JP2012154840A - Liquid level gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level gauge that can detect a position and the like of an upper layer liquid with high accuracy with a simple structure without being unnecessarily corroded even when the upper layer liquid and a lower layer liquid are kept at a high temperature and highly corrosive to metal, in a storage tank or a reaction tank storing a two-layer structured liquid whose upper layer liquid is a low conductive liquid such as an electrolyte and whose lower layer liquid has a higher specific gravity than that of the upper layer liquid to be unnecessarily mixed with the upper layer liquid and is a liquid having higher conductivity than that of the upper layer liquid.SOLUTION: A liquid level position and the like of the upper layer liquid 22 is detected according to a change in admittance output between a pair of electrodes 30, 40, 130, 140 in a state being supplied with AC current from an AC power source 50, especially a change in admittance output between probes 34, 44, 132b, 142b having a contact outer surface made of a material exhibiting corrosion resistance to the liquids.

Description

  The present invention relates to a level gauge that detects the position of a liquid surface by passing an alternating current between electrodes immersed in the liquid, and in particular, a high-temperature molten metal liquid is located under a high-temperature molten salt liquid. The present invention relates to a liquid level gauge for detecting the liquid level position of a two-layered liquid composed of two kinds of corrosive high-temperature liquids having different specific gravity and not easily mixed.

  In recent years, as a level gauge for detecting the position of the liquid level in a storage tank or reaction tank, a plurality of electrodes are installed in the liquid, and the capacitance value between the electrodes due to the change in the position of the liquid level, etc. Change to detect the position of the liquid level, Install a float in the liquid, detect the position of the liquid level by changing the float position, and the distance to the liquid level by ultrasonic or laser light A configuration such as one that measures and detects the position of the liquid level is used.

  Among these, the configuration for detecting the position of the liquid level from above using ultrasonic waves or laser light is a stable liquid level when there is a mist layer formed by cooling the liquid vapor on the liquid level. It is difficult to detect the position. When using ultrasonic waves, an oscillator may be installed at the bottom of the storage tank, and the liquid level may be detected from below, but when targeting a high-temperature liquid such as a molten salt, It is difficult to install an oscillator.

  In the configuration using the float, instead of directly detecting the liquid level, the detection is merely performed using a float that is easy to detect the position. There is no change in what must be detected.

  On the other hand, the configuration in which the liquid surface position is detected by a change in capacitance value between a plurality of electrodes has an advantage that the structure is simple and high temperature liquid can be used as a target.

  Patent Document 1 discloses a capacitance type liquid level gauge provided with a rod-shaped center electrode and an outer cylinder electrode, both of which are made of brass or stainless steel metal.

JP 2004-286651 A

  However, according to the study of the present inventor, since the capacitance type liquid level gauge disclosed in Patent Document 1 is for measuring the liquid level of the liquid in the liquefied gas tank, a metal such as brass or stainless steel is used. It only has a configuration with a pair of manufactured electrodes, and does not propose any configuration for detecting the liquid level or interface of a two-layer liquid composed of a highly corrosive electrolyte or metal at high temperatures. .

In particular, according to the study by the present inventor, in the case where molten zinc chloride is electrolyzed in an electrolytic reaction vessel to obtain molten zinc, both molten zinc chloride and molten zinc are high-temperature metals. Since the liquid is highly corrosive, the position of the liquid surface of the molten zinc chloride located in the upper layer can be detected practically with high accuracy. The position of the interface can be detected accurately and practically, and the supply and electrolysis of molten zinc chloride are stopped at an appropriate timing, contributing to stopping the unnecessary rise and fall of the molten zinc chloride liquid level. A level gauge with a possible configuration is required.

  However, at present, such a level gauge has not been put to practical use, and has a novel configuration that can be applied in practice when electrolysis of molten zinc chloride is performed in an electrolytic reaction vessel to obtain molten zinc. The realization of a liquid level gauge is awaited.

  The present invention has been made through the above-described studies. The upper layer liquid is a liquid having low conductivity such as an electrolytic solution, the lower layer liquid has a higher specific gravity than the upper layer liquid, and is not unnecessarily mixed with the upper layer liquid. In a storage tank or reaction tank in which a liquid having a two-layer structure, which is a liquid with higher conductivity, is stored, both the upper liquid and the lower liquid are maintained at high temperatures and are highly corrosive to metals. An object of the present invention is to provide a liquid level gauge that can detect the position of the liquid level of the upper liquid layer and the like with a simple configuration without causing unnecessary corrosion.

  In order to achieve the above object, in the first aspect, the present invention provides a first liquid that is an electrolyte that is stored in a container and has corrosiveness to a metal, and the first liquid in the container. The same as the first liquid and the second liquid so as to be able to traverse the interface formed with the conductive second liquid that is stored below the liquid and is corrosive to the metal. A pair of electrodes each having a probe with a contact outer surface made of a material that is immersable with an immersion length and is resistant to corrosion with respect to the first liquid and the second liquid; When the AC power source capable of supplying an AC current between each of the probes of a pair of electrodes and the tip of each of the probes of the pair of electrodes are located in the first liquid, Admittance output based on the alternating current flowing between the probes Depending on the reduction, a detecting unit is freely detect the position of the liquid surface of the first liquid, a liquid level meter comprising.

  Further, according to the present invention, in addition to the first aspect, the detection unit further includes an interface between the tip of the probe of each of the pair of electrodes and the interface between the first liquid and the second liquid. It is a second aspect that the position of the interface can be detected in accordance with a change in admittance output based on the alternating current flowing between the probes when crossing.

