An ECT data acquisition device and a data processing method

Abstract

The present invention belongs to the field of capacitance tomography data acquisition and processing. The relative permittivity of a mixture containing a conductive phase changes at two different excitation frequencies, and the permittivity distribution can further reflect the state distribution of each phase in the sensitive area. The number of channel switches is closely related to the image reconstruction rate. The present invention provides an ECT data acquisition device and processing method, which selects the lower limit frequency and the upper limit frequency of the dispersion frequency range for excitation, and performs secondary normalization processing on the capacitance data collected at two different excitation frequencies to improve the data acquisition rate and the image reconstruction rate. The present invention combines the MWS effect of a two-phase mixture containing a conductive phase with ECT technology, and performs secondary normalization on the capacitance data collected at two different excitation frequencies, meeting the requirements of image reconstruction accuracy and timeliness for a two-phase mixture containing a conductive phase in practical applications, and having important practical value and application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of capacitance tomography data acquisition and processing, and more specifically, relates to an ECT data acquisition device and a data processing method. Background Art

[0002] For the measurement of two-phase mixtures containing a conductive phase, a method of collecting resistance values using internal electrodes in direct contact with the sensing medium is commonly used. The intrusion of the internal electrodes into the area to be measured will affect the normal flow of the mixture. Since the traditional ECT measurement of two-phase mixtures containing a conductive phase fails to achieve the expected results, some scholars have proposed a multi-modal ECT technology based on admittance data, which increases the difficulty of system design. In addition, some scholars have proposed to analyze two-phase mixtures containing a conductive phase using complex permittivity, and the introduction of complex permittivity will inevitably increase the complexity of the analysis.

[0003] For two-phase mixtures containing a conductive phase, the two-phase mixture will exhibit different dielectric effects at different excitation frequencies. If two different excitation frequencies are appropriately selected, the capacitance values of the two-phase mixture containing a conductive phase at the two different excitation frequencies will change significantly.

[0004] For mixtures containing a conductive phase, whether the conductive phase is a dispersed phase or a continuous phase, due to the conductive characteristics of the conductive phase or the high permittivity characteristics of some conductive phases (such as water), the traditional ECT data acquisition and processing methods cannot obtain the distribution states of the dispersed phase and the continuous phase. According to the Maxwell-Wagner-Sillars (MWS) effect, for two-phase mixtures containing a conductive phase, the mixture will exhibit different dielectric effects at different excitation frequencies. If the lower limit frequency (ω1) and the upper limit frequency (ω2) of the dispersion frequency range are selected for excitation, the dielectric effects of the two-phase mixture containing a conductive phase at the two different excitation frequencies will change, thereby causing a change in the relative permittivity of the mixture.

[0005] For a capacitance tomography sensor with N electrodes, the number of effective inter-electrode capacitance values is N*(N - 1) / 2. For a classic single-frequency excitation and measurement scheme, the number of channel switches is N - 1. The number of channel switches is closely related to the rate of image reconstruction. There is an urgent need for a method that can reduce the number of channel switches, thereby improving the rate of image reconstruction and meeting the real-time and rapid requirements in the industrial two-phase flow monitoring process. Summary of the Invention

[0006] The present invention provides an ECT data acquisition and processing method for two-phase mixtures containing a conductive phase to solve the above-mentioned problems.

[0007] The technical solution adopted by the present invention to solve its technical problems is:

[0008] An ECT data acquisition device includes a pipeline, a shielding cover, and a number of electrodes. A number of arc-shaped grooves for placing electrodes are provided between the inner wall and the outer wall of the pipeline. The arc-shaped grooves are evenly distributed in a circumferential array, and adjacent arc-shaped grooves are not connected to each other; a shielding cover is provided between the arc-shaped grooves and the outer wall; the area surrounded by the inner wall of the pipeline is set as an imaging area.

[0009] Further, the number N of the arc-shaped grooves is calculated according to the following formula: N = 2 x , where x≥3 and x represents the number of channel switching times.

[0010] Further, the distance between the inner wall and the arc-shaped groove is 1 mm to 3 mm.

[0011] Further, the number of electrodes is the same as that of the arc-shaped grooves.

[0012] Further, it further includes a microcontroller system for controlling the switch array, and the microcontroller system is connected to the electrodes through the switch array.

