JP2010189675A - Gas generator and gas generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generator and a gas generating method by which high purity fluorine gas can be stably obtained through a long period while satisfactorily reducing maintenance cost. <P>SOLUTION: An electrolytic cell 1 is partitioned into a cathode chamber 3 and an anode chamber 4 with a partition wall 2. An electrolytic bath 5 is formed in the electrolytic cell 1. A cathode 6 is provided in the cathode chamber 3 and an anode 7 is provided in the anode chamber 4. The electrolysis of hydrogen fluoride is carried out in the electrolytic bath 5. The fluorine gas generated in the anode chamber 4 is discharged from a fluorine gas discharge pipe 30. A compressor 32 is interposed in the fluorine gas discharge pipe 30. An inverter circuit 321 is connected to the compressor 32. In the anode chamber 4, a pressure gauge PS2 measuring the pressure of the anode chamber 4 is provided. The controller 90 controls the inverter circuit 321 based on the measured result of the pressure gauge PS2, whereby a revolution speed of a motor built in the compressor 32 is adjusted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas generating device and a gas generating method for generating fluorine gas.

Conventionally, fluorine gas has been used in various applications such as material cleaning and surface modification in semiconductor manufacturing processes and the like. In that case, although fluorine gas itself may be used, various kinds of gases such as NF ₃ (nitrogen trifluoride) gas, NeF (neon fluoride) gas, and ArF (argon fluoride) gas synthesized based on the fluorine gas may be used. Fluorine-based gas may be used.

  In such a field, in order to supply fluorine gas stably, for example, a fluorine gas generator that electrolyzes HF (hydrogen fluoride) to generate fluorine gas is used.

  The fluorine gas generator shown in Patent Document 1 includes an electrolytic cell. The electrolytic cell is partitioned into a cathode chamber and an anode chamber by partition walls. An electrolytic bath made of a KF-HF mixed molten salt is formed in the electrolytic cell. A cathode is provided in the cathode chamber, and an anode is provided in the anode chamber. HF is supplied to the electrolytic bath in the electrolytic cell through the HF supply line, and electrolysis of HF is performed. Thereby, hydrogen gas is generated from the cathode of the electrolytic cell, and fluorine gas is generated from the anode.

  In the upper part of the cathode chamber, an outlet for hydrogen gas is provided. Hydrogen gas generated in the cathode chamber is discharged from the outlet through a hydrogen gas line on the cathode side. An automatic valve and an HF adsorption tower are inserted in the hydrogen gas line.

  A fluorine gas outlet is provided in the upper part of the anode chamber. The fluorine gas generated in the anode chamber is discharged from the outlet through the fluorine gas line. An HF adsorption tower and an automatic valve are inserted in the fluorine gas line. Further, in the fluorine gas line, a compressor unit is provided on the downstream side of the HF adsorption tower and the automatic valve.

  The cathode chamber and the anode chamber are provided with pressure gauges for measuring the pressure in each chamber. The automatic valve inserted in the hydrogen gas line and the fluorine gas line opens and closes in conjunction with the pressure value measured by the pressure gauge.

  For example, when the pressure in the cathode chamber is higher than atmospheric pressure, the automatic valve of the hydrogen gas line is opened, and when the pressure in the cathode chamber is lower than atmospheric pressure, the automatic valve of the hydrogen gas line is closed.

  When the pressure in the anode chamber is higher than atmospheric pressure, the fluorine gas line automatic valve is opened, and the fluorine gas in the anode chamber is sucked into the compressor unit through the fluorine gas line. On the other hand, when the pressure in the anode chamber is lower than atmospheric pressure, the automatic valve of the fluorine gas line is closed.

  As described above, the cathode chamber and the anode chamber are maintained at a predetermined pressure. Thereby, the liquid level of the electrolytic bath is maintained in a stable state, and fluctuations in electrolysis conditions during electrolysis of HF are suppressed.

JP 2004-52105 A

  In the fluorine gas generator, in order to sufficiently suppress fluctuations in electrolysis conditions, it is necessary to more accurately adjust the pressure in the cathode chamber and the anode chamber. In this case, the frequency of switching the open / close state of the automatic valve increases. As a result, the components of the automatic valve are easily worn. When particles are generated due to wear, the purity of the gas flowing in the line decreases. Therefore, automatic valve maintenance (replacement, repair, etc.) must be performed frequently.

  Further, in the above-described fluorine gas generator, since the compressor unit provided in the fluorine gas line always operates at the maximum capacity, a large load is always applied to the components (for example, bellows or reed valve) of the compressor unit. In this case, the constituent members of the compressor unit are easily worn, and the life of the compressor unit is reduced. Further, when particles are generated due to wear, the purity of the gas flowing in the line is lowered. Therefore, maintenance (replacement, repair, etc.) of the compressor unit must also be performed frequently.

