Device and method for measuring radial strain and micro-deformation of pyrolysis of oil-rich coal

Abstract

The invention relates to a device and a method for measuring radial strain and micro-deformation of pyrolysis of oil-rich coal. The device comprises a pressure chamber, and a pressure chamber inner cylinder is arranged in an inner cavity of the pressure chamber; a gas confining pressure chamber is formed between the outer wall of the pressure chamber inner cylinder and the inner wall of the pressure chamber; the annular heating sleeve sleeves the outer side of the pressure chamber; the displacement measuring structures are arranged on one side of the annular heating sleeve, and each displacement measuring structure corresponds to one protruding structure and is connected with the corresponding protruding structure; the stress applying structure is arranged at the lower end of the other side of the annular heating sleeve and is communicated with the gas confining pressure chamber; the temperature sensor is communicated with the gas confining pressure chamber; and the axial load loading mechanism is positioned above the pressure chamber. The radial strain capacity of the coal rock can be conveniently measured under the conditions of high temperature and triaxial stress loading, meanwhile, the radial micro-deformation of the coal rock is monitored, and the problem that the radial deformation is difficult to measure in the stress loading process of the coal rock under the high temperature condition is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil-rich coal pyrolysis measurement, and particularly relates to a radial strain and micro-deformation measurement device and method for oil-rich coal pyrolysis. BACKGROUND

[0002] In-situ pyrolysis of oil-rich coal is of great significance for green and efficient utilization of coal, and the mechanical properties of coal seams and surrounding rocks under high temperature conditions are the basis for in-situ development practices. Accurate testing of parameters such as compressive strength, elastic modulus and Poisson's ratio is the key to ensuring the smooth progress of in-situ pyrolysis of oil-rich coal. At present, the technical means for axial strain testing of coal and rock under high temperature conditions is relatively mature, while the radial strain testing of coal and rock is not perfect. The conventional ring-shaped testing device will fail under high temperature, so a more convenient and feasible method is needed to test the radial strain of coal and rock under high temperature conditions. At the same time, the micro-deformation in the radial direction of coal and rock during stress loading will also affect the mechanical strength without obvious deformation. Therefore, a device capable of accurately measuring the radial strain and micro-deformation of coal and rock under high temperature conditions is of great significance to the support strength and safety of coal and rock in the process of in-situ development of oil-rich coal. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a radial strain and micro-deformation measurement device and method for oil-rich coal pyrolysis, which can conveniently measure the radial strain of coal and rock under the conditions of high temperature and triaxial stress loading, and monitor the radial micro-deformation of coal and rock, solving the problem of difficulty in measuring radial deformation of coal and rock during stress loading under high temperature conditions.

[0004] In order to achieve the above purpose, the technical scheme of the present application is as follows: A radial strain and micro-deformation measurement device for oil-rich coal pyrolysis, comprising: A pressure chamber, a pressure chamber inner cylinder is arranged in the inner cavity of the pressure chamber, and the pressure chamber inner cylinder is used for accommodating a coal rock sample to be measured; a gas confining pressure chamber is formed between the outer wall of the pressure chamber inner cylinder and the inner wall of the pressure chamber; a protruding structure is arranged on one side of the pressure chamber inner cylinder and extends outward; the number of the protruding structures is multiple, and the protruding structures are arranged in an upper and lower interval structure; A ring-shaped heating sleeve is arranged outside the pressure chamber, and is used for uniformly heating the gas in the gas confining pressure chamber and the coal rock sample in the pressure chamber inner cylinder, so as to avoid measurement errors caused by local overheating or temperature gradient; A displacement measurement structure is arranged on one side of the ring-shaped heating sleeve, and the number of the displacement measurement structures is the same as that of the protruding structures. Each displacement measurement structure corresponds to one protruding structure, and is connected with the corresponding protruding structure, and is used for monitoring the change of the radial displacement of the coal rock sample in real time; A stress applying structure is arranged at the lower end of the other side of the annular heating sleeve and is connected with the gas confining chamber, and is used to control the pressure of the gas delivered by the gas pressure source to the gas confining chamber, so as to form a controllable tri-axial stress environment in the gas confining chamber, and accurately monitor the radial displacement of the coal rock sample; A temperature sensor is connected with the gas confining chamber, and is used to detect the actual pressure value in the gas confining chamber and feed back to the control system of the measuring device. An axial load loading mechanism is arranged above the pressure chamber, can move vertically downward, is in contact with the coal rock sample in the inner cylinder of the pressure chamber, and applies an axial load force.

[0005] Preferably, the displacement measuring structure comprises a heat-resistant stainless steel shell, a heat-insulating protective inner shell, a spring and a core extending outside the heat-resistant stainless steel shell are sequentially connected in the heat-resistant stainless steel shell from right to left, and an end of the core is connected with a micro-deformation conical probe which extends into the convex structure of the annular heating sleeve. The heat-insulating protective inner shell is sequentially connected with an electronic circuit board and a displacement sensor coil from right to left.

