Explosion sensor of the hottest explosion suppress

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Explosion suppression system - Explosion sensor

as we all know, when an explosion occurs in a confined space, it will be accompanied by thermal radiation, temperature rise, pressure rise, gas ionization and other phenomena. Therefore, as long as any of these external phenomena of the explosion is based on, we can find out whether there is an explosion in the equipment. Therefore, the explosion sensor used in the automatic explosion suppression system should be a device that can convert one of the above parameters into an electrical signal. Thermocouples, thermistors and electricity are the process control requirements of high-speed extrusion production lines. They are widely used in recording and measuring flame parameters in various production devices. In terms of its action speed and sensitivity, these instruments also fully meet the requirements of automatic explosion suppression system. However, they can only find the occurrence of fire source when they are in direct contact with the flame, which fundamentally limits their scope of use in this regard. However, these instruments can be used to detect the combustion in the pipeline, put the flame blocker and flame asphyxiation system into action, and also induce the rupture of the rupture disc. If you want to use them to find the explosion in the container, you have to know the specific location of the fire source in the equipment in advance, which is certainly difficult to do. Photosensitive sensor is a kind of instrument with the strongest applicability. Compared with other instruments, photosensitive sensors have obvious advantages in sensitivity, action speed and applicability in a wide range. Radiation occurs at the moment when the flame is generated and spreads outward at the speed of light. At present, the lag time of the mass-produced radiant energy receiver itself is very short (~ seconds). The combination of the two makes it possible for the explosion to be discovered in the initial stage of development [1]. The ray spectrum of hydrocarbon flame is generally very wide - from ultraviolet to infrared, less than 1% of the energy is ultraviolet, 2 ~ 3% of the energy is visible light, and the rest accounts for the vast majority of the energy is infrared within the range of wavelength from 0.76 to 25 microns. 3. Cooling rate: + 30 ℃ ~ 0 ℃ about 2.0 ℃/min. When selecting the radiation receiver according to the spectral sensitivity, we must consider not only the distribution of flame radiation energy, but also the anti-interference conditions of the explosion sensor. For example, some heating parts of the equipment may produce infrared rays, so the radiation receiver must be able to accurately distinguish what is the radiation generated in the production operation and what is the radiation generated by the flame. Using the characteristics of the flame ray spectrum and the selectivity of the radiation receiver, the anti-interference of the sensor can be guaranteed, and the interference rays in the environment where the radiation receiver is located can be weakened by the filter. Therefore, the optical radiation receiver can be used to detect the explosion in the completely enclosed equipment. Only when the automatic explosion suppression system is not cut off and the equipment is turned on can the receiver misoperate. Although the ultraviolet energy of the flame is weak, the wavelength is about 2.6 × 102. People from all walks of life are deliberately worried about whether this year's mission can be completed. The radiation receiver with the most sensitive spectrum below meters has a bright future in application. In the solar spectrum, this wavelength actually does not exist, because it has been absorbed by ozone in the atmosphere, while in the spectrum of all artificial light sources, the ultraviolet line spectrum is absorbed by the glass bulb of the light source itself. However, the sensitivity of the new photosensitive multiplier can even record the weak radiation in the above-mentioned area, which ensures the anti-interference required by the automatic explosion suppression system. For dust explosion suppression system, photosensitive sensor is not applicable. Although the penetration ability of infrared ray in powder fog is much higher than that of other rays, when the concentration of dust is very high, infrared ray is difficult to penetrate in this medium. In addition to this, in the equipment for processing powdery materials, all the internal surfaces, including the induction screen of the explosion sensor, will be covered with a thick layer of dust with poor transparency. In this case, although different devices can be used to continuously or regularly remove the dust on the induction screen by mechanical method or compressed air purging method, this will greatly complicate the structure of the sensor and greatly reduce the reliability of the whole system. Under this condition, pressure relay is more suitable. However, it can be seen from the table that even the pressure relay with extremely high sensitivity can only detect the explosion after the total explosion time has passed 10 ~ 20%. During this period of time, the spread range of the flame has reached about one third of the volume of the whole equipment. At this time, it is much more difficult to control the fire. Nevertheless, it is completely applicable to use pressure relay as the sensor of automatic explosion suppression system. Especially for dust explosion, pressure relay may be the most promising. In the new type of automatic explosion suppression system, some also adopt fixed limit pressure relay and differential diaphragm contact pressure relay, which can respond to the given pressure or the given pressure growth rate respectively. The limit pressure relay can be used for equipment connected to the atmosphere. Unless there is an explosion, the pressure in the equipment will never rise for any other reason. Powdery materials are usually processed in closed equipment and transported by air flow. Therefore, there is often either positive pressure or negative pressure in these equipment. Although the pressure is not high, it is only tens of millimeters of water column. Moreover, even when the process is normal, the pressure in the equipment will fluctuate, such as when the feeding is unstable and the filter is blocked. Under this condition, the pressure sensor of the automatic explosion suppression system should be able to distinguish whether the pressure fluctuation in the equipment is caused by explosion. Figure 1 differential contact pressure relay the differential contact pressure relay shown in Figure 1 has such a function. When contact 5 is connected with spring diaphragm 4 o) limit protection: it has two-level limit protection of program control and machinery; After touching, the sensor sends a command signal. Air chamber a communicates with the outside world through flow limiting orifice 3. In order to prevent the restriction orifice from blocking, especially in the environment with high dust content, the sensor can be equipped with a loose diaphragm 1, such as the diaphragm made of fluoroplastic film. The loose diaphragm itself will not cause a pressure difference, so the pressure in air chamber B is different from that in the equipment

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