  Further, in addition to the first or second aspect, the present invention is a columnar member in which each of the probes of the pair of electrodes has a flat surface that can be set parallel to the interface at a tip portion thereof. This is the third aspect.

  In addition to any one of the first to third aspects, a fourth aspect of the present invention is that each of the probes of the pair of electrodes is made of graphite.

  According to the present invention, in addition to any one of the first to fourth aspects, each of the probes of the pair of electrodes communicates with a conductive member of the pair of electrodes, and the conductive According to a fifth aspect, the member is covered with an insulating member exhibiting corrosion resistance with respect to the first liquid and the second liquid.

  According to the present invention, in addition to the first or second aspect, each of the probes of the pair of electrodes constitutes a sheath type thermocouple, and the detection unit further includes the first liquid and The sixth aspect is that the temperature of the second liquid can be detected.

  In addition to the sixth aspect, the present invention has a seventh aspect in which the sheath-type thermocouple is accommodated in a protective tube made of an insulating ceramic.

In addition to any one of the first to seventh aspects of the present invention, the first liquid is a molten salt containing molten zinc chloride, and the second liquid is a molten metal containing molten zinc. It is assumed that there is an eighth aspect.

  In the liquid level gauge according to the first aspect of the present invention, the liquid is stored in the container and is stored below the first liquid in the container and the first liquid that is corrosive to the metal. A material that can be immersed in a conductive second liquid that is corrosive to metal with the same immersion length and that is resistant to corrosion with respect to the first liquid and the second liquid. Using a pair of electrodes each having a probe with a contact outer surface, and supplying the alternating current between the probes while being positioned in the first liquid, the alternating current flowing between the probes By detecting the position of the liquid surface of the first liquid according to the change of the admittance value based on the upper liquid, the upper liquid is a liquid having a low conductivity, such as an electrolytic solution, and the lower liquid has a higher specific gravity than the upper liquid. Liquid that is not mixed unnecessarily and has higher conductivity than the upper liquid layer In the storage tank or reaction tank in which the liquid of the two-layer structure is stored, the upper layer liquid and the lower layer liquid are both maintained at a high temperature and are highly corrosive to metals. The position of the liquid level can be detected with high accuracy, and an unnecessary change in the liquid level of the upper liquid can be reliably stopped at a desired timing as necessary.

  Further, in the liquid level gauge according to the second aspect of the present invention, when the tips of the probes of the pair of electrodes cross the interface between the first liquid and the second liquid, the distance between the probes is further reduced. The position of the interface can be detected in accordance with the change in the admittance output based on the alternating current flowing through the liquid crystal, so that the position of the liquid surface of the upper liquid can be detected with high accuracy with a simple configuration. The position of the interface between the liquid and the lower liquid can be detected with high accuracy, and if necessary, unnecessary changes in the liquid level of the upper liquid and unnecessary changes in the interface between the upper liquid and the lower liquid can be performed at the desired timing. Can be stopped more reliably.

  In the liquid level gauge according to the third aspect of the present invention, each probe of the pair of electrodes is a cylindrical member having a flat surface that can be set parallel to the interface at the tip thereof. The interface between the upper liquid and the lower liquid can be instantaneously crossed, and the position of the interface between the upper liquid and the lower liquid can be detected with higher accuracy.

  In the liquid level gauge according to the fourth aspect of the present invention, the probes of the pair of electrodes are made of graphite, so that both the upper layer liquid and the lower layer liquid are maintained at a high temperature and corrode against the metal. Even if it has high properties, it does not corrode unnecessarily, and with a simple configuration, the position of the liquid surface of the upper liquid and the position of the interface between the upper liquid and the lower liquid can be detected with high accuracy.

  In the liquid level gauge according to the fifth aspect of the present invention, the probes of the pair of electrodes communicate with the conductive members of the electrodes, and the conductive members are the first liquid and the second liquid. By covering with an insulating member that is resistant to corrosion, the upper layer liquid and the lower layer liquid are both kept at a high temperature even when parts other than the probe of the electrode come into contact with droplets or gases such as the upper layer liquid. Even if it is highly corrosive to metals, it does not corrode unnecessarily, and with a simple configuration, the position of the liquid surface of the upper liquid and the position of the interface between the upper liquid and the lower liquid are highly accurate. Can be detected.

  In the liquid level gauge according to the sixth aspect of the present invention, each probe of the pair of electrodes constitutes a sheath type thermocouple and can detect the temperatures of the first liquid and the second liquid. In addition to detecting the position of the liquid level of the upper liquid layer, an additional function of detecting the liquid temperature can also be realized, and the liquid level of the upper liquid layer can be reduced while reducing the total number of electrodes used. The position, liquid temperature, etc. can be detected with high accuracy.

  In the liquid level gauge according to the seventh aspect of the present invention, the sheath-type thermocouple is housed in a protective tube made of insulating ceramic, so that both the upper-layer liquid and the lower-layer liquid are maintained at a high temperature to the metal. Even if it is highly corrosive, it does not corrode unnecessarily, and the position of the upper liquid, the liquid temperature, etc. can be detected with high accuracy with a simple configuration.

  In the liquid level gauge according to the eighth aspect of the present invention, the first liquid is a molten salt containing molten zinc chloride, and the second liquid is a molten metal containing molten zinc. , The position of the liquid surface of the molten zinc chloride can be detected with high accuracy while obtaining molten zinc in the lower layer.

