A device and method for testing resistivity and dielectric constant of oil-rich coal during pyrolysis

Abstract

The present invention provides a device and method for testing the resistivity and dielectric constant of oil-rich coal during pyrolysis, which belongs to the field of coal body characteristic testing, and includes: a test box, one side of which is connected to a nitrogen supply system, and the other side is connected to a pyrolysis product collection system; a heating seat, which is arranged in the test box; a first electrode plate, which is arranged on the heating seat, and the test sample of the oil-rich coal is placed on the first electrode plate; three force-applying components, which are respectively arranged above the test box and on two adjacent sides; a lifting component, which is arranged between the heating seat and the top force-applying component, and a second electrode plate is arranged on the side of the lifting component close to the first electrode plate, and the first electrode plate and the second electrode plate constitute a flat plate capacitor; a parameter measurement module, whose data acquisition end is electrically connected to the first electrode plate and the second electrode plate. The device can truly simulate the in-situ pyrolysis process, and realize the measurement of the resistivity and dielectric constant of the pyrolysis process of the oil-rich coal in one experiment under the action of triaxial or uniaxial pressure.

Description

Technical Field

[0001] The invention belongs to the technical field of coal body characteristic testing, and in particular relates to a device and method for testing resistivity and dielectric constant of oil-rich coal during pyrolysis. Background Art

[0002] The traditional way to mine oil-rich coal is to first dig the oil-rich coal to the ground, and then pyrolyze it to produce oil. This method is not only troublesome but also causes serious environmental pollution, and the resource utilization rate is also low. Now, in-situ pyrolysis technology can be used to mine oil-rich coal, that is, the oil-rich coal is heated to the pyrolysis temperature in the original layer, and the tar products produced by pyrolysis are directly extracted. Compared with the traditional ground distillation technology of oil-rich coal, this method is more economical and relatively environmentally friendly, reducing ground pollution. In recent years, scholars at home and abroad have also been working hard to improve this technology. It is very meaningful to study pollution-free mining of mineral resources, which can prevent environmental pollution and protect the ecological environment.

[0003] In the in situ pyrolysis process of oil-rich coal, electromagnetic heating and microwave heating are highly efficient heating methods. The resistivity and dielectric constant of oil-rich coal have a great influence on the in situ heating process and in situ heating efficiency, and these two parameters change in real time during the pyrolysis process. Therefore, testing the changing rules of the above two parameters during the pyrolysis process is of great significance for guiding the selection of pyrolysis process parameters. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a resistivity and dielectric constant testing device and method for oil-rich coal during pyrolysis, so that it can not only measure the expansion degree of oil-rich coal during high-temperature pyrolysis under uniaxial pressure conditions, but also measure the expansion degree of oil-rich coal during high-temperature pyrolysis under triaxial pressure conditions, so as to more thoroughly obtain the relationship between deformation and temperature during pyrolysis of oil-rich coal.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A device for testing resistivity and dielectric constant of oil-rich coal during pyrolysis, comprising:

[0007] The test box is connected to a nitrogen supply system on one side and a pyrolysis product collection system on the other side;

[0008] A heating seat is arranged in the test box;

[0009] A first electrode plate, disposed on the heating seat, on which the test sample of the oil-rich coal is placed;

[0010] Three force-applying components are respectively arranged on the upper side and two adjacent sides of the test box, and are used to apply forces in different directions to the test sample;

[0011] A lifting component is arranged between the heating seat and the force-applying component at the top, and a second electrode plate is arranged on a side of the lifting component close to the first electrode plate, and the first electrode plate and the second electrode plate constitute a flat-plate capacitor;

[0012] The parameter determination module has a data acquisition end electrically connected to the first electrode plate and the second electrode plate, and is used to collect the capacitance value C of the flat plate capacitor of the test sample under pressure and heating. p And the resistance value R.

[0013] Preferably, a limiting groove is provided on the heating seat, an insulating pad is arranged inside the limiting groove, the first electrode plate is placed on the insulating pad, and the cross-sectional area of ​​the test sample is the same as the shape and cross-sectional area of ​​the first electrode plate and the second electrode plate.

[0014] Preferably, the lifting assembly includes telescopic rods arranged on both sides of the heating seat, a top plate is arranged on the top of the telescopic rods, the insulating pad is arranged on the top of the top plate, and a fixing clamp is arranged on the bottom; the second electrode plate is arranged at the bottom of the top plate through the fixing clamp, and the insulating pad is clamped on the top of the top plate.

