JPH0619088Y2 - Continuous oxygen measuring device in high temperature atmosphere - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an apparatus for continuously measuring oxygen concentration in a high temperature atmosphere.

[Conventional technology]

In order to continuously measure the oxygen in the gas, a method is generally known in which the gas is sucked and collected by a suction pipe and the oxygen concentration is measured by a sensor provided outside.

This is to install an electrode on the inner and outer walls of a solid electrolyte, to provide a standard electrode in the solid electrolyte, to cause an oxygen concentration difference between the inner and outer walls of the solid electrolyte, and to measure the oxygen concentration from the potential difference generated thereby. .

Usually, in the case of gas, since heat transfer to the solid electrolyte is small, it is common to heat and raise the temperature of the solid electrolyte by a heating means such as a heater.

[Problems to be solved by the device]

In a high-temperature furnace, such as a tundish, when measuring the oxygen concentration in a high-temperature atmosphere (about 600 to 1,400 ° C.) in the space formed between the tundish container and the molten steel surface, the sensor part is set to the atmosphere. When exposed and measured inside, there were the following problems.

Since the convective heat transfer of gas to the sensor part is small, the true operating temperature cannot be grasped and a measurement error occurs, making it difficult to measure the oxygen concentration accurately.

(Approximately 1,550 ° C), the temperature of the surrounding objects such as the furnace wall is different from the ambient temperature, but since the radiant heat from these surrounding objects reaches the sensor part, the accurate gas temperature cannot be grasped and the measurement error occurs and the accurate oxygen It becomes difficult to measure the concentration.

[Means for Solving the Problems]

The present inventor has found that the above problem can be solved by positively sucking gas in a high temperature atmosphere and passing the gas through the sensor unit. Further, it has been found that the above problems can be solved by surrounding the sensor unit with a radiation shield so that the sensor unit is not affected by the radiant heat from surrounding objects.

By the way, when configuring the suction structure for sucking the gas in the high temperature atmosphere as described above in the oxygen measuring device,
It is inevitable that the structure will be complicated, and it is expected that assembly of the component parts will be difficult. In this regard, the present inventor has found that the assembly of the device can be facilitated by unitizing the component parts of the device and configuring the sensor unit and the outer shell unit.

Further, when the gas in the high temperature atmosphere is continuously sucked, there is a concern that the temperature of the device itself rises, which may adversely affect the distortion of each part and the electrode wire. In this regard, the inventor
It was found that by cooling the unitized outer shell unit, the device can be kept in a normal state even during long-term operation.

Therefore, the present invention is configured as a means for solving the above-mentioned problems, which is composed of a sensor unit and an outer shell unit which inserts and protects the sensor unit: the sensor unit includes an external electrode and an internal electrode. A sensor part having a solid electrolyte interposed therebetween, a protective tube extending from the sensor part for accommodating and protecting the electrode wire, and a head part including a terminal part provided at the tail end of the protective tube are provided. Reality:
The outer shell unit includes a fixing portion for fixing the head portion of the sensor unit, a tubular main body portion for housing and protecting the protection tube, and radiation surrounding the tip of the sensor portion inserted from the tubular main body portion. And a shield;
A gas suction passage that passes through the sensor portion from the opening of the radiation shield and is communicated with the suction mechanism via the tubular main body portion,
A refrigerant passage for cooling the cylindrical main body portion, which is isolated from the gas suction passage, is formed.

〔Example〕

A continuous oxygen measuring apparatus in a high temperature atmosphere according to the present invention will be described below with reference to an embodiment shown in the drawings.

In FIG. 1, the continuous oxygen measuring apparatus in a high temperature atmosphere comprises a sensor unit A, an outer shell unit B for inserting and protecting the sensor unit A, and a suction mechanism unit C connected to the outer shell unit B.

(Structure of Sensor Unit A) As shown in FIGS. 1 and 2, the sensor unit A has a sensor portion 1 at its tip, and a protective tube 2 extending from the sensor portion 1 for accommodating and protecting the electrode wire. And a head portion 4 including a terminal portion 3 is provided at the tail end portion of the protective tube 2.

