KR20220065864A - 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 electrolytic solution in the electrolysis cell, a current efficiency measuring step of measuring the current efficiency of fluorine gas generation in the electrolysis, and a fluid generated inside the electrolyzer during the electrolysis of the electrolytic solution from the inside of the electrolyzer Fluorine gas is produced by a method including a gas sending step to the outside through a flow path. In the air sending process, the flow path through which the fluid flows is switched according to the current efficiency measured in the current efficiency measuring process, and when the current efficiency measured in the current efficiency measuring process is greater than or equal to a preset reference value, the fluid is transferred from the inside of the electrolytic cell to the first outside The fluid is sent to the first flow path to be sent, and when it is smaller than a preset reference value, the fluid is sent to the second flow path that sends the fluid from the inside of the electrolytic cell to the second outside. The preset reference value is a numerical value within a range of 50% or more.

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 sent out from the electrolytic cell. The mist accompanying the fluorine gas becomes powdery and there is a possibility of clogging a pipe or a valve used for supplying the fluorine gas. Therefore, there are cases in which it is necessary to stop or stop the operation for producing the fluorine gas, which is 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 of heating 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 which is a space for roughing mist, and a filler accommodating unit for accommodating a filler for adsorbing mist.

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

However, the technique which can suppress more effectively the blockage of piping or a valve by mist was calculated|required.

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 solution containing hydrogen fluoride and metal fluoride to produce fluorine gas, the method comprising:

an electrolysis step of performing the electrolysis in an electrolyzer;

a current efficiency measuring step of measuring the current efficiency of fluorine gas generation in the electrolysis;

and a sending process of sending the 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 sending process, the flow path through which the fluid flows is switched according to the current efficiency measured in the current efficiency measuring process, and when the current efficiency measured in the current efficiency measuring process is equal to or greater than a preset reference value, the inside of the electrolytic cell to send the fluid to a first flow path for sending the fluid to the first outside, and to send the fluid to a second flow path for sending the fluid from the inside of the electrolytic cell to the second outside when it is smaller than the preset reference value, ,

The preset reference value is a method for producing a fluorine gas that is a numerical value within a range of 50% or more.

[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 fluorine gas as described in.

[4] Any one of [1] to [3] in which the electrolytic cell has a structure in which bubbles generated in the anode or cathode used in the electrolysis rise in the vertical direction in the electrolytic solution and reach the liquid level of the electrolytic solution. 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, comprising:

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

a current efficiency measuring unit for measuring the current efficiency of fluorine gas generation in 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 current efficiency measuring unit and 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 current efficiency,

The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the current efficiency measured by the current efficiency measuring unit is equal to or greater than a preset reference value, and when the current efficiency measured by the current efficiency measuring unit is less than the preset reference value, the inside of the electrolyzer to send the fluid to the second flow path from

The preset reference value is a fluorine gas manufacturing apparatus that is a numerical value within a range of 50% or more.

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 which concerns on one Embodiment of this invention.
2 is a schematic diagram illustrating an example of a fluorine gas production apparatus according to an embodiment of the present 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 a current efficiency in Reference Example 1.

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 improvements to this embodiment, and the form to which such a change or improvement was added can also be included in this invention.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined about the mist which causes clogging of piping or a valve in the electrolytic synthesis of 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, fine particles of an electrolyte solution, fine particles of a solid in which the fine particles of an electrolyte solution are phase-changed, and solids formed by the reaction of fluorine gas with a member constituting the electrolytic cell (metal forming the electrolytic cell, packing for the electrolytic cell, carbon electrode, etc.) it is particulate.

The present inventors measured the average particle diameter of mist contained in the fluid generated inside the electrolyzer at the time of electrolysis of electrolyte solution, and confirmed that the average particle diameter of mist changed with time. Further, as a result of intensive examination, it was found that there is a correlation between the average particle diameter of the mist and the current efficiency of fluorine gas generation in electrolysis, and the average particle diameter of the mist and the pipe or valve that sends the fluid are prone to clogging found a correlation between And, according to the current efficiency of the fluorine gas generation in the electrolysis, by studying the flow path for sending the fluid generated inside the electrolytic cell, it is possible to suppress the clogging of the pipe or valve, and to stop the operation of producing fluorine gas or It came to complete this invention by discovering what can reduce the frequency of a stoppage. EMBODIMENT OF THE INVENTION One Embodiment of this invention is 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, an electrolysis step of performing electrolysis in an electrolyzer; a current efficiency measuring step of measuring the current efficiency of generating fluorine gas of

