A test system and method for coupling microwave radiation pyrolysis of coal samples with permeation CT scanning

Abstract

The application provides a test system and method for pyrolysis of coal samples by non-focused microwave radiation coupled with penetration CT scanning, and belongs to the field of in-situ coal pyrolysis. The system comprises a microwave generating system, a pyrolysis percolation cavity, a pyrolysis percolation gas injection system, a loading system, a product collection system, a data acquisition system and a cooling system. The microwave generating system emits microwaves to heat the coal samples in the pyrolysis percolation cavity and forms non-focused microwaves in the cavity to simulate the in-situ microwave pyrolysis state. The pyrolysis experiment and the percolation experiment of the coal samples can be completed by injecting a pyrolysis atmosphere or a percolation gas into the cavity through the pyrolysis percolation gas injection system. The pyrolysis percolation cavity is directly placed on a CT scanner for scanning, and the changes of the pores and fissures of the coal samples at different pyrolysis temperatures can be observed. The application can be used to analyze the evolution law of the microwave pyrolysis on the physical microstructure, the permeability and the mass and heat transfer of the coal, and overcome the defects and deficiencies of the traditional test method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal in-situ pyrolysis, and in particular relates to a test system and method for non-focused microwave radiation pyrolysis of coal samples coupled with permeation CT scanning. BACKGROUND

[0002] Coal in-situ pyrolysis is a new coal mining method that directly pyrolyzes coal in the ground and then separates oil and gas, which is an economic and environmentally friendly green and efficient way of coal development and utilization, and has attracted widespread attention from energy experts and scholars at home and abroad.

[0003] The current heating method of traditional pyrolysis is electric heating, which is heated by external heat conduction, and may cause problems such as slow heating speed, high energy consumption, and uneven temperature distribution; while microwave radiation heating is to use the interaction between microwave electromagnetic field and polar molecules or conductive components in coal to directly heat the coal block through dielectric loss or eddy current effect. The energy of this heating method directly acts on the coal block, and the inside and outside are heated at the same time, so the heating rate is fast and uniform.

[0004] Patent CN111139099A provides a microwave pyrolysis equipment, which includes a rack, a microwave generating device, a waveguide protection device, and a stirring device. It can pyrolyze a large amount of materials, each device operates independently, is easy to maintain, and has high processing efficiency, overcoming the defect that large batches of materials need to be processed in batches.

[0005] Patent CN118558271A provides a fly ash rapid continuous modification device and method based on non-focused microwave heating. The device structure includes a conveyor belt, a microwave generating device, and a shielding shell. A coaxial line is connected to the microwave generating device, and the conveyor belt is arranged below the coaxial line and inside the shielding shell, realizing continuous transportation of coal powder and modification of fly ash under the action of microwave heating.

[0006] However, the above-mentioned patents cannot simulate real geological environmental conditions, so they cannot study some characteristics of coal in the laboratory, which restricts their application in the laboratory. SUMMARY

[0007] To solve the above technical problems, the present application provides a test system and method for non-focused microwave radiation pyrolysis of coal samples coupled with permeation CT scanning.

[0008] The technical scheme adopted by the application is: a test system for coal sample pyrolysis under non-focused microwave radiation coupled with permeation CT scanning, comprising a microwave generating system, a pyrolysis permeation cavity, a loading system, a product collection system, a data acquisition system and a cooling system, the pyrolysis permeation cavity is connected with the loading system, a coal sample is placed in the pyrolysis permeation cavity, a glass fiber spacer, an upper graphite packing, a lower graphite packing, an activated carbon layer and a closed support ring are arranged in the pyrolysis permeation cavity, the closed support ring is arranged in the middle of the pyrolysis permeation cavity and is used for wrapping the coal sample, the outer side of the closed support ring is wrapped with the activated carbon layer, the upper and lower sides of the closed support ring and the activated carbon layer are respectively provided with the upper graphite packing and the lower graphite packing, the glass fiber spacer is arranged at the top of the pyrolysis permeation cavity, and a wave absorbing assembly is arranged at the lower end of the coal sample.

