JP2011039019A - Superconductive sensor for electromagnetic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor for an electromagnetic diagnostic apparatus, capable of detecting an abnormal condition of a conductive rotating body without contacting the rotating body, and suppressing attenuation due to a distance of a magnetic field in order to apply to a large device. <P>SOLUTION: The sensor for the electromagnetic diagnostic apparatus includes a high-temperature superconductive electromagnet having a function of a magnetic field generation source generating a static magnetic field for the rotating body, and magnetic field sensors such as an induction coil and a Hall element for measuring a magnetic field generating a current induced by the rotating body moving in the generated magnetic field, and uses a set of the magnetic sensors and the superconductive electromagnet in measurement. The sensor for the electromagnetic diagnostic apparatus is capable of generating a strong magnetic field with a high current by using a high-temperature superconductive material, suppressing the attenuation due to the distance of the magnetic field by enlarging the electromagnet, and controlling the magnetic field by turning on/off the current. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a state monitoring and state diagnosis technique for realizing non-contact detection of an abnormal state of a rotating device having a conductive rotating body using an electromagnetic phenomenon.

  Rotating equipment is indispensable in the modern industry. Especially for rotating equipment that is incorporated as important equipment in large-scale facilities such as plants, the stoppage may lead to the entire system being stopped and the system itself being damaged. As such, ensuring its soundness is an important issue. Currently, the most common method for evaluating the soundness of rotating equipment is to measure the vibration of rotating equipment during operation and detect various abnormalities and malfunctions from their amplitude values, various statistics, and spectral analysis results. It has been adopted. Although vibration diagnosis is relatively simple, most of the abnormal states of rotating equipment can be detected, and many research results related to vibration diagnosis have been reported. However, in recent years, it has also been regarded as a problem that the abnormal state and remaining life of a rotating device cannot always be correctly evaluated by vibration diagnosis alone. That is, it cannot always be said that the degree of abnormal vibration represents the degree of functional loss of the rotating equipment, and the malfunction detected by vibration is just before the rotating equipment loses its function, or conversely In some cases, large abnormal vibrations may be measured even though the scratches are considered to be fine. In order to solve such a problem, Japanese Patent Application Laid-Open No. 2008-096410 proposes an electromagnetic diagnostic technique using an electromagnetic phenomenon, and simultaneously monitors the status of rotating equipment using a plurality of status monitoring techniques, and obtains the obtained signal. Attempts have been made to evaluate the abnormal state and the remaining life more quantitatively by comprehensively evaluating.

  JP2008-096410   Japanese Patent Application No. 2008-336198   Japanese Patent Application No. 2008-336199

  A state monitoring technique that enables early detection of an abnormality such as a defect occurring in a rotating body of a rotating device by an electromagnetic diagnosis technique has been proposed (Japanese Patent Laid-Open No. 2008-096410). Accessibility to a rotating part becomes a problem when the state of a rotating device is monitored using an electromagnetic diagnostic technique. The rotating part is always surrounded by a thick casing, and the detection sensitivity is easily affected by the material and thickness of the casing. In particular, in the case of a large rotating device, there is a problem that the distance from the place where the rotating device can be installed to the rotating portion is large, the static magnetic field in the rotating portion diverges, the induced eddy current becomes weak, and the detection sensitivity becomes low. Large permanent magnets can be used to obtain the required sensitivity, but magnet fabrication and handling during measurement is difficult.

  In monitoring the status of rotating equipment, it is necessary that the signals obtained in each measurement are at the same location. However, if a sensor is arranged for each measurement, it is difficult to guarantee the sensor positioning accuracy. . In order to realize state monitoring, it is desirable to always install a sensor. In the state monitoring technique based on the electromagnetic diagnosis technique proposed in Japanese Patent Laid-Open No. 2008-096410, a sensor in which a coil is wound around a permanent magnet is used. If such a sensor is installed for a long time and the rotating device is operated, there is a possibility of adverse effects such as disturbing the rotating state of the rotating device or capturing metallic foreign objects due to the magnetic field generated from the permanent magnet.

  It is conceivable to use an electromagnet instead of a permanent magnet. However, in order to create a magnetic field with sufficient strength, a large excitation current is required. If an electromagnet having the same strength as a permanent magnet is to be produced, the dimensions will be several to several tens of times that of a permanent magnet. Further, in the conventional electromagnet made of copper wire, the problem of heat generation due to a large excitation current cannot be ignored.

  In order to solve such a problem, the present invention provides a sensor for an electromagnetic diagnostic apparatus that does not give an influence of a magnetic field to a rotating device even when the sensor unit is mounted on the rotating device for a long period of time, and can obtain high detection sensitivity. Is to provide.