[0006] Preferably, the outer surface of the end of the heat-resistant stainless steel shell provided with the micro-deformation conical probe is provided with a threaded structure, so that the displacement measuring structure can be conveniently installed outside the pressure chamber through the threaded structure.

[0007] Preferably, the stress applying structure comprises a constant pressure gas pump, the output end of the constant pressure gas pump is connected with the gas confining chamber through a gas pipeline, the input end is connected with a driving structure, and the inside of the constant pressure gas pump is provided with a high-strength plunger.

[0008] Preferably, the driving structure comprises a stepping motor, the output end of the stepping motor is connected with a transmission gear, the transmission gear is connected with a transmission shaft, the transmission shaft extends into the constant pressure gas pump and is connected with the high-strength plunger.

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

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

[0011] Preferably, the transmission shaft is provided with a grating ruler, which is used to monitor the change of the gas volume in the constant pressure gas pump.

[0012] A measuring device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis and a method for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis by using the measuring device, the method comprises the following steps: Step 1, sample calibration, including the following steps: S11, the size of the alloy calibration sample is put into the high temperature pressure chamber, and a certain axial load is applied by the axial load loading mechanism to compress the alloy calibration sample; S12, set a certain confining pressure value by the control system, then open the constant pressure gas pump to make the pressure of the gas confining chamber reach the preset value; open the annular heating jacket switch to heat at a certain fixed rate until 700℃ is reached; S13, during the heating process, the state of the gas in the gas confining chamber will change, in order to maintain a constant preset confining pressure value, the high-strength plunger will automatically compress or stretch, at this time the grating scale scale during the heating process is recorded, and finally a curve of the change of the gas volume caused by the change of the temperature from room temperature to 700℃ is obtained; S14, the change of the volume of the heated gas is calculated by the formula ΔV0=S The grating scale displacement distance l is recorded as the curve of the change of the gas volume of the alloy calibration sample with temperature; Step 2, radial strain test, including the following steps: S21, after the alloy calibration sample completes the calibration, the axial pressure and confining pressure are removed, and after cooling, the coal rock sample of the same size is taken out and then put into the coal rock sample for testing; S22, after the coal rock sample is compressed by applying a certain axial load by the axial load loading mechanism, the constant pressure gas pump is started to apply confining pressure, the gas enters through the gas pipeline, and the high-precision stepping motor controls the high-strength plunger to compress the gas into the gas confining chamber, and after the set pressure value is reached, the stepping motor and the high-strength plunger stop running, and during this process, the opening and closing of the electric control air valve is controlled by the control system to complete the gas pressurization; S23, after reaching the preset pressure value, the annular heating jacket is opened to heat the sample at a constant rate to the preset temperature; S24, after the temperature of the gas confining chamber is stabilized, the axial load is applied, the confining pressure is kept unchanged, and the coal rock sample starts to deform radially after the axial deformation, so that the gas volume in the gas confining chamber changes, in order to maintain a constant confining pressure, the stepping motor is driven by the control system to move the high-strength plunger until the indicated value of the pressure sensor returns to the preset value; S25, during the process of continuously loading the axial stress, the axial deformation of the coal rock sample is recorded, and the change of the gas volume of the gas confining chamber is detected by the grating scale, and the change of the volume of the heated gas is calculated by the formula ΔV0=S The grating scale displacement distance l is recorded as the curve of the change of the gas volume of the coal rock sample with temperature, and the radial deformation of the coal rock sample is converted; S26, subtract the alloy calibration sample gas volume change with temperature curve from the coal rock sample gas volume change with temperature curve, so as to exclude the gas volume change caused by temperature effect, and calculate the gas volume change caused by the stress deformation of the coal rock sample; Step 3, micro-deformation test, comprising the following steps: S31, the radial micro-deformation of the sample is monitored by the displacement measurement structure, before the test, the pressure chamber inner cylinder of the gas confining pressure chamber is modified, a small cylindrical protruding structure is arranged at the upper, middle and lower parts respectively, the size is slightly larger than the micro-deformation cone-shaped probe, and a hole smaller than the size of the micro-deformation cone-shaped probe is preset on the cylindrical protruding structure; S32, after the coal rock sample is placed in the pressure chamber inner cylinder, the micro-deformation cone-shaped probe is installed in the preset hole, so that the micro-deformation cone-shaped probe can be just clamped inside the cylindrical protruding structure, and the top end of the cylindrical protruding structure is in contact with the side surface of the coal rock sample; S33, the heat-resistant stainless steel shell of the displacement measurement structure is screwed on the outer wall of the pressure chamber according to the thread, and the screwing ensures that the pressure chamber is not gas leakage; S34, during the process of applying axial load, the upper, middle and lower positions of the coal rock sample occur different degrees of radial micro-deformation, drive the micro-deformation cone-shaped probe to stretch and retract, and convert the displacement into an electrical signal through the displacement sensor coil and the electronic circuit board to the control system, finally obtain the micro-deformation change curve of different positions of the sample with the axial load, and complete the radial micro-deformation monitoring of the coal rock sample.