[0015] Preferably, each of the force-applying components comprises a power mechanism and a pressure plate arranged at a power output end of the power mechanism, the pressure plate is located in the test box and faces the heating seat, and a thin film pressure sensor is arranged at the bottom of the pressure plate.

[0016] Preferably, the nitrogen supply system comprises a nitrogen bottle and a nitrogen heater;

[0017] The nitrogen heater comprises a heating shell and a support frame arranged at the bottom of the heating shell, an electric heating pipe is arranged in the heating shell, a plurality of guide plates are arranged around the electric heating pipe in the heating shell, and a nitrogen outlet is arranged on the heating shell; the heating shell is connected with the nitrogen bottle through a vent pipe, the heating shell is connected with one side of the test box through an electric heating pipeline, and a nitrogen control valve is arranged on the electric heating pipeline;

[0018] A first temperature sensor is arranged inside the test box, and a second temperature sensor is arranged at the nitrogen outlet.

[0019] Preferably, the pyrolysis product collection system includes an oil and gas absorption chamber and a secondary absorption chamber, the oil and gas absorption chamber is connected to the other side of the test box through an oil and gas air guide pipe, the oil and gas absorption chamber is connected to the secondary absorption chamber through a pipeline, the oil and gas absorption chamber and the secondary absorption chamber are both provided with oil and gas absorption solvent, and the oil and gas air guide pipe is provided with an oil and gas control valve.

[0020] Preferably, it also includes a control module and multiple control switches, the signal input end of the control module is connected to the first temperature sensor, the second temperature sensor and three thin film pressure sensors, and the signal output end of the control module is connected to the electric heating tube, the heating seat, the nitrogen control valve, the oil and gas control valve, three power mechanisms and multiple control switches.

[0021] Preferably, the test box and the outer wall of the heating shell are respectively provided with a first insulation layer and a second insulation layer, and the power mechanism is a hydraulic cylinder.

[0022] Another object of the present invention is to provide a method for testing the resistivity and dielectric constant of oil-rich coal during pyrolysis, comprising the following steps:

[0023] The first electrode plate is arranged on the insulating pad in the limiting groove, and the second electrode plate is arranged on the bottom of the top plate of the lifting assembly by a fixing clamp;

[0024] Place the prepared test sample on the first electrode plate, and adjust the telescopic rod of the lifting assembly so that the second electrode plate descends to the top of the test sample and contacts the upper surface of the test sample;

[0025] Start the power mechanism to provide constant vertical and circumferential pressure for the test sample, so that the test sample is in a uniaxial, biaxial or triaxial stress state;

[0026] By controlling the heating power of the heating seat, the first temperature sensor collects the temperature in the test box in real time. When the temperature reaches the set value, the test box is kept at a constant temperature. At the same time, the capacitance value C of the flat capacitor of the test sample under pressure and heating is collected through the parameter measurement module. p And resistance value R;

[0027] Calculate the resistivity ρ through the resistance value R;

[0028]

[0029] Where S is the cross-sectional area of ​​the test sample, and L is the height of the test sample;

[0030] Through the capacitance value C p And the resistivity ρ calculates the dielectric constant ε of the test sample r ;

[0031] Combined with the temperature data collected by the first temperature sensor, the relationship between the heating temperature and the dielectric constant and the resistivity is analyzed, and a relationship diagram between the heating temperature and the dielectric constant and between the heating temperature and the resistivity is drawn.

[0032] Preferably, the test sample is a cube with a dielectric constant ε r The calculation formula is:

[0033]

[0034] Where S is the cross-sectional area of ​​the test sample, L is the height of the test sample, and C p is the capacitance value of the flat plate capacitor obtained by testing, and ε0 is the dielectric constant of vacuum.

