JPS5923221A - Scale accumulated quantity detecting method in nonmagnetic steel pipe, and device used for said method - Google Patents

Abstract

PURPOSE:To execute safely a quantitative detection of accumulated scale quantity, bt detecting magnetically the accumulated scale quantity by a probe by utilizing magnetism of the scale accumulated in nonmagnetic austenite stainless steel pipe. CONSTITUTION:A probe body 3 which contains a magnetic field generating magnet, a high sensitivity magnetism detecting element for detecting a magnetic flux variation, etc., and is capable of adjusting freely a gap to a stainless steel pipe by an adjusting bolt 5 is provided in a housing 2 which is freely movable in the axial direction of a nonmagnetic austenite stainless steel pipe of a superheater pipe, etc. of a steam boiler through a wheel 4. Also, a notch provided on a rim 4a of the wheel 4 is detected by an optical sensor 8 and a moving distance of the probe 3 is detected. When scale adheres to the inside of the stainless steel pipe, an output of the probe 3 by the high sensitivity magnetism detecting element is varied by magnetism of the scale. When a gauging diagram based on the scale quantity of a known quantity is referred to by this output, a quantitative detection of estimated quantity of scale can be executed safely without using a radiant ray, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to eliminate SUS scale deposited in non-magnetic austenitic stainless steel tubes, which are used, for example, as tubes in P1 and reheaters of steam boilers for thermal power generation. The present invention relates to a detection method and a device used therefor.

Failure of steam boilers, etc.! If scale is deposited in the J11 vessel or FHjH vessel, heat transfer will be poor, local stress will increase and rupture may occur, and if scale enters the turbine chamber, the turbine play 1- will become tfi. Problems such as damage or blockage of the nostle may occur, and ultimately the power generation capacity must be snubbed.

The trick is to detect the amount of ζ scale sediment and clean the inside of the pipe. Conventionally, this screen
However, this method using radioactive 71J radiation was found to be 1J by radiographic examination on the day of the detection investigation. There is a risk of exposure to 14-ray radiation, and the inspection cost per tube is high (therefore, if it is not possible to inspect all the tubes, a sampling inspection method must be used, and scale detection cannot be completely performed. There is a drawback that there is no

The present invention aims to solve the above-mentioned problems, and aims to provide a method for detecting scale deposit m that can quantitatively determine scale deposit m in a steel pipe, and an apparatus used in the fifth detection method. That is.

Hereinafter, the present invention will be explained based on examples.

Figure 1 shows a scale accumulation amount detection device (hereinafter referred to as “detection device”).
That's what it means. ) (1) A partially cutaway side view of J9 is shown.
The detection device has a configuration in which a probe body (3) is built into a housing (2) having a substantially rectangular hollow cross section, and a wheel (4) is rotatably mounted on the probe body 431 full iE body +21. J has been written. The probe body (3) has a hole 1-(5) for adjusting the probe position so that the detection f+1i (3a) can be adjusted to the optimal position for detection according to the outer diameter of the tube to be inspected. ) and has a grooved bottom so that the probe body (3) can be freely moved within the housing (2) by operating a dial (6) outside the housing (2).

In order to detect the moving distance during inspection, this detection device is equipped with a frame (7) that is designed to measure the distance traveled by the IF body (2).
A sensor (81) consisting of a light-emitting element and a light-receiving sample is installed in the frame (7), and a sensor (81) is installed on the outer periphery of the rim (4a) of the wheel (4). (1'j (411 is used to detect the moving pressure vessel l). In other words,
Cut out the outer peripheral surface of the rim (4a). ? j Except for f91, the wheels are painted black, and the cutout grooves (9) are made to have a 1.1 plane of development, so that an I-pulse signal is output per rotation of the wheel. Figure rl] ft1ll is the probe body (3
) and shinri'-([This is a signal cable that takes out the output of 1.

Figure 2 shows the scale detection circuit, and the detection device (
The output signal from 11 and the signal from range 11 (8) are sent to a two-pen recorder, for example, and the voltages associated with the scanning position and scale deposition are recorded on a recording paper.

The scale detection device according to the present invention is a highly sensitive magnetic detection device, the operating principle of which is shown in FIG.