[0013] Preferably, in step 3, when the gas pressure of the gas confining pressure chamber is increased, the cylindrical protruding structure with strong ductility is compressed, and the micro-deformation cone-shaped probe is tightly wrapped into one, so that the radial deformation can be monitored with higher precision.

[0014] The technical effects and advantages of the present application are as follows: 1, by adopting the high-precision displacement measurement structure, combined with accurate temperature and pressure control, the accurate measurement of the deformation characteristics of coal rock materials in complex high temperature and high pressure environment can be realized.

[0015] 2, the present application not only improves the measurement accuracy and stability, but also through the multi-point distributed displacement measurement structure and the micro-deformation cone-shaped probe design, the deformation details of the coal rock materials in the microcosmic level can be captured more carefully, which has important significance for in-depth study of the mechanical properties of coal rock and prediction of geological disasters in coal mining.

[0016] 3, The application itself keeps the set gas pressure unchanged, calculates the cavity volume change of the gas confining chamber through the gas volume change in the constant pressure gas pump, monitors the radial strain of the coal rock under the three-axis pressurization condition by measuring the high-strength piston movement of the constant pressure gas pump with the grating ruler, and pre-sets a cylindrical protruding structure on the pressure chamber inner cylinder of the gas confining chamber, and tightly wraps the micro-deformation conical probe by loading the gas confining pressure, so that the micro-deformation conical probe is in close contact with the sample and moves with the deformation of the red copper pressure chamber inner cylinder, thereby improving the micro-deformation monitoring precision.

[0017] 4, The high temperature resistance and high pressure resistance of the device of the application can simulate the effective test of thermal deformation in the oil-rich coal in-situ pyrolysis oil and gas production environment, and provide strong technical support for optimizing the in-situ pyrolysis process and ensuring the safety of the in-situ pyrolysis process. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 is the overall structure schematic diagram of the application; Fig. 2 is the structure schematic diagram of the displacement measurement structure of the application.

[0019] Mark explanation: 1-axial load loading mechanism; 2-coal rock sample; 3-gas confining chamber; 4-ring type heating jacket; 5-pressure chamber inner cylinder; 6-pressure chamber; 7-temperature sensor; 8-pressure sensor; 9-constant pressure gas pump; 10-high-strength plunger; 11-transmission shaft; 12-transmission gear; 13-step motor; 14-grating ruler; 15-electric control breather 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 insulation protection inner shell; 26-heat-resistant stainless steel shell. DETAILED DESCRIPTION

[0020] The following embodiments combined with the drawings will further illustrate the application in detail.

[0021] Referring to Figs. 1-2 the drawing, a radial strain and micro-deformation measurement device for oil-rich coal pyrolysis, the device comprises: A pressure chamber 6, a pressure chamber inner cylinder 5 is arranged in the inner cavity of the pressure chamber 6, the pressure chamber inner cylinder 5 is used to accommodate the coal rock sample 2 to be measured, the standard sample 2 is usually a low thermal expansion alloy material; the gas confining chamber 3 is formed between the outer wall of the pressure chamber inner cylinder 5 and the inner wall of the pressure chamber 6; the pressure chamber inner cylinder 5 is provided with a protruding structure extending outward on one side, the number of the protruding structure is multiple, and the protruding structure is arranged in an up-down interval structure.

[0022] In one embodiment, the convex structure is a cylindrical convex structure. This design not only can position the micro-deformation cone-shaped probe 19, but also can tightly match the micro-deformation cone-shaped probe 19 when the gas confining pressure is loaded, thereby improving the accuracy of micro-deformation monitoring. Under the action of the gas pressure, the cylindrical convex structure will form an integral with the micro-deformation cone-shaped probe 19, and jointly participate in the deformation process of the coal rock sample 2. This technology can ensure the close contact between the deformation cone-shaped probe 19 and the coal rock sample 2, and improve the sensitivity and accuracy of the radial micro-deformation measurement.

[0023] The annular heating sleeve 4 is sleeved outside the pressure chamber 6, and is used for uniformly heating the gas in the gas confining pressure chamber 3 and the coal rock sample 2 in the pressure chamber inner cylinder 5, so as to avoid the measurement error caused by local overheating or temperature gradient. In this embodiment, the annular heating sleeve 4 converts the electric energy into heat energy through the resistance heating principle, and uniformly distributes the heat energy on the outer wall of the entire gas confining pressure chamber 3, so as to ensure the uniformity of the temperature field and avoid the measurement error caused by local overheating or temperature gradient. The technology in this embodiment can realize the uniform heating of the coal rock sample under high temperature conditions, and creates an ideal temperature environment for the measurement of the radial strain.