[0035] The resistivity and dielectric constant testing device for pyrolysis of oil-rich coal provided by the present invention has the following beneficial effects:

[0036] This device can simulate the in-situ pyrolysis process by setting three force components and a heating seat, and can measure the resistivity and dielectric constant of the pyrolysis process of oil-rich coal in one experiment under triaxial or uniaxial pressure. It can also test the above two parameters in a free state to obtain the relationship between the pyrolysis temperature of oil-rich coal and the resistivity and dielectric constant, so as to better guide the in-situ pyrolysis of oil-rich coal and increase the yield of tar products. At the same time, during the pyrolysis process, nitrogen is injected into the test box through the nitrogen supply system, which can take out the pyrolysis products from time to time, prevent interference with the test process, and improve the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a schematic structural diagram of a device for testing resistivity and dielectric constant during pyrolysis of oil-rich coal according to Example 1 of the present invention;

[0039] Figure 2 It is a partial schematic diagram of the heating seat;

[0040] Figure 3 It is the control principle block diagram of the present invention;

[0041] Figure 4 is the relationship between heating temperature and resistivity;

[0042] Figure 5 This is a graph showing the relationship between heating temperature and dielectric constant.

[0043] Description of reference numerals:

[0044] Test box 1, heating seat 2, limiting groove 201, first electrode plate 3, test sample 4, second electrode plate 5, parameter measurement module 6, insulating pad 7, telescopic rod 8, top plate 9, fixing clamp 10, power mechanism 11, pressing plate 12, film pressure sensor 13, nitrogen bottle 14, heating shell 15, electric heating pipe 16, guide plate 17, nitrogen outlet 18, ventilation pipe 19, electric heating pipeline 20, nitrogen control valve 21, first temperature sensor 22, second temperature sensor 23, oil and gas absorption chamber 24, secondary absorption chamber 25, oil and gas air guide pipe 26, oil and gas control valve 27, control module 28, control switch 29, first thermal insulation layer 30, second thermal insulation layer 31, support frame 32, pipeline 33. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0046] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0047] In addition, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified or limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In the description of the present invention, unless otherwise specified, "plurality" means two or more, which will not be described in detail here.

[0048] Example 1

[0049] The present invention provides a device for testing the resistivity and dielectric constant of oil-rich coal during pyrolysis. Figure 1 and Figure 2As shown, it includes a test box 1, a heating seat 2, a first electrode plate 3, three force-applying components, a lifting component and an LCR tester 6.

[0050] Specifically, one side of the test box 1 is connected to a nitrogen supply system, and the other side is connected to a pyrolysis product collection system. The heating seat 2 is arranged in the test box 1 to simulate the actual environment of the oil-rich coal test sample; in this embodiment, the heating seat 2 is an electric heating plate, and the longitudinal section of the heating seat 2 is L-shaped.

[0051] The three force-applying components are respectively arranged above the test box 1 and on two adjacent sides, and are used to apply forces in different directions to the test sample 4. Specifically, each force-applying component includes a power mechanism 11 and a pressure plate 12 arranged at the power output end of the power mechanism 11. The pressure plate 12 is located in the test box 1 and faces the heating seat 2. A thin film pressure sensor 13 is arranged at the bottom of the pressure plate 12. The power mechanism 11 in this embodiment is a hydraulic cylinder. Because the coal is in a state of three-way force in the original layer, the triaxial state test can simulate the real original conditions. Pressure is applied to the test sample 4 individually or simultaneously by the three force-applying components 1, and then the resistivity and dielectric constant of the oil-rich coal in the real in-situ pyrolysis process are tested. Since two of the force-applying components are already on the two adjacent sides of the test box 1, the longitudinal plate of the L-shaped heating seat 2 is in a different direction from the force-applying component, so as to avoid conflict with the position of the force-applying component and improve the heating effect.

[0052] At the same time, the first electrode plate 3 is arranged on the heating seat 2, and the test sample 4 of the oil-rich coal is placed on the first electrode plate 3. The lifting assembly is arranged between the heating seat 2 and the top force-applying assembly, and the second electrode plate 5 is arranged on the side of the lifting assembly close to the first electrode plate 3. The first electrode plate 3 and the second electrode plate 5 constitute a flat plate capacitor. The data acquisition end of the parameter determination module 6 is electrically connected to the first electrode plate 3 and the second electrode plate 5, and is used to collect the capacitance value C of the flat plate capacitor of the test sample 4 under pressure and heating. p and resistance value R. Specifically, in this embodiment, the parameter determination module 6 is an LCR tester 6 , and the acquisition terminal probes of the LCR tester 6 are clamped on the first electrode plate 5 and the second electrode plate 10 , respectively.

[0053] In order to maintain the stability of the test, in this embodiment, a limiting groove 201 is opened on the heating seat 2, an insulating pad 7 is arranged inside the limiting groove 201, the first electrode plate 3 is placed on the insulating pad 7, and the cross-sectional area of ​​the test sample 4 is the same as the shape and cross-sectional area of ​​the first electrode plate 3 and the second electrode plate 5, thereby improving the test accuracy.

