A minimum ignition energy test device
By designing a multi-system minimum ignition energy test device, the problem that existing devices cannot adjust the experimental conditions is solved, and flexible testing of flammable liquid vapor and dust mixtures is achieved, providing a safer and controllable experimental environment, reducing the Explosion accident risk.
Patent Information
- Application Number
- CN202011387133.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-12-02
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2040-12-02
AI Technical Summary
The existing minimum ignition energy test devices cannot change the test ambient temperature, pressure and dust ratio, and there are safety hazards and experimental conditions limitations when testing flammable liquid vapors and combustible dust mixtures.
A minimum ignition energy testing device including explosion chambers, heating systems, vacuum systems, gas supply systems, powder spray systems, ignition systems and data acquisition systems is designed, through which temperature, ignition time and mixture ratio can be adjusted. Provides more flexible experimental conditions and achieves low energy ignition through high voltage generators and inductors.
The explosive test of flammable liquid vapor and dust mixtures is achieved, providing a safer and controllable experimental environment, enabling the testing of minimum ignition energy at different temperatures and pressures, reducing the risk of explosion accidents.
Smart Images
Figure CN112461890B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a minimum ignition energy testing device, in particular to a minimum ignition energy testing device. Background Art
[0002] With the development of modern industry, the production and use of combustible dust is becoming more and more extensive, and the accompanying dust explosion accidents are also increasing. In the typical tobacco processing process, the tobacco drying process is to use saturated water vapor to dry tobacco. As the temperature rises, the activity of the dust increases, and a small amount of combustible gas will be released. The minimum ignition energy of the dust will become smaller, and the risk of dust explosion will increase; the flavoring process is to add various solid or liquid flavors and spices to the tobacco, and the alcohol as a solvent evaporates to form alcohol vapor and dust particles that enter the dust removal system together. The minimum ignition energy of the dust in the gas-powder mixed environment is reduced, and the risk of dust explosion increases.
[0003] In order to better prevent dust explosion accidents in industrial production, it is necessary to measure the explosion characteristic parameters of combustible dust through dust explosion test equipment, mainly including the measurement of dust explosion concentration, explosion pressure and other parameters.
[0004] The explosion hazard of combustible dust is mainly measured by the sensitivity and severity of the explosion, and correctly measuring the minimum ignition energy of the material explosion is an important means to determine the explosion sensitivity test of combustibles. The lower the minimum ignition energy of the dust, the higher the explosion sensitivity of the combustible material and the easier it is to explode. The minimum ignition energy test is affected by many factors, such as temperature, ignition time, and the concentration of combustible materials. However, existing explosion test devices mainly test combustible gas mixtures or combustible dust at ambient temperature, and cannot test the minimum ignition energy of flammable liquid vapor and combustible dust mixtures. Some devices use oil bath heating or heating plates for heating, which may pose a safety hazard. Once thermal runaway occurs, it is very easy to cause accidents and injuries.
[0005] On the other hand, the existing experimental devices for testing the minimum ignition energy mostly use the Hartmann tube test device in which the ignition energy is controlled by electrodes. The test conditions such as the ambient temperature and pressure cannot be changed. The Hartmann tube is a semi-open structure and cannot be effectively sealed. Its pressure bearing capacity is limited, so the test conditions are greatly restricted. Summary of the invention
[0006] The purpose of the present invention is to overcome the problem in the prior art that the test conditions such as the ambient temperature, pressure, steam and dust ratio cannot be changed, and a minimum ignition energy test device is provided.
[0007] The purpose of the present invention is achieved through the following technical scheme: a minimum ignition energy testing device, comprising an explosion cavity, a heating system, a vacuum system, an air supply system, a powder spraying system, an ignition system, a data acquisition system, a controller and a sampling system, wherein the heating system, the vacuum system, the air supply system, the powder spraying system, the ignition system, the data acquisition system and the sampling system are all connected to the explosion cavity, the heating system and the powder spraying system are both connected to the controller, and the ignition system, the air supply system and the powder spraying system are all connected to the data acquisition system.
[0008] A better choice is that the heating system includes a water inlet pipe, a water outlet pipe, a heater, a water pump, a thermocouple, and a water storage container, the water inlet end of the water inlet pipe is connected to the water storage container, the water outlet end of the water inlet pipe is connected to the water inlet of the insulation layer, the water pump is installed on the water inlet pipe, the water inlet end of the water outlet pipe is connected to the water outlet of the insulation layer, the drain outlet of the water outlet pipe is connected to the water storage container, the heater and the thermocouple are both installed in the water storage container, and the heater and the thermocouple are both connected to a controller.
