How to prevent static electricity fire in petrochemical industry
In the petrochemical industry and industries where flammable gases, steam and dust are usually generated, static electricity is one of the important causes of fires. Therefore, it is very necessary to take measures to prevent the generation of static electricity and conduct static electricity protection.
Generally speaking, the contact and impact between the solid surface and the solid surface, the solid surface and the liquid surface, or the fracture of the solid or the splashing of the liquid may generate static electricity. For example, the flow of high-resistivity liquids (such as petroleum), the movement of liquid filtration, the movement of dust in the grinding, mixing and screening process, the gas transmission of dust, the movement of people and machines on the insulated floor, the relative movement of belts and axles Other similar processes may generate static electricity. After the electrostatic potential reaches a certain value, it will break down the surrounding gas and produce sparks. When the energy of the spark reaches a sufficient value, it can ignite certain flammable substances and cause a fire.
Based on past experience, there are three main conditions that cause static electricity fires. The first is the presence of flammable or explosive items; the second is the generation of electric charges during the installation, operation and operation of the equipment, and the accumulation of electric charges. The electric field strength formed by the electric charge is greater than the surrounding breakdown electric field strength; the third is that the electric spark has more energy than the surroundings The smallest ignition energy. If one of the above three conditions is missing, it cannot cause an explosion or fire. Anti-static safety measures are specific to specific situations.
1. Grounding. The static charge on the conductor can be introduced into the ground by grounding, so that the charge will not accumulate on the conductor.
2. Avoid the accumulation of static charge on the human body. The main causes of electrostatic charge on the human body are the friction of clothes, the transfer of charges after contact with other electrostatic objects, or the electrostatic induction when approaching charged objects. To prevent the accumulation of static charge on the human body, low-resistance anti-static footwear, floor, etc. can be used.
3. Ionize the atmosphere. Because ionization can increase the conductivity of the surrounding air and facilitate the movement of static charges on the surface of the object, the discharge of charged objects or a certain dose of isotope can be used to ionize the air to neutralize static electricity in the object or the air.
4. Humidification. Increasing the humidity of the air can improve the conductivity of the surface of the object and form a conductive path between the object and the ground. Generally, the relative humidity is controlled at 60%-70%, and the anti-static effect is very good.
5. Do a good job of anti-static treatment of non-metallic materials. Many non-metallic materials, such as plastic, rubber, and glass fiber, are insulators, which can easily carry static charges and can last for a long time. Usually, some substances can be added to these materials to make them conductive, and then grounding can be used to eliminate the accumulation of static charge.