It is typical sectional drawing which shows the structure of the liquid level meter in the 1st Embodiment of this invention, and also shows the storage tank which stores a liquid. It is a graph which shows the change curve of the admittance output of the liquid level meter in this embodiment. It is typical sectional drawing which shows the structure of the liquid level meter in the 2nd Embodiment of this invention, and also shows the storage tank which stores a liquid.

  Hereinafter, the liquid level gauge in each embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the figure, the x-axis and the z-axis form an orthogonal coordinate system, and the direction of the z-axis is a vertical vertical direction.

(First embodiment)
First, the liquid level gauge according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic cross-sectional view showing the configuration of the liquid level gauge in the present embodiment, and also shows a storage tank for storing a liquid. Moreover, FIG. 2 is a graph which shows the change curve of the admittance output of the liquid level meter in this embodiment.

  As shown in FIG. 1, the apparatus S1 in the present embodiment includes a liquid level gauge 10 and a storage tank 20 capable of storing a liquid. Such a device S1 may be a storage device that simply stores liquid, and typically uses a pair of electrolysis electrodes (not shown) to electrolyze molten zinc chloride, It may be an electrolysis device that generates Moreover, when apparatus S1 is an electrolysis apparatus, the storage tank 20 becomes an electrolytic reaction container.

  Specifically, the liquid level meter 10 includes a pair of electrodes 30 and 40 and an AC power supply 50 that communicates with the pair of electrodes 30 and 40 via power supply lines 50a and 50b and applies an AC voltage to flow an AC current. And an AC ammeter 60 connected to one of the power supply lines 50a and 50b, for example, the power supply line 50a, and a controller 70 electrically connected to the AC power supply 50 and the AC ammeter 60. The controller 70 includes an arithmetic device, a memory, etc., not shown.

In addition, typically, the graphite storage tank 20 to which the liquid level gauge 10 is applied is held in a temperature range of about 450 ° C. or more and 550 ° C. or less by a heating mechanism (not shown), and melted therein. Zinc chloride 22 and molten zinc 24 produced electrolytically therefrom are stored. Since the specific gravity of zinc chloride in the temperature range of 450 ° C. or higher and 550 ° C. or lower is about 2.4 and the specific gravity of zinc is about 6.4, both the molten zinc chloride 22 and the molten zinc 24 are Into a two-layered liquid with the molten zinc chloride 22 as the upper layer and the molten zinc 24 as the lower layer. Further, the conductivity of the molten zinc 24 is about five orders of magnitude higher than the conductivity of the molten zinc chloride 22.

  Here, the liquid having such a two-layer structure is not limited to the molten zinc chloride 22 and the molten zinc 24, and the upper layer liquid exhibits high corrosiveness to the metal and has low conductivity such as an electrolytic solution. Molten metal, etc., which is a liquid such as a molten salt, and the lower layer liquid is highly corrosive to metals, has a higher specific gravity than the upper layer liquid, is not unnecessarily mixed with the upper layer liquid, and has a higher conductivity than the upper layer liquid If it is a liquid, it is enough. In addition, when electrolysis is performed using molten zinc chloride as an electrolyte to obtain a liquid having a two-layer structure composed of molten zinc chloride 22 and molten zinc 24, a supporting electrolyte such as lithium chloride or potassium chloride may be used. In such a case, lithium chloride, potassium chloride, or the like may be mixed into the molten zinc chloride 22 and the molten zinc 24.

  In addition, the pair of electrodes 30 and 40 is made of a metal rod-shaped conductive member 32a and 42a surrounded by insulating protective tubes 32b and 42b, and a cylindrical probe made of a conductive member. Tactile elements 34 and 44 are provided correspondingly. Specifically, the protective tubes 32b and 42b are configured so that the conductive members 32a and 42a are not unnecessarily corroded by the droplets or gases of the molten zinc chloride 22 and the molten zinc 24, which have high corrosiveness to metals. A cylindrical insulating member typically made of ceramic and covering the periphery of the rod-like conductive members 32a and 42a. The probes 34 and 44 are each cylindrical, and the outer surfaces thereof are contact outer surfaces with respect to the molten zinc chloride 22 and the molten zinc 24. Further, in the probes 34 and 44, the upper outer surfaces connected to the protective tubes 32b and 42b are formed flush with the outer surfaces of the protective tubes 32b and 42b, and the tip surfaces of the lower ends thereof. Are formed as flat surfaces which can be located parallel to the interface 26 between the molten zinc chloride 22 and the molten zinc 24, respectively.

  Here, the probes 34 and 44 are set as portions that enter and are immersed in a liquid having a two-layer structure composed of the molten zinc chloride 22 and the molten zinc 24, respectively. Specifically, the probes 34 and 44 are set so that the upper ends of the probes 34 and 44 are flush with the liquid surface of the molten zinc chloride 22 or protrude above the liquid surface of the molten zinc chloride 22. The contacts 34, 44 are immersible in the molten zinc chloride 22 and the molten zinc 24 electrolyzed therefrom and are disposed so as to be able to traverse their rising interface 26, typically fixed. In addition, when the position of the interface 26 between the molten zinc chloride 22 and the molten zinc 24 is constant, the probes 34 and 44, that is, the pair of electrodes 30 and 40 are moved to the interface 26, respectively. Can be crossed. Further, it is assumed that the direction in which the probes 34 and 44 relatively cross the interface 26 is a vertical direction and is a direction orthogonal to the interface 26.

