Device and method for testing negative carbon content in the whole process of carbon dioxide sequestration by filling body

Abstract

A device and method for testing the negative carbon content during the whole process of carbon dioxide sequestration in backfill. The device includes a carbonation subsystem for backfill carbon dioxide sequestration, a high-pressure gas injection subsystem, a triaxial stress loading subsystem, a constant temperature control subsystem, a data acquisition subsystem, and a vacuum pumping subsystem. The stress loading subsystem and the constant temperature control subsystem are used to simulate real backfill sequestration conditions. Helium and carbon dioxide are respectively injected through the high-pressure gas injection subsystem to measure the free space volume of the reaction kettle, the negative carbon content of the backfill, and the permeability. The present invention solves the problem that it is difficult to accurately measure the sequestration capacity and sequestration efficiency in the existing simulation tests of carbon dioxide sequestration in backfill. It can realize the whole process simulation test of carbon dioxide sequestration in backfill under triaxial stress loading, temperature control, and gas injection pressure control, and can accurately test the negative carbon content and permeability of the backfill during the whole sequestration process, providing experimental support for the exploration of the mechanism of carbon dioxide sequestration in backfill and its field application of the technology.

Description

Technical Field

[0001] The present invention relates to the technical field of underground carbon dioxide sequestration, and particularly to a device and method for measuring the negative carbon amount in the whole process of carbon dioxide sequestration in a filling body. Background Art

[0002] The production and combustion of fossil fuels such as coal will generate a large amount of carbon dioxide and polluting gases, which are one of the main sources of carbon emissions. In addition, the output of coal-based solid wastes such as coal gangue and fly ash generated during the exploitation and utilization of coal is huge, and improper treatment will further cause ecological environmental pollution. How to achieve large-scale disposal of coal-based solid wastes while sequestering carbon dioxide is a key problem in the low-carbon and green development of coal.

[0003] During the process of carbon dioxide flowing and migrating in the filling body, it continuously contacts the pore surface of the filling body and undergoes physical and chemical reactions such as adsorption, dissolution, and mineralization, enabling carbon dioxide to be stably sequestered inside the filling body. Clearly defining the sequestration capacity and sequestration efficiency of the filling body is crucial for the field application of the technology of sequestering carbon dioxide in the filling body. The in-situ stress environment of the mine and the physical property parameters of the filling body can directly affect the pore permeability characteristics of the filling body, thereby causing changes in the sequestration capacity and sequestration efficiency of the filling body. Therefore, when evaluating the sequestration capacity and stability of carbon dioxide sequestration in the filling body, the stress state of the filling body must be considered. In addition, the injection pressure and formation temperature of carbon dioxide will cause changes in the thermodynamic properties of carbon dioxide, which in turn affect the sequestration capacity and sequestration efficiency of the filling body. Therefore, it is necessary to study the sequestration law of the filling body under triaxial stress conditions. However, the existing devices only consider the adsorption effect of coal and rock, and cannot achieve long-term simulation tests of carbon dioxide sequestration in the filling body under triaxial stress conditions, and cannot accurately calculate the negative carbon amount and permeability in the whole process of carbon dioxide sequestration in the filling body. Summary of the Invention

[0004] Technical Problem to be Solved: Aiming at the problem that it is difficult to accurately and long-term measure the sequestration capacity and sequestration efficiency in the simulation test of carbon dioxide sequestration in coal and rock in the prior art, the present invention provides a device and method for measuring the negative carbon amount in the whole process of carbon dioxide sequestration in a filling body. The device uses a stress loading subsystem and a constant temperature control subsystem to simulate the mine filling and sequestration environment, and sequentially injects helium and carbon dioxide through a high-pressure gas injection subsystem, and measures the free space volume of the reaction kettle, the negative carbon amount and permeability of the filling body. The method of the present invention can accurately monitor the negative carbon amount and permeability in the whole process of carbon dioxide sequestration in the filling body, obtain the variation law of the negative carbon amount of the filling body with time, and use it to analyze the mechanism of carbon dioxide sequestration in the filling body.

[0005] Technical solution: One of the objectives of the present invention is to provide a device for measuring the negative carbon amount in the whole process of carbon dioxide sequestration in a filling body. The measuring device includes: a filling body carbon sequestration subsystem, a high-pressure gas injection subsystem, a triaxial stress loading subsystem, a constant temperature control subsystem, a vacuum pumping subsystem, and a data acquisition subsystem.

[0006] The main structure of the filling body carbon sequestration subsystem is a reaction kettle, and the reaction kettle is a horizontal triaxial core holder with the rock sample replaced by a filling body sample, including a confining pressure structure arranged around the filling body sample, an axial pressure structure arranged at one end of the filling body sample, and horizontal air inlet holes and air outlet holes arranged at both ends of the filling body sample. A confining pressure inlet is provided on the confining pressure structure, and an axial pressure inlet is provided on the axial pressure structure.

