US-12618763-B2 - Experimental device and method for characterization of particle packing gradation

US12618763B2US 12618763 B2US12618763 B2US 12618763B2US-12618763-B2

Abstract

The present invention discloses an experimental device for characterization of particle packing gradation. The device is provided with a filling container with an upper opening, an air-permeable thin plate is arranged in the filling container, the air-permeable thin plate is densely covered with air-permeable round holes, the bottom of the filling container communicates with the top of a connecting pipe, the bottom of the connecting pipe is connected to one end of a U-shaped pipe, a marking line is provided on the pipe wall of the U-shaped pipe on the side of the connecting pipe, the connecting pipe is provided with a three-way pipe with a valve, and the three-way pipe with a valve is connected to a vacuum pump in a main machine through a bypass. The present invention further provides an experimental method for characterizing particle packing gradation.

Inventors

Yeqing SHEN
Chao Zhai
Mei MENG

Assignees

ANHUI NORMAL UNIVERSITY

Dates

Publication Date: 20260505
Application Date: 20230807
Priority Date: 20220815

Claims (9)

1 . An experimental method for characterizing particle packing gradation using an experimental device for characterization of particle packing gradation, comprising the following steps: Step 1. filling a first layer of fillers in a filling container; Step 2. controlling a three-way pipe with a valve to connect a vacuum pump to a U-shaped pipe, the U-shaped pipe having a first marking line, a second marking line, and a third marking line, and turning on the vacuum pump until a liquid level crosses the second marking line; Step 3. controlling the three-way pipe with the valve to connect the filling container to the U-shaped pipe, and starting timing when the liquid level drops to the second marking line; Step 4. stopping timing when the liquid level drops to the third marking line; Step 5. repeating steps 2-4 until reaching a preset number of repeated measurements, and taking an arithmetic mean as the final test result; and Step 6. repeating steps 1-5 for a second layer of the fillers with a different thickness until the number of filler layers reaches a designed number of layers of differing thicknesses; wherein: the device is provided with the filling container having an upper opening, an air-permeable thin plate is arranged in the filling container, the air-permeable thin plate is densely covered with air-permeable round holes, a bottom of the filling container communicates with a top of a connecting pipe, a bottom of the connecting pipe is connected to one end of the U-shaped pipe, the first, second, and third marking lines are provided on a pipe wall of the U-shaped pipe on the side of the connecting pipe, the connecting pipe is provided with the three-way pipe with the valve, and the three-way pipe with the valve is connected to the vacuum pump in a main machine through a bypass.
2 . The experimental method for characterizing particle packing gradation according to claim 1 , wherein: in the step 1, the thickness of each filler layer is 1.1-2.0 times the maximum particle size of the particles, the minimum thickness is 0.5 cm, each filler layer is compacted under a pressure of 1-20 MPa, and the total thickness of the fillers stacked layer-by-layer is 8-20 times the thickness of a single layer; in the step 5, the number of repeated measurements is 3-5, and if the error of each repeated measurement is 1-2 s, it is qualified, otherwise it is unqualified.
3 . The experimental method for characterizing particle packing gradation according to claim 1 , wherein: before the experiment, it is necessary to test the airtightness of the device, during the test, a liquid is injected into the U-shaped pipe, the upper opening of the filling container is sealed with a large rubber plug, the U-shaped pipe is connected to the connecting pipe with a rubber plug, the vacuum pump is connected to the U-shaped pipe by controlling the three-way pipe with a valve, the vacuum pump is turned on, the vacuum pump is turned off when the water level on one side of the U-shaped pipe crosses the first marking line, the U-shaped pipe is quickly connected to the upper-sealed filling container using the three-way pipe, and if there is no change in the liquid level for the set time, the airtightness of the device is qualified, and the characterization experiment of particle packing gradation can be carried out; the corresponding values of the packing thickness and air permeability time are obtained through the experimental method for characterizing particle packing gradation, so as to obtain the matching relationship between the specific value and the packing gradation index.
4 . The experimental method for characterizing particle packing gradation according to claim 1 , wherein: the filling container has a cylindrical or cuboid structure, the inner wall of the filling container is provided with a protruding platform for supporting an air-permeable thin plate, the air-permeable thin plate is placed on the platform, the distance between the air-permeable thin plate and the top of the connecting pipe is 1-2 cm, the thickness of the filling container wall and the thickness of the air-permeable thin plate are 0.5-1.5 cm, the thickness of the platform is 0.1-1.0 times the thickness of the filling container wall, the filling container above the air-permeable thin plate is provided with a depth scale on the inner wall, the minimum scale of the depth scale is 1 mm, the filling container is used for holding particles, the particle size of the particles is within the range of 0.01 μm-2 cm, the inner diameter of the filling container is 2-20 times the maximum particle size of the particles held in the filling container, the minimum inner diameter of the filling container is 2 cm, the height of the filling container above the air-permeable thin plate and the thickness of the filler layer are in a ratio of 1.0-1.5, the filling container and the connecting pipe are integrally cast and formed, and the area between the bottom of the platform of the filling container and the connecting pipe has a bucket-shaped structure with a large top and a small bottom.
5 . The experimental method for characterizing particle packing gradation according to claim 4 , wherein: the number of the air-permeable round holes on the air-permeable thin plate is 20-70 holes/cm 2 , the diameter of the air-permeable round holes is 0.1-0.5 mm, 1-3 layers of qualitative filter paper are placed on the air-permeable thin plate, and the device is provided with a bracket supporting the filling container.