  Since fluorine gas has extremely strong toxicity to the human body, sufficient maintenance is required to prevent contact with the human body when performing maintenance on the fluorine gas line. Therefore, the maintenance of the fluorine gas line is more complicated than the maintenance of the hydrogen gas line, so the maintenance cost is expensive.

  An object of the present invention is to provide a gas generation apparatus and a gas generation method capable of stably obtaining high-purity fluorine gas over a long period while sufficiently reducing maintenance costs.

  (1) A gas generator according to a first invention is a gas generator that generates fluorine by electrolysis, and is an electrolysis that contains an electrolytic bath that is partitioned into an anode chamber and a cathode chamber and contains a compound to be electrolyzed. A tank, a fluorine gas discharge path for discharging the fluorine gas generated in the anode chamber, a pressure measuring means for measuring the pressure in the anode chamber, a pump provided in the fluorine gas discharge path, and a drive applied to the pump motor An inverter circuit for generating a voltage, and a control means for controlling at least one of an effective value and a frequency of the drive voltage generated by the inverter circuit so that the rotational speed of the motor changes based on the pressure measured by the pressure measuring means. Is provided.

  In this gas generator, fluorine gas generated by electrolysis from the electrolytic bath is discharged through a fluorine gas discharge path. A pump is provided in the fluorine gas discharge path.

  A driving voltage is applied from the inverter circuit to the motor of the pump. At least one of the effective value and frequency of the drive voltage applied to the motor from the inverter circuit is controlled based on the pressure in the anode chamber measured by the pressure measuring means. Thereby, the rotational speed of the motor changes continuously and finely. Thereby, the pressure in the anode chamber can be accurately adjusted. As a result, it is possible to sufficiently suppress pressure fluctuations in the anode chamber and perform stable electrolysis.

  In the pump, since the rotation speed of the motor continuously and finely changes, the load applied to the components of the pump is sufficiently reduced as compared with the case where the motor always operates at the rated rotation speed. Thereby, the life extension of the pump is realized.

  Moreover, generation | occurrence | production of the particle | grains by abrasion of the structural member of a pump is prevented, and it is suppressed that the purity of the fluorine gas which flows through a fluorine gas discharge path falls. As a result, high-purity fluorine gas can be discharged through the fluorine gas discharge path.

  Maintenance of the fluorine gas discharge path is complicated in preparation and work, so that the maintenance cost is expensive. In this gas generator, since the wear of the components of the pump is suppressed, the maintenance frequency of the pump is reduced. As a result, the maintenance cost of the gas generator is sufficiently reduced.

  As described above, according to this gas generator, it is possible to stably discharge high-purity fluorine gas over a long period while sufficiently reducing the maintenance cost.

  (2) The control means may control at least one of an effective value and a frequency of the drive voltage generated by the inverter circuit so that the pressure in the anode chamber measured by the pressure measurement means becomes a predetermined pressure value.

  Fluorine gas is very toxic to the human body. Therefore, in a gas generator that generates fluorine gas, it is necessary to consider sufficient safety as compared with gas generators that generate other gases. Therefore, the level control of the electrolytic bath in the anode chamber must be performed sufficiently accurately during electrolysis.

  The liquid level of the electrolytic bath in the electrolytic cell varies depending on the pressure variation in the anode chamber. Therefore, as described above, at least one of the effective value and the frequency of the drive voltage applied to the motor from the inverter circuit is controlled so that the pressure in the anode chamber measured by the pressure measuring means becomes a predetermined pressure value. . In this case, the rotational speed of the motor changes, and the pressure in the anode chamber is maintained at a predetermined pressure. Thereby, it is possible to prevent the liquid level of the electrolytic bath from fluctuating rapidly during electrolysis. As a result, smooth operation of the gas generator is realized.

  (3) The control means is configured such that the pressure in the anode chamber measured by the pressure measuring means reaches a predetermined pressure value from the time when the electrolysis is started by applying a voltage to the electrolytic bath accommodated in the electrolytic cell. In the meantime, the inverter circuit may be controlled so that at least one of the effective value and the frequency of the drive voltage generated by the inverter circuit continuously increases.

  Immediately after the voltage is applied to the electrolytic bath, the state of electrolysis is unstable. Therefore, the generation amount of fluorine gas may increase sharply. In this case, the pressure in the anode chamber increases steeply, and the liquid level of the electrolytic bath also varies steeply. Therefore, from the start of electrolysis until the pressure in the anode chamber reaches a predetermined pressure value, at least one of the effective value and frequency of the drive voltage generated by the inverter circuit is controlled to increase continuously. The

  Thus, even when the amount of fluorine gas generated increases immediately after the start of electrolysis, the pressure in the anode chamber is suppressed from increasing sharply. Thereby, it is suppressed that the liquid level of the electrolytic bath fluctuates sharply. As a result, even at the start of electrolysis, it is possible to sufficiently suppress pressure fluctuation in the anode chamber and perform stable electrolysis.