[0013] An ECT data acquisition and processing method, based on the above ECT data acquisition device, for a two-phase mixture containing a conductive phase, selects the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range for excitation, and performs secondary normalization processing on the capacitance data collected at two different excitation frequencies to improve the data acquisition rate and the image reconstruction rate. The specific steps are as follows:

[0014] Step 1: Place electrodes in all the arc-shaped grooves in the pipeline of the ECT data acquisition device. Select any one of the N electrodes as the No. 1 electrode and number it as E1, and sequentially number the remaining N - 1 electrodes as E2, E3, E4... E(N) in the counterclockwise or clockwise direction;

[0015] Step 2: Under the conditions that the excitation frequencies are respectively the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range, the microcontroller system controls the switch array to complete x times of switching, and respectively obtains N*(N - 1) / 2 groups of inter-electrode capacitance values at two different excitation frequencies;

[0016] Step 3: Under three conditions of an empty field filled with a low dielectric constant substance in the imaging area, a full field filled with a high dielectric constant substance in the imaging area, and a mixed field filled with both a high dielectric constant substance and a low dielectric constant substance in the imaging area, perform parallel data acquisitions at two different excitation frequencies respectively. The collected data is recorded as the inter-electrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the empty field condition the inter-electrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the empty field condition the inter-electrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the full field condition The interelectrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the full-field condition The interelectrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the hybrid-field condition The interelectrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the hybrid-field condition For the capacitance data collected at two different excitation frequencies, respectively through Perform parallel normalization operation. Based on obtaining the parallel normalization data corresponding to the frequency, through Perform secondary normalization, where β is the adjustment factor, and C d Is the capacitance value after secondary normalization;

[0017] Step 4: Use the capacitance data after secondary normalization obtained in Step 3 to perform image reconstruction to obtain the phase distribution images of the mixture containing the conductive phase in the imaging area.

[0018] Furthermore, in Step 2, the specific steps for the microcontroller system to control the switch array to complete x times of switching are as follows:

[0019] Step 2.1 The microcontroller system controls the switch array to complete the first switching: E1, E2, E3…E(N / 2) are divided into the first group and connected to the excitation circuit, and E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)…E(N) are divided into the second group and connected to the measurement circuit M; under the conditions that the excitation frequencies are the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range respectively, measure the current values on E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)…E(N), convert them into digital signals through the current-voltage conversion circuit and the analog-to-digital converter, and demodulate the interelectrode capacitance values at different excitation frequencies;

[0020] Step 2.2: The microcontroller system controls the switch array to complete the second switching: Based on the grouping in Step 2.1, the first group is equally divided into the first-1 group and the first-2 group, and E1, E2…E(N / 4) of the first-1 group are connected to the excitation circuit, and E(N / 4 + 1), E(N / 4 + 2),…E(N / 2) of the first-2 group are connected to the measurement circuit M; the second group is equally divided into the second-1 group and the second-2 group, and E(N / 2 + 1), E(N / 2 + 2)…E(3N / 4) of the second-1 group are connected to the excitation circuit, and E(3N / 4 + 1), E(3N / 4 + 2)…E(N) of the second-2 group are connected to the measurement circuit M, and demodulate the interelectrode capacitance values at two different excitation frequencies;

[0021] Step 2.3: The several groups of electrodes divided in the previous step are equally divided again and connected to the measurement circuit M and the excitation circuit respectively, and demodulate the interelectrode capacitance values at two different excitation frequencies;

[0022] Step 2.4: Repeat the operation in Step 2.3 until x channel switches are completed, and obtain N*(N - 1) / 2 sets of interelectrode capacitance values at two different excitation frequencies respectively.

[0023] Applying the ECT data acquisition and processing method based on the MWS effect proposed by the present invention can quickly reconstruct the dielectric constant distribution of a two-phase mixture containing a conductive phase in a sensitive area, and the dielectric constant distribution can further reflect the state distribution of each phase in the sensitive area. The method of the present invention meets the requirements of image reconstruction accuracy and timeliness for two-phase mixtures containing a conductive phase in practical applications. Aiming at the problem that the traditional ECT technology cannot reconstruct the images of each phase of a two-phase mixture containing a conductive phase, the MWS effect of the two-phase mixture containing a conductive phase is integrated with the ECT technology, and the capacitance data collected at two different excitation frequencies are secondarily normalized, effectively solving the aforementioned problem. Different from the existing single-frequency excitation and measurement schemes, the present invention provides an ECT parallel data acquisition and processing method, which effectively reduces the number of channel switches and improves the ECT data acquisition rate and image reconstruction rate. Brief Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the pipeline structure of the ECT data acquisition device of the present invention;

[0025] Figure 2 It is a flowchart of the method implementation of the present invention;

[0026] Figure 3 It is a flowchart of the implementation of the parallel data acquisition method involved in the present invention;

[0027] Figure 4 It is a flowchart of the implementation of the capacitance data processing method involved in the present invention.

