Detection device with small strain monitoring and piezo-electric crystal and testing method thereof

Abstract

The invention discloses a detection device with small strain monitoring and a piezoelectric crystal and a testing method of the detection device, and aims to solve the problem that multi-scale real-time observation and accurate monitoring are difficult to carry out in a multi-gas hydrate replacement process in the prior art. The device is used for detecting the replacement efficiency and the micromechanical rigidity of the hydrate in different sediment mineral environments in a reaction kettle, during use, a hydrate replacement experiment is carried out between soil particles or ore sheets, and the change of the resistivity and the rigidity of the hydrate in the replacement process under the micro-micro scale is recorded in detail; the bending element performs real-time monitoring and effective analysis recording on soil body small strain in the replacement process so as to reflect soil body void ratio change, pore pressure change and structural damage of fine-grained soil and characterize important parameters of soil body deformation and dynamic characteristics. Powerful technical support and experimental means are provided for the research on the macro-fine-micro phenomenon of hydrate replacement in different simulated sediment geological environments under laboratory conditions.

Description

Technical Field

[0001] The present invention relates to the synthesis and replacement technologies of multi-gas hydrates in a simulated soil environment, and particularly to a detection device and a testing method thereof that include small strain monitoring and piezoelectric crystals. Background Art

[0002] With the continuous growth of global energy demand and the increasing awareness of environmental protection, natural gas hydrate, as a rich, clean and efficient energy resource, has received extensive attention. Its exploitation and utilization have become a research hotspot in the energy field. However, the formation and decomposition processes of natural gas hydrates involve complex multi-gas replacement reactions. In-depth study of the mechanisms of these reactions is of great significance for optimizing the exploitation process and improving the exploitation efficiency. At present, the research on multi-gas hydrate replacement reactions mainly relies on experimental-scale reactor devices, but their visualization degree is limited. Traditional reaction devices are difficult to achieve real-time and intuitive observation of the reaction process, resulting in researchers being unable to accurately capture the key phenomena and changes in the reaction. In addition, the monitoring means of existing devices are relatively single, usually only relying on parameters such as temperature and pressure for detection, lacking the ability to monitor key information such as gas replacement and hydrate structure in real time. In terms of mechanical detection, traditional methods for measuring the small strain shear modulus (such as triaxial tests combined with local strain sensors) have problems such as high sensor cost, complex installation, and the measurement accuracy being affected by the sample quality. At the same time, the gas monitoring after replacement mainly relies on large-scale equipment such as gas chromatographs, and the physical properties of hydrates during the replacement process are also difficult to accurately measure. Finally, due to the limitations of the monitoring means, the processing and analysis efficiency of experimental data is low, restricting the in-depth study of the reaction mechanism. To address the above problems, this patent proposes an innovative experimental device - a multi-scale visualization reactor monitoring system for multi-gas hydrate replacement with soil small strain and piezoelectric crystals. This device significantly improves the visualization degree and real-time monitoring ability of experimental research, can accurately measure the physical properties of hydrates, and improves the data processing efficiency. Through this innovative device, researchers can more deeply reveal the macro and micro mechanisms of hydrate formation and decomposition, providing important theoretical basis and technical support for the efficient exploitation and utilization of natural gas hydrates. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to solve the problems in the prior art that the visualization degree is low, the small strain monitoring degree is low, the data processing and analysis are difficult, and the physical properties of hydrates are difficult to measure during the hydrate replacement process, resulting in the inability to observe the macroscopic and microscopic changes during the replacement process, the inability to monitor the deformation characteristics of hydrates during the replacement process, and the inability to process the monitoring data during the replacement process. Now, a detection device and a testing method thereof that include small strain monitoring and piezoelectric crystals are provided.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows: A detection device including small strain monitoring and piezoelectric crystals, comprising:

[0005] A reaction kettle, which contains a water-containing test soil sample inside. A gas discharge port communicating with its interior is provided on the reaction kettle, and a valve is provided on the gas discharge port;

[0006] A gas delivery module, which is connected to the interior of the reaction kettle and is used to deliver carbon dioxide or methane into the reaction kettle;

[0007] A temperature control module, which is connected to the reaction kettle and is used to control the reaction temperature inside the reaction kettle;

[0008] It further includes:

[0009] A piezoelectric detection module, which is arranged inside the reaction kettle and is used to detect the replacement of hydrates. The piezoelectric detection module includes a first piezoelectric crystal, a second piezoelectric crystal, a first piezoelectric crystal, a second piezoelectric crystal, a signal exciter, a signal amplifier, a resistor, and an oscilloscope. The signal exciter is respectively connected to the first piezoelectric crystal and the second piezoelectric crystal. The resistor is connected in series between the signal exciter and the second piezoelectric crystal. Soil particles or mineral chips are bonded to both the first piezoelectric crystal and the second piezoelectric crystal. The signal exciter is connected to the first piezoelectric crystal. The second piezoelectric crystal is connected to the signal amplifier. The signal amplifier is connected to the oscilloscope. A first voltmeter is arranged between the first piezoelectric crystal and the second piezoelectric crystal. A second voltmeter is arranged between the first piezoelectric crystal, the second piezoelectric crystal, and the resistor. An adjustment mechanism is arranged between the first piezoelectric crystal and the second piezoelectric crystal. The adjustment mechanism is used to adjust the relative proximity or distance between the first piezoelectric crystal and the second piezoelectric crystal;

[0010] And a data processing module, which is respectively connected to the temperature control module, the oscilloscope, the first voltmeter, and the second voltmeter by signals.

[0011] In some preferred embodiments, it further includes a bending element monitoring module arranged inside the reaction kettle. The bending element monitoring module includes two bending element components. One of the bending element components is connected to the signal exciter, and the other bending element component is connected to the signal amplifier. A delivery module is externally connected to the reaction kettle for converting carbon dioxide into a liquid state and delivering it into the reaction kettle.

[0012] In some preferred embodiments, the delivery module includes a peristaltic pump and an intermediate container. A piston slides inside the intermediate container. The piston divides the intermediate container into an upper chamber and a lower chamber. The upper chamber is used to store carbon dioxide, and the lower chamber is used to store liquid. The peristaltic pump is connected to the lower chamber and is used to deliver the liquid into the lower chamber.

[0013] Preferably, in some embodiments, the adjusting mechanism includes an adjusting screw, a first guide plate, and a second guide plate. The adjusting screw is rotatably mounted on the reaction kettle, and one end of the adjusting screw protrudes outside the reaction kettle. A part of the adjusting screw is located inside the reaction kettle and is provided with two external threads with opposite helix directions. The first guide plate and the second guide plate are located inside the reaction kettle and are respectively threadedly connected to the two external threads of the adjusting screw. The first piezoelectric crystal is disposed on the first guide plate, and the second piezoelectric crystal is disposed on the second guide plate. The first guide plate and the second guide plate are both slidably disposed inside the reaction kettle along the displacement directions of the first piezoelectric crystal and the second piezoelectric crystal.

[0014] Preferably, in some embodiments, a guide shaft is disposed inside the reaction kettle. The guide shaft is disposed along the displacement directions of the first piezoelectric crystal and the second piezoelectric crystal. Guide holes matching the guide shaft are disposed on both the first guide plate and the second guide plate, and the guide holes on the first guide plate and the second guide plate are both disposed on the guide shaft.

[0015] Preferably, in some embodiments, the gas delivery module includes a first gas cylinder and a second gas cylinder. Carbon dioxide is stored in the first gas cylinder, and methane is stored in the second gas cylinder. Both the first gas cylinder and the second gas cylinder are in communication with the interior of the reaction kettle.

[0016] Preferably, in some embodiments, the temperature control module includes a low-temperature constant temperature bath and a heat exchange tube. The heat exchange tube is disposed inside the reaction kettle, and the low-temperature constant temperature bath is in communication with the heat exchange tube.

[0017] Preferably, in some embodiments, a visual observation window is disposed on the reaction kettle.

[0018] A test method using a detection device with small strain monitoring and piezoelectric crystals as described above is as follows:

[0019] S1. Before the test, open the upper cover of the reaction kettle, and then place soil particles or mineral chips on the first piezoelectric crystal and the second piezoelectric crystal inside the reaction kettle respectively.

[0020] S2. Start the temperature control module, signal exciter, signal amplifier, oscilloscope, and data processing module, check the temperature control module, signal exciter, signal amplifier, oscilloscope, and data processing module and ensure that each device is operating normally, and check the status of the gas delivery module.

