JP2002122410A - Capacitance type probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitance type probe capable of executing stable measurement without being influenced by humidity. SOLUTION: This capacitance type probe comprising an external cylinder 8 positioned on the outside in the radial direction, a guard member 6 positioned on the middle in the radial direction, an electrode 4 positioned on the inside in the radial direction, and insulating layers 5, 7 formed from insulating material respectively between the external cylinder 8 and the guard member 6 and between the guard member 6 and the electrode 4 is characterized by being provided with a heating means 9 for heating the insulating layers 5, 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compressor,
The present invention relates to a capacitance type probe for measuring a clearance mainly used for controlling or monitoring a steam turbine, a gas turbine, a jet engine or the like.

[0002]

2. Description of the Related Art As the above-mentioned capacitance type probe, for example, a probe shown in FIG. 7 is generally used. In the figure, in order to measure a gap (clearance) between the blade 1A constituting the rotating body 1 provided in the gas turbine and the casing 2, the surface of the electrode 4 is provided in a through hole 2K formed in the casing 2. The cylindrical capacitance type probe 3 is mounted in a state of being exposed to the internal space of the second. The capacitance type probe 3 includes an outer cylinder 8 positioned radially outward, a guard member 6 positioned radially intermediate, an electrode 4 positioned radially inward, and the outer cylinder 8 and the guard member. 6, and between the guard member 6 and the electrode 4 are insulating layers 5 and 7 formed of an insulating material. The static electricity of the fluid (combustion gas) between the capacitance type probe 3 and the blade 1A is formed. The system is configured to detect a phenomenon in which the capacitance changes depending on the distance between the two, and the system can measure the clearance by converting a change in capacitance into a voltage. still,
A casing 2 is provided on the outer surface of the outer cylinder 8 substantially at the center in the longitudinal direction.
A flange portion 8F is formed so as to be in contact with the outer surface of the projection. In FIG. 7, 11 is an electrode signal line connected to the electrode 4, 12 is a guard member signal line connected to the guard member 6, and 13 is connected to the outer cylinder 8. Ground wire, and constitutes a triple coaxial cable 14 in which these three wires are integrated. In addition, 21 shown in FIG. 7 is a relay metal ring member for connecting the outer cylinder 8 and the ground wire 13, and 22 is the guard member 6 and the guard member signal line 12. 23 is an insulating layer for insulating the guard member signal line 12 and the ground line 13 from each other, and 24 is the ground line 13 and the ring member. 21 is an insulating layer for insulating the connecting member 22 and the guard member 6 from each other; 25 is an insulating layer for insulating the electrode 4 from the connecting member 22;
This is an insulating layer for insulating the signal lines 11 for electrodes and the signal lines 12 for guard members.

[0003]

In the capacitance type probe 3 having the above structure, the insulating material forming the insulating layers 5 and 7 is made of a heat-resistant material so as to withstand a high-temperature and high-pressure fluid (combustion gas). Since it is made of a porous material having properties (having many pores), it has the following disadvantages. That is, in the high humidity season, the blade 1A
Moisture penetrates into the insulating layers 5 and 7 from the tip of the capacitance type probe 3 having an open side, and the insulation resistance of the capacitance type probe 3 is reduced. However, there is an inconvenience that the measurement by the capacitance type probe 3 cannot be performed immediately even when the device is operated.
Incidentally, the gas turbine driving a, the casing becomes hot, albeit between time a few minutes until the insulation resistance of a capacitive probe 3 is restored, particularly in a gas turbine starting (rising) when It is important to perform the measurement at a time (a time when the change in the size of the clearance is large), and early improvement has been demanded.

An object of the present invention is to provide a capacitance type probe capable of performing stable measurement without being affected by moisture in view of the above situation.

[0005]

In order to solve the above-mentioned problems, the present invention provides an outer cylinder positioned radially outward, a guard member positioned intermediate in the radial direction, and an electrode positioned radially inward. Measuring the distance between a rotating body having an insulating layer formed of an insulating material between the outer cylinder and the guard member and between the guard member and the electrode, and having a discontinuous outer surface such as a wall surface of a casing or a blade; or In a capacitance type probe for measuring a distance from an outer surface of a rotating body having a continuous outer surface such as a disk or a shaft, a heating means for heating the insulating layer is provided to constitute a capacitance type probe. By heating the insulating layer with the heating means as described above, it is possible to prevent moisture that is going to enter the insulating layer from entering the insulating layer, or to immediately remove even if it enters the insulating layer. Therefore, it is possible to reliably prevent the insulation resistance from being lowered by moisture.
The capacitance type probe can measure the distance between the wall surface of the casing and a rotating body having a discontinuous outer surface such as a blade, and the distance from the outer surface of the rotating body having a continuous outer surface such as a disk or a shaft. Can be measured.

