Flow Measurement Systems

Abstract

To measure a flow volume of a molten steel flowing inside a hollow part in a pipe in a non-contact manner with high accuracy.SOLUTION: An exciting coil 210 and a detection coil 220 are arranged while sandwiching a nozzle 160 (a submerged nozzle 163) for surface molten steel in between. A magnetic field is generated from the exciting coil 210 so that it intersects a molten steel flowing inside a hollow part in the nozzle 160 (the submerged nozzle 163) for surface molten steel, wherein the time change of the magnetic field is detected with the detection coil 220 as an induction electromotive force. An arithmetic logical part 400 detects a flow volume of the molten steel flowing inside the hollow part in the nozzle 160 (the submerged nozzle 163) for surface molten steel based on the induction electromotive force.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a flow measurement system, and is particularly suitable for use in measuring the flow rate of molten metal. [Background technology]

[0002] As a method for measuring the flow rate of molten metal, there is a method for measuring directly or indirectly, as described in Patent Document 1. In Patent Document 1, a transmitter coil and a receiver coil are arranged at positions facing each other across a shroud through which the molten metal passes from the ladle to the tundish. A magnetic field is generated in the flow direction of the molten metal from the transmitter coil arranged in this way. The magnetic field generated in the flow direction of the molten metal from the transmitter coil is excited in the molten metal in the shroud, so that a magnetic field is generated from the molten metal in the flow direction of the molten metal. The magnetic field generated in this way from the molten metal in the flow direction of the molten metal is detected by the receiver coil. The presence of slag in the shroud is detected by comparing the induced voltage generated in the receiver coil according to the detected magnetic field with a specified voltage range. In Patent Document 1, the voltage range used in detecting the presence of slag in the shroud in this way is separately set according to the flow rate of the molten metal measured directly or indirectly.

[0003] As described in Patent Document 1, there are methods for measuring the flow rate of molten metal directly or indirectly, but since the area around the molten metal is hot, a technique for measuring the flow rate of molten metal without contact is desired. Patent Document 1 states that the pouring speed in the tundish can be measured and the flow rate of molten metal can be calculated from the measured pouring speed, but does not explain the specific method.

[0004] As a method for non-contact measurement of the flow rate of molten metal, Patent Document 2 discloses a technique for measuring the flow rate of molten steel in a submerged nozzle that supplies molten steel from a tundish in continuous casting into a mold. In Patent Document 2, an excitation coil is used to excite an AC magnetic field that crosses the molten steel flow in an upper nozzle that is located above the sliding nozzle above the submerged nozzle. Then, a detection coil is used to detect a magnetic field in a direction parallel to the flow direction of the molten steel flow. The flow rate of the molten steel flow is derived based on the detected signal. In Patent Document 2, the detection coil is disposed between the excitation coil and the upper nozzle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2006-527089 [Patent Document 2] JP 2018-114548 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 2, a magnetic field perpendicular to the molten steel flow is excited, and the magnetic field generated by the induced current flowing in the molten steel is detected by the detection coil. Therefore, as described in Patent Document 2, if the molten steel flow is a non-filled flow (molten steel does not fill the space in the pipe through which the molten steel flow flows, and the molten steel falls discretely inside the pipe), the measurement accuracy is insufficient. For this reason, the flow rate of the molten steel can only be measured in the area of ​​the upper nozzle where the molten steel flow is considered to be a filled flow. In addition, since the detection coil needs to be placed between the excitation coil and the upper nozzle, the signal level detected by the detection coil is significantly reduced if the excitation coil and the detection coil are placed at a position away from the upper nozzle. In addition, the orientations of the excitation coil and the detection coil differ by 90°, and the detection coil is oriented in a direction parallel to the flow direction of the molten steel flow, so the signal detected by the detection coil is easily affected by noise. For these reasons, the technology described in Patent Document 2 cannot accurately measure the flow rate of the molten metal. The noise referred to here refers to, for example, electromagnetic noise generated from the surroundings and from devices and computers that perform signal processing, excluding the magnetic field and electric signal generated by the excitation coil and detection coil.

[0007] The present invention has been made in consideration of the above problems, and has an object to make it possible to measure the flow rate of molten metal flowing through a hollow portion of a pipe in a non-contact manner with high accuracy. [Means for solving the problem]

[0008] The flow measurement system of the present invention is a flow measurement system for measuring the flow rate of molten metal flowing through a hollow portion of a pipe, and includes an excitation coil that generates a magnetic field so as to intersect with the molten metal flowing through the hollow portion of the pipe, a current supplying means that supplies an AC excitation current to the excitation coil, a detection means that detects a magnetic field generated from the excitation coil when the AC excitation current flows through the excitation coil or a signal based on a time change in the magnetic field, and a flow rate deriving means that derives the flow rate of the molten metal based on the signal detected by the detection means, and the pipe is disposed between the excitation coil and the detection means, and a current supplying means that supplies an AC excitation current to the excitation coil ... Cut magnetic field a magnetic field reaching the detection means located opposite the exciting coil across the tube, of TheIt is characterized by being generated from an excitation coil. Effect of the Invention

[0009] According to the present invention, the flow rate of molten metal flowing through the hollow portion of a pipe can be measured in a non-contact manner with high accuracy. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of continuous casting equipment. [Diagram 2] 1 is a diagram illustrating an example of a configuration of a flow rate measurement system according to a first embodiment. [Diagram 3] FIG. 1 is a diagram showing an example of an outline of the layout of a flow measurement system. [Figure 4] FIG. 2 is a diagram illustrating an example of a detailed arrangement of the flow measurement system according to the first embodiment. [Diagram 5] FIG. 2 is a diagram conceptually illustrating an example of an excitation coil and a detection coil according to the first embodiment. [Figure 6] 3A to 3C are diagrams conceptually illustrating an example of the measurement principle of a flow rate measuring unit according to the first embodiment. [Figure 7] FIG. 11 is a diagram illustrating an example of the configuration of a flow rate measurement system according to a second embodiment. [Figure 8] FIG. 11 is a diagram illustrating an example of a detailed arrangement of a flow measurement system according to a second embodiment. [Figure 9] 10 is a diagram conceptually illustrating an example of an excitation coil and a detection coil according to the second embodiment. FIG. [Figure 10] 10A and 10B are diagrams conceptually illustrating an example of the measurement principle of a flow rate measuring unit according to the second embodiment. [Figure 11] FIG. 13 is a diagram illustrating an example of the configuration of a flow rate measurement system according to a third embodiment. [Figure 12] FIG. 13 is a diagram illustrating an example of a detailed arrangement of a flow measurement system according to a third embodiment. [Figure 13] FIG. 13 is a diagram showing a configuration of a flow rate measurement system according to a first modified example of the third embodiment. [Figure 14]FIG. 13 is a diagram showing details of the arrangement of a flow rate measurement system according to a first modified example of the third embodiment. [Figure 15] FIG. 13 is a diagram illustrating a configuration of a flow rate measurement system according to a second modified example of the third embodiment. [Figure 16] FIG. 13 is a diagram showing details of the arrangement of a flow rate measurement system according to a second modified example of the third embodiment. [Figure 17] FIG. 13 is a diagram illustrating an example of the configuration of a flow rate measurement system according to a fourth embodiment. [Figure 18] FIG. 13 is a diagram showing an example of detailed arrangement of a flow measurement system according to a fourth embodiment. [Figure 19] FIG. 13 is a diagram conceptually illustrating an example of an excitation coil and a detection coil according to the fourth embodiment. [Figure 20] FIG. 4 is a diagram showing an example of the relationship between the flow rate of molten steel and an induced electromotive force. [Figure 21] FIG. 13 is a diagram illustrating an example of a relationship between speed and induced electromotive force. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the fact that the objects to be compared are the same in terms of length, position, size, spacing, etc. includes not only the case where they are exactly the same, but also the case where they are different within the scope of the gist of the invention (for example, different within the tolerance range determined at the time of design). In addition, in each figure, for the convenience of explanation and notation, some of the configuration is simplified or omitted as necessary. In addition, the XYZ coordinates in each figure indicate the relationship of the orientation in each figure. A symbol with a ● in a circle indicates the direction from the back side to the front side of the paper. A symbol with a × in a circle indicates the direction from the front side to the back side of the paper.

[0012] (First embodiment) First, a first embodiment will be described. In this embodiment, a case will be illustrated in which a flow rate of molten steel flowing through a nozzle for supplying molten steel from a tundish to a mold is measured when a multi-layered slab in which the concentration of alloy elements in a surface layer of the slab differs from that in the interior of the slab is cast using continuous casting equipment.

[0013] FIG. 1 is a diagram showing an example of a continuous casting facility to which the flow rate measurement system of the present embodiment is applied. In the present embodiment, the case where the continuous casting facility is the continuous casting facility described in Patent Document 2 is illustrated. Therefore, detailed description of the continuous casting facility is omitted here. Note that the continuous casting facility itself can be realized by a known facility, and the continuous casting facility to which the flow rate measurement system of the present embodiment is applied is not limited to the continuous casting facility described in Patent Document 2.

[0014] In FIG. 1, the continuous casting equipment includes a ladle 110, a component adding device 120, a tundish 130, a mold 140, a nozzle for inner layer molten steel 150, a nozzle for surface layer molten steel 160, a molten steel level gauge 170, an electromagnetic stirrer 181, and an electromagnetic brake 182.

[0015] In this embodiment, a case where molten steel is supplied from one ladle 110 and one tundish 130 is illustrated. A tundish weir 131 having an opening 131a is formed in the tundish 130. The tundish 130 is divided into a first region 130a and a second region 130b by the tundish weir 131. The molten steel supplied into the ladle 110 is supplied to the first region 130a of the tundish 130. In the following description, the molten steel in the first region 130a is referred to as the first molten steel as necessary. The component addition device 120 continuously adds a predetermined element or alloy to the second region 130b of the tundish 130 by a wire or the like. This adjusts the components contained in the molten steel in the second region 130b. In the following description, the molten steel in the second region 130b is referred to as the second molten steel as necessary. In this embodiment, a case in which two types of molten steel (first molten steel and second molten steel) are held in the tundish 130 will be illustrated.

[0016] The nozzle 150 for inner layer molten steel is disposed at the bottom 130c (of the first region 130a) of the tundish 130. The nozzle 150 for inner layer molten steel has a hollow portion, which is connected to the first region 130a of the tundish 130. The nozzle 150 for inner layer molten steel supplies the first molten steel to a relatively lower region in the mold 140. FIG. 1 illustrates a case in which the nozzle 150 for inner layer molten steel supplies the first molten steel to a region below an electromagnetic brake 182, which will be described later.

[0017] The nozzle 160 for surface layer molten steel is disposed at the bottom 130c (of the second region 130b) of the tundish 130. The nozzle 160 for surface layer molten steel has a hollow portion, which is connected to the second region 130b of the tundish 130. The nozzle 160 for surface layer molten steel supplies the second molten steel to a relatively upper region in the mold 140. FIG. 1 illustrates a case in which the nozzle 160 for surface layer molten steel supplies the second molten steel to a region equivalent to the position of an electromagnetic stirrer 181 (described later) in the casting direction (Z-axis direction).

