TWI755972B - Fluorine gas production method and fluorine gas production device - Google Patents

Abstract

Provided is a method for producing fluorine gas capable of suppressing clogging of pipes and valves caused by mist. Through the electrolysis process that performs electrolysis of the electrolyte solution in the electrolytic cell, the moisture concentration measurement process that measures the moisture concentration in the electrolytic solution during electrolysis, and the electrolysis of the electrolytic solution, it will be generated inside the electrolytic cell. Fluorine gas is produced by the method of the gas supply process which is transported from the inside of the electrolytic cell to the external flow channel of the fluid. During the air supply process, switch the flow path of the flowing fluid according to the water concentration in the electrolyte measured by the water concentration measurement process, and when the water concentration in the electrolyte measured by the water concentration measurement process is below the preset reference value, at When the first flow channel that transports fluid from the inside of the electrolytic cell to the first outside, the fluid is transported, and when the fluid is larger than the preset reference value, the second flow channel that transports the fluid from the inside of the electrolytic cell to the second outside is transported. For the fluid, the preset reference value is a value within the range of 0.1% by mass to 0.8% by mass.

Description

Fluorine gas production method and fluorine gas production device

The present invention relates to a method for producing fluorine gas and an apparatus for producing fluorine gas.

Fluorine gas can be synthesized (electrolytic synthesis) by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride. The fluorine gas sent from the electrolytic cell is mixed with the mist because the fluorine gas also generates mist (for example, the mist of the electrolyte solution) through the electrolysis of the electrolyte solution. The mist mixed with the fluorine gas becomes a powder, and there is a concern that the piping or valve used for the gas supply of the fluorine gas may be blocked. For this reason, the operation of producing fluorine gas may have to be interrupted or stopped, resulting in an obstacle to the continuous operation of the production of fluorine gas formed by electrolysis. In order to suppress the clogging of pipes and valves due to mist, Patent Document 1 discloses a technique of heating fluorine gas mixed with mist or pipes through which the gas passes, to a temperature equal to or higher than the melting point of an electrolyte solution. In addition, Patent Document 2 discloses a gas generating device having a gas diffusion unit having a space for roughening mist, and a filler accommodating unit for accommodating a filler for adsorbing mist. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 5584904 [Patent Document 2] Japanese Patent Publication No. 5919824

[The problem to be solved by the invention]

However, a technique for more effectively suppressing blockage of pipes and valves due to mist has been desired. It is an object of the present invention to provide a method for producing a fluorine gas and an apparatus for producing a fluorine gas which can suppress the clogging of pipes and valves by mist. [Means for solving problems]

In order to solve the aforementioned problems, one aspect of the present invention is as follows [1] to [5]. [1] In a method for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride to produce fluorine gas, Equipped with: In the electrolytic cell, the electrolysis process of the aforementioned electrolysis is carried out, and the water concentration measurement process for measuring the water concentration in the electrolyte solution during the above electrolysis, And during the electrolysis of the aforementioned electrolyte, the fluid generated inside the aforementioned electrolytic cell is transported from the inside of the aforementioned electrolytic cell to the external flow channel through the air supply process; In the above-mentioned air supply process, the flow channel for flowing the fluid is switched according to the water concentration in the electrolyte solution measured by the water concentration measurement process, and the water concentration in the electrolyte solution measured by the water concentration measurement process is a preset reference. When the value is less than or equal to the above-mentioned preset reference value, the first flow channel that transports the fluid from the inside of the electrolytic cell to the first outside, and when the fluid is transported, is larger than the predetermined reference value, from the inside of the electrolytic cell to the first flow path. 2. The second flow channel for externally transporting the aforementioned fluid, which transports the aforementioned fluid, The aforementioned predetermined reference value is a method for producing a fluorine gas having a numerical value within a range of 0.1 mass % or more and 0.8 mass % or less.

[2] The method for producing the fluorine gas described in [1] in which the metal fluoride is a fluoride of at least one metal selected from potassium, cesium, rubidium, and lithium. [3] The anode used in the aforementioned electrolysis is a carbonaceous electrode formed of at least one carbon material selected from diamond, diamond-like carbon, amorphous carbon, graphite, and glassy carbon. Described in [1] or [2] ] The production method of fluorine gas. [4] The bubbles generated by the anode or cathode used in the aforementioned electrolysis in the aforementioned electrolytic cell are described in [1]~[ 3] The production method of fluorine gas of any one.

[5] In a fluorine gas production device for electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride to produce fluorine gas, Equipped with: an electrolytic cell for accommodating the above-mentioned electrolytic solution and performing the above-mentioned electrolysis, and a water concentration measuring unit for measuring the water concentration in the electrolyte solution in the electrolytic cell during the above electrolysis, And during the electrolysis of the aforementioned electrolyte, the fluid generated inside the aforementioned electrolytic cell is transported from the inside of the aforementioned electrolytic cell to the outside; The flow channel has a first flow channel for transporting the fluid from the inside of the electrolytic cell to the first outside, and a second flow channel for transporting the fluid from the inside of the electrolytic cell to the second outside. The water concentration in the electrolytic solution measured by the water concentration measuring section switches the flow channel through which the fluid flows to the first flow channel or the flow channel switching section of the second flow channel. When the water concentration in the electrolytic solution measured by the water concentration measuring part is below a preset reference value, the flow channel switching unit sends the fluid from the inside of the electrolytic cell to the first flow channel, and compares the flow. When the preset reference value is large, the fluid is transported from the inside of the electrolytic cell to the second flow passage, The above-mentioned preset reference value is a fluorine gas production apparatus with a numerical value within the range of 0.1 mass % or more and 0.8 mass % or less. [Inventive effect]

According to the present invention, when the electrolytic solution containing hydrogen fluoride and metal fluoride is electrolyzed to produce fluorine gas, it is possible to suppress the clogging of pipes and valves caused by mist.

An embodiment of the present invention will be described as follows. However, this embodiment shows an example of embodiment, but this invention is not limited to this embodiment. In addition, in this embodiment, various changes or improvements can be added, and the form which added these changes or improvements is also included in this invention. The inventors of the present invention conducted an in-depth examination of the mist that causes the blockage of pipes and valves in the electrolytic synthesis of fluorine gas. The "mist" in the present invention refers to the liquid microparticles or solid microparticles generated when the electrolytic cell generates fluorine gas through the electrolysis of the electrolyte. Specifically, it refers to the reaction between the microparticles of the electrolyte solution, the microparticles of the solid state of the phase change of the microparticles of the electrolyte solution, and the components constituting the electrolytic cell (metal forming the electrolytic cell, gaskets for the electrolytic cell, carbon electrodes, etc.) and fluorine gas. The fine particles of the solid produced.

The inventors of the present invention measured the average particle size of the mist contained in the fluid generated inside the electrolytic cell during electrolysis of the electrolyte solution, and confirmed that the average particle size of the mist changes over time. In addition, through the results of in-depth review, it was found that there is a correlation between the average particle size of the mist and the moisture concentration in the electrolyte during electrolysis, and it was found that the average particle size of the mist and the occlusion of the pipes or valves that transport the fluid are prone to occur. There is a correlation between sex. Then, it was found that according to the water concentration in the electrolyte during electrolysis, the flow path of the fluid generated inside the electrolytic cell was improved, and the blockage of pipes or valves was suppressed, and the frequency of interruption or stop of the operation of producing fluorine gas was reduced, so as to complete the present invention. An embodiment of the present invention will be described as follows.

The method for producing fluorine gas according to the present embodiment is a method for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride to produce fluorine gas. The water concentration measurement process of the water concentration in the electrolytic solution, and the gas supply process that transfers the fluid generated inside the electrolytic cell through the flow channel from the inside of the electrolytic cell to the outside during the electrolysis of the electrolytic solution.

In the air supply process, the flow path of the flowing fluid is switched according to the water concentration in the electrolyte solution measured by the water concentration measurement process. That is, when the water concentration in the electrolytic solution measured by the water concentration measurement process is below the preset reference value, the first flow path for transferring the fluid from the inside of the electrolytic cell to the first outside transfers the fluid more than the predetermined value. When the set reference value is large, the fluid is conveyed in the second flow passage that conveys the fluid from the inside of the electrolytic cell to the second outside. Then, the preset reference value is a numerical value within the range of 0.1 mass % or more and 0.8 mass % or less.