[0007] The high-pressure gas injection subsystem includes a standard chamber, a CO2 pressurization pipeline, and a He pressurization pipeline. The CO2 pressurization pipeline includes a high-pressure CO2 storage tank, and the He pressurization pipeline includes a high-pressure He storage tank. One end of the standard chamber is respectively connected to the high-pressure CO2 storage tank and the high-pressure He storage tank through pipelines, and the other end is connected to the air inlet hole of the reaction kettle. A valve c and a pressure sensor a are provided at the outlet of the high-pressure CO2 storage tank, a valve d and a pressure sensor b are provided at the outlet of the high-pressure He storage tank, a valve e and a pressure sensor c are provided at the outlet of the standard chamber, and a valve f and a pressure sensor d are provided at the air inlet hole of the reaction kettle.

[0008] The triaxial stress loading subsystem includes an axial pressure pump and a confining pressure pump, and the axial pressure pump and the confining pressure pump are respectively connected to the confining pressure inlet and the axial pressure inlet through pipelines.

[0009] The constant temperature control subsystem includes a constant temperature water bath and a temperature sensor connected thereto. The constant temperature water bath is arranged outside the reaction kettle and the standard chamber for adjusting the temperature.

[0010] The vacuum pumping subsystem includes a vacuum pump, and the vacuum pump is connected to the air outlet hole of the reaction kettle. A pressure sensor f is provided at the inlet of the vacuum pump, and a pressure sensor e and a valve g are sequentially provided at the air outlet hole of the reaction kettle.

[0011] The data acquisition subsystem includes a data acquisition unit and a data analysis unit. The data acquisition unit includes a pressure sensor a, a pressure sensor b, a pressure sensor c, a pressure sensor d, a pressure sensor e, a pressure sensor f, and a temperature sensor. The data analysis unit is a controller and a display. The input end of the controller is respectively electrically connected to the pressure sensor a, the pressure sensor b, the pressure sensor c, the pressure sensor d, the pressure sensor e, the pressure sensor f, and the temperature sensor, and the output end is electrically connected to the display.

[0012] Preferably, the carbon-negative amount testing device for the whole process of carbon dioxide sequestration in the filling body further includes a seepage monitoring subsystem, which includes a condenser, a saturated sodium bicarbonate solution storage tank, and an electronic balance connected in sequence through pipelines. The intake end of the condenser is connected to the air outlet of the reaction kettle through a pipeline. A valve j and a gas flow sensor are provided at the intake end of the condenser. The electronic balance is used to weigh the mass of the solution discharged from the saturated sodium bicarbonate solution storage tank. The gas flow sensor and the electronic balance are respectively electrically connected to the input end of the controller.

[0013] Preferably, the CO2 pressurization pipeline further includes a CO2 gas cylinder, a booster pump a, and an air compressor a. The CO2 gas cylinder, valve a, booster pump a, pressure sensor a, valve c, and high-pressure CO2 storage tank are connected in sequence through pipelines. The pipeline between the pressure sensor a and the valve c is connected to the standard chamber. The air compressor a is connected to the booster pump a to provide gas pressure. The He pressurization pipeline further includes a He gas cylinder, a booster pump b, and an air compressor b. The He gas cylinder, valve b, booster pump b, pressure sensor b, valve d, and high-pressure He storage tank are connected in sequence through pipelines. The pipeline between the pressure sensor b and the valve d is connected to the standard chamber. The air compressor and the booster pump b are connected to provide gas pressure.

[0014] Preferably, the reaction kettle includes a reaction kettle cylinder body, a piston, a plug, a first compression cap, a second compression cap, a first fixed collar, a second fixed collar, and a rubber sleeve. The rubber sleeve is axially arranged inside the reaction kettle cylinder body. The rubber sleeve has an axially penetrating cavity for accommodating the filling body sample to be tested. The first compression cap and the second compression cap are respectively embedded around the piston and the plug and are arranged at both ends of the reaction kettle cylinder body. The first fixed collar and the second fixed collar are respectively arranged at both ends of the rubber sleeve and respectively abut against the inner ends of the first compression cap and the second compression cap. The piston passes through the first compression cap and is arranged inside the inner cavity of the first fixed collar and can move left and right in the cavity. The plug passes through the second compression cap and is arranged inside the second fixed collar, and the inner end of the plug abuts against the side end of the filling body sample. Axial central holes are opened in the piston and the plug to form a horizontal air inlet and an air outlet for air inlet and outlet at both ends of the filling body sample. The outer wall of the rubber sleeve, the inner wall of the reaction kettle cylinder body, and the first fixed collar and the second fixed collar at both ends form a confining pressure chamber. The confining pressure inlet is arranged on the reaction kettle cylinder body. The cavity formed by the piston, the first compression cap, and the first fixed collar is the axial pressure chamber, and the axial pressure inlet is arranged on the first compression cap.

[0015] Preferably, the reaction kettle further includes a bracket, which is arranged at the bottom of the reaction kettle to support the reaction kettle.

[0016] Preferably, the vacuum subsystem further includes a buffer device disposed between the pipeline connecting the pressure sensor f and the valve g. Moreover, a valve h is provided at the inlet of the buffer device, a valve i is provided at one outlet, and the other outlet is connected to the pressure sensor f through a pipeline.

