A dynamic self-test experimental system and method for adsorption and diffusion in a porous medium

Abstract

The present invention discloses a dynamic self-test experimental system and method for adsorption and diffusion of porous media. The system includes a diffusion gas constant-temperature storage system, a high-frequency automatic data acquisition system, a differential pressure automatic leveling system, and a gas constant-temperature adsorption system. The present invention uses the differential pressure automatic leveling system to make the liquid levels of the water storage column and the gas collection column flush, solving the systematic error caused by gas pressure changes; the diffusion gas constant-temperature storage system and the gas constant-temperature adsorption system are used to solve the systematic error caused by gas temperature changes. The high-frequency automatic data acquisition system uses ultrasonic reflection to collect data information, enabling high-frequency and highly accurate readings. Computer programming calculates the total volume of gas diffusion and the gas adsorption amount of porous media, and realizes the dynamic visualization display of experimental data, improving the efficiency of scientific research work. The entire experimental system has a high degree of automation, greatly reducing the errors caused by manual operation, and saving a large amount of time for scientific research personnel at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption and diffusion in porous media, and particularly relates to a dynamic self-test experimental system and method for adsorption and diffusion in porous media. Background Art

[0002] With the rapid economic development in China in recent years, the demand for energy has also been steadily increasing, and the development of coalbed methane and shale gas energy has become a research hotspot. Therefore, studying the desorption and diffusion characteristics of gas in coal and shale is of great significance for the development and utilization of coalbed methane and shale gas. Coal, shale, various gas adsorbents, etc. are all typical porous medium materials, which have complex pore networks inside, and these pore-fracture systems provide the main sites for gas storage and migration. The gas migration in porous media can be divided into adsorption, desorption, diffusion, and seepage. Among them, the adsorption and desorption diffusion of gas mainly occur in micropores and are affected by both the adsorption concentration gradient and the pore structure. A large number of experts and scholars use the adsorption and diffusion coefficients to quantitatively describe the flow characteristics of gas in porous materials, and these parameters often need to be obtained through a large number of experimental tests. These adsorption and diffusion experiments are time-consuming, especially in the gas diffusion stage, and experimental personnel often need to record data at high frequency for a long time. However, at present, most gas diffusion experiments use the water displacement method and read the volume with a graduated cylinder. This experimental method has the following disadvantages: 1. Researchers need to spend a lot of time and energy on manual reading, and it is difficult to collect and record data at high frequency; 2. During the experiment, the liquid level in the graduated cylinder is constantly changing, and there will inevitably be a large error in manual reading by the human eye. Especially in the initial stage of gas diffusion, the speed is relatively fast, and researchers cannot accurately read the value; 3. According to the ideal gas state equation, the gas temperature has a great influence on the volume. Since the whole experimental process often takes more than 4 hours, the change of the external environmental temperature has a great influence on the accuracy of the experiment; 4. When measuring by the water displacement method, there is a pressure difference between the gas in the graduated cylinder and the outside world, and there will be a large error in the gas volume at this time; 5. When measuring by the water displacement method, the graduated cylinder needs to be refilled with water and the airtightness needs to be checked every time an experiment is carried out, and the operation is cumbersome, time-consuming and laborious. Summary of the Invention

[0003] Aiming at the deficiencies of the existing adsorption and desorption experimental devices, the present invention provides a dynamic self-test experimental system and method for adsorption and diffusion in porous media.

[0004] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0005] A dynamic self-test experimental system for adsorption and diffusion in porous media includes: a diffusion gas constant temperature storage system, a high-frequency automatic data acquisition system, a differential pressure automatic leveling system, and a gas constant temperature adsorption system.

[0006] The diffused gas constant temperature storage system includes a gas collecting column and a water storage column that are connected by a hose at the bottom. An air inlet pipe is provided above the gas collecting column. A water pipe is provided on the hose, and a three-way valve is provided on the water pipe. The outer layers of the gas collecting column, the water storage column, the hose, and the air inlet pipe are all sleeved with an outer layer constant temperature water bath pipe. A heating resistance wire is provided inside the outer layer constant temperature water bath pipe. Deionized water is provided inside both the gas collecting column and the water storage column.

[0007] The differential pressure automatic leveling system includes an automatic lifting platform provided below the water storage column. A floating plate is provided above the deionized water liquid level in the gas collecting column. A transmitter facing the direction of the water storage column is provided above the floating plate. An opaque oil is provided above the deionized water liquid level in the water storage column. A strip-shaped induction switch is provided on the side wall of the water storage column far from the gas collecting column. The strip-shaped induction switch is connected to a lifting switch, and the lifting switch adjusts the height of the automatic lifting platform. An exhaust pipe a is provided at the upper end of the gas collecting column, and an exhaust valve a is provided on the exhaust pipe a. An exhaust pipe b is provided at the upper end of the water storage column, and an exhaust valve b is provided on the exhaust pipe b.