[0009] A better choice, the powder spraying system includes an electric heating tape, a first temperature sensor, a second pressure gauge, a second solenoid valve, a third solenoid valve, a second gas cylinder and a powder bin, the first temperature sensor is installed on the inner wall of the powder bin, the electric heating tape is installed on the outer surface of the powder bin, the electric heating tape and the first temperature sensor are both connected to the controller, the second gas cylinder is connected to the powder bin through the third solenoid valve, the powder bin is connected to the explosion cavity through the second solenoid valve, the second pressure gauge is installed in the powder bin, and the second solenoid valve, the third solenoid valve and the second pressure gauge are all connected to the data acquisition system.
[0010] A better choice is that the vacuum system includes a vacuum pump, a vacuum tube, a first manual valve, a second manual valve, a third manual valve, a fourth manual valve, a fifth manual valve, a micro-differential pressure gauge and a first pressure gauge. The vacuum pump, the first manual valve, the vacuum tube, the second manual valve and the explosion chamber are connected in sequence. The first pressure gauge is installed on the vacuum tube through the third manual valve, the low-pressure end of the micro-differential pressure gauge is installed on the vacuum tube through the fourth manual valve, and the high-pressure end of the micro-differential pressure gauge is installed on the vacuum tube through the fifth manual valve.
[0011] A more preferred option is that the injection system includes a sixth manual valve, a transition chamber and a seventh manual valve connected in sequence, and the seventh manual valve is connected to the explosion chamber.
[0012] A more preferred option is that the gas supply system includes a first gas cylinder and a first solenoid valve, the first gas cylinder is connected to the explosion cavity through the first solenoid valve, and the first solenoid valve is connected to the data acquisition system.
[0013] A better choice is that the explosion chamber includes a sealing cover, a reactor, a diffuser, an electrode, an injection tube and an insulation layer, the sealing cover is installed on the top of the reactor, the electrode and the injection tube are both installed on the sealing cover, the electrode is connected to the ignition system, the injection tube is connected to the injection system, the diffuser is installed at the bottom of the reactor, the diffuser is connected to the powder spraying system, the insulation layer is installed on the outer surface of the reactor, the insulation layer is connected to the heating system, and the vacuum system, gas supply system and data acquisition system are all connected to the reactor.
[0014] A better choice is that the ignition system includes a high-voltage generator, a storage capacitor, a parasitic capacitor, a high-voltage relay and an inductor, the high-voltage relay is provided with a first terminal, a second terminal and a third terminal, the positive terminal of the high-voltage generator is connected to the first terminal, the third terminal is connected to the positive electrode of the storage capacitor, the positive electrode of the parasitic capacitor and an electrode of an explosion cavity are both connected to the second terminal, the other electrode of the explosion cavity is connected to the negative terminal of the high-voltage generator through the inductor, the negative electrode of the storage capacitor and the negative electrode of the parasitic capacitor are both connected to the negative terminal of the high-voltage generator, and the high-voltage relay is connected to the data acquisition system.
[0015] A better option is that the data acquisition system includes a second temperature sensor, a third temperature sensor, an explosion pressure sensor and a computer, the second temperature sensor, the third temperature sensor and the explosion pressure sensor are all installed in the explosion cavity, the second temperature sensor, the third temperature sensor and the explosion pressure sensor are all connected to the computer, and the powder spraying system, the air supply system and the ignition system are all connected to the computer.
[0016] A more preferred option is that the bottom of the explosion cavity also includes an exhaust port and an eighth manual valve, the exhaust port is located at the bottom of the explosion cavity, and the exhaust port is connected to the eighth manual valve.
[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0018] 1. The present invention can perform tests on different temperatures, ignition times, ignition energies and mixture (flammable liquid vapor and dust) ratios through an explosion chamber, a heating system, a vacuum system, an air supply system, a powder spraying system, an ignition system, a data acquisition system, a controller and a sampling system, and obtain the explosion parameters of the sample by collecting data, thereby providing a basis for preventing dust explosion accidents in industrial production.
[0019] 2. The present invention uses the sixth manual valve, transition chamber and seventh manual valve of the sampling system to enable the device to complete the sampling of flammable liquids, generate flammable liquid vapor, and form a mixture with dust for explosiveness testing in a test environment that does not affect the air pressure.
[0020] 3. The present invention calculates the amount of liquid vaporization through the vacuum pump, vacuum tube, first manual valve, second manual valve, third manual valve, fourth manual valve, fifth manual valve and micro-differential pressure gauge of the vacuum system. By pumping the environment to negative pressure, the flammable liquid is sampled and then sucked through the negative pressure environment of the explosion chamber and instantly vaporized. The method calculates the volume of flammable liquid vapor in the explosion chamber through changes in the micro-differential pressure gauge, thereby solving the problem of liquid sampling. At the same time, different ratios of flammable vapor and dust mixture can also be configured, making the explosiveness test of the liquid vapor and dust mixture more reasonable.
[0021] 4. The present invention controls the internal ambient temperature of the explosion cavity through a heating system including a water inlet pipe, a water outlet pipe, a heater, a water pump, a thermocouple, and a water storage container, so as to adjust the experimental temperature of the explosive test. The installation of an insulation layer can maintain the set ambient temperature stably and is safer and more controllable than oil bath heating.
