Device for detecting corrosion rate of supercritical carbon dioxide to coal sample

Abstract

The utility model discloses a device for detecting the corrosion rate of supercritical carbon dioxide to a coal sample, and relates to the technical field of anti-reflection, and the corrosion rate detection device comprises a reaction kettle, a vacuum pump, a reaction cavity, a thermobalance, a fluid supply assembly and a purging assembly. The required testing environment can be created in the reaction kettle, the thermal balance records the mass change of the coal sample in real time, during testing, pressurized inert gas can be purged into the reaction kettle through the purging assembly, desorption of carbon dioxide from pores of the coal sample is accelerated, it is ensured that the final mass is close to the mass of the coal sample after real corrosion, the corrosion rate calculation result is more accurate, and the test efficiency is improved. The corrosion effect of the supercritical carbon dioxide on the coal sample can be truly fed back.

Description

Technical Field

[0001] This application relates to the field of enhanced transparency technology, and more particularly to a device for detecting the solubility rate of coal samples by supercritical carbon dioxide. Background Technology

[0002] Supercritical carbon dioxide (SC-CO2) can achieve efficient extraction of coalbed methane from low-permeability coalbed methane by dissolving carbonates and other minerals in coal and improving pore and fracture connectivity. It also provides a technical pathway for carbon dioxide sequestration in deep coal seams. However, the dissolution effect of SC-CO2 on coal is highly dynamic and complex: it may promote the development of medium-to-large pores and increase permeability through a "pore-enlarging effect," but it may also cause deterioration of the coal's mechanical strength due to uneven mineral dissolution, affecting mining safety and sequestration stability. Therefore, exploring the dissolution effect of SC-CO2 on coal samples is an urgent problem to be solved in this technical field. Utility Model Content

[0003] This application provides a device for detecting the dissolution rate of coal samples by supercritical carbon dioxide, which can accurately reflect the dissolution effect of supercritical carbon dioxide on coal samples.

[0004] This application provides a device for detecting the solubility rate of coal samples by supercritical carbon dioxide, including a reaction vessel, a vacuum pump, a reaction chamber, a thermal balance, a fluid supply assembly, and a purging assembly. A heating wire for heating is installed inside the reaction vessel. The vacuum pump is connected to the reaction vessel. The reaction chamber is located inside the reaction vessel. The thermal balance is located inside the reaction chamber, and the coal sample to be tested is placed on the thermal balance. The fluid supply assembly is connected to the reaction vessel and is used to supply supercritical carbon dioxide to the reaction vessel. The purging assembly includes an inert gas source, a valve, and a booster pump. The inert gas source is connected to the inlet of the booster pump through the valve, and the outlet of the booster pump is connected to the reaction vessel.

[0005] Preferably, the top of the reactor is provided with a sealing cover and fastening bolts, and the sealing cover is connected to the top of the reactor by the fastening bolts.

[0006] Preferably, the reactor is equipped with a carbon dioxide sensor, a digital pressure gauge, and a digital thermometer.

[0007] Preferably, the suction port of the vacuum pump is connected to the reaction vessel through valve two.

[0008] Preferably, the reaction chamber includes a cavity, a second sealing cover, an electric metering valve, a guide tube, and a sample container; the cavity is located inside the reaction vessel, and the second sealing cover is located at the upper opening of the cavity, so that the interior of the cavity forms a sealed space; the electric metering valve is located on the second sealing cover and is used to connect the interior of the reaction vessel and the interior of the cavity; one end of the guide tube is connected to the electric metering valve, and the other end is connected to the sample container located on the thermal balance, and the coal sample is placed in the sample container.

[0009] Preferably, the cavity is equipped with multiple thermal balances, with each thermal balance, sample container, and flow guide tube corresponding to the other.

[0010] Preferably, the fluid supply assembly includes a carbon dioxide gas source, valve three, booster pump two, valve four, gas storage tank, valve five, constant temperature and constant flow pump, and valve six connected in sequence, with the outlet end of valve six connected to the reactor.

