JP2023170124A - Device and method for measuring carbon electrode length in electric resistance melting furnace, taper union used in the measurement device, and method for connecting taper union to metallic pipe - Google Patents

Abstract

To correctly measure a length of a carbon electrode by eliminating a measurement error derived from an outer shape of a union melted down together with a metallic pipe.SOLUTION: A carbon electrode length measurement device includes: a metallic pipe group which is put through at least one carbon electrode, constituted by connecting a plurality of metallic pipes by taper unions which are formed of the same material as that of the metallic pipes and have an outer shape without a step part, so as to reach a lower end of the carbon electrode; and a micro-wave transceiver to be mounted on an upper end of the metallic pipe group. A micro-wave is transmitted from the transceiver. The micro-wave is propagated in a cavity which is formed by melting-down of the metallic pipe or the taper union or both of the metallic pipe and taper union at a lower end part of the carbon electrode and also in a propagation route which is constituted by the metallic pipe group other than the cavity. Then, the micro-wave reflected against a melting liquid surface of the melted object is received so as to obtain a length of the carbon electrode.SELECTED DRAWING: Figure 2

Description

The present invention measures the length of the carbon electrode in an electric resistance melting furnace in which a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and electricity is applied to the carbon electrode to melt the material to be melted. The present invention relates to an apparatus and a measuring method. The present invention also relates to a taper union used in the measuring device, and a method for connecting the taper union and a metal pipe.

Electric resistance melting furnaces are used in which materials to be melted, such as iron ore, are put into the furnace, a carbon electrode is inserted into the accumulated material to be melted, the material is discharged, the material to be melted is melted, and the molten material is recovered. . In this electric resistance melting furnace, the carbon electrode gradually becomes shorter as discharge occurs, so it is necessary to measure the length of the carbon electrode and control the position of the carbon electrode.

Here, in Patent Document 1, the applicant inserts a metal pipe as a waveguide reaching the lower end of the carbon electrode inside the carbon electrode, and attaches a microwave transmitter/receiver to the upper end of the metal pipe. , the length of the metal pipe is measured by transmitting microwaves and receiving the microwaves reflected at the bottom end of the metal pipe, and the measured length of the metal pipe is determined as the length of the carbon electrode.Electrical resistance A method for measuring electrode length in a type melting furnace is proposed.

As mentioned above, the carbon electrode gradually becomes shorter due to discharge, and the metal pipe at the lower end also melts down accordingly. Therefore, as described in Patent Document 2, for example, a plurality of short metal pipes are connected with a union (reference numeral 78 in FIG. 4 of the same document) to form a single metal pipe group, and a short It is required to operate while adding metal pipes.

However, the union melts down along with the metal pipe, and after these melt down, a cavity corresponding to the external shape of the metal pipe and union remains in the carbon electrode. In this case, the microwave propagates in this cavity as well, so if there is a step in the cavity, the microwave will be reflected at the step, making it impossible to accurately measure the length of the carbon electrode. In particular, a general union for connecting metal pipes, as shown in Patent Document 2, has a complicated external shape, and there are steps at the corners of the nut, and there are steps in the hollow part after melting. Therefore, it is not suitable for measuring the length of carbon electrodes.

Patent No. 5671744 European Patent No. 3295209

Therefore, the present invention provides a measuring device and method for measuring the length of a carbon electrode by inserting a metal pipe inside a carbon electrode and receiving microwaves reflected at the lower end of the metal pipe. It is an object of the present invention to provide a measuring device and a measuring method that accurately measure the length of a carbon electrode by eliminating measurement errors caused by the outer shape of a melted union.

In order to solve the above problems, the present invention provides the following.

