CN105466834A - Compression ratio adjustable type porous media plane permeability measurement device and method - Google Patents

Abstract

A device and method for measuring the planar permeability of porous media with adjustable compressibility, including a measuring cylinder, a ball valve, a telescopic tube, an upper scale shaft, a lower scale shaft, a pressure plate, and a base; wherein, the lower surface of the pressure plate and the base The upper surface of the measuring platform is parallel to each other and gaskets are attached to each of them. The porous medium to be measured is placed between the gaskets. , the inner cavity of the telescopic tube and the inner pipe of the upper scale shaft constitute the channel for the measuring liquid to flow from the measuring cylinder to the measured porous medium on the lower side of the pressure plate; the upper scale shaft and the pressure plate compress the measured porous medium to the compressibility to be measured, and measure The liquid flows into the center of the measured porous medium under the action of gravity, and flows out from the radial edge after completely infiltrating the measured porous medium. Combining the change of the liquid level of the measuring cylinder, the measurement time and other data, the measured porous medium under the compressibility can be obtained Saturated permeability in the in-plane direction. The invention has the advantages of simple structure, convenient operation and high accuracy, and is used for measuring the plane permeability of porous media under different compression ratios.

Description

Device and method for measuring planar permeability of porous media with adjustable compressibility

technical field

The invention relates to the technical field of material performance testing, in particular to a measuring device and method for the plane permeability of porous media with adjustable compressibility, which is used for testing the permeability of porous media in the plane direction under different compressibility conditions.

Background technique

Porous media widely exist in nature and human production and life. At present, various types of porous media materials are increasingly used in various fields such as energy, materials, chemical industry, environmental science, biotechnology, bionics, medicine and agriculture. As an important basic characteristic of porous media, permeability is an important parameter to characterize the ability of fluid to pass through. Due to the complexity and diversity of porous media in terms of pore size and structure, the exact value of permeability usually depends on experimental measurement. In practical applications, porous media materials are often deformed in a state of compression, and the degree of deformation of porous media is generally expressed by compressibility, compressibility = compression amount of porous media sample thickness / original thickness of sample, its effect on permeability impact is very significant. Therefore, it is of great significance to construct an accurate and convenient test method and device for the permeability of porous media under different compressibility conditions for the in-depth research and optimal use of porous media.

The existing common methods and devices for measuring the permeability of porous media mainly have the following problems:

1. The method is too complicated, the volume of the device is too large, and the experiment is prone to errors;

2. Most of the measurement methods and devices are suitable for granular porous media, but not suitable for fibrous porous media or may cause large errors;

3. Most measurement methods and devices are suitable for thick and hard porous media, but not suitable for thin and soft porous media or will cause large errors;

4. It is impossible to accurately and continuously adjust the compressibility of the measured porous medium;

5. During the measurement process, the measuring liquid is not completely filled with the porous medium, resulting in inaccurate measured permeability results;

6. It can only be applied to the permeability within the specified range of the measuring device, and it cannot be measured or will cause large errors for the permeability within the range of different magnitudes;

7. Existing methods and devices are mainly aimed at measuring the permeability in the thickness direction of porous media, and there are few devices for testing the permeability in the direction of the plane;

Therefore, there is a need for an accurate and convenient measurement method and related device for the in-plane permeability of porous media with different thicknesses that are applicable to a wide range of permeability and can finely adjust the compressibility of porous media.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a measuring device and method for the planar permeability of porous media with adjustable compressibility, which can finely adjust the compressibility of the porous medium to be measured, so as to measure the permeability under the corresponding compressibility. The planar permeability achieves the effect of simple device structure, low cost and simple operation.

The present invention is achieved through the following technical solutions:

A measuring device for planar permeability of porous media with adjustable compressibility, characterized in that the measuring device includes a measuring cylinder, a ball valve, a telescopic tube, an upper scale shaft, a lower scale shaft, a pressure plate and a base;

The upper scale shaft is fixedly connected coaxially with a hollow pipe fitting and a tubular scale shaft. The hollow pipe fitting is provided with an axial inner pipe and the lower end and the upper part of the outer circumference are each provided with a section of external thread. The scale shaft The inner diameter is larger than the outer diameter of the hollow pipe, and it is connected to the external thread on the upper part of the hollow pipe. A sandwich lumen with a closed upper end is formed between the inner wall of the scale shaft and the external thread on the upper part of the hollow pipe. The outer wall of the scale shaft The lower end is provided with a circumferential scale mark;

