KR20220065825A - Fluorine gas manufacturing method and fluorine gas manufacturing apparatus - Google Patents

Abstract

A method for producing fluorine gas capable of suppressing clogging of piping or valves by mist is provided. An electrolysis step of performing electrolysis of the electrolyte in the electrolyzer, a water concentration measurement step of measuring the water concentration in the electrolyte during electrolysis, and a flow path from the inside of the electrolytic cell to the outside of the fluid generated inside the electrolyzer during the electrolysis of the electrolyte The fluorine gas is produced by a method comprising a sending process through the In the air sending process, the flow path through which the fluid flows is switched according to the moisture concentration in the electrolyte measured in the moisture concentration measurement process, and when the moisture concentration in the electrolyte measured in the moisture concentration measurement process is below a preset reference value, 1 The fluid is sent to the first flow path for sending the fluid to the outside, and when it is larger than a preset reference value, the fluid is sent to the second flow path for sending the fluid from the inside of the electrolytic cell to the second outside. The preset reference value is a numerical value within the range of 0.1 mass % or more and 0.8 mass % or less.

Description

Fluorine gas manufacturing method and fluorine gas manufacturing apparatus

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

Fluorine gas can be synthesized (electrolytic synthesis) by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride. Since mist (for example, mist of electrolyte solution) is also generated along with the fluorine gas by electrolysis of the electrolytic solution, the mist accompanies the fluorine gas discharged from the electrolytic cell. Mist accompanying fluorine gas becomes powder, and there exists a possibility of clogging the piping and valve used for fluorine gas sending. Therefore, there are cases where it is inevitable to stop or stop the operation for producing the fluorine gas, which has become a hindrance to the continuous operation in the production of the fluorine gas by the electrolytic method.

In order to suppress the clogging of piping or a valve by mist, the technique which heats the fluorine gas accompanying mist or the piping through which the said gas passes is disclosed by patent document 1 more than melting|fusing point of electrolyte solution. In addition, Patent Document 2 discloses a gas generating device having a gas diffusion unit that is a space for taking mist roughly, and a filler accommodating unit for accommodating a filler for adsorbing the mist.

Japanese Patent Publication No. 5584904 Japanese Patent Publication No. 5919824

However, the technique which can suppress more effectively the blockage of piping and a valve by mist has been desired.

An object of the present invention is to provide a fluorine gas manufacturing method and a fluorine gas manufacturing apparatus capable of suppressing clogging of piping or valves by mist.

In order to solve the above problems, one aspect of the present invention is as follows [1] to [5].

[1] A method for producing fluorine gas by electrolyzing an electrolyte containing hydrogen fluoride and metal fluoride to produce fluorine gas,

an electrolysis step of performing the electrolysis in an electrolyzer;

a water concentration measurement step of measuring the water concentration in the electrolyte solution during the electrolysis;

and a sending process of sending a fluid generated inside the electrolyzer from the inside of the electrolytic cell to the outside through a flow path during the electrolysis of the electrolyte;

In the air sending process, the flow path through which the fluid flows is switched according to the moisture concentration in the electrolyte measured in the moisture concentration measuring process, and the moisture concentration in the electrolyte measured in the moisture concentration measuring process is less than or equal to a preset reference value. sends the fluid to a first flow path for sending the fluid from the inside of the electrolytic cell to the first outside, and when it is greater than the preset reference value, the fluid into a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside is to send

The method for producing a fluorine gas, wherein the preset reference value is a numerical value within the range of 0.1% by mass or more and 0.8% by mass or less.

[2] The method for producing a fluorine gas according to [1], wherein the metal fluoride is a fluoride of at least one metal selected from potassium, cesium, rubidium, and lithium.

[3] [1] or [2] wherein the anode used in the electrolysis is a carbonaceous electrode formed of at least one carbon material selected from diamond, diamond-like carbon, amorphous carbon, graphite, and glassy carbon The method for producing a fluorine gas described in.

[4] Any one of [1] to [3], wherein the electrolyzer has a structure in which bubbles generated in the anode or cathode used in the electrolysis rise in the vertical direction in the electrolyte to reach the liquid level of the electrolyte The method for producing a fluorine gas according to claim.

[5] A fluorine gas production apparatus for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride,

an electrolyzer in which the electrolysis is performed by receiving the electrolyte;

a water concentration measuring unit for measuring the water concentration in the electrolyte in the electrolyzer during the electrolysis;

and a flow path for sending a fluid generated inside the electrolyzer from the inside of the electrolytic cell to the outside during the electrolysis of the electrolyte;

The flow path has a first flow path for sending the fluid from the inside of the electrolytic cell to the first outside, and a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside, and is measured by the moisture concentration measuring unit and a flow path switching unit for switching a flow path through which the fluid flows to the first flow path or the second flow path according to the moisture concentration in the electrolyte solution,

The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the water concentration in the electrolyte measured by the water concentration measurement unit is less than or equal to a preset reference value, and when greater than the preset reference value, the to send the fluid from the inside of the electrolyzer to the second flow path,

The preset reference value is a fluorine gas manufacturing apparatus that is a numerical value within the range of 0.1 mass % or more and 0.8 mass % or less.

ADVANTAGE OF THE INVENTION According to this invention, when electrolyzing the electrolyte solution containing hydrogen fluoride and a metal fluoride and manufacturing a fluorine gas, the clogging of piping and a valve by mist can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining an example of the light scattering detector used as an average particle diameter measuring part in the fluorine gas manufacturing apparatus by one Embodiment of this invention.
It is a schematic diagram explaining an example of the fluorine gas manufacturing apparatus by one Embodiment of this invention.
It is a schematic diagram explaining an example of the mist removal apparatus used as a mist removal part in the fluorine gas manufacturing apparatus of FIG.
FIG. 4 is a schematic diagram illustrating a first modified example of the fluorine gas production apparatus of FIG. 2 .
FIG. 5 is a schematic diagram illustrating a second modified example of the fluorine gas production apparatus of FIG. 2 .
6 is a schematic diagram for explaining a third modified example of the fluorine gas production apparatus of FIG. 2 .
7 is a schematic diagram for explaining a fourth modified example of the fluorine gas production apparatus of FIG. 2 .
FIG. 8 is a schematic diagram for explaining a fifth modified example of the fluorine gas production apparatus of FIG. 2 .
9 is a schematic diagram for explaining a sixth modified example of the fluorine gas production apparatus of FIG. 2 .
FIG. 10 is a schematic diagram for explaining a seventh modification of the fluorine gas production apparatus of FIG. 2 .
11 is a schematic diagram for explaining an eighth modification of the fluorine gas production apparatus of FIG. 2 .
FIG. 12 is a schematic diagram for explaining a ninth modification of the fluorine gas production apparatus of FIG. 2 .
13 is a schematic diagram for explaining a tenth modification of the fluorine gas production apparatus of FIG. 2 .
14 is a graph showing the particle size distribution of mist contained in the fluid generated at the anode in Reference Example 1;
15 is a graph showing the correlation between the average particle diameter of mist and the amount of mist generated at the anode in Reference Example 1. FIG.
It is a graph which shows the relationship between the average particle diameter of mist, and the water concentration in electrolyte solution in Reference Example 1. FIG.

An embodiment of the present invention will be described below. In addition, this embodiment shows an example of this invention, and this invention is not limited to this embodiment. In addition, it is possible to add various changes or improvement to this embodiment, and the form which added such a change or improvement can also be included in this invention.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined about the mist which causes blockage of piping or a valve in the electrolytic synthesis of a fluorine gas. "Mist" in the present invention is liquid microparticles or solid microparticles generated together with fluorine gas in an electrolytic cell by electrolysis of an electrolytic solution. Specifically, the fine particles of the electrolyte solution, the fine particles of the solid in which the particles of the electrolyte solution are phase-changed, and the solid particles formed by the reaction of fluorine gas with the members constituting the electrolytic cell (metal forming the electrolytic cell, packing for the electrolytic cell, carbon electrode, etc.) am.

