JP4085174B2 - Fluorine gas generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an on-site type fluorine gas generator.
[0002]
[Prior art]
Conventionally, fluorine gas is an essential gas that is indispensable in the field of semiconductor manufacturing, for example. Although it may be used by itself, nitrogen trifluoride gas (hereinafter referred to as NF ₃ gas) is synthesized based on fluorine gas, and is used for cleaning gas or dry etching of semiconductor manufacturing equipment. The 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), and the like are used for patterning a semiconductor integrated circuit. A gas for excimer laser oscillation, and a mixed gas of a rare gas and a fluorine gas is often used as a raw material.
[0003]
Fluorine gas and NF ₃ gas used for manufacturing semiconductors and the like are required to have high purity gas with few impurities. Moreover, in the manufacturing site of semiconductors, etc., a necessary amount of gas is taken out from a gas cylinder filled with fluorine gas and used. For this reason, it is very important to manage the storage location of the gas cylinder, ensuring the safety of the gas and maintaining the purity. Furthermore, since the demand for NF ₃ gas has been increasing rapidly recently, there is a problem in supply, and there is also a problem that a certain amount of inventory must be held. Considering these, it is preferable to install the on-demand, on-site fluorine gas generator in a place where the high-pressure fluorine gas cylinder is used.
[0004]
Normally, fluorine gas is generated by an electrolytic cell as shown in FIG. As the material of the electrolytic cell main body 201, Ni, Monel, carbon steel or the like is usually used. Further, a bottom plate 212 made of polytetrafluoroethylene or the like is attached to the bottom of the electrolytic cell 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 the electrolytic bath 202. The anode chamber 210 and the cathode chamber 211 are separated by a skirt 209 formed of monel or the like. Fluorine gas is generated by applying voltage 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 for electrolysis. Yes. 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 by mixing carbon tetrafluoride gas (hereinafter referred to as CF ₄ gas) generated during electrolysis or hydrogen fluoride gas (hereinafter referred to as HF gas) evaporated from the electrolytic bath. There was a problem.
[0005]
Further, 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, as a technique for controlling the fluctuation of the electrolyte surface, so-called start / stop control (On / Off control) is proposed in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5. Yes. However, when electrolysis is performed by this method, there is also a problem that the electrolysis is stopped every time the liquid level fluctuates and the electrolysis cannot be resumed until the electrolytic solution level returns to the original position.
[0006]
[Patent Document 1]
Japanese Patent Publication No. 9-505853 [Patent Document 2]
European Patent No. 0728228B1 [Patent Document 3]
European Patent No. 0852267B1 [Patent Document 4]
European Patent No. 0965661B1 [Patent Document 5]
US Pat. No. 5,688,384 Specification
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a fluorine gas generator that can stably and safely generate high-purity fluorine gas.
[0008]
[Means for Solving the Problems]
A fluorine gas generator for electrolyzing an electrolytic bath made of a mixed molten salt containing hydrogen fluoride to generate high-purity fluorine gas, comprising an anode chamber provided with an anode by a partition wall and a cathode An electrolytic cell separated into a cathode chamber, pressure maintaining means for maintaining the anode chamber and the cathode chamber at atmospheric pressure, and the liquid level of the electrolytic bath in each of the anode chamber and the cathode chamber is 5 or more Liquid level detecting means capable of detecting at the stage, wherein the liquid level detecting means is between the average liquid level and the highest abnormal liquid level and between the average liquid level and the lowest abnormal liquid. A predetermined liquid level before an abnormality can be detected between the surface level and the pressure maintaining means opens and closes in conjunction with pressure gauges provided in the anode chamber and the cathode chamber, respectively. Generated from the anode chamber and the cathode chamber The and automatic valve pressure gauge can be exhausted or shut off gas, which is connected to the cathode chamber for discharging the cathode chamber of a gas, the first interlocking automatic valve for opening and closing in conjunction with the liquid level detecting means A path having a second interlocking automatic valve connected to the anode chamber for discharging gas in the anode chamber and opening and closing in conjunction with the liquid level detection means, and the purge gas for supplying the purge gas. A path having a third interlocking automatic valve that is connected to the cathode chamber and opens and closes in conjunction with the liquid level detecting means, and is connected to the anode chamber for supplying purge gas, and in conjunction with the liquid level detecting means. A path having a fourth interlocking automatic valve that opens and closes before the liquid level detecting means in the cathode chamber becomes abnormal between the average liquid level and the highest abnormal liquid level. When a predetermined liquid level is detected The first interlocking automatic valve is closed to shut off the gas exhausted from the cathode chamber, and the fourth interlocking automatic valve is shut off from the purge gas supplied to the anode chamber. When the liquid level detecting means in the cathode chamber is closed and the uppermost abnormal liquid level is detected, the second interlocking automatic valve shuts off the gas generated in the anode chamber. Therefore , the third interlocking automatic valve is closed to shut off the purge gas supplied to the cathode chamber .
