A porous medium diffusion coefficient measuring device under gas-liquid two-way convection conditions

Abstract

The application discloses a porous medium diffusion coefficient measuring device under gas-liquid two-way convection conditions and belongs to the technical field of measurement. The device comprises a porous medium test sample, a sealing frame, an upper pressing plate, a lower pressing plate, a sealing ring, a gas source, a gas treatment device, a liquid storage cavity, a liquid pumping device, a gas flow control meter, a gas pressure sensor, a gas concentration sensor, a liquid pressure sensor and a liquid phase proportion measuring device. The device realizes gas phase collection and measurement by using controllable gas phase and liquid phase counterflow and gas dissolution, so that the diffusion capacity of the porous medium to gas-liquid two-phase materials can be quantitatively evaluated.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to a device for measuring the diffusion coefficient of porous media under two-way gas-liquid convection conditions. Background Technology

[0002] Porous media are widely used in various catalytic and separation systems in the chemical industry. The diffusion properties of the pores within porous media play a crucial role in regulating apparent chemical reaction rates and improving the transport capacity of reactants and products. In the regulation of most chemical reactions, mass transfer processes in porous media face the challenge of simultaneous gas-liquid two-phase transport, and the diffusion coefficient during bidirectional gas-liquid convection is difficult to measure accurately. Therefore, developing a device for measuring the diffusion coefficient of porous media under conditions of simultaneous gas-liquid bidirectional convection is of significant importance and practical value.

[0003] A comparison with existing technologies reveals that current devices for measuring the diffusion coefficient of porous media only test mass transfer processes under single-substance, unidirectional transport conditions, while devices capable of simultaneously measuring the diffusion coefficient under gas-liquid convection conditions are rare. CN 114486635A discloses a method and system for measuring the molecular diffusion coefficient within porous materials, but this device can only measure the diffusion coefficient of liquid-phase probe molecules within the porous material. CN 107314950A discloses a method for determining the diffusion coefficient of carbon dioxide in porous media, but this method primarily detects changes in carbon dioxide concentration using nuclear magnetic resonance and cannot be applied to other media. CN 113984587A discloses an in-situ method for measuring the CO2-water diffusion coefficient within porous media, but this method primarily tests the diffusion process of CO2 in water under conditions where the porous medium is filled with water, without considering the bidirectional gas-liquid convection scenario. Summary of the Invention

[0004] To address the shortcomings and gaps in existing technologies regarding the aforementioned issues, this invention proposes a porous media diffusion coefficient measuring device under gas-liquid bidirectional convection conditions. By controlling the gas-liquid phase reversal, gas phase collection and measurement are achieved through gas dissolution, thereby quantitatively evaluating the diffusion capacity of porous media for gas-liquid two-phase substances.

[0005] The specific technical solution of this invention is as follows:

[0006] A device for measuring the diffusion coefficient of porous media under bidirectional gas-liquid convection conditions, specifically including a porous media test sample, a sealing frame, an upper pressure plate, a lower pressure plate, a sealing ring, a gas source, a gas processing device, a liquid storage chamber, a liquid pumping device, a gas flow controller, a gas pressure sensor, a gas concentration sensor, a liquid pressure sensor, and a liquid phase ratio measuring device, etc.

[0007] The porous media test sample is surrounded by a leak-proof sealing frame. The porous media test sample and the sealing frame are located between the upper and lower pressure plates. The upper and lower pressure plates are connected by an adjustable-distance fastening system. Corresponding positions on the sealing frames of the upper and lower pressure plates are provided with sealing ring grooves, and leak-proof sealing rings are installed inside the grooves. The upper pressure plate has an air inlet and an air outlet. The air inlet is connected to the gas source, and the air outlet is connected to a gas processing device. A liquid storage chamber is installed below the lower pressure plate and is connected to a liquid pumping device. The gas source provides soluble gas at a certain pressure. A gas flow controller and a gas pressure sensor are sequentially installed between the gas source and the air inlet of the upper pressure plate. The gas processing device includes a liquid drying and collection device and a gas harmless treatment device connected in sequence. The liquid storage chamber is equipped with a gas concentration sensor for measuring the gas content diffused from the porous medium into the liquid in the chamber and a liquid pressure sensor for measuring liquid pressure fluctuations. The side of the porous medium test sample is equipped with a liquid phase ratio measuring device that can measure the proportion of liquid content inside the porous medium in real time.

[0008] Furthermore, the liquid phase ratio measuring device can emit X-rays and collect the attenuated X-rays that penetrate the porous medium test sample on the opposite side. Based on the attenuation of the X-rays, the volume and ratio of the liquid phase inside the porous medium test sample can be calculated and reconstructed.

[0009] Furthermore, a gas indicator for tracing is added to the sealed frame to detect whether leakage occurs at the frame.

[0010] Furthermore, the soluble gas provided by the gas source has a suitable solubility with the liquid inside the storage chamber, and the solubility of the gas in the liquid ranges from 1 to 50.