The base is an upright arcuate member, the lower part is provided with a measuring platform, and the upper part is provided with a through hole;

The lower scale shaft is a tubular member, the lower end of which is fixedly connected to the upper part of the base, and the upper part extends into the interlayer lumen of the upper scale shaft. The inner tube wall of the lower scale shaft is provided with internal threads and The external thread connection of the upper part of the hollow pipe of the upper scale shaft, the hollow pipe of the upper scale shaft passes through the through hole of the upper part of the base, and the rotation of the upper scale shaft can be on the lower scale shaft through the rotation of the thread Moving up and down along the axial direction, the outer tube wall of the lower scale shaft is provided with a scale line along the axial direction;

The center of the pressure plate is provided with a threaded through hole and is connected to the external thread at the lower end of the upper scale shaft. The lower surface of the pressure plate is parallel to the upper surface of the measuring platform of the base, and each is pasted with a pad sheet, the porous medium to be measured is placed between the pads;

The measuring cylinder is a cylindrical container containing the measuring liquid, and the outer peripheral surface is provided with a scale line showing the change of the measuring liquid. The measuring cylinder is connected to the ball valve, the telescopic tube and the upper scale shaft in sequence, and the inner surface of the measuring cylinder is The cavity, the inner cavity of the ball valve, the inner cavity of the telescopic tube and the inner pipe of the upper scale shaft constitute the channel for the measuring liquid to flow from the measuring cylinder to the measured porous medium on the lower side of the pressure plate.

As a further improvement, the measuring cylinder and the ball valve, the ball valve and the telescopic tube, and the base and the lower scale shaft are all connected by threads respectively, and the telescopic tube and the upper scale shaft are connected by joints and clips. Hoop connection.

As a further improvement, the measuring cylinder and the pressure plate are made of transparent or translucent materials that are easy to observe.

As a further improvement, the gasket is made of transparent silicone rubber with little compression deformation.

As a further improvement, the upper part of the base is provided with a scale lock for locking the upper scale shaft.

As a further improvement, the measuring cylinder is fixed at a suitable height by a fixing frame.

As a further improvement, the upper scale shaft and the lower scale shaft are made of stainless steel.

As a further improvement, a measurement liquid contact plate is placed under the base, and the measurement liquid contact plate is a plastic box with a diameter larger than that of the base.

As a further improvement, the exhaust liquid and the measuring liquid are ethanol aqueous solution or glycerol aqueous solution.

Another technical solution of the present invention is:

A method for measuring the planar permeability of porous media realized by the above measuring device, comprising the following specific steps:

1. Preparation before measurement

1) Use degassed water to prepare exhaust liquid and measuring liquid;

2) cutting the measured porous medium, measuring and determining the original thickness of the measured porous medium;

3) Use alcohol or acetone solvent to clean the measuring cylinder, ball valve, telescopic tube, upper scale shaft, lower scale shaft, pressure plate, base, upper gasket and lower gasket, and assemble and install the compression tube after drying. Measuring device for the plane permeability of porous media with adjustable rate;

4) Place the measured porous medium between the upper gasket and the lower gasket, rotate and adjust the height of the upper scale shaft and the pressure plate, so that the upper gasket and the lower gasket are close to and compress the measured porous medium Medium, measure and obtain the test thickness of the measured porous medium, calculate and determine the test compressibility of the measured porous medium according to the following formula:

Test compressibility = thickness compression of the measured porous medium / original thickness,

Compression of the measured porous medium = original thickness - test thickness;

The thickness of the porous medium to be measured is obtained according to the following method:

Reading the scale value of the upper scale axis based on the scale reference line of the lower scale axis, and then reading the scale value of the lower scale axis based on the scale reference line of the upper scale axis, the upper scale The sum of the scale value of the axis and the scale value of the lower scale axis is the thickness of the measured porous medium;

2. Exhaust

Open the ball valve, pour the exhaust liquid into the measuring cylinder continuously, so that the exhaust liquid flows through the measuring cylinder, ball valve, telescopic tube and upper scale shaft in sequence, flows into the center of the porous medium to be measured, and then flows radially through the measured After measuring the radius range of the porous medium, it flows out. Observe that there are no bubbles left at the pressure plate and the side surface of the porous medium to be measured. It can be confirmed that the exhaust liquid has completely infiltrated the porous medium to be measured, and stop pouring the exhaust liquid;

3. Measure the data and calculate the permeability

1) by observing the scale line on the measuring cylinder, record the liquid level height of the measuring liquid in the measuring cylinder at the beginning and end of a certain measurement time;