[0022] 5. The present invention includes an ignition system including a high-voltage generator, a storage capacitor, a parasitic capacitor, a high-voltage relay and an inductor. The high-voltage generator is used to charge the storage capacitor. After the voltage reaches a certain level, the high-voltage relay is controlled to discharge. The generated electric spark provides an ignition source for the explosive test, thereby achieving the control of low-energy ignition energy of 1mJ-2000mJ. The high-voltage relay can control the ignition delay time of the gas-powder mixture test, and can simulate the influence of different delay times on the minimum ignition energy of the gas-powder mixture. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of a minimum ignition energy testing device of the present invention;
[0024] Figure 2 It is a schematic diagram of an explosion chamber, a sampling system and a data acquisition system of a minimum ignition energy testing device of the present invention;
[0025] Figure 3 It is a schematic diagram of a heating system of a minimum ignition energy testing device of the present invention;
[0026] Figure 4 It is a schematic diagram of an ignition system of a minimum ignition energy testing device of the present invention;
[0027] Figure 5 It is a schematic diagram of a powder spraying system of a minimum ignition energy testing device of the present invention;
[0028] Figure 6 It is a schematic diagram of vacuuming a minimum ignition energy testing device of the present invention;
[0029] The markings of the components in the attached drawings are as follows: 1. Explosion chamber; 10. Reactor; 11. Diffuser; 12. Water inlet; 13. Water outlet; 14. Exhaust port; 141. Eighth manual valve; 15. Air inlet; 16. Air extraction port; 17. Powder inlet; 18. Sample loading port; 19. Sealing cover; 2. Heating system; 20. Water storage container; 21. Water inlet pipe; 22. Heater; 23. Insulation layer; 24. Water pump; 25. Thermocouple; 26. Water outlet pipe; 3. Vacuum system; 30. Micro differential pressure gauge; 31. First pressure gauge; 32. Vacuum pump; 33. First manual valve; 34. Second manual valve; 35. Third manual valve; 36. Fourth manual valve; 37. Fifth manual valve; 38. Filter; 4. Air supply system; 40, the first gas cylinder; 41, the first solenoid valve; 5, the powder spraying system; 50, the second gas cylinder; 51, the powder bin; 52, the second pressure gauge; 53, the first temperature sensor; 54, the gas pipe; 55, the second solenoid valve; 56, the third solenoid valve; 57, the electric heating belt; 6, the ignition system; 60, the electrode; 61, the storage capacitor; 62, the parasitic capacitor; 63, the high-voltage relay; 64, the inductor; 65, the high-voltage generator; 7, the data acquisition system; 70, the computer; 71, the second temperature sensor; 72, the third temperature sensor; 73, the explosion pressure sensor; 8, the sampling system; 80, the sampling tube; 81, the sixth manual valve; 82, the seventh manual valve; 83, the transition chamber; 9, the controller. DETAILED DESCRIPTION
[0030] The purpose of the present invention is further described in detail below with reference to the accompanying drawings and specific examples. The examples cannot be described one by one here, but the implementation methods of the present invention are not therefore limited to the following examples.
[0031] Embodiment 1
[0032] like Figure 1As shown, a minimum ignition energy testing device includes an explosion chamber 1, a heating system 2, a vacuum system 3, an air supply system 4, a powder spraying system 5, an ignition system 6, a data acquisition system 7, a controller 9 and a sampling system 8. The water outlet pipe 26 and the water inlet pipe 21 of the heating system 2 are both connected to the insulation layer 23 of the explosion chamber 1, the second manual valve 34 of the vacuum system 3 is connected to the air suction port 16 of the explosion chamber 1, the first solenoid valve 41 of the air supply system 4 is connected to the air inlet 15 of the explosion chamber 1, the second solenoid valve 55 of the powder spraying system 5 is connected to the powder inlet 17 of the explosion chamber 1, the ignition system 6 is connected to the electrode 60 of the explosion chamber 1, the second temperature sensor 71, the third temperature sensor 72 and the explosion pressure sensor 73 of the data acquisition system 7 are all connected to the explosion chamber 1, and the seventh manual valve 82 of the sampling system 8 is connected to the sampling tube 80 of the explosion chamber 1. The thermocouple 25 and the heater 22 of the heating system 2 are connected to the controller 9, the first temperature sensor 53 and the electric heating cable 57 of the powder spraying system 5 are connected to the controller 9, the first solenoid valve 41 of the air supply system 4 is connected to the computer 70 of the data acquisition system 7, and the second solenoid valve 55 and the third solenoid valve 56 of the powder spraying system 5 are connected to the computer 70 of the data acquisition system 7. An exhaust port 14 is also provided at the bottom of the explosion cavity 1, and the exhaust port 14 is connected to the eighth manual valve 141.
