Lance tip, refining device, and method of operating a furnace equipped with the same

Abstract

To provide a lance tip capable of continuously measuring the temperature of molten iron, a refining apparatus, and an operation method of a furnace equipped with them.SOLUTION: Lance tips 4, 20, 22, and 24 for lances of a refining apparatus 1 have a camera 9 provided at the central portion of the tip portion for photographing molten iron in a furnace of the refining apparatus 1, flow paths 7, 14, 16, 21, 23, and 25 through which refining gas flows, and sub-discharge holes 15 for refining gas provided around the camera 9. The flow paths 7, 14, 16, 21, 23, 25 are provided with a plurality of branch flow paths 14, 16, 21, 23, 25 branched into a plurality of branches, and at least one branch flow path 16, 21, 23, 25 among the plurality of branch flow paths 14, 16, 21, 23, 25 is connected to the sub-discharge hole 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lance tip used for measuring the temperature of molten iron being blown, a refining apparatus, and a method for operating a furnace equipped with the same. [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) the phosphorus and carbon 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. Measuring the temperature of the molten iron during blowing is important not only for temperature control 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 generated by the refining reaction, and the reaction rate and type of reaction change depending on the temperature of the molten iron. In addition, the use of scrap has increased in recent years, and when room-temperature scrap is added to the furnace, the temperature of the molten iron drops. Due to these circumstances, temperature control of molten steel is becoming increasingly important.

[0004] An example of a technology for measuring the temperature of molten iron is described in Patent Document 1. Patent Document 1 discloses a technology for controlling temperature by taking an image of the 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]

[0005] [Patent Document 1] International Publication No. 2022 / 149490 Summary of the Invention [Problem to be solved by the invention]

[0006] To improve the accuracy of detecting the end point temperature of molten steel, it is necessary to continuously monitor the temperature change of molten steel for at least several minutes in the latter half of the blowing process. In the molten steel temperature measurement technology described in Patent Document 1, when molten steel is splashed by blowing gas from a lance onto the molten steel, the molten steel droplets may adhere to the camera lens. If this occurs, the camera lens becomes unusable. Thus, there is still room for improvement in terms of continuously monitoring the temperature change of molten steel over several minutes.

[0007] The present invention has been made in consideration of the problems of the prior art, and aims to provide a lance tip, a refining apparatus, and a method for operating a furnace equipped with the same, which are capable of continuously measuring the temperature of molten iron. [Means for solving the problem]

[0008] The means for solving the above problems are as follows. (1) A lance tip for a lance of a refining device, the lance tip having a camera provided in the center of the tip for photographing molten iron in the furnace of the refining device, a flow path through which a refining gas flows, and a secondary discharge hole for the refining gas provided around the camera, the flow path having a plurality of branch flow paths branched into a plurality of paths, at least one of the plurality of branch flow paths being connected to the secondary discharge hole. (2) The flow path has one first flow path which is the branch source of some of the branch flow paths among the plurality of branch flow paths, and at least one of the branch flow paths connected to the secondary discharge hole includes a direct branch flow path which branches directly from the first flow path, in a lance tip as described in (1). (3) A lance tip as described in (1), having a main discharge hole through which refining gas is injected or discharged toward the molten iron, the flow path having one first flow path which is the branch source of some of the plurality of branch flow paths, other branch flow paths among the plurality of branch flow paths that are not connected to the secondary discharge hole are connected to the main discharge hole, and the at least one branch flow path connected to the secondary discharge hole includes an indirect branch flow path that is not directly branched from the first flow path but is branched from the other branch flow path and connected to the secondary discharge hole. (4) A lance tip according to any one of (1) to (3), which has a housing for accommodating the camera, and the secondary discharge hole is formed inside the housing. (5) A lance tip according to any one of (1) to (4), in which a space is formed between the tip and the camera. (6) A lance tip according to any one of (1) to (5), having a protrusion formed around the camera at the tip. (7) A lance tip described in any of (1) to (6), wherein the secondary discharge hole has a cylindrical portion formed to surround the camera and a plurality of vertical holes connected to the cylindrical portion. (8) A temperature measuring device for a refining apparatus, comprising the lance tip described in any one of (1) to (7) and a calculation unit that calculates the temperature of the molten iron based on image data of the molten iron photographed by the camera. (9) A refining apparatus equipped with a lance provided with the lance tip described in any one of (1) to (7). (10) A method of operating a furnace, comprising measuring the temperature of the molten iron in the furnace using the temperature measuring device described in (8), and controlling the temperature of the molten iron based on the measured temperature. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent droplets of molten iron from adhering to a camera that photographs the molten iron in a furnace. As a result, the molten iron in the furnace can be continuously photographed by the camera to obtain image data, and the temperature of the molten steel can be continuously measured based on the image data obtained by continuously photographing the molten steel. As a result, it is possible to perform detailed temperature control of the molten steel, and it is possible to improve refining efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of a refining apparatus equipped with a top-blowing lance to which the lance tip of the present invention can be applied. [Figure 2] FIG. 2 is a cross-sectional view of an example of a lance tip of the first embodiment. [Figure 3] FIG. 4 is a diagram showing an example of a sub-discharge hole. [Figure 4] FIG. 10 is a cross-sectional view of an example of a lance tip according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view of an example of a lance tip of a third embodiment. [Figure 6] FIG. 10 is a cross-sectional view of an example of a lance tip according to a fourth embodiment. [Figure 7] FIG. 10 is a perspective view showing an example of the configuration of a camera according to a fourth embodiment. [Figure 8] FIG. 11 is a cross-sectional view of an example of a lance tip according to a fifth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of an example of a lance tip according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (First embodiment) Fig. 1 shows an example of a refining apparatus equipped with a top-blowing lance to which the lance tip of the present invention can be applied. The refining apparatus shown in Fig. 1 can be applied to a blowing process for the purposes of desiliconizing, dephosphorizing, and decarburizing molten iron, and an example thereof is a converter facility. The refining apparatus described above includes a converter 1 made of refractory material for storing molten iron, a top-blowing lance 2 for blowing oxygen gas onto the molten iron stored inside the converter 1, and a bottom-blowing tuyeres 3 installed at the bottom of the converter 1 for blowing nitrogen or the like as a bottom-blowing gas to stir the molten iron.

