JPH081494Y2 - Device for measuring oxygen activity in slag - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring oxygen activity in slag, which is capable of highly accurately measuring oxygen activity in hot metal slag and molten steel slag produced in the iron making process, and more specifically, the device. The present invention relates to a device for measuring oxygen activity in slag, which can prolong life and reduce device cost.

[0002]

2. Description of the Related Art Conventionally, for measuring the oxygen activity in molten pig iron slag or molten steel slag, a platinum reference electrode is wound in close contact with the outer surface of a one-end closed tube type solid electrolyte containing a standard electrode material or A method is known in which an oxygen concentration battery constituted by being sheathed is embedded and fixed at the probe tip, and this probe is directly positioned in the molten slag layer existing in the molten steel upper layer in the experimental furnace or the actual furnace. Since it is difficult to detect the interface position between the slag and the molten steel by the method, it is difficult to position the oxygen concentration battery, which is the detection part, reliably in the slag, and it is exposed to high temperature for a long time. There is a problem that the probe diameter becomes large in order to protect the detection part. And above all, if you try to apply such a measuring method to an actual furnace, it is necessary to temporarily stop the progress of the iron making process, but as a matter of fact it is not possible to stop the iron making process for a long time, for this reason, The above method is extremely difficult to use in an actual furnace.

In order to solve such a problem, the present inventor has proposed Japanese Patent Application No. 1-271033 (Japanese Unexamined Patent Publication No. 3-1
No. 31748) has already been filed. As shown in FIG. 8, a reaction tube b in which an inert gas is circulated from the lower side to the upper side is vertically provided in a condensing radiant furnace a, and an iron crucible c is provided in a heating portion in the reaction tube b. In the iron crucible c, an alloy with iron is not formed in the iron crucible c, an oxide is not easily generated, and the specific gravity is higher than that of the slag S in the iron crucible c. The metal M is accommodated in a molten state together with the slag S that is the measurement target.
In the measurement, the electrolysis force between the iron crucible c also serving as a control electrode and the standard electrode is measured by immersing the solid electrolyte e of the closed end type having the standard electrode in the molten metal M and the slag S in the molten state. f and the temperature measurement on the support d
The thermoelectromotive force detected by the temperature-measuring element g arranged inside is measured by the meter h, and the oxygen activity of the slag S is measured based on these measured values. With the advent of this device, it became possible to measure the oxygen activity in the slag collected from the actual furnace with high accuracy and in a short time.

[0004]

However, in this measuring apparatus, the reaction tube b is made of transparent quartz which has a high transmittance of infrared rays as a heat source radiated from the condensing radiant furnace a and has a high hot strength in a high temperature state. Although a tube is used, as a result of a rapid temperature rise inside the reaction tube b, iron vapor (fumes) is rapidly generated from the surface of the iron crucible c and the sample slag, and these fumes adhere to the inner wall of the reaction tube b. As a result of contaminating the reaction tube b, there is a problem that the transmittance of infrared rays is lowered in the course of use and the thermal efficiency is remarkably lowered, making it impossible to uniformly heat the surface of the iron crucible c. Then, in order to perform sufficient heating under such a condition, it is necessary to greatly increase the power of the furnace, but this causes a problem that the burden of the furnace becomes large and the life of the furnace is shortened. Further, the reaction tube b devitrified due to the attachment of contaminants and the like easily absorbs heat in the reaction tube itself, and as a result, devitrification of the reaction tube b progresses further, and the decrease in thermal efficiency increases synergistically as the number of melting increases. Become. To deal with this, positively increase the flow rate of the inert gas introduced into the furnace to forcefully discharge the fumes outside the furnace,
As a passive measure, there is a method of cleaning and removing contaminants attached to the reaction tube with hydrofluoric acid or the like depending on the contamination situation. However, the former method is not effective for iron fume or the like having a large specific gravity, and there is a concern that the sample slag in the iron crucible may be entrained and scattered outside the iron crucible c due to an increase in the exhaust flow rate. The latter method not only takes time and labor to replace the reaction tube b, but also involves danger to the human body at the time of cleaning, and it does not always ensure reliable cleaning and removal, and the cleaning effect decreases as the number of times of cleaning increases. In addition, there is a problem in that this method is extremely inefficient in practical use because it requires installation of cleaning equipment.