[0028] In the figure, 1 - inner wall, 2 - outer wall, 3 - electrode, 4 - arc groove, 5 - shielding cover, 6 - imaging area. Detailed Embodiments

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0030] As Figures 1 to 4As shown in the figure, the present invention discloses an ECT data acquisition device for a two-phase mixture containing a conductive phase. The ECT data acquisition device includes a pipeline, a shielding cover 5, and a plurality of electrodes 3. A plurality of arc-shaped grooves 4 for placing the electrodes 3 are provided between the inner wall 1 and the outer wall 2 of the pipeline. The arc-shaped grooves 4 are evenly distributed in a circumferential array, and adjacent arc-shaped grooves 4 are not connected to each other. The number of electrodes 3 is the same as the number of arc-shaped grooves 4. The distance between the inner wall 1 and the arc-shaped groove 4 is 1 mm - 3 mm. A shielding cover 5 is provided between the arc-shaped groove 4 and the outer wall 2. An imaging area 6 is provided in the area surrounded by the inner wall 1 of the pipeline.

[0031] The number N of the arc-shaped grooves 4 is calculated according to the following formula: N = 2 x , where x ≥ 3, and x represents the number of channel switching times.

[0032] The present invention also discloses an ECT data acquisition and processing method for a two-phase mixture containing a conductive phase. Based on the above-mentioned ECT data acquisition device for a two-phase mixture containing a conductive phase, for the two-phase mixture containing a conductive phase, the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range are selected for excitation, and the capacitance data collected at two different excitation frequencies are subjected to secondary normalization processing to improve the data acquisition rate and the image reconstruction rate. The specific steps are as follows:

[0033] Step 1: Place the electrodes 3 in all the arc-shaped grooves 4 in the pipeline of the ECT data acquisition. Select a certain electrode among the N electrodes as the No. 1 electrode and number it as E1, and sequentially number the remaining N - 1 electrodes as E2, E3, E4... E(N) in the counterclockwise or clockwise direction. After the numbering direction is selected, it cannot be changed.

[0034] Step 2: Under the conditions that the excitation frequencies are respectively the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range, the switch array control system completes x times of switching, and respectively obtains N*(N - 1) / 2 groups of inter-electrode capacitance values at two different excitation frequencies.

[0035] The specific steps for the switch array control system to complete x times of switching are as follows:

[0036] Step 2.1 The microcontroller system controls the switch array to complete the first switching: E1, E2, E3... E(N / 2) are divided into the first group and connected to the excitation circuit, and E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N) are divided into the second group and connected to the measurement circuit M; under the conditions that the excitation frequencies are respectively the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range, measure the current values on E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N), convert them into digital signals through the current-voltage conversion circuit and the analog-to-digital converter, and demodulate the inter-electrode capacitance values at different excitation frequencies through the digital signals.

[0037] Step 2.2: The microcontroller system controls the switch array to complete the second switching: In step 2, the first group is equally divided into the first-1 group and the first-2 group. E1, E2... E(N / 4) of the first-1 group are connected to the excitation circuit, and E(N / 4 + 1), E(N / 4 + 2)... E(N / 2) of the first-2 group are connected to the measurement circuit M; the second group is equally divided into the second-1 group and the second-2 group. E(N / 2 + 1), E(N / 2 + 2)... E(3N / 4) of the second-1 group are connected to the excitation circuit, and E(3N / 4 + 1), E(3N / 4 + 2)... E(N) of the second-2 group are connected to the measurement circuit M, and the interelectrode capacitance values at two different excitation frequencies are demodulated.

[0038] Step 2.3: The several groups of electrodes divided in the previous step are equally divided again and respectively connected to the measurement circuit M and the excitation circuit, and the interelectrode capacitance values at two different excitation frequencies are demodulated.

