Lance tip, temperature measuring equipment, refining equipment operation method, and molten steel manufacturing method

Abstract

To provide a lance tip, temperature measuring equipment, a method for operating a refining apparatus, and a method for producing molten steel, capable of continuously and accurately measuring the temperature of molten iron in the refining apparatus.SOLUTION: A lance tip 4 is provided at the tip of a lance in a refining apparatus for refining molten iron by injecting blowing gas, which is a blowing gas containing oxygen, from the lance. The lance tip includes a camera 42 for generating image data by photographing molten iron, and a jetting hole 43 provided around the lens of the camera 42 for jetting seal gas.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lance tip, a temperature measuring device, a method for operating a refining device, and a method for producing molten steel. [Background technology]

[0002] In the blowing process of converter steelmaking, a top blowing lance is used to blow oxygen gas onto the molten iron, oxidizing (burning) phosphorus, carbon, etc. in the molten iron to adjust the composition of the molten iron and also adjusting the temperature of the molten iron to an optimum temperature for the next process. In this case, measuring the temperature of the molten iron during processing is important not only for temperature control of the molten iron but also from the perspective of adjusting the composition of the molten iron.

[0003] The temperature of molten iron changes from moment to moment due to the heat of reaction during the refining reaction, and the reaction rate and type of reaction change depending on the temperature of the molten iron.In addition, in recent years, the use of scrap has accelerated in the molten steel manufacturing process, but if scrap is added at room temperature, the temperature of the molten iron will drop, so temperature control of the molten iron is becoming increasingly important.

[0004] As a technique for measuring the temperature of molten iron, Patent Document 1 discloses a technique in which a probe for observing the inside of a furnace, equipped with a CCD camera, is attached to the tip of a sublance, and the sublance is inserted into the furnace to measure the temperature inside the converter.

[0005] Furthermore, Patent Document 2 discloses a technology for measuring the temperature of molten iron by installing a CCD camera at the end opposite to the tip of the main lance and photographing the molten iron through a hole from above the exterior of the lance through which gas is injected.

[0006] Furthermore, Patent Document 3 discloses a technology in which a single-core optical fiber that is small enough not to obstruct the injection of the oxygen jet is installed near the injection nozzle opening of the main lance, and temperature is measured using a monochromatic thermometer connected to the single-core optical fiber.

[0007] Furthermore, Patent Document 4 discloses a technology for controlling temperature by taking an image of molten steel with a camera installed in the center below the lance tip and converting the image into temperature data. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 10-88221 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-126062 [Patent Document 3] Japanese Patent Application Publication No. 62-226025 [Patent Document 4] International Publication No. 2021 / 149490 Summary of the Invention [Problem to be solved by the invention]

[0009] When controlling the temperature of molten steel during blowing based on the measurement results of the molten steel temperature, it is necessary to measure the temperature of molten steel continuously. In particular, when producing molten steel in a converter, it is necessary to continuously grasp the temperature change for at least several minutes in the latter half of the blowing process in order to improve the accuracy of the end point temperature.

[0010] In the technology disclosed in Patent Document 1, the sublance is a device that measures the state inside the furnace intermittently, so there is a problem in that it is not possible to continuously grasp temperature changes, making it difficult to improve the accuracy of the endpoint temperature.

[0011] Furthermore, in the device disclosed in Patent Document 2, the camera is installed at a position 10 m or more away from the object to be measured, which narrows the field of view, making it difficult to determine which position on the surface of the molten iron in the converter is being observed, resulting in problems with measurement accuracy.

[0012] Furthermore, with the technology disclosed in Patent Document 3, only data related to temperature can be obtained from the device, and the temperature measurement position cannot be directly observed. Therefore, there is a possibility that the measured temperature is the temperature of the slag, not the temperature of the molten iron, and there is a problem that the temperature of the molten iron cannot be measured with high accuracy.

[0013] Furthermore, the measurement method disclosed in Patent Document 4 had the problem that when gas was blown from a lance onto molten steel, the molten steel would splash, and the splash would adhere to the camera lens, frequently rendering the camera unusable.

[0014] Therefore, the present invention has been made with an eye on the above-mentioned problems, and aims to provide a lance tip, temperature measuring equipment, a method for operating a refining apparatus, and a method for producing molten steel, which are capable of continuously and accurately measuring the temperature of molten iron in a refining apparatus. [Means for solving the problem]

[0015] (1) According to one aspect of the present invention, in a refining apparatus for refining molten iron by injecting a blowing gas, which is a blowing gas containing oxygen, from a lance, there is provided a lance tip provided at the tip of the lance, the lance tip comprising: a camera that photographs the molten iron and generates image data; and an injection hole provided around the lens of the camera that injects a sealing gas.