In the air sending step, the flow path through which the fluid flows is switched according to the current efficiency measured in the current efficiency measuring step. That is, when the current efficiency measured in the current efficiency measurement process is equal to or greater than a preset reference value, the fluid is sent from the inside of the electrolytic cell to the first flow path for sending the fluid to the first outside, and when it is smaller than the preset reference value, the second flow is transmitted from the inside of the electrolyzer. The fluid is sent to the second flow path for sending the fluid to the outside. In addition, the preset reference value is a numerical value within a range of 50% or more.

In addition, the fluorine gas production apparatus of the present embodiment is a fluorine gas production apparatus for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride, and an electrolyzer containing an electrolyte solution and performing electrolysis; and a current efficiency measuring unit for measuring the current efficiency of generating fluorine gas of

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 that switches the flow path through which the fluid flows to the first flow path or the second flow path according to the current efficiency measured by the current efficiency measuring unit.

The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the current efficiency measured by the current efficiency measuring unit is equal to or greater than a preset reference value, and sends the fluid from the inside of the electrolytic cell to the second flow path when it is smaller than the preset reference value. it is written In addition, the preset reference value is a numerical value within a range of 50% or more.

In the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of the present embodiment, the flow path through which the fluid flows is switched to the first flow path or the second flow path depending on the current efficiency of the fluorine gas generation in the electrolysis. As a result, The flow path is switched to the 1st flow path or the 2nd flow path according to the average particle diameter of mist, and it is hard to produce clogging of the flow path by mist. Therefore, when the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment electrolyze the electrolyte solution containing hydrogen fluoride and a metal fluoride and manufacture fluorine gas, the blockage of piping and a valve by mist can be suppressed. 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 manufacturing method and fluorine gas manufacturing apparatus of this embodiment, the measurement of current efficiency may be performed constantly during electrolysis, may be performed regularly at regular intervals, or may be performed irregularly at any 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 different location, and the same location may be sufficient as them.

Here, an example of the manufacturing method and fluorine gas manufacturing apparatus of the fluorine gas of this embodiment is shown. The first flow passage is a flow passage that sends the fluid from the inside of the electrolytic cell to the fluorine gas separator for sorting and taking out the fluorine gas from the fluid via the mist removing part for removing 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 current efficiency is equal to or greater than the preset reference value, the fluid is sent to the mist removal unit provided in the first flow path, and when it is smaller 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 different 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 diameter larger than that of the first flow path, it is possible to suppress clogging of the second flow path by mist. In addition, by configuring at least a part of the second flow path with a pipe that is inclined with respect to the horizontal direction and extends in a downward direction from the upstream side to the downstream side, it is possible to suppress clogging of the second flow path by the mist.

Moreover, by providing the inside of the 2nd flow path with the rotation screw which sends the mist accumulated in the inside of the 2nd flow path to an upstream or downstream, clogging 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 through 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 blockage suppression mechanism is provided in the 2nd flow path, it is hard to produce clogging by mist. Therefore, when the fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment electrolyze the electrolyte solution containing hydrogen fluoride and a metal fluoride and manufacture fluorine gas, the blockage of piping and a valve by mist can be suppressed. In addition, even if the mist removal unit or blockage suppression mechanism is not provided, the blockage of piping or valves caused by mist is suppressed by simply switching the flow path through which the fluid flows to a separate flow path (first flow path or second flow path). Although the effect is exhibited, the said effect is excellent in the one provided with a mist removal part and a blockage suppression mechanism.

The fluorine gas manufacturing method and fluorine gas manufacturing apparatus of this embodiment are demonstrated in more detail below.

[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 do not mix.

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. Further, as the anode, a metal electrode made of a metal such as nickel or Monel (trademark) in addition to the above-mentioned carbon material can also be used. As the cathode, for example, a metal electrode made of a metal such as iron, copper, nickel or 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. When cesium or rubidium is contained in the electrolytic solution, the specific gravity of the electrolytic solution increases, so that 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 is corrosive, it is preferable to form the part in contact with the electrolyte such as the inner surface of the electrolytic cell with a metal such as iron, nickel, or Monel (trademark).