The present inventors measured the average particle diameter of mist contained in the fluid generated inside the electrolysis tank at the time of electrolysis of electrolyte solution, and confirmed that the average particle diameter of mist changed with time. In addition, as a result of intensive examination, it was found that there is a correlation between the average particle diameter of mist and the moisture concentration in the electrolyte at the time of electrolysis, and the correlation between the average particle diameter of mist and the likelihood of clogging of the pipe or valve through which the fluid is transmitted found this one And, by designing a flow path for sending the fluid generated inside the electrolyzer according to the moisture concentration in the electrolyte during electrolysis, clogging of piping or valves can be suppressed, and the frequency of interruption or stoppage of the operation for producing fluorine gas is reduced. What could be done was found, and it came to complete this invention. An embodiment of the present invention will be described below.

The method for producing fluorine gas of 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. A water concentration measuring step of measuring the water concentration in the electrolytic solution, and a sending step of sending a fluid generated inside the electrolyzer during the electrolysis of the electrolytic solution through a flow path from the inside of the electrolytic cell to the outside.

In the air sending process, the flow path through which the fluid flows is switched according to the moisture concentration in the electrolyte measured in the moisture concentration measuring process. That is, when the moisture concentration in the electrolyte measured in the moisture concentration measurement process is less than or equal to a preset reference value, the fluid is sent from the inside of the electrolyzer to the first flow path that sends the fluid to the first outside, and when it is greater than the preset reference value, the inside of the electrolyzer It is adapted to send the fluid to the second flow path for sending the fluid to the second outside. In addition, 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 production apparatus of this embodiment is a fluorine gas production apparatus that electrolyzes an electrolyte solution containing hydrogen fluoride and metal fluoride to produce fluorine gas, and an electrolyzer in which electrolysis is performed by accommodating the electrolyte solution; a water concentration measuring unit for measuring the water concentration in the electrolytic solution in the electrolytic cell; and a flow path for sending a fluid generated inside the electrolytic cell during electrolysis of the electrolytic solution from the inside of the electrolytic cell to the outside.

The flow path has a first flow path for sending the fluid from the inside of the electrolytic cell to the first outside, and a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside. In addition, this flow path has a flow path switching unit for switching the flow path through which the fluid flows to the first flow path or the second flow path according to the moisture concentration in the electrolyte measured by the water concentration measuring unit.

The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the water concentration in the electrolyte measured by the water concentration measuring unit is less than or equal to a preset reference value; It is meant to send fluid. In addition, 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 fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment, the flow path through which a fluid flows is switched to the 1st flow path or the 2nd flow path according to the moisture concentration in the electrolyte solution at the time of electrolysis, As a result, the average particle diameter of mist As a result, the flow path is switched to the first flow path or the second flow path, so that the flow path is less likely to be blocked by mist. Therefore, the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment can suppress the clogging of piping and valves by mist when manufacturing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride. . Therefore, it is possible to reduce the frequency of interruption or stop of the operation for producing the fluorine gas, and it is easy to perform continuous operation. Therefore, fluorine gas can be manufactured economically.

In addition, in the fluorine gas production method and fluorine gas production apparatus of the present embodiment, the measurement of the moisture concentration in the electrolyte may be performed on the electrolyte in the anode chamber in which the anode is disposed, or in the electrolyte in the cathode chamber in which the cathode is disposed. also good In addition, the measurement of the water concentration in electrolyte solution may be performed constantly during electrolysis, may be performed regularly with fixed intervals, and may be performed irregularly and from time to time. In addition, although the 1st flow path and the 2nd flow path are separate flow paths, the 1st exterior and the 2nd exterior may be a separate location, and the same location may be sufficient as them.

Here, an example of the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment is shown. The first flow path is a flow path for sending the fluid from the inside of the electrolytic cell to a fluorine gas sorting part that sorts and withdraws fluorine gas from the fluid via a mist removing part that removes mist from the fluid. The second flow path is a flow path for sending the fluid from the inside of the electrolytic cell to the fluorine gas sorting unit without passing through the mist removing unit. That is, when the moisture concentration in the electrolyte is less than or equal to a preset reference value, the fluid is sent to the mist removal unit provided in the first flow path, and when it is greater than the preset reference value, the fluid is not sent to the mist removal unit. In this example, the fluorine gas separation unit corresponds to the first exterior and the second exterior, and the first exterior and the second exterior are the same location, but the first exterior and the second exterior may be located at separate locations.

And the 2nd flow path has a blockage suppression mechanism which suppresses blockage of the 2nd flow path by mist. Although the blockage suppression mechanism will not be specifically limited if blockage of the 2nd flow path by mist can be suppressed, For example, the following are mentioned. That is, large-diameter piping, inclined piping, a rotating screw, and an airflow generator can be illustrated, and these may be used in combination.

More specifically, by configuring at least a part of the second flow path with a pipe having a larger diameter than that of the first flow path, it is possible to suppress clogging of the second flow path by mist. Moreover, blockage of the 2nd flow path by mist can be suppressed by comprising at least a part of the 2nd flow path by the piping which is inclined with respect to a horizontal direction and extends in the downward direction from an upstream side toward a downstream side.

Moreover, by providing the inside of the 2nd flow path with the rotating screw which sends the mist accumulated in the inside of the 2nd flow path to an upstream or downstream, blockage of the 2nd flow path by mist can be suppressed. Moreover, by providing in the 2nd flow path the airflow generating apparatus which flows the airflow for raising the flow velocity of the fluid which flows in the 2nd flow path, blockage of the 2nd flow path by mist can be suppressed. Moreover, you may provide in the 2nd flow path as a blockage suppression mechanism another mist removal part from the mist removal part with which the 1st flow path was equipped.

Since mist is removed from the fluid by the mist removal part, the 1st flow path is difficult to produce clogging by mist, and since the 2nd flow path is provided with the blockage suppression mechanism, it is hard to produce clogging by mist. Therefore, the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment can suppress the clogging of piping and valves by mist when manufacturing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride. . In addition, even if the mist removal unit or blockage suppression mechanism is not provided, the effect of suppressing the clogging of piping or valves by mist is exhibited simply by switching the flow path through which the fluid flows to a separate flow path (first flow path or second flow path) However, the one provided with a mist removal part and a blockage suppression mechanism is excellent in the said effect.

Hereinafter, the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment are demonstrated in more detail.

[Electrolyzer]

There is no particular limitation on the aspect of the electrolytic cell, and any electrolytic cell can be used as long as it can generate fluorine gas by electrolyzing an electrolytic solution containing hydrogen fluoride and metal fluoride.

Usually, the interior of the electrolytic cell is divided by a partition member such as a partition wall into an anode chamber in which an anode is disposed and a cathode chamber in which a cathode is disposed, so that fluorine gas generated from the anode and hydrogen gas generated from the cathode are prevented from mixing.

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

The electrolyte contains hydrogen fluoride and a metal fluoride, and the type of the metal fluoride is not particularly limited, but is preferably a fluoride of at least one metal selected from potassium, cesium, rubidium, and lithium. If the electrolyte contains cesium or rubidium, the specific gravity of the electrolyte increases, so the amount of mist generated during electrolysis is suppressed.

As the electrolytic solution, 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 to 2.5:1. In the case of hydrogen fluoride:potassium fluoride = 2:1, KF·2HF is a typical electrolyte solution, and the melting point of this mixed molten salt is about 72°C. Since this electrolyte solution has corrosive properties, it is preferable to form the part in contact with the electrolyte solution, such as the inner surface of the electrolytic cell, with a metal such as iron, nickel, or Monel (trademark).

In the electrolysis of the electrolyte, a direct current is applied to the anode and the cathode, a gas containing fluorine gas is generated at the anode, and a gas containing hydrogen gas is generated at the cathode. In addition, since hydrogen fluoride in the electrolyte has vapor pressure, the gases generated from the anode and the cathode are accompanied by hydrogen fluoride, respectively. Moreover, in manufacture of the fluorine gas by electrolysis of electrolyte solution, the mist of electrolyte solution contains in the gas which generate|occur|produces by electrolysis. Accordingly, the gas phase portion of the electrolytic cell consists of a gas generated by electrolysis and a mist of hydrogen fluoride and electrolyte solution. Therefore, what is discharged from the inside of the electrolyzer to the outside consists of a gas generated by electrolysis, a mist of hydrogen fluoride, and an electrolyte solution, and in the present invention, this is referred to as a "fluid".

