JP6992548B2 - Oxygen concentration measurement probe and oxygen concentration detector - Google Patents

Description

The present invention relates to an oxygen concentration measuring probe and an oxygen concentration detector.

As an oxygen concentration measuring probe, for example, there is one described in Patent Document 1. This oxygen concentration measuring probe immerses the immersed portion of the solid electrolyte tube containing the solid oxygen reference electrode in a molten metal, for example, molten copper, and measures the potential difference generated between the internal electrode and the external electrode. The oxygen concentration in the molten metal was measured.

In the oxygen concentration measuring probe, the solid oxygen reference electrode is made of a metal / metal oxide provided inside the solid electrolyte tube, and an internal electrode is embedded in the solid oxygen reference electrode.

Japanese Unexamined Patent Publication No. 57-90151

When measuring the oxygen concentration in the molten metal, this oxygen concentration measuring probe is used by immersing the tip of the solid electrolyte tube (hereinafter, also referred to as "immersion portion") in the molten metal, and thus is used on the surface thereof. There is a risk that slag or the like present in the molten metal will adhere in the form of an oxide. In the oxygen concentration measuring probe, if an oxide made of slag or the like adheres to the surface of the immersed portion of the solid electrolyte tube, the oxygen concentration in the molten metal is measured high. Therefore, the oxygen concentration in the molten metal cannot be measured accurately.

Therefore, an object of the present invention is to provide an oxygen concentration measuring probe capable of accurately measuring the oxygen concentration in the molten metal and an oxygen concentration detector provided with the oxygen concentration measuring probe.

The present invention provides the oxygen concentration measuring probes [1] to [3] and the oxygen concentration detector of [4] in order to achieve the above object.

[1] The internal electrode and the external electrode, the solid electrolyte tube arranged between the internal electrode and the external electrode and having a dipping portion immersed in the molten metal, and the solid electrolyte tube arranged on the outer surface of the external electrode are not used. An oxygen concentration measuring probe comprising a tubular member having a first end into which the active gas flows in and a second end in which the inflowing inert gas is discharged.
[2] The oxygen concentration measuring probe according to the above [1], wherein the second end portion of the tubular member is located in the vicinity of the dipping portion of the solid electrolyte tube.
[3] The oxygen concentration measuring probe according to the above [1], wherein the inert gas is nitrogen or argon.
[4] An oxygen concentration detector comprising the oxygen concentration measuring probe according to any one of the above [1] to [3].

According to the present invention, it is possible to provide an oxygen concentration measuring probe capable of accurately measuring the oxygen concentration in a molten metal and an oxygen concentration detector provided with the oxygen concentration measuring probe.

(A) is a schematic cross-sectional view showing an example of an oxygen concentration detector provided with an oxygen concentration measuring probe according to an embodiment of the present invention, and (b) is an arrangement of tubular members for inflowing and discharging inert gas. It is explanatory drawing which shows the position. It is explanatory drawing which shows the oxygen concentration detector provided with the oxygen measurement probe which concerns on the modification of embodiment of this invention.

[Oxygen concentration measurement probe]
The oxygen concentration detector provided with the oxygen concentration measuring probe according to the embodiment of the present invention will be described in detail below with reference to the drawings.
FIG. 1A is a schematic cross-sectional view showing an example of an oxygen concentration detector provided with an oxygen concentration measuring probe according to an embodiment of the present invention.

The oxygen concentration measuring probe 10 according to the embodiment of the present invention is arranged inside the external electrode 7, the solid electrolyte tube 4 having the immersion portion 4a, and the tube of the solid electrolyte tube 4. A tubular member 8 is provided, which is arranged in contact with the outer surface of the external electrode 7 and the internal electrode 1 and the reference electrode 3, and an inert gas flows into the inside.

The oxygen concentration measuring probe 10 shown in FIG. 1A includes a sealing material 3A for sealing the reference electrode 3 in the tube of the solid electrolyte tube 4, and a reinforcing tube 5 provided on the outside of the solid electrolyte tube 4. Further, a fireproof material 6 provided on the outside of the reinforcing pipe 5 is further provided, and if necessary, the internal electrode 1 is coated with a metal coating. The total length of the probe 10 is, for example, about 500 mm to 800 mm.

(Internal electrode 1)
The material of the internal electrode 1 is not particularly limited as long as it has a melting point higher than that of the molten metal to be measured and can be used as an oxygen concentration measuring probe. For example, stainless steel (SUS), nickel (Ni), and copper (Cu). ), Platinum (Pt). In particular, when stainless steel (SUS) is used for the external electrode 7, it is preferable to use the same stainless steel (SUS) as the internal electrode 1 because the thermoelectromotive force due to the use of dissimilar metals is not generated. When the oxygen concentration measuring probe 10 is used, the surface of the internal electrode 1 is heated to about 1000 ° C. Even if the platinum (Pt) electrode is heated to about 1000 ° C., an oxide film is unlikely to be formed on the surface of the platinum (Pt) electrode.