[0012] A lance tip 4 is attached to the tip of the top-blowing lance 2. The structure of the lance tip 4 will be described later. The top-blowing lance 2 is inserted into and removed from the converter 1 from above by a moving device (not shown). The top-blowing lance 2, for example, has a triple-tube structure, consisting of a central tube (not shown) and two outer tubes (not shown) formed around it. Oxygen gas is supplied to the top-blowing lance 2 from an oxygen gas supply device (not shown), which is part of the converter equipment. The oxygen gas flows through the central tube and is sprayed onto the molten iron through the main discharge hole (described below). Cooling water is supplied to the top-blowing lance 2 from a cooling water supply device (not shown), which is part of the converter equipment. The cooling water circulates between the cooling water supply device and the top-blowing lance 2 through the two outer tubes, cooling the top-blowing lance 2 and the lance tip. In Figure 1, the direction of oxygen gas flow is indicated by the symbol "5," and the direction of cooling water flow is indicated by the symbol "6."

[0013] As described above, the lance tip 4 is attached to the tip of the top-blowing lance 2. FIG. 2 is a cross-sectional view of an example of the lance tip 4 of the first embodiment. The lance tip 4 shown in FIG. 2 is a cylindrical member with approximately the same outer diameter as the top-blowing lance 2, and has a first flow path 7 formed therein through which oxygen gas flows. The first flow path 7 extends in the height direction of the lance tip 4 (the vertical direction in FIG. 2). By attaching the lance tip 4 to the tip of the top-blowing lance 2, the first flow path 7 and the central tube of the top-blowing lance 2 are connected to each other. In addition, a cooling water path (not shown) is formed in communication with the outer tube, and by attaching the lance tip 4 to the tip of the top-blowing lance 2, the outer tube and the cooling water path are connected to each other.

[0014] One end of the lance tip 4 in the height direction shown in Figure 2 (hereinafter referred to as the tip of the lance tip 4) is tapered. A recessed storage section 8 is formed along the central axis of the lance tip 4 in the center of the tip of the lance tip 4 in the radial direction of the lance tip 4. A camera unit (hereinafter referred to simply as the camera) 9 that photographs the molten iron is installed in the storage section 8, and the depth of the storage section 8 is set to be approximately the same as the length of the camera 9 in the example shown in Figure 2. The camera 9 is installed inside the storage section 8 so that a lens (not shown) of the camera 9 faces the molten iron side. The pixel value data of images continuously photographed by the camera 9 (hereinafter referred to as image data) is converted into temperature, and the temperature of the molten iron is continuously measured.

[0015] Returning to the explanation of Fig. 1, the image data generated by the camera 9 is transmitted to the calculation unit 11 via the repeater 10, as shown in Fig. 1. The transmission of the image data from the camera 9 to the repeater 10 and the transmission of the image data from the repeater 10 to the calculation unit 11 may be wired or wireless.

[0016] The calculation unit 11 may be, for example, a general-purpose computer such as a workstation or a personal computer. The calculation unit 11 is configured to convert image data transmitted from the camera 9 into temperature data. Methods for converting image data into temperature data include, for example, a method of acquiring luminance data from the image data and converting the luminance data into temperature data, and a method of acquiring spectral radiance data from the image data and converting the spectral radiance data into temperature data.

[0017] When converting the luminance data into temperature data, the calculation unit 11 obtains, from the acquired image data, for example, an integral value of luminance within a predetermined sampling time or a maximum value of luminance as luminance data. The calculation unit 11 converts the acquired luminance data into temperature data using the correspondence relationship between luminance data and temperature measured in advance using a blackbody furnace.

[0018] On the other hand, the measurement principle of a two-color radiation thermometer (also called a ratio thermometer) can be applied to convert spectral radiance data into temperature data. A two-color radiation thermometer measures radiance at two different wavelengths, calculates their ratio, and compares it with the radiance ratio of a previously measured blackbody to convert it into the temperature of the object. This method allows for relatively stable temperature measurement even when the emissivity fluctuates. When converting spectral radiance data into temperature data using the same principle as a two-color radiation thermometer, the calculation unit 11 acquires spectral radiance data of, for example, red (R) and green (G) based on the three primary colors of red (R), green (G), and blue (B) that are image data, and calculates the radiance ratio from the radiance data. The calculation unit 11 converts the spectral radiance data into temperature data using the correspondence relationship between the intensity ratio of the spectral radiance data and temperature, which has been previously determined using a blackbody radiation furnace or the like.

