A device and method for measuring radial strain and microdeformation in oil-rich coal pyrolysis

Abstract

The present application relates to a kind of radial strain and micro-deformation measuring device and method of oil-rich coal pyrolysis, the device includes pressure chamber, inner cavity is equipped with pressure chamber inner cylinder;Gas confining chamber is formed between the outer wall of pressure chamber inner cylinder and the inner wall of pressure chamber;Annular heating jacket, sleeve is set in the outside of pressure chamber;Displacement measurement structure is arranged in annular heating jacket one side, each displacement measurement structure corresponds one convex structure respectively, and with corresponding convex structure is connected;Stress exerting structure is arranged in the lower end of annular heating jacket other side, and is connected with gas confining chamber;Temperature sensor is connected with gas confining chamber;Axial load loading mechanism is located above pressure chamber.This application can conveniently measure the radial strain of coal rock under the condition of high temperature and loading triaxial stress, while monitoring the radial micro-deformation of coal rock, solve the difficult problem that radial deformation is difficult to measure in the stress loading process of coal rock under high temperature condition.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology for oil-rich coal pyrolysis, and particularly relates to a device and method for measuring radial strain and micro-deformation in oil-rich coal pyrolysis. Background Technology

[0002] In-situ pyrolysis of oil-rich coal is of great significance for the green and efficient utilization of coal. The mechanical properties of coal seams and surrounding rocks under high-temperature conditions serve as the foundation for in-situ development practices. Accurate testing of parameters such as compressive strength, elastic modulus, and Poisson's ratio is crucial to ensuring the smooth progress of in-situ pyrolysis of oil-rich coal. Currently, the technology for testing the axial strain of coal and rock under high-temperature conditions is relatively mature, but the testing of radial strain is still imperfect. Conventional ring-shaped testing devices fail at high temperatures. Therefore, a more convenient and feasible method is needed to test the radial strain of coal and rock under high-temperature conditions. Furthermore, even without significant deformation during stress loading, micro-deformation in the radial direction can still affect the mechanical strength of coal and rock. Therefore, proposing a device capable of accurately measuring the radial strain and micro-deformation of coal and rock under high-temperature conditions is of great significance for ensuring the support strength and safety of coal and rock in the in-situ development of oil-rich coal. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a device and method for measuring radial strain and micro-deformation in oil-rich coal pyrolysis. This device can conveniently measure the radial strain of coal and rock under high temperature and triaxial stress conditions, while simultaneously monitoring the radial micro-deformation of coal and rock, thus solving the problem of difficulty in measuring radial deformation of coal and rock during stress loading under high temperature conditions.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: A device for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal, the device comprising: The pressure chamber has an inner cylinder inside its cavity, which is used to hold the coal and rock sample to be measured. A gas-filled pressure chamber is formed between the outer wall of the inner cylinder and the inner wall of the pressure chamber. One side of the inner cylinder has a protruding structure extending outward, and there are multiple protruding structures arranged in an upper and lower spaced manner. An annular heating sleeve is fitted on the outside of the pressure chamber to uniformly heat the gas in the gas-enclosed pressure chamber and the coal and rock samples in the cylinder of the pressure chamber, so as to avoid measurement errors caused by local overheating or temperature gradient. The displacement measuring structure is located on one side of the annular heating sleeve, and the number of the displacement measuring structures is the same as the number of the protruding structures. Each displacement measuring structure corresponds to one protruding structure and is connected to the corresponding protruding structure, and is used to monitor the change of radial displacement of the coal and rock sample in real time. A stress-applying structure is provided at the lower end of the other side of the annular heating jacket and is connected to the gas pressure chamber. It is used to control the pressure of the gas supplied by the gas pressure source to the gas pressure chamber, thereby forming a controllable triaxial stress environment in the gas pressure chamber and accurately monitoring the radial displacement of the coal and rock sample. A temperature sensor, which is connected to the gas pressure chamber, is used to detect the actual pressure value inside the gas pressure chamber and feed it back to the control system of the measuring device; An axial load loading mechanism is located above the pressure chamber and can move vertically downwards, contacting the coal and rock sample in the inner cylinder of the pressure chamber and applying an axial load force.

[0005] Preferably, the displacement measuring structure includes a heat-resistant stainless steel shell, and from right to left, a heat-insulating protective inner shell, a spring, and an iron core extending out of the heat-resistant stainless steel shell are connected inside the heat-resistant stainless steel shell. A micro-conical probe is connected to the end of the iron core, and the micro-conical probe extends into the protruding structure of the annular heating jacket. The heat-insulating protective inner shell contains, from right to left, an electronic circuit board and a displacement sensor coil.

[0006] Preferably, the outer surface of the end of the heat-resistant stainless steel shell equipped with the micro-deformed conical probe is provided with a threaded structure, which allows the displacement measuring structure to be conveniently installed on the outside of the pressure chamber.

[0007] Preferably, the stress application structure includes a constant pressure air pump, the output end of which is connected to the gas confining chamber through a gas pipeline, and the input end is connected to a drive structure. The constant pressure air pump is equipped with a high-strength plunger inside.

