Detection method for determining metal dust explosion based on coupling of emission spectrum and explosion pressure

Abstract

The invention discloses a detection method for determining metal dust explosion based on emission spectrum and explosion pressure coupling, and relates to the technical field of metal dust explosion testing. The method comprises the following steps: firstly, installing a required experiment system; measuring the median particle size of a to-be-measured metal dust sample, drying the to-be-measured metal dust sample, putting the to-be-measured metal dust sample into a powder spraying system after drying, vacuumizing the experimental tank body, and spraying the metal dust sample into the vacuumized experimental tank body through the powder spraying system to form a metal dust cloud; the ignition system is used for ignition, so that the metal dust cloud explodes; recording and analyzing experimental data through a fiber optic spectrometer, a temperature detection system and a data acquisition system to obtain a characteristic spectrum of explosion flames at the initial stage of explosion and a time-varying curve of explosion pressure; and finally, calculating an explosion detection index F at the initial stage of metal dust explosion by virtue of a formula. According to the method, metal dust explosion can be more accurately detected.

Description

Technical Field

[0001] The present invention relates to the technical field of metal dust explosion testing, and particularly to a method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure. Background Art

[0002] Metals are widely used, but the harm caused by their dust explosions is extremely great. Aluminum powder, magnesium powder, and aluminum-magnesium alloy dust are listed in the hazardous chemicals list due to their flammable and explosive characteristics. In the past, many metal dust explosion accidents have caused serious casualties and property losses.

[0003] The main research reports on the detection of metal dust hazards are as follows:

[0004] Application No. 201911410966.1 discloses a test device and evaluation method for the spontaneous ignition hazard of metal dust when wet. The test device mainly includes a control system, a monitoring system, a constant temperature water tank, and a work cabinet. The monitoring system includes an oxygen monitoring device, a hydrogen monitoring device, a humidity detection device, and a liquid level monitoring device that are electrically connected to the control system and are respectively installed inside the work cabinet. The work cabinet is set as an electrical cabinet structure with the monitoring system and the control system installed inside for experimental work, and a bearing plate, a test water tank, a waste liquid tank, and a test container are also installed inside. The control system mainly includes a PLC controller, a touch screen, and a temperature sensor. The constant temperature water tank is connected to the test water tank through a heat preservation pipe. This prior art obtains the critical conditions for the spontaneous ignition of dust when wet by adjusting the temperature, humidity, and oxygen content inside the device to determine the dangerous characteristics of the dust's spontaneous ignition when wet.

[0005] "Metal dust concentration detection technology based on charge induction method" disclosed by Zhao Zheng et al. studied the basic principle of metal dust concentration detection technology based on charge induction method based on the electrostatic characteristics of metal dust, designed the detection mechanism and method of charge induction method, and completed the design of the weak charge signal extraction circuit and early warning function. This technology can be applied to the real-time continuous long-term online detection of metal dust.

[0006] The above-mentioned prior arts mainly studied the spontaneous combustion and concentration of metal dust, but did not involve the research on the explosion of metal dust when encountering a fire source. However, dust is extremely likely to cause an explosion when mixed with air and encountering a fire source. These accidents mostly occur in the production, storage, and processing links. Therefore, it is of great significance to detect the occurrence of metal dust explosion in a timely and accurate manner. Summary of the Invention

[0007] The object of the present invention is to provide a method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure. By directly substituting parameters such as the characteristic spectrum of the metal dust explosion flame and the explosion pressure into a formula to obtain an explosion detection index F, the explosion of metal dust can be detected. The method of the present invention can detect the explosion of metal dust more accurately.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure successively includes the following steps:

[0010] a. Install the required experimental system. The experimental system includes an experimental tank, an optical fiber spectrometer, a temperature detection system, a data acquisition system, a powder spraying system, a pressure sensor and an ignition system;

[0011] b. Measure the median particle size of the metal dust sample to be tested, dry it, put it into the powder spraying system after drying, evacuate the experimental tank to vacuum, and spray the metal dust sample into the evacuated experimental tank through the powder spraying system to form a metal dust cloud;

[0012] c. Ignite through the ignition system to cause the metal dust cloud obtained in step b to explode; record and analyze the experimental data through the optical fiber spectrometer, the temperature detection system and the data acquisition system to obtain the characteristic spectrum of the explosion flame at the initial stage of the explosion and the curve of the explosion pressure changing with time;

[0013] d. Calculate the explosion detection index F at the initial stage of the metal dust explosion by means of formula (1);

[0014]

[0015] In formula (1), ΔI λ / Δt is the spectral intensity change rate at a specific wavelength; η is the average rate of change of the spectral intensity at a specific wavelength with time under normal working conditions; P is the real-time pressure; α is a safety factor to avoid mis-triggering of the pressure threshold setting, with a value of 2-3; P0 is the pressure when the experimental system operates normally.

