A negative pressure attraction-type particle electrostatic charge sampling and determination system and method

Abstract

This invention discloses a negative pressure attraction-type particle electrostatic charge sampling and measurement system and method, belonging to the field of particle electrostatic charge sampling and measurement technology. It addresses the problem in existing particle electrostatic charge measurement methods where sampling and measurement are performed in separate steps, and the sampling operation can cause changes in the electrostatic charge of the particle, affecting the accuracy of the measurement. In this system, a contact plate is placed at the opening at the front end of the particle chamber and is electrically connected to the particle chamber. The sampling tube's outlet end is electrically connected to the contact plate and passes through the contact plate to communicate with the particle chamber. The particle chamber is electrically connected to the input end of a charge meter via a connecting terminal. A negative pressure attraction device is connected to the rear end of the particle chamber via a flexible tube. The method includes the particle being drawn into the particle chamber through the sampling tube under negative pressure attraction; the particle conducts its charge to the charge meter within the sampling tube, contact plate, and particle chamber; and the charge meter measures the charge parameters of the particle. This invention can be used for particle electrostatic charge sampling and measurement.

Description

Technical Field

[0001] This invention belongs to the field of particle electrostatic charge sampling and measurement technology, and particularly relates to a negative pressure attraction-type particle electrostatic charge sampling and measurement system and method. Background Technology

[0002] In industrial production processes involving powders, the triboelectric properties of powder particles often result in high static electricity. This static electricity can lead to particle adhesion, surface sticking, and even spark discharge, disrupting normal production and posing safety hazards. Therefore, the measurement of static charge in powder particles is crucial for studying particle charging characteristics and subsequently improving production equipment and processes.

[0003] Currently, the commonly used methods for determining the static charge of particles usually involve two steps: sampling and measurement. Because the static charge is unstable, it is very easy for the charge to change during the sampling process. In particular, when metal instruments (e.g., sampling spoons) are used for sampling, the contact between the metal instruments and the particles can cause the charge to dissipate, thus affecting the accuracy of the final measurement. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a negative pressure attraction-type particle electrostatic charge sampling and measurement system and method to solve the problem that in the prior art particle electrostatic charge measurement method, sampling and measurement are performed in separate steps, and the sampling operation will cause changes in the electrostatic charge of the particle to be measured, which will affect the accuracy of the measurement.

[0005] The objective of this invention is mainly achieved through the following technical solutions.

[0006] This invention provides a negative pressure attraction-type particle electrostatic charge sampling and measurement system, including a sampling device, a charge meter, and a negative pressure attraction device. The sampling device includes a sampling tube, a contact plate, a connecting terminal, and a particle chamber. The sampling tube, contact plate, connecting terminal, and particle chamber are all made of conductive materials. The front end of the particle chamber is open. The contact plate covers the opening at the front end of the particle chamber and is electrically connected to the particle chamber. The sampling tube's outlet end is electrically connected to the contact plate and passes through the contact plate to communicate with the particle chamber. One end of the connecting terminal is electrically connected to the particle chamber, and the other end of the connecting terminal is electrically connected to the input end of the charge meter. The negative pressure attraction device is connected to the rear end of the particle chamber through a flexible tube.

[0007] Furthermore, the aforementioned negative pressure attraction-type particle electrostatic charge sampling and measurement system also includes a shell made of conductive material and an outer cover made of insulating material. The front end of the shell is open, and the outer cover is placed over the opening of the shell and fixedly connected to the shell. A through hole is opened on the outer cover, and the sampling tube's outlet end passes through the through hole and the contact plate in sequence to communicate with the particle cavity. The contact plate is fixed inside the outer cover, and the rear end of the shell is connected to the negative pressure attraction device.

[0008] Furthermore, the through-hole is matched with the sampling tube.

[0009] Furthermore, the rear end of the particle chamber is open, allowing the particle chamber to communicate with the shell.

[0010] Furthermore, the aforementioned negative pressure attraction-type particle electrostatic charge sampling and measurement system also includes a filter screen, which is placed over the opening at the rear end of the particle chamber and fixedly connected to the rear end of the particle chamber. The mesh size of the filter screen is smaller than the particle size of the particle to be measured.