[0024] The displacement measurement structure is arranged on one side of the annular heating sleeve 4, and the number of the displacement measurement structures is the same as that of the convex structures. Each displacement measurement structure corresponds to one convex structure and is connected with the corresponding convex structure, and is used for monitoring the change of the radial displacement of the coal rock sample 2 in real time.

[0025] In one embodiment, as shown in the drawings, the displacement measurement structure is three micro-deformation sensors, which correspond to the coal rock samples 2 in the convex structures at the upper, middle and lower positions. By arranging the micro-deformation sensors at different positions of the coal rock sample 2, the radial micro-deformation distribution of the coal rock under the conditions of high temperature and loading stress can be comprehensively monitored. The micro-deformation sensors at different positions can independently collect data, and through comparison and analysis, the inhomogeneity of the deformation of the coal rock can be revealed. This technology can provide the radial micro-deformation information of the coal rock sample 2, and provide more comprehensive data support for evaluating the mechanical stability of the coal rock under the conditions of high temperature and loading stress.

[0026] The stress applying structure is arranged at the lower end of the other side of the annular heating sleeve 4, and is connected with the gas confining pressure chamber 3, and is used for controlling the pressure of the gas delivered by the gas pressure source to the gas confining pressure chamber 3, so as to form a controllable triaxial stress environment in the gas confining pressure chamber 3, and accurately monitor the radial displacement of the coal rock sample 2. The temperature sensor 7 is connected with the gas confining pressure chamber 3, and is used for detecting the actual pressure value in the gas confining pressure chamber 3, and feeding 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 downward and contact the coal rock sample 2 in the pressure chamber inner cylinder 5 and apply an axial load force.

[0027] It should be noted that the present embodiment adopts a closed-loop control system, which ensures accurate control of pressure and temperature during measurement through real-time monitoring and adjustment, improving the accuracy and reliability of the measurement. Closed-loop control is based on feedback mechanism, collecting data through pressure sensor 8 and temperature sensor 7 and timely stress application structure to maintain the set triaxial stress conditions. The technology in this embodiment can realize accurate measurement of the radial strain of coal rock under high temperature and triaxial stress conditions, providing key data support for mechanical analysis of oil-rich coal in situ pyrolysis process.

[0028] In one embodiment, the displacement measurement structure includes a heat-resistant stainless steel shell 26, which is connected from right to left in sequence with a heat-insulating protective inner shell 25, a spring 20, and a core 24 extending outside the heat-resistant stainless steel shell 26, the end of the core 24 is connected with a micro-deformation conical probe 19, the micro-deformation conical probe 19 extends into the convex structure of the annular heating sleeve 4; the heat-insulating protective inner shell 25 is connected from right to left in sequence with an electronic circuit board 22 and a displacement sensor coil 21. The outer surface of one end of the heat-resistant stainless steel shell 26 provided with a threaded structure, through the threaded structure, the displacement measurement structure can be conveniently installed outside the pressure chamber 6.

[0029] It should be noted that the micro-deformation conical probe 19 is made of hard alloy, which has high hardness and good heat resistance, and is suitable for radial micro-deformation monitoring in high temperature environment. The hard alloy probe can withstand high temperature and high pressure, and keep its shape and performance stable. This technology can ensure that the micro-deformation conical probe 19 maintains good contact state during high temperature and loading stress, improving the reliability and accuracy of micro-deformation measurement.

[0030] The micro-deformation conical probe 19 is designed as a conical probe, which can better embed into the sample surface and reduce the sliding error during measurement. The conical probe has a smaller contact area with the sample surface, which can more sensitively sense the small displacement change of the sample. This technology can improve the accuracy and reliability of micro-deformation measurement, and provide more accurate data for the study of mechanical behavior of coal rock under high temperature and loading stress conditions.

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

[0032] In addition, the direct contact between the top end of the micro-deformation cone-shaped probe 19 and the side edge of the coal rock sample 2 can minimize measurement errors and improve the sensitivity of micro-deformation measurement. Direct contact reduces the displacement transmission error of intermediate links, enabling the coal rock sample 2 to more accurately reflect the true displacement change of the coal rock sample 2. This technology provides key data for evaluating the mechanical properties of coal rock under high temperature and loading stress conditions.

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

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

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

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

[0037] It should be noted that the present application cooperates the high-precision stepping motor 13 with the grating ruler 14 to accurately control and monitor the radial displacement change of the coal rock sample 2. The high-precision stepping motor 13 drives the movement of the high-strength plunger 10 through the transmission shaft 11 and the transmission gear 12, and the design of this mechanical structure ensures the accurate control of the radial displacement. The grating ruler 14 is used to monitor the displacement change of the plunger 10, and then the volume change of the confining pressure chamber 3 is calculated, which can more accurately measure the radial strain of the coal rock material under high temperature and multi-axial stress conditions.