In addition, the fluorine gas manufacturing apparatus of the present embodiment electrolyzes an electrolytic solution containing hydrogen fluoride and metal fluoride to produce fluorine gas. Moisture concentration measuring part for measuring the water concentration in the electrolytic solution in the electrolytic cell, and a flow channel for transporting the fluid generated inside the electrolytic cell from the inside of the electrolytic cell to the outside during the electrolysis of the electrolytic solution.

The flow path includes a first flow path for conveying fluid from the inside of the electrolytic cell to the first outside, and a second flow path for conveying the fluid from the inside of the electrolytic cell to the second outside. In addition, the flow path has a flow path switching portion that switches the flow path of the flowing fluid to the first flow path or the second flow path according to the moisture concentration in the electrolyte solution measured by the moisture concentration measuring portion. When the water concentration in the electrolyte measured by the water concentration measuring part is below the preset reference value, the flow channel switching part sends the fluid from the inside of the electrolytic cell to the first flow channel, which is higher than the preset reference value. When it is large, the fluid is sent from the inside of the electrolytic cell to the second channel. Then, the preset reference value is a numerical value within the range of 0.1 mass % or more and 0.8 mass % or less.

In the method for producing fluorine gas and the apparatus for producing fluorine gas according to the present embodiment, the flow path of the flowing fluid is switched to the first flow path or the second flow path according to the water concentration in the electrolyte during electrolysis. As a result, the flow path is switched to the first flow path or the second flow path according to the average particle diameter of the mist, and the flow path blockage due to the mist is less likely to occur. Therefore, the method for producing fluorine gas and the apparatus for producing fluorine gas according to the present embodiment electrolyze an electrolyte solution containing hydrogen fluoride and metal fluoride, and when producing fluorine gas, it is possible to suppress the clogging of pipes and valves caused by mist. Therefore, the frequency of interruption or stoppage of the fluorine gas production operation can be reduced, and continuous operation can be easily performed. For this reason, fluorine gas can be produced economically.

However, in the method for producing fluorine gas and the apparatus for producing fluorine gas in the present embodiment, the measurement of the water concentration in the electrolyte may be performed for the electrolyte in the anode chamber equipped with the anode, and the measurement of the water concentration in the cathode chamber equipped with the cathode may be performed for the electrolyte solution in the anode chamber equipped with the anode. Electrolyte can also be carried out. In addition, the measurement of the water concentration in the electrolyte solution may be performed frequently during electrolysis, periodically at regular intervals, or at any time from time to time. Furthermore, although the first flow passage and the second flow passage are separate flow passages, the first exterior and the second exterior may be in separate locations or may be the same location.

Here, an example of a fluorine gas production method and a fluorine gas production apparatus according to the present embodiment are shown. The first flow channel is a flow channel for conveying the fluid through the mist removing part that removes the mist from the fluid from the inside of the electrolytic cell, and the fluorine gas extracting part that extracts the fluorine gas from the fluid. The second flow channel is a flow channel for conveying fluid from the inside of the electrolytic cell to the fluorine gas extraction section without passing through the mist removal section. That is, when the water concentration in the electrolyte solution is below the preset reference value, the fluid is sent to the mist removing part provided in the first flow path, and when it is larger than the preset reference value, the fluid system does not send the mist to the mist. Remove department. In this example, the fluorine gas extraction part corresponds to the first outer part and the second outer part. Although the first outer part and the second outer part are the same place, the first outer part and the second outer part may be different places.

Then, the second flow path has a blockage suppressing mechanism for suppressing blockage of the second flow path due to mist. The blockage suppressing means is not particularly limited as long as it can suppress blockage of the second flow passage by mist, but for example, the following may be mentioned. That is, a large-diameter piping, an inclined piping, a rotary screw, and an air flow generating device can be exemplified, and these can be combined and used. Specifically, by configuring at least a part of the second flow passage through a pipe having a larger diameter than that of the first flow passage, the blockage of the second flow passage due to mist can be suppressed. In addition, by forming at least a part of the second flow passage through a pipe which is inclined with respect to the horizontal direction and extends in a direction descending from the upstream side to the downstream side, the blockage of the second flow passage by the mist can be suppressed.

Furthermore, the mist accumulated in the second flow path can be prevented from being blocked by the rotary screw which transports the mist accumulated in the second flow path to the upstream side or the downstream side, and is installed inside the second flow path. Furthermore, by disposing an air flow generating device in the second flow passage that circulates an air flow that increases the flow velocity of the fluid flowing in the second flow passage, the occlusion of the second flow passage by mist can be suppressed. However, a mist removing portion different from the mist removing portion provided in the first flow passage may be provided in the second flow passage as the clogging suppressing means.

Since the first flow channel removes the mist from the fluid through the mist removing part, the occlusion caused by the mist is less likely to occur, and the second flow channel is provided with the clogging suppressing mechanism, so that the occlusion caused by the mist is less likely to occur. Therefore, the method for producing fluorine gas and the apparatus for producing fluorine gas according to the present embodiment electrolyze an electrolyte solution containing hydrogen fluoride and metal fluoride, and when producing fluorine gas, it is possible to suppress the clogging of pipes and valves caused by mist. However, even if it does not have the mist removing part or the blockage suppressing mechanism, the function of suppressing the piping or valve caused by mist can be exerted only by switching the flow path of the flowing fluid to another flow path (the first flow path or the second flow path). The effect of blocking is excellent in the above-mentioned effect if the mist removing portion or blocking suppressing mechanism is provided.

Hereinafter, the method for producing fluorine gas and the apparatus for producing fluorine gas according to the present embodiment will be described in more detail. [electrolyzer] The form of the electrolytic cell is not particularly limited, and any electrolytic cell can be used as long as it can electrolyze an electrolyte solution containing hydrogen fluoride and metal fluoride to generate fluorine gas. Usually, the interior of the electrolytic cell is divided into an anode chamber equipped with an anode and a cathode chamber equipped with a cathode through a partition member such as a partition wall, so that the fluorine gas generated by the anode and the hydrogen gas generated by the cathode are not mixed.

As the anode, for example, a carbonaceous electrode formed of a carbon material such as diamond, diamond-like carbon, amorphous carbon, graphite, glassy carbon, and amorphous carbon can be used. Moreover, as an anode, in addition to the above-mentioned carbon material, for example, a metal electrode formed of a metal such as nickel and Monel (trademark) can be used. Moreover, as a cathode, the metal electrode formed of metals, such as iron, copper, nickel, Monel (trademark), can be used, for example.

The electrolyte solution contains hydrogen fluoride and metal fluoride. Although the type of the metal fluoride is not particularly limited, it is preferably a fluoride of at least one metal selected from potassium, cesium, rubidium, and lithium. When the electrolytic solution contains cesium or rubidium, the specific gravity of the electrolytic solution will increase, so that the amount of mist generated during electrolysis can be suppressed.

As the electrolyte, for example, a mixed molten salt of hydrogen fluoride (HF) and potassium fluoride (KF) can be used. The molar ratio of hydrogen fluoride and potassium fluoride in the mixed molten salt of hydrogen fluoride and potassium fluoride can be, for example, hydrogen fluoride:potassium fluoride=1.5~2.5:1. Hydrogen fluoride: Potassium fluoride = 2:1 KF・2HF is the representative electrolyte, and the melting point of this mixed molten salt is about 72℃. Since the electrolyte is corrosive, it is preferable that the contact parts of the electrolyte such as the inner surface of the electrolytic cell are formed of metals such as iron, nickel, and Monel (trademark).

During the electrolysis of the electrolyte, a direct current is applied to the anode and the cathode, the gas containing fluorine gas is generated at the anode, and the gas containing hydrogen gas is generated at the cathode. In addition, the hydrogen fluoride in the electrolyte has a vapor pressure, so hydrogen fluoride is mixed with the gas generated by the anode and the cathode, respectively. Furthermore, in the production of fluorine gas by electrolysis of the electrolytic solution, the gas generated by the electrolysis contains the mist of the electrolytic solution. Therefore, the gas phase part of the electrolytic cell is formed by the gas generated by electrolysis and the mist of hydrogen fluoride and electrolyte. Therefore, what is outputted from the inside of the electrolytic cell to the outside is formed by the gas generated by electrolysis and the mist of hydrogen fluoride and electrolyte solution, which is called "fluid" in the present invention.