Further, since hydrogen fluoride in the electrolytic solution is consumed by the progress of electrolysis, a pipe for continuously or intermittently supplying and replenishing hydrogen fluoride to the electrolytic cell may be connected to the electrolytic cell. 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 reason mist generate|occur|produces at the time of electrolysis of electrolyte solution is as follows. The temperature of the electrolyte solution at the time of electrolysis is adjusted to 80-100 degreeC, for example. Since the melting point of KF·2HF is 71.7°C, when the temperature is adjusted to the above, the electrolyte is in a liquid state. Gas bubbles generated at both electrodes of the electrolytic cell rise in the electrolyte and burst at the liquid level of the electrolyte. At this time, a part of the electrolyte is discharged into the gas phase.

Since the temperature of the gas phase is lower than the melting point of the electrolyte, the discharged electrolyte undergoes a phase change to a state of minute powder. This powder is considered to be a mixture KF·nHF of potassium fluoride and hydrogen fluoride. This powder becomes mist by riding the flow of gas generated otherwise, and forms the fluid generated in the electrolyzer. It is difficult to effectively remove such mist by general countermeasures such as installation of a filter for reasons such as having adhesiveness.

In addition, although the amount of generation is small, the fine powder of the organic compound may be generated as a mist by the reaction between the carbonaceous electrode serving as the anode and the fluorine gas generated in the electrolysis. When it demonstrates in detail, contact resistance generate|occur|produces in many cases where electric current is supplied to a carbonaceous electrode, and it may become a temperature higher than the temperature of electrolyte solution by Joule heat. Therefore, the soot-like organic compound CFx may be generated as a mist when carbon forming the carbonaceous electrode and fluorine gas react.

In addition, it is preferable that the electrolyzer has a structure in which the bubbles generated in the anode or the cathode used in the electrolysis rise vertically in the electrolyte to reach the liquid level of the electrolyte. When the bubble has a structure in which it is difficult to rise in the electrolyte solution in a vertical direction and rises in a direction inclined with respect to the vertical direction, a plurality of bubbles are aggregated and large bubbles are easily generated. As a result, since large bubbles reach the liquid level of the electrolytic solution and burst, the amount of mist generated tends to increase. If the bubble rises in the vertical direction in the electrolyte, if it has a structure that can reach the liquid level of the electrolyte, small bubbles will reach the liquid level of the electrolyte and burst, so the amount of mist generated is likely to decrease.

[Average particle diameter measurement unit]

Although the fluorine gas manufacturing apparatus of this embodiment may be equipped with the average particle diameter measuring part which measures the average particle diameter of the mist contained in a fluid, this average particle diameter measuring part is light scattering which measures an average particle diameter by the light scattering method. It may be comprised by a detector. Since the light scattering detector can measure the average particle diameter of the mist in the fluid which flows through a flow path while continuously operating a fluorine gas manufacturing apparatus, it is preferable as an average particle diameter measuring part.

An example of a light scattering detector is demonstrated, referring FIG. The light scattering detector of FIG. 1 is a light scattering detector usable as an average particle diameter measuring unit in the fluorine gas production apparatus of the present embodiment (eg, the fluorine gas production apparatus of FIGS. 2 and 4 to 13 described later). That is, when an electrolyte solution containing hydrogen fluoride and metal fluoride is electrolyzed inside the electrolyzer of a fluorine gas manufacturing apparatus to produce fluorine gas, a light scattering detector that measures the average particle diameter of the mist contained in the fluid generated inside the electrolytic cell am.

The light scattering detector may be connected to the fluorine gas production device, and the fluid may be sent from the inside of the electrolyzer to the light scattering detector to measure the average particle diameter of the mist, and the fluid from the inside of the electrolyzer without connecting the light scattering detector and the fluorine gas production device may be taken out and introduced into a light scattering detector to measure the average particle diameter of the mist.

The light scattering detector of FIG. 1 includes a sample chamber 1 accommodating a fluid F, a light source 2 irradiating light L for measuring light scattering to the fluid F in the sample chamber 1, and the light The scattered light detection unit 3 for detecting the scattered light S generated when the light L for scattering measurement is scattered by the mist M in the fluid F, is installed in the sample chamber 1 and is in contact with the fluid F and a transparent window 4A through which the light L for measuring light scattering is transmitted, and a transparent window 4B installed in the sample chamber 1 and in contact with the fluid F through which the scattered light S is transmitted. . The transparent windows 4A and 4B are formed 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). there is.

Light L (for example, laser light) for measuring light scattering generated from the light source 2 passes through the converging lens 6 and the transparent window 4A of the sample chamber 1 into the sample chamber 1 . It is irradiated to the fluid (F) accommodated in the sample chamber (1). At this time, if a material that reflects light, such as mist (M), exists in the fluid (F), the light (L) for measuring light scattering is reflected and scattered. A part of the scattered light (S) generated by the light (L) for measuring light scattering is scattered by the mist (M) passes through the transparent window (4B) of the sample chamber (1) and is drawn out from the sample chamber (1), It enters the scattered light detection unit 3 through the condensing lens 7 and the throttle 8 . At this time, the average particle diameter of the mist M can be known from the information obtained from the scattered light S. In addition, the average particle diameter obtained here is a number average particle diameter. As the scattered light detection unit 3, for example, an aerosol spectrometer welas (registered trademark) digital 2000 manufactured by PALAS can be used.

The transparent windows 4A and 4B are in contact with the fluid F, but since the fluid F contains highly reactive fluorine gas, it is necessary to form the transparent windows 4A and 4B with a material that is difficult to be corroded by the fluorine gas. there is As a material for forming the transparent windows 4A and 4B, at least one selected from diamond, calcium fluoride, potassium fluoride, silver fluoride, barium fluoride, and potassium bromide can be used. When the transparent windows 4A and 4B are made of the above material, deterioration due to contact with the fluid F can be suppressed.

Further, a film made of the above material coated on the surface of glass such as quartz may be used as the transparent windows 4A and 4B. Since the portion in contact with the fluid F is coated with the film made of the above material, deterioration due to contact with the fluid F can be suppressed while reducing cost. The transparent windows 4A and 4B may be a laminate in which the surface in contact with the fluid F is made of the above material and the other parts are formed of ordinary glass such as quartz.

The material of parts other than the transparent windows 4A and 4B of the light scattering detector is not particularly limited as long as it has corrosion resistance to fluorine gas. For example, Monel (trademark), Hastelloy (trademark), which are copper-nickel alloys , it is preferable to use a metal material such as stainless steel.

[Average particle diameter of mist and moisture concentration in electrolyte]

The present inventors measured the average particle diameter of the mist which generate|occur|produces at the time of manufacture of the fluorine gas by electrolysis of electrolyte solution using the light scattering detector. An example of the result will be described. After the anode of the fluorine gas production apparatus was replaced with a new anode or the electrolytic cell was filled with a new electrolyte, electrolysis was started, and the average particle diameter of mist in the fluid generated from the anode for a certain period immediately after the start of electrolysis was measured. As a result, the average particle diameter of the mist was 0.5-2.0 micrometers. After that, when a sufficient time elapses after continuing the electrolysis, the electrolysis starts to become stable, but the average particle diameter of the mist in the fluid at the time of this stable electrolysis was about 0.2 µm.

In this way, a mist having a relatively large particle diameter is generated from immediately after the start of electrolysis to the time of stable electrolysis. When a fluid containing a large mist immediately after the start of electrolysis flows through a pipe or a valve, the mist adsorbs to the inner surface of the pipe or valve, and clogging of the pipe or valve tends to occur.

On the other hand, the particle diameter of the mist which generate|occur|produces at the time of stable electrolysis is comparatively small. These small mists are difficult to cause sedimentation or deposition in the fluid, so they can flow through pipes or valves stably. For this reason, at the time of stable electrolysis, the possibility that the fluid which consists of mist and the gas generated from an electrode will cause blockage of a pipe|tube or a valve is comparatively low. In addition, the time from immediately after the start of electrolysis to the time of stable electrolysis is usually 25 hours or more and 200 hours or less. In addition, from immediately after the start of electrolysis to the time of stable electrolysis, approximately 40 kAh or more of electricity per 1000 L of the electrolytic solution is required.

