Irregular urea particle surface area measuring device based on air pressure measuring method

Abstract

The utility model relates to the field of urea particle surface measurement, in particular to an irregular urea particle surface area measuring device based on an air pressure measuring method. The irregular urea particle surface area measuring device based on the air pressure measuring method comprises a BET machine, a telescopic pipe and a limiting structure, a connecting plate is arranged at the bottom of the BET machine, square rods are fixedly connected to the two ends of the connecting plate, the two square rods are slidably connected with the two sides of the BET machine, the telescopic pipe is installed between the BET machine and the connecting plate, the middle of the connecting plate is designed to be hollow, and the limiting structure is arranged in the middle of the BET machine. A liquid nitrogen tank is placed on the BET machine, the inner diameter of the connecting plate is smaller than the outer diameter of the liquid nitrogen tank, and a limiting structure is installed between the BET machine and the connecting plate. According to the utility model, the telescopic tube is designed to automatically cover the sample test tube when the connecting plate descends, so that the test tube after liquid nitrogen treatment is effectively prevented from being directly exposed outside. The protection measure obviously reduces the frostbite risk caused by mistakenly touching the low-temperature test tube by detection personnel, and improves the safety of experiment operation.

Description

Technical Field

[0001] The utility model relates to the field of urea particle surface measurement, in particular to a device for measuring the surface area of ​​irregular urea particles based on an air pressure measurement method. Background Art

[0002] In the slow-release fertilizer industry, urea slow-release fertilizer is widely used in modern agriculture to improve fertilizer utilization due to its low solubility in water and ability to slowly release nitrogen in the soil. However, the shape, roundness, and smoothness of urea granules have a significant impact on the preparation process and economic efficiency of coated slow-release fertilizers. In particular, when urea granules are irregular in shape, their surface area increases significantly, which directly affects the amount of coating agent used and the coating effect.

[0003] Currently, the shape of urea granules is mainly evaluated through particle size analysis based on national standards. However, this method cannot objectively reflect the roundness and smoothness of the granules, especially irregularities such as angular shapes. In order to more accurately evaluate the surface area characteristics of urea granules, a more precise measurement method is needed.

[0004] The Brunauer-Emmett-Teller (BET) method, a classic gas adsorption method, is widely used to determine the specific surface area, average pore size, and pore size distribution of catalysts. Its principle is based on the reversible physical adsorption of gas molecules on solid surfaces. By measuring the amount of gas adsorbed on the adsorbent surface at equilibrium under a certain pressure, the specific surface area of ​​the sample is calculated using a theoretical model. However, existing BET instruments are primarily designed for nanoscale porous catalysts, such as gas shift catalysts, desulfurization agents, and pressure swing adsorption adsorbents. Surface area measurements of large, millimeter-sized particles, such as urea granules, have not been widely used.

[0005] In addition, during operation, existing BET machines usually require the use of liquid nitrogen tanks to provide an ultra-low temperature environment so that the required adsorption temperature can be reached during the nitrogen adsorption process. However, this design means that the test tubes containing samples are directly exposed to the outside after liquid nitrogen treatment, lacking the necessary protective devices. Since the temperature of the test tubes after liquid nitrogen treatment is extremely low, direct exposure to the outside can easily cause testers to accidentally touch them and cause frostbite, posing a serious safety hazard.

[0006] Therefore, it is necessary to provide a new device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement to solve the above technical problems. Utility Model Content

[0007] In order to solve the above technical problems, the utility model provides a device for measuring the surface area of ​​irregular urea particles based on the air pressure measurement method.

[0008] The utility model provides a surface area measuring device for irregular urea particles based on a barometric pressure measurement method, comprising: a BET machine, a telescopic tube and a limiting structure. A connecting plate is provided at the bottom of the BET machine, both ends of the connecting plate are fixedly connected to square rods, the two square rods are slidably connected to both sides of the BET machine, a telescopic tube is installed between the BET machine and the connecting plate, and the middle part of the connecting plate is hollow, a liquid nitrogen tank is placed on the BET machine, the inner diameter of the connecting plate is smaller than the outer diameter of the liquid nitrogen tank, and a limiting structure is installed between the BET machine and the connecting plate.