[0033] The explosion chamber 1 is used for the explosion reaction of dust and flammable liquid vapor; the heating system 2 provides the explosion chamber 1 with a suitable reaction environment temperature; the vacuum system 3 vacuumizes the reactor 10 to vaporize the liquid sample; the powder spraying system 5 supplies gas to the powder bin 51 through the third electromagnetic valve 56, and the second gas cylinder 50 adjusts the gas supply speed of the gas pipe 54 according to the experimental needs to achieve the inner cavity pressure of the powder bin 51 to reach 2MPa, and then controls the second electromagnetic valve 55 to operate through the computer 70, and the sample is sprayed into the explosion chamber 1; the ignition system 6 provides appropriate ignition energy for the electrode 60; the data acquisition system 7 collects the pressure and temperature data during the explosion process, and can control the ignition of the ignition system 6, the powder spraying system 5 and the gas supply system 4; the controller 9 is a PLC controller 9, which can control the temperature of the circulating water and the temperature of the powder bin 51; the sample injection system 8 realizes liquid dripping and sealing through two valve switches. The exhaust port 14 is used to remove dust and debris after the test. The gas supply system 4 is used to adjust the inner cavity gas pressure of the reactor 10 to meet the environmental requirements of the reaction.
[0034] The explosion chamber 1 includes a sealing cover 19, a reactor 10, a diffuser 11, an electrode 60, an injection tube 80 and an insulation layer 23. The sealing cover 19 is installed on the top of the reactor 10, the injection tube 80 is installed on the sealing cover through the sample loading port 18, two electrodes 60 are installed on both sides of the injection tube 80, the electrode 60 is connected to the ignition system 6 through a wire, the injection tube 80 is connected to the seventh manual valve 82 of the injection system 8, the diffuser 11 is installed on the bottom of the reactor 10 through a thread, the diffuser 11 is connected to the powder spraying system 5 through the powder inlet 17, the insulation layer 23 is installed on the outer surface of the reactor 10, the water inlet and the water outlet of the insulation layer 23 are both connected to the heating system 2, the second manual valve 34 of the vacuum system 3 is connected to the reactor 10, and the second temperature sensor 71, the third temperature sensor 72 and the explosion pressure sensor 73 of the data acquisition system 7 are all connected to the reactor 10 of the explosion chamber 1.
[0035] The reactor 10 has a capacity of 20L and is used for explosion reactions of liquid vapor and dust mixtures; the sealing cover 19 is used to fix the sampling tube 80 and the electrode 60 to ensure that the reactor 10 is in a sealed state; the diffuser 11 allows the dust to be dispersed throughout the inner cavity of the reactor 10; the electrode 60 is used to ignite the dust and liquid vapor in the reactor 10; the sampling tube 80 is used to connect the sampling system 8 to deliver the sample from the outside to the inside of the reactor 10; the insulation layer 23 is made of pipes and insulation cotton, the insulation cotton wraps the outer surface of the reactor 10 to form a spherical structure, the pipe is embedded in the insulation cotton, and the pipe is connected to the external heating system 2 to keep the reactor 10 warm and allow circulating water to flow through the entire surface of the reactor 10.
[0036] The data acquisition system 7 includes a second temperature sensor 71, a third temperature sensor 72, an explosion pressure sensor 73 and a computer 70. The second temperature sensor 71 of the data acquisition system 7 is installed on the ball wall of the reactor 10, the third temperature sensor 72 of the data acquisition system 7 extends into the interior of the reactor 10, and the explosion pressure sensor 73 of the data acquisition system 7 extends into the interior of the reactor 10. The first temperature sensor 53, the second temperature sensor 71, the third temperature sensor 72, the second pressure gauge 52 and the explosion pressure sensor 73 are all connected to the computer 70, and the first solenoid valve 41 of the air supply system 4, the second solenoid valve 55 of the powder spraying system 5, the third solenoid valve 56 of the powder spraying system 5 and the high-voltage relay 63 of the ignition system 6 are all connected to the computer 70.
[0037] The first temperature sensor 53 collects temperature data of the powder bin surface; the second temperature sensor 71 collects temperature data of the outer surface of the reactor 10; the third temperature sensor 72 collects temperature data inside the reactor 10; the explosion pressure sensor 73 collects pressure data of the explosion inside the reactor 10; the computer 70 stores a program for storing explosion pressure data and temperature data of the reactor 10, and can also control the ignition system 6, the air supply system 4 and the powder spraying system 5.
[0038] The heating system 2 includes an inlet pipe 21, an outlet pipe 26, a heater 22, a water pump 24, a thermocouple 25, and a water storage container 20. The water inlet end of the inlet pipe 21 is connected to the water storage container 20, the water outlet end of the inlet pipe 21 is connected to the water inlet 12 of the insulation layer 23, the water pump 24 is installed on the inlet pipe 21, the water inlet end of the outlet pipe 26 is connected to the water outlet 13 of the insulation layer 23, the drainage end of the outlet pipe 26 is connected to the water storage container 20, the heater 22 and the thermocouple 25 are both installed on the water storage container 20, and the heater 22 and the thermocouple 25 are both connected to the controller 9.