2) Check the viscosity of the measuring liquid and the density of the measuring liquid according to the measuring liquid;

3) Calculate the plane permeability of the porous medium to be measured under the conditions of the test compressibility according to the following formula:

in,

K is the plane permeability of the measured porous medium,

a is the cross-sectional area of the inner cavity of the measuring cylinder,

R _sample is the radius of the measured porous medium,

The R _scale is the inner diameter of the inner pipe of the upper scale axis,

Δt is the measurement time,

_h1 is the liquid level height of the measuring liquid in the measuring cylinder at the beginning of the measuring time,

_h2 is the liquid level height of the measuring liquid in the measuring cylinder at the end of the measuring time,

μ is the viscosity of the measured liquid,

ρ is the measured liquid density,

g is the acceleration due to gravity,

H is the test thickness of the porous medium to be measured.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention has the advantages of simple structure, low cost, convenient operation, easy manufacture and maintenance, and is especially suitable for measuring the plane direction permeability of various types of porous media (including fibrous porous media and granular porous media) with high compressibility.

2. Adjust the height of the upper scale axis and the pressure plate to obtain porous media with different thicknesses, thereby changing the thickness parameters and compressibility of the porous media. During the measurement process, the compressibility of the measured porous media can be continuously and precisely adjusted, so that Obtain the dependence relationship between permeability and compressibility of porous media.

3. The upper and lower gaskets made of silicone rubber that fix the porous medium to be measured can be closely attached to the porous medium, effectively preventing side leakage of the measuring liquid in the thickness direction.

4. The pressure difference of the measured porous medium is characterized by the change of hydraulic momentum, which has high accuracy, is more convenient, and saves the test cost.

5. The exhaust liquid and measuring liquid adopt the special ratio of ethanol aqueous solution and glycerol aqueous solution obtained from experimental research to ensure the single-phase saturation of the measured porous medium, eliminate the interference of other fluids, and make the measurement results more accurate.

Description of drawings

Figure 1 is a schematic diagram of the device of the present invention.

Figure 2 is a schematic structural view of the upper scale shaft and the pressure plate.

Fig. 3 is a schematic diagram of the structure of the lower scale axis.

In the figure: 1 measuring cylinder, 2 ball valve, 3 telescopic tube, 4 upper scale shaft, 5 lower scale shaft, 6 base, 7 scale lock, 8 pressure plate, 9 tested porous medium, 10 upper gasket, 11 lower gasket , 12 external thread, 13 internal thread through hole, 14 scale shaft, 15 external thread, 16 hollow pipe, 17 external thread, 18 internal thread.

detailed description

The invention provides a measuring device and method for the planar permeability of porous media with adjustable compressibility, which is used to finely adjust the compressibility of porous media and measure the permeability under the corresponding compressibility, including the use of ethanol with a mass fraction of 40%. The aqueous solution infiltrates the porous medium to exhaust gas to ensure single-phase saturation; the measurement device accurately and continuously measures the permeability of the porous medium under different compressibility; device.

The structure of the present invention will be further elaborated below in conjunction with the accompanying drawings and specific examples, but the protection scope of the present invention cannot be limited by this.

Please refer to Figure 1, which shows that the measuring device for the planar permeability of porous media with adjustable compressibility includes a graduated cylinder 1, a ball valve 2, an expansion tube 3, an upper scale shaft 4, a lower scale shaft 5, a pressure plate 8, a scale lock 7 and a base Seat 6.

The base 6 is an upright arcuate member, the lower part is provided with a raised measuring platform, and the upper part is provided with a through hole.

Please refer to FIG. 2 , the upper scale axis 4 is formed by coaxially fixed connection of a hollow pipe member and a tubular scale axis 14 . The outer diameter of the hollow pipe fitting is 8 mm, the length is 135 mm, and an inner pipe 16 with an axial inner diameter of 6.5 mm is provided. A section of external thread 12 is provided at the lower end of the outer periphery of the hollow pipe fitting, and a section of external thread 15 is provided at the upper part of the outer periphery. . The inner diameter of the scale shaft 14 is 9mm, which is larger than the outer diameter of the hollow pipe. The scale shaft 14 is connected to the external thread 15 on the upper part of the hollow pipe, and the upper end is formed between the inner wall and the external thread 15 on the upper part of the hollow pipe. For a closed dissection lumen, the outer diameter of the scale shaft 14 is 10.25 mm, and the length is 51 mm.