Japanese Patent Application No. 1-271033 (Japanese Patent Application Laid-Open No. 3-131748)
In the measuring apparatus of No. 3, the iron crucible c is placed on the upper part of the support d consisting of an iron hollow tube, but the upper part of the support d is in the heating range in the furnace, and its heat capacity affects the melting conditions. give. That is, when the heat capacity of the support base d is large, the load on the furnace is large and it takes time to raise the temperature, and when the heat capacity is small, the problem of seizure between the iron crucible c and the support base d and the support There is a problem that melting of the table itself occurs. Further, the burn-in and the melting loss of the support stand depend on the size of the heat capacity of the support stand, but there are factors other than the heat capacity. That is, since infrared rays have high reflection efficiency for objects having a mirror surface or a white surface, heating efficiency for these objects is low, while infrared rays have low reflection efficiency for objects having dark surfaces and black objects. Heating efficiency is high. Although the inside of the reaction tube b is filled with an inert gas, when the purity of the inert gas is low or the upper and lower parts of the reaction tube b are not tightly sealed and there is an inflow of outside air, the support base d is measured. As the number of times increases, the surface thereof undergoes oxidative discoloration due to heating, and as a result, there is a problem that heating efficiency increases and the frequency of baking and melting loss increases. Since the support base is arranged in the heating range in the furnace in this way, it causes an increase in the load on the furnace and, as a result, the heating efficiency changes due to the change in the state of the surface of the support base d. It is difficult to prevent burning and melting damage by setting the heat capacity of the support base d in a specific range, and there is also a problem that the heating efficiency for the iron crucible c cannot be kept constant.

The iron crucible c is heated to 1400 by heating for a short time.
It is necessary to raise the temperature to a desired temperature of ℃ ~ 1500 ℃, it is necessary to prevent melting loss in the iron crucible c or seizure with the support base d even in this rapid heating. Also, from the viewpoint of extending the life of the furnace, it is desirable that the load on the furnace is small. Japanese Patent Application No. 1-271033 (Japanese Patent Application Laid-Open No. 3-1
No. 31748) does not particularly consider the shape and heat capacity of the iron crucible c. Therefore, if the shape and heat capacity of the crucible c are too large, it takes time to raise the temperature and the load on the furnace is increased. On the other hand, if the shape and heat capacity of the crucible c are small, the temperature can be raised in a short time and the load on the furnace is reduced, but if there is a time delay in controlling the heat quantity or the iron crucible c If the temperature of the iron crucible c is not uniform, the iron crucible c may be melted.

The present invention has been made in view of the above situation, and it is possible to prevent the expensive reaction tube from being polluted to prolong the life of the apparatus and reduce the apparatus maintenance cost, and to avoid the contamination in the furnace. By making the burden of the furnace constant regardless of the number of measurements, the life of the furnace itself can be extended, and by optimizing the shape and heat capacity of the iron crucible, the burden on the furnace can be reduced. It is intended to completely solve the problems of melting of the iron crucible and seizure with the support.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present inventor has conducted diligent research and, as a result, conceived to adopt a multi-layer tube structure in which an exhaust pipe for guiding the exhaust of fumes is additionally provided inside the reaction tube. did. That is, the present invention uses the outer peripheral surface of the iron crucible
It can be covered and its upper end is above the iron crucible.
The transparent inner tube extended above the end opening position
An iron crucible that is installed in the crucible and is in the transparent reaction tube internal space.
The steam generated from the iron crucible and slag is located above the bob.
The exhaust pipe that guides the passage is partially covered with the upper part of the transparent inner pipe.
With a gap for introducing an inert gas between it and the transparent inner tube
It is characterized by being arranged in.

Further, in order to prevent a change in the heating efficiency of the supporting table from affecting the load of the furnace, it is preferable to cover the supporting table with a light-shielding protective tube. Furthermore, it is more preferable that the support base is divided into two parts in the height direction so that the upper member can be replaced, and the iron crucible has an outer diameter of 22 to 13 mm, an inner diameter of 19 to 10 mm, and a wall thickness of 3 to 1.5 mm. The most preferable heating condition can be realized when the thickness is set in the range of 45 to 15 mm.

