JPH0540092A - Apparatus for analyzing components of molten metal - Google Patents

Abstract

PURPOSE:To rapidly obtain the accurate analytical result of the components of molten steel by transmitting laser beam for analysis to a remote position. CONSTITUTION:A laser waveguide 2 transmitting laser beam for analysis and an optical fiber 2 propagating the plasma beam generated on the surface of a sample are passed through the innermost peripheral pipe 1a of a water cooling cylinder 1 having a triple structure and the intermediate pipe and outermost peripheral pipe thereof are water cooling pipes 1b, 1c through which cooling water 15 circulated. A plurality of joint parts 5 having the degree of freedom are provided on the way of the laser waveguide 2 and laser beam is transmitted to the sample while reflected by the joint parts 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal component analyzer for analyzing a molten metal component such as molten steel by laser emission spectroscopy.

[0002]

2. Description of the Related Art In refining work of molten metal, particularly in converter refining of steel, molten metal (molten steel)
There is a strong demand for higher accuracy in the component analysis and reduction of analysis time.

At present, as a typical component analysis method for molten steel used in the refining process of iron and steel, there is a discharge emission spectroscopic analysis method using electric discharge. In this method, for example, a sample that is a part of molten steel is sampled in a sampling container by the sublance method shown in Iron and Steel Handbook VOL2, p490, and then analyzed in a fully-equipped analytical room. ..

In this analysis method, the sample is sampled, the sample is taken out of the sampling container, the sample is transferred into the analysis chamber, the sample is cooled, cut, and polished. It takes about 5 minutes from the start of sampling to the completion of analysis processing. Considering that the refining process takes about 20 minutes, this 5 minutes can be said to be a very long time. Therefore, when the analysis result is obtained, the analyzed molten steel may have already finished the refining process and moved to the next process, or the refining may proceed to refining the molten steel with greatly different components. The problem is that the analysis results cannot be used effectively.

Different from the discharge emission spectroscopy as described above, attempts have been made to directly analyze the components of molten metal (molten steel). Among such direct analysis methods, a sample is irradiated with laser light to generate plasma light on its surface, and the plasma light is spectrally analyzed to directly analyze the components of the molten metal, so-called laser emission spectroscopy. The method is widely used. Compared to discharge emission spectroscopy, this laser emission spectroscopy is less susceptible to changes in distance from the sample surface, has a short response time, and is capable of analyzing samples at a distance of about 1 m. It is advantageous in that it can be automated without being consumed.

When the composition of molten steel in converter refining is analyzed by laser emission spectroscopy, the molten steel surface is covered with a thick slag layer, so it is necessary to form a sample surface from which this slag is removed. is there. As a direct analysis method of molten metal (molten steel) in consideration of such a point, for example, JP-A-61-61
─ There is one disclosed in Japanese Patent No. 181946.

In the method disclosed in Japanese Patent Laid-Open No. 61-181946, a laser oscillator and a spectroscope are arranged in a room having a water-cooled double wall, and a condenser tube equipped with a window is used as a part of the double wall. The laser beam is transmitted to the inside of the condenser tube through this window, and the molten metal is irradiated with the laser beam in the consumable sample probe attached to the tip of the condenser tube. This sample probe has
A metal cap is provided like the paper tube of the conventional sublance method, and the metal cap is removed when the sample probe passes through the slag surface and is immersed in the molten metal. Therefore, it is possible to prevent the slag from entering the sample probe and to analyze the molten metal. Further, in the method disclosed in Japanese Patent Laid-Open No. 61-181946, the sample probe is immersed in the molten metal at the time of sampling by expanding / contracting the condenser tube or raising / lowering the entire apparatus.