[0011] Preferably, the fluid supply assembly further includes an electromagnetic flow meter 1, an electromagnetic flow meter 2, and a digital pressure gauge 2. The electromagnetic flow meter 1 is connected between the valve 3 and the booster pump 2, the electromagnetic flow meter 2 is connected between the booster pump 2 and the valve 4, and the digital pressure gauge 2 is connected to the gas storage tank.

[0012] Preferably, the purging assembly also includes a valve seven disposed between the booster pump one and the reactor.

[0013] Preferably, it also includes an exhaust gas collection assembly; the exhaust gas collection assembly includes a collection chamber, valve eight, carbon dioxide sensor two, inert gas sensor, digital pressure gauge three, and digital thermometer two; the collection chamber is connected to the reactor through valve eight, and carbon dioxide sensor two and inert gas sensor two are both located in the collection chamber; digital pressure gauge three and digital thermometer two are both connected to the collection chamber.

[0014] The corrosion rate detection device of this application has at least the following beneficial effects:

[0015] This application creates the necessary testing environment within the reactor by setting up a heating wire, a vacuum pump, and a fluid supply assembly. The thermal balance records the changes in coal sample mass in real time. During testing, pressurized inert gas can be purged into the reactor through a purging assembly to accelerate the desorption of carbon dioxide from the pores of the coal sample, ensuring that the final mass is close to the actual mass of the coal sample after dissolution. This makes the calculation of the dissolution rate more accurate and can truly reflect the dissolution effect of supercritical carbon dioxide on the coal sample. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0017] Figure 1 This is a schematic diagram of the overall structure of the corrosion rate detection device of this application;

[0018] Figure 2 This is a schematic diagram of the reaction chamber;

[0019] Figure 3This is a flowchart of the supercritical carbon dioxide damage effect evaluation method of this application;

[0020] Figure 4 This is a schematic diagram of the four types of experience curves in this application;

[0021] The annotations in the attached figures are explained as follows:

[0022] 100. Fluid supply components;

[0023] 200. Purge assembly;

[0024] 300. Exhaust gas collection assembly;

[0025] 1. Carbon dioxide gas source; 2. Valve 3; 3. Booster pump 2; 4. Valve 4; 5. Gas storage tank; 6. Valve 5; 7. Thermostatic and constant flow pump; 8. Valve 6; 9. Electromagnetic flowmeter 1; 10. Electromagnetic flowmeter 2; 11. Digital pressure gauge 2; 12. Reactor; 13. Heating wire; 14. Sealing cover 1; 15. Fastening bolts; 16. Carbon dioxide sensor 1; 17. Digital pressure gauge 1; 18. Digital thermometer 1; 19. Programmable temperature module 20. Vacuum pump; 21. Valve II; 22. Reaction chamber; 23. Chamber body; 24. Sealing cap II; 25. Electric quantitative valve; 26. Guide tube; 27. Sample container; 28. Thermal balance; 29. ​​Inert gas source; 30. Valve I; 31. Booster pump I; 32. Valve VII; 33. Collection chamber; 34. Valve VIII; 35. Carbon dioxide sensor II; 36. Inert gas sensor; 37. Digital pressure gauge III; 38. Digital thermometer II;

[0026] 400. Coal sample. Detailed Implementation

[0027] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0028] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] This embodiment discloses a device for detecting the solubility rate of coal samples by supercritical carbon dioxide, and also discloses a method for evaluating the damage effect of supercritical carbon dioxide based on the solubility rate detection device.

[0030] like Figure 1 As shown, the corrosion rate detection device of this embodiment will be introduced first. The corrosion rate detection device includes a reaction vessel 12, a vacuum pump 20, a reaction chamber 22, a thermal balance 28, a fluid supply assembly 100, a purging assembly 200, and a tail gas collection assembly 300.

[0031] The reactor 12 is configured as an existing digital display high temperature and high pressure reactor, which is a regular cylindrical or rectangular shape. It has an internal space for accommodating the reaction chamber 22. The reactor 12 is also equipped with a heating wire 13, which is coaxially surrounded around the reaction chamber 22 to generate heat and create the required temperature environment.