The sensor unit 1 is made of ZrO ₂ stabilized with MgO or the like.
End closed tubular solid electrolyte tube 5 made of solid electrolyte such as
Have. A mixture of a metal and an oxide of the metal, for example, a reference material of Mo—MoO ₂ is enclosed as a standard electrode (not shown) inside the solid electrolyte tube 5 (as known as a standard electrode). You may use the air electrode). An internal electrode 6 such as a platinum wire is in contact with the solid electrolyte tube 5, and the internal electrode 6 is extendedly connected to the terminal portion 3 through an alumina insulating tube 7 housed in the protective tube 2. An external electrode 8 such as a platinum wire is electrically contacted with the outer wall of the solid electrolyte tube 5, and the external electrode 8 is also extended to the terminal portion 3 through an alumina insulating tube 9 housed in the protective tube 2. It is connected. In the illustrated embodiment, one electrode (platinum wire) of the R thermocouple wire is extended from the hot junction portion and wound around and attached to the outer wall of the solid electrolyte tube 5. In this case, the temperature of the solid electrolyte tube 5 is also measured.

The protection tube 2 is made of a highly airtight porcelain protection tube whose both ends are open. The protection tube 2 is inserted through the pair of alumina insulation tubes 7 and 9 and has a solid electrolyte tube 5 that constitutes the sensor section 1 at the tip. Is held in a protruding shape. Preferably, the tip ends of the pair of alumina insulating tubes 7 and 9 and the solid electrolyte tube 5 are fixed in the tip portion of the protective tube 2 by a sealing plug 10 and a refractory cement 11. The high airtight porcelain protective tube means, for example, an internal electrode wire 6 and an external electrode wire 8 (in the illustrated embodiment, in a high temperature state (about 1200 to 1400 ° C.) like an alumina protective tube. , Thermocouple wire) is stable in a high temperature state where it does not generate metal vapor itself that promotes deterioration of the thermocouple wire. At a temperature of about 1,200 ° C. or less, stability can be obtained even if a stainless steel tube is used as the protective tube 2.

The tail end of the protective tube 2 is provided with a flanged sleeve 12 of the head 4.
Inserted and fixed in.

The head portion 4 is provided with a terminal box 13 that houses and holds the terminal portion 3, and the terminal box 13 is fixed to the tail portion of the flanged sleeve 12. Between the terminal box 13 and the flange 12a of the sleeve 12, a fixing ring 1 having an internal screw 14a is provided.
4 is inserted outside. The fixing ring 14 is used for fixing the sensor unit A to the outer shell unit B as described later.

(Structure of Outer Shell Unit) As shown in FIG. 1, the outer shell unit B includes a fixing portion 15 for fixing the head portion 4 of the sensor unit A and a cylindrical main body portion 16 for accommodating and protecting the protective tube 2. And the tubular body 1
And a radiation shield 17 surrounding the tip of the sensor unit 1 inserted from 6.

The fixing portion 15 is composed of a cylindrical body fixed to the tail end of the tubular main body portion 16, and the inner thread of the fixing ring 14 provided on the head 4 of the sensor unit A is provided on the outer periphery of the tail end of the fixing portion 15. 14
An external screw 15a for detachably attaching a is formed.

The tubular main body portion 16 constitutes a triple pipe of an inner pipe 18, a middle pipe 19, and an outer pipe 20 each formed of a stainless steel pipe, and a feed passage 21 is formed between the inner pipe 18 and the middle pipe 19. Tube 19
A return path 22 is formed between the outer tube 20 and the outer tube 20,
The refrigerant passage 23 is constituted by. That is, while the inner pipe 18 and the outer pipe 20 are connected in a closed shape at the tips, the middle pipe 19 has the tip as a free end between the inner and outer pipes 18 and 20, and the feed passage 21 to the return passage 22. Return road 24 leading to
Therefore, the refrigerant pressure-fed in the feed path 21 is pressure-fed to the return path 22 via the return path 24. An inlet port 25 communicating with the feed passage 21 is provided in the middle pipe 19 in the vicinity of the tail end of the tubular main body 16.
Also, the outlet port 2 communicating with the return path 22.
6 is provided on the outer tube 20. A bellows space 27 for relaxing the difference in thermal expansion and compensating the pressure by bulging the outer pipe 20 is formed in the return path 22 near the outlet port 26.