[0039] The water inlet pipe 21 and the water outlet pipe 26 are connected to the insulation layer 23 of the explosion cavity 1, and convey circulating water to the insulation layer 23; the heater 22 is used to heat the circulating water; the water pump 24 is used to provide power for the circulating water; the thermocouple 25 is used to measure the temperature of the circulating water and feed it back to the controller 9; the water storage container 20 is used to store the circulating water.
[0040] The powder spraying system 5 includes an electric heating tape 57, a first temperature sensor 53, a second pressure gauge 52, an air pipe 54, a second solenoid valve 55, a third solenoid valve 56, a second gas cylinder 50 and a powder bin 51. The first temperature sensor 53 is installed on the inner wall of the powder bin 51, the electric heating tape 57 is installed on the outer surface of the powder bin 51, the electric heating tape 57 and the first temperature sensor 53 are both connected to the controller 9, the second gas cylinder 50 is connected to the powder bin 51 through the air pipe 54, the third solenoid valve 56 is installed on the air pipe 54, the powder bin 51 is connected to one end of the second solenoid valve 55, and the other end of the second solenoid valve 55 is connected to the diffuser 11 of the explosion cavity 1 through the powder inlet 17, the second pressure gauge 52 is installed on the powder bin 51, and the second solenoid valve 55, the third solenoid valve 56 and the second pressure gauge 52 are all connected to the computer 70 of the data acquisition system 7.
[0041] The electric heating tape 57 is used to heat the dust in the powder bin 51; the first temperature sensor 53 is used to measure the temperature of the dust and feed it back to the controller 9, and then give instructions to the electric heating tape 57 to control the heating; the second pressure gauge 52 is used to monitor the pressure data in the powder bin 51 and transmit it to the computer 70; the second solenoid valve 55 controls whether the dust enters the reactor 10; the third solenoid valve 56 controls whether the second gas cylinder 50 inflates the powder bin 51; the computer 70 can control the opening or closing of the second solenoid valve 55 and the third solenoid valve 56 through instructions; the second gas cylinder 50 is used to store gas; the powder bin 51 is used to store dust and mix dust and air.
[0042] The vacuum system 3 includes a vacuum pump 32, a vacuum tube, a first manual valve 33, a second manual valve 34, a third manual valve 35, a fourth manual valve 36, a fifth manual valve 37, a micro-differential pressure gauge 30, a filter 38 and a first pressure gauge 31. The vacuum pump 32, the filter 38, the first manual valve 33, the vacuum tube, the second manual valve 34 and the air extraction port 16 of the explosion chamber 1 are connected in sequence. The first pressure gauge 31 is installed on the vacuum tube through the third manual valve 35. The low-pressure end of the micro-differential pressure gauge 30 is installed on the vacuum tube through the fourth manual valve 36. The high-pressure end of the micro-differential pressure gauge 30 is installed on the vacuum tube through the fifth manual valve 37. The micro-differential pressure gauge 30 is located on the left side of the first air pressure gauge 31.
[0043] The vacuum pump 32 is used as the vacuum source of the vacuum pumping system 3; the vacuum tube is used to deliver vacuum; the first manual valve 33 is used to control the connection or closing of the vacuum tube and the vacuum pump, and the second manual valve 34 is used to control the connection or closing of the reactor 10 and the vacuum tube; the third manual valve 35 is used to control the connection or closing of the first pressure gauge 31 and the reactor 10; the fourth manual valve 36 is the low-pressure valve of the micro-differential pressure gauge 30, which is used to control the connection or closing of the low-pressure end of the micro-differential pressure gauge 30 and the vacuum tube; the fifth manual valve 37 is the high-pressure valve of the micro-differential pressure gauge 30, which is used to control the high-pressure end of the micro-differential pressure gauge 30. Connected or closed with the vacuum tube; the micro differential pressure gauge 30 is used to measure the pressure difference change inside the reactor 10 of the explosion cavity 1, and the volume of the space occupied by the liquid in the cavity evaporated into gas is determined according to the pressure difference change, so as to determine the ratio of the flammable liquid vapor and dust mixture; the range of the micro differential pressure gauge 30 is divided into 1500Pa or 3000Pa, and the micro differential pressure gauge 30 of different ranges can be replaced according to the saturated vapor pressure of the liquid and the explosion limit of the liquid vapor to meet the needs; the first pressure gauge 31 is used to measure the internal pressure change of the explosion cavity 1; the filter 38 is used to remove impurities from the extracted air.
