JPH05312651A - Continuous temperature measuring apparatus and component analyzing apparatus for molten metal - Google Patents

Abstract

PURPOSE:To obtain an apparatus for continuously measuring temperature and analyzing components of molten metal stably. CONSTITUTION:The continuous temperature measuring/component analyzing apparatus for molten metal comprises an optical measuring unit 4, a tuyere 3, and a gas transmissive porous body 15 having central through hole, wherein the optical measuring unit is disposed at the base end part of the tuyere while the gas transmissive porous body 15 is projected in front of the tuyere so that a through hole 17 will communicate with the central port of the tuyere. Since a desired mashroom shape is obtained for the measuring hole tuyere and a straightforward optical path is obtained stably, temperature and compositional elements of molten metal can be measured stably, continuously, and accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a long-life tuyere by simultaneously performing tuyere protection through the tuyere of a metal-smelting furnace such as a steelmaking converter, a smelting reduction furnace, a scrap melting furnace, and an electric furnace. The present invention relates to an apparatus for continuously measuring the temperature and constituent elements of a molten metal in a furnace while aiming for improvement.

[0002]

_2. Description of the Related Art For example, during an O ₂ blowing operation for about 20 minutes per charge in a steelmaking converter, a device called "sublance" for measuring the temperature of molten metal and collecting an analytical sample is generally used. Target. However, this device is originally intended for discontinuous use, and a waiting time of about 5 minutes is required at the minimum to obtain the analysis result of the molten metal component from the collected sample. Therefore, there is only a method of predicting and controlling the target end point only by the temperature and the carbon content at one point during the blowing, and further, Mn and P other than carbon are used.
The current situation is that elements such as are finally known after tapping.

In the gas analysis on the exhaust gas side, despite the fact that a continuous measurement technique has already been established, there is a lack of continuous information on the temperature and composition of molten steel that dynamically changes during short-time blowing. Is a major obstacle for improving the end point temperature in the final stage of the blowing operation and the accuracy of the components, and achieving high efficiency by matching with high-speed continuous casting. Continuous temperature measurement and component analysis are performed. Development of the device is desired.

Japanese Patent Laid-Open No. 60-231141 discloses a combination of a pulsed laser beam and a tuyere-shaped thin tube mainly for cooling the molten metal in a furnace using inert gas cooling. The continuous measurement method "is shown.

As a continuous temperature measuring method, a method of using an optical fiber provided in a tuyere-shaped thin tube has been attempted, and any method of measuring temperature and chemical composition (component element) of this kind has been attempted. Optical measuring devices are usually applied. Therefore, in order to fully bring out the functions of these measuring devices, it is necessary that the light beam from the measuring instrument side always directly hits the molten metal, or the light beam from the molten metal side always reaches the detecting side of the measuring instrument. The front of the inner side of the furnace of the mouth-capillary tube must be kept healthy. The condition or state in which the front surface of the thin tube is melted and damaged must of course be strictly avoided.

As such tuyere-shaped thin tubes, single tubes of various materials, or double tube tuyere originally developed as refining tuyere are used. However, since the tuyere for this purpose basically flows mainly the cooling gas for protecting the tuyere including the detection part of the measuring device from the heat of the molten metal, the front of the tuyere does not A solid substance (so-called mushroom) is formed from the molten metal, and a meandering gas passage, a porous gas passage, or complete blockage is likely to occur. At this time, so-called “visual field loss” occurs, which leads to a decrease in measurement accuracy, and in a remarkable case, no information can be obtained from the molten metal side.

