Device for measuring electrode length of carbon electrode in resistance-type furnace and method for operating resistance-type furnace

Abstract

In a resistance-type furnace, even if a metal conduit (20) burns through, the molten liquid surface (200) is detected, and the electrode length of a carbon electrode (10) is measured more accurately. The present invention is provided with: a conduit (20) which is formed by connecting a plurality of metal conduit pieces (21) and which is inserted so as to reach the lower end of a carbon electrode (10); and a distance meter (30) which is installed at the upper end of the conduit (20) and is provided with a microwave or millimeter wave transmitting and receiving unit. The inner diameter of the conduit (20) is larger than the inner diameter of the waveguide (35) of the distance measuring instrument (30), the conduit (20) and the distance measuring instrument (30) are connected via a tapered structure (40), the tapered structure (40) is provided with a cavity expanding in a tapered shape from the waveguide (35) to the conduit (20), and microwaves or millimeter waves are transmitted from the lower end of the conduit (20) to the melt surface (200) of the object to be melted. The distance between the distance meter (30) and the molten liquid surface (200) is measured by receiving the microwaves or millimeter waves reflected by the molten liquid surface (200).

Description

Technical Field

[0001] The present invention relates to an apparatus for measuring the electrode length of a carbon electrode in a resistance type melting furnace used for melting a molten material such as iron ore into the furnace. The present invention also relates to an operating method of the resistance type melting furnace. Background Art

[0002] The following resistance melting furnace is currently used, in which a molten material such as iron ore is put into the furnace, a carbon electrode is inserted into the accumulated molten material, and electricity is applied to melt the molten material, and the molten material is recovered. Fig.12 1 is a schematic diagram showing an example of a resistance melting furnace, showing the situation of melting iron ore. As shown in the figure, in the resistance melting furnace 100, a carbon electrode 101 is inserted into the iron ore 102 accumulated in the furnace, and a current is passed through the carbon electrode 101. The iron ore 102 existing between the electrodes is used as a resistor, and the iron ore 102 is melted by Joule heat. Electricity is supplied to the carbon electrode 101 from the power supply 110 via the electrode holder 180 mounted on the carbon electrode 101. Then, when melting proceeds, three layers of unmelted iron ore 102, molten slag layer 103, and molten iron layer 104 are formed in sequence from the top at the bottom of the furnace, and the molten slag is recovered from the slag discharge port 105, and the molten iron is recovered from the steel outlet 106.

[0003] At this time, the electrode lifting device 120 is used to lift the carbon electrode 101 in the up and down direction in the figure while energizing the carbon electrode 101. Therefore, it is necessary to detect the molten liquid level of the molten iron layer 104, calculate the electrode length of the carbon electrode 101, and control the lifting position of the carbon electrode 101.

[0004] Therefore, in Patent Document 1, the applicant inserts a metal conduit reaching the lower end of at least one carbon electrode, installs a microwave or millimeter wave transceiver at the upper end of the conduit, and propagates the microwaves or millimeter waves from the transceiver inside the conduit, receives the microwaves or millimeter waves reflected at the lower end of the conduit to detect the molten liquid level of the molten iron layer, and calculates the electrode length of the carbon electrode based on the distance from the transceiver to the molten liquid level.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5671744 Summary of the invention

[0008] Technical problem that the invention aims to solve

[0009] However, since the conduit is made of metal, when the molten material is a metal with a high melting point such as iron ore, the lower end is burned through by the high heat from the molten liquid surface. In addition, the inner wall of the carbon electrode is exposed at the burned-through portion of the conduit, and the exposed carbon absorbs microwaves and millimeter waves, which greatly attenuates the transmitted and received power. Therefore, it may be impossible to accurately detect the molten liquid surface and the electrode length of the carbon electrode.

[0010] The present invention has been made in view of such circumstances, and an object of the present invention is to detect the molten liquid level more accurately and measure the electrode length of the carbon electrode more accurately in a resistance melting furnace even if the metal pipe burns through.

[0011] Technical solutions to the problem

[0012] In order to solve the above-mentioned problems, the present invention provides the following (1) to (11) apparatuses for measuring the electrode length of a carbon electrode in a resistance melting furnace.

