CN106932444A - A kind of batching interface test experience device and experimental technique based on electrical conductivity - Google Patents

Abstract

The invention relates to an experimental device and method for detecting a mixed oil interface based on electrical conductivity, which is characterized in that it includes a signal generator, two annular measuring devices equipped with several pairs of electrical conductivity probes, two signal processing circuits, two Data acquisition cards with different resolutions and a host computer. Two ring-shaped measuring devices are arranged at the end of the experimental pipeline, and the input ends of each pair of conductance probes are connected to the signal generator; the output ends of each pair of conductance probes on the two ring-shaped measuring devices are respectively connected to two signal processing circuits. The output signal of each pair of conductivity probes is demodulated on the measuring device to obtain a DC current signal reflecting the concentration of the solution, which is sent to the data acquisition card. The two data acquisition cards are used to modulate and demodulate the obtained DC current signals, convert them into standard current signals and send them to the host computer for data processing, storage and display. The invention can be widely used in the detection of the mixed oil interface in the sequential transportation of refined oil.

Description

Experimental device and method for detecting mixed oil interface based on electrical conductivity

technical field

The invention relates to a measuring device for sequentially conveying mixed oil, in particular to an experimental device and method for detecting mixed oil interface based on electrical conductivity.

Background technique

During the sequential transportation along the pipeline, reliable and accurate measurement of the mixed oil in the mixed oil area is the basic condition for the success of the sequential transportation, and it is also an important condition for accurately grasping the change of the mixed oil when the laboratory conducts the research of the sequential transportation of the mixed oil. The mixed oil measuring device is generally installed at the head and end of the station to detect the mixed oil concentration, so as to determine the mixed oil of the delivered oil according to the change of the mixed oil concentration, and send a signal to the gate valve switching device to accurately cut the mixed oil, so that each section of the oil Products are sent to different storage tanks.

At present, the most widely used monitoring methods and instruments on refined oil pipelines are as follows: one is based on the principle of oil density difference, that is, using a density meter to detect mixed oil; the other is a capacitive instrument, this measuring device The principle is to determine the change of the oil concentration in sequence according to the change of the dielectric constant of mixed oil; the third is based on the principle of the change of ultrasonic and light wave propagation speed in the oil flow; the fourth is based on the difference of refractive index of different media, using optical The detection system detects the mixed oil interface. However, the above-mentioned several oil-contamination detection methods cannot grasp the concentration of contaminating oil at different positions on the pipe cross-section in laboratory experiments.

As shown in Figure 1, in recent years, the flow parameter measurement technology of the pipe cross section has been widely used in multiphase pipe flow, such as the use of conductivity probes to measure the liquid holdup of gas-liquid two-phase flow, and then to measure the flow parameters at different positions on the pipe cross section. The concentration of mixed oil is measured. The application of conductance probe measurement is based on the fact that the conductance between two electrodes installed on a special pipe section has a certain relationship with the thickness of the liquid film. The principle is that there is a certain relationship between the conductance of the liquid at a certain height and its height, so the height of the liquid is obtained by measuring the conductance of the liquid around the probe. The disadvantages of this technology are: ① only the data of the measurement point at the center of the pipe can be collected on the pipe section, and it cannot fully reflect the overall liquid holdup distribution and gas-liquid change characteristics on a certain section of the pipe; ② due to the requirement of accurate measurement In order to measure the change law of liquid holdup in a certain radial direction, a small probe needs to run through the entire pipeline, and under the impact of a certain flow velocity, the probe in the pipeline may be washed out and deformed, so it must be Both ends use relaxation devices such as AB glue to fasten the probe, but since the probe is fixed on the pipe by AB glue, its tensioning effect may not be realized. Therefore, the influence of the deformation of the probe on the measurement accuracy cannot be ignored.

Contents of the invention

In view of the problems referred to above, the object of the present invention is to provide a kind of oil-contaminated interface detection experimental device and experimental method based on electrical conductivity, by setting the annular measurement device with many pairs of electrical conductivity probes to measure the different radial positions on the same pipe section The concentration value of mixed oil is detected, and the measurement accuracy is high.