  Further, in the state where only the molten zinc chloride 22 is located between the probes 34 and 44, the molten zinc chloride 22 is an electrolyte. Therefore, the electric circuit composed of these is fused between the probes 34 and 44. It is evaluated as an equivalent circuit in which the resistance caused by the zinc chloride 22 and the capacitance are connected in parallel. In the equivalent circuit in such a case, when the immersion length of the probes 34 and 44 in the molten zinc chloride 22 changes, the probes 34 and 44 are maintained in a state where the distance between the probes 34 and 44 is kept constant. Since the length in the vertical direction of the region composed of the molten zinc chloride 22 located therebetween changes, the probes 34 and 44 are a kind of variable resistance and variable that face each other with the molten zinc chloride 22 interposed therebetween. Functions as a condenser. Therefore, the electrical characteristic value composed of such a resistance component and a capacitance component, typically the admittance value, changes continuously according to the immersion length of the probes 34 and 44 in the molten zinc chloride 22. It will be. The inductance value of the molten zinc chloride 22 is substantially negligible.

Further, when air is interposed between the probes 34 and 44 in addition to the molten zinc chloride 22, the equivalent circuit in which only the molten zinc chloride 22 is positioned between the probes 34 and 44 is used. Thus, in addition to the resistance component and capacitance component of the molten zinc chloride 22 between the probes 34 and 44, it is necessary to consider the capacitance component of air between the probes 34 and 44 thereabove. That is, in the equivalent circuit in such a case, when the immersion length of the probes 34 and 44 in the molten zinc chloride 22 changes, the probe 34 is maintained in a state where the distance between the probes 34 and 44 is kept constant. , 44, the ratio of the vertical length of the region composed of molten zinc chloride 22 and the vertical length of the region composed of air above it changes, so that the probes 34, 44 It functions as a kind of variable resistor and variable capacitor that are opposed to each other with molten zinc chloride 22 and air interposed therebetween. Therefore, the electrical characteristic value composed of such a resistance component and a capacitance component, typically the admittance value, changes continuously according to the immersion length of the probes 34 and 44 in the molten zinc chloride 22. It will be.

  Further, in the state where only the molten zinc 24 is located between the probes 34 and 44, the molten zinc 24 is a metal. Therefore, the electric circuit composed of these is caused by the molten zinc 24 between the probes 34 and 44. It is evaluated as an equivalent circuit with a resistor connected. That is, in the equivalent circuit in such a state, the distance between the probes 34 and 44 is constant, so that the resistance value is constant. Note that the capacitance value and the inductance value of the molten zinc 24 are substantially negligible.

  Further, when the probes 34 and 44 cross the interface 26 between the molten zinc chloride 22 and the molten zinc 24 from the molten zinc chloride 22 toward the molten zinc 24, the electric circuit composed of these probes is connected to the probe. In addition to the equivalent circuit in which the resistance caused by the molten zinc chloride 22 and the electrostatic capacitance caused by the molten zinc chloride 22 and the air above it are connected in parallel between the electrodes 34 and 44, in addition to this, the probe 34 is further added. 44, the equivalent circuit in which the resistance caused by the molten zinc 24 is connected is changed to an equivalent circuit connected in parallel. Here, since the resistance value caused by the molten zinc 24 between the probes 34 and 44 is substantially constant and is a relatively small value, the entire equivalent circuit thereof is between the probes 34 and 44. It can be evaluated as an equivalent circuit in which the resistance caused by the molten zinc 24 is connected.

  That is, when the probes 34 and 44 cross the interface 26 between the molten zinc chloride 22 and the molten zinc 24 from the molten zinc chloride 22 toward the molten zinc 24, the electric circuit composed of them is From the equivalent circuit in which the resistance caused by the molten zinc chloride 22 and the electrostatic capacitance caused by the molten zinc chloride 22 and the air above it are connected in parallel between the probes 34 and 44, the fusion between the probes 34 and 44 is achieved. It can be evaluated that the resistance caused by the zinc 24 changes rapidly to an equivalent circuit to which the resistance is connected. From the same discussion, when the probes 34, 44 cross the interface 26 between the molten zinc chloride 22 and the molten zinc 24 from the molten zinc 24 toward the molten zinc chloride 22, the probes 34, From an equivalent circuit in which a resistance caused by molten zinc 24 is connected between 44, a resistance caused by molten zinc chloride 22 between the probes 34 and 44 and an electrostatic charge caused by molten zinc chloride 22 and the air above it. It can be evaluated as an abrupt change to an equivalent circuit in which the capacitance is connected in parallel

  The AC power supply 50 applies an AC voltage by applying an AC voltage between the pair of electrodes 30 and 40, that is, between the probes 34 and 44. The reason why the AC power supply 50 is used as a measurement power supply is that the molten zinc chloride 22 is an electrolyte, and therefore, when a DC voltage is applied and a DC current is applied, the current value flowing between the probes 34 and 44 is not stable. On the other hand, when an AC voltage is applied and an AC voltage is applied, a stable current value can be obtained. Further, the maximum voltage of the AC voltage is set to a range smaller than the electrolysis voltage of the molten zinc chloride 22, for example, a range of 1 V or less so as not to cause unnecessary electrolysis of the molten zinc chloride 22.

As described above, the frequency of the alternating current applied from the alternating current power supply 50 is preferably in the range of 5 Hz to 1000 Hz. Specifically, regarding the lower limit of the frequency of the applied alternating current, the lower the frequency of the applied alternating current, the greater the electrical characteristics detected due to the molten zinc chloride 22, typically the admittance value. Thus, it is preferable from the viewpoint that the measurement accuracy of the position of the liquid surface of the molten zinc chloride 22 can be improved. However, since a stable detection value cannot be practically obtained at a low frequency of less than 5 Hz, the measurement is performed at 5 Hz or more. Preferably there is.