However, since the hydrogen fluoride in the electrolytic solution is consumed by the progress of the electrolysis, the piping for supplying hydrogen fluoride to the electrolytic tank continuously or intermittently for replenishment may be connected to the electrolytic tank. The supply of hydrogen fluoride may be supplied to the cathode chamber side of the electrolytic cell, or may be supplied to the anode chamber side. The main reasons for the generation of mist during electrolysis of the electrolyte solution are as follows. The temperature of the electrolyte solution at the time of electrolysis is adjusted to, for example, 80 to 100°C. The melting point of KF and 2HF is 71.7°C. When the temperature is adjusted to the above temperature, the electrolyte is in a liquid state. The gas bubbles generated by the two electrodes of the electrolytic cell rise up in the electrolyte and burst at the liquid level of the electrolyte. At this time, a part of the electrolyte solution is released into the gas phase.

Since the temperature of the gas phase is lower than the melting point of the electrolyte, the electrolyte released here is phase-changed into a state of extremely fine powder. The powder system should be KF·nHF, a mixture of potassium fluoride and hydrogen fluoride. This powder system rides on the flow of other generated gases to become mist, forming the fluid produced by the electrolytic cell. Such mist is difficult to effectively remove due to the reasons of stickiness and the like, and it is only a normal countermeasure such as the installation of a filter.

In addition, although the amount of generation is small, there may be cases where fine powder of organic compounds is generated as mist due to the reaction with the carbonaceous electrode of the anode and the fluorine gas generated by electrolysis. In detail, contact resistance is often generated in the power supply portion of the current to the carbonaceous electrode, and the temperature of the electrolyte may be higher than that of the electrolyte through Joule heat. For this reason, the coal-like organic compound CFx may be generated as a mist through the reaction between the carbon forming the carbonaceous electrode and the fluorine gas.

However, the electrolytic cell has a structure in which the air bubbles generated by the anode or cathode used in the electrolysis rise in the vertical direction in the electrolyte and reach the liquid level of the electrolyte. When it is difficult for the air bubbles to rise vertically in the electrolyte solution and has a structure in which it rises in an oblique direction with respect to the vertical direction, a plurality of air bubbles tend to aggregate into large air bubbles. As a result, since the large air bubbles reach the liquid level of the electrolyte solution and burst, the amount of mist generation tends to increase. When bubbles rise in the vertical direction in the electrolyte, they can reach the liquid level of the electrolyte, and the small air bubbles reach the liquid level of the electrolyte and burst, and the amount of mist generated tends to be reduced.

[Average particle diameter measurement section] Although the fluorine gas production apparatus of the present embodiment may include an average particle diameter measuring section for measuring the average particle diameter of mist contained in the fluid, the average particle diameter measuring section is an optical scattering detector capable of measuring the average particle diameter by optical scattering. be constituted. Since the light scattering detector can measure the average particle diameter of the mist in the fluid flowing in the flow channel under the continuous operation of the fluorine gas production device, it is preferable to be used as the average particle diameter measuring unit.

An example of the light scattering detector will be described below with reference to FIG. 1 . The light scattering detector shown in FIG. 1 is used in the fluorine gas production apparatus of the present embodiment (for example, the fluorine gas production apparatus shown in FIGS. 2 and 4 to 13 described later), and can be used as a light scattering detector used in the average particle diameter measuring section. clutter detector. That is, the electrolytic solution containing hydrogen fluoride and metal fluoride is electrolyzed inside the electrolytic cell of the fluorine gas production device, and when fluorine gas is produced, the average particle size of the mist contained in the fluid generated in the electrolytic cell is measured. light scattering detector. The optical dispersion detector is connected to the fluorine gas production device, and the fluid is sent from the inside of the electrolytic cell to the optical dispersion detector to measure the average particle size of the mist, or the optical dispersion detector and the fluorine gas production device are not connected. , Take out the fluid from the inside of the electrolytic cell and introduce it into a light scattering detector to measure the average particle size of the mist.

The light scattering detector of FIG. 1 includes a sample chamber 1 that accommodates a fluid F, a light source 2 that irradiates the fluid F in the sample chamber 1 with light L for light scattering measurement, and light L for detecting light scattering The stray light detection unit 3 for stray light S generated by the stray light S generated by being scattered by the mist M in the fluid F, and the transparent window 4A provided in the sample chamber 1 to contact the fluid F and transmit the stray light for measuring light L, It is installed in the sample chamber 1, is in contact with the fluid F, and transmits the scattered light S through the transparent window 4B. The transparent windows 4A and 4B are made of at least one selected from diamond, calcium fluoride (CaF ₂ ), potassium fluoride (KF), silver fluoride (AgF), barium fluoride (BaF ₂ ), and potassium bromide (KBr). 1 is formed.

Light L (eg, laser light) emitted from the light source 2 passes through the convergent lens 6 and the transparent window 4A of the sample chamber 1 , enters the sample chamber 1 , and irradiates the fluid F contained in the sample chamber 1 . At this time, when there is a substance that reflects light such as the mist M in the fluid F, the light L for light scattering measurement is reflected and scattered. A part of the scattered light S generated by the scattered light L for light scattering measurement by the mist M is scattered through the transparent window 4B of the sample chamber 1, taken out from the sample chamber 1 to the outside, and enters through the condenser lens 7 and the aperture 8. Scattered light detection unit 3 . At this time, from the information obtained from the scattered light S, the average particle diameter of the mist M can be known. However, the average particle diameter obtained here is the number of average particle diameters. As the scattered light detection unit 3, for example, an aerosol spectrometer welas (registered trademark) digital 2000 manufactured by PALAS Corporation can be used.

Although the transparent windows 4A and 4B are in contact with the fluid F, since the fluid F contains a highly reactive fluorine gas, the transparent windows 4A and 4B need to be formed of a material that is difficult to be corroded by the fluorine gas. As a material system for forming the transparent windows 4A and 4B, at least one selected from the group consisting of diamond, calcium fluoride, potassium fluoride, silver fluoride, barium fluoride, and potassium bromide can be exemplified. When the transparent windows 4A and 4B are formed of the above-mentioned materials, deterioration due to contact with the fluid F can be suppressed.

In addition, a film made of the above-mentioned material can be applied to the surface of glass such as quartz, and used as the transparent windows 4A and 4B. Since the part in contact with the fluid F is coated with a film made of the above-mentioned material, it is possible to suppress the deterioration caused by the contact with the fluid F at a reduced cost. The transparent windows 4A and 4B may be a laminated body formed of the above-mentioned material on the surface to be in contact with the fluid F, and the other part may be formed of a normal glass such as quartz. The material of the parts other than the transparent windows 4A and 4B in the light scattering detector is not particularly limited as long as it has corrosion resistance to fluorine gas. For example, copper-nickel alloys such as Monel (trademark) and HASTELLOY (trademark) are used. ), stainless steel and other metal materials are preferred.

[Average particle size of mist and water concentration in electrolyte] The inventors of the present invention measured the average particle diameter of the mist generated during the production of fluorine gas formed by electrolysis of the electrolyte solution using a light scattering detector. An example of the result will be described. Replace the anode of the fluorine gas production device with a new anode, fill the electrolytic tank with new electrolyte, open the tire for electrolysis, and measure the average particle size of the mist in the fluid generated by the anode during a certain period of time after the start of electrolysis. As a result, the average particle diameter of the mist was 0.5 to 2.0 μm. After that, the electrolysis is continued, and after a sufficient time, the electrolysis begins to stabilize, and the average particle diameter of the mist in the fluid during stable electrolysis is about 0.2 μm. In this way, during the period from the start of electrolysis to the time of stable electrolysis, mist with a large particle size is generated. When the fluid containing the large mist after the start of electrolysis flows into the pipe or valve, the mist is adsorbed on the inner surface of the pipe or valve, and the blockage of the pipe or valve is easy to occur.

In this regard, during stable electrolysis, the particle size of the generated mist is small. Such a small mist is difficult to settle or accumulate in the fluid, and it can flow stably through pipes or valves. For this reason, during stable electrolysis, the possibility that the flow system of the mist and the gas generated in the electrode will block the piping or the valve is low. However, the time from the start of electrolysis to the time of stable electrolysis is usually 25 hours or more and 200 hours or less. Also, from the start of electrolysis to the time of stable electrolysis, approximately 40kAh or more of electricity is required per 1000L of electrolyte.

In addition, the present inventors discovered that there is a close relationship between the average particle size of the mist and the water concentration in the electrolyte solution. Usually, the water concentration in the electrolytic solution is large at the start of electrolysis, and shows a value larger than 1.0% by mass. The average particle diameter of the mist at this time is larger than 0.4 μm. Thereafter, as the electrolysis is continued, the water concentration in the electrolyte solution decreases, and when it becomes 0.3 mass % or less, the average particle diameter of the mist becomes 0.4 μm or less.

