Mechanism, Characteristics, Harm And Prevention Of Powder Static Electricity
Due to the rapid development of modern industry, the generation of dust is very common in human production and life, and the pulverization of raw materials and finished products is also widely used in mining, smelting, chemical, textile, pharmaceutical, food processing and building materials industries. However, the hazards caused by dust can be seen everywhere in human living environment, daily production and life.
Among so many hazards, people tend to ignore the electrostatic hazards in the process of powder production, transportation and storage. In the manufacture of powder, the raw materials are broken, crushed and ground, and in the process of powder transportation, collection and storage, frequent friction between powder particles and between the powder and the container wall is inevitable. Impact, friction, and separation will result in contact, separation electrification and friction electrification, which will charge the powder and container with static electricity.
Powders containing a huge amount of powder particles will accumulate considerable electrostatic charges. If the resistivity is high, the accumulated static electricity will not easily leak, thus forming a strong electrostatic field. If the electric field strength can penetrate the air, it will Different forms of electrostatic discharge phenomena occur. If electrostatic discharge of substances occurs, the harm range is wide and the consequences are serious. The objects that generate brush discharge and spark discharge will have a high potential, and may generate a current of several amperes. This electrostatic energy will cause insulation breakdown, Cause electric shock, fire and explosion.
Powder Static Electricity Is Harmful In Industry
In the production process, when the static electricity of an object accumulates to a certain extent, or its potential is higher than the breakdown field strength of the surrounding medium, electrostatic discharge occurs. This electrostatic discharge phenomenon is the energy release process caused by the ionization of the gas in the space around the charged body caused by the electric field energy, that is, the process of converting electrostatic energy into heat energy, light energy and sound energy. According to the luminous form of electrostatic discharge, electrostatic discharge can be divided into corona discharge, brush discharge, spark discharge, and surface discharge that emits light along the surface of a charged body.
Spark discharges mostly occur between metal objects. The air between the electrodes is broken down during discharge, forming a very concentrated discharge channel. This kind of discharge energy is released quickly and concentrated, so it is dangerous to ignite. Electrostatic discharge can cause production failures, damage semiconductor components, and cause malfunctions and malfunctions of electronic devices using these components; static noise can cause information errors; can cause fires and explosions; and electrostatic shocks to the human body, Causes injuries such as dermatitis or skin burns. The most serious hazards caused by static electricity are fire and explosion. Therefore, the focus of electrostatic safety protection is mainly on the protection of fire and explosion.
How To Keep Safe From The Hazards Static Electricity
To eliminate the hazards of static electricity, technical measures should be taken first to limit or avoid the generation and accumulation of static electricity from the process. For example, pay attention to the selection of materials or the material selection of production equipment; improve the operation method, prevent splashing and washing, and reduce the friction speed or flow rate as much as possible; when filling the solution, first remove the impurities at the bottom of the tank, and Purifies petroleum products and helps eliminate additional static electricity. Leakage and neutralization methods can also be used to eliminate static electricity.
During activities such as walking, putting on and taking off clothes, or standing up from a chair, the human body can generate static electricity due to contact and separation of solid materials such as clothing and electrostatic induction. When the human body and other objects are discharged, the discharge spark is enough to ignite petroleum vapor and many gases. Therefore, in an explosive and flammable environment, anti-static work clothes made of conductive fibers and anti-static shoes made of conductive rubber must be worn. Utilizes the humidity dependence of the antistatic effect.
Powder Electrostatic Characteristics
Powder electrostatic voltage can be as high as thousands to tens of thousands of volts. Compared with other solids, dust has many differences, such as dispersibility and suspension. Under the same material and quality conditions, the dust surface area is much larger than that of the whole solid, mainly because of its dispersibility. Static electricity is often generated because of increased surface area, which leads to reduced stability. Therefore, even though the monolithic polyethylene is a stable substance, the polyethylene in the powder state is unstable and may explode violently. Since the powder is in a suspended state, the particles and the ground are always insulated by air, regardless of whether the material that makes up the powder is an insulating material. Therefore, many metal powders can also generate and accumulate static electricity under certain conditions, such as aluminum powder and magnesium powder.
Dust For Industrial Productionanti-static
In actual industrial production, dust undergoes different processes such as grinding, stirring, screening and pneumatic conveying in the process of production, storage and transportation. Static electricity is generated by collision, friction, peeling and fracture with processing equipment, conveying pipes, screens, etc. According to the charging characteristics of different processes and different types of industrial dust, corresponding electrostatic disaster prevention measures should be formulated.
In actual industrial production, the driving force for conveying dust is generally air conveying. In an environment with air, if the dust is accumulated due to static electricity and eventually leads to electrostatic discharge, the electrostatic discharge energy is greater than the minimum ignition energy of the dust, which will cause the dust to burn and explode, resulting in Casualties, property damage and environmental pollution. In this case, the air is changed to nitrogen for transportation, which avoids direct contact between dust and oxygen, completely eliminates the combustion and explosion accidents caused by static electricity accumulation and discharge, and eliminates static electricity hazards from the root.