[0019] When image data from an infrared camera is used, the calculation unit 11 creates brightness data corresponding to the wavelength of infrared light. The calculation unit 11 converts the brightness data into temperature data using the correspondence between the brightness data intensity and temperature, which has been previously investigated using a blackbody radiation furnace or the like. As the brightness data obtained from the image data, data of any wavelength component in the infrared wavelength range can be used, as long as the relationship between the intensity of that wavelength component and temperature is known in advance.

[0020] If the camera 9 is an infrared thermography camera or other device capable of acquiring image data and converting it into temperature data, the calculation unit 11 does not need to have the function of converting image data into temperature data. The calculation unit 11 displays the temperature data on a display unit 12, such as a display. In this way, the surface temperature of the molten iron is continuously measured. The calculation unit 11 may also display the image data transmitted along with the temperature data on the display unit 12. By displaying the image data on the display unit 12 in this way, the temperature of the molten iron in the converter 1 can be measured while observing it, making it possible to determine whether the temperature data represents the temperature of the molten iron or the temperature of the slag formed on the surface of the molten iron. Then, by selectively using the temperature data determined to be the temperature of the molten iron, it is possible to avoid measuring the temperature of the slag, thereby improving the accuracy of measuring the temperature of the molten iron. If the image data is transmitted to another display unit via wireless communication, the display unit 12 may not be provided.

[0021] Returning to the explanation of Figure 2, as shown in Figure 2, at least one main discharge hole 13 through which oxygen gas is sprayed or discharged toward the molten iron is formed at the tip of the lance tip 4. In the case of this embodiment, there are multiple main discharge holes 13, and they are formed on a predetermined circumference centered on the central axis of the lance tip 4, at positions slightly away from the accommodation section 8. Specifically, the main discharge holes 13 are preferably formed, for example, at regular intervals in the circumferential direction of the tip of the lance tip 4. The number of main discharge holes 13 to be provided can be determined, for example, based on the amount of oxygen gas to be sprayed onto the molten iron, the flow rate of the oxygen gas, etc.

[0022] As described above, the main discharge hole 13 is a portion for spraying oxygen gas onto the molten iron. For this purpose, the first flow path 7 is connected to the main discharge hole 13 by the branch flow path 14. In other words, oxygen gas can be injected or discharged from the main discharge hole 13 through the branch flow path 14 branched from the first flow path 7. That is, the first flow path 7 is a flow path for oxygen gas, and also serves as a branch source for some of the branch flow paths (the branch flow path denoted by reference numeral 14 in this specification, and the branch flow paths denoted by reference numerals 16 and 25, which will be described later). In this embodiment, there is only one first flow path 7.

[0023] In the example shown in FIG. 2, the branch flow passage 14 for the main discharge hole 13 is formed in a Laval shape. Therefore, the flow rate of the oxygen gas that flows into the branch flow passage 14 increases, and the oxygen gas is sprayed or discharged from the main discharge hole 13. That is, the branch flow passage 14 for the main discharge hole 13 includes a linear throat portion (constricted portion) 141 and an expanding portion 142 whose inner diameter gradually increases from the throat portion 141 side toward the tip of the lance tip 4. In the example shown in FIG. 2, the throat portion 141 is connected to the outside in the radial direction of the first flow passage 7. Furthermore, the branch flow passage 14 is formed at the tip of the lance tip 4 so that the angle between its central axis and the central axis of the lance tip 4 is an acute angle. That is, the branch flow passage 14 is formed to face slightly outward with respect to the central axis of the lance tip 4. This prevents the oxygen gases injected or discharged from each main discharge hole 13 from joining together and colliding with the molten iron, which would otherwise cause the molten iron to violently scatter. This is to avoid the possibility that splashes of molten iron may adhere to the camera 9, rendering it unusable.

[0024] In order to more effectively prevent droplets of molten iron from adhering to the camera 9, in the first embodiment of the present invention, an air curtain can be formed around the camera 9 by oxygen gas. Specifically, a secondary discharge hole 15 for oxygen gas is formed in the periphery relatively close to the camera 9 at the tip of the lance tip 4 in the radial direction of the lance tip 4. This secondary discharge hole 15 for oxygen gas is provided for the purpose of forming an air curtain, and an air curtain is formed around the camera 9 by the ejection or discharge of oxygen gas from this secondary discharge hole 15. In addition, in the case of this embodiment, the secondary discharge hole 15 is provided between the camera 9 and the main discharge hole 13.

[0025] An example of the auxiliary discharge hole 15 is shown in Figure 3. In this embodiment, the auxiliary discharge hole 15 having the shape shown in Figure 3 is provided in the lance tip 4. The auxiliary discharge hole 15 in Figure 3 includes a cylindrical portion 151 that is circumferentially undivided and surrounds the entire periphery of the camera 9, and a discharge hole group 153 that is a group of multiple vertical holes 152 that are connected to the cylindrical portion 151 and can discharge oxygen gas from the tip of the lance tip 4. The cylindrical portion 151 equalizes the flow rate of oxygen gas provided through the branch flow path 16, which will be described later, and the oxygen gas is distributed to all of the vertical holes 152 in the discharge hole group 153 that are connected to the cylindrical portion 151.