[0008] Preferably, the drive structure includes a stepper motor, the output end of which is connected to a transmission gear, a transmission shaft is connected to the transmission gear, the transmission shaft extends into the constant pressure air pump, and is connected to the high-strength plunger.

[0009] Preferably, the gas pipeline is equipped with a pressure sensor to detect the actual pressure value in the gas confining chamber and feed it back to the control system of the measuring device.

[0010] Preferably, the constant pressure air pump is equipped with an electrically controlled air valve to control the pressure of the gas delivered by the constant pressure air pump to the gas confining chamber.

[0011] Preferably, the drive shaft is equipped with a grating ruler for monitoring changes in gas volume within the constant pressure air pump.

[0012] A method for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis using a measuring device, the method comprising the following steps: Step 1, Sample Calibration, includes the following steps: S11. Place the alloy calibration sample of the specified size into the high temperature and pressure chamber cylinder, and apply a certain axial load through the axial load loading mechanism to press the alloy calibration sample tightly. S12. Set a certain confining pressure value through the control system, then turn on the constant pressure air pump to make the pressure of the gas confining chamber reach the preset value; turn on the annular heating jacket switch to make the temperature rise at a certain fixed rate until it reaches 700℃. S13. As the gas state in the gas confining chamber changes during the heating process, in order to maintain a constant preset confining pressure value, the high-strength plunger will automatically compress or stretch. At this time, the scale of the grating ruler during the heating process is recorded, and finally a curve of gas volume change caused by the temperature change from room temperature to 700℃ is obtained. S14. Calculate the volume change of the heated gas ΔV0 using the formula: = Cross-sectional area of ​​the constant pressure pump cavity S The displacement distance l of the grating ruler is recorded as a curve of the gas volume of the alloy calibration sample changing with temperature; Step 2, radial strain test, includes the following steps: S21. After the alloy calibration sample is calibrated, remove the axial pressure and confining pressure, wait for it to cool down, take it out, and then put it into a coal and rock sample of the same size for testing. S22. After applying a certain axial load through the axial load loading mechanism to compress the coal and rock sample, start the constant pressure air pump to apply confining pressure. The gas enters through the gas pipeline and is compressed into the gas confining pressure chamber by the high-strength plunger controlled by the high-precision stepper motor. After reaching the set pressure value, the stepper motor and the high-strength plunger stop running. During this process, the gas pressurization is completed by the control system controlling the opening and closing of the electronically controlled air valve. S23. After reaching the preset pressure value, turn on the annular heating jacket to heat up to the preset temperature at the constant rate used when calibrating the sample. S24. After the temperature of the gas confining chamber stabilizes, axial load is applied to keep the confining pressure constant. After the coal and rock sample undergoes axial deformation, it begins to deform radially, causing the gas volume in the gas confining chamber to change. In order to maintain a constant confining pressure, the control system drives the stepper motor to move the high-strength plunger until the pressure sensor reading returns to the preset value. S25. During the continuous application of axial stress, record the axial deformation of the coal and rock sample. Simultaneously, detect the gas volume change in the gas confining chamber using a grating ruler. Calculate the volume change of the heated gas, ΔV0, using the formula: ΔV0 = (Cross-sectional area S of the constant pressure gas pump chamber). The displacement distance l of the grating ruler is recorded as a curve of the gas volume of the coal and rock sample changing with temperature, and the radial deformation of the coal and rock sample is calculated. S26. Subtract the curve of the gas volume of the alloy calibration sample from the curve of the gas volume of the coal and rock sample changing with temperature to eliminate the gas volume change caused by the temperature effect and estimate the amount of gas volume change caused by the stress deformation of the coal and rock sample. Step 3, Micro-deformation test, including the following steps: S31. The radial micro-deformation of the sample is monitored by displacement measurement structure. Before the test, the pressure inner cylinder of the gas confining chamber is modified. A small cylindrical external protrusion structure is set in the upper, middle and lower parts respectively. The size is slightly larger than the micro-deformation cone probe. A hole smaller than the size of the micro-deformation cone probe is preset on the cylindrical external protrusion structure. S32. After placing the coal and rock sample into the pressure chamber cylinder, insert the micro-conical probe into the preset hole so that the micro-conical probe can be precisely locked inside the cylindrical external protrusion structure, and the top of the cylindrical external protrusion structure is in contact with the side of the coal and rock sample. S33. Screw the heat-resistant stainless steel shell of the displacement measuring structure onto the outer wall of the pressure chamber according to the thread, and tighten it to ensure that there is no air leakage inside the pressure chamber. S34. During the application of axial load, the upper, middle and lower positions of the coal and rock sample undergo radial micro-deformation of different degrees, which drives the micro-deformation conical probe to extend and retract and converts the displacement into an electrical signal through the displacement sensor coil and electronic circuit board and transmits it to the control system. Finally, the curves of the micro-deformation of the sample at different positions with axial load are obtained, thus completing the monitoring of radial micro-deformation of the coal and rock sample.