  According to the first aspect of the invention for solving the above-mentioned problems, in the sensor for an electromagnetic diagnostic apparatus, the excitation part and the magnetic field sensor part (induction coil or Hall element) are separated, and when measuring, the magnetic field sensor part and the excitation part are set. And used as a sensor for an electromagnetic diagnostic apparatus. FIG. 1 shows a sensor for an electromagnetic diagnostic apparatus. A high temperature superconducting electromagnet is used in the excitation part. A large current is applied to the exciting coil 2 made of high temperature superconducting material to generate a strong magnetic field. The liquid nitrogen cooling vessel 3 surrounding the excitation coil is filled with liquid nitrogen to maintain the superconducting state of the excitation coil. The liquid nitrogen container has an inlet 4 and an outlet 5 for injecting liquid nitrogen, and liquid nitrogen can be replenished as needed. Since it is an electromagnet, the control of the magnetic field is simple, and the magnetic field can be turned on only when measuring. The magnetic field sensor part 1 is separated from the excitation part and can be mounted outside or inside the casing for a long time. In the case of mounting inside the casing, it is possible to get closer to the rotating part, and the detection sensitivity can be increased.

  The invention of claim 2 enables eddy current flaw detection by applying an AC current or a pulse current instead of a DC current to a high-temperature superconducting electromagnet and measuring a magnetic field sensor output signal.

  In the sensor for an electromagnetic diagnostic apparatus of the present invention, a strong magnetic field that is difficult to attenuate and diverge is created by using an electromagnet made of a high-temperature superconducting material, which is sufficient for an internal rotating part even from the outside of a large rotating device. A magnetic field having an intensity can be applied to maintain the detection sensitivity of the electromagnetic diagnostic signal. A magnetic field sensor can be mounted in the casing of the rotating device for a long period of time, and the magnetic field generated by the eddy current generated in the rotating body of the rotating device can be detected by turning on the electromagnet only when measuring.

  Next, the Example in this invention is described in detail based on an accompanying drawing. Parts common to the drawings use the same reference numerals.

  FIG. 2 shows an embodiment in which claim 1 of the present invention is applied to an impeller of a large pump. The main parts of the present invention are an electromagnetic sensor unit 1 for measurement, an exciting coil 2 for generating a static magnetic field in a rotating body passage, a liquid nitrogen cooling vessel 3 for cooling with liquid nitrogen, an inlet 4 and an outlet for liquid nitrogen It consists of five. An electromagnetic diagnostic device sensor is installed outside the pump casing 7 to measure the impeller 6 inside the casing. In this figure, an impeller 6 composed of four rotating blades is attached to a rotating shaft 8, and the impeller 6 rotates around the rotating shaft 8 in the direction of an arrow 9. When the impeller 6 crosses the static magnetic field generated by the high-temperature superconducting electromagnet as a magnetic field generation source, an electromotive force is generated in the impeller 6 and, as a result, a current is induced. Since the current flow changes depending on the presence / absence of a defect in the impeller 6 and the nature of the defect, the presence / absence of the defect can be detected and evaluated from the value of the signal detected by the magnetic field sensor 1. The magnetic field sensor 1 here is an induction coil that sticks to the outer surface of the casing. However, as described above, it is important to capture the dynamic magnetic field generated by the induced current generated when the rotating part crosses the static magnetic field. The coil does not necessarily have to stick to the outer surface of the casing, and a magnetic field sensor such as a Hall element other than the induction coil can also be applied.

  FIG. 3 shows an embodiment in which claim 1 of the present invention is applied to a rotor blade such as a turbine blade. The excitation unit of the electromagnetic diagnostic apparatus sensor is the same as described above, but the induction coil of the magnetic field sensor unit is installed inside the turbine casing 11 to measure the signal. The detection sensitivity can be improved by installing it in the vicinity of the turbine blade 10.

The sensor for electromagnetic diagnostic apparatuses of this invention. The bird's-eye view when the sensor for an electromagnetic diagnostic apparatus according to one embodiment of the present invention is installed outside the pump impeller casing Sectional drawing at the time of installing the sensor for electromagnetic diagnostic apparatuses which is one Example of this invention inside a turbine casing

1 Magnetic field measurement part of sensor 2 Excitation coil part of electromagnet (high temperature superconducting material)
3 Electromagnetic liquid nitrogen cooling vessel 4 Liquid nitrogen cooling vessel liquid nitrogen inlet 5 Liquid nitrogen cooling vessel liquid nitrogen outlet 6 Pump impeller 7 Pump casing 8 Rotating shaft 9 Rotating direction 10 Turbine blade 11 Turbine casing

Claims (2)

  A high-temperature superconducting electromagnet that acts as a magnetic field source that generates a static magnetic field at the passing position of the rotating body, and an induction coil or hole for measuring the magnetic field generated by the current induced in the rotating body that moves in the generated magnetic field A sensor for an electromagnetic diagnostic apparatus, comprising a magnetic field sensor such as an element and using a magnetic field sensor and a high-temperature superconducting electromagnet as a set for measurement.   A high-temperature superconducting electromagnet that acts as a magnetic field source that generates a static magnetic field at the passing position of the rotating body, and an induction coil or hole for measuring the magnetic field generated by the current induced in the rotating body that moves in the generated magnetic field A magnetic field sensor such as an element is provided, and the magnetic field sensor signals caused by the dynamic magnetic field generated by the induced current generated when the rotating part crosses the static magnetic field as in the first aspect of the invention can be collected. In addition, a sensor for an electromagnetic diagnostic device that enables eddy current flaw detection by applying an alternating current or a pulse current to a high temperature superconducting coil for excitation and measuring a magnetic field sensor output signal.

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