  On the other hand, as for the upper limit of the frequency of the alternating current applied in this way, the higher the frequency of the alternating current applied, the better because it is possible to obtain a stable detection value, but when the frequency exceeds 1000 Hz, The electrical characteristics detected due to the molten zinc chloride 22, typically the admittance value, are significantly reduced, making it impossible to substantially measure the change in the position of the liquid level of the molten zinc chloride 22, Since it is necessary to provide an electromagnetic shield for the controller 70 or the like, or the AC power supply 50 or the AC ammeter 60 is special and tends to be expensive, the frequency is preferably 1000 Hz or less. Furthermore, from the viewpoint that the AC power supply 50, the AC ammeter 60, etc., which are closer to the commercial power supply frequency and are inexpensive and highly reliable, can be used, the frequency of the applied AC current is in the range of 50 Hz to 100 Hz. More preferred.

  The AC ammeter 60 measures an AC current flowing through a circuit system including the pair of electrodes 30 and 40 and the molten zinc chloride 22 and the molten zinc 24 in the electrolytic cell 20.

  Further, the controller 70 controls the AC power supply 50 and the AC ammeter 60, and obtains the liquid level of the molten zinc chloride 22 from the control unit 70a that obtains the admittance output A shown in FIG. 2 and the admittance output A shown in FIG. And a detecting unit 70b for detecting the position of the interface 26 between the molten zinc chloride 22 and the molten zinc 24. In FIG. 2, the horizontal axis indicates the immersion length L (m) that is the length of the probes 34 and 44 of the pair of electrodes 30 and 40 penetrating downward from the liquid surface of the molten zinc chloride 22. Is an admittance output A (V) indicating the voltage value output by the controller 70.

  Specifically, the control unit 70a controls the operation of the AC power supply 50 to supply the above-described AC current between the probes 34 and 44, and also controls the operation of the AC ammeter 60 to measure the AC current. An electrical signal carrying a current value is received. Further, the control unit 70a performs data processing on the electrical characteristic value carried by the electrical signal received from the AC ammeter 60, that is, the AC current value flowing between the probes 34 and 44, with a simple circuit configuration, and the admittance value, , Admittance output A is obtained, and the admittance output A is output to the detection unit 70b. Further, the detection unit 70b detects the position of the liquid level of the molten zinc chloride 22 stored in the storage tank 20 from the admittance output A output from the control unit 70a, and at the same time, between the molten zinc chloride 22 and the molten zinc 24. The position of the interface 26 is detected.

  More specifically, when the probes 34 and 44 of the pair of electrodes 30 and 40 in a state where an alternating current is supplied from the alternating current power supply 50 penetrates relatively downward from the liquid surface of the molten zinc chloride 22, The profile C1 shown in FIG. 2 is obtained in which the admittance output A output from the controller 70 increases in response to the increase in the immersion length L. This is because, when the molten zinc chloride 22 and the air above it are located between the probes 34 and 44, these are the resistance caused by the molten zinc chloride 22 and the static caused by the molten zinc chloride 22 and the air above it. Since an equivalent circuit is formed in which the capacitance is connected in parallel, the capacitance value is increased in response to the increase in the immersion length L. In an ideal system, the profile C1 is linear.

Therefore, in the system composed of the probes 34 and 44, the molten zinc chloride 22 and the air above the memory, the change curve of the admittance output A including the profile C1 is measured in advance and converted into a database, and the illustration of the detection unit 70b is omitted. In the system consisting of the probes 34 and 44 having the same physical characteristics, the molten zinc chloride 22 and the air above it, the liquid of the probes 34 and 44 and the molten zinc chloride 22 is stored. When the positional relationship with the surface changes relatively, referring to the profile C1, typically, the molten zinc chloride is based on the position of the lower end of the probes 34 and 44 to which those positions are fixed. The position of the liquid level of 22 can be detected. Furthermore, when the positions of the probes 34 and 44, that is, the pair of electrodes 30 and 40 are fixed as described above, and the molten zinc chloride 22 is supplied to the storage tank 20, the operator of the apparatus S1 If it can be shown that the admittance output A output from the controller 70 is increased, the operator intuitively understands that the position of the liquid level of the molten zinc chloride 22 is correspondingly increased. Easy to understand. That is, when the liquid level of the molten zinc chloride 22 is rising as described above, the operator or the like can display the display of the liquid level of the molten zinc chloride 22 in addition to the detected position information of the liquid level of the molten zinc chloride 22. By referring to the displayed change curve of the admittance output A, the supply of the molten zinc chloride 22 is stopped according to the desired position of the liquid level of the molten zinc chloride 22, and the liquid level of the molten zinc chloride 22 is unnecessarily increased. Can be stopped reliably.

  On the other hand, the probes 34 and 44 of the pair of electrodes 30 and 40 in a state where an alternating current is supplied from the AC power supply 50 are positioned relatively lower, and the lower ends of the probes 34 and 44 are When entering the molten zinc 24 across the interface 26 between the molten zinc chloride 22 and the molten zinc 24, the profile C2 shown in FIG. 2 is obtained such that the admittance output A output by the controller 70 exhibits a constant value. . This is because when the molten zinc chloride 22 and the molten zinc 24 are located between the probes 34 and 44, the resistance of the molten zinc 24 to be constant between the probes 34 and 44 due to the molten zinc 24. This is because the connected equivalent circuit is substantially formed.