[0016] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, the ignition system is located inside the experimental tank, and the ignition system includes an electronic ignition source and an ignition electrode.

[0017] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, the optical fiber spectrometer and the temperature detection system are respectively connected to the outside of the experimental tank. The spectral optical fiber spectrometer is used to collect spectral information, and the temperature detection system is used to measure the environmental temperature inside the experimental tank.

[0018] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, the experimental tank body is connected with a vacuum pump, and the inside of the experimental tank body is evacuated to a vacuum state through the vacuum pump; metal dust and compressed air are introduced into the powder storage tank, and the metal dust is pressurized and dispersed into the experimental tank body through the compressed air.

[0019] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, in formula (1), η is calculated according to formula (2):

[0020]

[0021] In formula (2), T is the time when η changes in real time; ΔI λ (k) / Δt is the spectral intensity change rate of wavelength λ at the k-th moment.

[0022] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, the metal dust sample to be measured mainly refers to aluminum-magnesium alloy dust.

[0023] In the above method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, in step d, the criteria for the explosion of the metal dust sample to be measured are divided according to the magnitude of F, specifically: when F≥1, it indicates that the metal dust sample to be measured has exploded; when F<1, it indicates that the metal dust sample to be measured has not exploded.

[0024] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0025] The present invention proposes a method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure. With the aid of the experimental system of the present invention, by obtaining the emission spectrum information and explosion parameters of several explosion flames, such as the spectral intensity change rate, the spectral intensity change rate under normal conditions, and the explosion pressure P during the explosion of aluminum-magnesium alloy dust at a wavelength of 500 nm, aluminum powder at a wavelength of 471 nm, and magnesium powder at a wavelength of 372 nm, the emission spectrum information and explosion parameters of the explosion flame are determined through experiments. The parameters are substituted into the proposed explosion detection method to obtain the explosion detection index F. When F≥1, it represents an explosion, and when F<1, it indicates that the metal dust sample to be measured has not exploded. Through the 20L closed spherical explosion overpressure characteristic experimental system, the formation process of metal dust explosion and the danger of metal dust explosion can be understood, providing a certain theoretical reference for safe production, and strict fire and explosion prevention measures can be formulated and taken in advance to ensure production safety.

[0026] The present invention obtains the explosion detection index F through a formula, and by dividing the value of F, the detection of metal dust explosion can be more accurate. Description of the Drawings

[0027] The present invention will be further described below in conjunction with the accompanying drawings:

[0028] Figure 1 It is a schematic flow diagram of a method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure according to the present invention.

[0029] Figure 2 It is a schematic structural diagram of the experimental system required by the present invention.

[0030] In the figure: 1. Vacuum pump, 2. Valve, 3. Fiber optic spectrometer, 4. Electronic ignition source, 5. Ignition electrode, 6. Powder storage tank, 7. Exhaust valve, 8. Temperature detection system, 9. Data acquisition system, 10. Experimental tank. Specific embodiments

[0031] The present invention proposes a method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure. In order to make the advantages and technical solutions of the present invention clearer and more definite, the present invention will be further described below in conjunction with specific embodiments.

[0032] The main technical concept of the present invention lies in: mainly applying the theoretical knowledge of spectroscopy and the theoretical knowledge of dust explosion, and using the metal dust and its explosion information: the change rate of spectral intensity at the time of explosion of aluminum-magnesium alloy dust with a wavelength of 500 nm, aluminum powder with a wavelength of 471 nm, and magnesium powder with a wavelength of 372 nm, the change rate of spectral intensity under normal conditions, the explosion pressure P, etc., to detect the occurrence of explosion, and solving the technical problems such as untimely detection of metal dust explosion in the prior art. The explosion detection index F can be obtained through the formula of the present invention. By analyzing the value of F, the explosion of metal dust can be detected more accurately.