[0009] The pyrolysis permeation cavity is provided with an upper outlet, a lower outlet and an in-kettle temperature measuring point, the upper outlet and the lower outlet are respectively provided with a flow sensor, and the in-kettle temperature measuring point is provided with a thermocouple.

[0010] The loading system comprises a loading frame, a composite oil cylinder is mounted on the loading frame, the microwave generating system is mounted on the cylinder barrel of the composite oil cylinder, pressure sensors are arranged at the bottom of the glass fiber spacer and the inner side of the activated carbon layer, and the pressure sensors are used for measuring the pressure of the axial pressure and the confining pressure applied by the loading system.

[0011] The product collection system is connected with the upper outlet through a gas pipe.

[0012] The data acquisition system is connected with the two flow sensors, the thermocouple and the two pressure sensors through wires.

[0013] The cooling system is arranged at the bottom of the pyrolysis permeation cavity.

[0014] Further, a pyrolysis permeation gas injection system is further included, the pyrolysis permeation gas injection system is connected with the lower outlet through a gas pipe, permeation gas is injected, and a permeation pressure is set.

[0015] Further, the wave absorbing assembly is composed of a ceramic fiber heat insulation layer and a silicon carbide-based absorbing layer, the ceramic fiber heat insulation layer is used for transmitting microwaves and insulating and heat insulating the coal sample, and the silicon carbide-based absorbing layer is used for absorbing microwaves penetrating the coal sample.

[0016] Further, the loading system is composed of an axial loading system and a lateral loading system, an upper table and a lower table are mounted on the loading frame, the composite oil cylinder is mounted on the upper table, the composite oil cylinder is connected with a hydraulic pump station, the composite oil cylinder comprises an inner cylinder and a ring cylinder, a cylinder barrel is arranged below the composite oil cylinder, an inner wall aluminum alloy bushing, an upper end inner wall pressure head and an upper end outer wall pressure head are arranged on the outer side of the cylinder barrel from inside to outside, the inner cylinder in the composite oil cylinder transmits pressure to the upper end inner wall pressure head on the cylinder barrel, so as to provide axial pressure for the coal sample, and the ring cylinder in the composite oil cylinder transmits pressure to the upper end outer wall pressure head on the cylinder barrel, so as to provide confining pressure for the coal sample.

[0017] Furthermore, the microwave generating system is composed of a microwave generator, a microwave generating end and a metal refraction plate, the microwave generator is mounted on the cylinder, and the microwave generating end extends into the cylinder;

[0018] The microwaves emitted by the microwave generator are directed toward the metal refraction plate through the microwave generating end to change the transmission direction of the microwave energy, thereby heating the coal sample.

[0019] Furthermore, the upper end of the pyrolysis seepage cavity is connected to the upper end gland of the loading system through bolts, and a gasket is provided between the upper end of the cavity and the upper end gland.

[0020] Furthermore, the data acquisition system generates dynamic curves of the pressure loading process, temperature change, and pore pressure change during the test by real-time collecting and recording the temperature in the pyrolysis seepage cavity, the axial pressure and confining pressure provided by the loading system, the osmotic pressure and gas flow rate when the pyrolysis seepage gas injection system injects gas, and the gas flow rate data at the outlet, and controls and outputs them.

[0021] Furthermore, the cooling system includes a lower water cooling device, and a water inlet and a water outlet are respectively provided on both sides of the lower water cooling device.

[0022] Furthermore, the metal refraction plate is made of high-purity aluminum, the surface is anodized, and the tilt angle is 45°±2°.