[0009] Preferably, the limiting structure includes: a connecting column, a hemispherical block, an avoidance groove, an unlocking ring, a sleeve, an extension block, a groove, a limit spring, a slider and a trapezoidal block. The top of the connecting plate is fixedly connected to the connecting column, the top of the connecting column is fixedly connected to the hemispherical block, one side of the hemispherical block is provided with an avoidance groove, one end of the connecting column is slidably connected to the unlocking ring, the two ends of the unlocking ring are designed to be inclined, the bottom end of the BET machine is fixedly connected to the sleeve, one end of the sleeve is provided with an extension block, the inner wall of the extension block is provided with a groove, the inner wall of the groove is fixedly connected to the limit spring, the inner wall of the groove is slidably connected to the slider, one side of the slider is fixedly connected to the limit spring, the end of the slider away from the spring is fixedly connected to the trapezoidal block, and one end of the trapezoidal block extends out of the inside of the sleeve.

[0010] Preferably, a reset spring is sleeved on the outer wall of the square rod, and both ends of the reset spring are fixedly connected to the bottom of the BET machine and the top of the connecting plate respectively.

[0011] Preferably, the telescopic tube is made of a transparent material, a measuring tube is provided at the bottom of the BET machine, and the stretched length of the telescopic tube is longer than the length of the measuring tube.

[0012] Preferably, the operating interface of the BET machine is provided with a display screen and input buttons. The display screen is used to display various parameters and results during the measurement process in real time, and the input buttons allow the user to input sample information, set measurement parameters, etc., thereby improving the usability and intelligence level of the device.

[0013] Preferably, the housing of the BET machine is made of corrosion-resistant and easy-to-clean materials to increase the service life and maintenance convenience of the device. At the same time, the bottom of the BET machine is also provided with non-slip pads to ensure the stability of the device during operation.

[0014] Preferably, a shock-absorbing pad is provided at the bottom of the connecting plate. The shock-absorbing pad is made of elastic material and is used to provide a buffer between the pressure reducing tank and the connecting plate to reduce the impact of vibration or impact on the measurement results during the measurement process.

[0015] Compared with related technologies, the device for measuring the surface area of ​​irregular urea particles based on the barometric pressure measurement method provided by the present invention has the following beneficial effects:

[0016] Improve measurement accuracy:

[0017] The BET method, based on the reversible physical adsorption of gas molecules on solid surfaces, allows for more accurate determination of the specific surface area of ​​urea granules. Compared to traditional particle size analysis methods, the BET method more comprehensively reflects the impact of irregularities such as granular roundness, smoothness, and angularity on surface area, providing more accurate data support for the preparation of urea slow-release fertilizers.

[0018] Expand the scope of application:

[0019] The improved BET instrument is not only suitable for measuring the specific surface area of ​​nanoporous catalysts, but has also been successfully applied to the measurement of the specific surface area of ​​large millimeter-sized particles such as urea granules, filling a gap in this field. This expansion has expanded the application of the BET method in fields such as materials science and agricultural chemistry.

[0020] Enhanced Security:

[0021] During operation, the telescopic tube automatically covers the sample tube when the connecting plate descends, effectively preventing the tube from being directly exposed to the liquid nitrogen. This protective measure significantly reduces the risk of frostbite caused by accidental contact with the cryogenic tube, thus improving the safety of experimental operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the device for measuring the surface area of ​​irregular urea particles based on the air pressure measurement method provided by the utility model;

[0023] Figure 2 for Figure 1 The structural diagram of the limiting structure shown;

[0024] Figure 3 for Figure 1 The structural schematic diagram of the feeding structure shown;

[0025] Figure 4 for Figure 1 The structural schematic diagram of the feeding structure shown.