[0008] The data high-frequency automatic acquisition system includes an ultrasonic transmitter provided above the water storage column, a metal plate at the bottom end of the water storage column, and a computer connected to the ultrasonic transmitter through a data transmission line.

[0009] The gas constant temperature adsorption system is connected to the air inlet pipe through a pipeline.

[0010] Preferably, the diffused gas constant temperature storage system further includes a digital display water bath temperature controller for adjusting the temperature of the heating resistance wire.

[0011] Preferably, the diffused gas constant temperature storage system further includes a manual lifting platform provided below the gas collecting column.

[0012] Preferably, the ultrasonic transmitter is fixed above the water storage column through a fixed bracket, and the ultrasonic transmitter is powered by a DC power supply through a power cord.

[0013] Preferably, the gas constant temperature adsorption system includes a vacuum pump, an adsorption tank, a reference tank, an adsorption gas cylinder, and a helium gas cylinder. The vacuum pump is connected to the adsorption tank through a pipeline. An electromagnetic valve c is provided on the pipeline between the vacuum pump and the adsorption tank. The first end of the electromagnetic valve d is connected to the pipeline between the electromagnetic valve c and the adsorption tank through a pipeline. The second end of the electromagnetic valve d is connected to the first end of the electromagnetic valve b through a pipeline. The second end of the electromagnetic valve b is respectively connected to the adsorption gas cylinder and the helium gas cylinder through pipelines. The reference tank is connected to the pipeline between the second end of the electromagnetic valve d and the first end of the electromagnetic valve b through a pipeline. A gas pressure sensor is provided on the pipeline at the outlet of the reference tank. The gas pressure sensor is signal-connected to the computer. The inlet of the electromagnetic valve a is connected to the pipeline between the electromagnetic valve c and the adsorption tank through a pipeline. The first outlet of the electromagnetic valve a is connected to the air inlet pipe through a pipeline. The second outlet of the electromagnetic valve a is connected to the external air through a pipeline. The adsorption tank and the reference tank are placed in a water tank, and a water bath heater is provided in the water tank.

[0014] Preferably, the gas constant-temperature adsorption system further includes a constant-temperature water bath controller for controlling the temperature of the water bath heater.

[0015] The present invention also provides a dynamic self-test experimental method for porous medium adsorption and diffusion, comprising the following steps:

[0016] S1: Open the three-way valve to inject deionized water into the water pipe, and adjust the heights of the manual lifting platform and the automatic lifting platform so that the liquid level in the gas collecting column is flush with the exhaust pipe a, and the liquid level in the water storage column is flush with the liquid level in the gas collecting column;

[0017] S2: Place the porous medium solid to be measured into the adsorption tank, open solenoid valve c and solenoid valve d, and use a vacuum pump to evacuate the adsorption tank and the reference tank for 12 hours;

[0018] S3: Close solenoid valve d, open solenoid valve b to fill the reference tank with helium gas at a pressure of p h1 Then close solenoid valve b, open solenoid valve d, and record the pressures p h2 ;

[0019] S4: Open solenoid valve c and solenoid valve d, and use a vacuum pump to evacuate the adsorption tank and the reference tank for 2 hours;

[0020] S5: Close solenoid valve d, open solenoid valve b to fill the reference tank with high-purity adsorption gas at a pressure of p c1 Then close solenoid valve b, open solenoid valve d, and wait for 12 hours to reach adsorption equilibrium, and record the pressures p c2 ;

[0021] S6: Open the second outlet of solenoid valve a to evacuate the free gas in the adsorption tank and the reference tank until the reading of the gas pressure sensor is 0.1 MPa; then close the second outlet of solenoid valve a and open the first outlet of solenoid valve a;

[0022] S7: The gas diffuses from the inlet pipe into the gas collecting column, and the differential pressure automatic leveling system makes the liquid levels of the water storage column and the gas collecting column flush. The change in the gas volume in the gas collecting column is equal to the change in the volume of deionized water in the water storage column. Open the ultrasonic transmitter and the DC power supply, and emit high-frequency ultrasonic waves vertically downward at a fixed time interval. The ultrasonic waves are first reflected by the opaque oil and then reflected by the metal plate at the bottom of the water storage column. The ultrasonic transmitter transmits the reflected signals into the computer through the data transmission line for recording and calculation;

[0023] S8: Open the exhaust valve a and raise the automatic lifting platform. Due to the differential pressure, the gas is discharged from the exhaust pipe a and harmlessly treated until the initial state of the liquid level in step S1 is restored;

[0024] S9: Replace with other porous media solids to be measured, and repeat steps S2 - S8 until the experiment is completed.