[0032] In some preferred embodiments, the top of the reactor 12 is provided with a first opening, and the first opening is provided with a sealing cover 14. The sealing cover 14 is used to close the first opening so that a sealed space is formed inside the reactor 12. The sealing cover 14 is connected to the top of the reactor 12 by a plurality of fastening bolts 15. The first opening facilitates opening the internal space of the reactor 12 in the non-working state to facilitate various operations such as discharging materials.

[0033] In some preferred embodiments, the reactor 12 is equipped with a carbon dioxide sensor 16, a digital pressure gauge 17, and a digital thermometer 18. The carbon dioxide sensor 16 is located at the top of the reactor 12 and is used to detect the carbon dioxide concentration in the internal space of the reactor 12. The digital pressure gauge 17 is located at the top of the reactor 12 and is connected to the interior of the reactor 12 to detect the pressure in the internal space of the reactor 12. The digital thermometer 18 is located at the top of the reactor 12 and is connected to the interior of the reactor 12 to detect the temperature in the internal space of the reactor 12.

[0034] In some preferred embodiments, a programmed temperature rise module 19 is provided inside the reactor 12. The programmed temperature rise module 19 is directly or indirectly connected to the heating wire 13. The programmed temperature rise module 19 is used to control the operation of the heating wire 13 and has the function of raising the internal temperature of the reactor 12 and keeping it warm.

[0035] Vacuum pump 20 is located on the upper left side of reactor 12. The suction port of vacuum pump 20 is connected to valve 21, which is connected to the upper middle part of reactor 12. Vacuum pump 20 is used to draw a vacuum to avoid air interfering with the SC-CO2 dissolution of coal samples and improve the accuracy of the test.

[0036] like Figure 2 As shown, the reaction chamber 22 is coaxially built into the interior of the reaction vessel 12 to accommodate multiple thermal balances 28 and coal samples to be tested. The reaction chamber 22 includes a cavity 23, a second sealing cover 24, an electric metering valve 25, a guide tube 26, and a sample container 27. The cavity 23 is coaxially built into the interior of the reaction vessel 12, and a second opening is provided at the top of the cavity 23. The second sealing cover 24 is located at the second opening to seal the cavity 23, forming a closed space inside the cavity 23. Preferably, the second sealing cover 24 is an electric sealing cover that can automatically open and close under the control of the central control computer. The electric metering valve 25 is located on the second sealing cover 24. Preferably, the second sealing cover 24 has mounting holes corresponding one-to-one with the electric metering valve 25. The metering valve 25 is coaxially mounted in the mounting hole, and a sealing ring or sealing medium can be installed between the electric metering valve 25 and the inner peripheral wall of the mounting hole, so that the interior of the cavity 23 can only be connected to the interior of the reactor 12 through the electric metering valve 25. The inlet of the electric metering valve 25 is connected to the interior of the reactor 12, and the outlet of the electric metering valve 25 is connected to one end of the guide pipe 26. The other end of the guide pipe 26 is connected to the top of the sample container 27. The sample container 27 contains the sample to be tested. The sample container 27 is placed on the thermal balance 28, which is located on the inner bottom wall of the cavity 23.

[0037] There is at least one thermal balance 28. In this embodiment, it is preferred that there are at least ten thermal balances 28. Multiple thermal balances 28 are arranged in an array on the inner bottom wall of the cavity 23. The thermal balances 28 are connected to the central control computer via shielded cables. They can automatically collect sample quality data in real time and calculate the erosion rate through the built-in software module, as shown below.

[0038] ;

[0039] in, This indicates the initial mass of the coal sample, that is, its mass before it was dissolved. This indicates the final mass of the coal sample, that is, the mass after it has been dissolved.

[0040] In this embodiment, the thermal balance 28, sample container 27, guide tube 26, and electric metering valve 25 are arranged in a one-to-one correspondence. One or more electric metering valves 25 can be opened according to actual needs, thereby guiding the supercritical carbon dioxide in the reaction vessel 12 through the guide tube 26 to the sample container 27 to dissolve the sample. This design enables selective testing, sequential testing, and other operations, improving the flexibility of the device.

