Material contact type powder electrostatic monitoring device

Abstract

The utility model discloses a material contact type powder electrostatic monitoring device which comprises a first detection unit and a second detection unit, the first detection unit comprises a first Faraday inner cylinder and a first detection circuit connected with the first Faraday inner cylinder; the first detection circuit is used for detecting the total charge quantity of the first Faraday inner cylinder; the second detection unit comprises a second Faraday inner cylinder and a second detection circuit connected with the second Faraday inner cylinder; the second detection circuit is used for detecting interference charges of the second Faraday inner cylinder; and calculating the induced charge on the first Faraday inner cylinder according to the total charge of the first Faraday inner cylinder and the interference charge of the second Faraday inner cylinder. The static electricity monitoring device is very suitable for continuous real-time static electricity monitoring of continuous production of petrochemical industry powder.

Description

Technical Field

[0001] The utility model relates to the technical field of material static electricity detection, in particular to a material contact type powder static electricity monitoring device. Background Technique

[0002] In the production process of chemical powder materials represented by PE, PP, and EVA, the pneumatic conveying link can make the high volume resistivity powder materials carry 1 - 5 μC / kg or higher static electricity. At the same time, the granular material pneumatic conveying link contains a certain amount of polymer dust such as filaments and broken particles. At the same time, the chemical powder may also be accompanied by the escape of combustible monomer gases represented by polymer monomers such as ethylene and propylene. The critical value for the bin not to generate static discharge is 0.1 - 0.2 μC / kg. The above situation causes a high incidence of explosion accidents in petrochemical powder bins caused by static discharge.

[0003] Petrochemical powder production has extensive safety requirements for the continuous detection of the material static electricity level in the powder production process. Sampling with a cylinder-driven Faraday bucket, such as in patent ZL201920679427.7, can only achieve intermittent detection of materials. The detection data has a long interval and cannot form real-time continuous data. Moreover, the cylinder-type sampling static electricity detection may have material jamming, and faults such as the cylinder being stuck during propulsion or retraction may occur, resulting in failed material sampling. At the same time, the sampling cup inside the pneumatic conveying pipeline forms a protrusion. Under the high-speed material flow, the protruding sampling cup can cause a large number of broken particles and increase the granular material dust concentration. From the perspective of evaluating the pneumatic conveying dust concentration and broken particle control, the cylinder-type sampling static electricity monitoring should not be carried out frequently.

[0004] Some scholars have pointed out that the Faraday cage is used for non-contact continuous material flow static electricity detection and can be used for continuous detection of continuous material flows, but the limiting condition is that the material flow cannot contact the Faraday cage. Other scholars have pointed out that the simulated Faraday inner cylinder can be used to measure continuous material flows, and the same limiting condition is that the charged object to be measured can pass through the inner cylinder smoothly without friction. The simulated Faraday inner cylinder proposed by a certain industrial safety research institute for detecting continuously moving charged objects also has the same limiting condition that the material cannot contact the inner wall of the simulated Faraday inner cylinder.

[0005] The above detection methods of the Faraday cage and the traditional simulated Faraday inner cylinder that limit the material not to contact the inner cylinder have not been used for the detection of petrochemical powder pneumatic conveying materials in the past because the dilute-phase pneumatic conveying powder materials move at high speed in the pipeline, and the powder will contact the inner wall of the pipeline, resulting in collisions and friction.

[0006] In patents ZL201510994330.1 and ZL201810478603.0, the simulated Faraday inner cylinder structure is used to detect powder static electricity, innovatively supporting the material to directly contact the inner wall of the Faraday inner cylinder, but the above patents do not disclose methods for solving the signal interference and error elimination of the material contacting the Faraday inner cylinder. Summary of the Invention

[0007] The purpose of the present utility model is to provide a material-contact type powder electrostatic monitoring device to solve the deficiencies in the prior art. The present utility model adopts the principle of simulating the Faraday inner cylinder, allowing the material to directly contact the metal inner cylinder, with no protrusions in the monitor conveying pipeline, and using the same pipe diameter and the same type of pipeline for pneumatic conveying to achieve continuous electrostatic detection. The present utility model is very suitable for continuous real-time electrostatic monitoring in the continuous production of petrochemical powders. Cooperating with a continuous control algorithm for ion wind static elimination, a stable static charge elimination effect with a low static charge amount can be obtained. The application of the present utility model enables the electrostatic detection in chemical powder production to enter a real-time continuous detection mode.