6 . The experimental method for characterizing particle packing gradation according to claim 1 , wherein: the connecting part of the connecting pipe and the U-shaped pipe is provided with a rubber plug, the center of the rubber plug is provided with a through hole, the bottom of the connecting pipe is inserted into the through hole, the outer edge of the rubber plug is inserted into the U-shaped pipe, and the rubber plug provides the connecting part of the connecting pipe and the U-shaped pipe with airtightness.
7 . The experimental method for characterizing particle packing gradation according to claim 6 , wherein: the diameter of the U-shaped pipe is 3-50 times the maximum particle size of the particles, the height of the U-shaped pipe is 20-600 times the maximum particle size of the particles, three marking lines are provided, which are, from top to bottom, the first marking line, the second marking line, and the third marking line, wherein the first marking line is at a position 0.8-0.9 times the total height of the U-shaped pipe, the second marking line is at a position 0.7-0.8 times the total height of the U-shaped pipe, and the third marking line is at a position 0.5-0.7 times the total height of the U-shaped pipe.
8 . The experimental method for characterizing particle packing gradation according to claim 7 , wherein: the U-shaped pipe is filled with a liquid to a height 0.3-0.5 times the total height of the U-shaped pipe, and the liquid is deionized water or pure water.
9 . The experimental method for characterizing particle packing gradation according to claim 1 , wherein: a vacuum pump and a power supply are fixed inside the casing of the main machine, a screen for displaying time is provided on the surface of the casing, the power supply supplies power for the vacuum pump and the screen, a button area is provided on the surface of the casing, and buttons for controlling timing and running of the vacuum pump are arranged in the button area.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the priority of Chinese Patent Application No. 202210976423.1, filed with the China National Intellectual Property Administration on Aug. 15, 2022, and titled with “EXPERIMENTAL DEVICE AND METHOD FOR CHARACTERIZATION OF PARTICLE PACKING GRADATION”, which is hereby incorporated by reference in its entirety. FIELD The present invention relates to the technical field of experimental device, and in particular to an experimental device for characterization of particle packing gradation. BACKGROUND Particles are often used as raw materials in chemical, building materials and metallurgical industries. The final performance of the products converted from particles is closely related to particle packing. Particle packing gradation is an important factor for material engineering to obtain durability, compactness and other excellent performance. The regulation of particle packing and optimization of product performance both require the particle packing gradation. The current conventional equipment cannot directly test the particle packing gradation. In industrial practice and application, the particle size distribution of particles is usually determined using laser particle size analysis. Then the particle size composition is adjusted according to the Fuller curve, to achieve continuous distribution of particles as much as possible, so as to obtain theoretically graded particles. However, the graded particles are not necessarily densely packed according to the order of the gradation degree. The particle size of the particles obtained by the laser particle size method is a theoretical particle size, which much differs from the real shape and size of the particles. The graded particles formulated according to the Fuller curve are only a rough approximation of the theory. In addition, the formulation method of the particle gradation according to the Fuller curve cannot be applied to particles with a wide particle size range. The finer the capillary pores of the compacted particle packing structure and the more the number of the capillary pores, the longer the duration for a certain amount of air passing through. The duration for a certain amount of air passing through the packing pores of the compacted particles is closely related to the particle packing gradation. When the particles are packed up in the order of particle size, the formed packing pores are small and narrow, and the resistance to gas passage is large and the time taken is long. When the particles are packed up thicker and thicker in the order of particle size, the formed packing pores are smaller and narrower, and the resistance to gas passage is greater and the time taken is longer. SUMMARY The technical problem to be solved by the present invention is to provide a characterization method based on the actual particle packing gradation by utilizing the law of air passing through the particle packing structure, and its realization device. In order to achieve the above object, the technical solution adopted in the present invention provides an experimental device for characterization of particle packing gradation, wherein the device is provided with a filling container with an upper opening, an air-permeable thin plate is arranged in the filling container, the air-permeable thin plate is densely covered with air-permeable round holes, the bottom of the filling container communicates with the top of a connecting pipe, the bottom of the connecting pipe is connected to one end of a U-shaped pipe, a marking line is provided on the pipe wall of the U-shaped pipe on the side of the connecting pipe, the connecting pipe is provided with a three-way pipe with a valve, and the three-way pipe with a valve is connected to a vacuum pump in a main machine through a bypass. The filling container has a cylindrical or cuboid structure, the inner wall of the filling container is provided with a protruding platform for supporting an air-permeable thin plate, the air-permeable thin plate is placed on the platform, the distance between the air-permeable thin plate and the top of the connecting pipe is 1-2 cm, the thickness of the filling container wall and the thickness of the air-permeable thin plate are 0.5-1.5 cm, the thickness of the platform is 0.1-1.0 times the thickness of the filling container wall, the filling container above the air-permeable thin plate is provided with a depth scale on the inner wall, the minimum scale of the depth scale is 1 mm, the filling container is used for holding particles, the particle size of the particles is within the range of 0.01 mm-2 cm, the inner diameter of the filling container is 2-20 times the maximum particle size of the particles held in the filling container, the minimum inner diameter of the filling container is 2 cm, the height of the filling container above the air-permeable thin plate and the thickness of the filler layer are in a ratio of 1.0-1.5, the filling