In this way, since the average particle size of the mist has a correlation with the moisture concentration in the electrolyte, it is possible to replace the average particle size of the mist during electrolysis to measure the moisture concentration in the electrolyte, and use the measurement results in the flow path. switch. That is, when the water concentration in the electrolyte is measured at a specific timing during electrolysis, in accordance with the measurement result, the flow path of the fluid generated by electrolysis is appropriately switched at the above-mentioned specific timing.

The deduction of the water concentration in the electrolyte is related to the magnitude of the current value and the amount of energization (the product of the current value and the electrolysis time) and decreases. ^The larger the current value, the faster the reduction of the water concentration, which will produce a carbonaceous electrode with an anode effect that the voltage of the anode rises sharply. electrolysis. The water concentration can be decreased at a constant current density, or the water concentration can be decreased by increasing the current density gradually.

Based on these findings, the present inventors have invented the above-mentioned fluorine gas production method and fluorine gas production apparatus having a structure in which the flow passage of the flowing fluid is switched according to the water concentration in the electrolyte during electrolysis. The fluorine gas production apparatus of the present embodiment has a first flow channel and a second flow channel, and a flow channel for fluid transfer may be selected from the two flow channels by using a flow channel switching portion (eg, a switching valve).

Alternatively, the fluorine gas production apparatus of the present embodiment has two flow channels, and a moving exchange mechanism for moving and exchanging the electrolytic cell. From the two flow channels, the flow channel used for the transfer of the fluid is selected, and the flow channel is located between the flow channels. Nearby, it is also possible to connect via a mobile electrolytic cell, and to switch the flow path. As described above, since the first flow channel and the second flow channel are provided, while the one flow channel is cut off for cleaning, the other flow channel can be opened to continue the operation of the fluorine gas production apparatus.

In the review by the present inventors, since the mist with a large average particle size is generated during the period from the start of electrolysis to the time of stable electrolysis, the fluid may be transported in the second flow passage having the occlusion suppressing mechanism at this time. As time elapses, and when stable electrolysis is reached, mist with a small average particle size is generated. At this time, the first flow channel having the mist removing portion can be used to transfer fluid, and the flow channel can be switched.

Although the switching of the flow channels is carried out according to the measured water concentration in the electrolyte, the switching of the flow channels can be carried out according to the preset reference value. A suitable reference value for the average particle diameter of the mist generated by the anode varies for each device, but may be, for example, 0.1 μm or more and 1.0 μm or less, preferably 0.2 μm or more and 0.8 μm or less, and more preferably 0.4 μm. Therefore, from the perspective of the correlation between the average particle size of the mist and the water concentration in the electrolyte solution, the appropriate reference value for the water concentration in the electrolyte solution is 0.1 mass % or more and 0.8 mass % or less, preferably 0.2 mass % or more 0.6 mass % or less, More preferably, it is 0.3 mass %. When the water concentration in the electrolyte is greater than the reference value, the fluid can be transported in the second flow channel, and when the water concentration is below the reference value, the fluid can be transported in the first flow channel.

The water concentration in the electrolyte solution can be measured, for example, by the Karl Fischer method. Alternatively, the electrolyte solution can be heated to, for example, 250° C. or higher and 400° C. or lower, and the amount of water in the generated gas can be measured by, for example, infrared spectroscopy to obtain the water concentration in the electrolyte solution. In the detection solution used in the Karl Fischer method, since the solid electrolyte is almost insoluble, although other solvents for dissolving the solid electrolyte are required, there are almost no solvents with high solubility for the solid electrolyte. Therefore, since it is difficult to dissolve a large amount of solid electrolyte and perform Karl Fischer analysis, the Karl Fischer method is suitable for the analysis of solid electrolyte with a large water content. In contrast, the method of heating a solid electrolyte to measure the amount of water in the generated gas requires a longer analysis time than the Karl Fischer method, but can accurately analyze the water concentration in the electrolyte.

However, the fluid produced by the cathode (the main component is hydrogen), for example, contains 20~50μg (calculated by assuming the specific gravity of the mist is 1.0 g/mL) per unit volume (1 liter) of powder, the average particle size of this powder The diameter is about 0.1 μm, with a distribution of ±0.05 μm.

In the fluid produced by the cathode, through the water concentration in the electrolyte, there is no big difference in the particle size distribution of the produced powder. The mist containing the fluid generated by the cathode has a smaller average particle size than the mist containing the fluid generated by the anode, and it is more difficult to cause blockage of pipes or valves than the mist containing the fluid generated by the anode. Therefore, the mist containing the fluid generated at the cathode can be removed from the fluid by using an appropriate removal method.

An example of the fluorine gas production apparatus of the present embodiment will be described in detail with reference to the lower part of FIG. 2 . Although the fluorine gas production apparatus of FIG. 2 is an example with two electrolytic cells, the number of electrolytic cells may be one, or three or more, for example, 10 to 15 cells. The fluorine gas production apparatus shown in FIG. 2 includes electrolytic cells 11 and 11 for accommodating an electrolytic solution 10 inside and performing electrolysis; The inside is immersed in the electrolytic solution 10 and at the same time, the cathode 15 is arranged opposite to the anode 13 .

The inside of the electrolytic cell 11 extends vertically downward from the ceiling inside the electrolytic cell 11 , and is immersed in the partition wall 17 of the electrolyte 10 through the lower end, and is divided into an anode chamber 22 and a cathode chamber 24 . Then, the anode 13 is arranged in the anode chamber 22 , and the cathode 15 is arranged in the cathode chamber 24 . However, the space on the liquid level of the electrolyte 10 is separated into the space in the anode chamber 22 and the space in the cathode chamber 24 through the partition wall 17, and the part above the lower end of the partition wall 17 in the electrolyte 10 is separated by the partition wall 17. The partition wall 17 is separated, and the portion on the lower side of the lower end of the partition wall 17 in the electrolyte solution 10 is continuous without being directly separated by the partition wall 17 .

Further, the fluorine gas production apparatus shown in FIG. 2 is provided with a moisture concentration measuring unit 36 that measures the moisture concentration in the electrolytic solution 10 in the electrolytic cell 11 during electrolysis of the electrolytic solution 10, and a moisture concentration measuring unit 36 that measures The first average particle diameter measuring section 31 for the average particle diameter of the mist contained in the fluid generated in the electrolytic cell 11, the first mist removing section 32 for removing the mist from the fluid, and the fluorine gas extracted from the fluid and extracted A fluorine gas extraction part (not shown) and a flow channel for transporting fluid from the inside of the electrolytic cell 11 to the fluorine gas extraction part.

Furthermore, this flow channel has a first flow channel for conveying fluid from the inside of the electrolytic cell 11 to the fluorine gas extraction section via the first mist removing portion 32 , and a first flow channel for transferring fluid from the electrolytic cell 11 without passing through the first mist removing portion 32 . A second flow channel that internally transports fluid to the fluorine gas extraction unit. In addition, this flow path has a flow path switching portion that switches the flow path of the flowing fluid to the first flow path or the second flow path according to the moisture concentration in the electrolyte 10 measured by the moisture concentration measuring portion 36 . That is, a flow channel switching portion is provided in the middle of the flow channel extending from the electrolytic cell 11, and the flow channel of the flowing fluid can be changed through the flow channel switching portion.

This flow channel switching unit transfers the fluid from the inside of the electrolytic cell 11 to the first flow channel when the water concentration in the electrolyte 10 measured by the water concentration measuring unit 36 is equal to or less than a predetermined reference value, which is higher than the predetermined value. When the reference value is large, the fluid is fed from the inside of the electrolytic cell 11 to the second flow path. Then, the second flow path has a blockage suppressing mechanism that suppresses blockage caused by the mist of the second flow path.

That is, when the water concentration in the electrolytic solution 10 is below the reference value, the electrolytic cell 11 and the fluorine gas extraction part are connected, and the fluid and the water in the electrolytic solution 10 are transported through the first flow path where the first mist removing part 32 is provided. When the concentration is larger than the reference value, the electrolytic cell 11 and the fluorine gas extraction part are connected, and the fluid is fed in the second flow passage provided with the occlusion suppression mechanism. As the moisture concentration measuring unit 36, for example, a Karl Fischer moisture measuring apparatus can be used.

As the first mist removing unit 32, for example, a mist removing device capable of removing mist having an average particle size of 0.4 μm or less from a fluid is used. The type of mist removing device, that is, the method of removing mist, is not particularly limited, but because the average particle size of mist is small, for example, electrostatic precipitators, venturi cleaners, and filters can be used as mist removal devices. device is used.