[0008] The present utility model provides a material-contact type powder electrostatic monitoring device, which includes a first detection unit and a second detection unit;

[0009] The first detection unit includes a first Faraday inner cylinder and a first detection circuit connected to the first Faraday inner cylinder; the first detection circuit is used to detect the total charge amount of the first Faraday inner cylinder;

[0010] The second detection unit includes a second Faraday inner cylinder and a second detection circuit connected to the second Faraday inner cylinder; the second detection circuit is used to detect the interfering charge of the second Faraday inner cylinder;

[0011] Calculate the induced charge on the first Faraday inner cylinder according to the total charge of the first Faraday inner cylinder and the interfering charge of the second Faraday inner cylinder.

[0012] For the material-contact type powder electrostatic monitoring device as described above, optionally, the first detection circuit includes a first operational amplifier, a discharge switch, a discharge resistor, and a detection capacitor;

[0013] The non-inverting input terminal of the first operational amplifier is electrically connected to the outer wall of the first Faraday inner cylinder through a first wire; the inverting input terminal of the first operational amplifier is electrically connected to its output terminal;

[0014] The discharge switch and the discharge resistor are connected in series to form a discharge branch; one end of the discharge branch is electrically connected to the first wire, and the other end is grounded;

[0015] One end of the detection capacitor is electrically connected to the first wire, and the other end is grounded;

[0016] The discharge switch is used to close before detection to discharge the first Faraday inner cylinder; and to disconnect during the detection process.

[0017] For the material-contact type powder electrostatic monitoring device as described above, optionally, it further includes a safety resistor;

[0018] One end of the safety resistor is electrically connected to the first wire, and the other end is grounded.

[0019] The material contact type powder electrostatic monitoring device as described above, wherein, optionally, the second detection circuit includes a second operational amplifier and a differential elimination resistor;

[0020] The non-inverting input terminal of the second operational amplifier is electrically connected to the outer wall of the second Faraday inner cylinder through a second wire; the inverting input terminal of the second operational amplifier is electrically connected to its output terminal;

[0021] One end of the differential elimination resistor is electrically connected to the second wire, and the other end is grounded.

[0022] The material contact type powder electrostatic monitoring device as described above, wherein, optionally, it further includes an outer cylinder;

[0023] The first Faraday inner cylinder and the second Faraday inner cylinder are both coaxially arranged with the outer cylinder, and the first Faraday inner cylinder and the second Faraday inner cylinder have the same inner diameter;

[0024] An insulating pad is arranged between the first Faraday inner cylinder and the second Faraday inner cylinder.

[0025] The material contact type powder electrostatic monitoring device as described above, wherein, optionally, it further includes an explosion-proof chamber and a detection board arranged in the explosion-proof chamber;

[0026] The first detection circuit and the second detection circuit are arranged on the detection board;

[0027] An explosion-proof gland for leading out a signal wire is provided on the explosion-proof chamber.

[0028] The material contact type powder electrostatic monitoring device as described above, wherein, optionally, flanges are provided at both ends of the outer cylinder.

[0029] The material contact type powder electrostatic monitoring device as described above, wherein, optionally, the first Faraday inner cylinder and the second Faraday inner cylinder have the same shape and size;

[0030] Both the first Faraday inner cylinder and the second Faraday inner cylinder are insulated from the outer cylinder.

[0031] The present utility model also proposes a method for detecting material static electricity for the device, which includes the following steps:

[0032] S1, discharging the first Faraday inner cylinder;

[0033] S2. Obtain the total charge amount during the detection period through the first Faraday inner cylinder and the first detection circuit;

[0034] S3. Obtain the interfering charge during the detection period through the second Faraday inner cylinder and the second detection circuit;

[0035] S4. Calculate the charge amount transferred from the material to the first Faraday inner cylinder according to the total charge amount and the interfering charge.

[0036] Among them, in step S4, the formula for calculating the induced charge on the first Faraday inner cylinder is:

[0037] Q ind1 =Q tot1 -μQ 干扰

[0038] Among them, Q ind1 is the induced charge amount on the first Faraday inner cylinder, Q 总 is the total charge amount on the first Faraday inner cylinder during the detection period, μ is a constant coefficient, and Q 干扰 is the interfering charge during the detection period.

