. Gas is used as a heating medium because it is inefficient because the residual liquid takes a long time to evacuate when discharging the fluid and evacuating the gap 17 using the vacuum unit 21. Is preferred. When the liquefied gas is flammable, it is preferable to use an inert gas rather than air. The heating fluid may be released to the atmosphere after use, or may be recycled.

Liquefied gas transferred from the cylinder 24 into the container 11
As described above, 14 is heated by supplying an inert gas such as nitrogen from the heating fluid inlet 18 to the gap 17 of the double wall structure. Preferably, this inert gas is in the container 11
It is controlled and supplied so that the temperature of the liquefied gas 14 therein is constant. In the case where the temperature of the liquefied gas in the container 11 rises above a predetermined temperature when the inert gas is continuously supplied, such as when the consumption of the vaporized gas is stopped, the heating inert gas is used. The gas supply is stopped and the vacuum unit 21 is activated to evacuate the gap 17 of the double wall structure to create a vacuum. By doing so, the liquefied gas in the container can be effectively kept warm and its temperature can be maintained. A heat insulating material may be provided around the container 11 to further improve the heat insulating efficiency. In addition,
In FIG. 1, the vacuum unit 21 is connected to a pipe connected to the outlet 19 through which the heating fluid is discharged from the gap 17 of the double wall structure, but the vacuum unit 21 is connected to the inlet 18 on the heating fluid supply side. It does not matter if it is connected to a connecting pipe.

As described above, the double wall structure of the container 11 is used for both the purpose of heating and keeping the liquefied gas 14 in the container warm.
Therefore, in order to increase the thermal efficiency, this double wall structure is
It is preferably made to cover as much of the 11 surface as possible.

The gas vaporized in the container 11 is the vaporized gas outlet.
Supplied from 13 to User 25. Since the temperature of the liquefied gas in the container 11 is maintained substantially constant as described above, the pressure of the vaporized gas in the container 11 is also maintained substantially constant, so that the user can use the vaporized gas. If it is resumed, it can respond immediately.

When the temperature of the liquefied gas in the container 11 is lowered, the vacuum in the gap 17 of the double wall structure of the container 11 is released and the supply of the heating fluid is started again. The decrease in the temperature of the liquefied gas in the container 11 occurs due to the evaporation of the liquefied gas in the container accompanying the consumption of the gas, the supply of new liquefied gas from the cylinder 24, or the natural heat dissipation from the container 11.

In FIG. 1, the liquefied gas inlet 12 and the vaporized gas outlet are shown.
Although 13 is shown as separate, in some cases (for example, when the required capacity of container 11 is small and it is difficult to provide separate inlets and outlets), the inlets and outlets may be combined together. You can leave it alone. This mode is particularly suitable when the supply of the liquefied gas to the container 11 and the delivery of the vaporized gas from the container 11 do not overlap.

In the vaporized gas supply pipe 28 from the container 11 to the user 25, a phenomenon in which a part of the vaporized gas is cooled and condensed by heat radiation from the pipe and condensed again is observed. Plumbing 28
If there is a structure part where the pipe once descended rises in the middle of the above, the reliquefied gas forms a liquid pool and blocks a part of the pipe, which hinders the normal supply of vaporized gas. In order to avoid this, the vaporized gas supply pipe 28 from the container 11 to the user 25 should have a function of collecting the gas reliquefied on the way. Recovery of the reliquefied gas in the middle of the piping can be performed by providing a mechanism for returning the reliquefied gas to the cylinder 24. This can be accomplished by providing a line for returning the reliquefied gas from line 28 to cylinder 24, as shown at 29 in FIG. Further, the pipe 28 from the container 11 to the user 25 may be provided with a slope inclined downward toward the container 11 so that the reliquefied gas is collected in the container 11.

[0016]

In the present invention, a container separate from the liquefied gas reservoir is adopted as a double-walled gas evaporator, and a heating fluid is caused to flow in the gap between the inner wall and the outer wall to heat the liquefied gas. In addition to the above, the supply of the heating fluid is stopped when the heating of the liquefied gas is completed, and the gap of the double wall structure can be evacuated. Therefore, it becomes possible to keep the temperature of the container much more effective when the heating is stopped, and along with this, it becomes possible to improve the thermal efficiency and suppress the waste of energy. Further, since the heat retaining effect of the liquefied gas in the evaporation container is enhanced, it becomes possible to hold the liquefied gas in the container in a state where it is easily vaporized for a long time, and the gas having a predetermined pressure can be supplied when necessary. become able to.

Further, when the use of vaporized gas is interrupted, a function of recovering the reliquefied gas from the evaporation container to the user in the middle of the supply pipe is provided, so that the gas supply amount is insufficient due to the blockage of the pipe. And, it becomes possible to prevent pressure fluctuation.