Moreover, the present inventors discovered that there existed a close relationship between the average particle diameter of mist and the water concentration in electrolyte solution. Usually, the water concentration in electrolyte solution is large at the time of electrolysis start, and shows a value larger than 1.0 mass %. The average particle diameter of the mist at this time is larger than 0.4 micrometer. Then, as electrolysis is continued, the water concentration in electrolyte solution will fall, and when it will be 0.3 mass % or less, the average particle diameter of mist will be 0.4 micrometer or less.

In this way, since there is a correlation between the average particle diameter of the mist and the moisture concentration in the electrolyte, the moisture concentration in the electrolyte is measured instead of the average particle diameter of the mist during electrolysis, and the measurement result can be used for switching the flow path. That is, if the moisture concentration in the electrolyte is measured at a predetermined timing during electrolysis, the flow path through which the fluid generated by the electrolysis flows at the predetermined timing can be appropriately switched according to the measurement result.

The transition of the moisture concentration in the electrolyte decreases depending on the magnitude of the current value and the amount of current (the product of the current value and the electrolysis time). The higher the current value, the faster the decrease in moisture concentration. However, when a carbonaceous electrode that produces an anode effect, in which the voltage of the anode rises rapidly, is used for the anode, the anode current density is less than 0.1A/cm2. . The water concentration may be decreased while the current density is constant, or the water concentration may be decreased while gradually increasing the current density.

The present inventors have invented the fluorine gas manufacturing method and the fluorine gas manufacturing apparatus which have a structure in which the flow path through which a fluid flows according to the moisture concentration in the electrolyte solution at the time of electrolysis can be switched based on this knowledge. The fluorine gas production apparatus of this embodiment has a first flow path and a second flow path, and a flow path used for conveying the fluid is selected from among the two flow paths using a flow path switching unit (eg, a switching valve). good to be

Alternatively, the fluorine gas production apparatus of the present embodiment has two flow passages and a movement replacement mechanism for moving and replacing the electrolytic cell, and selects a flow passage used for conveying the fluid from among the two flow passages, and selects a flow passage near the flow passage. The flow path may be switched by moving and connecting the electrolytic cell.

Since it has a 1st flow path and a 2nd flow path as mentioned above, even while one flow path is blocked|blocked and cleaning, the other flow path is opened and the fluorine gas manufacturing apparatus can be continuously operated.

According to the investigation by the present inventors, mist with a relatively large average particle diameter is generated from immediately after the start of electrolysis to the time of stable electrolysis. Since mist with a relatively small average particle diameter is generated when time elapses at the time of stable electrolysis, the flow path may be switched so as to send the fluid to the first flow path having the mist removal unit.

The flow path is switched according to the measured moisture concentration in the electrolyte, but the flow path is switched based on a preset reference value. An appropriate reference value for the average particle diameter of the mist generated at the anode differs for each device, but is, 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 correlation between the average particle diameter of the mist and the moisture concentration in the electrolyte, an appropriate reference value for the moisture concentration in the electrolyte is 0.1% by mass or more and 0.8% by mass or less, preferably 0.2% by mass or more and 0.6% by mass or less, more preferably 0.3 % by mass. When the moisture concentration in the electrolyte is greater than the reference value, the fluid can be sent to the second flow path, and when the water concentration is less than the reference value, the fluid can be sent to the first flow path.

The water concentration in the electrolytic solution can be measured, for example, by the Karl Fischer method. Alternatively, the water concentration in the electrolytic solution can also be determined by heating the electrolytic solution to, for example, 250°C or higher and 400°C or lower, and measuring the amount of water in the generated gas by infrared spectroscopy, for example. Since the solid electrolyte solution hardly dissolves in the detection solution used in the Karl Fischer method, a separate solvent for dissolving the solid electrolyte solution is required, but there are few solvents that have high solubility in the solid electrolyte solution. Therefore, since it is difficult to perform a Karl Fischer analysis by dissolving a large amount of a solid electrolyte, the Karl Fischer method is suitable for analysis of a solid electrolyte having a high water content. On the other hand, the method of heating a solid electrolyte and measuring the amount of water in the generated gas requires a longer analysis time than the Karl Fischer method, but can analyze the water concentration in the electrolyte with high precision.

In addition, the fluid (the main component is hydrogen gas) generated from the cathode contains, for example, 20 to 50 µg of powder per unit volume (1 liter) (calculated assuming that the specific gravity of the mist is 1.0 g/mL), , The average particle diameter of this powder is about 0.1 μm, and has a distribution of ±0.05 μm.

In the case of the fluid generated at the cathode, no significant difference was observed in the particle size distribution of the generated powder depending on the water concentration in the electrolytic solution. Since the mist contained in the fluid generated from the cathode has an average particle diameter smaller than that of the mist contained in the fluid generated from the anode, it is difficult to cause clogging of pipes or valves compared to the mist contained in the fluid generated from the anode. Therefore, the mist contained in the fluid generated at the cathode may be removed from the fluid using an appropriate removal method.

An example of the fluorine gas manufacturing apparatus of this embodiment is demonstrated in detail, referring FIG. Although the fluorine gas manufacturing apparatus of FIG. 2 is an example provided with two electrolyzers, 1 group may be sufficient as it, 3 or more groups may be sufficient as it, for example, 10-15 groups may be sufficient as it.

The fluorine gas production apparatus shown in FIG. 2 includes electrolytic cells 11 and 11 in which electrolysis is performed by accommodating the electrolyte 10 therein, and an anode 13 disposed inside the electrolytic cell 11 and immersed in the electrolyte 10 . ) and a cathode 15 disposed inside the electrolytic cell 11 and immersed in the electrolytic solution 10 and disposed to face the anode 13 .

The inside of the electrolytic cell 11 is extended vertically downward from the ceiling surface of the inside of the electrolytic cell 11, and the lower end thereof is immersed in the electrolyte 10 by a partition wall 17, the anode chamber 22 and the cathode chamber ( 24) is partitioned. 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 by the partition wall 17 , and is located above the lower end of the partition wall 17 in the electrolyte solution 10 . The portion on the side is separated by the partition wall 17 , but the portion of the electrolyte 10 on the lower side than the lower end of the partition wall 17 is not directly separated by the partition wall 17 but is continuous.

In addition, the fluorine gas production apparatus shown in FIG. 2 includes a water concentration measuring unit 36 that measures the water concentration in the electrolyte 10 in the electrolytic cell 11 at the time of electrolysis of the electrolyte 10 , and electricity of the electrolyte 10 . A first average particle diameter measuring unit 31 for measuring the average particle diameter of the mist contained in the fluid generated inside the electrolytic cell 11 during decomposition, and a first mist removing unit 32 for removing the mist from the fluid; , a fluorine gas separator (not shown) for sorting and withdrawing fluorine gas from the fluid, and a flow path for sending the fluid from the inside of the electrolytic cell 11 to the fluorine gas sorting part.

In addition, this flow path includes a first flow path for sending a fluid from the inside of the electrolytic cell 11 to the fluorine gas sorting unit via the first mist removing unit 32 and an electrolytic cell (without passing through the first mist removing unit 32) ( 11) has a second flow path for sending the fluid to the fluorine gas sorting unit from the inside. In addition, this flow path has a flow path switching unit that switches the flow path through which the fluid flows to the first flow path or the second flow path according to the moisture concentration in the electrolyte 10 measured by the water concentration measuring unit 36 . That is, a flow path switching unit is provided in the middle of the flow path extending from the electrolytic cell 11, and the flow path through which the fluid flows can be changed by the flow path switching unit.

The flow path switching unit sends the fluid from the inside of the electrolytic cell 11 to the first flow path when the water concentration in the electrolyte 10 measured by the water concentration measuring unit 36 is less than or equal to a preset reference value, and is greater than the preset reference value. In this case, the fluid is sent from the inside of the electrolytic cell 11 to the second flow path. And the 2nd flow path has a blockage suppression mechanism which suppresses blockage by mist of the 2nd flow path.