  (4) The gas generator further includes opening / closing means for opening / closing the fluorine gas discharge path, and the control means opens the opening / closing means when electrolysis is performed in the electrolytic cell, and the electrolysis is not performed in the electrolytic cell. The opening / closing means may be controlled to close the opening / closing means.

  As described above, when the electrolysis is not performed in the electrolytic cell, the opening / closing means is closed to prevent the pressure state in the anode chamber from largely fluctuating without the electrolysis. This reliably prevents the external atmosphere from flowing back into the anode chamber without electrolysis and the leakage of fluorine gas in the anode chamber to the outside.

  (5) A gas generation method according to the second invention is a gas generation method for generating fluorine gas by electrolysis using an electrolytic cell partitioned into an anode chamber and a cathode chamber, and is accommodated in the electrolytic cell. A step of generating fluorine gas in the anode chamber by applying a voltage to the electrolytic bath, a step of measuring the pressure in the anode chamber, and a fluorine gas generated in the anode chamber being discharged from the anode chamber through a fluorine gas discharge path by a pump Applying a drive voltage generated by the inverter circuit to the pump motor, an effective value of the drive voltage generated by the inverter circuit so that the rotational speed of the motor changes based on the measured pressure, and Controlling at least one of the frequencies.

  In this gas generating method, fluorine gas is generated in the anode chamber by applying a voltage to the electrolytic bath accommodated in the electrolytic cell. Then, the drive voltage generated by the inverter circuit is applied to the pump motor, and the fluorine gas generated in the anode chamber is discharged by the pump through the fluorine gas discharge path.

  At this time, the pressure in the anode chamber is measured. Based on the measured pressure, at least one of the effective value and frequency of the drive voltage generated by the inverter circuit is controlled so that the rotational speed of the motor changes. Thereby, the rotational speed of the motor changes continuously and finely. Thereby, the pressure in the anode chamber can be accurately adjusted. As a result, it is possible to sufficiently suppress pressure fluctuations in the anode chamber and perform stable electrolysis.

  In the pump, since the rotation speed of the motor continuously and finely changes, the load applied to the components of the pump is sufficiently reduced as compared with the case where the motor always operates at the rated rotation speed. Thereby, the life extension of the pump is realized.

  Moreover, generation | occurrence | production of the particle | grains by abrasion of the structural member of a pump is prevented, and it is suppressed that the purity of the fluorine gas which flows through a fluorine gas discharge path falls. As a result, high-purity fluorine gas can be discharged through the fluorine gas discharge path.

  Maintenance of the fluorine gas discharge path is complicated in preparation and work, so that the maintenance cost is expensive. According to this gas generation method, since wear of the constituent members of the pump is suppressed, the number of maintenance of the pump is reduced. As a result, the maintenance cost of the pump is sufficiently reduced.

  As described above, according to this gas generation method, it is possible to stably discharge high-purity fluorine gas over a long period while sufficiently reducing the maintenance cost.

  (6) The gas generation method may further include a step of closing the fluorine gas discharge path by the opening / closing means when electrolysis is not performed in the electrolytic cell.

  As described above, when the electrolysis is not performed in the electrolytic cell, the opening / closing means is closed to prevent the pressure state in the anode chamber from largely fluctuating without the electrolysis. This reliably prevents the external atmosphere from flowing back into the anode chamber without electrolysis and the leakage of fluorine gas in the anode chamber to the outside.

  According to the present invention, it is possible to obtain a fluorine gas having a high purity stably over a long period of time while sufficiently reducing the maintenance cost.

It is a schematic diagram which shows the structure of the fluorine gas generator which concerns on one embodiment of this invention. It is a block diagram which shows a part of control system in the fluorine gas generator of FIG. It is a figure for demonstrating the example of control of the compressor inserted in the fluorine gas exhaust pipe of FIG. It is a flowchart which shows the control operation for the pressure regulation of the anode chamber by the control apparatus of FIG.

  Hereinafter, a gas generation device and a gas generation method according to an embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of Fluorine Gas Generating Device FIG. 1 is a schematic diagram showing a configuration of a fluorine gas generating device according to an embodiment of the present invention. As shown in FIG. 1, the fluorine gas generator 100 includes an electrolytic cell 1. The electrolytic cell 1 is made of a metal or alloy such as Ni (nickel), monel, pure iron or stainless steel. The electrolytic cell 1 is partitioned into a cathode chamber 3 and an anode chamber 4 by a partition wall 2. The partition 2 is made of Ni or Monel, for example.