[0010]

The oxygen activity in the slag using the device of the present invention is measured as follows. First of all, it does not form an alloy with iron in an inert atmosphere and does not form oxides, and stores a specific metal in a solidified state in an iron crucible and puts the slag to be measured on it, or puts it in the iron crucible. The slag is stored first and then the specific metal is added. Then, the transparent inner tube was sheathed in an iron crucible, and after the iron crucible was placed on a support, the transparent crucible was positioned at a predetermined position in the transparent reaction tube. While circulating, the iron crucible is heated by a condensing radiant furnace to melt the slag and the specific metal.

Subsequently, the closed-end tube type solid electrolyte containing the standard electrode is immersed in a specific metal through the molten slag layer, and the oxygen activity in the specific metal is measured to measure the oxygen content in the slag. The oxygen activity of is measured.

Although fumes are generated from the heated iron crucible, since the exhaust pipe is arranged above the iron crucible inside the reaction tube, the fumes are exhausted to the outside of the reaction tube through the exhaust pipe by the chimney effect. Although the amount of fume attached to the inner surface of the exhaust pipe increases as the number of measurements increases,
The inner surface of the reaction tube is hardly polluted. Further, even if the inner surface of the exhaust pipe is contaminated, the space surrounded by the exhaust pipe originally does not need to be heated. Therefore, the contamination of the inner surface of the exhaust pipe does not affect the heating conditions of the iron crucible. The heating efficiency can be stabilized over a long period of time. Further, when the inner surface of the exhaust pipe becomes significantly contaminated, it can be dealt with only by appropriately replacing the exhaust pipe, and the replacement of the expensive transparent reaction tube is hardly necessary.

Further, when the outer surface of the support base is covered with a light-shielding protection tube, the heating of the support base is limited to prevent oxidative discoloration of the outer surface of the support base, and the efficiency of heating the support base can be made constant. Therefore, it becomes easy to design the heat capacity of the support base.
Then, under such conditions, by making the shape of the iron crucible a specific one, it is possible to prevent burning or melting damage between the iron crucible and the support, while enabling rapid temperature rise.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a cross-sectional explanatory view showing an embodiment of the oxygen activity measuring apparatus for slag of the present invention, and FIG. 2 is an enlarged cross-sectional view of the essential part of the same embodiment. In the figure, 1 is a transparent reaction tube made of a heat-resistant material such as quartz, and the transparent reaction tube 1 is positioned at the center of a concentrating radiant furnace 2 which is a heat source in the melting furnace. In the present embodiment, the condensing radiant furnace 2 having a heat source capacity of 8 KW is used, but the heat source capacity is appropriately set according to the capacity of the iron crucible to be heated. The concentrating radiant furnace 2 has the advantages that temperature control is easy, the time required for temperature rise is short, and strong heating is possible, so that slag can be melted in a short time.

The lower part of the transparent reaction tube 1 is fixed to the base 4 via the connecting tool 3, and the upper part is sealed by covering the upper part with the canopy 5. The side part of the connecting tool 3 is filled with nitrogen gas or argon gas. A gas inflow path 6 is provided to allow an inert gas to flow into the transparent reaction tube 1. On the other hand, the canopy 5 is provided with a solid electrolyte insertion hole 7 which also serves as a gas discharge hole for discharging the inert gas inside the transparent reaction tube 1. Also, canopy 5
A water cooling pipe 8 is attached to the side and the side of the connector 3.

In the figure, 9 is a support for mounting an iron crucible. Inside the support 9, a temperature measuring element 10 is provided with its temperature sensing portion in contact with the lower surface of the iron crucible 11. It is fixed. The support base 9 is composed of an upper support base 9a and a lower support base 9b, and connects the upper and lower support bases 9a and 9b via a step. The reason why the support base 9 is divided into upper and lower parts is that it is close to the heat source and the upper part of the support base, which is subject to severe oxidative discoloration, can be replaced, so that the lower part of the support base can be used continuously and the running cost of the device is not reduced. However, it is not always necessary to divide it.