That is, when the moisture concentration in the electrolyte solution 10 is less than or equal to the reference value, the fluid is sent to the first flow path that connects the electrolytic cell 11 and the fluorine gas sorting unit and the first mist removal unit 32 is installed, and in the electrolytic solution 10 When the moisture concentration is larger than the reference value, the fluid is sent to the second flow path that connects the electrolytic cell 11 and the fluorine gas sorting unit and is provided with a blockage suppression mechanism.

As the moisture concentration measuring unit 36 , for example, a Karl Fischer moisture measuring device can be used.

As the 1st mist removal part 32, the mist removal apparatus which can remove mist with an average particle diameter of 0.4 micrometer or less from a fluid is used, for example. Although it does not specifically limit about the kind of mist removal apparatus, ie, the method of removing mist, Since the average particle diameter of mist is small, for example, an electrostatic precipitator, a venturi scrubber, and a filter can be used as a mist removal apparatus.

It is preferable to use the mist removal apparatus shown in FIG. 3 among the said mist removal apparatus. The mist removal apparatus shown in FIG. 3 is a scrubber type mist removal apparatus which uses liquid hydrogen fluoride as a circulating liquid. The mist removal apparatus shown in FIG. 3 can remove the mist with an average particle diameter of 0.4 micrometer or less from a fluid efficiently. In addition, although liquid hydrogen fluoride is used as the circulating fluid, it is preferable to cool the circulating fluid in order to lower the concentration of hydrogen fluoride in the fluorine gas, so that the concentration of hydrogen fluoride in the fluorine gas can be adjusted by controlling the cooling temperature.

The fluorine gas manufacturing apparatus shown in FIG. 2 is demonstrated in more detail. The first pipe 41 for sending the fluid generated in the anode chamber 22 of the electrolytic cell 11 (hereinafter, may be referred to as “anode gas”) to the outside is connected to the electrolytic cell 11 and the fourth pipe 44 . is connected, and the anode gas discharged from the two electrolytic cells 11 and 11 is sent to the fourth pipe 44 through the first pipe 41 to be mixed. In addition, the main component of the anode gas is fluorine gas, and the subcomponents are mist, hydrogen fluoride, carbon tetrafluorocarbon, oxygen gas, and water.

The 4th pipe 44 is connected to the 1st mist removal part 32, and since the anode gas is sent to the 1st mist removal part 32 by the 4th pipe 44, mist and hydrogen fluoride in the anode gas are removed. It is removed from the anode gas by the 1st mist removal part 32. The anode gas from which mist and hydrogen fluoride have been removed is discharged from the first mist removal unit 32 to a fluorine gas sorting unit (not shown) through the sixth pipe 46 connected to the first mist removal unit 32 . has been Then, the fluorine gas is separated from the anode gas by the fluorine gas sorting unit and taken out.

In addition, the 8th pipe 48 is connected to the 1st mist removal part 32, and hydrogen fluoride of the liquid which is a circulating fluid is supplied to the 1st mist removal part 32 through the 8th pipe 48, there is. Moreover, the 9th piping 49 is connected to the 1st mist removal part 32. As shown in FIG. The ninth pipe 49 is connected to the electrolytic cells 11 and 11 through the third pipe 43, and is used for the removal of mist in the first mist removal unit 32, and a circulating fluid containing mist (liquid hydrogen fluoride) is returned to the electrolytic cells 11 and 11 from the first mist removal unit 32 .

The cathode chamber 24 of the electrolytic cell 11 is the same as the anode chamber 22 . That is, the second pipe 42 for sending the fluid (hereinafter, sometimes referred to as “cathode gas”) generated in the cathode chamber 24 of the electrolytic cell 11 to the outside is connected to the electrolytic cell 11 and the fifth pipe ( 45), and the cathode gas discharged from the two electrolytic cells 11 and 11 is sent to the fifth pipe 45 through the second pipe 42 to be mixed. In addition, the main component of the cathode gas is hydrogen gas, and the subcomponents are mist, hydrogen fluoride, and water.

Since the cathode gas contains a fine mist and 5 to 10% by volume of hydrogen fluoride, it is not preferable to discharge it to the atmosphere as it is. Therefore, the 5th pipe 45 is connected to the 2nd mist removal part 33, cathode gas is sent to the 2nd mist removal part 33 by the 5th pipe 45, and mist in the cathode gas and hydrogen fluoride is removed from the cathode gas by the second mist removal unit 33 . Cathode gas from which mist and hydrogen fluoride were removed is discharged|emitted to the atmosphere from the 2nd mist removal part 33 by the 7th piping 47 connected to the 2nd mist removal part 33. As shown in FIG. Although it does not specifically limit about the kind of 2nd mist removal part 33, ie, the method of removing mist, The mist removal apparatus of the scrubber type which uses aqueous alkali solution as a circulating liquid can be used.

The first pipe 41, the second pipe 42, the fourth pipe 44, and the pipe diameter and the installation direction of the fifth pipe 45 (meaning the direction in which the pipe extends, for example, the vertical direction, horizontal direction) is not particularly limited, but the first pipe 41 and the second pipe 42 are installed to extend from the electrolytic cell 11 in the vertical direction, and the first pipe 41 and the second pipe 42 ), it is desirable to set the pipe diameter so that the flow velocity of the fluid flowing through it is 30 cm/sec or less in the standard state. Then, even when the mist contained in the fluid falls by its own weight, since the mist settles in the electrolytic cell 11, it is difficult to cause clogging of the inside of the first pipe 41 and the second pipe 42 by the powder. .

In addition, the fourth pipe 44 and the fifth pipe 45 are installed to extend in the horizontal direction, and the flow rate of the fluid flowing through the fourth pipe 44 and the fifth pipe 45 is the first pipe 41 . And it is preferable to set it as the pipe diameter which becomes about 1 to 10 times faster than the case of the 2nd pipe 42.

In addition, a second bypass pipe 52 for sending the anode gas to the outside of the electrolytic cell 11 is provided separately from the first pipe 41 . That is, the second bypass pipe 52 communicates with the electrolytic cell 11 and the first bypass pipe 51 , and the anode gas discharged from the two electrolytic cells 11 and 11 is transferred to the second bypass pipe 52 . ) is sent to the first bypass pipe 51 to be mixed. Further, the anode gas is discharged to a fluorine gas sorting unit (not shown) through the first bypass pipe 51 . Then, the fluorine gas is separated from the anode gas by the fluorine gas sorting unit and taken out. The fluorine gas sorting part connected to the first bypass pipe 51 and the fluorine gas sorting part connected to the sixth pipe 46 may be the same or different.

The pipe diameter or installation direction of the second bypass pipe 52 is not particularly limited, but the second bypass pipe 52 is installed to extend from the electrolytic cell 11 in the vertical direction, and the second bypass pipe ( 52), it is preferable to set it as the pipe diameter at which the flow velocity of the fluid is 30 cm/sec or less in the standard state.

In addition, the first bypass pipe 51 is installed to extend along the horizontal direction. And, the first bypass pipe 51 is a pipe having a larger diameter than the fourth pipe 44, and the pipe diameter of the first bypass pipe 51 is a first bypass pipe due to the deposition of powder. (51) has a size that is difficult to cause blockage. The blockage suppression mechanism is comprised by the 1st bypass pipe 51 being the pipe of a pipe diameter larger than the 4th pipe 44. As shown in FIG.

The pipe diameter of the first bypass pipe 51 is preferably more than 1.0 times and 3.2 times that of the fourth pipe 44, more preferably 1.05 times or more and 1.5 times or less. That is, the flow passage cross-sectional area of the first bypass pipe 51 is preferably 10 times or less that of the fourth pipe 44 .

As can be seen from the above description, the first flow path is constituted by the first pipe 41 and the fourth pipe 44 , and is connected to the first bypass pipe 51 and the second bypass pipe 52 . The second flow path is constituted by And the blockage suppression mechanism is provided in the 1st bypass pipe 51 which comprises the 2nd flow path.