[0041] The fluid supply assembly 100 includes a carbon dioxide gas source 1, valve 3 2, booster pump 2 3, valve 4 4, gas storage tank 5, valve 5 6, constant temperature and constant flow pump 7, and valve 6 8. The carbon dioxide gas source 1 can be a gas cylinder containing carbon dioxide gas, a laboratory or industrial acid container, or other container that can provide the carbon dioxide gas required for the reaction. The outlet of the carbon dioxide gas source 1 is connected to valve 3 2. The carbon dioxide gas source 1 can be controlled by an external central control computer to control whether the gas in the carbon dioxide gas source 1 is delivered externally. The outlet of valve 3 2 is connected to the inlet of booster pump 2 3, and the outlet of booster pump 2 3 is connected to valve 4 4. Booster pump 2 3 is configured as a gas-liquid booster pump. The outlet of valve 4 4 ​​is connected to gas storage tank 5, the outlet of gas storage tank 5 is connected to valve 5 6, the outlet of valve 5 6 is connected to constant temperature and constant flow pump 7, the outlet of constant temperature and constant flow pump 7 is connected to valve 6 8, and the outlet of valve 6 8 is connected to the upper middle part of the reaction vessel 12. In this embodiment, carbon dioxide gas source 1 is turned on, and booster pump 2 3 pressurizes carbon dioxide to 10 MPa. At this time, the state of carbon dioxide is considered to have reached the supercritical state, and it is temporarily stored in storage tank 5. The constant temperature and constant flow pump 7 can accurately control the temperature and pressure of the fluid (supercritical carbon dioxide) and inject the fluid into the reactor 12 through the pipeline.

[0042] In this preferred embodiment, the fluid supply assembly 100 further includes an electromagnetic flow meter 9, an electromagnetic flow meter 10, and a digital pressure gauge 11. The electromagnetic flow meter 9 is connected to the pipeline between the valve 2 and the booster pump 3, the electromagnetic flow meter 10 is connected to the pipeline between the booster pump 3 and the valve 4, and the digital pressure gauge 11 is internally connected to the gas storage tank 5. This embodiment uses the electromagnetic flow meters 9, 10, and 11 to detect parameters along the fluid supply path, facilitating control of the testing process.

[0043] The purging assembly 200 includes an inert gas source 29, a valve 30, a booster pump 31, and a valve 32. The inert gas source 29 includes a gas cylinder containing inert gas, preferably argon. The inert gas source 29 can be controlled by an external central control computer, thereby controlling whether the gas in the inert gas source 29 is transported outward. The outlet of the inert gas source 29 is connected to valve 30, and valve 30 is connected to booster pump 31. Booster pump 31 is configured as a gas-liquid booster pump. The outlet of booster pump 31 can be directly connected to the interior of the reactor 12. In this embodiment, it is preferable that the outlet of booster pump 31 is indirectly connected to the interior of the reactor 12, that is, the outlet of booster pump 31 is connected to valve 32, and the outlet of valve 32 is connected to the interior of the reactor 12.

[0044] In this embodiment, argon gas ( As an inert gas, it can quickly replace the residual carbon dioxide in reactor 12. Combined with appropriate heating, it can accelerate the desorption of carbon dioxide from the pores of the coal sample, ensuring that the final mass is close to the actual mass of the coal sample after dissolution. This makes the dissolution rate calculation more accurate and can provide a reliable basis for subsequent coal sample type determination. Secondly, it can also avoid experimental interference and contamination. It does not react chemically with coal samples or supercritical carbon dioxide, which can completely remove residual carbon dioxide without introducing new impurities, ultimately helping to clarify the experimental endpoint and improve efficiency.

[0045] If carbon dioxide is not fully desorbed, it will remain in the pores of the coal sample in an adsorbed state, causing the final measured mass of the coal sample to be higher than expected. According to the dissolution rate calculation formula, an inflated final mass will directly lead to an underestimation of the dissolution rate, failing to accurately reflect the degree of dissolution of the coal by supercritical carbon dioxide. Secondly, it interferes with subsequent data acquisition. Residual carbon dioxide will be slowly released into reactor 12 or collection chamber 33, causing continuous fluctuations in the carbon dioxide concentration in collection chamber 33. This makes it impossible to accurately determine the endpoint of "complete desorption," thus affecting the effectiveness of subsequent vacuuming and residual gas removal steps, and may even interfere with the gas environment of other coal sample experiments. Finally, it disrupts the true state of the coal sample. Residual carbon dioxide may react secondaryly with unreacted components in the coal sample or alter the pressure environment within the coal sample pores, rendering subsequent assessments of the degree of coal sample damage meaningless.