The radiation shield 17 is, as shown in FIGS. 1 and 3, an inner tube 28 made of a refractory material,
It has a triple structure of the middle tube 29 and the outer tube 30. As the refractory material, for example, high-purity alumina (Al ₂
O ₃ 99.5% or more), silicon nitride, silicon carbide, or the like is used. Inner tube 28 and middle tube 2
9 has a tail end held by a collar 32, and both tubes 2
Between 8 and 29, a suction auxiliary passage 31 having both ends opened is formed. A guide tube 33 made of stainless steel is fitted around the tail end of the middle tube 29. By fixing the end portion of the outer tube 30 to the flange 33a of the guide tube 33, the outer tube 30 is separated from the flange 33a. In the front area, they are positioned concentrically on the outer periphery of the middle tube 29 with a space therebetween. As a result, the radiation shield 17
Is assembled by inserting the guide cylinder 33 into the open end of the cylindrical main body 16 and adhering it through refractory cement, and constitutes a radiation shield unit D.

Thus, with the sensor unit A inserted in the outer shell unit B, the sensor unit 1 inserted from the tip of the tubular main body unit 16 is surrounded by the radiation shield 17. In this state, the gas suction passage 34 is formed between the outer shell unit B and the sensor unit A. That is, the gas suction path 3
4 is an opening 35 of the inner tube 28 of the radiation shield 17.
From the sensor unit 1 to the inside of the fixing unit 15 via the inner tube 18 of the cylindrical main body unit 16 and communicates with the suction port 36 provided in the fixing unit 15. Radiation shield 1
A filter 37 made of stainless steel mesh or the like is attached to the tip of the filter 7 for dust removal. In the case of the illustrated example, the peripheral edge of the filter 37 is inserted into the space between the inner tube 29 and the outer tube 30. ing.

(Structure of Suction Mechanism Unit) As shown in FIG. 1, the suction mechanism unit C includes a venturi unit 38 connected to the suction port 36 and an ejector unit 39 connected to the venturi unit 38.

The venturi unit 38 constitutes a venturi pipe 41 having a differential pressure tap 40 for controlling the gas flow rate from the suction port 36 to the ejector unit 39, and one end of the venturi pipe 41 is connected to the suction port 36 of the outer shell unit B by a joint 42. The other end is connected to the inlet port 43 of the ejector unit 39 by a joint 44.

The ejector unit 39 has the inlet port 43.
The ejector nozzle 45 at one end in the direction intersecting with
And an outlet port 46 is arranged at the other end.

(Other Illustrated Configurations) As shown in FIG. 1, the outer shell unit B has a cylindrical main body 1
6. Attach the mounting flange 47a to the middle portion in the longitudinal direction of 6,
The outer tube 20 is covered with a heat insulating tube 47b between the mounting flange 47a and the tip of the tubular main body 16. The heat insulating tube 47b is formed of, for example, a ceramic fiber made of alumina / silica (trade name: Kaowool).

A cover member 48 is attached to the tail end side of the outer shell unit B. The cover member 48 surrounds the outer periphery of the outer shell unit B in a state where the inlet port 43 and the outlet port 26 of the refrigerant passage 23 and the suction port 36 of the gas suction passage 34 are projected from the opening on one side. An end portion of the cover member 48 is supported by a ring body 49 fixed to the outer tube 20.

[Operation of Example]

The high-temperature atmosphere continuous oxygen measuring device based on the above embodiment,
For example, as shown in FIG. 4, it is used to measure oxygen in the high temperature atmosphere in the tundish 50 of the continuous casting apparatus.

