How to prevent static electricity in pneumatic conveying
? ? ? Inpneumatic conveyingThe harm of static electricity in pneumatic conveying is very significant. Static electricity may cause material adhesion and dust explosion. Therefore, when designing pneumatic conveying, it is important to pay great attention to static electricity in pneumatic conveying. So, how to prevent static electricity? Let the editor of Juheng understand for you below.
1. The disasters caused by electrostatic discharge of charged objects are due to their discharge, which forms an ignition source, which is one of the necessary conditions for dust explosions. Electrostatic discharge refers to the discharge that occurs in the nearby atmosphere or along the surface of a charged object due to certain obstructive factors.
The classification of electrostatic discharge is as follows:
(1) Gas discharge
1) Sharp discharge. As shown, in the atmosphere, the general discharge energy and density are relatively small, occurring in protruding parts, emitting light, accompanied by weak sound, and the probability of causing disasters is low.
2) Beam discharge. After further expansion of the discharge at the tip of the system, the luminescence appears in a dendritic shape, accompanied by strong destructive sounds. Compared with pointed discharge, it has a higher possibility of disaster formation.
3) Spark discharge. The shapes of charged objects and grounding bodies are relatively smooth, and they are relatively close to each other. Emit a strong light accompanied by a destructive sound. The discharge energy of spark discharge is high, making it the most likely source of ignition.
(2) Surface charge: Surface charge often occurs on the surface of an insulator, and the discharge conditions are: high charge or close to the insulator. The discharge emits light in a dendritic shape.
2. Humidification and de electrification. For example, in the process of limestone crushing, static electricity occurs, causing the powders to agglomerate and adhere to the inner wall and balls of the ball mill, greatly hindering the crushing effect. If water is added as a conductive substance, it can remove static electricity and shorten the time required for crushing. The relationship between the amount of water added W and the crushing speed. The relationship between the powder conductivity ys, mass specific surface area Sm, and the adsorbed water molecule layer thickness n (in terms of the number of water molecule layers). Practice has proven that the pulverization process operates best when the conductivity of the powder is adjusted to 10-7-10-9 S/m through humidity control. This pair of pneumatic conveying can be used as a reference.
3. Charged prevention agents are also a type of surfactant, with a wide variety of types, divided into five categories: esters, anionic surfactants, non ionized surfactants, amphoteric surfactants, and cationic surfactants.
4. Grounding provides reliable electrical contact for all parts of the device, while the device itself is grounded.
5. Other effective measures for removing electricity include air ionization, granulation (increasing particle size), and the use of blended fabrics with hydrophilic and conductive polymer fibers as filter materials on bag vacuum cleaners.
pneumatic conveyingThe design of is a complex project that involves aerodynamics,Multiple disciplines such as particle science, mechanics, thermodynamics, fluid mechanics, etc. So professional people are needed to design it in order to achieve the characteristics of stable transportation and high transportation efficiency.