A detachable variable diameter electrical capacitance tomography sensor and imaging system

Abstract

The application discloses a detachable variable-diameter electrical capacitance tomography sensor and an imaging system, which comprises array distribution electrodes and an insulating elastic belt; the measuring electrodes of the array distribution electrodes are formed by parallel and partially superimposed combination of sub-electrodes A and B; the outer sides of the sub-electrodes A and B are fixed to the surface of the insulating elastic belt; when the insulating elastic belt is contracted or extended, the lower surface of the sub-electrode A and the upper surface of the sub-electrode B of each electrode can be relatively moved, and meanwhile, the lower surface of the sub-electrode A and the upper surface of the sub-electrode B keep contact and conduction, and the electrode coverage remains unchanged; the two ends of the elastic belt are connected through a buckle structure; the two ends of the elastic belt are provided with positioning holes; when the elastic belt is closed and connected, the first measuring electrode and the last measuring electrode of the array distribution electrodes realize the same distance through the positioning holes, and the distance of the remaining adjacent measuring electrodes is the same. The detachable variable-diameter electrical capacitance tomography sensor realizes the purpose of measuring different diameter measured objects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensor design, and particularly relates to a detachable variable-diameter electrical capacitance tomography sensor and an imaging system. BACKGROUND

[0002] Electrical capacitance tomography (ECT) is a process tomography technology based on the principle of capacitance sensing. It acquires the projection data (capacitance value) of the non-conductive measured object field at different observation angles through a specially designed array of capacitive sensors arranged around the imaging area profile (such as a pipeline or a closed container), and inverts the medium (dielectric constant) distribution in the measured object field according to the sensor sensitivity field characteristics and the appropriate reconstruction algorithm of the inversion algorithm to give the medium distribution result in the form of an image, which can realize non-contact imaging of the dielectric constant inside any shape structure. It is an ideal non-contact measurement technology. Electrical capacitance tomography has the advantages of non-invasion, fast response, low cost, safety and no radiation. It is most widely used in two-phase flow and multi-phase flow detection, and is also applied in skull model temperature distribution imaging, warehouse grain moisture monitoring, frozen soil layer measurement, sliding bearing lubricating oil film measurement and other aspects, involving petroleum, chemical industry, electric power, metallurgy, building materials, medicine and other fields of national economy and industry. Therefore, the technology has broad application prospects and development potential.

[0003] The general two-dimensional ECT arranges n capacitor electrode arrays in the circumferential direction of the circular insulating rigid pipeline or the outer circumferential direction of the rectangular section, forms a capacitor between every two electrodes, has m = n * (n-1) / 2 capacitors, and the size of the m capacitors is closely related to the distribution of the dielectric constant in the pipeline. The in-pipeline sensitive field S of the relationship between the dielectric constant and the array capacitor is obtained by modeling the sensing characteristics in the pipeline, and the dielectric constant distribution in the pipeline is reconstructed according to the sensitive field and the m array capacitors and a certain inversion algorithm. In the capacitive tomography sensor and system disclosed in the prior art with publication number CN111175354B, the array electrodes are insulatively enclosed in the outer circumferential wall of the pipeline for measurement by the support frame; the capacitive tomography sensor disclosed in publication number CN110455877B and the like is a barrel-shaped sensor, which sequentially includes array distribution electrodes, electrode insulating sleeves, flange outer pipes, insulating pipes and signal transmission lines from the inside to the outside; and the like are all arranged in the circumferential direction of the circular insulating rigid pipeline. The advantages are that: in order to ensure the determination of the sensitive field, the sensor pipeline is usually a rigid structure, and the electrodes are arranged outside the insulating pipeline, and the electrode size, the inner and outer diameters of the insulating pipeline, and the pipeline dielectric constant are all fixed values. The above structures all have problems: (1) the fixed rigid structure can only measure the sensor of a certain size profile, and cannot be used for imaging in the case of uneven profile size. (2) The sensor cannot be disassembled along the circumferential direction. The prior art with publication number CN209707433U discloses a non-regular geometric shape super element capacitive tomography device, which realizes imaging of the irregular pipeline placed on the surface of the base through the shielding cover and the radial shielding electrode plate, and still has the above problems.