Referring to Fig. 3, the lower scale axis 5 is a tubular member with an inner diameter of 8mm, an outer diameter of 18mm, and a length of 55mm, and its lower end is provided with an external thread 17 with a length of 5mm, a pitch of 0.5mm, and an outer diameter of 16mm. , so as to be fixedly connected with the upper part of the base 6 by screwing. The upper scale shaft 4 and the lower scale shaft 5 are threadedly engaged, and the upper part of the lower scale shaft 5 extends into the interlayer lumen of the upper scale shaft 4, and the inner tube wall of the lower scale shaft 5 is provided with The internal thread 18 is connected with the external thread 15 on the upper part of the hollow pipe of the upper scale 4, and the pitch is 0.5mm. The hollow tube of the upper scale shaft 4 passes through the through hole on the top of the base 6, the lower scale shaft 5 is fixed, and the upper scale shaft 4 can rotate axially on the lower scale shaft 5 through the screw thread. Move up and down for a spiral motion.

Please refer to Fig. 2, the center of the pressure plate 8 is provided with an internal thread through hole 13, which is connected with the external thread 12 at the lower end of the upper scale shaft 4, and the pitch is 0.5 mm. Please refer to Fig. 1, the lower surface of the pressure plate 8 is parallel to the upper surface of the measuring platform of the base 6 and each is attached with an upper gasket 10 and a lower gasket 11, the porous medium 9 to be measured It is placed horizontally between the upper pad 10 and the lower pad 11 .

The measured porous medium 9 is a cylinder with flat ends, and its diameter is determined according to the range of the measured permeability. The upper gasket 10 and the lower gasket 11 are low-compression-deformation silicon rubber discs, transparent and small in compression deformation, and their diameter is the same as the diameter of the measured porous medium 9, which can be tightly connected to the measured porous medium 9. In order to fix the upper and lower end surfaces of the measured porous medium 9 and prevent the measurement liquid from leaking sideways from the thickness direction of the measured porous medium 9 .

The pressure plate 8 is made of a transparent or translucent material that is easy to observe, such as plexiglass, which does not deform under pressure and can observe whether the measured porous medium 9 is saturated in a single phase. Both the diameter of the pressure plate 8 and the diameter of the measuring platform of the base 6 are the same as the diameter of the porous medium 9 to be measured.

Both the upper scale shaft 4 and the lower scale shaft 5 are made of stainless steel, which is corrosion-resistant. The lower end of the scale shaft 14 outer wall of the upper scale shaft 4 is provided with a circumferential scale line, which divides the circumference into 50 equal parts. The lower end edge of the scale shaft 14, that is, the lower end edge of the upper scale shaft 4 is the The scale reference line of the upper scale axis 4, along with the spiral movement of the upper scale axis 4, the circle scale line also rotates, because the pitch of the external thread 15 and the internal thread 18 is 0.5mm, so whenever the upper scale axis 4 rotates During one revolution, the pressure plate 8 advances or retreats by a pitch of 0.5 mm. The outer tube wall of the lower scale shaft 5 is provided with an axial scale line, see Fig. 1, a vertical line in the middle, that is, the scale reference line of the lower scale shaft 5, the left and right sides of this line Each has a row of scale lines with a spacing of 1 mm, and the left scale line is exactly in the middle of the two adjacent scale lines on the right. During measurement, read the scale value of the upper scale axis 4 based on the scale reference line of the lower scale axis 5, and then read the lower scale axis 5 based on the scale reference line of the upper scale axis 4 The scale value of , the sum of the scale value of the upper scale axis and the scale value of the lower scale axis is the thickness of the measured porous medium 9 .

Please refer to Fig. 1 , the scale lock 7 is placed on the upper part of the base 6, and locks and fixes the upper scale shaft 4 as required, so as to prevent the movement of the upper scale shaft 4 from causing measurement errors.

