JP5659449B2 - Fluorine gas generation method - Google Patents

Description

This invention relates to the fluorine gas generation method.

  Some conventional fluorine gas generators generate fluorine gas by a so-called medium temperature method (see, for example, Patent Document 1). In this fluorine gas generator, a partition for separating the inside of the electrolytic cell into an anode chamber and a cathode chamber is provided in the electrolytic cell, an anode is provided in the anode chamber, and a cathode is provided in the cathode chamber.

When an electrolysis voltage is applied between the anode and the cathode, the mixed molten salt (KF · 2HF) contained in the electrolytic bath and heated to about 90 ° C. HF is electrolyzed, F ₂ gas is generated in the anode chamber, and H ₂ gas is generated in the cathode chamber. Of these, F ₂ gas is used industrially, and H ₂ gas is released into the atmosphere.

Japanese Patent Laid-Open No. 11-106979 (FIG. 12)

By the way, in the fluorine gas generator as described above, maintenance is periodically performed for replacement of parts such as an anode, a cathode, and other packings. In such a case, first, voltage application and heating to the operating apparatus are stopped. Next, an inert gas such as N ₂ gas is supplied into the anode chamber, the F ₂ gas remaining in the supplied inert gas is discharged, and replacement with F ₂ gas is performed. In this state, maintenance is performed. When the maintenance is completed, heating and voltage application are resumed for the stopped apparatus. Then, by this restart, the inert gas remaining in the F ₂ gas generated in the anode chamber is discharged and replaced with the inert gas. Hereinafter, a normal operating state is obtained.

However, in the above conventional maintenance method, it takes several tens of hours to replace the F ₂ gas generated in the anode chamber by resuming with the remaining inert gas after the maintenance is completed. There was a problem that it took a considerable time to resume normal operation. In addition, since the initial F ₂ gas generated in the anode chamber due to resumption is low in F ₂ concentration and cannot be used, this generated F ₂ gas must be discarded, and the raw material HF is wasted to some extent. There was also a problem of end.

Accordingly, an object of the present invention is to provide a fluorine gas generation method capable of shortening the time from the end of maintenance to resuming normal operation and capable of effectively using raw material HF. .

The fluorine gas generation method according to the present invention applies an electrolysis voltage between an anode and a cathode in an electrolytic cell having an anode chamber and a cathode chamber and containing KF · 2HF of a mixed molten salt, and in the electrolytic cell. The KF · 2HF is heated to operate a fluorine gas generator, and the KF · 2HF contained in the electrolytic cell is electrolyzed, whereby fluorine gas is introduced into the anode chamber and hydrogen is introduced into the cathode chamber. In the fluorine gas generation method for generating gas, an HF removal unit is formed from a mixed gas of hydrogen gas and HF gas generated in the cathode chamber when the KF · 2HF accommodated in the electrolytic cell is electrolyzed. Through the process of releasing only hydrogen gas into the atmosphere, and after stopping the operation of the electrolytic cell, after exhausting the fluorine gas in the electrolytic cell, introducing an inert gas into the electrolytic cell, Atmosphere in the electrolytic cell After replacing the atmosphere with an inert gas and performing maintenance in the electrolytic cell, the inert gas is exhausted, and then the fluorine gas stored in advance is introduced to change the atmosphere in the electrolytic cell. Fluorine gas remaining in the anode chamber and HF after exhausting the fluorine gas in the electrolytic cell, including the step of replacing with fluorine gas and the step of operating the electrolytic cell after replacing with fluorine gas A step of releasing a mixed gas with the gas into the atmosphere through the HF removal section; and after exhausting the inert gas, the inert gas remaining in the anode chamber is further removed through the HF removal section. It further includes at least one of steps for releasing into the atmosphere.
Preferably, in the invention according to claim 1, a partition for separating the inside of the electrolytic cell into an anode chamber and a cathode chamber is provided in the electrolytic cell, and the anode provided in the anode chamber and the By applying an electrolysis voltage to the cathode provided in the cathode chamber, HF of KF · 2HF contained in the electrolytic cell and made liquid by heating is electrolyzed, thereby Fluorine gas is generated in the anode chamber, and hydrogen gas is generated in the cathode chamber.
Preferably, in the invention described in claim 1, the fluorine gas generated in the anode chamber is supplied into the fluorine gas tank by driving the compressor.
Preferably, in the invention according to claim 3 , the voltage application to the anode and the cathode is stopped, the heating is stopped, and the KF · 2HF made liquid by heating is solidified by a natural decrease in the temperature. Then, the fluorine gas remaining in the anode chamber is discharged, the inert gas is supplied into the anode chamber, maintenance is performed in this state, and when the maintenance is completed, the inert gas remaining in the anode chamber is The compressed fluorine gas in the fluorine gas tank is supplied into the anode chamber, the solidified KF · 2HF is liquefied by heating, and then an electrolytic voltage is applied between the anode and the cathode.
Preferably, in the invention described in claim 3, the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is discharged by driving the compressor.
Preferably, in the invention according to claim 5, the discharge of the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is performed by the discharge and the supply of the inert gas or the compressed fluorine gas. Repeat several times.
Preferably, in the invention described in claim 1, the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is discharged by driving a vacuum pump.