[0013] (1) An apparatus for measuring the electrode length of a carbon electrode in a resistance furnace, wherein:

[0014] The resistance melting furnace melts the melt by inserting a carbon electrode hanging down into the furnace into the melt accumulated in the furnace and applying electricity to the carbon electrode. The device for measuring the electrode length of the carbon electrode in the resistance melting furnace comprises:

[0015] a conduit formed by connecting a plurality of metal conduit pieces and inserted so as to reach the lower end of the carbon electrode; and

[0016] A rangefinder is installed at the upper end of the conduit and comprises: a microwave or millimeter wave transceiver unit; and a waveguide, and

[0017] The inner diameter of the conduit is larger than the inner diameter of the waveguide of the rangefinder, and,

[0018] The conduit and the rangefinder are connected via a tapered structure having a cavity that expands in a tapered shape from the waveguide toward the conduit.

[0019] The microwave or the millimeter wave is transmitted from the lower end of the conduit toward the molten liquid surface of the melt, and the microwave or the millimeter wave reflected by the molten liquid surface is received to measure the distance between the rangefinder and the molten liquid surface.

[0020] (2) According to the device for measuring the electrode length of a carbon electrode in a resistance furnace as described in (1), the conduit pieces are connected to each other via threaded sockets.

[0021] (3) According to the device for measuring the electrode length of the carbon electrode in the resistance melting furnace described in (1), the conduit pieces are connected to each other using a conical joint, and the outer shape of the conical joint is: formed with two conical surfaces extending continuously from the central part with the largest diameter to both ends.

[0022] (4) According to the device for measuring the electrode length of a carbon electrode in a resistance melting furnace described in (1), the connection portion between the tapered structure and the conduit is closed by a member made of a material that is transparent to the microwave or the millimeter wave.

[0023] (5) According to the device for measuring the electrode length of a carbon electrode in a resistance melting furnace described in (1), an inert gas is supplied to the conduit to increase the internal pressure, and when the internal pressure rises sharply, it is determined that the conduit is in a blocked state, and the supply amount of the inert gas is increased to remove the blocked portion.

[0024] (6) According to the device for measuring the electrode length of the carbon electrode in the resistance melting furnace described in (1), a metal plate or a metal mesh is installed at the supply port for supplying the inert gas to the conduit, the metal plate is formed with holes with an opening diameter that microwaves or millimeter waves cannot penetrate, and the mesh of the metal mesh cannot be penetrated by microwaves or millimeter waves.

[0025] (7) According to the device for measuring the electrode length of a carbon electrode in a resistance melting furnace described in (1), the microwave or the millimeter wave is converted into a circularly polarized wave and transmitted toward the molten liquid surface.

[0026] (8) The device for measuring the electrode length of a carbon electrode in a resistance melting furnace according to (1), wherein the device includes a measurement mode for measuring the electrode length of the carbon electrode a plurality of times and obtaining an average value of the electrode length.

[0027] (9) A device for measuring the electrode length of a carbon electrode in a resistance melting furnace according to (1), wherein the device has a measuring mode for measuring the electrode length of the carbon electrode multiple times and performing arithmetic averaging on either or both of the received beat waveform and the distance spectrum waveform obtained by performing FFT processing on the received beat waveform.

[0028] (10) In the device for measuring the electrode length of a carbon electrode in a resistance melting furnace according to (1), the guide tube is made of SUS.

[0029] (11) According to the device for measuring the electrode length of a carbon electrode in a resistance melting furnace described in (1), the reflected signals appearing at equal distances from the conduit are observed.

[0030] In addition, in order to solve the above-mentioned problem, the present invention provides the following operating method (12).

[0031] (12) A method for operating a resistance melting furnace, wherein a carbon electrode hanging down into a melt accumulated in the furnace is inserted into the melt and electricity is applied to the carbon electrode to melt the melt.

[0032] The method for operating the resistance melting furnace comprises: obtaining the distance (L1) from the distance meter to the molten liquid surface by using the device for measuring the electrode length of the carbon electrode described in any one of (1) to (11); and

[0033] A second distance meter is arranged above the distance meter, a distance (L2) between the distance meter and the second distance meter is measured, and the distance (L3) from the second distance meter to the molten liquid surface is obtained by adding the distance (L2) to the obtained distance (L1),

[0034] The hanging position of the carbon electrode is controlled based on the distance (L3).

[0035] In the following description, the “device for measuring the electrode length of the carbon electrode in the resistance melting furnace” will also be simply referred to as the “measuring device”.

[0036] Effects of the Invention

[0037] According to the measuring device of the present invention, even if the metal pipe is burned through, the molten liquid level can be detected, and the electrode length of the carbon electrode can be measured more accurately.

[0038] Furthermore, according to the operation method of the present invention, even if the metal pipe is burned through, the electrode length of the carbon electrode can be measured more accurately, so the raising and lowering of the carbon electrode can be controlled more accurately, and efficient and stable operation can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a cross-sectional view schematically showing the device structure of an embodiment of the measuring device of the present invention along the axis line of the carbon electrode.