[0026] The vertical holes 152 of the discharge hole group 153 are formed to extend in the height direction of the lance tip 4, and the axial cross section can be, for example, circular. The vertical holes 152 of the discharge hole group 153 may be formed at regular intervals in the circumferential direction of the lance tip 4, or may be formed as continuous circular slits around the entire circumferential direction. The axial direction of the cylindrical portion 151 and the axial direction of the discharge hole group 153 preferably coincide with the axial direction of the top-blowing lance 2. The thickness and height of the cylindrical portion 151, the inner diameter of the vertical holes 152 of the discharge hole group 153, and the number of the vertical holes 152 of the discharge hole group 153 are set to a value that allows oxygen gas to be drawn in from the first flow path 7 to form an air curtain around the camera 9. As a result, an air curtain of oxygen gas can be formed around the camera 9.

[0027] As shown in FIG. 2 , a branch flow path 16 of the auxiliary discharge hole 15, which connects the cylindrical portion 151 of the auxiliary discharge hole 15 and the first flow path 7, is formed between the storage portion 8 and the main discharge hole 13 in the radial direction of the lance tip 4. The branch flow path 16 of the auxiliary discharge hole 15 branches directly from the first flow path 7. The branch flow path 16 extends inward in the radial direction of the lance tip 4 from the connection portion with the first flow path 7, and also extends in the height direction of the lance tip 4 from the connection portion with the first flow path 7 toward the tip of the lance tip 4. The inner diameter (i.e., cross-sectional area) of the branch flow path 16 is set to be approximately the same as the width of the cylindrical portion 151 and smaller than the inner diameters of the first flow path 7 and the throat portion 141. The inclination angle and inner diameter of the branch flow path 16 are set to be sufficient to draw oxygen gas from the first flow path 7 into the branch flow path 16 for the auxiliary discharge hole to form an air curtain around the camera 9. These inclination angle and inner diameter can be determined by design.

[0028] The oxygen gas corresponds to the refining gas in the embodiment of the present invention, and the camera 9, the calculation unit 11, the display unit 12, etc. correspond to the temperature measurement device for the refining apparatus in the embodiment of the present invention. The first flow path 7, the multiple branch flow paths 14, 16, and the branch flow paths 21, 23, 25 described later correspond to the flow paths in the embodiment of the present invention. The branch flow path 16 described above corresponds to the direct branch flow path in this embodiment.

[0029] (Operation of the first embodiment) Once molten iron is poured into the converter 1, the top-blowing lance 2 is inserted into the converter 1 by a top-blowing lance moving device. Oxygen gas is supplied to the top-blowing lance 2 from an oxygen gas supply device, flows through the central tube, and enters the first passage 7 of the lance tip 4 connected to the central tube. The oxygen gas flows through the first passage 7 into the branch passage 14 for the main discharge hole 13, and is sprayed or discharged from the main discharge hole 13 toward the molten iron. Because the branch passage 14 has a Laval shape, the oxygen gas is compressed in the throat section 141 and its flow velocity increases to almost sonic speed. The compressed oxygen gas then expands in the expansion section 142, increasing its flow velocity to almost supersonic speed.

[0030] Furthermore, part of the oxygen gas flows from the first flow path 7 into the branch flow path 16 for the auxiliary discharge hole 15. Because the inner diameter of the branch flow path 16 for the auxiliary discharge hole is set smaller than the inner diameter of the first flow path 7, the oxygen gas is compressed in the branch flow path 16 for the auxiliary discharge hole 15 and its flow rate increases. The oxygen gas is then discharged from the auxiliary discharge hole 15 and expands, increasing its flow rate and forming an air curtain around the camera 9.

[0031] Therefore, according to the first embodiment, even if oxygen gas is injected or discharged from the main discharge port 13 at nearly supersonic speed, causing violent splashes of molten iron at the interface of the molten iron, the splashes collide with the oxygen gas forming the air curtain and are splashed around the camera 9. This makes it possible to prevent splashes of molten iron from adhering to the camera 9. As a result, it is possible to prevent splashes of molten iron from adhering to the camera 9 and rendering the camera 9 unusable.

[0032] (Second embodiment) Fig. 4 is a cross-sectional view of an example of a lance tip according to the second embodiment. The lance tip 20 shown in Fig. 4 is configured to supply oxygen gas to the auxiliary discharge hole 15 via a branch flow path 21 for the auxiliary discharge hole 15 branching from the branch flow path 14 of the main discharge hole 13. Specifically, the branch flow path 21 for the auxiliary discharge hole is connected to a throat portion 141 of the branch flow path 14 of the main discharge hole 13. In other words, the branch flow path 21 does not branch directly from the first flow path 7, from which some of the branch flow paths branch. The branch flow path 21 extends radially inward from the connection with the throat portion 141 of the lance tip 20, and also extends vertically from the connection with the throat portion 141 toward the tip of the lance tip 20.

[0033] The inclination angle and inner diameter of the branch flow path 21 for the auxiliary discharge hole 15 are set to an angle of inclination and inner diameter that allows oxygen gas to be drawn in from the throat portion 141 to form an air curtain around the camera 9. Since other configurations are the same as those shown in Fig. 2, the same components as those shown in Fig. 2 are assigned the same reference numerals as in Fig. 2 and their description will be omitted. The above-mentioned branch flow path 21 corresponds to the indirect branch flow path of this embodiment.