The shape of the internal electrode 1 is preferably rod-shaped (linear) as shown in FIG. 1A, but is not limited to this. For example, the shapes described in FIG. 1 (shape in which the tip portion is thick) and FIG. 3 (shape in which the tip portion is spherical) of Patent Document 1 described above can be adopted.

(Metal coating 2)
A metal coating 2 may be provided on the internal electrode 1 as needed. The metal coating 2 is made of, for example, a noble metal composed of platinum (Pt), rhodium (Rh), palladium (Pd), iridium (Ir), or an alloy of the noble metal. When these metals are used, when the surface of the internal electrode 1 is heated to about 1000 ° C. when the oxygen concentration measuring probe 10 is used, an oxide film is not formed on the surface of the metal coating 2, so that an oxide film is formed. There is no problem that it peels off and a gap is created. The film thickness of the metal coating 2 is not particularly limited, but is preferably 1 μm or more and 2000 μm or less.

The film formation range of the metal coating 2 is preferably the entire portion where the internal electrode 1 can come into direct contact with the reference electrode 3, but it may be a part thereof. In the embodiment shown in FIG. 1 (a), the entire portion that can come into direct contact with the reference pole 3 is coated, and the metal coating 2 is provided up to the upper portion where the reference pole 3 does not exist.

Various methods can be used for forming the metal coating 2. For example, it can be formed by metal plating.

In addition to the case where "formed on the internal electrode 1" is formed on the surface of the internal electrode 1 as shown in FIG. 1 (a), for example, the above-mentioned Patent Document 1 ( The case where the sleeve such as Fe or stainless steel shown in the right column of page 3, FIG. 4) is formed on the sleeve in the embodiment provided at the tip of the internal electrode 1 is also included.

(Reference pole 3)
As the reference electrode 3, for example, a solid oxygen reference electrode using a metal / metal oxide such as Fe / FeO powder, Ni / NiO powder, Cr / CrO powder, or an air reference electrode using a gas such as air ( It is composed of a gas reference electrode) and has the effect of keeping the oxygen concentration inside the solid electrolyte tube 4 constant. Note that FIGS. 1 and 2 show a case where a solid oxygen reference electrode is used as the reference electrode 3.

The reference electrode 3 is enclosed so as to fill the inside of the solid electrolyte tube 4, and the end portion of the internal electrode 1 is embedded in the central portion thereof. The internal electrode 1 does not reach the tip portion of the solid electrolyte tube 4 (the region shown by the length a in FIG. 1A) which is in direct contact with the molten metal, and the reference electrode 3 is filled. The length a is preferably, for example, about 3 mm to 5 mm. On the other hand, the length (length b in FIG. 1A) of the remaining portion of the solid electrolyte tube 4 (the portion covered with the reinforcing tube 5 or the like and not in direct contact with the molten metal) is preferably about 50 mm to 70 mm, for example.

Although not shown, when an air reference electrode (gas reference electrode) is used as the reference electrode 3, a gas such as air is introduced from the outside of the solid electrolyte tube 4 into the inside of the solid electrolyte tube 4. The pipe is provided inside the solid electrolyte pipe 4. At this time, the inside of the solid electrolyte pipe 4 is filled with a gas such as air introduced through the pipe, and the oxygen concentration is kept constant. When the air reference electrode is used as the reference electrode 3, there is an advantage that the measurement can be performed for a long time (several tens of hours to several hundred hours) as compared with the solid oxygen reference electrode.

(Solid electrolyte tube 4)
The solid electrolyte tube 4 has an immersion portion 4a which is the tip of the solid electrolyte tube 4, and as a material thereof, has the property of a solid electrolyte (ion conductive solid) and selectively oxygen ions (O ^2- ), For example, stabilized zirconia (ZrO ₂ + MgO) can be mentioned as a suitable one.

(Reinforcing pipe 5)
The reinforcing pipe 5 is for preventing the solid electrolyte pipe 4 from cracking, and for example, an alumina pipe is suitable.

(Refractory 6)
As the material of the refractory material 6, refractory cement is suitable, and for example, magnesium-based cement is suitable.

(External electrode 7)
The material of the external electrode 7 may be any metal that does not melt when the oxygen concentration measuring probe 10 is immersed in the molten metal, and for example, stainless steel (SUS) is suitable. It is optimal to use stainless steel (SUS) for both the internal electrode 1 and the external electrode 7, because in this case, a thermoelectromotive force that causes a measurement error does not occur between the internal electrode 1 and the external electrode 7. There is an advantage that it is not necessary to correct the measurement error.

(Tubular member 8)
The material of the tubular member 8 may be any metal that does not melt when the oxygen concentration measuring probe 10 is immersed in the molten metal, and is made of, for example, stainless steel (SUS) or ceramics. The inert gas flows into the tubular member 8. As the inert gas, for example, a gas composed of nitrogen (N ₂ ) or argon (Ar) is suitable.