Next, the flow path switching unit will be described. The first piping 41 is provided with a first piping valve 61, respectively. And by switching the 1st piping valve 61 to an open state or a closed state, it is possible to control whether or not the anode gas is sent from the electrolytic cell 11 to the 1st mist removal part 32. Moreover, the bypass valve 62 is provided in the 2nd bypass pipe 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 the anode gas is supplied from the electrolytic cell 11 to the first bypass pipe 51 .

In addition, the water concentration measuring unit 36 is installed in the electrolytic cell 11, and the electrolytic solution 10 in the electrolytic cell 11 is introduced into the water concentration measuring unit 36 to measure the water concentration in the electrolytic solution 10 during electrolysis. can be measured in The electrolyte solution 10 for measuring the water concentration may be the electrolyte solution 10 on the anode chamber 22 side or the electrolyte solution 10 on the cathode chamber 24 side.

Moreover, between the electrolytic cell 11 and the 1st mist removal part 32, when it demonstrates in detail, it is an intermediate part of the 4th pipe 44, and the 1st average particle is downstream from the connection part with the 1st pipe 41. A diameter measuring unit 31 is provided. And the 1st average particle diameter measuring part 31 measures the average particle diameter of the mist contained in the anode gas which flows through the 4th pipe 44. As shown in FIG. Moreover, the electric power efficiency in manufacture of a fluorine gas can be measured by analyzing the fluorine gas and nitrogen gas contained in the anode gas after measuring the average particle diameter of mist.

Moreover, the same 2nd average particle diameter measuring part 34 is provided also downstream from the intermediate part of the 1st bypass pipe 51 and the connection part with the 2nd bypass pipe 52, and a 2nd average particle The average particle diameter of the mist contained in the anode gas flowing through the 1st bypass pipe 51 is measured by the diameter measuring part 34. As shown in FIG. However, the fluorine gas manufacturing apparatus shown in FIG. 2 does not need to be equipped with the 1st average particle diameter measurement part 31 and the 2nd average particle diameter measurement part 34 .

The moisture concentration measuring unit 36 measures the moisture concentration in the electrolyte 10 in the electrolyzer 11, and when the measurement result is larger than a preset reference value, the bypass valve 62 is opened to the anode gas is sent from the electrolytic cell 11 to the first bypass pipe 51 , and the anode gas is supplied to the fourth pipe 44 and the first mist removal unit 32 with the first pipe valve 61 closed. not to be sent. That is, the anode gas is sent to the second flow path.

On the other hand, when the measurement result is equal to or less than a preset reference value, the first piping valve 61 is opened, the anode gas is sent to the fourth piping 44 and the first mist removal unit 32, and the bypass valve By setting (62) to a closed state, the anode gas is not sent from the electrolytic cell (11) to the first bypass pipe (51). That is, the anode gas is sent to the first flow path.

The said flow path switching part is comprised by the 1st piping valve 61 and the bypass valve 62 so that the above description may show.

As described above, by operating the fluorine gas production apparatus while switching the flow path according to the water concentration in the electrolyte 10 during electrolysis, smooth continuous operation can be performed while suppressing clogging of piping and valves by mist. there is. Therefore, according to the fluorine gas manufacturing apparatus shown in FIG. 2, fluorine gas can be manufactured economically.

For example, you may perform electrolysis, replacing a filter, preparing two or more piping which provided the filter as a mist removal part, and switching suitably.

In addition, it is good to judge the period in which replacement of a filter should be performed frequently and the period in which it is not necessary to perform replacement of a filter frequently based on the measurement of the water concentration in the electrolyte solution 10 at the time of electrolysis. And, if the switching frequency of the piping through which a fluid flows is adjusted appropriately based on the said determination, the operation|movement of a fluorine gas manufacturing apparatus can be continuously performed efficiently.

Next, the modified example of the fluorine gas manufacturing apparatus shown in FIG. 2 is demonstrated.

[First Modification]

The first modification will be described with reference to FIG. 4 . In the fluorine gas production apparatus shown in FIG. 2 , the second bypass pipe 52 connects the electrolytic cell 11 and the first bypass pipe 51 to the fluorine gas production of the first modification shown in FIG. 4 . In the device, the second bypass pipe 52 connects the first pipe 41 and the first bypass pipe 51 . The configuration of the fluorine gas production apparatus of the first modification is substantially the same as that of the fluorine gas production apparatus of FIG. 2 except for the above points, and thus descriptions of the same parts are omitted.

[Second Modification]

A 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 in which one electrolytic cell 11 is provided. The 1st average particle diameter measuring part 31 is provided in the 1st piping 41 instead of the 4th piping 44, and is provided in the upstream of the 1st piping valve 61. Further, the second bypass pipe 52 is not provided, and the first bypass pipe 51 is directly connected to the electrolytic cell 11 without passing through the second bypass pipe 52 .

And since the 1st bypass pipe 51 has a larger diameter compared with the 4th pipe 44, it functions as a blockage suppression mechanism. Moreover, the effect of blockage suppression can further be increased by providing the space for mist accumulating in the downstream end of the 1st bypass pipe 51, for example. As the space for this mist pooling, for example, the downstream end portion of the first bypass pipe 51 is formed with a larger pipe diameter than the central portion in the installation direction (for example, 4 times or more of the pipe diameter of the central portion in the installation direction). and a space formed by forming the downstream end portion of the first bypass pipe 51 in the same shape as a container is mentioned, and the first bypass pipe 51 is blocked by the space for mist pooling. can be suppressed. This aims at the effect of blockage prevention by the large flow path cross-sectional area, and the effect of blockage prevention using the gravity fall of mist by the fall of the linear velocity of a gas flow.

In addition, the bypass valve 62 is provided in the 3rd bypass pipe 53 which connects the 1st bypass pipe 51 and the fluorine gas sorting part (not shown). The configuration of the fluorine gas production apparatus of the second modified example is substantially the same as that of the fluorine gas production apparatus of FIG. 2 except for the above points, and thus descriptions of the same parts are omitted.

[Third modification example]

A third modified example will be described with reference to FIG. 6 . In the fluorine gas production apparatus according to the third modification, the first average particle size measuring unit 31 is provided in the electrolytic cell 11 , and the anode gas inside the electrolytic cell 11 is converted into the first average particle size measuring unit 31 . It is introduced directly into the mist so that the average particle diameter of the mist is measured. The fluorine gas production apparatus according to 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 modified example is substantially the same as that of the fluorine gas production apparatus of the second modified example except for the above points, and thus descriptions of the same parts are omitted.

[Fourth modification]

A fourth modified example will be described with reference to FIG. 7 . The fluorine gas production apparatus of the fourth modification is an example in which the blockage suppression mechanism is different from that of the second modification shown in FIG. 5 . In the fluorine gas production apparatus of the second modified example, the first bypass pipe 51 was provided so as to extend in the horizontal direction, but in the fluorine gas production apparatus of the fourth modified example, the first bypass pipe 51 is disposed in the horizontal direction It is inclined with respect to and extends in a direction descending from the upstream side toward the downstream side. By this inclination, the accumulation of powder inside the 1st bypass pipe 51 is suppressed. The larger the inclination, the greater the effect of suppressing the accumulation of powder.

The angle of inclination of the first bypass pipe 51 is preferably 30 degrees or more, more preferably 40 degrees or more and 60 degrees or less, in a range where the depression from the horizontal plane is smaller than 90 degrees. If clogging of the first bypass pipe 51 is likely to occur, if the inclined first bypass pipe 51 is hammered, the deposits inside the first bypass pipe 51 are easy to move, so clogging can be avoided. can

The configuration of the fluorine gas production apparatus of the fourth modification is substantially the same as that of the fluorine gas production apparatus of the second modification except for the above points, and therefore the description of the same parts is omitted.

[Fifth modification]

A fifth modified example will be described with reference to FIG. 8 . The fluorine gas production apparatus of the fifth modification is an example in which the blockage suppression mechanism is different from that of the third modification shown in FIG. 6 . In the fluorine gas production apparatus of the third modified example, the first bypass pipe 51 was provided so as to extend in the horizontal direction. In the fluorine gas production apparatus of the fifth modified example, the first bypass pipe 51 is disposed in the horizontal direction. It is inclined with respect to and extends in a direction descending from the upstream side toward the downstream side. By this inclination, the accumulation of powder inside the 1st bypass pipe 51 is suppressed. A preferable angle of inclination of the first bypass pipe 51 is the same as in the case of the fourth modification. The configuration of the fluorine gas production apparatus of the fifth modified example is substantially the same as that of the fluorine gas production apparatus of the third modified example except for the above points, and therefore descriptions of similar parts are omitted.