[0004] The purpose of the present application is to provide a sensor structure with an arbitrarily adjustable diameter, and the sensor can be disconnected at the electrode gap to facilitate disassembly, solving the problems of the general ECT that cannot measure the diameter and cannot be disassembled. SUMMARY

[0005] 1. Technical problems to be solved:

[0006] In view of the above technical problems, the present application provides a detachable variable-diameter capacitive tomography sensor and imaging system, which can measure different diameter imaging objects with one set of ECT instrument and can be disassembled circumferentially.

[0007] 2. Technical solutions:

[0008] A detachable variable-diameter capacitive tomography sensor, characterized in that it comprises array distribution electrodes and an insulating elastic belt.

[0009] The array distribution electrodes comprise a plurality of measurement electrodes uniformly arranged in the extension direction of the insulating elastic belt.

[0010] The measuring electrodes are formed by the parallel and partially superimposed combination of sub-electrode A and sub-electrode B; the outer side edges of the sub-electrode A and sub-electrode B are fixed to the surface of the insulating elastic band by a fixing structure, and the lower surface of the sub-electrode A is movably superimposed on the upper surface of the sub-electrode B, so that when the insulating elastic band is contracted or extended, the relative movement between the lower surface of the sub-electrode A and the upper surface of the sub-electrode B of each measuring electrode is caused while the lower surface of the sub-electrode A and the upper surface of the sub-electrode B remain in contact and conduction; during measurement, the array distribution electrodes are located on the inner side in contact with the surface of the pipeline to be imaged, and the insulating elastic band is located on the outer side.

[0011] The two ends of the insulating elastic band are connected by a buckle structure; the two ends of the elastic band are provided with positioning holes, and when the insulating elastic band is connected, the first measuring electrode and the last measuring electrode of the array distribution electrodes realize the same distance between the two and the distance between the adjacent measuring electrodes.

[0012] Further, the outer side edges of the sub-electrode A and sub-electrode B are fixed to the surface of the insulating elastic band by screws.

[0013] Further, the array distribution electrodes are at least one row of electrodes; each row of electrodes is at least 4 columns; and the length of the insulating elastic band is adapted to the surface circumference of the pipeline to be imaged.

[0014] Further, the sub-electrode A and sub-electrode B are both sheet-shaped rectangles; the total width of each measuring electrode is W, and the widths of the sub-electrodes are W1 and W2 respectively; and when the insulating elastic band is in a normal working state, i.e. the insulating elastic band is elastically deformed, W is less than W1+W2.

[0015] Further, the sub-electrode A and sub-electrode B are both copper electrodes; and are connected to the signal acquisition system through wires arranged on the measuring electrodes.

[0016] Further, a shielding cover is arranged on the outer periphery of the insulating elastic band.

[0017] An imaging system of a detachable variable-diameter electrical capacitance tomography sensor, the array distribution electrodes are connected to the electrical capacitance tomography signal acquisition system through signal lines, the electrical capacitance tomography signal acquisition system measures the capacitance between the sensor electrodes and digitizes, and then transmits to the imaging computer through communication lines to complete image reconstruction.

[0018] 3. Beneficial effects:

[0019] (1) The imaging system of the detachable variable-diameter electrical capacitance tomography sensor adopted in the scheme can select an insulating elastic band with a corresponding length according to the circumference of a pipeline to be imaged, and the electrode surface of the insulating elastic band directly contacts the surface of the pipeline, the insulating elastic band is stretched to cause elastic deformation of the insulating elastic band, and meanwhile, relative displacement between the sub-electrodes of each measuring electrode is caused, and through the sensor connected with the electrode to the imaging computer, the measuring electrode can be closely attached to the measured object, and imaging errors caused by the gap between the measuring electrode and the measured electrode are avoided.

[0020] (2) The detachable variable-diameter electrical capacitance tomography sensor adopted in the scheme fixes the electrical capacitance tomography electrode on the insulating elastic band, and wraps the measured object with the insulating elastic band, and the size of the sensor circumference can be automatically adjusted according to the diameter of the measured object, so that the imaging of measured objects with different diameters is realized.