[0013] Preferably, in step 3, when the gas pressure in the gas confining chamber increases, it compresses the highly ductile cylindrical protruding structure, tightly wrapping the micro-deformation conical probe into a single unit, enabling higher precision monitoring of radial deformation.

[0014] The technical effects and advantages of this invention are as follows: 1. This application, by employing a high-precision displacement measurement structure and combining it with precise temperature and pressure control, enables accurate measurement of the deformation characteristics of coal and rock materials under complex high-temperature and high-pressure environments.

[0015] 2. This application not only improves the accuracy and stability of the measurement, but also, through the multi-point distributed displacement measurement structure and the micro-deformation conical probe design, can capture the deformation details of coal and rock materials at the micro level more meticulously. This is of great significance for in-depth research on the mechanical properties of coal and rock and for predicting geological disasters in coal mining.

[0016] 3. The application proposes to calculate the volume change of the gas confining chamber by measuring the volume change of the gas in the constant pressure gas pump while maintaining a constant gas pressure. Then, it uses a grating ruler to measure the high-intensity piston movement of the constant pressure gas pump to monitor the radial strain of coal and rock under triaxial pressure. A cylindrical protrusion structure is preset on the inner cylinder of the pressure chamber of the gas confining chamber, and it is tightly wrapped around the micro-deformation conical probe by applying gas confining pressure. This ensures that the micro-deformation conical probe is in close contact with the sample and moves with the deformation of the inner cylinder of the copper pressure chamber, thereby improving the accuracy of micro-deformation monitoring.

[0017] 4. The high temperature and high pressure resistance of the device in this application enable it to effectively test the thermal deformation in the oil and gas production environment of in-situ pyrolysis of oil-rich coal, providing strong technical support for optimizing the in-situ pyrolysis process and ensuring the safety of the in-situ pyrolysis process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the displacement measurement structure of the present invention.

[0019] Explanation of reference numerals in the attached drawings: 1—Axial load loading mechanism; 2—Coal and rock sample; 3—Gas confining chamber; 4—Annular heating jacket; 5—Inner cylinder of pressure chamber; 6—Pressure chamber; 7—Temperature sensor; 8—Pressure sensor; 9—Constant pressure air pump; 10—High-strength plunger; 11—Drive shaft; 12—Drive gear; 13—Stepper motor; 14—Grating ruler; 15—Electrically controlled ventilation valve; 16—Upper sensor; 17—Middle sensor; 18—Lower sensor; 19—Micro-deformation conical probe; 20—Spring; 21—Displacement sensor coil; 22—Electronic circuit board; 23—Thread; 24—Iron core; 25—Heat-insulated protective inner shell; 26—Heat-resistant stainless steel outer shell. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments given in the accompanying drawings.

[0021] See Figures 1-2 As shown, a device for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal includes: Pressure chamber 6, with an inner cylinder 5 inside the cavity of pressure chamber 6, is used to hold the coal and rock sample 2 to be measured and the standard sample 2, which is usually made of low thermal expansion alloy material; a gas-enclosed pressure chamber 3 is formed between the outer wall of the inner cylinder 5 and the inner wall of pressure chamber 6; one side of the inner cylinder 5 is provided with a protruding structure extending outward, and there are multiple protruding structures arranged in an upper and lower spaced structure.

[0022] In one embodiment, the protruding structure is a cylindrical protrusion. This design not only positions the micro-deformation conical probe 19 but also allows it to closely engage with the probe under gas pressure, improving the accuracy of micro-deformation monitoring. Under gas pressure, the cylindrical protrusion forms an integral part with the micro-deformation conical probe 19, jointly participating in the deformation process of the coal and rock sample 2. This technology ensures close contact between the deformation conical probe 19 and the coal and rock sample 2, improving the sensitivity and accuracy of radial micro-deformation measurement.

[0023] The annular heating sleeve 4 is sleeved on the outside of the pressure chamber 6 and is used to uniformly heat the gas in the gas confining chamber 3 and the coal and rock sample 2 in the inner cylinder 5 of the pressure chamber, so as to avoid measurement errors caused by local overheating or temperature gradient. In this embodiment, the annular heating jacket 4 converts electrical energy into heat energy through resistance heating, distributing it evenly across the outer wall of the entire gas-confined chamber 3. This ensures the uniformity of the temperature field and avoids measurement errors caused by local overheating or temperature gradients. The technology in this embodiment enables uniform heating of coal and rock samples under high-temperature conditions, creating an ideal temperature environment for radial strain measurement.

[0024] The displacement measuring structure is set on one side of the annular heating sleeve 4, and the number of the displacement measuring structures is the same as the number of the protruding structures. Each displacement measuring structure corresponds to one protruding structure and is connected to the corresponding protruding structure, and is used to monitor the change of radial displacement of the coal and rock sample 2 in real time.