[0021] S3. Adjust the distance between the soil particles or mineral chips between the first piezoelectric crystal and the second piezoelectric crystal to the required distance through the adjusting mechanism, and then drop water droplets between the soil particles or mineral chips to form a cylindrical water layer.

[0022] S4. During the test, cover the upper cover of the reactor. Pass methane gas into the reactor through the gas delivery module until it reaches 3 Mpa, and then open the valve to discharge the gas in the reactor. Repeat the process of filling and discharging the gas several times to ensure that there is no other gas in the reactor 1 and check the airtightness of the reactor 1.

[0023] S5. Use the temperature control module to adjust the internal temperature of the reactor to 2 °C, and then pass gas into the reactor again through the gas delivery module until the pressure in the reactor reaches 8 Mpa and stop gas input.

[0024] S6. Wait for the hydrate to form and record the temperature and pressure. When the temperature and pressure decrease significantly, it indicates that the hydrate is forming. Mark the hydrate formation conditions until the temperature, pressure, or oscilloscope in the reactor shows no obvious change, and then consider the reaction completed.

[0025] S7. After the methane hydrate is formed, adjust the temperature in the reactor to -5 °C through the temperature control module. At this time, the methane hydrate has a good preservation effect.

[0026] S8. Open the valve at the gas discharge port on the reactor to discharge the excess methane gas in the reactor, pass in 5 Mpa of carbon dioxide, and adjust the temperature in the reactor to 5 - 10 °C through the temperature control module for replacement.

[0027] S9. During the replacement, send an electrical signal every 20 m / s with a signal exciter. The first piezoelectric crystal and the second piezoelectric crystal generate P-waves in the reactor, the flexural element generates S-waves, and they are transmitted to the oscilloscope through a signal amplifier for display. The first voltmeter and the second voltmeter send the received signals to the data processing module, and the replacement efficiency of the hydrate will be manifested by the change in resistance.

[0028] S10. When there is no obvious change in the temperature, pressure, and oscilloscope in the reactor, consider the reaction completed. Open the valve at the gas discharge port on the reactor to discharge the gas in the reactor, turn off the temperature control module, signal exciter, signal amplifier, oscilloscope, and data processing module, open the upper cover of the reactor, and clean the reactor.

[0029] The beneficial effects of the present invention are as follows: An innovative device of a multi-gas hydrate replacement visualization reactor for a detection device and a test method thereof containing small strain monitoring and piezoelectric crystals conducts hydrate replacement experiments in soil samples (or mineral samples) and mineral particle suspensions, and details and records the macroscopic and microscopic morphological changes of hydrates during the replacement process. Through the bending element monitoring module, the small strains during the replacement process can be monitored in real time and effectively analyzed and recorded to reflect the changes in soil porosity ratio, pore pressure, and the structural damage of fine-grained soil, which are important parameters characterizing soil deformation and dynamic characteristics. Through the piezoelectric crystal module, which is arranged inside the reactor and used to detect the replacement efficiency of hydrates and the stiffness of hydrates. Therefore, the present invention provides strong technical support and experimental means for the research on hydrate replacement phenomena under laboratory conditions for simulating different sediment soil geological environments, avoiding the problems in the prior art such as low visualization degree, low small strain monitoring degree, difficult data processing and analysis, and difficult measurement of the physical properties of hydrates during the hydrate replacement process, resulting in the inability to observe macroscopic and microscopic changes during the replacement process, the inability to monitor the deformation characteristics of hydrates during the replacement process, and the inability to process the monitoring data during the replacement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the drawings and embodiments.

[0031] Figure 1 is a schematic structural diagram of the present invention;

[0032] Figure 2 is a schematic structural diagram inside the reactor of the present invention.

[0033] In the figure: 1. Reactor, 2. Gas discharge port, 3. Valve, 4. First gas cylinder, 5. Second gas cylinder, 6. First piezoelectric crystal, 7. Second piezoelectric crystal, 8. Signal exciter, 9. Signal amplifier, 10. Resistor, 11. Oscilloscope, 12. First voltmeter, 13. Second voltmeter, 14. Adjusting screw, 15. First guide plate, 16. Second guide plate, 17. Visualization observation window, 18. Temperature control module, 19. Data processing module, 20. Bending element, 21. Peristaltic pump, 22. Intermediate container. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present invention will be further described in detail below with reference to the embodiments:

[0035] The present invention is not limited to the following specific embodiments. Those of ordinary skill in the art can implement the present invention in other various specific embodiments according to the content disclosed in the present invention, or those that simply change or modify using the design structure and idea of the present invention all fall within the protection scope of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0038] As Figure 1-2 shown, a detection device including small strain monitoring and piezoelectric crystals comprises:

[0039] A reaction kettle 1, which contains a water-containing test soil sample inside. A gas discharge port 2 communicating with the inside of the reaction kettle 1 is provided on the reaction kettle 1, and a valve 3 is provided on the gas discharge port 2. A pressure sensor and a temperature sensor are installed on the reaction kettle 1;

[0040] A gas delivery module, which is in communication with the inside of the reaction kettle 1 and is used to deliver carbon dioxide or methane into the reaction kettle 1;

[0041] A temperature control module 18, which is in communication with the reaction kettle 1 and is used to control the reaction temperature inside the reaction kettle 1;

[0042] Piezoelectric detection module, which is arranged in the reactor 1 and used to detect the replacement of hydrates. The piezoelectric detection module includes a first piezoelectric crystal 6, a second piezoelectric crystal 7, a signal exciter 8, a signal amplifier 9, a resistor 10 and an oscilloscope 11. The first piezoelectric crystal 6 and the second piezoelectric crystal 7 are relatively arranged in the reactor 1. The signal exciter 8 is respectively connected to the first piezoelectric crystal 6 and the second piezoelectric crystal 7. The resistor 10 is connected in series between the signal exciter 8 and the second piezoelectric crystal 7. Soil particles or mineral chips are bonded to both the first piezoelectric crystal 6 and the second piezoelectric crystal 7. In this embodiment, soil particles are used. The second piezoelectric crystal 7 is connected to the signal amplifier 9, and the signal amplifier 9 is connected to the oscilloscope 11. A first voltmeter 12 is arranged between the first piezoelectric crystal 21 and the second piezoelectric crystal 7. A second voltmeter 13 is arranged between the first piezoelectric crystal 21, the first piezoelectric crystal 22 and the resistor 10. An adjusting mechanism is arranged between the first piezoelectric crystal 21 and the first piezoelectric crystal 22. The adjusting mechanism is used to adjust the relative proximity or distance between the first piezoelectric crystal 21 and the first piezoelectric crystal 22;

[0043] And a data processing module 19, which is respectively connected to the temperature control module 18, the oscilloscope 11, the first voltmeter 12 and the second voltmeter 13 in a signal connection. The data processing module 19 is a single-chip microcomputer, which can store and analyze data.

[0044] Bender element monitoring module, which is arranged in the reactor 1. The bender element monitoring module includes two bender element components 20. One of the bender element components 20 is connected to the signal exciter 8, and the other bender element component 20 is connected to the signal amplifier 9. A water-containing soil sample is arranged in the reactor 1. A conveying module for converting carbon dioxide into a liquid state and conveying it into the reactor is connected outside the reactor 1. The conveying module includes a peristaltic pump 21 and an intermediate container 22. A piston 23 slides in the intermediate container 22. The piston 23 divides the intermediate container into an upper chamber and a lower chamber. The upper chamber is used to store carbon dioxide, and the lower chamber is used to store liquid. The peristaltic pump 21 is connected to the lower chamber and used to convey the liquid into the lower chamber;

[0045] The adjusting mechanism includes an adjusting screw 14, a first guide plate 15 and a second guide plate 16. The adjusting screw 14 is rotatably installed on the reactor 1. One end of the adjusting screw 14 protrudes outside the reactor 1. A part of the adjusting screw 14 is located inside the reactor 1 and is provided with two external threads with opposite helix directions. The first guide plate 15 and the second guide plate 16 are located inside the reactor 1 and are respectively threadedly connected to the two external threads of the adjusting screw 14. The first piezoelectric crystal 6 is arranged on the first guide plate 15, and the second piezoelectric crystal 7 is arranged on the second guide plate 16. The first guide plate 15 and the second guide plate 16 are both slidably arranged inside the reactor 1 along the displacement direction of the first piezoelectric crystal 6 and the second piezoelectric crystal 7.