[0017] Another object of the present invention is to provide a method for testing the whole-process negative carbon amount of carbon dioxide sequestration in a filling body based on the above-mentioned testing device for the whole-process negative carbon amount of carbon dioxide sequestration in a filling body. The steps are as follows:

[0018] Step 1: Place the filling body specimen into the reaction kettle and connect the testing device for the whole-process negative carbon amount of carbon dioxide sequestration in the filling body.

[0019] Step 2: Close all valves, open valve d and valve e, inject He into the standard chamber, and then open valve f for airtightness detection of the device.

[0020] Step 3: Close all valves, open valve e, valve f, and valve g, and turn on the vacuum pump to create a vacuum in the device.

[0021] Step 4: Set the temperature of the constant temperature water bath and apply axial pressure and confining pressure through the triaxial stress loading subsystem.

[0022] Step 5: Close all valves, open valve d and valve e, inject He into the standard chamber, close valve d, and wait until the reading of the pressure sensor c stabilizes at P S1 . Then open valve f. When the readings of the pressure sensor c and the pressure sensor d are the same and stable at P R2 , calculate the free space volume of the device, that is, the pore volume Vs of the filling body in the reaction kettle. The calculation formula is as follows:

[0023]

[0024] In the formula, V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the filling body in the reaction kettle, cm 3 ; P S1 is the initial He pressure in the standard chamber, Mpa; P R2 is the stable He pressure in the reaction kettle, MPa; Z S1 and Z R2 are the compression factors of the initial He in the standard chamber and the stable He in the reaction kettle respectively, which are obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States.

[0025] Step 6: Close all valves, open valve e, valve f, and valve g. Turn on the vacuum pump to create a vacuum in the device, then close valve f and valve g. Open valve c to inject CO2 into the standard chamber, and then close valve c. When the reading of pressure sensor c stabilizes at P S3 open valve f. When the readings of pressure sensor c and pressure sensor d are the same and stable at P R4 calculate the carbon sequestration amount of the filling body. The formula is as follows:

[0026]

[0027] In the formula, P S3 is the initial CO2 pressure in the standard chamber, in Mpa; P R4 is the stable CO2 pressure in the reactor, in MPa; V R is the volume of the standard chamber, in cm 3 ; V S is the pore volume of the filling body in the reactor, in cm 3 ; Z S3 and Z R4 are the compression factors of the initial CO2 in the standard chamber and the stable CO2 in the reactor respectively, obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States; n b is the carbon sequestration amount per unit mass of the filling body, in mmol / g; n b1 and n b2 are the amount of substance of the initial CO2 in the standard chamber and the amount of substance of CO2 in the standard chamber and the reactor after the start of sequestration respectively, in mmol; M is the mass of the filling body, in g; R is the universal gas constant, 8.31 J / (mol・K); T is the temperature of the constant temperature water bath, in K;

[0028] Step 7: When the CO2 injection time reaches the target number of days, close valve e and valve f. Calculate the free carbon sequestration amount of the filling body according to the reading P R5 of pressure sensor d. The calculation formula is as follows:

[0029]

[0030] In the formula, n f is the free carbon sequestration amount of the filling body, in mmol / g; P R5 is the pressure in the reactor, in MPa; V S is the pore volume of the filling body in the reactor, in cm 3 ; Z R5 is the compression factor of CO2 in the reactor, obtained by querying the carbon dioxide compression factor diagram at different temperatures and pressures; M is the mass of the filling body, in g; R is the universal gas constant, 8.31 J / (mol・K); T is the temperature of the constant temperature water bath, in K.

[0031] Preferably, the method further includes a permeability test, and the specific steps are as follows:

[0032] Step 1: Place the filling body specimen into the reaction kettle and connect the whole-process negative carbon amount test device for the filling body to seal carbon dioxide.

[0033] Step 2: Close all valves, open valve d and valve e, inject He into the standard chamber, and then open valve f for airtightness detection of the device.

[0034] Step 3: Close all valves, open valve e, valve f, and valve g, and turn on the vacuum pump to create a vacuum in the device.

[0035] Step 4: Set the temperature of the constant temperature water bath and apply axial pressure and confining pressure through the triaxial stress loading subsystem.

[0036] Step 5: Close all valves, open valve d and valve e, inject He into the standard chamber, close the valve, and wait until the reading of pressure sensor c is stable at P S1 After that, open valve f. When the readings of pressure sensor c and pressure sensor d are the same and stable at P R2 Calculate the free space volume of the device, that is, the pore volume Vs of the filling body in the reaction kettle. The calculation formula is as follows:

[0037]

[0038] In the formula, V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the filling body in the reaction kettle, cm 3 ; P S1 is the initial He pressure in the standard chamber, Mpa; P R2 is the stable He pressure in the reaction kettle, MPa; Z S1 , Z R2 are the compression factors of the initial He in the standard chamber and the stable He in the reaction kettle respectively, which are obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States.