[0008]

In the above-mentioned conventional example,
There are problems as described below. When the components in steel are analyzed by the laser emission spectroscopic analysis method, a spectroscope having a high wavelength resolution is necessary because iron spectral lines are present in plasma light in a very large number and densely. for that reason,
It is necessary to stabilize the temperature of the spectroscope and its surroundings to ± several ° C. Moreover, in order to operate the detection element stably, it is also necessary to set the ambient temperature to 40 ° C. or lower. Furthermore, vibrations and the like must be sufficiently removed. Such a need also applies to the laser oscillator. However, the inside of the converter is extremely hot, and the inside of the converter is 40 ° C even if the converter is actually covered with a water cooling wall.
It is extremely difficult to maintain the following constant temperature. Also,
The molten steel in the converter is violently flowing, and when part of the equipment is immersed in the molten steel, violent vibration occurs. From such a point, it is easily conceivable that it is impossible to load the entire apparatus into the converter and perform the component analysis.

Further, in a method in which the above-mentioned method is improved and the light collecting tube is expanded or contracted or a long light collecting tube is prepared and only the light collecting tube is loaded into the converter at the time of sampling, the method will be described below. There is a problem.

In this case, since it is not necessary to load the laser oscillator and the spectroscope in the converter, it is possible to control the influence of temperature and vibration countermeasures on them. However, when the laser oscillator and the spectroscope were installed on the converter, the distance from these to the molten steel surface was more than 10 m, and in some cases, 20
The distance is m or more. The outer diameter of the condenser tube is usually about 100 to 10 mm at most due to the restrictions of peripheral equipment. It is easily presumed that such a condenser tube made of steel, for example, will bend when the upper end is fixed and a slight force is applied to the lower end. Moreover, since the atmosphere and the molten steel are violently flowing in the converter, the tip of the condenser tube is bent and vibrates. For example, when the outer diameter of the condenser tube is about 100 mm, the amplitude of this bending vibration exceeds 100 mm. Therefore, it is impossible to transmit the laser light to the center of the condenser lens in the vicinity of the molten steel surface inside the condenser cylinder having a length of 20 m.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a molten metal component analyzer capable of accurately and quickly analyzing a molten metal component.

[0012]

A molten metal component analyzing apparatus according to the present invention is an apparatus for analyzing a molten metal component using a laser emission spectroscopic analysis method, which is provided with a joint portion having a degree of freedom, A laser waveguide that transmits laser light to the sample to irradiate the sample of the molten metal to be analyzed with the laser beam, a water cooling tube that passes the laser waveguide inside, and a laser beam that is generated on the surface of the sample. An optical fiber for propagating the plasma light, and a coupling portion provided in the middle of the laser waveguide and capable of disconnecting and connecting the laser waveguide are provided.

[0013]

In the component analyzer of the present invention, since the transmission direction of the laser light transmitted in the laser waveguide is changed at the joint, it is free to provide such a joint in the middle of the laser waveguide. Laser light can be transmitted in any direction. Also,
The water cooling tube protects the laser waveguide from thermal influences and supports the weight of the laser waveguide.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments thereof by way of example of composition analysis of molten steel.

FIG. 1 is a schematic diagram showing the construction of a laser waveguide and a water cooling tube in a molten metal (molten steel) component analyzer according to the present invention. In the figure, 1 is a water-cooled tube having a laser waveguide 2 inserted therein. The water-cooled tube 1 has a triple wall structure, and a laser waveguide 2 for transmitting laser light and an optical fiber 3 for propagating plasma light pass through the innermost peripheral tube 1a. Further, the intermediate pipe and the outermost peripheral pipe of the water cooling cylinder 1 are water cooling pipes 1b and 1c through which cooling water circulates. The laser waveguide 2 is configured by alternately connecting a tube portion 4 made of, for example, a titanium alloy and a joint portion 5 having a degree of freedom. The length of the water cooling cylinder 1 including the laser waveguide 2 is 22 m. The laser waveguide 2 has six joints 5, and specifically,
12m, 13m, 18m, 19m, 21m, 22 from the top of water cooling cylinder 1
The joint portion 5 is provided at the position m.