[0016] (2) In the lance tip of (1), the flow rate of the seal gas injected from the injection hole is Q [Nm 3 / sec], and the total opening area of the above injection holes is S [m 2 ], Q / S≧200 is satisfied.

[0017] (3) In the lance tip of (2) above, the injection hole has a slit-like shape that surrounds the outer periphery of the lens of the camera.

[0018] (4) In the lance tip of (2) above, the injection holes are arranged on a concentric circle with the lens of the camera at the center and are composed of a plurality of holes surrounding the outer periphery of the lens of the camera.

[0019] (5) In the lance tip of (4) above, when the perimeter of a circle centered on the camera lens and passing through the centers of the multiple holes is L [m], and the edge length, which is the total length of the overlap of the outer periphery of the circle with the multiple holes, is M [m], M / L≧0.5 is satisfied.

[0020] (6) According to one aspect of the present invention, there is provided a temperature measuring device for measuring the temperature of the molten iron in a refining apparatus that performs a refining process on molten iron by injecting a blowing gas, which is a blowing gas containing oxygen, from a lance, the temperature measuring device comprising: a lance tip described in any one of (1) to (5) above; and a computing device that converts image data captured by the camera into temperature data.

[0021] (7) According to one aspect of the present invention, there is provided a method for operating a refining apparatus that performs a refining process of molten iron by injecting a blowing gas, which is a blowing gas containing oxygen, from a lance, and that controls the temperature of the molten iron using the temperature measuring equipment described in (6) above.

[0022] (8) According to one aspect of the present invention, there is provided a method for producing molten steel, in which molten steel is produced by injecting a blowing gas, which is a blowing gas containing oxygen, from a lance in a refining apparatus to perform a refining process on molten iron, and the method for producing molten steel, in which the temperature measuring equipment described in (6) above is used to control the temperature of the molten iron during the refining process, is provided. [Effects of the Invention]

[0023] According to one aspect of the present invention, it is possible to provide a lance tip, temperature measuring equipment, a method for operating a refining apparatus, and a method for producing molten steel, which can continuously and accurately measure the temperature of molten iron in a refining apparatus. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing a refining device according to an embodiment of the present invention. [Figure 2] 1A and 1B are schematic diagrams showing a lance tip, in which (A) is a cross-sectional view and (B) is a bottom view. [Figure 3] FIG. 10 is a bottom view showing a lance tip according to a modified example. [Figure 4] 10 is an explanatory view showing an injection hole of a lance tip in a modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following detailed description, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, identical or similar parts are designated by identical or similar reference numerals, and redundant explanations will be omitted. The drawings are schematic and may differ from the actual product. Furthermore, the embodiments shown below exemplify devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not specify the materials, structure, arrangement, etc. of component parts as described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0026] FIG. 1 shows a schematic diagram of a refining apparatus 1 according to one embodiment of the present invention. In this embodiment, the refining apparatus 1 is a converter-type refining furnace that produces molten steel by blowing molten pig iron. The refining apparatus 1 includes a furnace body 2, a lance 3, and a computing device 5. A lance tip 4 is provided at the tip of the lance 3 for injecting blowing gas 8, which is a blowing gas containing oxygen.

[0027] In the blowing process in the refining equipment 1, after molten pig iron is poured into the furnace body 2, a lance 3 is inserted from the top of the furnace body 2. Next, blowing gas 8 is injected toward the molten pig iron from a lance tip 4 attached to the end of the lance 3, thereby oxidizing and refining the molten pig iron. During this process, various auxiliary materials are added to the molten pig iron in the furnace body 2 as needed, and slag 7 is formed on the surface of the molten pig iron due to oxidation of slag-forming components such as CaO in the auxiliary materials and molten pig iron components. In the blowing process, molten pig iron with a high carbon concentration is oxidized to produce molten steel with a low carbon concentration. The molten pig iron and molten steel are collectively referred to as molten iron 6. The lance 3 has an internal cooling path (not shown) for flowing cooling water, and the lance 3 is cooled by the cooling water flowing through this cooling path during the blowing process.

[0028] As shown in FIG. 2, the lance tip 4 includes a plurality of main holes 41, a camera 42, and an injection hole 43.

[0029] The plurality of main holes 41 are through which the blowing gas containing oxygen supplied through the inside of the lance 3 is injected. The main holes 41 are provided concentrically and at equal intervals on the bottom surface of the lance tip 4. In the example shown in FIG. 2, the lance tip 4 is provided with four main holes 41, for example.