[0018] The molten metal level gauge 170 is a sensor for measuring the molten metal level (position in the casting direction) in the mold 140 . The electromagnetic stirring device 181 is for applying an electromagnetic force to the molten steel (first molten steel) in the mold 140, thereby creating an agitated flow of the molten steel in a horizontal plane (XY plane). The electromagnetic brake 182 applies a DC magnetic field to the molten steel in the mold 140 to reduce the downward flow rate of the molten steel.

[0019] With the above-described continuous casting equipment, a solidified shell solidified in a relatively upper region within the mold 140 is formed as a surface layer portion MS of the cast strand, and a solidified shell solidified in a relatively upper region within the mold 140 is formed as an inner layer portion MI of the cast strand.

[0020] In this embodiment, a case where a flow measurement system is applied to measure the flow rate of the second molten steel flowing inside the surface molten steel nozzle 160 is exemplified. In the following description, the second molten steel will be abbreviated to molten steel as necessary. FIG. 2 is a diagram showing an example of the configuration of the flow measurement system. FIG. 2 is a cross-sectional view taken along line II in FIG. 1. FIG. 3 is a diagram showing an example of an outline of the arrangement of the flow measurement system. FIG. 3 is a cross-sectional view taken along line II in FIG. 2. FIG. 4 is a diagram showing an example of the details of the arrangement of the flow measurement system.

[0021] 2 to 4, the flow rate measurement system has a flow rate measurement unit 200 and a calculation unit 400. The flow rate measurement unit 200 performs measurements to derive the flow rate of molten steel. The calculation unit 400 performs calculations to derive the flow rate of molten steel based on the results of measurements by the flow rate measurement unit 200.

[0022] In this embodiment, the flow rate of molten steel in the hollow portion of the nozzle for surface layer molten steel 160 is to be measured. An example of the configuration of the nozzle for surface layer molten steel 160 will now be described. As shown in FIG. 3, the nozzle 160 for surface layer molten steel has an upper nozzle 161 , a sliding nozzle 162 , and a submerged nozzle 163 .

[0023] The upper nozzle 161 has a hollow portion, which is in communication with an opening in the bottom 130c of the second region 130b of the tundish 130. In this manner, in this embodiment, the molten steel in the second region 130b of the tundish 130 flows into the upper nozzle 161. A sliding nozzle 162 is disposed below the upper nozzle 161, and a submerged nozzle 163 is disposed below the sliding nozzle 162 in a connected manner.

[0024] The sliding nozzle 162 has a plurality of sliding nozzle plates. In this embodiment, the sliding nozzle 162 has three sliding nozzle plates, an upper plate 162a, a center plate 162b, and a lower plate 162c. Each plate has a molten steel passage port, and the area of ​​the opening of the sliding nozzle 162 is changed by fixing the upper plate 162a and the lower plate 162c and sliding the center plate 162b to adjust the positions of the molten steel passage ports of the three plates. This adjusts the injection amount of molten steel. The molten steel whose injection amount has been adjusted by the sliding nozzle 162 is supplied into the mold 140 from the submerged nozzle 163. Note that a stopper may be used instead of the sliding nozzle 162 to adjust the amount of molten steel supplied into the mold 140.

[0025] In the nozzle 160 for surface layer molten steel, the hollow part of the upper nozzle 161 is filled with molten steel. On the other hand, below the upper nozzle 161, for example, in the hollow part of the submerged nozzle 163, the molten steel may not be filled but may flow discretely (with cavities) in the space. In the technology described in Patent Document 2, the measurement accuracy is insufficient when measuring the flow rate of molten steel flowing discretely in the space. For this reason, in the technology described in Patent Document 2, the flow rate of molten steel in the hollow part of the upper nozzle 161 is the measurement target. In contrast, the flow rate measurement system of this embodiment measures the flow rate of molten steel in the hollow part of the submerged nozzle 163. However, the flow rate measurement system of this embodiment may also measure the flow rate of molten steel in the hollow part of the upper nozzle 161. Thus, in this embodiment, the nozzle 160 for surface layer molten steel (submerged nozzle 163) is an example of a pipe through which the molten steel to be measured flows.

[0026] In this embodiment, as shown in Figure 3, an example is shown in which the position of the flow rate measuring unit 200 in the casting direction (Z-axis direction) is determined so that the range (range from the upper end to the lower end) of the flow rate measuring unit 200 in the casting direction (Z-axis direction) is included in the range (range from the upper end to the lower end) of the submerged nozzle 163 in the casting direction (Z-axis direction).

[0027] 2 to 4, the flow rate measuring unit 200 has an excitation coil 210, a detection coil 220, a core 230, and a case 240. The excitation coil 210 and the detection coil 220 are so-called solenoid coils. When an AC excitation current flows through the excitation coil 210, a magnetic field is generated from the excitation coil 210. The excitation coil 210 is a coil that generates a magnetic field that intersects with the molten steel flowing through the hollow part of the nozzle 160 for surface molten steel (submerged nozzle 163). The orientation of the excitation coil 210 is determined so that such a magnetic field is generated. The detection coil 220 detects, as an induced electromotive force, a time change in the magnetic field generated from the excitation coil 210 by the AC excitation current flowing through the excitation coil 210. The orientation of the detection coil 220 is determined so that such a magnetic field can be detected. When a magnetic field penetrates the detection coil 220, an induced electromotive force is generated at both ends of the detection coil 220.

[0028] 2 and 4, in this embodiment, the position of the excitation coil 210 and the detection coil 220 is determined so that the central axis 160a of the nozzle 160 for surface layer molten steel (submerged nozzle 163) is perpendicular to the central axis 210a of the excitation coil 210 and the central axis 220a of the detection coil 220, and the central axis 160a of the nozzle 160 for surface layer molten steel (submerged nozzle 163) intersects with the central axis 210a of the excitation coil 210 and the central axis 220a of the detection coil 220 at one point. It is most preferable that the central axis 160a of the nozzle 160 for surface layer molten steel (submerged nozzle 163) intersects with the central axis 210a of the excitation coil 210 and the central axis 220a of the detection coil 220 at one point, but the central axis 210a of the excitation coil 210 and the central axis 220a of the detection coil 220 may be offset from each other. For example, it is preferable that the amount of deviation between the central axis 210a of the excitation coil 210 and the central axis 220a of the detection coil 220 be on the order of millimeters (less than 10 mm).

[0029] In addition, the nozzle 160 for surface molten steel (submerged nozzle 163) is disposed between the excitation coil 210 and the detection coil 220. Therefore, a magnetic flux based on a magnetic field generated from the excitation coil 210 crosses the nozzle 160 for surface molten steel (submerged nozzle 163) and penetrates the detection coil 220, generating an induced electromotive force in the detection coil 220. In this embodiment, as shown in FIG. 2, a case is illustrated in which a distance Y1 between the excitation coil 210 and the nozzle 160 for surface molten steel (submerged nozzle 163) in the casting thickness direction (Y-axis direction) and a distance Y2 between the detection coil 220 and the nozzle 160 for surface molten steel (submerged nozzle 163) in the casting thickness direction (Y-axis direction) are approximately the same (preferably the same). However, these distances Y1 and Y2 may be different. For example, these distances Y1 and Y2 may be different on the order of millimeters (less than 10 mm).

[0030] Core 230 is made of a soft magnetic material. Fig. 5 is a conceptual diagram showing an example of excitation coil 210 (Fig. 5(a)) arranged to surround core 230 and detection coil 220 (Fig. 5(b)) arranged to surround core 230. 5, in this embodiment, the excitation coil 210 and the detection coil 220 are disposed so as to wind around the core 230. Also, as shown in FIG. 5(a), in this embodiment, the excitation coil 210 has a winding portion, and one turn of the excitation coil 210 is configured by one winding portion. For convenience of notation and explanation, FIG. 5(a) illustrates a case where the number of turns of the excitation coil 210 is one turn, but the number of turns of the excitation coil 210 is appropriately set so that the magnetic field generated by the excitation coil 210 is detected by the detection coil 220.

[0031] As shown in FIG. 5(b), in this embodiment, the detection coil 220 has a winding part, and one winding part constitutes one turn of the detection coil 220. FIG. 5(b) illustrates a case where the number of turns of the detection coil 220 is one for convenience of notation and explanation, but the number of turns of the detection coil 220 is appropriately set so that the magnetic field generated by the excitation coil 210 is detected by the detection coil 220. In FIG. 5(a), one end and the other end of the excitation coil 210 are connected to an AC power source (waveform generator 401 and power amplifier 402), so that the excitation current winds around the winding part of the excitation coil 210. In FIG. 5(b), one end and the other end of the detection coil 220 are connected to a voltmeter (lock-in amplifier 403), so that the current corresponding to the induced electromotive force winds around the winding part of the detection coil 220.

[0032] In this embodiment, as shown in Fig. 2 and Fig. 4, the core 230 has a first portion 230a, a second portion 230b, and a third portion 230c. The excitation coil 210 goes around the first portion 230a. The detection coil 220 goes around the second portion 230b. The third portion 230c is magnetically connected to the first portion 230a and the second portion 230b, and is arranged to go around the surface molten steel nozzle 160 (submerged nozzle 163). The third portion 230c is magnetically connected to the first portion 230a and the second portion 230b, which means that a magnetic path is formed between the third portion 230c and the first portion 230a and the second portion 230b.

[0033] In this embodiment, as shown in Figures 2 to 4, the first portion 230a and the second portion 230b have a rectangular parallelepiped shape. Also, the tip surfaces of the first portion 230a and the second portion 230b are planes that are substantially parallel to a plane determined by the casting direction (Z-axis direction) and the casting width direction (X-axis direction) and face the direction of the nozzle 160 for surface layer molten steel (submerged nozzle 163) (i.e., the tip surfaces of the first portion 230a and the second portion 230b face each other with the nozzle 160 for surface layer molten steel (submerged nozzle 163) between them). At this time, it is preferable that the deviation amount of each axis between the central axis of the tip surface of the first portion 230a (a line passing through the center of gravity of the tip surface of the first portion 230a and perpendicular to the tip surface) and the central axis of the tip surface of the second portion 230b (a line passing through the center of gravity of the tip surface of the second portion 230b and perpendicular to the tip surface) is on the order of millimeters (less than 10 mm). In addition, in this embodiment, as shown in Figs. 2 to 4, a case where the third portion 230c has a hollow rectangular parallelepiped shape is illustrated. In addition, a case where the central axis of the third portion 230c and the central axis 160a of the nozzle 160 for surface molten steel (submerged nozzle 163) approximately coincide with each other is illustrated. It is preferable that the deviation amount of each axis between the central axis of the third portion 230c and the central axis 160a of the nozzle 160 for surface molten steel (submerged nozzle 163) is on the order of millimeters (less than 10 mm).

