In recent years, dust explosions have occurred more frequently in industries such as metallurgy, automobile manufacturing, military, coal, textiles, grain, and food and medicine. According to statistics, there is at least one dust explosion accident occurring on average every day worldwide. The Kunshan Zhongrong explosion accident that occurred on August 2, 2014 alone resulted in 146 deaths and 114 injuries.
With the continuous development of modern industry, the number of enterprises involved in powder processing and dust generation is increasing. The vast majority of dust is flammable and has explosive risks. At the same time, many enterprises have serious dust accumulation on workshop equipment, pipelines, ceilings, and protective covers. The deposited dust will become the "dust source" for secondary dust explosions. Once the first dust explosion accident occurs, the shock wave generated by the explosion will oxidize the deposited dust into a dust cloud, resulting in a stacked dust explosion accident.
Dust explosion accidents will generate high-temperature gases, forming high-speed and high-pressure shock waves, which greatly threaten almost all production processes and assembly lines involved in dust production enterprises. So, the severity of the consequences of dust explosions increases exponentially, once it occurs, it will cause roofs to overturn, walls to collapse, factories to be destroyed, and people to die. Dust explosions pose a serious threat to industrial production safety and also makeDust explosion preventionTechnology has become a key technology for industrial safety.
The five elements of dust explosion:
1. There are combustibles. That is to say, combustible dust, such as starch and flour commonly found in our daily lives, are also combustible..
2. There are oxides that support combustion. Oxide not only refers to oxygen that supports combustion and explosion, but also includes substances that can undergo chemical reactions with combustibles.
3. Ignition source. There are many types of ignition sources, such as open flames, static electricity, sparks, overheated surfaces, etc.
4. Closed space. Including various types of storage tanks, containers, houses, pipelines, etc.
5. Dust can be suspended in the air. When dust is suspended in a closed container and the concentration reaches the lower explosive limit, coupled with the other four conditions, a dust explosion will occur.
Once a dust explosion occurs, it is not uncontrollable and there are many disaster control technologies available. The purpose of explosion disaster control technology is to control explosion accidents in their initial stage or local area, and minimize the degree of damage and loss caused by the disaster. In practical work, for dust explosions, it is necessary toExplosion proofThe perfect combination of technology, explosion venting technology, and explosion suppression technology is necessary to effectively control explosions.
1、 Explosion proof technology
When a dust explosion occurs, the flames and pressure generated will spread to other equipment and facilities through connected pipes, conduits, conveyor belts, etc., causing a secondary explosion. In this case, explosion-proof technology can be used to install isolation devices on the connected pipes to prevent the spread of flames and eliminate the risk of secondary explosions.
Explosion proof equipment is divided into two types: mechanical and chemical. Mechanical explosion-proof devices are divided into active and passive types. Common passive isolation valves include Ventex valves, flap valves, etc. The working principle is that when an explosion occurs, the pressure generated by the explosion pushes the components in the valve body, isolating the valve. Active mode detects the occurrence of an explosion through a detector, and then sends a signal to the isolation device through a controller to actively close the valve. Active plug-in valves and chemical isolation belong to active isolation devices.
2、 Explosion release technology
Explosion release technology is a method of opening the pressure and flame released during the explosion process by installing explosion plates and other equipment on the device, in order to avoid catastrophic damage to the process equipment. The area of the explosion-proof plate is related to the volume of the protected equipment and the explosive parameters of the material, and can be calculated through a formula.
When venting, the flame generated by the explosion, incompletely burned materials, and pressure will be discharged together. If the equipment is located outdoors, materials are allowed to be directly discharged into the atmosphere, and there is sufficient safety zone around the equipment, direct explosion venting can be chosen. If the device is located indoors and direct venting is not allowed, it can be vented outdoors through a venting conduit. However, adding a venting conduit will increase the venting area and also increase the maximum pressure that can be reached for venting. In this case, a flameless venting device can also be used for venting, extinguishing the flame during venting.
In summary, enterprises should choose the most suitable dust explosion protection technology based on their own process system and the explosive characteristics of dust.
In summary, based on the characteristics of dust explosion protection technology, in order for enterprises to effectively control dust explosion accidents, they must do a good job in the preliminary work, such as identifying the characteristics of dust sources, dust characteristics, diffusion characteristics, and ignition source hazards, as well as specialized ventilation design. In response to the intensity of dust explosions and the rate of increase in explosion pressure, combined with the application of industrial dust explosion prevention technology, management and training should be strengthened to achieve comprehensive and multi-level control of dust explosion accidents.
For more information on explosion-proof construction and renovation, please contact Zhongnuo Testing directly
Service Hotline: 18924609560 (same WeChat account)
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