FIG. 6 is a diagram showing an example of visual field loss in a continuous temperature measurement test by an optical fiber conducted by the inventors using a double tube tuyere. The optical fiber 4 is inserted into the furnace outer end (in the present invention, this part is referred to as the base end) of the inner tube 3a of the double tube tuyere 3 provided through the refractory brick 1 and the iron shell 2 of the furnace, When (Ar + O ₂ ) 5a was flown to the inner tube 3a and (C ₃ H ₈ ) 5b was flown to the outer tube 3b, the mushroom 6 adhered to the tip of the front of the tuyere and the visual field was lost. The time during which warming was possible was about 1/2 of the total blowing time. After cooling, the naturally formed mushrooms 6 were taken out and longitudinally cut, and the gas passage 7 in the central portion was bent as shown in the drawing.

Further, in the example of continuous component analysis using a laser emission spectrometer by the same method as described above, it was difficult to obtain data that is consistent with the analysis result of the sublance sample. Since the shape of the mushrooms and the condition of the gas passages are unstable, it is considered that the phenomenon in which the light rays are blocked occurs due to a local or momentary visual field loss.

As a means for preventing the occurrence of visual field loss and ensuring a straight path of light, O ₂ is mixed into the cooling gas, and it is linked with data from another temperature measuring device provided at the tuyere. Although there is also a method of automatically controlling the O ₂ ratio (see Japanese Patent Laid-Open No. 60-231141), the problem of whether or not the temperature at the tuyere temperature measurement point is representative, and the delay in response However, it is generally not practical.

When a visual field loss occurs, the means for recovering the light passage is to mix O ₂ in a cooling gas flowing to the tuyere of the measurement hole at a ratio higher than a normal ratio to accelerate the oxidation reaction, and to heat the reaction. There is also a method to dissolve and remove a part of mushrooms, but there is no reliable method to obtain the basis for determining the mixing ratio instantaneously, and if you make a mistake, you will melt the tuyere itself, and eventually the important part of the measuring instrument. It may also cause the detector to melt.

[0011]

As described above, in the method of continuously measuring the temperature or the component of the molten metal by the non-contact type thermometer or the component analyzer provided in the conventional tuyere, the front face of the tuyere is used. Stable and accurate measurement was impossible because the shape and structure of the natural mushrooms generated at the tip of the was greatly affected. On the other hand, if it is attempted to form a mushroom having no visual field loss, only gas blowing conditions in a direction in which no mushroom is formed can be selected, and the refractory in the tuyere and its surroundings will be worn.

Therefore, in order to solve the difficult problem of preventing melting of tuyere at the same time while preventing the formation of mushrooms, it is necessary to constantly change the O ₂ amount and the cooling gas flow rate. There was a problem.

The object of the present invention is to measure, for example, the temperature and components that slightly change in the final stage of blowing of a steelmaking converter, and control the blowing conditions based on the results to determine the end temperature and the hit rate of the components. Aiming at a system that can contribute to improvement, by using known measuring means (for example, optical fiber thermometer, laser emission spectrometer), while protecting the tuyere, at the same time, the temperature or composition of the molten metal is stable and accurate. It is to provide a device that enables continuous measurement of elements.

[0014]

[Means for Solving the Problems] When attempting to measure the temperature and composition of molten steel by using a known technique such as an optical measuring instrument or tuyere, the success rate and accuracy of the measurement are The shape of the mushrooms attached to the tip of the tuyere front and the fluctuation of the flow rate of the cooling gas are greatly affected.

Therefore, in the present invention, a gas-permeable porous body (artificial mushroom) is applied to the tip of the front of the tuyere as a means for improving the stability of the mushroom, which is the root of the problem, and at the same time securing the straight path of light. It was decided to.

The gist of the present invention resides in the following device.

(1) A continuous temperature measuring device for a molten metal, comprising a non-contact thermometer, a tuyere, and a gas-permeable porous body having a through hole in the center thereof, wherein the non-contact thermometer is A continuous temperature measuring device for molten metal, which is installed at a base end portion of a tuyere, and wherein the gas-permeable porous body is attached so as to project from a tuyere front face such that a through hole is continuous with a tuyere center opening.