[0034] Furthermore, the core 230 has a shape that is line-symmetrical with respect to a virtual straight line that passes through the central axis of the core 230 (the third portion 230c) and extends in the casting thickness direction (Y-axis direction). The core 230 has a shape that is line-symmetrical with respect to a virtual straight line that passes through the central axis of the core 230 (the third portion 230c) and extends in the casting width direction (X-axis direction). Therefore, the base end faces of the first portion 230a and the second portion 230b are disposed on the inner peripheral surface of the third portion 230c so that the core 230 has such a shape. In this embodiment, as shown in Figs. 2 to 4, a case is illustrated in which the first portion 230a, the second portion 230b, and the third portion 230c are integrated and cannot be separated. That is, in FIG. 4, for convenience of notation and explanation, the boundary between the first portion 230a and the third portion 230c, and the boundary between the second portion 230b and the third portion 230c are shown by dashed lines, but in reality, such boundary lines do not exist.

[0035] The case 240 is made of a heat insulating material and is intended to prevent the excitation coil 210, the detection coil 220, and the core 230 from being overheated by radiant heat from the molten steel. The case 240 is preferably made of a non-magnetic and non-metallic (preferably insulating) material. The excitation coil 210, the detection coil 220, and the core 230 configured as described above are housed inside the case 240. A cooling medium (dry air, etc.) may be supplied from the outside of the case 240 to the inside toward the excitation coil 210, the detection coil 220, and the core 230. In this case, for example, a flow of the cooling medium circulating in a direction (XY plane) perpendicular to the casting direction (Z-axis direction) may be formed in the hollow area inside the case 240 shown in FIG. 2. For example, one or more through holes may be formed in a partial area of ​​the side of case 240, pipes that serve as a path for the cooling medium may be attached to the through holes, and a fan or blower may be attached to the pipes, thereby forming a flow of cooling medium that circulates in a direction perpendicular to the direction in which molten steel flows in the hollow area inside case 240 shown in FIG. 2.

[0036] Fig. 6 is a diagram conceptually illustrating an example of the measurement principle of the flow rate measuring unit 200. In Fig. 6, arrows indicate magnetic field lines. Fig. 6(a) is a diagram for explaining the magnetic field H (magnetic flux Φ) when no molten steel (molten metal) is present. In Fig. 6(a), when an AC excitation current flows through excitation coil 210, a magnetic field H (magnetic flux Φ) is generated from excitation coil 210 according to Ampere's law (right-hand rule). The magnetic flux density B corresponding to the magnetic field H generated at this time is high near the central axis of excitation coil 210. In Fig. 6, this is represented by shortening the interval between the arrows.

[0037] In FIG. 6(a), since there is no molten steel (molten metal) between the excitation coil 210 and the detection coil 220, the magnetic field H (magnetic flux Φ) generated from the excitation coil 210 moves toward the detection coil 220 without being affected by the molten steel. In FIG. 6(a), for the sake of simplicity, it is assumed that the magnetic field H (magnetic flux Φ) generated from the excitation coil 210 all advances in the casting thickness direction (Y-axis direction). By using the core 230, it is possible to suppress the spatial spread of the magnetic field H (magnetic flux Φ) generated from the excitation coil 210. Therefore, it is possible to limit and homogenize the area in which the magnetic field H (magnetic flux Φ) is generated. The magnetic field H (magnetic flux Φ) generated from the excitation coil 210 penetrates the detection coil 220. As a result, an induced electromotive force is generated at both ends of the detection coil 220 according to Faraday's law of electromagnetic induction.

[0038] 6(b) is a diagram for explaining the magnetic field H (magnetic flux Φ) when molten steel (molten metal) with a flow velocity of 0 (zero) is present. As in the case shown in FIG. 6(a), when an AC excitation current flows through excitation coil 210, a magnetic field H (magnetic flux Φ) is generated from excitation coil 210. In FIG. 6(b), since molten steel (molten metal) is present between excitation coil 210 and detection coil 220, eddy current I flows in the molten steel to cancel out the magnetic field H according to Lenz's law. e Therefore, the magnetic field H (magnetic flux Φ) reaching the detection coil 220 is smaller than in the case shown in Fig. 6(a). In Fig. 6(b), this is indicated by the arrow line indicating the magnetic field H (magnetic flux Φ) being shown by a dashed line.

[0039] FIG. 6(c) is a diagram for explaining the magnetic field H (magnetic flux Φ) when there is molten steel (molten metal) flowing in the direction of casting progress (negative direction of the Z axis (direction of the outline arrow)). As in the cases shown in FIGS. 6(a) and 6(b), when an AC excitation current flows through excitation coil 210, a magnetic field H (magnetic flux Φ) is generated from excitation coil 210. Also, as in the case shown in FIG. 6(b), eddy currents I e In Fig. 6(c), the molten steel flows in the direction of the molten steel flow (negative direction of the Z axis). The eddy current I e is dragged (slightly) in the direction of the flow of the molten steel (negative direction of the Z axis) by the flow of the molten steel. In this way, the eddy current I e As the magnetic field H (magnetic flux Φ) is dragged in the direction of the molten steel flow (negative direction of the Z axis), the magnetic field H (magnetic flux Φ) is also dragged in the direction of the molten steel flow (negative direction of the Z axis).

[0040] Here, the induced electromotive force V generated at both ends of the detection coil 220 is proportional to the time change (dΦ / dt) of the magnetic flux Φ penetrating the detection coil 220, so if the proportionality coefficient is α, the relationship V=αdΦ / dt holds. In addition, the eddy current I e And since the amount of deviation z (in the flow direction of the molten steel (negative direction of the Z-axis)) of the magnetic field H (magnetic flux) is proportional to the flow velocity v of the molten steel, the magnetic flux Φ penetrating the detection coil 220 is also proportional to the flow velocity v of the molten steel. Therefore, as shown in FIG. 6(c), the eddy current I e The magnetic field H (magnetic flux Φ) penetrating the detection coil 220 decreases according to the deviation z of the magnetic field H (magnetic flux). e The amount of deviation z of the magnetic field H (magnetic flux) is proportional to the magnetic field H (magnetic flux Φ) that penetrates the detection coil 220. In FIG. 6(c), this is shown by the dashed arrow at the bottom not penetrating the detection coil 220. As described above, the eddy current I due to the flow of molten steel e And because the deviation z of the magnetic field H (magnetic flux) and the flow velocity v of the molten steel are in a proportional relationship, the magnetic flux Φ penetrating the detection coil 220 is also in a proportional relationship with the flow velocity v of the molten steel (Φ can be approximated by a linear function of v). Therefore, the induced electromotive force V generated across both ends of the detection coil 220 is expressed as V=αdΦ(v) / dt, where α is the proportionality coefficient.

[0041] In FIG. 4, a calculation section 400 includes a waveform generator 401 , a power amplifier 402 , a lock-in amplifier 403 , and a computer 404 . The waveform generator 401 generates a sine wave. The power amplifier 402 is, for example, a constant current amplifier, which amplifies the sine wave generated by the waveform generator 401 to generate an excitation current, and supplies the excitation current to the excitation coil 210. Here, it is preferable that the excitation frequency (frequency of the excitation current) is a frequency other than the commercial frequency. This is because it is possible to suppress signals generated by other electric devices driven by the commercial frequency from being detected as noise by the detection coil 220. In addition, from the viewpoint of improving the S / N ratio, it is preferable that the excitation frequency is a frequency higher than the commercial frequency, but it may be a frequency lower than the commercial frequency. For example, an AC current with a frequency of 30 Hz and an effective value of 1 A can be used as the excitation current. In this embodiment, an example of a current supply means is realized by using the waveform generator 401 and the power amplifier 402.

[0042] The signal of the induced electromotive force detected by the detection coil 220 is input to a filter. The filter removes unwanted band noise signals contained in the signal of the induced electromotive force detected by the detection coil 220. For example, a low-pass filter can be used as the filter. For example, a low-pass filter with a cutoff frequency of 40 Hz can be used. However, the filter is not limited to a low-pass filter. For example, a band-pass filter can be used. Since the signal of the induced electromotive force detected by the detection coil 220 is a time change of a magnetic field, there is a phase difference of -90° between the magnetic field excited by the excitation coil 210 and the induced electromotive force detected by the detection coil 220. Therefore, the lock-in amplifier 403 detects a component of the signal that has passed through the filter, the component having a phase shift of -90° with respect to the excitation current to the excitation coil 210. This reference phase signal for detection is supplied from the waveform generator 401 to the lock-in amplifier 403. For example, only a frequency component of 30 Hz is detected by the lock-in amplifier 403. The signal after detection by the lock-in amplifier 403 becomes a flow velocity original signal that is the basis for flow velocity measurement. The flow velocity original signal is sent to a computer 404 as a calculation device. The computer 404 derives the flow velocity of the molten steel flowing through the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) based on the flow velocity original signal. The computer 404 then derives the flow rate of the molten steel based on the flow rate of the molten steel flowing through the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) and outputs information on the flow rate of the molten steel. The form of output includes at least one of, for example, display on a computer display, transmission to an external device, and storage in a storage medium inside or outside the computer 404. In this embodiment, an example of a flow rate derivation means is realized by using the lock-in amplifier 403 and the computer 404.

[0043] The flow velocity of the molten steel flowing through the hollow portion of the nozzle 160 for surface molten steel (submerged nozzle 163) is derived, for example, as follows. As described above, there is a relationship of V=αdΦ(v) / dt. Therefore, a flow velocity original signal (induced electromotive force) V is derived when the flow velocity v is changed by performing a simulation or a numerical simulation, and based on a set of the derived flow velocity v and the flow velocity original signal (induced electromotive force) V, a regression analysis or the like is performed utilizing the relationship of V=αdΦ(v) / dt and the fact that Φ is a linear function of v, to determine the coefficients and constants of the function Φ(v) and the proportionality coefficient α. The proportionality coefficient α may be included in the function Φ(v). For example, the computer 404 applies the flow velocity original signal to V of V=αdΦ(v) / dt to derive the flow velocity v. When deriving the flow velocity v as described above, it is preferable to use the flow velocity original signal obtained when no molten steel is present in the hollow portion of the nozzle 160 for surface molten steel (submerged entry nozzle 163) as a reference signal (a signal corresponding to a reference voltage (0 (zero) voltage)). In this case, the value obtained by subtracting the reference signal from the flow velocity original signal corresponds to V in V=αdΦ(v) / dt.

[0044] The flow rate of the molten steel flowing through the hollow portion of the surface layer molten steel nozzle 160 (submerged nozzle 163) is derived, for example, as follows. The volumetric flow rate of the molten steel flowing through the hollow portion of the nozzle 160 for surface layer molten steel (submerged nozzle 163) is derived by multiplying the flow velocity of the molten steel flowing through the hollow portion of the nozzle 160 for surface layer molten steel (submerged nozzle 163) by the cross-sectional area assumed as the cross-sectional area of ​​the molten steel in a direction perpendicular to the flow direction. The mass flow rate of the molten steel flowing through the hollow portion of the nozzle 160 for surface layer molten steel (submerged nozzle 163) is derived based on the volumetric flow rate of the molten steel flowing through the hollow portion of the nozzle 160 for surface layer molten steel (submerged nozzle 163) and the density of the molten steel. The flow rate of the molten steel may be a volumetric flow rate or a mass flow rate.

