Built-in high-voltage low-temperature electrical capacitance tomography sensor and installation method

Abstract

The invention discloses a built-in high-voltage low-temperature electrical capacitance tomography sensor and an installation method. The sensor comprises a metal pipeline, a signal wire, a built-in sensing pole piece, an axial shielding ring and a fixing tool, one end of the metal pipeline is provided with a standard flange, and the other end of the metal pipeline is provided with a drilling flange; the drilling flange is formed by performing radial drilling on a standard flange between the mounting holes, and the radial drilling hole serves as a leading-out channel of a signal wire. The built-in sensing pole piece and the axial shielding ring are placed on the inner side of the high-pressure thick-wall pipeline through a built-in method, phase distribution imaging in the low-temperature high-pressure pipeline is achieved, and the problems that the imaging precision of the thick-wall pipeline is low, and a signal wire of the inner pipeline is led out are solved.

Description

Technical Field

[0001] The present invention relates to the fields of cryogenic refrigeration engineering technology, fluid flow process monitoring and sensor science and technology, and in particular to a built-in high-voltage and low-temperature capacitance tomography sensor and an installation method thereof. Background Art

[0002] Gas-liquid two-phase flow is a common flow form in cryogenic fluid (fluid with a temperature below -150°C) devices, such as aerospace fuel tanks, liquefied natural gas pipelines, and liquid hydrogen plants. Therefore, determining the phase distribution is crucial to the cryogenic fluid industry. Parameters such as the two-phase flow state and cavitation rate derived from the phase distribution are important parameters of the fluid flow state. However, due to the properties of cryogenic fluids and the working environment, the measurement of cryogenic fluid phase distribution remains a thorny issue.

[0003] Capacitance tomography (ECT) is a non-invasive measurement technology, which includes a front-end sensor, a capacitance data acquisition system, and a back-end host computer. The front-end sensor can be installed outside the fluid to be measured or even the pipe to be measured. By measuring the capacitance information of the working fluid between the sensor electrodes, the image of the fluid phase distribution inside the sensor is obtained through the algorithm inside the host computer.

[0004] The original intention of establishing the electrical capacitance tomography system is to use a non-invasive and non-contact method to detect the phase distribution of the fluid inside the pipeline. The electrical capacitance tomography system has good performance in imaging normal temperature, high temperature fluids and even low temperature fluids at normal pressure. With the application of deep neural network methods, the imaging accuracy of electrical capacitance tomography has been significantly improved.

[0005] Since the basis of the capacitance tomography system is the capacitance difference between different phases of the two-phase flow, the material of the detection section of the pipe where the capacitance tomography sensor is installed needs to be an insulator, so that a capacitor can be formed between the sensor pole pieces, rather than directly short-circuiting. In this way, the medium between each pair of sensor pole pieces is the pipeline wall and the two-phase flow medium. The change in the phase distribution of the two-phase flow medium will correspondingly change the dielectric constant distribution of the two-phase flow medium, thereby causing a change in the capacitance between each pair of sensor pole pieces. After all capacitance changes are collected by the capacitance data acquisition system and entered into the host computer, the two-phase flow phase distribution image can be calculated by the corresponding algorithm in the software.

[0006] It can be seen that the existence of the pipeline is irrelevant in the entire acquisition process. It is only a container used to limit the two-phase flow fluid. In terms of detection principle, the change of the two-phase flow will not cause the phase change of the pipeline, and thus will not cause a significant change in the dielectric constant of the pipeline. At the same time, if the change in capacitance caused by the change in the dielectric constant is called sensitivity, the sensitivity calculated at different positions of a pair of pole pieces in the calculation domain is different. Combining these sensitivities into a matrix can obtain the sensitive field of the capacitance of a pair of pole pieces in the calculation domain. From the sensitive field image in the figure below, it can be seen that the sensitive field value close to the pole piece is larger, that is, the capacitance change caused by the change in the dielectric constant is more drastic near the pole piece, which is also in line with intuitive feelings.

[0007] This brings up the issue of pipe wall thickness. The presence of the pipe wall is located in the most sensitive thickness area of ​​the system, but the presence of the pipe wall does not contribute to the imaging process at all, but instead encroaches on the required calculation domain inside the pipe. This phenomenon can be summarized as the pipe wall reducing the effective measurement domain.

