Charged dust cloud minimum ignition energy and flame propagation testing device and method

Abstract

The invention discloses a charged dust cloud minimum ignition energy and flame propagation testing device and method, the device comprises a support frame, a transparent test box is fixed on the support frame, and a box door is hinged to the top of the transparent test box; the corona discharge system is mounted in the transparent test box and is used for corona discharge; the electric spark release system is mounted in the transparent test box and is used for releasing electric sparks; the object image acquisition system is arranged outside the transparent test box and is used for acquiring explosive object images; the vibration dust raising system is mounted at the bottom of the transparent test box and is used for raising dust; the dust charge capacity test system is arranged outside the transparent test box and is used for measuring the charge capacity and the mass of the dust sample and calculating the dust charge-to-mass ratio; and a terminal control system. According to the invention, the test of the minimum ignition energy and the flame propagation characteristic of the charged dust cloud formed after electrostatic electrification of dust can be realized, so that the influence rule of the dust charge quantity on the minimum ignition energy and the flame propagation characteristic can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of dust explosion characteristics and risk parameter testing, and in particular to a device and method for testing the minimum ignition energy and flame propagation of a charged dust cloud. Background Art

[0002] Dust explosion is a major safety hazard in production and life. Accurately understanding the ignition and flame propagation process of dust explosion is an important basis for the prevention and control of dust explosion disasters. The minimum ignition energy of the dust cloud is the minimum ignition energy required to ignite the mixed cloud of dust and air, and is the core parameter to characterize the risk of combustible dust explosion. Clarifying the flame propagation characteristics during the dust explosion process is a prerequisite for assessing the intensity and scope of dust explosion disasters, formulating emergency management measures, and reducing disaster losses. With the continuous development of the dust production and processing industry, the phenomenon of dust electrostatic charging has also attracted widespread attention. During the production and processing process, dust will frequently collide and rub against equipment and walls, causing electrostatic charging and carrying an electric charge. In addition, processes such as electrostatic spraying and electrostatic dust removal involve dust charging processes. Generally, the higher the resistivity of dust, the stronger its insulation and the easier it is to accumulate static electricity. However, due to the insulating effect of air, dusts of different resistivities may generate and accumulate static electricity. The accumulation of static electricity will further disturb the ignition and flame propagation process of the dust cloud, potentially leading to a decrease in the minimum ignition energy of the dust cloud and intensifying its flame propagation, increasing its explosion hazard.

[0003] At present, the main technical route for the minimum ignition energy and flame propagation test of dust clouds is to achieve it through the test experiment of igniting dust clouds by electrode discharge inside visible cavities such as Hartmann tubes. Experimental tests can obtain the minimum ignition energy of dust clouds, flame speed and other characteristic parameters related to ignition and flame propagation of dust clouds. However, the existing test devices and methods basically do not involve charged dust, and it is impossible to obtain the minimum ignition energy and flame propagation characteristics of charged dust clouds. At present, only the Chinese invention disclosure text CN114609187A discloses a multiphase system explosion test device affected by coupled environmental factors, which involves the test of the multiphase explosion process under the influence of an external electrostatic field environment. However, the invention does not consider the test method of the minimum ignition energy and flame propagation characteristic parameters of charged dust clouds under the influence of static electricity accumulation generated by the dust itself. The lack of test methods for the minimum ignition energy and flame propagation of charged dust clouds restricts the accurate assessment of the risk of dust explosion under the influence of static electricity accumulation and the effective understanding of its explosion hazards. Therefore, it is urgent to test the flame propagation characteristic parameters such as the minimum ignition energy of the charged dust cloud, the flame morphology structure, and the flame speed under the influence of the dust's own electrostatic accumulation. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for testing the minimum ignition energy and flame propagation of charged dust clouds, so as to solve the problems existing in the prior art.