  Here, when the lower ends of the probes 34 and 44 of the pair of electrodes 30 and 40 in a state where an alternating current is supplied from the AC power supply 50 reaches the interface 26 between the molten zinc chloride 22 and the molten zinc 24. The admittance output A output from the controller 70 is an admittance step shown in FIG. 2 in which the immersion length L changes suddenly from A1 to A2 around L1, and the profile C1 changes rapidly to the profile C2. Profile C3 is obtained. In such a case, the resistance between the probes 34 and 44 that exhibits a variable value due to the molten zinc chloride 22 and the electrostatic property that exhibits a variable value due to the molten zinc chloride 22 and the air above it. This is because the equivalent circuit in which the capacitance is connected in parallel is rapidly switched to the equivalent circuit in which a resistor having a constant value is connected between the probes 34 and 44 due to the molten zinc 24. Further, since the conductivity of the molten zinc 24 is relatively remarkably small, the resistance value resulting from the molten zinc 24 is relatively remarkably small, and the admittance that is the output voltage step of the profile C3 in the admittance output A is obtained. The step is relatively significantly increased.

  Therefore, in the configuration in which the positions of the probes 34 and 44, that is, the pair of electrodes 30 and 40 are fixed, the molten zinc chloride 22 is generated by the electrolysis of the molten zinc chloride 22 after the molten zinc chloride 22 is supplied to the storage tank 20. When the liquid level of the molten zinc chloride 22 is lowered, if the change curve of the admittance output A including the profiles C2 and C3 in addition to the profile C1 is measured in advance and made into a database, then the same Position of the probes 34, 44 and the interface between the molten zinc chloride 22 and the molten zinc 24 in a system comprising the probes 34, 44 having physical characteristics, the molten zinc chloride 22, the air above the molten zinc 24 and the molten zinc 24. When the relationship changes relatively, typically referring to the switching from profile C1 to admittance step profile C3, typically their position With reference to the position of the lower end of the fixed probe 34 and 44, it is possible to detect the position of the interface 26 between the molten zinc chloride 22 with the molten zinc 24. Further, the operator of the apparatus S1 stops the electrolysis according to the occurrence of the admittance step in the change curve of the admittance output A, that is, according to the lower limit position of the liquid level of the molten zinc chloride 22, or the chloride By additionally supplying the zinc 22 to the storage tank 20, an unnecessary decrease in the liquid level of the molten zinc chloride 22 and an unnecessary increase in the interface between the molten zinc chloride 22 and the molten zinc can be more reliably stopped.

At this time, the tip surfaces of the lower ends of the probes 34 and 44 are flat surfaces set so as to be parallel to the interface 26 between the molten zinc chloride 22 and the molten zinc 24, respectively. Child 3
The tip surfaces of the lower ends of 4, 4 and 44 instantaneously cross the interface 26 between the molten zinc chloride 22 and the molten zinc 24, so that the admittance step profile C3 becomes an upright mode in the admittance output A and exhibits a steep inclination. Therefore, the detection accuracy of the occurrence of the admittance step, that is, the position of the interface 26 between the molten zinc chloride 22 and the molten zinc 24 can be improved.

  The operation for stopping the unnecessary increase or decrease of the liquid level of the molten zinc chloride 22 and the unnecessary increase of the interface between the molten zinc chloride 22 and the molten zinc is performed by the operator of the apparatus S1 or the like. This may be performed manually or automatically by providing the controller 70 with a limiter function.

  According to the configuration of the present embodiment described above, the first liquid that is an electrolyte corrosive to the metal stored in the container and the metal stored below the first liquid in the container. A contact outer surface made of a material that is immersable in a conductive second liquid having corrosive properties with the same immersion length and that is resistant to corrosion with respect to the first liquid and the second liquid. An admittance value based on an alternating current flowing between the probes using a pair of electrodes each having a probe and being positioned in the first liquid while supplying an alternating current between the probes By detecting the position of the liquid surface of the first liquid according to the change in the upper liquid, the upper liquid is a liquid having a low conductivity such as an electrolyte, and the lower liquid has a higher specific gravity than the upper liquid and is unnecessary with the upper liquid. Two layers that are liquids that do not mix and are more conductive than the upper liquid In the storage tank or reaction tank in which the liquid is stored, even if the upper layer liquid and the lower layer liquid are both maintained at a high temperature and highly corrosive to metals, the liquid level of the upper layer liquid can be reduced with a simple configuration. This position can be detected with high accuracy, and if necessary, an unnecessary change in the liquid level of the upper liquid can be surely stopped at a desired timing.

  Further, when the tip of each probe of the pair of electrodes crosses the interface between the first liquid and the second liquid, a change in admittance output based on an alternating current flowing between the probes, in particular, admittance. Since the position of the interface can be detected according to the level difference of the output, the position of the liquid surface of the upper liquid layer can be detected with high accuracy with a simple configuration, and the interface between the upper liquid layer and the lower liquid layer can be detected. The position of the upper layer liquid can be detected with high accuracy, and if necessary, unnecessary changes in the liquid level of the upper liquid layer and unnecessary changes in the interface between the upper liquid layer and the lower liquid layer can be stopped more reliably. Can do.

  Further, each probe of the pair of electrodes is a cylindrical member having a flat surface which can be set parallel to the interface at the tip thereof, and in particular, instantaneously crosses the interface between the upper layer liquid and the lower layer liquid. And the position of the interface between the upper liquid and the lower liquid can be detected with higher accuracy.