[0025] In one embodiment, as shown in the figure, the displacement measurement structure consists of three miniature deformation sensors, corresponding to the coal and rock samples 2 within the protruding structures at the upper, middle, and lower positions. By placing these micro-deformation sensors at different locations on the coal and rock samples 2, the radial micro-deformation distribution of the coal and rock under high temperature and loaded stress conditions can be comprehensively monitored. The micro-deformation sensors at different locations can independently collect data, and through comparative analysis, the non-uniformity of coal and rock deformation can be revealed. This technology can provide radial micro-deformation information for the coal and rock samples 2, providing more comprehensive data support for assessing the mechanical stability of coal and rock under high temperature and loaded stress conditions.

[0026] A stress-applying structure is provided at the lower end of the other side of the annular heating jacket 4 and is connected to the gas confining chamber 3. It is used to control the pressure of the gas supplied by the gas pressure source to the gas confining chamber 3, thereby forming a controllable triaxial stress environment in the gas confining chamber 3 and accurately monitoring the radial displacement of the coal and rock sample 2. Temperature sensor 7 is connected to gas pressure chamber 3 and is used to detect the actual pressure value inside gas pressure chamber 3 and feed it back to the control system of the measuring device. An axial load loading mechanism 1 is located above the pressure chamber 6 and can move vertically downwards, contacting the coal and rock sample 2 in the inner cylinder 5 of the pressure chamber and applying an axial load force.

[0027] It should be noted that this embodiment employs a closed-loop control system. Through real-time monitoring and adjustment, precise control of pressure and temperature is ensured during the measurement process, improving the accuracy and reliability of the measurement. The closed-loop control is based on a feedback mechanism, collecting data through pressure sensor 8 and temperature sensor 7 and applying stress to the structure in a timely manner to maintain the set triaxial stress conditions. The technology in this embodiment enables precise measurement of the radial strain of coal and rock under high temperature and triaxial stress conditions, providing crucial data support for the mechanical analysis of in-situ pyrolysis of oil-rich coal.

[0028] In one embodiment, the displacement measuring structure includes a heat-resistant stainless steel housing 26. From right to left, a heat-insulating protective inner shell 25, a spring 20, and an iron core 24 extending outside the heat-resistant stainless steel housing 26 are sequentially connected inside the heat-resistant stainless steel housing 26. A micro-conical probe 19 is connected to the end of the iron core 24, and the micro-conical probe 19 extends into the protruding structure of the annular heating sleeve 4. From right to left, an electronic circuit board 22 and a displacement sensor coil 21 are sequentially connected inside the heat-insulating protective inner shell 25. The outer surface of the end of the heat-resistant stainless steel housing 26 where the micro-conical probe 19 is mounted has a threaded structure, which allows the displacement measuring structure to be easily installed outside the pressure chamber 6.

[0029] It should be noted that the micro-deformation conical probe 19 is made of cemented carbide, which has high hardness and good heat resistance, making it suitable for radial micro-deformation monitoring in high-temperature environments. The cemented carbide probe can withstand high temperatures and high pressures while maintaining its shape and performance stability. This technology ensures that the micro-deformation conical probe 19 maintains good contact under high temperatures and applied stress, improving the reliability and accuracy of micro-deformation measurements.

[0030] The micro-deformation conical probe 19, designed with a conical shape, can better embed itself into the sample surface, reducing slippage errors during measurement. The smaller contact area between the conical probe and the sample surface allows for more sensitive detection of minute displacement changes in the sample. This technology improves the accuracy and reliability of micro-deformation measurements, providing more accurate data for studying the mechanical behavior of coal and rock under high temperature and loaded stress conditions.

[0031] In this embodiment, the micro-deformation conical probe 19 is positioned by a cylindrical protrusion structure pre-set on the inner copper wall of the triaxial pressure chamber cylinder 5. The positional relationship between the cylindrical protrusion structure and the displacement measurement structure ensures that the micro-deformation conical probe 19 can accurately measure the micro-deformation of the coal and rock sample 2, realizing radial micro-deformation monitoring under high temperature conditions, which is difficult to achieve with traditional measurement techniques.

[0032] Furthermore, the direct contact between the tip of the micro-deformation conical probe 19 and the side of the coal sample 2 minimizes measurement errors and improves the sensitivity of micro-deformation measurements. Direct contact reduces displacement transmission errors in intermediate stages, allowing the coal sample 2 to more accurately reflect its true displacement changes. This high-precision monitoring of the radial micro-deformation of sample 2 provides crucial data for evaluating the mechanical properties of coal under high temperature and loaded stress conditions.

[0033] The coordinated deformation of the micro-deformation conical probe 19 and the inner copper wall of the pressure chamber cylinder 5 can more accurately reflect the radial micro-deformation of the coal sample 2, improving the accuracy and reliability of the measurement. The deformation of the inner copper wall can drive the synchronous displacement of the micro-deformation conical probe 19, and this displacement change is directly related to the radial micro-deformation of the coal sample 2. This technique can capture the subtle deformation of the coal sample 2 under high temperature and loaded stress conditions, providing strong support for the study of the micromechanical properties of coal.

[0034] In one embodiment, the stress application structure includes a constant pressure air pump 9, the output end of which is connected to the gas confining chamber 3 through a gas pipeline, and the input end is connected to a drive structure. The constant pressure air pump 9 is equipped with a high-strength plunger 10 inside.