[0040] Figure 2 This is an enlarged view showing a threaded socket.

[0041] Figure 3 It is an enlarged view showing the conical structure and functional parts.

[0042] Figure 4 (A) is Figure 1 A partial enlarged view of part A. Figure 4 (B) is Figure 1 A partial enlarged view of part B. Figure 4 (C) is Figure 1 A partial enlarged view of part C.

[0043] Figure 5(A) is a cross-sectional view showing a conical joint. Figure 5 (B) is from Figure 5 A top view viewed from the AA direction.

[0044] Figure 6 (A) is a side view showing the positioning screw. Figure 6 (B) is from Figure 6 (A) Top view viewed from the BB direction.

[0045] Figure 7 This is a schematic diagram showing the rotation direction of the electric field during transmission and reception when circularly polarized microwaves or millimeter waves are used.

[0046] Figure 8 This is a graph showing the results of verification result 1.

[0047] Fig. 9 This is a graph showing the results of verification result 2.

[0048] Fig.10 This is a graph showing the results of verification result 3.

[0049] Fig.11 It is a figure for demonstrating the operation method of the resistance type melting furnace of this invention.

[0050] Fig.12 This is a schematic diagram showing an example of a resistance furnace. DETAILED DESCRIPTION

[0051] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0052] like Fig.12 As shown, in a resistance melting furnace, a plurality of carbon electrodes are inserted into a melt such as iron ore, and the melt is melted by passing electricity through the carbon electrodes. In the present invention, at least one carbon electrode functions as a "measurement device for the electrode length of the carbon electrode".

[0053] [Measurement device]

[0054] Figure 1 As shown in the figure, the measuring device 1 has a metal conduit 20 inserted into a conventional carbon electrode 10 and reaching the lower end of the carbon electrode 10, and a distance meter 30 is installed at the upper end of the conduit 20.

[0055] The carbon electrode 10 contains an electrode body 18 inside an electrode shell (metal cover) 15 composed of a metal cylinder. The electrode body 18 of the carbon electrode 10 is divided into an electrode firing part 18a, a coal tar melting part 18b, and an electrode material part 18c from the side close to the molten liquid surface 200 of the melt. When the melt is melted, the side of the electrode firing part 18a that contacts or faces the molten liquid surface 200 (hereinafter referred to as the "lower end") will be consumed. In order to compensate for this consumption, a mixture of carbon blocks and coal tar pitch as electrode materials is put into the opening at the upper end of the electrode shell 15. In addition, the electrode shell 15 is formed into one by connecting multiple electrode shell sheets (metal cover sheets) 16. The lower end will be consumed during melting, so it is configured to connect a new other electrode shell sheet (metal cover sheet) 16b on the lower electrode shell sheet (metal cover sheet) 16a. In addition, the reference numeral 17 is a seam of the electrode shell sheet 16.

[0056] The conduit 20 is a conduit formed by connecting a plurality of conduit pieces 21 into one piece using a joint 22. Similar to the carbon electrode 10, the lower end is consumed during melting, so a new conduit piece 21b is connected to the lower conduit piece 21a using the joint 22. When the conduit piece 21 is connected, a conduit clamp 25 is used to separate and reconnect the conduit 20 from the tapered structure 40 described later.

[0057] like Figure 2 As shown, the connector 22 (refer to Figure 1 ) is preferably a threaded socket 70. The threaded socket 70 has a thread groove 71 formed on its inner circumference, and accordingly, thread grooves 23 are formed on the outer circumference of both ends of the conduit piece 21 in a manner that engages with the thread groove 71 of the threaded socket 70. By using the threaded socket 70, the conduit piece 21 can be reliably connected, and linearity can be achieved when connecting multiple conduit pieces 21.

[0058] In addition, the electrode shell sheet 16 of the carbon electrode 10, the conduit sheet 21 of the conduit 20, and the joint 22 are preferably made of a metal with a higher melting point. As such a metal, for example, SUS304 can be preferably used from the perspectives of low cost, excellent processability and environmental resistance, and no rust. SUS304 reduces the propagation loss caused by the deterioration of the material quality, and enables stable measurement.

[0059] In addition, the waveguide 35 and the tapered structure 40 described later are also preferably made of SUS304.