[0045] The cross-sectional area assumed as the cross-sectional area of ​​the molten steel in the direction perpendicular to the flow direction is determined, for example, as follows. When the molten steel flowing through the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) fills the hollow part, the cross-sectional area of ​​the hollow part of the submerged nozzle 163 (in the direction perpendicular to the central axis of the submerged nozzle 163) can be set as the cross-sectional area assumed as the cross-sectional area of ​​the molten steel in the direction perpendicular to the flow direction. On the other hand, when the molten steel flowing through the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) flows discretely within the hollow part, for example, the cross-sectional area of ​​the molten steel flowing through the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) when the area of ​​the opening of the sliding nozzle 162 and the change in mass of the molten steel in the tundish 130 per unit time are made different from each other is derived, for example, from actual slab production data. Then, the relationship between the area of ​​the opening of the sliding nozzle 162, the amount of change in mass of the molten steel in the tundish 130 per unit time, and the cross-sectional area of ​​the molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163) is derived by performing regression analysis or the like. Thereafter, the amount of change in mass of the molten steel in the tundish 130 per unit time is measured, and the area of ​​the opening of the sliding nozzle 162 is obtained. From the relationship derived as described above, the cross-sectional area of ​​the molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163) is derived as a cross-sectional area assumed to be the cross-sectional area of ​​the molten steel in a direction perpendicular to the flow direction. Although the shape of the cross section of the actual molten steel may be significantly deformed, the cross-sectional area derived in this manner is sufficient on average for the production of slabs over a long period of time.

[0046] As described above, in this embodiment, the excitation coil 210 and the detection coil 220 are arranged with the nozzle for surface layer molten steel 160 (submerged nozzle 163) between them. The excitation coil 210 generates a magnetic field that intersects with the molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163), and the detection coil 220 detects the time change of the magnetic field as an induced electromotive force. The calculation unit 400 derives the flow rate of molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163) based on the induced electromotive force. Therefore, the flow rate of molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163) can be measured in a non-contact manner with high accuracy.

[0047] For example, compared to Patent Document 2, even if the excitation coil 210 and the detection coil 220 are moved away from the nozzle 160 for surface molten steel (submerged nozzle 163), the signal strength of the induced electromotive force can be suppressed from decreasing. As a result, compared to Patent Document 2, it is not necessary to enlarge the device in order to increase the signal strength of the induced electromotive force. Therefore, the burden of operation due to the enlargement of the device can be reduced. For example, it is possible to suppress the narrowing of the working space due to the enlargement of the device. Furthermore, even if the hollow part of the submerged nozzle 163 is not filled with molten steel and flows discretely in the space (with cavities), the flow rate of molten steel flowing through the hollow part of the nozzle 160 for surface molten steel (submerged nozzle 163) can be measured with high accuracy compared to Patent Document 2. Furthermore, compared to Patent Document 2, the influence of noise contained in the signal of the induced electromotive force can be reduced.

[0048] In addition, in this embodiment, the excitation coil 210 and the detection coil 220 are wound around the core 230. Therefore, the magnetic field generated from the excitation coil 210 can be easily made to reach the detection coil 220. Specifically, in this embodiment, the core 230 has a first portion 230a in which the excitation coil 210 is arranged, a second portion 230b in which the detection coil 220 is arranged, and a third portion 230c that is magnetically connected to the first portion 230a and the second portion 230b and arranged to orbit (surround) the nozzle for surface layer molten steel 160 (submerged nozzle 163). Specifically, in this embodiment, the third portion 230c has a cross section in a plane perpendicular to the casting direction (Z-axis direction) that is closed around the nozzle for surface layer molten steel 160 (submerged nozzle 163). Therefore, by suppressing the spatial spread of the magnetic field H (magnetic flux) generated from the excitation coil 210, the region in which the magnetic field H (magnetic flux Φ) is generated can be limited and made uniform. Therefore, the magnetic field H (magnetic flux Φ) can be made to reach the detection coil 220 more easily, and the influence of noise contained in the induced electromotive force signal can be further reduced. In addition, the magnetic field H (magnetic flux Φ) leaking to the outside can be reduced, so that adverse effects on the outside can be suppressed.

[0049] Furthermore, in this embodiment, the detection coil 220 has a winding portion, and one winding portion constitutes one turn of the detection coil 220. Therefore, the configurations of the detection coil 220 and the core 230 can be simplified.

[0050] <Modification> <<First Modification>> In this embodiment, the case where the core 230 is used has been exemplified. However, it is not essential to use the core 230. As the excitation coil 210 and the detection coil 220, for example, an air-core type coil in which a coil is wound around a ceramic bobbin may be used.

[0051] <<Second Modification>> In the present embodiment, the case where the detection coil 220 is used has been exemplified. However, the detector for detecting the magnetic field or the change over time in the magnetic field is not limited to the detection coil 220. For example, other magnetic sensors such as a Hall element may be used as the detector.

[0052] <<Third Modification>> In this embodiment, the process for deriving the flow rate of molten steel is performed by software on the computer 404. However, this is not necessarily required. For example, the process may be performed by using hardware (e.g., a suitable analog circuit) instead of software. <<Fourth Modification>> In this embodiment, the case where the lock-in amplifier 403 is used to detect the signal from the detection coil 220 has been exemplified. However, this is not necessarily required. For example, a synchronous detector or the like may be used to detect the component of the signal having the desired phase.

[0053] <<Fifth Modification>> In the present embodiment, the case where the flow rate of molten steel in the nozzle for surface layer molten steel 160 is to be measured has been exemplified. However, the flow rate of molten steel may be the flow rate of molten steel in the nozzle for inner layer molten steel 150. Furthermore, the flow rate measuring system may be applied to each of the nozzle for inner layer molten steel 150 and the nozzle for surface layer molten steel 160.

[0054] <<Sixth Modification>> In this embodiment, the flow rate detection system is applied to a continuous casting facility that continuously casts a multi-layered slab in which the concentration of alloy elements in the surface layer of the slab is different from that in the interior of the slab. However, the application of the flow rate measurement system is not limited to this, as long as the flow rate of molten metal flowing through the hollow part of the tube can be measured. For example, the flow rate detection system of this embodiment may be applied to a continuous casting facility that has one nozzle (submerged nozzle) that injects molten steel from a tundish into a mold.

[0055] <<Seventh Modification>> In this embodiment, the third portion 230c of the core 230 has a hollow rectangular parallelepiped shape. However, the shape of the third portion of the core is not limited to a hollow rectangular parallelepiped shape. For example, the third portion of the core may have a hollow concave shape. In this case, the third portion of the core has a shape that excludes the region on the positive side of the X-axis from the first portion 230a and the second portion 230b, for example, with respect to the third portion 230c shown in FIG. 2.

[0056] Second embodiment Next, a second embodiment will be described. In the first embodiment, a case where one turn of the detection coil 220 is formed by one winding part is exemplified. In contrast, in the present embodiment, a case where one turn of the detection coil is formed by two winding parts, a first winding part and a second winding part, is described. As described above, the present embodiment and the first embodiment differ mainly in the configuration and processing due to the difference in the configuration of the detection coil. Therefore, in the description of this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in Figs. 1 to 6, and detailed description thereof will be omitted.

[0057] In this embodiment, a case where a flow rate measurement system is applied to the continuous casting equipment shown in the first embodiment is also illustrated. Fig. 7 is a diagram showing an example of the configuration of the flow rate measurement system. Fig. 7 is a diagram corresponding to Fig. 2. Fig. 8 is a diagram showing an example of the detailed arrangement of the flow rate measurement system. Fig. 8 is a diagram corresponding to Fig. 4.

[0058] 7 and 8, the flow rate measurement system has a flow rate measurement unit 700 and a calculation unit 400. As in the first embodiment, the flow rate of molten steel in the hollow portion of the submerged nozzle 163 is measured in this embodiment. However, as in the first embodiment, the flow rate measurement system of this embodiment may also measure the flow rate of molten steel in the hollow portion of the upper nozzle 161.

[0059] As in the first embodiment, this embodiment also illustrates an example in which the position of the flow rate measuring unit 700 in the casting direction (Z-axis direction) is determined so that the range (range from the upper end to the lower end) of the flow rate measuring unit 700 in the casting direction (Z-axis direction) is included in the range (range from the upper end to the lower end) of the submerged nozzle 163 in the casting direction (Z-axis direction) (see Figure 3).

[0060] The flow rate measuring unit 700 includes an excitation coil 210 , a detection coil 720 , a core 730 , a spacer 740 , and a case 240 . The excitation coil 210 and the case 240 are the same as those described in the first embodiment. The detection coil 720 is a so-called solenoid coil. Fig. 9 is a conceptual diagram showing an example of an excitation coil 210 (Fig. 9(a)) arranged so as to surround a core 730, and a detection coil 720 (Fig. 9(b)) arranged so as to surround the core 730.

[0061] 9(a) and 9(b), this embodiment illustrates a case where the excitation coil 210 and the detection coil 720 are arranged to wind around the core 730. Also, as in the first embodiment, this embodiment illustrates a case where the excitation coil 210 has a winding portion, and one turn of the excitation coil 210 is composed of one winding portion, as shown in FIG.

[0062] As shown in FIG. 9B, in this embodiment, the detection coil 720 has a first winding part 721 and a second winding part 722. One turn of the detection coil 720 is composed of one first winding part 721 and one second winding part 722 connected to the first winding part 721. For convenience of notation and explanation, FIG. 9B illustrates a case where the number of turns of the detection coil 720 is one turn, but the number of turns of the detection coil 720 is appropriately set so that the magnetic field generated by the excitation coil 210 is detected by the detection coil 220. The one-turn part of the detection coil 720 has a shape obtained by twisting the one-turn part of the detection coil 220 of the first embodiment into the shape of an Arabic numeral 8 as a whole.

[0063] Therefore, the first winding part 721 and the second winding part 722 are connected so that the direction of the current flowing through the first winding part 721 and the direction of the current flowing through the second winding part 722 are opposite to each other when a magnetic flux of the same direction penetrates the first winding part 721 and the second winding part 722 at the same time. In the example shown in FIG. 9(b), when a magnetic flux Φ from the back side to the front side of the paper penetrates the first winding part 721 and the second winding part 722 at the same time, the direction of the current flowing through each of the first winding part 721 and the second winding part 722 is indicated by an arrow line next to the detection coil 720. As shown in FIG. 9(b), the direction of the current flowing through the first winding part 721 and the direction of the current flowing through the second winding part 722 are opposite to each other. Therefore, when the amount of magnetic flux penetrating the first winding portion 721 and the second winding portion 722 in the same direction at the same time is the same, the current flowing through the first winding portion 721 and the current flowing through the second winding portion 722 completely cancel each other out, and the induced electromotive force generated at both ends of the detection coil 720 becomes 0 (zero). On the other hand, for example, when the amount of magnetic flux penetrating the first winding portion 721 and the second winding portion 722 in the same direction at the same time is different, the current flowing through the first winding portion 721 and the current flowing through the second winding portion 722 cancel each other out, but a current according to the difference between the current flowing through the winding portion with the larger amount of penetrating magnetic flux and the current flowing through the winding portion with the smaller amount of penetrating magnetic flux flows in the same direction as the current flowing through the winding portion with the larger amount of penetrating magnetic flux. Therefore, an induced electromotive force corresponding to the difference in the amount of magnetic flux in the same direction penetrating the first winding portion 721 and the second winding portion 722 at the same time is generated at both ends of the detection coil 720. In addition, in FIG. 9(b), one end and the other end of the detection coil 720 are connected to a voltmeter (lock-in amplifier 403), so that a current corresponding to the induced electromotive force circulates around the winding portions of the detection coil 720.