[0054] Specifically, in the present embodiment, the lifting assembly includes telescopic rods 8 arranged on both sides of the heating seat 2. The telescopic rods 8 in the present embodiment are existing electric telescopic rods or telescopic rods with a self-resetting function. A top plate 9 is arranged on the top of the telescopic rod 8, an insulating pad 7 is arranged on the top of the top plate 9, and a fixing clamp 10 is arranged on the bottom. The second electrode plate 5 is clamped at the bottom of the top plate 9 by the fixing clamp 10, and the insulating pad 7 is arranged on the top of the top plate 9. The height of the top plate 9 and the second electrode plate 5 is adjusted by lifting and lowering the four telescopic rods 8, so that the second electrode plate 5 is in contact with the top of the test sample 4 during the experiment. In the present embodiment, there are four telescopic rods 8, which are respectively arranged at the four corners of the bottom of the top plate 9. The area of ​​the top plate 9 is much larger than the area of ​​the test sample 4 and the pressing plate 12, so as to ensure that the distance between the two telescopic rods 8 is greater than the side length of the pressing plate 12, so that the pressing plate can pass through the two telescopic rods 8 and then approach the test sample 4. When the power mechanism 11 of the top force-applying assembly drives the pressing plate 12 to move downward until the pressing plate 12 contacts the insulating pad 7 on the top plate 9 or even squeezes the insulating pad 7, the telescopic rod 8 will automatically contract and fall together with the top plate 9.

[0055] Furthermore, in this embodiment, the nitrogen supply system includes a nitrogen bottle 14 and a nitrogen heater.

[0056] Specifically, the nitrogen heater includes a heating shell 15 and a support frame 32 arranged at the bottom of the heating shell 15. An electric heating tube 16 is arranged in the heating shell 15. A plurality of guide plates 17 are arranged around the electric heating tube 16 in the heating shell 15. The guide plates 17 increase the flow distance of nitrogen in the heating shell 15, so that the nitrogen can turn back and forth in the heating shell 15 to improve the heating efficiency. A nitrogen outlet 18 is arranged on the heating shell 15; the heating shell 15 is connected to the nitrogen bottle 14 through a vent pipe 19, and the heating shell 15 is connected to one side of the test box 1 through an electric heating pipe 20, and a nitrogen control valve 21 is arranged on the electric heating pipe 20; the injected nitrogen is mainly used to replace the air in the test box 1 before the test starts, and the oil and gas products produced by coal pyrolysis are taken out of the test box 1 during the test heating process to prevent interference with the test process and improve the test accuracy. In addition, the products taken out can be collected outside the box. The temperature of the injected nitrogen is consistent with the temperature inside the test box 1, so as not to affect the temperature inside the test box during the gas injection process. The nitrogen entering the heating shell 15 is heated by the electric heating tube 16, so that the temperature of the nitrogen entering the test box 1 through the heating shell 15 is consistent with the temperature inside the test box 1, which is conducive to the discharge of the pyrolysis products.

[0057] In order to conveniently control the temperature of nitrogen and the test box 1, a first temperature sensor 22 is provided inside the test box 1 in this embodiment, and a second temperature sensor 23 is provided at the nitrogen outlet 18, so that the temperature of the incoming nitrogen is consistent with that of the test box 1, thereby reducing the influence of temperature on the experiment.

[0058] Specifically, in this embodiment, the pyrolysis product collection system includes an oil and gas absorption chamber 24 and a secondary absorption chamber 25. The oil and gas absorption chamber 24 is connected to the other side of the test box 1 through an oil and gas air guide pipe 26. The oil and gas absorption chamber 24 is connected to the secondary absorption chamber 25 through a pipeline 33. The oil and gas absorption chamber 24 and the secondary absorption chamber 25 are both provided with an oil and gas absorption solvent acetone solvent, and an oil and gas control valve 27 is provided on the oil and gas air guide pipe 26. The pyrolysis product comes out at the same time as the nitrogen. The pyrolysis product is absorbed and the nitrogen flows out. The absorption may not be complete at one time, so the secondary absorption chamber 22 is provided to make the absorption more complete.