  In addition, since the probe of each of the pair of electrodes is made of graphite, both the upper layer liquid and the lower layer liquid are maintained at a high temperature and corrode unnecessarily even if they are highly corrosive to metals. The position of the liquid surface of the upper layer liquid and the position of the interface between the upper layer liquid and the lower layer liquid can be detected with high accuracy with a simple configuration.

  In addition, each probe of the pair of electrodes communicates with the conductive member of the electrode, and the conductive member is covered with an insulating member that exhibits corrosion resistance to the first liquid and the second liquid. Therefore, even when a portion other than the probe of the electrode comes into contact with a droplet or gas such as an upper layer liquid, both the upper layer liquid and the lower layer liquid are maintained at a high temperature and are highly corrosive to the metal. However, it does not corrode unnecessarily, and with a simple configuration, the position of the liquid surface of the upper liquid and the position of the interface between the upper liquid and the lower liquid can be detected with high accuracy.

(Second Embodiment)
Next, a liquid level gauge according to the second embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 3 is a schematic cross-sectional view showing the configuration of the liquid level gauge in the present embodiment, and also shows a storage tank for storing liquid.

  In the present embodiment, the configuration of the pair of electrodes 130 and 140 of the liquid level gauge 100 is mainly different from that of the pair of electrodes 30 and 40 of the liquid level gauge 10 described in the first embodiment. Since this is a difference, the following description will be made by paying attention to such a difference, and the same components are denoted by the same reference numerals, and the description will be simplified or omitted as appropriate.

  As shown in FIG. 3, the level gauge 100 applied to the device S <b> 2 in the present embodiment includes a pair of electrodes 130 and 140, and the pair of electrodes 130 and 140 includes the sheath-type thermocouples 132 and 142. And insulating protective tubes 134 and 144 that surround and accommodate the sheathed thermocouples 132 and 142, respectively.

  Specifically, the sheath-type thermocouples 132 and 142 are thermocouples 132a and 142a composed of two types of metal members that are electrically connected to a temperature detector (not shown) and function as a probe. The sheaths 132b and 142b, which are made of metal such as stainless steel and accommodate the pairs 132a and 142a, and are filled between the thermocouples 132a and 142a and the sheaths 132b and 142b so as to be electrically insulating and thermally conductive. Certain fillers 132c, 142c are provided correspondingly. The sheaths 132b and 142b are electrically connected to the controller 70, respectively, and exhibit the same functions as the probes 34 and 44 in the first embodiment.

  The protective tubes 134 and 144 are sheathed thermocouples so that the sheathed thermocouples 132 and 142 are not undesirably corroded by the high-temperature molten zinc chloride 22 and the molten zinc 24, which are highly corrosive to metals. The pair 132, 142 is a closed-bottom cylindrical insulating member that is typically made of ceramic and covers the space with air interposed therebetween. Here, the outer surfaces of the protective tubes 134 and 144 constitute contact outer surfaces for the molten zinc chloride 22 and the molten zinc 24 with respect to the sheaths 132b and 142b. As described above, since the protective tubes 134 and 144 are closed bottom cylindrical members, the sheathed thermocouples 132 and 142 themselves may be either an exposed type or an embedded type.

  Here, in the pair of electrodes 130 and 140, the sheaths 132 b and 142 b that function as probes are provided between the insulating protective tubes 134 and 144 and the sheaths 132 b and 142 b and the protective tubes 134 and 144. Therefore, when the molten zinc chloride 22 and the air above and further the molten zinc 24 are located between the pair of electrodes 130 and 140, an electric circuit including these is provided. Thus, the circuit is evaluated as an equivalent circuit in which a capacitance and a resistance are connected between the sheaths 132b and 142b.

  More specifically, when the pair of electrodes 130 and 140 in a state where an alternating current is supplied from the alternating current power supply 50 penetrates relatively downward from the liquid surface of the molten zinc chloride 22, the immersion length of the sheaths 132b and 142b is increased. Corresponding to the increase in the length L, a profile similar to the profile C1 shown in FIG. 2 is obtained in which the admittance output A output from the controller 70 increases. On the other hand, the pair of electrodes 130 and 140 in a state in which an alternating current is supplied from the alternating current power supply 50 is positioned relatively lower, and the lower ends of the sheaths 132b and 142b are the molten zinc chloride 22 and the molten zinc 24. The admittance step profile C3 seen in the first embodiment does not appear clearly even when the molten zinc 24 has entered the interface 26 across the interface 26. From the profile similar to the profile C1, the sheath 132b 2, the profile C2 ′ shown in FIG. 2 is changed so as to be appropriately changed according to the length in the vertical direction of the region composed of the molten zinc chloride 22 between 142b.

  Therefore, in this configuration, while using a profile similar to the profile C1 as in the first embodiment, the positions of the lower ends of the sheaths 132b and 142b whose positions are fixed are typically visible for convenience. The position of the liquid level of the molten zinc chloride 22 can be detected using the position of the lower end of the protective tubes 134 and 144 as a reference. Further, although the detection accuracy is lowered for the configuration of the first embodiment, in principle, the change is made by utilizing the fact that the admittance output A changes from a profile similar to the profile C1 to the profile C2 ′. The position of the interface 26 between the molten zinc chloride 22 and the molten zinc 24 can be detected using the bending point or the like.