[0064] As shown in Figures 7 and 8, in the same manner as in the first embodiment, this embodiment also illustrates a case in which the positions of the excitation coil 210 and the detection coil 720 are determined so that the central axis 160a of the nozzle 160 for surface molten steel (submerged nozzle 163) is perpendicular to the central axis 210a of the excitation coil 210 and the central axis 720a of the detection coil 720, and so that the central axis 160a of the nozzle 160 for surface molten steel (submerged nozzle 163) intersects with the central axis 210a of the excitation coil 210 and the central axis 720a of the detection coil 720 at a single point. 7, in the present embodiment, as in the first embodiment, a case is illustrated in which the distance Y1 between the excitation coil 210 and the nozzle 160 for surface molten steel (submerged nozzle 163) in the casting thickness direction (Y-axis direction) and the distance Y2 between the detection coil 720 and the nozzle 160 for surface molten steel (submerged nozzle 163) in the casting thickness direction (Y-axis direction) are approximately the same (preferably the same). However, these distances Y1 and Y2 may be different. In addition, the detection coil 720 is illustrated as being integrated and cannot be separated. There is no boundary line between the first winding part 721 and the second winding part 722.

[0065] The core 730 is made of a soft magnetic material. It is necessary to arrange the detection coil 720 so as to go around the core 730. Therefore, as shown in Fig. 8 to Fig. 9, the core 730 has a first core 731 arranged relatively on the upstream side (upper side) in the casting direction (Z-axis direction) and a second core 732 arranged relatively on the downstream side (lower side) in the casting direction (Z-axis direction).

[0066] In this embodiment, as shown in Fig. 7 and Fig. 8, the first core 731 has a first portion 731a, a second portion 731b, and a third portion 731c, and the second core 732 has a first portion 732a, a second portion 732b, and a third portion 732c. An excitation coil 210 goes around the entire first portions 731a and 732a. A detection coil 720 goes around each of the second portions 731b and 732b. The third portion 731c is magnetically connected to the first portion 731a and the second portion 731b, and is arranged to go around the nozzle 160 for surface molten steel (submerged nozzle 163).

[0067] In this embodiment, as shown in Figs. 7 and 8, the first portion 731a and the second portion 731b have a rectangular parallelepiped shape. The tip surfaces of the first portion 731a and the second portion 731b are planes that are substantially parallel to a plane determined by the casting direction (Z-axis direction) and the casting width direction (X-axis direction) and face the direction of the nozzle 160 for surface layer molten steel (submerged nozzle 163) (i.e., the tip surfaces of the first portion 731a and the second portion 731b face each other with the nozzle 160 for surface layer molten steel (submerged nozzle 163) between them). In this embodiment, as shown in Figs. 7 and 8, the third portion 731c has a hollow rectangular parallelepiped shape. The central axis of the third portion 731c and the central axis 160a of the nozzle 160 for surface layer molten steel (submerged nozzle 163) are substantially aligned. The central axis of the first core 731 and the central axis of the third portion 731c coincide with each other.

[0068] Furthermore, the first core 731 has a shape that is line-symmetrical with respect to a virtual line that passes through the center axis of the first core 731 and extends in the casting thickness direction (Y-axis direction). The first core 731 has a shape that is line-symmetrical with respect to a virtual line that passes through the center axis of the first core 731 and extends in the casting width direction (X-axis direction). Therefore, the base end surfaces of the first portion 731a and the second portion 731b are disposed on the inner peripheral surface of the third portion 731c so that the first core 731 has such a shape. In this embodiment, as shown in Figs. 7 and 8, a case is illustrated in which the first portion 731a, the second portion 731b, and the third portion 731c are integrated and cannot be separated. That is, in Figure 8, for convenience of notation and explanation, the boundary line between the first portion 731a and the third portion 731c, and the boundary line between the second portion 731b and the third portion 731c are shown by dashed lines, but in reality, such boundary lines do not exist. As described above, the first core 731 is obtained by shortening the thickness (length in the casting direction (Z-axis direction)) of the core 230 described in the first embodiment.

[0069] The second core 732 can be realized by the same thing as the first core 731. The second core 732 is realized by replacing the first core 731, the first part 731a, the second part 731b, and the third part 731c in the description of the first core 731 with the second core 732, the first part 732a, the second part 732b, and the third part 732c, respectively. Therefore, a detailed description of the second core 732 will be omitted here.

[0070] The first core 731 and the second core 732 are arranged with a gap between them in the casting direction (Z-axis direction). The positions of the first core 731 and the second core 732 in the casting width direction (X-axis direction) and the casting thickness direction (Y-axis direction) are the same. That is, when the core 730 is viewed from the casting direction (Z-axis direction) so that the first core 731 is visible, the second core 732 is hidden by the first core 731 and cannot be seen. Similarly, when the core 730 is viewed from the casting direction (Z-axis direction) so that the second core 732 is visible, the first core 731 is hidden by the second core 732 and cannot be seen.

[0071] As shown in Figure 9 (b), the spacing between the first core 731 and the second core 732 in the casting direction (Z-axis direction) is set so that the first winding portion 721 and the second winding portion 722 of the detection coil 720 are positioned in the area between the first core 731 and the second core 732. The spacer 740 is made of a non-magnetic and insulating material. The spacer 740 is made of a material having a strength that does not deform when installed in the continuous casting equipment. The spacer 740 is disposed in a region between the first core 731 and the second core 732 where the detection coil 720 is not disposed. As shown in FIG. 7, in this embodiment, the spacer 740 has the same planar shape as the planar shapes of the third parts 731c and 732c of the first core 731 and the second core 732. Although the spacer 740 is not visible in the cross-sectional view shown in FIG. 7, the planar shape of the spacer 740 is shown by a broken line for convenience of explanation. The spacer 740 is disposed in the region between the first core 731 and the second core 732 so as to overlap with the third parts 731c and 732c of the first core 731 and the second core 732.

[0072] Fig. 10 is a diagram conceptually illustrating an example of the measurement principle of the flow rate measuring unit 700. Fig. 10 is a diagram corresponding to Fig. 6. FIG. 10(a) is a diagram for explaining the magnetic field H (magnetic flux Φ) when there is no molten steel (molten metal). In FIG. 10(a), since there is no molten steel (molten metal) between the excitation coil 210 and the detection coil 720, the magnetic field H (magnetic flux Φ) generated from the excitation coil 210 is directed toward the detection coil 720 without being affected by the molten steel. In FIG. 10(a), as in FIG. 6(a), for the sake of simplicity, the magnetic field H (magnetic flux Φ) generated from the excitation coil 210 is assumed to proceed straight in the casting thickness direction (Y-axis direction). The magnetic field H generated from the excitation coil 210 penetrates the detection coil 720. In this case, the amount of magnetic flux in the same direction penetrating the first winding portion 721 and the second winding portion 722 of the detection coil 720 at the same time is the same. Therefore, as described above, no induced electromotive force is generated at both ends of the detection coil 720 (i.e., the induced electromotive force is 0 (zero)).

[0073] 10(b) is a diagram for explaining the magnetic field H (magnetic flux Φ) when molten steel (molten metal) with a flow velocity of 0 (zero) is present. In FIG. 10(b), since molten steel (molten metal) is present between the excitation coil 210 and the detection coil 720, an eddy current I e flows. Therefore, the magnetic field H (magnetic flux Φ) that reaches the detection coil 720 is smaller than in the case shown in FIG. 10(a). As in FIG. 6(b), this is shown in FIG. 10(b) by using dashed arrows to indicate the magnetic field H (magnetic flux Φ). In this case, too, the amount of magnetic flux that penetrates the first winding portion 721 and the second winding portion 722 at the same time in the same direction is the same. Therefore, as described above, no induced electromotive force is generated at both ends of the detection coil 720 (i.e., the induced electromotive force is 0 (zero)).

[0074] FIG. 10(c) is a diagram for explaining the magnetic field H (magnetic flux Φ) when molten steel (molten metal) flows in the casting direction (the direction of the white arrow). As explained with reference to FIG. 6(c), in FIG. 10(c), eddy current I eAs the magnetic field H (magnetic flux Φ) is dragged in the direction of the molten steel flow (negative direction of the Z axis), the magnetic field H (magnetic flux Φ) is also dragged in the direction of the molten steel flow (negative direction of the Z axis).

[0075] Here, the induced electromotive force V generated at both ends of the detection coil 720 is proportional to the time change (d(φ1-φ2) / dt) of the difference between the magnetic flux φ1 penetrating the first winding portion 721 and the magnetic flux φ2 penetrating the second winding portion 722. If the proportionality coefficient is α, then the relationship V=αdΦ / dt=αd(φ1-φ2) / dt holds. Also, the eddy current I due to the flow of molten steel e And since the amount of deviation z (in the flow direction of the molten steel (negative direction of the Z-axis)) of the magnetic field H (magnetic flux Φ) is proportional to the flow velocity v of the molten steel, the difference (φ1-φ2) in the amount of magnetic flux penetrating the first winding portion 721 and the second winding portion 722 is also proportional to the flow velocity v of the molten steel. Therefore, as shown in FIG. 10(c), the eddy current I due to the flow of molten steel e In accordance with the deviation z of the magnetic field H (magnetic flux Φ), the magnetic flux φ1 penetrating the first winding portion 721 decreases, and the magnetic flux φ2 penetrating the second winding portion 722 increases. In this way, the eddy current I e Also, the deviation z of the magnetic field H (magnetic flux Φ) is proportional to the difference (φ1-φ2) in the amount of magnetic flux passing through the first winding portion 721 and the second winding portion 722. In FIG. 10(c), this is represented by making the number of dashed arrow lines passing through the first winding portion 721 and the number of dashed arrow lines passing through the second winding portion 722 different from the numbers shown in FIG. 10(b). As described above, the eddy current I due to the flow of molten steel e Also, since the deviation z of the magnetic field H (magnetic flux Φ) is proportional to the flow velocity v of the molten steel, the difference (φ1-φ2) in the amount of magnetic flux penetrating the first circulation part 721 and the second circulation part 722 is also proportional to the flow velocity v of the molten steel (φ1-φ2 ​​(=Φ) can be approximated by a linear function of v). Therefore, the induced electromotive force V generated at both ends of the detection coil 720 is expressed as V=αdΦ(v) / dt, where α is a proportionality coefficient.