The measuring cylinder 1 is a cylindrical container containing the measuring liquid, and is fixed at a suitable height by a fixing frame. The measuring cylinder 1 is made of a transparent or translucent material, and the change of the measuring liquid level can be clearly seen from the outside. The outer peripheral surface of the measuring cylinder 1 is provided with scale lines showing the change of the remaining volume of the measuring liquid. The measuring cylinder 1 is sequentially connected with the ball valve 2, the telescopic tube 3 and the upper scale shaft 4 and is respectively sealed and fitted. The measuring cylinder 1 and the ball valve 2 and the ball valve 2 and the telescopic tube 3 are respectively connected by threads, wherein the outer diameter of the ball valve 2 is 16 mm, the inner diameter of the upper end is 12 mm, and the inner diameter of the lower end is 14 mm. Each is provided with a section of 5mm long internal thread of 0.5mm pitch, which is connected with the measuring cylinder 1 and the telescopic tube 3 respectively; the inner diameter of the measuring cylinder 1 is 50mm, the outer diameter is 54mm, and the length is 305mm. Interface, the outer diameter of this interface is 12mm, the inner diameter is 8mm, and the outer circumference is provided with the external thread that is connected with the upper end of the ball valve 2 with a pitch of 0.5mm; the telescopic tube 3 is a pipeline whose length can be adjusted, and its outer diameter is equal to the The inner diameter of the lower end of the ball valve 2 is 14 mm, and the upper end is provided with an external thread with a pitch of 0.5 mm connected to the ball valve 2. The inner diameter of the telescopic tube 3 is equal to the outer diameter of the upper scale shaft 4, which is 10 mm. It is connected with the upper scale shaft 4 through a special joint and a clamp.

The inner chamber of the measuring cylinder 1, the inner chamber of the ball valve 2, the inner chamber of the telescopic tube 3 and the inner pipe 16 of the upper scale shaft 4 constitute the measured liquid flowing from the measuring cylinder 1 to the lower side of the pressure plate 8. The channel of the porous medium enables the measuring liquid to flow accurately into the center of the porous medium 9 to be measured.

The measuring liquid adopts an aqueous solution with a mass fraction of ethanol of 40% or an aqueous solution with a mass fraction of glycerol of 80%, so as to ensure the single-phase flow of the measured porous medium 9 and exclude the interference of other fluids. During operation, the measuring liquid is stored in the measuring cylinder 1, accurately flows into the center of the porous medium 9 to be measured through the channel, and then flows out of the porous medium 9 in the radial direction through its radius. Before the measurement, the aqueous solution with ethanol mass fraction of 40% can also be used as exhaust liquid.

A measuring liquid contact plate is placed under the base 6, which is a circular plastic box with a diameter larger than that of the base 6, and the inner surface of the box is smooth and horizontal.

The basis that the present invention tests is Darcy's law derivation formula:

When the present invention works, the upper scale shaft and the pressure plate are used to fix the measured porous medium, and the measured porous medium is compressed to the compression rate to be measured, the measuring cylinder, the ball valve, the telescopic tube and the inner pipeline of the upper scale shaft constitute the flow of the measuring liquid. Then the measuring liquid will flow into the center of the measured porous medium accurately along the above-mentioned pipeline under the action of gravity, and flow out from the radial edge of the measured porous medium after completely infiltrating the measured porous medium, combined with the change of the liquid level on the measuring cylinder (h ₁ , h ₂ ), the measurement time (Δt) experienced in this process and other known data (μ, a, R _sample , R _scale , H, ρ, g) can get the measured porous Saturation permeability in the in-plane direction of the medium.

The present invention is tested based on the derivation of the plane radial seepage of Darcy's law:

The flow model in porous media usually adopts Darcy’s law. Darcy’s law mainly describes the flow behavior of Newtonian fluid in porous media, indicating that the volume flow rate (Q) of the measured liquid flowing through the side surface of the measured medium per unit time is related to the thickness of the measured medium ( H), the inner diameter of the pipeline in the upper scale axis (R _ruler ) is proportional to the pressure difference (ΔP) in the measured medium, and inversely proportional to the radius (R _sample ) and viscosity (μ) of the measured medium; the proportional coefficient K is defined as Permeability of the medium under test.

When the measuring device is in operation, the measured porous medium 9 under different thicknesses can be obtained by rotating and adjusting the height of the upper scale shaft 4 and the pressure plate 8, thereby changing the thickness parameter and compressibility of the measured porous medium 9, and obtaining the required measurement. Compressibility (compressibility=compression of the thickness of the porous medium 9 to be measured/the original thickness of the porous medium 9 to be measured), the measuring liquid will be under the action of gravity along the measuring cylinder 1, the ball valve 2, the telescopic tube 3 and the upper scale axis 4 The inner pipe 16 accurately flows into the center of the measured porous medium 9, and flows out from the radial side of the measured porous medium 9 after completely soaking the measured porous medium 9. The measured liquid volume flow rate (Q) and the measured liquid volume flow rate (Q) within a certain period of time (Δt) and the measured The pressure difference (ΔP) in the porous medium 9 is all related to the liquid level change (h ₁ , h ₂ ) in the measuring cylinder 1, the above relationship is substituted, and the basis derivation formula of the present invention is obtained by calculus:

Together with other known data of this process (μ, a, R _sample , R _scale , H, ρ, g), the in-plane direction permeability (K) of the measured porous medium 9 under the compressibility can be obtained.