[0060] The rangefinder 30 includes a microwave and millimeter wave transceiver unit (not shown) and is connected to the upper end of the catheter 20 via a tapered structure 40. Figure 1 and Figure 3As shown, the inner diameter of the catheter 20 is larger than the inner diameter of the waveguide 35 of the rangefinder 30, and the tapered structure 40 is a component having a tapered cavity 41 that expands from the end of the waveguide 35 of the rangefinder 30 toward the upper end of the catheter 20. In addition, the tapered structure 40 is connected to the catheter 20 through, for example, a threaded socket 70.

[0061] In addition, the cross-sections of the conduit 20 , the waveguide 35 , and the tapered structure 40 described above may be square in addition to the circular shape.

[0062] Microwaves and millimeter waves propagate well in the conduit 20, and more specifically, in the burnt-through portion of the conduit 20 (the exposed surface 12 described later), and the electrode length of the carbon electrode 10 can be measured more accurately. However, it is preferred that the inner diameter of the conduit 20 is larger than the inner diameter of the waveguide 35, but if the conduit 20 is too thick, the cost may increase. Specifically, when using a 79 GHz millimeter wave and the inner diameter of the waveguide 35 is In the case of

[0063]

[0064] In the case of a non-self-baking carbon electrode, a circular hole directly opened at the lower end of the carbon electrode is used as a substitute for the conduit 20 to measure the electrode length.

[0065] In addition, if Figure 3 As shown, it is preferred that the connection between the conical structure 40 and the conduit 20 is sealed by a functional component 50 made of a material that transmits detection waves, such as fluororesin. Since the conduit 20 is invaded by high heat from the molten liquid surface 200 or dust in the furnace, the internal components of the rangefinder 30 such as the transceiver unit are protected by the functional component 50.

[0066] The detection wave may be a microwave or a millimeter wave, but a wave with a higher frequency is preferred, and a millimeter wave is more preferred.

[0067] In the measuring device 1 thus constructed, the lower end of the carbon electrode 10 is consumed, and the lower end portion of the conduit 20 is subjected to high heat from the molten liquid surface 200, so that a portion of the conduit 20 and the joint 22 are burned through, exposing the interface with the carbon electrode 10.

[0068] For example, Figure 4 (A) indicates Figure 1 A magnified view of part A. Figure 4 (B) indicates Figure 1 An enlarged view of part B, Figure 4 (C) indicates Figure 1 The enlarged view of part C of Figure 4(A) is the portion where the conduit 20 begins to burn through and the boundary between the conduit 20 and the carbon electrode 10 begins to appear. Figure 4 (B) is the burnt-through portion of the joint 22. Figure 4 (C) is the portion after the conduit 20 is burned through.

[0069] like Figure 4 As shown in (A), the cross-sectional shape changes at the portion where the conduit 20 starts to burn through, but since the inner diameter of the conduit 20 is sufficiently larger than the wall thickness of the conduit 20, it can be said that there is substantially no influence on the measurement.

[0070] It should be noted that in Figure 4 In (A), the portion where the conduit 20 is burned through and the cross-sectional shape changes becomes a step-like shape, but the steps may not be at the same horizontal position over the entire circumference of the inner diameter, and may be different in the vertical direction in the figure. As shown in the figure, the conduit 20 and the joint 22 are burned through in a portion closer to the molten liquid surface 200 than the lower half of the A portion, and the boundary surface between the conduit 20 and the carbon electrode 10 is exposed as shown by the reference numeral 12.

[0071] In the following description, the portion where the pipe 20 or the joint 22 is burned through and the carbon electrode 10 is exposed is referred to as an “exposed surface 12 ”.

[0072] Generally, when microwaves and millimeter waves propagate in a carbon tube, the conductivity of the wall surface is low, so the propagation loss increases and the transmission and reception signals are absorbed. Since the exposed surface 12 is carbon, the microwaves and millimeter waves are significantly attenuated during the propagation of the exposed surface 12. However, as described above, the inner diameter of the conduit 20 is made larger than the inner diameter of the waveguide 35, and the excitation of unnecessary higher-order modes other than the circular TE11 mode constituting the circularly polarized wave is suppressed as much as possible, and the propagation of the circular TE11 mode is mainly maintained, thereby reducing the propagation loss and reducing the degradation of the distance measurement accuracy.