Among the above-mentioned mist removing apparatuses, it is preferable to use the mist removing apparatus shown in FIG. 3 . The mist removing device shown in FIG. 3 is a scrubber-type mist removing device using liquid hydrogen fluoride as a circulating liquid. The mist removing device shown in FIG. 3 can efficiently remove mist having an average particle diameter of 0.4 μm or less from the fluid. In addition, although the liquid hydrogen fluoride is used as the circulating liquid, in order to reduce the concentration of hydrogen fluoride in the fluorine gas, it is better to cool the circulating liquid, and the concentration of hydrogen fluoride in the fluorine gas can be adjusted by controlling the cooling temperature.

The fluorine gas production apparatus shown in FIG. 2 will be described in more detail. The fluid generated in the anode chamber 22 of the electrolytic cell 11 (hereinafter referred to as "anode gas") is sent to the external first piping 41, the electrolytic cell 11 and the fourth piping 44 are connected, and the two electrolytic cells are connected. The anode gas sent from 11 and 11 is sent to the fourth pipe 44 through the first pipe 41 to be mixed. However, the main component of the anode gas is fluorine gas, and the subcomponents are mist, hydrogen fluoride, carbon tetrafluoride, oxygen, and water.

The fourth piping 44 is connected to the first mist removing portion 32 , and the anode gas is sent to the first mist removing portion 32 through the fourth piping 44 , and the mist and hydrogen fluoride in the anode gas are sent to the first mist removing portion 32 from the first mist removing portion 32 . Anode gas is removed. The anode gas system for removing mist and hydrogen fluoride is sent from the first mist removing portion 32 to a fluorine gas extracting portion (not shown) via the sixth piping 46 connected to the first mist removing portion 32 . Then, fluorine gas is extracted from the anode gas through the fluorine gas extraction unit and taken out.

However, an eighth piping 48 is connected to the first mist removing part 32 , and the hydrogen fluoride in the liquid circulating liquid is supplied to the first mist removing part 32 via the eighth piping 48 . Furthermore, the ninth piping 49 is connected to the first mist removing part 32 . The ninth piping 49 is connected to the electrolytic cells 11 and 11 via the third piping 43, and is used in the first mist removing part 32 to remove the mist, and the circulating liquid containing the mist (liquid hydrogen fluoride) is removed from the first mist Section 32 returns to electrolytic cells 11 , 11 .

For the cathode chamber 24 of the electrolytic cell 11, and the anode chamber 22 is the same. That is, when the fluid generated in the cathode chamber 24 of the electrolytic cell 11 (hereinafter referred to as "cathode gas") is sent to the external second piping 42, the electrolytic cell 11 and the fifth piping 45 are communicated, and the electrolytic cell 11 and the fifth piping 45 are communicated. The cathode gas sent from the tanks 11 and 11 is sent to the fifth pipe 45 via the second pipe 42 to be mixed. However, the main component of the cathode gas is hydrogen gas, and the sub-components are mist, hydrogen fluoride, and water.

Because the cathode gas system contains fine mist and 5~10% by volume of hydrogen fluoride, it is not good to directly discharge the atmosphere. Therefore, the fifth pipe 45 is connected to the second mist removing part 33 , and the cathode gas is sent to the second mist removing part 33 through the fifth pipe 45 , and the mist and hydrogen fluoride in the cathode gas are sent through the second mist removing part 33 , removed from the cathode gas. The cathode gas system for removing mist and hydrogen fluoride is discharged from the second mist removing portion 33 to the atmosphere via the seventh piping 47 connected to the second mist removing portion 33 . The type of the second mist removing part 33, that is, the method of removing the mist is not particularly limited, but a scrubber-type mist removing device using an alkaline aqueous solution as a circulating liquid can be used.

The diameter or installation direction (meaning the direction in which the pipes extend, such as the vertical direction and the horizontal direction) of the first piping 41, the second piping 42, the fourth piping 44, and the fifth piping 45 are not particularly limited. The second piping 42 extends vertically from the electrolytic cell 11, and the flow velocity of the fluid flowing in the first piping 41 and the second piping 42 is 30 cm/sec or less in a standard state, and the pipe diameter is preferably set. In this way, when the mist contained in the fluid falls by its own weight, the mist settles in the electrolytic cell 11 , so that it is difficult to block the inside of the first piping 41 and the second piping 42 due to powder generation. In addition, the fourth piping 44 and the fifth piping 45 are extended in the horizontal direction, and the flow velocity of the fluid flowing in the fourth piping 44 and the fifth piping 45 is 1 to 10 times that of the first piping 41 and the second piping 42 It is better to set the pipe diameter as quickly as possible.

Furthermore, the second bypass piping 52 for sending the anode gas to the outside of the electrolytic cell 11 is provided separately from the first piping 41 . That is, the second bypass piping 52 communicates the electrolytic cell 11 and the first bypass piping 51, and the anode gas sent from the two electrolytic cells 11 and 11 is sent to the first bypass piping via the second bypass piping 52 51 to be mixed. Furthermore, the anode gas is sent out to the fluorine gas extraction part not shown through the first bypass pipe 51 . Then, fluorine gas is extracted from the anode gas through the fluorine gas extraction unit and taken out. However, the fluorine gas extraction part connected to the first bypass piping 51 and the fluorine gas extraction part connected to the sixth piping 46 may be the same or different.

Although the diameter or installation direction of the second bypass piping 52 is not particularly limited, the second piping 52 is extended from the electrolytic cell 11 in the vertical direction, and the flow velocity of the fluid flowing in the second bypass piping 52 is 30 in the standard state. It is better to set the pipe diameter below cm/sec.

Moreover, the 1st bypass piping 51 is extended in the horizontal direction. Then, the first bypass pipe 51 is a pipe with a larger diameter than the fourth pipe 44, and the diameter of the first bypass pipe 51 is so large that it is difficult to generate the first bypass pipe due to the accumulation of powder. Block 51. The 1st bypass piping 51 passes the piping whose diameter is larger than the 4th piping 44, and comprises a blockage suppression means. The diameter of the first bypass piping 51 is preferably more than 1.0 times and not more than 3.2 times that of the fourth piping 44, and more preferably not less than 1.05 times and not more than 1.5 times. That is, it is preferable that the cross-sectional area of the flow passage of the first bypass piping 51 is 10 times or less the size of the fourth piping 44 .

As can be seen from the above description, the above-mentioned first flow path is formed via the first piping 41 and the fourth piping 44 , and the above-mentioned second flow path is formed via the first bypass piping 51 and the second bypass piping 52 . Then, a clogging suppression mechanism is provided in the first bypass pipe 51 constituting the second flow path.

Next, the flow path switching section will be described. Each of the first piping 41 is provided with a first piping valve 61 . Then, by switching the first piping valve 61 to the open state or the closed state, it is possible to control whether or not to supply the anode gas from the electrolytic cell 11 to the first mist removing part 32 . Moreover, the bypass valve 62 is provided in the 2nd bypass piping 52, respectively. Then, by switching the bypass valve 62 to the open state or the closed state, it is possible to control whether or not to supply the anode gas from the electrolytic cell 11 to the first bypass piping 51 .

Furthermore, the electrolytic cell 11 is provided with a moisture concentration measuring unit 36, and the electrolytic solution 10 in the electrolytic cell 11 is introduced into the moisture concentration measuring unit 36, and the moisture concentration in the electrolytic solution 10 can be measured during electrolysis. The electrolyte 10 for measuring the water concentration may be the electrolyte 10 on the side of the anode chamber 22 or the electrolyte 10 on the side of the cathode chamber 24 .

Furthermore, between the electrolytic cell 11 and the first mist removing portion 32, in detail, in the middle portion of the fourth piping 44, and on the downstream side of the connection portion of the first piping 41, a first average particle diameter measurement is provided. Section 31. Then, the average particle diameter of the mist contained in the anode gas flowing through the fourth piping 44 is measured through the first average particle diameter measuring unit 31 . Furthermore, by analyzing the fluorine gas and nitrogen gas contained in the anode gas after the measurement of the average particle diameter of the mist, the current efficiency of the production of the fluorine gas can be measured.

Then, in the middle part of the first bypass pipe 51, and on the downstream side of the connection part of the second bypass pipe 52, the second average particle diameter measuring part 34 is similarly provided, and through the second average particle diameter measuring part 34, The average particle diameter of the mist contained in the anode gas flowing through the first bypass pipe 51 was measured. However, the fluorine gas production apparatus shown in FIG. 2 may not include the first average particle diameter measuring unit 31 and the second average particle diameter measuring unit 34 .