The iron crucible 11 placed on the upper part of the support 9 accommodates both the slag S to be measured and the specific metal M. As the specific metal, any metal may be adopted as long as it does not form an alloy with iron in an inert atmosphere, is hard to generate an oxide, and has a specific gravity larger than that of the slag S. Although silver, copper, etc. exist, silver is used in this embodiment. In the molten slag S and the specific metal M, a closed-end tube type solid electrolyte 12 having a standard electrode (not shown) is immersed. The standard electrode side lead 13 derived from the solid electrolyte 12 penetrates the canopy 5 of the transparent reaction tube 1 and is guided to the outside of the transparent reaction tube 1, while the iron crucible 11 serving as a control electrode is connected to the iron crucible 11. The reference electrode side circuit is guided to the base 4 through the electrically conductive support 9, and an oxygen concentration battery is formed between the base 4 which is the reference electrode and the standard electrode side lead 13. . Although not shown, the base 4 and the standard pole side lead 13
A measuring instrument is attached between and so that the electromotive force generated from the oxygen concentration battery can be measured.

According to the present invention, in such an apparatus, it is most preferable that the iron crucible 11 is provided with a transparent inner tube 14 having a specific size and the exhaust pipe 15 is disposed at a specific position in the internal space of the transparent reaction tube 1. This is a major feature.

As shown in FIG. 2, the transparent inner tube 14 has an inner diameter slightly larger than the outer diameter of the iron crucible 11, and its length is set longer than the length of the iron crucible 11. Transparent inner tube
The inner diameter of 14 is set to be slightly larger than the outer diameter of the iron crucible 11 to provide a gap between the transparent inner tube 14 and the iron crucible 11, because the transparent inner tube 14 is made of quartz and hardly thermally expands. This is because it is intended to prevent the iron crucible 11 that is thermally expanded by heating from being destroyed. For example, when the present inventor conducted an experiment using the apparatus shown in the figure, the transparent inner tube 14 and the iron crucible were
If the gap between the iron crucible and 0.5
It is not possible to avoid the destruction of the transparent inner tube 14 due to the above. On the other hand, if it is 1.5 mm or more, it is not possible to prevent the fume generated from the side wall of the iron crucible 11 from reaching the inner surface of the transparent reaction tube. It has been found that it is preferable to set the gap size between 14 and the iron crucible 11 in the range of 0.5 mm to 1.5 mm in this embodiment. In this way, the gap size is 0 in this embodiment.
Although it is set in the range of 5 mm to 1.5 mm, when other device configurations are used, other gap sizes may be used as long as both the above problems can be avoided. Further, the length of the transparent inner tube 14 is made longer than the length of the iron crucible 11 by making the transparent inner tube 14 which covers the iron crucible 11 function as a wall, so that the boiling slag S can be converted into the iron crucible 11. This is to prevent spilling to the outside and also to prevent fume generated from the side surface of the iron crucible 11 from contaminating the inner surface of the transparent reaction tube 1. As the transparent inner tube 14, a transparent inner tube that allows infrared rays radiated from a heat source to pass therethrough without attenuation is used. Then, the transparent inner tube 14 is a consumable type that is used only for one measurement, like the iron crucible 11, so that the material and the wall thickness may be such that the shape can be maintained at least during the measurement time, for example, A thin quartz tube or the like is used.

The exhaust pipe 15 is located above the transparent inner pipe 14,
The transparent inner tube (14) is provided with a part of the upper part thereof covered and an inert gas introducing gap (16) provided between the transparent inner tube and the transparent inner tube (14). The exhaust pipe 15 is for guiding the fumes generated from the iron crucible 11 so as to be discharged to the outside of the transparent reaction tube 1 without contacting the inner surface of the transparent reaction tube 1 as much as possible. Since fume is heavy, it is difficult to discharge iron vapor with a simple exhaust pipe.Therefore, in the present invention, a gap 16 for introducing an inert gas is provided between the transparent inner pipe 14 and The fumes are guided upward by riding on the flow of an inert gas such as argon gas that blows up. The flow rate of the inert gas increases as it passes through the inert gas introducing gap 16 which is a narrow path, and the fumes are discharged to the outside of the transparent reaction tube 1 together with the inert gas. The gap 16 for introducing the inert gas is designed on the assumption that a flow velocity sufficient to exhaust the fumes can be obtained, and in this embodiment, the gap is set in the range of 2 mm to 5 mm. Since the exhaust pipe 15 is intended for exhausting fumes, it does not need translucency, and therefore an inexpensive heat-resistant pipe can be used. Further, various components contained in the fumes will adhere to the inner surface of the exhaust pipe 15, but as described above, there is no problem since the exhaust pipe 15 does not need translucency. If the exhaust gas is hindered by the increase, the exhaust pipe 15 may be replaced appropriately. Since an inexpensive heat-resistant pipe can be used as the exhaust pipe 15, the influence of replacement of the exhaust pipe 15 on the increase in running cost can be minimized.