[0026] Numbers in the figure: 1. BET machine; 2. Connecting plate; 3. Square rod; 4. Telescopic tube; 5. Liquid nitrogen tank; 6. Limiting structure; 7. Reset spring; 8. Measuring test tube; 9. Display screen; 10. Input button; 61. Connecting column; 62. Hemispherical block; 63. Avoidance groove; 64. Unlocking ring; 65. Sleeve; 66. Extension block; 67. Groove; 68. Limiting spring; 69. Slider; 610. Trapezoidal block. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0029] See also Figure 1-4 , a device for measuring the surface area of ​​irregular urea particles based on air pressure measurement, the device for measuring the surface area of ​​irregular urea particles based on air pressure measurement includes: the device for measuring the surface area of ​​irregular urea particles based on air pressure measurement provided by the utility model includes: a BET machine 1, a telescopic tube 4 and a limiting structure 6, a connecting plate 2 is provided at the bottom of the BET machine 1, both ends of the connecting plate 2 are fixedly connected with square rods 3, the two square rods 3 are slidably connected to both sides of the BET machine 1, a telescopic tube 4 is installed between the BET machine 1 and the connecting plate 2, and the middle part of the connecting plate 2 is hollow, a liquid nitrogen tank 5 is placed on the BET machine 1, the inner diameter of the connecting plate 2 is smaller than the outer diameter of the liquid nitrogen tank 5, and a It is equipped with a limiting structure 6, and a return spring 7 is provided on the outer wall of the square rod 3. The two ends of the return spring 7 are fixedly connected to the bottom of the BET machine 1 and the top of the connecting plate 2 respectively. The telescopic tube 4 is made of transparent material. A measuring tube 8 is provided at the bottom of the BET machine 1. The extended length of the telescopic tube 4 is longer than the length of the measuring tube 8. The operating interface of the BET machine 1 is provided with a display screen 9 and input buttons 10. The display screen 9 is used to display various parameters and results during the measurement process in real time. The input button 10 allows the user to input sample information, set measurement parameters, etc., which improves the ease of use and intelligence of the device. The outer shell of the BET machine 1 is made of corrosion-resistant and easy-to-clean materials to increase the service life of the device and facilitate maintenance. At the same time, the bottom of the BET machine 1 is also provided with a non-slip foot pad to ensure the stability of the device during operation. The bottom of the connecting plate 2 is provided with a shock-absorbing hydraulic tank. The shock-absorbing pad is made of elastic material and is used to provide a buffer between the hydraulic tank and the connecting plate 2 to reduce the impact of vibration or impact on the measurement results during the measurement process.

[0030] See also Figure 3-4The limiting structure 6 includes: a connecting column 61, a hemispherical block 62, an avoidance groove 63, an unlocking ring 64, a sleeve 65, an extension block 66, a groove 67, a limit spring 68, a slider 69 and a trapezoidal block 610. The top of the connecting plate 2 is fixedly connected to the connecting column 61, the top of the connecting column 61 is fixedly connected to the hemispherical block 62, one side of the hemispherical block 62 is provided with an avoidance groove 63, one end of the connecting column 61 is slidably connected to the unlocking ring 64, and the two ends of the unlocking ring 64 are inclined. The bottom end of the BET machine 1 is fixedly connected to the sleeve 65, one end of the sleeve 65 is provided with an extension block 66, the inner wall of the extension block 66 is provided with a groove 67, the inner wall of the groove 67 is fixedly connected to the limit spring 68, the inner wall of the groove 67 is slidably connected to the slider 69, one side of the slider 69 is fixedly connected to the limit spring 68, and the end of the slider 69 away from the spring 68 is fixedly connected to the trapezoidal block 610, and one end of the trapezoidal block 610 extends out of the sleeve 65.

[0031] It should be noted that: the specific steps of measuring the surface area of ​​irregular urea particles by the barometric method

[0032] 1. Sample Preparation

[0033] The urea granular sample is subjected to appropriate processing, such as grinding into powder, to increase its surface area.