(1) In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the carbon electrode is energized to melt the material to be melted. A device for measuring the
A plurality of metal pipes are made of the same material as the metal pipes and have a tapered union with an external shape without a stepped portion so as to be inserted through at least one of the carbon electrodes and reach the lower end of the carbon electrode. A group of metal pipes connected together,
a microwave transmitting and receiving device attached to the upper end of the group of metal pipes;
transmitting the microwave from the transmitting/receiving device;
At the lower end of the carbon electrode, a cavity is formed by melting down the metal pipe, the tapered union, or both the metal pipe and the tapered union, and the group of metal pipes other than the cavity. Propagating the microwave through a propagation path configured,
A carbon electrode length measuring device in an electric resistance melting furnace, which measures the length of the carbon electrode by receiving the microwave reflected from the melt surface of the object to be melted.
(2) In the device for measuring the length of a carbon electrode in an electric resistance melting furnace according to (1) above, a taper union used to connect the metal pipes,
A tapered union that is made of the same material as the metal pipe and has an external shape with no stepped portions.
(3) The tapered union according to (2) above, which has a screw hole reaching the inner peripheral surface through which the metal pipe is inserted, and a set screw is attached to the screw hole.
(4) A method for connecting the tapered union according to (3) above and the metal pipe, comprising:
After inserting the metal pipe into the taper union and installing the set screw in the screw hole, the part of the set screw protruding from the outer peripheral surface of the taper union is removed. Connection method.
(5) In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the carbon electrode is energized to melt the material to be melted. A method of measuring
Using the carbon electrode length measuring device in the electric resistance melting furnace described in (1) above,
A carbon electrode in an electric resistance melting furnace, which receives the microwave transmitted from the transmitting/receiving device, propagates through the propagation path, and is reflected on the melt surface of the object to be melted to determine the length of the carbon electrode. How to measure length.

In the present invention, one metal pipe group is constructed by connecting a plurality of metal pipes with a tapered union having an external shape with no stepped portion so as to reach the lower end of the carbon electrode inside the carbon electrode. Insert. Therefore, the cavity of the carbon electrode that is formed when the metal pipe or tapered union melts down also has a shape without a stepped portion. As a result, there is no problem in the propagation of microwaves in this cavity, and the length of the carbon electrode can be accurately measured.

FIG. 1 is a diagram showing an example of the overall structure of an electric resistance melting furnace. FIG. 2 is a cross-sectional view showing a carbon electrode inserted through a group of metal pipes. FIG. 3(A) is a cross-sectional view showing the tapered union, and FIG. 3(B) is a plan view seen from the AA direction in FIG. 3(A). FIG. 4(A) is a side view showing the set screw, and FIG. 4(B) is a plan view seen from the BB direction in FIG. 4(A).

FIG. 1 is a diagram showing an example of the overall structure of an electric resistance melting furnace. As shown in the figure, a carbon electrode 101 hanging inside an electric resistance melting furnace 100 is inserted into deposited iron ore 102 using a lifting device 120, and power is supplied to the carbon electrode 101 from a power source 110 to melt the iron ore. Three layers of melted and unmelted iron ore 102, a molten slag layer 103, and a molten iron layer 104 are formed, and the molten slag is collected from the slag discharge port 105, and the molten iron is collected from the tap port 106.
As shown in FIG. 2, the carbon electrode 101 has an electrode case 150 filled with an electrode body 160 made of a mixture of carbon lumps and coal tar pitch, and is powered by a power source 110 through an electrode holder 180 shown in FIG. Ru. Further, the lower end 201 of the carbon electrode 101 is in contact with the liquid surface of the molten iron layer 104.

Further, by inserting a metal pipe group 200 reaching the lower end of the carbon electrode 101a into at least one carbon electrode 101a, and further installing a microwave transmitter/receiver 300 at the upper end of the metal pipe group 200, The carbon electrode 101a is made to function as an electrode for measuring electrode length. Then, when the microwave is transmitted from the transceiver 300, the microwave propagates inside the metal pipe group 200 and is reflected by the liquid surface of the molten iron layer 104 when it reaches the lower end 201 of the carbon electrode 101a. Then, the reflected microwave propagates again inside the metal pipe group 200 and is received by the transceiver 300. Then, the length of the metal pipe group 200 is determined from the time difference between transmission and reception of microwaves.

Furthermore, since the lower ends of the metal pipe group 200 are open, in order to prevent molten slag and molten iron from flowing in, nitrogen gas or inert Gas may be supplied to increase the internal pressure of the pipe. Note that the internal pressure is adjusted by a pressure regulator 250.

Since the lower end of the metal pipe group 200 is consumed during melting, a joint 210 is inserted between the metal pipe group 200 and the transmitter/receiver 300 to supplement the consumed amount. As shown in FIG. 2, the method of adding a short metal pipe is to add a short metal pipe 200a from above the carbon electrode 101a, connect it with a tapered union 230 made of the same material as the short metal pipe 200a, and make one long metal pipe. They are configured as a group 200, and are added sequentially from the top.

In addition, when the short metal pipe 200a located at the lower end 201 of the carbon electrode 101a of the metal pipe group 200 and furthermore the tapered union 230 melt down, the short metal pipe 200a located at the lower end 201 of the carbon electrode 101a of the metal pipe group 200 melts down, and the short metal pipe 200a located at the lower end 201 of the carbon electrode 101a is melted down. A cavity 240 corresponding to the external shape of the pipe 200a and the tapered union 230 is formed.

