JP2010230605A - Device for detecting foreign substance in pitch coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of concurrently discriminating whether a specimen is a pitch coke, a metallic foreign substance, or a nonmetallic foreign substance. <P>SOLUTION: Disposed in a pitch coke conveying direction are detection devices which run a current to a resonance circuit (detection coil), generate an eddy current to the specimen by a magnetic flux to be generated in a direction orthogonal to the current, and capture a change of an inductance in the detection coil due to a change of the magnetic flux to be caused by the eddy current, the detection devices including at least one set of a detection device P detecting a slight change of the inductance and a detection device M detecting only a big change of the inductance. The pitch coke is detected if the change of the inductance is detected only by the detection device P, the metallic foreign substance is detected if the change of the inductance is detected by both detection devices P and M, and the nonmetallic foreign substance is detected if no change of the inductance is detected by both detection devices P and M. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In the present invention, in order to discriminate and remove metal pieces (iron, aluminum, etc.) and non-metal objects (brick waste, wood pieces, plastics, etc.) mixed in pitch coke, the subject is pitch coke, metal foreign matter, non- The present invention relates to a foreign matter detection device in pitch coke that discriminates simultaneously which metal foreign matter is.

  There has been proposed an inspection apparatus that detects an abnormality of a subject or a mixed foreign substance by a change in electromagnetic induction (see Patent Document 1). As shown in FIG. 3 of Patent Document 1, this electromagnetic induction inspection apparatus includes an AC power source 11, an excitation coil 13a, a detection coil unit 13 including an induction coil 13b, an excitation coil 23a, and an induction coil 23b. From a balanced circuit 22 in which a balanced inductor unit 23 is connected in series to the detection coil unit 13, an amplifier 24 that amplifies the output from the balanced circuit 22, and a determination circuit 25 that determines the subject S from the output of the amplifier 24 The detection circuit 15 is configured. Thus, in this prior art, an object is identified by placing a subject in an alternating magnetic field, causing a change in the magnetic field due to that, and capturing the change in the magnetic field. Recognize the existence of a substance.

  On the other hand, pitch coke is coke obtained by dry distillation of coal tar pitch or petroleum pitch. Hard pitch carbonization is performed using a chamber furnace for the production of coal coke. Recently, it is efficiently produced from soft pitch by a delayed coker for producing petroleum coke. Compared with coal coke, it has less ash and becomes pure carbon by calcination. Pitch coke has applications such as anode raw materials for aluminum electrolytic refining, molded graphite electrodes for steel making, carbon bricks, automobile tires, semiconductors, lithium batteries, and graphite materials for nuclear reactors.

  Thus, in the production process of pitch coke, metal pieces (iron pieces, aluminum, etc.) of equipment, non-metallic foreign matters (furnace refractories (brick waste, etc.), wood pieces, plastic, etc.) may be mixed into pitch coke. These contaminants directly affect the quality of products made from pitch coke, such as molded graphite electrodes for steelmaking and graphite for reactors.

Conventionally, in the production process of pitch coke, in addition to the extraction of iron (steel) pieces by magnetism, foreign matter (brick waste, aluminum, wood pieces, plastics, etc.) is detected by X-rays. The result is not obtained. For example, a piece of wood or the like cannot be detected by an electromagnet, a metal detector, or an X-ray detector. On the other hand, the means for detecting abnormality of a specimen due to a change in electromagnetic induction disclosed in Patent Document 1 described above and a foreign substance mixed therein detect an abnormality such as a crack in the subject, and the reference product S _ref Although it is possible to discriminate whether or not the subject is a foreign substance by comparing with the subject, it is not possible to discriminate between the pitch coke, the metallic foreign matter, and the nonmetallic foreign matter simultaneously.

  In the pitch coke manufacturing process or inspection line, the present invention discriminates simultaneously whether the specimen is pitch coke, metallic foreign matter or nonmetallic foreign matter, and separates metallic foreign matter and nonmetallic foreign matter individually from the line. An object of the present invention is to provide an apparatus for detecting foreign matter in pitch coke for removal and flowing in each line.