[0073] Therefore, microwaves and millimeter waves from the transceiver unit of the rangefinder 30 are Figure 1 As shown by the reference numeral M in the figure, the microwave propagates in the waveguide 35, the cavity 41 of the conical structure 40, and the conduit 20, and propagates well without being greatly attenuated at the exposed surface 12, and is sent from the lower end of the conduit 20 to the molten liquid surface 200. Then, it is reflected by the molten liquid surface 200, and is received by the transceiver unit of the range finder 30 along the opposite path, thereby detecting the molten liquid surface 200. Then, based on the time difference between transmission and reception, the distance from the range finder 30 to the molten liquid surface 200, that is, the electrode length of the carbon electrode 10 is obtained. Conventionally, microwaves and millimeter waves are greatly attenuated at the exposed surface 12, but in the measuring device 1 of the present invention, since the attenuation at the exposed surface 12 is suppressed, the molten liquid surface 200 can be detected more accurately, and the electrode length of the carbon electrode 10 can be obtained.

[0074] As described above, the detection wave propagates well on the exposed surface 12 with low attenuation. However, in order to make the propagation better, it is also preferable to use Figure 5 The conical connector 80 is shown as the connector 22. In addition, Figure 5 (A) is a cross-sectional view of the conical joint 80, Figure 5 (B) is from Figure 5 (A) is a top view observed from the AA direction. Figure 5 As shown in (A), the central portion 81 of the tapered joint 80 is the largest outer diameter, is formed into a cylindrical shape with a predetermined width, and has two tapered surfaces 82 extending continuously from the central portion 81 to both ends, and has a generally barrel-shaped outer shape as a whole.

[0075] In addition, a stepped stopper 83 having the same width as the wall thickness of the duct piece 21 protrudes in an annular shape from the inner peripheral surface of the center portion in the longitudinal direction of the tapered joint 80, and the duct piece 21 is inserted so that its end abuts against the stopper 83. Here, the stopper 83 has the same wall thickness as the duct piece 21, so that the propagation of microwaves and millimeter waves is not hindered.

[0076] In addition, the lengthwise dimensions H1 and H2 of the central portion 81 and the tapered surface 82 of the tapered joint 80 are preferably equal to or greater than the wavelength of microwaves or millimeter waves. The lengths H2 of the two tapered surfaces 82 may be the same or different.

[0077] The maximum outer diameter D of the tapered joint 80 is preferably set to a size that does not generate high-order modes of microwaves and millimeter waves.

[0078] And, if Figure 5 As shown in (B), in the central portion 81 of the tapered joint 80, there are formed at multiple locations at equal intervals in the circumferential direction so as to penetrate the inner circumferential surface for installation. Figure 6 The threaded hole 85 of the set screw 90 is shown. In addition, Figure 6 (A) is a side view showing the positioning screw 90. Figure 6 (B) is from Figure 6 (A) Top view observed from the BB direction.

[0079] The length L of the set screw 90 in the longitudinal direction is longer than the wall thickness of the central portion 81 of the tapered joint 80, and a thread 91 is formed on the outer peripheral surface to engage with the thread teeth of the threaded hole 85 of the tapered joint 80. In addition, a hexagonal hole 95 is formed on one end surface. In addition, the material of the set screw 90 is the same as that of the tapered joint 80 and the duct piece 21.

[0080] In order to connect the duct piece 21 using such a tapered joint 80 and a set screw 90, after the duct piece 21 is inserted until it abuts against the stopper 83 of the tapered joint 80, the set screw 90 is installed in the threaded hole 85 of the tapered joint 80 and screwed in until the end surface of the set screw 90 reaches the outer peripheral surface of the duct piece 21, thereby fixing the duct piece 21. Then, the portion of the set screw 90 protruding from the threaded hole 85 of the tapered joint 80 is cut off by a grinder or the like, and the tapered joint 80 is processed so that no unevenness is formed on the outer peripheral surface.

[0081] By using the conical joint 80 as the joint 22, Figure 4 In the exposed surface 12 shown in (B), the step portion 12a disappears, and the reflection of microwaves and millimeter waves at the step portion 12a disappears.

[0082] The measuring device 1 is configured as described above, but various modifications are possible, for example, Figure 1 As shown, it is preferred to supply nitrogen (N2) or an inert gas between the tapered structure 40 of the conduit 20 and the rangefinder 30 to increase the internal pressure of the conduit 20. The lower end of the conduit 20 is open, so sometimes molten metal flows in, and by increasing the internal pressure of the conduit 20, the inflow of molten metal is prevented. In addition, sometimes the lower end of the conduit 20 melts and blocks the conduit 20, and the internal pressure of the conduit 20 rises sharply. When a sharp rise in the internal pressure is detected, the supply of nitrogen or inert gas can also be increased to remove the substance (blockage) blocking the conduit 20. In addition, the adjustment of the internal pressure is performed by the pressure regulator 60. In addition, reference numeral 61 is a pressure gauge.