During the electrolysis of the electrolyte, a direct current is applied to the anode and the cathode, so that 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, hydrogen fluoride is accompanied by gases generated from the anode and cathode, 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 electrolyzer consists of a gas generated by electrolysis, hydrogen fluoride, and a mist of an electrolyte solution. Therefore, what is sent out from the inside of an electrolytic cell consists of the gas generated by electrolysis, hydrogen fluoride, and the mist of electrolyte solution, and this is called "fluid" in the present invention.

In addition, since hydrogen fluoride in the electrolytic solution is consumed by the progress of electrolysis, a pipe for continuously or intermittently supplying hydrogen fluoride to the electrolytic cell for replenishment 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 reasons that mist is generated at the time of electrolysis of the electrolyte are 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 from 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 electrolytic solution is released in the gas phase.

Since the temperature of the gas phase is lower than the melting point of the electrolyte, the released electrolyte changes phase to a very fine powder-like state. 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 other generated gas, and forms the fluid generated in the electrolyzer. It is difficult to effectively remove such mist by ordinary countermeasures, such as installation of a filter, for reasons such as having adhesiveness.

In addition, although the amount is small, the fine powder of the organic compound may be generated as a mist by the reaction between the carbonaceous electrode as the anode and the fluorine gas generated by electrolysis. To be more specific, contact resistance is often generated in the portion where the electric current is fed to the carbonaceous electrode, and the temperature may be higher than the temperature of the electrolyte due to Joule heat. Therefore, when carbon which forms a carbonaceous electrode and fluorine gas react, soot-like organic compound CFx may generate|occur|produce as mist.

In addition, it is preferable that the electrolytic cell has a structure in which the bubbles generated in the anode or the cathode used in the electrolysis rise in the vertical direction in the electrolytic solution and reach the liquid level of the electrolytic solution. If the bubble hardly rises in the vertical direction in the electrolyte solution and has a structure in which it rises in a direction inclined with respect to the vertical direction, a plurality of bubbles will aggregate and large bubbles are likely to be 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 has a structure that can reach the liquid level of the electrolyte when it rises in the vertical direction in the electrolyte, small bubbles will reach the liquid level of the electrolyte and burst, so the amount of mist generated tends to decrease.

[Average particle diameter measurement unit]

The fluorine gas production apparatus of the present embodiment may be provided with an average particle diameter measurement unit for measuring the average particle diameter of the mist contained in the fluid, but this average particle diameter measurement unit is composed of a light scattering detector that measures the average particle diameter by a light scattering method it may be good 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 (for example, the fluorine gas production apparatus of FIGS. 2 and 4 to 13 described later) of the present embodiment. 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, it is a light scattering detector that measures the average particle diameter of the mist contained in the fluid generated inside the electrolytic cell. .

The light scattering detector may be connected to the fluorine gas production device, 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 may be taken out from the inside of the electrolytic cell without connecting the light scattering detector and the fluorine gas production device Then, it may introduce|transduce into a light scattering detector, and you may measure the average particle diameter of mist.

The light scattering detector of FIG. 1 includes a sample chamber 1 for accommodating a fluid F, a light source 2 for irradiating light L for light scattering measurement to the fluid F in the sample chamber 1, and for light scattering measurement A scattered light detection unit 3 that detects the scattered light S generated by the light L being scattered by the mist M in the fluid F, is installed in the sample chamber 1 and is in contact with the fluid F to measure light scattering It is provided with the transparent window 4A through which the molten light L transmits, and the transparent window 4B which is provided in the sample chamber 1 and comes in contact with the fluid F and transmits the scattered light S. 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). has been

Light L for light scattering measurement (for example, laser light) generated from the light source 2 passes through the converging lens 6 and the transparent window 4A of the sample chamber 1 and enters the sample chamber 1 , The fluid F accommodated in the chamber 1 is irradiated. At this time, if a substance that reflects light such as mist M exists in the fluid F, the light L for light scattering measurement is reflected and scattered. A part of the scattered light S generated when the light L for light scattering measurement is scattered by the mist M passes through the transparent window 4B of the sample chamber 1 and is taken out from the sample chamber 1 to the outside, and condensed It enters the scattered light detection unit 3 through the lens 7 and the diaphragm 8 . At this time, the average particle diameter of the mist M can be known from the information obtained from scattered light. 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.