[0059] Furthermore, if Figure 3 As shown, in order to accurately control the test parameters, the present embodiment further includes a control module 28 and a plurality of control switches 29, the signal input end of the control module 28 is connected to the first temperature sensor 22, the second temperature sensor 23 and the three film pressure sensors 13, and the signal output end of the control module 28 is connected to the electric heating tube 16, the heating seat 2, the nitrogen control valve 21, the oil and gas control valve 27, the three power mechanisms 11 and the plurality of control switches 29. The control module 28 can collect the data collected by each sensor in real time, and by comparing the collected data with the set value, the operation of each component is controlled according to the comparison, so that the entire operation process is more precise, and the precision and accuracy of the test are improved.

[0060] In order to reduce the influence of the external environment on the experimental temperature, the first insulation layer 30 and the second insulation layer 31 are respectively provided on the outer wall of the test box 1 and the heating shell 15. Specifically, the refractory fiber insulation layer is used to seal the outlet gap for insulation treatment.

[0061] Based on the same inventive concept, the present invention also provides a method for testing the resistivity and dielectric constant of oil-rich coal during pyrolysis. During the experiment, the pressure in three directions is first set by the control module 28, and then heating is started to perform the experiment, so as to ensure that the pressure in three directions remains constant during the experiment. The film pressure sensor 7 is mainly used to test the pressure and feed it back to the pressure component to maintain the force constant.

[0062] Before the experiment begins, it is necessary to inject nitrogen into the test box 1 to replace the air inside, because nitrogen is an inert gas and will not react with the coal sample and pyrolysis products. During the experiment, as the temperature in the chamber gradually increases, the oil-rich coal undergoes pyrolysis, and gaseous oil and gas products will be produced. In order to collect the oil and gas products and calculate the oil and gas yield, nitrogen is continuously injected into the test box 1 through the nitrogen supply system. The nitrogen can quickly and fully take out the products during the discharge of the test box 1, and cool and collect them outside the test box 1. If nitrogen is not injected and the pyrolysis products are simply discharged by themselves, some of the products will remain in the chamber after the experiment, resulting in errors in the experimental results. The injected nitrogen is heated by the electric heating tube 16, and the temperature of the injected nitrogen is recorded in real time by the second temperature sensor 23, and the temperature in the test box 1 is recorded in real time by the first temperature sensor 22. The heating components are controlled by the control module 28 so that the temperature of the injected nitrogen is always consistent with the temperature in the test box 1, thereby not affecting the temperature in the test box.

[0063] Specifically, the testing method provided by the present invention comprises the following steps:

[0064] Step 1: Prepare the oil-rich coal into a test sample 4 or a cylinder with a side length of a cube.

[0065] Step 2: Set the first electrode plate 3 on the insulating pad 7 in the limiting groove 201, and set the second electrode plate 5 on the bottom of the top plate 9 of the lifting assembly through the fixing clamp 10.

[0066] Step 3: Place the prepared test sample 4 on the first electrode plate 3, adjust the telescopic rod 8 of the lifting assembly so that the second electrode plate 5 descends to the top of the test sample 4 and abuts against the upper surface of the test sample 4, and seal the test box 1.

[0067] Step 4: Start any one, two or three power mechanisms 11 to provide constant vertical and circumferential pressure for the test sample 4, so that the test sample 4 is in a uniaxial, biaxial or triaxial stress state.

[0068] Step 5: By controlling the heating power of the heating seat 2, the first temperature sensor 22 collects the temperature in the test box 1 in real time. When the temperature reaches the set value, the test box 1 is kept at a constant temperature. At the same time, the capacitance value C of the flat plate capacitor of the test sample 4 under pressure and heating is collected by the LCR tester 6. p And the resistance value R. In this embodiment, the highest test temperature in the test can reach 600°C.

[0069] Calculate the resistivity ρ through the resistance value R;

[0070]

[0071] Wherein, S is the cross-sectional area of ​​the test sample 4, and L is the height of the test sample 4.

[0072] Through the capacitance value C p And the resistivity ρ calculate the dielectric constant ε of test sample 4 r .

[0073] In this embodiment, the test sample 4 is a cube, and its dielectric constant ε r The calculation formula is:

[0074]

[0075] Where S is the cross-sectional area of ​​the test sample 4, L is the height of the test sample 4, and C p is the capacitance value of the flat plate capacitor obtained by testing, and ε0 is the dielectric constant of vacuum.