The moisture concentration in the electrolytic solution 10 in the electrolytic cell 11 is measured through the moisture concentration measuring unit 36, and when the measurement result is greater than the preset reference value, the bypass valve 62 is opened, and the anode gas is removed from the electrolytic cell. At the same time that 11 is sent to the first bypass piping 51 , the first piping valve 61 is closed, and the anode gas is not sent to the fourth piping 44 and the first mist removing unit 32 . That is, the anode gas is sent to the second flow path.

On the other hand, when the measurement result is lower than the preset reference value, the first piping valve 61 is opened, and the anode gas is sent to the fourth piping 44 and the first mist removing unit 32, and the bypass valve 62 is opened. The state is closed, and the anode gas is not sent from the electrolytic cell 11 to the first bypass piping 51 . That is, the anode gas is sent to the first flow path. As can be seen from the above description, the above-described flow path switching portion is configured via the first piping valve 61 and the bypass valve 62 .

As described above, according to the water concentration in the electrolyte 10 at the time of electrolysis, the fluorine gas production apparatus is operated while switching the flow path, and the operation is performed smoothly and continuously while suppressing the blockage of pipes and valves caused by mist. Therefore, according to the fluorine gas production apparatus shown in FIG. 2, fluorine gas can be produced economically.

For example, as the mist removal part, it is possible to prepare a plurality of pipes with filters installed, and to perform electrolysis while changing the filters appropriately. Furthermore, the period during which the filter is to be exchanged frequently and the period during which the filter is not required to be exchanged frequently can be determined based on the measurement of the water concentration in the electrolyte 10 during electrolysis. Then, according to the above judgment, when the switching frequency of the flowing fluid piping is appropriately adjusted, the operation of the fluorine gas production apparatus can be efficiently continued.

Next, a modification of the fluorine gas production apparatus shown in FIG. 2 will be described. [1st Variation] The first modification will be described with reference to FIG. 4 . Compared with the fluorine gas production apparatus shown in FIG. 2, the second bypass piping 52 connects the electrolytic cell 11 and the first bypass piping 51, and in the fluorine gas production apparatus of the first modification shown in FIG. The path piping 52 connects the first piping 41 and the first bypass piping 51 . The configuration of the fluorine gas production apparatus of the first modification is almost the same as that of the fluorine gas production apparatus of FIG. 2 except for the above-mentioned parts, and the description of the same parts is omitted.

[Second modification example] The second modification will be described with reference to FIG. 5 . The fluorine gas production apparatus of the second modification shown in FIG. 5 is an example provided with one electrolytic cell 11 . The first average particle diameter measuring unit 31 is not the fourth piping 44 but is provided on the first piping 41 and is provided on the upstream side of the first piping valve 61 . In addition, the second bypass piping 52 is not provided, and the first bypass piping 51 is directly connected to the electrolytic cell 11 without the second bypass piping 52 .

Then, since the diameter of the first bypass pipe 51 is larger than that of the fourth pipe 44, it functions as a clogging suppressing mechanism. Furthermore, for example, by providing a space for storing mist at the downstream end of the first bypass pipe 51, the effect of suppressing clogging is further increased. As the space for storing the mist, for example, a pipe diameter formed so that the downstream end portion of the first bypass pipe 51 is larger than the central portion in the installation direction (for example, the pipe diameter of the central portion in the installation direction is 4 times or more). The space formed, or the space formed by forming the downstream end portion of the first bypass pipe 51 in the shape of a container, can suppress the blockage of the first bypass pipe 51 through the space for storing mist. This is for the effect of preventing occlusion caused by the large cross-sectional area of the flow path, and the effect of preventing occlusion from falling due to the gravity of the mist due to the decrease in the linear velocity of the gas flow. Furthermore, the bypass valve 62 is provided in the 3rd bypass piping 53 which connects the 1st bypass piping 51 and the fluorine gas extraction part which is not shown in figure. The configuration of the fluorine gas production apparatus of the second modification is almost the same as that of the fluorine gas production apparatus of FIG. 2 except for the above-mentioned parts, and the description of the same parts is omitted.

[3rd Variation] The third modification will be described with reference to FIG. 6 . In the fluorine gas production apparatus according to the third modification, the first average particle diameter measuring unit 31 is provided in the electrolytic cell 11, and the anode gas inside the electrolytic cell 11 is directly introduced into the first average particle diameter measuring unit 31 to measure the average particle size of the mist. Diameter determination. The fluorine gas production apparatus of the third modification does not include the second average particle diameter measuring unit 34 . The configuration of the fluorine gas production apparatus of the third modification is almost the same as that of the fluorine gas production apparatus of the second modification except for the above-mentioned parts, and the description of the same parts is omitted.

[4th Variation] The fourth modification will be described with reference to FIG. 7 . The fluorine gas production apparatus of the fourth modification is a different example from the second modification shown in FIG. 5 in which the blockage suppression mechanism is different. In the fluorine gas production apparatus according to the second modification, the first bypass pipe 51 is provided to extend in the horizontal direction, but in the fluorine gas production apparatus according to the fourth modification, the first bypass pipe 51 is inclined with respect to the horizontal direction. , and extends in the direction of descending from the upstream side to the downstream side. By this inclination, accumulation of powder in the inside of the first bypass piping 51 can be suppressed. The greater the inclination, the greater the effect of suppressing the accumulation of powder.

The inclination angle of the first bypass piping 51 is in a range smaller than 90 degrees from the depression angle from the horizontal plane, preferably 30 degrees or more, and more preferably 40 degrees or more and 60 degrees or less. If clogging of the first bypass pipe 51 occurs, when the inclined first bypass pipe 51 is hammered, the deposits inside the first bypass pipe 51 are easily moved, and clogging can be avoided. The configuration of the fluorine gas production apparatus of the fourth modification is almost the same as that of the fluorine gas production apparatus of the second modification except for the above-mentioned parts, and the description of the same parts is omitted.

[5th Variation] The fifth modification will be described with reference to FIG. 8 . The fluorine gas production apparatus of the fifth modification is a different example from the third modification shown in FIG. 6 in that the clogging suppression mechanism is different. In the fluorine gas production apparatus according to the third modification, the first bypass pipe 51 is installed to extend in the horizontal direction, but in the fluorine gas production apparatus according to the fifth modification, the first bypass pipe 51 is inclined with respect to the horizontal direction. , and extends in the direction of descending from the upstream side to the downstream side. By this inclination, accumulation of powder in the inside of the first bypass piping 51 can be suppressed. The preferable inclination angle of the first bypass piping 51 is the same as that in the above-mentioned fourth modification. The configuration of the fluorine gas production apparatus of the fifth modification is almost the same as that of the fluorine gas production apparatus of the third modification except for the above-mentioned parts, and the description of the same parts is omitted.

[Sixth modification example] The sixth modification will be described with reference to FIG. 9 . The fluorine gas production apparatus of the sixth modification is an example in which the structure of the electrolytic cell 11 is different from the second modification shown in FIG. 5 . The electrolytic cell 11 has one anode 13 and two cathodes 15 and 15 , and is divided into one anode chamber 22 and one cathode chamber 24 via a cylindrical partition wall 17 surrounding one anode 13 . The anode chamber 22 is formed to extend above the upper surface of the electrolytic cell 11 , and the first bypass piping 51 is connected to the upper end portion of the anode chamber 22 of the electrolytic cell 11 . The configuration of the fluorine gas production apparatus of the sixth modification is almost the same as that of the fluorine gas production apparatus of the second modification except for the above-mentioned parts, and the description of the same parts is omitted.

[Variation 7] The seventh modification will be described with reference to FIG. 10 . The fluorine gas production apparatus of the seventh modification is an example in which the structure of the first bypass piping 51 is different from the sixth modification shown in FIG. 9 . That is, in the fluorine gas production apparatus according to the seventh modification, the first bypass pipe 51 is the same as the fourth modification and the fifth modification, is inclined with respect to the horizontal direction, and extends so as to descend from the upstream side to the downstream side. direction. The preferable inclination angle of the first bypass piping 51 is the same as that in the above-mentioned fourth modification. The configuration of the fluorine gas production apparatus of the seventh modification is almost the same as that of the fluorine gas production apparatus of the sixth modification except for the above-mentioned parts, and the description of the same parts is omitted.