[Sixth Modification]

A 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 that of the second modification shown in FIG. 5 . The electrolytic cell 11 has one anode 13 and two cathodes 15 and 15, and one anode chamber 22 is formed by a cylindrical partition 17 surrounding the one anode 13. and one cathode chamber 24 . The anode chamber 22 is formed to extend upward from the upper surface of the electrolytic cell 11 , and the first bypass pipe 51 is connected to the upper end of the anode chamber 22 of the electrolytic cell 11 . The configuration of the fluorine gas production apparatus of the sixth modified example is substantially the same as that of the fluorine gas production apparatus of the second modified example except for the above points, and therefore the description of the same parts is omitted.

[Seventh Modification]

A 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 pipe 51 is different from that of the sixth modification shown in FIG. 9 . That is, in the fluorine gas production apparatus of the seventh modification, the first bypass pipe 51 is inclined with respect to the horizontal direction as in the fourth and fifth modifications, and descends from the upstream side toward the downstream side. is extended to A preferable angle of inclination of the first bypass pipe 51 is the same as in the case of the fourth modification. The configuration of the fluorine gas production apparatus of the seventh modification is substantially the same as that of the fluorine gas production apparatus of the sixth modification except for the above points, and therefore the description of the same parts is omitted.

[8th modification]

An eighth modification will be described with reference to FIG. 11 . The fluorine gas production apparatus of the eighth modification is an example in which the blockage suppression mechanism is different from that of the second modification shown in FIG. 5 . In the fluorine gas production apparatus according to the eighth modification, the rotation screw 71 constituting the blockage suppression mechanism is provided inside the first bypass pipe 51 . The rotation screw 71 is provided so that its rotation axis is parallel to the longitudinal direction of the first bypass pipe 51 .

And by rotating the rotating screw 71 with the motor 72, the mist accumulated in the inside of the 1st bypass pipe 51 can be sent to an upstream or downstream. Thereby, it is suppressed that the powder is accumulated in the inside of the 1st bypass pipe 51. As shown in FIG. The configuration of the fluorine gas production apparatus of the eighth modification is substantially the same as that of the fluorine gas production apparatus of the second modification except for the above points, and therefore the description of the same parts is omitted.

[Ninth Modification]

A ninth modification will be described with reference to FIG. 12 . The fluorine gas production apparatus of the ninth modification is an example in which the blockage suppression mechanism is different from that of the second modification shown in FIG. 5 . In the fluorine gas production apparatus according to the ninth modification, an airflow generator 73 constituting the blockage suppression mechanism is provided in the first bypass pipe 51 . The airflow generator 73 sends an airflow (for example, an airflow of nitrogen gas) from the upstream side of the 1st bypass pipe 51 toward the downstream side, and the anode gas which flows in the 1st bypass pipe 51 inside increase the flow rate of Thereby, it is suppressed that the powder is accumulated in the inside of the 1st bypass pipe 51. As shown in FIG.

A 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 it is also possible to make the flow rate larger than 10 m/sec, in that case, the pressure loss due to piping resistance in the first bypass pipe 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 be about the same. However, if the difference between the pressure in the anode chamber 22 and the pressure in the cathode chamber 24 becomes too large, the anode gas flows into the partition wall 17 . It flows into the cathode chamber 24 over the fluorine gas, and a reaction between the fluorine gas and the hydrogen gas may occur, which may interfere with the generation of the fluorine gas.

The configuration of the fluorine gas production apparatus of the ninth modification is substantially the same as that of the fluorine gas production apparatus of the second modification except for the above points, and therefore the description of the same parts is omitted.

[10th modification]

A tenth modification will be described with reference to FIG. 13 . In the fluorine gas production apparatus according to the tenth modification, the first average particle size measuring unit 31 is provided in the electrolytic cell 11 , and the anode gas inside the electrolytic cell 11 is converted into the first average particle size measuring unit 31 . It is introduced directly into the mist so that the average particle diameter of the mist is measured. The fluorine gas production apparatus according to the tenth modification does not include the second average particle diameter measuring unit 34 . The configuration of the fluorine gas production apparatus according to the tenth modification is substantially the same as that of the fluorine gas production apparatus according to the ninth modification illustrated in FIG. 12 except for the above points, and thus descriptions of the same parts are omitted.

Example

The present invention will be described in more detail with reference to Examples and Comparative Examples below.

[Reference Example 1]

The electrolytic solution was electrolyzed to prepare fluorine gas. As the electrolytic solution, a mixed molten salt (560L) of 434 kg of hydrogen fluoride and 630 kg of potassium fluoride was used. As the anode, an amorphous carbon electrode made by SGL Carbon (width 30cm, length 45cm, thickness 7cm) was used, and 16 anodes were installed in the electrolytic cell. In addition, a punching plate made by Monel (trademark) was used as the cathode, and it was installed in the electrolytic cell. Two negative poles oppose one positive electrode, and the total area of the part opposing the negative electrode among one positive electrode is 1736 cm<2>.

Electrolysis temperature was controlled to 85-95 degreeC. First, the electrolysis solution temperature was set to 85°C, and a direct current of 1000 A was applied at a current density of 0.036 A/cm 2 to start electrolysis. The water concentration in the electrolytic solution at this time was 1.0 mass %. In addition, the water concentration is measured by the Karl Fischer analysis method.

After starting the electrolysis under the above conditions, a small bursting sound was observed in the vicinity of the anode in the anode chamber for 10 hours immediately after the start of the electrolysis. This bursting sound is thought to have occurred because the generated fluorine gas and moisture in the electrolyte reacted.

In this state, when the fluid generated at the anode was discharged from the anode chamber of the electrolyzer, it was sampled, and the mist contained in the fluid was analyzed. As a result, per 1 L of the fluid generated from the positive electrode, 5.0 to 9.0 mg (calculated assuming that the specific gravity of the mist was 1.0 g/mL. The same applies below) of powder was contained, and the average particle diameter of this powder was 1.0 to 2.0 μm. As a result of observing this powder with an optical microscope, powder having a shape as if the inside of a sphere was cut out was mainly observed. In addition, the current efficiency of fluorine gas generation at this time was 0 to 15%.

In addition, when electrolysis is continued up to 30 kAh with an electric current, the frequency at which a bursting sound is generated inside the anode chamber has been reduced. The water concentration in the electrolytic solution at this time was 0.7 mass %. In addition, in this state, when the fluid generated at the anode was discharged from the anode chamber of the electrolyzer to the outside, it was sampled, and the mist contained in the fluid was analyzed. As a result, 0.4 to 1.0 mg of mist per liter of fluid generated from the anode was contained, and the average particle diameter of this mist was 0.5 to 0.7 mu m. In addition, the current efficiency of fluorine gas generation at this time was 15 to 55%. Let the stage of electrolysis from the start of electrolysis to here be "step (1)".

In addition, electrolysis of the electrolytic solution was continued following step (1). Then, hydrogen fluoride was consumed and the level of the electrolytic solution was lowered. Therefore, hydrogen fluoride was appropriately supplied from the hydrogen fluoride tank to the electrolytic cell. The water concentration in the hydrogen fluoride supplied is 500 mass ppm or less.

In addition, when the electrolysis was continued and the energization amount reached 60 kAh, the average particle diameter of the mist contained in the fluid generated at the anode was 0.36 µm (that is, 0.4 µm or less). At this point, there was no rupture sound at all inside the anode chamber. In addition, the water concentration in the electrolyte solution at this time was 0.2 mass % (that is, 0.3 mass % or less). In addition, the current efficiency of fluorine gas generation at this time was 65%. Let the stage of electrolysis from the end time of step (1) to this be "step (2)".