[0018]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The examples described herein are for illustrative purposes and, of course, are not intended to limit the invention.

An embodiment of the present invention is shown in FIG. In this figure, 41 represents a liquefied gas cylinder, and the evaporation container of the gas evaporation device is indicated by 42. The liquefied gas cylinder 41 is filled with a liquefied gas of, for example, tungsten hexafluoride. The evaporation container 42 has, for example, an outer diameter of 104 mm and an inner diameter.
100 mm, height 250 mm stainless steel member 43 for inner wall construction,
Stainless steel member for outer wall construction with outer diameter 200 mm and inner diameter 190 mm 44
It consists of Further, a gap between the member 43 forming the inner wall and the member 44 forming the outer wall of the double wall structure of the evaporation container 42.
Evaporation vessel 42 is connected to a vacuum unit 46 so that 45 can be evacuated.

The liquefied gas in the cylinder 41 is supplied to the container 42 through the pipe 51 by opening the valve V1. The liquid level in the container 42 is monitored by a liquid level gauge LS, and when the liquid level reaches a predetermined level, the valve V1 is closed by a signal from LS to stop the supply of liquefied gas. When the liquid level in the container 42 drops to a certain level, the liquid level gauge LS operates, and the signal causes the valve V1 to open and the liquefied gas to be supplied from the cylinder 41 again.

On the other hand, the temperature of the liquefied gas in the container 42 is measured by a thermometer T.
When the liquid temperature in the container 42 drops as in the case where the liquefied gas is supplied from the cylinder 41 as monitored by I, the inert gas supply valve V2 and the discharge valve V3 are opened by a command from the temperature control device SC. , The inert gas begins to flow into the gap 45 of the double wall structure of the container 41, and at the same time, the heater 47 is activated by the signal from the temperature control device SC.
The heating of the inert gas starts at. The supply temperature of the inert gas is also monitored by the thermometer TI installed in the supply pipe 52, and is controlled by adjusting the thermal energy given to the inert gas by the heater 47. As the inert gas heater 47, any type can be used. For example, it may be of a type heated by an infrared heater, or may use another heating medium (for example, steam). While flowing the inert gas for heating, the valve V4 provided in the pipe 54 connected to the vacuum unit 46 is closed, and the inert gas used for heating is passed through the pipe 53. Is discharged. The discharged inert gas may be circulated and reused.

After the supply of the heating inert gas is started, if the temperature of the liquefied gas in the evaporation container 41 reaches a predetermined value, the container 42
A signal from a thermometer TI inside the temperature controller SC functions to stop heating of the inert gas in the heater 47, close the valves V2 and V3 of the inert gas pipe, and to the vacuum unit 46. Open the valve V4 of the connected pipe 54 and open the vacuum unit.
Start operation of 46. The vacuum unit 46 can be composed of any vacuum generating means. For example, an ejector type vacuum generating means may be used, or a vacuum pump may be used. When the gap 45 of the double wall structure becomes a vacuum, the valve V4 is closed and the operation of the vacuum unit 46 is stopped. By thus maintaining the gap 45 of the double wall structure in a vacuum, the heat retaining effect of the liquefied gas in the container 42 is enhanced.

The temperature of the liquefied gas in the container 42 is controlled by the vaporization of the liquefied gas accompanying the consumption of the gas, the replenishment of the liquefied gas from the cylinder 41 due to the lowering of the liquid level in the container 42, and the natural temperature of the container 42. It also decreases due to heat dissipation. The temperature of the liquefied gas in the container 42 is monitored by the thermometer TI as described above, and when the temperature falls to a predetermined temperature, the heating operation described above is repeated.

The gas vaporized in the evaporation container 42 is supplied to the user 48 via the pipe 55. In the embodiment shown in FIG. 2, the piping
55 is provided with a shutoff valve V5, which is closed when the user 48 is not using gas.
When the user 48 starts to use the gas, a signal from a flow meter (not shown) that detects the use of the gas opens the valve V5, and the supply of the gas from the container 42 is started. The valve V6 arranged downstream of the valve V5 is a control valve for keeping the supply gas pressure to the user 48 constant. When the user 48 stops using the gas, a signal from a flow meter (not shown) closes the shut-off valve V5. By providing a shutoff valve between the gas evaporator and the user (gas consuming equipment) in this way, the shutoff valve V5
As a result of the gas being reliquefied in the pipe 56 on the user side downstream of, the excess gas is prevented from being supplied to the portion of the pipe 56 from the evaporation container 42. Further, the reliquefied gas generated in the pipe 56 is returned to the cylinder 41 via the pipe 57. This pipe 57 is also provided with a shutoff valve V7, which is operated in conjunction with the shutoff valve V5 of the pipe 55, so that the valve V5 is open, i.e. closed when the user 48 is using gas. And is opened periodically when valve V5 is closed.