[0025] Preferably, in step S7, the computer calculates the gas adsorption amount Q of the porous medium under standard conditions ∞ , and the calculation formula is as follows:

[0026]

[0027] where, T0 and T a are the gas temperatures during gas adsorption and desorption diffusion processes under standard conditions respectively; p h1 is the helium pressure filled into the reference tank; P0 is the gas pressure under standard conditions; p h2 is the helium equilibrium pressure in the adsorption tank; p c1 is the adsorption gas pressure filled into the reference tank; p c2 is the equilibrium pressure of the adsorption gas in the adsorption tank; V c is the volume of the reference tank in the system.

[0028] Preferably, in step S7, the computer calculates the volume ΔV of gas diffusion during the interval between two adjacent emissions of the ultrasonic transmitter d , and the calculation formula is as follows:

[0029]

[0030] where, are the volumes of the liquid column at the first emission and the second emission of two adjacent ultrasonic emissions respectively; v w is the wave speed of ultrasonic waves in water; are the first reflection time and the second reflection time of the first emission of two adjacent ultrasonic emissions respectively; are the first reflection time and the second reflection time of the second emission of two adjacent ultrasonic emissions respectively; A is the cross - sectional area of the water storage column.

[0031] Preferably, the process of the differential pressure automatic leveling system making the liquid levels of the water storage column and the gas collection column flush in step S7 is as follows:

[0032] Gas diffuses from the inlet pipe into the gas collection column, causing the liquid level in the water storage column to rise and the liquid level in the gas collection column to drop. The light emitted by the transmitter passes through the deionized water in the water storage column and irradiates on the strip - shaped induction switch. The strip - shaped induction switch is activated and controls the lifting switch to adjust the height of the automatic lifting platform; until the liquid levels of the water storage column and the gas collection column are flush, the opaque oil blocks the light emitted by the transmitter, the strip - shaped induction switch is deactivated, and the automatic lifting platform maintains the existing height.

[0033] Compared with the prior art, the beneficial effects of the present invention:

[0034] Starting from the overall optimized design of the adsorption, desorption and diffusion experimental system for porous media, this invention uses a differential pressure automatic leveling system and a constant temperature system to solve the systematic errors caused by changes in gas temperature and pressure. The differential pressure automatic leveling system is ingeniously designed, with high sensitivity and strong reliability in photoelectric induction control. By using ultrasonic reflection to read data information, high-frequency and highly accurate readings can be achieved. The data on the equilibrium pressure of gas adsorption and the change in diffusion amount are recorded in real time on a computer, and through formula programming calculation, the dynamic visualization display of experimental data can be realized, improving the efficiency of scientific research work. The entire experimental system has a high degree of automation, greatly reducing the errors caused by human operation and saving a large amount of time for researchers. This invention has a wide range of applications, can conduct adsorption, desorption and diffusion experiments on various porous media, and can also study the effects of different temperatures, different adsorption pressures, and different types of adsorbed gases on the adsorption, desorption and diffusion characteristics of porous media. This invention is simple to operate, has a high degree of automation, accurate data, and wide applicability, and can achieve better experimental results compared with traditional experimental systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic structural diagram of the present invention;

[0037] Figure 2 It is the gas diffusion rate curve of porous media under the equilibrium pressure of different adsorbed gases, where Qt is the cumulative gas diffusion amount.

[0038] In the figure: 1 - intake pipe; 2 - outer constant temperature water bath pipe; 3 - exhaust valve a; 4 - exhaust pipe a; 5 - emitter; 6 - floating plate; 7 - deionized water; 8 - heating resistance wire; 9 - three-way valve; 10 - hose; 11 - water pipe; 12 - manual lifting platform; 13 - exhaust pipe b; 14 - exhaust valve b; 15 - digital display water bath temperature controller; 16 - DC power supply; 17 - power cord; 18 - ultrasonic emitter; 19 - fixing bracket; 20 - water storage column; 21 - gas collecting column; 22 - light-proof oil; 23 - strip-shaped induction switch; 24 - metal plate; 25 - lifting switch; 26 - automatic lifting platform; 27 - computer; 28 - data transmission line; 29 - vacuum pump; 30 - solenoid valve a; 31 - solenoid valve b; 32 - solenoid valve c; 33 - solenoid valve d; 34 - constant temperature water bath controller; 35 - water tank; 36 - ventilation pipeline; 37 - adsorption tank; 38 - gas pressure sensor; 39 - reference tank; 40 - water bath heater; 41 - adsorbed gas cylinder; 42 - helium gas cylinder. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] Embodiment 1