In addition, 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 part 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 the 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 portions 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, but for example, Monel (trademark), Hasteroy (trademark), copper-nickel alloy It is preferable to use a metal material such as stainless steel.

[Average particle diameter of mist and current efficiency of fluorine gas generation in electrolysis]

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 the 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 size 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 size is generated from immediately after the start of electrolysis to the time of stable electrolysis. When a fluid containing 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 size of the mist generated during stable electrolysis is relatively small. This small mist hardly causes sedimentation or deposition in the fluid, so it can flow through the pipe or valve stably. For this reason, during stable electrolysis, a fluid composed of mist and gas generated from the electrode is less likely to cause clogging of piping or valves. Moreover, 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 electrolyte is required.

Moreover, the present inventors discovered that there existed a close relationship between the average particle diameter of mist, and electric current efficiency. Usually, the current efficiency is small at the start of electrolysis, and exhibits a value smaller than 60%. The average particle diameter of the mist at this time is larger than 0.4 micrometer. After that, as the electrolysis is continued, the current efficiency increases, and when it becomes 60% or more, the average particle diameter of the mist becomes 0.4 µm or less.

In this way, since there is a correlation between the average particle diameter of mist and current efficiency, current efficiency is measured instead of the average particle diameter of mist during electrolysis, and the measurement result can be used for switching the flow path. That is, if the current efficiency 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.

Current efficiency refers to the percentage of electricity used in the target reaction in the electrochemical reaction of electrolysis. It is calculated as the ratio (percentage) of the actual production amount of the target product.

In the present embodiment, since the target object in the electrochemical reaction of the electrolysis is fluorine gas, the theoretical production amount of fluorine gas calculated from the amount of current (current (A) × time (s) = coulomb), actually produced fluorine gas By dividing the amount of , the current efficiency of fluorine gas generation in the electrolysis can be calculated.

Although the measuring method in particular of the quantity of the fluorine gas produced|generated is not specifically limited, For example, it can measure by the following titration method. That is, the gas generated at the anode is passed through the aqueous potassium iodide solution for a certain period of time, and the fluorine gas in the anode gas is absorbed into the potassium iodide aqueous solution. Then, since iodine is liberated from the potassium iodide aqueous solution, the amount (mol/min) of the actually produced|generated fluorine gas can be measured by titrating this liberated iodine.

Then, the current efficiency can be calculated by substituting the amount of the actually generated fluorine gas and the current value to the following equation.

Current efficiency = {Amount of fluorine gas actually produced (mol/min)}/{Current value (A) × 60 (sec/min)/96500 (A sec)/2} × 100

When measuring the amount of fluorine gas actually produced, the entire amount of fluorine gas generated at the anode may be absorbed in the potassium iodide aqueous solution, or a portion may be aliquoted and absorbed. In the case of fractional fractionation, nitrogen gas is supplied to the electrolyzer at a known flow rate, and the mixing ratio of the mixed gas of fluorine gas and nitrogen gas discharged from the electrolyzer is measured. This mixing ratio is determined by passing the mixed gas through an aqueous solution of potassium iodide, quantifying the amount of fluorine gas by absorbing the fluorine gas in the mixed gas into an aqueous solution of potassium iodide, and measuring the amount of nitrogen gas not absorbed into the aqueous solution of potassium iodide with a gas meter or the like. It can be obtained by quantification.

The present inventors have invented the fluorine gas manufacturing method and the fluorine gas manufacturing apparatus which have a structure which can switch the flow path through which a fluid flows according to electric current efficiency based on this knowledge. The fluorine gas manufacturing 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 the two flow paths using a flow path switching unit (for example, a switching valve). good.

Alternatively, the fluorine gas production apparatus of the present embodiment has two flow paths and a movement replacement mechanism for moving and replacing the electrolytic cell, selecting a flow path used for conveying the fluid from among the two flow paths, and placing the electrolytic cell in the vicinity of the flow path By moving and connecting, the flow path may be switched.