In order to achieve the above object, the present invention adopts the following technical solutions: a conductivity-based oil-contamination interface detection experimental device is characterized in that: it includes a signal generator, two annular measuring devices provided with several pairs of conductivity probes, Two signal processing circuits, two data acquisition cards with different resolutions, and a host computer; the two annular measuring devices are arranged in the end pipeline of the test section of the experimental pipeline, and the input ends of each pair of conductance probes on the two annular measuring devices are Connected with the signal generator; the output ends of each pair of conductance probes on the two ring measuring devices are respectively connected with the two signal processing circuits; the signal generator is each pair of conductance probes on the two ring measuring devices The input signal is provided, and the two signal processing circuits are respectively used to demodulate the output signals of each pair of conductance probes on the ring measuring device to obtain a DC current signal reflecting the concentration of the solution, and send it to the two data acquisition cards; The data acquisition card is used to modulate and demodulate the obtained DC current signals, convert them into standard current signals and send them to the host computer for data processing, storage and display.

The annular measuring device includes an annular gasket and several pairs of conductivity probes fixedly arranged on the annular gasket; wherein the first pair of the conductivity probes are fixed on any diameter passing through the center of the annular gasket, The remaining pairs of conductance probes are respectively arranged in parallel with the first pair of conductance probes, and the vertical distances of each pair of conductance probes are determined according to the measurement accuracy requirements, so as to ensure that different radial directions on the tube section can be measured. Concentration value; the outer ends of the two conductance probes in each pair of conductance probes are aligned with the outer diameter edge of the ring gasket, and the inner ends of the two conductance probes are adjacent to but not in contact.

The annular gasket in the annular measuring device needs to match the inner diameter of the pipe at the end of the test section of the experimental pipe section.

The pairs of conductance probes are fixed on the ring spacer by epoxy glue.

The two annular measuring devices are arranged at the end of the experimental pipeline one by one through four flanges welded on the experimental pipeline, and a polytetrafluoroethylene gasket is used between the flange and the contact surface of the two annular measuring devices Make a seal.

An experimental method for detecting an oil-contaminated interface based on electrical conductivity using the device, characterized in that it comprises the following steps: 1) making several pairs of conductance probes of different lengths; 2) calibrating the conductance probes to obtain the concentration of contaminating oil The fitting relationship between the value and the output current value of the conductance probe; 3) After the calibration is completed, fix each pair of conductance probes on the ring gasket to form two sets of ring measuring devices; 4) Set the two sets of ring measuring devices in the experimental In the end pipeline of the pipeline test section, and its input end is connected with the signal generator, and the output signal of the signal generator is set according to the experimental requirements; 5) The output ends of each pair of conductivity probes of the two ring measuring devices are connected with Two data processing circuits and two data acquisition cards with different resolutions are connected; 6) According to the fitting relationship between the obtained mixed oil concentration value and the output current value of the conductivity probe, and the output current value of the conductivity probe, the sequence transmission pipeline is obtained The mixed oil concentration values corresponding to different radial directions of the pipe section.

In said step 1), the manufacturing method of the conductivity probe comprises the following steps: 1. determine the specific model of the syringe needle and the diameter of the platinum wire according to the experimental requirements, and cut the syringe needle and the platinum wire to the required length, and use a grinding wheel to machine to make the incision smooth; ②Cut the PTFE thin tube to the required length, insert the processed platinum wire into the PTFE thin tube, and reserve a section of platinum wire at both ends to expose the tube. To ensure that one end of the platinum wire can be connected to the data line, and the other end of the platinum wire can be in contact with the conductive solution; ③Insert the PTFE thin tube inserted into the platinum wire into the prepared syringe needle; ④Fill the syringe needle with insulating material, Insulate the platinum wire from the syringe needle; ⑤ Coat the outer wall of the syringe needle with glass glue for insulation, and ensure that the platinum wires at both ends reserved in step ② are not insulated from each other to obtain a conductivity probe.