In the illustrated example, the tapered union 230 melts down together with the metal pipe 200a, but either the metal pipe 200a or the tapered union 230 may melt down, and the shape of the cavity 240 also changes accordingly. It will be as per your requirement.

Here, if a general union such as the one described above (see reference numeral 78 in FIG. 4 of Patent Document 2) is used as a union for connecting a plurality of short metal pipes 200a, there will be a step in the external shape of the union. As a result, this stepped portion is also formed in the cavity 240 of the carbon electrode 101a. The microwaves that have propagated through the metal pipe group 200 continue to propagate through the cavity 240 formed in the carbon electrode 101a, but at this time, they are reflected at the stepped portion of the cavity 240. As a result, the microwave, which should be reflected at the liquid surface of the molten iron layer 104, is no longer reflected at the liquid surface, and therefore the original length of the carbon electrode 101a cannot be accurately measured. .

Therefore, in this embodiment, as shown in FIGS. 3(A) and 3(B), the outer shape of the union has no stepped portion. Note that FIG. 3(A) is a cross-sectional view of the tapered union 230 according to this embodiment in which the external shape of the union is a shape without a stepped portion, and FIG. 3(B) is a cross-sectional view of A- It is a top view seen from the A direction. As shown in FIG. 3(A), the tapered union 230 according to the present embodiment is formed into a cylindrical shape with a central portion 231 having the maximum outer diameter and a predetermined width, and is continuous from the central portion 231 to both ends. Two tapered surfaces 232, 232 are formed which extend as shown in FIG.

Further, a step-shaped stopper 233 having the same width as the wall thickness of the metal pipe 200a protrudes in an annular shape from the inner peripheral surface of the center portion in the longitudinal direction of the tapered union 230, and the metal pipe 200a is The part is inserted so as to come into contact with the stopper 233. Here, since the stopper 233 has the same thickness as the metal pipe 200a, it does not interfere with the propagation of microwaves.

It is preferable that the longitudinal dimensions H1 and H2 of the central portion 231 and the tapered surface 232, that is, the length of each portion along the axis of the metal pipe 200a, are each longer than the wavelength of the microwave. If each of the dimensions H1 and H2 is within this range, propagation of microwaves in the tapered union 230 and the cavity 240 will not be hindered. Note that the lengths H2 of the two tapered surfaces 232 may be the same or different.

Furthermore, since the maximum outer diameter D of the tapered union 230 becomes the inner diameter of the cavity 240, it is preferable to set the dimension so that the microwave mode does not convert, that is, the dimension that does not generate a higher-order microwave mode.

Furthermore, as shown in FIG. 3(B), the center portion 231 of the tapered union 230 has screw holes 235 at multiple locations at equal intervals along the circumferential direction for mounting the set screws 270 shown in FIG. It is formed to penetrate to the inner peripheral surface.

The set screw 270 has a longitudinal length L longer than the wall thickness of the central portion 231 of the tapered union 230, and has a screw 272 formed on its outer circumferential surface that engages with the thread of the threaded hole 235 of the tapered union 230. There is. Further, a hexagonal hole 275 is formed in one end surface. The set screw 270 is made of the same material as the taper union 230 and the metal pipe 200a.

The metal pipe 200a can be fixed and connected by such a taper union 230 and set screw 270. That is, after inserting a new metal pipe 200a until it contacts the stopper 233 of the taper union 230, the set screw 270 is installed in the threaded hole 235 of the taper union 230, so that the end surface of the set screw 270 is aligned with the outer periphery of the metal pipe 200a. Fix the metal pipe 200a by inserting screws until it reaches the surface. Thereafter, the portion of the set screw 270 protruding from the threaded hole 235 of the tapered union 230 is cut off using a sander or the like, and the outer peripheral surface of the tapered union 230 is processed so as not to have any unevenness.

As described above, by using the tapered union 230, which has an external shape with no stepped portion, as a union for connecting a plurality of short metal pipes, there is no stepped portion in the cavity 240 of the carbon electrode 101a, and the length of the carbon electrode 101a is eliminated. can be determined accurately.

Furthermore, as shown in FIG. 2, the cavity 240 of the carbon electrode 101a also includes the outer peripheral surface of the melted metal pipe 200a, so the interface between the lower end of the melted metal pipe 200a and the upper end 240a of the cavity 240 A step 245 corresponding to the thickness of the metal pipe 200a is formed. The thicker the metal pipe 200a, the larger the step 245. Therefore, it is preferable to use the metal pipe 200a with a wall thickness of 2 mm or less so as not to affect the propagation of microwaves.