[0039] Among them, it further includes step S5,

[0040] S5. The induced charge in each measurement period is accumulated to the end value of the previous adjacent measurement period, where steps S1 to S4 are taken as one measurement period.

[0041] Compared with the prior art, the present utility model has at least the following beneficial effects:

[0042] Due to the adoption of a non-mechanical detection principle, the entire electrostatic monitoring device has no mechanical rotating parts and no cylinders, and there is no need for a cylinder to drag a constant-volume sampling cylinder to receive and pour materials. Charge monitoring is real-time detection, which can reflect the static charge situation of the material in real time. The monitoring response speed has been improved in principle. Due to the absence of cylinders and mechanical sampling cylinders, the service life and reliability of the monitor have been greatly improved.

[0043] The electrostatic monitor of the present utility model can be installed at any angle, supports vertical installation, also supports horizontal installation, and also supports inclined straight pipe section installation. The electrostatic monitor of the present utility model meets the requirement of the pneumatic conveying device design for the electrostatic monitor to have flexible installation adaptability, and is suitable for the safety transformation of old powder silos and the pneumatic conveying system with compact pipeline space.

[0044] When the production conditions such as environmental humidity change, the static electricity carried by the material pellets during pneumatic conveying changes. As a result, it is required that the static electricity elimination system continuously measures the static electricity level of the material, adjusts the amount of static electricity eliminating ions in real time, and ensures a stable low static electricity amount of the material after static electricity elimination. The static electricity monitor of the present utility model meets this requirement and continuously tracks the change of the static electricity of the material. It can avoid the deficiencies of the past mechanical constant volume using the cylinder sampling method, such as long sampling period, discontinuous sampling, having a data-free area in the middle of sampling, poor tracking of the charge change of the material, the static electricity elimination being based on empirical values, poor convergence, and high residual static electricity charge.

[0045] The static electricity monitor of the present utility model supports direct contact with the material, that is, it supports both dilute-phase pneumatic conveying of powder and dense-phase pneumatic conveying of powder, and is applicable to the production of a wide range of high volume resistivity petrochemical powders. Since this monitor cooperates with an ion wind static eliminator and adopts a feedback control algorithm, it can obtain an extremely low residual charge, less than the critical value at which the material does not generate static electricity discharge, thus realizing the intrinsic safety of static electricity in the pneumatic conveying of the material and improving the safety level of the petrochemical powder silo.

[0046] The contactable continuous detection static electricity monitor of the present utility model shows obvious advantages compared with the traditional cylinder sampling static electricity monitor. Its advanced monitoring technology can replace the traditional cylinder sampling products, completely solve the problems of the cylinder sampling products such as intermittent measurement of the material charge, non-intelligent static electricity elimination operation, inconvenient operation, feedback control hysteresis, and unsatisfactory static electricity elimination effect, and has significant social benefits. Description of the Drawings

[0047] Figure 1 It is an axonometric view of the overall structure of the present utility model.

[0048] Figure 2 It is a schematic structural diagram of the first detection circuit and the second detection circuit proposed by the present utility model.

[0049] Figure 3 It is an explanatory diagram of the calculation steps of the present utility model.

[0050] Description of the Reference Numerals in the Drawings:

[0051] 1 - First detection unit, 2 - Second detection unit, 3 - Outer cylinder, 4 - Insulating pad, 5 - Explosion-proof chamber,

[0052] 6 - Detection plate;

[0053] 11 - First Faraday inner cylinder, 12 - First detection circuit;

[0054] 21 - Second Faraday inner cylinder, 22 - Second detection circuit;

[0055] 121 - First operational amplifier, 122 - Discharge switch, 123 - Discharge resistor, 124 - Detection capacitor,

[0056] 125 - The first wire, 126 - Safety resistor;

[0057] 221 - The second operational amplifier, 222 - Differential elimination resistor, 223 - The second wire;

[0058] 31 - Flange;

[0059] 51 - Explosion-proof gland. Specific embodiments

[0060] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, rather than to limit the present invention.