[0033] The metal dust sample to be measured mentioned in the present invention refers to aluminum-magnesium alloy dust.

[0034] As Figure 2 shown, the experimental system required by the present invention includes a vacuum pump 1, a valve 2, a fiber optic spectrometer 3, an electronic ignition source 4, an ignition electrode 5, a powder spraying system, an exhaust valve 7, a temperature detection system 8, a data acquisition system 9, and an experimental tank 10. The powder spraying system includes a powder storage tank 6. The electronic ignition source 4 and the ignition electrode 5 are located inside the experimental tank 10 and together constitute an ignition system. The experimental tank 10 is usually a 20L closed spherical tank. The powder spraying system is used to pressurize the metal dust sample to be measured and spray it into the experimental tank to form a dust cloud. The experimental tank 10 is connected to the exhaust valve 7. The data acquisition system 10, the temperature detection system 8, and the fiber optic spectrometer 3 are connected to the experimental tank 10.

[0035] Using the above experimental system to detect the explosion of metal dust, its prediction method is as Figure 1As shown in the figure, it specifically includes the following steps:

[0036] (1) First, design a metal dust explosion experiment plan, including experimental parameters such as the particle size and mass of the metal dust, and the emission spectrum intensity value measured by the fiber optic spectrometer; install and debug the experimental system;

[0037] (2) Use a particle size analyzer to analyze the particle size distribution of the aluminum-magnesium alloy dust, measure the median particle size of the aluminum-magnesium alloy dust sample, dry it in an oven, then put it into the powder spraying system, pressurize the powder storage tank to 2 MPa, evacuate the experimental tank to a vacuum of 32 kPa, and spray the metal dust into the experimental tank to form a dust cloud;

[0038] (3) Ignite through the ignition system to cause the metal dust cloud in the experimental tank to explode, use the fiber optic spectrometer and pressure sensor to collect experimental data, and obtain the change rate of the characteristic spectrum of aluminum powder, magnesium powder, and aluminum-magnesium alloy powder under normal conditions and the change rate of the characteristic spectrum during explosion, and the explosion pressure; prepare the characteristic spectrum of the explosion flame at the initial stage of explosion and the curve of the explosion pressure changing with time;

[0039] (4) Calculate the metal dust explosion detection index F through formula (1).

[0040]

[0041] In formula (1), F is the explosion detection index; ΔI λ / Δt is the change rate of the spectral intensity at a specific wavelength; η is the average rate of change of the spectral intensity at a specific wavelength with time under normal conditions (which can be dynamically updated through real-time data); ΔI λ / Δt and η can both be obtained by measuring with a fiber optic spectrometer; P is the real-time pressure (obtained from the characteristic spectrum of the explosion flame at the initial stage of explosion and the curve of the explosion pressure changing with time); α is a safety factor to avoid mis-triggering of the pressure threshold setting, and can take a value of 2 - 3; P0 is the peak process pressure obtained from the pressure analysis during the normal operation of the experimental system.

[0042] Because η needs to be updated in real time, the calculation method of η is given:

[0043]

[0044] In the formula, T is the time when η changes in real time; ΔI λ (k) / Δt is the change rate of the spectral intensity at wavelength λ at the k-th moment.

[0045] (5) According to the magnitude of F, divide the standard for detecting the explosion of aluminum-magnesium alloy dust: when F ≥ 1, it indicates that the metal dust has exploded; when F < 1, it indicates that the metal dust has not exploded; when there is a situation where the metal dust burns briefly and then goes out, F < 1.

[0046] The present invention will be further described below in conjunction with specific embodiments.

[0047] Embodiment 1:

[0048] Before conducting the metal dust explosion experiment, design an explosion experiment plan, pre-experiment to determine the optimal particle size for metal dust explosion, and use the ignition system to test the ignition energy to ensure that the ignition energy is the minimum energy sufficient to ignite the metal dust. Use the temperature detection system 8 to measure the ambient temperature inside the experimental tank, install and debug the system to ensure that all components are in good condition; ensure that the 20L airtight experimental tank has good airtightness, and use the vacuum pump 1 to evacuate the 20L airtight experimental tank to a vacuum; check the ignition duration of the ignition system to ensure that it can accurately detonate the metal dust cloud dispersed in the experimental tank; select metal dust with an appropriate particle size, and then put the metal dust into the powder storage tank of the powder spraying system and wait to be sprayed into the tank to form a metal dust cloud.