[0039] Step 6: Close all valves, open valve e, valve f, and valve g, turn on the vacuum pump to create a vacuum in the device, close valve f and valve g, open valve c, inject CO2 into the standard chamber, close valve c, and wait until the reading of pressure sensor c is stable at P R6 After that, open valve f and valve j and start timing. When the readings of pressure sensor c and pressure sensor d are the same and stable at P R7 Stop timing, record the seepage time as T, and read the reading of pressure sensor e as P R8, monitor the readings of the gas flow sensor and the electronic balance, and calculate the CO2 permeability in the filling body. The calculation formula is as follows:

[0040] ,

[0041] In the formula, k is the CO2 permeability; μ is the dynamic viscosity of CO2, Pa·s; Q is the total seepage flow rate of CO2, m 3 ; L is the length of the filling body, m; A is the cross-sectional area of the port of the filling body, m 2 ; T is the seepage time, s; P R6 , P R7 , P R8 are the initial pressure at the inlet end of the reaction kettle, the final pressure at the inlet end of the reaction kettle, and the final pressure at the outlet end of the reaction kettle, respectively, MPa.

[0042] Preferably, when the seepage flow rate does not exceed 0.001 m 3 / min, the gas flow sensor is used to calculate the total seepage flow rate Q of CO2; when the seepage flow rate is greater than 0.001 m 3 / min, the drainage method is used to calculate the total seepage flow rate Q of CO2 through the electronic balance.

[0043] Beneficial effects: Permeability and carbon sequestration amount are two key parameters of the technology for filling and storing carbon dioxide, which can characterize the carbon dioxide storage capacity and CO2 flow characteristics of the filling body and are important indicators for evaluating the effect of filling and storing carbon dioxide. However, in the current existing technologies, the measurement of carbon sequestration amount is mostly used for coal and rock samples, and only the mineralization or adsorption carbon sequestration amount is considered separately. The overall carbon sequestration amount of the sample under various CO2 storage effects such as mineralization, adsorption, dissolution, and free storage is not comprehensively considered, and the influence of CO2 injection time on the carbon sequestration amount of the sample is not considered either. Therefore, the present invention proposes a device and method for measuring the negative carbon amount in the whole process of filling and storing carbon dioxide in a filling body. By using a stress loading subsystem and a constant temperature control subsystem to simulate real filling and storing conditions, helium and carbon dioxide are injected in sequence through a high-pressure gas injection subsystem, and the free space volume of the reaction kettle, the negative carbon amount and permeability of the filling body are measured, which can accurately, real-time and quickly monitor the negative carbon amount and permeability in the whole process of filling and storing carbon dioxide in the filling body, ensuring the reliability and accuracy of the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of a device for measuring the negative carbon amount in the whole process of filling and storing carbon dioxide in the present invention;

[0045] Figure 2 is a schematic structural diagram of the reaction kettle in the present invention;

[0046] Figure 3 is a schematic diagram of the data acquisition unit in the present invention;

[0047] The numbers and labels in the figure represent the following: 1. CO2 gas cylinder; 2. He gas cylinder; 3. Valve a; 4. Valve b; 5. Booster pump a; 6. Air compressor a; 7. Air compressor b; 8. Booster pump b; 9. Pressure sensor a; 10. Pressure sensor b; 11. Valve c; 12. Valve d; 13. High-pressure CO2 storage tank; 14. High-pressure He storage tank; 15. Standard chamber; 16. Valve e; 17. Pressure sensor c; 18. Valve f; 19. Pressure sensor d; 20. Reactor; 21. Pressure sensor e; 22. Valve g; 23. Valve h; 24. Buffer device; 25. Valve i; 26. Pressure sensor f; 27. Vacuum pump; 28. Valve j; 29. Gas flow sensor; 30. Condenser; 31. Saturated sodium bicarbonate solution storage tank; 32. Electronic balance; 33. Axial pressure pump; 34. Confining pressure pump; 35. Support; 36. Temperature sensor; 37. Constant temperature water bath; 38. Data analysis unit; 39. Data acquisition unit; 40. Data acquisition subsystem; 41. Reactor cylinder; 42. Piston; 43. Plug; 44. First compression cap; 45. Second compression cap; 46. First fixed collar; 47. Second fixed collar; 48. Filling body sample; 49. Rubber sleeve; 50. Confining pressure inlet; 51. Confining pressure chamber; 52. Axial pressure inlet; 53. Axial pressure chamber; 54. Air inlet hole; 55. Air outlet hole. Specific implementation mode

[0048] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] Embodiment

[0050] As Figure 1 shown, a full-process negative carbon amount testing device for carbon dioxide sequestration in a filling body provided by an embodiment of the present invention includes: a carbonation sequestration subsystem for filling body, a high-pressure gas injection subsystem, a triaxial stress loading subsystem, a constant temperature control subsystem, a vacuum pumping subsystem, a data acquisition subsystem 40, and a seepage monitoring subsystem.