(2) An apparatus for continuous component analysis of molten metal comprising an optical analyzer, a tuyere, and a gas-permeable porous body having a through hole in the center thereof, wherein the optical analyzer is A continuous component analyzer for molten metal, which is installed at a base end of a tuyere, and wherein the gas-permeable porous body is attached so as to project to the front of the tuyere so that a through hole is continuous with the center of the tuyere.

[0019]

The artificial mushroom used in the apparatus of the present invention is a member which is connected to the tip of the center hole (innermost tube) in front of the multi-tuyer tuyeres of the metal refining furnace and is attached so as to project into the furnace. That is, the whole is composed of a gas-permeable porous body, and a fiber optic thermometer or a laser emission spectrometer sensor is attached to the base end outside the furnace corresponding to the tuyere center hole to detect the temperature and constituent elements of molten steel. It is something to measure.

FIG. 1 is a diagram showing a metal refining furnace (upper-bottom blowing converter) to which the apparatus of the present invention is applied. That is, double tube tuyeres 3 and 3'are provided inside the refractory brick 1 on the side wall (or the bottom of the furnace) 10 of the storage part of the molten steel 9 of the metal refining furnace 8. One of them is for a continuous temperature measuring device and the other is for a continuous component analyzer, which are independent of each other. The furnace shown in FIG. 1 is provided with necessary equipment such as a main lance 11 for blowing oxygen upward, the sub lance 12, a bottom blowing tuyere 13, and a dust collecting hood 14.

FIG. 2 is a diagram for explaining an example of the shape of the gas-permeable porous body 15 and the state of attachment to the double tube tuyere 3. In this case, the gas-permeable porous body 15 has a mushroom shape and has a gas reservoir 16 for uniform gas diffusion therein.
have. At its center, there is a through hole 17, which is located at a position corresponding to the tuyere inner pipe 3a. The through hole on the side where the gas-permeable porous body 15 and the refractory brick 1 are in contact with the outer tuyere pipe 3b. It is attached so that it comes to each.

FIG. 3 is a schematic view showing an example of the structure of a continuous temperature measuring device applied to the metal refining furnace of FIG. 1. As shown in this figure, the gas permeable porous body 15 'has an internal structure. The shape may be such that the gas reservoir 16 is not provided. This equipment consists of a double tube tuyere, and a gas permeable porous body at the tip of the front surface of the inside of this furnace.
A condenser 18 capable of detecting the temperature of the metal bath and a non-contact type optical fiber thermometer 4 are installed at the base end of the furnace 15 'and the tuyere 3 outside the furnace, and the temperature is measured by a device 19 for processing the bath temperature data of the molten steel 9. It is converted into the temperature, and is recorded and displayed on the temperature recorder 20.

The tuyere 3 is composed of the tuyere inner tube 3a and the tuyere outer tube 3b as described above, and is provided with an inert gas for cooling and protecting the tuyere itself, the condenser 18 and the non-contact type optical fiber thermometer 4. The inner tube gas 5a mainly composed of, and the outer tube gas 5b such as propane is flowed to protect the tuyere and the gas-permeable porous body 15 '.

In the case of an apparatus for analyzing continuous components of molten metal using a laser emission spectrometer or the like, the following apparatus configuration may be used. That is, a pulse laser transmitter and a plasma beam receiver generated by the pulse laser are provided at the positions of the condenser 18 and the non-contact optical fiber thermometer 4 at the base end outside the furnace of the tuyere 3 shown in FIG. Equipment for processing bath temperature data 19
An apparatus for converting a plasma beam into a component value is installed at the position, and a component recorder is installed at the position of the temperature recorder 20. The method of flowing the cooling gas is the same as in the case of the above continuous temperature measuring device.

Normally, when measuring, 5a shown in FIG.
5b N ₂ (Ar can be used) is measured while flowing a small amount of gas, etc., but when measurement is not always necessary (for example, in the initial stage of blowing of the converter), or solid matter adheres to the front of the tuyere to interfere with the measurement. When there is a possibility that a small amount of O ₂ gas is mixed with 5a to prevent the formation of solid matter that causes a visual field loss at the tip of the tuyere inner tube 3a, and also the advance timing that requires measurement. The solids must be removed with to secure the field of view in front of the inner tube.