[0044] The ignition system 6 includes a high-voltage generator 65, a storage capacitor 61, a parasitic capacitor 62, a high-voltage relay 63 and an inductor 64. The high-voltage relay 63 is provided with a first terminal, a second terminal and a third terminal. The positive terminal of the high-voltage generator 65 is connected to the first terminal, the third terminal is connected to the positive electrode of the storage capacitor 61, the positive electrode of the parasitic capacitor 62 and one electrode 60 are both connected to the second terminal, the other electrode 60 is connected to the negative terminal of the high-voltage generator 65 through the inductor 64, the negative electrode of the storage capacitor 61 and the negative electrode of the parasitic capacitor 62 are both connected to the negative terminal of the high-voltage generator 65, and the high-voltage relay 63 is connected to the data acquisition system 7.
[0045] The high voltage generator 65 converts the AC voltage into a high voltage DC voltage; the storage capacitor 61 is used to store the voltage; the parasitic capacitor 62 is a suppression capacitor used to smooth the capacitance of the external cable; the high voltage relay 63 is used as an ignition switch and is controlled by the program of the computer 70; the function of the inductor 64 is to extend the discharge time. By controlling the high voltage relay 63, the charging voltage charges the storage capacitor 61. After the charging is completed, the high voltage relay 63 is controlled by the computer 70 to discharge the connected discharge voltage, and the adjustable time discharge of the electrodes 60 at both ends is realized through the inductor 64. The ignition energy is released by discharge, and the ignition energy can be controlled to be between 1mJ and 2000mJ.
[0046] The injection system 8 includes a sixth manual valve 81, a transition chamber 83 and a seventh manual valve 82 which are connected in sequence. The seventh manual valve 82 is connected to the injection tube 80, and the injection tube 80 is installed on the sealing cover 19 through the sample loading port 18. The function of the sixth manual valve 81 is to connect or close the outside with the transition chamber 83 and send the sample into the transition chamber 83; the function of the transition chamber 83 is to store a small amount of sample and measure the injection volume; the function of the seventh manual valve 82 is to connect or close the transition chamber 83 with the reactor 10, and the injection system 8 can send the sample into the reactor 10 under the condition of isolating the outside gas.
[0047] The gas supply system 4 includes a first gas cylinder 40 and a first solenoid valve 41. The first gas cylinder 40 is connected to the reactor 10 of the explosion chamber 1 through the first solenoid valve 41, and the first solenoid valve 41 is connected to the computer 70 of the data acquisition system 7. The first gas cylinder 40 provides air to the inside of the reactor 10, and the first solenoid valve 41 is used to control the air to enter the reactor 10.
[0048] The saturated vapor pressure of ethanol at different ambient temperatures is used to determine the amount of liquid vaporization. The reactor 10 is evacuated to a vacuum for multiple times and the liquid sample is dripped in. The liquid sample is instantly vaporized after being sucked into the negative pressure environment of the explosion chamber 1. The amount of liquid evaporation is determined by observing the reading of the micro-pressure differential gauge 30. This solves the problem of configuring the ratio of ethanol vapor and tobacco dust mixtures of different concentrations and fully mixing them, making the explosiveness test of the flammable vapor and dust mixture more reasonable.
[0049] Set the explosion reaction temperature T 1 =50°C, observe the temperature T of the circulating water in the water storage container 20 3 = 25℃, using the formula PV = nRT, calculate the temperature T of the powder bin 51 2 =70°C, use the controller 9 to heat the powder bin to 70°C; close the seventh manual valve 82, open the sixth manual valve 81 of the sample delivery system, inject 2mL of ethanol liquid into the transition bin 83, and close the sixth manual valve 81; open the first manual valve 33 and the second manual valve 34, close the third manual valve 35, the fourth manual valve 36, the fifth manual valve 37, the sixth manual valve 81 and the seventh manual valve 82, turn on the vacuum pump 32, evacuate the reactor 10, open the third manual valve 35, observe the reading of the first pressure gauge 31, and determine the reaction After the pressure in the reactor 10 reaches below -0.09MPa, the vacuum pump 32 is turned off, and then the seventh manual valve 82 is opened to suck the liquid through the negative pressure inside the reactor 10, and the liquid is instantly evaporated into ethanol vapor. The ethanol vapor pressure in the reactor 10 is recorded by the scale calibration of the transition chamber and the micro-pressure difference meter 30, and the above steps are repeated for many times. It is observed that 0.04mL of ethanol liquid needs to be added to reach the lower explosion limit of 5% of ethanol, and 0.5mL of ethanol liquid needs to be added to reach the lower explosion limit of 10% of ethanol, and the experimental data are recorded. The mixed air is introduced for many times through the air supply system 4 to clean the ethanol vapor in the reactor 10.