In said step 2), the method for calibrating the conductivity probe comprises the following steps: 1. adding a certain amount of edible salt to a beaker of a certain volume, and after the edible salt is completely melted, measure the density of brine with a Baume meter; 2. The two conductance probes are fixed on the cardboard with AB glue, and the two ends are respectively connected to the signal generator and the signal processing circuit through the signal line. Put the cardboard with the conductance probe fixed on the beaker so that the tip of the conductance probe Immerse in salt water; ③Set the output voltage of the signal generator to provide the input signal for the conductivity probe, and the signal processing circuit demodulates the output signal of the conductivity probe, and sends it to the host computer through the data acquisition card to obtain the current at the concentration of the salt water Output value; ④Remove the cardboard and add a certain amount of edible salt to the beaker one by one, measure the density of the brine after adding salt each time, and repeat the step ③ to measure multiple sets of data; ⑤The host computer analyzes and processes the experimental data to obtain The fitting relationship between different saline concentrations and the output current value of the conductivity probe.

The present invention has the following advantages due to the adoption of the above technical scheme: 1. The present invention can simultaneously measure the mixed oil concentration values at different radial positions on the same pipe section because the annular measuring device is provided with many pairs of conductivity probes, and the measurement results more precise. 2. In the present invention, since each pair of conductance probes is fixed on the ring gasket through AB glue, it has a certain tension effect, so that the probes will not be washed and deformed, ensuring high measurement accuracy. 3. Since the logarithm and distance of the conductance probes on the annular measuring device can be set according to the needs of the experiment, the present invention can meet the measurement of different precision requirements, and has a wider application range. 4. In the present invention, since the output signals of each pair of conductivity probes in the annular measuring device can be displayed in real time by the host computer after passing through the signal processing circuit and the data acquisition board, the observation of the concentration detection results of the oil-contaminated interface is more intuitive. 5. Since the present invention is provided with two sets of annular measuring devices, which respectively measure the concentration of upstream and downstream oil products in the pipeline, the scope of the detection range is expanded and the detection accuracy is improved. The invention has simple structure and convenient operation, so the invention can be widely used in the field of oil-contaminated interface detection in sequential transportation.

Description of drawings

Fig. 1 is a schematic structural view of a conductivity probe in the prior art; wherein, figure (a) is a front view, and figure (b) is a schematic diagram of a tube section;

Fig. 2 is a structural representation of the present invention;

Fig. 3 is a schematic diagram of a specific embodiment of the present invention;

Fig. 4 is a schematic structural view of the annular measuring device of the present invention;

Fig. 5 is a schematic diagram of the manufacturing process of the conductivity probe of the present invention;

Fig. 6 is a diagram showing the relationship between brine concentration and current output when the brine density reaches 1.260g/ml in the embodiment of the present invention;

Fig. 7 is a graph showing the relationship between the concentration of brine and the current output when the density of brine in the embodiment of the present invention reaches a saturation of 1.334 g/ml.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 2 and Fig. 3, the experimental device for detecting the mixed oil interface based on conductivity of the present invention comprises a signal generator 1, two annular measuring devices 2, two signal processing circuits 3, two data acquisition cards 4 with different resolutions, and A host computer 5 . Two ring-shaped measuring devices 2 are arranged in the end pipe of the test section of the experimental pipeline before and after, and they all include a ring gasket 21 and several pairs of conductance probes 22 arranged on the ring gasket 21; each pair of conductance probes on the two ring-shaped measuring devices 2 The input ends of 22 are connected to the signal generator 1 , and the output ends of each pair of conductance probes 22 on the two annular measuring devices 2 are respectively connected to two signal processing circuits 3 . The signal generator 1 is used to provide input signals for each pair of conductance probes 22 on the two ring measuring devices 2; the two signal processing circuits 3 are used to demodulate the output signals of each pair of conductance probes 22 on the two ring measuring devices 2 , to obtain a direct current signal reflecting the concentration of the solution, and send it to the data acquisition card 4; the two data acquisition cards 4 are respectively used to modulate and demodulate the obtained direct current signals, convert it into a standard current signal, and send it to the upper position Machine 5 performs data processing, storage and display.