[0049] When conducting the metal dust explosion experiment, press start on the data acquisition system of the 20L airtight experimental tank, and use the vacuum system to evacuate the experimental tank to a certain required vacuum, and spray the metal dust in the powder spraying system into the experimental tank. The powder spraying system in the experimental tank first sprays the metal dust into the experimental tank to form a metal dust cloud, completing the powder spraying process. Immediately afterwards, the ignition electrode ignites the ignition cartridge, and the metal dust cloud undergoes energy excitation and explodes. At the same time, use the data acquisition system 10 to collect experimental data such as characteristic spectra and pressure, and the explosion situation can be observed through the glass window of the experimental tank. It should be noted that the outer shells of all electrical equipment should be connected to the common ground.

[0050] When the metal dust explosion experiment is completed, thoroughly clean the experimental tank with a vacuum cleaner. For the relevant data obtained from the experiment that affect the metal dust explosion, evaluate and analyze the possibility of the metal dust explosion through the proposed formula. According to the design purpose, analyze the explosion, including the characteristic spectra of the explosion flame, the change of the explosion pressure, etc., and combine with formula (1) to judge the possibility of the metal dust explosion occurring.

[0051] Those parts not described in the present invention can be achieved by referring to the prior art.

[0052] It should be noted that those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present application, rather than to limit the present application. As long as within the scope of the essential spirit of the present application, appropriate changes and variations made to the above embodiments fall within the scope of protection required by the present application.

Claims

1. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure, characterized in that The following steps are included in sequence: a. Install the required experimental system, which includes an experimental tank, a fiber optic spectrometer, a temperature detection system, a data acquisition system, a powder spraying system, a pressure sensor and an ignition system; b. Measure the median particle size of the metal dust sample to be tested, dry it, put it into the powder spraying system after drying, evacuate the experimental tank to vacuum, and spray the metal dust sample into the vacuumed experimental tank through the powder spraying system to form a metal dust cloud; c. Ignite the metal dust cloud obtained in step b by igniting the ignition system; record and analyze the experimental data by using a fiber optic spectrometer, a temperature detection system, and a data acquisition system to obtain a characteristic spectrum of the explosion flame at the initial stage of the explosion and a curve of the explosion pressure changing with time; d. Calculate the explosion detection index F at the initial stage of metal dust explosion using formula (1); In Equation (1), ΔI λ / Δt is the spectral intensity change rate at a specific wavelength; η is the average rate at which the spectral intensity of a specific wavelength changes with time under normal working conditions; P is the real-time pressure; α is a safety factor to avoid false triggering of the pressure threshold setting, with a value of 2 to 3; P0 is the pressure during normal operation of the experimental system.

2. The metal dust explosion detection method based on the coupling of emission spectrum and explosion pressure according to claim 1, characterized in that: The ignition system is located in the experimental tank, and the ignition system includes an electronic ignition source and an ignition electrode.

3. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure according to claim 1, characterized in that: The optical fiber spectrometer and the temperature detection system are respectively connected to the outside of the experimental tank. The optical fiber spectrometer is used to collect spectrum information, and the temperature detection system is used to test the ambient temperature in the experimental tank.

4. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure according to claim 1, characterized in that: The experimental tank is connected to a vacuum pump, and the experimental tank is evacuated into a vacuum state by the vacuum pump; metal dust and compressed air are introduced into the powder storage tank, and the metal dust is pressurized and dispersed into the experimental tank by the compressed air.

5. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure according to claim 1, characterized in that: In formula (1), η is calculated according to formula (2): In formula (2), T is the time for η to change in real time; ΔI λ (k) / Δt is the spectral intensity change rate of wavelength λ at the k-th moment.

6. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure as claimed in claim 1, characterized in that: The metal dust samples to be tested mainly refer to aluminum-magnesium alloy dust.

7. A method for detecting metal dust explosion based on the coupling of emission spectrum and explosion pressure according to claim 1, characterized in that: In step d, the explosion standards of the metal dust samples to be tested are divided according to the size of F, specifically: When F ≥ 1, it indicates that the metal dust sample to be tested has exploded; When F < 1, it indicates that the metal dust sample to be tested did not explode.

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