[0008] In conventional electrical capacitance tomography application scenarios, thick-walled pipes are not common. But in high-pressure and low-temperature scenarios (pressure above 1.6MPa), it is inevitable. In high-pressure and low-temperature scenarios, extremely thick non-metallic materials are required to ensure their safety. For example, the wall of a standard DN32 pipe under a pressure of 1.6MPa is more than 5mm. The pole piece of the traditional external sensor is arranged outside the fluid pipe. Due to the decrease in the effective measurement domain, the capacitance measurement accuracy and the final imaging accuracy will become extremely low, which makes the external electrical capacitance tomography system unsuitable for high-pressure and low-temperature scenarios. Summary of the invention

[0009] In order to solve the problems in the prior art, the present invention provides a built-in high-voltage and low-temperature capacitance tomography sensor and an installation method, which can realize the detachable installation of the sensor and the incoming flow pipeline. The size of the sensor can be determined according to the needs, and it is only necessary to ensure that the flange size at both ends is consistent with the incoming flow pipeline. The connection with the capacitance tomography system is a signal wire, and no other connection is required. It has the advantages of simple structure, sturdy shell, and easy installation.

[0010] To this end, the present invention adopts the following technical solutions:

[0011] In one aspect, the present invention provides a built-in high-voltage and low-temperature capacitance tomography sensor, which includes a metal pipe, a signal wire, a built-in sensing electrode, an axial shielding ring, and a fixing tool;

[0012] A standard flange is provided at one end of the metal pipe, and a drilled flange is provided at the other end; the drilled flange is obtained by evenly arranging a plurality of radial holes along the circumferential direction on the outer edge of the standard flange; the radial holes penetrate the drilled flange and the metal pipe;

[0013] The fixing fixture is detachably fixed inside the metal pipe, the fixing fixture is cylindrical, and its outer surface is provided with a mounting groove for fixing the signal wire; there are two axial shielding rings, which are respectively arranged at both ends of the inner surface of the fixing fixture for shielding the axial magnetic field outside the measurement domain; there are multiple built-in sensing pole pieces, which are evenly arranged on the inner surface of the fixing fixture along the circumferential direction, and the built-in sensing pole piece is arranged between the two axial shielding rings; one end of the mounting groove is connected to the radial hole, and the other end is connected to the connection position of the built-in sensing pole piece through an opening, and the opening is used for the signal wire to pass through and connect the built-in sensing pole piece;

[0014] The signal wire is a shielded wire; one end of the signal wire is connected to the connection position of the built-in sensing electrode, and the other end is led out to the outside of the sensor along the opening, the installation groove and the radial hole.

[0015] The built-in sensing electrode is in direct contact with the low-temperature fluid to be measured. The thickness of the built-in sensing electrode is consistent with that of the axial shielding ring. The built-in sensing electrode and the axial shielding ring are installed in a mounting groove preset on the inner surface of the fixed tooling, and the depth of the inner surface mounting groove is consistent with the thickness of the built-in sensing electrode and the axial shielding ring.

[0016] The present invention also provides a method for installing the built-in high-voltage and low-temperature capacitance tomography sensor, which comprises the following steps:

[0017] 1) Install the built-in sensor pole piece and axial shielding ring in the installation groove reserved on the inner surface of the fixed tooling, and use low-temperature glue to glue them. After installation, ensure that the built-in sensor pole piece and axial shielding ring are flush with the inner surface of the fixed tooling; connect one end of the signal wire to the connection position of the built-in sensor pole piece;

[0018] 2) Arrange the other end of the signal wire along the mounting groove on the outer surface of the fixed tooling, and use sealant to seal the connection between the mounting groove and the mounted sensor electrode;

[0019] 3) Install the installation tool inside the metal pipe;

[0020] 4) Pass the signal wire through the radial holes inside the metal pipe;

[0021] 6) Use low-temperature glue to completely seal the radial holes;

[0022] 7) Connect the standard flange and the drilled flange to the flange of the section to be inspected respectively, and connect the signal wire to the capacitance tomography system.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention provides a built-in high-pressure and low-temperature capacitance tomography sensor, which can realize the detachable installation of the sensor and the incoming flow pipeline. The geometric dimension design of the installation tool can ensure that the inner diameter of the incoming flow pipeline is consistent with the inner diameter of the sensor flow channel, ensuring the stability of the working medium flow and the consistency of the phase distribution inside and outside the sensor.