In Fig. 3, if the magnet inside the probe body is in the air, and the magnet does not have a single target (object to be investigated), then the magnetic field lines that are native to the magnet will be zero at the center point of the magnet. Therefore, no output is generated at a and a'. In this case, if output occurs at a or a', the position or characteristic balance of the detection element is out of balance, so
Adjust so that it becomes zero using the zero point adjustment volume. Next, when the magnet is brought into contact with the object to be investigated (71), the zero point position shifts and magnetic flux φ1 acts on the detection elements a and a', producing an output.

Moreover, this change produces the same output of 1 m in the volume of the surveyed moon.

The scale measuring method using the above detection device (1) and acid one-path configuration will be explained.

-711, it is known that when scale is deposited inside a non-magnetic Austenite 1 stainless steel pipe, this scale becomes magnetic, and when the probe of a scale detection device approaches it, the scale deposits and detects it. It is possible to change the output according to the amount of scale in the pipe,
Probe contact value (a, affected by the degree of contact)
Therefore, the following method is used to measure the scale M with good tff accuracy.

In the detection method according to the present invention, a test tV having the same shape as the tube to be inspected (f-tf') is provided, filled with a scale of known M (or iron t5)), and the output indicated value by the probe is measured by the probe. Create a calibration curve diagram in advance and use the instructions If
By applying f to this calibration curve, it is intended to quantitatively determine the scale deposition (1).

The procedure will be described below. As shown in Figure 4, we will take one eggplant bamboo ('r) with 11 eggs (D), 5 wall thicknesses (1), and the pipe length of about 50. +U+ degree and at least 4 reviews"-Create. Then, a scale (or iron 15) (S) is added inside, but in this example, as shown in Figure 5, it is a senior minister! I((Figure 5(a)
The full state of l is 1009 stones. )] 00
, 75 , 50 .

It will be 2596.) Fill it with 1, and close both α1j11 with transparent vinyl etc. so that the filling state can be seen from the outside. Ku.

Arrange the probe body (3) of the scale detection device (1) in the ∆ or C direction (not shown in Figure 6) by aligning it with the above case 1 tube (T).
Read the instructions for the output of the same program 1; 1-buo body (3) by getting close to it or touching it. This operation is performed on all eggplants, one bamboo shoot, and the indicated value is plotted as shown in FIG. 7, and a comparison line between mm% and the indicated value is plotted, and this can be used as a calibration curve.

In the above, scanning the probe body (3) with respect to the tube from the 8 or C direction provides the best linearity according to the change in the amount of scale in the tube, especially the change in weight % near 50% (= J). It's for a reason.

In addition, in the m6 diagram, when scanning from the D direction, instructions cannot be obtained unless the scale is nearly 100% filled (see Figure 8), and furthermore, when scanning from the B direction of the same diagram, the indication is not obtained when the amount of scale accumulation increases. This is because J9J cannot be used to quantitatively grasp the amount of scale (see FIG. 9).

After creating the calibration curve, a scale detection investigation of the tube to be tested is carried out on site, and the adjustment of the attitude of the probe unit (3) is carried out with the test tube ('F) as the basis.

On-site investigation to check for presence of scale 1■
A survey is conducted, and a tree density survey is conducted after the rough survey, and the indicated value of the tfj fine survey is converted into a -ζ scale deposition amount W- (estimated) using a calibration diagram.

Since the 111 investigation checks the existence of a pool, Figure 6B, which shows the wall + F1 most clearly,
Detection in direction! ji ii'i', (scan 11!
In this investigation, if the output instruction value of the probe body (3) is O, 4″11j dense adjustment 311: is not necessary.

O 11 High J Exam 1 Many It'/j Close E Examination is Bl l
It is necessary to collect data for the signal UtfH signal and the IIF determination in step 1). This signal is used to confirm the presence of magnetism such as limescale inside the pipe to be inspected, magnetization due to stainless steel silk deformation, and iron deposits on the outside surface of the pipe.A in Figure 6. B.

This is performed every time scanning is performed from the C, D direction or any other desired direction.