[0046] In this embodiment, the model of the peristaltic pump 21 is 2PB-1040Ⅳ. The peristaltic pump 21 has a flow regulation capacity ranging from 0.01 to 10.0 ml / min and can operate under a pressure environment of 0 to 42 MPa. The repeated measurement accuracy of this peristaltic pump 21 is not greater than ±0.5%, and the setting accuracy is not greater than ±1%. Its single plunger displacement is 100 μl, suitable for handling media with viscosities in the range of 0.3 to 5 cp. The interface dimensions of the peristaltic pump 21 are specified as: the inlet is Φ3×0.5 mm, and the outlet is Φ1.6×0.5 mm. The physical dimensions of the peristaltic pump 21 are 260×385×185 mm, and the weight is 12 kg.

[0047] The peristaltic pump 21 adopts a parallel double-pump head design, in which the left and right plungers work together in an alternating reciprocating motion manner, cooperate with the one-way valves at the inlet and outlet, and realize the continuous process of liquid suction and discharge, so as to ensure the constant flow delivery of the liquid. The core function of this peristaltic pump 21 is to pressurize and transmit the subsequent input gas, and at the same time prevent the gas from flowing back.

[0048] The intermediate container 22 is constructed of stainless steel and is equipped with a circular piston inside. The core function of this container is to serve as a storage chamber for the subsequent injection of carbon dioxide gas. By using the peristaltic pump 21 to transport clear water to the second chamber at a stable flow rate and generate a consistent pressure, the gas in the first chamber is compressed and transported into the internal space of the reaction kettle 1.

[0049] A guide shaft is arranged inside the reaction kettle 1, and the guide shaft is arranged along the displacement directions of the first piezoelectric crystal 6 and the second piezoelectric crystal 7. Guide holes matching the guide shaft are arranged on both the first guide plate 15 and the second guide plate 16, and the guide holes on the first guide plate 15 and the second guide plate 16 are both arranged on the guide shaft.

[0050] The gas delivery module includes a first gas cylinder 4 and a second gas cylinder 5. Carbon dioxide is stored in the first gas cylinder 4, and methane is stored in the second gas cylinder 5. Both the first gas cylinder 4 and the second gas cylinder 5 are in communication with the inside of the reaction kettle 1. The first gas cylinder 4 and the reaction kettle 1 are connected by an external pipeline, and a first valve is installed on the external pipeline. The second gas cylinder 5 and the reaction kettle 1 are connected by an external pipeline, and a second valve is installed on the external pipeline.

[0051] The temperature control module 18 includes a low-temperature constant temperature bath and a heat exchange tube. The heat exchange tube is arranged inside the reaction kettle 1, and the low-temperature constant temperature bath is in communication with the heat exchange tube, that is, the internal temperature of the reaction kettle 1 is adjusted by means of heat exchange.

[0052] There are four visual observation windows 17 provided on the reaction kettle 1, and the four visual observation windows 17 are evenly distributed along the circumferential direction of the reaction kettle 1. The visual observation windows 17 are composed of high-transparency optical lenses, aiming to optimize the visual monitoring of the hydrate formation and decomposition processes and ensure sufficient supplementary lighting and observation from different perspectives. In addition, the visual observation windows 17 are configured with sapphire lenses, and this lens has the performance of withstanding high-pressure conditions to meet the adaptation to the high-pressure environment during the experiment.

[0053] Example 2

[0054] Example 2 adopts a test method of Example 1, specifically: a test method using a detection device with small strain monitoring and piezoelectric crystals as described above, and the operation steps are as follows:

[0055] S1. Before the test, open the upper cover of the reaction kettle 1, pour the water-containing soil sample into the reaction kettle 1, and then place the soil particles or ore chips on the first piezoelectric crystal 6 and the second piezoelectric crystal 7 in the reaction kettle 1 respectively. Both the soil particles and the water-containing soil sample are quartz sand.

[0056] S2. Start the temperature control module 18, signal exciter 8, signal amplifier 9, oscilloscope 11 and data processing module 19, check the temperature control module 18, signal exciter 8, signal amplifier 9, oscilloscope 11 and data processing module 19 and ensure that each device is operating normally, and check the status of the gas delivery module.

[0057] S3. And adjust the distance between the first piezoelectric crystal 6 and the second piezoelectric crystal 7 to the required distance through the adjustment mechanism, and then drop water between the first piezoelectric crystal 6 and the second piezoelectric crystal 7 to form a cylindrical water layer.