As shown in FIG. 4 , the annular measuring device 2 includes an annular gasket 21 and several pairs of conductivity probes 22 fixedly arranged on the annular gasket 21 . In the present invention, only four pairs of conductivity probes 22 are used as an example for introduction, but it is not limited thereto. Wherein, the first pair of conductance probes is fixedly arranged on any diameter passing through the center of the ring gasket 21, and the other pairs of conductance probes are respectively arranged in parallel with the first pair of conductance probes, and the vertical distances of each pair of conductance probes are according to The measurement accuracy depends on the requirements to ensure that the measurement can obtain the concentration values of different radial directions on the pipe section. Simultaneously, the outer ends of the two conductance probes in each pair of conductance probes are all aligned with the outer diameter edge of the ring gasket 21, and the inner ends of the two conductance probes are adjacent to but not in contact, so as to ensure that the measurement results in any radial direction of the tube section. point concentration changes.

In the above-mentioned embodiments, the outer diameter of the annular gasket 22 in the annular measuring device 2 needs to match the inner diameter of the pipe at the end of the test section of the experimental pipe.

In the above-mentioned embodiments, each pair of conductance probes 22 is fixed on the ring gasket 21 by epoxy glue.

In each of the above-mentioned embodiments, the two ring-shaped measuring devices 2 are arranged in the end pipe of the test section of the experimental pipeline through four flanges welded on the experimental pipeline one after the other, and the contact surface between the flanges and the contact surface of the two ring-shaped measuring devices Seal with PTFE gaskets.

Based on the above-mentioned experimental device for detecting an oil-contaminated interface based on electrical conductivity, the present invention also provides an experimental method for detecting an oil-contaminated interface based on electrical conductivity, comprising the following steps:

1) Make several pairs of conductance probes 22 with different lengths.

As shown in Figure 5, the fabrication method of the conductance probe comprises the following steps:

①Determine the specific model of the syringe needle 221 and the diameter of the platinum wire 222 according to the experimental requirements, cut the syringe needle 221 and the platinum wire 222 to the required length, and use a grinder to grind them to make the incision smooth.

②Cut the PTFE thin tube 223 to the required length, insert the treated platinum wire 222 into the PTFE thin tube 223, and reserve a section of platinum wire 222 at both ends to expose the tube to ensure that the platinum One end of the wire 222 can be connected to the data line, and the other end of the platinum wire 222 is in contact with the conductive solution. In the present invention, the lengths of the platinum wires 222 reserved at both ends are 1mm and 5mm respectively, that is, the 1mm end is in contact with the conductive solution, and the 5mm end is connected with the data line.

③ Insert the thin polytetrafluoroethylene tube 223 inserted into the platinum wire 222 into the prepared syringe needle 221 .

④ Fill the syringe needle 221 with insulating material, and insulate the platinum wire 222 from the syringe needle 221 .

In order to ensure that no air is mixed during the filling process, before filling, connect the syringe needle 221 and the syringe 225 with the heat-shrinkable tube 224, heat the heat-shrinkable tube 224 to shrink, and tightly connect the syringe needle 221 and the syringe 225. At this time, mix the syringe 225 The insulating material such as epoxy resin is slowly pushed into the syringe needle 221 until the epoxy resin overflows from the other end, and the syringe 225 is removed until the epoxy resin is cured.

⑤ Coat the outer wall of the syringe needle 221 with glass glue for insulation, and ensure that the platinum wires 222 at both ends reserved in step ② are not insulated from each other to obtain the conductivity probe 22 .

2) Calibrate the conductivity probe 22 to obtain a fitting relationship between the concentration value of the mixed oil and the output current value of the conductivity probe 22 .