  An electrolytic bath 5 made of a KF-HF mixed molten salt is formed in the electrolytic cell 1. A cathode 6 made of, for example, Ni (nickel) is provided in the cathode chamber 3, and an anode 7 made of, for example, low polarizability carbon is provided in the anode chamber 4. HF (hydrogen fluoride) is supplied to the electrolytic bath 5 in the electrolytic cell 1 through the HF supply pipe 10, and electrolysis of HF is performed. Thereby, hydrogen gas is mainly generated from the cathode 6 of the electrolytic cell 1, and fluorine gas is mainly generated from the anode 7.

  In the upper part of the cathode chamber 3, a cathode outlet 20a is provided. One end (upstream end) of the hydrogen gas discharge pipe 20 is connected to the cathode outlet 20a. Hydrogen gas generated in the cathode chamber 3 is discharged through the hydrogen gas discharge pipe 20 from the cathode outlet 20a. An HF adsorption tower 24, a control valve 21, a compressor 22 and a control valve 23 are inserted in this order from the upstream side to the downstream side of the hydrogen gas discharge pipe 20.

  The HF adsorption tower 24 is filled with NaF or the like. The HF adsorption tower 24 adsorbs HF from a mixed gas of hydrogen gas and HF discharged from the cathode chamber 3. In the following description, the mixed gas of hydrogen gas and HF discharged from the cathode chamber 3 is appropriately referred to as hydrogen gas. An inverter circuit 22I is connected to the compressor 22. The drive voltage generated by the inverter circuit 22I is given to the compressor 22.

  The downstream end of the hydrogen gas discharge pipe 20 is connected to, for example, a gas cylinder or a factory production line. Thereby, the hydrogen gas discharged | emitted from the cathode chamber 3 is stored by a gas cylinder, or is supplied to the manufacturing line of a factory.

  In the upper part of the anode chamber 4, an anode outlet 30 a is provided. One end (upstream end) of the fluorine gas discharge pipe 30 is connected to the anode outlet 30a. The fluorine gas generated in the anode chamber 4 is discharged through the fluorine gas discharge pipe 30 from the anode outlet 30a. In the fluorine gas discharge pipe 30, an HF adsorption tower 34, a control valve 31, a compressor 32, and a control valve 33 are inserted in this order from upstream to downstream.

  The HF adsorption tower 34 is filled with NaF or the like. The HF adsorption tower 34 adsorbs HF from the mixed gas of fluorine gas and HF discharged from the anode chamber 4. In the following description, the mixed gas of fluorine gas and HF discharged from the anode chamber 4 is appropriately referred to as fluorine gas. An inverter circuit 32I is connected to the compressor 32. The drive voltage generated by the inverter circuit 32I is given to the compressor 32.

  The downstream end of the fluorine gas discharge pipe 30 is connected to, for example, a gas cylinder or a factory production line. Thereby, the fluorine gas discharged | emitted from the anode chamber 4 is stored by a gas cylinder, or is supplied to the manufacturing line of a factory.

  The cathode chamber 3 is provided with a pressure gauge PS1 for measuring the pressure in the cathode chamber 3. In the anode chamber 4, a pressure gauge PS <b> 2 that measures the pressure in the anode chamber 4 is provided.

  An automatic valve 11 and an orifice 12 are inserted in the HF supply pipe 10. In order to prevent the electrolytic bath 5 from being sucked into the HF supply pipe 10, a control valve 13 is connected between the HF supply pipe 10 downstream of the orifice 12 and the hydrogen gas discharge pipe 7. The HF supply pipe 10 is provided with a pressure gauge PS3.

(2) Control system of fluorine gas generator The control device 90 includes a CPU (Central Processing Unit) and a memory or a macro computer, and controls the operation of each component of the fluorine gas generator 100. For example, the control device 90 applies a voltage for electrolysis between the cathode 6 and the anode 7. The output signal of the pressure gauge PS3 is given to the control device 90. Thus, the control device 90 controls the open / close state of the control valve 13 based on the output signal of the pressure gauge PS3. Specifically, the control device 90 opens the control valve 13 when the internal pressure of the HF supply pipe 10 is lower than a predetermined pressure. Thereby, the electrolytic bath 5 is prevented from being sucked into the HF supply pipe 10.

  Further, the control device 90 controls the operations of the inverter circuits 22I and 32I, the compressors 22 and 32, and the control valves 21, 23, 31, and 33. FIG. 2 is a block diagram showing a part of a control system in the fluorine gas generator 100 of FIG.

  As shown in FIG. 2, an output signal is given to the control device 90 from a pressure gauge PS1 provided in the cathode chamber 3. In this case, the control device 90 controls the inverter circuit 22I based on the output signal from the pressure gauge PS1. Specifically, control device 90 controls at least one of the effective value and frequency of the drive voltage of compressor 22 generated in inverter circuit 22I. As a result, the rotational speed of the motor 22M built in the compressor 22 is continuously and finely varied within a range equal to or lower than the rated rotational speed. Thereby, the discharge pressure of the hydrogen gas discharged from the compressor 22 can be continuously and finely adjusted.