[0034] (Operation of the second embodiment) When oxygen gas flows into the main discharge hole 13, the oxygen gas flows into the auxiliary discharge hole 15 via a branch flow path 21 for the auxiliary discharge hole 15 that is connected to the throat portion 141 of the main discharge hole 13. The inner diameter of the branch flow path 21 is set smaller than the inner diameter of the first flow path 7. Therefore, the oxygen gas is compressed in the branch flow path 21 and its flow rate increases. The oxygen gas is then discharged from the auxiliary discharge hole 15 and expands, further increasing its flow rate, and an air curtain is formed around the camera 9.

[0035] Therefore, even with the lance tip 20 configured as shown in Fig. 4, the air curtain can deflect molten iron droplets flying toward the camera 9 to the periphery of the camera 9, in much the same way as with the lance tip 4 configured as shown in Fig. 2. In this way, the camera 9 can be protected from molten iron droplets. In this way, even with the second embodiment, it is possible to obtain almost the same functions and effects as with the first embodiment.

[0036] (Third embodiment) Fig. 5 is a cross-sectional view of an example of the lance tip 22 of the third embodiment. The example shown in Fig. 5 is configured to supply oxygen gas to the auxiliary discharge hole 142 via a branch flow path 23 for the auxiliary discharge hole 15 branching off from the expanded portion 142 of the main discharge hole 13. Specifically, the branch flow path 23 for the auxiliary discharge hole is connected to the expanded portion 142 of the branch flow path 14 for the main discharge hole 13. The branch flow path 23 for the auxiliary discharge hole 15 extends inward in the radial direction of the lance tip 22 from the connection portion with the expanded portion 142 of the branch flow path 14 for the main discharge hole 13, and also extends toward the tip end of the lance tip 22 from the connection portion with the expanded portion 142 in the height direction of the lance tip 22.

[0037] The inclination angle and inner diameter of the branch flow path 23 are set to an extent that oxygen gas can be drawn from the enlarged portion 142 into the branch flow path 23 for the auxiliary discharge hole 15 to form an air curtain around the camera 9. The inclination angle of the branch flow path 23 is smaller than the inclination angle of the branch flow path 21 in the second embodiment described above. Since the other configurations are the same as those shown in FIG. 2, the same components as those shown in FIG. 2 are denoted by the same reference numerals as in FIG. 2 and their description will be omitted. The branch flow path 23 for the auxiliary discharge hole 15 in the third embodiment corresponds to the multiple branch flow paths and other branch flow paths in the embodiments of the present invention. The above-described branch flow path 23 corresponds to the indirect branch flow path in this embodiment.

[0038] (Operation of the third embodiment) When oxygen gas flows into the main discharge hole 13, the oxygen gas flows into the auxiliary discharge hole 15 via the branch flow path 23 for the auxiliary discharge hole 15, which is connected to the enlarged portion 142 of the branch flow path 14 for the main discharge hole 13. The inner diameter of the branch flow path 23 is set smaller than the inner diameter of the first flow path 7. Therefore, the oxygen gas is compressed in the branch flow path 23 and its flow rate increases. The oxygen gas is then discharged from the auxiliary discharge hole 15 and expands, further increasing its flow rate, and an air curtain is formed around the camera 9.

[0039] Therefore, even with the lance tip 22 configured as shown in Fig. 5, the air curtain can deflect droplets of molten iron scattering toward the camera 9 to the periphery of the camera 9, in much the same way as with the lance tip 4 configured as shown in Fig. 2. This makes it possible to protect the camera 9 from droplets of molten iron. In this way, even with the third embodiment, it is possible to obtain almost the same actions and effects as the above-described embodiments.

[0040] (Fourth embodiment) FIG. 6 is a cross-sectional view of an example of a lance tip 24 according to the fourth embodiment. The example shown in FIG. 6 is an example in which a camera 30 is housed within a housing 29, and a secondary discharge hole 15 and a branch flow path 25 connected to the secondary discharge hole 15 are formed within the housing 29. Oxygen gas is sprayed or discharged from the secondary discharge hole 15 to form an air curtain. FIG. 7 is a perspective view showing an example of the configuration of the camera 30 according to the fourth embodiment. FIG. 7(a) is a perspective view showing an example of the camera 30 housed within the housing 29, and FIG. 7(b) is a perspective view showing an example of each component of the camera 30. Note that in FIG. 7, the branch flow path 25 for the secondary discharge hole 15 is omitted for simplicity. As shown in FIGS. 7(a) and 7(b), the housing 29 is a hollow cylindrical container having a hole for photography at one end of the housing 29 in the longitudinal direction, and the outer diameter of the housing 29 is set to be approximately the same as the inner diameter of the storage section 8. As shown in Figures 7(a) and 7(b), a camera 30 is housed inside the housing 29. The housing 29 is fixed inside the housing portion 8, whereby the camera 30 is attached to the lance tip 28.