First, the measurement principle of the conductivity probe 22 is briefly introduced. Under the condition that the composition and temperature of the conductive solution are fixed, the conductivity of the conductive solution is fixed, and the conductivity of the measurement medium between the two probes of the conductivity probe 22 will change with the concentration of the conductive solution, and there is a definite relationship , as follows:

Among them, L is the conductance; R is the resistance; ρ is the resistivity; A is the effective area of the conductor; l is the effective length of the conductor; k is the conductivity. The energized electrode will form an electric field in the conductive solution, and the lines of force are mainly distributed between the two electrodes. The effective area A of the conductor can be approximated by the effective area of the electrode immersed in the conductive solution. The distance between the electrodes remains unchanged, that is, the effective area of the conductor and the effective length of the conductor remain unchanged. Therefore, when the concentration of the conductive solution is constant, the conductance L between the two electrodes is constant. After that, keep the voltage across the energized electrodes constant. According to Ohm's law, the current flowing through the electrodes is proportional to the conductance of the conductive solution between the two electrodes, that is

It can be seen from the above formula that the output signal of the conductivity probe 22, that is, the current signal, can reflect the change of the solution concentration.

The principle of the conductivity probe measuring the concentration of the conductive solution is that there is a certain relationship between the conductivity of the solution and the output signal of the conductivity probe, but the theory of the conductivity probe is not yet mature, so it must be calibrated before use to obtain the concentration of the solution and the output signal of the conductivity probe. relationship to the output signal. That is, first conduct laboratory experiments, measure the conductance corresponding to different concentrations of conductive solutions, and obtain a fitting relationship between the concentration of conductive fluid and its conductivity, and then according to the fitting relationship and the actual conductivity of the conductive fluid obtained during actual measurement, get Conductive fluid concentration during actual sequential delivery.

In the present invention, the sequential delivery experiment is carried out with brine and clear water instead of oil, so the concentration change during the sequential delivery is considered by measuring the density of brine. There is a certain relationship between a certain concentration of salt water and the conductance of the salt water, that is, the conductivity of the salt water in the circuit is measured to reflect the concentration change of the salt water.

The calibration method of the conductivity probe 22 includes the following steps: ①Add a certain amount of edible salt into a beaker with a certain volume, and measure the density of the salt water with a Baume meter after the edible salt is completely dissolved; ②Use two conductivity probes 22 with AB The glue is fixed on the cardboard, and the two ends are respectively connected to the signal generator 1 and the signal processing circuit 3 through signal lines, and the cardboard with the conductivity probe 22 fixed is placed on the beaker, so that the tip of the conductivity probe 22 is immersed in salt water; ③ Set the output voltage of the signal generator 1 to provide the input signal for the conductivity probe 22, and the signal processing circuit 3 demodulates the output signal of the conductivity probe, and sends it to the host computer 5 through the data acquisition card 4 to obtain the lower concentration of the brine. ④Remove the cardboard and add a certain amount of edible salt to the beaker, measure the density of the salt water after adding salt each time, and then repeat step ③ to measure multiple sets of data; ⑤The host computer 5 analyzes the experimental data After processing, the fitting relationship between the concentration of saline and the output current value of the conductivity probe is obtained.

The present invention has carried out multiple groups of experiments, and the following two groups of experimental result data are respectively the calibration experiment results (as shown in Table 1) when the saline solution reaches saturation and does not reach saturation, and wherein the experimental group 1 configures the saline terminal concentration to be 1.260 g/mL, the end point concentration of saline in experimental group 2 was 1.334 g/mL.

Table 1 Calibration experiment result data

Among them: m0 is the density of clear water, 1.007g/mL; m1 is the density of brine measured last time, g/mL; mx is the density of brine measured any time, g/mL.

As shown in Figure 6 and Figure 7, the dimensionless concentration (mx-m0)/(m1-m0) of brine has a linear relationship with the output display current value of the host computer 5, and it can be seen from the second set of data that when the brine is configured to saturation When the brine dimensionless concentration and current output value deviate from the fitted linear relationship line, that is, the incomplete data when the concentration is low is better than the linearity of the complete data fitting. The reason is that when the brine reaches saturation, the conductivity of brine and The concentration of salt water is not linear, and another reason is that the hardness of the tap water used is too high, which affects the test results of the experiment.

3) After the calibration is completed, each pair of conductance probes 22 with different lengths is fixed on the ring gasket 21 to form two sets of ring measuring devices 2 .