[0051] Among them, the main structure of the carbonation sequestration subsystem for filling body is the reactor 20. The reactor 20 is a horizontal triaxial core holder, and the core therein is replaced by a filling body sample 48 (in this embodiment, the filling body sample 48 is a cylinder with a diameter of 50 mm and a height of 100 mm), including a confining pressure structure arranged around the filling body sample 48, an axial pressure structure arranged at one end of the filling body sample 48, and horizontal air inlet holes 54 and air outlet holes 55 arranged at both ends of the filling body sample 48. A confining pressure inlet 50 is arranged on the confining pressure structure, and an axial pressure inlet 52 is arranged on the axial pressure structure.

[0052] Furthermore, as Figure 2 shown, the reactor 20 includes a reactor cylinder body 41, a piston 42, a plug 43, a first compression cap 44, a second compression cap 45, a first fixed collar 46, a second fixed collar 47, and a rubber sleeve 49. The rubber sleeve 49 is axially disposed inside the reactor cylinder body 41. The rubber sleeve 49 has an axially penetrating cavity for accommodating the test filling body sample 48. The first compression cap 44 and the second compression cap 45 are respectively embedded around the piston 42 and the plug 43 and are disposed at both ends of the reactor cylinder body 41. The first fixed collar 46 and the second fixed collar 47 are respectively disposed at both ends of the rubber sleeve 49 and respectively abut against the inner ends of the first compression cap 44 and the second compression cap 45. The piston 42 passes through the first compression cap 44 and is disposed inside the inner cavity of the first fixed collar 46 and can move left and right in the cavity. The plug 43 passes through the second compression cap 45 and is disposed inside the inner cavity of the second fixed collar 47, and the inner end of the plug 43 abuts against the side end of the filling body sample 48. Axial center openings are formed in the piston 42 and the plug 43 to form a horizontal air inlet hole 54 and an air outlet hole 55 for air inlet and outlet at both ends of the filling body sample 48. The outer wall of the rubber sleeve 49, the inner wall of the reactor cylinder body 41, and the first fixed collar 46 and the second fixed collar 47 at both ends form a confining pressure chamber 51. The confining pressure inlet 50 is disposed on the reactor cylinder body 41. The cavity formed by the piston 42, the first compression cap 44, and the first fixed collar 46 is an axial pressure chamber 53, and the axial pressure inlet 52 is disposed on the first compression cap 44.

[0053] Furthermore, the reactor 20 further includes a bracket 35. The bracket 35 is disposed at the bottom of the reactor 20 for supporting the reactor 20.

[0054] The high-pressure gas injection subsystem includes a standard chamber 15 (with a volume of 100 mL in this embodiment), a CO2 pressurization pipeline, and a He pressurization pipeline. The CO2 pressurization pipeline includes a high-pressure CO2 storage tank 13, and the He pressurization pipeline includes a high-pressure He storage tank 14. One end of the standard chamber 15 is respectively connected to the high-pressure CO2 storage tank 13 and the high-pressure He storage tank 14 through pipelines, and the other end is connected to the air inlet hole 54 of the reactor 20. A valve c 11 and a pressure sensor a 9 are provided at the outlet of the high-pressure CO2 storage tank 13, a valve d 12 and a pressure sensor b 10 are provided at the outlet of the high-pressure He storage tank 14, a valve e 16 and a pressure sensor c 17 are provided at the outlet of the standard chamber 15, and a valve f 18 and a pressure sensor d 19 are provided at the air inlet hole 54 of the reactor 20.

[0055] Further, the CO2 pressurization pipeline further includes a CO2 gas cylinder 1, a booster pump a 5, and an air compressor a 6. The CO2 gas cylinder 1, valve a 3, booster pump a 5, pressure sensor a 9, valve c 11, and high-pressure CO2 storage tank 13 are sequentially connected by pipelines. The pipeline between the pressure sensor a 9 and the valve c 11 is connected to the standard chamber 15. The air compressor a 6 is connected to the booster pump a 5 to provide gas pressure. The He pressurization pipeline further includes a He gas cylinder 2, a booster pump b 8, and an air compressor b 7. The He gas cylinder 2, valve b 4, booster pump b 8, pressure sensor b 10, valve d 12, and high-pressure He storage tank 14 are sequentially connected by pipelines. The pipeline between the pressure sensor b 10 and the valve d 12 is connected to the standard chamber 15. The air compressor b 7 is connected to the booster pump b 8 to provide gas pressure.

[0056] The triaxial stress loading subsystem includes an axial pressure pump 33 and a confining pressure pump 34. The axial pressure pump 33 and the confining pressure pump 34 are respectively connected to the axial pressure inlet 52 and the confining pressure inlet 50 by pipelines.

[0057] The constant temperature control subsystem includes a constant temperature water bath 37 and a temperature sensor 36 connected thereto. The constant temperature water bath 37 is provided outside the reaction kettle 20 and the standard chamber 15 for adjusting the temperature.

[0058] The vacuum pumping subsystem includes a vacuum pump 27. The vacuum pump 27 is connected to the air outlet 55 of the reaction kettle 20. A pressure sensor f 26 is provided at the inlet of the vacuum pump. A pressure sensor e 21 and a valve g 22 are sequentially provided at the air outlet of the reaction kettle 20.