[0041] The camera 30 described above is installed at the tip of the top-blowing lance 2 and is therefore exposed to high temperatures. Therefore, in order to efficiently cool the camera 30, it is preferable to configure the housing 29 using a metal material with high thermal conductivity. For example, the housing 29 is preferably made of copper (Cu). Using a copper housing 29 allows efficient heat exchange between the camera 30 and the cooling water flowing inside the top-blowing lance 2 via the housing 29. In this way, the cooling of the camera 30 can be strengthened and the camera 30 can be protected from high heat.

[0042] Here, we will explain the configuration of camera 30. As shown in Figure 7(b), camera 30 has an image sensor 32, a lens 33, two radiant heat blocking filters 34, a fixing ring 35, and a battery 36.

[0043] Image sensor 32 is a sensor that photographs the molten iron and generates image data. Image sensor 32 includes a CCD sensor and a data processing circuit that processes the data generated by the CCD sensor to generate image data. Two radiant heat blocking filters 34 are fixed to a fixing ring 35 on the side of lens 33 that faces the molten iron. The provision of radiant heat blocking filters 34 can suppress temperature increases in lens 33 and image sensor 32 due to radiant heat from the molten iron, thereby suppressing heat-related damage or breakage of lens 33 and image sensor 32. If the two radiant heat blocking filters 34 can be fixed to lens 33 by other means, fixing ring 35 may not be provided. While an example in which image sensor 32 includes a CCD sensor has been shown, this is not limiting, and a CMOS sensor may be used instead of a CCD sensor.

[0044] The radiant heat blocking filter 34 can be one or more of Thorlab's ND filters (models NDUV10B, NDUV20B, and NDUV30B), Thorlab's hot mirror (infrared cut filter) (model M254H00), and Thorlab's bandpass filter (model FL532-1). In the example shown in FIG. 6(b), two radiant heat blocking filters 34 are provided, but this is not limiting. As long as one or more radiant heat blocking filters 34 are provided, it is possible to suppress the temperature rise of the camera 9 due to the radiant heat of the molten iron and to suppress damage or breakage of the camera due to heat.

[0045] Returning to the description of FIG. 6 , as shown in FIG. 6 , a branch flow path 25 for the secondary discharge hole 15 connected to the first flow path 7 is formed inside the housing 29. This branch flow path 25 extends radially inward from its connection with the first flow path 7 of the lance tip 28 and also extends vertically from its connection with the first flow path 7 toward the tip of the lance tip 24. The inner diameter of the branch flow path 25 is set to be smaller than the inner diameter of the first flow path 7. The inclination angle and inner diameter of the branch flow path 25 are set to be sufficient to draw oxygen gas from the first flow path 7 into the branch flow path 25 for the secondary discharge hole 15 and form an air curtain around the camera 9. These inclination angle and inner diameter can be determined by design. Since the other components are similar to those shown in FIG. 2 , the same components as those shown in FIG. 2 are denoted by the same reference numerals as those in FIG. 2 and their description will be omitted. The above-described branch flow path 25 corresponds to the direct branch flow path of this embodiment.

[0046] (Operation of the fourth embodiment) When oxygen gas flows into the main discharge hole 13, the oxygen gas flows into the auxiliary discharge hole 15 via the branch flow path 25 of the branch flow path 25 for the auxiliary discharge hole 15, which is connected to the first flow path 7. The inner diameter of the branch flow path 25 is set smaller than the inner diameter of the first flow path 7. Therefore, the oxygen gas is compressed in the branch flow path 25 and its flow rate increases. Then, the oxygen gas is discharged from each auxiliary discharge hole 15 and expands, which further increases the flow rate, and an air curtain is formed around the camera 30.

[0047] Therefore, even with the lance tip 24 configured as shown in FIG. 6, the air curtain can deflect molten iron droplets flying toward the camera 30 to the periphery of the camera 30, similarly to the lance tip 4 configured as shown in FIG. 2. In this way, the camera 30 can be protected from molten iron droplets. In this way, the fourth embodiment can also achieve substantially the same effects and advantages as the above-described embodiments. Furthermore, in the fourth embodiment, a branch flow path 25 for a secondary discharge hole through which oxygen gas flows is formed inside the housing 29 of the camera 30. This makes it possible to avoid interference with a cooling water path (not shown) for cooling water formed inside the lance tip 24.

[0048] (Fifth embodiment) Fig. 8 is a cross-sectional view of an example of a lance tip 40 of the fifth embodiment. The example shown in Fig. 8 is an example in which the depth of the storage section 8 is set deeper than the length of the camera 9, and the camera 9 is stored inside the storage section 8. Therefore, the tip of the camera 9 is located more inside the lance tip 40 than the tip of the lance tip 40, that is, above the tip of the lance tip 40 in the up-down direction of Fig. 8. In other words, the example shown in Fig. 8 is an example in which a space S is formed between the tip of the lance tip 40 and the tip of the camera 9 in the height direction of the lance tip 40.

[0049] 8, the length h1 between the tip of the camera 9 and the tip of the lance tip 40 is preferably equal to or greater than the diameter d of the camera 9. This allows the camera 9 to be separated from the surface of the molten iron, making it possible to avoid splashes of the molten iron. Since the other components are the same as those shown in FIG. 2, the same components as those shown in FIG. 2 are denoted by the same reference numerals as those in FIG. 2 and their description will be omitted.