[0061] In the prior art, when using the Faraday inner cylinder for detection, when the charged material comes into contact with the Faraday inner cylinder, there are the following several types of charges: one is the charge transferred from the charge carried by the material itself to the Faraday inner cylinder during the contact process; the second is that when the material powder contacts and separates from the metal inner barrel, due to the different abilities of the powder and the metal inner barrel to acquire electrons, an unbalanced distribution of charges will occur, and the metal inner barrel will lose or acquire charges; the third is that due to the principle of the Faraday inner cylinder, the Faraday inner cylinder will induce opposite static charges of the material inside the inner cylinder, and the external detection capacitor of the Faraday inner cylinder will have an equal amount of opposite-polarity static charges remaining. The only charge that can accurately represent the static electricity carried by the material is the third type of charge, that is, the induced charge, and the other two types of charges will both cause measurement errors. To reduce this error, the present invention proposes the following embodiments to solve it.

[0062] Embodiment 1

[0063] Please refer to Figure 1 and Figure 2 , the present invention provides a material contact type powder electrostatic monitoring device, which includes a first detection unit 1 and a second detection unit 2. The first detection unit 1 is used to detect the total charge amount within a corresponding time period, and the second detection unit 2 is used to detect the interference charge within a corresponding time period. In this application, the interference charge refers to the charge that the metal inner barrel will lose or acquire and the induced charge, that is, the aforementioned second type of charge and the third type of charge.

[0064] Specifically, the first detection unit 1 includes a first Faraday inner cylinder 11 and a first detection circuit 12 connected to the first Faraday inner cylinder 11; the first detection circuit 12 is used to detect the total charge amount of the first Faraday inner cylinder 11.

[0065] The second detection unit 2 includes a second Faraday inner cylinder 21 and a second detection circuit 22 connected to the second Faraday inner cylinder 21; the second detection circuit 22 is used to detect the interference charge of the second Faraday inner cylinder 21.

[0066] In specific implementation, the pneumatic conveying system usually uses pipes made of 304SS stainless steel. The first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 of the monitor of the present utility model both adopt metal pipes with the same material, the same pipe diameter, and the same internal treatment requirements as those of the pneumatic conveying. For the first type of charge mentioned above, that is, when the material carrying static charge collides with the metal inner cylinder of the simulated Faraday inner cylinder of the monitor, the charge carried by the powder itself may be directly transferred to the simulated Faraday inner cylinder at the contact surface. This part of the transferred charge can be defined as the transferred charge, denoted as Q tra , the transferred charge generated on the first Faraday inner cylinder 11 is denoted as Q tra1 , the transferred charge generated on the second Faraday inner cylinder 21 is denoted as Q tra2 ; For the second type of charge mentioned above, that is, when the powder of the material comes into contact with and separates from the metal inner barrel, due to the different abilities of the powder and the metal inner cylinder to acquire electrons, an unbalanced distribution of charges will occur, and the metal inner cylinder will lose or gain some charges. This part of the charge can be defined as the separated charge, denoted as Q lea , the separated charge generated on the first Faraday inner cylinder 11 is denoted as Q lea1 , the separated charge generated on the second Faraday inner cylinder 21 is denoted as Q lea2 ; For the third type of charge mentioned above, that is, due to the principle of the Faraday inner cylinder, the Faraday inner cylinder will induce opposite static charges of the material inside the inner cylinder, and the external detection capacitor of the Faraday inner cylinder will have the remaining opposite-polarity and equal static charges. The remaining charge on this part of the external capacitor is the induced charge, denoted as Q ind , the induced charge generated on the first Faraday inner cylinder 11 is denoted as Q ind1 , the induced charge generated on the second Faraday inner cylinder 21 is denoted as Q ind2 ; Since the transferred charge, the separated charge, and the induced charge exist simultaneously and are mixed together, if the material directly contacts the inner wall of the simulated Faraday inner cylinder, the voltage signal on the external capacitor cannot be directly used for charge calculation. This is the reason why the Faraday cover and the traditional simulated Faraday inner cylinder for detecting continuous material flow must limit the material from contacting the Faraday inner cylinder.

[0067] In this application, the total charge is detected by the first detection unit 1, and the sum of the separated charge and the induced charge is detected by the second detection unit 2. The induced charge of the first Faraday inner cylinder 11 is calculated based on the total charge of the first Faraday inner cylinder 11 and the interference charge of the second Faraday inner cylinder 21.