[8th Variation] The eighth modified example will be described with reference to FIG. 11 . The fluorine gas production apparatus of the eighth modification is a different example from the second modification shown in FIG. 5 in which the blockage suppression mechanism is different. In the fluorine gas production apparatus of the eighth modification, the rotating screw 71 constituting the clogging suppression mechanism is provided inside the first bypass pipe 51 . The rotating screw 71 is provided so as to be parallel to the longitudinal direction of the first bypass pipe 51 with respect to the rotating shaft. Then, the rotary screw 71 is rotated by the motor 72, and the mist accumulated in the inside of the first bypass pipe 51 is sent to the upstream side or the downstream side. Thereby, accumulation of powder in the inside of the first bypass piping 51 can be suppressed. The configuration of the fluorine gas production apparatus of the eighth modification is almost the same as that of the fluorine gas production apparatus of the second modification except for the above-mentioned parts, and the description of the same parts is omitted.

[Ninth Variation] The ninth modification example will be described with reference to FIG. 12 . The fluorine gas production apparatus of the ninth modified example is a different example from the second modified example shown in FIG. 5 in which the blockage suppression mechanism is different. In the fluorine gas production apparatus of the ninth modified example, the airflow generation device 73 constituting the clogging suppression mechanism is provided inside the first bypass pipe 51 . The airflow generator 73 feeds an airflow (eg, nitrogen gas) from the upstream side of the first bypass pipe 51 to the downstream side, and the flow rate of the anode gas in the first bypass pipe 51 rises. Thereby, accumulation of powder in the inside of the first bypass piping 51 can be suppressed.

The preferable flow velocity of the anode gas flowing in the first bypass pipe 51 at this time is 1 m/sec or more and 10 m/sec or less. Although the flow velocity can be made larger than 10 m/sec, the pressure loss caused by the resistance of the piping in the first bypass piping 51 increases, and the pressure in the anode chamber 22 of the electrolytic cell 11 increases. It is preferable that the pressure in the anode chamber 22 and the pressure in the cathode chamber 24 are almost the same, and when the difference between the pressure in the anode chamber 22 and the pressure in the cathode chamber 24 is too large, the anode gas will flow into the cathode through the partition wall 17 In the chamber 24, fluorine gas reacts with hydrogen gas, which will hinder the generation of fluorine gas. The configuration of the fluorine gas production apparatus of the ninth modification is almost the same as that of the fluorine gas production apparatus of the second modification except for the above-mentioned parts, and the description of the same parts is omitted.

[10th Variation] The tenth modification will be described with reference to FIG. 13 . In the fluorine gas production apparatus of the tenth modification, the first average particle diameter measuring unit 31 is provided in the electrolytic cell 11, and the anode gas inside the electrolytic cell 11 is directly introduced into the first average particle diameter measuring unit 31 to measure the average particle size of the mist. Diameter determination. The fluorine gas production apparatus of the tenth modification does not include the second average particle diameter measuring unit 34 . The configuration of the fluorine gas production apparatus of the tenth modification is almost the same as that of the fluorine gas production apparatus of the ninth modification shown in FIG. 12 except for the above-mentioned parts, and the description of the same parts is omitted. [Example]

Hereinafter, an Example and a comparative example are shown, and this invention is demonstrated more concretely. [Reference Example 1] Electrolyte was electrolyzed to produce fluorine gas. As the electrolyte, a mixed molten salt (560 L) of 434 kg of hydrogen fluoride and 630 kg of potassium fluoride was used. As the anode, an amorphous carbon electrode (30 cm in width, 45 cm in length, and 7 cm in thickness) made by SGL Cabon was used, and 16 anodes were installed in the electrolytic cell. In addition, a perforated plate of Monel (trademark) was used as a cathode, and an electrolytic cell was installed. In one anode, the opposite two cathodes, and one anode, the total area of the part facing the cathode is 1736 cm ² .

The electrolysis temperature is controlled at 85~95℃. First, the temperature of the electrolyte solution was set to 85° C., and the direct current of 1000 A was applied at a current density of 0.036 A/cm ² to start electrolysis. At this time, the water concentration in the electrolytic solution was 1.0% by mass. However, the moisture concentration can be determined by Karl Fisher analysis. Electrolysis was started under the above-mentioned conditions, and a small cracking sound was observed in the vicinity of the anode in the anode chamber during 10 hours from the start of electrolysis. This cracking sound should be generated by the reaction between the generated fluorine gas and the moisture in the electrolyte.

In this state, the fluid generated by the anode is sent to the outside from the anode chamber of the electrolytic cell and collected, and the mist contained in the fluid is analyzed. As a result, the fluid produced by the anode contains 5.0 to 9.0 mg (calculated by assuming that the specific gravity of the mist is 1.0 g/mL. The same applies hereinafter) powder per 1 L, and the average particle diameter of the powder is 1.0 to 2.0 μm. As a result of observation of this powder with an optical microscope, the shape of the powder passing through the interior of the sphere was mainly observed. In addition, the current efficiency of fluorine gas generation at this time is 0 to 15%.

Moreover, the frequency of cracking sound generated inside the anode chamber is reduced when the energization amount continues to be electrolyzed to 30kAh. At this time, the water concentration in the electrolytic solution was 0.7% by mass. In this state, the fluid generated by the anode is sent out from the anode chamber of the electrolytic cell to the outside and collected, and the mist contained in the fluid is analyzed. As a result, the fluid produced by the anode contained 0.4-1.0 mg of mist per 1 L, and the average particle diameter of the mist was 0.5-0.7 μm. Moreover, the current efficiency of fluorine gas generation at this time is 15~55%. Let the electrolysis stage from the start of electrolysis to this point be "stage (1)".

Furthermore, following stage (1), the electrolysis of the electrolyte is continued. As a result, hydrogen fluoride is consumed and the water level of the electrolytic solution drops, so that hydrogen fluoride is appropriately supplied from the hydrogen fluoride tank to the electrolytic tank. The water concentration in the supplied hydrogen fluoride is 500 mass ppm or less. Furthermore, when the electrolysis is continued, and the energization amount reaches 60kAh, the average particle size of the mist contained in the fluid generated by the anode becomes 0.36 μm (ie, 0.4 μm or less). At this time, no cracking sound is generated in the anode chamber at all. In addition, the water concentration in the electrolyte solution at this time was 0.2 mass % (that is, 0.3 mass % or less). Moreover, the current efficiency of fluorine gas generation at this time is 65%. Let the electrolysis stage from the termination time point of stage (1) to this be "stage (2)".

Furthermore, the current was increased to 3500 A, and the current density was increased to 0.126 A/cm ² , and the step (2) was continued, and the electrolysis of the electrolyte was continued. In this state, the fluid generated by the anode is sent to the outside from the anode chamber of the electrolytic cell and collected, and the mist contained in the fluid is analyzed. As a result, the fluid produced by the anode contains 0.03-0.06 mg of powder per 1 L, the average particle diameter of the powder is about 0.2 μm (0.15-0.25 μm), and the particle diameter has a distribution of about 0.1-0.5 μm . Fig. 14 shows the measurement results of the particle size distribution of this powder. Moreover, the current efficiency of fluorine gas generation at this time is 94%. At this time, the water concentration in the electrolyte solution is less than 0.2 mass %. Let the electrolysis stage from the termination point of stage (2) to this point be the "stable stage".

The content of the electrolysis of Reference Example 1 performed as described above is shown in Table 1 in its entirety. In Table 1, the accompanying current, the elapsed time of electrolysis, the amount of energization, the water concentration in the electrolyte, the fluid produced by the anode (referred to as "anode gas" in Table 1), the mass of the mist contained in 1L, and the average particle size of the mist It also shows the amount of fluid (containing fluorine, oxygen, mist) generated by the anode, the amount of mist generated by the anode, the intensity of the cracking sound, and the water concentration in the fluid generated by the cathode (Table 1). 1 is referred to as "water concentration in cathode gas").

In addition, a graph showing the relationship between the average particle size of the mist and the amount of the mist generated by the anode is shown in FIG. 15 . From the graph of FIG. 15, it can be seen that there is a correlation between the average particle size of the mist and the amount of mist generated by the anode. The larger the amount of mist generated, the easier it is to block pipes or valves. When mist larger than the average particle diameter of 0.4 μm is generated, the amount of mist generated increases, and it is precipitated by gravity. The graph in Figure 15 The relationship shown can be said to represent the correlation between the average particle size of the mist and the susceptibility to the occlusion of pipes or valves. Furthermore, a graph showing the relationship between the average particle size of the mist and the water concentration in the electrolyte is shown in FIG. 16 . The larger the average particle size of the mist is, the more likely it is to block the pipes or valves. The relationship shown in the graph in Fig. 16 can be called the correlation between the water concentration in the electrolyte and the easy generation of blockage of the pipes or valves. sex.