[0076] The calculation unit 400 of this embodiment performs the same processing as the calculation unit 400 of the first embodiment. However, the signal input to the calculation unit 400 is not the induced electromotive force detected by the detection coil 220, but the induced electromotive force detected by the detection coil 720. The induced electromotive force detected by the detection coil 720 is an induced electromotive force corresponding to the time change of the difference (φ1-φ2) in the amount of magnetic flux penetrating the first circulating part 721 and the second circulating part 722. Therefore, the coefficients and constants of the function Φ(v) and the value of the proportionality coefficient α are different from those of the first embodiment. Also, even if molten steel does not exist in the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163) and the molten steel penetrates the detection coil 720, the induced electromotive force detected by the detection coil 720 becomes 0 (zero). Therefore, in this embodiment, it is not necessary to subtract the reference signal (the flow velocity original signal obtained when molten steel does not exist in the hollow part of the nozzle 160 for surface layer molten steel (submerged nozzle 163)) from the flow velocity original signal.

[0077] As described above, in this embodiment, the detection coil 720 has the first winding portion 721 and the second winding portion 722, and one turn of the detection coil 720 is composed of one first winding portion 721 and one second winding portion 722 connected to the first winding portion 721. The first winding portion 721 and the second winding portion 722 are connected so that the direction of the current flowing through the first winding portion 721 and the direction of the current flowing through the second winding portion 722 are opposite to each other when magnetic flux of the same direction passes through the first winding portion 721 and the second winding portion 722 at the same time. Therefore, the induced electromotive force detected by the detection coil 720 is an induced electromotive force according to the time change of the difference (φ1-φ2) between the amount of magnetic flux passing through the first winding portion 721 and the second winding portion 722. Therefore, in addition to the effects described in the first embodiment, the induced electromotive force detected by the detection coil 720 becomes less susceptible to the effects of disturbances, and the flow rate of molten steel flowing through the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163) can be measured with even higher accuracy. Also, it becomes unnecessary to perform processing based on the flow velocity original signal when no molten steel is present in the hollow part of the nozzle for surface layer molten steel 160 (submerged nozzle 163). <Modification> In this embodiment as well, the various modified examples described in the first embodiment can be adopted.

[0078] (Third embodiment) Next, a third embodiment will be described. In the first embodiment, the core 230 is configured to go around the nozzle 160 for surface layer molten steel (submerged nozzle 163), and the cross section in a plane perpendicular to the casting direction (Z-axis direction) has a closed shape around the nozzle 160 for surface layer molten steel (submerged nozzle 163). As described in the first embodiment, this can further reduce the influence of noise contained in the signal of the induced electromotive force, and can reduce the magnetic field H (magnetic flux Φ) leaking to the outside, thereby suppressing adverse effects on the outside. On the other hand, when the core 230 is configured to go around the nozzle 160 for surface layer molten steel (submerged nozzle 163), the volume of the core 230 becomes large. In addition, it is not easy to retract the flow rate measuring unit 200 and the nozzle 160 for surface layer molten steel (submerged nozzle 163) from the continuous casting equipment. Therefore, in this embodiment, a case will be described in which a core is used that does not orbit the nozzle 160 for surface molten steel (submerged nozzle 163) and whose cross-sectional shape in a plane perpendicular to the casting direction (Z-axis direction) does not have a closed shape around the nozzle 160 for surface molten steel (submerged nozzle 163). As described above, the main difference between this embodiment and the first embodiment is the configuration of the core. Therefore, in the description of this embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals as those in Figures 1 to 6, and detailed description thereof will be omitted.

[0079] This embodiment also illustrates a case where a flow rate measurement system is applied to the continuous casting equipment shown in the first embodiment. Fig. 11 is a diagram showing an example of the configuration of the flow rate measurement system. Fig. 11 is a diagram corresponding to Fig. 2. Fig. 12 is a diagram showing an example of the detailed arrangement of the flow rate measurement system. Fig. 12 is a diagram corresponding to Fig. 4.

[0080] 11 and 12, the flow rate measurement system has a flow rate measurement unit 1100 and a calculation unit 400. As in the first embodiment, the flow rate measurement object in this embodiment is the flow rate of molten steel in the hollow portion of the submerged nozzle 163. However, as in the flow rate measurement system of the first embodiment, the flow rate measurement system of this embodiment may also measure the flow rate of molten steel in the hollow portion of the upper nozzle 161.

[0081] As in the first embodiment, this embodiment also illustrates an example in which the position of the flow measuring unit 1100 in the casting direction (Z-axis direction) is determined so that the range (range from the upper end to the lower end) of the flow measuring unit 1100 in the casting direction (Z-axis direction) is included in the range (range from the upper end to the lower end) of the submerged nozzle 163 in the casting direction (Z-axis direction) (see Figure 3).

[0082] The flow rate measuring unit 1100 includes an excitation coil 210, a detection coil 220, a core 1130, and cases 1141 and 1142. The excitation coil 210 and the detection coil 220 are the same as those described in the first embodiment.

[0083] In this embodiment, as shown in FIG. 11 and FIG. 12, the core 1130 has a first portion 1130a and a second portion 1130b. The first portion 1130a and the second portion 1130b have the same configuration. The first portion 1130a is, for example, the same as the first portion 230a described in the first embodiment, and has a rectangular parallelepiped shape. The excitation coil 210 goes around the first portion 1130a. At this time, as shown in FIG. 11 and FIG. 12, the first portion 1130a does not need to be larger in the Y-axis direction than the excitation coil 210 (i.e., the length of the first portion 1130a in the Y-axis direction may be equal to or less than the length of the excitation coil 210 in the Y-axis direction). The second portion 1130b is, for example, the same as the second portion 230b described in the first embodiment, and has a rectangular parallelepiped shape. The detection coil 220 goes around the second portion 1130b. 11 and 12, the second portion 1130b does not need to be larger in the Y-axis direction than the detection coil 220 (i.e., the length of the second portion 1130b in the Y-axis direction may be equal to or less than the length of the detection coil 220 in the Y-axis direction). In this embodiment, the core 1130 does not have a portion made of a soft magnetic material for magnetically connecting the first portion 1130a and the second portion 1130b, like the third portion 230c described in the first embodiment.

[0084] The cases 1141 and 1142 are made of a heat insulating material, similar to the case 240 described in the first embodiment. In addition, the cases 1141 and 1142 are preferably made of a non-magnetic and non-metallic (preferably insulating) material. In this embodiment, separate cases 1141 and 1142 are used for the first part 1130a and the second part 1130b of the core 1130, respectively. The case 1141 is for preventing the excitation coil 210 and the first part 1130a of the core 1130 from being overheated by the radiant heat from the molten steel. The excitation coil 210 and the first part 1130a of the core 1130 are housed inside the case 1141. The case 1142 is for preventing the detection coil 220 and the second part 1130b of the core 1130 from being overheated by the radiant heat from the molten steel. The detection coil 220 and the second portion 1130b of the core 1130 are housed inside the case 1142. The insides of the cases 1141 and 1142 do not communicate with each other.

[0085] Similar to the case 240 described in the first embodiment, a cooling medium (e.g., dry air) may be supplied from the outside to the inside of the case 1141 (1142) toward the excitation coil 210 and the first part 1130a of the core 1130 (the detection coil 220 and the second part 1130b of the core 1130).

[0086] As described above, in this embodiment, the core 1130 has the first part 1130a where the excitation coil 210 is arranged and the second part 1130b where the detection coil 220 is arranged, and does not go around (surround) the nozzle for surface molten steel 160 (submerged nozzle 163). Therefore, various operations for the excitation coil 210, the first part 1130a of the core 1130, and the case 1141, and various operations for the detection coil 220, the second part 1130b of the core 1130, and the case 1142 can be performed separately. The various operations include installation and removal. In addition, the volume and mass of the flow rate measurement unit 1100 can be reduced. Therefore, various operations for the flow rate measurement unit 1100 are facilitated. Furthermore, since the size of cases 1141, 1142 can be reduced, stagnation of the cooling medium inside cases 1141, 1142 can be suppressed, and therefore the insides of cases 1141, 1142 can be cooled more easily.

[0087] In this embodiment, as shown in FIG. 11, by moving at least one of the core 1130 (and the cases 1141, 1142) and the nozzle 160 for surface layer molten steel (submerged nozzle 163) along a direction perpendicular to the longitudinal direction (casting direction (Z-axis direction)) of the nozzle 160 for surface layer molten steel (submerged nozzle 163), the core 1130 is moved from the direction in which the first part 1130a and the second part 1130b of the core 1130 face each other (Y-axis direction). A space larger than the outer diameter of the nozzle 160 for surface layer molten steel (submerged nozzle 163) is formed in the core 1130 (and the cases 1141, 1142) so that the core 1130 (and the cases 1141, 1142) and the nozzle 160 for surface layer molten steel (submerged nozzle 163) do not overlap when the core 1130 (and the cases 1141, 1142) and the nozzle 160 for surface layer molten steel (submerged nozzle 163) are viewed. The outer diameter of the nozzle 160 for surface layer molten steel (submerged nozzle 163) is the outer diameter (diameter of the outermost circle) of the nozzle 160 for surface layer molten steel in the cross section shown in FIG. 11. Therefore, the flow rate measuring unit 1100 and the nozzle 160 for surface layer molten steel (submerged nozzle 163) can be easily retracted from the continuous casting equipment. Furthermore, the method for moving the core 1130 (and the cases 1141, 1142) and the nozzle for surface molten steel 160 (submerged nozzle 163) is not particularly limited. For example, the core 1130 (and the cases 1141, 1142) and the nozzle for surface molten steel 160 (submerged nozzle 163) may be moved using a crane. A driving device having a motor for moving the core 1130 (and the cases 1141, 1142) and a driving device having a motor for moving the nozzle for surface molten steel 160 (submerged nozzle 163) may be used.

[0088] <Modification> <<First Modification>> In this embodiment, the core 1130 has a first portion 1130a and a second portion 1130b each having a rectangular parallelepiped shape. However, as long as the core does not revolve around the surface molten steel nozzle 160 (submerged nozzle 163), the first and second portions of the core are not limited to those shown in Figures 11 and 12. For example, the following first modified example may be adopted.

[0089] Fig. 13 is a diagram showing the configuration of a flow measurement system according to a first modified example of this embodiment. Fig. 13 is a diagram corresponding to Fig. 2 and Fig. 11. Fig. 14 is a diagram showing the details of the arrangement of the flow measurement system according to the first modified example of this embodiment. Fig. 15 is a diagram corresponding to Fig. 4 and Fig. 12. 13 and 14, the flow rate measurement system includes a flow rate measurement unit 1300 and a calculation unit 400.

[0090] The flow rate measuring unit 1300 includes an excitation coil 210, a detection coil 220, a core 1330, and cases 1341 and 1342. The excitation coil 210 and the detection coil 220 are the same as those described in the first embodiment.

[0091] In the first modified example, as shown in FIG. 13 and FIG. 14, the core 1330 has a first portion 1330a and a second portion 1330b. The first portion 1330a and the second portion 1330b have the same configuration. For example, as shown in FIG. 13 and FIG. 14, the first portion 1330a and the second portion 1330b have a shape in which two rectangular parallelepipeds of different sizes are integrated so that the XY cross section and the YZ cross section have a convex shape. Note that the XZ cross sections of the first portion 1330a and the second portion 1330b are quadrangles, and the quadrangle has a wider region of the convex shape than a narrower region. In FIG. 13 and FIG. 14, the boundary between the wider region and the narrower region of the convex shape is indicated by a dashed line (virtual line).