[0046] The exhaust gas collection assembly 300 includes a collection chamber 33, a valve 34, a carbon dioxide sensor 35, an inert gas sensor 36, a digital pressure gauge 37, and a digital thermometer 38. The collection chamber 33 is located on the lower right side of the reactor 12 and is connected to the valve 34. The valve 34 is also connected to the lower right side of the reactor 12. Both the carbon dioxide sensor 35 and the inert gas sensor 36 are located within the collection chamber 33 and are used to detect the concentration values ​​of carbon dioxide and inert gas within the collection chamber 33, respectively. In this embodiment, the inert gas sensor 36 is preferably configured as an argon gas concentration sensor. The digital pressure gauge 37 is located at the top of the collection chamber 33 and is connected to the interior of the collection chamber 33, used to detect the pressure within the collection chamber 33. The digital thermometer 38 is located at the top of the collection chamber 33 and is connected to the interior of the collection chamber 33, used to detect the temperature within the collection chamber 33.

[0047] In this embodiment, the carbon dioxide concentration in the collection chamber 33 and the reaction vessel 12 can be monitored. When the concentration is stable, it can be determined that the desorption is complete, thus avoiding subjective judgment errors.

[0048] In this embodiment, the corrosion rate detection device controls and collects parameters of each component through a central control computer. Specifically, the following components are connected to the central control computer: carbon dioxide gas source 1, all electromagnetic flow meters, all valves (electric valves), all booster pumps, gas storage tank 5, constant temperature and constant flow pump 7, vacuum pump 20, all digital pressure gauges, all digital thermometers, programmable temperature module 19, all thermal balances 28, all electric metering valves 25, all sensors (including carbon dioxide sensors and inert gas sensors), and inert gas source 29. They are all electrically connected to the central control computer, preferably through shielded cables, and can directly and automatically collect, process, and calculate data.

[0049] like Figure 3 As shown in the figure, this embodiment also discloses a method for evaluating the damage effect of supercritical carbon dioxide based on the above-mentioned dissolution rate detection device, as follows:

[0050] A. Prepare coal samples with particle size gradients of 4cm, 3cm, 2.5cm, 2cm, 1.5cm, 1cm, 0.8cm, 0.6cm, 0.4cm and 0.2cm, and divide them into group ①, group ②... group ⑩ according to particle size;

[0051] B. Remove the fastening bolt 15, open the sealing cover 14 and the sealing cover 24, place coal samples of different particle sizes into the sample container 27, then close the sealing cover 14. Turn on the vacuum pump 20 and valve 21 to create a vacuum environment inside the reaction vessel 12. Close the sealing cover 24 and record the initial mass of the coal sample as follows: ;

[0052] C. The target temperature is set by the programmable heating module 19, and the internal temperature of the reactor 12 is heated to 40°C by the heating wire 13; the carbon dioxide gas source 1 is turned on, and the carbon dioxide is pressurized to 10 MPa by the booster pump 31, at which point the carbon dioxide reaches the supercritical state.

[0053] D. Open valve 6, and inject a constant flow rate and injection pressure (greater than 10 MPa) through the constant temperature and constant flow pump 7. Observe the pressure of the digital pressure gauge 17 to be stable at 10 MPa or above, and observe the temperature of the digital thermometer 18 to be stable at 40℃. Open the electric quantitative valve 25 and inject supercritical carbon dioxide into the sample tank 27 through the guide tube 26 so that the supercritical carbon dioxide reacts with the coal sample.

[0054] E. During the reaction of supercritical carbon dioxide with the coal sample, the mass of the coal sample was recorded by a thermobalance at 1-hour intervals. When the mass of the coal sample no longer changed, it was considered that the reaction between supercritical carbon dioxide and the coal sample was nearly complete.