[0038] In this embodiment, the stepper motor 13 is a high-precision stepper motor with excellent control precision and stability, which can accurately control the movement of the piston and thus achieve precise control of the radial displacement of the sample. The stepper motor 13 controls the rotation angle by receiving pulse signals, thereby achieving precise displacement control. This technology ensures the controllability of the radial displacement of the sample during loading and the accuracy of the measurement, providing a strong guarantee for studying the mechanical behavior of coal 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 in the gas confining chamber 3 and feed back to the control system of the measuring device.

[0040] In one embodiment, an electrically controlled vent valve 15 is provided on the constant pressure gas pump 9 to control the pressure of the gas delivered by the constant pressure gas 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 instructions of the control system through electromagnetic driving principle, controls the flow of gas, realizes automatic operation, and improves the safety and convenience of the experiment. This technology simplifies the experimental operation process, reduces the influence of human factors on the experimental results, and ensures the repeatability and consistency of the experiment.

[0042] The working process of the present application is as follows: First, the low-thermal-expansion alloy calibration sample is placed in the high-temperature triaxial pressure chamber inner cylinder 5, the axial load and confining pressure are applied through the closed-loop control system, the constant pressure gas pump 9 and the grating ruler 14 are used to monitor the gas volume change, and the gas volume change curve caused by temperature change is calibrated. Subsequently, the load is removed, the alloy calibration sample is cooled and taken out; then the coal sample 2 is re-placed for testing, the axial load and confining pressure are applied again, the gas volume change is monitored by the grating ruler 14, and the radial strain of the coal sample 2 is calculated. At the same time, the micro-deformation cone probe 19 positioned by the cylindrical protruding structure pre-set on the inner wall of the triaxial pressure chamber inner cylinder 5 monitors the radial micro-deformation of the coal sample 2 at the upper, middle and lower positions, converts the displacement into an electrical signal, and finally obtains the curve of the micro-deformation with the change of the axial load. The entire working process is carried out under the conditions of high temperature and triaxial stress, and the closed-loop control system ensures the accurate control of pressure and temperature, while the design of the micro-deformation probe improves the accuracy and reliability of the micro-deformation measurement.

[0043] A measuring device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis, and a method for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis, the method comprising the following steps: Step 1, sample calibration, comprising the following steps: S11, the size of the alloy calibration sample is put into the high temperature pressure chamber inner cylinder 5, and a certain axial load is applied by the axial load loading mechanism 1 to compress the alloy calibration sample; S12, set a certain confining pressure value through the control system, then open the constant pressure gas pump 9 to make the pressure of the gas confining chamber 3 reach the preset value, and open the annular heating jacket 4 switch to make the temperature rise at a certain fixed rate until it reaches 700℃; S13, because the state of the gas in the gas confining chamber 3 will change during the temperature rising process, in order to maintain the 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 temperature rising process is recorded, and finally a curve of the gas volume change caused by the temperature change from room temperature to 700℃ is obtained; S14, the temperature rising gas volume change amount ΔV0=the cross-sectional area S of the constant pressure gas pump cavity The grating ruler displacement distance l is recorded as the curve of the gas volume change of the alloy calibration sample with temperature; Step 2, radial strain test, including the following steps: S21, after the alloy calibration sample completes the calibration, the axial pressure and confining pressure are removed, and then the coal rock sample 2 of the same size is taken out and put into the coal rock sample 2 for testing after cooling; S22, after the coal rock sample 2 is compressed by applying a certain axial load by the axial load loading mechanism 1, the confining pressure is applied by starting the constant pressure gas pump 9, the gas enters through the gas pipeline, and the high-precision stepping motor 13 controls the high-strength plunger 10 to compress the gas into the gas confining chamber 3, after the set pressure value is reached, the stepping motor 13 and the high-strength plunger 10 stop running, and during this process, the opening and closing of the electric control air valve 15 is controlled by the control system to complete the gas pressurization; S23, after reaching the preset pressure value, the annular heating jacket 4 is opened to rise to the preset temperature at the constant rate as in the calibration sample; S24, after waiting for the temperature of the gas confining chamber 3 to stabilize, the axial load is applied, the confining pressure is kept unchanged, and the coal rock sample 2 starts to deform radially after the axial deformation, so that the gas volume in the gas confining chamber 3 changes, in order to maintain the constant confining pressure, the stepping motor 13 is driven by the control system to move the high-strength plunger 10 until the indication of the pressure sensor 8 returns to the preset value; S25, in the process of continuously loading the axial stress, the axial deformation of the coal rock sample 2 is recorded, and the gas volume change of the gas confining chamber 3 is detected by the grating ruler 14, and the temperature rising gas volume change amount ΔV0=the cross-sectional area S of the constant pressure gas pump cavity The grating ruler displacement distance l is recorded as the curve of the gas volume change of the coal rock sample with temperature, and the radial deformation of the coal rock sample 2 is converted; S26, the curve of the gas volume of the coal sample with temperature is subtracted from the curve of the gas volume of the alloy calibration sample with temperature, so as to exclude the gas volume change caused by the temperature effect, and calculate the gas volume change caused by the stress deformation of the coal sample 2; For example, the coal sample 2 is a cylindrical sample, the diameter is d0, the height is h0, the initial volume of the sample V0=(d0 / 2) 2 ·π·h0; The axial deformation amount Δh of the sample after loading stress, the diameter d1 of the sample, the sample volume V1=(d1 / 2) 2 ·π·(h0-Δh); The volume V2=(d0 / 2) 2 ·π·Δh; the gas volume ΔV changed by the radial deformation can be obtained; After integration, S l=(d1 / 2) 2 ·π·(h0-Δh)+(d0 / 2) 2 ·π·Δh-(d0 / 2) 2 ·π·h0; d1= ; The radial deformation amount Δd=d1-d0; The radial strain ε=Δd / d0.