FIG. 2 is an enlarged schematic view showing the vicinity of the joint 5. The joint portion 5 located at 13 m, 19 m, and 22 m from the upper portion of the water cooling cylinder 1 is connected to the innermost peripheral wall (inner wall of the water cooling pipe 1 b) 1 d of the water cooling cylinder 1 via a ball bearing 6. The weight of the laser waveguide 2 is supported by this connecting portion. The pipe portion 4 above the connecting portion is composed of two pipes 4a and 4b, and the two pipes 4a and 4b are connected by a linear bearing 7. Thereby, the length of the tube portion 4 can be changed in the long axis direction.

FIG. 3 is a schematic cross-sectional view showing the internal structure of the laser waveguide 1. Adjacent tube sections 4A, 4B and these tube sections 4A,
4B shows the joint portion 5 connected and arranged between the joint portion 4B and 4B. The tube portion 4A and the joint portion 5 are connected via a bearing 8. A rotatable mirror 9 is provided in the joint 5. In the figure, the arrow indicates the optical axis of the transmitted laser light, and the alternate long and short dash line indicates the rotation axes of the tube portion 4B, the joint portion 5 and the mirror 9. Laser light transmission in the laser waveguide 2 will be described with reference to FIG. The laser light transmitted along the central axis in the upstream pipe portion 4A is reflected by the mirror 9 in the joint portion 5. In the joint portion 5, the mirror 9 rotates about a rotation axis that coincides with the incident direction of the laser light, and the reflected laser light is transmitted along the central axis of the downstream pipe portion 4B. In this way, it is possible to change the reflection direction of the laser light by rotating the mirror 9. Therefore, by providing a plurality of joints 5 having such a configuration in the middle of the laser waveguide 2, laser light can be transmitted in any direction.

The laser light is transmitted through the laser waveguide 2 having a degree of freedom, but the laser light must be incident on a condenser lens of several tens of mm after being transmitted for 20 m. Therefore, it is necessary to transmit the laser light with an angle accuracy of 0.03 degrees or less. Therefore, an extra force is applied to the laser waveguide 2, and even if the tube portion 4 is bent even slightly, laser light cannot be transmitted well. Therefore, the tube portion 4 is made of a material having a low thermal expansion coefficient and a low weight (a titanium alloy in the example). However, since the total length of the laser waveguide 2 reaches 20 m, the weight of the laser waveguide 2 itself may cause the tube portion 4 to receive an extra stress. In order to improve this point, in this embodiment, as described above, the joint portions 5 at every two positions are fixed to the water cooling pipe 1b, and the weight of the laser waveguide 2 is supported by the water cooling pipe 1b. .. Thus, the water cooling tube cools the laser waveguide 2 and supports the weight thereof. Also, the water cooling cylinder 1
2 so that stress is not applied to the pipe portion 4 when the pipe is bent.
As shown in, the pipe portion 4 above the connection portion with the water cooling pipe 1b is extendable and contractable in the long axis direction. With the above configuration, in the present invention, laser light can be accurately transmitted to the condenser lens in the curved laser waveguide 2.

FIG. 4 is a schematic diagram showing the overall structure of the spectroscopic analysis device. Reference numeral 11 in the figure indicates an analysis chamber covered with a heat insulating wall. A vibration isolation table 12 for preventing vibration is installed in the analysis room 11, and a laser oscillator 13 for oscillating laser light is installed on the vibration isolation table 12.
A spectroscope 14 for performing spectrum analysis of plasma light is mounted. Laser waveguide 2 and optical fiber 3 are in the analysis room
The laser waveguide 2 is connected to a laser oscillator 13 and the optical fiber 3 is connected to a spectroscope 14 extending to the inside of 11. A coupling 15 that can be disconnected and connected is provided in the middle of the laser waveguide 2 in the analysis chamber 11. The inside of the analysis room 11 is air-conditioned at ± 3 ° C. A paper tube 16 is connected to the lower end of the water cooling cylinder 1.