[0006] By configuring the heating means with a heater wire wound around the outer surface of the outer cylinder, the heater wire can be mounted without any improvement to the existing capacitance type probe. Also, if the power frequency of the heater wire is 50
Hz or 60 Hz (Hertz), whereas the carrier frequency of FM used in the measurement system using the capacitance type probe is 2 MHz (megahertz) or more, and the carrier frequency of AM is Since the frequency is 1 kHz (kilohertz) or more, the two frequencies are greatly different, and even if a heater wire is provided, the measurement function of the measurement system using the capacitance type probe is not affected at all.

[0007] The capacitance type probe is provided on a wall surface of a casing through which a fluid passes, and the heater wire is wound around only a part of an outer surface of the outer cylinder on an outer side of the casing. When the capacitance type probe is provided in the casing through which the fluid passes as described above, even if the heater wire is wound only on a part of the outer surface of the outer cylinder on the outer side of the casing, the number of turns may be increased. By performing the change, the same heating effect as when the heater wire is wound around the entire outer side of the casing can be obtained.

The heating means comprises a heater wire and a support member for accommodating the heater wire, and when the heater wire is exchanged by mounting the heating means via the support member, the support member can be replaced. It only needs to be attached to and detached from the capacitance type probe.

[0009] By providing the switching means for switching the heating means from the operating state to the non-operating state after the set time elapses from the start of rotation of the rotating body, the heating means is always operated when the rotating body is not rotating. The running cost can be reduced and the service life of the heating means can be prolonged as compared with the case where the means is kept in the operating state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a columnar shape for measuring the clearance (gap) between a rotating body 1 and a casing 2 in a gas turbine (it may be any shape such as a prism or a polygon). Are attached at equal intervals in the circumferential direction of the casing 2,
Based on the detection information from these four capacitance type probes 3, it is configured to be used for control and monitoring of the gas turbine. Here, the capacitance type probe 3 used in the gas turbine will be described. However, the capacitance type probe 3 may be used under a high temperature condition such as a jet engine. Further, the capacitance of the combustion gas is detected, but the capacitance of a fluid containing liquid such as lubricating oil in addition to air such as dew-condensed water or various combustion gases is detected. You may do so. Also, four capacitance type probes 3 are provided,
One, two, three, or five or more may be provided and implemented.

The rotating body 1 is configured by attaching a large number of blades (wings) 1A to a rotating shaft 1B. or,
Each of the blades 1A has a clearance between the outer peripheral edge thereof and the casing 2 different in the rotation direction, and the blades 1A and the blades 1A are attached at predetermined intervals in the rotation direction. In addition to measuring the distance between the wall surface (inner surface) 2A of the casing 2 and the rotating body having a discontinuous outer surface such as the blade 1, the rotating body having a continuous outer surface such as a disk or a shaft (not shown) is also shown. It may be used to measure the distance between the outer surface and the capacitance type probe.

As shown in FIG. 2, the capacitance type probe 3 is inserted into a through hole 2K formed in the casing 2, and its tip end surface (detection surface) is formed on the inner surface 2 of the casing 2.
It is fixed at a position flush with A. By arranging the tip end surface of the capacitance type probe 3 flush with the inner surface 2A of the casing 2, the distance from the inner surface 2A is calculated as a correction amount when the clearance is detected when the capacitance type probe 3 is not arranged flush. There is an advantage that this is not necessary, but it is not necessary to arrange them flush.