[0041] A porous medium adsorption and diffusion dynamic self-test experimental system includes: a diffusion gas constant temperature storage system, a data high-frequency automatic acquisition system, a differential pressure automatic leveling system, and a gas constant temperature adsorption system.

[0042] The diffusion gas constant temperature storage system includes a gas collecting column 21 and a water storage column 20 that are connected at the bottom through a hose 10. The gas collecting column 21 and the water storage column 20 are cylindrical or cubic columns with equal cross-sections and the cross-sectional areas of the two are the same. The height of the water storage column 20 is twice the height of the gas collecting column 21. A manual lifting platform 12 is provided below the gas collecting column 21. An intake pipe 1 is provided above the gas collecting column 21. A water pipe 11 is provided on the hose 10, and a three-way valve 9 is provided on the water pipe 11. The outer layer of the gas collecting column 21, the water storage column 20, the hose 10, and the intake pipe 1 are all sleeved with an outer constant temperature water bath pipe 2. A heating resistance wire 8 is provided inside the outer constant temperature water bath pipe 2 to maintain the temperature of the gas inside the pipe constant. Deionized water 7 is provided inside both the gas collecting column 21 and the water storage column 20. The temperature of the heating resistance wire 8 is adjusted by a digital display water bath temperature controller 15.

[0043] The differential pressure automatic leveling system includes an automatic lifting platform 26 provided below the water storage column 20. There is a floating plate 6 above the deionized water 7 level in the gas collection column 21. Above the floating plate 6, there is a transmitter 5 facing the direction of the water storage column 20. The transmitter 5 is a laser transmitter or an infrared transmitter. There is an opaque oil 22 above the deionized water 7 level in the water storage column 20. On the side wall of the water storage column 20 far from the gas collection column 21, there is a strip-shaped induction switch 23. The strip-shaped induction switch 23 is connected to a lifting switch 25, and the lifting switch 25 adjusts the height of the automatic lifting platform 26. At the upper end of the gas collection column 21, there is an exhaust pipe a4, and an exhaust valve a3 is provided on the exhaust pipe a4; at the upper end of the water storage column 20, there is an exhaust pipe b13, and an exhaust valve b14 is provided on the exhaust pipe b13. The exhaust valve b14 remains open, so that the inside of the water storage column 20 is at one atmosphere pressure.

[0044] The data high-frequency automatic acquisition system includes an ultrasonic transmitter 18 provided above the water storage column 20, a metal plate 24 at the bottom end of the water storage column 20, and a computer 27 connected to the ultrasonic transmitter 18 through a data transmission line 28; the ultrasonic transmitter 18 is fixed above the water storage column 20 through a fixed bracket 19, and the ultrasonic transmitter 18 is powered by a DC power supply 16 through a power line 17.

[0045] The gas constant-temperature adsorption system includes a vacuum pump 29, an adsorption tank 37, a reference tank 39, an adsorption gas cylinder 41, and a helium gas cylinder 42. The internal volumes of the adsorption tank 37 and the reference tank 39 are equal. The vacuum pump 29 is connected to the adsorption tank 37 through a pipeline 36. An electromagnetic valve c32 is provided on the pipeline 36 between the vacuum pump 29 and the adsorption tank 37. The first end of an electromagnetic valve d33 is connected to the pipeline 36 between the electromagnetic valve c32 and the adsorption tank 37 through a pipeline 36. The second end of the electromagnetic valve d33 is connected to the first end of an electromagnetic valve b31 through a pipeline 36. The second end of the electromagnetic valve b31 is respectively connected to the adsorption gas cylinder 41 and the helium gas cylinder 42 through a pipeline 36. The reference tank 39 is connected to the pipeline 36 between the second end of the electromagnetic valve d33 and the first end of the electromagnetic valve b31 through a pipeline 36. A gas pressure sensor 38 is provided on the pipeline 36 at the outlet of the reference tank 39. The gas pressure sensor 38 is signal-connected to the computer 27. The inlet of an electromagnetic valve a30 is connected to the pipeline 36 between the electromagnetic valve c32 and the adsorption tank 37 through a pipeline 36. The first outlet of the electromagnetic valve a30 is connected to the inlet pipe 1 through a pipeline 36. The second outlet of the electromagnetic valve a30 is connected to the external air through a pipeline 36. The adsorption tank 37 and the reference tank 39 are placed in a water tank 35, and a water bath heater 40 is provided in the water tank 35. The water bath heater 40 controls the temperature through a constant temperature water bath controller 34.