During the permeability measurement process, the measuring liquid is ethanol aqueous solution or glycerin aqueous solution, and the above-mentioned gravity-driven water head pressurization method is adopted. The specific steps of the measurement method are as follows:

1. Preparation before measurement.

1) Prepare a sufficient amount of an aqueous solution with a mass fraction of ethanol of 40% and an aqueous solution with a mass fraction of glycerol of 80%, respectively. It should be noted that the water used in the preparation is degassed water.

2) Roughly determine the magnitude range of the permeability of the measured porous medium 9, thereby determine the measurement solution formula used in the measurement and the corresponding device structure scheme, the diameter of the upper gasket 10 and the lower gasket 11, according to the lower gasket The measured porous medium 9 is cut according to the size of the sheet 11, the thickness of the measured porous medium 9 is measured several times, and the average value of the multiple results is taken as the original thickness.

3) Use an aqueous solution with a mass fraction of 40% ethanol or acetone and other solvents to put the measuring cylinder 1, the ball valve 2, the telescopic tube 3, the upper scale shaft 4, the pressure plate 8, the base 6, the scale lock 7, the upper gasket 10 and the lower pad Rinse off the surface of sheet 11 and the oily substances on the inner pipeline, dry them, connect the components according to the structure shown in Figure 1, seal the joints, assemble and install the porous medium with adjustable compressibility measuring device.

4) Fix the upper gasket 10 and the lower gasket 11 on the pressure plate 8 and the base 6 respectively, then place the measured porous medium 9 between the two gaskets; rotate and adjust the upper scale shaft 4 and the pressure plate The height of the disc 8 makes the upper gasket 10 and the lower gasket 11 close to the porous medium 9 to be measured, and determines the test thickness of the porous medium 9 to be measured, thereby determining the thickness of the porous medium 9 to be measured. Test the compressibility (compressibility=compression of the measured thickness of the porous medium 9/measured original thickness of the porous medium 9).

2. Exhaust

Open the ball valve 2, pour a sufficient amount of aqueous solution with a mass fraction of 40% ethanol as the exhaust liquid, so that the exhaust liquid flows through the measuring cylinder 1, the ball valve 2, the telescopic tube 3, and the inner pipe 16 of the upper scale shaft 4 in sequence, and accurately flows into the Within the range of 6.5 mm in diameter of the measured center point of the porous medium 9, flow out after flowing radially through the medium radius range in the measured porous medium 9; continue to pour the measuring liquid until the seepage liquid has completely soaked the After measuring the porous medium 9 (it can be judged from the transparent pressure plate 8 and the outlet of the medium side surface without air bubbles), stop pouring the exhaust liquid; then pour degassed water, rinse the pipeline for a period of time, and close the ball valve 2.

3. Measure the data and calculate the permeability.

1) The volume flow rate (Q) of the measuring liquid flowing through the side surface of the measured porous medium 9 within a certain measurement time (Δt) can be calculated by multiplying the liquid level change (h ₁ , h ₂ ) in the measuring cylinder 1 by the area of the inner tube of the measuring cylinder 1 ( a) Divided by the measurement time (Δt).

2) The inner tube area (a) of the measuring cylinder 1 can be obtained by multiplying the square of the inner diameter of the measuring cylinder 1 by π.

3) The inner diameter (R _scale ) of the inner pipe 16 of the upper scale axis 4 is 3.25 mm, and the radius (R _sample ) of the measured porous medium 9 is 25 mm.

4) The test thickness (H) of the porous medium 9 to be measured can be obtained by adding the scale values of the upper and lower scale axes, and the reading method is as follows: read the upper scale axis 4 based on the scale reference line of the lower scale axis 5 Then read the scale value of the lower scale axis 5 based on the scale reference line of the upper scale axis 4, the sum of the scale value of the upper scale axis and the scale value of the lower scale axis is the sum Measure the test thickness (H) of the porous media.

5) According to literature review, the viscosity of the measured liquid (μ), the density of the measured liquid (ρ), and the acceleration of gravity (g) are all known.

6) Substituting the numerical values of the above physical quantities into the derivation formula of the plane radial seepage of Darcy's law:

The plane permeability (K) of the measured porous medium 9 under the test compression rate can be obtained.