[0005] To achieve the above object, the present invention provides the following solution: The present invention provides a device for testing the minimum ignition energy and flame propagation of a charged dust cloud, comprising: A charged dust explosion chamber, comprising a support frame, a transparent test box is fixed on the support frame, and a box door is hinged on the top of the transparent test box; A corona discharge system, installed in the transparent test box, for corona discharge; An electric spark release system, installed in the transparent test box, for releasing electric sparks; An image collection system, arranged outside the transparent test box, for collecting images of explosions; A vibration dust raising system is installed at the bottom of the transparent test box to raise dust; A dust charge test system is arranged outside the transparent test box and is used to measure the charge and mass of the dust sample and calculate the dust charge-to-mass ratio; The terminal control system, the corona discharge system, the electric spark release system, the object image collection system, and the vibration dust raising system are all electrically connected to the terminal control system.

[0006] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the corona discharge system comprises a discharge plate, a grounding plate and a DC electrostatic generator; The discharge plate and the grounding plate are respectively fixedly connected to two opposite sides of the inner wall of the transparent test box, and the DC electrostatic generator is arranged outside the transparent test box and is electrically connected to the discharge plate; A plurality of pointed electrodes are arranged in an array on the discharge plate.

[0007] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the spark discharge system comprises a spark discharge electrode and a spark energy control circuit system; The electric spark discharge electrode comprises two electrode heads with pointed ends facing each other and symmetrically fixed on two opposite side walls of the transparent test box, and the two electrode heads are respectively connected to the positive electrode and the negative electrode of the electric spark energy control circuit system; Among them, a voltage and current monitoring submodule is provided in the electric spark energy control circuit system, and the voltage and current monitoring submodule is used to monitor the discharge voltage and current of the electric spark energy control circuit system.

[0008] According to the charged dust cloud minimum ignition energy and flame propagation test device provided by the present invention, the spark discharge electrode is made of tungsten, the gap between the two spark discharge electrodes is 0mm-10mm, the tip curvature diameter of the spark discharge electrode is 2mm, and the spark energy control circuit system can release spark energy in the range of 0.1mJ-3J, with an adjustment accuracy of 0.1mJ.

[0009] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the image acquisition system includes a high-speed camera and a free radical spectrum acquisition instrument; The high-speed camera is used to collect the flame morphology of charged dust explosion in real time; The free radical spectrum collector comprises a fiber optic probe, a grating spectrometer and an oscilloscope connected in series in sequence. The fiber optic probe is used to capture the free radical spectrum signals of the chemical reaction of the charged dust explosion flame front; the grating spectrometer is used to collect and analyze the free radical spectrum signals obtained by the fiber optic probe; and the oscilloscope is used to display and store the free radical spectrum signals collected by the grating spectrometer.

[0010] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the vibration dust raising system comprises an insulating piston plate and a servo electric cylinder; The edge of the insulating piston plate is provided with a sealing ring, and the insulating piston plate is slidably connected in the transparent test box; The servo electric cylinder is fixed to the bottom of the support frame, and the top end of the servo electric cylinder is detachably connected to the bottom surface of the insulating piston plate.

[0011] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the dust charge amount testing system comprises a Faraday cup, a charge meter, and an electronic balance; The Faraday cup is placed on the electronic balance, and the charge meter is electrically connected to the Faraday cup; The charge meter is used to measure the charge q of the dust sample in the Faraday cage, and the electronic balance is used to measure the mass m of the dust sample in the Faraday cage; The calculation formula of the dust charge-to-mass ratio is q / m.

[0012] According to the device for testing the minimum ignition energy and flame propagation of charged dust clouds provided by the present invention, the terminal control system includes a timing controller and a host computer, and the timing controller is electrically connected to the host computer.