As described above, the present invention is characterized in that the transparent inner tube 14 is mounted on the iron crucible 11 and the exhaust pipe 15 is provided above the iron crucible 11. Optimum heating conditions for crucible 11,
And to prevent this condition from changing, the iron crucible 11
In consideration of the dimensions and shape, the amount of infrared rays absorbed by the support base 9 that supports the iron crucible 11 is made constant. In order to eliminate the change in the amount of infrared absorption on the support 9, it is significant to suppress the oxidative discoloration reaction on the surface of the support 9, and in order to suppress the oxidative discoloration reaction, the support 9 is protected against light. It has been found that it is effective to sheath the tube 17. In the illustrated embodiment, an opaque quartz tube is used as the light-shielding protective tube 17 that covers the support base 9. By covering the opaque quartz tube, it is possible to remarkably suppress the heating efficiency of the supporting table 9, and as a result, the discoloration of the outer surface of the supporting table 9 is suppressed, and the heating efficiency for the iron crucible 11 is kept substantially constant. Became possible. Then, on the assumption that the heating conditions for the iron crucible 11 can be maintained substantially constant, in order to determine the outer dimensions of the iron crucible 11, a heating experiment was performed by changing the dimensions, and the optimum dimensions of the iron crucible 11 were derived. . Table 1 shows various dimensions of the iron crucible used in this experiment, and FIG. 3 shows a temperature rise trajectory of the iron crucible when these iron crucibles were used. An 8 KW condensing radiant furnace was used for the experiment, and the temperature was measured by the temperature measuring element 10 positioned below the iron crucible.

[0022]

[Table 1]

As is apparent from FIG. 3, the outer diameter is 25 mm and the inner diameter is
22mm and 60mm in height require a considerable time to reach the target temperature of 1500 ℃, while the outer diameter of 22mm,
The target temperature is reached in 240 seconds with an inner diameter of 19 mm and a height of 45 mm, and about 16 with an outer diameter of 13 mm, an inner diameter of 10 mm, and a height of 15 mm.
It was found that the target temperature was reached in 0 seconds. From these results, when the heat source capacity of the concentrating radiant furnace is about 8 kW,
It was found that the heating rate can be almost satisfied if the outer diameter is 22 mm to 13 mm, the inner diameter is 19 mm to 10 mm, and the height is 45 mm to 15 mm. In addition, although not particularly described, if the thickness is in the range of 3 mm to 1.5 mm according to a separate experiment for changing the thickness,
It was also confirmed that an almost satisfactory heating rate could be achieved. It was also found that if the outer diameter is 13 mm, the inner diameter is 10 mm, the height is 45 mm, and the wall thickness is 1.5 mm or less, the rate of temperature increase is high, but seizure and melting loss may occur, which is not preferable.

Thus, the iron crucible 11 used in the present invention
The size and shape of the iron crucible 11 are determined in order to prevent seizure and melting damage. It is designed from the viewpoint of the reliability of the physical contact, and in this embodiment, as shown in FIG. 4, a recess 18 is formed on the lower surface of the iron crucible 11, while
A convex portion 19 that fits into the concave portion 18 is formed on the upper end of the support base 9. The fitting relationship can be reversed as a matter of course. As shown in FIG. 5, a convex portion 20 can be formed on the lower surface of the iron crucible 11 and a concave portion 21 can be formed on the upper end of the support base 9.

To use the oxygen activity measuring device in the slag having the above-mentioned structure, the following procedure is performed. First, the iron crucible
The slag S collected from the converter and ladle is housed in the 11 together with the specific metal M. At this time, the specific metal M is in a solidified state, but the slag S may be in a molten state. However, from the viewpoint of shortening the measurement time, the molten slag S
Needless to say, it is preferable to use