[0068] Due to the adoption of a non-mechanical detection principle, there are no mechanical rotating parts in the entire charge monitoring unit, no cylinders, and there is no need for a cylinder to drag a constant-volume sampling cylinder to receive and pour materials. Charge monitoring is real-time detection, which can reflect the static charge situation of the material in real time. The monitoring response speed has been improved in principle. Since there are no cylinders and mechanical sampling cylinders, the service life and reliability of the monitor have been greatly improved.

[0069] The electrostatic monitor of the present utility model can be installed at any angle, supports vertical installation, also supports horizontal installation, and also supports installation in an inclined straight pipe section. The electrostatic monitor of the present utility model meets the requirement of the pneumatic conveying device design for the electrostatic monitor to have flexible installation adaptability, and is suitable for the safety transformation of old powder bins and the pneumatic conveying system with a compact pipeline space. Since the static charge carried by the material during pneumatic conveying of granular materials changes when production conditions such as environmental humidity change, it is required that the electrostatic elimination system continuously measures the static electricity level of the material and adjusts the amount of charged ions in real time to ensure a stable low static electricity level of the material after static elimination. The electrostatic monitor of the present utility model meets this requirement and continuously tracks the change of the static electricity of the material. It can avoid the deficiencies of the past mechanical constant-volume sampling cylinder sampling method, such as long sampling period, discontinuous sampling, having a data-free area in the middle of sampling, poor tracking of material charge changes, relying on empirical values for static elimination, poor convergence, and high residual static charge.

[0070] The electrostatic monitor of the present utility model supports direct contact with the material, that is, it supports dilute-phase pneumatic conveying of powder and also supports dense-phase pneumatic conveying of powder, and is suitable for the production of a wide range of high-volume resistivity petrochemical powders. Since the monitor cooperates with an ion wind static eliminator and uses a feedback control algorithm, an extremely low residual charge can be obtained, which is less than the critical value at which the material does not generate static discharge, thus realizing the intrinsic safety of static electricity in the pneumatic conveying of materials and improving the safety level of petrochemical powder bins. The contact-type continuous detection electrostatic monitor of the present utility model shows obvious advantages compared with the traditional cylinder-type sampling electrostatic monitor. Its advanced monitoring technology can replace traditional cylinder sampling products, completely solve the problems of intermittent measurement of material charge by cylinder sampling products, non-intelligent static elimination operation, inconvenient operation, feedback control hysteresis, and unsatisfactory static elimination effect, and has significant social benefits.

[0071] Specifically, in some embodiments, in order to detect the total charge amount, the first detection circuit 12 includes a first operational amplifier 121, a discharge switch 122, a discharge resistor 123, and a detection capacitor 124.

[0072] The non-inverting input terminal of the first operational amplifier 121 is electrically connected to the outer wall of the first Faraday inner cylinder 11 through a first wire 125; the inverting input terminal of the first operational amplifier 121 is electrically connected to its output terminal.

[0073] The discharge switch 122 is connected in series with the discharge resistor 123 to form a discharge branch; one end of the discharge branch is electrically connected to the first wire 125, and the other end is grounded; in specific implementation, the function of the discharge switch 122 is to be briefly closed at the beginning of each detection period to discharge the detection capacitor 124. In one implementation, the value of the detection period can be 5 seconds. At the beginning of the detection period, the discharge switch 122 is closed for 4 ms. Of course, the value of the detection period can also be other values, and the closing time of the discharge switch 122 can be changed accordingly, as long as the ratio of the closing time of the discharge switch 122 to the duration of the detection period is less than 0.1%. And the closing time of the discharge switch 122 should be greater than 7 times the time constant of the typical value of the discharge resistor 123 and the detection capacitor 124. In specific implementation, the value of the discharge resistor 123 can be 5 - 50 Ω, and a preferred value is 50 Ω.

[0074] One end of the detection capacitor 124 is electrically connected to the first wire 125, and the other end is grounded; in specific implementation, the value of the detection capacitor 124 can be 1 μF to 50 μF. In a preferred implementation, the value of the detection capacitor 124 can be 10 μF.

[0075] The discharge switch 122 is used to be closed before detection to discharge the first Faraday inner cylinder 11; and is opened during the detection process.