[0011] Furthermore, a flow channel for gas guidance and droplet purging is provided in the contact area between the upper pressure plate and the porous medium test sample. The gas distribution is achieved through the flow guidance area to ensure that the gas pressure and flow velocity inside the flow channel are uniformly distributed.

[0012] Furthermore, the upper pressure plate is made of a transparent material, and the surface of the material is coated with a superhydrophobic coating to enhance the gas's ability to purge droplets.

[0013] Furthermore, the lower pressure plate is provided with a porous support layer for filtration and support. The porous support layer has high rigidity and a suitable pore size range, with an elastic modulus of not less than 200MPa and a pore size range of 10μm to 500μm.

[0014] Furthermore, the liquid pumping device can provide stable micro-flow control and output, with a flow control range of 10 μL / min to 20 mL / min.

[0015] Furthermore, a liquid pressure buffer is connected to the side of the liquid storage chamber. When the instrument is working, a certain volume of sparingly soluble gas is stored in the pressure buffer to slow down drastic changes in liquid pressure and facilitate liquid pressure control. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the overall shape and connection relationship of a porous medium diffusion coefficient measuring device under two-way gas-liquid convection conditions.

[0017] In the diagram, 6-gas source, 7-gas processing device, 9-liquid pumping device, 10-gas flow controller, 11-gas pressure sensor, and 14-liquid phase ratio measuring device.

[0018] Figure 2 This is a cross-sectional view of the internal structure of the device.

[0019] In the figure, 1-porous medium test sample, 2-sealing frame, 3-upper pressure plate, 4-lower pressure plate, 5-sealing ring, 8-liquid storage chamber, 12-gas concentration sensor, 13-liquid pressure sensor, 301-flow channel, 302-flow guide area, 401-porous support layer, 801-pressure buffer zone, 802-poorly soluble gas.

[0020] Figure 3 This is a schematic diagram of a gas processing device.

[0021] In the figure, 701 is a liquid drying and collection device, and 702 is a gas harmless treatment device. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and specific examples. These examples will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0023] Example

[0024] A device for measuring the diffusion coefficient of porous media under bidirectional gas-liquid convection conditions, specifically including a porous media test sample, a sealing frame, an upper pressure plate, a lower pressure plate, a sealing ring, a gas source, a gas processing device, a liquid storage chamber, a liquid pumping device, a gas flow controller, a gas pressure sensor, a gas concentration sensor, a liquid pressure sensor, and a liquid phase ratio measuring device, etc.

[0025] The porous media test sample (1) is connected to the surrounding sealing frame (2) by adhesive or other means to prevent leakage of gaseous or liquid substances through the frame. The porous media test sample and the sealing frame are clamped between the upper pressure plate (3) and the lower pressure plate (4) by bolts or other fastening methods. The distance between the upper and lower pressure plates can be adjusted by the thickness of the gasket or springs. O-ring grooves are provided at the corresponding positions of the sealing frame on the upper and lower pressure plates to place O-rings (5) to prevent leakage of gaseous and liquid substances to the outside.

[0026] The upper pressure plate is provided with an air inlet and an air outlet. The air inlet is connected to the air source (6), and the air outlet is connected to the gas processing device (7). At the same time, a gas flow controller (10) and a gas pressure sensor (11) are connected to the air inlet and outlet to regulate the gas flow and measure the gas pressure in real time.

[0027] The gas supplied by the gas source needs to have a suitable solubility with the liquid used. This allows for the resolution of the problem of difficult collection and measurement after traditional two-way gas convection by utilizing the gas's dissolution process in the liquid. It also helps to better simulate the actual working conditions in chemical reactions. The solubility of the gas in the liquid should be within the range of 1-50. Too low a solubility will make it difficult for the gas to be completely absorbed by the liquid, resulting in a gas cavity in the liquid storage chamber, affecting the liquid transfer process and the measurement of gas transfer volume. On the other hand, too high a solubility will cause the gas to dissolve completely in a short time, resulting in a momentary negative pressure in the gas cavity at the upper pressure plate, producing a "fountain" effect, which will affect the normal liquid transfer process.

[0028] The gas processing device (7) includes a liquid drying and collection device (701) and a gas detoxification device (702) connected in sequence. The main purpose of drying and collection is to obtain the real-time transfer volume of liquid through the porous medium through real-time quality detection. At the same time, gas drying is also beneficial for further gas processing. Since most easily soluble gases are often toxic and dangerous, the gases cannot be directly discharged into the air, but need to pass through a detoxification device. The main treatment methods are complete absorption through chemical reagent reaction or discharge after being converted into a detoxification gas.

[0029] A liquid storage chamber (8) is installed below the pressure plate. The liquid storage chamber is connected to a liquid pumping device (9). The flow control range of the pump should meet the usage requirements and be as accurate as possible. The recommended adjustment range is 10 μL / min to 20 mL / min. A gas concentration sensor (12) for measuring the gas content diffused from the porous medium into the liquid in the chamber and a liquid pressure sensor (13) for measuring liquid pressure fluctuations are installed in the liquid storage chamber. The gas concentration sensor needs to be selected according to the type of gas used. Most gases will ionize after dissolving in liquid. Therefore, the gas concentration can be measured by conductivity measurement or pH value measurement.