Next, the iron crucible 11 is placed on the upper surface of the support base 9 which is covered by the light-shielding protection tube 17, and the transparent inner tube 14 is mounted on the iron crucible 11, and the iron crucible 11 in this state is
It is housed and fixed at a predetermined position in the transparent reaction tube 1 in which the exhaust pipe 15 is installed. When the iron crucible 11 thus arranged is placed in the transparent reaction tube 1, a transparent reaction is performed by injecting an inert gas from the gas inflow path 6 and exhausting gas from the insertion hole 7 which also serves as a gas exhaust hole. A gas flow from the lower side to the upper side is created inside the tube 1, and under this condition, the concentrating radiant furnace 2 is operated to rapidly heat the iron crucible 11 to melt the slag S and the specific metal M. The heating is done by infrared rays emitted from a heat source, the outline of which is shown in FIG. That is, the infrared ray R irradiated from the heat source and directed to the iron crucible 11 is transmitted through the transparent inner tube 14 which covers the iron crucible 11 and is transmitted to the iron crucible 11.
Infrared R that heats the surface but, on the other hand, heads for the support 9.
Is blocked in its path by a light-shielding protective tube 17 that covers the support 9, and most of it is converted into heat inside the light-shielding protective tube 17 without reaching the surface of the support 9, or as shown in the figure. It is reflected to the outside of the light-shielding protective tube 17. In this way, since the infrared rays R of the concentrating radiant furnace 2 heat only the iron crucible 11, rapid heating of the iron crucible 11 is possible, while the efficiency of heating the surface of the support 9 is extremely low. It is also possible to prevent oxidative discoloration on the surface of the support base 9. Further, since the transparent inner tube 14 is extended on the outer periphery of the opening of the iron crucible 11, the boiling slag S will not be spilled out, and the inert gas will not flow into the iron crucible before the slag S is melted. It does not get caught in 11 and scatter the slag.

Inert gas G passing through the transparent reaction tube 1
As shown in FIG. 7, the flow rate increases from the lower side to the upper side, and particularly when passing through the inert gas introducing gap 16 formed between the exhaust pipe 15 and the transparent inner pipe 14, the flow velocity increases. The increased inert gas G guides the fume F generated from the iron crucible 11 into the exhaust pipe 15. Therefore, the fume F having a large specific gravity can be prevented from flowing down, so that the inner surface of the transparent reaction tube 1 is not contaminated, and the transparency of the transparent reaction tube 1 can be maintained for a long period of time.
The frequency of discarding and replacing the expensive transparent reaction tube 1 can be significantly reduced.

After the slag S and the specific metal M are dissolved, the solid electrolyte 12 is lowered from above the iron crucible and passed through the slag layer, and then the tip is immersed in the specific metal. In this state, an oxygen concentration battery is formed between the standard electrode side lead 13 and the reference iron crucible 11 with the solid electrolyte 12 and the specific metal M interposed therebetween, and the electromotive force generated by this oxygen concentration battery is standard. It is measured by an instrument (not shown) connected between the pole side lead 13 and the control pole. Further, the temperatures of the slag S and the specific metal M are constantly measured by the temperature measuring element 10 installed in the support base 9 and are instructed to a temperature measuring instrument (not shown), and arithmetic processing is performed based on these two values. By doing so, the oxygen activity in the slag is calculated. Since the specific metal that does not form an alloy with iron and produces very little oxide is used, the oxygen activity in the specific metal is in equilibrium with the oxygen activity in the slag, and the mutual oxygen activities are Since there is a correlation between the amounts, the oxygen activity in the slag can be obtained based on the oxygen activity value in the specific metal calculated by the above method.

When the measurement of the oxygen activity is completed, the inert gas in the transparent reaction tube is exhausted, and then the iron crucible 11 is taken out of the transparent reaction tube to complete the measurement. Since the present invention uses a condensing radiant furnace as a melting furnace, it is possible to raise the temperature inside the transparent reaction tube in a short time. For example, in this embodiment using an 8 KW condensing radiant furnace, the reaction tube It takes about 1 to 15 minutes from the time when the iron crucible is housed to the time when the iron crucible is taken out, and the oxygen activity can be measured extremely quickly.

[0030]

As described above, according to the method and apparatus for measuring oxygen activity in slag of the present invention, the oxygen activity of the slag contained together with the specific metal is measured, so that the solid electrolyte is measured. It has the basic effect that it can be brought into complete contact with the target, and furthermore, the transparent inner pipe is exteriorly mounted on the iron crucible and the exhaust pipe is placed above the iron crucible to guide the fume exhaust. It is possible to prevent fouling of the transparent reaction tube due to fumes, and it is possible to significantly reduce the frequency of replacement of the expensive transparent reaction tube.
Also, since it is possible to prevent fouling inside the furnace, it is possible to keep the burden on the furnace constant regardless of the number of measurements.
The life of the furnace itself can be extended.