According to the present invention, after the maintenance of the electrolytic cell, after exhausting the inert gas, the atmosphere was the previously pooled in advance fluorine gas is introduced in the electrolytic cell to the fluorine gas, the fluorine After replacing the gas, the electrolytic cell is operated, so that normal operation can be resumed immediately after maintenance inside the electrolytic cell. Therefore, from the end of maintenance until normal operation is resumed. The time can be shortened, and the raw material HF can be used effectively.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a fluorine gas generator as a first embodiment of the present invention. The fluorine gas generator includes an electrolytic cell 1. A lid 2 is provided on the upper side of the electrolytic cell 1. A partition wall 5 for separating the inside of the electrolytic cell 1 into an anode chamber 3 and a cathode chamber 4 is provided at a portion other than the lower portion in the central portion of the electrolytic cell 1. An anode 6 is provided in the anode chamber 3, and a cathode 7 is provided in the cathode chamber 4. Each upper part of the anode 6 and the cathode 7 passes through the lid 2 and protrudes above the lid 2.

  A mixed molten salt KF · 2HF8 is accommodated on the lower side of the electrolytic cell 1 except for the upper part. A heating means (not shown) such as a heater is provided on the outer periphery of the electrolytic cell 1. When the temperature in the electrolytic cell 1 becomes about 90 ° C. higher than the melting point of 71.7 ° C. of KF · 2HF8 due to heating by the heating means, KF · 2HF8 becomes liquid and when heating by the heating means is stopped, Liquid KF · 2HF is solidified by a natural drop in its temperature. In this case, the upper part of the anode chamber 3 and the cathode chamber 4 is a space whether the KF · 2HF 8 is in a liquid state or in a solidified state.

  An HF gas supply pipe 11 is inserted into a predetermined portion of the lid 2 on the cathode chamber 4. One end of the HF gas supply pipe 11 is positioned in KF · 2HF 8 accommodated in the electrolytic cell 1. An HF gas supply electromagnetic valve 12 is provided in the middle of the HF gas supply pipe 11. An HF gas supply source 13 is connected to the other end of the HF gas supply pipe 11.

An H ₂ gas discharge pipe 14 is inserted into another predetermined portion of the lid 2 on the cathode chamber 4. One end of the H ₂ gas discharge pipe 14 communicates with the upper space of the cathode chamber 4. In the middle of the H ₂ gas exhaust pipe 14 is H ₂ gas discharge solenoid valve 15 is provided. One end of the HF gas removal cylinder 16 is connected to the other end of the H ₂ gas discharge pipe 14. An HF adsorbent made of NaF or the like is accommodated in the HF gas removal cylinder 16. The other end of the HF gas removal cylinder 16 is open to the atmosphere.

An N ₂ gas supply pipe 21 is inserted through a predetermined portion of the lid 2 on the anode chamber 3. One end of the N ₂ gas supply pipe 21 communicates with the upper space of the anode chamber 3. In the middle of the N ₂ gas supply pipe 21 is N ₂ gas supplying solenoid valve 22 is provided. The other end of the N ₂ gas supply pipe 21 N ₂ gas supply source 23 is connected.

  A common pipe 24 is inserted into another predetermined portion of the lid 2 on the anode chamber 3. One end of the common pipe 24 communicates with the upper space of the anode chamber 3. A compressor 25 is provided in the middle of the common pipe 24. One end of each of the first and second pipes 26 and 27 is connected to the other end of the common pipe 24.

