JP2004052105A - Gaseous fluorine generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gaseous fluorine generator which can stably and safely generate highly pure gaseous fluorine. <P>SOLUTION: The gaseous fluorine generator for generating highly pure gaseous fluorine by electrolyzing an electrolytic bath 2 consisting of a hydrogen fluoride-containing mixed molten salt is provided with: an electrolytic cell 1 divide, by a partition wall 16, into an anode chamber 3 provided with an anode and a cathode chamber 4 provided with a cathode; a pressure maintenance means of maintaining the pressure inside the anode chamber 3 and the cathode chamber 4 at atmospheric pressure; and liquid level sensing means 5 and 6 capable of sensing the liquid face levels of the electrolytic bath 2 in the anode chamber 3 and the cathode chamber 4, respectively, at three or more stages. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an on-site type fluorine gas generator.
[0002]
[Prior art]
Conventionally, fluorine gas has been an essential gas indispensable in, for example, the semiconductor manufacturing field. In some cases, nitrogen trifluoride gas (hereinafter referred to as NF ₃ gas) or the like is synthesized based on fluorine gas, and is used as a cleaning gas or dry etching gas for semiconductor manufacturing equipment. Demand for gas is growing rapidly. Further, neon fluoride gas (hereinafter, referred to as NeF gas), argon fluoride gas (hereinafter, referred to as ArF gas), krypton fluoride gas (hereinafter, referred to as KrF gas), or the like is used for patterning a semiconductor integrated circuit. Excimer laser oscillation gas is used, and a mixed gas of a rare gas and a fluorine gas is frequently used as a raw material thereof.
[0003]
Fluorine gas and NF ₃ gas used in the production of semiconductors and the like are required to be high-purity gas with few impurities. Also, in a manufacturing site for semiconductors and the like, a required amount of gas is extracted from a gas cylinder filled with fluorine gas and used. For this reason, it is very important to control the storage location of gas cylinders, ensuring gas safety and maintaining purity. Furthermore, since the demand for NF ₃ gas has been rapidly increasing recently, there is a problem in supply, and there is also a problem that a certain amount of stock must be held. In consideration of these, it is preferable to install the apparatus at a place where an on-demand on-site fluorine gas generator is used, rather than handling a high-pressure fluorine gas cylinder.
[0004]
Usually, fluorine gas is generated by an electrolytic cell as shown in FIG. The material of the electrolytic cell body 201 is usually Ni, Monel, carbon steel, or the like. Further, a bottom plate 212 made of polytetrafluoroethylene or the like is attached to the bottom of the electrolytic cell main body 201 in order to prevent the generated hydrogen gas and fluorine gas from being mixed. The electrolytic bath body 201 is filled with a mixed molten salt of potassium fluoride-hydrogen fluoride (hereinafter, referred to as KF-HF) as an electrolytic bath 202. The anode chamber 210 and the cathode chamber 211 are separated by a skirt 209 formed of Monel or the like. A voltage is applied between the carbon or nickel (hereinafter, referred to as Ni) anode 203 housed in the anode chamber 210 and the Ni cathode 204 housed in the cathode chamber 211 to perform electrolysis to generate fluorine gas. I have. Note that the generated fluorine gas is discharged from the generation port 208, and the hydrogen gas generated on the cathode side is discharged from the hydrogen gas discharge port 207. However, it is difficult to obtain high-purity fluorine gas due to mixing of carbon tetrafluoride gas (hereinafter, referred to as CF ₄ gas) generated during electrolysis and hydrogen fluoride gas (hereinafter, referred to as HF gas) evaporated from the electrolytic bath. There was a problem.
[0005]
When used on demand or on site, automatic adjustment of the liquid level of the electrolytic bath in the electrolytic cell main body 201 is indispensable for safe automatic operation. For example, so-called start / stop control (On / Off control) has been proposed in Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and Patent Literature 5 as a technique for controlling the fluctuation of the electrolyte surface. I have. However, when the electrolysis is performed by this method, there is a problem that the electrolysis is stopped every time the liquid level changes, and the electrolysis cannot be restarted until the electrolyte level returns to the original position.
[0006]
[Patent Document 1]
Japanese Patent Publication No. 9-505853 [Patent Document 2]
European Patent No. 0728228 B1 [Patent Document 3]
European Patent No. 0852267B1 [Patent Document 4]
European Patent No. 0965661B1 [Patent Document 5]
US Pat. No. 5,688,384.
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a fluorine gas generator capable of stably and safely generating high-purity fluorine gas.