[0034] The samples were degassed at 70 °C to remove moisture and volatile impurities on the sample surface.

[0035] 2. Adsorption Experiment

[0036] The sample is exposed to nitrogen gas at a certain temperature (usually liquid nitrogen temperature, about 77K).

[0037] By changing the pressure of nitrogen, the amount of nitrogen adsorption at different pressures was measured.

[0038] 3. Data Collection

[0039] The adsorption amount was recorded at different nitrogen partial pressures, usually in the low pressure range to ensure that the adsorption process was close to monolayer adsorption.

[0040] Use the BET equation to analyze the data: in:

[0041] V is the adsorption capacity at pressure P.

[0042] P0 is the saturated vapor pressure of nitrogen.

[0043] P is the actual pressure.

[0044] Vm is the monolayer adsorption capacity.

[0045] C is the BET constant, which is related to the adsorption energy.

[0046] 4. Calculate specific surface area

[0047] Solve the BET equation to find Vm (monolayer adsorption capacity).

[0048] Calculate the specific surface area A using Vm:

[0049] N A Avogadro's constant (6.022×10 23 MOL -1 ).

[0050] A m is the cross-sectional area of ​​the adsorbed molecule (nitrogen molecule), usually taken as 0.162nm 2 .

[0051] M is the mass of the sample.

[0052] 5. Results Analysis

[0053] The calculated specific surface area can reflect the surface area of ​​urea particles, including the roundness and smoothness of the particles.

[0054] Analysis of the specific surface area of ​​different urea granules can be used to evaluate their potential performance as slow-release fertilizers.

[0055] 6. Application

[0056] The obtained specific surface area data can be used to optimize the production process of urea granules and improve the slow-release effect and economy of fertilizers.

[0057] Although this method requires precise experimental equipment and strict experimental conditions in actual operation, it provides a scientific approach to evaluate and optimize the physical properties of urea granules.

[0058] The working principle of the device for measuring the surface area of ​​irregular urea particles based on the air pressure measurement method provided by the utility model is as follows:

[0059] 1. Initial State

[0060] Installing the sample tube: First, install the urea granule sample tube to be tested at the designated location on the BET machine 1. At this point, the connecting plate 2, connected by two square rods 3, is at its highest point on the BET machine 1. The hemispherical block 62 on the connecting plate 2 precisely engages with the trapezoidal block 610 fixed to the BET machine 1, ensuring the stability of the connecting plate 2. At the same time, the telescopic tube 4 is also extended, but its lower end is not covering the sample tube, allowing for subsequent operations.

[0061] Preparation of the return spring 7: The connecting plate 2 and the telescopic tube 4 are each connected to two return springs 7, which are in a pre-compressed state and are ready to provide a downward thrust after the connecting plate 2 is unlocked.

[0062] 2. Start the measurement process

[0063] Hydraulic tank rises: When the BET machine 1 is started, the hydraulic tank begins to rise. A device for immersing sample tubes is installed at the end of the hydraulic tank. As the hydraulic tank rises, several sample tubes are inserted into liquid nitrogen one by one to achieve the required ultra-low temperature environment.

[0064] Unlocking process: When the hydraulic tank rises to a certain distance, it triggers a mechanical device that pushes the distance unlocking mechanism at one end of the connecting plate 2. This mechanism drives the unlocking block upward via the connecting post 61. The unlocking post on the unlocking block then rises and compresses the trapezoidal locking block 610. This compression causes the trapezoidal locking block 610 to contract, releasing the locking relationship with the hemispherical block 62.

[0065] Connecting plate 2 descends: As the unlocking post continues to rise and engages with a specific portion of trapezoidal block 610, liquid nitrogen tank 5 begins to descend. At this point, since trapezoidal block 610 has been unlocked, it no longer restricts the movement of connecting plate 2. Simultaneously, the unlocking ring 64 slides into the escape groove 63 due to the movement of trapezoidal block 610. The inclined design of escape groove 63 ensures that the inclined surface of unlocking ring 64 is tangential to the outer wall of hemispherical block 62, further preventing the trapezoidal block 610 from reengaging with hemispherical block 62.

