High-temperature and high-pressure fluid displacement test method capable of monitoring deformation of coal body

Abstract

The invention discloses a high-temperature and high-pressure fluid displacement test method capable of monitoring deformation of a coal body, which comprises the following steps: S1, loading a sample: cutting a raw coal block into a cylindrical sample, and loading the cylindrical sample into a support sleeve; s2, device assembling is conducted, specifically, the supporting sleeve is arranged in a clamping assembly, device assembling is completed, and then injection conditions are set through an injection system; s3, starting a test, injecting a high-temperature and high-pressure fluid into the sample through an injection system to complete the test, recording axial and radial displacement changes of the sample, and analyzing the deformation condition of the sample; s4, repeatedly testing, respectively changing the injection conditions, repeatedly testing, and recording the axial and radial displacement changes of the sample when each condition is changed. In a coal body displacement test, the deformation of a coal body is monitored, the deformation condition of a test piece is analyzed, the deformation condition of the coal body under different injection conditions is researched by changing injection conditions, and the change rule of mechanical properties after high-temperature and high-pressure fluid is injected into a coal rock body is analyzed.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground resource exploitation, and particularly relates to a high-temperature and high-pressure fluid displacement test method capable of monitoring coal body deformation. Background Technique

[0002] China's current energy consumption structure still mainly relies on coal in the short term, and the traditional utilization method of coal is combustion for power generation, which will release a large amount of polluting gases such as dust, nitrogen oxides, sulfur oxides, and greenhouse gases, resulting in serious environmental problems. Therefore, domestic and foreign scholars are committed to developing green, clean, and efficient coal mining technologies. Underground coal gasification (UCG) is a coal mining method that burns coal in place underground in a controlled manner and converts it into gas. This technology uses redox reactions to convert coal resources underground into combustible gases (CO, CH4, H2), which can reduce the cost of coal mining, reduce environmental pollution, and carbon dioxide emissions. Among them, supercritical water gasification is a technology with broad application prospects. Supercritical water has unique physical and chemical properties, and its density, solubility, viscosity, and diffusion coefficient are quite different from those of water under standard conditions. All kinds of gases and organic compounds can be dissolved in supercritical water, which theoretically avoids the generation of pollutants during the traditional coal combustion process.

[0003] Injecting high-temperature and high-pressure fluid into the coal body will change the physical and chemical properties, mechanical properties, internal structure, etc. of the coal and rock mass, reduce the strength of the coal and rock mass, change its stress environment, which may cause the coal and rock strata to slip, affect the stability of the strata, and may even induce earthquakes in severe cases. Summary of the Invention

[0004] The present invention intends to provide a high-temperature and high-pressure fluid displacement test method capable of monitoring coal body deformation. By simulating the test of high-temperature and high-pressure fluid displacing the coal body, the deformation of the coal and rock mass during the injection process of high-temperature and high-pressure fluid is studied, and then the mechanical characteristics and strength change laws of the coal body are analyzed.

[0005] For this purpose, the technical solution adopted by the present invention is as follows: A high-temperature and high-pressure fluid displacement test method capable of monitoring coal body deformation, comprising the following steps:

[0006] S1: Sample loading. Cut the raw coal block into a cylindrical sample, then process it through a grinding machine to make the flatness of the sample end surface within ±0.02 mm, and then load the sample into a flexible support sleeve.

[0007] S2: Device assembly. A high-temperature confining pressure sleeve is sleeved outside the support sleeve, then the whole is placed into the clamping assembly, and sealed through a sealing structure. Then, a radial monitoring and detection sensor and an axial detection sensor are installed as required. Then, the fluid injection pressure, injection rate, injection temperature, and fluid injection type are set through the injection system.

[0008] S3: Start the test. Inject high-temperature and high-pressure fluid into the specimen through the injection system to complete the test. Meanwhile, record the axial and radial displacement changes of the specimen through the radial monitoring detection sensor and the axial detection sensor, and analyze the deformation of the specimen;

[0009] S4: Repeat the test. Change the types of injected fluid, the pressure of injected fluid, and the temperature of injected fluid respectively, repeat the test, and record the axial and radial displacement changes of the specimen when each condition changes, so as to analyze the deformation law of the coal and rock mass after injecting high-temperature and high-pressure fluid.