[0008]
[Means for Solving the Problems]
The fluorine gas generating apparatus according to claim 1 of the present invention for solving the above-mentioned problems is provided with a fluorine gas for electrolyzing an electrolytic bath made of a mixed molten salt containing hydrogen fluoride to produce high-purity fluorine gas. A gas generator, comprising: an electrolytic cell separated by a partition into an anode chamber provided with an anode and a cathode chamber provided with a cathode; pressure maintaining means for maintaining the inside of the electrolytic cell at atmospheric pressure; and the anode chamber And a liquid level detecting means capable of detecting the liquid level of the electrolytic bath in each of the cathode chambers in three or more stages.
According to this configuration, a slight change in the liquid level can be detected, and the pressure maintaining means can always maintain the anode chamber and the cathode chamber at atmospheric pressure. Therefore, the liquid level of the electrolytic bath is stabilized. As a result, fluctuations in electrolysis conditions during electrolysis can be reduced, so that a stable supply of fluorine gas can be achieved. Further, since the anode chamber and the cathode chamber are maintained at the atmospheric pressure, inflow of air or the like from the outside can be prevented, and high-purity fluorine gas can be generated stably.
[0009]
The fluorine gas generating device according to claim 2, wherein the pressure maintaining means is an automatic valve that opens and closes in conjunction with a pressure gauge provided in each of the anode chamber and the cathode chamber. And an automatic valve interlocked with a liquid level detecting means provided in each of the cathode chambers.
According to this configuration, pressure control in the electrolytic cell can be easily and reliably performed. In addition, since the liquid level detecting means and the automatic valve are linked, the liquid level of the electrolytic bath can be automatically adjusted.
[0010]
According to a third aspect of the present invention, in the fluorine gas generating apparatus according to the second aspect, the automatic valve, which is one of pressure maintaining means for maintaining the pressure in the electrolytic cell at atmospheric pressure, comprises: When it is higher than this, it opens to discharge the gas in the electrolytic cell.
According to this configuration, the inside of the electrolytic cell, particularly the inside of the cathode chamber, can always be maintained at the atmospheric pressure. For this reason, the liquid level of the electrolytic bath in the electrolytic cell can always be kept stable.
[0011]
The fluorine gas generating device according to claim 4, according to any one of claims 1 to 3, wherein at least one of a compressor and a vacuum generator is provided behind an automatic valve that opens and closes in conjunction with the pressure gauge. An automatic valve, which is provided and opens and closes in conjunction with the pressure gauge, is maintained in a reduced pressure state.
According to this configuration, the gas discharge line downstream of the automatic valve that opens and closes in conjunction with the pressure gauge is in a reduced pressure state. Therefore, the gas discharged from the cathode chamber more reliably passes through the automatic valve that opens and closes in conjunction with the pressure gauge.
[0012]
According to a fifth aspect of the present invention, in the fluorine gas generator according to the first aspect, the liquid level detecting means is configured by three or more liquid level sensors capable of detecting each liquid level of the electrolytic bath. .
According to this configuration, the liquid level of the electrolytic bath in the electrolytic cell can be detected in three or more stages, so that even a slight change in the liquid level can be detected. Then, in accordance with the signal from each liquid level sensor, it is possible to open and close each valve on each gas line connected to the electrolytic cell to flow gas and pressurize or depressurize to raise the liquid level. Become. For this reason, even if electrolysis is not stopped one by one by the liquid level control (On / Off control) of the electrolytic bath as disclosed in Patent Document 1 or the like, automatic operation in a state where the liquid level is maintained at a constant level is performed. Becomes possible.
[0013]
A sixth aspect of the present invention is a fluorine gas generator having a liquid level detecting means and a pressure gauge capable of detecting the pressure in the electrolytic cell.
According to this configuration, the liquid level fluctuation due to the rise or fall of the electrolytic bath caused by the differential pressure can be controlled more accurately, and the clogging of a filter attached to a pipe or a line at a later stage due to scattering of the electrolytic bath or the like can be prevented. With this control, safe and stable operation can be secured.
[0014]
The gas supplied to the cathode chamber and the anode chamber by opening and closing the solenoid valve that opens and closes in conjunction with the liquid level detection means according to claim 1 or 2, It is a rare gas or a nitrogen gas.