As described above, since the first flow passage and the second flow passage are provided, the fluorine gas production apparatus can be continuously operated by opening the other flow passage even while one of the flow passages is blocked and cleaned.

According to the studies conducted by the present inventors, mist having a relatively large average particle size is generated from immediately after the start of electrolysis to the time of stable electrolysis. When time elapses and stable electrolysis is reached, mist with a relatively small average particle diameter is generated.

The flow path is switched according to the measured current efficiency, 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 varies from device to 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 current efficiency, the lower limit of an appropriate reference value for the current efficiency is 50% or more, preferably 60% or more. Further, the upper limit of the reference value is preferably 99% or less, more preferably 90% or less. The most appropriate reference value for current efficiency is 60%. When the current efficiency is less than the reference value, the fluid can be sent to the second flow path, and when the current efficiency is greater than the reference value, the fluid can be sent to the first flow path.

In addition, the fluid (the main component is hydrogen gas) generated at 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, a large difference due to the current efficiency was not observed in the particle size distribution of the generated powder. 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, compared to the mist contained in the fluid generated from the anode, it is difficult to cause clogging of pipes or valves. 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 electrolyzers 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 a partition wall 17 extending vertically downward from the ceiling surface of the inside of the electrolytic cell 11 and the lower end thereof is immersed in the electrolytic solution 10, the anode chamber 22 and the cathode chamber (24) is demarcated. 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 current efficiency measuring unit 38 that measures the current efficiency of fluorine gas generation in the electrolysis, and the electrolytic solution 10 generated inside the electrolytic cell 11 during the electrolysis of the electrolyte 10 . A first average particle size measuring unit 31 for measuring the average particle size of the mist contained in the fluid, the first mist removing unit 32 for removing the mist from the fluid, and fluorine for separating and taking out fluorine gas from the fluid A gas separation unit (not shown in the drawing) and a flow path for sending the fluid from the inside of the electrolytic cell 11 to the fluorine gas separation unit are provided.

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 removal unit 32 , and the electrolytic cell 11 without passing through the first mist removing unit 32 . ) has a second flow path for sending the fluid from the inside to the fluorine gas sorting unit. 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 current efficiency measured by the current efficiency measuring unit 38 . 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 current efficiency measured by the current efficiency measuring unit 38 is equal to or greater than the preset reference value, and when the current efficiency measured by the current efficiency measuring unit 38 is smaller than the preset reference value, the electrolytic cell 11 It is adapted to send the fluid from the inside of the 2nd 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 current efficiency is greater than or equal to the reference value, the fluid is sent to the first flow path in which the electrolytic cell 11 and the fluorine gas sorting unit are connected and the first mist removing unit 32 is installed. 11) and the fluorine gas sorting unit, and the fluid is sent to the second flow path provided with the blockage suppression mechanism.

Although the structure of the current efficiency measuring part 38 is not specifically limited, The current efficiency measuring part 38 has a structure which can calculate|require the current efficiency by the appropriate method mentioned above, for example. That is, the current efficiency measuring unit 38 includes an inert gas supply unit (not shown) that supplies an inert gas such as nitrogen gas to the anode chamber 22 of the electrolytic cell 11 at a predetermined flow rate, and The mixed gas containing the fluorine gas and the inert gas discharged from the anode chamber 22 is fractionated, passed through a potassium iodide aqueous solution for a certain period of time, the fluorine gas in the mixed gas is absorbed into the potassium iodide aqueous solution, and the iodine liberated from the potassium iodide aqueous solution is titrated. Based on the titration part (not shown in the drawing), the flow rate of the inert gas in the inert gas supply part, the titration result by the titration part (the amount of fluorine gas actually produced), and the current value in the electrolysis You may have a calculation part (not shown in figure) which calculates the current efficiency of the fluorine gas generation|occurrence|production in electrolysis.

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. The type of mist removal device, that is, the method of removing the mist is not particularly limited, but since the average particle diameter of the mist is small, for example, an electrostatic precipitator, a venturi scrubber, or a filter can be used as the mist removal device. .