[0013] A method for testing the minimum ignition energy and flame propagation of charged dust clouds, comprising the following steps: S1, preset dust charging conditions, dust sample charge and dust cloud concentration, put the dust sample through the top of the transparent test box to the top surface of the vibration dust system according to the preset dust cloud concentration, close the box door, start the vibration dust system, adjust the frequency and stroke of the vibration dust system until the maximum height of the dust just reaches the top box door, and continue for a certain period of time; S2, start the corona discharge system to charge the dust, intermittently suspend the dust raising and charging process, take a small amount of sample after the dust settles, put it into the dust charge test system to calculate the charge-to-mass ratio of the dust sample to be tested, determine the charge of the dust sample to be tested and compare it with the preset value, repeat the dust raising and charging process until the charge of the dust sample reaches the preset value, and turn off the vibration dust raising system and the corona discharge system; S3, start the vibration dust raising system to raise the charged dust again, and after the ignition delay period, start the electric spark release system to generate electric sparks with preset energy; S4, visually observe whether the electric spark can ignite the dust cloud, adjust the preset energy of the electric spark according to whether the ignition is successful or not, replace the dust sample and use different ignition delay periods to repeat S1-S3 until the minimum electric spark energy required to ignite the dust cloud with preset charge and concentration is obtained; change the charge of the dust sample and the concentration of the dust cloud according to the charging conditions and repeat the operation to obtain the minimum electric spark energy required to ignite the charged dust cloud with different concentrations under the preset charging conditions, and take the minimum value as the minimum ignition energy of the charged dust cloud within the test concentration range under the charging conditions; S5, under the preset dust charging condition and under the most sensitive dust cloud concentration condition with minimum ignition energy, replace the dust sample, repeat S1-S3, use the electric spark with energy level higher than the minimum ignition energy of the charged dust cloud to ignite the charged dust cloud, and start the image acquisition system to collect and monitor the flame propagation morphology and the free radical spectrum signal of the flame front at the same time as the electric spark is released; S6, repeat S1-S5 tests ten times, and take the average value of the minimum ignition energy and flame propagation characteristic parameters of the charged dust cloud obtained from the ten tests as the final result.

[0014] The present invention discloses the following technical effects: The present invention can realize the dust charging of dust and the test of the minimum ignition energy and flame propagation of charged dust cloud by combining various systems. In the transparent test box, by setting up the corona charging system and the vibration dust raising system, the corona charging of dust in the vibration dust raising process can be realized; the dust charge amount can be measured by using the dust charge amount testing device; further combined with the vibration dust raising system, the electric spark release system, and the image acquisition system, the multi-level electric spark ignition and explosion flame propagation test of the charged dust cloud can be realized, and then the minimum ignition energy, flame propagation speed, flame morphology structure and free radical change characteristics of the chemical reaction of the charged dust cloud can be obtained through the terminal control system, and the explosion pressure and flame can be released in time and safely through the box door, which is safe and reliable.

[0015] The present invention is specifically used for the electrostatic accumulation and explosion risks of dust in powder-related industries. It can test the minimum ignition energy and flame propagation characteristics of charged dust clouds formed after dust electrostatic charging, thereby obtaining the influence of dust charge on its minimum ignition energy and flame propagation characteristics, further expanding the scope of application of dust cloud minimum ignition energy and flame propagation testing technology, and providing support for the accurate assessment and prevention of dust explosion risks in powder-related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of the minimum ignition energy and flame propagation test device of the charged dust cloud of the present invention; Figure 2 The present invention is a flow chart of the method for testing the minimum ignition energy and flame propagation of charged dust clouds.

[0018] Among them, 1. Box door; 2. Transparent test box; 3. Support frame; 4. Discharge plate; 5. Grounding plate; 6. DC static generator; 7. Spark discharge electrode; 8. Spark energy control circuit system; 9. High-speed camera; 10. Fiber optic probe; 11. Grating spectrometer; 12. Oscilloscope; 13. Insulating piston plate; 14. Servo cylinder; 15. Faraday cup; 16. Charge meter; 17. Electronic balance; 18. Timing controller; 19. Host computer. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figure 1-Figure 2 The present invention provides a device for testing the minimum ignition energy and flame propagation of charged dust clouds, comprising: The charged dust explosion chamber comprises a support frame 3, a transparent test box 2 is fixed on the support frame 3, and a box door 1 is hinged on the top of the transparent test box 2; the support frame 3 adopts a steel structure support frame 3, and the whole is a box-shaped structure, and the transparent test box 2 is cast by insulating quartz glass; A corona discharge system, installed in the transparent test box 2, for corona discharge; The electric spark release system is installed in the transparent test box 2 and is used to release the electric spark; An image collection system, arranged outside the transparent test box 2, is used to collect images of explosions; A vibration dust raising system is installed at the bottom of the transparent test box 2 to raise dust; The dust charge test system is arranged outside the transparent test box 2 and is used to measure the charge and mass of the dust sample and calculate the dust charge-to-mass ratio; The terminal control system, corona discharge system, electric spark release system, image collection system and vibration dust removal system are all electrically connected to the terminal control system.