[0039] Step 2.4: Repeat the operation of step 2.3 until x channel switches are completed, and N*(N - 1) / 2 groups of interelectrode capacitance values at two different excitation frequencies are respectively obtained.

[0040] Step 3: Under three conditions of an empty field filled with a low-dielectric-constant substance in the imaging area, a full field filled with a high-dielectric-constant substance in the imaging area, and a mixed field filled with both a high-dielectric-constant substance and a low-dielectric-constant substance in the imaging area, parallel data acquisitions at two different excitation frequencies are respectively performed. The acquired data are recorded as the interelectrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the empty field condition The interelectrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the empty field condition The interelectrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the full field condition The interelectrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the full field condition The interelectrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the mixed field condition The interelectrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the mixed field condition For the capacitance data collected at two different excitation frequencies, respectively through Perform parallel normalization operations. Based on obtaining the parallel normalization data at the corresponding frequencies, through Perform secondary normalization, where β is an adjustment factor, and C d Is the capacitance value after secondary normalization;

[0041] Step 4: Use the capacitance data after secondary normalization obtained in step 3 for image reconstruction to obtain the phase distribution images of the mixture containing the conductive phase in the imaging area.

[0042] In Figure 1 the illustrated embodiment, a cylindrical pipe is printed by using 3D printing technology. Those skilled in the art can also use other existing technologies to produce or fabricate the pipe. The size of the pipe can be adjusted according to actual requirements. Considering that the symmetric distribution of the array electrodes along the inner wall of the pipe can reduce or even eliminate the measurement error, N arc-shaped grooves are printed at a distance of 2 mm from the inner wall of the pipe in a uniform distribution manner. The length of the arc-shaped grooves is the same as the inner diameter of the pipe, and the arc-shaped grooves are not connected to each other, which are used to fix N electrodes. Circular grooves with the same length as the arc-shaped grooves are printed between the arc-shaped grooves and the outer wall, which are used to place the shielding covers. Embedding the shielding covers and the electrodes between the inner and outer walls of the pipe can effectively prevent the electrodes and the shielding covers from being affected by environmental corrosion and affecting the performance of the sensor, and increase the service life of the electrodes and the shielding covers.

[0043] In this embodiment, taking x = 3, that is, N = 8 as an example for description. So far, an 8-electrode electrical capacitance tomography sensor as Figure 1 shown is built.

[0044] For a mixture containing a conductive phase, the traditional electrical capacitance tomography data acquisition and processing method cannot effectively obtain the phase state distribution images of the two-phase mixture. According to the Maxwell-Wagner (MWS) effect, for a two-phase mixture containing a conductive phase, the lower limit frequency (ω1) and the upper limit frequency (ω2) of the dispersion frequency range are selected for excitation, then the capacitance values of the mixture containing the conductive phase at the two limit frequencies of the dispersion frequency range will have the largest difference.

[0045] Select any one of the N electrodes as the No. 1 electrode and label it as E1. Number the remaining N - 1 electrodes in counterclockwise order as E2, E3, E4... E(N). The microcontroller system controls the switch array to complete the first switch. E1, E2, E3... E(N / 2) are grouped together and connected to the excitation circuit, and E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N) are grouped into another group and connected to the measurement circuit M. Under the conditions that the excitation frequencies are the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range respectively, measure the current values on E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N), convert them into digital signals through the current-voltage conversion circuit and the analog-to-digital converter, and demodulate the inter-electrode capacitance values at different excitation frequencies; on the basis of the first switch, the microcontroller system controls the switch array to complete the second switch, and the two subgroups are equally divided into four subgroups. E1, E2, E3... E(N / 4) are connected to the excitation circuit, E(N / 4 + 1), E(N / 4 + 2), E(N / 4 + 3)... E(N / 2) are connected to the measurement circuit M, E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(3N / 4) are connected to the excitation circuit, and E(3N / 4 + 1), E(3N / 4 + 2), E(3N / 4 + 3)... E(N) are connected to the measurement circuit M, and demodulate the inter-electrode capacitance values at two different excitation frequencies, and repeat the above grouping measurement process. When the switch array completes x channel switches, obtain N*(N - 1) / 2 groups of inter-electrode capacitance values at two different excitation frequencies respectively.