[0046] Example 2

[0047] A dynamic self-test experimental method for porous medium adsorption diffusion includes the following steps:

[0048] S1: Open the three-way valve 9 to inject deionized water 7 into the water pipe 11. Adjust the heights of the manual lifting platform 12 and the automatic lifting platform 26 so that the liquid level in the gas collecting column 21 is flush with the exhaust pipe a4, and the liquid level in the water storage column 20 is flush with the liquid level in the gas collecting column 21.

[0049] S2: Place the porous medium solid to be measured into the adsorption tank 37. Open the solenoid valve c32 and the solenoid valve d33, and use the vacuum pump 29 to evacuate the adsorption tank 37 and the reference tank 39 for 12 hours.

[0050] S3: Close the solenoid valve d33, open the solenoid valve b31 to fill the reference tank 39 with helium gas at a pressure of p h1 Then close the solenoid valve b31, open the solenoid valve d33, and record the pressures p h2 in the adsorption tank 37 and the reference tank 39.

[0051] S4: Open the solenoid valve c32 and the solenoid valve d33, and use the vacuum pump 29 to evacuate the adsorption tank 37 and the reference tank 39 for 2 hours.

[0052] S5: Close the solenoid valve d33, open the solenoid valve b31 to fill the reference tank 39 with high-purity adsorption gas at a pressure of p c1 Then close the solenoid valve b31, open the solenoid valve d33, and wait for 12 hours to reach adsorption equilibrium. Record the pressures p c2 in the adsorption tank 37 and the reference tank 39.

[0053] S6: Open the second outlet of the solenoid valve a30 to evacuate the free gas in the adsorption tank 37 and the reference tank 39 until the reading of the gas pressure sensor 38 is 0.1 MPa, that is, to make the pressures in the adsorption tank 37 and the reference tank 39 the same as the external atmospheric pressure. Then close the second outlet of the solenoid valve a30 and open the first outlet of the solenoid valve a30.

[0054] S7: The gas diffuses from the inlet pipe 1 into the gas collecting column 21, and the differential pressure automatic leveling system makes the liquid levels in the water storage column 20 and the gas collecting column 21 flush. The process is as follows:

[0055] The gas diffuses from the inlet pipe 1 into the gas collecting column 21, causing the liquid level in the water storage column 20 to rise and the liquid level in the gas collecting column 21 to drop. The light emitted by the emitter 5 passes through the deionized water 7 in the water storage column 20 and irradiates on the strip-shaped induction switch 23. The strip-shaped induction switch 23 is activated and controls the lifting switch 25 to adjust the height of the automatic lifting platform 26. Until the liquid levels in the water storage column 20 and the gas collecting column 21 are flush, the light-blocking oil 22 blocks the light emitted by the emitter 5, the strip-shaped induction switch 23 is deactivated, and the automatic lifting platform 26 maintains the existing height.

[0056] The change in the volume of gas in the gas collecting column 21 is equal to the change in the volume of deionized water 7 in the water storage column 20. Turn on the ultrasonic transmitter 18 and the DC power supply 16, and emit ultrasonic waves vertically downward at a fixed time interval. The time interval between two adjacent ultrasonic wave emissions is 2 s. The ultrasonic waves are first reflected when they encounter the opaque oil 22 and are secondarily reflected when they encounter the metal plate 24 at the bottom of the water storage column 20. The ultrasonic transmitter 18 transmits the reflected signal into the computer 27 through the data transmission line 28 for recording and calculation;

[0057] The computer 27 calculates the gas adsorption amount Q of the porous medium under standard conditions ∞ , and the calculation formula is as follows:

[0058]

[0059] Among them, T0 and T a are the gas temperatures during gas adsorption and desorption diffusion processes under standard conditions respectively; p h1 is the helium pressure filled into the reference tank; P0 is the gas pressure under standard conditions; p h2 is the helium gas equilibrium pressure in the adsorption tank; p c1 is the adsorption gas pressure filled into the reference tank; p c2 is the equilibrium pressure of the adsorption gas in the adsorption tank; V c is the volume of the reference tank in the system;