[0013] The capacitance type probe 3 will be described in detail.
300 ° C.) and an insulating layer 5 formed of a porous (porous) insulating material on the outside of the electrode 4, and the same heat-resistant alloy (heat-resistant temperature of about 1300 C), and an insulating layer 7 formed of the same insulating material as above on the outside of the guard member 6.
And an outer cylinder 8 made of a heat-resistant alloy (heat-resistant temperature of about 1300 ° C.) in the same manner as described above, and heating means for winding the outer layers 8 around the outer cylinder 8 to heat the insulating layers 5 and 7. (The detection surface temperature of the electrode 4 is 10
A heater body 9 capable of heating to 0 ° C. or more) and a cover body 10 made of a heat-resistant alloy (heat-resistant temperature of about 1300 ° C.) similar to the above to cover the heater wire 9 outside the heater wire 9 The capacitance type probe 3 is configured as a constituent member. The cover body 10 has a cylindrical tubular portion 10A positioned diametrically outside the through-hole 2K, and a ring-shaped plate-shaped member for closing between both ends of the tubular portion 10A and both ends of the outer cylinder 8. It is composed of two lids 10B and 10C. In addition, a flange portion 10 </ b> F for making contact with the outer surface of the casing 2 is formed so as to protrude from an outer surface at a substantially central portion in a longitudinal direction of the cylindrical portion 10 </ b> A. In FIG. 2, reference numeral 11 denotes an electrode signal line connected to the electrode 4, 12 denotes a guard member signal line connected to the guard member 6, and 13 denotes a signal line connected to the outer cylinder 8. Ground wire,
These three wires constitute a triple coaxial cable 14 integrated. In addition, 21 shown in FIG. 2 is a relay metal ring member for connecting the outer cylinder 8 and the ground wire 13, and 22 is a guard member 6 and the guard member signal line 12. And 23, an insulating layer for insulating the guard member signal line 12 and the ground line 13 from each other.
Is an insulating layer for insulating the ground wire 13 and the ring member 21 from the connecting member 22 and the guard member 6, and 25 is an insulating layer for insulating the electrode 4 from the connecting member 22. Reference numerals 26 denote insulating layers for insulating the signal lines 11 for electrodes from the signal lines 12 for guard members. When the blade 1A passes through the capacitance type probe 3, the capacitance between the two changes, and the capacitance type probe 3 detects the change. The capacitance change is converted into a voltage by a system component device, and a calibration operation for recording a voltage corresponding to the clearance is performed. By using the calibrated data, it is converted online into a physical quantity unit (mm). The capacitance type probe 3 is made of a heat-resistant material as described above, or is not affected by vibration or noise, as well as temperature change (up to about 1300 ° C.), depending on the system components. , Can be measured.

The insulating material constituting the insulating layers 5, 7, 23 to 26 is generally a metal or metalloid (metalloid) oxide and nitride, a mixture of these oxides or nitrides, Alternatively, a mixture of other oxides or nitrides, a mixture of other oxides or nitrides, or the like can be given, but other materials may also be used.

As the heating means, for example, a coil-shaped heating element (heating element) that generates heat by passing electricity through a heater wire (Nichrome wire) 9 made of a nickel-chromium alloy (the material may be other than these) is used. However, in addition to using a heating element (heating element) formed in a sheet shape, a configuration that circulates steam in a pipe, a configuration that uses induction heating, and the like.
The specific configuration of the heating means is not limited to these. Further, the heater wire 9 is wound around the entire surface of the outer cylinder 8, but as shown in FIG. May be implemented.
Also, as shown in FIG. 3, by forming a flange portion 8F on the outer cylinder 8 so as to protrude, one of the lid portions 1 shown in FIG.
There is an advantage that OC can be shared by the flange portion 8F. When the same material and the same diameter (diameter) as those of the heater wire 9 shown in FIG. 2 are used, the number of turns is increased from the number of turns in FIG. As a result, a calorific value substantially equal to that of FIG. 2 can be obtained. The difference between the calorific values can be reduced as much as possible by forming the outer cylinder 8 and the guard member 6 from a material having a high thermal conductivity. Further, by heating the outer cylinder 8 by the heater wire 9, heat is transmitted in the order of the insulating layer 7, the guard member 6, and the insulating layer 5. However, only the insulating layers 5 and 7 are directly heated. May be configured. Since the other configuration shown in FIG. 3 is the same as that of FIG. 2, the same reference numerals are given and the description is omitted.