[0011] Furthermore, the connection terminal includes a connection post, an insulating layer, and a grounding layer sequentially arranged from the inside out. The grounding layer is insulated from the connection post and the particle cavity, and the connection post is electrically connected to the charge meter.

[0012] Furthermore, the connecting post is electrically connected to the charge meter via a connecting wire.

[0013] Furthermore, the connecting line includes a signal transmission line, an insulation layer, and a signal shielding mesh, which are sequentially arranged from the inside out, and the signal shielding mesh is grounded.

[0014] Furthermore, the grounding terminal of the charge meter is grounded through the outer casing, and the grounding layer of the connecting terminal is grounded through the outer casing.

[0015] This invention also provides a negative pressure attraction-based particle electrostatic charge sampling and measurement method, which uses the above-mentioned negative pressure attraction-based particle electrostatic charge sampling and measurement system. The sampling and measurement method includes the following steps:

[0016] The particles to be tested are drawn into the particle chamber through the sampling tube under negative pressure.

[0017] The particle to be tested conducts its charge to the charge meter in the sampling tube, contact plate and particle cavity, and the charge meter measures the charge parameters of the particle to be tested.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects.

[0019] A) The negative pressure attraction-type particle electrostatic charge sampling and measurement system provided by this invention is suitable for online sampling and measurement of particle electrostatic charge parameters (e.g., particle charge, charge-to-mass ratio, surface charge density, and equivalent current). Since the sampling tube is directly connected to the particle cavity, the sampling tube, contact plate, and particle cavity constitute a conductive cavity. The particle cavity is kept under negative pressure by the negative pressure attraction device, which enables the simultaneous sampling and measurement of the particle to be measured. This avoids the change in the electrostatic charge of the particle to be measured due to the sampling and measurement being performed in separate steps, thereby effectively improving the accuracy of particle electrostatic charge sampling and measurement. This provides a new means for the electrostatic measurement of particles in powder industry and chemical industry equipment, and provides a reference for equipment upgrades and improvements.

[0020] B) The negative pressure attraction particle electrostatic charge sampling and measurement system provided by the present invention can collect the electrostatic charge parameters of the particle at the instant the particle to be tested contacts the sampling tube, contact plate and particle cavity, since the sampling tube, contact plate and particle cavity are all conductive materials, and there is basically no loss of electrostatic charge, thereby effectively improving the accuracy of particle electrostatic charge sampling and measurement.

[0021] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0023] Figure 1 This is a schematic diagram of the negative pressure attraction-type particle electrostatic charge sampling and measurement system provided in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the sampling device in the negative pressure attraction-type particle electrostatic charge sampling and determination system provided in Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the sampling tube in the negative pressure attraction-type particle electrostatic charge sampling and determination system provided in Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of the particle cavity in the negative pressure attraction-type particle electrostatic charge sampling and measurement system provided in Embodiment 1 of the present invention.

[0027] Figure label:

[0028] 1-Sampling device; 101-Sampling tube; 1011-Reduced diameter section; 1012-Constant diameter section; 1013-Expanded diameter section; 1014-Elastic convex area; 102-Outer cover; 103-Contact piece; 104-Connecting terminal; 105-Filter screen; 106-Particle chamber; 1061-Cavity guide groove; 107-Outer shell; 2-Charge meter; 3-Negative pressure suction device. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0030] Example 1

[0031] This embodiment provides a negative pressure attraction-type particle electrostatic charge sampling and measurement system. (See also...) Figures 1 to 2 The system includes a sampling device 1, a charge meter 2, and a negative pressure suction device 3. The sampling device 1 includes a sampling tube 101 made of conductive material, a contact piece 103, a connecting terminal 104, and a particle chamber 106. The front end of the particle chamber 106 is open. The contact piece 103 covers the opening at the front end of the particle chamber 106 and is electrically connected to the particle chamber 106. The sampling tube 101 is electrically connected to the contact piece 103 and passes through the contact piece 103 to communicate with the particle chamber 106. One end of the connecting terminal 104 is electrically connected to the particle chamber 106, and the other end of the connecting terminal 104 is electrically connected to the input end of the charge meter 2. The negative pressure suction device 3 is connected to the rear end of the particle chamber 106 through a flexible tube.