In the formula,

K is the plane permeability of the measured porous medium,

a is the cross-sectional area of the inner cavity of the measuring cylinder,

R _sample is the radius of the measured porous medium,

The R _scale is the inner diameter of the inner pipe of the upper scale axis,

Δt is the measurement time,

_h1 is the liquid level height of the measuring liquid in the measuring cylinder at the beginning of the measuring time,

_h2 is the liquid level height of the measuring liquid in the measuring cylinder at the end of the measuring time,

μ is the viscosity of the measured liquid,

ρ is the measured liquid density,

g is the acceleration due to gravity,

H is the test thickness of the porous medium to be measured.

In the above steps, for the measured porous medium 9 in the range of low permeability, an aqueous solution with a mass fraction of ethanol of 40% can be used as the measurement liquid, and the method of changing the sample diameter, the inner diameter of the flow tube and the inner diameter of the graduated cylinder at the same time can be Adjust so that the device is suitable for the permeability range; for the measured porous medium 9 in the middle permeability range, an aqueous solution of 40% ethanol mass fraction can be used as the measuring liquid; for the measured high permeability range The porous medium 9 may use an aqueous solution with a mass fraction of glycerol of 80% as the measuring liquid.

Application example:

The GFD-4.6 graphite felt of SGL Company was used to measure the permeability of the measuring device of the present invention. The actual test sample is a disc-shaped carbon felt with a thickness of 4.6mm and a diameter of 50mm. The measuring solution is an aqueous solution with a mass fraction of 40% ethanol at a temperature of 20°C. The density of the aqueous ethanol solution is 0.935g·cm ³ and the viscosity is 2.91mPa· s. As listed in the table below, take several different typical compressibility listed in the table below (the thickness and difference in the table are just for the convenience of comparison), and then measure the permeability. The test results prove that the thickness can be obtained under various compression ratios, and the compression ratio can be adjusted freely from 0 to 57%. Measure three times under each compression ratio, take the average value, and obtain the test results as follows:

Numbering Sample original thickness mm Sample test thickness mm Compression ratio% Permeability Darcy 1 4.6 4.5 2 90 2 4.6 4 13 65 3 4.6 3.5 twenty four 46 4 4.6 3 35 39 5 4.6 2.5 46 35 6 4.6 2 57 20

The test results are in good agreement with the permeability parameters of GFD-4.6 graphite felt provided by SGL. Therefore, the measuring method and device of the present invention can accurately measure the planar permeability of porous media under different compressibility.

It should be understood that for those skilled in the art, equivalent or equivalent improvements or changes can be made to the above content, and all these improvements and changes should fall within the scope of protection required by the present invention.

Claims (10)

