Static electricity safety is an important part of safety management in the chemical production process. The generation and accumulation of static electricity may cause major safety accidents, seriously affect safe production, and cause significant economic losses. The hidden nature of static electricity causes personnel to pay less attention to the management of static electricity safety. Therefore, be familiar with the causes of static electricity, fully understand the preventive measures of static electricity, implement preventive measures in the chemical production process, improve personnel’s awareness of static electricity safety and safety management level in the production process, so that everyone pays attention to static electricity safety to ensure Production is safe and stable.
Chemical companies often use, transport and store flammable and explosive gases, liquids and solids in the production process. Due to factors such as process formulation deviations, improper operation methods or paralysis of personnel thinking, static electricity will be generated. May cause a safety accident. Combustion and explosion accidents caused by static electricity in the chemical production process are not uncommon, but the quality of products is not up to standard, equipment and facilities are damaged, and serious economic losses, casualties and other adverse effects will be serious. Therefore, understand the causes of static electricity, predict the possible hazards, and take safe and reliable preventive measures to achieve “prevention first, prevent combination”, in order to ensure the safe and orderly production, to achieve the intrinsic safety of the production process.
1 .Causes of static electricity
Static electricity is caused by the transfer of electrons in the outer layer of atoms caused by various external forces to form positive and negative charges, so static electricity is divided into positive and negative static electricity. The main causes of static electricity are friction electrification, contact electrification and induction electrification. The friction between the objects will cause the transfer of charge, which is the electrification of the friction; the objects of two different materials will separate after contact with each other, and the objects will be charged when they are close to the charged objects; when the objects are close to the charged objects, the objects will be charged, which is called induction charging. Static electricity is not a static charge. It is a charge that accumulates on the surface or inside of an object because the generated charge cannot be released in time. When objects of different electrostatic potential are close to or in contact with each other, charge transfer will occur, and the discharge of static electricity will produce electrostatic discharge. If ignition conditions are met, combustible materials will be ignited, causing accidents and casualties.
2. The danger of static electricity
(1) Cause production safety accidents
Most media used in chemical production are flammable and explosive. During the process of material friction stirring, material flow, shaking during media transportation, etc., static electricity will accumulate. The voltage of static electricity can reach 10,000 volts, even 100,000 volts. If discharge occurs, combustibles, flammables, or even difficult Burning materials will also be ignited. The instantaneous discharge of static electricity can also cause dust explosions. The danger of dust explosions is often more shocking. The first explosion of dust will raise more dust, and the second explosion of dust is often more terrible. The human body generates static electricity due to the friction between clothing or between the human body and the clothing during the activity. The strong mobility of the personnel makes the monitoring of the static electricity carried by the human body particularly difficult. Once electrostatic discharge of the human body occurs, it may cause combustibles and combustibles. When a fire or explosion occurs, causing a safety accident or casualties.
(2) Cause production safety failure
Static electricity can cause great harm to safety operations, quality, equipment and production environment. Especially in the process of powder material transportation, static electricity will deposit materials with smaller particle size, adhere to the pipe wall, block the pipeline, the material cannot be transported, and even the pressure of the pipeline and the system rises, which may cause serious damage to the equipment . The discharge of static electricity causes the electronic components of the device to burn out or break down in the computer system or control system, which may cause errors in signal transmission or reception, thereby causing production failures and safety accidents. Static electricity will also accelerate the aging speed of electronic components and shorten their life.
(3) Cause personal injury
Electrostatic shock is not an electric shock through which the electric current continuously passes through the human body, but refers to the shock injury caused by the static discharge instantaneously. Electrostatic shock can cause damage to the human center, nerves and other parts. Electrostatic shock is not caused by the human body directly touching the live part of the charged equipment, nor caused by the failure of the electrical equipment, but because of the contact and separation of the clothes and solid materials during the activities of the person, as well as the static induction and other conditions that make the human body Static electricity is formed, resulting in injury from electrostatic discharge. The damage of static electricity to personnel is uncertain, and special attention should be paid to the static electricity of personnel.
3. Prevention of static electricity
Static electricity has the characteristics of high voltage, low power, low power, small current and short action time, but electrostatic discharge is instantaneous discharge, and often instantaneous power is large. In the chemical production process, safety is the basic condition for obtaining economic benefits. Without safety guarantee, there is no way to talk about production benefits. Often, the economic losses caused by an accident caused by parking will be very large. The generation of static electricity is inevitable. How to reduce the generation of static electricity and release the accumulated static electricity safely in time to eliminate the harm caused by static electricity to ensure that production runs under the premise of intrinsic safety. There are many ways to eliminate static electricity, but the simple and effective measures in the production process mainly include process design control method, static grounding method, static neutralization method and anti-static measures for the human body.
4.Process design control method
The process design control method is a simple and effective solution to fundamentally solve static electricity. From the perspective of process design, the elimination of static electricity is to eliminate static electricity from intrinsic safety, mainly in process design, equipment material selection, equipment structure type, and addition of conductive substances Such measures as reduce the generation of static electricity or discharge the generated static electricity in a timely and safe manner. The main measures are: (1) Choose a reasonable material feeding sequence and method: choose the order of different materials feeding order, the reasonable arrangement of the material conveying method or feeding method; (2) Equipment material: choose the material that is conducive to electrostatic discharge according to the nature of the material Conductive materials, avoid the use of insulating materials; (3) The static discharge measures of the equipment are considered in the design process of the moving equipment, and the safe and reliable measures must be taken to guide the static electricity away from the moving equipment during the design process; (4) The material transportation speed and The material and size of the pipe are reasonably matched: the larger the pipe diameter, the smaller the flow rate, and the smaller the pipe diameter, the faster the flow rate; (5) the addition of a charge inhibitor or a high-conductivity substance to promote the dissipation of charge and reduce the risk of static electricity; (6) Electrostatic grounding alarms are installed at the ends of other mobile equipment such as raw material barrels, turnover barrels, tank trucks, etc., and the static electricity accumulated by the mobile equipment can be exported in time.
related systems. The importance of static electricity in chemical production should be paid attention to. It is eliminated by safe and reliable measures, so as to ensure the safe production of enterprises, avoid accidents, and achieve intrinsic safety in the production process.