According to this configuration, a slight change in the liquid level can be detected, and the anode chamber and the cathode chamber can always be maintained at atmospheric pressure by the pressure maintaining means. For this reason, the liquid level of the electrolytic bath is stabilized. As a result, fluctuations in the electrolysis conditions during electrolysis can be reduced, so that stable fluorine gas supply can be achieved. Further, since the anode chamber and the cathode chamber are maintained at atmospheric pressure, inflow of air or the like from the outside can be prevented, and high-purity fluorine gas can be stably generated. Moreover, the pressure control in the electrolytic cell can be easily and reliably performed. Furthermore, since the liquid level detecting means and the automatic valve are interlocked, the liquid level of the electrolytic bath can be automatically adjusted.
[0010]
According to a second aspect of the present invention, there is provided the fluorine gas generator according to the first aspect, wherein the automatic valve, which is one of pressure maintaining means for maintaining the pressure in the electrolytic cell at atmospheric pressure, has a large pressure in the electrolytic cell. When it becomes higher than the atmospheric pressure, it opens and discharges the gas in the electrolytic cell.
According to this configuration, the inside of the electrolytic cell, particularly the cathode chamber, can always be maintained at atmospheric pressure. For this reason, the liquid level height of the electrolytic bath in the electrolytic bath can always be in a stable state.
[0011]
Fluorine gas generator according to claim 3, in claim 1 or 2, behind the automatic valve which opens and closes in conjunction with the pressure gauge, a compressor, one or more at least one is provided out of the vacuum generator , the automatic valve which opens and closes in conjunction with the pressure gauge in which is maintained in a reduced pressure state.
According to this configuration, the gas discharge line on the downstream side of the automatic valve that opens and closes in conjunction with the pressure gauge is decompressed. For this reason, the gas discharged from the cathode chamber passes through the automatic valve that opens and closes in conjunction with the pressure gauge more reliably.
[0012]
According to a fourth aspect of the present invention, there is provided the fluorine gas generator according to the first aspect, wherein the liquid level detecting means is constituted by five or more liquid level sensors capable of detecting each liquid level of the electrolytic bath. .
According to this configuration, it is possible to detect the liquid level of the electrolytic bath in the electrolytic cell in five or more stages, so that even a slight liquid level fluctuation can be detected. And according to the signal from each liquid level sensor, it is possible to raise and lower the liquid level by opening and closing each valve on each gas line connected to the electrolytic cell and injecting gas to pressurize or depressurize Become. For this reason, automatic operation in a state where the liquid level is maintained at a constant level without stopping electrolysis by the liquid level control (On / Off control) of the electrolytic bath as disclosed in Patent Document 1 or the like. Is possible.
[0013]
The invention according to claim 5 is a fluorine gas generator having a pressure gauge capable of detecting the pressure in the electrolytic cell while having liquid level detecting means.