[0046] Select a certain electrode as the No. 1 electrode and label it as E1 from 8 electrodes. Number the remaining 7 electrodes in counterclockwise order as E2, E3, E4... E8. For the classical single-frequency excitation and measurement scheme, the number of channel switches is 7. For an 8-electrode capacitance tomography sensor, if K (K < 8) sinusoidal excitation signals are applied to K electrodes, K*(8 - K) mutual capacitances can be measured. When K = 4, the number of mutual capacitances for each channel switch can be maximized, and thus the number of channel switches can be minimized, improving the data acquisition rate and the image reconstruction rate. Therefore, for an 8-electrode capacitance tomography sensor, the minimum number of channel switches is 3.

[0047] The microcontroller system controls the switch array to complete the first switch, and the eight electrodes are divided into two groups. E1, E2, E3, E4 are connected to the excitation circuit, and the excitation circuit generates an excitation signal I. E5, E6, E7, E8 are connected to the measurement circuit MM. Under the conditions that the excitation frequencies are ω1 and ω2, measure the current on E5, E6, E7, E8, convert it into a digital signal through the current-voltage conversion circuit and the analog-to-digital converter, and demodulate the inter-electrode capacitance values at different excitation frequencies

[0048] The microcontroller system controls the switch array to complete the second switching. On the basis of the first switching, the two subgroups are divided into four subgroups. E1 and E2 are connected to the excitation circuit, E3 and E4 are connected to the measurement circuit MM, E5 and E6 are connected to the excitation circuit, E7 and E8 are connected to the measurement circuit MM, and the interelectrode capacitance values at different excitation frequencies are demodulated.

[0049] The microcontroller system controls the switch array to complete the third switching. On the basis of the second switching, the four subgroups are divided into eight subgroups. E1 is connected to the excitation circuit, E2 is connected to the measurement circuit M, E3 is connected to the excitation circuit, E4 is connected to the measurement circuit M, E5 is connected to the excitation circuit, E6 is connected to the measurement circuit M, E7 is connected to the excitation circuit, E8 is connected to the measurement circuit M, and the interelectrode capacitance values at different excitation frequencies are demodulated. The parallel data acquisition method involved in the present invention is as Figure 3 shown.

[0050] For the eight-electrode electrical capacitance tomography sensor, by adopting the parallel data acquisition scheme proposed by the present invention, through three switchings, 28 groups of interelectrode capacitance data at different excitation frequencies are obtained respectively. Compared with the seven-channel switching times in the classical single-frequency excitation and measurement scheme, the channel switching times for obtaining the same interelectrode capacitance data are reduced by four times. Thus, it can be seen that the parallel data acquisition method proposed by the present invention can improve the data acquisition rate and further improve the image reconstruction rate.

[0051] The capacitance data processing method involved in the present invention is as Figure 4 shown. Under the conditions of an empty field (the sensing area is filled with a low-dielectric-constant substance), a full field (the sensing area is filled with a high-dielectric-constant substance), and a mixed field (a mixture of high- and low-dielectric-constant substances), parallel data acquisitions at two different frequencies are respectively carried out, and the acquired data is denoted as For the capacitance values at different frequencies, is respectively used for normalization to obtain as the basis, and through secondary normalization is carried out, where β is an adjustment factor.

[0052] The image reconstruction is carried out using the capacitancedata after secondary normalization to obtain the phase state distribution image of the mixture containing the conductive phase in the imaging area.