[0032] It should be noted that the end of the particle chamber 106 with the sampling tube 101 is defined as the front end, and the end of the particle chamber 106 corresponding to the head is defined as the rear end.

[0033] Compared with the prior art, the negative pressure attraction particle electrostatic charge sampling and measurement system provided in this embodiment is suitable for online sampling and measurement of particle electrostatic charge parameters (e.g., particle charge, charge-to-mass ratio, surface charge density, and equivalent current). Since the sampling tube 101 is directly connected to the particle cavity 106, the sampling tube 101, the contact plate 103, and the particle cavity 106 constitute a conductive cavity. The negative pressure attraction device 3 keeps the particle cavity 106 in a negative pressure state, which enables the simultaneous sampling and measurement of the particle to be tested. This avoids the change in the electrostatic charge of the particle to be tested due to the sampling and measurement being performed in separate steps, thereby effectively improving the accuracy of particle electrostatic charge sampling and measurement. This provides a new means for the electrostatic measurement of particles in powder industry and chemical industry equipment, and provides a reference for equipment upgrades and improvements.

[0034] Furthermore, since the sampling tube 101, contact plate 103, and particle cavity 106 are all made of conductive materials, the electrostatic charge parameters of the particle to be tested can be collected the instant the particle comes into contact with the sampling tube 101, contact plate 103, and particle cavity 106, with virtually no loss of electrostatic charge, thereby effectively improving the accuracy of particle electrostatic charge sampling and measurement.

[0035] To ensure the stability of the overall structure, the aforementioned negative pressure attraction-type particle electrostatic charge sampling and measurement system also includes a shell 107 made of conductive material and an outer cover 102 made of insulating material. The front end of the shell 107 is open, and the outer cover 102 is placed over the opening of the shell 107 and is fixedly connected to the shell 107 by threads or other detachable means. Air tightness must be ensured during connection, and after connection, the contact piece 103 should be tightly attached to the particle cavity 106 and electrically conductive. A through hole is opened on the outer cover 102, and the sampling tube 101 passes through the through hole and the contact piece 103 in sequence and communicates with the particle cavity 106. The contact piece 103 is fixed inside the outer cover 102, and the rear end of the shell 107 is connected to the negative pressure attraction device 3.

[0036] During the sampling and measurement process, in order to reduce the shaking of the sampling tube 101, the above-mentioned through hole is matched with the sampling tube 101. That is to say, the diameter of the through hole is equal to the outer diameter of the sampling tube 101, there is no gap between the sampling tube 101 and the through hole, and the sampling tube 101 can achieve a fixed connection with the through hole after passing through the through hole.

[0037] It should be noted that, in order to facilitate the connection of the negative pressure suction device 3, the rear end of the outer shell 107 is connected to the negative pressure suction device 3. However, in actual applications, the purpose of the negative pressure suction device 3 is to create a negative pressure state in the particle chamber 106. Therefore, the rear end of the particle chamber 106 is open, so that the particle chamber 106 is connected to the shell, thereby creating a negative pressure state in the particle chamber 106.

[0038] In order to prevent the particles to be tested from clogging the negative pressure suction device 3, the above-mentioned negative pressure suction particle electrostatic charge sampling and measurement system also includes a filter screen 105. The filter screen 105 is covered at the opening at the rear end of the particle chamber 106 and is fixedly connected to the rear end of the particle chamber 106 by welding or other means. The mesh size of the filter screen 105 is smaller than the particle size of the particles to be tested, so as to confine the particles to be tested within the particle chamber 106, thereby preventing the particles to be tested from clogging the negative pressure suction device 3.