The effects of the artificial mushroom are as follows.

As is well known, in so-called bottom-blown tuyeres for metal refining, the blades are delicately balanced by the cooling effect of the blown gas, the temperature of the molten steel that increases and rises momentarily, and the temperature of the refractory bricks around the tuyeres. Protect the tip of the tuyere and surrounding bricks by relying on the mushrooms that naturally form around the mouth. However, it is also well known that the location, size, growth rate, etc. at which this naturally formed mushroom first starts forming is not always uniform. Moreover, the shape and the direction of gas passage are greatly affected by so-called back attack caused by the jet of the blown gas and the flow phenomenon of molten steel, and in some cases, what is once formed is separated and disappears again. It is so unstable that it may get lost.

In order to eliminate such instability, an artificial mushroom having a composition similar to that of molten steel and having a stable shape close to that of natural mushroom and having a through hole connecting to the tuyere tube is previously prepared. It is attached to the tip of the front of the tuyere. By this method, the shape of the mushroom and the straight path of the light can be stably obtained, so that it becomes possible to measure the temperature and the constituent elements of the metal bath in a stable and continuous manner and with high accuracy. In the event that a phenomenon in which the above-mentioned momentary visual field loss has occurred is recognized, even if the oxygen ratio in the inner pipe cooling gas is increased, it is possible to obtain favorable melting loss only on the inner surface of the through hole. It remains so that mushroom stability is not immediately compromised.
Therefore, the refractory bricks around the tuyere for measurement are hardly worn, and stable refining and improvement of hit rate are possible.

In the artificial mushroom, FIG. 2 and FIG.
As shown in, the cross-sectional shape can be made hemispherical from the beginning, and since the whole is a porous body, the cooling gas flows evenly and radially. Therefore, it is possible to maintain the stability of the mushroom even when the cooling gas amount is close to a certain amount. Further, since the through-hole is provided and the straight path of the light is secured from the beginning, the fluctuation range of the amount of O ₂ gas used for preventing the visual field loss or securing the visual field can be reduced.

As described above, when the fluctuation range of the amount of gas used is reduced, the temperature fluctuation at the measurement point is naturally suppressed,
This has the effect of improving the temperature measurement accuracy.

The porous body constituting the protective member used in the apparatus of the present invention may be made of metal, and a large number of mechanically small holes may be formed therein. Are more preferable. Further, an aggregate of ceramic fibers having pores in the fibers, that is, a ceramic foam is put in a mold, and a metal can be cast thereon to relatively easily produce a porous body,
It is possible to manufacture such a protection member at low cost.

As the metallic component, cast iron steel having a carbon concentration of 0.5 to 2%, which is lower than that of the hot metal, is desirable as in the case of natural mushrooms, and other components may be used as long as they do not adversely affect refining. It may be a heat resistant steel such as Ni, Ni-Cr alloy steel or stainless steel. The porosity is 10 to 10
100 / cm ² and a pore size of less than 2.0 mm are preferable.

[0033]

EXAMPLE A top-bottom blowing converter for metal refining shown in FIG. 1 was used, and tuyeres for measuring the temperature of the molten steel and tuyere for measuring the components of the molten steel were separately provided on the side wall of the converter. The tests were carried out by attaching the gas-permeable porous bodies shown in FIG. 2, respectively. The comparative example is a case of the conventional method measured without attaching the gas-permeable porous body.

The temperature and components during blowing when molten iron was made into molten steel under the refining conditions shown in Table 1 were measured and compared with the conventional method. Table 2 shows the specifications of the gas-permeable porous body and the tuyere shape at this time. The results are shown in FIGS. 4 and 5. Table 3 compares only the results of the blowout stage.