[0022] In this embodiment, electromagnets are respectively provided on the box door 1 and the transparent test box 2. The two electromagnets are attracted to each other, and the suction force is controlled by controlling the voltage. In this way, when the pressure in the transparent test box 2 exceeds the suction force, the box door 1 can be directly opened to achieve the effect of safe pressure relief. According to the further optimized scheme, the corona discharge system includes a discharge plate 4, a grounding plate 5 and a DC electrostatic generator 6; the discharge plate 4 and the grounding plate 5 are both made of copper; the DC electrostatic generator 6 can generate 0-±10KV adjustable high voltage DC power, and the tip curvature diameter of the tip electrode is 0.5mm.

[0023] The discharge plate 4 and the grounding plate 5 are respectively fixedly connected to the two opposite sides of the inner wall of the transparent test box 2, and the DC electrostatic generator 6 is arranged outside the transparent test box 2 and is electrically connected to the discharge plate 4; A plurality of pointed electrodes are arrayed on the discharge plate 4. The pointed electrodes are processed on the discharge plate 4 by a plastic forming method; According to a further optimized solution, the spark release system includes a spark discharge electrode 7 and a spark energy control circuit system 8; The spark discharge electrode 7 includes two electrode heads with pointed ends facing each other and symmetrically fixed on two opposite side walls of the transparent test box 2, and the two electrode heads are respectively connected to the positive electrode and the negative electrode of the spark energy control circuit system 8; Among them, the spark energy control circuit system 8 is provided with a voltage and current monitoring submodule, which is used to monitor the discharge voltage and current of the spark energy control circuit system 8. The spark energy control circuit system 8 can generate a spark with a preset nominal energy range of 0.1mJ-3J and an adjustment accuracy of 0.1mJ through the spark discharge electrode 7, and can monitor the discharge voltage and current during the spark release process, and can monitor the actual spark energy by integrating the voltage and current product over time.

[0024] According to a further optimization scheme, the spark discharge electrode 7 is made of tungsten, the gap between the two spark discharge electrodes 7 is 0mm-10mm, the tip curvature diameter of the spark discharge electrode 7 is 2mm, and the spark energy control circuit system 8 can release spark energy in the range of 0.1mJ-3J with an adjustment accuracy of 0.1mJ.

[0025] To further optimize the scheme, the image acquisition system includes a high-speed camera 9 and a free radical spectrum acquisition device; The high-speed camera 9 is used to collect the flame morphology of the charged dust explosion in real time; The free radical spectrum collector comprises a fiber optic probe 10, a grating spectrometer 11, and an oscilloscope 12 which are connected in series in sequence. The fiber optic probe 10 is used to capture the free radical spectrum signals of the chemical reaction of the charged dust explosion flame front; the grating spectrometer 11 is used to collect and analyze the free radical spectrum signals obtained by the fiber optic probe 10; and the oscilloscope 12 is used to display and store the free radical spectrum signals collected by the grating spectrometer 11.

[0026] The high-speed camera 9 and the grating spectrometer 11 can be triggered by the timing controller 18 when the spark energy control circuit system 8 generates sparks to ignite the charged dust cloud. The high-speed camera 9 can collect the flame morphology of the charged dust cloud in the flame propagation process in real time and store the relevant images in the host computer 19, while the grating spectrometer 11 collects the free radical signals of the flame front during the flame propagation process through the optical fiber probe 10 connected to it and records and stores them in the oscilloscope 12 for subsequent analysis and research on the flame propagation speed, flame morphology structure, flame front chemical reaction rate and reaction intensity.

[0027] Further optimizing the scheme, the vibration dust raising system includes an insulating piston plate 13 and a servo electric cylinder 14; A sealing ring is provided at the edge of the insulating piston plate 13, and the insulating piston plate 13 is slidably connected in the transparent test box 2; The servo electric cylinder 14 is fixed to the bottom of the support frame 3 , and the top end of the servo electric cylinder 14 is detachably connected to the bottom surface of the insulating piston plate 13 .

[0028] A suction cup is installed on the top of the servo electric cylinder 14 , and the servo electric cylinder 14 is fixed to the insulating piston plate 13 through the suction cup.