It is preferable to use the mist removal apparatus shown in FIG. 3 among 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. A first pipe 41 for sending a fluid (hereinafter, sometimes referred to as “anode gas”) generated in the anode chamber 22 of the electrolytic cell 11 to the outside connects the electrolytic cell 11 and the fourth pipe 44 . It communicates, and the anode gas sent out from the two electrolytic cells 11 and 11 is sent to the 4th pipe 44 through the 1st pipe 41, and is mixed. In addition, the main component of the anode gas is fluorine gas, and the subcomponents are mist, hydrogen fluoride, carbon tetrafluoride, 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 in anode gas and hydrogen fluoride is removed from the anode gas by the first mist removal unit 32 . The anode gas from which mist and hydrogen fluoride have been removed is sent out from the first mist removal unit 32 to a fluorine gas sorting unit not shown in the figure through the sixth pipe 46 connected to the first mist removal unit 32, there is. Then, the fluorine gas is separated from the anode gas by the fluorine gas sorting unit and taken out.

Moreover, the 8th pipe 48 is connected to the 1st mist removal part 32, and the liquid hydrogen fluoride 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 is used for mist-containing circulating fluid (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 that of 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 sent out from the two electrolytic cells 11 and 11 is sent to the fifth pipe 45 through the second pipe 42 to be mixed. Moreover, the main component of cathode gas is hydrogen gas, and the subcomponent is mist, hydrogen fluoride, and water.

Since the cathode gas contains fine mist and 5 to 10 vol% 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 and the 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 rate of the fluid flowing through the duct 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 velocity 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. As shown in FIG.

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. In addition, the anode gas is sent 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 desirable to set the pipe diameter so that the flow velocity of the fluid is 30 cm/sec or less under standard conditions.

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 the first bypass pipe 51 due to the deposition of powder. ) is of a size that is difficult to cause occlusion. 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 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. As shown in FIG. In addition, a bypass valve 62 is provided in each of the second bypass pipes 52 . 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 titration part for titrating the liberated iodine by fractionating the anode gas among the current efficiency measuring part 38 of the fluorine gas manufacturing apparatus and passing it through an aqueous potassium iodide solution is an intermediate part of the fourth pipe 44 and the first pipe It is provided on the downstream side of the connection part with (41). In addition, it is preferable that the said inert gas supply part is provided in the vicinity of the electrolytic cell 11, and the installation location of the said calculation part is not specifically limited.

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 measurement 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 current 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 the 2nd average particle The average particle size of the mist contained in the anode gas flowing through the first bypass pipe 51 is measured by the diameter measuring unit 34 . 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. As shown in FIG.

The current efficiency measuring unit 38 measures the current efficiency of fluorine gas generation in the electrolysis, and when the measurement result is smaller than a preset reference value, the bypass valve 62 is opened to remove the anode gas. The anode gas is sent from the electrolytic cell 11 to the first bypass pipe 51, and the anode gas is sent to the fourth pipe 44 and the first mist removal unit 32 with the first pipe valve 61 closed. do not let it stand That is, the anode gas is sent to the second flow path.

On the other hand, when the measurement result is equal to or greater than the preset reference value, the first pipe valve 61 is opened to send the anode gas to the fourth pipe 44 and the first mist removal unit 32, and the bypass valve ( 62) is closed to prevent the anode gas from being sent from the electrolytic cell 11 to the first bypass pipe 51. That is, the anode gas is sent to the first flow path.

As can be seen from the above description, the flow path switching unit is constituted by the first piping valve 61 and the bypass valve 62 .

By operating the fluorine gas production apparatus while switching the flow path according to the current efficiency of fluorine gas generation in the electrolysis as described above, smooth continuous operation can be performed while suppressing clogging of piping and valves by mist. . 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 sufficient to judge the period in which the filter replacement is frequently performed and the period in which the filter replacement is not required frequently based on the measurement of the current efficiency. 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, a modified example of the fluorine gas production apparatus shown in FIG. 2 will be described.

[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 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.