[0076] In the actual application process, the monitoring device performs detections periodically. Each measurement period is a detection period, denoted as T. At the beginning of each measurement period, the discharge switch 122 is first closed for a short time to fully discharge the detection capacitor 124, that is, after this short time, the remaining charge of the detection capacitor 124 is less than 0.1% of the original charge amount. Then the discharge switch 122 is opened, and the charge amount of the detection capacitor 124 and the voltage at the output end of the first operational amplifier 121 are measured. Through the real-time voltage at the output end of the first operational amplifier 121 and the value of the detection capacitor 124, the total charge value Q on the first Faraday inner cylinder 11 can be obtained. tot1 。

[0077] The total charge value on the first Faraday inner cylinder 11 satisfies the following formula:

[0078] Q tot1 =Q tra1 +Q lea1 +Q ind1 。

[0079] In specific implementation, in order to ensure that the impedance limit of the continuous detection of the inner cylinder to the protective ground by the Faraday inner cylinder principle complies with the general standard for preventing electrostatic accidents, a safety resistor 126 is also included; one end of the safety resistor 126 is electrically connected to the first wire 125, and the other end is grounded. The safety resistor Rsaf The value is set within the range of 50M to 500M ohm resistors. In a preferred implementation, the value is 500M ohm. The safety resistor should not be set too small because the size of the safety resistor determines the decay rate of the induced charge, and quantitatively detecting the induced charge is the core purpose of the monitor detection.

[0080] The input signal V of the first detection circuit 12 a includes the detection of the transferred charge signal, separated charge signal, and induced charge signal of the first Faraday inner cylinder 11. The input signal of the first detection circuit 12 will detect a long interval periodic short grounding, and an output voltage V is formed at the output end of the voltage follower composed of the first operational amplifier. tot .

[0081] In specific implementation, in order to detect the interfering charge, the second detection circuit 22 includes a second operational amplifier 221 and a differential cancellation resistor 222.

[0082] The non-inverting input terminal of the second operational amplifier 221 is electrically connected to the outer wall of the second Faraday inner cylinder 21 through a second wire 223; the inverting input terminal of the second operational amplifier 221 is electrically connected to its output terminal.

[0083] One end of the differential cancellation resistor 222 is electrically connected to the second wire 223, and the other end is grounded. The differential cancellation resistor usually takes a value of 500 to 50k ohm, such as a typical value of 50k ohm. The differential cancellation resistor should not be too large because the purpose of setting the differential cancellation resistor R rem requires that the induced charge of the second Faraday inner cylinder 21 be rapidly attenuated. Due to the relatively small value of the differential cancellation resistor 222, the induced charge of the second Faraday inner cylinder 21 can be rapidly attenuated to zero. In a certain implementation, when the parasitic capacitance Cpar of the non-inverting input terminal of the second operational amplifier 221 is 1pF or less, the equivalent capacitance from the second Faraday inner cylinder 21 to the ground is 99pF, and the induced charge Q ind2 can be attenuated to less than 0.1% of the original amplitude in 7 times the RC typical time constant Rrem = 50kΩ, C = 100pF, 35μs. Because the powder material continuously collides with and separates from the inner cylinder of the monitor, the transferred charge Qtra2 of the second Faraday inner cylinder 21 and the separated charge Q lea2 of the second Faraday inner cylinder 21 rem will be continuously generated and measured by the output voltage V tra2 of the output terminal of the second operational amplifier 221. The sum of the transferred charge Q lea2 and the separated charge Q rem can be obtained through the current flowing through the differential cancellation resistor R rem and time, that is, the voltage on the differential cancellation resistor Rrem is calculated from the resistance value and time t.

[0084]

[0085] That is, with the differential elimination resistor R rem being determined, the output terminal voltage V of the second operational amplifier 221 rem through the time integration with polarity of the curve, the transferred charge Q tra2 and the separated charge Q lea2 can obtain the numerical value of the sum.

[0086] Due to the corresponding proportional relationship between the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21, therefore, Q tra1 + Q lea1 = μ(Q tra2 + Q lea2 ); where the value of μ is related to the corresponding proportional relationship between the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21. In a preferred implementation, when the materials of the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 are the same, the inner diameter sizes are equal, the inner surface roughness is the same, and the contact areas with the material are equal, the value of μ is 1.

[0087] That is to say, accurate detection results can be obtained through the following formula.

[0088]

[0089] Therefore, the detection accuracy can be improved through this electrostatic monitoring device.

[0090] In a preferred implementation, the present utility model further includes an outer cylinder 3; specifically in implementation, the outer cylinder 3 is grounded to form an outer shielding layer.