[0029] Further optimizing the scheme, the dust charge test system includes a Faraday cup 15, a charge meter 16, and an electronic balance 17; The Faraday cage 15 is placed on the electronic balance 17, and the charge meter 16 is electrically connected to the Faraday cage 15; The charge meter 16 is used to measure the charge q of the dust sample in the Faraday cup 15, and the electronic balance 17 is used to measure the mass m of the dust sample in the Faraday cup 15; Among them, the calculation formula for dust charge-to-mass ratio is q / m.

[0030] According to a further optimization scheme, the terminal control system includes a timing controller 18 and a host computer 19 , and the timing controller 18 is electrically connected to the host computer 19 .

[0031] A method for testing the minimum ignition energy and flame propagation of charged dust clouds, comprising the following steps: S1, preset dust charging conditions, dust sample charge and dust cloud concentration, put the dust sample through the top of the transparent test box 2 to the top surface of the vibration dust system according to the preset dust cloud concentration, close the box door 1, start the vibration dust system, adjust the frequency and stroke of the vibration dust system until the maximum height of the dust just reaches the top box door 1, and continue for a certain period of time; S2, start the corona discharge system to charge the dust, intermittently suspend the dust raising and charging process, take a small amount of sample after the dust settles, put it into the dust charge test system to calculate the charge-to-mass ratio of the dust sample to be tested, determine the charge of the dust sample to be tested and compare it with the preset value, repeat the dust raising and charging process until the charge of the dust sample reaches the preset value, and turn off the vibration dust raising system and the corona discharge system; S3, start the vibration dust raising system to raise the charged dust again, and after the ignition delay period, start the electric spark release system to generate electric sparks with preset energy; S4, visually observe whether the electric spark can ignite the dust cloud, adjust the preset energy of the electric spark according to whether the ignition is successful or not, replace the dust sample and use different ignition delay periods to repeat S1-S3 until the minimum electric spark energy required to ignite the dust cloud with preset charge and concentration is obtained; change the charge of the dust sample and the concentration of the dust cloud according to the charging conditions and repeat the operation to obtain the minimum electric spark energy required to ignite the charged dust cloud with different concentrations under the preset charging conditions, and take the minimum value as the minimum ignition energy of the charged dust cloud within the test concentration range under the charging conditions; S5, under the preset dust charging condition and under the most sensitive dust cloud concentration condition with minimum ignition energy, replace the dust sample, repeat S1-S3, use the electric spark with energy level higher than the minimum ignition energy of the charged dust cloud to ignite the charged dust cloud, and start the image acquisition system to collect and monitor the flame propagation morphology and the free radical spectrum signal of the flame front at the same time as the electric spark is released; S6, repeat S1-S5 tests ten times, and take the average value of the minimum ignition energy and flame propagation characteristic parameters of the charged dust cloud obtained from the ten tests as the final result.

[0032] Embodiment, preset dust charge condition: the dust charge is a fixed value Q, the minimum ignition energy and flame propagation of the charged dust cloud under fixed charge conditions are tested; Step 1. Vibration dust: Preset a certain dust cloud concentration c1 and the inner volume V of the transparent test box 2, calculate the required dust sample mass M1=c1·V, weigh the dust sample with a mass of M1 and place it on the insulating piston plate 13 through the top door 1 of the transparent test box 2, start the servo electric cylinder 14, adjust the push-pull frequency and stroke until the maximum height of the dust just reaches the top door 1, and continue for a certain period of time.

[0033] Step 2. Dust charging: Start the DC electrostatic generator 6 to charge the dust, and adjust the DC voltage from low to high to control the charging intensity; intermittently shut down the servo electric cylinder 14 and the electrostatic generator to suspend the dust and charging process and let the dust sample stand. After it is completely settled on the insulating piston plate 13, take a small amount of sample and put it into the dust charge test device to measure its charge q1. At the same time, measure its mass m1 through the electronic balance 17, so that its charge-to-mass ratio can be calculated as q1 / m1. Further, the charge Q1=(M1-m1)·q1 / m1 of the dust sample in the transparent test box 2 can be obtained, and compared with the preset fixed dust charge Q, the above dust charging process is repeated until the charge of the dust sample in the transparent test box 2 reaches the preset value Q, and then the servo electric cylinder 14 and the electrostatic generator are turned off.