[0058] S4. During the test, cover the upper cover of the reaction kettle 1, open the second gas cylinder 5, introduce methane gas into the reaction kettle 1 until it reaches 3 Mpa, and then open the back pressure valve at the valve 3 to discharge the gas in the reaction kettle 1. Repeat the gas charging and discharging several times to ensure that there is no other gas in the reaction kettle 1, and check the airtightness of the reaction kettle 1.

[0059] S5. After using the temperature control module 18 to adjust the internal temperature of the reaction kettle 1 to 2 °C, introduce the gas in the second gas cylinder 5 into the reaction kettle 1 again until the pressure in the reaction kettle 1 reaches 8 Mpa and stop gas input.

[0060] S6. Wait for the hydrate to form and record the temperature and pressure. When the temperature and pressure decrease significantly, it indicates that the hydrate is forming. Mark the hydrate formation conditions until there is no obvious change in the temperature, pressure or oscilloscope 11 in the reaction kettle 1, and then consider the reaction to be completed.

[0061] S7. After the methane hydrate is formed, adjust the temperature in the reaction kettle 1 to -5°C through the temperature control module 18. At this time, the methane hydrate has a good preservation effect.

[0062] S8. Open the valve 3 of the gas discharge port 2 on the reaction kettle 1 to discharge the excess methane gas in the reaction kettle 1. Then open the first gas cylinder 4 and introduce 5 Mpa of carbon dioxide, and adjust the temperature in the reaction kettle 1 to 5 - 10°C through the temperature control module 18 for replacement.

[0063] S9. During the replacement, send an electrical signal every 20 m / s with the signal exciter 8, and send the received signal to the data processing module 19 through the oscilloscope 11, the first voltmeter 12, and the second voltmeter 13. The bending element 20 generates an S wave on the oscilloscope 11, and the first piezoelectric crystal 6 and the second piezoelectric crystal 7 generate a P wave. The two can contact the signal simultaneously without conflict, and different waveforms are displayed on the oscilloscope 11.

[0064] S10. When there are no obvious changes in the temperature, pressure, and oscilloscope 11 in the reaction kettle 1, it is considered that the reaction is completed. Open the valve 3 of the gas discharge port 2 on the reaction kettle 1 to discharge the gas in the reaction kettle 1. Turn off the temperature control module 18, the signal exciter 8, the signal amplifier 9, the oscilloscope 11, and the data processing module 19. Open the upper cover of the reaction kettle 1 and clean the reaction kettle 1.

[0065] When the above detection device containing small strain monitoring and piezoelectric crystals and its testing method are in use, the reaction rate during the CH4-CO2 replacement can be explored through the resistance difference between water and hydrate. The instrument used is a piezoelectric crystal. First, drop deionized water between the soil particles or ore chips in the reaction kettle 1. The water forms a water meniscus between the soil particles or ore chips using its surface tension and maintains a thin cylindrical water layer, which represents incompletely water-saturated sediment, and makes the signal exciter 8, the first piezoelectric crystal 6, between the soil particles or ore chips, the second piezoelectric crystal 7, the resistor 10, and then to the signal exciter 8 connected in series. Send an electrical signal through the signal exciter 8, and record the values of the first voltmeter 12 and the second voltmeter 13 by the data processing module 19. At the same time, connect a line on the periphery in series with the signal exciter 8, the first piezoelectric crystal 6, between the soil particles or ore chips, the second piezoelectric crystal 7, the signal amplifier 9, and the oscilloscope 11, and make the oscilloscope 11 receive the P wave generated by the first piezoelectric crystal 6 and the second piezoelectric crystal 7. Secondly, inject the corresponding gas for forming hydrate and adjust the appropriate temperature and pressure for generation. Furthermore, connect the signal exciter 8, the bending element 20 on one side, between the soil particles or ore chips, the bending element 20 on the other side, the signal amplifier 9, and the oscilloscope 11 in series, and make the oscilloscope 11 receive the S wave generated by the bending element 20 on one side and the bending element 20 on the other side.

[0066] Measure the resistance 10 during hydrate formation. When measuring the resistance 10, the stiffness change of the longitudinal wave magnitude will also be used to explore the stability of the hydrate-bearing particles.