Further, the electrolysis of the electrolyte solution was continued following step (2) by increasing the current to 3500 A and increasing the current density to 0.126 A/cm 2 . In this state, when the fluid generated at the anode was discharged from the anode chamber of the electrolyzer, it was sampled, and the mist contained in the fluid was analyzed. As a result, 0.03 to 0.06 mg of powder per 1 L of fluid generated from the anode is contained, and the average particle diameter of this powder is about 0.2 μm (0.15 to 0.25 μm), and the particle diameter has a distribution of about 0.1 to 0.5 μm. there was. 14, the measurement result of the particle diameter distribution of this powder is shown. In addition, the current efficiency of fluorine gas generation at this time was 94%. The water concentration in the electrolytic solution at this time was less than 0.2 mass %. Let the stage of electrolysis from the end time of step (2) to this be a "stable stage".

Table 1 summarizes the contents of the electrolysis of Reference Example 1 performed as described above. Table 1 shows current, electrolysis elapsed time, energization amount, moisture concentration in the electrolyte, the mass of mist contained in 1 L of fluid generated at the anode (referred to as “anode gas” in Table 1), average particle diameter of mist, and current efficiency together with the amount of fluid (containing fluorine gas, oxygen gas, and mist) generated at the anode, the amount of mist generated at the anode, the strength of the bursting sound, and the moisture concentration in the fluid generated at the cathode (Table 1, moisture concentration") is also shown.

Moreover, the graph which shows the relationship between the average particle diameter of mist, and the quantity of the mist which generate|occur|produced in the positive electrode is shown in FIG. It can be seen from the graph of FIG. 15 that there is a correlation between the average particle diameter of the mist and the amount of mist generated at the anode. The greater the amount of mist generated, the more likely clogging of piping or valves occurs, and when mist with an average particle diameter larger than 0.4 μm is generated, the amount of mist generated increases and is deposited by the action of gravity, so in the graph of FIG. It can be said that the relationship shown has shown the correlation of the average particle diameter of mist, and the clogging of piping or a valve occurring easily.

Moreover, the graph which shows the relationship between the average particle diameter of mist, and the water concentration in electrolyte solution is shown in FIG. Since the larger the average particle diameter of the mist is, the more likely the clogging of the pipe or the valve occurs, it can be said that the relationship shown in the graph of Fig. 16 represents the correlation between the moisture concentration in the electrolyte and the clogging of the pipe or the valve easily.

[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 step (1), the fluid generated at the anode was circulated through the second bypass pipe, the bypass valve, and the first bypass pipe. After the electrolysis of step (1) was completed, the electrolysis was temporarily stopped and the inside of the fluorine gas production apparatus was inspected. As a result, although mist was accumulated in the 1st bypass piping, since the diameter of the piping was made thick, the blockage of the piping did not occur.

Since the electrolysis in step (2) was carried out in which the average particle diameter of the mist was 0.4 µm or less (the water concentration in the electrolyte solution was 0.2 mass % or less 0.3 mass % of the reference value), the fluid generated at the anode was transferred to the first pipe and the first pipe valve , the 4th pipe and the 1st mist removal part were made to flow through. The first pipe, the first pipe valve, and the fourth pipe did not accumulate or clogged the mist, and since the fluid generated at the anode was supplied to the first mist removing section, the mist was removed in the first mist removing section. The 1st mist removal part is a scrubber type removal part which sprays liquid hydrogen fluoride, and removes microparticles|fine-particles, such as mist, The removal rate of mist was 98 % or more.

[Comparative Example 1]

Electrolysis of step (1) WHEREIN: Electrolysis was performed similarly to Example 1 except that the fluid generated at the anode was made to flow through the 1st piping, 1st piping valve, 4th piping, and 1st mist removal part.

During the electrolysis in step (1), the measured value of the pressure gauge on the anode side of the pressure gauges attached to the anode side and the cathode side of the electrolyzer gradually increased, and the pressure difference from the pressure on the cathode side became 90 mmH ₂ O, so the electrolysis was stopped. The reason for the stop is as follows. Since the vertical length (immersion depth) of the portion immersed in the electrolyte among the partition walls in the electrolytic cell was 5 cm, when the pressure on the anode side is about 100 mmH ₂ O higher than the pressure on the cathode side, the liquid level of the electrolyte on the anode side is lower than the lower end of the partition wall . As a result, it is very dangerous because the fluorine gas passes over the barrier rib and mixes with the hydrogen gas on the cathode side to cause a rapid reaction between the fluorine gas and the hydrogen gas.

After purging the inside of the system with nitrogen gas or the like, the inside of the first pipe, the first pipe valve, and the fourth pipe were inspected. As a result, the first pipe was a pipe extending in the vertical direction, so there was no blockage. A small amount of powder had adhered to the first piping valve, and the pipe downstream of the first piping valve, ie, an inlet portion to the fourth piping, was blocked with the powder. Powder was also deposited in the fourth pipe, but not in an amount sufficient to block the pipe.

1 Sample room 2 Light source
3 Scattered light detection unit 4A, 4B transparent window
10 Electrolyte 11 Electrolyzer
13 Anode 15 Cathode
22 Anode chamber 24 Cathode chamber
31 1st average particle diameter measurement part 32 1st mist removal part
33 2nd mist removal part 34 2nd average particle diameter measurement part
36 Moisture Concentration Measuring Unit 41 First Pipe
42 2nd pipe 43 3rd pipe
44 4th pipe 45 5th pipe
46 6th pipe 47 7th pipe
48 8th pipe 49 9th pipe
51 1st bypass piping 52 2nd bypass piping
61 first pipe valve 62 bypass valve
F Fluid L Light for measuring light scattering
M Mist S Scattered light

Claims (5)

A method for producing fluorine gas by electrolyzing an electrolyte containing hydrogen fluoride and metal fluoride to produce fluorine gas,
an electrolysis step of performing the electrolysis in an electrolyzer;
a water concentration measurement step of measuring the water concentration in the electrolyte solution during the electrolysis;
and a sending process of sending the fluid generated inside the electrolytic cell from the inside of the electrolytic cell to the outside through a flow path during the electrolysis of the electrolytic solution,
In the air sending process, the flow path through which the fluid flows is switched according to the moisture concentration in the electrolyte measured in the moisture concentration measuring process, and the moisture concentration in the electrolyte measured in the moisture concentration measuring process is less than or equal to a preset reference value. sends the fluid to a first flow path for sending the fluid from the inside of the electrolytic cell to the first outside, and when it is greater than the preset reference value, the fluid into a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside is to send
The method for producing a fluorine gas, wherein the preset reference value is a numerical value within the range of 0.1% by mass or more and 0.8% by mass or less. The method of claim 1,
The method for producing a fluorine gas, wherein the metal fluoride is a fluoride of at least one metal selected from potassium, cesium, rubidium, and lithium. 3. The method of claim 1 or 2,
A method for producing fluorine gas, wherein the anode used in the electrolysis is a carbonaceous electrode formed of at least one carbon material selected from diamond, diamond-like carbon, amorphous carbon, graphite, and glassy carbon. 4. The method according to any one of claims 1 to 3,
The electrolytic cell is a method for producing a fluorine gas having a structure in which bubbles generated in the anode or the cathode used in the electrolysis rise in a vertical direction in the electrolyte to reach the liquid level of the electrolyte. A fluorine gas production apparatus for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride, comprising:
an electrolyzer in which the electrolysis is performed by receiving the electrolyte;
a water concentration measuring unit for measuring the water concentration in the electrolyte in the electrolyzer during the electrolysis;
and a flow path for sending a fluid generated inside the electrolyzer from the inside of the electrolytic cell to the outside during the electrolysis of the electrolyte;
The flow path has a first flow path for sending the fluid from the inside of the electrolytic cell to the first outside, and a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside, and is measured by the moisture concentration measuring unit and a flow path switching unit for switching a flow path through which the fluid flows to the first flow path or the second flow path according to the water concentration in the electrolyte solution,
The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the water concentration in the electrolyte measured by the water concentration measurement unit is less than or equal to a preset reference value, and when greater than the preset reference value, the to send the fluid from the inside of the electrolyzer to the second flow path,
The preset reference value is a fluorine gas manufacturing apparatus that is a numerical value within a range of 0.1% by mass or more and 0.8% by mass or less.

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