Further, the heater wire 9 as the heating means is wound directly around the outer cylinder 8 as shown in FIG.
As shown in FIG. 2, a heater is formed by wrapping the heater wire 9 around a separately formed support member 27, and the support member 27 (shown by a two-dot chain line in FIG. 2) around which the heater wire 9 is wound is a capacitance type. The probe 3 may be attached by welding or fitting. Specifically, a flange 8F is formed substantially at the center in the longitudinal direction of the outer cylinder 8, and an annular space for forming a storage space in which the support member 27 can be fitted on the upper surface side of the flange 8F in the drawing. The portion 8A is formed. Then, the support member 27 including a ring-shaped horizontal portion 27A forming a lid portion and a cylindrical portion 27B in a vertical posture that hangs downward from the inner peripheral edge of the horizontal portion 27 is fitted into the storage space. Further, as shown in FIG. 5, a support member 27 around which the heater wire 9 is wound may be fitted to the outer surface of the outer cylinder 8. The support member 27
Is composed of a support portion main body 27C which is open on the outside and has an annular heater wire storage portion, and a cylindrical portion 27D for closing an outer opening of the support portion main body 27C. The other configurations shown in FIGS. 4 and 5 have different shapes from those in FIG. 2, but are functionally the same, so they are denoted by the same reference numerals and description thereof is omitted.

FIG. 6 shows an FM-modulated capacitance type clearance measurement system for measuring a clearance based on an output signal (output voltage) from the capacitance type probe 3. That is, the capacitance type probe 3 and the triple coaxial cable 14, a transmitter 15 installed at a measurement location, a demodulator 16 installed at a remote location, a speed module 17,
Although the system is configured from the signal processing module 18, the system may be configured by an AM modulation type device other than the configuration illustrated in the figure.

The transmitter 15 supplies a transmission voltage to the capacitance type probe 3 through the triple coaxial cable 14. In this state, when the blade 1A passes through the tip of the capacitance type probe 3, the capacitance that changes between the two is detected, and the carrier wave of the transmission circuit is modulated according to the change. Then, the frequency change is demodulated by the demodulator 16 from the frequency-modulated carrier. The frequency change is converted into a voltage signal by a frequency-DC converter circuit. Therefore, the output voltage of the demodulator 16 is proportional to the capacitance between the capacitance type probe 3 and the blade 1A. Factors giving the change in the capacitance include the shape of the blade 1A facing (facing) the capacitance probe 3 and the change in the distance between the blades 1A, 1A, and the clearance between the capacitance probe 3 and the blade 1A. Although it is a change, usually during operation (rotating body 1
(During rotation), the shape of the blade 1A facing the capacitance type probe 3 and the distance between the blades 1A, 1A do not change. Change.

Reference numeral 19 shown in FIG. 6 is an oscilloscope, which displays a voltage waveform and an effective value voltage that change when the blade 1A passes therethrough. These displays are drawn in a non-linear manner.

The speed module 17 includes a demodulator 1
6, which is used in combination with 6, and measures the period of the demodulator output signal waveform to create a speed signal. By simply setting the number of blades (wings) in the front panel of the speed module 17 in advance, the rotation speed of the rotating body 1 is displayed on the front panel of the speed module 17.

The signal processing module 18 is used in combination with the demodulator 16 and the speed module 17, and converts the “non-linear stepped signal” from the demodulator 16 into a linear signal. The stepped signal converted (linearized) into a linear signal is output to the speed module 17.
The maximum value, the minimum value, and the average value for each rotation of the rotation shaft 1B are output using the signal for each rotation of the rotation shaft 1B. If a rotation signal can be obtained from the outside, it can be used. Further, the maximum value, the minimum value, and the average value within the set time can be output by using the internal timer. In the linearized signal of the signal processing module 18, a voltage of 1 volt corresponds to 1 mm, and the maximum value, the minimum value, and the average value are also units (mm) of the physical quantity of the clearance. The clearance values converted (linearized) into these linear signals are output signals to the personal computer 20 for displaying measured values in real time using data recording software. The position of the flange portion 8F or 10F provided in the capacitance type probe of FIGS. 2 to 5 may be other than the position shown in the drawings. Also, the capacitance type probe is attached to the casing 2 via the flange 8F or 10F.
Is omitted, and the casing 2 is provided on the outer peripheral surface of the capacitance type probe.
Alternatively, a male screw portion that is screwed into the female screw portion formed in the through hole 2K may be formed, and the capacitance type probe may be screwed into the through hole 2K and attached.

[0022]

According to the first aspect of the present invention, by heating the insulating layer by the heating means, even if the moisture that tries to enter the insulating layer enters the insulating layer, or if the moisture enters the insulating layer, the moisture immediately enters the insulating layer. Can remove moisture,
Since it is possible to reliably prevent the insulation resistance from being lowered by moisture, it is possible to provide a capacitance type probe capable of performing stable measurement without being affected by moisture.