[0050] Embodiment 2
[0051] (1) Preparation before explosion
[0052] Take 500g / m 3Tobacco dust sample, open the powder bin 51, load the sample, and close the spiral hatch of the powder bin 51; make sure that the electrode 60 on the sealing cover 19 is connected to the ignition system 6, close the top cover and tighten it. Close the seventh manual valve 82, open the sixth manual valve 81 at the liquid injection port, inject 2 mL of sample into the transition chamber 83, and close the sixth manual valve 81; open the first manual valve 33 and the second manual valve 34, close the third manual valve 35, the fourth manual valve 36, and the fifth manual valve 37, open the vacuum pump 32, evacuate the reactor 10, open the third manual valve 35, observe the reading of the first pressure gauge 31, and close the vacuum pump 32 and the first manual valve 33 after confirming that the pressure in the reactor 10 reaches -0.094 MPa; open the fourth manual valve 36 and the fifth manual valve 37, and after the pointer of the micro-pressure differential gauge 30 stabilizes, close the fourth manual valve 36, slowly open the seventh manual valve 82, and allow the sample to slowly enter. When 0.04 mL of sample flows into the transition chamber, close the seventh manual valve 82, and the liquid is sucked into the reactor 10 by the negative pressure inside. It evaporates into liquid vapor instantly, and the amount of ethanol vapor in the explosion cavity 1 is determined to be 5% of the volume of the lower explosion limit of ethanol through the micro-pressure differential meter 30, and the fourth manual valve 36 and the fifth manual valve 37 are closed; the air mixed gas is then filled into the explosion cavity 1 through the air supply system 4 until the reading of the first pressure gauge 31 shows 0.06MPa, and the second manual valve 34 is closed; the program of the computer 70 sets the minimum ignition energy to 500mJ, and adjusts the vacuum high-voltage relay 63 to charge the voltage, and sets the ignition time on the high-voltage relay 63 in the program of the computer 70, and uses the power supply discharge to charge the storage capacitor 61, and then discharges it after reaching the voltage, and the formed electric spark provides an ignition source for the explosive test, which can overcome the weakness of the Hartmann tube in withstanding the small explosion pressure, and enables the device to achieve the control of low-energy ignition energy of 1mJ-2000mJ.
[0053] (2) Conducting an explosion experiment: The second solenoid valve 55 is opened by the computer 70 of the data acquisition system 7 to spray powder, and the high-voltage relay 63 is controlled by the computer 70 to ignite the explosion. The pressure and temperature changes in the reactor 10 are monitored in real time by the explosion pressure sensor 73, the second temperature sensor 71 and the third temperature sensor 72 and transmitted to the computer 70 for subsequent calculations.
[0054] (3) Cleaning after the explosion: After the explosion is over, open the eighth manual valve 141, open the outlet of the ram gas cylinder, flush the dust in the powder bin 51 and the bottom of the diffusion valve of the air pipe 54 into the reactor 10, open the sealing cover 19, extend the suction port of the vacuum cleaner into the reactor 10, and suck out the suspended dust in the reactor 10 and the light dust on the inner wall of the reactor 10. After removing the disperser from the reactor 10, use a vacuum cleaner and / or a brush to remove the dust / explosion residue in the dead corner between the disperser body and the dispersion block.
[0055] 4) Open all valves and install all components, reset the dust concentration, ethanol liquid volume, explosion chamber 1 temperature, ignition delay time, ignition energy, etc., and prepare for the next experiment.
[0056] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.
Claims
1. A minimum ignition energy test device, characterized in that: It includes an explosion cavity, a heating system, a vacuum system, an air supply system, a powder spraying system, an ignition system, a data acquisition system, a controller and a sampling system. The heating system, the vacuum system, the air supply system, the powder spraying system, the ignition system, the data acquisition system and the sampling system are all connected to the explosion cavity, the heating system and the powder spraying system are all connected to the controller, and the ignition system, the air supply system and the powder spraying system are all connected to the data acquisition system; The vacuum system comprises a vacuum pump, a vacuum tube, a first manual valve, a second manual valve, a third manual valve, a fourth manual valve, a fifth manual valve, a micro differential pressure gauge and a first pressure gauge, wherein the vacuum pump, the first manual valve, the vacuum tube, the second manual valve and the explosion chamber are connected in sequence, the first pressure gauge is installed on the vacuum tube through the third manual valve, the low pressure end of the micro differential pressure gauge is installed on the vacuum tube through the fourth manual valve, and the high pressure end of the micro differential pressure gauge is installed on the vacuum tube through the fifth manual valve; A testing method for a minimum ignition energy testing device comprises the following steps: S1. Put the dust into the powder bin and close the powder bin; S2. Close the seventh manual valve, open the sixth manual valve, inject 2 mL of flammable liquid into the transition chamber, and close the sixth manual valve; S3, open the first manual valve and the second manual valve, close the third manual valve, the fourth manual valve, and the fifth manual valve, and evacuate the reactor with a vacuum pump until the pressure in the reactor reaches -0.094 MPa; S4, open the fourth manual valve and the fifth manual valve, after the pointer of the micro-pressure differential gauge is stable, close the fourth manual valve, slowly open the seventh manual valve, so that the flammable liquid slowly enters the transition chamber, when 0.04mL of flammable liquid flows into the transition chamber, close the seventh manual valve, the flammable liquid is sucked into the negative pressure inside the reactor and instantly evaporates into flammable liquid vapor, the amount of flammable liquid vapor in the explosion cavity is determined by the micro-pressure differential gauge to be 5% of the volume of the lower explosion limit of the flammable liquid, and close the fourth manual valve and the fifth manual valve; S5. Fill the air mixture through the air supply system until the reading of the first pressure gauge shows 0.06MPa, and then close the second manual valve; set the value of the minimum ignition energy through the computer, and adjust the vacuum high-voltage relay to charge the voltage, set the ignition time of the high-voltage relay through the computer, use the power discharge to charge the storage capacitor, and then discharge it after reaching the voltage, and the generated electric spark provides an ignition source for the explosive test; S6. Open the second solenoid valve through the computer to spray powder, control the high-voltage relay through the computer to ignite the explosion, and monitor the pressure and temperature changes in the reactor in real time through the explosion pressure sensor, the second temperature sensor and the third temperature sensor and transmit them to the computer.