In the device in which the sensor unit A, the outer shell unit B and the suction mechanism unit C are assembled, the tip of the outer shell unit B is inserted into the lid 51 of the tundish 50, and the tundish 50 is exposed to a high temperature atmosphere. It is inserted and fixed by fixing the attachment flange 47a to the lid 51. Although illustration is omitted, the molten metal 52 has a burnt surface or the like placed on the molten metal surface to prevent oxidation of the molten steel surface and keep it warm. The space 53 above the molten metal surface of the tundish 50 forms a high-temperature atmosphere sealed by the lid 51, and is made an inert atmosphere by supplying an inert gas such as nitrogen or argon to prevent the molten steel from being oxidized. There is.

The outlet port 26 of the refrigerant passage 23 in the outer shell unit B and the ejector nozzle 45 of the ejector unit 39 in the suction mechanism unit C are connected by a communication pipe 54. Further, the inlet port 2 of the refrigerant passage 23
Reference numeral 5 is connected to a discharge port of an air supply source 55 such as a compressor or an air pump. The electrode wire of the sensor unit A passes through the terminal portion 3 and the electromotive force indicator 56.
Have been contacted.

When cooling air such as nitrogen is pressure-fed from the air supply source 55, the air pressure-fed from the inlet port 25 of the refrigerant path 23 to the feed path 21 is returned from the feed path 21 to the return path 2.
4 through return route 22 to outlet port 26
The ejector noise 45 of the suction mechanism unit C ejects through the connecting path 54. The jetted air is discharged from the outlet port 46 of the ejector unit 39, but a circulation path 57 may be provided to return it to the air supply source 55 again.

When air is ejected from the ejector nozzle 45, the suction mechanism unit C makes the venturi unit 38 side a negative pressure with respect to the ejector unit 39, whereby the opening 3 of the radiation shield 17 is passed through the gas suction passage 34.
From 5, the atmospheric gas in the tundish space 53 is sucked. The gas sucked from the opening 35 passes through the sensor unit 1, is guided to the gas suction passage 34, and is discharged from the outlet port 46 of the suction mechanism unit C together with air. At the same time, the gas is also sucked from the suction auxiliary passage 31 of the radiation shield 17 to increase the suction gas flow rate. At this time, since the filter 37 is provided in the opening 35 and the suction auxiliary passage 31, dust such as burning will not enter.

Therefore, since the atmospheric gas in the tundish space 53 continuously passes through the sensor unit 1 at high speed while being sucked, the gas in the atmosphere largely convects to come into contact with the sensor unit 1 and grasp the true gas temperature. This enables accurate oxygen concentration measurement.

Further, when the sensor is exposed to a high temperature atmosphere as in the conventional case, the radiant heat from the molten steel surface or the furnace wall is generated as a gas temperature measurement error, which results in an oxygen concentration measurement error. On the other hand, as described above, the sensor unit 1
Is surrounded by the radiation shield 17, it is possible to perform accurate oxygen concentration measurement without being affected by radiant heat.

Further, in the above-described embodiment, when the air pressure-fed from the air supply source 55 passes through the refrigerant passage 23, the tubular main body portion 16 of the outer shell unit B is suitably cooled, so that the mounting points of the respective units are distorted. It is possible to continuously operate for a long period of time without causing any deterioration or deterioration of the electrode wire of the sensor unit A.

According to the result of the experiment by the present inventor, when a conventional solid electrolyte cell exposure type sensor is used to measure the oxygen amount (about 21%) in the air at 1,200 ° C., the gas temperature transmitted to the sensor unit is In the case of ± 30 ° C, the electromotive force value causes an error of ± 12 mV, and a measurement error of ± 30% in oxygen amount occurs, whereas when the device of the present invention is used, the measurement error should be almost seen. I couldn't.