According to this configuration, the fluctuation of the liquid level due to the rise and fall of the electrolytic bath caused by the differential pressure can be controlled more accurately, and blockage of a filter attached to the downstream piping or line 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 fluorine gas generator according to claim 6 is the gas supplied to the cathode chamber and the anode chamber according to claim 1 or 2 by opening and closing the electromagnetic valve that opens and closes in conjunction with the liquid level detection means. It is a rare gas or nitrogen gas.
According to this configuration, the generated gas is arbitrarily diluted with a rare gas such as nitrogen (N ₂ ) gas, neon gas (Ne gas), argon gas (Ar gas), or krypton gas (Kr gas). It can be used as a gas for excimer laser oscillation used in patterning of a semiconductor integrated circuit as a mixed gas of the above mixture ratio.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a fluorine gas generator according to the present invention will be described based on the drawings.
[0016]
FIG. 1 is a schematic view of the main part of the fluorine gas generator of this embodiment. In FIG. 1, 1 is an electrolytic cell, 2 is an electrolytic bath made of a KF-HF mixed molten salt, 3 is an anode chamber, 4 is a cathode chamber, and 5 is a first detecting the liquid level of the electrolytic bath 2 in the anode chamber 3. 1 liquid level detection means, 6 is a 2nd liquid level detection means which detects the liquid level of the cathode chamber 4 in five steps. Reference numeral 7 is a pressure gauge for measuring the pressure in the anode chamber 3, and 8 is 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. Further, 11 is a thermometer for measuring the temperature of the electrolytic bath 2, and 12 is a temperature control means for operating the heater 13 provided on the side surface and bottom of the electrolytic cell 1 by being actuated by a signal from the thermometer 11. Reference numeral 14 denotes an adsorption tower for adsorbing HF from the mixed gas of hydrogen and HF discharged from the cathode chamber 4, and reference numeral 15 denotes an adsorbed HF gas from the mixed gas of F ₂ and HF discharged from the anode chamber 3. And an HF absorption tower filled with NaF or the like that discharges only high-purity fluorine gas.
[0017]
The electrolytic cell 1 is made of a metal such as Ni, Monel, pure iron, or stainless steel. The electrolytic cell 1 is separated into an anode chamber 3 and a cathode chamber 4 by a partition wall 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 what was processed into the predetermined shape from the graphite molded object, and formed in the block shape for an anode. Moreover, it is preferable to use Ni or iron as a 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 anode chamber 3 and the cathode chamber 4 at atmospheric pressure, are generated from the anode chamber 3. A fluorine gas generating port 22 and a hydrogen gas generating port 23 generated from the cathode chamber 4 are provided. These generating ports 22 and 23 are provided with bent tubes formed of a material having corrosion resistance to fluorine gas such as Hastelloy, and droplets from the anode chamber 3 and the cathode chamber 4 enter the gas line. That is restrained. Further, the upper lid 17 has the HF introduction port 25 from the HF supply line 24 for supplying HF when the liquid level height of the electrolytic bath 2 is lowered, and the liquid level heights 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]
Moreover, 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 control means 12 connected to the heater 13 and capable of general PID control, and the anode chamber 3 or the cathode chamber. 4, and a thermometer 11 such as a thermocouple provided in any one of them, and controls the temperature in the electrolytic cell 1. A heat insulating material can be provided around the heater 13. The heater 13 can be exemplified by a ribbon type, nichrome wire, hot water or the like, and the form thereof is not particularly limited, but is preferably a shape that covers the entire circumference of the electrolytic cell 1.
[0019]
The first liquid level detection means 5 and the second liquid level detection means 6 include five liquid level sensors S1 to S5 as shown in FIG. With these five liquid level sensors S1 to S5, the liquid level height of the electrolytic bath 2 can be detected stepwise.