[0066] 3. Sample tube protection

[0067] Connecting plate 2 and telescopic tube 4 descend: After trapezoidal block 610 is unlocked, connecting plate 2 and telescopic tube 4 rapidly descend under the action of two return springs 7. As connecting plate 2 descends, telescopic tube 4 gradually expands until its lower end completely covers the sample tube. This rapid and smooth process effectively prevents direct exposure of the sample tube after liquid nitrogen treatment.

[0068] BET Measurement: After the sample tube is securely enclosed by the telescopic tube 4, the BET instrument 1 performs gas adsorption and desorption measurements according to a pre-defined procedure. Urea particles within the sample tube undergo reversible physical adsorption of nitrogen molecules at ultra-low temperatures. The equilibrium adsorption capacity is measured and the specific surface area of ​​the urea particles is calculated using the BET theoretical model.

[0069] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement, characterized in that: include: BET machine (1), the bottom of the BET machine (1) is provided with a connecting plate (2), both ends of the connecting plate (2) are fixedly connected to square rods (3), and the two square rods (3) are slidably connected to both sides of the BET machine (1); A telescopic tube (4) is installed between the BET machine (1) and the connecting plate (2), and the middle portion of the connecting plate (2) is hollow. A liquid nitrogen tank (5) is placed on the BET machine (1), and the inner diameter of the connecting plate (2) is smaller than the outer diameter of the liquid nitrogen tank (5); A limiting structure (6) is installed between the BET machine (1) and the connecting plate (2).

2. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: The limiting structure (6) includes: a connecting column (61), a hemispherical block (62), an avoidance groove (63), an unlocking ring (64), a sleeve (65), an extension block (66), a groove (67), a limiting spring (68), a slider (69) and a trapezoidal block (610). The top of the connecting plate (2) is fixedly connected to the connecting column (61), the top of the connecting column (61) is fixedly connected to the hemispherical block (62), one side of the hemispherical block (62) is provided with an avoidance groove (63), one end of the connecting column (61) is slidably connected to the unlocking ring (64), and both ends of the unlocking ring (64) are fixedly connected to the connecting column (61). The end is designed to be inclined, and the bottom end of the BET machine (1) is fixedly connected to a sleeve (65), one end of the sleeve (65) is provided with an extension block (66), the inner wall of the extension block (66) is provided with a groove (67), the inner wall of the groove (67) is fixedly connected to a limit spring (68), the inner wall of the groove (67) is slidably connected to a slider (69), one side of the slider (69) is fixedly connected to the limit spring (68), and one end of the slider (69) away from the spring (68) is fixedly connected to a trapezoidal block (610), and one end of the trapezoidal block (610) extends out of the interior of the sleeve (65).

3. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: The outer wall of the square rod (3) is provided with a reset spring (7), and the two ends of the reset spring (7) are fixedly connected to the bottom of the BET machine (1) and the top of the connecting plate (2) respectively.

4. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: The telescopic tube (4) is made of a transparent material. A measuring tube (8) is provided at the bottom of the BET machine (1). The stretched length of the telescopic tube (4) is longer than the length of the measuring tube (8).

5. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: The operating interface of the BET machine (1) is provided with a display screen (9) and an input button (10). The display screen (9) is used to display various parameters and results during the measurement process in real time, and the input button (10) allows the user to input sample information and set measurement parameters.

6. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: The outer shell of the BET machine (1) is made of corrosion-resistant and easy-to-clean material, and the bottom of the BET machine (1) is also provided with a non-slip foot pad.

7. The device for measuring the surface area of ​​irregular urea particles based on barometric pressure measurement according to claim 1, characterized in that: A shock-absorbing pad is provided at the bottom of the connecting plate (2).

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