[0010] As an optimization of the above solution, the clamping structure includes a mounting plate and a ductile specimen tube. The specimen tube is arranged with upper and lower through holes. A pressurizing system for realizing triaxial pressurization of the specimen is arranged on the clamping structure; the pressurizing system includes a high-temperature circumferential pressure sleeve arranged between the specimen tube and the support sleeve, and an axial pressure mounting plate arranged below the mounting plate through a connecting column. The high-temperature circumferential pressure sleeve is equipped with a circumferential pressure tracking system, and an axial pressure cylinder is arranged on the axial pressure mounting plate.

[0011] Further preferably, the sealing structure includes floating plugs arranged at the upper and lower ends of the specimen tube. Between each floating plug and the specimen tube, multiple high-temperature gaskets and double V-shaped combined graphite components are sequentially arranged from inside to outside. A bolt pre-tightening and top-tightening structure for ensuring reliable sealing of the sealing structure is arranged at the end of each floating plug. An outlet for fluid injection or an inlet communicated with the injection system is arranged in the floating plug, and the outlet and the inlet are respectively arranged in different floating plugs.

[0012] Further preferably, the heating component includes a heating tile sleeved outside the specimen tube, and a heat preservation sleeve is arranged outside the heating tile.

[0013] Further preferably, the bolt pre-tightening and top-tightening structure includes an upper bolt pre-tightening and top-tightening structure and a lower bolt pre-tightening and top-tightening structure corresponding to the upper and lower floating plugs. The upper bolt pre-tightening and top-tightening structure includes a first flange sleeved on the upper end of the specimen tube and a second flange sleeved on the upper end of the upper floating plug. The first flange and the second flange are connected by mounting bolts. A T-shaped upper top block is arranged at a position close to the upper end of the floating plug, and the lower end of the upper top block can be inserted into the upper end of the specimen tube. A lower notch for the upper top block to be inserted into is arranged at the lower end of the second flange, and an upper top-tightening bolt capable of pressing on the upper top block is arranged on the second flange;

[0014] The lower bolt pre-tightening and jacking structure includes a third flange sleeved on the lower end of the specimen tube and a fourth flange sleeved on the position near the lower end of the lower floating plug. The third flange is arranged on the mounting plate located at its lower end. The upper end of the fourth flange is located inside the mounting plate. At the position near the lower end of the lower floating plug, a T-shaped lower jacking block is arranged, and the upper end of the lower jacking block can be inserted into the lower end of the specimen tube. An upper notch for the lower jacking block to be inserted into is arranged at the upper end of the fourth flange. A lower jacking bolt capable of jacking on the lower jacking block is arranged on the fourth flange.

[0015] Further preferably, at least two rows of radial monitoring sensors are provided, and at least four radial monitoring sensors are provided in each row in different directions. The radial monitoring sensors pass through the specimen tube and then contact the specimen. The radial detection sensors are arranged on the sensor bracket, and the sensor bracket is arranged on the mounting plate; the axial monitoring sensor is arranged between the axial pressure mounting plate and the detection plate.

[0016] Further preferably, the mounting plate is arranged on the flipping assembly. The flipping assembly includes a flipping bracket. Horizontal flipping shafts are arranged at both ends of the mounting plate, and the other ends of the flipping shafts are rotatably arranged on the flipping seats. The flipping seats are arranged on the flipping bracket. A traveling mechanism for driving the whole flipping assembly to move and fixing the position after moving is arranged at the bottom of the flipping bracket.

[0017] Further preferably, the injection system includes a storage container for containing fluid, a constant pressure pump for realizing fluid flow, a heater for realizing fluid heating, and a fluid buffer tank for ensuring that the input fluid is in a supercritical state. The storage container, the constant pressure pump, the heater, and the fluid buffer tank are sequentially connected through an injection pipeline. A monitoring structure for monitoring its pressure and temperature is arranged on the fluid buffer tank. A pressure vessel for buffering pressure fluctuations during heating is connected in parallel to the heater. A control valve is arranged on the fluid buffer tank.

[0018] The beneficial effects of the present invention: In the coal body displacement test, the deformation of the coal body is monitored, the deformation of the specimen is analyzed, by changing the injection conditions, the deformation of the coal body under different injection conditions is studied, and the change law of the mechanical properties of the coal and rock mass after injecting high-temperature and high-pressure fluid is analyzed. Description of the Drawings

[0019] Figure 1 is the process schematic diagram of the present invention.