  The control device 90 opens the control valves 21 and 23 when HF electrolysis is performed, and closes the control valves 21 and 23 when HF electrolysis is not performed. This prevents the hydrogen gas on the downstream side of the compressor 22 from being sucked into the cathode chamber 3 when HF is not electrolyzed. Thereby, the pressure inside the cathode chamber 3 is prevented from fluctuating significantly, and failure of the compressor 22 due to the backflow of hydrogen gas through the compressor 22 is prevented.

  An output signal is given to the control device 90 from a pressure gauge PS2 provided in the anode chamber 4. The control device 90 controls the inverter circuit 32I and the control valves 31 and 33 based on the output signal from the pressure gauge PS2. Specifically, control device 90 controls at least one of the effective value and frequency of the drive voltage of compressor 22 generated in inverter circuit 32I. As a result, the rotational speed of the motor 32M built in the compressor 32 is continuously and finely varied within a range equal to or lower than the rated rotational speed. Thereby, the discharge pressure of the fluorine gas discharged from the compressor 32 can be adjusted continuously and finely.

  The control device 90 opens the control valves 31 and 33 when HF electrolysis is performed, and closes the control valves 31 and 33 when HF electrolysis is not performed. This prevents the fluorine gas on the downstream side of the compressor 32 from being sucked into the anode chamber 4 when HF is not electrolyzed. Thereby, the pressure in the anode chamber 4 is prevented from fluctuating significantly, and failure of the compressor 32 due to the backflow of fluorine gas through the compressor 32 is prevented.

(3) Operation control of the compressor inserted in the fluorine gas discharge pipe In the following description, the pressure on the upstream side of the compressor 32 and the internal pressure of the anode chamber 4 in the fluorine gas discharge pipe 30 in FIG. The pressure on the downstream side of the compressor 32 in the fluorine gas discharge pipe 30 is referred to as a secondary pressure. In the present embodiment, the primary pressure is measured by the pressure gauge PS2 in FIG.

  The compressor 32 of FIG. 1 is used for adjusting the pressure in the anode chamber 4 during electrolysis of HF, that is, for accurately adjusting the primary pressure. Specifically, the compressor 32 maintains the primary pressure at a predetermined value (target pressure value α) during the electrolysis of HF. Thereby, the fluctuation | variation of the electrolysis conditions of HF is fully suppressed. The target pressure value α is set to 100 kPa as an absolute pressure, for example. Hereinafter, a control example of the compressor 32 will be described.

  FIG. 3 is a diagram for explaining a control example of the compressor 32 inserted in the fluorine gas discharge pipe 30 of FIG. FIG. 3A shows a change in primary pressure when HF electrolysis is performed. In Fig.3 (a), a vertical axis | shaft shows a primary pressure and a horizontal axis shows time. FIG. 3B shows a change in the drive voltage of the motor 32M (FIG. 2) when HF electrolysis is performed. In FIG. 3B, the vertical axis indicates the drive voltage of the motor 32M, and the horizontal axis indicates time.

  In FIG. 3, a voltage for electrolysis is applied between the cathode 6 and the anode 7 by the control device 90 of FIG. Thereby, the electrolysis of HF is started. 1 is switched from the closed state to the open state by the control device 90.

  When the electrolysis of HF is started, fluorine gas is generated in the anode chamber 4 of FIG. Thereby, the pressure in the anode chamber 4, that is, the primary pressure rises from 0 kPa (atmospheric pressure) in terms of gauge pressure. At this time, the primary pressure is measured by the pressure gauge PS2 and given to the control device 90.

  When the primary pressure reaches the target pressure value α at time t1, the control device 90 controls the inverter circuit 32I of FIG. 1 so that the primary pressure is kept constant at the target pressure value α.

  As a result, as shown in FIG. 3B, the driving voltage applied to the motor 32M of the compressor 32 rises sharply from 0V to a predetermined voltage value β from time t1 to time t2. Thereby, the motor 32M performs a rotation operation at a rotation speed corresponding to the applied drive voltage.

  By operating the motor 32M, the fluorine gas in the anode chamber 4 is sucked through the fluorine gas discharge pipe 30 and discharged. This prevents the primary pressure from continuing to increase beyond the target pressure value α from the time point t1 to t2.

  Thereafter, when the amount of fluorine gas generated in the anode chamber 4 gradually increases from time t2 to time t3, the control device 90 controls the inverter circuit 32I according to the change in the primary pressure measured by the pressure gauge PS2. As a result, the drive voltage applied to the motor 32M gradually increases within the range of the rated voltage of the motor 32M or less, and the rotational speed of the motor 32M gradually increases. As a result, the primary pressure is kept constant at the target pressure value α from time t2 to time t3.