[0023] A test method for coupling non-focused microwave radiation pyrolysis of coal samples with penetrant CT scanning, using the test system for coupling non-focused microwave radiation pyrolysis of coal samples with penetrant CT scanning, comprises the following steps:

[0024] Step 1: Before the experiment, the coal sample was processed;

[0025] Step 2: Place the coal sample into the pyrolysis seepage chamber and seal it, tightening the bolts to prevent gas leakage;

[0026] Step 3: Connect the pyrolysis permeate gas injection system, product collection system, and data acquisition system, and use the loading system to perform axial pressure and confining pressure loading;

[0027] Step 4: inject pyrolysis atmosphere through the lower outlet, start the cooling system, start the microwave generation system to pyrolyze the coal sample, set the required pyrolysis temperature, keep the temperature for a period of time when the set pyrolysis temperature is reached, and start the product collection system to complete the collection of pyrolysis products;

[0028] Step 5: Scan the pyrolyzed coal sample with a CT scanner to analyze the effect of microwave heating on the changes in the pores and cracks of the coal sample;

[0029] Step 6: Start the pyrolysis permeation gas injection system to conduct a permeation experiment on the coal sample after pyrolysis, monitor, collect and process data in real time, and conduct a permeability test on the coal sample;

[0030] Step 7: Use the data acquisition system to analyze and process the experimental data. At this point, the non-focused microwave radiation pyrolysis coal sample coupled penetration CT scanning test is completed.

[0031] The beneficial effects of this application compared to the prior art are:

[0032] 1. This application can simulate the in-situ microwave pyrolysis state of coal samples. Specifically, the microwave absorbing component (silicon carbide-based absorption layer and ceramic fiber insulation layer) at the bottom of the cavity absorbs the transmitted microwaves, reduces reflection interference, forms a non-focused microwave field, and simulates the in-situ microwave pyrolysis of coal.

[0033] Second, this application can perform real stress simulation, and the experimental data is more comprehensive. The loading system can accurately reproduce the actual stress state of the coal seam. The cavity integrates thermocouples (accuracy ±0.5°C), pressure sensors and flow sensors to monitor temperature, pressure and gas flow in real time. Combined with the PLC control system, dynamic closed-loop adjustment is achieved. The comprehensiveness of data collection far exceeds that of traditional equipment.

[0034] This application integrates microwave pyrolysis, coal sample CT scanning, and permeability testing. The titanium alloy cavity (with excellent transmission properties) can be directly transferred to CT scanning without repeated coal sample disassembly, enabling triaxial stress scanning before and after pyrolysis. The lower outlet supports N2 atmosphere control, meeting the needs of multiple experiments such as permeability testing (pressure drop method) and pyrolysis gas extraction (condensation separation). Its functional scalability significantly exceeds that of a single pyrolysis device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present application will be further described below with reference to the accompanying drawings:

[0036] Figure 1 A schematic diagram of the overall structure of the device provided in the embodiment of the present application;

[0037] Figure 2 for Figure 1 Schematic diagram of the structure of the pyrolysis seepage cavity and the loading system;

[0038] In the figure: 1 is a microwave generating system; 2 is a pyrolysis permeation cavity; 3 is a loading system; 4 is a pyrolysis permeation gas injection system; 5 is a product collection system; 6 is a data acquisition system; 7 is a cooling system; 101 is a microwave generator; 102 is a microwave generating end; 103 is a metal refractive plate; 201 is a coal sample; 202 is the upper end of the cavity; 203 is a closed support ring; 204 is a glass fiber spacer; 205 is an upper graphite disc root; 206 is a lower graphite disc root; 207 is an activated carbon layer; 208 is a ceramic fiber heat insulation layer; 209 is a silicon carbide-based absorption layer; 210 is an in-pot temperature measuring point; 211 is a lower outlet; 212 is an upper outlet; 301 is an upper table; 302 is a lower table; 303 is a loading frame; 304 is a composite oil cylinder; 305 is an inner cylinder; 306 is a ring cylinder; 307 is an upper end inner wall pressure head; 308 is an upper end outer wall pressure head; 309 is an inner wall aluminum alloy bushing; 310 is an upper end gland; 311 is a bolt; 312 is a gasket; 701 is a lower water cooling device; 702 is a water inlet; 703 is a water outlet. DETAILED DESCRIPTION

[0039] As shown in Figure 1 and 2 , the application provides a non-focusing microwave radiation pyrolysis coal sample coupling permeation CT scanning test system, which can simulate real geological environment conditions, according to the conditions of ground stress and temperature field under mineral geological occurrence conditions, can meet the simulation of in-situ microwave radiation pyrolysis of coal sample in the laboratory, and can perform CT scanning and permeability detection, and analyze the advanced, efficient, intuitive, reliable and safe test system of the change of pore and fracture characteristics and permeation characteristics of coal.