[0055] F. After the reaction is complete, it is necessary to promote the expulsion of supercritical carbon dioxide. In this embodiment, the expulsion is promoted in a coordinated manner by gradient heating, gradient vacuum, and inert gas purging.

[0056] The first stage involves promoting the removal of residual gas from the surface (0-1 hour) to remove adsorbed gases from the coal sample surface. The process includes: a programmed temperature rise module 19 controlling the heating wire 13 to raise the temperature of the reactor 12 from 40℃ to 45℃ during the reaction stage. This low temperature rise during this stage avoids thermal damage to the coal sample and maintains a constant temperature. A vacuum pump 20 is started to adjust the vacuum level inside the reactor 12 to a low vacuum of -0.05MPa to avoid directly damaging the coal sample structure, and continuous evacuation is performed. An inert gas source 29, valve 30, and booster pump 31 are opened, and a low purging flow rate of 100mL / min is set to ensure that only the surface of the coal sample is disturbed, preventing sample displacement. Intermittent purging (30s purging, 30s pause) is controlled to prevent excessive dilution of carbon dioxide by argon, which could affect concentration monitoring.

[0057] In the second stage, residual gas in the coal sample pores is expelled (1-2 hours) to remove residual gases. This includes: the programmed temperature rise module 19 continues to control the heating, raising the temperature from 45℃ to 55℃ to increase the desorption rate within the pores and maintain a constant temperature. The vacuum pump 20 increases its suction force, raising the vacuum level from -0.05MPa to a high vacuum of -0.09MPa, creating a pressure difference between the inside and outside of the pores, accelerating the overflow of residual gas, and continuously pumping gas. The argon purging flow rate is increased to a high flow rate of 150mL / min, switching to continuous purging, using the argon flow to replace the overflowing carbon dioxide within the pores and accelerate its entry into the collection chamber 33.

[0058] The third stage, residual gas confirmation and cleanup (2~2.5h), ensures no residue remains, including: maintaining a temperature of 55℃, and after the carbon dioxide concentration stabilizes, stopping the heating of the programmed temperature rise module 19 and allowing it to cool naturally to 40℃. Maintaining a high vacuum of -0.09MPa until the carbon dioxide concentration in the collection chamber 33 stabilizes. Gradually reducing the argon purging flow rate to 50mL / min, and finally shutting off the inert gas source 29, valve 7 32, and booster pump 2 3 to stop purging.

[0059] In this embodiment, combining argon purging with a heating operation is preferred as it effectively removes residual carbon dioxide. However, argon purging alone may not completely remove residual carbon dioxide, and a very small amount may adhere to the inside of the coal sample, leading to an inflated final mass and consequently an underestimation of the erosion rate. In this embodiment, combining argon purging with a heating operation is a preferred method. Direct argon purging can also effectively remove residual carbon dioxide; therefore, those skilled in the art can choose whether to combine the purging process with a gradient heating operation based on actual needs.

[0060] The method in this embodiment uses a gradient heating approach, which can also avoid the coal sample pyrolyzing due to excessively high temperatures or failing to effectively promote desorption due to excessively low temperatures.

[0061] G. Ensure consistent coal sample mass across all particle sizes, and record the mass of the coal sample after reaction as follows: , The initial mass of the coal sample should be consistent with the coal sample group number, for example, the initial mass of coal sample group ① is denoted as . The initial mass of coal sample ② is denoted as . And so on, similarly. Indicates the dissolution rate of group ①;

[0062] H. Calculate the dissolution rate of coal samples of each particle size. The formula is as follows:

[0063] ;

[0064] Statistical analysis was performed, and particle size-dissolution rate (φ-R) curves (hereinafter referred to as measured curves) were plotted. The measured curves were compared with four types of empirical φ-R curves (e.g., ...). Figure 4 As shown in the figure, the type of coal sample can be determined, the degree of damage caused by supercritical carbon dioxide can be assessed, the quantitative gap in the mechanism of supercritical carbon dioxide damage in coal can be filled, and it can be used to guide the engineering implementation of supercritical carbon dioxide in coalbed methane development and carbon sequestration.