[0039] Specifically, the structure of the connecting terminal 104 is a nested structure, including a connecting post, an insulating layer and a grounding layer arranged sequentially from the inside to the outside. The grounding layer is insulated from the connecting post and the particle cavity 106. The connecting post is electrically connected to the charge meter 2 through a connecting wire.

[0040] Specifically, the structure of the connecting line includes, from the inside out, a signal transmission line, an insulation layer, and a signal shielding mesh, which are sequentially nested. The signal shielding mesh is grounded and can effectively shield signal interference, further improving the accuracy of particle electrostatic charge sampling and measurement.

[0041] Understandably, in order to provide a reference potential, the grounding terminal of the charge meter 2 is grounded through the housing 107, and the grounding layer of the connecting terminal 104 is grounded through the housing 107.

[0042] Considering that the particle cavity 106 is suspended inside the outer shell 107, displacement of the particle cavity 106 is inevitable as the usage time increases. In order to ensure the installation stability between the particle cavity 106 and the outer shell 107, the above-mentioned negative pressure attraction particle electrostatic charge sampling and measurement system also includes an insulating support. The particle cavity 106 is mounted inside the outer shell 107 through the insulating support.

[0043] To improve the sampling performance of sampling tube 101, for the structure of sampling tube 101, please refer to... Figure 3 Specifically, it includes a narrowing section 1011, a constant-diameter section 1012, and an expanding section 1013 connected sequentially along the flow direction of the particles to be tested. The narrowing section 1011 accelerates the flow velocity of the particles to be tested and enhances their attraction, making it suitable for attracting larger particles under negative pressure when the negative pressure suction remains constant. The constant-diameter section 1012 stabilizes the flow of the particles to be tested, increasing the contact time and probability between the particles and the constant-diameter section 1012, thereby improving charge conduction between them. The expanding section 1013 facilitates the smooth entry of the particles to be tested from the sampling tube 101 into the particle cavity 106.

[0044] For example, the length-to-diameter ratio (i.e., length-to-diameter ratio) of the sampling tube 101 is 10-20, the length of the sampling tube 101 is 10-20 cm, and the length ratio of the reduced diameter section 1011, the constant diameter section 1012 and the expanded diameter section 1013 is 1-1.5:7.5-9:1-1.5.

[0045] In order to further increase the contact time and contact probability between the test particles and the constant diameter section 1012, a spiral tube guide groove is opened on the inner wall of the expanded diameter section 1013. The spiral tube guide groove can generate a spiral flow of test particles, which can further improve the contact time and contact probability between the test particles and the sampling tube 101, thereby further improving the charge conduction between the test particles and the sampling tube 101.

[0046] It is worth noting that, due to the design of the reduced-diameter section 1011, the diameter of the feed end of the reduced-diameter section 1011 is larger than the diameter of the discharge end of the reduced-diameter section 1011 (i.e., the constant-diameter section 1012). During sampling, the constant-diameter section 1012 of the sampling tube 101 may become clogged. To reduce the occurrence of clogging in the constant-diameter section 1012, at least one elastic convex region 1014 is provided on the side wall of the constant-diameter section 1012. The inner wall of the elastic convex region 1014 is concave. The outer wall of 1014 is elastically convex. Once the constant diameter section 1012 becomes blocked, the elastically convex area 1014 can be pressed from the outer wall of the constant diameter section 1012, causing the elastically convex area 1014 to deform into the constant diameter section 1012. Then, the elastically convex area 1014 is released, and it pops outward and generates a certain vibration. Through the vibration, the particles to be tested at the blockage location of the constant diameter section 1012 are loosened and moved, thereby solving the problem of blockage in the constant diameter section 1012.

[0047] To improve the contact time and probability between the test particle and the particle cavity 106, a spiral-shaped cavity guide groove 1061 is also formed on the inner wall of the particle cavity 106. (See [reference]) Figure 4 The spiral flow channel 1061 can generate a spiral flow of particles to be tested, which further increases the contact time and contact probability between the particles to be tested and the sampling tube 101, thereby further improving the charge conduction between the particles to be tested and the sampling tube 101.