[0030] To detect the proportion of gas and liquid phases within the pores of a porous medium, a liquid phase proportion measuring device (14) is provided on the side of the test sample to measure the liquid content within the porous medium in real time. Preferably, the measurement can be performed by X-ray transmission. Since X-rays attenuate at different rates after penetrating different substances, the distribution and proportion of gas and liquid phases within the porous medium can be reconstructed by calculating and analyzing the X-ray intensity after penetrating the sample.

[0031] Meanwhile, the liquid storage chamber is connected to a liquid pressure buffer zone (801). In addition to the liquid portion, the buffer zone also contains a region (802) filled with sparingly soluble gas. The main purpose of retaining this portion of liquid is to buffer the liquid pressure fluctuations when the liquid is pumped into the storage chamber through the volume compression of the gas, thereby avoiding a sharp pressure rise in a short period of time and helping to accurately control the liquid pressure.

[0032] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A device for measuring the diffusion coefficient of porous media under gas-liquid bidirectional convection conditions, characterized in that: The test sample includes a porous medium test sample (1), a sealing frame (2), an upper pressure plate (3), a lower pressure plate (4), a sealing ring (5), a gas source (6), a gas processing device (7), a liquid storage chamber (8), a liquid pumping device (9), a gas flow controller (10), a gas pressure sensor (11), a gas concentration sensor (12), and a liquid pressure sensor (13). The porous media test sample (1) is surrounded by a sealing frame (2) to prevent leakage. The porous media test sample (1) and the sealing frame (2) are located between the upper pressure plate (3) and the lower pressure plate (4). The upper pressure plate (3) and the lower pressure plate (4) are connected by a fastening connection with adjustable distance. The sealing frame on the upper pressure plate (3) and the lower pressure plate (4) are provided with sealing ring grooves at corresponding positions. A sealing ring (5) to prevent leakage is installed inside the groove. The upper pressure plate (3) is provided with an air inlet and an air outlet. The air inlet is connected to the air source (6), and the air outlet is connected to the gas processing device (7). A liquid storage chamber (8) is installed below the lower pressure plate (4) and the porous media test sample (1). The liquid storage chamber stores the liquid to be tested. The liquid storage chamber (8) is connected to the liquid pumping device (9). The gas source (6) provides soluble gas at a certain pressure. A gas flow controller (10) and a gas pressure sensor (11) are sequentially provided between the gas source (6) and the air inlet of the upper pressure plate (3). The gas processing device (7) includes a liquid drying and collecting device (701) and a gas harmless treatment device (702) connected in sequence. The liquid storage chamber (8) is equipped with a gas concentration sensor (12) for measuring the gas content diffused from the porous medium into the liquid in the chamber and a liquid pressure sensor (13) for measuring liquid pressure fluctuations.

2. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: It also includes a liquid phase ratio measuring device (14), which is disposed on the side of the porous medium test sample (1). The liquid phase ratio measuring device (14) can realize CT imaging. By emitting X-rays and collecting the attenuated X-rays that penetrate the porous medium test sample (1) on the opposite side, the liquid phase volume and ratio inside the porous medium test sample (1) can be calculated and reconstructed according to the X-ray attenuation.

3. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: A gas indicator for tracing is added to the sealed frame (2) to detect whether leakage occurs at the frame.

4. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: The soluble gas provided by the gas source (6) has a suitable solubility with the liquid inside the storage chamber (8), and the solubility of the gas in the liquid is in the range of 1~50.

5. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: The upper pressure plate (3) is provided with a flow channel (301) for gas guidance and droplet purging within the contact area between it and the porous medium test sample (1). The flow channel (302) is used to achieve appropriate gas distribution so as to ensure that the gas pressure and flow velocity inside the flow channel are uniformly distributed.

6. The porous media diffusion coefficient measuring device according to claim 1 or claim 5, characterized in that: The upper pressure plate (3) is made of a transparent material, and the surface of the material is coated with a superhydrophobic coating to enhance the gas’s ability to purge droplets.

7. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: It also includes a porous support layer (401) for filtration and support, the porous support layer being located between the upper pressure plate (3) and the lower pressure plate (4), the porous support layer having greater rigidity and a suitable pore size range, an elastic modulus of not less than 200MPa, and a pore size range of 10μm~500μm.

8. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: The liquid pumping device (9) can provide stable micro-flow control and output, with a flow control range of 10μL / min to 20mL / min.

9. The porous media diffusion coefficient measuring device according to claim 1, characterized in that: The liquid storage chamber (8) is connected to a liquid pressure buffer zone (801) on its side. When the instrument is working, a certain volume of sparingly soluble gas (802) is stored in the liquid pressure buffer zone (801) to reduce drastic changes in liquid pressure and facilitate liquid pressure control.

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