System and method for detecting thickness of industrial boiler scale based on SH (Shear) wave

A technology for industrial boilers and thickness detection, applied in measuring devices, using ultrasonic/sonic/infrasonic waves, using sound waves/ultrasonic/infrasonic waves to analyze solids, etc., can solve problems such as indistinguishable, overlapping reflected waves, and limited measurement accuracy, and achieve good results The effect of measurement accuracy

Inactive Publication Date: 2010-09-01
BEIJING UNIV OF TECH
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Problems solved by technology

However, when the scale thickness is thin, the reflected waves overlap, making it difficult to distinguish, and the measurement accuracy is limited

Method used

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  • System and method for detecting thickness of industrial boiler scale based on SH (Shear) wave
  • System and method for detecting thickness of industrial boiler scale based on SH (Shear) wave
  • System and method for detecting thickness of industrial boiler scale based on SH (Shear) wave

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Embodiment Construction

[0043] Concrete implementation steps of the present invention include:

[0044] Step 1: Draw the dispersion curve

[0045] The dispersion equation (9) derived from the wave model of SH waves in the double-layer structure is used to build a model for the boiler wall and scale structure. In this example, 8mm steel plates are used as the boiler wall, and 0.5mm-3mm marble is selected. (The chemical composition is calcium carbonate, which is the same as that of ordinary scale.) As scale, the thickness of scale is selected between 0-3mm, and a dispersion curve is drawn every 0.1mm. The SH wave dispersion curves under different scale thicknesses are attached Figure 3-9 shown.

[0046] The acoustic parameters of steel plate and marble are as follows:

[0047]

[0048] Step 2: Draw the dispersion curves of the SH0 mode under different scale thicknesses

[0049] Extract the dispersion curve of the SH0 mode from the dispersion curve obtained in step 1, and draw it in the same gra...

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Abstract

The invention relates to a method for detecting the thickness of industrial boiler scale by utilizing an SH (Shear) wave which is sensitive to an attachment on the surface of a plate layer, belonging to the field of nondestructive inspection of ultrasonic guided waves. In the method, firstly, a dispersion curve with different scale thicknesses is drawn by utilizing a dispersion equation for SH wave propagation in a double-layer structure to obtain a variation curve of SH0 modal group velocity changing along with the increase of the thickness of the scale, and then a high detection frequency and a low detection frequency respectively corresponding to thinner scales and thicker scales are further obtained. A detection system is shown as the drawing and comprises a function generator (1), a power amplifier (2), a change-over switch (3), an EMAT (Electromagnetic-Acoustic Transducer) sensor (4), an oscillometer (5) and a computer (6). The group velocity of an SH0 modal in a structure formed by a boiler and scales can be measured by the system, and the thickness of the scale can be obtained according to the corresponding curve of the group velocity and the scale thickness by the calculation, thereby the online and nondestructive testing on the thickness of the industrial boiler scale is realized.

Description

technical field [0001] The invention belongs to the field of ultrasonic guided wave non-destructive testing, in particular to a method for detecting scale thickness of industrial boilers by using SH waves (horizontal shear waves). Background technique [0002] Boiler is an important energy conversion equipment, which plays an irreplaceable role in industrial production and daily life. Especially in the power industry, the boiler unit is one of the three main forces of thermal power plants. However, during the operation of the boiler, since the water contains calcium and magnesium salts with low solubility, after continuous evaporation and concentration, when the concentration of impurities in the water reaches saturation, precipitation will occur and adhere to the inner wall of the boiler to form A crusty layer, this is limescale. [0003] Scale has great harm to industrial production: First, the thermal conductivity of scale is dozens or even hundreds of times worse than ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B17/02G01N29/12
Inventor 何存富郑阳吴斌李杨周进节宋国荣
Owner BEIJING UNIV OF TECH
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