[0050] (Operation of the fifth embodiment) When oxygen gas flows into the first flow path 7 of the lance tip 40, the oxygen gas flows into the main discharge hole 13 and the branch flow path 16 for the auxiliary discharge hole 15. Then, as in the first embodiment shown in FIG. 2, the oxygen gas is discharged from the auxiliary discharge hole 15 via the branch flow path 16 for the auxiliary discharge hole 15, forming an air curtain around the camera 9. Therefore, in the fifth embodiment shown in FIG. 8, similarly to the lance tip 4 configured as shown in FIG. 2, the air curtain can repel molten iron droplets scattering toward the camera 9 to the periphery of the camera 9. In this way, the camera 9 can be protected from molten iron droplets. Furthermore, in the fifth embodiment, the tip of the camera 9 is located more inward than the tip of the lance tip 40. Therefore, for example, molten iron droplets scattering approximately perpendicular to the central axis of the lance tip 40, i.e., from the side of the camera 9, can be blocked by the lance tip 40. Therefore, the fifth embodiment can more effectively protect the camera 9 from molten iron droplets compared to the first embodiment.

[0051] (Sixth embodiment) FIG. 9 is a cross-sectional view showing an example of a lance tip 41 according to the sixth embodiment. The example shown in FIG. 9 illustrates a configuration in which protrusions 42 protruding toward the converter 1 are formed around the housing 8 at the tip of the lance tip 41. The protrusions 42 may be formed at regular intervals around the periphery of the housing 8, or may be formed continuously around the entire periphery of the housing 8. The height h2 of the protrusions 42 from the tip of the lance tip 41 is preferably equal to or greater than the diameter d of the camera 9. This allows the camera 9 to be spaced apart from the molten iron surface, thereby blocking splashes of molten iron. A secondary discharge hole 15 is formed radially inside the protrusion 42 of the lance tip 41. Oxygen gas is injected or discharged from the secondary discharge hole 15 to form an air curtain toward the camera 9. Other configurations are similar to those shown in FIG. 2 . Therefore, the same components as those shown in FIG. 2 are designated by the same reference numerals and will not be described further.

[0052] (Operation of the sixth embodiment) When oxygen gas flows into the first flow passage 7 of the lance tip 41, the oxygen gas flows into the main discharge hole 13 and the branch flow passage 16 for the auxiliary discharge hole 15. The oxygen gas is then discharged from each auxiliary discharge hole 15 via the branch flow passage 16 for the auxiliary discharge hole 15. The flow direction of the oxygen gas is guided by the protrusions 42 so that it is aligned along the central axis of the top-blowing lance 2 and the lance tip 41. As a result, compared to the above-described embodiments, the oxygen gas constituting the air curtain is less likely to spread to the surrounding area. Therefore, in the sixth embodiment shown in FIG. 9, the air curtain can more effectively deflect molten iron droplets toward the camera 9 than in the previous embodiments. This allows the camera 9 to be more effectively protected from molten iron droplets. Furthermore, the protrusions 42 can block molten iron droplets that fly approximately perpendicular to the central axis of the lance tip 41, i.e., from the side of the camera 9. Therefore, the camera 9 can be more effectively protected from molten iron droplets than in the previous embodiments.

[0053] In addition, in a refining apparatus 1 using the lance tips 4, 20, 22, 24, 40, 41 and top-blown lance 2 of the first to sixth embodiments, a method of refining by continuously measuring the temperature of molten iron and controlling the temperature of the molten iron corresponds to a furnace operating method according to an embodiment of the present invention. Furthermore, the present invention is not limited to the refining apparatuses of the first to sixth embodiments, i.e., converters. In other words, the lance tips according to the embodiments of the present invention and the top-blown lances equipped with the lance tips can be applied to any refining apparatus that requires top-blowing of gas and temperature control of molten iron. Specifically, the refining apparatus to which the present invention can be applied may be a vacuum degasser (Ruhrstahl-Hausen) or an electric furnace. [Example]

[0054] Next, an example will be described in which the effects of the lance tip according to the present invention were verified. Lance tips configured in substantially the same manner as those in the above-described embodiments were attached to the tip of a top-blowing lance inserted into a converter. A camera attached to the lance tip continuously photographed the molten iron in the converter, and the molten steel temperature was continuously measured based on the photographed image data.

[0055] In experimental condition 1, a lance tip without an air curtain was used. In experimental condition 2, as in the first embodiment, a lance tip 4 capable of drawing in oxygen gas directly from the first flow path 7 through the branch flow path 16 to form an air curtain around the camera 9 was used. In experimental condition 3, as in the second embodiment, a lance tip 20 was used capable of drawing in oxygen gas from the throat portion 141 of the branch flow path 14 connected to the main discharge hole 13 to form an air curtain around the camera 9. In experimental condition 4, as in the third embodiment, a lance tip 22 was used capable of drawing in oxygen gas from the enlarged portion 142 of the branch flow path 14 connected to the main discharge hole 13 to form an air curtain around the camera 9. In experimental condition 5, as in the fourth embodiment, a lance tip 24 was used in which a camera 9 was installed in a housing portion so that the tip of the camera 9 was located a diameter inward from the tip of the lance tip. In experimental condition 6, as in the fifth embodiment, a lance tip 41 was used in which a protrusion 42 was formed around the housing portion 8.