[0020] Figure 2 is the schematic diagram of the test device in the present invention.

[0021] Figure 3 is the schematic diagram of the clamping structure in the present invention.

[0022] Figure 4 This is a three-dimensional schematic diagram of the clamping structure in the present invention.

[0023] Figure 5 This is a schematic diagram of the clamping structure and the flipping assembly in the present invention.

[0024] Figure 6 This is a schematic diagram of the pressure vessel in the present invention.

[0025] Reference numerals: inlet - 1, outlet - 2, specimen tube - 3, mounting disc - 4, support sleeve - 5, floating plug - 6, high - temperature gasket - 7, graphite assembly - 8, provided with inlet - 9, first flange - 10, second flange - 11, upper top block - 12, upper tightening bolt - 13, third flange - 14, fourth flange - 15, lower top block - 16, high - temperature ring pressing sleeve - 20, connecting column - 21, axial pressure mounting plate - 22, axial pressure cylinder - 23, cooling sleeve - 24, radial monitoring sensor - 25, axial monitoring sensor - 26, sensor bracket - 27, detection plate - 28, flipping bracket - 29, flipping shaft - 30, flipping seat - 31, traveling mechanism - 32, storage container - 33, constant - pressure pump - 34, heater - 35, fluid buffer tank - 36, pressure vessel - 37, base - 37a, cylinder - 37b, piston - 37c, pressure cap - 37d, plug - 37e, control valve - 38, lower tightening bolt - 45. Detailed implementation manners

[0026] The present invention will be further described below through embodiments in conjunction with the accompanying drawings:

[0027] As Figures 1-6 shown, a high - temperature and high - pressure fluid displacement test method for monitoring the deformation of coal body includes the following steps:

[0028] The first step, specimen loading. Cut the raw coal block into a cylindrical specimen, then process it through a grinding machine to make the flatness of the specimen end face within ±0.02 mm, and then load the specimen into a flexible support sleeve.

[0029] The second step, device assembly. A high - temperature ring pressing sleeve is sleeved outside the support sleeve, then the support sleeve sleeved with the high - temperature ring pressing sleeve is placed into the clamping assembly, and sealed through a sealing structure. Then, install the radial monitoring sensor and the axial monitoring sensor as required, and set the fluid injection pressure, injection rate, injection temperature, and fluid injection type through the injection system.

[0030] Among them, the clamping assembly includes a mounting disc 4 and a ductile specimen tube 3, and the specimen tube 3 is provided with upper and lower through holes. Preferably, the specimen tube and the support sleeve are made of nickel-based alloy materials, specifically high-temperature aviation materials, such as imported alloy 718 or domestic material 4169, which have high temperature resistance, high pressure resistance and corrosion resistance, do not deform after repeated use, still have high strength under high temperature and high pressure, and even have a tensile strength of 1500 N / mm under the condition of 800 °C high temperature. 2 , and the yield strength reaches 800 N / mm. 2 , and the elongation rate can reach more than 30%.

[0031] A pressurizing system for realizing triaxial pressurization of the specimen and simulating the surrounding environment of the coal body is arranged on the clamping structure. The pressurizing system includes a high-temperature circumferential pressure sleeve 20 arranged between the specimen tube 3 and the support sleeve 5 and an axial pressure mounting plate 22 arranged below the mounting disc 4 through a connecting column 21. The high-temperature circumferential pressure sleeve 20 is equipped with a circumferential pressure tracking system. An axial pressure cylinder 23 is arranged on the axial pressure mounting plate 22. Preferably, a cooling sleeve 24 with water inlets and outlets is arranged between the axial pressure cylinder 23 and the specimen tube 3 to prevent the temperature of the specimen tube from affecting the axial pressure cylinder.

[0032] Preferably, the circumferential pressure tracking system includes a circumferential pressure tracking pump and a circumferential pressure tracking pipeline communicated with the high-temperature circumferential pressure sleeve. The circumferential pressure tracking pump is equipped with a control panel, a safety pressure relief function, etc., and can realize differential pressure tracking, automatic pressure lifting and lowering, display pressure data, feedback system, etc. through a control terminal; it has the function of manually controlling pressure lifting and lowering.