According to this configuration, the generated gas is optionally diluted with a rare gas such as nitrogen (N ₂ ) gas or neon gas (Ne gas), argon gas (Ar gas), or krypton gas (Kr gas). Can be used as an excimer laser oscillation gas used in patterning a semiconductor integrated circuit.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of a fluorine gas generator according to the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a schematic view of a main part of the fluorine gas generator of the present embodiment. In FIG. 1, 1 is an electrolytic bath, 2 is an electrolytic bath made of a KF-HF-based mixed molten salt, 3 is an anode room, 4 is a cathode room, and 5 is a liquid level of the electrolytic bath 2 in the anode room 3. The first liquid level detecting means 6 is a second liquid level detecting means for detecting the liquid level of the cathode chamber 4 in five steps. Reference numeral 7 denotes a pressure gauge for measuring the pressure in the anode chamber 3, and reference numeral 8 denotes a pressure gauge for measuring the pressure in the cathode chamber 4. Reference numerals 9 and 10 denote automatic valves that open and close in conjunction with the pressures of the pressure gauges 7 and 8. Reference numeral 11 denotes a thermometer for measuring the temperature of the electrolytic bath 2, and reference numeral 12 denotes a temperature control means which operates in response to a signal from the thermometer 11 to control a heater 13 provided on the side and bottom of the electrolytic cell 1. 14 is a adsorption tower to adsorb HF from a mixed gas of hydrogen and HF discharged from the cathode chamber 4, 15 adsorbs HF gas from a mixed gas of F ₂ and HF discharged from the anode chamber 3 Is an HF absorption tower filled with NaF or the like that discharges only high-purity fluorine gas.
[0017]
The electrolytic cell 1 is formed of a metal such as Ni, Monel, pure iron, and stainless steel.
The electrolytic cell 1 is separated into an anode chamber 3 and a cathode chamber 4 by a partition 16 made of Ni or Monel. Although not shown, an anode is disposed in the anode chamber 3. The cathode chamber 4 is provided with a cathode (not shown). In addition, it is preferable to use an anode formed by processing a graphite molded body into a predetermined shape to form a block. Further, it is preferable to use Ni or iron as the cathode. In the upper lid 17 of the electrolytic cell 1, purge gas inlets and outlets 20 and 21 from gas lines 18 and 19, which are one of pressure maintaining means for maintaining the inside of the anode chamber 3 and the cathode chamber 4 at atmospheric pressure, and a gas generated from the anode chamber 3. An outlet 22 for generating a fluorine gas and an outlet 23 for generating a hydrogen gas generated from the cathode chamber 4 are provided. Each of the generating ports 22 and 23 has a bent tube made of a material having corrosion resistance to fluorine gas such as Hastelloy, and splashes from the anode chamber 3 and the cathode chamber 4 enter the gas line. That is being suppressed. In addition, the upper lid 17 has the HF inlet 25 from the HF supply line 24 for supplying HF when the liquid level of the electrolytic bath 2 is lowered, and the liquid level of the anode chamber 3 and the cathode chamber 4 respectively. A first liquid level detecting means 5 and a second liquid level detecting means 6 for detecting, and pressure gauges 7 and 8 are provided.
[0018]
The electrolytic cell 1 is provided with a temperature adjusting means for heating the inside of the electrolytic cell 1. The temperature adjusting means includes a heater 13 provided in close contact with the periphery of the main body of the electrolytic cell 1, a temperature controlling means 12 connected to the heater 13 and capable of performing general PID control, an anode chamber 3 or a cathode chamber. And a thermometer 11 such as a thermocouple provided in any one of the electrolyzers 4 to control the temperature in the electrolytic cell 1. Note that a heat insulating material can be provided around the heater 13. The heater 13 can be exemplified by a ribbon type, a nichrome wire, hot water, or the like. The form is not particularly limited, but is preferably a shape that covers the entire circumference of the electrolytic cell 1.
[0019]
The first liquid level detecting means 5 and the second liquid level detecting means 6 include five liquid level sensors S1 to S5 as shown in FIG. These five liquid level sensors S1 to S5 can detect the liquid level of the electrolytic bath 2 stepwise.
