JPH0631683B2 - Position measurement method for molten metal lining surface - Google Patents

Description

The present invention relates to a method for measuring the position of a lining surface of molten metal in various metal melting furnaces such as a blast furnace and a converter, a molten metal container such as a ladle, and the like, This is intended to grasp the thickness of the furnace wall and the profile of furnace wall melting loss.

[Conventional technology]

Understanding the thickness of the furnace wall of this type of molten metal furnace or vessel is extremely important for the operation and safety management of the furnace in order to know the degree of melting loss due to the molten metal.

Conventional methods include (1) a method of embedding a radioisotope in the furnace wall, and (2) Japanese Patent Publication No. 58-27844.

[Problems to be solved by the invention]

However, the method (1) has the drawbacks that it is difficult to handle the radioisotope and that the thickness of only one point in the buried wall can be measured. The method (2) is an effective method, but it is laborious to bury the metal coaxial line, and it is necessary to replace the melting loss limit at each time, which is disadvantageous in terms of cost.

Therefore, an object of the present invention is to provide a measuring method that is easy to handle and saves the trouble of replacement. Occasionally, another object is to provide a measuring method capable of sufficiently protecting the tuyere, protecting bricks around the tuyere by optimally forming mushrooms around the tuyere, and reducing refractory repair costs. is there.

[Means for solving problems]

A tuyere is provided on the furnace wall in contact with the molten metal of the molten metal container, and one or more optical fibers that gaze at the solidified metal at the tip of the opening are applied to this tuyere, and the solidified metal surface is passed through the tuyere and melted at the tuyere portion. Cooling gas supply means for maintaining solidification of the metal are respectively provided; laser light is projected onto the surface of the solidified metal through the optical fiber, and reflected light reflected there is captured to grasp the position of the molten metal lining surface. It is what

The molten metal container includes a blast furnace, a torpedo car, a converter, a ladle, a tundish, an RH furnace and the like.

[Action]

In the present invention, the position of the solidified metal surface is measured based on the phase difference between the reflected light reflected from the molten metal lining surface, that is, the solidified metal surface, and the projected light through the optical fiber. As a result, if the tuyere portion of the molten metal container is melted, the outer surface of the container is displaced at the position, so that the vessel thickness of the tuyere portion can be grasped as a result, and in the tuyere opening cross section, By arranging a plurality of optical fibers and measuring the positions of a plurality of points, the profile of the solidified metal surface, and consequently the melting loss profile of the tip of the tuyere can be determined.

In the present invention, at the time of measurement, since it is a laser rangefinder using an optical fiber, there is no difficulty such as radio isotope in handling, it can be measured in a non-contact state with molten metal, and the measurement sensor is not worn, It does not require replacement and is economical.

By the way, the apparatus itself used for carrying out the method of the present invention is disclosed in
As is known from Japanese Patent Laid-Open No. 60-129628, the same device measures the temperature of molten steel, and the objects to be measured are completely different. In the present invention, basically, the known device is used for measuring the position of the lining surface of the molten metal, thereby alleviating the problems of the conventional method.

On the other hand, when measuring the molten steel temperature using a laser beam, the molten steel at the tip of the tuyere can not measure the melting temperature in the solidified, in the present invention, based on a completely opposite idea, Cooling gas is supplied through the tuyere in order to positively generate so-called mushrooms at the tip of the tuyere. By forming such mushrooms, it is possible to grasp the melting condition of the tuyere.

On the other hand, in the above publications, the cooling gas is supplied, but the purpose is to provide tuyere or optical fiber (including lens).
However, it is not intended to actively generate mushrooms, as is clear from the publication that it intends to measure the molten steel temperature. In addition, in the present invention, since the cooling gas is supplied with a cooling capacity such that mushrooms are generated, there is an advantage that the tuyere and the optical fiber can be more reliably protected from heat.

It is also possible to measure the position of the molten metal surface directly on the molten metal surface, that is, like the present invention, by projecting a laser beam without generating mushrooms, but an inert gas such as Ar may be used. When the surface of the molten metal is wavy due to blowing, the irradiation laser light is scattered and reflected, and the intensity of the emission spectrum of the molten metal itself is extremely strong. However, the S / N ratio is low and measurement is practically impossible. Furthermore, when injecting an inert gas from the bottom blowing tuyere like a top-bottom blowing composite blowing converter, the bubble shape at the tip opening of the tuyere becomes a spherical surface, so the above scattering and reflection becomes even larger. , Measurement becomes even more impossible. On the other hand, in the present invention, since mushrooms are generated, the surface thereof is stable and the emission spectrum intensity from the inner surface of the bulb is weak, and the above problem does not occur.

In addition, the generation of mushrooms reduces the amount of melting damage at the tuyere of the furnace wall, thus reducing the cost of refractory repair.

[Specific configuration of the invention]

 Hereinafter, the present invention will be described in more detail with reference to the drawings.

1 to 3 are provided with tuyere 2 in the molten metal pool portion in order to grasp the melting state of the furnace wall in the upper-bottom blowing composite blowing converter 1 as a molten metal container, It shows an example of measuring the position of the lining surface of the molten steel M.

The tuyere 2 has the conduits L _{1 to} L ₅ consisting of five heat-resistant pipes evenly arranged in the tuyere nozzle refractory 3 in the illustrated example, and emits light and receives light that gazes inside the furnace before the entrance thereof. Are arranged according to the number of the conduits L _{1 to} L ₅ , and each lens 4 is attached to the tip of the optical fiber 5, 5. Lens 4 and optical fiber 5 are protective boxes 6
A and the cooling gas passage 6B are covered.