A first electromagnetic valve 28 is provided in the middle of the first pipe 26. One end of an HF gas removal cylinder 29 is connected to the other end of the first pipe 26. An HF adsorbent made of NaF or the like is accommodated in the HF gas removal cylinder 29. The other end portion of the HF gas removal cylinder 29 is connected to one end portion of an F ₂ gas tank 31 through a pipe 30.

One end of an F ₂ gas supply pipe 32 is connected to the other end of the F ₂ gas tank 31. In the middle of the F ₂ gas supply pipe 32 is F ₂ gas supplying solenoid valve 33 is provided. The other end portion of the F ₂ gas supply pipe 32 is not shown, it is supplied with compressed F ₂ gas from the F ₂ gas tank 31, is connected to a device for industrial use an F ₂ gas.

A second electromagnetic valve 34 is provided in the middle of the second pipe 27. The other end of the second pipe 27 is connected to a predetermined portion of the H ₂ gas exhaust pipe 14 between the H ₂ gas discharge solenoid valve 15 and the HF gas removal tube 16.

Next, normal operation of the fluorine gas generator configured as described above will be described. Now, the H ₂ gas discharge solenoid valve 15 and the first solenoid valve 28 are in an open state, and the HF gas supply solenoid valve 12, the N ₂ gas supply solenoid valve 22, the second solenoid valve 34, and the F ₂ valve. It is assumed that the gas supply solenoid valve 33 is in a closed state. Further, it is assumed that the compressor 25 is in a driving state.

When the temperature in the electrolytic cell 1 is maintained at about 90 ° C., which is higher than the melting point of 71.7 ° C. of KF · 2HF8, by heating with heating means, KF · 2HF8 becomes liquid. In this state, when an electrolysis voltage is applied between the anode 6 and the cathode 7, HF of the liquid KF · 2HF 8 is electrolyzed, and a mixed gas of F ₂ gas and HF gas is contained in the anode chamber 3. And a mixed gas of H ₂ gas and HF gas is generated in the cathode chamber 4.

The mixed gas of F ₂ gas and HF gas generated in the anode chamber 3 is driven by the compressor 25 through the common pipe 24, the compressor 25, the first pipe 26, and the opened first electromagnetic valve 28. To the HF gas removal cylinder 29. In HF gas removal tube 29, the HF gas was removed from the mixed gas of supplied F ₂ gas and HF gas is supplied to the F ₂ gas tank 31 only F ₂ gas through a pipe 30. Thus, the inside F ₂ gas tank 31 F ₂ gas compressed by driving the compressor 25 is temporarily stored.

Then, when the F ₂ gas supply electromagnetic valve 33 in the closed state is opened, the compressed F ₂ gas temporarily stored in the F ₂ gas tank 31 is predetermined through the F ₂ gas supply pipe 33. Supplied to the equipment and used industrially.

On the other hand, the mixed gas of H ₂ gas and HF gas generated in the cathode chamber 4 is supplied to the HF gas removal cylinder 16 through the H ₂ gas discharge pipe 14 and the open H ₂ gas discharge electromagnetic valve 15. Is done. The HF gas removal cylinder 16 removes the HF gas from the supplied mixed gas of H ₂ gas and HF gas, and releases only the H ₂ gas into the atmosphere.

  In the normal operation as described above, when the HF concentration of the liquid KF · 2HF8 in the electrolytic cell 1 is lowered to some extent, when the HF gas supply electromagnetic valve 12 in the closed state is opened, HF gas is supplied from the HF gas supply source 13 into the liquid KF · 2HF 8 in the electrolytic cell 1 through the HF gas supply pipe 11 and the opened HF gas supply electromagnetic valve 12. Thereby, the normal operation as described above is continued.

Next, a case where maintenance is performed after stopping the normal operation as described above will be described. In this case, first, when voltage application to the anode 6 and the cathode 7 is stopped, generation of F ₂ gas and H ₂ gas is stopped. When heating by the heating means is stopped, liquid KF · 2HF solidifies due to a natural drop in temperature. Further, the first electromagnetic valve 28 in the opened state is closed, and the second electromagnetic valve 34 in the closed state is opened. Further, the H ₂ gas discharge electromagnetic valve 15 in the open state is closed.