[0091] The first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 are both coaxially arranged with the outer cylinder 3, and the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 have the same inner diameter; an insulating pad 4 is arranged between the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21.

[0092] In specific implementation, metal compression rings are connected to both ends of the outer cylinder 3. The metal compression ring at one end is insulated from the first Faraday inner cylinder 11 through an insulating layer, and the metal compression ring at the other end is insulated from the second Faraday inner cylinder 21 through an insulating layer. The metal compression ring is connected to the outer cylinder 3, that is, the metal compression ring is also grounded.

[0093] To ensure safety, it further includes an explosion-proof chamber 5 and a detection board 6 disposed inside the explosion-proof chamber 5; specifically, the explosion-proof chamber 5 is fixedly disposed on the outer periphery of the outer cylinder 3. The first detection circuit 12 and the second detection circuit 22 are disposed on the detection board 6; an explosion-proof gland 51 for leading out a signal wire is provided on the explosion-proof chamber 5. In this way, safety can be ensured.

[0094] To facilitate connecting this monitoring device to a pipeline, flanges 31 are provided at both ends of the outer cylinder 3. Specifically, this device is connected in series to the pipeline through the flanges 31.

[0095] The first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 have the same shape and size; both the first Faraday inner cylinder 11 and the second Faraday inner cylinder 21 are insulated from the outer cylinder 3.

[0096] Since the first Faraday inner cylinder 11 is periodically grounded at long detection intervals, the final Q ind1 is the calculated value of the long detection interval plus the end value of the previous long detection interval. Similar to the requirements of traditional analog Faraday inner cylinders, when there is no material and no output ions in the Faraday inner cylinder, i.e., the material conveying pipeline, the detected value Q ind1 needs to be zero-calibrated.

[0097] Figure 3 A calculation step description diagram is disclosed, in which the Q tra2 and Q lea2 calculation steps in the case of stable values are listed. T ind1 、T I 、T II 、T III are long detection intervals. Q tot1 Subtract the transferred charge Q tra2 of the second Faraday inner cylinder 21 and the separated charge Q lea2 to obtain the induced charge Q ind1 of the first Faraday inner cylinder 11. That is, calculate the corresponding interference charge according to the voltage at the output end of the second operational amplifier, i.e., the sum of the transferred charge and the separated charge of the second Faraday inner cylinder 21; calculate the total charge of the first Faraday inner cylinder according to the voltage at the output end of the first operational amplifier. Calculate the induced charge of the first Faraday inner cylinder 11 based on the total charge and the interference charge. This electrostatic continuous detection method for a material-contactable type using a double analog Faraday cylinder is called a full-time differential analog Faraday cylinder electrostatic continuous detection method.

[0098] Embodiment 2

[0099] This embodiment proposes a method for the device described in Embodiment 1. The same parts can be referred to Embodiment 1, and only its detection method will be described below.

[0100] This embodiment provides a method for detecting the static electricity of materials for the device described in Embodiment 1, which includes the following steps:

[0101] S1, discharge the first Faraday inner cylinder 11; the discharging process of the first Faraday inner cylinder 11 is realized by closing the discharge switch 122 in Embodiment 1. The closing timing and closing time can refer to Embodiment 1.

[0102] S2, obtain the total charge amount within the detection period through the first Faraday inner cylinder 11 and the first detection circuit 12; in this embodiment, the detection period is one measurement cycle in Embodiment 1.

[0103] S3, obtain the interfering charges within the detection period through the second Faraday inner cylinder 21 and the second detection circuit 22; the calculation method of the interfering charges can refer to Embodiment 1 and will not be elaborated here.

[0104] S4, calculate the charge amount transferred from the material to the first Faraday inner cylinder 11 based on the total charge amount and the interfering charges. Specifically, in step S4, the formula for calculating the induced charge on the first Faraday inner cylinder 11 is: Q ind1 =Q tot1 -μQ 干扰 ;

[0105] where Q ind1 is the induced charge amount on the first Faraday inner cylinder, Q 总 is the total charge amount on the first Faraday inner cylinder within the detection period, μ is a constant coefficient, and Q 干扰 is the interfering charge within the detection period. Further calculation formulas can refer to Embodiment 1 and will not be elaborated here.