[0034] Step 3. Dust ignition: Start the servo electric cylinder 14 again, keep the push-pull frequency and stroke used in step 1 to raise the charged dust again, after a certain ignition delay period, start the multi-level spark release device, preset a certain spark energy, release the spark of preset energy through the discharge electrode to ignite the charged dust cloud, and record the discharge voltage and current changes during the spark generation process, and calculate the actual energy E1 of the generated spark by integrating the voltage and current product over time.

[0035] Step 4. Minimum ignition energy test: Observe visually whether the spark with energy E1 can ignite the charged dust cloud, adjust the preset spark energy according to whether the ignition is successful or not, replace the dust sample and repeat steps 1-3 with different ignition delay periods until the minimum spark energy Emin(c1,Q) required to ignite the dust cloud with charge Q at concentration c1 is obtained; change the preset dust cloud concentration (c2, c3, …, cn) and repeat the above steps to obtain the minimum spark energy required to ignite charged dust clouds with different concentrations of charge Q: Emin(c2,Q), Emin(c3,Q), …, Emin(cn,Q), analyze its changing trend with dust cloud concentration, take the minimum value Emin(c1, c3, …, cn,Q) as the minimum ignition energy of the charged dust cloud with charge Q within the test dust cloud concentration range, and the corresponding dust cloud concentration is the most sensitive dust cloud concentration.

[0036] Step 5. Flame propagation test: keep the charge Q unchanged, and under the most sensitive dust cloud concentration condition, replace the dust sample, repeat steps 1-3, use an electric spark with an energy level higher than the minimum ignition energy of the charged dust cloud to ignite the charged dust cloud, and simultaneously start the high-speed camera 9 and the free radical spectrum collector to collect and monitor the flame propagation morphology and the free radical spectrum signal of the flame front.

[0037] Step 6. Repeat the test: Repeat the above test process 10 times, and take the average value of the minimum ignition energy and flame propagation characteristic parameters of the charged dust cloud obtained from the 10 tests as the final result.

[0038] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0039] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A device for testing the minimum ignition energy and flame propagation of charged dust clouds, characterized in that: include: A charged dust explosion chamber, comprising a support frame (3), a transparent test box (2) being fixed on the support frame (3), and a box door (1) being hinged on the top of the transparent test box (2); A corona discharge system, installed in the transparent test box (2) and used for corona discharge; An electric spark release system, installed in the transparent test box (2) and used for releasing electric sparks; An image collection system, arranged outside the transparent test box (2) and used for collecting images of explosions; A vibration dust raising system, installed at the bottom of the transparent test box (2) for raising dust; A dust charge test system, arranged outside the transparent test box (2), for measuring the charge and mass of the dust sample and calculating the dust charge-to-mass ratio; The terminal control system, the corona discharge system, the electric spark release system, the object image collection system, and the vibration dust raising system are all electrically connected to the terminal control system.

2. A device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The corona discharge system comprises a discharge plate (4), a grounding plate (5) and a DC electrostatic generator (6); The discharge plate (4) and the grounding plate (5) are respectively fixedly connected to opposite side surfaces of the inner wall of the transparent test box (2); the DC static electricity generator (6) is arranged outside the transparent test box (2) and is electrically connected to the discharge plate (4); The discharge plate (4) is provided with a plurality of pointed electrodes in an array.

3. The device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The electric spark release system comprises an electric spark discharge electrode (7) and an electric spark energy control circuit system (8); The electric spark discharge electrode (7) comprises two electrode heads with pointed ends facing each other and symmetrically fixed on two opposite side walls of the transparent test box (2), and the two electrode heads are respectively connected to the positive electrode and the negative electrode of the electric spark energy control circuit system (8); Wherein, a voltage and current monitoring submodule is provided in the electric spark energy control circuit system (8), and the voltage and current monitoring submodule is used to monitor the discharge voltage and current of the electric spark energy control circuit system (8).

4. A device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 3, characterized in that: The spark discharge electrode (7) is made of tungsten, the gap between the two spark discharge electrodes (7) is 0 mm-10 mm, the tip curvature diameter of the spark discharge electrode (7) is 2 mm, and the spark energy control circuit system (8) can release spark energy in the range of 0.1 mJ-3J, with an adjustment accuracy of 0.1 mJ.