[0020]
The pressure maintaining means for maintaining the pressure in the anode chamber 3 and the cathode chamber 4 at atmospheric pressure is measured by the pressure gauges 7 and 8 for measuring the pressure in the anode chamber 3 and the cathode chamber 4 with the gas from the pressurizing cylinder. The automatic valves 9 and 10 that open and close in conjunction with the results, and the first and second liquid level detection means 5 and the second liquid level detection means 6 open and close according to the detection result of the liquid level of the electrolytic bath 2. 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, and the inside of the gas line It consists of flow meters 39-41 that can set the gas flow rate to pass through in advance. The automatic valves 31 to 34 are preferably air actuator type. Thereby, heat generation is small during operation, and the influence on the gas line can be reduced. By this pressure maintaining means, the pressure in the anode chamber 3 and the cathode chamber 4 is maintained at atmospheric pressure. Thereby, the pressure in the electrolytic cell 1 is maintained at atmospheric pressure, and the liquid level during electrolysis can be maintained in a stable state. For this reason, there is little fluctuation | variation of electrolysis conditions and stable electrolysis can be performed. In addition, fluorine gas and hydrogen gas generated by electrolysis are discharged from the respective generation ports 22 and 23 so as to be pushed out of the electrolytic cell 1. Thus, the pressure maintaining means discharges the gas generated by electrolysis from the electrolytic cell 1 by maintaining the pressure in the anode chamber 3 and the cathode chamber 4 at atmospheric pressure, and supplies the gas into the electrolytic cell 1. Intrusion of outside air is also prevented.
[0021]
Further, 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 kinds of 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. Thus, for example, it can be used as an excimer laser oscillation source 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, The required amount of fluorine gas can be supplied on-site when necessary.
[0022]
The HF adsorption tower 14 that adsorbs the HF gas in the hydrogen gas discharged from the cathode chamber 4 is provided with a first adsorption tower 14a and a second adsorption tower 14b in parallel. These first adsorption tower 14a and second adsorption tower 14b can be used simultaneously, or either one can be used. The adsorption tower 14 is preferably made of a material having corrosion resistance to fluorine gas and HF, and is made of, for example, stainless steel, monel, Ni, fluorine-based resin, etc., and contains sodium fluoride and soda inside. Lime is filled and HF in hydrogen gas is removed by adsorbing HF passing therethrough.
[0023]
The HF adsorption tower 14 is disposed on the downstream side 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 gas line 28 without using oil. Intrusion into the oil gas line and the electrolytic cell 1 can be prevented.
[0024]
The HF absorption tower 15 for removing HF in the fluorine gas discharged from the anode chamber 3 is provided with first absorption towers 15a and 15b in parallel as in the HF adsorption tower 14 described above. Then, the inside is filled with NaF, and HF contained in the released fluorine gas is removed. Similarly to the HF adsorption tower 14, the HF absorption tower 15 is preferably formed of a material having corrosion resistance to fluorine gas and HF. 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 the pressure maintaining means is provided. The gas generated from the anode chamber 3 becomes a severe environment in which HF gas and electrolytic bath droplets are generated simultaneously with the fluorine gas. In particular, in an environment where fluorine and HF are mixed, a strong oxidizing atmosphere is obtained. For this reason, 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 brought into a state of being opened and closed 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 so that clogging inside can be detected.
[0026]
In addition, it is preferable that the fluorine gas generator containing these electrolytic cells 1 is provided in the cabinet which consists of one housing | casing which is not shown in figure. This is because it becomes easy to use on demand and on site. The cabinet is preferably formed 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, it is preferable that storage means such as a buffer tank is provided on the downstream side from which high-purity fluorine gas is discharged. As a result, a necessary amount of fluorine gas can be provided when necessary, and an on-line fluorine gas generator that can be installed in a production line of a semiconductor production facility is obtained.
[0028]
Next, the operation of the fluorine gas generator according to this embodiment will be described.