[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. As shown in FIG. 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, for example, by providing the space for mist accumulating in the downstream end of the 1st bypass pipe 51, the effect of blockage suppression can further be increased. As the space for this mist stagnant, for example, a space formed by forming the downstream end portion of the first bypass pipe 51 with a larger pipe diameter than the central portion in the installation direction (for example, 4 times or more the diameter of the central portion in the installation direction). However, there is a space formed by forming the downstream end portion of the first bypass pipe 51 in the same shape as a container, and the space for mist stagnant can suppress clogging of the first bypass pipe 51 can This aims at the effect of blockage prevention by the large flow path cross-sectional area and the effect of blockage prevention using the gravitational 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 which is not shown in figure. 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 of the third modified example, 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 measured by the first average particle size measuring unit 31 . It is introduced directly to the mist, so that the measurement of the average particle diameter of the mist is carried out. The fluorine gas production apparatus according to the third modification does not include the second average particle size 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 modification 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 modification, 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 modification, the first bypass piping 51 extends in the horizontal direction It is inclined with respect to , and extends in the direction of 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 the first bypass pipe 51 is likely to be blocked, if the inclined first bypass pipe 51 is hammered, the deposits inside the first bypass pipe 51 are likely to move, so the blockage can be prevented. can be avoided

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 thus descriptions of the same parts are omitted.

[Fifth modification]

A fifth modification 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 the direction of 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 inclination angle of the first bypass pipe 51 is the same as in the case of the fourth modified example. The configuration of the fluorine gas production apparatus of the fifth modification is substantially the same as that of the fluorine gas production apparatus of the third modification except for the above points, and therefore the description of the same parts is 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, 15), and one anode chamber (22) 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 modification is substantially the same as that of the fluorine gas production apparatus of the second modification except for the above points, and thus descriptions of the same parts are 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. extended in the direction of A preferable inclination angle of the first bypass pipe 51 is the same as in the case of the fourth modified example. 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 thus descriptions of the same parts are 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 accumulates 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 accumulates 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. The pressure in the anode chamber 22 and the pressure in the cathode chamber 24 are preferably 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 through the partition wall 17 . ) and flows into the cathode chamber 24, 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 measurement unit 31 is provided in the electrolytic cell 11 , and the anode gas inside the electrolytic cell 11 is measured by the first average particle size measurement unit 31 . It is introduced directly to the mist, so that the measurement of the average particle diameter of the mist is carried out. The fluorine gas production apparatus according to the tenth modification does not include the second average particle size measuring unit 34 . The configuration of the fluorine gas production apparatus of the tenth modification is substantially the same as that of the fluorine gas production apparatus of the ninth modification shown in FIG. 12 except for the above points, and thus descriptions of the same parts are omitted.

Example

An Example and a comparative example are shown below, and this invention is demonstrated more concretely.

[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. An amorphous carbon electrode (30 cm wide, 45 cm long, and 7 cm thick) manufactured by SGL Carbon Corporation was used as the anode, and 16 anodes were installed in the electrolytic cell. Further, 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 temperature of the electrolyte solution was set to 85 DEG C, a direct current of 1000 A was applied at a current density of 0.036 A/cm&lt;2&gt;, and electrolysis was started. 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.

When the electrolysis under the above conditions was started, a small bursting sound was observed in the vicinity of the anode in the anode chamber from immediately after the start of the electrolysis until the total energization amount reached 10 kAh. It is thought that this bursting sound was generated because the generated fluorine gas and the moisture in the electrolyte reacted.

In this state, when the fluid generated at the anode was sent out from the anode chamber of the electrolyzer, it was collected and the mist contained in the fluid was analyzed. As a result, a powder of 5.0 to 9.0 mg per 1 L of the fluid generated from the anode (the specific gravity of the mist was calculated assuming that it was 1.0 g/mL. The same applies below) was contained, and the average particle diameter of this powder was 1.0 to It was 2.0 micrometers. As a result of observing this powder with an optical microscope, a powder having a shape similar to that in which 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 the electrolysis is continued until 30 kAh is reached by the accumulated energization amount, 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 %. Further, in this state, when the fluid generated at the anode was sent out from the anode chamber of the electrolyzer, it was sampled and the mist contained in the fluid was analyzed. As a result, 0.4 to 1.0 mg of mist was contained per 1 L of the fluid generated from the anode, and the average particle diameter of this mist was 0.5 to 0.7 µm. 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)".

Further, the electrolysis of the electrolytic solution was continued following the 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 hydrogen fluoride to be supplied is 500 mass ppm or less.