[0060] The computer 27 calculates the volume ΔV of gas diffusion during the interval between two adjacent emissions of the ultrasonic transmitter 18 d , and the calculation formula is as follows:

[0061]

[0062] Among them, are the volumes of the liquid columns at the first emission and the second emission of two adjacent ultrasonic wave emissions respectively; v w is the wave speed of ultrasonic waves in water; are the first reflection time and the second reflection time of the first emission of two adjacent ultrasonic wave emissions respectively; are the first reflection time and the second reflection time of the second emission of two adjacent ultrasonic wave emissions respectively; A is the cross-sectional area of the water storage column 20;

[0063] S8: Open the exhaust valve a3 and raise the automatic lifting platform 26. Due to the pressure difference, the gas is discharged from the exhaust pipe a4 and harmlessly treated until the initial state of the liquid level in step S1 is restored;

[0064] S9: Replace other porous medium solids to be tested and repeat steps S2 - S8 until the experimental work is completed.

[0065] Example 3

[0066] A dynamic self - testing experimental method for the gas adsorption capacity of a porous medium, comprising the following steps:

[0067] S1: Place the porous medium solid to be measured into the adsorption tank 37, open the solenoid valve c32 and the solenoid valve d33, and use the vacuum pump 29 to evacuate the adsorption tank 37 and the reference tank 39 for 12 hours;

[0068] S2: Fill the space above the liquid level of the gas collection column 21 with the adsorption gas. In the initial state, the liquid levels of the water storage column 20 and the gas collection column 21 are flush. The light - impermeable oil 22 blocks the light emitted by the emitter 5, and the strip - shaped induction switch 23 is deactivated;

[0069] S3: Open the second outlet of the solenoid valve a30, and fill the adsorption tank 37 with helium at a standard atmospheric pressure according to the reading of the gas pressure sensor 38, then close the second outlet of the solenoid valve a30;

[0070] S4: Open the first outlet of the solenoid valve a30. The adsorption gas is adsorbed by the porous medium solid in the adsorption tank 37 and reduced, causing the liquid level in the water storage column 20 to drop and the liquid level in the gas collection column 21 to rise. The light emitted by the emitter 5 passes through the water storage column 20 and irradiates on the strip - shaped induction switch 23. The strip - shaped induction switch 23 is activated and controls the lifting switch 25 to adjust the height of the automatic lifting platform 26; until the liquid levels of the water storage column 20 and the gas collection column 21 are flush, the light - impermeable oil 22 blocks the light emitted by the emitter 5, the strip - shaped induction switch 23 is deactivated, and the automatic lifting platform 26 maintains the existing height;

[0071] S5: The change in the gas volume in the gas collection column 21 is equal to the change in the volume of deionized water 7 in the water storage column 20. Open the ultrasonic emitter 18 and the DC power supply 16, and emit ultrasonic waves vertically downward at a fixed time interval. The time interval between two adjacent ultrasonic wave emissions is 2 s. The ultrasonic wave undergoes the first reflection when it encounters the light - impermeable oil 22 and the second reflection when it encounters the metal plate 24 at the bottom of the water storage column 20. The ultrasonic emitter 18 transmits the reflection signal into the computer 27 through the data transmission line 28 and records and calculates it; the computer 27 calculates the volume ΔV of the gas adsorbed during the time interval between two adjacent ultrasonic wave emissions by the ultrasonic emitter 18 d , and the calculation formula is as follows:

[0072]

[0073] Among them, are the volumes of the liquid columns at the first emission and the second emission of ultrasonic waves in two adjacent emissions respectively; v w is the wave speed of ultrasonic waves in water; are the first reflection time and the second reflection time of the first emission of ultrasonic waves in two adjacent emissions respectively; They are respectively the first reflection time and the second reflection time of the second ultrasonic wave emission in two adjacent ultrasonic wave emissions; A is the cross-sectional area of the water storage column 20.