[0040] As shown in Figure 1As shown, the test system for pyrolysis of coal sample by non-focused microwave radiation coupled with permeation CT scanning proposed in the present application mainly comprises a microwave generating system 1, a pyrolysis permeation cavity 2, a loading system 3, a pyrolysis permeation gas injection system 4, a product collection system 5, a data acquisition system 6 and a cooling system 7. The pyrolysis permeation cavity 2 is an important component of the test system. The entire cavity is made of titanium alloy (excellent transmission performance). The upper end 202 of the cavity is connected to the upper end gland 310 of the loading system 3 through the bolt 311. A gasket 312 is arranged between the upper end 202 of the cavity and the upper end gland 310. After the bolt 311 is tightened, the air tightness of the entire cavity can be ensured. The pyrolysis permeation cavity 2 is internally provided with a glass fiber spacer 204, an upper graphite packing 205, a lower graphite packing 206, an activated carbon layer 207 and a closed support ring 203 for supporting and fixing the coal sample 201. The glass fiber spacer 204 can transmit microwaves and at the same time can transmit pressure to make the axial pressure act on the coal sample 201 (cylindrical coal sample). The cavity is provided with an upper outlet 212, a lower outlet 211 and an in-cavity temperature measuring point 210. The flow sensors are arranged on the upper outlet 212 and the lower outlet 211. The thermocouple is arranged on the in-cavity temperature measuring point 210 to measure the flow of the gas at the upper outlet 212 and the lower outlet 211 and the temperature in the cavity in real time. The lower end of the place where the coal sample 201 is placed is provided with a wave absorption assembly which comprises a ceramic fiber heat insulation layer 208 and a silicon carbide-based absorption layer 209. The ceramic fiber heat insulation layer 208 can transmit microwaves and has the function of heat insulation and heat insulation to block the conduction heating of the silicon carbide-based heat to the coal sample 201. The silicon carbide-based absorption layer 209 can absorb the microwaves penetrating the coal sample 201 to reduce the reflection of the microwaves in the furnace cavity and form a non-focused microwave field to simulate the state of in-situ microwave radiation heating of the coal bed.

[0041] The microwave generating system 1 comprises a microwave generator 101, a microwave generating end head 102 and a metal refracting plate 103. The microwave generator 101 can emit microwaves. The microwaves are emitted to the metal refracting plate 103 through the microwave generating end head 102 to change the transmission direction of the microwave energy so as to heat the coal sample 201. The material of the metal refracting plate 103 is high-purity aluminum. The surface is subjected to anodic oxidation treatment to improve the microwave reflection efficiency. The inclination angle is 45°±2° to ensure that the microwaves uniformly cover the surface of the coal sample 201.

[0042] The loading system 3 is composed of an axial loading system and a lateral loading system, which are composed of a loading frame 303 containing an upper platform 301 and a lower platform 302, a composite oil cylinder 304 installed on the upper platform 301, and a hydraulic pump station connected with the composite oil cylinder 304, the composite oil cylinder 304 including an inner cylinder 305 and a ring cylinder 306, a cylinder barrel is arranged below the composite oil cylinder 304, the cylinder barrel is provided with an inner wall aluminum alloy bushing 309, an upper end inner wall pressure head 307 and an upper end outer wall pressure head 308 from inside to outside, a microwave generator 101 is installed on the cylinder barrel, and a microwave generating end head 102 extends into the cylinder barrel, the upper end inner wall pressure head 307 on the cylinder barrel is pressurized by the inner cylinder 305 in the composite oil cylinder 304, axial pressure is provided for the coal sample 201, and the upper end outer wall pressure head 308 on the cylinder barrel is pressurized by the ring cylinder 306 in the composite oil cylinder 304, confining pressure is provided for the coal sample 201.