Further, when the electrolysis was continued and the energization amount of the integration exceeded 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 point of step (1) to here be "step (2)".

Further, the current was increased to 3500 A and the current density was increased to 0.126 A/cm 2 , and the electrolysis of the electrolytic solution was continued in step (2). In this state, when the fluid generated at the anode was sent out from the anode chamber of the electrolyzer, it was collected 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 shows the measurement result of the particle size distribution of this powder. In addition, the current efficiency of fluorine gas generation at this time was 94%. Let the stage of electrolysis from the end point of step (2) to this "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 1L of fluid generated at the anode (indicated as “anode gas” in Table 1), average particle size of mist, current efficiency together with the amount of fluid (including fluorine gas, oxygen gas, and mist) generated at the anode, the amount of mist generated at the anode, the strength of the rupture, and the moisture concentration in the fluid generated at the cathode (in Table 1, “cathode Moisture concentration in gas”) 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. From the graph of FIG. 15, it turns out that there exists a correlation between the average particle diameter of mist, and the quantity of the mist which generate|occur|produces from an anode. The larger the amount of mist generated, the more likely the 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 the graph of FIG. It can be said that the relationship shown in has shown the correlation between the average particle diameter of mist, and the possibility of clogging of piping or a valve.

Moreover, the graph which shows the relationship between the average particle diameter of mist, and electric current efficiency 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 current efficiency and the clogging of the pipe or the valve.

[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 in 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 became large, the blockage of the piping did not occur.

Since the electrolysis in step (2) was performed in which the average particle diameter of the mist was 0.4 µm or less (current efficiency is 65% or more than 60% of the reference value), the fluid generated at the anode is removed from the first pipe, the first pipe valve, the fourth pipe, and the second pipe. 1 It was made to flow through a mist removal unit. 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 among 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 reasons for the suspension are as follows. Since the vertical length (immersion depth) of the part 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, the fluorine gas crosses the barrier and mixes with the hydrogen gas on the cathode side, causing a rapid reaction between the fluorine gas and the hydrogen gas, which is very dangerous.

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 checked. 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 on the downstream side of the first piping valve, ie, the inlet portion to the fourth pipe, was blocked with the powder. There was also powder accumulation in the 4th pipe, but it was not enough 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 Room
31... 1st average particle diameter measurement part
32... 1st mist removal part
33... 2nd mist removal part
34... 2nd average particle diameter measurement part
38 ... Current Efficiency Measuring Unit
41... the first pipe
42... 2nd pipe
43... the third pipe
44... 4th pipe
45... 5th pipe
46... the 6th pipe
47... the 7th pipe
48... the 8th pipe
49... the 9th pipe
51... 1st bypass piping
52... 2nd bypass piping
61... 1st piping valve
62...bypass valve
F...fluid
L...light for light scattering measurement
M... mist
S...Scattered light

Claims (5)

A method for producing fluorine gas by electrolyzing an electrolyte solution containing hydrogen fluoride and metal fluoride to produce fluorine gas, the method comprising:
an electrolysis step of performing the electrolysis in an electrolyzer;
a current efficiency measuring step of measuring the current efficiency of fluorine gas generation in the electrolysis;
and a sending process of sending the 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 sending process, the flow path through which the fluid flows is switched according to the current efficiency measured in the current efficiency measuring process, and when the current efficiency measured in the current efficiency measuring process is equal to or greater than a preset reference value, the inside of the electrolytic cell to send the fluid to a first flow path for sending the fluid to the first outside from ,
The preset reference value is a method for producing a fluorine gas that is a numerical value within a range of 50% or more. 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 cathode used in the electrolysis rise in a vertical direction in the electrolyte solution and reach the liquid level of the electrolyte solution. 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 current efficiency measuring unit for measuring the current efficiency of fluorine gas generation in 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 current efficiency measuring unit and 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 current efficiency,
The flow path switching unit sends the fluid from the inside of the electrolyzer to the first flow path when the current efficiency measured by the current efficiency measuring unit is equal to or greater than a preset reference value, and when the current efficiency measured by the current efficiency measuring unit is less than the preset reference value, the inside of the electrolyzer to send the fluid to the second flow path from
The preset reference value is a fluorine gas manufacturing apparatus that is a numerical value within a range of 50% or more.

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