11fl Symptomffl If data can be collected by scanning in the same direction as when creating the inspection m line, that is, in the 8 or 13 direction shown in Figure 6, but with the detection device (1) The scanning state will be described with reference to FIG. 1O. The test tube ('F) in Fig. 6 is aligned with the test tube '1' on which scale S is deposited.
The detection device (1) is located in the A direction and the opening force direction side.
U. Hold the detection device by hand and move it in the axial direction of the tube T to be inspected. As a result, the indicated value is drawn on the recording paper, and the pulses generated by the sensor (8) at every fixed distance of movement generated by the rotation of the wheel (4) are also recorded on the recording paper.

Therefore, since the scanning point in the direction of the bamboo axis is shown, it is possible to know where the deposited scale is present in the tube to be inspected.

Based on the indicated value data obtained above, the amount of scale deposited is expressed in weight % using the calibration curve shown in Figure 7 using one eggplant tube (T), and the amount of deposited scale is determined by full verification. It's something you can do.

As described above, the present invention firstly moves a probe having a built-in magnet that generates a magnetic field and a high-sensitivity magnetic detection element that detects changes in magnetic flux along the longitudinal direction of a non-magnetic steel pipe; This method detects the amount of scale deposited in a non-magnetic steel pipe by detecting scale deposits in an open pipe by the output of It has the excellent effect of being able to accurately determine the IIn, and secondly, the probe body is housed in a housing that is equipped with a magnet that generates a magnetic field and a highly sensitive magnetic detection element that detects changes in magnetic flux. (Along with J, the detection end, which is the side of the high-sensitivity magnetic detection element, is an open case)
I bought it so that I could adjust the ■ protruding from it by 1 Jlil,
Wheels are installed on both sides of the detection end of the main body of the same housing,
Moreover, since it is a scale accumulation detection device that detects scale deposits on non-stick steel wheels, it is equipped with a unit that outputs a signal according to the number of rotations of the wheel. When performing detection after adjusting the advance m of the probe body, the measurement is performed while moving along the length of the tube while keeping the gap from the detection O1:+ aligned on the surface of the tube to be inspected constant. This has the effect of being able to

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway surface diagram of the scale deposition detection device, Fig. 2 is a block diagram of the electric 10 mark δ that processes the output of the detection device, and Fig. 3 is an explanatory diagram of the operating principle of the magnetic detection device. Fourth
The figure shows a front view and a side view of the test tube, Figure 5 is a schematic diagram of the test tube filled with a predetermined fl' [%], and Figure 6 shows the probe body as seen in Test 111゛. An explanatory diagram showing the approach direction, Figure 7 is a calibration curve obtained with a test tube, Figures 8 and 9 are calibration curves when changing the approach direction of the probe, and Figure 10 is a calibration curve obtained from the test tube. FIG. 3 is a front view showing the detection device in a flattened state. (1) - Scale jlfi ■ Detection device (2) - Housing (3) Probe body (3a) - Detector, 1 (4) - Wheel (4a) - Notch groove rim (5) - Blowoff position Pole 1 (6) Key probe position 1J7I Diameter for Ti
Mounting number J frame (8) - Seven pins' - (9) - (J) Missing ^r (10) - Signal cable 11W Applicant Electronic r6ke] Nigyo Co., Ltd. Agent of Shin Nippon Nondestructive Testing Co., Ltd. People Tegumi Masu (2 idiots)

Claims (1)

[Claims] 1. A probe incorporating a magnet that generates a magnetic field and a highly sensitive magnetic detection element that detects changes in magnetic flux is moved along the longitudinal direction of a non-magnetic steel pipe. A method for detecting the amount of scale deposits in a non-magnetic steel pipe, comprising detecting scale deposits in the non-magnetic steel pipe based on the output of the above. 2. Place the probe body, which is equipped with a magnet that generates a magnetic field and a high-sensitivity magnetic detection element that detects changes in magnetic flux, into the housing, and place the detection end, which is the side of the high-sensitivity magnetic detection element, inside the housing. ■ that protrudes from the opening θ11) of the body is I! It is configured so that it can be connected to the probe body in the same housing.
．． What is claimed is: 1. A scale pile view detection device mounted on a non-magnetic steel pipe, characterized in that wheels are provided on both sides of the i side, and a sensor is provided for outputting a signal corresponding to the number of rotations of the wheels.