[0025] 2. The present invention provides a built-in high-voltage and low-temperature capacitance tomography sensor, in which the connection of the capacitance tomography system is a signal wire, and no other lines are required.

[0026] 3. The present invention provides a built-in high-pressure and low-temperature capacitance tomography sensor, in which the subject pipeline is a metal pipeline and can withstand the pressure requirements of high-pressure application scenarios.

[0027] 4. The present invention provides a built-in high-pressure and low-temperature capacitance tomography sensor, whose electrode is built-in. In the application scenario where the wall thickness of the high-pressure pipeline is relatively thick, it can effectively avoid the poor imaging effect of the external sensor on the thick-walled imaging pipeline, and obtain a high-precision two-phase flow working fluid phase distribution image in the pipe.

[0028] 5. The present invention provides a built-in high-voltage and low-temperature capacitance tomography sensor, in which the internal and external signal wires are the same, instead of using a plug to achieve the transmission of internal and external signals, which effectively reduces the interference of analog signals in the plug due to stray capacitance and parasitic capacitance, and reduces interference and noise in the signal transmission stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an isometric view of the overall structure of a built-in high-voltage and low-temperature capacitance tomography sensor of the present invention;

[0030] Figure 2 It is a front view of the overall structure of a built-in high-voltage and low-temperature capacitance tomography sensor of the present invention;

[0031] Figure 3 It is an isometric view of a metal pipe of a built-in high-pressure and low-temperature electrical capacitance tomography sensor of the present invention;

[0032] Figure 4 It is a front view of a metal pipe of a built-in high-pressure and low-temperature capacitance tomography sensor of the present invention;

[0033] Figure 5 It is an isometric view of a built-in high-pressure and low-temperature capacitance tomography sensor of the present invention after removing the metal pipe;

[0034] Figure 6 It is an isometric view of an installation tool, a built-in sensing pole piece, and an axial shielding ring of a built-in high-voltage and low-temperature capacitance tomography sensor of the present invention;

[0035] Figure 7 It is a cross-sectional view of an installation tool, a built-in sensing electrode piece, and an axial shielding ring of a built-in high-voltage and low-temperature capacitance tomography sensor of the present invention;

[0036] Figure 8 It is a cross-sectional view of an installation tool for a built-in high-voltage and low-temperature capacitance tomography sensor of the present invention.

[0037] Fig. 9 The invention relates to a built-in sensing pole piece and an axial shielding ring of a built-in high-voltage and low-temperature capacitance tomography sensor.

[0038] Fig.10 Imaging results for pipes with different wall thicknesses. DETAILED DESCRIPTION

[0039] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0040] The present invention will be further described below in conjunction with the accompanying drawings.

[0041] like Figure 1-8 As shown, the built-in high-voltage and low-temperature capacitance tomography sensor of the present invention comprises a metal pipe 1, a signal wire 2, a built-in sensing electrode 4, an axial shielding ring 5 and a fixing fixture 3; a standard flange 11 is provided at one end of the metal pipe 1, and a drilled flange 12 is provided at the other end; the drilled flange is obtained by evenly arranging a plurality of radial holes 121 along the circumferential direction on the outer edge of the standard flange; the radial holes penetrate the drilled flange and the metal pipe 1;

[0042] The fixing tool 3 is detachably fixed inside the metal pipe 1, and the fixing tool 3 is cylindrical, and its outer surface is provided with a mounting groove for fixing the signal wire 2; there are two axial shielding rings 5, which are respectively arranged at both ends of the inner surface of the fixing tool 3 to shield the axial magnetic field outside the measurement domain; there are multiple built-in sensing pole pieces 4, which are evenly arranged on the inner surface of the fixing tool 3 along the circumferential direction, and the built-in sensing pole piece 4 is arranged between the two axial shielding rings 5; one end of the mounting groove is connected to the radial hole 121, and the other end is connected to the connection position of the built-in sensing pole piece 4 through an opening, and the opening is used for the signal wire 2 to pass through and connect to the built-in sensing pole piece 4;

[0043] The signal wire 2 is a shielded wire; one end of the signal wire 2 is connected to the connection position of the built-in sensing electrode 4, and the other end is led out to the outside of the sensor along the opening, the mounting groove and the radial hole 121.