  In order to solve the above problems, the present invention applies a current to a resonance circuit (detection coil) composed of an inductance (L) and a capacitance (C), and vortexes the subject by a magnetic flux generated in a direction orthogonal to the current. A detection device that generates a current and captures a change in inductance in a detection coil caused by a magnetic flux change caused by the eddy current is detected only in a detection device P that detects a small inductance change and a large inductance change in the direction of conveyance of pitch coke. At least one set of detection devices M to be detected is arranged, the pitch coke is detected by detecting the inductance change of only the detection device P, and the metal foreign object is detected by detecting the inductance changes of both the detection device P and the detection device M. And the inductance of both the detection device P and the detection device M By a change or detection of a small change in inductance can be ignored a foreign substance detecting device of the pitch coke obtained by configured to detect non-metallic foreign matter.

  According to the present invention, in the pitch coke manufacturing process or inspection line, the specimen is any of pitch coke, metallic foreign matter (iron pieces, aluminum, etc.), non-metallic foreign matter (brick waste, wood pieces, plastic melted solid matter, etc.). It is possible to discriminate them simultaneously, and there is an effect that metal foreign matters and non-metallic foreign matters can be individually removed.

It is the schematic which shows the structure of the foreign material detection apparatus in the pitch coke of this invention. It is a circuit diagram which shows (a) oscillation circuit (b) oscillation state detection circuit (c) output circuit (comparator) which comprises the foreign material detection apparatus in the pitch coke of this invention. It is the schematic which shows one embodiment of the ejector which removes the metal foreign material detected by the foreign material detection apparatus in the pitch coke of this invention, and a nonmetallic foreign material out of a line. It is the schematic which shows an example of the assembly | attachment state to the pitch coke manufacturing line or inspection line of the foreign material detection apparatus in the pitch coke of this invention. (A) is a top view, (b) is a front view.

  Hereinafter, the present invention will be described according to the embodiment.

  In the present invention, an alternating current is passed through a resonance circuit (detection coil) composed of an inductance (L) and a capacitance (C), and an eddy current is generated in a subject by a magnetic flux generated in a direction orthogonal to the current. This is a detection device that captures a change in inductance in a detection coil caused by a change in magnetic flux caused by an eddy current as a change in phase.

  On the other hand, the present invention has been made focusing on the fact that pitch coke has conductivity between a conductor such as a metal and a non-conductive object (dielectric) such as a brick and plastic. Thus, in the pitch coke production line or inspection line, at least one set of the detection device P for detecting a small inductance change and the detection device M for detecting only a large inductance change is arranged adjacent to the subject flow direction, It is recognized that the subject is pitch coke by detecting the inductance change only in the detection device P, and that the subject is a metal foreign object by detecting the inductance change in both the detection device P and the detection device M. Further, it is recognized that the subject is a non-metallic foreign matter such as brick scraps, wooden pieces, and plastics by no change in inductance or virtually no change in both the detection device P and the detection device M.

As compared with the detection device M, the detection device P is configured to detect a small inductance change by either increasing the number of turns n _{p of the} coil or increasing the angular frequency ω.

  Further, the set of the detection device P and the detection device M is arranged in multiple stages in the pitch coke flow direction, and captures inductance changes in the detection device P and the detection device M many times under the rolling state of the subject. It is desirable to do. By doing so, it is possible to detect that a part of a specimen in which brick dust is adhered to pitch coke, for example, is non-metallic foreign matter.

  An apparatus for detecting foreign matter in pitch coke according to an embodiment of the present invention will be described. FIG. 1 shows a device configuration of a foreign matter detection device in pitch coke according to an embodiment of the present invention. In FIG. 1, 1 is a pitch coke, 2 is an oscillation circuit, and in this embodiment, is an oscillation circuit of a pitch coke detector P. This circuit is an LC oscillation circuit, and the coil L1 in this circuit is the pitch coke detection coil P in FIG. Reference numeral 3 denotes an oscillation state detection circuit, which detects an inductance change in the oscillation circuit (detection coil) 2 by detecting a phase advance or delay caused by the inductance change in the oscillation circuit 2. Reference numeral 4 denotes an output circuit, which is a kind of comparator. The output of the oscillation state detection circuit 3 is output as a logic level of “1” or a logic level of “0”, and it is determined whether or not the subject is pitch coke.

  Reference numeral 5 denotes a foreign matter ejector. When a metallic foreign matter or non-metallic foreign matter in the pitch coke is detected by the metallic foreign matter detection device M or the pitch coke detection device P (only the pitch coke detection device P detects an inductance change, the subject is pitch coke, If an inductance change is detected in both the pitch coke detection device P and the metal foreign matter detection device M, the subject is a metal foreign matter, and if no inductance change is detected in both the pitch coke detection device P and the metal foreign matter detection device M, the subject Is detected by a foreign object detection control device 7, the metal foreign object or non-metallic foreign object (brick, wood, plastic, etc.) is put into the foreign object chute 24. Throw it in. As shown in FIG. 3, the foreign object ejector 5 is driven impactively by a signal from the foreign object detection control device 7 to the drive coil 52, and throws the foreign object into the foreign object chute 24.

