JPS607306A - Measuring device for thickness of scale in pipe - Google Patents

Abstract

PURPOSE:To make it possible to measure the thickness of attached scale without destruction in a short time, by detecting the change in impedance by filling a pipe with a magnetic fluid including magnetic colloid. CONSTITUTION:The inside of a pipe to be measured 11 is filled with a magnetic fluid 12 including magnetic colloid 19. A DC exiting coil 16 is provided on the outer surface of the pipe 11, and a magnetic force is applied to the fluid 12. Thus the colloid 19 is collected. Meanwhile a detecting coil 18 is provided in close proximity to the coil 16. When a high frequency voltage is applied to the coil 18, the impedance of the coil 18 is changed by the magnetic reciprocal action with the colloid 19, which is collected to the surface of scale 13, based on the amount of the colloid 19 and the distance between the colloid 19 and the coil 18. Therefore, by measuring and analyzing the change in impedance of the coil 18, the thickness of the scale 13 can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal scale measuring device L61 for measuring the thickness of scale attached to the inner surface of a boiler tube or the like.

When measuring the thickness of scale attached to the inner surface of boiler tubes, tanks, cylinder piping, etc., conventional measurements r, N
Remove the tube at i location II! ,! Generally, a destructive method was adopted in which djQ was determined for one side of the cut.
However, it takes time to determine dil, and it is not possible to use the dill constant again. Therefore, the location to be measured must be thoroughly inspected using a new probe. This does not only mean that it is costly, but also that it is possible to determine the Jm of the same 4111, but if there is an object that truly requires inspection other than the 1111 fixed point and it is difficult to perform a destructive inspection, it is difficult to determine the dl for this object. −
I can't do it.

Non-(N, destructive?I11) methods using ultrasound, X-ray transmission, and heat flow can be considered, but the acoustic properties of the scale, the small absorption of X-rays, and the scale Due to reasons such as the fact that they do not have any thermal effect, none of them are practical in principle and have not been put to practical use.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an in-pipe scale measuring device that non-destructively measures scale attached to the inside of a boiler tube or the like.

That is, the pipe scale measuring device according to the present invention includes a magnetic fluid containing magnetic colloid filled in the pipe to be measured;
A DC +11/16G coil is attached to the outer peripheral surface of the above-mentioned broken 11111 fixed tube and applies a magnetic force to the above-mentioned magnetic fluid to collect the magnetic colloid, and a DC +11/16G coil is provided close to the above-mentioned excitation coil to collect the collected colloid. The detection coil is provided with a detection coil to which a high frequency signal whose impedance is changed according to the relationship , and the impedance of the detection coil is detected.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the state of the measuring section, in which the interior of a cheap 11 to be measured is filled with a magnetic fluid 12 mixed with a specified mouse magnetic colloid. Here, 13 is scale attached to the inner wall of tube 1. Then, a detection instrument 14 is placed opposite to the outer peripheral surface of the tube 1 to be measured. This detection instrument 14 includes an iron core 15 having a TSi-like shape, and an excitation coil 16 is wound around the outer periphery of the iron core 15. In addition, a columnar iron core 17 is inserted into the hollow part of this iron core 15, and a detection coil 18 is completely wound around this iron core 17, so that the opening surface of the iron core 15 has a broken 6i11 constant tape. It should be possible to set it in contact with the outer circumferential surface of No. 1. Here, when a DC excitation current is supplied to the excitation coil 16, the magnetic force of the excitation coil 16 causes the 11-tonne colloid 19 in the magnetic fluid 12 to:,'
H43 is found on the surface of the scale 13 at a fixed location. In this state, high frequency pressure is applied to the detection coil 18, which is similarly formed inside the iron core 15. The impedance of the detection coil 18 changes depending on the distance between the colloid 19 and the detection coil 18 due to the magnetic interaction with the magnetic colloid 19 collected on the surface of the scale 13. The thickness of the scale 13 is measured by measuring and analyzing the change in impedance of the coil 18.

Figure 2 shows the circuit h (13) of this measuring device. An AC power source 20 supplies power to the rectifier circuit 2 and the oscillator 22. The DC power supply is supplied to the DC stabilization πL%j23, which supplies a stabilized DC excitation current to the excitation coil 16.The oscillator 22 also generates a high frequency voltage signal.

This high frequency voltage is supplied to the AC bridge 24 including the detection coil 18. This AC bridge 24 is
3 which incorporates the detection coil 18 and temperature compensation and comparison circuit.
It is formed from two IζCL circuits 25°26.27, and is configured so that when the impedance of the detection coil 18 changes, the phase and amplitude of the high frequency output from the AC bridge 24 changes. The high frequency signal output from the AC bridge 24 is then amplified by an amplifier 28 and supplied to a phase amplitude lid measurement circuit 29. This measurement circuit 29 uses a high frequency signal from an amplifier 28 and an oscillator 22.
Compare the high frequency signal from the meter side, perform θ1 analysis, and output from a cathode ray tube, etc.! , #It-t 30, scale 13
This indicates the thickness of the material.

As described above, according to the present invention, inside the neck or pressure vessel:
・The thickness of the scale ft and i'r on the inner surface of I,
It is possible to provide a device that performs measurements non-destructively within a short period of time.

[Brief explanation of drawings]

FIG. 1 shows the pipe scale according to the present invention, which is certain V/lJ; ill+constant:, i, '4, i, ? 1ffi plane view explaining the measurement part of
FIG. 2 is a block diagram showing a measurement circuit using a fixed part. 1)...Tube, 12...Magnetic 010 body, 13.
...Scale, 14...Detection instrument, 15 crest + J center for magnetic coil, 16...1 excitation coil, 17...Iron core for detection coil, 18...Detection coil, 19...Magnetic colloid , 20...father υ1masa [ra source, 2)...rectifier circuit, 22...oscillation, sound, 23...DC stabilization-■L source, 24...AC θ; L bridge, 2s , 2t; ,
,? 7 ・RCL circuit, 2 B...amplifier, 2
9... Phase/oscillation 11 6 measurement circuit, 3o... output device.

Claims (1)

[Claims] A magnetic fluid containing a magnetic colloid filled in the tube to be measured, a DC excitation coil disposed opposite to the outer peripheral surface of the tube to be measured and applying a magnetic force to the magnetic fluid to collect the magnetic colloid, and a DC excitation coil adjacent to the excitation coil. A detection coil provided as a top surface 3 and supplied with a high frequency signal whose impedance changes depending on the relationship with the collected magnetic colloid, and a change in impedance of the detection coil is detected. Scale measuring device.