Claims

1. A dynamic self-test experimental system for adsorption and diffusion in a porous medium, characterized in that, Including: A diffusion gas constant temperature storage system, a data high-frequency automatic acquisition system, a differential pressure automatic leveling system, and a gas constant temperature adsorption system. The diffusion gas constant temperature storage system includes a gas collection column (21) and a water storage column (20) whose bottoms are connected by a hose (10). An air inlet pipe (1) is provided above the gas collection column (21). A water pipe (11) is provided on the hose (10), and a three-way valve (9) is provided on the water pipe (11). The outer sides of the gas collection column (21), the water storage column (20), the hose (10), and the air inlet pipe (1) are all sleeved with an outer layer constant temperature water bath tube (2). A heating resistance wire (8) is provided in the outer layer constant temperature water bath tube (2). Deionized water (7) is provided in both the gas collection column (21) and the water storage column (20). The differential pressure automatic leveling system includes an automatic lifting platform (26) provided below the water storage column (20). A floating plate (6) is provided above the liquid level of the deionized water (7) in the gas collection column (21). A transmitter (5) facing the direction of the water storage column (20) is provided above the floating plate (6). An opaque oil (22) is provided above the liquid level of the deionized water (7) in the water storage column (20). A strip-shaped induction switch (23) is provided on the side wall of the water storage column (20) away from the gas collection column (21). The strip-shaped induction switch (23) is connected to a lifting switch (25), and the lifting switch (25) adjusts the height of the automatic lifting platform (26). An exhaust pipe a (4) is provided at the upper end of the gas collection column (21), and an exhaust valve a (3) is provided on the exhaust pipe a (4). An exhaust pipe b (13) is provided at the upper end of the water storage column (20), and an exhaust valve b (14) is provided on the exhaust pipe b (13). The data high-frequency automatic acquisition system includes a ultrasonic transmitter (18) provided above the water storage column (20), a metal plate (24) at the bottom end of the water storage column (20), and a computer (27) connected to the ultrasonic transmitter (18) through a data transmission line (28). The gas constant temperature adsorption system is connected to the air inlet pipe (1) through a pipeline (36). The diffusion gas constant temperature storage system further includes a digital display water bath temperature controller (15) for adjusting the temperature of the heating resistance wire (8). The diffusion gas constant temperature storage system further includes a manual lifting platform (12) provided below the gas collection column (21).

2. The porous medium adsorption and diffusion dynamic self-test experimental system according to claim 1, wherein: The ultrasonic transmitter (18) is fixed above the water storage column (20) through a fixing bracket (19), and the ultrasonic transmitter (18) is powered by a DC power supply (16) through a power cord (17).

3. The porous medium adsorption and diffusion dynamic self-test experimental system according to claim 1, wherein: The gas constant-temperature adsorption system includes a vacuum pump (29), an adsorption tank (37), a reference tank (39), an adsorption gas cylinder (41), and a helium cylinder (42). The vacuum pump (29) is connected to the adsorption tank (37) through a pipeline (36). An electromagnetic valve c (32) is provided on the pipeline (36) between the vacuum pump (29) and the adsorption tank (37). The first end of the electromagnetic valve d (33) is connected to the pipeline (36) between the electromagnetic valve c (32) and the adsorption tank (37) through the pipeline (36). The second end of the electromagnetic valve d (33) is connected to the first end of the electromagnetic valve b (31) through the pipeline (36). The second end of the electromagnetic valve b (31) is respectively connected to the adsorption gas cylinder (41) and the helium cylinder (42) through the pipeline (36). The reference tank (39) is connected between the second end of the electromagnetic valve d (33) and the first end of the electromagnetic valve b (31) through the pipeline (36). A gas pressure sensor (38) is provided on the pipeline (36) at the outlet of the reference tank (39). The gas pressure sensor (38) is signal-connected to a computer (27). The inlet of the electromagnetic valve a (30) is connected to the pipeline (36) between the electromagnetic valve c (32) and the adsorption tank (37) through the pipeline (36). The first outlet of the electromagnetic valve a (30) is connected to the intake pipe (1) through the pipeline (36). The second outlet of the electromagnetic valve a (30) is connected to the external air through the pipeline (36). The adsorption tank (37) and the reference tank (39) are placed in a water tank (35), and a water bath heater (40) is provided in the water tank (35).

4. The porous medium adsorption and diffusion dynamic self-test experimental system according to claim 3, wherein: The gas constant-temperature adsorption system further includes a constant-temperature water bath controller (34) for controlling the temperature of the water bath heater (40).