[0035] In one embodiment, the drive structure includes a stepper motor 13, the output end of which is connected to a transmission gear 12, and a transmission shaft 11 is connected to the transmission gear 12. The transmission shaft 11 extends into the constant pressure air pump 9 and is connected to the high-strength plunger 10.

[0036] In one embodiment, the drive shaft 11 is provided with a grating ruler 14 for monitoring the gas volume change inside the constant pressure air pump 9.

[0037] It should be noted that this application utilizes a high-precision stepper motor 13 in conjunction with a grating ruler 14 to precisely control and monitor the radial displacement changes of the coal and rock sample 2. The high-precision stepper motor 13 drives the movement of the high-strength piston 10 via a drive shaft 11 and a drive gear 12. This mechanical structure design ensures precise control of the radial displacement. The grating ruler 14 is used to monitor the displacement changes of the piston 10, thereby calculating the volume change of the confining chamber 3. This configuration enables more accurate measurement of the radial strain of coal and rock materials under high temperature and multiaxial stress conditions.

[0038] In this embodiment, the stepper motor 13 is a high-precision stepper motor. High-precision stepper motors possess excellent control accuracy and stability, enabling precise control of the piston's movement and thus achieving accurate control of the sample's radial displacement. The stepper motor 13 controls its rotation angle by receiving pulse signals, thereby achieving precise displacement control. This technology ensures the controllability and accuracy of the sample's radial displacement during loading, providing strong support for studying the mechanical behavior of coal and rock under high temperature and triaxial stress.

[0039] In one embodiment, a pressure sensor 8 is provided on the gas pipeline to detect the actual pressure value inside the gas confining chamber 3 and feed it back to the control system of the measuring device.

[0040] In one embodiment, the constant pressure air pump 9 is equipped with an electrically controlled air valve 15, which is used to control the pressure of the gas delivered by the constant pressure air pump 9 to the gas confining chamber 3.

[0041] In this embodiment, the electrically controlled vent valve 15 automatically opens and closes according to the control system commands via electromagnetic drive, controlling the flow of gas and achieving automated operation, thus improving the safety and convenience of the experiment. This technology simplifies the experimental operation process, reduces the impact of human factors on the experimental results, and ensures the repeatability and consistency of the experiment.

[0042] The working process for this application is as follows: First, the low thermal expansion alloy calibration sample is placed in the high-temperature triaxial pressure chamber cylinder 5. Axial load and confining pressure are applied through a closed-loop control system. The gas volume change is monitored using a constant pressure air pump 9 and a grating ruler 14 to complete the calibration of the gas volume change curve caused by temperature change. Then, the load is removed, the alloy calibration sample is cooled, and removed. Next, the coal and rock sample 2 is placed back in for testing, and axial load and confining pressure are applied again. The gas volume change is monitored using the grating ruler 14 to calculate the radial strain of the coal and rock sample 2. Simultaneously, a micro-deformation conical probe 19, positioned by a cylindrical protrusion on the inner copper wall of the triaxial pressure chamber cylinder 5, monitors the radial micro-deformation of the coal and rock sample 2 at the upper, middle, and lower positions. The displacement is converted into an electrical signal, ultimately obtaining the micro-deformation curve as a function of axial load. The entire process is conducted under high temperature and triaxial stress conditions. The closed-loop control system ensures precise control of pressure and temperature, while the design of the micro-deformation probe improves the accuracy and reliability of micro-deformation measurement.