  After time t3, the amount of gas generated in the anode chamber 4 is kept constant. In this case, the control device 90 keeps the drive voltage applied to the motor 32M constant by controlling the inverter circuit 32I. As a result, the rotational speed of the motor 32M is kept constant, and the primary pressure is kept constant at the target pressure value α.

  In the above description, the control example of the compressor 32 inserted in the fluorine gas discharge pipe 30 and the operation thereof have been described, but the same control is performed on the compressor 22 inserted in the hydrogen gas discharge pipe 20.

(4) Control Flow A control flow for adjusting the pressure in the anode chamber 4 by the control device 90 of FIG. 1 will be described. FIG. 4 is a flowchart showing a control operation for adjusting the pressure of the anode chamber 4 by the control device 90 of FIG.

  First, when the start of electrolysis of HF is instructed by an input device or the like (not shown), the control device 90 applies a predetermined voltage between the cathode 6 and the anode 7 (step S11), and the fluorine gas discharge pipe The two control valves 31 and 33 inserted in 30 are opened (step S12).

  And the control apparatus 90 detects a primary pressure based on the pressure value of the anode chamber 4 measured by the pressure gauge PS2 (step S13).

  Here, in the control device 90, the target pressure value α of the anode chamber 4 is stored in advance. The target pressure value α is set by, for example, an operator operating an input device or the like.

  The control device 90 determines whether or not the detected primary pressure value matches the preset target pressure value α (step S14).

  When the primary pressure value matches the target pressure value α, the control device 90 controls the inverter circuit 32I in FIG. 2 to maintain the drive voltage applied to the motor 32M in FIG. 2 at the current voltage value ( Step S15).

  Subsequently, the control device 90 determines whether or not the termination of the electrolysis of HF is instructed by the input device or the like (step S16). When the end of electrolysis is not instructed, the control device 90 returns to the process of step S13. On the other hand, when the end of the electrolysis is instructed, the control device 90 ends the application of the voltage between the cathode 6 and the anode 7 (step S17), and the two devices inserted in the fluorine gas discharge pipe 30 are used. The control valves 31 and 33 are closed (step S18).

  If the primary pressure value does not match the target pressure value α in step S14, the control device 90 compares the primary pressure value with the target pressure value α, and controls the inverter circuit 32I based on the comparison result. . Thereby, the drive voltage applied to the motor 32M in FIG. 2 is continuously and finely varied from the current voltage value (step S21).

  For example, when the primary pressure value is lower than the target pressure value α, the control device 90 controls the inverter circuit 32I so that the drive voltage applied to the motor 32M in FIG. 2 decreases. As a result, the rotational speed of the motor 32M decreases, and the suction force of the compressor 32 decreases. As a result, the primary pressure increases.

  Conversely, when the primary pressure value is higher than the target pressure value α, the control device 90 controls the inverter circuit 32I so that the drive voltage applied to the motor 32M in FIG. 2 increases. As a result, the rotational speed of the motor 32M increases, and the suction force of the compressor 32 increases. As a result, the primary pressure decreases.

  When the control of the compressor 32 is performed as described above, even when the primary pressure value matches the target pressure value α, the rotational speed of the motor 32M is increased when the difference between the primary pressure and the secondary pressure is large. Get higher. Even when the primary pressure value matches the target pressure value α, the rotational speed of the motor 32M decreases when the difference between the primary pressure and the secondary pressure is small. That is, when the secondary pressure changes, the rotation speed of the motor 32M changes in order to make the primary pressure value coincide with the target pressure value α.

  After the process of step S21, the control device 90 proceeds to the process of step S16. In steps S12 to S16 and S21 described above, the pressure adjustment of the anode chamber 4 has been described. However, the pressure adjustment of the cathode chamber 3 is performed in the same manner as the pressure adjustment of the anode chamber 4.

(5) Effects (a) As described above, in the fluorine gas generator 100 according to the present embodiment, the inverter circuit 32I continuously and finely changes the drive voltage of the motor 32M within the range of the rated voltage or less. Thereby, the pressure adjustment (adjustment of the primary pressure) of the anode chamber 4 is performed. Thereby, the fluctuation | variation of the electrolysis conditions of HF is fully suppressed, and the electrolysis of HF is performed stably.

  (B) Fluorine gas is very toxic to the human body. Therefore, in the fluorine gas generator, it is necessary to consider sufficient safety as compared with gas generators that generate other gases. As a result, the level of the electrolytic bath in the anode chamber must be sufficiently accurately controlled during electrolysis of HF. The liquid level height of the electrolytic bath varies according to the pressure variation in the anode chamber.

  For this reason, the fluctuation range of the electrolytic bath liquid level allowed in the fluorine gas generator is equal to the fluctuation range of the electrolytic bath liquid level allowed in the gas generator that generates other gases. It is set smaller than this.