5. A method for self-testing the dynamic adsorption and diffusion of porous media using the experimental system according to any one of claims 1-4, characterized in that, It includes the following steps: S1: Open the three-way valve (9) to inject deionized water (7) into the water pipe (11). Adjust the heights of the manual lifting platform (12) and the automatic lifting platform (26) so that the liquid level height in the gas collection column (21) is flush with the exhaust pipe a (4), and the liquid level height in the water storage column (20) is flush with the liquid level height in the gas collection column (21). S2: Place the porous medium solid to be measured into the adsorption tank (37). Open the electromagnetic valve c (32) and the electromagnetic valve d (33), and use the vacuum pump (29) to evacuate the adsorption tank (37) and the reference tank (39) for 12 hours. S3: Close solenoid valve d(33), open solenoid valve b(31) to fill the reference tank (39) with helium at a pressure of p h1 , then close solenoid valve b(31), open solenoid valve d(33), and record the pressures p in the adsorption tank (37) and the reference tank (39) h2 ; S4: Open the electromagnetic valve c (32) and the electromagnetic valve d (33), and use the vacuum pump (29) to evacuate the adsorption tank (37) and the reference tank (39) for 2 hours. S5: Close solenoid valve d (33), open solenoid valve b (31) to fill the reference tank (39) with high-purity adsorption gas at pressure p c1 Then close solenoid valve b (31), open solenoid valve d (33), wait for 12 hours to reach adsorption equilibrium, and record the pressures p in the adsorption tank (37) and the reference tank (39) c2 ; S6: Open the second outlet of the electromagnetic valve a (30) to evacuate the free gas in the adsorption tank (37) and the reference tank (39) until the reading of the gas pressure sensor (38) is 0.1 MPa; then close the second outlet of the electromagnetic valve a (30) and open the first outlet of the electromagnetic valve a (30). S7: The gas diffuses from the intake pipe (1) into the gas collecting column (21). The differential pressure automatic leveling system makes the liquid levels of the water storage column (20) and the gas collecting column (21) flush. The volume change of the gas in the gas collecting column (21) is equal to the volume change of the deionized water (7) in the water storage column (20). Turn on the ultrasonic transmitter (18) and the DC power supply (16), and emit ultrasonic waves vertically downward at a fixed time interval. The ultrasonic waves are first reflected when they encounter the opaque oil (22), and are secondarily reflected when they encounter the metal plate (24) at the bottom of the water storage column (20). The ultrasonic transmitter (18) transmits the reflected signal into the computer (27) through the data transmission line (28) for recording and calculation; S8: Open the exhaust valve a (3) and raise the automatic lifting platform (26). Due to the differential pressure, the gas is discharged from the exhaust pipe a (4) and harmlessly treated until the initial liquid level state in step S1 is restored; S9: Replace other porous medium solids to be tested, and repeat steps S2 - S8 until the experimental work is completed.

6. The dynamic self-test experimental method for adsorption and diffusion in a porous medium according to claim 5, characterized in that: In step S7, the computer (27) calculates the gas adsorption amount Q of the porous medium under standard conditions ∞ , and the calculation formula is as follows: Among them, T0 and T a are the gas temperatures during the gas adsorption and desorption diffusion processes under standard conditions, respectively; p h1 is the helium pressure filled into the reference tank; P0 is the gas pressure under standard conditions; p h2 is the helium equilibrium pressure in the adsorption tank; p c1 is the adsorption gas pressure filled into the reference tank; p c2 is the equilibrium pressure of the adsorption gas in the adsorption tank; V c is the volume of the reference tank in the system.

7. The dynamic self-test experimental method for adsorption and diffusion of porous media according to claim 5, characterized in that: In step S7, the computer (27) calculates the volume ΔV of gas diffusion during the interval between two adjacent emissions of the ultrasonic transmitter (18). d , and the calculation formula is as follows: Among them, are the volumes of the liquid column at the first emission and the second emission during two adjacent ultrasonic emissions respectively; v w is the wave speed of ultrasonic waves in water; are the first reflection time and the second reflection time of the first emission during two adjacent ultrasonic emissions respectively; are the first reflection time and the second reflection time of the second emission during two adjacent ultrasonic emissions respectively; A is the cross-sectional area of the water storage column (20).

8. The dynamic self-test experimental method for adsorption and diffusion of porous media according to claim 5, characterized in that: The process of the differential pressure automatic leveling system making the liquid levels of the water storage column (20) and the gas collecting column (21) flush in step S7 is as follows: The gas diffuses from the intake pipe (1) into the gas collecting column (21), causing the liquid level in the water storage column (20) to rise and the liquid level in the gas collecting column (21) to drop. The light emitted by the emitter (5) passes through the deionized water (7) in the water storage column (20) and irradiates on the strip-shaped induction switch (23). The strip-shaped induction switch (23) is activated and controls the lifting switch (25) to adjust the height of the automatic lifting platform (26); until the liquid levels of the water storage column (20) and the gas collecting column (21) are flush, the opaque oil (22) blocks the light emitted by the emitter (5), the strip-shaped induction switch (23) is deactivated, and the automatic lifting platform (26) maintains the current height.

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