2. A minimum ignition energy testing device according to claim 1, characterized in that: The heating system includes a water inlet pipe, a water outlet pipe, a heater, a water pump, a thermocouple, and a water storage container. The water inlet end of the water inlet pipe is connected to the water storage container, the water outlet end of the water inlet pipe is connected to the water inlet of the insulation layer, the water pump is installed on the water inlet pipe, the water inlet end of the water outlet pipe is connected to the water outlet of the insulation layer, the drain outlet of the water outlet pipe is connected to the water storage container, the heater and the thermocouple are both installed in the water storage container, and the heater and the thermocouple are both connected to a controller.
3. A minimum ignition energy testing device according to claim 1, characterized in that: The powder spraying system includes an electric heating tape, a first temperature sensor, a second pressure gauge, a second solenoid valve, a third solenoid valve, a second gas cylinder and a powder bin. The first temperature sensor is installed on the inner wall of the powder bin, the electric heating tape is installed on the outer surface of the powder bin, the electric heating tape and the first temperature sensor are both connected to a controller, the second gas cylinder is connected to the powder bin through the third solenoid valve, the powder bin is connected to the explosion cavity through the second solenoid valve, the second pressure gauge is installed in the powder bin, and the second solenoid valve, the third solenoid valve and the second pressure gauge are all connected to a data acquisition system.
4. A minimum ignition energy testing device according to claim 1, characterized in that: The sample injection system comprises a sixth manual valve, a transition chamber and a seventh manual valve which are connected in sequence, and the seventh manual valve is connected to the explosion cavity.
5. A minimum ignition energy testing device according to claim 1, characterized in that: The gas supply system includes a first gas cylinder and a first solenoid valve, the first gas cylinder is connected to the explosion cavity through the first solenoid valve, and the first solenoid valve is connected to the data acquisition system.
6. A minimum ignition energy testing device according to claim 1, characterized in that: The explosion chamber includes a sealing cover, a reactor, a diffuser, an electrode, an injection tube and an insulation layer. The sealing cover is installed on the top of the reactor, the electrode and the injection tube are both installed on the sealing cover, the electrode is connected to the ignition system, the injection tube is connected to the injection system, the diffuser is installed at the bottom of the reactor, the diffuser is connected to the powder spraying system, the insulation layer is installed on the outer surface of the reactor, the insulation layer is connected to the heating system, and the vacuum system, gas supply system and data acquisition system are all connected to the reactor.
7. A minimum ignition energy testing device according to claim 1, characterized in that: The ignition system includes a high-voltage generator, a storage capacitor, a parasitic capacitor, a high-voltage relay and an inductor. The high-voltage relay is provided with a first terminal, a second terminal and a third terminal. The positive terminal of the high-voltage generator is connected to the first terminal, the third terminal is connected to the positive electrode of the storage capacitor, the positive electrode of the parasitic capacitor and an electrode of an explosion cavity are both connected to the second terminal, the other electrode of the explosion cavity is connected to the negative terminal of the high-voltage generator through the inductor, the negative electrode of the storage capacitor and the negative electrode of the parasitic capacitor are both connected to the negative terminal of the high-voltage generator, and the high-voltage relay is connected to the data acquisition system.
8. A minimum ignition energy testing device according to claim 1, characterized in that: The data acquisition system includes a second temperature sensor, a third temperature sensor, an explosion pressure sensor and a computer. The second temperature sensor, the third temperature sensor and the explosion pressure sensor are all installed in the explosion cavity. The second temperature sensor, the third temperature sensor and the explosion pressure sensor are all connected to the computer. The powder spraying system, the air supply system and the ignition system are all connected to the computer.
9. A minimum ignition energy testing device according to claim 1, characterized in that: The bottom of the explosion cavity also includes an exhaust port and an eighth manual valve. The exhaust port is located at the bottom of the explosion cavity, and the exhaust port is connected to the eighth manual valve.