[0033] The sealing structure includes floating plugs 6 arranged at the upper and lower ends of the specimen tube 3. A plurality of high-temperature gaskets 7 and a double V-shaped combined graphite assembly 8 are sequentially arranged between each floating plug 6 and the specimen tube 3 from the inside to the outside. When the internal pressure extrudes outward, the self-sealing rubber ring deforms, making its outer diameter fit more closely with the specimen tube and its inner diameter fit more closely with the high-temperature circumferential pressure sleeve, so as to achieve reliable sealing. The outlet 2 and the inlet 1 are respectively arranged in different floating plugs 6. Preferably, an inlet 9 is also arranged on the floating plug 6 provided with the outlet 2.

[0034] Preferably, the high-temperature gasket material is an imported ultra-high temperature material from the United States, which has good elasticity even at 1000 °C, can be used for frequent loading and unloading, and can be arbitrarily stamped into a formed sealing gasket. Using a double V-shaped combined graphite assembly as the sealing component has the characteristics of reliable sealing and convenient loading and unloading, and at the same time plays a role in blocking the boundary cross-flow between the circumferential pressure sleeve and the core sample, and eliminating the boundary effect.

[0035] To ensure the reliable sealing of the sealing structure, a bolt pre-tightening and pressing structure for ensuring the reliable sealing of the sealing structure is provided at the end of each floating plug 6. The bolt pre-tightening and pressing structure includes an upper bolt pre-tightening and pressing structure and a lower bolt pre-tightening and pressing structure arranged up and down. That is, the upper bolt pre-tightening and pressing structure is used to lock the floating plug at the upper end, and the lower bolt pre-tightening and pressing structure is used to lock the floating plug at the lower end.

[0036] The upper bolt pre-tightening and pressing structure includes a first flange 10 sleeved on the upper end of the specimen tube 3 and a second flange 11 sleeved on the upper end of the upper floating plug 6. The first flange 10 and the second flange 11 are connected by mounting bolts. At a position near the upper end of the floating plug 6, a T-shaped upper top block 12 is provided, and the lower end of the upper top block 12 can be inserted into the upper end of the specimen tube 3. At the lower end of the second flange 11, a lower notch for the upper top block 12 to be inserted into is provided. On the second flange 11, an upper tightening bolt 13 that can press on the upper top block 12 is provided.

[0037] The lower bolt pre-tightening and pressing structure includes a third flange 14 sleeved on the lower end of the specimen tube 3 and a fourth flange 15 sleeved at a position near the lower end of the lower floating plug 6. The third flange 14 is arranged on the mounting plate 4 located at its lower end. The upper end of the fourth flange 15 is located inside the mounting plate 4. At a position near the lower end of the lower floating plug 6 at the lower end, a T-shaped lower top block 16 is provided, and the upper end of the lower top block 16 can be inserted into the lower end of the specimen tube 3. At the upper end of the fourth flange 15, an upper notch for the lower top block 16 to be inserted into is provided. On the fourth flange 15, a lower tightening bolt 45 that can press on the lower top block 16 is provided.

[0038] The sealing structure is tightened by multiple tightening bolts and top blocks to prevent the outward movement of the sealing structure when the internal pressure rises. Preferably, the screws are made of high-strength heat-resistant materials and will not produce thread sticking phenomena at high temperatures.

[0039] The monitoring system includes a radial monitoring sensor 25 and an axial monitoring sensor 26. The radial monitoring sensor 25 is provided with at least two rows, and at least four radial monitoring sensors 25 are arranged in different directions in each row. The radial monitoring sensor 25 passes through the specimen tube 3 and contacts the specimen, and a sealing ring and a gasket are provided between the radial monitoring sensor and the specimen tube. The radial detection sensor 25 is arranged on the sensor bracket 27, and the sensor bracket 27 is arranged on the mounting plate 4. The axial monitoring sensor 26 is arranged between the axial pressure mounting plate 22 and the detection plate 28, and the detection plate 28 is arranged at the lower end of the lower floating plug 6.

[0040] To achieve horizontal and vertical flipping, the mounting disc 4 is arranged on the flipping assembly. The flipping assembly includes a flipping bracket 29. Horizontal rotating shafts 30 are arranged at both ends of the mounting disc 4. The other ends of the rotating shafts 30 are rotatably arranged on a flipping seat 31. The flipping seat 31 is arranged on the flipping bracket 29. A traveling mechanism 32 is arranged at the bottom of the flipping bracket 29 for driving the whole flipping assembly to move and fix the position after movement.