[0092] This allows the amount of magnetic flux generated by excitation coil 210 to be increased by the amount of the wide area of ​​the convex shape of first portion 1330a and second portion 1330b, thereby improving detection accuracy. In addition, the magnetic flux generated by excitation coil 210 spreads to the surroundings, reducing interference caused by electromagnetic induction, and further has the advantage of being able to attenuate noise from the surroundings together with detection coil 220.

[0093] Excitation coil 210 goes around the narrow convex region of first portion 1330a. At this time, it is preferable that the side surfaces (end faces in the X-axis and Z-axis directions) of the wide convex region of first portion 1330a are not positioned to the side of excitation coil 210 (positive and negative sides of the X-axis and Z-axis).

[0094] Detection coil 220 goes around the narrow convex region of second portion 1130b. At this time, it is preferable that the side surface (the end surface in the X-axis direction) of the wide convex region of second portion 1330b is not positioned to the side of detection coil 220 (the positive direction side or the negative direction side of the X-axis).

[0095] In addition, in Figures 13 and 14, for convenience of notation and explanation, the boundary line between the narrow and wide regions of the convex shape of first portion 1330a and the boundary line between the narrow and wide regions of the convex shape of second portion 1330b are shown by dashed lines, but in reality such boundary lines do not exist.

[0096] Like the core 1130 described in this embodiment, the core 1330 of the first modified example does not have a portion made of a soft magnetic material to magnetically connect the first portion 1330a and the second portion 1330b.

[0097] The cases 1341 and 1342 are different from the cases 1141 and 1142 described in this embodiment only in size. The case 1341 has a size capable of housing the excitation coil 210 and the first part 1330a of the core 1330. The case 1342 has a size capable of housing the detection coil 220 and the second part 1330b of the core 1330.

[0098] By configuring the core 1330 as in the first modified example, the amount of magnetic flux generated from the excitation coil 210 (first part 1330a of the core 1330) and the amount of magnetic flux penetrating the detection coil 220 (second part 1330b of the core 1330) can be increased compared to the core 1130 described in this embodiment.

[0099] Moreover, the modified example of the core 1130 described in this embodiment is not limited to the core 1330 of the first modified example. For example, the shape and size of the core may be appropriately determined so as not to orbit the nozzle 160 for surface molten steel (submerged nozzle 163) depending on which of the following is to be prioritized: preventing an increase in the volume and weight of the core, enabling the flow measurement unit and the nozzle 160 for surface molten steel (submerged nozzle 163) to be easily retracted from the continuous casting equipment, or increasing the amount of magnetic flux.

[0100] Further, the tip faces of the first parts 1130a, 1330a of the cores 1130, 1330 (the faces facing the nozzle 160 for surface molten steel (submerged nozzle 163) with a gap therebetween) may be positioned closer to the nozzle 160 for surface molten steel (submerged nozzle 163) side (the positive side of the Y axis) than the excitation coil 210. Similarly, the tip faces of the first parts 1130b, 1330b of the cores 1130, 1330 (the faces facing the nozzle 160 for surface molten steel (submerged nozzle 163) with a gap therebetween) may be positioned closer to the nozzle 160 for surface molten steel (submerged nozzle 163) side (the negative side of the Y axis) than the detection coil 220. These are the same for the core 230 described in the first embodiment and the core 730 described in the second embodiment.

[0101] <<Second Modification>> In this embodiment, the case where separate cases 1141, 1142 are used has been exemplified. However, the excitation coil 210, the detection coil 220, and the core 1130 (the first part 1130a and the second part 1130b) may be housed in one case so that the flow rate measuring unit and the nozzle for surface molten steel 160 (the submerged nozzle 163) can be easily retracted from the continuous casting equipment. For example, the following second modified example may be adopted.

[0102] Fig. 15 is a diagram showing the configuration of a flow measurement system according to a second modified example of this embodiment. Fig. 15 is a diagram corresponding to Fig. 2 and Fig. 11. Fig. 16 is a diagram showing details of the arrangement of the flow measurement system according to the second modified example of this embodiment. Fig. 16 is a diagram corresponding to Fig. 4 and Fig. 12. 15 and 16, the flow rate measurement system includes a flow rate measurement unit 1500 and a calculation unit 400.

[0103] The flow rate measuring unit 1500 includes an excitation coil 210, a detection coil 220, a core 1130, and a case 1540. The excitation coil 210 and the detection coil 220 are the same as those described in the first embodiment. The core 1130 is the same as those described in the present embodiment.

[0104] The case 1540 is made of a heat insulating material and serves to prevent the excitation coil 210, the detection coil 220, and the core 1130 from being overheated by radiant heat from the molten steel. The case 1540 is preferably made of a non-magnetic and non-metallic (preferably insulating) material. The case 240 described in the first embodiment has a shape that goes around (surrounds) the nozzle for surface layer molten steel 160 (submerged nozzle 163) like the core 230, and the cross section perpendicular to the casting direction (Z-axis direction) has a shape that is closed around the nozzle for surface layer molten steel 160 (submerged nozzle 163). In contrast, the case 1540 of the second modified example is disposed around the nozzle 160 for surface layer molten steel (submerged nozzle 163), but the cross section perpendicular to the casting direction (Z-axis direction) does not have a closed shape around the nozzle 160 for surface layer molten steel (submerged nozzle 163), and has a shape with both ends separated in the cross section perpendicular to the casting direction (Z-axis direction) so that the nozzle 160 for surface layer molten steel (submerged nozzle 163) can pass through. Specifically, Fig. 15 illustrates a case in which the cross section of the case 1540 perpendicular to the casting direction (Z-axis direction) has a non-hollow concave shape at both ends in the casting direction (Z-axis direction) and a hollow concave shape in the region between the both ends.

[0105] The case 1540 contains the excitation coil 210, the detection coil 220, and the core 1130 (first portions 1130a and 1130b). A cooling medium (such as dry air) may be supplied from the outside of the case 1540 to the inside toward the excitation coil 210, the detection coil 220, and the core 1130 (first portions 1130a and 1130b). In this case, for example, a flow of the cooling medium (a flow circulating on the XY plane) circulating in a direction perpendicular to the casting direction (Z-axis direction) may be formed in the hollow region inside the case 1540 shown in FIG. For example, one or more through holes may be formed in a portion of the side surface (e.g., the tip surface) of case 1540 that is located in a narrow concave region of the side surface, and a pipe that serves as a path for the cooling medium may be attached to the through hole, and a fan or blower may be attached to the pipe, thereby forming a flow of cooling medium circulating in a direction perpendicular to the casting direction (Z-axis direction) in the hollow region inside case 1540 shown in FIG. 15.

[0106] The nozzle 160 for surface molten steel (submerged nozzle 163) is disposed in the concave space of the case 1540, and the size of the space is such that the nozzle 160 for surface molten steel can be moved laterally (in the negative direction of the X-axis) beyond the flow rate measuring unit 1500. In this way, even with a single case 1540, the flow rate measuring unit 1500 and the nozzle 160 for surface molten steel (submerged nozzle 163) can be easily retracted from the continuous casting equipment. In addition, since there is only one case 1540, it is not necessary to supply a cooling medium separately to each of the two cases 1141 and 1142 as in this embodiment.

[0107] <<Other variations>> The first and second modified examples may be combined. In addition, the present embodiment may also employ the various modified examples described in the first embodiment (excluding the seventh modified example of the first embodiment). In addition, the case 1540 described in the second modified example of the present embodiment may be applied to the core described in the seventh modified example of the first embodiment.

[0108] (Fourth embodiment) Next, the fourth embodiment will be described. In the third embodiment, a core 1130 is applied to the excitation coil 210 and the detection coil 220 described in the first embodiment, which does not go around the nozzle 160 for surface molten steel (submerged nozzle 163) and has a cross section in a plane perpendicular to the casting direction (Z-axis direction) that does not have a closed shape around the nozzle 160 for surface molten steel (submerged nozzle 163). In contrast, in the present embodiment, a core is applied to the excitation coil 210 and the detection coil 720 described in the second embodiment, which does not go around the nozzle 160 for surface molten steel (submerged nozzle 163) and has a cross section in a plane perpendicular to the casting direction (Z-axis direction) that does not have a closed shape around the nozzle 160 for surface molten steel (submerged nozzle 163). Thus, the present embodiment and the third embodiment are mainly different in the configuration of the core. Therefore, in the description of this embodiment, the same parts as those in the first to third embodiments are denoted by the same reference numerals as those in FIGS. 1 to 16, and detailed description thereof will be omitted.

[0109] This embodiment also illustrates a case where a flow measurement system is applied to the continuous casting equipment shown in the first embodiment. Fig. 17 is a diagram showing an example of the configuration of the flow measurement system. Fig. 17 is a diagram corresponding to Figs. 2 and 7. Fig. 18 is a diagram showing an example of the detailed arrangement of the flow measurement system. Fig. 18 is a diagram corresponding to Figs. 4 and 8.

[0110] 17 and 18, the flow rate measurement system has a flow rate measurement unit 1700 and a calculation unit 400. In this embodiment, as in the first and second embodiments, the flow rate of molten steel in the hollow part of the submerged nozzle 163 is the measurement target. However, the flow rate measurement system of this embodiment may also measure the flow rate of molten steel in the hollow part of the upper nozzle 161, as in the first and second embodiments.

[0111] In addition, similarly to the first and second embodiments, this embodiment also illustrates an example in which the position of the flow measuring unit 1100 in the casting direction (Z-axis direction) is determined so that the range (range from the upper end to the lower end) of the flow measuring unit 1700 in the casting direction (Z-axis direction) is included in the range (range from the upper end to the lower end) of the submerged nozzle 163 in the casting direction (Z-axis direction) (see Figure 3).

[0112] The flow rate measuring unit 1100 includes an excitation coil 210, a detection coil 720, a core 1730, a spacer 1740, and cases 1741 and 1742. The excitation coil 210 and the detection coil 720 are the same as those described in the first and second embodiments.

[0113] In this embodiment, as shown in FIG. 17 and FIG. 18, the core 1730 has a first portion 1730a and two second portions 1730b and 1730c. The first portion 1730a is, for example, the same as the first portion 230a described in the first embodiment and has a rectangular parallelepiped shape. The excitation coil 210 goes around the first portion 1130a. The two second portions 1730b and 1730c have the same configuration. The second portions 1730b and 1730c are, for example, the same as the second portion 731a of the first core 731 and the second portion 731b of the second core 732 described in the second embodiment and have a rectangular parallelepiped shape. The detection coil 720 goes around each of the second portions 1730b and 1730c.

[0114] The two second portions 1730b, 1730c of the core 1730 are arranged with a gap between them in the casting direction (Z-axis direction). The positions of the two second portions 1730b, 1730c of the core 1730 in the casting width direction (X-axis direction) and the casting thickness direction (Y-axis direction) are the same. That is, when the core 1730 is viewed from the casting direction (Z-axis direction) so that one second portion 1732b of the core 1730 is visible, the other second portion 1732c of the core 1730 is hidden by one second portion 1732b and cannot be seen.