The pipe through which the vaporized gas flows has an appropriate gradient so that the gas reliquefied in the pipe can be collected without staying in the pipe. The reliquefied gas can be collected in the cylinder 41 or can be collected in the evaporation container 42 (FIG. 2 shows the case of collecting in the cylinder 41).

Although an example of completely automatic operation has been described here, it is of course possible to operate manually, and a part of the operation can be automated (for example, liquefied gas heating / heating operation or vaporized gas). Automate the supply operation to users) and operate the rest manually. It is also possible to connect the vaporized gas supply pipe from the container 42 to a plurality of users and supply the vaporized gas to each of them.

[0027]

As described above, according to the present invention,
By flowing a heated inert gas into the gap of the double-walled structure of the evaporation container to heat the liquefied gas in the container and then vacuuming this gap to keep the liquefied gas warm, the waste of energy is suppressed. In addition, the liquefied gas in the container can be kept at a temperature at which it can be easily vaporized for a long time, so that the gas of the required amount and the required pressure can be supplied at any time according to the demand of the gas consuming facility (user).

Further, according to the present invention, by providing the function of recovering the reliquefied gas in the middle of the piping from the evaporation container to the consuming facility, the gas supply amount shortage and the pressure due to the clogging of the pipe with the reliquefied gas are caused. It becomes possible to prevent fluctuation.

[Brief description of drawings]

1 is an illustration of the apparatus and method of the present invention.

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

[Explanation of symbols]

 11 ... Container 12 ... Liquefied gas inlet 13 ... Vaporized gas outlet 14 ... Liquefied gas 15 ... Container inner wall 16 ... Container outer wall 17 ... Gap between inner wall and outer wall 18 ... Heating fluid inlet 19 ... Heating fluid outlet 21 ... Vacuum unit 24 ... Liquefied gas cylinder 25 ... Gas consumption equipment 41 ... Liquefied gas cylinder 42 ... Evaporation container 43 ... Inner wall constituent member 44 ... Outer wall constituent member 45 ... Double wall structure gap 46 ... Vacuum unit 47 ... Heating unit 48 ... Gas consumption equipment

Claims (11)

[Claims] 1. A container (11) having a double wall structure formed of an inner wall (15) and an outer wall (16) for supplying a liquefied gas (14) into the container (11). Has a liquefied gas inlet (12) and a vaporized gas outlet (13) for sending vaporized gas to the outside of the container, and further comprises an inner wall (15) and an outer wall (16) of the double wall structure. A container (11) having a fluid inlet (18) and a fluid outlet (19) for letting in and out a liquefied gas heating fluid, and an inner wall (15) and an outer wall (15) of the double wall structure. A gas evaporator comprising a means (21) for evacuating a gap (17) with the space (16). 2. The apparatus according to claim 1, wherein an inert gas is used as the liquefied gas heating fluid. 3. The apparatus according to claim 1, wherein the vaporized gas outlet of the container is connected to one or more gas consuming facilities via a pipe. 4. The apparatus according to claim 3, further comprising a mechanism for grading the pipe and collecting the reliquefied gas generated in the pipe without allowing the reliquefied gas to remain in the pipe. 5. A shutoff valve is provided in the pipe, and a mechanism is provided for collecting the reliquefied gas generated in the pipe downstream of the shutoff valve when the supply of gas to the gas consuming facility is stopped.
Or the device according to 4. 6. A liquefied gas is placed in a container having a double wall structure formed of an inner wall and an outer wall, and a fluid for heating the liquefied gas is flown between the inner wall and the outer wall of the double wall structure. To heat the liquefied gas in the container, and when the liquefied gas reaches the specified temperature, stop the supply of the heating fluid and create a vacuum between the inner and outer walls of the double wall structure to liquefy the inside of the container. A gas supply method characterized in that the gas is kept warm, and if the temperature of the liquefied gas in the container drops, the liquefied gas is heated and the subsequent heat retention operation is repeated, and the gas vaporized in the container is supplied to the gas consuming facility. . 7. The method according to claim 6, wherein an inert gas is used as the heating fluid. 8. The method according to claim 1, wherein the gas vaporized in the container is supplied to one or more gas consuming facilities. 9. The method according to claim 8, wherein reliquefied gas generated on the way from the container to the gas consuming facility is collected to prevent pooling of the liquid. 10. The method according to claim 6, wherein the heating operation and the heat insulating operation of the liquefied gas are performed automatically. 11. The method according to claim 6, wherein the vaporized gas is supplied automatically.