[0029]
Usually, in a state where electrolysis is normally performed, the inside of the electrolytic cell 1 is maintained at atmospheric pressure, and the height of the electrolytic bath 2 in the anode chamber 3 and the cathode chamber 4 is the same liquid level. However, during electrolysis, for example, the fluorine gas line (gas line after the fluorine gas generation port 22) is blocked due to accumulation of droplets or the like in the electrolytic bath 2, or the hydrogen gas line (gas line after the hydrogen generation port 23) is blocked. Etc., the pressure in the electrolytic cell 1 fluctuates. 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 pressure gauges 7 and 8 are opened and closed according to the fluctuation of the pressure, The pressure in the electrolytic cell 1 is adjusted to be maintained at atmospheric pressure.
[0030]
Thus, when the pressure in the electrolytic cell 1 is maintained at atmospheric pressure by opening and closing the automatic valves 9 and 10, the height of the electrolytic bath 2 in the anode chamber 3 and the cathode chamber 4 in the electrolytic cell 1 is The liquid level is the same. However, during electrolysis, for example, droplets of the electrolytic bath 2 accumulate further, and the pressure in the electrolytic cell 1 cannot be maintained at atmospheric pressure by opening and closing the automatic valves 9 and 10. For example, a fluorine gas line (fluorine) The liquid surface height of the electrolytic bath 2 in the anode chamber 3 is increased by increasing the pressure in the anode chamber 3 due to blockage of the gas line after the gas generating port 22 or the like, or decreasing the pressure in the cathode chamber 4. May be lower than the liquid level of the electrolytic bath 2 in the cathode chamber 4. In this case, an abnormality in the liquid level is detected by 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.
[0031]
Usually, the liquid level of the electrolytic bath 2 when the pressure in the electrolytic cell 1 is kept at atmospheric pressure by opening and closing the automatic valves 9 and 10 and electrolysis is performed normally is the first liquid level detecting means 5 and Of the five liquid level sensors S1 to S5 of the second liquid level detection means 6, the liquid level sensors are located between the liquid level sensors S2 and S4. However, as described above, when the liquid surface height of the electrolytic bath 2 in the cathode chamber 4 is higher than the liquid surface height of the electrolytic bath in the anode chamber 3, that is, the liquid surface height of the cathode chamber 4 is second. When it becomes higher than the liquid level sensor S2 of the liquid level detecting means, the automatic valve 31 and the automatic valve 34 are closed. Thus, 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 valve 31 and the automatic valve 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 valve 33 and The automatic valve 32 is also closed and the electrolysis is interrupted.
[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 released from the fluorine gas generating 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 level height of the anode chamber 3 and the cathode chamber 4 of the electrolytic bath 2 returns to the same level, the electrolysis is resumed.
[0033]
As described above, the fluorine gas generator according to this 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 to these. Then, the liquid surface height of the electrolytic bath 2 is controlled while maintaining the inside of the electrolytic cell 1 at atmospheric pressure. Further, 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 these automatic valves 9 and 10, they are provided in the anode chamber 3 and the cathode chamber 4. The inside of the electrolytic cell 1 is maintained at atmospheric pressure by the first liquid level detection means 5 and the second liquid level detection means 6 and automatic valves 31 to 34 that open and close in conjunction with these. Thus, the inside of the electrolytic cell 1 can be maintained at atmospheric pressure by the two-stage control method, and the liquid level of the electrolytic bath 2 can be maintained at a stable height. As a result, it is not necessary to change the electrolysis conditions during electrolysis, and stable generation of fluorine gas can be performed.
[0034]
The fluorine gas generator according to the present invention is not limited to the above-described embodiment, and may be as follows, for example.