[0053] The above are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. An ECT data acquisition and processing method, characterized in that, ECT data acquisition is performed by an ECT data acquisition device. The ECT data acquisition device includes a pipeline, a shielding cover (5), and a plurality of electrodes (3). A plurality of arc-shaped grooves (4) for placing the electrodes (3) are provided between the inner wall (1) and the outer wall (2) of the pipeline. The arc-shaped grooves (4) are evenly distributed in a circumferential array, and adjacent arc-shaped grooves (4) are not connected to each other. A shielding cover (5) is provided between the arc-shaped grooves (4) and the outer wall (2). An imaging area (6) is provided in the area surrounded by the inner wall (1) of the pipeline. For a two-phase mixture containing a conductive phase, the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range are selected for excitation, and the capacitance data collected at two different excitation frequencies are subjected to secondary normalization processing to improve the data acquisition rate and the image reconstruction rate. The specific steps are as follows: Step 1: Electrodes (3) are placed in all the arc-shaped grooves (4) in the pipeline of the ECT data acquisition device. Any one of the N electrodes is selected as the No. 1 electrode and numbered as E1, and the remaining N - 1 electrodes are sequentially numbered as E2, E3, E4... E(N) in the counterclockwise or clockwise direction. Step 2: Under the conditions that the excitation frequencies are respectively the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range, the microcontroller system controls the switch array to complete x times of switching, and respectively obtains N*(N - 1) / 2 groups of inter-electrode capacitance values at two different excitation frequencies. Step 3: Under three conditions, namely an empty field filled with a low dielectric constant material in the imaging area, a full field filled with a high dielectric constant material in the imaging area, and a mixed field filled with both a high dielectric constant material and a low dielectric constant material in the imaging area, parallel data acquisitions are respectively performed at two different excitation frequencies. The acquired data are recorded as the inter-electrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the empty field condition The inter-electrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the empty field condition The inter-electrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the full field condition The inter-electrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the full field condition The inter-electrode capacitance when the excitation frequency is the lower limit frequency ω1 of the dispersion frequency range under the mixed field condition The inter-electrode capacitance when the excitation frequency is the upper limit frequency ω2 of the dispersion frequency range under the mixed field condition For the capacitance data acquired at two different excitation frequencies, respectively through perform parallel normalization operations. Based on obtaining the parallel normalization data corresponding to the frequencies, through perform secondary normalization, where β is an adjustment factor, and C d is the capacitance value after secondary normalization; Step 4: Image reconstruction is performed using the capacitancedata after secondary normalization obtained in Step 3 to obtain the phase distribution images of the mixture containing the conductive phase in the imaging area.

2. The ECT data acquisition and processing method according to claim 1, wherein In Step 2, the specific steps for the microcontroller system to control the switch array to complete x times of switching are as follows: Step 2.1 The microcontroller system controls the switch array to complete the first switching: E1, E2, E3... E(N / 2) are divided into the first group and connected to the excitation circuit, and E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N) are divided into the second group and connected to the measurement circuit M. Under the conditions that the excitation frequencies are respectively the lower limit frequency ω1 and the upper limit frequency ω2 of the dispersion frequency range, the current values on E(N / 2 + 1), E(N / 2 + 2), E(N / 2 + 3)... E(N) are measured, converted into digital signals through a current-voltage conversion circuit and an analog-to-digital converter, and the inter-electrode capacitance values at different excitation frequencies are demodulated through the digital signals. Step 2.2: The microcontroller system controls the switch array to complete the second switching: Based on the grouping in Step 2.1, the first group is equally divided into the first-1 group and the first-2 group. E1, E2... E(N / 4) of the first-1 group are connected to the excitation circuit, and E(N / 4 + 1), E(N / 4 + 2),... E(N / 2) of the first-2 group are connected to the measurement circuit M; the second group is equally divided into the second-1 group and the second-2 group. E(N / 2 + 1), E(N / 2 + 2)... E(3N / 4) of the second-1 group are connected to the excitation circuit, and E(3N / 4 + 1), E(3N / 4 + 2)... E(N) of the second-2 group are connected to the measurement circuit M, and the interelectrode capacitance values at two different excitation frequencies are demodulated; Step 2.3: The several groups of electrodes divided in the previous step are equally divided again and respectively connected to the measurement circuit M and the excitation circuit, and the interelectrode capacitance values at two different excitation frequencies are demodulated; Step 2.4: Repeat the operation in Step 2.3 until x channel switches are completed, and N*(N - 1) / 2 groups of interelectrode capacitance values at two different excitation frequencies are obtained respectively.

3. The ECT data acquisition and processing method according to claim 1, wherein The number N of the arc-shaped grooves (4) is calculated according to the following formula: N = 2 x , where x ≥ 3 and x represents the number of channel switching times.

4. The ECT data acquisition and processing method according to claim 1, wherein The distance between the inner wall (1) and the arc-shaped groove (4) is 1 mm to 3 mm.

5. The ECT data acquisition and processing method according to claim 1, wherein The number of the electrodes (3) is the same as that of the arc-shaped grooves (4).

6. The ECT data acquisition and processing method according to claim 1, wherein It further includes a microcontroller system for controlling the switch array, and the microcontroller system is connected to the electrodes through the switch array.

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