[0041] The injection system includes a storage container 33 for containing fluid, a constant-pressure pump 34 for realizing fluid flow, a heater 35 for realizing fluid heating, and a fluid buffer tank 36 for ensuring that the input fluid is in a supercritical state. The storage container 33, the constant-pressure pump 34, the heater 35, and the fluid buffer tank 36 are sequentially connected through an injection pipeline. A monitoring structure for monitoring its pressure and temperature is arranged on the fluid buffer tank 36. A pressure vessel 37 for buffering pressure fluctuations during heating is connected in parallel to the heater 35. A control valve 38 is arranged on the fluid buffer tank.

[0042] As Figure 6 shown, the pressure vessel 37 is a piston-type pressure vessel, specifically including a cylinder body 37b arranged on a base 37a. A piston 37c is slidably arranged in the cylinder body 37b. Gaskets and sealing rings are arranged between the piston 37c and the cylinder body 37b to ensure the sealing between the piston and the cylinder body. Pressure caps 37d for closing the cylinder body 37b are arranged at both the upper and lower ends of the cylinder body 37b. A plug 37e is arranged on the pressure cap 37d, and a flow channel for fluid to pass through is arranged on the plug 37e. The pressure vessel is made of high-strength materials and is sealed and isolated using O-rings. In addition to the isolation function, the important function of the piston is to transmit the power of the power liquid to the working medium for work. There is no pulse phenomenon, and it can stably transmit pressure and flow, with low pressure loss. During the whole test process, it is necessary to ensure that the fluids in the pressure vessel and the storage container are of the same type.

[0043] The specific structure of the heater 35 includes a heat transfer body with a main body made of cast aluminum material. Electric heating tubes are spirally arranged on the heat transfer body, and a heating channel for fluid to pass through is arranged outside the electric heating tubes. Heat insulation materials are arranged outside the heat transfer body, and the heat insulation materials are made of ceramic fiber blankets.

[0044] In the third step, start the test. Inject high-temperature and high-pressure fluid into the specimen through the injection system to complete the test. At the same time, record the axial and radial displacement changes of the specimen through the radial monitoring detection sensor and the axial detection sensor, and analyze the deformation of the specimen.

[0045] Step 4: Repeat the tests. Change the types of injected fluids, the pressures of injected fluids, and the temperatures of injected fluids respectively, repeat the tests, and record the displacement changes in the axial and radial directions of the specimens when each condition is changed, so as to analyze the deformation law of coal and rock masses after injecting high-temperature and high-pressure fluids.

Claims

1. A high-temperature and high-pressure fluid displacement test method for monitoring coal body deformation, characterized in that: The steps are as follows: S1: Specimen loading. Cut the raw coal block into a cylindrical specimen, then process it through a grinding machine to make the flatness of the specimen end face within ±0.02 mm, and then load the specimen into a flexible support sleeve; S2: Device assembly. A high-temperature ring pressing sleeve is sleeved outside the support sleeve, then the whole is placed into the clamping assembly and sealed through a sealing structure. Then, a radial monitoring and detection sensor and an axial detection sensor are installed as required. Next, set the fluid injection pressure, injection rate, injection temperature, and fluid injection type through the injection system; S3: Start the test. Inject high-temperature and high-pressure fluid into the specimen through the injection system to complete the test. At the same time, record the axial and radial displacement changes of the specimen through the radial monitoring and detection sensor and the axial detection sensor, and analyze the deformation of the specimen; S4: Repeat the test. Change the type of injected fluid, the pressure of the injected fluid, and the temperature of the injected fluid respectively, repeat the test, and record the axial and radial displacement changes of the specimen when each condition changes, so as to analyze the deformation law of the coal and rock mass after injecting high-temperature and high-pressure fluid.

2. The high-temperature and high-pressure fluid displacement test method for monitoring coal mass deformation according to claim 1, characterized in that: The clamping structure includes a mounting plate (4) and a ductile specimen tube (3). The specimen tube (3) is arranged to penetrate up and down. A pressurizing system for realizing triaxial pressurization of the specimen is arranged on the clamping structure; the pressurizing system includes a high-temperature ring pressing sleeve (20) arranged between the specimen tube (3) and the support sleeve (5) and an axial pressure mounting plate (22) arranged below the mounting plate (4) through a connecting column (21). The high-temperature ring pressing sleeve (20) is equipped with a ring pressure tracking system, and an axial pressure cylinder (23) is arranged on the axial pressure mounting plate (22).