[0065] like Figure 4 As shown, the four types of φ-R empirical curves include:

[0066] Class I (easily soluble coal): The dissolution rate increases rapidly and then decreases significantly;

[0067] Type II (relatively soluble coal): The dissolution rate steadily increased before experiencing a slight decrease;

[0068] Category III (difficult-to-dissolve coal): The dissolution rate increases slowly and then decreases very slightly;

[0069] Class IV (refractory coal): The dissolution rate increases slowly and then remains almost flat.

[0070] like Figure 4 As shown, the horizontal axis of the four types of φ-R empirical curves represents the particle size, and the vertical axis represents the dissolution rate. The trend of the dissolution rate is that it decreases with decreasing particle size.

[0071] To avoid the influence of subjective factors, the comparison and judgment criteria in this embodiment can be carried out in the following comparison manner:

[0072] First, it is necessary to ensure that the particle size and empirical curve used in the experiment maintain the same gradient range, eliminate interference from non-particle size data, and strictly follow the calculation logic of this embodiment in the calculation method of the dissolution rate; the particle size includes: 4cm, 3cm, 2.5cm, 2cm, 1.5cm, 1cm, 0.8cm, 0.6cm, 0.4cm and 0.2cm.

[0073] II. When there is a significant discrepancy between the measured curve and the four types of empirical curves, for example, when the measured curve and the four types of empirical curves are simultaneously imported into Origin software and the images are output, the curve similarity between the measured curve and the empirical curve is calculated using the Python Fréchet distance open-source code, denoted as S. The similarity is then used to determine the coal sample type and assess the degree of damage caused by SC-CO2. The similarity determination criteria are as follows: S ≥ 0.5, deemed similar, and the coal sample type result is output; S < 0.5, deemed dissimilar, and the following quantitative parameters are used for comparison:

[0074] ① Rate of increase in dissolution rate Take the average value of the dissolution rate difference for particle sizes of 4cm, 3cm, and 2.5cm, i.e. (Note: The average difference can reduce the error of single particle size experiments. The difference in specific surface area between samples in the large particle size range of 4cm, 3cm, and 2.5cm is smaller than that between samples in the small particle size range. Therefore, samples of 4cm, 3cm, and 2.5cm are selected to calculate the average difference.)

[0075] ② Maximum dissolution rate reduction First, find the maximum dissolution rate in the measured curve. (For a specific particle size), then calculate The difference between the erosion rate and the minimum particle size (0.2 cm) accounts for The percentage, that is: ;

[0076] ③Stable range of dissolution rate Find a continuous grain size range (at least 5 consecutive points) where the erosion rate variation is ≤0.5%. If this range includes the smallest grain size (0.2 cm), record the starting grain size of this range as [value missing]. .

[0077]

[0078] III. The following case study provides the judgment rules for measured curves located in the middle of empirical curves:

[0079] Case 1: Between Class I and Class II

[0080] Measured curve parameters: =4.9% (meets the Class II V1 range: 2% ≤ <5%) =3.1% (meets Category I) Interval: ≥3%), no stable interval ;

[0081] Decision logic: Priority, classified as Category II; Approaching Class I, label the subtype;

[0082] Final determination: Class II (near Type I) relatively easily soluble coal.

[0083] Case ②: Between Class II and Class III

[0084] Measured curve parameters: =2.1% (meets the Class II v1 range: 2% ≤ <5%) =0.9% (meets Category III) Interval: 0.1% ≤ <1%), no stable interval ;

[0085] Decision logic: Priority, classified as Category II; Approaching Category III, subtype labeled;

[0086] Final determination: Type II (near Type III) relatively easily soluble coal.

[0087] Case 3: Between Class III and Class IV

[0088] Measured curve parameters: =0.4% (Conforms to Class IV v1 range: <0.5%) =0.15% (compliant with Class III) Interval: 0.1% ≤ <1%) =1.2cm (close to Class IV) ≤1cm, but not met);

[0089] Decision logic: It should be preferentially classified as Category IV, but , Not entirely consistent; experimental data needs to be verified (e.g., whether it's due to incomplete desorption). (Too large); if the data is correct, label the subtype;

[0090] Final determination: Class IV (near Type III) refractory coal (please specify) =1.2cm, slightly higher than the Class IV standard).