5. The device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The image acquisition system comprises a high-speed camera (9) and a free radical spectrum acquisition device; The high-speed camera (9) is used to collect the flame morphology of the charged dust explosion in real time; The free radical spectrum collector comprises an optical fiber probe (10), a grating spectrometer (11), and an oscilloscope (12) which are connected in series in sequence. The optical fiber probe (10) is used to capture free radical spectrum signals of chemical reactions on a charged dust explosion flame front; the grating spectrometer (11) is used to collect and analyze the free radical spectrum signals acquired by the optical fiber probe (10); and the oscilloscope (12) is used to display and store the free radical spectrum signals acquired by the grating spectrometer (11).

6. The device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The vibration dust removal system comprises an insulating piston plate (13) and a servo electric cylinder (14); A sealing ring is provided on the edge of the insulating piston plate (13), and the insulating piston plate (13) is slidably connected in the transparent test box (2); The servo electric cylinder (14) is fixed to the bottom of the support frame (3), and the top end of the servo electric cylinder (14) is detachably connected to the bottom surface of the insulating piston plate (13).

7. The device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The dust charge test system comprises a Faraday cup (15), a charge meter (16), and an electronic balance (17); The Faraday cup (15) is placed on the electronic balance (17), and the charge meter (16) is electrically connected to the Faraday cup (15); The charge meter (16) is used to measure the charge q of the dust sample in the Faraday cage (15), and the electronic balance (17) is used to measure the mass m of the dust sample in the Faraday cage (15); The calculation formula of the dust charge-to-mass ratio is q / m.

8. The device for testing the minimum ignition energy and flame propagation of charged dust clouds according to claim 1, characterized in that: The terminal control system comprises a timing controller (18) and a host computer (19), and the timing controller (18) is electrically connected to the host computer (19).

9. A method for testing the minimum ignition energy and flame propagation of a charged dust cloud, based on the device for testing the minimum ignition energy and flame propagation of a charged dust cloud according to any one of claims 1 to 8, characterized in that: The steps include: S1, preset dust charging conditions, dust sample charge and dust cloud concentration, put the dust sample through the top of the transparent test box (2) to the top surface of the vibration dust system according to the preset dust cloud concentration, close the box door (1), start the vibration dust system, adjust the frequency and stroke of the vibration dust system until the maximum height of the dust just reaches the top box door (1), and continue for a certain period of time; S2, start the corona discharge system to charge the dust, intermittently suspend the dust raising and charging process, take a small amount of sample after the dust settles, put it into the dust charge test system to calculate the charge-to-mass ratio of the dust sample to be tested, determine the charge of the dust sample to be tested and compare it with the preset value, repeat the dust raising and charging process until the charge of the dust sample reaches the preset value, and turn off the vibration dust raising system and the corona discharge system; S3, start the vibration dust raising system to raise the charged dust again, and after the ignition delay period, start the electric spark release system to generate electric sparks with preset energy; S4, visually observe whether the electric spark can ignite the dust cloud, adjust the preset energy of the electric spark according to whether the ignition is successful or not, replace the dust sample and use different ignition delay periods to repeat S1-S3 until the minimum electric spark energy required to ignite the dust cloud with preset charge and concentration is obtained; change the charge of the dust sample and the concentration of the dust cloud according to the charging conditions and repeat the operation to obtain the minimum electric spark energy required to ignite the charged dust cloud with different concentrations under the preset charging conditions, and take the minimum value as the minimum ignition energy of the charged dust cloud within the test concentration range under the charging conditions; S5, under the preset dust charging condition and under the most sensitive dust cloud concentration condition with minimum ignition energy, replace the dust sample, repeat S1-S3, use the electric spark with energy level higher than the minimum ignition energy of the charged dust cloud to ignite the charged dust cloud, and start the image acquisition system to collect and monitor the flame propagation morphology and the free radical spectrum signal of the flame front at the same time as the electric spark is released; S6, repeat S1-S5 tests ten times, and take the average value of the minimum ignition energy and flame propagation characteristic parameters of the charged dust cloud obtained from the ten tests as the final result.

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