The effect of dust concentration and particles on the explosion
Dust concentration and flammable dust explosion also exist the upper and lower limits of dust concentration. The value is affected by many factors such as ignition energy, oxygen concentration, particle size, powder type and moisture content. The explosion limit can be estimated by using the simplified formula. Generally speaking, the dust explosion lower limit concentration is 20 ~ 60g/m3 and the upper limit is between 2 and 6kg/m3. The upper limit is affected by many factors, and its value is easier to determine than the lower limit. It is usually not easy to reach the upper limit concentration. Therefore, the lower limit is more important and more useful.
(2) when the particle size of combustible powder is larger than 400um, the dust cloud formed is no longer explosive. However, when the size of ultrafine powders is below 10um, it is more dangerous. It should be noted that even if the average particle size of the powder is larger than 400um, it often contains finer powders, and the few parts of the powder are also explosive.
3, the technical measures of dust explosion. The combustion reaction requires combustible materials and oxygen, and a certain source of ignition. For dust explosion, there are three elements: ignition source, flammable fine dust, dust suspended in air, and dust cloud formed in the explosion concentration range. The three elements exist at the same time to explode. Therefore, as long as one of the conditions is eliminated, the explosion can be prevented. In Bag Filter, the following technical measures are often adopted.
In the special design of the structural design measures of explosion-proof structure, in order to prevent the ash of combustible dust in the internal components of the Dust Collector, all beams and separators should be set up, and the slope of the dustproof board should be less than 70 degrees. The slide angle of the ash bucket is greater than 70 degrees. In order to prevent the ash accumulation due to the small angle between the two bucket walls, the two adjacent side plates should be welded to the slide plate to eliminate the deposition of dust. Considering that the operation is not normal and the dust is exposed to the dust when the dust humidity is large, the heat insulation or tube of the steam pipe is added to the high temperature dust collector when the ash bucket is designed. Electric heater. In order to prevent the ash hopper material, each bin still needs to set up the boom vibrator or air gun.
(2) using an antistatic filter bag inside the dust collector, because the high concentration dust is rubbed with each other during the flow process, the dust and the filter cloth also have mutual friction to produce static electricity, and the product assembly of the static electricity produces sparks and causes the burning. For the pulse cleaning method, the filter bag with polyester needled felt is easy to produce electrostatic deficiency in order to eliminate the polyester needle felt. In the filter bag, the conductive metal wire or carbon fiber is spun in the filter bag. When the filter bag is installed, the filter bag is connected by the steel skeleton and the porous plate, and the shell is connected to the floor network through the shell. For anti filter bags, many kinds of antistatic products such as MP922 have been developed. The effect is very good.
It is important to set up a safety hole (valve) to limit the explosion to the inside of the bag type dust collector and not extend to other aspects. The purpose of setting up safety holes is not to prevent the safety holes from exploding, but to limit the scope of explosion and reduce the number of explosions. Most dust remover handling explosive dust is operated under the condition of safety hole. Because of this, the design of safety holes should ensure that in case of an explosion accident, it can play a real role; usually, we should strengthen the maintenance and management of safety holes.
(1) the explosion-proof plate is an emergency pressure relief device driven by pressure difference and is not automatically closed. It is mainly used in pipe or dust removal equipment to avoid damage caused by overpressure or vacuum. Compared with the safety valve, bursting disc has the advantages of large discharge area, sensitive action, high precision, corrosion resistance and easy to clog. Rupture discs can be used separately or in combination with safety valves.
2. Explosion-proof valve design safety explosion-proof valve design mainly has two kinds: one is the explosion-proof plate; the other is the heavy hammer type explosion-proof valve. The former needs to replace the new board after breaking, and the production should be interrupted. When it is exposed to high negative pressure, it will be easily damaged and not easy to keep warm. The latter is more advanced than the previous ones, and is closed by heavy hammer pressure and poor tightness. The above two methods are not suitable for high pressure pulse ash removal. In order to solve the tightness problem, explosion proof safety lock can be designed on the hammer type explosion proof valve. Its characteristics are: when the lock is closed, the lock of the safety door is mainly through this lock, which can be released automatically when it explode. The release force (An Quanli) can be adjusted by the spring. In order to balance the safety door, 4~6 locks should be set according to the safety door area. In order to make the explosion-proof door tight and air tight, it can be designed as a dual structure of the explosion-proof plate and the safety lock.
Looking for ideal Industrial Bag Type Pulse Jet Filter Manufacturer & supplier ? We have a wide selection at great prices to help you get creative. All the Pulse Jet Air Filter are quality guaranteed. We are China Origin Factory of Industrial Pulsed Jet Deduster. If you have any question, please feel free to contact us.
Product Categories : Bag Filter