  Therefore, the operation of the fluorine gas generator may be forcibly stopped even when the liquid level fluctuation of the electrolytic bath allowed by the gas generator that generates other gas occurs.

  On the other hand, in the fluorine gas generator 100 described above, the inverter circuit 32I is controlled so that the pressure in the anode chamber 4 becomes the target pressure value α. Thereby, the pressure in the anode chamber 4 is accurately maintained at the target pressure value α. Thereby, it is sufficiently suppressed that the liquid level of the electrolytic bath 5 fluctuates during the electrolysis of HF. As a result, smooth operation of the fluorine gas generator 100 is realized.

  (C) In the compressor 32, the rotational speed of the motor 32M changes continuously and finely within a range equal to or lower than the rated rotational speed in accordance with fluctuations in the primary pressure and the secondary pressure. As a result, the load applied to the constituent members of the compressor 32 is sufficiently reduced as compared with the case where the motor 32M always operates at the rated rotational speed. Thereby, the lifetime of the compressor 32 is extended.

  (D) Moreover, generation | occurrence | production of the particle by abrasion of the structural member of the compressor 32 is prevented, and it is suppressed that the purity of the fluorine gas which flows through the fluorine gas discharge pipe 30 falls. As a result, high-purity fluorine gas can be stably obtained through the fluorine gas discharge pipe 30.

  In the present embodiment, the same control operation as described above is performed for the compressor 22 as well. Therefore, the life of the compressor 22 is extended, and it is possible to stably obtain high-purity hydrogen gas through the hydrogen gas discharge pipe 20.

  (E) The maintenance of the fluorine gas line is more complicated in preparation and work than the maintenance of the hydrogen gas line, so the maintenance cost is expensive.

  In the fluorine gas generation device 100 according to the present embodiment, since the wear of the constituent members of the compressor 32 is suppressed, the number of maintenance times of the compressor 32 is reduced. As a result, the maintenance cost of the fluorine gas generator 100 is sufficiently reduced.

(6) Modification (a) Immediately after voltage is applied to the electrolytic bath 5, the state of electrolysis of HF is unstable. Therefore, the generation amount of fluorine gas may increase sharply. In this case, the pressure in the anode chamber 4 rises steeply, and the liquid level of the electrolytic bath 5 also changes steeply.

  Therefore, the controller 90 drives the drive voltage generated by the inverter circuit 32I from when the electrolysis of HF is started until the pressure in the anode chamber 4 measured by the pressure gauge PS2 reaches the target pressure value α. The inverter circuit 32I may be controlled so that at least one of the effective value and the frequency increases continuously.

  As a result, even when the amount of fluorine gas generated increases immediately after the start of HF electrolysis, the pressure in the anode chamber 4 is suppressed from increasing sharply. As a result, the liquid surface height of the electrolytic bath 5 is also suppressed from changing sharply. As a result, even at the start of electrolysis, it is possible to sufficiently suppress pressure fluctuation in the anode chamber and perform stable electrolysis.

  (B) The control device 90 may close either one of the control valves 31 and 33 inserted in the fluorine gas discharge pipe 30 when the electrolysis of HF is stopped. Thereby, when the electrolysis of HF is stopped, the pressure state in the anode chamber 4 is prevented from fluctuating greatly.

  In this case, it is preferable to close the control valve 31 on the downstream side of the compressor 32. This prevents the fluorine gas from flowing back through the compressor 32. As a result, failure of the compressor 32 is prevented.

  Similarly, the control device 90 may close either one of the control valves 21 and 23 inserted in the hydrogen gas discharge pipe 20 when the electrolysis of HF is stopped. Thereby, when the electrolysis of HF is stopped, the pressure state in the cathode chamber 3 is prevented from fluctuating greatly.

  In this case, it is preferable to close the control valve 21 on the downstream side of the compressor 22. This prevents hydrogen gas from flowing back through the compressor 22. As a result, failure of the compressor 22 is prevented.

  (C) The fluorine gas discharge pipe 30 may be provided with one of the control valves 31 and 33 instead of providing the control valves 31 and 33. In this case, when the electrolysis of HF is stopped, the control valve inserted in the fluorine gas discharge pipe 30 is closed. Thereby, when the electrolysis of HF is stopped, the pressure state in the anode chamber 4 is prevented from fluctuating greatly.

  In this case, it is preferable to insert a control valve 33 on the downstream side of the compressor 32 in the fluorine gas discharge pipe 30. Thereby, when the electrolysis of HF is stopped, the compressor 32 is prevented from malfunctioning due to the backflow of fluorine gas.

  Instead of providing the control valves 21 and 23, one of the control valves 21 and 23 may be provided in the hydrogen gas discharge pipe 20. In this case, when the electrolysis of HF is stopped, the control valve inserted in the hydrogen gas discharge pipe 20 is closed. Thereby, when the electrolysis of HF is stopped, the pressure state in the cathode chamber 3 is prevented from fluctuating greatly.