  The configuration of the metal foreign object detection device M is the same as that of the pitch coke detection device P, and includes an oscillation circuit 12, an oscillation state detection circuit 13, and an output circuit (comparator) 14. Reference numeral 6 denotes an object passage detection sensor, which is a photosensor such as a light shielding photosensor or a reflection photosensor.

  FIG. 2A shows the oscillation circuits 2 and 12. A detection coil L1 in which a conductive coil is wound around a ferrite core and an LC oscillation circuit including capacitors C3, C4, and C5 generate an alternating magnetic field (oscillation circuit output). FIG. 2B shows the oscillation state detection circuits 3 and 13. This circuit is a PLL circuit, and a commercially available PLLIC was used from the viewpoint of circuit stability and cost reduction. When the output of the oscillation circuits 2 and 12 is connected to the oscillation input of this circuit, the PLL circuit outputs the change in the oscillation frequency of the oscillation circuits 2 and 12 as a minute voltage change indicating the oscillation state, thereby the inductance of the detection coil L1. The amount of change is captured. The oscillation frequency of the oscillation state detection circuits 3 and 13 is adjusted by the trimmer capacitor TC1 and the variable resistor VR1.

FIG. 2C shows output circuits (comparators) 4 and 14. The outputs of the oscillation state detection circuits 3 and 13 enter the buffer circuit of the transistor TR2 through the low-pass filter of the resistor R10 and the capacitor C11, and are led from the collector which is the output to the comparator IC3, and the determination result is “load”. It is output as to whether or not current flows through the part. For example, the location of the "load" as the logic level of the In the detecting device P for which the subject recognizes whether the pitch coke, when equal to or greater than the threshold of the inductance variation L _P '1' It is determined that a current flows and the subject is pitch coke. When the logic level is “0”, it is determined that the subject is not pitch coke.

  FIGS. 4 (a) and 4 (b) show a mode when the foreign matter detecting device in pitch coke according to one embodiment of the present invention is incorporated in a pitch coke inspection line. 4A is a plan view and FIG. 4B is a front view. 4 (a) and 4 (b), 21 is an object carrying-in conveyor, 22 is a branching conveyor, and 23 is a smooth feeder, which uniformly distributes and develops the object on a plane. D is a foreign object detection device and an ejector group. A pair of the pitch coke detection device P and the metal foreign object detection device M having the configuration shown in FIG. 1 is a flow of the subject as shown in the partially enlarged view of FIG. It is arranged in a staggered manner in the (slope) direction and the width direction.

  Reference numeral 24 denotes a foreign matter chute, in which metallic foreign matter and non-metallic foreign matter (such as brick scraps, wooden pieces, and plastics) detected by the pitch coke detection device P and the metallic foreign matter detection device M are thrown by the foreign matter ejector 5.

Reference numeral 25 denotes a confluence chute, which is a pitch coke after the detection of metallic foreign matter and non-metallic foreign matter in the pitch coke in the foreign matter detecting device and the ejector group D region and the foreign matter throwing into the foreign matter chute 24 by the foreign matter ejector 5 are completed. Merge onto the normal product conveyor 27. FB is a foreign matter blown by the ejector 5, and 26 is a foreign matter carry-out conveyor.
Example 1

  As a pitch coke detecting device P, a ferrite core having a diameter of 6 mm and a copper wire having a diameter of 0.085 mm are wound 3000 times as a detection coil L1 shown in FIG. 2A, and FIG. 2A, FIG. ) Was applied and a power supply voltage of 3 V was applied. First, the inductance of the coil was 93.3 mH when nothing was brought close to the coil L1. In this state, the trimmer capacitor TC1 and the variable resistor VR1 were adjusted so that the output circuit was turned off.

Next, when the pitch coke was brought close to the detection coil L1, the inductance of the coil increased to 93.7 mH, the output circuit 4 was turned on, and it was determined that the subject was pitch coke. Even if bricks, glass pieces, or wood pieces are brought close to the detection coil L1, the inductance of the detection coil L1 remains 93.3 mH, so that the output circuit 4 remains OFF and the object is a non-metallic foreign object. Judged.