[0044] like Figure 2 As shown, in a specific embodiment of the present invention, an 8-electrode capacitance tomography scheme is adopted, the metal pipe 1 is a standard stainless steel straight pipe with a standard DN65GB2.5MPa, the standard flange 12 is a standard stainless steel flange with a standard DN65 GB2.5MPa, and the drilling flange is processed from the standard stainless steel flange with a standard DN65 GB2.5MPa. Specifically, radial holes penetrating the flange are arranged circumferentially on the outer edge of the standard stainless steel flange; the radial holes 121 have a diameter of 5mm, and the radial holes are arranged between the mounting holes of the drilling flange 12; the radial holes penetrate the inner surface of the metal pipe 1 and the outer surface of the drilling flange 12, and the number of the radial holes is consistent with the number of signal wires 2, the number of mounting grooves, and the number of built-in sensor electrodes 4. The working medium in the pipeline can be liquid nitrogen.

[0045] like Figure 3 As shown, in a specific embodiment of the present invention, an RG316 coaxial cable is used as the signal conductor 2, and the conductor is welded on the welding position of the built-in sensor electrode. The thickness of the built-in sensor electrode 4 and the axial shielding ring 5 are both 1mm, and the depth of all grooves on the inner side of the fixed tooling 3 is 1mm. The built-in sensor electrode 4 and the axial shielding ring 5 are set on the inner surface of the fixed tooling 3 by low-temperature glue, and the axial gap between the built-in sensor electrode 4 and the axial shielding ring 5 is the same as the circumferential gap between each built-in sensor electrode 4. After passing through the fixed tooling 3, the signal conductor 2 is fixed by the installation groove on the outside of the fixed tooling 3, and the size of the installation groove is consistent with the width of the RG316 conductor. The two axial shielding rings 5 ​​are connected by a wire, and the wire is led out through the shielding layer of any signal wire and grounded when the sensor is working. Since each signal wire will be connected to the measuring instrument, the shielding layer of each wire can also be connected together through the instrument, so the shielding layer of each wire is equivalent. After the connection is completed, the instrument is grounded, and then electrically, the shielding layer of the signal wire, the axial shielding ring, and the metal pipe are all grounded. In this embodiment, the material of the built-in sensor electrode 4 and the axial shielding ring is copper, and brass, aluminum, stainless steel and other materials can also be selected.

[0046] like Figure 1 As shown, in a specific embodiment of the present invention, epoxy resin is used as a sealing material to fill the gap between the mounting groove and the radial hole 121 and achieve sealing under high pressure.

[0047] like Figure 8 As shown, in a specific embodiment of the present invention, the fixing fixture 3 is made of polytetrafluoroethylene raw material column to ensure that its structure is intact and does not produce cracks at low temperature. The axial length of the fixing fixture 3 is not shorter than the axial length of the metal pipe 1. The fixing fixture 3 and the metal pipe 1 are interference fit to ensure that the fixing fixture 3 will not shrink and separate from the metal pipe 1 at low temperature.

[0048] In particular, for standard electrical capacitance tomography applications, the circumferential coverage of the sensing electrode is 0.75-0.85, and the circumferential width is Where a is the circumferential coverage of the pole piece, n is the number of pole pieces, and d is the inner diameter of the fixture 4. If the thickness of the sensing pole piece is too small, the structural strength of the pole piece will be reduced, causing it to wrinkle and deform at low temperatures, destroying the structure of the parallel plate capacitor composed of multiple pole pieces, thereby causing the sensor to fail. If the thickness is too large, the edge effect at the end of the pole piece will increase, causing the electric field between the two pole pieces to deviate from the uniform electric field, reducing the measurement accuracy. The preferred range of the thickness of the sensing pole piece obtained by numerical simulation and experiment is 0.3mm-1mm.