[0083] In addition, if Figure 3 As shown in FIG. 1 , a metal inert gas intake member 65 having a plurality of fine holes 63 may be installed at the intake port 62 for introducing nitrogen gas or inert gas into the conduit 20. Although not shown in the figure, the inert gas intake member 65 may be a metal mesh. The opening diameter of the fine holes 63 is set to a diameter that microwaves and millimeter waves do not penetrate and the inert gas can flow easily, for example, in the case of 79 GHz millimeter waves, it is set to The mesh size of the metal mesh is also the same. The inert gas intake member 65 can prevent microwaves and millimeter waves from leaking from the intake port 62.

[0084] In addition, it is preferable to use circularly polarized microwaves or millimeter waves M'. Figure 7 As shown, the rangefinder 30 includes a receiving circuit 31, a transmitting circuit 32, and a circularly polarized wave generator 33. The receiving circuit 31 receives a linearly polarized wave having an electric field direction different from that of the linearly polarized wave transmitted from the transmitting circuit 32. By utilizing this characteristic, the receiving circuit 31 and the transmitting circuit 32 are separated, and the circularly polarized wave generator 33 is interposed between the receiving circuit 31 and the waveguide 35, thereby improving the accuracy of signal processing.

[0085] exist Figure 7 On the right side of the figure, arrows are used to indicate the direction of the electric field of the detection wave M' in each part of the measuring device 1. The receiving circuit 31 and the transmitting circuit 32 both receive or transmit linear polarized waves whose electric field is oriented in a certain direction. When the received signal whose electric field is oriented in the opposite direction to the circular polarization wave passes through the circular polarization wave generator 33, due to the effect of the circular polarization wave generator 33, it becomes a linear polarized wave whose electric field direction is different from that of the transmitted wave.

[0086] Furthermore, the microwave or millimeter wave M whose electric field rotates in a certain direction (right-handed in the figure) is transmitted from the transmission circuit 32 to the conical structure 40 through the waveguide 35 by the circularly polarized wave generator 33. O ', in the state of the clockwise electric field, it propagates in the conduit 20 and further on the exposed surface 12 of the carbon electrode 10 and is sent to the molten liquid surface 200.

[0087] Microwaves and millimeter waves M are circularly polarized waves (right-handed circularly polarized waves or true circularly polarized waves) whose electric field is directed to the right relative to the propagation direction. O If reflected by the melt surface 200, the microwave or millimeter wave M becomes a left-handed circularly polarized wave (negative circularly polarized wave) of an electric field whose rotation direction is counterclockwise with respect to the propagation direction of the microwave or millimeter wave. r '. Then, it is sent to the rangefinder 30 through the exposed surface 12 of the carbon electrode 10, the conduit 20, the conical structure 40, and the waveguide 35 in the state of the left-handed electric field, and passes through the circular polarization wave generator 33 in the reverse direction. At this time, it passes through the circular polarization wave generator 33 and becomes a linear polarization wave with an electric field direction different from that of the transmitted linear polarization wave, so it is received by the receiving circuit 31.

[0088] In this way, by using the circularly polarized microwaves or millimeter waves M′, only the microwaves or millimeter waves M′ from the transmission circuit 32 are received in the reception circuit 31. O 'Microwave and millimeter wave M with different electric fields r ', so the transmitted wave and the received wave can be almost completely separated, thus greatly improving the measurement accuracy.

[0089] In order to reduce the noise level and improve the SN ratio, the noise floor power can be reduced by 1 / N by repeating the measurement a plurality of times (N times) and finding the average value.

[0090] Alternatively, the noise floor power may be reduced by 1 / N by performing multiple measurements and adding and averaging either or both of the obtained reception beat waveform and the range spectrum waveform obtained by performing FFT processing on the reception beat waveform.

[0091] (Verification result 1)

[0092] imitate Figure 1 The measuring device 1 was used to connect 6 SUS304 pipes with a total length of 2m as a pipe piece to make a SUS304 pipe with a total length of 12m. Then, an iron plate, which was used as the molten iron layer, was used to cover the opening of one end of the SUS304 pipe. Millimeter waves were sent from the waveguide of the rangefinder installed at the other end to measure the signal strength at each distance. The results are shown in Figure 8 .

[0093] In the graph shown, the peak of the signal intensity is caused by a tiny reflection at the joint of the SUS304 pipe. Moreover, this peak appears regularly every 2m, and a similar peak also appears at a distance of 12m, which shows that the millimeter wave propagates throughout the entire length of the SUS304 pipe.