[0076] Step 6: Analyze the relationship between the heating temperature and the dielectric constant and the resistivity in combination with the temperature data collected by the first temperature sensor 2, and draw a relationship diagram between the heating temperature and the dielectric constant and between the heating temperature and the resistivity, as shown in the figure below: Figure 4 and Figure 5 As shown, generally when the pyrolysis temperature is lower than 400°C, the resistivity and dielectric constant change slightly. When the pyrolysis temperature exceeds 400°C, the resistivity and dielectric constant of oil-rich coal increase with temperature.

[0077] Furthermore, in this embodiment, during the test, nitrogen gas having the same temperature as that in the cavity is continuously introduced into the test box 1, with the purpose of bringing the pyrolysis products out of the test box 1 through the injected nitrogen gas, so as to be used for the later calculation of the pyrolysis tar yield; the specific implementation method is that the nitrogen bottle 13 provides nitrogen gas at room temperature, which is heated by a nitrogen heater so that the temperature of the nitrogen heater reaches the air temperature detected by the temperature sensor in the test box 1, thereby ensuring that the temperature injected into the test box 1 is consistent with the temperature in the cavity, and the injection of nitrogen does not affect the temperature in the test box 1.

[0078] In summary, the resistivity and dielectric constant testing device for pyrolysis of oil-rich coal provided in this embodiment can be used to perform the following tests:

[0079] (1) Only the pressure plate connected to the force-applying assembly in the vertical direction is in contact with the test sample, and the other two directions are not in contact. The relationship between the resistivity and dielectric constant of oil-rich coal and the temperature in the free state can be measured.

[0080] (2) During the test, a constant force is applied only in the vertical direction, so the relationship between the resistivity and dielectric constant of oil-rich coal and temperature under the uniaxial state can be tested.

[0081] (3) During the test, a constant force is applied to the three axes, so the relationship between the resistivity and dielectric constant of the oil-rich coal and the temperature under the three-axis state can be tested.

[0082] (4) Multiple groups of tests, with different forces applied in each group of tests, can test the relationship between the resistivity and dielectric constant of oil-rich coal and temperature under the same temperature and different pressure conditions.

[0083] The present invention can realize triaxial pressurization, the pyrolysis temperature can be increased to 600°C at different heating rates, nitrogen gas with the same temperature as that in the test chamber is injected to discharge the pyrolysis products, and the products are separated and collected.

[0084] The embodiments described above are only preferred specific implementation modes of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A device for testing resistivity and dielectric constant of oil-rich coal during pyrolysis, characterized in that: include: A test box (1), one side of which is connected to a nitrogen supply system, and the other side of which is connected to a pyrolysis product collection system; A heating seat (2) is arranged in the test box (1); A first electrode plate (3) is arranged on the heating seat (2), and a test sample (4) of oil-rich coal is placed on the first electrode plate (3); Three force-applying components, respectively arranged above the test box (1) and on two adjacent sides, for applying forces in different directions to the test sample (4); A lifting component is arranged between the heating seat (2) and the force-applying component at the top, a second electrode plate (5) is arranged on a side of the lifting component close to the first electrode plate (3), and the first electrode plate (3) and the second electrode plate (5) constitute a flat-plate capacitor; A parameter determination module (6) having a data acquisition end electrically connected to the first electrode plate (3) and the second electrode plate (5) for collecting the capacitance value C of the flat plate capacitor of the test sample (4) under pressure and heating p And resistance value R; The lifting assembly comprises telescopic rods (8) arranged on both sides of the heating seat (2); a top plate (9) is arranged on the top of the telescopic rods (8); an insulating pad (7) is arranged on the top of the top plate (9); and a fixing clamp (10) is arranged on the bottom; the second electrode plate (5) is clamped at the bottom of the top plate (9) by the fixing clamp (10); The nitrogen supply system comprises a nitrogen bottle (14) and a nitrogen heater; The nitrogen heater comprises a heating shell (15) and a support frame (32) arranged at the bottom of the heating shell (15); an electric heating tube (16) is arranged in the heating shell (15); a plurality of guide plates (17) are arranged in the heating shell (15) around the electric heating tube (16); and a nitrogen outlet (18) is arranged on the heating shell (15); the heating shell (15) is connected to the nitrogen bottle (14) through a vent pipe (19); the heating shell (15) is connected to one side of the test box (1) through an electric heating pipeline (20); a nitrogen control valve (21) is arranged on the electric heating pipeline (20); the injected nitrogen is mainly used to replace the air in the test box (1) before the test starts, and to bring out the oil and gas products generated by coal pyrolysis from the test box (1) during the test heating process; the temperature of the injected nitrogen is consistent with the temperature in the test box (1); A first temperature sensor (22) is arranged inside the test box (1), and a second temperature sensor (23) is arranged at the nitrogen outlet (18); Each of the force-applying components comprises a power mechanism (11) and a pressure plate (12) arranged at the power output end of the power mechanism (11); the pressure plate (12) is located in the test box (1) and faces the heating seat (2); a thin film pressure sensor (13) is arranged at the bottom of the pressure plate (12); It also includes a control module (28) and a plurality of control switches (29), wherein a signal input end of the control module (28) is connected to a first temperature sensor (22), a second temperature sensor (23) and three film pressure sensors (13), and a signal output end of the control module (28) is connected to the electric heating tube (16), a heating seat (2), a nitrogen control valve (21), an oil and gas control valve (27), three power mechanisms (11) and a plurality of control switches (29); The outer walls of the test box (1) and the heating shell (15) are respectively provided with a first thermal insulation layer (30) and a second thermal insulation layer (31), and the power mechanism (11) is a hydraulic cylinder.

