Centrifuge Suppliers tell everyone about the safe use of centrifuges
Centrifuge is widely used in the pharmaceutical and chemical industries, and it is still the main equipment for solid-liquid separation in the current production processes of chemical intermediates and pharmaceutical raw materials. However, the centrifugal separation process in the production of chemical and pharmaceutical industries generally involves flammable and explosive solvents. The safety of the centrifuge during operation has become the primary requirement for model selection.
During the operation of the centrifuge, the internal environment in which flammable solvents exist has potentially unsafe factors causing combustion and explosion. If this potential unsafe factor meets the right conditions, it will lead to accidents.
1.Causes of combustion and explosion accidents
Combustibles, oxidizers and ignition sources are called the three elements of combustion. Explosion is violent combustion. Explosion is a phenomenon in which energy is rapidly released or rapidly converted into mechanical work and other energy. The conditions for causing an explosion are: temperature, pressure, and explosive concentration. Explosion accidents caused in centrifuges are mainly the explosion of combustible gas mixtures in confined spaces, that is, the explosion of explosive materials. The explosion process of explosive substances has the following three characteristics: that is, the reaction process releases heat, the process speed is extremely fast and can automatically propagate, and a large amount of gas products are generated in the process. These three conditions are necessary for any chemical reaction to become an explosive reaction, and these three are interrelated and indispensable.
2. Basic principles of explosion protection
The basic principle of explosion protection is to analyze the characteristics of the explosion process in order to take corresponding preventive measures. Prevent the emergence of the first process, limit the development of the second process, and protect against the harm of the third process. The basic principles are as follows:
(1) Prevent the formation of explosive mixtures
(2) Strictly control the ignition source
(3) Cut off the propagation route of the explosion
(4) Reduce the damage to personnel, equipment and buildings caused by explosion pressure and shock waves
(5) Detect and alarm.
3. Safety technical measures for explosion-proof centrifuge
(1) Prevent the formation of combustible and explosive systems
When centrifuging inflammable and explosive materials, the Centrifuge can be filled with combustible gas. Once the centrifuge generates sparks due to static electricity or other reasons, the centrifuge will experience combustion and explosion accidents. Therefore, when centrifuging a solution containing flammable and explosive materials, ensure that the centrifuge is airtight and explosion-proof. When using inert gas or other gas protection, such as filling the centrifuge with nitrogen to replace the air inside, so as to maintain the oxygen concentration within a safe range. To control the oxygen concentration, the oxygen concentration monitoring method can generally be used to strictly control the oxygen concentration.
First of all, it is necessary to ensure that the nitrogen gas source is stable and operate in strict accordance with the operating procedures. The two accidents mentioned above were caused by the operators opening the feeding valve and turning on the centrifuge without the protection of nitrogen, and the solution entered the high-speed rotating centrifuge. The machine produced static sparks that detonated the toluene mixed gas, causing the centrifuge to explode. When the nitrogen pressure is insufficient or the nitrogen supply system fails, the alarm device will send an alarm and automatically stop; when the centrifuge is started, the centrifuge system must be replaced with nitrogen, and the oxygen concentration will reach 1% to 2%. When the centrifuge enters the liquid, the floating liquid and the washing liquid must be protected with nitrogen to prevent the air from entering the centrifuge at the end of the liquid or with the vortex mist of the liquid; in the event of a power failure, to achieve nitrogen purge The work can still be carried out normally, it is required to select a normally closed solenoid valve to ensure that the nitrogen pipeline valve is always open when the power is cut off.
Special attention should be paid to the fact that when the enterprise transforms the original centrifuge, in the inertization protection transformation of the centrifuge, the corresponding supporting facilities should be installed, such as online oxygen detection system, interlocking protection device, otherwise it will be easily protected by inertia. Unstable air source, poor management, and misoperation, due to the system sealing, cause more serious centrifuge explosion accidents.
(2) Eliminate and control ignition sources
The main energy sources that cause fire and explosion accidents are open flames, high-temperature surfaces, friction and impact, adiabatic compression, chemical reaction heat, electrical sparks, static sparks, lightning strikes, etc. Therefore, full attention must be paid to these fire sources in places with fire and explosion hazards, and strict control measures must be taken.