[0059] Further, the vacuum pumping subsystem further includes a buffer device 24. The buffer device 24 is provided between the pipelines connecting the pressure sensor f26 and the valve g 22. And, a valve h 23 is provided at the inlet of the buffer device 24, a valve i 25 is provided at one outlet, and the other outlet is connected to the pressure sensor f 26 by a pipeline.

[0060] The seepage monitoring subsystem includes a condenser 30, a saturated sodium bicarbonate solution storage tank 31, and an electronic balance 32 that are sequentially connected by pipelines. The intake end of the condenser 30 is connected to the air outlet 55 of the reaction kettle 20 by a pipeline. A valve j 28 and a gas flow sensor 29 are provided at the intake end of the condenser 30. The electronic balance 32 is used to weigh the mass of the solution discharged from the saturated sodium bicarbonate solution storage tank 31. The gas flow sensor 29 and the electronic balance 32 are respectively electrically connected to the input end of the controller.

[0061] The data acquisition subsystem 40 includes a data acquisition unit 39 and a data analysis unit 38. The data acquisition unit 39 includes a pressure sensor a 9, a pressure sensor b 10, a pressure sensor c 17, a pressure sensor d 19, a pressure sensor e 21, a pressure sensor f 26, a gas flow sensor 29, an electronic balance 32, and a temperature sensor 36. The data analysis unit 38 is a controller and a display. The input end of the controller is electrically connected to the pressure sensor a 9, the pressure sensor b 10, the pressure sensor c 17, the pressure sensor d 19, the pressure sensor e 21, the pressure sensor f 26, the gas flow sensor 29, the electronic balance 32, and the temperature sensor 36 respectively, and the output end is electrically connected to the display.

[0062] As Figure 3 shown, the data types of the data acquisition unit 39 include gas pressure, loading stress, temperature, and seepage flow rate. The gas pressure includes the high-pressure CO2 storage tank pressure, the high-pressure He storage tank pressure, the standard chamber pressure, the reaction kettle inlet end pressure, the reaction kettle outlet end pressure, and the vacuum pumping pressure. The loading stress specifically includes axial pressure and confining pressure. The temperature is the temperature of the constant temperature water bath. The seepage flow rate includes the gas flow rate at the reaction kettle outlet end and the mass of the discharged saturated sodium bicarbonate solution.

[0063] A method for testing the whole-process negative carbon amount of carbon dioxide sequestration in a filling body based on the above-mentioned whole-process negative carbon amount testing device for carbon dioxide sequestration in a filling body is as follows:

[0064] Step 1: Place the filling body specimen 48 into the reaction kettle and connect the whole-process negative carbon amount testing device for carbon dioxide sequestration in the filling body.

[0065] Step 2: Close all valves, open valve b 4, valve d 12, booster pump b 8, and air compressor b 7, inject He into the high-pressure He storage tank 14. After reaching the preset gas pressure (16 MPa in this embodiment), close valve b 4, booster pump b 8, and air compressor b 7, and open valve e 16 to inject He into the standard chamber 15. Then open valve f 18 for device airtightness detection. If the change amount of the reading of the pressure sensor d 19 is less than 0.002 MPa during the 2-hour process, it indicates that the device has good airtightness.

[0066] Step 3: Close all valves, open valve e 16, valve f 18, valve g 22, and valve h 23, turn on the vacuum pump 27 to create a vacuum in the device. When the reading of the pressure sensor f 26 becomes 0, turn off the vacuum pump.

[0067] Step 4: Set the temperature of the constant temperature water bath 37, and apply axial pressure and confining pressure through the triaxial stress loading subsystem. The experimental temperature range is from room temperature to 100 °C, the axial pressure range is from 0 to 20 MPa, and the confining pressure range is from 0 to 20 MPa.

[0068] Step 5: Close all valves, open valve b 4, valve d 12, booster pump b 8, and air compressor b 7, and inject He into the high-pressure He storage tank 14. After reaching the preset gas pressure (1 - 16 MPa), close valve b 4, booster pump b 8, and air compressor b 7, and open valve e 16 to inject He into the standard chamber 15. Wait until the reading of pressure sensor c 17 stabilizes at P S1 After that, close valve d 12, open valve f 18. When the readings of pressure sensor c 17 and pressure sensor d 19 are the same and stable at P R2 At this time, calculate the free space volume of the device, that is, the pore volume Vs of the reactor filling body. The calculation formula is as follows:

[0069]

[0070] In the formula, V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the reactor filling body, cm 3 ; P S1 is the initial He pressure in the standard chamber, Mpa; P R2 is the stable He pressure in the reactor, MPa; Z S1 、Z R2 are the compression factors of the initial He in the standard chamber and the stable He in the reactor respectively, which are obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States (see Table 1 below);

[0071] Table 1 Compression factors of helium at 0 - 16 MPa, 20 - 100 °C

[0072]