2. The resistivity and dielectric constant testing device for pyrolysis of oil-rich coal according to claim 1, characterized in that: The heating seat (2) is provided with a limiting groove (201), an insulating pad (7) is arranged inside the limiting groove (201), the first electrode plate (3) is placed on the insulating pad (7), and the cross-sectional area of ​​the test sample (4) is the same as the shape and cross-sectional area of ​​the first electrode plate (3) and the second electrode plate (5).

3. The resistivity and dielectric constant testing device during pyrolysis of oil-rich coal according to claim 1, characterized in that: The pyrolysis product collection system comprises an oil and gas absorption chamber (24) and a secondary absorption chamber (25); the oil and gas absorption chamber (24) is connected to the other side of the test box (1) via an oil and gas air guide pipe (26); the oil and gas absorption chamber (24) is connected to the secondary absorption chamber (25) via a pipeline (33); an oil and gas absorption solvent is provided in both the oil and gas absorption chamber (24) and the secondary absorption chamber (25); and an oil and gas control valve (27) is provided on the oil and gas air guide pipe (26).

4. The resistivity and dielectric constant testing device for pyrolysis of oil-rich coal according to claim 1, characterized in that: The heating seat (2) is an electric heating plate, and the longitudinal section of the heating seat (2) is L-shaped.

5. A testing method using the resistivity and dielectric constant testing device during pyrolysis of oil-rich coal as claimed in claim 4, characterized in that: The following steps are involved: The first electrode plate (3) is arranged on the insulating pad (7) in the limiting groove (201), and the second electrode plate (5) is arranged on the bottom of the top plate (9) of the lifting assembly by means of a fixing clamp (10); Placing the prepared test sample (4) on the first electrode plate (3), and adjusting the telescopic rod (8) of the lifting assembly so that the second electrode plate (5) descends to the top of the test sample (4) and abuts against the upper surface of the test sample (4); Starting any power mechanism (11) to provide constant vertical and circumferential pressure to the test sample (4), so that the test sample (4) is in a uniaxial, biaxial or triaxial stress state; By controlling the heating power of the heating seat (2), the first temperature sensor (22) collects the temperature in the test box (1) in real time. When the temperature reaches a set value, the test box (1) is kept at a constant temperature. At the same time, the capacitance value C of the flat plate capacitor of the test sample (4) under pressure and heating is collected through the parameter measurement module (6). p And resistance value R; Calculate the resistivity ρ through the resistance value R; Through the capacitance value C p And resistivity C p Calculate the dielectric constant ε of the test sample (4) r ; In combination with the temperature data collected by the first temperature sensor (22), the relationship between the heating temperature and the dielectric constant and the resistivity is analyzed, and a relationship diagram between the heating temperature and the dielectric constant and between the heating temperature and the resistivity is drawn.

6. The method for testing resistivity and dielectric constant of oil-rich coal during pyrolysis according to claim 5, characterized in that: The test sample (4) is a cube, and the calculation formula of its dielectric constant εr is: Where S is the cross-sectional area of ​​the test sample (4), L is the height of the test sample (4), and C p is the capacitance value of the flat plate capacitor obtained by testing, and ε0 is the dielectric constant of vacuum.

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