[0043] A method for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis using a measuring device, the method comprising the following steps: Step 1, Sample Calibration, includes the following steps: S11. Place the alloy calibration sample of the specified size into the high temperature and pressure chamber cylinder 5, and apply a certain axial load through the axial load loading mechanism 1 to press the alloy calibration sample tightly. S12. Through the control system, a certain confining pressure value is set, and then the constant pressure air pump 9 is turned on to make the pressure of the gas confining pressure chamber 3 reach the preset value; the switch of the annular heating jacket 4 is turned on to make the temperature rise at a certain fixed rate until it reaches 700℃. S13. Since the gas state in the gas confining chamber 3 will change during the heating process, in order to maintain a constant preset confining pressure value, the high-strength plunger 10 will automatically compress or stretch. At this time, the scale of the grating ruler 14 during the heating process is recorded, and finally a curve of gas volume change caused by temperature change from room temperature to 700℃ is obtained. S14. Calculate the volume change of the heated gas ΔV0 using the formula: = Cross-sectional area of ​​the constant pressure pump cavity S The displacement distance l of the grating ruler is recorded as a curve of the gas volume of the alloy calibration sample changing with temperature; Step 2, radial strain test, includes the following steps: S21. After the alloy calibration sample is calibrated, remove the axial pressure and confining pressure, wait for it to cool down, take it out, and then put it into the coal and rock sample 2 of the same size for testing. S22. After applying a certain axial load through the axial load loading mechanism 1 to compress the coal and rock sample 2, the constant pressure air pump 9 is started to apply confining pressure. The gas enters through the gas pipeline and the high-strength plunger 10 is controlled by the high-precision stepper motor 13 to compress the gas into the gas confining pressure chamber 3. After reaching the set pressure value, the stepper motor 13 and the high-strength plunger 10 stop running. During this process, the control system controls the opening and closing of the electric control ventilation valve 15 to complete the gas pressurization. S23. After reaching the preset pressure value, turn on the annular heating jacket 4 to heat up to the preset temperature at the constant rate used when calibrating the sample. S24. After the temperature of the gas confining chamber 3 stabilizes, axial load is applied to keep the confining pressure constant. After the coal and rock sample 2 undergoes axial deformation, it begins to deform radially, causing the gas volume in the gas confining chamber 3 to change. In order to maintain a constant confining pressure, the control system drives the stepper motor 13 to move the high-strength plunger 10 until the reading of the pressure sensor 8 returns to the preset value. S25. During the continuous application of axial stress, record the axial deformation of coal and rock sample 2. Simultaneously, detect the gas volume change in gas confining chamber 3 using grating ruler 14. Calculate the gas volume change ΔV0 during heating using the formula: ΔV0 = (Cross-sectional area S of constant pressure pump chamber) / (Cross-sectional area S of constant pressure pump chamber). The displacement distance l of the grating ruler is recorded as a curve of the gas volume of the coal and rock sample changing with temperature, and the radial deformation of coal and rock sample 2 is calculated. S26. Subtract the curve of the gas volume of the alloy calibration sample from the curve of the gas volume of the coal and rock sample changing with temperature to eliminate the gas volume change caused by the temperature effect and estimate the amount of gas volume change caused by the stress deformation of coal and rock sample 2. For example, suppose coal and rock sample 2 is a cylindrical sample with a diameter of d0 and a height of h0, and the initial sample volume V0 = (d0 / 2). 2 ·π·h0; The axial deformation Δh of the sample after stress loading, the diameter d1 of the sample, and the volume of the sample after stress loading V1=(d1 / 2) 2 ·π·(h0-Δh); The volume occupied during the axial loading process is V2 = (d0 / 2). 2 ·π·Δh; it can be concluded that the gas volume change due to radial deformation is ΔV=V1+V2-V0; After integration, we can obtain S. l=(d1 / 2) 2 ·π·(h0-Δh)+(d0 / 2) 2 ·π·Δh-(d0 / 2) 2 ·π·h0; d1 = Calculated ; Radial deformation Δd = d1 - d0; Radial strain ε = Δd / d0.

[0044] In the radial strain test, the calibrated constant-pressure air pump 9 and grating ruler 14 are used to test a coal and rock sample 2 of the same size. After the sample is compressed, the constant-pressure air pump 9 is pressurized by the electrically controlled air valve 15 until the set confining pressure is reached and then stops operating. Subsequently, the annular heater 4 raises the temperature to the preset value, and after the temperature stabilizes, axial stress loading begins. As the coal and rock sample 2 undergoes axial deformation, the resulting radial deformation causes a change in the gas volume within the confining chamber 3. To maintain a constant confining pressure, the stepper motor 13 drives the piston 10 to move until the reading of the pressure sensor 8 returns to the set value. During this process, the piston displacement change monitored by the grating ruler 14 is converted into a gas volume change, and the radial strain of the sample is further calculated. By subtracting the volume change curve of the calibrated sample, the temperature effect can be eliminated, and only the gas volume change after the sample is subjected to force can be calculated, thus obtaining a more accurate radial strain result.

[0045] Step 3, Micro-deformation test, including the following steps: S31. The radial micro-deformation of the sample is monitored by the displacement measurement structure. Before the test, the pressure inner cylinder 5 of the gas confining chamber 3 is modified. A small cylindrical external protrusion structure is set in the upper, middle and lower parts respectively. The size is slightly larger than the micro-deformation cone probe 19. An opening slightly smaller than the size of the micro-deformation cone probe 19 is preset on the cylindrical external protrusion structure. S32. After placing the coal and rock sample 2 into the pressure chamber cylinder 5, insert the micro-shaped variable cone probe 19 into the preset hole so that the micro-shaped variable cone probe 19 can be just stuck inside the cylindrical external protrusion structure, and the top of the cylindrical external protrusion structure can just contact the side of the coal and rock sample 2. S33. The heat-resistant stainless steel shell 26 of the displacement measurement structure is screwed onto the outer wall of the pressure chamber 6 according to the thread, and tightened to ensure that there is no air leakage inside the pressure chamber 6. When the gas pressure in the confining chamber 3 increases, it will compress the highly ductile copper cylindrical protrusion structure, tightly wrapping the micro-deformation conical probe 19 into one piece, which can monitor radial deformation with higher precision. S34. During the application of axial load, the upper, middle and lower positions of the coal and rock sample 2 undergo radial micro-deformation of different degrees, which drives the micro-deformation cone probe 19 to extend and retract and convert the displacement into an electrical signal through the displacement sensor coil 21 and the electronic circuit board 22 and transmit it to the control system. Finally, the curves of the micro-deformation of the sample at different positions with axial load are obtained, and the radial micro-deformation monitoring of the coal and rock sample 2 is completed.