Here, the compressor 25 may be temporarily stopped and re-driven, or the driving during normal operation may be continued as it is. In any case, the mixed gas of the F ₂ gas and the HF gas remaining in the anode chamber 3 by driving the compressor 25 is in the common pipe 24, the compressor 25, the second pipe 27, and the valve open state. It is supplied to the HF gas removal cylinder 16 via the second electromagnetic valve 34 and the H ₂ gas discharge pipe 14. The HF gas removal cylinder 16 removes the HF gas from the supplied mixed gas of F ₂ gas and HF gas, and releases only the F ₂ gas into the atmosphere.

Next, the drive of the compressor 25 is stopped. Next, the N ₂ gas supply electromagnetic valve 22 in the closed state is opened. Then, N ₂ gas (inert gas) from the N ₂ gas supply source 23 is supplied to the anode chamber 3 through the N ₂ gas supply solenoid valve 22 in the N ₂ gas supply line 21 and the open state, the anode The chamber 3 is filled with N ₂ gas at atmospheric pressure. Next, the N ₂ gas supply electromagnetic valve 22 in the valve open state is closed. In this state, maintenance is performed.

When the maintenance is completed, the compressor 25 is then driven. Then, the N ₂ gas remaining in the anode chamber 3 is the common pipe 24, the compressor 25, the second pipe 27, the second electromagnetic valve 34 in the valve open state, the H ₂ gas discharge pipe 14 and the HF gas. It is discharged into the atmosphere through the removal cylinder 16. Next, the drive of the compressor 25 is stopped.

Next, the second electromagnetic valve 34 in the opened state is closed, and the first electromagnetic valve 28 in the closed state is opened. Then, the compressed F ₂ gas in the F ₂ gas tank 31 is supplied from the pipe 30, the HF gas removal cylinder 29, the first pipe 26, the opened first electromagnetic valve 28, the stopped compressor 25 and the common pipe 24. Is supplied into the anode chamber 3 and the anode chamber 3 is filled with F ₂ gas at atmospheric pressure.

Next, when the temperature inside the electrolytic cell 1 is maintained at about 90 ° C., which is higher than the melting point of 71.7 ° C. of KF · 2HF8, by heating with heating means, the solidified KF · 2HF8 becomes liquid. Next, the H ₂ gas discharge solenoid valve 15 in the closed state is opened. Next, when an electrolytic voltage is applied between the anode 6 and the cathode 7, the normal operation is resumed.

As described above, in this fluorine gas generator, the compressed F ₂ gas in the F ₂ gas tank 31 is supplied into the anode chamber 3 after the maintenance is completed, so that an electrolytic voltage is applied between the anode 6 and the cathode 7. When the voltage is applied, the normal operation can be resumed immediately, and therefore the time from the end of maintenance to the resumption of normal operation can be shortened. Further, the raw material HF can be used effectively without wastefully discarding the F ₂ gas when the normal operation is resumed.

By the way, the compressor 25 cannot perform high vacuum evacuation in terms of performance, and the gas concentration to be discharged from the anode chamber 3 cannot be lowered sufficiently. Therefore, when the mixed gas of F ₂ gas and HF gas or N ₂ gas remaining in the anode chamber 3 is discharged, the discharge and supply of N ₂ gas or compressed F ₂ gas are repeated several times. The gas concentration to be discharged from the anode chamber 3 can be sufficiently reduced. However, in such a method, since gas discharge and gas supply are repeated several times, it takes some time. Then, next, an embodiment that can further reduce the time will be described.

(Second Embodiment)
FIG. 2 shows a schematic configuration diagram of a fluorine gas generator as a second embodiment of the present invention. This fluorine gas generator differs from the fluorine gas generator shown in FIG. 1 in that a vacuum pump 35 is provided in the middle of the second pipe 27 between the second electromagnetic valve 34 and the HF gas removal cylinder 16. Is a point. Then, by driving the vacuum pump 35, the mixed gas of the F ₂ gas and the HF gas remaining in the anode chamber 3 or the N ₂ gas is discharged. Since the vacuum pump 35 can perform high vacuum evacuation in a relatively short time, the time can be further reduced.