Each optical fiber 5 is connected to a laser length measuring device 7, and its output is given to an image processing device 8. The cooling gas 9 passes through the flow rate adjusting valve 10 and the pressure gauge 11, enters the protection box 6A from the cooling gas passage 6B, passes through the conduits L _{1 to} L ₅ , and is blown into the furnace 1. There is. In FIG. 1, S is slag, and MA generated by blowing cooling gas is mushroom. L is a lance for blowing oxygen. Reference numeral 12 is a cooling gas measurement controller.

In such equipment, the cooling gas 9 is usually continuously supplied to the tuyere. As this cooling gas, CO ₂ gas or an inert gas (Ar, N ₂ etc.) that does not affect the refined metal is used, and preferably, a metal such as Fe ₂ O ₃ , MgO etc. is used as a cooling material in the gas. It is preferable to mix oxide powder to increase the cooling effect. By blowing the cooling gas 9, the molten steel in the tuyere 2 portion is cooled and the mushroom MA is generated. The mushroom MA generation control is based on the pressure signal from the pressure gauge 11 and adjusts the flow rate adjusting valve 10. It is done by doing. Of course, the cooling gas 9 is the conduit of the tuyere 2, the lens 4
And the optical fiber 5 is cooled and protected.

With the mushroom MA thus generated, the laser light from the laser length measuring device 7 is radiated from the optical fiber 5 and the lens 4 through the conduits L _{1 to} L ₅ to the surface of the mushroom MA, and the reflected light there is reflected. Can be grasped by the laser length measuring device 7 through the lens 4 and the optical fiber 5. In this laser length measuring device 7, the optical paths of the received light and the received light are separated, the distance of the optical path is calculated based on the phase difference between them by, for example, formula (1), and the mushroom MA of Knowing the position of the tuyere surface,
It is used as an index of the melting condition of refractory materials in tuyeres and furnaces.

D = (S / 2) + nt (V / 2) (1) where D: optical path distance, S: phase difference, n: t = 1 / f,
V: speed of light By the way, as laser light, molten steel components (Si, C, M
It is desirable to use near infrared laser light of 8000 Å to 12000 Å which avoids the spectrum generated when (n, S, P, etc.) is oxidized. Further, the inner surface of the conduit such as stainless steel is
It is also desired to perform a black baking treatment (alumite, etc.) so as to prevent unnecessary scattering and reflection.

〔Example〕

 Next, examples will be shown.

In the 170t top-bottom blowing composite blowing converter shown in FIG. 1, the tuyere of FIGS. 2 and 3 was attached, and the lining position of the molten steel was measured.

First, when the source pressure of the inert gas was set to 7 kgf / cm ² and the cooling gas was supplied, the supply gas pressure was initially about 1.5 to 2.5 kgf / cm ^2.
2 , while the cooling gas supply pressure was 5 to
It was confirmed that the mushroom had grown to 7 kgf / cm ² , mushrooms had grown, and covered the tuyere tip opening.

In this state, using 10000 Å near infrared laser light,
The measurement was performed. In this case, the S / N ratio was 10 or more, and the S / N ratio in the absence of mushrooms was 1 or less, showing a large difference.

The measurement was performed at each fiber (lens) position and traced for each number of times of blowing, and the results shown in FIGS. 4 and 5 were obtained. By this, it was confirmed that the temporal change of the melting loss of the tuyere or the furnace wall and the change of the melting profile could be clearly understood.

Further, according to the present invention, while measuring the lining surface of the molten metal, a cooling gas having a sufficient flow rate (pressure) is supplied to actively generate mushrooms, and when the lining surface of the molten metal is not measured, a small amount is obtained. When the change in the amount of wear of the tuyere was observed when the mushroom formation was unstable only by supplying the cooling gas of No. 2, the results of FIG. 6 were obtained, and according to the method of the present invention, the tuyere Was found to have a low wear rate.

On the other hand, when the correlation between the actual wear value of the tuyere length from which the tuyere was extracted and the wear amount measurement value by the method of the present invention was observed at every certain time during the operation, the results of FIG. 7 were obtained, and the method of the present invention was obtained. It was found that the measurement accuracy of was high.

〔The invention's effect〕

As described above, according to the present invention, advantages such as excellent handleability, capable of withstanding long-term use, and high measurement accuracy are brought about.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of application of the method of the present invention in a top-bottom blow composite blowing converter, FIG. 2 is a detailed sectional view of tuyere, and FIG. 3 is II.
FIGS. 4 to 7 are views of measurement results in the example, taken along the line I-III. 1 ... converter, 2 ... tuyere, 4 ... light emitting and receiving lens, 5 ... optical fiber, 7 ... laser length unit, 9 ... cooling gas, M ... molten steel, MA ... _{mushrooms, L} 1 ~L 5 _... conduit.

Claims (1)

[Claims] 1. A tuyere is provided on a furnace wall in contact with molten metal of a molten metal container, and one or more optical fibers that gaze at the solidified metal at the opening tip of the tuyere and the tuyere are applied to the surface of the solidified metal. Cooling gas supply means for maintaining solidification of the molten metal are respectively provided at the tuyere portions; laser light is projected onto the surface of the solidified metal through the optical fiber, and reflected light reflected there is captured to determine the position of the molten metal lining surface. A method for measuring the position of a molten metal lining surface characterized by grasping.