In the present invention, the syringe needle used when making the conductance probe 22 is a 12# syringe needle with an outer diameter of 1.26mm and an inner diameter of 0.9mm. The diameter of the platinum wire used is 0.3 mm. The inner diameter of the ring gasket adopted is 26mm, the outer diameter is 46mm, and the thickness is 10mm. The first pair of conductance probes is arranged on any diameter passing through the center of the ring gasket, and the remaining pairs of conductance probes are arranged parallel to the first pair of conductance probes, and they are aligned with the straight line passing through the tube core and parallel to the direction of the probes. The distance settings are 0.52r, 0.83r, and 0.94r, respectively, that is, the distances between each pair of conductivity probes are 6.5mm, 3.9mm, and 1.3mm, respectively. The distance between the tips of the two conductance probes in each pair of conductance probes is 0.4 mm (as shown in FIG. 4 ). The purpose of arranging the conductivity probe in this way is to measure the non-radial concentration value on the tube section, and the distance between the probes at the tube wall is small to observe the concentration change of the tube wall.

4) Set the two annular measuring devices 2 in the end pipeline of the test section of the experimental pipeline, and connect their input terminals to the signal generator 1, and set the output signal of the signal generator 1 according to the experimental requirements.

In the present invention, an alternating voltage signal with a signal frequency of 10 kHz and an amplitude of 5 V is used as the input signal of each pair of conductance probes. After the signal generator is set up as required, it is connected to each pair of conductance probes of the two ring-shaped measuring devices. . Since each annular measuring device is provided with four pairs of conductance probes in the present invention, the annular measuring device can measure instantaneous conductance values of liquids at four different measuring points on the pipeline cross section.

5) Connect the output terminals of each pair of conductance probes 22 of the two annular measuring devices 2 to two data processing circuits 3 and two data acquisition cards 4 with different resolutions in turn.

Among them, the annular measuring device 2 (the oil flow direction shown in Fig. 3 ) located upstream is connected with the low-resolution data acquisition card, and its detection range is high but the accuracy is low; the annular measuring device 2 located downstream is connected with the high-resolution data acquisition card The acquisition card is connected, and the detection range is low and the precision is high; two ring-shaped measuring devices 2 are installed on the pipeline and used together to expand the range of the detection range and improve the detection accuracy.

6) According to the fitting relationship between the obtained mixed oil concentration value and the output current value of the conductivity probe, and the output current value of the conductivity probe in the experiment, the mixed oil concentration value corresponding to the different radial direction of the pipe section in the sequential delivery pipeline can be obtained .

The above-mentioned embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not excluded from the protection scope of the present invention.

Claims (8)