The tubular member 8 has a first end into which the inert gas flows in and a second end in which the inert gas flowing in from the first end is discharged. The tubular member 8 is arranged upstream of the position where the solid electrolyte tube 4 is arranged with respect to the flow of the molten metal so as to be along the oxygen concentration measuring probe 10. The tubular member 8 is fixed and arranged so as to be in contact with the outer surface of the external electrode 7 by a fixing member made of a material such as stainless steel. The inert gas composed of nitrogen (N ₂ ), argon (Ar), etc. flowing into the inside of the tubular member 8 arranged on the upstream side of the solid electrolyte pipe 4 continuously or intermittently is the immersion portion 4a of the solid electrolyte pipe 4. It flows out along the flow of the molten metal from the second end of the tubular member 8 located in the vicinity of. The flowing inert gas hits the surface of the immersion portion 4a immersed in the molten metal of the solid electrolyte tube 4. The fact that the second end of the tubular member 8 is located near the immersion portion 4a means that the second end of the tubular member 8 arranged on the outer surface of the external electrode 7 is the position of the tip of the external electrode 7. This includes the case where the inert gas emitted from the second end portion is located at the same level or below the same position so as to be able to hit the surface of the immersion portion 4a. As a result, the surface of the immersed portion 4a immersed in the molten metal of the solid electrolyte tube 4 is less likely to form an oxide made of slag or the like, or the oxide already formed can be removed. As a result, it is possible to prevent the oxide made of slag or the like from adhering to the surface of the solid electrolyte tube 4 and measuring the oxygen concentration in the molten metal to be high, so that the oxygen concentration in the molten metal can be accurately measured. Can be measured.

Although the S region in FIG. 1 is air, it may be an embodiment in which nitrogen is flowed in order to extend the life of the reference electrode 3.

The oxygen concentration measuring probe 10 according to the embodiment of the present invention is suitable for measuring the oxygen concentration in various molten metals (for example, molten copper).

FIG. 1B shows the direction 8a of the flow of the inert gas released by the tubular member 8 in the oxygen concentration measuring probe 10. The direction 8a of the flow of the inert gas is directed to the center O where the immersion portion 4a of the solid electrolyte-to-solid electrolyte 4 is located.

In FIGS. 1A and 1B, the tubular member 8 provided along the external electrode 7 is connected to the connecting tube 16 via the connecting portion 12 connected to the first end portion. The connecting tube 16 supplies the inert gas from the inert gas source 14 to the first end of the tubular member 8 by the pump 13.

The pump 13 is controlled by the control unit 15, and the supply amount, continuous supply, intermittent supply, and the like of the inert gas to the tubular member 8 are controlled. The control unit 15 inputs a potential difference signal output by the potentiometer 11 to monitor the oxygen concentration in the molten metal, records the result, and controls the pump 13 based on the result.

FIG. 2 shows a modified example in which the oxygen concentration measuring probe 10 is provided with three tubular members 81, 82, and 83. In this modification, the shape of the inert gas discharge end of the tubular member 8 may be devised so that the direction 8a of the flow of the inert gas is directed toward the center.

[Oxygen concentration detector]
The oxygen concentration detector according to the embodiment of the present invention includes the oxygen concentration measuring probe 10 according to the embodiment of the present invention.

Lead wires are connected to the internal electrodes 1 and the external electrodes 7, and each lead wire is connected to the above-mentioned potentiometer 11. An electromotive force determined by the oxygen concentration ratio is generated between the inner and outer electrodes, and by measuring the voltage generated between the electrodes with a potentiometer 11, the oxygen concentration can be obtained using a well-known conversion formula.

The present invention is not limited to the above embodiments and examples, and various modifications can be made.

1 ... Internal electrode 2 ... Metal coating 3 ... Reference electrode 3A ... Encapsulant 4 ... Solid electrolyte tube 5 ... Reinforcing tube 6 ... Fireproof material 7 ... External electrode 8,81,82,83 ... Tubular member 10 ... Oxygen concentration measuring probe 11 ... Potential difference meter 12 ... Connection unit 13 ... Pump 14 ... Inert gas source 15 ... Control unit 16 ... Connection tube

Claims (3)

The internal electrode and the external electrode, the solid electrolyte tube arranged between the internal electrode and the external electrode and having a dipping portion immersed in the molten metal, and the solid electrolyte tube arranged in contact with the outer surface of the external electrode are not arranged. It has a first end into which the active gas flows in and a second end in which the inflowing inert gas is discharged, the second end being at or below the position of the tip of the external electrode. An oxygen concentration measuring probe comprising a tubular member arranged at a position where the released inert gas can be applied to the surface of the immersion portion along the flow of the molten metal . The oxygen concentration measuring probe according to claim 1, wherein the inert gas is nitrogen or argon. An oxygen concentration detector comprising the oxygen concentration measuring probe according to claim 1 or 2 .

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