1. A measuring device for the plane permeability of porous media with adjustable compressibility, characterized in that: the measuring device includes a measuring cylinder, a ball valve, a telescopic tube, an upper scale shaft, a lower scale shaft, a pressure plate and a base; The upper scale shaft is fixedly connected coaxially with a hollow pipe fitting and a tubular scale shaft. The hollow pipe fitting is provided with an axial inner pipe and the lower end and the upper part of the outer circumference are each provided with a section of external thread. The scale shaft The inner diameter is larger than the outer diameter of the hollow pipe, and it is connected to the external thread on the upper part of the hollow pipe. A sandwich lumen with a closed upper end is formed between the inner wall of the scale shaft and the external thread on the upper part of the hollow pipe. The outer wall of the scale shaft The lower end is provided with a circumferential scale mark; The base is an upright arcuate member, the lower part is provided with a measuring platform, and the upper part is provided with a through hole; The lower scale shaft is a tubular member, the lower end of which is fixedly connected to the upper part of the base, and the upper part extends into the interlayer lumen of the upper scale shaft. The inner tube wall of the lower scale shaft is provided with internal threads and The external thread connection of the upper part of the hollow pipe of the upper scale shaft, the hollow pipe of the upper scale shaft passes through the through hole of the upper part of the base, and the rotation of the upper scale shaft can be on the lower scale shaft through the rotation of the thread Moving up and down along the axial direction, the outer tube wall of the lower scale shaft is provided with a scale line along the axial direction; The center of the pressure plate is provided with a threaded through hole and is connected to the external thread at the lower end of the upper scale shaft. The lower surface of the pressure plate is parallel to the upper surface of the measuring platform of the base, and each is pasted with a pad sheet, the porous medium to be measured is placed between the pads; The measuring cylinder is a cylindrical container containing the measuring liquid, and the outer peripheral surface is provided with a scale line showing the change of the measuring liquid. The measuring cylinder is connected to the ball valve, the telescopic tube and the upper scale shaft in sequence, and the inner surface of the measuring cylinder is The cavity, the inner cavity of the ball valve, the inner cavity of the telescopic tube and the inner pipe of the upper scale shaft constitute the channel for the measuring liquid to flow from the measuring cylinder to the measured porous medium on the lower side of the pressure plate. 2. The measuring device for planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: between the graduated cylinder and the ball valve, between the ball valve and the telescopic tube, and between the base and the lower scale The shafts are respectively connected by threads, and the telescopic tube and the upper scale shaft are connected by joints and hoops. 3. The device for measuring planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: the measuring cylinder and the pressure plate are made of transparent or translucent materials that are easy to observe. 4. The device for measuring planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: said gasket is made of transparent silicone rubber with little compression deformation. 5. The measuring device for planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: the upper part of the base is provided with a scale lock for locking the upper scale axis. 6 . The device for measuring planar permeability of porous media with adjustable compressibility according to claim 1 , wherein the measuring cylinder is fixed at a suitable height by a fixing frame. 6 . 7. The device for measuring planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: the upper scale axis and the lower scale axis are made of stainless steel. 8. The measuring device for planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: a measuring liquid contact plate is placed under the base, and the measuring liquid contact plate is a plastic box with a diameter larger than the The diameter of the base described above. 9. The device for measuring planar permeability of porous media with adjustable compressibility according to claim 1, characterized in that: said exhaust liquid and measuring liquid are ethanol aqueous solution or glycerol aqueous solution. 10. A method for measuring the porous medium plane permeability realized by the measuring device according to claim 1, characterized in that: the method comprises the following specific steps: 1. Preparation before measurement 1) Use degassed water to prepare exhaust liquid and measuring liquid; 2) cutting the measured porous medium, measuring and determining the original thickness of the measured porous medium; 3) Use alcohol or acetone solvent to clean the measuring cylinder, ball valve, telescopic tube, upper scale shaft, lower scale shaft, pressure plate, base, upper gasket and lower gasket, and assemble and install the compression tube after drying. Measuring device for the plane permeability of porous media with adjustable rate; 4) Place the measured porous medium between the upper gasket and the lower gasket, rotate and adjust the height of the upper scale shaft and the pressure plate, so that the upper gasket and the lower gasket are close to and compress the measured porous medium Medium, measure and obtain the test thickness of the measured porous medium, calculate and determine the test compressibility of the measured porous medium according to the following formula: Test compressibility = thickness compression of the measured porous medium / original thickness, Compression of the measured porous medium = original thickness - test thickness; The thickness of the porous medium to be measured is obtained according to the following method: Reading the scale value of the upper scale axis based on the scale reference line of the lower scale axis, and then reading the scale value of the lower scale axis based on the scale reference line of the upper scale axis, the upper scale The sum of the scale value of the axis and the scale value of the lower scale axis is the thickness of the measured porous medium; 2. Exhaust Open the ball valve, pour the exhaust liquid into the measuring cylinder continuously, so that the exhaust liquid flows through the measuring cylinder, ball valve, telescopic tube and upper scale shaft in sequence, flows into the center of the porous medium to be measured, and then flows radially through the measured After measuring the radius range of the porous medium, it flows out. Observe that there are no bubbles left at the pressure plate and the side surface of the porous medium to be measured. It can be confirmed that the exhaust liquid has completely infiltrated the porous medium to be measured, and stop pouring the exhaust liquid; 3. Measure the data and calculate the permeability 1) by observing the scale line on the measuring cylinder, record the liquid level height of the measuring liquid in the measuring cylinder at the beginning and end of a certain measurement time; 2) Check the viscosity of the measuring liquid and the density of the measuring liquid according to the measuring liquid; 3) Calculate the plane permeability of the porous medium to be measured under the conditions of the test compressibility according to the following formula: in, K is the plane permeability of the measured porous medium, a is the cross-sectional area of the inner cavity of the measuring cylinder, R _sample is the radius of the measured porous medium, The R _scale is the inner diameter of the inner pipe of the upper scale axis, Δt is the measurement time, _h1 is the liquid level height of the measuring liquid in the measuring cylinder at the beginning of the measuring time, _h2 is the liquid level height of the measuring liquid in the measuring cylinder at the end of the measuring time, μ is the viscosity of the measured liquid, ρ is the measured liquid density, g is the acceleration due to gravity, H is the test thickness of the porous medium to be measured.