[0106] S5, accumulate the induced charges within each measurement cycle to the end value of the previous adjacent measurement cycle, where steps S1 to S4 are one measurement cycle. In this way, the measurement results can be made continuous.

[0107] In specific implementation, splice the induced charge of this detection period with the induced charge at the end of the previous period, that is, translate the induced charge of this detection period along the vertical axis so that the induced charge amount at the start of this detection period is equal to the induced charge amount at the end of the previous period.

[0108] The above has detailed the structure, characteristics, and function effects of the present utility model based on the embodiments shown in the drawings. The above is only the preferred embodiment of the present utility model, but the present utility model is not limited to the implementation scope shown in the drawings. Any changes made according to the concept of the present utility model, or modified into equivalent embodiments with equivalent changes, still within the spirit covered by the specification and the drawings, should be within the protection scope of the present utility model.

Claims

1. A powder electrostatic monitoring device of material contact type, characterized in that: It includes a first detection unit (1) and a second detection unit (2); The first detection unit (1) includes a first Faraday inner cylinder (11) and a first detection circuit (12) connected to the first Faraday inner cylinder (11); the first detection circuit (12) is used to detect the total electric charge of the first Faraday inner cylinder (11); The second detection unit (2) includes a second Faraday inner cylinder (21) and a second detection circuit (22) connected to the second Faraday inner cylinder (21); the second detection circuit (22) is used to detect the interfering charge of the second Faraday inner cylinder (21); Calculate the induced charge on the first Faraday inner cylinder (11) according to the total charge of the first Faraday inner cylinder (11) and the interfering charge of the second Faraday inner cylinder (21).

2. The material contact type powder electrostatic monitoring device according to claim 1, characterized in that: The first detection circuit (12) includes a first operational amplifier (121), a discharge switch (122), a discharge resistor (123), and a detection capacitor (124); The non-inverting input terminal of the first operational amplifier (121) is electrically connected to the outer wall of the first Faraday inner cylinder (11) through a first wire (125); the inverting input terminal of the first operational amplifier (121) is electrically connected to its output terminal; The discharge switch (122) and the discharge resistor (123) are connected in series to form a discharge branch; one end of the discharge branch is electrically connected to the first wire (125), and the other end is grounded; One end of the detection capacitor (124) is electrically connected to the first wire (125), and the other end is grounded; The discharge switch (122) is used to close before detection to discharge the first Faraday inner cylinder (11); and open during detection.

3. The material contact type powder electrostatic monitoring device according to claim 2, wherein: It also includes a safety resistor (126); One end of the safety resistor (126) is electrically connected to the first wire (125), and the other end is grounded.

4. The material contact type powder electrostatic monitoring device according to claim 3, characterized in that: The second detection circuit (22) includes a second operational amplifier (221) and a differential elimination resistor (222); The non-inverting input terminal of the second operational amplifier (221) is electrically connected to the outer wall of the second Faraday inner cylinder (21) through a second wire (223); the inverting input terminal of the second operational amplifier (221) is electrically connected to its output terminal; One end of the differential elimination resistor (222) is electrically connected to the second wire (223), and the other end is grounded.

5. The material contact type powder electrostatic monitoring device according to any one of claims 1-4, characterized in that: It also includes an outer cylinder (3); The first Faraday inner cylinder (11) and the second Faraday inner cylinder (21) are both coaxially arranged with the outer cylinder (3), and the first Faraday inner cylinder (11) and the second Faraday inner cylinder (21) have the same inner diameter; An insulating pad (4) is provided between the first Faraday inner cylinder (11) and the second Faraday inner cylinder (21).

6. The material contact type powder electrostatic monitoring device according to claim 5, characterized in that: It also includes an explosion-proof chamber (5) and a detection board (6) arranged in the explosion-proof chamber (5); The first detection circuit (12) and the second detection circuit (22) are arranged on the detection board (6); An explosion-proof gland (51) for leading out a signal wire is provided on the explosion-proof chamber (5).

7. The material contact type powder electrostatic monitoring device according to claim 5, wherein: Flanges (31) are provided at both ends of the outer cylinder (3).

8. The powder electrostatic monitoring device of the material contact type according to claim 5, characterized in that: The first Faraday inner cylinder (11) and the second Faraday inner cylinder (21) have the same shape and size; Both the first Faraday inner cylinder (11) and the second Faraday inner cylinder (21) are insulated from the outer cylinder (3).

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