[0049] When installing and using the sensor of this embodiment, first install the built-in sensor electrode and the axial shielding ring in the installation groove reserved on the inner surface of the fixed tool 3, and use low-temperature glue to glue them. After installation, ensure that the built-in sensor electrode and the axial shielding ring are flush with the inner surface of the fixed tool; connect one end of the signal wire 2 to the connection position of the built-in sensor electrode; arrange the other end of the signal wire 2 along the installation groove on the outer surface of the fixed tool 3, and use sealant to seal the installation groove and the connection position of the built-in sensor electrode; install the installation tool 3 inside the metal pipe 1; pass the signal wire through the radial hole 121 from the inside of the metal pipe 1; use low-temperature glue to completely seal the radial hole 121; connect the standard flange 11 and the drilled flange 12 to the flange of the section to be detected respectively, and connect the signal wire 2 to the capacitance tomography system.

[0050] In order to verify the influence of tube wall thickness on imaging accuracy, the present invention conducted a numerical simulation experiment. The results are as follows: Fig.10 As shown. The blue in the figure is the gas phase and the red is the liquid phase. The leftmost is the preset flow type in the numerical simulation experiment, and the four pictures on the right are the imaging results calculated by different algorithms under different cases. The inner diameter of the pipe in both examples is 30mm. The outer diameters of the pipes corresponding to the imaging results of the upper and lower cases are 50mm and 31mm respectively. The imaging results of the thin pipe wall (outer diameter 31mm) are visible, and the phase interface is clear regardless of the LBP algorithm or the Landweber algorithm. The difference between different algorithms lies in the area size of the surrounding artifacts and the clarity of the phase interface. The imaging results of the thick pipe wall (outer diameter 50mm) are basically invisible. In the results of the two algorithms, the phase interface is severely distorted, and the phase distribution is also basically wrong in the stereotyped angle analysis.

[0051] From the above experiments, we can see that the influence of thick pipe wall on the capacitance tomography system cannot be ignored. In the external pole piece solution of thick pipe wall, its lower measurement accuracy is determined in theory, and its upper limit of imaging accuracy has been determined. Therefore, the use of internal pole piece solution in high voltage scenarios is a more effective solution.

[0052] However, the general built-in pole piece solution needs to solve new difficulties, including:

[0053] 1) The built-in capacitance tomography sensor electrode is in direct contact with the fluid to be measured, so the installation and fixing forms of the electrode need to be designed. At the same time, the structural strength of the electrode needs to be able to resist the shrinkage and distortion of the material under low temperature conditions.

[0054] 2) Under the premise of contact measurement, in order to avoid its influence on the fluid to be measured, it is necessary to ensure that its measurement form is non-invasive, that is, the flow path of the measuring section is consistent with the flow path of the incoming flow, so that no expansion or compression section is introduced in the measuring section, and the interference with the original flow field can be minimized.

[0055] According to the above explanation of the present invention, the present invention adopts a copper plate of moderate thickness as the measuring electrode, and ensures that its structural strength and no wrinkles at low temperature will not affect the measurement accuracy due to excessive thickness. The present invention designs an installation tool, the inner surface of the tool has a groove for installing the measuring electrode, and the outer surface has a groove for installing the wire, and the inner diameter of the tool is guaranteed to be consistent with the inner diameter of the incoming flow pipe. The tool is an integrated solution, and after completing the wire welding, electrode installation and other operations on the outside of the metal pipe, the tool can be pushed into the metal pipe to complete the sensor installation. In order to ensure the strength of the external metal pipe under high pressure, the present invention adopts a flange drilling solution to lead out the wire, and the high-pressure sealing of the hole adopts a low-temperature glue sealing solution, which ensures its strength and sealing while reducing structural components.

[0056] The specific implementation methods described above further illustrate the structure, technical solutions and operation methods of the device of the present invention in actual use. It should be understood that the above is only a specific implementation example of the present invention and is not intended to limit the present invention. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention, such as: the number and arrangement of flexible measuring electrode arrays, insulating measuring pipe materials, etc.