FIG. 4 is a plot of an example of the results obtained by continuously measuring the temperature with an optical fiber thermometer according to the method of the present invention within a blowing time of 22 minutes. It was confirmed that stable and accurate measurement was possible during the smelting period.

Similarly, FIG. 5 shows an example of the result when the C, Mn and P components were continuously measured by the laser emission spectrometer according to the method of the present invention within the blowing time of 22 minutes by the sublance. It is a plot compared with the measurement result,
It was confirmed that stable and accurate measurement was possible during the entire blowing period.

As shown in Table 3, when the molten steel temperature was measured by the optical fiber thermometer by the device of the present invention, the field of view of the measurement hole could be stably maintained, and the measurement success rate was greatly improved. Further, even when compared with the sampling temperature measurement that was carried out as a test just before blowing off, the difference was only 15 ° C on average, which was smaller than the difference of 30 ° C in the comparative example, and there was little variation. This is because the field of view of the light from the molten steel is sufficiently secured, and the probability that low-temperature solid matter is present in the field of view is sufficiently low, and as shown in Table 1, the gas flown to the tuyere of the measurement hole. This shows that the measurement accuracy is improved due to the effect that the fluctuation range of the amount is reduced.

Even when the molten steel component was continuously measured by the laser emission spectrometer, the field of view of the measurement hole was sufficiently secured,
As shown in Table 3, both the measurement success rate and the analysis accuracy were improved, and the wear rate of the measurement hole tuyere was halved by the uniform and stable cooling by the gas-permeable porous body.

As used herein, the measurement success rate means that in the case of temperature, if the difference from the temperature measured by the Sublance method is within 100 ° C., it can be dealt with, that is, the ratio of the number of charges to the total number of charges when it is regarded as successful. Is. For component analysis,
It is the ratio of the number of charges to the total number of charges when it is regarded as successful if it is within ± 20% of the analysis value of the sample by the Sublance method.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

According to the continuous temperature and component measuring apparatus of the present invention, since the shape of the mushroom at the measuring hole tuyere and the straight path of light can be stably obtained, it is possible to stably and continuously
Moreover, it is possible to accurately measure the temperature of the metal bath and the constituent elements. Further, the refractory bricks around the tuyere of the measurement hole are hardly worn, and more stable refining and improvement of the end point temperature and the accuracy of the components are possible, which contributes to the reduction of refining cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a refining furnace using the apparatus of the present invention and an attachment position of the apparatus.

FIG. 2 is a cross-sectional view showing an example of the shape of a gas-permeable porous body and the state of attachment to tuyere in the device of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating the configuration of the device of the present invention when the temperature of the metal bath is continuously measured.

FIG. 4 is a diagram showing an example of the result of continuous measurement of the temperature of molten steel during the blowing time by the apparatus of the present invention shown in FIG.

FIG. 5 is a diagram showing an example of a result of continuous measurement of molten steel components during a blowing time.

FIG. 6 is a schematic cross-sectional view illustrating an example of the situation of a mushroom formed naturally when a gas-permeable porous body is not used.

Claims (2)

[Claims] 1. A continuous temperature measuring device for a molten metal, comprising a non-contact thermometer, a tuyere, and a gas-permeable porous body having a through hole in the center thereof, wherein the non-contact thermometer is a wing. A continuous temperature measuring device for molten metal, which is installed at a base end portion of a mouth, and wherein the gas-permeable porous body is attached so as to project to a front surface of a tuyere so that a through hole is continuous with a tuyere center opening. 2. A continuous component analyzer for a molten metal, comprising an optical analyzer, a tuyere, and a gas-permeable porous body having a through hole in the center thereof, wherein the optical analyzer is a wing. An apparatus for analyzing a continuous component of a molten metal, which is installed at a base end of a mouth, and wherein the gas-permeable porous body is attached so as to project to a front surface of a tuyere so that a through hole is continuous with a central mouth of the tuyere.