[0094] Furthermore, since peaks corresponding to joints of the catheter piece can be detected every 2 m, by observing peaks appearing at equal intervals and fixed reflections appearing far away, blocked sites in the catheter and sites where the catheter piece has shifted can be estimated.

[0095] (Verification result 2)

[0096] A carbon pipe with the same diameter and a total length of 2 m was connected to one end of a SUS304 conduit equivalent to that in Verification Result 1, and the opening of the carbon pipe was covered with an iron plate. Figure 1 The exposed surface 12 of the carbon electrode 10 in the measuring device 1 is then transmitted from the waveguide of the distance meter attached to the other end of the SUS pipe, and the signal intensity at each distance is measured.

[0097] The results are shown in Fig. 9 .

[0098] In the graph shown in the figure, similarly to verification result 1, peaks appear every 2 m, corresponding to the SUS304 pipe. In addition, a peak appears at the joint at a distance of 12 m, which is the connection between the SUS304 pipe and the carbon pipe. Furthermore, a peak also appears at a distance of 14 m from the iron plate that shields the carbon pipe, indicating that millimeter waves also propagate in the carbon pipe.

[0099] (Verification result 3)

[0100] Similar to Verification Result 2, a carbon tube and a SUS304 tube were connected, and an iron plate was placed 1 m away from the opening of the carbon tube. Then, millimeter waves were transmitted from the waveguide of the rangefinder installed at the other end of the SUS304 tube, and the signal strength at each distance was measured. The results are shown in Fig.10 .

[0101] In the graph shown in the figure, similar to the verification result 2, the peaks appear every 2 m, corresponding to the SUS304 pipe and the carbon pipe. In addition, the peak also appears at a distance of 15 m from the carbon pipe 1 m, which shows that the millimeter wave propagates in the carbon pipe and even in the air. This means that it can also be measured stably by propagating from the lower end of the pipe 20 that has been burned through to the exposed surface 12.

[0102] In the above verification results, the peaks generated by the joints of the SUS304 tube pieces were observed. Therefore, in the measuring device 1, the number of tube pieces 21 and the overall length of the tube 20 can be known by simply counting the number of peaks. In addition, since the peaks of the reflected waves appear every 2 m, the position of the joints can be measured without correction. This is because the signal speed (group velocity) of the circular TE11 mode is approximately equal to the speed of light (the speed of the plane wave). That is, it means that the inner diameter of the tube 20 is sufficiently large relative to the inner diameter of the waveguide 35.

[0103] [Operation method]

[0104] The present invention also relates to a method for operating a resistance furnace using the above-mentioned measuring device 1. First, Fig.11 As shown, the electrode length, that is, the distance (L1) of the conduit 20, that is, the carbon electrode 10, is obtained from the distance meter 30 using the measuring device 1.

[0105] In addition, a plate-shaped position measuring member 38 is mounted on the rangefinder 30, and a second rangefinder 210 is provided above the rangefinder 30 to measure the interval distance (L2) between the second rangefinder 210 and the rangefinder 30. As the second rangefinder 210, a general microwave or millimeter wave rangefinder can be used, microwaves or millimeter waves are transmitted from the antenna 220 toward the position measuring member 38, and microwaves or millimeter waves reflected by the position measuring member 38 are received, and the interval distance (L2) is calculated based on the time difference.

[0106] Then, the distance (L1) and the spacing distance (L2) are added to obtain the distance (L3), and the hanging position of the carbon electrode 10 is controlled based on a distance signal of the distance (L3).

[0107] Since the carbon electrode 10 gradually becomes shorter due to the consumption of the melt, it is necessary to gradually lower the carbon electrode 10 accordingly. Therefore, as described above, by fixing the second distance meter 210 at a place where the height does not change, such as the top of the furnace equipment, as a reference position, and knowing the distance (L3) from the reference position to the lower end of the carbon electrode 10, the hanging position of the carbon electrode 10 can be controlled.

[0108] This enables more stable operation.

[0109] Various embodiments have been described above, but the present invention is certainly not limited to these examples. As long as one skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present invention. In addition, within the scope of not departing from the gist of the invention, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined.

[0110] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2023-115847) filed on July 14, 2023, and the contents thereof are incorporated herein by reference.