The present invention has been described above based on the illustrated embodiments, but the present invention can make various design changes and additions of configurations based on the scope of claims for utility model registration. For example, in the above embodiment, by connecting the outlet port 26 of the refrigerant passage 23 to the ejector nozzle 45, the refrigerant passage 23
The gas suction passage 34 and the gas suction passage 34 are configured as one system to be economically advantageous, but the refrigerant passage 23 and the gas suction passage 34 may be configured as separate independent systems. That is, while an air supply source 55 for pumping air such as nitrogen is provided in the refrigerant passage 23, a separate and independent air supply source is connected to the ejector nozzle 45 for operating the gas suction passage 34,
Alternatively, an independent system can be freely configured by connecting a suction pump or the like to the suction port 36. In this case, the refrigerant passage 23 can form an independent air cooling or water cooling system by connecting the inlet port 25 and the outlet port 26 to the circulator.

Further, in the above embodiment, the outer shell unit B and the suction mechanism unit C are shown as independent units, but the suction mechanism unit C may be inseparably incorporated in the outer shell unit B in advance.

Furthermore, although the above describes the tundish, it can be widely used for measuring the oxygen concentration in the high temperature atmosphere of a high temperature furnace such as a converter, a coke oven, a heating furnace and the like.

[Effect of device]

As a result of being configured as described above, the present invention has the following technical effects.

(1) The gas suction path positively sucks the gas in the high temperature atmosphere to be measured and allows it to continuously pass through the sensor section, so it is easy to move the convection heat of the gas in the high temperature atmosphere to the sensor section. The true temperature of the gas is grasped and the oxygen concentration can be accurately measured.

(2) Since the radiation shield shields the sensor from radiant heat from surrounding objects in a high temperature atmosphere,
It is possible to accurately measure the oxygen concentration without causing a temperature measurement error due to the influence of the radiant heat.

(3) Outer shell unit By constructing the refrigerant passage for cooling the cylindrical main body, it is possible to sufficiently withstand long-term measurement.

(4) While having a complicated structure including a gas suction passage and a refrigerant passage, all of these complicated structures are provided in the outer shell unit, while a sensor unit is configured separately from the outer shell unit. Since the device is assembled by removably inserting it into the outer shell unit and storing it, assembly work and disassembly and cleaning work are easy and easy, and only the sensor unit must be replaced. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention partially broken away, FIG. 2 is an enlarged sectional view showing a state where a sensor unit of the embodiment is taken out, and a part thereof is omitted, and FIG. FIG. 3 is an enlarged sectional view taken along the line III-III in FIG. 1, and FIG. 4 is an explanatory view showing a usage example of the apparatus according to the embodiment. A ... Sensor unit, B ... Outer shell unit, C ...
Suction mechanism unit, D ... Radiation shield unit, 1 ...
… Sensor, 2 …… Protective tube, 3 …… Terminal, 4
...... Head, 5 …… Solid electrolyte tube, 6,8 …… Electrode, 14
…… Fixing ring, 15 …… Fixing part, 16 …… Cylindrical body part, 1
7 ... Radiation shield, 23 ... Refrigerant passage, 31 ... Suction auxiliary passage, 34 ... Gas suction passage, 35 ... Opening portion, 37 ...
Filter, 38 ... Venturi unit, 39 ... Ejector unit.

Claims (1)

[Scope of utility model registration request] 1. A sensor unit and an outer shell unit for inserting and protecting the sensor unit: The sensor unit includes a sensor unit (1) in which a solid electrolyte is interposed between an external electrode and an internal electrode, and The protective tube (2) extending from the sensor section to store and protect the electrode wire and the head section (4) including the terminal section (3) provided at the tail end of the protective tube are provided: The shell unit includes a fixing portion (15) for fixing the head of the sensor unit, a tubular main body (16) for housing and protecting the protective tube, and a tip of the sensor portion inserted from the tubular main body. A radiation shield (17) surrounding the gas shield passage (17); and the outer shell unit further includes a gas suction path (34) passing through the sensor portion from the opening of the radiation shield and communicating with the suction mechanism via the tubular main body portion. ), And a refrigerant passage that is isolated from the gas suction passage and cools the cylindrical main body ( 23) and a continuous oxygen measuring device in a high-temperature atmosphere.