[0030] The camera 42 is provided at the center of the lower part of the lance tip 4. The camera 42 is provided with a lens positioned at the center of the bottom surface of the lance tip 4, with the lens facing downward so as to be able to continuously photograph the molten iron 6 in the furnace body 2. The camera 42 is not particularly limited as long as it is able to continuously photograph the molten iron 6 in the furnace body 2. The photographing results (image data) taken by the camera 42 are transmitted to the computing device 5. The method of transmitting the image data may be either wired or wireless.

[0031] The injection holes 43 are provided around the lens of the camera 42 and are holes through which a seal gas is injected. The seal gas is not particularly limited, and may be, for example, a blowing gas or an inert gas. When blowing gas is used as the seal gas, this can be easily achieved by providing a blowing gas supply path within the lance tip 4 that branches off from the path that supplies the blowing gas to the main hole 41 and is connected to the injection holes 43. When a gas other than blowing gas, such as an inert gas, is used, this can be achieved by providing a supply path within the lance 3 that is separate from the blowing gas supply path.

[0032] The injection hole 43 is preferably provided so as to be able to inject the seal gas while covering the lens of the camera 42. In addition, in a multi-hole lance 3 (a lance having a plurality of main holes 41) provided in a converter as shown in Fig. 2, the injection hole 43 is preferably provided in a region inside the main holes 41 (i.e., toward the center of the lance 3), as indicated by the circular dotted line in the bottom view of Fig. 2(B).

[0033] The blowing gas injected from the main hole 41 of the lance tip 4 is injected at supersonic speed, causing violent splashing at the interface with the molten iron 6. If the scattered splashing adheres to the lens of the camera 42, the camera 42 becomes unusable. In this embodiment, by injecting seal gas from around the lens of the camera 42, the splashing is repelled by the collision pressure of the seal gas before it adheres to the lens, thereby preventing the splashing from adhering to the lens. Furthermore, it is more effective to set the flow path of the seal gas so that it intersects with the path of the splashing toward the lens of the camera 42.

[0034] The injection hole 43 controls the flow rate of the seal gas injected from the injection hole 43 to Q [Nm 3 / sec], and the total opening area of the injection holes 43 is S [m 2], it is preferable that Q / S≧200 be satisfied. Because the splash is a liquid, a high flow velocity is required to repel the splash with a gas having a low density. The speed at which the splash travels toward the lens varies depending on the operating conditions, but under general operating conditions, it is preferable to ensure that the flow velocity of the seal gas is approximately 200 m / sec or more (i.e., Q / S≧200).

[0035] Furthermore, because splashes are scattered toward the lens from various directions, the placement of the injection holes 43 is important. In the example shown in FIG. 2, the injection holes 43 are slits that tightly surround the outer periphery of the lens of the camera 42. Even when the injection holes 43 are directed directly downward, the jets of sealing gas injected from the injection holes 43 tend to attract each other, causing the sealing gas to combine and flow while moving toward the center (directly below the lens). For this reason, the sealing gas is also effective at repelling splashes that fly from directly below the lens of the camera 42.

[0036] The arithmetic device 5 is configured with a computer or the like, and calculates the temperature of the molten iron 6 by converting the image data acquired from the camera 42 into temperature data. The lance tip 4 and the arithmetic device 5 are collectively referred to as temperature measurement equipment. In other words, the temperature measurement equipment according to this embodiment is for measuring the temperature of the molten iron 6 in the refining apparatus 1, and includes the lance tip 4 and the arithmetic device 5 that converts the image data captured by the camera 42 into temperature data. The arithmetic device 5 can determine the temperature of the molten iron 6 from the temperature data. In this case, for example, the maximum temperature from the temperature data or the temperature at a specific position in the image data may be determined as the temperature of the molten iron 6.

[0037] According to this embodiment, the temperature of the molten iron 6 can be continuously measured without splashing onto the temperature-measuring camera 42. Furthermore, by determining the temperature of the molten iron 6 from image data captured by the camera 42, the temperature of the molten iron 6 can be measured with high accuracy. This enables precise temperature control of the molten iron 6, thereby improving refining efficiency. Furthermore, according to this embodiment, in comparison with the method using a sub-lance as in Patent Document 1, continuous measurement is possible and there is no need to replace the measurement probe each time a measurement is performed, thereby reducing running costs. Furthermore, since the lance 3 is cooled by cooling water flowing inside during the blowing process, damage to the camera 42 due to overheating can be prevented.