[0048] It is worth noting that the cavity guide channel 1061 may cause the test particles to remain in the cavity guide channel 1061 and be unable to be poured out of the particle cavity 106. To solve the above problem, the cavity guide channel 1061 includes an inclined wall and a vertical wall arranged sequentially from the front end to the rear end of the particle cavity 106. The inclined wall is arranged radially relative to the particle cavity 106, and the vertical wall is arranged radially along the particle cavity 106. In this way, on the one hand, the arrangement of the guide channel can prolong the contact time between the test particles and the particle cavity 106 and increase the contact area between the test particles and the particle cavity 106. On the other hand, when the test particles are poured out of the particle cavity 106, the inclined wall can guide the test particles so that they can be poured out of the particle cavity 106 smoothly.

[0049] For example, the contact piece 103, filter 105 and particle chamber 106 are made of conductive metal, such as pure copper; the outer shell 107 is made of conductive metal, such as stainless steel; the outer cover 102 is made of insulating material, such as nylon; and the sampling tube 101 is made of conductive metal (e.g., pure copper) and covered with insulating material (e.g., insulating rubber).

[0050] Example 2

[0051] This embodiment provides a negative pressure attraction-based particle electrostatic charge sampling and measurement method, which uses the negative pressure attraction-based particle electrostatic charge sampling and measurement system provided in Embodiment 1. The sampling and measurement method includes the following steps:

[0052] Step 1: Start the preheating function of the charge meter, and the preheating time is 10-15 minutes;

[0053] Step 2: Turn on the negative pressure suction device and check the overall airtightness of the negative pressure suction particle electrostatic charge sampling and measurement system to ensure that the particle chamber is under negative pressure.

[0054] Step 3: Activate the charge acquisition function of the charge meter, bring the sample inlet of the sampling tube close to the particle to be tested, and the particle to be tested is drawn into the particle cavity through the sampling tube under the negative pressure attraction. The particle to be tested transfers the charge on the particle to the charge meter through contact charging and induction charging in the sampling tube, contact plate and particle cavity. The charge meter measures the charge parameters of the particle to be tested, and completes the sampling and measurement of the static charge of the particle.

[0055] Compared with the prior art, the beneficial effects of the negative pressure attraction particle electrostatic charge sampling and determination method provided in this embodiment are basically the same as those of the negative pressure attraction particle electrostatic charge sampling and determination system provided in Embodiment 1, and will not be described in detail here.

[0056] To ensure measurement accuracy, for example, the percentage of the particle to be measured in the particle cavity is 20% to 80%.

[0057] For example, step 2 above, checking the overall airtightness of the negative pressure suction type particle electrostatic charge sampling and measurement system includes the following steps:

[0058] Step 21: Block the sampling end of the sampling tube;

[0059] Step 22: Observe the pressure gauge reading on the negative pressure suction device. If the pressure gauge reading decreases, it indicates that the overall airtightness of the negative pressure suction particulate electrostatic charge sampling and determination system is good. If the pressure gauge reading remains unchanged, it indicates that there is a leak in the negative pressure suction particulate electrostatic charge sampling and determination system.

[0060] Specifically, in step 3 above, the charge parameters include particle charge, charge-to-mass ratio, and surface charge density. The charge parameters of the particle to be tested are measured by the charge meter in the following steps:

[0061] Stop the charge meter's charge acquisition function, read the charge quantity q, C, turn off the negative pressure suction device, open the outer cover, take out the particle to be tested from the particle chamber and weigh it to obtain the particle mass m, kg, and the charge-to-mass ratio q / m of the particle to be tested can be obtained.

[0062] Calculate the surface charge density σ, C / m of the particles. 2The following formula is used:

[0063]

[0064] Where ρ is the density of the particle to be measured, kg / m³ 3 d p Let be the particle size, in meters (m).