When the gap for introducing the inert gas is set to 2 to 5 mm, the flow velocity of the inert gas passing through the gap is moderately increased, and the fumes having a large specific gravity are surely guided upward. You can

Further, when a light-shielding protective tube is provided on the outer surface of the support base, the heating of the support base is limited to prevent oxidative discoloration of the outer surface of the support base, and the efficiency of heating the support base can be kept constant. Therefore, it becomes easy to design the heat capacity of the support base.
Then, under such conditions, by making the shape of the iron crucible a specific one, it is possible to prevent burning or melting damage between the iron crucible and the support, while enabling rapid temperature rise.

Further, when the support base is divided into two parts in the height direction, when the upper part of the support base is contaminated, it is possible to deal with it by replacing only the upper member, and the running cost can be further reduced.

When the heat source capacity of the concentrating radiant furnace is 8 KW, the iron crucible has an outer diameter of 22 to 13 mm and an inner diameter of 19 to 10 m.
It is preferable to set m, wall thickness 3 to 1.5 mm, and height 45 to 15 mm. When this range is set, baking or melting loss between the iron crucible and the support table is possible while enabling rapid temperature rise. Can be reliably prevented.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing an embodiment of an apparatus for measuring oxygen activity in slag according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the same embodiment.

FIG. 3 is a graph showing a temperature rise trajectory of iron crucibles having different dimensions.

FIG. 4 is an explanatory sectional view showing a method of fixing the iron crucible to the support base.

FIG. 5 is an explanatory sectional view showing another method of fixing the iron crucible to the support base.

FIG. 6 is an explanatory cross-sectional view of a main part showing a heating state inside a transparent reaction tube.

FIG. 7 is an explanatory cross-sectional view of an essential part showing a flow of an inert gas inside a transparent reaction tube.

FIG. 8 is an explanatory sectional view showing a conventional device for measuring oxygen activity in slag.

[Explanation of symbols]

 1 Transparent Reaction Tube 2 Concentrating Radiation Furnace 6 Gas Inflow Path 7 Insertion Hole 9 Support Stand 10 Temperature Measuring Element 11 Iron Crucible 12 Solid Electrolyte 13 Standard Electrode Lead 14 Transparent Inner Tube 15 Exhaust Pipe 16 Inert Gas Introducing Gap 17 Light-shielding protection tube R Infrared G Inert gas F Fume

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-131748 (JP, A)

Claims (5)

[Scope of utility model registration request] 1. An inert gas is introduced into the concentrating radiant furnace from below to above.
A transparent reaction tube circulated toward one side is hung vertically, and in the iron crucible placed on the support table in a detachable state at the heating target site in the transparent reaction tube, iron and It contains a specific metal that does not form an alloy, is hard to generate oxides, and has a higher specific gravity than the slag, and accommodates it in a molten state with the slag to be measured. In an apparatus that measures the oxygen activity in the slag by measuring the electromotive force between the iron crucible that is immersed and also serves as the control electrode and the standard electrode, it is possible to cover the outer peripheral surface of the iron crucible and its upper end. A transparent inner tube extended to a position above the upper end opening position of the iron crucible is installed on the iron crucible, and at the upper position of the iron crucible in the transparent reaction tube inner space, the steam generated from the iron crucible and the slag is Oxygen activity in the slag to an exhaust pipe for guiding the passage, formed by arranging in a state in which a inert gas feed gap between the transparent inner tube <br/> upper part exterior to and transparent inner tube Quantity measuring device. 2. The apparatus for measuring oxygen activity in slag according to claim 1, wherein the gap for introducing the inert gas is set to 2 to 5 mm. 3. An apparatus for measuring oxygen activity in slag according to claim 1, wherein the support table on which the iron crucible is placed is covered with a light-shielding protective tube. 4. A support base on which an iron crucible is placed is mounted in a height direction 2
The oxygen activity measuring device in slag according to claim 1 or 2, which is divided and the upper member can be replaced. 5. The iron crucible has an outer diameter of 22 to 13 mm and an inner diameter of 19 to 10 m.
The apparatus for measuring oxygen activity in slag according to claim 1, 2, 3 or 4, wherein m, wall thickness is 3 to 1.5 mm, and height is 45 to 15 mm.