[0038] <Modification> Although the present invention has been described above with reference to specific embodiments, it is not intended that the invention be limited by these descriptions. By referring to the description of the present invention, other embodiments of the present invention that include various modifications in addition to the disclosed embodiments will be apparent to those skilled in the art. Therefore, it should be understood that the embodiments of the invention set forth in the claims also encompass embodiments that include these modifications described herein, either alone or in combination.

[0039] For example, in the above embodiment, the injection hole 42 is a circumferential slit, but the present invention is not limited to such an example. For example, the injection hole 42 may be a plurality of holes 430 surrounding the outer periphery of the lens of the camera 42, as shown in FIG. 3. In the example shown in FIG. 3, the holes 430 are circular. For simplicity of explanation, FIG. 3 shows only the inner region of the main hole 41 of the lance tip 40 (the circular dotted line region in FIG. 2(B)). The plurality of holes 430 are arranged concentrically and equidistantly spaced apart, with the center of each circle being the lens of the camera 42. As shown in FIG. 4, when the perimeter of a circle (concentric circle) centered on the lens of the camera 42 and passing through the centers of the plurality of holes 430 is L [m], and the edge length, which is the total length of the overlap of the perimeter of this concentric circle with the plurality of holes 430, is M [m], it is preferable that M / L≧0.5 be satisfied. As shown in FIG. 4, the edge length M is the overlapping length between m1 [m] and m 12 [m], the sum of each length (m1+m2+···+m 11 +m 12 ) In Figure 2, the radius of the concentric circles is r [m].

[0040] 3, when the injection hole 43 has a multi-hole shape consisting of a plurality of holes 430, the injected seal gas advances while spreading in the radial direction, so even if there are gaps between the holes 430, the gaps between the jets of seal gas are filled at positions away from the holes 430. However, if the intervals between the holes 430 are too wide, the gaps between the jets may not be filled, so by satisfying M / L≧0.5, the gaps between the jets of seal gas can be filled reliably.

[0041] When the injection hole 43 is a circumferential slit as in the above embodiment, it may be difficult to maintain a constant gap spacing around the entire circumference due to thermal deformation. In such cases, by making the injection hole 43 a multi-hole shape as shown in FIG. 3, it is possible to prevent gaps from being generated in the jet of seal gas. Note that although the hole 430 is circular in the example shown in FIG. 3, the shape of the hole 430 may be other shapes. Furthermore, the injection hole 43 may be a partial slit formed partially around the outer periphery of the lens of the camera 42, rather than around the entire circumference of the lens.

[0042] In the above embodiment, the refining apparatus 1 is a converter-type refining furnace that produces molten steel from molten pig iron, but the present invention is not limited to this example. The refining apparatus 1 may be any apparatus that requires top gas blowing from the lance 3 and temperature control of the molten iron 6, and may be, for example, a vacuum degassing apparatus such as an RH or an electric furnace. Furthermore, the converter-type refining furnace can also be used for the purpose of preliminary treatment such as desiliconization and dephosphorization of molten pig iron.

[0043] Furthermore, the present invention can also be applied to a method for operating a refining apparatus 1 and a method for producing molten steel. A method for operating a refining apparatus 1 according to one aspect of the present invention is a method for operating a refining apparatus that performs a refining process on molten iron 6 by injecting a blowing gas 8, which is a blowing gas containing oxygen, from a lance 3, and controls the temperature of the molten iron 6 using the temperature measuring equipment described in the above embodiment or other modified examples. A method for producing molten steel according to another aspect of the present invention is a method for producing molten steel that produces molten steel by injecting a blowing gas 8, which is a blowing gas containing oxygen, from a lance 3 in a refining apparatus 1 and performs a refining process on the molten iron 6, and controls the temperature of the molten iron 6 using the above temperature measuring equipment during the refining process. [Example]

[0044] Next, an example carried out by the present inventors will be described. In the example, the refining apparatus 1 was a converter-type refining furnace, and a temperature-measuring camera 42 was attached to the lance tip 4 at the tip of the lance 3 of the converter-type refining furnace, and the temperature of the molten iron 6 was continuously measured. Considering process use, it is necessary to be able to continuously measure the temperature for at least 5 days or more, preferably for 50 days or more, and more preferably for six months or more (183 days or more). Therefore, a case where the number of days of successful continuous temperature measurement was 5 or more was evaluated as pass, a result where the number of days of successful continuous temperature measurement was less than 5 was evaluated as fail, a result where the number of days of successful continuous temperature measurement was 5 to 50 was evaluated as pass, a result where the number of days of successful continuous temperature measurement was 50 to 183 was evaluated as good, and a result where the number of days of successful continuous temperature measurement was 183 days or more was evaluated as excellent.