[0056] Considering the industrial use of the lance tips 4, 20, 22, 24, 40, and 41 according to the present invention, it is desirable that the temperature of molten iron can be measured continuously for more than six months (approximately 180 days or more). Therefore, experimental conditions under which the temperature of molten iron could be measured continuously for more than six months were evaluated as passing. In the experimental conditions in which an air curtain was formed around the camera, the injection hole was formed in the lance tip in the shape of a continuous circular slit around the entire circumference. The oxygen gas discharge flow rate at the injection hole was adjusted to 200 m / sec. Table 1 summarizes the experimental conditions and the number of days for which continuous temperature measurement was successful under each experimental condition. The symbols A, B, and C in the "Evaluation" column in Table 1 have the following meanings. A "C" was assigned if the number of days for which continuous temperature measurement was successful was less than the target of 180 days, a "B" was assigned if it was 180 days or more but less than 400 days, and an "A" was assigned if it was 400 days or more. Therefore, a rating of A or B means it is effective, or a pass.

[0057] [Table 1]

[0058] As shown in Table 1, under experimental condition 1, in which no air curtain was formed, a large amount of molten iron droplets adhered to the camera, making it impossible to measure the temperature on the first day after the start of the experiment. In contrast, under experimental conditions 2 to 4, in which an air curtain could be formed around the camera, the temperature of the molten iron could be measured for more than the target period of 180 days. Furthermore, under experimental condition 5, in which a space was formed between the tip of the lance tip and the tip of the camera, and experimental condition 6, in which protrusions were formed around the camera, the number of days for which the temperature of the molten iron could be measured could be extended even further than under experimental conditions 2 to 4.

[0059] From the above results, it was found that when a camera is attached to the lance tip, forming an air curtain around the camera can prevent molten iron droplets from adhering to the camera, making stable, continuous temperature measurement possible. Furthermore, by using the continuous temperature measurement data of molten iron, it is possible to grasp the temperature of molten steel in detail. Furthermore, it is possible to properly manage the temperature of molten iron, such as adjusting the temperature to an appropriate level for the next process, thereby improving the productivity of steel products. [Explanation of symbols]

[0060] 1 Converter 2 Top-blowing lance 3 Bottom-blown tuyere 4 Lance tip of the first embodiment 5. Oxygen flow direction 6 Cooling water flow direction 7 First flow path 8 Storage section 9 Camera 10 Repeater 11 Arithmetic section 12 Display section 13 Main discharge hole 14 Branch flow path (for main discharge hole) 141 throat 142 Enlarged section 15 Sub-discharge hole 151 Cylindrical part 152 Vertical hole 153 Discharge hole group (for sub-discharge holes) 16 Branch flow path (for secondary discharge hole) 20 Lance tip of second embodiment 21 Branch flow path (for secondary discharge hole) 22 Lance tip of the third embodiment 23 Branch flow path (for secondary discharge hole) 24 Lance tip of the fourth embodiment 29 Housing 30 Camera of the fourth embodiment 32 Image Sensor 33 Lens 34 Radiant heat blocking filter 35 Retaining ring 36 Battery 25 Branch flow path (for secondary discharge hole) 40 Lance tip of fifth embodiment 41 Lance tip of the sixth embodiment 42 Protrusion

Claims

1. A lance tip for a lance of a refining device, a camera provided at the center of the tip for photographing molten iron in the furnace of the refining device; a flow path through which a refining gas flows; and a secondary discharge hole for the refining gas provided around the camera, The flow path includes a plurality of branch flow paths branched into a plurality of paths, At least one of the branch flow paths is connected to the secondary discharge hole.

2. the flow path includes one first flow path that is a branch source of some of the branch flow paths among the plurality of branch flow paths, The lance tip according to claim 1 , wherein the at least one branch flow passage connected to the secondary discharge hole includes a direct branch flow passage that branches directly from the first flow passage.

3. a main discharge hole through which a refining gas is injected or discharged toward the molten iron; the flow path includes one first flow path that is a branch source of some of the branch flow paths among the plurality of branch flow paths, Among the plurality of branch flow paths, the other branch flow paths that are not connected to the sub discharge port are connected to the main discharge port, The lance tip according to claim 1, wherein the at least one branch flow path connected to the secondary discharge hole includes an indirect branch flow path that is not directly branched from the first flow path but is branched from another branch flow path and connected to the secondary discharge hole.

4. a housing for accommodating the camera; The lance tip according to claim 1 , wherein the secondary discharge hole is formed inside the housing.

5. The lance tip of claim 1 , wherein a space is formed between the tip and the camera.

6. The lance tip according to claim 1 , further comprising a protrusion formed around the camera at the tip.

7. The lance tip according to claim 1 , wherein the secondary discharge hole comprises a cylindrical portion formed to surround the camera, and a plurality of vertical holes connected to the cylindrical portion.

8. The lance tip according to any one of claims 1 to 7; A temperature measuring device for a refining apparatus, comprising: a calculation unit that calculates the temperature of the molten iron based on image data of the molten iron photographed by the camera.

9. A refining apparatus comprising a lance provided with the lance tip according to any one of claims 1 to 7.

10. The temperature of the molten iron in the furnace is measured by the temperature measuring device according to claim 8, and controlling the temperature of the molten iron based on the measured temperature.

Images