[0046] In the micro-deformation test, the upper, middle, and lower positions of the sample are monitored by the upper sensor 16, the middle sensor 17, and the lower sensor 18, respectively. Each sensor includes a hard alloy micro-deformation conical probe 19, an iron core 24, a spring 20, a displacement sensor coil 21, an electronic circuit board 22, a heat-insulating protective inner shell 25, and a heat-resistant stainless steel outer shell 26. These high-precision displacement measurement structures are positioned by a cylindrical protrusion pre-set on the inner cylinder 5 of the pressure chamber, ensuring stable contact between the micro-deformation conical probe 19 and the coal and rock sample 2. With the application of axial load, small radial deformations occur at different parts of the sample. This deformation is converted into displacement by the expansion and contraction of the micro-deformation conical probe 19, and then converted into electrical signals by the displacement sensor coil 21 and the electronic circuit board 22. Finally, the computer collects, processes, and plots the curve of micro-deformation changing with axial load.

[0047] It is worth noting that the contact point between the micro-deformation sensor and the sample is located on the side of the sample. This is achieved by directly positioning the tip of the micro-deformation conical probe 19 in contact with the sample. This direct contact method reduces measurement errors and ensures data reliability. Furthermore, the deformability of the inner cylinder 5 of the pressure chamber and its close contact with the micro-deformation probe 19 ensure that even if the gas pressure chamber 3 itself deforms during the measurement process, it will not significantly affect the measurement results, thus maintaining the accuracy of the micro-deformation measurement.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method of measuring radial strain and micro deformation of oil-rich coal pyrolysis, which is measured by a radial strain and micro deformation measuring device for oil-rich coal pyrolysis, characterized by, The measuring device includes: Pressure chamber (6), the inner cavity of the pressure chamber (6) is provided with an inner cylinder (5), the inner cylinder (5) is used to hold the coal and rock sample (2) to be measured; a gas confining chamber (3) is formed between the outer wall of the inner cylinder (5) and the inner wall of the pressure chamber (6); a protruding structure extending outward is provided on one side of the inner cylinder (5), the number of the protruding structures is multiple, and they are arranged in an upper and lower spaced structure; The annular heating sleeve (4) is fitted on the outside of the pressure chamber (6) to uniformly heat the gas in the gas confining chamber (3) and the coal and rock sample (2) in the inner cylinder (5) of the pressure chamber, so as to avoid measurement errors caused by local overheating or temperature gradient. The displacement measuring structure is set on one side of the annular heating sleeve (4), and the number of the displacement measuring structures is the same as the number of the protruding structures. Each displacement measuring structure corresponds to a protruding structure and is connected to the corresponding protruding structure. It is used to monitor the change of radial displacement of the coal and rock sample (2) in real time. The displacement measuring structure includes a heat-resistant stainless steel shell (26), and from right to left connected inside the heat-resistant stainless steel shell (26) are a heat-insulating protective inner shell (25), a spring (20), and an iron core (24) extending outside the heat-resistant stainless steel shell (26). The end of the iron core (24) is connected to a micro-deformed conical probe (19), which extends into the protruding structure of the annular heating sleeve (4). From right to left inside the heat-insulating protective inner shell (25) are an electronic circuit board (22) and a displacement sensor coil (21). The stress application structure is set at the lower end of the other side of the annular heating jacket (4) and connected to the gas confining chamber (3). It is used to control the pressure of the gas pressure source supplying gas to the gas confining chamber (3), thereby forming a controllable triaxial stress environment in the gas confining chamber (3) and accurately monitoring the radial displacement of the coal and rock sample (2). The stress application structure includes a constant pressure air pump (9), the output end of which is connected to the gas confining chamber (3) through a gas pipeline, and the input end is connected to a drive structure, which includes a stepper motor (13), the output end of which is connected to a transmission gear (12), a transmission shaft (11) connected to the transmission gear (12), a grating ruler (14) on the transmission shaft (11), a high-strength plunger (10) inside the constant pressure air pump (9), and an electrically controlled air valve (15) on the constant pressure air pump (9); a pressure sensor (8) is provided on the gas pipeline. Temperature sensor (7), which is connected to the gas confining chamber (3), is used to detect the actual pressure value inside the gas confining chamber (3) and feed it back to the control system of the measuring device; An axial load loading mechanism (1) is located above the pressure chamber (6) and can move vertically downwards, and contact the coal and rock sample (2) in the inner cylinder (5) of the pressure chamber, and apply an axial load force. The measurement method includes the following steps: Step 1, Sample Calibration, includes the following steps: S11. Place the alloy calibration sample of the specified size into the high temperature pressure chamber cylinder (5), and apply a certain axial load through the axial load loading mechanism (1) to press the alloy calibration sample tightly. S12. Set a certain confining pressure value through the control system, and then turn on the constant pressure air pump (9) to make the pressure of the gas confining chamber (3) reach the preset value; turn on the switch of the annular heating jacket (4) to make the temperature rise at a certain fixed rate until it reaches 700℃. S13. Since the gas state in the gas confining chamber (3) will change during the heating process, in order to maintain a constant preset confining pressure value, the high-strength plunger (10) will automatically compress or stretch. At this time, the scale of the grating ruler (14) during the heating process is recorded, and finally a curve of gas volume change caused by temperature change from room temperature to 700℃ is obtained. S14. Calculate the change in gas volume ΔV0 by the formula: cross-sectional area of ​​constant pressure pump cavity S * grating ruler displacement distance l, and record it as a curve of gas volume change of alloy calibration sample with temperature. Step 2, radial strain test, includes the following steps: S21. After the alloy calibration sample is calibrated, remove the axial pressure and confining pressure, wait for it to cool down and take it out, and then put it into a coal and rock sample of the same size (2) for testing. S22. Apply a certain axial load through the axial load loading mechanism (1) to press the coal and rock sample (2) tightly. Then start the constant pressure gas pump (9) to apply confining pressure. The gas enters through the gas pipeline. The high-strength plunger (10) is controlled by the high-precision stepper motor (13) to compress the gas into the gas confining chamber (3). After the set pressure value is reached, the stepper motor (13) and the high-strength plunger (10) stop running. During this process, the gas pressurization is completed by the control system controlling the opening and closing of the electric control ventilation valve (15). S23. After reaching the preset pressure value, turn on the annular heating jacket (4) to heat up to the preset temperature at the constant rate when calibrating the sample. S24. After the temperature of the gas confining chamber (3) stabilizes, axial load is applied to keep the confining pressure constant. After the coal and rock sample (2) undergoes axial deformation, radial deformation is initiated, causing the gas volume in the gas confining chamber (3) to change. In order to maintain a constant confining pressure, the stepper motor (13) is driven by the control system to move the high-strength plunger (10) until the reading of the pressure sensor (8) returns to the preset value. S25. During the process of continuously loading axial stress, the axial deformation of the coal and rock sample (2) is recorded. At the same time, the gas volume change of the gas confining chamber (3) is detected by the grating ruler (14). The gas volume change ΔV0 is calculated by the formula: constant pressure gas pump cavity cross-sectional area S * grating ruler displacement distance l. The curve of the gas volume of the coal and rock sample changing with temperature is recorded. The radial deformation of the coal and rock sample (2) is obtained by conversion. S26. Subtract the curve of the gas volume of the alloy calibration sample from the curve of the gas volume of the coal and rock sample changing with temperature to eliminate the gas volume change caused by the temperature effect and estimate the amount of gas volume change caused by the deformation of the coal and rock sample (2). Step 3, Micro-deformation test, including the following steps: S31. The radial micro-deformation of the sample is monitored by the displacement measurement structure. Before the test, the inner cylinder (5) of the pressure chamber of the gas confining chamber (3) is modified. A small cylindrical external protrusion structure is set in the upper, middle and lower parts respectively. The size is slightly larger than the micro-deformation cone probe (19). A hole smaller than the size of the micro-deformation cone probe (19) is preset on the cylindrical external protrusion structure. S32. After placing the coal and rock sample (2) into the pressure chamber cylinder (5), insert the micro-conical probe (19) into the preset hole so that the micro-conical probe (19) can be just stuck inside the cylindrical external protrusion structure and the top of the cylindrical external protrusion structure can contact the side of the coal and rock sample (2). S33. Screw the heat-resistant stainless steel shell (26) of the displacement measuring structure onto the outer wall of the pressure chamber (6) according to the thread, and tighten it to ensure that there is no air leakage inside the pressure chamber (6); S34. During the application of axial load, the upper, middle and lower positions of the coal and rock sample (2) undergo different degrees of radial micro-deformation, which drives the micro-deformation cone probe (19) to extend and retract and convert the displacement into an electrical signal through the displacement sensor coil (21) and electronic circuit board (22) and transmit it to the control system. Finally, the curves of the micro-deformation of the sample at different positions with the axial load are obtained, and the radial micro-deformation monitoring of the coal and rock sample (2) is completed.

2. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: The heat-resistant stainless steel shell (26) is equipped with a micro-deformed conical probe (19) with a thread (23) on the outer surface of one end, through which the displacement measuring structure is installed on the outside of the pressure chamber (6).

3. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: The drive shaft (11) extends into the constant pressure air pump (9) and is connected to the high-strength plunger (10).

4. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: The pressure sensor (8) is used to detect the actual pressure value inside the gas confining chamber (3) and feed it back to the control system of the measuring device.

5. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: The electrically controlled vent valve (15) is used to control the pressure of the gas delivered by the constant pressure gas pump (9) to the gas confining chamber (3).

6. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: The drive shaft (11) is equipped with a grating ruler (14) for monitoring the gas volume change inside the constant pressure air pump (9).

7. The method for measuring radial strain and micro-deformation in the pyrolysis of oil-rich coal according to claim 1, characterized in that: In step 3, when the gas pressure in the gas confining chamber (3) increases, it will compress the cylindrical outward protrusion structure with strong extensibility, tightly wrapping the micro-deformation conical probe (19) into one piece, which can monitor radial deformation with higher precision.

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