[0073] Step 6: Close all valves, open valve e 16, valve f 18, valve g 22, and valve h 23. Turn on the vacuum pump 27 to create a vacuum in the device. When the reading of pressure sensor f 26 becomes 0, turn off the vacuum pump 27, close valve f 18, valve g 22, and valve h 23, and open valve a 3, valve c 11, booster pump a 5, and air compressor a 6 to inject CO2 into the high-pressure CO2 storage tank 13. After reaching the preset gas pressure (1 - 16 MPa), close valve a 3, booster pump a 5, and air compressor a 6, and open valve e 16 to inject CO2 into the standard chamber 15. When the reading of pressure sensor c 17 stabilizes at P S3 , close valve c 11, open valve f 18. When the readings of pressure sensor c 17 and pressure sensor d 19 are the same and stable at P R4 , calculate the carbon sequestration amount of the filling body. The formula is as follows:

[0074]

[0075] In the formula, P S3 is the initial CO2 pressure in the standard chamber, Mpa; P R4 is the stable CO2 pressure in the reactor after reaction, MPa; V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the filling body in the reactor, cm 3 ; Z S3 , Z R4 are the compression factors of the initial CO2 in the standard chamber and the stable CO2 in the reactor after reaction, respectively, obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States (see Table 2 below); n b is the carbon sequestration amount per unit mass of the filling body, mmol / g; n b1 , n b2 are the amounts of substance of the initial CO2 in the standard chamber and the amounts of substance of CO2 in the standard chamber and the reactor after the start of sequestration, respectively, mmol; M is the mass of the filling body, g; R is the universal gas constant, 8.31 J / (mol・K); T is the temperature of the constant temperature water bath, K;

[0076] Table 2 Compression factors of carbon dioxide at 0 - 16 MPa, 20 - 100 °C

[0077]

[0078] Step 7: After the CO2 injection time reaches the target number of days (1 - 7 days), close valve e 16 and valve f 18. According to the reading P of pressure sensor d 19 R5Calculate the free carbon sequestration amount of the filling body, and the calculation formula is as follows:

[0079]

[0080] In the formula, n f is the free carbon sequestration amount of the filling body, mmol / g; P R5 is the pressure in the reactor, MPa; V S is the pore volume of the filling body in the reactor, cm 3 ; Z R5 is the compression factor of CO2 in the reactor, which is obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States (see Table 2 above); M is the mass of the filling body, g; R is the universal gas constant, 8.31 J / (mol·K); T is the temperature of the constant temperature water bath, K.

[0081] Furthermore, as one of the preferred embodiments of the present invention, the method further includes a permeability test, and the specific steps are as follows:

[0082] Step 1: Place the filling body specimen 48 into the reactor and connect the test device for the whole process of carbon negative sequestration of the filling body storing carbon dioxide;

[0083] Step 2: Close all valves, open valve b 4, valve d 12, booster pump b 8, and air compressor b 7, inject He into the high-pressure He storage tank 14. After reaching the preset gas pressure (16 MPa in this embodiment), close valve b 4, booster pump b 8, and air compressor b 7, and open valve e 16 to inject He into the standard chamber 15. Then open valve f 18 for airtightness detection of the device. If the change amount of the reading of the pressure sensor d 19 is less than 0.002 MPa during the 2-hour process, it indicates that the device has good airtightness;

[0084] Step 3: Close all valves, open valve e 16, valve f 18, valve g 22, and valve h 23, turn on the vacuum pump 27 to create a vacuum in the device. When the reading of the pressure sensor f 26 becomes 0, turn off the vacuum pump;

[0085] Step 4: Set the temperature of the constant temperature water bath 37, apply axial pressure and confining pressure through the triaxial stress loading subsystem. The experimental temperature range is from room temperature to 100 °C, the axial pressure range is from 0 to 20 MPa, and the confining pressure range is from 0 to 20 MPa;

[0086] Step 5: Close all valves, open valve b 4, valve d 12, booster pump b 8, and air compressor b 7, inject He into the high-pressure He storage tank 14. After reaching the preset gas pressure (1 - 16 MPa), close valve b 4, booster pump b 8, and air compressor b 7, and open valve e 16 to inject He into the standard chamber 15. Wait until the reading of pressure sensor c 17 stabilizes at P S1 After that, close valve d 12, open valve f 18. When the readings of pressure sensor c 17 and pressure sensor d 19 are the same and stable at P R2 Calculate the free space volume of the device, i.e., the pore volume Vs of the reactor filling, and the calculation formula is as follows:

[0087]

[0088] In the formula, V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the reactor filling, cm 3 ; P S1 is the initial He pressure in the standard chamber, Mpa; P R2 is the stable He pressure in the reactor, MPa; Z S1 and Z R2 are the compression factors of the initial He in the standard chamber and the stable He in the reactor respectively, obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States (see Table 1);