[0021] (3) The detachable variable-diameter electrical capacitance tomography sensor adopted in the scheme is composed of two sub-electrodes for each measuring electrode, and the single-sided edge of the sub-electrode is fixed on the insulating elastic band. The overlap ratio of the sub-electrodes in the measuring electrode is adjusted through the stretching ratio of the insulating elastic band to realize the automatic adjustment of the electrode width, so that the electrode coverage rate does not change due to the change of the diameter of the measured object.

[0022] (4) The detachable variable-diameter electrical capacitance tomography sensor adopted in the scheme has no inner tube, has high imaging accuracy, is not affected by the dielectric constant of the inner tube and the thickness of the pipeline, and finally realizes the imaging under different sensor diameters through one-time calibration. The traditional ECT sensor needs to be calibrated separately for each size of the sensor.

[0023] (5) The detachable variable-diameter electrical capacitance tomography sensor adopted in the scheme has a variable diameter, and the ratio of the maximum inner diameter to the minimum inner diameter is close to 2, and stepless adjustment and the minimum diameter ratio can be realized in the range.

[0024] In summary, the detachable variable-diameter electrical capacitance tomography sensor fixes the electrical capacitance tomography electrode on the elastic band, and achieves the purpose of measuring measured objects with different diameters. For pipelines that do not need to be measured frequently and cannot be cut off to install the ECT sensor, the detachable type of the method is particularly suitable, and the traditional ECT sensor cannot be realized. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the principle of the detachable variable-diameter electrical capacitance tomography sensor in the specific embodiment.

[0026] Figure 2 It is a schematic diagram of two sub-electrodes of the measuring electrode in the specific embodiment.

[0027] Figure 3 Figure 1 is a schematic diagram of the displacement between the sub-electrodes of the measuring electrode in the embodiment of the application when the measuring electrode is used in imaging a pipe with different diameters;

[0028] Figure 4 Figure 2 is a cross-sectional view of the electrode structure in the embodiment of the application when the sensor is used in imaging a pipe with different diameters.

[0029] Reference signs: measuring electrode 1, insulating elastic band 2, sub-electrode A 11, sub-electrode B 12, screw 3. DETAILED DESCRIPTION

[0030] The application will be described in detail below with reference to the accompanying drawings.

[0031] As shown in the accompanying drawings Figure 1 to the accompanying drawings Figure 4 A detachable variable-diameter electrical capacitance tomography sensor, characterized in that it comprises arrayed electrodes and an insulating elastic band 2.

[0032] The arrayed electrodes comprise a plurality of measuring electrodes 1 arranged uniformly along the extension direction of the insulating elastic band.

[0033] Each of the measuring electrodes is formed by juxtaposing and partially superimposing a sub-electrode A and a sub-electrode B; the outer sides of the sub-electrode A and the sub-electrode B are fixed to the surface of the insulating elastic band by a fixing structure, and the lower surface of the sub-electrode A is movably superimposed on the upper surface of the sub-electrode B, so that when the insulating elastic band is contracted or extended, the relative movement between the lower surface of the sub-electrode A and the upper surface of the sub-electrode B of each measuring electrode is enabled while the lower surface of the sub-electrode A and the upper surface of the sub-electrode B remain in contact and conductive; during measurement, the arrayed electrodes are located on the inner side in contact with the surface of the pipe to be imaged, and the insulating elastic band is located on the outer side; in the figure, the sub-electrode A is indicated by reference sign 11, and the sub-electrode B is indicated by reference sign 12.

[0034] The two ends of the insulating elastic band are connected by a buckle structure; the two ends of the elastic band are provided with positioning holes, and when the insulating elastic band is connected, the distance between the first measuring electrode and the last measuring electrode of the arrayed electrodes is the same as the distance between the adjacent measuring electrodes.

[0035] Further, the outer sides of the sub-electrode A and the sub-electrode B are fixed to the surface of the insulating elastic band by a screw 3.