  As the metal foreign object detection device M, a ferrite core having a diameter of 4.5 mm and a copper wire having a diameter of 0.085 mm wound about 1500 times is used as a detection coil L1 shown in FIG. 2A, and FIGS. The circuit shown in (c) was connected and a power supply voltage of 3 V was applied. First, the inductance of the coil was 4.6 mH when nothing was brought close to the coil L1. In this state, the trimmer capacitor TC1 and the variable resistor VR1 were adjusted so that the output circuit was turned off. Next, when a stainless steel piece was brought close to the detection coil L1, the inductance of the coil decreased to 4.2 mH, the output circuit 14 was turned on, and it was determined that the subject was a metallic foreign object. When a copper piece is brought close to the detection coil L1, the inductance of the coil is reduced to 4.2 mH, and in the case of an aluminum piece, the inductance is reduced to 4.1 mH. In either case, the output circuit 14 is turned on and it is determined that the subject is a metallic foreign object.

When the metal foreign matter detection device M and the pitch coke detection device P are arranged as shown in FIG. 1 and the pitch coke piece is passed from top to bottom, only the output circuit of the pitch coke detection device P is turned on, It was determined to be pitch coke. Next, when a stainless steel bolt was passed in the same manner, the output circuit of the metal foreign object detection device M was turned on, and it was determined that the passed object was a metal foreign object. Furthermore, if the brick pieces are passed in the same way, the output circuits of both the metal foreign matter detection device M and the pitch coke detection device P remain OFF, and the passed material is non-metallic foreign matter (brick waste, wood chips, plastic, etc.) It was determined that
(Example 2)

  FIG. 2A shows a coil as a pitch coke detection device P in which a copper wire having a diameter of 70 mm is wound 3000 times on a cylindrical frame having a diameter of 70 mm and then the cylindrical frame is removed to form only a ring-shaped copper wire. The detection coil L1 was used, and the circuits shown in FIGS. 2A, 2B, and 2C were connected to apply a power supply voltage of 3V. First, the inductance of the coil was 70.5 mH when nothing was brought close to the detection coil L1. In this state, the trimmer capacitor TC1 and the variable resistor VR1 were adjusted so that the output circuit was turned off.

  Next, when pitch coke was passed through the detection coil L1, the inductance of the coil increased to 70.6 mH, the output circuit was turned on, and it was determined that the subject was pitch coke. Since the inductance of the detection coil L1 remains unchanged at 70.5 mH even when the detection coil L1 passes through brick scraps, glass pieces, and wood pieces, the output circuit 4 remains OFF, and it is determined that the subject is a non-metallic foreign matter. In this way, the metallic foreign matter detection device M and the pitch coke detection device P can be configured by means for making the coil hollow and passing (dropping) the subject therein.

1 Pitch coke P Pitch coke detection device M Metal foreign matter detection device 2 Oscillation circuit 3 Oscillation state detection circuit 4 Output circuit (comparator)
5 Foreign Object Ejector 51 Ejector Case 52 Drive Coil 6 Subject Passing Detection End 12 Oscillation Circuit 13 Oscillation State Detection Circuit 14 Output Circuit (Comparator)
DESCRIPTION OF SYMBOLS 21 Specimen carrying-in conveyor 22 Branching chute 23 Smooth feeder D Foreign substance detection sensor and ejector group 24 Foreign substance chute 25 Pitch coke merge chute 26 Foreign substance carrying out conveyor 27 Normal article carrying out conveyor FB Foreign substance blown off by ejector

Japanese Patent No. 3140105 (Japanese Patent Laid-Open No. 05-002082)

Claims (1)

A current flows through a resonance circuit (detection coil) composed of an inductance (L) and a capacitance (C), and an eddy current is generated in a subject by a magnetic flux generated in a direction orthogonal to the current, and the magnetic flux generated by the eddy current At least one set of detection devices that detect a small inductance change and a detection device M that detects only a large inductance change are arranged in the direction of conveyance of pitch coke in order to detect the inductance change in the detection coil caused by the change. Then, it is detected that the pitch coke is detected by detecting the inductance change of only the detection device P, and the metallic foreign object is detected by detecting the inductance change of both the detection device P and the detection device M, and the inductance of both the detection device P and the detection device M. A small inductance that is unchanged or negligible Foreign matter detection device of pitch coke obtained by configured to detect non-metallic foreign matter by the change detection.

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