[0091] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A supercritical carbon dioxide dissolution rate detection device for a coal sample, characterized by, include: The reactor (12) is equipped with a heating wire (13) for heating. A vacuum pump (20) is connected to the reactor (12); The reaction chamber (22) is located inside the reaction vessel (12); A thermal balance (28) is set inside the reaction chamber (22), and the coal sample to be tested is set on the thermal balance (28); A fluid supply assembly (100) is connected to the reactor (12) and is used to supply supercritical carbon dioxide into the reactor (12); The purging assembly (200) includes an inert gas source (29), a valve (30), and a booster pump (31); the inert gas source (29) is connected to the inlet of the booster pump (31) through the valve (30), and the outlet of the booster pump (31) is connected to the reactor (12).

2. The apparatus for detecting the rate of solution according to claim 1, wherein The top of the reactor (12) is provided with a sealing cover (14) and a fastening bolt (15). The sealing cover (14) is connected to the top of the reactor (12) by the fastening bolt (15).

3. The apparatus of claim 1, wherein The reactor (12) is equipped with a carbon dioxide sensor (16), a digital pressure gauge (17), and a digital thermometer (18).

4. The apparatus for detecting the rate of solution according to claim 1, wherein The suction port of the vacuum pump (20) is connected to the reactor (12) through valve two (21).

5. The apparatus of claim 1, wherein The reaction chamber (22) includes a chamber body (23), a sealing cap (24), an electric metering valve (25), a flow guide tube (26), and a sample container (27). The cavity (23) is located inside the reactor (12), and the sealing cover (24) is located at the upper opening of the cavity (23) so that the interior of the cavity (23) forms a sealed space; the electric quantitative valve (25) is located on the sealing cover (24) to connect the interior of the reactor (12) and the interior of the cavity (23); one end of the guide pipe (26) is connected to the electric quantitative valve (25), and the other end is connected to the sample container (27) located on the thermal balance (28), and the coal sample is located inside the sample container (27).

6. The apparatus for detecting the rate of solution according to claim 5, wherein Multiple thermal balances (28) are installed inside the cavity (23), and the thermal balances (28), sample containers (27) and guide tubes (26) are installed one by one.

7. The apparatus according to any one of claims 1 to 6, wherein The fluid supply assembly (100) includes a carbon dioxide gas source (1), valve three (2), booster pump two (3), valve four (4), gas storage tank (5), valve five (6), constant temperature and constant flow pump (7) and valve six (8) connected in sequence. The outlet end of valve six (8) is connected to the reactor (12).

8. The apparatus for detecting the rate of solution according to claim 7, wherein The fluid supply assembly (100) also includes an electromagnetic flow meter 1 (9), an electromagnetic flow meter 2 (10), and a digital pressure gauge 2 (11). The electromagnetic flow meter 1 (9) is connected between valve 3 (2) and booster pump 2 (3), the electromagnetic flow meter 2 (10) is connected between booster pump 2 (3) and valve 4 (4), and the digital pressure gauge 2 (11) is connected to the gas storage tank (5).

9. The apparatus of claim 1, wherein, The purging assembly (200) also includes a valve seven (32) disposed between the booster pump one (31) and the reactor (12).

10. The apparatus according to any one of claims 1 to 6, wherein It also includes an exhaust gas collection assembly (300); The tail gas collecting assembly (300) comprises a collecting cavity (33), a valve eight (34), a carbon dioxide sensor two (35), an inert gas sensor (36), a digital pressure gauge three (37) and a digital thermometer two (38); the collecting cavity (33) is communicated with the reaction kettle (12) through the valve eight (34), the carbon dioxide sensor two (35) and the inert gas sensor (36) are arranged in the collecting cavity (33); the digital pressure gauge three (37) and the digital thermometer two (38) are communicated with the collecting cavity (33).

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