[0043] The axial loading system transmits pressure to the upper end inner wall pressure head 307 on the cylinder barrel by the inner cylinder 305 in the composite oil cylinder 304, and axial pressure is applied to the coal sample 201 through the glass fiber gasket 204; the confining pressure principle of the lateral loading system is that the confining pressure medium of the closed support ring 203 and the upper graphite packing 205 and the lower graphite packing 206 is arranged on the lateral side of the coal sample 201, lateral loading of the ring cylinder 306 of the composite oil cylinder 304 is accepted by the upper end outer wall pressure head 308, and confining pressure is applied, the loading system 3 can provide axial pressure and confining pressure for the coal sample 201 after being pressurized, the vertical stress and the horizontal stress of the coal seam underground are simulated, and the real geological conditions of the coal seam are restored.

[0044] Pressure sensors are arranged at the bottom of the glass fiber gasket 204 and the inner side of the activated carbon layer 207, respectively, for measuring the pressure of the axial pressure and the confining pressure applied by the loading system 3.

[0045] The pyrolysis permeation gas injection system 4 is connected with the lower outlet 211 through a gas pipe, can inject permeation gas (N2), set the required permeation pressure, and at the same time provide N2 atmosphere for pyrolysis.

[0046] The product collection system 5 is connected with the upper outlet 212 through a gas pipe, separates the generated tar and coal gas through the condensing device in it, and performs oil and gas component analysis.

[0047] The data acquisition system 6 adopts a PLC control system, the PLC control system is connected with the flow sensors and thermocouples arranged at the upper outlet 212, the lower outlet 211 and the temperature measuring points 210 in the kettle, and two pressure sensors, real-time acquisition and recording of the temperature in the cavity, the axial pressure and the confining pressure provided by the loading system 3, the permeation pressure and the gas flow when the pyrolysis permeation gas injection system 4 injects gas, and the gas flow of the outlet, and generation of the pressure loading process dynamic curve, the temperature change dynamic curve, and the pore pressure change dynamic curve in the test process, in order to control and output.

[0048] The cooling system 7 is mainly a lower water cooling device 701, water is fed from a water inlet 702 arranged on the side of the lower water cooling device 701, and flows out from a water outlet 703 opposite to the water inlet 702.

[0049] The microwave generator 101 in the microwave generating system 1 in the embodiment can emit an industrial standard frequency of 2.45 GHz, and the power range is 800-3000 W, which can be dynamically adjusted according to experimental requirements.

[0050] In the embodiment, the coal sample 201 can be a standard cylindrical coal sample with a diameter of 50 mm and a height of 100 mm.

[0051] In the embodiment, the pressure range of the loading system 3 is 0-50 MPa, the pressure sensor accuracy is ±0.1 MPa, and closed-loop control is supported.

[0052] In the embodiment, the permeation pressure regulation range of the pyrolysis permeation gas injection system 4 is 0.1-6 MPa, and the gas flow control accuracy is ±0.01 L / min.

[0053] In the embodiment, the working temperature of the condensing device of the product collection system 5 is-20℃-5℃, the tar separation efficiency is ≥95%, and the gas collection bag volume is 10-50 L.

[0054] In the embodiment, the data acquisition system 6 collects sensor data at a frequency of ≥1 Hz and generates a dynamic curve.

[0055] In the wave-absorbing assembly of the embodiment, the thickness of the ceramic fiber thermal insulation layer 208 is 20 mm, the thickness of the silicon carbide-based absorbing layer 209 is 30 mm, and the microwave absorption rate is ≥90%.