According to the second aspect, the heating means is constituted by a heater wire wound around the outer surface of the outer cylinder, so that the heater wire can be mounted without any improvement to the existing capacitance type probe. Can be. Further, even if the heater wire is attached, the measurement is not affected at all.

According to the third aspect, the capacitance type probe may be provided on the wall surface of the casing through which the fluid passes, and the heater wire may be wound around only a part of the outer surface of the outer cylinder on the outer side of the casing. By increasing the number of turns or the like, the same heating effect as when a heater wire is wound around the entire outer side of the casing can be obtained, and the degree of freedom in design can be increased.

According to the fourth aspect of the present invention, the heater wire, the supporting member which is formed separately from the heater wire and the heating means are constituted, so that the heater wire is connected to the capacitance type probe via the supporting member. Since it can be attached, when replacing the heater wire, it is only necessary to attach and detach the support member to and from the capacitance type probe, and it is possible to dramatically improve the operability when replacing the heater wire. it can.

According to the present invention, the heating means is set to the operating state when the rotating body is not rotating, and switching means for switching the heating means from the operating state to the non-operating state after a lapse of a set time from the start of rotation of the rotating body is provided. In addition, the running cost can be reduced and the life of the heating means can be extended as compared with the case where the heating means is always kept in the operating state, and a capacitance type probe which is advantageous in terms of use can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view in which a plurality of capacitance type probes for measuring a clearance between a wall surface of a casing and a rotating body are attached to a casing.

FIG. 2 is a cross-sectional view showing a structure of a mounting portion of the capacitance type probe.

FIG. 3 is a cross-sectional view showing a structure of a mounting portion of another capacitance type probe.

FIG. 4 is a cross-sectional view showing a structure of a mounting portion of another capacitance type probe.

FIG. 5 is a cross-sectional view showing a structure of a mounting portion of another capacitance type probe.

FIG. 6 is a block diagram showing a capacitance type clearance measurement system.

FIG. 7 is a sectional view showing a conventional capacitance type probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating body 1A Blade 1B Rotary shaft 2 Casing 2A Wall surface 2K Through hole 3 Capacitive probe 4 Electrode 5 Insulating layer 6 Guard member 7 Insulating layer 8 Outer cylinder 8F Flange 9 Heater wire 10 Cover body 10A Cylindrical section 10B, 10C Lid 10F Flange 11 Signal line 12 Signal line 13 Ground wire 14 Triple coaxial cable 15 Transmitter 16 Demodulator 17 Speed module 18 Signal processing module 19 Oscilloscope 20 PC 21 Ring member 22 Connection member 23 to 26 Insulation layer 27 Support member 27A Horizontal part 27B Tube part 27C Support part body 27D Cylindrical part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mark Liddell UK 389 TN, Tyne and Wear, Washington, 4 Setting Stones F-term (Reference) 2F063 AA23 BA04 BC05 BD16 CA31 CB03 DA05 DB01 DB07 DD02 DD03 DD04 DD06 HA04 HA09 HA20 PA01 PA03 ZA01

Claims (5)

[Claims] An outer cylinder positioned radially outward, a guard member positioned radially intermediate, an electrode positioned radially inward, and between the outer cylinder and the guard member and between the guard member and the electrode. Measuring the distance between the wall of the casing and the rotating body having a discontinuous outer surface such as a blade or the like from the outer surface of the rotating body having a continuous outer surface such as a disk or a shaft. A capacitance type probe for measuring a distance, wherein a heating means for heating the insulating layer is provided. 2. The capacitance type probe according to claim 1, wherein said heating means is a heater wire wound around an outer surface of said outer cylinder. 3. The capacitance type probe is provided on a wall surface of a casing through which a fluid passes, and the heater wire is wound around only a part of an outer surface of the outer cylinder on an outer side of the casing. Or the capacitance type probe according to 2. 4. The capacitance type probe according to claim 1, wherein said heating means comprises a heater wire and a support member for accommodating said heater wire, said heating means being mounted via said support member. 5. A switching means for setting the heating means to an operating state when the rotating body is not rotating, and for switching the heating means from an operating state to a non-operating state after a lapse of a set time from the start of rotation of the rotating body. Item 5. The capacitance type probe according to any one of Items 1 to 4.