  In addition, since the pair of electrodes 130 and 140 incorporate the sheath type thermocouples 132 and 142, the liquid temperature of the molten zinc chloride 22 and the molten zinc 24 can be detected with high accuracy, and the electrode is inserted into the storage tank 20. The total number of electrodes can be reduced. In particular, when the storage tank 20 is an electrolytic reaction vessel, it is necessary to adopt a heat insulating structure and to close the open upper end portion with a lid to realize an airtight structure, so that electrodes and various pipes maintain airtightness. Although there is a tendency to be inserted through the through-hole with a configuration that requires a relatively large occupied area, a configuration that can reduce the total number of electrodes that are inserted into the storage tank 20 in this way is a complicated peripheral. This is significant from the viewpoint of reducing the total number of through-holes having a structure and simplifying the overall configuration of the device S2. If one sheath-type thermocouple has the same sheath length as the other sheath-type thermocouple and the lower end position of the thermocouple is relatively upward, the height from the bottom of the storage tank 20 is increased. It is also possible to measure the liquid temperature of the molten zinc chloride 22 and the molten zinc 24 at different locations.

  Note that only one of the pair of electrodes 130 and 140 having the sheath type thermocouples 132 and 142 in the present embodiment is applied, and the probes 34 and 44 in the first embodiment are applied to the other. One of the pair of electrodes 30 and 40 may be applied. In such a case, the position of the interface 26 between the molten zinc chloride 22 and the molten zinc 24 is compared to the case where all of the pair of electrodes 130 and 140 are used. Can be detected with high accuracy.

  According to the configuration of the present embodiment described above, each probe of the pair of electrodes constitutes a sheath type thermocouple, and the temperatures of the first liquid and the second liquid can be detected. In addition to detecting the position of the liquid surface, it can also realize an additional function of detecting the liquid temperature, reducing the total number of electrodes, etc. Temperature etc. can be detected with high accuracy.

  In addition, since the sheath type thermocouple is housed in a protective tube made of insulating ceramic, both the upper layer liquid and the lower layer liquid are maintained at a high temperature, and even if they are highly corrosive to metals, they are undesirably corroded. Therefore, the position of the upper liquid, the liquid temperature, and the like can be detected with high accuracy with a simple configuration.

  In the present invention, the type, arrangement, number, and the like of the members are not limited to the above-described embodiments, and the components depart from the gist of the invention, such as appropriately replacing the constituent elements with those having the same operational effects. Of course, it can be appropriately changed within the range not to be.

  As described above, in the present invention, the upper layer liquid is a liquid having low conductivity such as an electrolyte, the lower layer liquid has a higher specific gravity than the upper layer liquid, and is not unnecessarily mixed with the upper layer liquid, and is more conductive than the upper layer liquid. In a storage tank or reaction tank in which a two-layer structure liquid, which is a highly liquid, is stored, both the upper layer liquid and the lower layer liquid are kept at a high temperature and corrode unnecessarily even if they are highly corrosive to metals. Therefore, it is possible to provide a liquid level gauge that can detect the position of the liquid level of the upper layer liquid with high accuracy with a simple configuration. It is expected to be widely applicable to the target level gauge.

DESCRIPTION OF SYMBOLS 10 ... Liquid level meter 20 ... Storage tank 22 ... Upper layer liquid 24 ... Lower layer liquid 26 ... Interface 30, 40 ... Electrode 32, 42 ... Electrode part 32a, 42a ... Protective tube 32b, 42b ... Conductive member 34, 44 ... Probe 50 ... AC power supply 50a ... Feed line 50b ... Feed line 60 ... AC ammeter 70 ... Detection unit 70a ... Control unit 70b ... Detection unit 100 ... Level gauge 130, 140 ... Electrode 132, 142 ... sheath type thermocouple,
132a, 142a ... thermocouple,
132b, 142b ... sheath,
132c, 142c ... fillers,
134, 144 ... protective tube,

Claims (8)

A first liquid which is an electrolyte which is stored in a container and corrosive to metal; and a conductive liquid which is stored below the first liquid in the container and corrosive to metal. The first liquid and the second liquid can be immersed in the first liquid and the second liquid with the same immersion length so that they can traverse the interface formed with the second liquid. A pair of electrodes each having a probe made of a material whose outer surface in contact with the liquid exhibits corrosion resistance;
An alternating current power source capable of supplying an alternating current between the probes of each of the pair of electrodes;
When the tip of each probe of the pair of electrodes is located in the first liquid, the first responsive to a change in admittance output based on the alternating current flowing between the probes. A detection unit capable of detecting the position of the liquid level of the liquid,
A liquid level gauge.   The detector further includes the alternating current flowing between the probes when the tips of the probes of the pair of electrodes cross the interface between the first liquid and the second liquid. The liquid level gauge according to claim 1, wherein the position of the interface can be detected in accordance with a change in admittance output based on a current.   3. The liquid level gauge according to claim 1, wherein each of the probes of the pair of electrodes is a columnar member having a flat surface that can be set in parallel with the interface at a tip portion thereof.   The liquid level gauge according to claim 1, wherein each of the probes of the pair of electrodes is made of graphite.   Each of the probes of the pair of electrodes communicates with the conductive member of the first pair of electrodes, and the conductive member is resistant to corrosion with respect to the first liquid and the second liquid. The liquid level gauge according to claim 1, wherein the liquid level gauge is covered with an insulating member exhibiting properties.   2. The probe according to claim 1, wherein each of the probes of the pair of electrodes constitutes a sheath-type thermocouple, and the detection unit is further capable of detecting temperatures of the first liquid and the second liquid. Liquid level gauge as described.   The liquid level meter according to claim 6, wherein the sheath type thermocouple is accommodated in a protective tube made of an insulating ceramic.   The liquid level gauge according to any one of claims 1 to 7, wherein the first liquid is a molten salt containing molten zinc chloride and the second liquid is a molten metal containing molten zinc.