[0020]
The pressure maintaining means for maintaining the pressure in the anode chamber 3 and the cathode chamber 4 at the atmospheric pressure is provided by measuring the gas from the pressurizing cylinder with the pressure gauges 7 and 8 for measuring the pressure in the anode chamber 3 and the cathode chamber 4. Automatic valves 9 and 10 that open and close in response to the results, and open and close according to the result of detection of the liquid level of the electrolytic bath 2 by the first liquid level detecting means 5 and the second liquid level detecting means 6. Automatic valves 31 to 34 for supplying or exhausting gas to the anode chamber 3 and the cathode chamber 4 respectively; manual valves 35 to 38 for opening and closing the gas lines 18 and 19 of the pressure maintaining means; It is composed of flow meters 39 to 41 that can set the flow rate of the passing gas to a predetermined flow rate in advance. It is preferable that the automatic valves 31 to 34 use an air actuator type. Thereby, heat generation during operation is small, and the influence on the gas line can be reduced. The pressure in the anode chamber 3 and the cathode chamber 4 is maintained at the atmospheric pressure by the pressure maintaining means. Thereby, the pressure in the electrolytic cell 1 is maintained at the atmospheric pressure, and the liquid level during electrolysis can be maintained in a stable state. Therefore, stable electrolysis can be performed with little change in electrolysis conditions. Further, the fluorine gas and the hydrogen gas generated by the electrolysis are discharged from the respective generating ports 22 and 23 so as to be pushed out of the electrolytic cell 1. As described above, the pressure maintaining means discharges the gas generated by the electrolysis from the electrolytic cell 1 by maintaining the pressures in the anode chamber 3 and the cathode chamber 4 at the atmospheric pressure, and discharges the gas into the electrolytic cell 1. It also prevents outside air from entering.
[0021]
The gas for supplying the gas into the electrolytic cell 1 connected to the pressure maintaining means is not particularly limited as long as it is an inert gas. For example, when one or more rare gases such as Ar gas, Ne gas, Kr gas, and Xe gas are used, a mixed gas of fluorine gas and these rare gases can be easily obtained at an arbitrary mixing ratio. This makes it possible, for example, to use it as a radiation source for excimer laser oscillation for patterning integrated circuits in the semiconductor manufacturing field, and by disposing the fluorine gas generator according to the present invention on a manufacturing line in the semiconductor manufacturing field, On-site, the required amount of fluorine gas can be supplied when needed.
[0022]
The HF adsorption tower 14 that adsorbs HF gas in the hydrogen gas discharged from the cathode chamber 4 has a first adsorption tower 14a and a second adsorption tower 14b provided in parallel. The first adsorption tower 14a and the second adsorption tower 14b can be used simultaneously or one of them can be used. The adsorption tower 14 is preferably formed of a material having corrosion resistance to fluorine gas and HF. For example, the adsorption tower 14 is formed of stainless steel, Monel, Ni, a fluorine-based resin, or the like. The lime in the hydrogen gas is removed by filling the lime and absorbing the passing HF.
[0023]
This HF adsorption tower 14 is arranged downstream of the automatic valve 10 which is one of the pressure maintaining means. A vacuum generator 26 is provided between the automatic valve 10 and the HF adsorption tower 14. The vacuum generator 26 reduces the pressure in the gas line 28 by the ejector effect of the gas passing through the gas line 27, and can reduce the pressure of the gas line 28 without using oil. In addition, it is possible to prevent oil from entering the gas line and the electrolytic cell 1.
[0024]
The HF absorption tower 15 for removing HF in the fluorine gas discharged from the anode chamber 3 is provided with the first absorption towers 15a and 15b in parallel, similarly to the HF adsorption tower 14 described above. Then, the inside is filled with NaF, and HF contained in the released fluorine gas is removed. Like the HF adsorption tower 14, the HF absorption tower 15 is preferably formed of a material having corrosion resistance to fluorine gas and HF, and examples thereof include stainless steel, Monel, and Ni.
[0025]
On the downstream side of the HF absorption tower 15, an automatic valve 9, which is one of pressure maintaining means, is provided. The gas generated from the anode chamber 3 is a severe environment in which HF gas and electrolytic bath splash are generated simultaneously with fluorine gas. Particularly in an environment where fluorine and HF are mixed, a strong oxidizing atmosphere is created. Therefore, by providing the automatic valve 9 on the downstream side of the HF absorption tower 15, only the fluorine gas from which HF has been removed can be used, and the opening and closing operation can be performed without being affected by the HF gas. . The HF adsorption tower 14 and the HF absorption tower 15 are provided with pressure gauges 30 and 29, respectively, so that clogging inside can be detected.
[0026]
In addition, it is preferable that the fluorine gas generator including the electrolytic cell 1 is provided in a cabinet including a single casing (not shown). This is because on-demand and on-site use becomes easy. This cabinet is preferably made of a material that does not react with fluorine gas. For example, a metal such as stainless steel or a resin such as vinyl chloride can be used.