[0044] In the radial strain test section, the constant pressure gas pump 9 and the grating ruler 14 completed the calibration will be used to test the coal sample 2 of the same size. After the sample is compressed, the constant pressure gas pump 9 is pressurized by controlling the electric control air valve 15, and stops running after reaching the set confining pressure. Then, the ring heater 4 raises the temperature to the preset value, and after the temperature is stable, the axial stress loading starts. With the axial deformation of the coal sample 2, the radial deformation that follows causes the change of the gas volume in the confining pressure chamber 3. In order to maintain constant confining pressure, the stepping 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 displacement change of the piston monitored by the grating ruler 14 is converted into the gas volume change, and the radial strain of the sample is further calculated. By subtracting the volume change curve of the calibration sample, the temperature effect can be excluded, and only the gas volume change of the sample after stress is calculated, and a more accurate radial strain result is obtained.

[0045] Step 3, micro-deformation test, comprising the following steps: S31, the radial micro-deformation of the sample is monitored by the displacement measurement structure, before the test, the pressure chamber inner cylinder 5 of the gas confining pressure chamber 3 is modified, a small cylindrical protruding structure is arranged at the upper, middle and lower parts respectively, the size is slightly larger than the micro-deformation cone probe 19, and a hole slightly smaller than the size of the micro-deformation cone probe 19 is preset on the cylindrical protruding structure; S32, after the coal rock sample 2 is put into the pressure chamber inner cylinder 5, the micro-deformation cone probe 19 is installed in the preset hole, so that the micro-deformation cone probe 19 can be just clamped inside the cylindrical protruding structure, and the top of the cylindrical protruding structure is just in contact with the side of the coal rock sample 2; S33, the heat-resistant stainless steel shell 26 of the displacement measurement structure is screwed on the outer wall of the pressure chamber 6 according to the thread, and the screwing ensures that the inside of the pressure chamber 6 will not leak; when the gas pressure of the confining pressure chamber 3 increases, the ductile red copper cylindrical protruding structure will be compressed, the micro-deformation cone probe 19 will be tightly wrapped into one, and the radial deformation can be monitored with higher precision; S34, during the application of axial load, the upper, middle and lower positions of the coal rock sample 2 will have different degrees of radial micro-deformation, which will drive the micro-deformation cone probe 19 to stretch and contract, and the displacement will be converted into electrical signals by the displacement sensor coil 21 and the electronic circuit board 22 and transmitted to the control system, finally the curve of the micro-deformation of the sample at different positions with the change of axial load is obtained, and the radial micro-deformation monitoring of the coal 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 contains a hard alloy micro-deformation cone probe 19, an iron core 24, a spring 20, a displacement sensor coil 21, an electronic circuit board 22, a heat insulation protection inner shell 25 and a heat-resistant stainless steel shell 26. These high-precision displacement measurement structures are positioned by the cylindrical protruding structure preset on the pressure chamber inner cylinder 5, which ensures the stable contact between the micro-deformation cone probe 19 and the coal rock sample 2. With the application of axial load, different parts of the sample will have a small radial deformation, which will be converted into displacement through the stretching and contraction of the micro-deformation cone probe 19, and then converted into electrical signals through the displacement sensor coil 21 and the electronic circuit board 22, finally collected, processed and plotted by the computer to obtain the curve of the micro-deformation with the change of axial load.