[0036] Further, the arrayed electrodes are at least one row of electrodes; each row of electrodes is at least 4 columns; and the length of the insulating elastic band is adapted to the surface circumference of the pipe to be imaged.

[0037] Further, the sub-electrode A and the sub-electrode B are both sheet-shaped rectangles; the total width of each measuring electrode is W, and the widths of the sub-electrodes are W1 and W2 respectively; when the insulating elastic belt is in a normal working state, i.e. the insulating elastic belt is elastically deformed, W is less than W1+W2.

[0038] Further, the sub-electrode A and the sub-electrode B are both copper electrodes; the measuring electrodes are connected to a signal acquisition system through wires arranged on the measuring electrodes.

[0039] Further, a shielding cover is arranged on the periphery of the insulating elastic belt.

[0040] An imaging system of a detachable variable-diameter electrical capacitance tomography sensor, the array distribution electrodes are connected to an electrical capacitance tomography signal acquisition system through signal lines, the electrical capacitance tomography signal acquisition system measures the capacitance between the sensor electrodes and digitizes, and then transmits to an imaging computer through communication lines to complete image reconstruction. Specific embodiments:

[0042] As shown in Figures 1-4 , the embodiments all take an 8-electrode electrical capacitance tomography system as an example E1-E8 to represent a single measuring electrode; two working conditions are used in the embodiments for comparison: (1) the circumference of the pipe to be imaged is relatively small, and the length of the selected insulating elastic belt is slightly longer than the length when the insulating elastic belt is not stressed, at this time the diameter of the pipe is represented as 100mm in the figure; (2) the circumference of the pipe to be imaged is longer, and the diameter of the pipe is marked as 160mm in the figure.

[0043] As shown in the attached Figure 1 , each single measuring electrode includes a sub-electrode A and a sub-electrode B, wherein the length of the insulating elastic belt is represented as C, and the two ends of the insulating elastic belt are connected in a closed loop through a buckle structure. The surface of the insulating elastic belt is uniformly provided with 8 measuring electrodes in one cross section (one row), and each measuring electrode is a copper electrode with a thickness of 0.1mm. When the insulating elastic belt is elastically deformed under stress, the electrode width W of each measuring electrode, the total length of the elastic belt, and the distance between adjacent electrodes will increase proportionally.

[0044] As shown in the attached Figure 2 , 3 , each measuring electrode is formed by superimposing and combining a sub-electrode A and a sub-electrode B, the left edge of the sub-electrode A and the right edge of the sub-electrode B are respectively fixed to the insulating elastic belt by 3 fixed screws, the width of the insulating elastic belt is slightly wider than the electrode axial length L, and 8 electrodes are uniformly distributed on the insulating elastic belt. The sub-electrodes in the embodiments are rectangular with the same shape, which ensures that the two sub-electrodes can overlap each other when the insulating elastic belt is stretched, thereby realizing connection.

[0045] As shown in the attached Figure 1 , 4As shown, the greater the force F on the insulating elastic band in this scheme, the longer the total length C of the elastic band. According to the elastic deformation formula, as long as the insulating elastic band is within its elastic deformation or elongation range, the ratio between the electrode width W and the gap P between the electrodes on the elastic band will always remain unchanged. Figure 1 The top image shows the external view and cross-sectional view when the insulating elastic force is small, while the bottom image shows the external view and cross-sectional view when the insulating elastic force is large. When imaging cylindrical imaging regions of different diameters, Figure 1 The elastic band wraps around the cylinder being measured, with the measuring electrodes positioned inside and the elastic band outside. The ends of the elastic band are secured to the measuring area via clips, allowing for detachment. Positioning holes ensure the gap between electrodes 1 and 8 is the same size as the gaps between other electrodes. The electrodes act directly on the measured medium without any isolation channels. The elastic band length C, electrode width W, and electrode gap P are adaptively adjusted according to the diameter of the imaging area, while the electrode axial length L remains constant, unaffected by the diameter of the measured object. The electrode width W for different imaging area diameters is obtained by adjusting the overlap ratio of electrodes A and B.