  In this case, it is preferable to insert a control valve 23 on the downstream side of the compressor 22 in the hydrogen gas discharge pipe 20. Thereby, when the electrolysis of HF is stopped, the compressor 22 is prevented from malfunctioning due to the backflow of hydrogen gas.

  (D) As the compressors 22 and 32, reversible rotary pumps that permit rotation in one direction and in the opposite direction of the built-in motors 22M and 32M may be used. In this case, even if hydrogen gas and fluorine gas flow backward, the compressors 22 and 32 do not fail. This eliminates the need to provide the control valves 23 and 33 on the downstream side of the compressors 22 and 32. As a result, the increase in size of the entire fluorine gas generator 100 is suppressed.

  (E) The pressure in the cathode chamber 3 may be adjusted by operating the compressor 22 provided in the hydrogen gas discharge pipe 20 at a constant capacity at all times and controlling the open / closed state of at least one of the control valves 21 and 22. .

When the pressure in the cathode chamber 3 is adjusted by controlling the open / closed state of at least one of the control valves 21, 22, a hydrogen gas disposal device is provided at the downstream end of the hydrogen gas discharge pipe 20 instead of the compressor 22. May be. Thereby, the hydrogen gas sent from the cathode chamber 3 to the hydrogen gas disposal device through the hydrogen gas discharge pipe 20 is diluted with the N ₂ gas for dilution and discarded into the atmosphere.

(7) Correspondence between each constituent element of claims and each element of the embodiment Hereinafter, an example of correspondence between each constituent element of the claims and each element of the embodiment will be described. It is not limited to.

  In the above embodiment, the fluorine gas discharge pipe 30 is an example of the fluorine gas discharge path, the pressure gauge PS2 is an example of the first pressure measuring means, the compressor 32 is an example of the pump, and the motor 32M is the motor. The inverter circuit 32I is an example of an inverter circuit, the control device 90 is an example of a control means, and at least one of the control valves 31, 33 is an example of an opening / closing means.

  As each constituent element in the claims, various other elements having configurations or functions described in the claims can be used.

  The present invention can be used to generate fluorine gas by electrolysis.

DESCRIPTION OF SYMBOLS 1 Electrolysis tank 3 Cathode chamber 4 Anode chamber 5 Electrolytic bath 30 Fluorine gas discharge pipe 31, 33 Control valve 22, 32 Compressor 100 Fluorine gas generator 22I, 32I Inverter circuit 22M, 32M Motor PS1, PS2, PS3 Pressure gauge

Claims (6)

A gas generator for generating fluorine by electrolysis,
An electrolytic cell containing an electrolytic bath partitioned into an anode chamber and a cathode chamber and containing a compound to be electrolyzed;
A fluorine gas discharge path for discharging the fluorine gas generated in the anode chamber;
Pressure measuring means for measuring the pressure in the anode chamber;
A pump provided in the fluorine gas discharge path;
An inverter circuit for generating a drive voltage applied to the pump motor;
Control means for controlling at least one of an effective value and a frequency of the drive voltage generated by the inverter circuit so that the rotational speed of the motor changes based on the pressure measured by the pressure measuring means. A gas generator. The control means controls at least one of an effective value and a frequency of the drive voltage generated by the inverter circuit so that the pressure in the anode chamber measured by the pressure measuring means becomes a predetermined pressure value. The gas generator according to claim 1. The control means includes a period from when electrolysis is started by applying a voltage to the electrolytic bath until the pressure in the anode chamber measured by the pressure measuring means reaches the predetermined pressure value. 3. The gas generator according to claim 2, wherein the inverter circuit is controlled so that at least one of an effective value and a frequency of the drive voltage generated by the inverter circuit continuously increases. An opening / closing means for opening / closing the fluorine gas discharge path;
The control means controls the opening / closing means to open the opening / closing means when electrolysis is performed in the electrolytic cell and to close the opening / closing means when electrolysis is not performed in the electrolytic cell. The gas generator according to any one of claims 1 to 3. A gas generation method for generating fluorine gas by electrolysis using an electrolytic cell partitioned into an anode chamber and a cathode chamber,
Generating fluorine gas in the anode chamber by applying a voltage to an electrolytic bath housed in the electrolytic cell;
Measuring the pressure in the anode chamber;
Discharging the fluorine gas generated in the anode chamber from the anode chamber through a fluorine gas discharge path by a pump;
Applying a drive voltage generated by an inverter circuit to the motor of the pump;
Controlling the effective value and / or frequency of the drive voltage generated by the inverter circuit so that the rotational speed of the motor changes based on the measured pressure. . 6. The gas generation method according to claim 5, further comprising a step of closing the fluorine gas discharge path by an opening / closing means when electrolysis is not performed in the electrolytic cell.

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