[0035]
For example, the electrolytic bath is electrolyzed using the electrolytic cell 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 using only one. It can also be done. Further, the position and number of 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, and the inside of the electrolytic cell is maintained at 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 becomes possible to always maintain the liquid level height 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 other gases such as rare gas into fluorine gas is provided, a mixed gas of rare gas and fluorine gas having a desired mixing ratio can be obtained, and semiconductor manufacturing such as a source for excimer laser oscillation 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 schematic view of an example of a liquid level detection 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]
DESCRIPTION OF SYMBOLS 1 Electrolysis tank 2 Electrolytic bath 3 Anode chamber 4 Cathode chamber 5 1st liquid level detection means 6 2nd liquid level detection 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 Bulkhead 17 Upper lid 18, 19 Gas line 20, 21 Purge gas inlet / outlet 22, 23 Gas generation port 24 HF supply line 25 HF inlet 26 Vacuum generator 27, 28 Gas line 29, 30 Pressure gauges 31-34 Automatic valve 35 -38 Manual valve 39-41 Flow meter 42 Compressor unit S1-S5 Liquid level sensor

Claims (5)

A fluorine gas generator for electrolyzing an electrolytic bath made of a mixed molten salt containing hydrogen fluoride to produce high purity fluorine gas,
An electrolytic cell separated into an anode chamber provided with an anode by a partition wall and a cathode chamber provided with a cathode;
Pressure maintaining means for maintaining the anode chamber and the cathode chamber at atmospheric pressure;
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 five or more stages,
Predetermined before the liquid level detecting means becomes abnormal between the average liquid level and the highest abnormal liquid level and between the average liquid level and the lowest abnormal liquid level. It can detect the liquid level of
Said pressure maintenance means, and open and close in conjunction with the anode chamber and a pressure gauge wherein the respectively provided in the cathode chamber, an automatic pressure gauge which can be evacuated or shut off gas generated from said cathode compartment and said anode compartment A valve, a path connected to the cathode chamber for discharging the gas in the cathode chamber, and having a first interlocking automatic valve that opens and closes in conjunction with the liquid level detection means; and discharges the gas in the anode chamber For connecting to the anode chamber and having a second interlocking automatic valve that opens and closes in conjunction with the liquid level detection means, and to the cathode chamber for supplying purge gas, A path having a third interlocking automatic valve that opens and closes in conjunction, and a path having a fourth interlocking automatic valve that is connected to the anode chamber for supplying purge gas and opens and closes in conjunction with the liquid level detection means Have
When the liquid level detection means in the cathode chamber detects a predetermined liquid level before an abnormality occurs between the average liquid level and the highest abnormal liquid level, the first interlocking is performed. An automatic valve is closed to shut off the gas exhausted from the cathode chamber, and the fourth interlocking automatic valve is closed to shut off the purge gas supplied to the anode chamber;
When the liquid level detecting means in the cathode chamber detects the uppermost abnormal liquid level, the second interlocking automatic valve is closed to shut off the gas generated in the anode chamber. And a fluorine gas generator in which the third interlocking automatic valve is closed to shut off the purge gas supplied to the cathode chamber .   The automatic valve that opens and closes in conjunction with a pressure gauge that is one of pressure maintaining means for maintaining the pressure in the electrolytic cell at atmospheric pressure opens when the pressure in the electrolytic cell becomes higher than atmospheric pressure, and the electrolytic cell The fluorine gas generator according to claim 1, wherein the gas inside is discharged.   At least one of a compressor and a vacuum generator is provided behind the automatic valve that opens and closes in conjunction with the pressure gauge, and a gas discharge line downstream of the automatic valve that opens and closes in conjunction with the pressure gauge The fluorine gas generator according to claim 1 or 2, wherein the pressure is maintained in a reduced pressure state.   The fluorine gas generator according to claim 1, wherein the liquid level detection means is constituted by five or more liquid level sensors capable of detecting each liquid level of the electrolytic bath.   The fluorine gas generator according to any one of claims 1 to 4, further comprising a pressure gauge that has the liquid level detection means and can detect the pressure in the electrolytic cell.

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