[0056] The application also provides a test method for coupling and permeating CT scanning of a coal sample by non-focused microwave radiation pyrolysis, and the test method can simulate real geological environmental conditions by using the non-focused microwave radiation pyrolysis coal sample coupling and permeation CT scanning test system. First, the coal sample 201 is processed to the required size, and then sealed in the pyrolysis permeation cavity 2, and loaded to the set stress value by the loading system 3, and different temperature nodes are set for microwave radiation heating. When the temperature reaches the set value and stabilizes for 2 hours, the CT scanner is used to observe the changes of the coal sample 201 after pyrolysis, and the CT scanning experiment is carried out; the pyrolysis permeation gas injection system 4 can also be started, the required permeation pressure is set, the change of the gas flow is observed, and the coal sample permeation experiment is carried out, and the specific implementation steps are as follows:

[0057] Step one: before the experiment, the coal sample 201 is processed to form a standard cylindrical coal sample;

[0058] Step two: Put the coal sample 201 into the pyrolysis permeation cavity 2 and seal it, tighten the bolt 311 to prevent gas leakage;

[0059] Step three: Connect the pyrolysis permeation gas injection system 4, the product collection system 5 and the data acquisition system 6, and use the loading system 3 to load the axial pressure and the confining pressure;

[0060] Step four: Inject the pyrolysis atmosphere (N2) through the lower outlet 211, start the cooling system 7, start the microwave generating system 1 to pyrolyze the coal sample 201, set the required pyrolysis temperature, keep the temperature for 2 hours when the set pyrolysis temperature is reached, and start the product collection system 5 to complete the collection of pyrolysis products;

[0061] Step five: Perform CT scanning to scan the coal sample 201 after pyrolysis, and analyze the influence of microwave heating on the change of the pore and fracture of the coal sample 201;

[0062] Step six: Start the pyrolysis permeation gas injection system 4 to perform the permeation experiment of the coal sample 201 after pyrolysis, and monitor, collect and process the data in real time to test the permeability of the coal sample 201;

[0063] Step seven: Use the data acquisition system 6 to analyze and process the experimental data, and thus the non-focused microwave radiation pyrolysis coal sample coupling permeation CT scanning experiment is completed.

[0064] The spatial resolution of the CT scanner matched with the embodiment is ≤10μm, and the scanning interval can be determined according to the experimental requirements. CT scanning under three-dimensional stress can be performed according to different temperature nodes.

[0065] The experimental method of the present application will be described below according to specific embodiments.

[0066] In the embodiment, a standard cylindrical coal sample with a diameter of 50mm and a height of 100mm is taken as an example. The temperature loading is selected as 450℃. The non-focused microwave radiation pyrolysis coal sample coupling permeation CT scanning test system is used for testing, including the following steps:

[0067] Step one: Before the experiment, the coal sample 201 is processed to form a standard cylindrical coal sample with a diameter of 50mm and a height of 100mm;

[0068] Step two: Put the coal sample 201 into the pyrolysis permeation cavity 2 and seal it, tighten the bolt 311 to prevent gas leakage;

[0069] Step three: Connect the various monitoring sensors, use the loading system 3 to load the axial pressure and the confining pressure, set the axial pressure to 80MPa and the confining pressure to 64MPa;

[0070] Step four: inject pyrolysis atmosphere (N2) through the lower outlet 211, start the microwave generating system 1 to pyrolyze the coal sample 201, set the required pyrolysis temperature, keep the temperature for 2 hours when reaching the set pyrolysis temperature, and start the product collection system 5 to complete the collection of pyrolysis products;

[0071] Step five: perform CT scanning to scan the coal sample 201 after pyrolysis, and analyze the influence of microwave heating on the change of pores and fissures of the coal sample 201;

[0072] Step six: start the pyrolysis permeation gas injection system 4 to perform the permeation experiment of the coal sample 201 after pyrolysis, and real-time monitor, collect and process data to test the permeability of the coal sample 201;

[0073] Step seven: use the data acquisition system 6 to analyze and process the experimental data, and thus the non-focused microwave radiation pyrolysis coal sample coupling permeation CT scanning experiment is completed.