(Third embodiment)
FIG. 3 shows a schematic configuration diagram of a fluorine gas generator as a third embodiment of the present invention. This fluorine gas generator differs from the fluorine gas generator shown in FIG. 2 in that the compressor 25 is provided in the middle of the first pipe 26 between the common pipe 24 and the first electromagnetic valve 28. is there. In this case, the compressor 25 can be prevented from getting in the way when the vacuum pump 35 is driven.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the fluorine gas generator as 1st Embodiment of this invention. The schematic block diagram of the fluorine gas generator as 2nd Embodiment of this invention. The schematic block diagram of the fluorine gas generator as 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolytic cell 2 Lid 3 Anode chamber 4 Cathode chamber 5 Partition 6 Anode 7 Cathode 8 KF / 2HF
11 HF gas supply pipe 12 HF gas supply solenoid valve 13 HF gas supply source 14 H ₂ gas discharge pipe 15 H ₂ gas discharge solenoid valve 16 HF gas removal cylinder 21 N ₂ gas supply pipe 22 N ₂ gas supply solenoid valve 23 N ₂ gas supply source 24 Common pipe 25 Compressor 26 First pipe 27 Second pipe 28 First solenoid valve 29 HF gas removal cylinder 30 Pipe 31 F ₂ gas tank 32 F ₂ gas supply pipe 33 For F ₂ gas supply Solenoid valve 34 Second solenoid valve 35 Vacuum pump

Claims (7)

An electrolytic voltage is applied between an anode and a cathode in an electrolytic cell having an anode chamber and a cathode chamber and containing mixed molten salt KF · 2HF, and the KF · 2HF in the electrolytic cell is heated to form fluorine. In a fluorine gas generation method of operating a gas generator to electrolyze the KF · 2HF accommodated in the electrolytic cell, thereby generating fluorine gas in the anode chamber and hydrogen gas in the cathode chamber,
When the KF · 2HF contained in the electrolytic cell is electrolyzed, only hydrogen gas is released into the atmosphere from the mixed gas of hydrogen gas and HF gas generated in the cathode chamber through the HF removal section. And a process of
After the operation of the electrolytic cell is stopped, the fluorine gas in the electrolytic cell is exhausted, an inert gas is introduced into the electrolytic cell, and the atmosphere in the electrolytic cell is replaced with an inert gas; , After performing maintenance in the electrolytic cell, exhausting the inert gas, introducing a pre-stored fluorine gas to replace the atmosphere in the electrolytic cell with fluorine gas, and fluorine gas After replacing, the step of operating the electrolytic cell;
After exhausting the fluorine gas in the electrolytic cell, and further releasing the mixed gas of fluorine gas and HF gas remaining in the anode chamber into the atmosphere through the HF removal section; A method for generating fluorine gas, further comprising at least one of a step of releasing the inert gas remaining in the anode chamber into the atmosphere through the HF removal section after exhausting the active gas .   In the invention according to claim 1, a partition for separating the inside of the electrolytic cell into an anode chamber and a cathode chamber is provided in the electrolytic cell, and the anode provided in the anode chamber and the cathode chamber are provided in the electrolytic cell. By applying an electrolysis voltage to the provided cathode, HF of KF · 2HF housed in the electrolytic cell and made liquid by heating is electrolyzed, and thereby the anode chamber A fluorine gas is generated, and hydrogen gas is generated in the cathode chamber.   2. The fluorine gas generation method according to claim 1, wherein the fluorine gas generated in the anode chamber is supplied into a fluorine gas tank by driving a compressor. In the invention according to claim 3 , the voltage application to the anode and the cathode is stopped, the heating is stopped, and the KF · 2HF made liquid by heating is solidified by a natural decrease in the temperature,
Next, the fluorine gas remaining in the anode chamber is discharged, an inert gas is supplied into the anode chamber, maintenance is performed in this state, and when the maintenance is completed, the inert gas remaining in the anode chamber is removed. The compressed fluorine gas in the fluorine gas tank is discharged, supplied into the anode chamber, the solidified KF · 2HF is liquefied by heating, and then an electrolytic voltage is applied between the anode and the cathode. Fluorine gas generation method. 4. The fluorine gas generation method according to claim 3 , wherein the discharge of the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is performed by driving the compressor. In the invention according to claim 5, the discharge of the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is a number of the discharge and the supply of the inert gas or the compressed fluorine gas. A method for generating fluorine gas, which is repeated once. 2. The fluorine gas generation method according to claim 1, wherein the fluorine gas remaining in the anode chamber or the inert gas remaining in the anode chamber is discharged by driving a vacuum pump.

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