[0065] In step 3 above, the charge parameters include the equivalent current. The charge parameters of the particle to be tested are measured by the charge meter in the following steps:

[0066] Record the cumulative charge q i With time t i The changing relationship;

[0067] The slope of the curve of cumulative charge changing with time is obtained, and the equivalent current I, A of the particle is calculated using the following formula:

[0068]

[0069] in, The average value over time, in seconds. C represents the average charge.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A negative pressure attraction-type particle electrostatic charge sampling and measurement system, characterized in that, Includes a sampling device, a charge meter, and a negative pressure suction device; The sampling device includes a sampling tube, a contact plate, a connecting terminal, and a particle chamber. The sampling tube, contact plate, connecting terminal, and particle chamber are all made of conductive materials. The front end of the particle chamber is open, the contact plate is placed over the opening at the front end of the particle chamber and is electrically connected to the particle chamber, the sampling tube is electrically connected to the contact plate and passes through the contact plate to communicate with the particle chamber, one end of the connecting terminal is electrically connected to the particle chamber, the other end of the connecting terminal is electrically connected to the input end of the charge meter, and the negative pressure suction device is connected to the rear end of the particle chamber through a flexible tube. The sampling tube includes a narrowing section, a constant diameter section, and an expanding section connected sequentially along the flow direction of the particles to be tested. The sidewall of the constant diameter section is provided with at least one elastic convex area. The inner wall of the particle cavity is provided with a spiral cavity guide groove; the groove wall of the cavity guide groove includes an inclined wall and a vertical wall arranged sequentially from the front end to the rear end of the particle cavity, the inclined wall is arranged at an inclination relative to the radial direction of the particle cavity, and the vertical wall is arranged along the radial direction of the particle cavity.

2. The negative pressure attraction-type particle electrostatic charge sampling and measurement system according to claim 1, characterized in that, It also includes a shell made of conductive material and an outer cover made of insulating material. The front end of the shell is open, and the outer cover is placed over the opening of the shell and fixedly connected to the shell. The outer cover has a through hole, and the sampling tube's outlet end passes through the through hole and the contact piece in sequence to communicate with the particle chamber. The contact piece is fixed to the inside of the outer cover, and the rear end of the outer shell is connected to the negative pressure suction device.

3. The negative pressure attraction-type particle electrostatic charge sampling and measurement system according to claim 2, characterized in that, The through-hole is matched with the sampling tube.

4. The negative pressure attraction-type particle electrostatic charge sampling and measurement system according to claim 2, characterized in that, The rear end of the particle cavity is open, allowing the particle cavity to communicate with the shell.

5. The negative pressure attraction-type particle electrostatic charge sampling and measurement system according to claim 4, characterized in that, It also includes a filter screen, which is placed over the opening at the rear end of the particle chamber and fixedly connected to the rear end of the particle chamber. The mesh size of the filter screen is smaller than the particle size of the particle to be tested.

6. The negative pressure attraction-type particle electrostatic charge sampling and determination system according to claim 2, characterized in that, The connection terminal includes a connecting post, an insulating layer, and a grounding layer arranged sequentially from the inside to the outside. The grounding layer is insulated from the connecting post and the particle cavity. The connecting post is electrically connected to the charge meter.

7. The negative pressure attraction-type particle electrostatic charge sampling and determination system according to claim 6, characterized in that, The connecting post is electrically connected to the charge meter via a connecting wire.

8. The negative pressure attraction-type particle electrostatic charge sampling and determination system according to claim 7, characterized in that, The connecting line includes a signal transmission line, an insulation layer, and a signal shielding mesh, which are sequentially arranged from the inside out, and the signal shielding mesh is grounded.

9. The negative pressure attraction-type particle electrostatic charge sampling and determination system according to claim 6, characterized in that, The grounding terminal of the charge meter is grounded through the outer casing, and the grounding layer of the connection terminal is grounded through the outer casing.

10. A negative pressure attraction-based method for sampling and determining the electrostatic charge of particles, characterized in that, The negative pressure attraction-type particle electrostatic charge sampling and measurement system according to any one of claims 1 to 9, wherein the sampling and measurement method comprises the following steps: The particles to be tested are drawn into the particle chamber through the sampling tube under negative pressure. The particle to be tested conducts its charge to the charge meter in the sampling tube, contact plate and particle cavity, and the charge meter measures the charge parameters of the particle to be tested.

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