[0047] It is worth noting that the direct contact point of the micro-deformation sensor with the sample is located on the side of the sample, which is achieved by directly setting the top end of the micro-deformation cone probe 19 in contact with the sample. This direct contact reduces measurement errors and ensures data reliability. In addition, the close contact between the deformation capability of the pressure chamber inner cylinder 5 and the micro-deformation probe 19 ensures that even if the gas surrounding pressure chamber 3 itself deforms during the measurement, it will not significantly affect the measurement results, thereby maintaining the accuracy of the micro-deformation measurement.

[0048] The above only describes the preferred embodiments of the present application, and it should be pointed out that for those skilled in the art, without departing from the inventive concept, a number of modifications and improvements can be made, which are within the scope of the present application.

Claims

1. A device for measuring radial strain and micro-deformation of oil-rich coal pyrolysis, characterized in that, The device comprises: A pressure chamber (6) is provided with a pressure chamber inner cylinder (5) in the inner cavity of the pressure chamber (6), the pressure chamber inner cylinder (5) is used for accommodating the coal rock sample (2) to be measured; a gas confining pressure chamber (3) is formed between the outer wall of the pressure chamber inner cylinder (5) and the inner wall of the pressure chamber (6); one side of the pressure chamber inner cylinder (5) is provided with a protruding structure extending outward, the number of the protruding structure is multiple, and the protruding structure is arranged in an up-down interval structure; An annular heating jacket (4) is sleeved on the outer side of the pressure chamber (6), is used for uniformly heating the gas in the gas confining pressure chamber (3) and the coal rock sample (2) in the pressure chamber inner cylinder (5), and avoids measurement errors caused by local overheating or temperature gradient; A displacement measurement structure is arranged on one side of the annular heating jacket (4) and has the same number as the protruding structure, each displacement measurement structure corresponds to one protruding structure and is connected with the corresponding protruding structure, and is used for monitoring the change of the radial displacement of the coal rock sample (2) in real time; A stress applying structure is arranged at the lower end of the other side of the annular heating jacket (4) and is connected with the gas confining pressure chamber (3), is used for controlling the pressure of the gas delivered by the gas pressure source to the gas confining pressure chamber (3), so as to form a controllable triaxial stress environment in the gas confining pressure chamber (3) and accurately monitor the radial displacement of the coal rock sample (2); A temperature sensor (7) is connected with the gas confining pressure chamber (3) and is used for detecting the actual pressure value in the gas confining pressure chamber (3) and feeding back to the control system of the measuring device; An axial load loading mechanism (1) is located above the pressure chamber (6), can move vertically downward, is in contact with the coal rock sample (2) in the pressure chamber inner cylinder (5) and applies an axial load.

2. A device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 1, characterized in that: The displacement measurement structure comprises a heat-resistant stainless steel shell (26), the heat-resistant stainless steel shell (26) is sequentially connected with a heat insulation protection inner shell (25), a spring (20) and a iron core (24) extending outside the heat-resistant stainless steel shell (26) from right to left, the end of the iron core (24) is connected with a micro-deformation conical probe (19), and the micro-deformation conical probe (19) extends into the protruding structure of the annular heating jacket (4); The heat insulation protection inner shell (25) is sequentially connected with an electronic circuit board (22) and a displacement sensor coil (21) from right to left.

3. A device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 2, characterized in that: The outer surface of one end of the heat-resistant stainless steel shell (26) provided with the micro-deformation conical probe (19) is provided with a thread (23), and the displacement measurement structure is mounted on the outer side of the pressure chamber (6) through the thread (23).

4. The device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 1, characterized in that: The stress applying structure comprises a constant pressure gas pump (9), the output end of the constant pressure gas pump (9) is connected with the gas confining pressure chamber (3) through a gas pipeline, the input end is connected with a driving structure, and the inside of the constant pressure gas pump (9) is provided with a high-strength plunger (10).

5. A device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 4, characterized in that: The driving structure comprises a stepping motor (13), an output end of the stepping motor (13) is connected with a transmission gear (12), the transmission gear (12) is connected with a transmission shaft (11), the transmission shaft (11) extends into a constant-pressure gas pump (9) and is connected with the high-strength plunger (10).

6. A device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 4, characterized in that: A pressure sensor (8) is arranged on the gas pipeline, which is used for detecting the actual pressure value in the gas confining chamber (3) and feeding back to the control system of the measuring device.

7. A device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 6, characterized in that: An electrically-controlled vent valve (15) is arranged on the constant-pressure gas pump (9), which is used for controlling the pressure of the gas delivered from the constant-pressure gas pump (9) to the gas confining chamber (3).

8. The device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 5, characterized in that: A grating ruler (14) is arranged on the transmission shaft (11), which is used for monitoring the gas volume change in the constant-pressure gas pump (9).