[0027]
Although not shown, a storage means such as a buffer tank is preferably provided on the downstream side where high-purity fluorine gas is discharged. As a result, a required amount of fluorine gas can be provided when required, and an on-line fluorine gas generator can be provided on a production line of a semiconductor production facility.
[0028]
Next, the operation of the fluorine gas generator according to this embodiment will be described.
[0029]
Normally, in a state where electrolysis is normally performed, the inside of the electrolytic cell 1 is maintained at the atmospheric pressure, and the heights of the electrolytic baths 2 in the anode chamber 3 and the cathode chamber 4 are the same liquid level. However, during electrolysis, a fluorine gas line (gas line after the fluorine gas generation port 22) is blocked due to accumulation of, for example, droplets of the electrolytic bath 2, or a hydrogen gas line (gas line after the hydrogen generation port 23) is blocked. The pressure in the electrolytic cell 1 fluctuates due to the above factors. At this time, the pressure is measured by the pressure gauges 7 and 8 provided in the anode chamber 3 and the cathode chamber 4, and the automatic valves 9 and 10 linked to the respective pressure gauges 7 and 8 are opened and closed by the fluctuation of the pressure. The pressure in the electrolytic cell 1 is adjusted to be maintained at the atmospheric pressure.
[0030]
As described above, when the pressure in the electrolytic cell 1 is maintained at the atmospheric pressure by opening and closing the automatic valves 9 and 10, the height of the anode chamber 3 in the electrolytic cell 1 and the height of the electrolytic bath 2 in the cathode chamber 4 are increased. The liquid level is the same. However, during electrolysis, for example, droplets of the electrolytic bath 2 further accumulate, and the pressure in the electrolytic cell 1 cannot be maintained at the atmospheric pressure by opening and closing the automatic valves 9 and 10. When the pressure in the anode chamber 3 increases or the pressure in the cathode chamber 4 decreases due to blockage of the gas line after the gas generating port 22), the liquid level of the electrolytic bath 2 in the anode chamber 3 increases. May be lower than the liquid level of the electrolytic bath 2 in the cathode chamber 4. In this case, the first liquid level detecting means 5 and the second liquid level detecting means 6 provided in the anode chamber 3 and the cathode chamber 4 detect an abnormality in the liquid level.
[0031]
Normally, the pressure in the electrolytic cell 1 is maintained at the atmospheric pressure by opening and closing the automatic valves 9 and 10, and when the electrolysis is performed normally, the liquid level of the electrolytic bath 2 is determined by the first liquid level detecting means 5 and Among the five liquid level sensors S1 to S5 of the second liquid level detecting means 6, it is located between the liquid level sensors S2 and S4. However, as described above, when the liquid level of the electrolytic bath 2 in the cathode chamber 4 becomes higher than the liquid level of the electrolytic bath in the anode chamber 3, that is, the liquid level of the cathode chamber 4 becomes the second level. When the level becomes higher than the level sensor S2 of the level detecting means, the automatic valves 31 and 34 are closed. When the liquid level of the electrolytic bath 2 in the cathode chamber 4 returns to normal, the automatic valve 31 and the automatic valve 34 are opened, and the electrolysis is continued. On the other hand, even when the automatic valves 31 and 34 are closed, when the liquid level of the electrolytic bath 2 in the cathode chamber 4 increases and becomes higher than the liquid level sensor S1, the automatic valves 33 and The automatic valve 32 is also closed, interrupting the electrolysis.
[0032]
When the electrolysis is interrupted, the automatic valve 32 is opened for a short time, and the fluorine gas in the anode chamber 3 is discharged from the fluorine gas generation port 23 provided in the upper lid 17 of the electrolytic cell 1. At the same time, the automatic valve 33 is also opened for a short time, and the purge gas is introduced into the cathode chamber 4. As a result, when the liquid levels of the anode chamber 3 and the cathode chamber 4 of the electrolytic bath 2 return to the same level, the electrolysis is restarted.
[0033]
As described above, the fluorine gas generator according to the present embodiment adjusts the pressure in the electrolytic cell 1 by the pressure gauges 7 and 8 that measure the pressure in the electrolytic cell 1 and the automatic valves 9 and 10 that are linked thereto. Then, the liquid level in the electrolytic bath 2 is controlled while maintaining the inside of the electrolytic bath 1 at atmospheric pressure. When the liquid level of the electrolytic bath 2 in the electrolytic cell 1 cannot be maintained at the same level by controlling the liquid level by opening and closing the automatic valves 9 and 10, the liquid is provided in the anode chamber 3 and the cathode chamber 4. The inside of the electrolytic cell 1 is maintained at the atmospheric pressure by the first liquid level detecting means 5 and the second liquid level detecting means 6 and the automatic valves 31 to 34 which open and close in conjunction with these. As described above, the inside of the electrolytic cell 1 can be maintained at the atmospheric pressure and the liquid level of the electrolytic bath 2 can be maintained at a stable level by the two-stage control method. This eliminates the need to change the electrolysis conditions during electrolysis, and allows stable generation of fluorine gas.