When designing the centrifuge, ensure that there is sufficient safety space for the moving parts to eliminate possible mechanical friction and impact. At the same time, the centrifuge system must have measures to eliminate static electricity. For braking devices, mechanical friction braking devices must not be used, and electrical energy consumption braking is generally used. In addition, for the transmission belt, an anti-static belt is used to eliminate or reduce the possibility of static electricity. When purchasing a centrifuge, companies should put forward more precise manufacturing requirements for the configuration of the centrifuge, such as: configuration of explosion-proof motors, on-site explosion-proof buttons, explosion-proof solenoid valves, explosion-proof proximity switches, explosion-proof isolation barriers, anti-static belts, electrostatic grounding, Frequency converter control, energy consumption braking, nitrogen protection, online oxygen content detection, etc. However, not all occasions with explosion-proof requirements need to be configured, and should be configured appropriately according to the actual process and operating environment. In the process of transporting flammable and explosive materials, the relevant requirements of GB12158-2006 "General Guidelines for the Prevention of Electrostatic Accidents" shall be strictly followed. Special attention should be paid to the anti-static treatment of the discharge pipe between the reactor and the centrifuge.
In addition, use non-sparking copper, alloy or other tools, and explosion-proof electronic clocks in the explosion hazard area; smoking, fireworks, and mobile phones are strictly prohibited at the operation site. The workplace should be tested regularly for lightning protection and static electricity to ensure safety.
(3) Isolate and block to prevent the accident from spreading
The two accidents mentioned above were caused by the explosion of the centrifuge, which ignited the solution containing flammable and explosive materials discharged from the bottom valve of the reactor, which quickly spread to the entire workshop. Due to the excessive storage of dangerous chemicals in the workshop, the explosion and combustion accident caused all the indoor equipment to collapse and destroy, causing the accident to expand.
First of all, the centrifugal separation area should be set up in a separate compartment, separated from other production areas by fireproof solid walls, and sufficient pressure relief area should be ensured, and the ventilation of the centrifugal separation area should be strengthened. The centrifuge operation area should strictly control the number of on-site operators.
Secondly, companies should strictly control the amount of hazardous chemicals stored in the workplace. Enterprises with conditions try to use pipeline transportation. If the job site needs to use barreled materials for direct feeding, a special intermediate material storage area should be designated. The material storage area and the production area should be separated by fireproof solid walls, and try to ensure that there is no material stacking in the solvent area. It is strictly forbidden to store hazardous chemicals in the centrifugal operation area, and special attention should be paid to the centrifugal residue not to be stored in the centrifuge room.
(4) Effective monitoring and timely processing
The centrifugal operation area is strictly in accordance with the requirements of GB50493-2009 "Petrochemical flammable gas and toxic gas detection and alarm design specification", with flammable gas and toxic gas detection and alarm devices, and interlocked with forced ventilation facilities. If the centrifuge leaks, the detection alarm can issue an alarm within the set safe concentration range, which can achieve early detection, early elimination, and early control to prevent accidents and spread.
(5) Improve the centrifugal process and use a new type of centrifuge
In the design of the centrifuge nitrogen protection system, an online oxygen detection device and a pressure transmission sensor are set to detect the oxygen concentration in the centrifuge cavity during operation, and implement quantitative control to control the oxygen content within a safe range. When the centrifugal equipment breaks down and personnel misoperation forms a dangerous state, a series of operations such as safe discharge of accidents and shutdowns can be realized through automatic alarms, activation of interlocking protection devices and safety devices to ensure system safety.
4.experience and lessons
The factors that affect safety in the process of safe production are the unsafe behavior of human beings and the unsafe state of objects. While educating and guiding employees to improve safety awareness, we should put the unsafe state of objects in the first place. There are many factors influencing people's unsafe behaviors, and at the same time, no matter how strong people's safety awareness is, they may make mistakes of this kind. If we control the unsafe state of things well, we can actually improve the security of the system.
The centrifugal separation process in the production of chemical and pharmaceutical industries generally involves flammable and explosive solvents. The safety of the centrifuge during operation has become the primary requirement for model selection. The application of new technologies such as centrifuge inert gas protection, online oxygen detection technology, pressure difference automatic transmitter, and special interlock protection make the system safer and product quality more assured. Especially the application of intelligent automatic control technology will greatly improve the safety and automation of traditional centrifugal separation equipment, and ensure the safety and reliability of the system.
The company also provides Decanter Centrifuges, please feel free to contact us if necessary