[0089] Step 6: Close all valves, open valve e 16, valve f 18, valve g 22, valve h 23, turn on the vacuum pump 27 to create a vacuum in the device. When the reading of pressure sensor f 26 becomes 0, turn off the vacuum pump 27; close valve f 18, valve g 22, valve h 23, open valve a 3, valve c 11, booster pump a 5, and air compressor a 6 to inject CO2 into the high-pressure CO2 storage tank 13. After reaching the preset gas pressure (1 - 16 MPa), close valve a 3, booster pump a 5, and air compressor a 6 and open valve e 16 to inject CO2 into the standard chamber 15. Wait until the reading of pressure sensor c 17 stabilizes at P R6 After that, close valve c 11, open valve f 18 and valve j 28 and start timing. When the readings of pressure sensor c 17 and pressure sensor d 19 are the same and stable at P R7 Stop timing, record the seepage time as T, read the reading P R8 of pressure sensor e 21, monitor the readings of gas flow sensor 29 and electronic balance 32, and calculate the CO2 permeability in the filling, and the calculation formula is:

[0090]

[0091] In the formula, k is the CO2 permeability; μ is the dynamic viscosity of CO2, in Pa·s, which can be obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States (see Table 3); Q is the total seepage flow rate of CO2, in m 3 ; L is the length of the filling body, in m; A is the cross-sectional area of the port of the filling body, in m 2 ; T is the seepage time, in s; P R6 、P R7 、P R8 are respectively the initial pressure at the inlet end of the reactor, the final pressure at the inlet end of the reactor, and the final pressure at the outlet end of the reactor, in MPa.

[0092] Table 3 Dynamic viscosity of carbon dioxide at 0 - 16 MPa and 20 - 100 °C

[0093]

[0094] Furthermore, as one of the preferred embodiments of the present invention, when the seepage flow rate is less than or equal to 0.001 m 3 / min, the gas flow sensor 29 is used to calculate the total seepage flow rate Q of CO2; when the seepage flow rate is greater than 0.001 m 3 / min, the drainage method is adopted and the electronic balance 32 is used to calculate the total seepage flow rate Q of CO2.

[0095] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some 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 invention.

Claims

1. A method for testing the negative carbon content of a filling body during the whole process of carbon dioxide storage, characterized in that: The method includes a permeability test of the filling body, and the specific steps are as follows: Step 1: placing a filling body sample (48) into a reaction kettle, and connecting the filling body to a negative carbon content testing device for the entire process of carbon dioxide storage; Step 2: Close all valves, open valve d (12) and valve e (16), inject He into the standard chamber (15), and then open valve f (18) to perform air tightness test of the device; Step 3: Close all valves, open valve e (16), valve f (18), valve g (22), and turn on the vacuum pump (27) to establish a vacuum in the device; Step 4, setting the temperature of the constant temperature water bath (37), and applying axial pressure and confining pressure through the triaxial stress loading subsystem; Step 5: Close all valves, open valve d (12) and valve e (16), inject He into the standard chamber (15), close valve d (12), and wait until the pressure sensor c (17) indicates a stable reading of P S1 After that, open valve f (18). When the readings of pressure sensor c (17) and pressure sensor d (19) are the same and stable at P R2 When calculating the free space volume of the device, that is, the pore volume Vs of the reactor filling body, the calculation formula is as follows: ， Where V R is the volume of the standard chamber, cm 3 ; V S is the pore volume of the reactor filling, cm 3 ;P S1 is the initial He pressure in the standard chamber, MPa; P R2 is the He pressure after stabilization in the reactor, MPa; Z S1 , Z R2 They are the compression factor of the initial He in the standard chamber and the compression factor of the stabilized He in the reactor, respectively, which are obtained by querying the REFPROP physical property database software developed by the National Institute of Standards and Technology of the United States; Step 6: Close all valves, open valve e (16), valve f (18), valve g (22), open the vacuum pump (27) to create a vacuum in the device, close valve f (18) and valve g (22), open valve c (11), inject CO2 into the standard chamber (15), close valve c (11), and wait until the pressure sensor c (17) indicates a stable reading of P R6 After that, open valve f (18) and valve j (28) and start timing. Wait until the readings of pressure sensor c (17) and pressure sensor d (19) are the same and stable at P. R7 When , stop timing, record the seepage time as T, and read the reading P of the pressure sensor e (21). R8 , monitor the readings of the gas flow sensor (29) and the electronic balance (32), and calculate the permeability of CO2 in the filling body. The calculation formula is: ， Where k is the CO2 permeability; μ is the dynamic viscosity of CO2, Pa·s; Q is the total seepage flow of CO2, m 3 ; L is the length of the filling body, m; A is the port cross-sectional area of ​​the filling body, m 2 ; T is the seepage time, s; P R6 , P R7 , P R8 They are the initial pressure at the reactor inlet, the final pressure at the reactor inlet, and the final pressure at the reactor outlet, in MPa.

2. The method for testing the negative carbon content of a filling body during the whole process of carbon dioxide storage according to claim 1, characterized in that: When the seepage rate does not exceed 0.001m 3 / min, the gas flow sensor (29) is used to calculate the total seepage flow rate Q of CO2; when the seepage flow rate is greater than 0.001m 3 / min, the total seepage flow rate Q of CO2 was calculated by the water displacement method using an electronic balance (32).

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