[0067]

[0068] Among them, in the above formula, R is the medium resistance, with the unit of Ω, V1 is the voltage, the unit of V1 is V, V2 is the voltage, the unit of V2 is V, and R* is the known resistance of the series resistor, with the unit of Ω.

[0069] The stability of the hydrate particles will also be explored by using the stiffness change of the P-wave amplitude. The first piezoelectric crystal 6 and the second piezoelectric crystal 7 generate P-waves. The first piezoelectric crystal 6 and the second piezoelectric crystal 7 will be connected to a sine signal exciter 8. The model of the signal exciter 8 is 33509B, Agilent, operating at a resonant frequency of about 60 kHz, and a signal amplifier 9 is used to measure the amplitude of the signals generated by the first piezoelectric crystal 6 and the second piezoelectric crystal 7. The model of the signal amplifier 9 is 3944, Krohn-Hite, and it is displayed on an oscilloscope 11. The model of the oscilloscope 11 is DSOX2024, Agilent.

[0070] To quantify the anisotropy of the soil mass, two sets of horizontal bender elements 20 are installed in the reactor 1. The bender elements 20 estimate the horizontal shear modulus G by detecting the propagation speed of shear waves in the hydrate to measure respectively max,hh and the vertical shear modulus G max,hv , The shear wave propagates from the signal exciter 8 to one side of the bender element 20 in the reactor 1 into the soil mass, and after passing through the soil mass, it reaches the other side of the bender element 20. The other side of the bender element 20 senses the vibration of the shear wave and converts it into an electrical signal, which is transmitted to the signal amplifier 9 and the received signal waveform is recorded on the oscilloscope 11, including amplitude, time delay, and frequency characteristics. After collecting the complete parameters in this device, the propagation time, wave speed, amplitude attenuation, and frequency characteristics of the shear wave will be analyzed in the data acquisition system to deduce the mechanical parameters of the soil mass such as shear wave speed, elastic modulus, and damping ratio. The deformation parameters of the soil mass are recorded in real time during this process to achieve the real-time monitoring effect of hydrate formation and replacement processes.

[0071] Based on the ideal embodiments of the present invention as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A detection device including small strain monitoring and piezoelectric crystal, comprising: A reactor, wherein the reactor is provided with a gas discharge port connected to the interior thereof, and the gas discharge port is provided with a valve; A gas delivery module, which is connected to the interior of the reactor and is used to deliver carbon dioxide or methane into the reactor; A temperature control module, which is connected to the reactor and is used to control the reaction temperature in the reactor; It is characterized by further comprising: A piezoelectric detection module, which is arranged in a reactor and used to detect the replacement of hydrates, the piezoelectric detection module includes a first piezoelectric crystal, a second piezoelectric crystal, a signal exciter, a signal amplifier, a resistor and an oscilloscope, the first piezoelectric crystal and the second piezoelectric crystal are arranged relatively in the reactor, the first piezoelectric crystal and the second piezoelectric crystal are bonded with soil particles or mineral sheets, the signal exciter is respectively connected to the first piezoelectric crystal and the second piezoelectric crystal, the resistor is connected in series between the signal exciter and the second piezoelectric crystal, the second piezoelectric crystal is connected to the signal amplifier, the signal amplifier is connected to the oscilloscope, a first voltmeter is arranged between the first piezoelectric crystal and the second piezoelectric crystal, a second voltmeter is arranged between the first piezoelectric crystal, the second piezoelectric crystal and the resistor, an adjustment mechanism is arranged between the first piezoelectric crystal and the second piezoelectric crystal, and the adjustment mechanism is used to adjust the first piezoelectric crystal and the second piezoelectric crystal to be relatively close to or away from each other; and a data processing module, wherein the data processing module is respectively connected to the temperature control module, the oscilloscope, the first voltmeter and the second voltmeter signals.

2. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: It also includes a bending element monitoring module arranged in the reactor, the bending element monitoring module includes two bending element components, one of which is connected to the signal exciter, and the other is connected to the signal amplifier. The reactor is connected to the outside of the conveying module for converting carbon dioxide into liquid and conveying it into the reactor.

3. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 2, characterized in that: The conveying module includes a horizontal flow pump and an intermediate container. A piston slides inside the intermediate container. The piston divides the intermediate container into an upper chamber and a lower chamber. The upper chamber is used to store carbon dioxide, and the lower chamber is used to store liquid. The horizontal flow pump is connected to the lower chamber and is used to convey the liquid into the lower chamber.

4. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: The adjustment mechanism includes an adjustment screw, a first guide plate and a second guide plate. The adjustment screw is rotatably mounted on the reactor. One end of the adjustment screw protrudes outside the reactor. A portion of the adjustment screw is located in the reactor and is provided with two sections of external threads with opposite rotation directions. The first guide plate and the second guide plate are located in the reactor and are respectively threadedly connected to the two sections of external threads of the adjustment screw. The first piezoelectric crystal is arranged on the first guide plate, and the second piezoelectric crystal is arranged on the second guide plate. The first guide plate and the second guide plate are both slidably arranged in the reactor along the displacement direction of the first piezoelectric crystal and the second piezoelectric crystal.

5. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: A guide shaft is arranged in the reactor, and the guide shaft is arranged along the displacement direction of the first piezoelectric crystal and the second piezoelectric crystal. The first guide plate and the second guide plate are both provided with guide holes matching the guide shaft, and the guide holes on the first guide plate and the second guide plate are both arranged on the guide shaft.

6. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: The gas delivery module includes a first gas cylinder and a second gas cylinder, wherein the first gas cylinder stores carbon dioxide, and the second gas cylinder stores methane, and both the first gas cylinder and the second gas cylinder are connected to the interior of the reactor.

7. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: The temperature control module comprises a low-temperature thermostatic bath and a heat exchange tube, wherein the heat exchange tube is arranged in the reaction kettle, and the low-temperature thermostatic bath is communicated with the heat exchange tube.

8. A detection device comprising small strain monitoring and piezoelectric crystal according to claim 1, characterized in that: The reactor is provided with a visual observation window.

9. A testing method using a detection device comprising small strain monitoring and piezoelectric crystals as claimed in claim 3, characterized in that: The steps are as follows: S1. Before the test, open the upper cover of the reactor, and then place soil particles or mineral pieces on the first piezoelectric crystal and the second piezoelectric crystal in the reactor respectively; S2, start the temperature control module, signal exciter, signal amplifier, oscilloscope and data processing module, check the temperature control module, signal exciter, signal amplifier, oscilloscope and data processing module and ensure that each device is operating normally, and check the status of the gas delivery module; S3, and adjusting the distance between the soil particles or the ore pieces between the first piezoelectric crystal and the second piezoelectric crystal to a desired distance through the adjusting mechanism, and then dripping water drops between the soil particles or the ore pieces to form a cylindrical water layer; S4. During the test, cover the upper cover of the reactor, introduce methane gas into the reactor through the gas delivery module to 3Mpa, and then open the valve to discharge the gas in the reactor. Repeat the filling and discharging of gas several times to ensure that there is no other gas in the reactor 1, and check the airtightness of the reactor 1; S5, after adjusting the internal temperature of the reactor to 2°C by using the temperature control module, the gas is introduced into the reactor again through the gas delivery module until the pressure in the reactor reaches 8Mpa and the gas input is stopped; S6. Wait for hydrate to form and record the temperature and pressure. When the temperature and pressure drop significantly, it means that hydrate is forming. The hydrate formation conditions are marked. The reaction is considered complete when there is no obvious change in the temperature, pressure or oscilloscope in the reactor. S7. After the methane hydrate is generated, the temperature in the reactor is adjusted to -5° through the temperature control module. At this time, the methane hydrate has a good preservation effect; S8. Open the valve of the gas discharge port on the reactor to discharge the excess methane gas in the reactor, introduce 5Mpa carbon dioxide, and adjust the temperature in the reactor to 5-10° through the temperature control module for replacement; S9. During the replacement, the signal exciter sends an electrical signal every 20 m / s. The first piezoelectric crystal and the second piezoelectric crystal generate P waves in the reactor, and the bending element generates S waves, which are transmitted to the oscilloscope through the signal amplifier for display. The first voltmeter and the second voltmeter send the received signals to the data processing module. The replacement efficiency of the hydrate will be shown by the change of resistance. S10. If there is no obvious change in the temperature, pressure and oscilloscope in the reactor, the reaction is considered to be completed. Open the valve of the gas discharge port on the reactor to discharge the gas in the reactor, turn off the temperature control module, signal exciter, signal amplifier, oscilloscope and data processing module, open the upper cover of the reactor and clean the reactor.

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