9. A method for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis using the radial strain and micro-deformation measuring device for oil-rich coal pyrolysis according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: Step 1, sample calibration, comprising the following steps: S11, the alloy calibration sample of a certain size is placed in the inner cylinder (5) of the high-temperature pressure chamber, and a certain axial load is applied through the axial load loading mechanism (1) to compress the alloy calibration sample; S12, a certain confining pressure value is set through the control system, then the constant-pressure gas pump (9) is opened, so that the pressure of the gas confining chamber (3) reaches the preset value; the annular heating jacket (4) switch is opened, so that the temperature is raised at a certain fixed rate until 700 DEG C; S13, because the state of the gas in the gas confining chamber (3) changes during the temperature rising process, in order to maintain the constant preset confining pressure value, the high-strength plunger (10) will automatically compress or stretch, at this time, the grating ruler (14) scale during the temperature rising process is recorded, and finally a gas volume change curve caused by the temperature change from room temperature to 700 DEG C is obtained; S14, the formula calculates the volume change of the heating gas ΔV0= constant pressure gas pump cavity cross-sectional area S The grating displacement distance l is recorded as the curve of the alloy calibration sample gas volume changing with temperature. Step 2, radial strain test, comprising the following steps: S21, after the alloy calibration sample completes the calibration, the axial load and the confining pressure are removed, and after cooling, the coal rock sample (2) of the same size is taken out and placed in the coal rock sample (2) for testing; S22, after the coal rock sample (2) is compressed by applying a certain axial load through the axial load loading mechanism (1), the constant-pressure gas pump (9) is started to apply the confining pressure, the gas enters through the gas pipeline, and the high-strength plunger (10) is controlled by the high-precision stepping motor (13) to compress the gas into the gas confining chamber (3), after reaching the set pressure value, the stepping motor (13) and the high-strength plunger (10) stop running, and the opening and closing of the electrically-controlled vent valve (15) controlled by the control system completes the gas pressurization during the process; S23, after reaching the preset pressure value, the annular heating jacket (4) is opened to raise the temperature to the preset temperature at the constant rate as in the calibration of the sample; S24, after the temperature of the gas confining chamber (3) is stable, the axial load is applied, the confining pressure is kept unchanged, the coal rock sample (2) starts to deform radially after the axial deformation, so that the gas volume in the gas confining chamber (3) changes, in order to maintain the constant confining pressure, the high-strength plunger (10) is driven by the stepping motor (13) controlled by the control system to move until the indication of the pressure sensor (8) returns to the preset value. S25, in the process of constantly loading axial stress, record the axial deformation of coal rock sample (2), at the same time, detect the gas volume change of gas confining chamber (3) through grating ruler (14), calculate the volume change of heating gas through formula ΔV0= constant pressure gas pump cavity sectional area S Grating ruler displacement distance l, record as the curve of coal rock sample gas volume change with temperature, and convert to get the radial deformation of coal rock sample (2); S26, subtract the alloy calibration sample gas volume change with temperature curve from the coal rock sample gas volume change with temperature curve to exclude the gas volume change caused by temperature effect, and calculate the gas volume change caused by the stress deformation of the coal rock sample (2); Step 3, micro-deformation test, comprising the following steps: S31, monitor the radial micro-deformation of the sample by the displacement measuring structure, before testing, modify the pressure chamber inner cylinder (5) of the gas confining chamber (3), set a small cylindrical protruding structure on the upper, middle and lower parts, which is slightly larger than the micro-deformation cone probe (19), and preset a hole smaller than the micro-deformation cone probe (19) on the cylindrical protruding structure; S32, after the coal rock sample (2) is placed in the pressure chamber inner cylinder (5), the micro-deformation cone probe (19) is loaded into the preset hole, so that the micro-deformation cone probe (19) can be clamped inside the cylindrical protruding structure, and the top of the cylindrical protruding structure is in contact with the side surface of the coal rock sample (2); S33, screw the heat-resistant stainless steel shell (26) of the displacement measuring structure on the outer wall of the pressure chamber (6) according to the thread, and tighten it to ensure that the inside of the pressure chamber (6) will not leak; S34, during the process of applying axial load, the upper, middle and lower positions of the coal rock sample (2) will have different degrees of radial micro-deformation, which will drive the micro-deformation cone probe (19) to stretch and contract, and the displacement will be converted into an electrical signal through the displacement sensor coil (21) and the electronic circuit board (22) to the control system, and finally the micro-deformation change curve of the sample at different positions with the axial load is obtained, and the radial micro-deformation monitoring of the coal rock sample (2) is completed.

10. The device for measuring the radial strain and micro-deformation of oil-rich coal pyrolysis according to claim 9, characterized in that: In step 3, when the gas pressure of the gas confining chamber (3) rises, the cylindrical protruding structure with strong ductility will be compressed, and the micro-deformation cone probe (19) will be tightly wrapped into one, which can more accurately monitor the radial deformation.

Images