[0057] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A built-in high-voltage and low-temperature capacitance tomography sensor, characterized in that: It comprises a metal pipe (1), a signal wire (2), a built-in sensor electrode (4), an axial shielding ring (5) and a fixing tool (3); One end of the metal pipe (1) is provided with a standard flange (11), and the other end is provided with a drilled flange (12); the drilled flange is obtained by evenly arranging a plurality of radial holes (121) along the circumferential direction on the outer edge of the standard flange; the radial holes penetrate the drilled flange and the metal pipe (1); The fixing fixture (3) is detachably fixed inside the metal pipe (1); the fixing fixture (3) is cylindrical, and its outer surface is provided with a mounting groove for fixing the signal wire (2); there are two axial shielding rings (5), which are respectively arranged at two ends of the inner surface of the fixing fixture (3) for shielding the axial magnetic field outside the measurement domain; there are multiple built-in sensing pole pieces (4), which are evenly arranged on the inner surface of the fixing fixture (3) along the circumferential direction, and the built-in sensing pole piece (4) is arranged between the two axial shielding rings (5); one end of the mounting groove is connected to the radial hole (121), and the other end is connected to the connection position of the built-in sensing pole piece (4) through an opening, and the opening is used for the signal wire (2) to pass through and connect to the built-in sensing pole piece (4); The signal wire (2) is a shielded wire; one end of the signal wire (2) is connected to the connection position of the built-in sensor electrode (4), and the other end is led out to the outside of the sensor along the opening, the mounting groove and the radial hole (121).

2. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The metal pipe (1) is a standard metal straight pipe; the axial length of the fixing fixture (3) is not shorter than the axial length of the metal pipe (1).

3. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 2, characterized in that: The radial holes are arranged between two mounting holes of the drilling flange (12); the radial holes penetrate the inner surface of the metal pipe (1) and the outer surface of the drilling flange (12), and the number of the radial holes is consistent with the number of signal wires (2), the number of mounting grooves and the number of built-in sensor electrodes (4).

4. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The fixing fixture (3) and the metal pipe (1) are in interference fit, so as to ensure that the fixing fixture (3) will not shrink and separate from the metal pipe (1) at low temperatures.

5. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The built-in sensing pole piece (4) and the axial shielding ring (5) are arranged on the inner surface of the fixing fixture (3) by means of low-temperature glue, and the axial gap between the built-in sensing pole piece (4) and the axial shielding ring (5) is the same as the circumferential gap between each built-in sensing pole piece (4).

6. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The built-in sensing electrode (4) is in direct contact with the low-temperature fluid to be measured. The thickness of the built-in sensing electrode (4) is consistent with that of the axial shielding ring (5), and the thickness is 0.3 mm to 1 mm. The built-in sensing electrode (4) and the axial shielding ring (5) are installed in a mounting groove preset on the inner surface of the fixed tooling (3), and the depth of the inner surface mounting groove is consistent with the thickness of the built-in sensing electrode (4) and the axial shielding ring (5).

7. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The two axial shielding rings (5) are connected via a wire, the wire is led out through the shielding layer of any signal wire, and the two axial shielding rings are grounded when the sensor is working.

8. The built-in high-voltage and low-temperature capacitance tomography sensor according to claim 1, characterized in that: The openings, mounting grooves and radial holes (121) are filled and sealed with low-temperature glue after the signal wires (2) are arranged.

9. A method for installing a built-in high-voltage and low-temperature capacitance tomography sensor as claimed in claim 1, characterized in that: The following steps are involved: 1) Installing the built-in sensor electrode piece and the axial shielding ring in the installation groove reserved on the inner surface of the fixed tooling (3), and bonding them with low-temperature glue, and ensuring that the built-in sensor electrode piece and the axial shielding ring are flush with the inner surface of the fixed tooling after installation; connecting one end of the signal wire (2) to the connection position of the built-in sensor electrode piece; 2) placing the other end of the signal wire (2) along the mounting groove on the outer surface of the fixing tool (3), and using a sealant to seal the connection between the mounting groove and the mounted sensor electrode; 3) Installing the installation tool (3) inside the metal pipe (1); 4) Passing the signal wire out from the metal pipe (1) along the radial hole (121); 6) Using low temperature glue to completely seal the radial hole (121); 7) The standard flange (11) and the drilled flange (12) are respectively connected to the flange of the section to be inspected, and the signal wire (2) is connected to the capacitance tomography system.

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