100 Electric resistance melting furnace 101, 101a Carbon electrode 200 Metal pipe group 200a Metal pipe 201 Lower end (of metal pipe group) 230 Taper union 231 Center portion 232 Tapered surface 233 Stopper 235 Screw hole 240 Cavity 270 Set screw 300 Transmission/reception vessel

(1) In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the carbon electrode is energized to melt the material to be melted. A device for measuring the
A plurality of metal pipes are formed with two tapered surfaces continuously extending from the center portion having the maximum diameter to both ends so as to be inserted through at least one of the carbon electrodes and reach the lower end of the carbon electrode. A group of metal pipes connected by externally shaped tapered unions,
a microwave transmitting and receiving device attached to the upper end of the group of metal pipes, and
transmitting the microwave from the transmitting/receiving device;
At the lower end of the carbon electrode, a cavity is formed by melting down the metal pipe, the tapered union, or both the metal pipe and the tapered union, and the group of metal pipes other than the cavity. Propagating the microwave through a propagation path configured,
A carbon electrode length measuring device in an electric resistance melting furnace, which measures the length of the carbon electrode by receiving the microwave reflected from the melt surface of the object to be melted.
(2) In the device for measuring the length of a carbon electrode in an electric resistance melting furnace according to (1) above, a taper union used to connect the metal pipes ,
A tapered union that has an external shape with two tapered surfaces that extend continuously from the center portion, which is the maximum diameter, to both ends .
(3) The tapered union according to (2) above, characterized in that the tapered union has a screw hole reaching the inner peripheral surface through which the metal pipe is inserted, and a set screw is attached to the screw hole.
(4) A method for connecting the tapered union according to (3) above and the metal pipe, comprising:
After inserting the metal pipe into the taper union and installing the set screw in the screw hole, a portion of the set screw protruding from the outer circumferential surface of the taper union is removed. Connection method.
(5) In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the carbon electrode is energized to melt the material to be melted. A method of measuring
Using the carbon electrode length measuring device in the electric resistance melting furnace described in (1) above,
A carbon electrode in an electric resistance melting furnace, which receives the microwave transmitted from the transmitting/receiving device, propagates through the propagation path, and is reflected on the melt surface of the object to be melted to determine the length of the carbon electrode. How to measure length.

Claims (5)

In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the length of the carbon electrode is measured by applying current to the carbon electrode to melt the material to be melted. A device for
A plurality of metal pipes are made of the same material as the metal pipes and have a tapered union with an external shape without a stepped portion so as to be inserted through at least one of the carbon electrodes and reach the lower end of the carbon electrode. A group of metal pipes connected together,
a microwave transmitting and receiving device attached to the upper end of the group of metal pipes, and
transmitting the microwave from the transmitting/receiving device;
At the lower end of the carbon electrode, a cavity is formed by melting down the metal pipe, the tapered union, or both the metal pipe and the tapered union, and the group of metal pipes other than the cavity. Propagating the microwave through a propagation path configured,
A carbon electrode length measuring device in an electric resistance melting furnace, which measures the length of the carbon electrode by receiving the microwave reflected from the melt surface of the object to be melted. The carbon electrode length measuring device in an electric resistance melting furnace according to claim 1, comprising: a tapered union used to connect the metal pipes;
A tapered union that is made of the same material as the metal pipe and has an external shape with no stepped portions. 3. The tapered union according to claim 2, further comprising a screw hole that reaches the inner circumferential surface through which the metal pipe is inserted, and a set screw is installed in the screw hole. A method of connecting the tapered union according to claim 3 and the metal pipe, comprising:
After inserting the metal pipe into the taper union and installing the set screw in the screw hole, a portion of the set screw protruding from the outer circumferential surface of the taper union is removed. Connection method. In an electric resistance melting furnace, a carbon electrode hanging down into the furnace is inserted into the material to be melted deposited in the furnace, and the length of the carbon electrode is measured by applying current to the carbon electrode to melt the material to be melted. A method of
Using the carbon electrode length measuring device in an electric resistance melting furnace according to claim 1,
A carbon electrode in an electric resistance melting furnace, which receives the microwave transmitted from the transmitting/receiving device, propagates through the propagation path, and is reflected on the melt surface of the object to be melted to determine the length of the carbon electrode. How to measure length.

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