[0046] like Figure 3 As shown, if the diameter of the imaging circle increases by 1.6 times, the distance between the screws fixing sub-electrode A and sub-electrode B, i.e., the electrode width W, also increases by 1.6 times, as shown in the attached diagram. Figure 4 As shown, since the electrode width W changes proportionally with the circumference length C, the electrode angle θ remains constant before and after the sensor diameter changes. That is, the position and size of each electrode also change proportionally; the area of ​​the two electrodes of a capacitor increases, and their distance increases accordingly, while the axial length L of the electrode remains constant. According to the basic relationship Capacitance = Dielectric Constant × Area / Distance, the capacitance remains unchanged before and after the sensor diameter changes. Therefore, after changing the sensor diameter, there is no need to recalibrate the sensor with an empty and full tube. This method's variable-diameter capacitance tomography sensor, with a constant measurement medium, only requires one empty and full tube calibration to image under different sensor tube diameters.

[0047] To prevent interference from external electromagnetic signals, a shielding cover is placed around the elastic band. Sub-electrode A and sub-electrode B are kept fully conductive. The signals from each electrode are led out through fixing screws, and the fixing screws are connected to the capacitance acquisition instrument through shielded wires.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims of this application.

Claims

1. A detachable variable diameter electrical capacitance tomography sensor, characterized in that: The array distribution electrode comprises a plurality of measuring electrodes arranged uniformly along the extension direction of the insulating elastic belt. The array distribution electrode comprises a plurality of measuring electrodes arranged uniformly along the extension direction of the insulating elastic belt. The measuring electrode is formed by the parallel and partially superimposed combination of a sub-electrode A and a sub-electrode B. The outer side edges of the sub-electrode A and the sub-electrode B are fixed to the surface of the insulating elastic belt by a fixing structure. The lower surface of the sub-electrode A is movable and superimposed on the upper surface of the sub-electrode B. When the insulating elastic belt is contracted or extended, the relative movement between the lower surface of the sub-electrode A and the upper surface of the sub-electrode B is driven while the lower surface of the sub-electrode A and the upper surface of the sub-electrode B remain in contact and conduction. During measurement, the array distribution electrode is located on the inner side in contact with the surface of the pipeline to be imaged, and the insulating elastic belt is located on the outer side.

2. The detachable variable diameter electrical capacitance tomography sensor according to claim 1, wherein: The two ends of the insulating elastic belt are connected by a buckle structure.

3. The detachable variable diameter electrical capacitance tomography sensor according to claim 1, wherein: The two ends of the elastic belt are provided with positioning holes.

4. An imaging system of a detachable variable diameter electrical capacitance tomography sensor, image acquisition is performed by using the detachable variable diameter electrical capacitance tomography sensor according to any one of claims 1-3; characterized in that: When the insulating elastic belt is connected, the distance between the first measuring electrode and the last measuring electrode of the array distribution electrode is the same as the distance between the remaining adjacent measuring electrodes. The outer side edges of the sub-electrode A and the sub-electrode B are fixed to the surface of the insulating elastic belt by a screw. The sub-electrode A and the sub-electrode B are both sheet-shaped rectangles. The total width of each measuring electrode is W, and the widths of the sub-electrodes are W1 and W2, respectively. When the insulating elastic belt is in a normal working state, i.e., the insulating elastic belt is elastically deformed, W is less than W1+W2. The array distribution electrode is at least one row of electrodes. Each row of electrodes is at least 4 columns. The length of the insulating elastic belt is adapted to the surface circumference of the pipeline to be detected and imaged. The sub-electrode A and the sub-electrode B are both copper electrodes. The sub-electrode A and the sub-electrode B are connected to the signal acquisition system through wires arranged on the measuring electrode. A shielding cover is arranged on the outer periphery of the insulating elastic belt. The array distribution electrode is connected to the electrical capacitance tomography signal acquisition system through a signal line. The electrical capacitance tomography signal acquisition system measures the capacitance between the sensor electrodes and digitizes them. The data are transmitted to an imaging computer through a communication line to complete image reconstruction.

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