[0111] Description of Reference Numerals

[0112] 1. Measurement device

[0113] 10 Carbon Electrode

[0114] 12 Show your face

[0115] 12a Step section

[0116] 15 Electrode shell (metal cover)

[0117] 16, 16a, 16b electrode shell sheet (metal cover sheet)

[0118] 18 Electrode body

[0119] 18a Electrode firing section

[0120] 18b Coal tar melting section

[0121] 18c Electrode Materials Department

[0122] 20 Catheter

[0123] 21, 21a, 21b catheter piece

[0124] 22 connector (interface)

[0125] 23, 71 thread groove

[0126] 25 Catheter clamp

[0127] 30 Rangefinder

[0128] 31 Receiving Circuit

[0129] 32 Transmitting Circuit

[0130] 33 Circularly polarized wave generator

[0131] 35 Waveguide

[0132] 38 Position measurement parts

[0133] 40 Cone Structure

[0134] 41 Cavity

[0135] 50 Functional components

[0136] 60 Pressure regulator

[0137] 62 Entrance

[0138] 63 Pores

[0139] 65 Inert gas intake components

[0140] 70 threaded socket

[0141] 80 Conical Connector

[0142] 81 Central part

[0143] 82 Cone

[0144] 83 Stopper

[0145] 85 threaded hole

[0146] 90 Set screw

[0147] 91 Thread

[0148] 95 Hexagonal hole

[0149] 120 Electrode lifting device

[0150] 200 Melt level

[0151] 210 Second Rangefinder

[0152] 220 Antenna

Claims

1. A device for measuring the electrode length of a carbon electrode in a resistance furnace, characterized in that: The resistance melting furnace melts the melt by inserting a carbon electrode hanging down into the furnace into the melt accumulated in the furnace and applying electricity to the carbon electrode. The device for measuring the electrode length of the carbon electrode in the resistance melting furnace comprises: a conduit formed by connecting a plurality of metal conduit pieces and inserted so as to reach the lower end of the carbon electrode; and A rangefinder is installed at the upper end of the conduit and comprises: a microwave or millimeter wave transceiver unit; and a waveguide, and The inner diameter of the conduit is larger than the inner diameter of the waveguide of the rangefinder, and, The conduit and the rangefinder are connected via a tapered structure having a cavity that expands in a tapered shape from the waveguide toward the conduit. The microwave or the millimeter wave is transmitted from the lower end of the conduit toward the molten liquid surface of the melt, and the microwave or the millimeter wave reflected by the molten liquid surface is received to measure the distance between the rangefinder and the molten liquid surface.

2. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The conduit pieces are connected to each other via threaded sockets.

3. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The conduit pieces are connected to each other by a tapered joint having an outer shape in which two tapered surfaces are formed extending continuously from a center portion having a maximum diameter toward both ends.

4. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: A connection portion between the tapered structure and the conduit is closed by a member made of a material that is permeable to the microwaves or the millimeter waves.

5. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: An inert gas is supplied to the conduit to increase the internal pressure, and when the internal pressure rises suddenly, it is determined that the conduit is in a blocked state, and the supply amount of the inert gas is increased to remove the blocked portion.

6. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: A metal plate or a metal mesh is attached to a supply port for supplying an inert gas to the conduit. The metal plate has holes with an opening diameter that prevents microwaves or millimeter waves from entering. The mesh of the metal mesh is not penetrated by microwaves or millimeter waves.

7. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The microwave or the millimeter wave is made into a circularly polarized wave and is transmitted toward the molten liquid surface.

8. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The measuring device includes a measuring mode for measuring the electrode length of the carbon electrode a plurality of times and obtaining an average value of the electrode length.

9. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The measuring device has a measuring mode for measuring the electrode length of the carbon electrode a plurality of times and performing arithmetic averaging on one or both of the obtained reception beat waveform and the range spectrum waveform obtained by performing FFT processing on the reception beat waveform.

10. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: The catheter is made of SUS.

11. The device for measuring the electrode length of a carbon electrode in a resistance furnace according to claim 1, characterized in that: Observe the reflected signals appearing at equal intervals from the catheter.

12. A method for operating a resistance melting furnace, wherein the resistance melting furnace melts the melt by inserting a carbon electrode hanging down into the furnace into the melt accumulated in the furnace and applying electricity to the carbon electrode, The operating method of the resistance furnace is characterized in that: The distance (L1) from the distance meter to the molten liquid surface is obtained by using the electrode length measuring device of the carbon electrode according to any one of claims 1 to 11, and A second distance meter is arranged above the distance meter, a distance (L2) between the distance meter and the second distance meter is measured, and the distance (L3) from the second distance meter to the molten liquid surface is obtained by adding the distance (L2) to the obtained distance (L1), The hanging position of the carbon electrode is controlled based on the distance (L3).

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