[0045] First, as shown in Figure 2, an experiment was conducted in which the shape of the sealing gas injection hole 43 was a circumferential slit. When no sealing gas was injected (Level 1), a large amount of splash adhered to the lens of the camera 42, making it impossible to measure the temperature after one day. Next, an experiment was conducted in which sealing gas was injected from the injection hole 43. As shown in Table 1, the number of days in which continuous temperature measurement was successful increased as the flow velocity of the sealing gas increased, and continuous temperature measurement was successful for more than six months at flow velocities of 200 m / sec or more.

[0046] [Table 1]

[0047] Next, experiments were conducted by changing the seal gas injection hole 43 to a multi-hole shape consisting of multiple holes 430 as shown in Figure 3. A multi-hole shape has the disadvantage of having more gaps between the seal gas jets than a full-circumferential slit, so a flow velocity of 200 m / sec or more is required. Therefore, experiments were conducted at a flow velocity of 200 m / sec or more. Furthermore, for the multi-hole shape, the ratio M / L of the edge length M to the circumferential length L of the concentric circle mentioned above is a parameter, so the value of M / L was changed between 0.1 and 0.8 (M / L = 1 is a full-circumferential slit).

[0048] The experimental results are shown in Table 2. As M / L increased, the number of days for which continuous temperature measurement was successful increased, and continuous temperature measurement was successful for more than six months at M / L levels of 0.5 or higher. When M / L was set to 0.5 and the flow velocity was slow (levels 14 and 15), the number of days for which continuous temperature measurement was successful fell to less than 183 days, indicating that it is more preferable to ensure a discharge flow velocity of 200 m / sec or higher even in porous shapes.

[0049] [Table 2]

[0050] From the above results, it was found that the temperature measurement method in which the camera 42 is attached to the lance tip 4 allows stable continuous temperature measurement by preventing splash adhesion with sealing gas. It was confirmed that by using the continuous temperature measurement data, it is possible to grasp the temperature of the molten iron in detail, and by performing temperature control such as adjusting the temperature to be suitable for the next process, it leads to improved productivity. [Explanation of symbols]

[0051] 1. Refining equipment 2 Furnace body 3. Lance 4 Lance Chip 41 Main hole 42 Camera 43 Injection hole 430 holes 5 Computing device 6. Molten Iron 7. Slug 8. Blow gas

Claims

1. In a refining apparatus for refining molten iron by injecting a blowing gas containing oxygen from a lance, a lance tip is provided at a tip of the lance, a camera that captures an image of the molten iron and generates image data; an injection hole provided around the lens of the camera and configured to inject a seal gas; Equipped with A lance tip that satisfies Q / S≧200, where Q [Nm 3 / sec] is the flow rate of the seal gas injected from the injection holes and S [m 2 ] is the total opening area of the injection holes.

2. The lance tip according to claim 1 , wherein the injection hole has a slit-like shape surrounding the outer periphery of the lens of the camera.

3. The lance tip according to claim 1 , wherein the injection holes are arranged on a concentric circle with the lens of the camera at the center and are configured by a plurality of holes surrounding the outer periphery of the lens of the camera.

4. A lance tip as described in claim 3, wherein M / L≧0.5 is satisfied when the circumferential length of a circle centered on the camera lens and passing through the centers of each of the multiple holes is L [m] and the edge length, which is the total length of the overlap of the outer periphery of the circle with the multiple holes, is M [m].

5. A temperature measuring device for measuring the temperature of the molten iron in a refining apparatus that performs a refining process of molten iron by injecting a blowing gas containing oxygen from a lance, A lance tip according to any one of claims 1 to 4, a computing device that converts image data captured by the camera into temperature data; Equipped with temperature measurement equipment.

6. A method for operating a refining apparatus that performs a refining process on molten iron by injecting a blowing gas containing oxygen from a lance, the method comprising: A method for operating a refining apparatus, comprising: controlling the temperature of the molten iron using the temperature measuring equipment according to claim 5.

7. A method for producing molten steel, comprising the steps of: injecting a blowing gas containing oxygen from a lance in a refining apparatus to perform a refining process on molten iron to produce molten steel; A method for producing molten steel, wherein the temperature of the molten iron is controlled using the temperature measuring equipment according to claim 5 when the refining treatment is performed.

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