[0074] In summary, the present application can be used for the experimental study of microwave radiation pyrolysis coupling permeation CT scanning of coal and rock, and the experimental system of the present application is also suitable for non-focused microwave pyrolysis and permeation CT coupling experiment of shale and other porous medium materials.

[0075] Compared with the traditional device and method, the present application can simulate the in-situ microwave pyrolysis state of the coal sample 201 by setting the wave-absorbing assembly around and at the bottom of the cavity, absorb the microwave penetrating the coal sample 201, reduce the reflection interference of the microwave in the furnace cavity, and finally form a non-focused microwave heating field; at the same time, the experimental device is provided with a triaxial loading system for the coal sample 201 to simulate the real geological conditions and perform in-situ pyrolysis experiment; the pyrolysis permeation cavity is made of titanium alloy (excellent transmission performance) to facilitate the in-situ CT scanning experiment of the coal sample 201, and the lower outlet at the lower side of the pyrolysis permeation cavity 2 is connected with the pyrolysis permeation gas injection system 4 to inject permeation gas (N2) to facilitate the permeation experiment of the coal sample 201.

[0076] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A test system for unfocused microwave radiation pyrolysis of coal samples coupled with penetration CT scanning, characterized by: The invention comprises a microwave generating system (1), a pyrolysis seepage cavity (2), a loading system (3), a product collecting system (5), a data acquisition system (6) and a cooling system (7); the pyrolysis seepage cavity (2) is connected to the loading system (3); a coal sample (201) is placed in the pyrolysis seepage cavity (2); a glass fiber spacer (204), an upper graphite packing (205), a lower graphite packing (206), an activated carbon layer (207) and a closed support ring ( 203), wherein the closed support ring (203) is arranged in the middle of the pyrolysis seepage cavity (2) for wrapping the coal sample (201), the outer side of the closed support ring (203) is wrapped with an activated carbon layer (207), the upper and lower sides of the closed support ring (203) and the activated carbon layer (207) are respectively provided with an upper graphite packing (205) and a lower graphite packing (206), a glass fiber spacer (204) is arranged on the top of the pyrolysis seepage cavity (2), and a wave absorbing component is provided at the lower end of the coal sample (201); The pyrolysis seepage cavity (2) is provided with an upper outlet (212), a lower outlet (211) and a temperature measuring point (210) in the kettle. Flow sensors are provided on the upper outlet (212) and the lower outlet (211), and a thermocouple is provided on the temperature measuring point (210) in the kettle. The loading system (3) includes a loading frame (303), a composite oil cylinder (304) is installed on the loading frame (303), a microwave generating system (1) is installed on the cylinder of the composite oil cylinder (304), and pressure sensors are respectively provided at the bottom of the glass fiber spacer (204) and the inner side of the activated carbon layer (207) for measuring the axial pressure and confining pressure applied by the loading system (3); The product collection system (5) is connected to the upper outlet (212) via an air pipe; The data acquisition system (6) is connected to two flow sensors, a thermocouple, and two pressure sensors via wires; The cooling system (7) is arranged at the bottom of the pyrolysis seepage cavity (2).

2. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 1, characterized in that: The invention also includes a pyrolysis permeation gas injection system (4), which is connected to the lower outlet (211) through a gas pipe, injects permeation gas, and sets the permeation pressure.

3. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 2, characterized in that: The absorbing component consists of a ceramic fiber insulation layer (208) and a silicon carbide-based absorption layer (209), wherein the ceramic fiber insulation layer (208) is used to transmit microwaves and provide thermal insulation for the coal sample (201), and the silicon carbide-based absorption layer (209) is used to absorb microwaves that penetrate the coal sample (201).

4. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 2, characterized in that: The loading system (3) is composed of an axial loading system and a lateral loading system. An upper table (301) and a lower table (302) are installed on the loading frame (303). A composite oil cylinder (304) is installed on the upper table (301). The composite oil cylinder (304) is connected to a hydraulic pump station. The composite oil cylinder (304) includes an inner cylinder (305) and an annular cylinder (306). A cylinder barrel is provided below the composite oil cylinder (304). The outer side of the cylinder barrel is from the inner to the outer side. An inner wall aluminum alloy bushing (309), an upper inner wall pressure head (307) and an upper outer wall pressure head (308) are provided on the outside. Pressure is transmitted to the upper inner wall pressure head (307) on the cylinder barrel through the inner cylinder (305) in the composite oil cylinder (304), thereby providing axial pressure for the coal sample (201). Pressure is transmitted to the upper outer wall pressure head (308) on the cylinder barrel through the annular cylinder (306) in the composite oil cylinder (304), thereby providing confining pressure for the coal sample (201).

5. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 4, characterized in that: The microwave generating system (1) is composed of a microwave generator (101), a microwave generating end (102), and a metal refraction plate (103); the microwave generator (101) is mounted on the cylinder, and the microwave generating end (102) extends into the cylinder; The microwaves emitted by the microwave generator (101) are directed toward the metal refraction plate (103) through the microwave generating end (102) to change the transmission direction of the microwave energy, thereby heating the coal sample (201).

6. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 2, characterized in that: The upper end (202) of the pyrolysis seepage cavity (2) is connected to the upper end pressure cover (310) of the loading system (3) via bolts (311), and a gasket (312) is provided between the upper end (202) of the cavity and the upper end pressure cover (310).

7. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 2, characterized in that: The data acquisition system (6) collects and records the temperature in the pyrolysis seepage cavity (2), the axial pressure and confining pressure provided by the loading system (3), the osmotic pressure and gas flow rate when the pyrolysis seepage gas injection system (4) injects gas, and the gas flow rate data at the outlet in real time, and generates a dynamic curve of the pressure loading process, a dynamic curve of the temperature change, and a dynamic curve of the pore pressure change during the test, and controls and outputs them.

8. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 2, characterized in that: The cooling system (7) comprises a lower water cooling device (701), and a water inlet (702) and a water outlet (703) are respectively provided on both sides of the lower water cooling device (701).

9. The test system for coal sample pyrolysis by unfocused microwave radiation coupled with penetration CT scanning according to claim 5, characterized in that: The metal refraction plate (103) is made of high-purity aluminum, the surface of which is anodized, and the inclination angle is 45°±2°.

10. A method for testing coal samples by unfocused microwave radiation pyrolysis coupled with penetrant CT scanning, using the test system for unfocused microwave radiation pyrolysis coupled with penetrant CT scanning according to any one of claims 2 to 9, characterized in that: The following steps are involved: Step 1: Before the experiment, the coal sample (201) was processed; Step 2: Place the coal sample (201) into the pyrolysis seepage cavity (2) and seal it, and tighten the bolts (311) to prevent gas leakage; Step 3: Connect the pyrolysis permeation gas injection system (4), the product collection system (5) and the data acquisition system (6), and use the loading system (3) to perform axial pressure and confining pressure loading; Step 4: injecting pyrolysis atmosphere through the lower outlet (211), turning on the cooling system (7), starting the microwave generating system (1) to pyrolyze the coal sample (201), setting the desired pyrolysis temperature, keeping the temperature for a period of time when the set pyrolysis temperature is reached, and turning on the product collecting system (5) to complete the collection of pyrolysis products; Step 5: Scan the pyrolyzed coal sample (201) through a CT scanner to analyze the effect of microwave heating on the changes in pores and cracks in the coal sample (201); Step 6: Start the pyrolysis permeation gas injection system (4), conduct a permeation experiment on the coal sample (201) after pyrolysis, monitor, collect and process data in real time, and conduct a permeability test on the coal sample (201); Step 7: Analyze and process the experimental data using the data acquisition system (6). At this point, the non-focused microwave radiation pyrolysis coal sample coupled with penetration CT scanning test is completed.

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