[Example 1] The same electrolysis as in Reference Example 1 was performed using the fluorine gas production apparatus shown in FIG. 2 . In the electrolysis of the stage (1), the fluid generated by the anode is circulated through the second bypass pipe, the bypass valve, and the first bypass pipe. After the electrolysis of the stage (1) is terminated, the electrolysis is temporarily stopped, and the internal inspection of the fluorine gas production apparatus is carried out. As a result, although the mist was accumulated in the first bypass piping, the piping was not blocked due to the large diameter of the piping.

Since the average particle diameter of the mist is 0.4 μm or less (the water concentration in the electrolyte is 0.3 mass % or less of the reference value and 0.2 mass %), the fluid generated by the anode is passed through the first stage (2). The piping, the 1st piping valve, the 4th piping, and the 1st mist removing part are circulated. The first piping, the first piping valve, and the fourth piping did not accumulate or block the mist, and the flow system generated by the anode was supplied to the first mist removing part, and the first mist removing part removed the mist. The first mist removing section is a scrubber-type removing section that sprays hydrogen fluoride in the liquid and removes fine particles such as mist, and the mist removal rate is 98% or more.

[Comparative Example 1] In the electrolysis of stage (1), the same procedure as in Example 1 was performed except that the fluid generated by the anode was circulated through the first piping, the first piping valve, the fourth piping, and the first mist removing part. The same electrolysis was performed. In the electrolysis of stage (1), the measured value of the pressure gauge on the anode side of the pressure gauges installed on the anode side and the cathode side of the electrolytic cell gradually increased, and the pressure difference with the pressure on the cathode side became 90 mmH ₂ O. Therefore, stop electrolysis. The reasons for the suspension are as follows. Since the vertical length (impregnation length) of the part of the electrolyte immersed in the partition wall in the electrolytic cell is 5 cm, when the pressure on the anode side is about 100 mmH ₂ O higher than the pressure on the cathode side, the amount of electrolyte on the anode side is about 100 mmH2O higher. The liquid level is lower than the lower end of the partition wall. As a result, the fluorine gas crosses the partition wall and mixes with the hydrogen gas on the cathode side, resulting in a violent reaction between the fluorine gas and the hydrogen gas, which is very dangerous.

The inside of the first piping, the first piping valve, and the fourth piping was checked after the system was exhausted with nitrogen, etc. The first piping was a piping extending in the vertical direction, and there was no blockage. A small amount of powder adhered to the first piping valve, and the piping on the downstream side of the first piping valve, that is, the inlet portion of the fourth piping was blocked by the powder. The fourth piping also had powder accumulation, but not enough to block the piping.

1: Sample room 2: light source 3: Scattered light detection section 4A, 4B: Transparent window 10: Electrolyte 11: Electrolyzer 13: Anode 15: Cathode 22: Anode chamber 24: Cathode Chamber 31: The first average particle diameter measuring section 32: 1st mist removal part 33: 2nd mist removal part 34: Second Average Particle Diameter Measurement Section 36: Moisture concentration measuring section 41: 1st piping 42: 2nd piping 43: 3rd piping 44: 4th piping 45: 5th piping 46: 6th piping 47: 7th piping 48: No. 8 piping 49: 9th piping 51: 1st bypass piping 52: Second bypass piping 61: 1st piping valve 62: Bypass valve F: fluid L: light for light scattering measurement M: fog S: scattered light

1 is a schematic diagram illustrating an example of a light scattering detector used as an average particle diameter measuring unit in a fluorine gas production apparatus according to an embodiment of the present invention. [ Fig. 2] Fig. 2 is a schematic diagram illustrating an example of a fluorine gas production apparatus according to an embodiment of the present invention. [ Fig. 3] Fig. 3 is a schematic diagram illustrating an example of a mist removal device used as a mist removal unit in the fluorine gas production apparatus of Fig. 2 . [ Fig. 4] Fig. 4 is a schematic diagram illustrating a first modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 5] Fig. 5 is a schematic diagram illustrating a second modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 6] Fig. 6 is a schematic diagram illustrating a third modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 7] Fig. 7 is a schematic diagram illustrating a fourth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 8] Fig. 8 is a schematic diagram illustrating a fifth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 9] Fig. 9 is a schematic diagram illustrating a sixth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 10] Fig. 10 is a schematic diagram illustrating a seventh modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 11] Fig. 11 is a schematic diagram illustrating an eighth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 12] Fig. 12 is a schematic diagram illustrating a ninth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 13] Fig. 13 is a schematic diagram illustrating a tenth modification of the fluorine gas production apparatus of Fig. 2 . [ Fig. 14 ] In Reference Example 1, a graph showing the particle size distribution of the mist contained in the fluid generated by the anode. [ Fig. 15] In Reference Example 1, a graph showing the correlation between the average particle size of mist and the amount of mist generated by the anode. 16 is a graph showing the relationship between the average particle size of mist and the water concentration in the electrolyte solution in Reference Example 1. FIG.

10: Electrolyte

11: Electrolyzer

13: Anode

15: Cathode

17: Partition Wall

22: Anode chamber

24: Cathode Chamber

31: The first average particle diameter measuring section

32: 1st mist removal part

33: 2nd mist removal part

34: Second Average Particle Diameter Measurement Section

36: Moisture concentration measuring section

41: 1st piping

42: 2nd piping

43: 3rd piping

44: 4th piping

45: 5th piping

46: 6th piping

47: 7th piping

48: No. 8 piping

49: 9th piping

51: 1st bypass piping

52: Second bypass piping

61: 1st piping valve

62: Bypass valve

Claims (4)

A method for producing fluorine gas, comprising electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride to produce a fluorine gas producing fluorine gas, which is characterized by comprising: in an electrolytic cell, the electrolysis process of the aforementioned electrolysis is performed, and during the aforementioned electrolysis , the water concentration measurement process for measuring the water concentration in the electrolytic solution, and the electrolysis of the electrolytic solution, the fluid generated inside the electrolytic cell is transported from the inside of the electrolytic cell to the outside through the flow channel The gas supply project; in the aforementioned gas supply project, the flow channel for the flow of the aforementioned fluid is switched according to the moisture concentration in the aforementioned electrolyte solution measured by the aforementioned moisture concentration measurement process, and the aforementioned moisture concentration measurement process in the aforementioned electrolyte The concentration of water in the electrolyte solution is: When the preset reference value is less than or equal to the preset reference value, the first flow channel that transports the fluid from the inside of the electrolytic cell to the first outside, and the fluid is transported. The inside of the second flow channel that transports the fluid to the second outside, and the fluid is transported. The preset reference value is a value within the range of 0.1% by mass to 0.8% by mass; A structure in which the bubbles generated by the anode or cathode used rise in the vertical direction in the electrolyte solution, and can reach the liquid level of the electrolyte solution. The method for producing fluorine gas according to claim 1, wherein the metal fluoride is at least one selected from the group consisting of potassium, cesium, rubidium, and lithium the metal fluoride. The method for producing fluorine gas according to claim 1 or 2, wherein the anode used in the electrolysis is formed of at least one carbon material selected from the group consisting of diamond, diamond-like carbon, amorphous carbon, graphite, and glassy carbon carbon electrode. A fluorine gas production apparatus for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride, characterized by comprising: an electrolytic cell for accommodating the electrolyte solution and performing the above electrolysis, and measuring the measurement during the above electrolysis. The water concentration measuring section for the water concentration in the electrolytic solution in the electrolytic cell, and the flow of the fluid generated inside the electrolytic cell during the electrolysis of the electrolytic solution from the inside of the electrolytic cell to the outside channel; the flow channel has a first flow channel for transporting the fluid from the inside of the electrolytic cell to the first outside, and a second flow channel for transporting the fluid from the inside of the electrolytic cell to the second outside, and has a corresponding The flow path switching portion is a flow path switching portion that switches the flow path through which the fluid flows into the first flow path or the second flow path based on the moisture concentration in the electrolyte solution measured by the moisture concentration measuring portion. When the water concentration in the electrolytic solution measured by the water concentration measuring unit is below a preset reference value, the fluid is sent from the inside of the electrolytic cell to the first flow path, which is higher than the preset reference value. When the value is large, the fluid is transported from the inside of the electrolytic cell to the second channel, The above-mentioned preset reference value is a value within the range of 0.1% by mass to 0.8% by mass; the above-mentioned electrolytic cell has bubbles generated by the anode or cathode used in the above-mentioned electrolysis and rises in the vertical direction in the above-mentioned electrolyte solution. , can reach the structure of the liquid level of the aforementioned electrolyte.

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