FIG. 5 is a schematic diagram showing the structure of a sampling means for sampling molten steel. A crucible 18 having an inner diameter of 20 mm and a depth of 30 mm is installed in the paper tube 16 via a heat insulating material 17. A low melting point metal cap 19 is attached to the tip of the paper tube 16. Incidentally, as the structure of the paper tube, only the metal cap may be provided at the tip of the paper tube without providing the crucible so that the molten steel surface is directly dispersed in combination with a device for measuring the height of the molten steel surface. ..

Next, the component analysis operation of molten steel will be described.

The entire apparatus is moved up and down, and the water cooling cylinder 1 is placed in the converter.
Insert. The paper tube 16 is immersed in molten steel, and the molten steel as a sample is sampled by a sampling means. Upon contact with the molten steel, the metal cap 19 melts, the molten steel once flows into the upper part of the sampling means, excess molten steel flows out when the sampling means is removed from the molten steel, and the sample remains in the crucible 16 and the upper surface of the crucible 16 is substantially covered. A consistent sample surface is obtained.

After sampling the sample, the laser oscillator
13 is oscillated, and laser light is transmitted from the laser oscillator 13 into the laser waveguide 1, and as shown by the arrow in FIG.
The sample in 18 is irradiated with laser light. The laser light passes through a condenser lens having a focal length of 1.5 m, for example, at the emission end of the laser waveguide 1 and is condensed to a diameter of about 2 mm on the sample surface. Plasma is generated on the sample surface by the irradiation of the laser light, and the plasma emits the plasma light having the spectral characteristic peculiar to the element. The plasma light is propagated to the spectroscope 14 by the optical fiber 3, the spectrum of the plasma light is analyzed by the spectroscope 14, and the components of the sample (molten steel) are analyzed.

As described above, in the present invention, it is possible to analyze the components of the molten steel in the converter directly or immediately after sampling the sample (molten steel).

Although molten steel is taken as an example in the above-mentioned embodiment, it is needless to say that the component analysis can be similarly performed in the case of other molten metals as well.

[0026]

As described above in detail, in the molten metal component analyzing apparatus of the present invention, a laser waveguide having a plurality of joints having a degree of freedom is used, and a laser for accurate analysis to a remote position is obtained. Since the light is transmitted, the molten metal in the converter can be directly and immediately after being sampled for component analysis, and the molten metal component can be rapidly analyzed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a configuration of a laser waveguide and a water cooling tube in a molten metal component analyzer of the present invention.

FIG. 2 is a schematic diagram showing the vicinity of a joint portion of a laser waveguide in a molten metal component analyzer of the present invention.

FIG. 3 is a schematic cross-sectional view showing an internal configuration of a laser waveguide in the molten metal component analyzer of the present invention.

FIG. 4 is a schematic diagram showing the overall configuration of a molten metal component analyzer of the present invention.

FIG. 5 is a schematic diagram showing a configuration of sampling means in the molten metal component analyzer of the present invention.

[Explanation of symbols]

 1 water cooling tube 1b water cooling tube 1c water cooling tube 2 laser waveguide 3 optical fiber 4 tube section 5 joint section 9 mirror 13 laser oscillator 14 spectroscope 15 coupling 16 paper tube 18 crucible

Claims (1)

[Claims] 1. An apparatus for analyzing a component of a molten metal by using a laser emission spectroscopic analysis method, comprising a joint portion having a degree of freedom, and transmitting a laser beam inside the joint portion to obtain a laser on a sample of the molten metal to be analyzed. A laser waveguide for irradiating light, a water cooling tube for passing the laser waveguide inside, an optical fiber for propagating plasma light generated on the surface of the sample by irradiation of laser light, and a laser waveguide for the laser waveguide. A molten metal component analyzer, comprising: a coupling portion which is provided midway and which allows the laser waveguide to be separated and connected.