[0115] Fig. 19 is a diagram conceptually showing an example of an excitation coil 210 (Fig. 19(a)) arranged so as to surround a core 1730, and a detection coil 720 (Fig. 19(b)) arranged so as to surround a core 1730. Fig. 19 is a diagram corresponding to Fig. 9.

[0116] In this embodiment, as shown in Fig. 19(a), an example is shown in which the excitation coil 210 is arranged to wind around the first portion 1730a of the core 1730. As in the second embodiment, in this embodiment, as shown in Fig. 19(a), an example is shown in which the excitation coil 210 has a winding portion, and one turn of the excitation coil 210 is formed by one winding portion.

[0117] As described in the second embodiment, the detection coil 720 has a first winding portion 721 and a second winding portion 722. One turn of the detection coil 720 is formed by one first winding portion 721 and one second winding portion 722 connected to the first winding portion 721. As shown in FIG. 19(b), the present embodiment illustrates a case in which the number of turns of the detection coil 720 is one, as in the second embodiment, but the number of turns of the detection coil 720 is appropriately set so that the magnetic field generated by the excitation coil 210 is detected by the detection coil 220. The one-turn portion of the detection coil 720 has a shape obtained by twisting the one-turn portion of the detection coil 220 of the first embodiment into the shape of an Arabic numeral 8 as a whole.

[0118] The magnetic flux passing through the first winding portion 721 and the second winding portion 722 and the current flowing through the first winding portion 721 and the second winding portion 722 are as described in the second embodiment with reference to Figure 9, so detailed description of these will be omitted here.

[0119] As shown in FIG. 19(b), the spacing in the casting direction (Z-axis direction) between the two second portions 1730b, 1730c of the core 1730 is set so that the first winding portion 721 and the second winding portion 722 of the detection coil 720 are positioned in the area between the two second portions 1730b, 1730c of the core 1730. The spacer 1740 is made of a non-magnetic and insulating material like the spacer 740 described in the second embodiment. The spacer 1740 is made of a material having a strength that does not deform when installed in the continuous casting equipment. The spacer 1740 is disposed in a region between the two second parts 1730b and 1730c of the core 1730 where the detection coil 720 is not disposed. As shown in FIG. 17, this embodiment illustrates a case where the spacer 1740 has a rectangular parallelepiped shape. Although the spacer 1740 is not visible in the cross-sectional view shown in FIG. 17, the planar shape of the spacer 1740 is shown by a broken line for convenience of explanation. The spacer 1740 is disposed in a region between the two second parts 1730b and 1730c of the core 1730 so as to overlap with the region of the two second parts 1730b and 1730c of the core 1730 where the detection coil 720 is not disposed.

[0120] In the second embodiment, a core 730 is used that goes around the nozzle 160 for surface layer molten steel (submerged nozzle 163) and has a cross section in a plane perpendicular to the casting direction (Z-axis direction) that is closed around the nozzle 160 for surface layer molten steel (submerged nozzle 163). Therefore, in the second embodiment, as shown in Figs. 7 to 9, the core 730 has a first core 731 that is relatively arranged upstream (upper side) in the casting direction (Z-axis direction) and a second core 732 that is relatively arranged downstream (lower side) in the casting direction (Z-axis direction). The cross sections of the first core 731 and the second core 732 in a plane perpendicular to the casting direction (Z-axis direction) have a closed shape around the nozzle 160 for surface layer molten steel (submerged nozzle 163). Moreover, the cross section of the spacer 740 in a plane perpendicular to the casting direction (Z-axis direction) also has a closed shape around the surface molten steel nozzle 160 (submerged nozzle 163). Since the second embodiment uses the core 730 and spacer 740 having such a shape, the spacer 740 is also placed between the first core 731 and the second core 732 in the region where the excitation coil 210 is placed in order to place the detection coil 720.

[0121] In contrast, in this embodiment, the core 1730 does not have a portion for magnetically connecting the first portion 1730a to the second portions 1730b and 1730c. Therefore, it is not necessary to make the first portion 1730a of the core 1730 into two first portions separated in the casting direction (Z-axis direction) like the first portions 731a and 732a of the first core 731 and the second core 732 described in the second embodiment. Therefore, the amount of magnetic flux generated from the first portion 1730a of the core 1730 can be made larger than the amount of magnetic flux generated from the first portions 731a and 732a of the first core 731 and the second core 732.

[0122] <Modification> In this embodiment as well, the various modified examples described in the first to third embodiments can be employed (however, the seventh modified example of the first embodiment is excluded). Also, in the second embodiment as well, as in this embodiment, at least a part of the region between the first core 731 and the second core 732 other than the region in which the excitation coil 210 and the detection coil 720 are arranged may be a part of the core (i.e., may be made of a soft magnetic material).

[0123] (Example) Next, an embodiment will be described. In this example, the flow rate of molten steel flowing through the hollow portion of the surface layer molten steel nozzle 160 (submerged nozzle 163) was measured by the method of the second embodiment. 20 is a diagram showing an example of the relationship between the flow rate of molten steel and the induced electromotive force, in which au indicates an arbitrary unit.

[0124] To obtain graphs 2001 and 2002 shown in Fig. 20, the flow rate of molten steel was derived based on the induced electromotive force detected by detection coil 720 in two different periods, and the relationship between the flow rate of molten steel and the induced electromotive force was derived for each period. In Fig. 20, graph 2001 shows the relationship in a first period, and graph 2002 shows the relationship in a second period. The end of the first period is earlier than the start of the second period, and there is no overlap between the first period and the second period. The slopes of graphs 2001 and 2002 are approximately the same. From this, it can be seen that the method of the second embodiment can continue to perform accurate measurement even if the time during which the radiant heat from the molten steel is received becomes longer.

[0125] FIG. 21 is a diagram showing an example of the relationship between speed and induced electromotive force. FIG. 21(a) shows the relationship when the method described in Patent Document 2 is used. FIG. 21(b) shows the relationship when the method of the second embodiment is used. In order to obtain the graphs 2111 to 2113, 2121, 2122, and 2123 shown in FIG. 21, a solid metal was used instead of molten steel, and the induced electromotive force was detected when the speed of the metal was changed, and the relationship between speed and induced electromotive force was derived from the detected results. The relationship between speed and induced electromotive force was derived by changing the distance between the detection coil and the metal.

[0126] As shown by the graphs 2111, 2112, and 2113 in FIG. 21(a), in the technique described in Patent Document 2, the relationship between the speed and the induced electromotive force varies when the distance between the detection coil and the metal is different. This corresponds to the fact that when the molten steel is not filled but flows discretely in the space, the induced electromotive force detected by the detection coil shows different values ​​depending on the position where the molten steel is present, even though the flow rate is the same. In contrast, as shown by the graphs 2121, 2122, and 2123 in FIG. 21(b), in the technique of the second embodiment, the relationship between the speed and the induced electromotive force hardly varies even when the distance between the detection coil and the metal is different. This corresponds to the fact that the induced electromotive force detected by the detection coil hardly depends on the position of the molten steel, even when the molten steel is not filled but flows discretely in the space. Therefore, it can be seen that the technique of the second embodiment can measure the flow rate of molten steel flowing through the hollow part of the nozzle for surface molten steel 160 (submerged nozzle 163) with higher accuracy than the technique described in Patent Document 2.

[0127] (Other embodiments) The processes performed by the computer 404 in the above-described embodiments of the present invention can be realized by the computer executing a program. A computer-readable recording medium on which the program is recorded and a computer program product such as the program can also be applied as embodiments of the present invention. Examples of recording media that can be used include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, magnetic tapes, non-volatile memory cards, and ROMs. Furthermore, the above-described embodiments of the present invention are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0128] 110 Ladle 120 Component addition device 130 Tundish 140 Mold 150 Nozzle for inner layer molten steel 160 Surface molten steel nozzle 170 Water Level Gauge 181 Electromagnetic stirring device 182 Electromagnetic brake 200 Flow measurement section 210 Excitation coil 220 Detection coil 230 cores 240 cases 400 Arithmetic section 700 Flow measurement section 720 Detection coil 730 cores 740 Spacer 1100 Flow measurement section 1130 cores Cases 1141 and 1142 1300 Flow measurement section 1330 cores 1341, 1342 cases 1500 Flow measurement section 1540 Case 1700 Flow measurement section 1730 cores 1740 Spacer 1741, 1742 cases

Claims

1. 1. A flow measurement system for measuring a flow rate of molten metal flowing through a hollow portion of a tube, comprising: an excitation coil for generating a magnetic field across the molten metal flowing through the hollow portion of the tube; a current supplying means for supplying an AC excitation current to the excitation coil; a detection means for detecting a magnetic field generated from the excitation coil when an AC excitation current flows through the excitation coil, or a signal based on a change in the magnetic field over time; and a flow rate deriving means for deriving a flow rate of the molten metal based on a signal detected by the detection means, the tube is disposed between the excitation coil and the detection means; A flow measurement system, characterized in that a magnetic field that crosses the pipe is generated from the excitation coil and reaches the detection means located opposite the excitation coil across the pipe.

2. The detection means includes a detection coil. the flow rate deriving means derives a flow rate of the molten metal based on a signal of an induced electromotive force generated in the detection coil as a result of the detection coil detecting a time change in a magnetic field; 2. The flow rate measurement system according to claim 1, wherein a magnetic flux based on a magnetic field generated from the excitation coil passes across the pipe and through the detection coil, thereby generating an induced electromotive force in the detection coil.

3. Further comprising a core; The flow rate measurement system according to claim 2 , wherein the excitation coil and the detection coil are arranged to surround the core.

4. The core is a first portion in which the excitation coil is disposed; a second portion in which the detection coil is disposed; a third portion magnetically connected to the first portion and the second portion and arranged to circumnavigate the tube; 4. The flow rate measurement system according to claim 3, wherein the first portion and the second portion are disposed at opposing positions with a gap between them across the pipe.

5. The core is a first portion in which the excitation coil is disposed; a second portion in which the detection coil is disposed; the first portion and the second portion are disposed at opposing positions with a gap between them via the pipe, 4. The flow measurement system of claim 3, wherein the core does not have a portion that encircles the tube.

6. The flow measurement system described in claim 5, characterized in that the core has a space larger than the outer diameter of the tube so that the core and the tube do not overlap when viewed from a direction in which the first part and the second part face each other by moving at least one of the core and the tube along a direction perpendicular to the longitudinal direction of the tube.

7. The detection coil has a winding portion, 7. The flow rate measurement system according to claim 2, wherein one turn of the detection coil is formed by one of the winding portions.

8. the detection coil has a first winding portion and a second winding portion, the first winding portion and the second winding portion are connected to each other such that, when a magnetic flux of the same direction passes through the first winding portion and the second winding portion at the same time, a direction of a current flowing through the first winding portion and a direction of a current flowing through the second winding portion are opposite to each other; The flow measurement system according to any one of claims 2 to 6, characterized in that one turn of the detection coil is formed by one of the first winding parts and one of the second winding parts connected to the first winding part.

9. the molten metal is molten steel, 9. The flow rate measurement system according to claim 1, wherein the pipe is a nozzle for supplying molten steel in a tundish into a mold in a continuous casting facility.

Images