1. A kind of oil-contaminated interface detection experiment device based on electric conductivity, it is characterized in that: it comprises a signal generator, two are provided with the annular measuring device of some pairs of electric conductance probes, two signal processing circuits, two different resolutions Data acquisition card and a host computer; The two annular measuring devices are arranged in the end pipeline of the experimental pipeline test section before and after, and the input ends of each pair of conductance probes on the two said annular measuring devices are connected with the said signal generator; The output terminals of the probes are respectively connected to the two signal processing circuits; the signal generator provides input signals for each pair of conductance probes on the two ring measuring devices, and the two signal processing circuits are respectively used to pair the conductance probes on the ring measuring devices. The output signals of each pair of conductivity probes are demodulated to obtain DC current signals reflecting the concentration of the solution, and sent to the two data acquisition cards; the two data acquisition cards are respectively used to modulate the obtained DC current signals Demodulate, convert it into a standard current signal and send it to the host computer for data processing, storage and display. 2. A kind of oil-contaminated interface detection experimental device based on electrical conductivity as claimed in claim 1, is characterized in that: said annular measuring device comprises an annular gasket and several pairs of conductivity probes fixedly arranged on the annular gasket ; wherein the first pair of conductance probes is fixedly arranged on any diameter passing through the center of the ring gasket, and the remaining pairs of conductance probes are respectively arranged in parallel with the first pair of conductance probes, and each pair The vertical distance of the conductance probe is determined according to the measurement accuracy requirements, so as to ensure that the measurement obtains different radial concentration values on the tube section; The outer diameter edges of the sheets are aligned, and the inner ends of the two conductivity probes are in close proximity but not in contact. 3. A kind of oil-contaminated interface detection experimental device based on electrical conductivity as claimed in claim 2, is characterized in that: the described annular spacer in the described annular measuring device needs to match with the inner diameter of the end pipeline of the test section of the experimental pipe section . 4 . The experimental device for detecting an oil-contaminated interface based on electrical conductivity as claimed in claim 2 , wherein each pair of electrical conductivity probes is fixed on the annular gasket by epoxy glue. 5 . 5. A kind of oil-contaminated interface detection experimental device based on electrical conductivity as claimed in claim 1, is characterized in that: two said ring-shaped measuring devices are arranged on the experimental pipe one after the other through four flanges welded on the experimental pipeline. The end of the pipe, and the contact surfaces between the flange and the two annular measuring devices are sealed with polytetrafluoroethylene gaskets. 6. A method for detecting an oil-contaminated interface based on electrical conductivity of the device according to any one of claims 1 to 5, characterized in that it comprises the following steps: 1) Make several pairs of conductivity probes with different lengths; 2) Calibrate the conductivity probe to obtain the fitting relationship between the concentration of mixed oil and the output current value of the conductivity probe; 3) After the calibration is completed, fix each pair of conductivity probes on the ring gasket to form two sets of ring measuring devices; 4) Set two sets of annular measuring devices in the end pipeline of the test section of the experimental pipeline, and connect its input end to the signal generator, and set the output signal of the signal generator according to the experimental requirements; 5) connecting the output terminals of each pair of conductance probes of the two ring-shaped measuring devices with two data processing circuits and two data acquisition cards with different resolutions in turn; 6) According to the fitting relationship between the obtained mixed oil concentration value and the output current value of the conductivity probe, and the output current value of the conductivity probe, the mixed oil concentration value corresponding to the different radial direction of the pipe section in the sequential delivery pipeline is obtained. 7. a kind of oil-contaminated interface detection experimental method based on electrical conductivity as claimed in claim 6, is characterized in that: in described step 1), the preparation method of conductivity probe comprises the following steps: ① Determine the specific model of the syringe needle and the diameter of the platinum wire according to the experimental requirements, cut the syringe needle and the platinum wire to the required length, and use a grinder to polish the cut to make the cut smooth; ② Cut the PTFE thin tube to the required length, insert the processed platinum wire into the PTFE thin tube, and reserve a section of platinum wire at both ends to expose the tube to ensure that the platinum wire at one end can be connected with the data The other end of the platinum wire can be in contact with the conductive solution; ③Insert the thin polytetrafluoroethylene tube inserted into the platinum wire into the prepared syringe needle; ④ Fill the syringe needle with insulating material to insulate the platinum wire from the syringe needle; ⑤ Coat the outer wall of the syringe needle with glass glue for insulation, and ensure that the platinum wires at both ends reserved in step ② are not insulated from each other to obtain a conductivity probe. 8. a kind of oil-contaminated interface detection experimental method based on electrical conductivity as claimed in claim 6, is characterized in that: in described step 2), the method that conductivity probe is calibrated comprises the following steps: ① Add a certain amount of edible salt into a beaker with a certain volume, and measure the density of the brine with a Baume meter after the edible salt is completely dissolved; ②Fix the two conductance probes to the cardboard with AB glue, and connect the two ends to the signal generator and the signal processing circuit respectively through the signal line. Put the cardboard with the conductance probe fixed on the beaker to make the conductance probe dip the tip in salt water; ③Set the output voltage of the signal generator to provide the input signal for the conductance probe, and the signal processing circuit demodulates the output signal of the conductance probe, and sends it to the host computer through the data acquisition card to obtain the current output value under the saline concentration; ④Remove the cardboard and add a certain amount of edible salt to the beaker one by one, measure the density of the salt water after adding salt each time, repeat step ③ to measure multiple sets of data; ⑤ The host computer analyzes and processes the experimental data, and obtains the fitting relationship between different brine concentrations and the output current value of the conductivity probe.