[0034]
The fluorine gas generator according to the present invention is not limited to the above-described embodiment, and may be, for example, the following.
[0035]
For example, the electrolytic bath is electrolyzed using the electrolytic bath main body as a cathode, and at this time, the liquid level detecting means for detecting the liquid level of the electrolytic bath controls the liquid level of the electrolytic bath by using only one. You can also do so. Further, the position, number, and the like of the automatic valves are not particularly limited to the embodiment of the present invention.
[0036]
【The invention's effect】
The present invention is configured as described above. The inside of the electrolytic cell is maintained at the atmospheric pressure, and the liquid level of the electrolytic bath is detected and controlled by two systems of a pressure gauge and a liquid level detecting means. For this reason, it is possible to keep the liquid level of the electrolytic bath at a constant level, to stabilize the electrolysis conditions, and to stably generate and supply fluorine gas. In addition, since a means for mixing the fluorine gas with another gas, for example, a rare gas, is provided, a mixed gas of a rare gas and a fluorine gas having a desired mixing ratio can be obtained. It can be used in the field.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of a fluorine gas generator of the present invention.
FIG. 2 is a schematic diagram showing an example of a liquid level detecting means used in the fluorine gas generator according to the present invention.
FIG. 3 is a schematic view of a conventionally used fluorine gas generator.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 electrolytic cell 2 electrolytic bath 3 anode chamber 4 cathode chamber 5 first liquid level detecting means 6 second liquid level detecting means 7, 8 pressure gauge 9, 10 automatic valve 11 thermometer 12 temperature control means 13 heater 14 HF adsorption tower 15 HF absorption tower 16 Partition wall 17 Top lid 18, 19 Gas line 20, 21 Purge gas inlet 22, 23 Gas generation port 24 HF supply line 25 HF introduction port 26 Vacuum generator 27, 28 Gas line 29, 30 Pressure gauge 31-34 Automatic valve 35 -38 Manual valve 39-41 Flow meter 42 Compressor unit S1-S5 Liquid level sensor

Claims (7)

A fluorine gas generator for electrolyzing an electrolytic bath made of a mixed molten salt containing hydrogen fluoride to generate high-purity fluorine gas,
An electrolytic cell separated into an anode chamber provided with an anode by a partition and a cathode chamber provided with a cathode,
Pressure maintaining means for maintaining the anode chamber and the cathode chamber at atmospheric pressure,
A fluorine gas generator comprising: a liquid level detecting means capable of detecting the liquid level of the electrolytic bath in each of the anode chamber and the cathode chamber in three or more stages. An automatic valve that opens and closes in conjunction with a pressure gauge provided in each of the anode chamber and the cathode chamber, and an automatic valve that operates in conjunction with liquid level detection means provided in each of the anode chamber and the cathode chamber. 2. The fluorine gas generator according to claim 1, comprising a valve. An automatic valve that opens and closes in conjunction with a pressure gauge, which is one of pressure maintaining means that maintains the pressure in the electrolytic cell at atmospheric pressure, opens when the pressure in the electrolytic cell becomes higher than atmospheric pressure, and opens the electrolytic cell. The fluorine gas generator according to claim 2, wherein the gas is discharged. Behind the automatic valve that opens and closes in conjunction with the pressure gauge, at least one of a compressor and a vacuum generator is provided, and a gas discharge line downstream of the automatic valve that opens and closes in conjunction with the pressure gauge is depressurized. The fluorine gas generator according to any one of claims 1 to 3, wherein the fluorine gas generator is maintained in a state. 2. The fluorine gas generator according to claim 1, wherein the liquid level detecting means includes three or more liquid level sensors capable of detecting each liquid level of the electrolytic bath. 3. The fluorine gas generator according to any one of claims 1 to 5, further comprising a pressure gauge having the liquid level detecting means and capable of detecting a pressure in an electrolytic cell. The fluorine gas generator according to claim 1, wherein the gas supplied into the electrolytic cell by opening and closing the automatic valve that opens and closes in conjunction with the liquid level detection unit is a rare gas or a nitrogen gas.

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