3. The high-temperature and high-pressure fluid displacement test method for monitoring coal body deformation according to claim 2, characterized in that: The sealing structure includes floating plugs (6) arranged at the upper and lower ends of the specimen tube (3). Between each floating plug (6) and the specimen tube (3), multiple high-temperature gaskets (7) and double V-shaped combined graphite components (8) are sequentially arranged from inside to outside. A bolt pre-tightening and top-tightening structure for ensuring the reliable sealing of the sealing structure is arranged at the end of each floating plug (6). An outlet (2) for fluid injection or an inlet (1) communicated with the injection system is arranged inside the floating plug (6), and the outlet (2) and the inlet (1) are respectively arranged in different floating plugs (6).

4. The high-temperature and high-pressure fluid displacement test method for monitoring coal body deformation according to claim 3, characterized in that: The bolt pre-tightening and top-tightening structure includes an upper bolt pre-tightening and top-tightening structure and a lower bolt pre-tightening and top-tightening structure corresponding to the upper and lower floating plugs. The upper bolt pre-tightening and top-tightening structure includes a first flange (10) sleeved on the upper end of the specimen tube (3) and a second flange (11) sleeved on the upper end of the upper floating plug (6). The first flange (10) and the second flange (11) are connected by mounting bolts. A T-shaped upper top block (12) is arranged at a position close to the upper end of the floating plug (6), and the lower end of the upper top block (12) can be inserted into the upper end of the specimen tube (3). A lower notch for the upper top block (12) to be inserted into is arranged at the lower end of the second flange (11), and an upper top-tightening bolt (13) capable of pressing on the upper top block (12) is arranged on the second flange (11); The lower bolt pre-tightening and jacking structure includes a third flange (14) sleeved on the lower end of the specimen tube (3) and a fourth flange (15) sleeved on the lower floating plug (6) near its lower end. The third flange (14) is arranged on the mounting plate (4) located at its lower end. The upper end of the fourth flange (15) is located inside the mounting plate (4). At the position of the lower floating plug (6) near its lower end, a T-shaped lower jacking block (16) is arranged, and the upper end of the lower jacking block (16) can be inserted into the lower end of the specimen tube (3). The upper end of the fourth flange (15) is provided with an upper notch for the lower jacking block (16) to be inserted into, and a lower jacking bolt (45) capable of jacking on the lower jacking block (16) is arranged on the fourth flange (15).

5. The high-temperature and high-pressure fluid displacement test method for monitoring the deformation of coal mass according to claim 2, characterized in that: At least two rows of the radial monitoring sensors (25) are provided, and at least four radial monitoring sensors (25) are arranged in different directions in each row. The radial monitoring sensors (25) are in contact with the specimen after passing through the specimen tube (3). The radial detection sensors (25) are arranged on the sensor bracket (27), and the sensor bracket (27) is arranged on the mounting plate (4); the axial monitoring sensor (26) is arranged between the axial pressure mounting plate (22) and the detection plate (28).

6. The high-temperature and high-pressure fluid displacement test method for monitoring coal body deformation according to claim 2, characterized in that: The mounting plate (4) is arranged on the flipping assembly. The flipping assembly includes a flipping bracket (29). Horizontal flipping shafts (30) are arranged at both ends of the mounting plate (4). The other ends of the flipping shafts (30) are rotatably arranged on the flipping seats (31). The flipping seats (31) are arranged on the flipping bracket (29). A traveling mechanism (32) for driving the whole flipping assembly to move and fix the position after moving is arranged at the bottom of the flipping bracket (29).

7. The high-temperature and high-pressure fluid displacement test method for monitoring coal mass deformation according to claim 1, wherein: The injection system includes a storage container (33) for containing fluid, a constant pressure pump (34) for realizing fluid flow, a heater (35) for realizing fluid heating, and a fluid buffer tank (36) for ensuring that the input fluid is in a supercritical state. The storage container (33), the constant pressure pump (34), the heater (35), and the fluid buffer tank (36) are sequentially connected through an injection pipeline. A monitoring structure for monitoring its pressure and temperature is arranged on the fluid buffer tank (36). A pressure vessel (37) for buffering pressure fluctuations during heating is connected in parallel to the heater (35). A control valve (38) is arranged on the fluid buffer tank.

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