Safety technology of the hottest mixing process

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Mixing process safety technology

agitation process safety the safety of reaction and operation under mixing conditions

stirring directly affects the mixing degree and reaction speed of the reaction. The mixing speed is fast, and the relative movement speed between the material and the wall, and between the material and the mixer is also fast. If the wall or agitator is an insulator (such as glass lining), or it is not an insulator but is poorly grounded, the danger of static electricity cannot be ignored. Generally, the volume is more than 300L, the mixing speed is more than 60R/min, and the relative movement speed of the material with the mixer and the wall can exceed 1m/S; If the resistivity of the material is about 1012 cm (for example, the resistivity of benzene is 4.2 1012 cm), static electricity is easy to accumulate and discharge. When there is an explosive mixture of flammable liquid vapor and air in the reverse sampler, the fire risk is particularly high. In order to prevent this danger, we should first understand the properties and resistivity of materials; If the material is flammable and explosive, and the resistivity is between 1010 ~ 1015 cm, the mixing speed should be controlled. The larger the reactor diameter, the slower the mixing speed should be. 10. Open the oil return valve to make the piston fall back to the reactor below 00l, and the stirring speed shall be controlled within 60R/min; Above 1000L, the rotating speed should also be slowed down, otherwise inert gas should be filled or the process conditions should be changed, such as adding electrolyte aqueous solution and other materials to reduce the resistivity to below 1010 cm

secondly, oil leakage from the stuffing box of the mixing shaft should be avoided, because the oil in the stuffing box will be dangerous if it leaks into the reactor. For example, during nitrification reaction, there is concentrated nitric acid in the reactor. If lubricating oil leaks in, the oil will oxidize and heat under the action of concentrated nitric acid, which will raise the temperature of reaction materials, and flushing, combustion and explosion may occur. When there is strong oxidant in the reactor, China's demand is difficult to overcome, and there are similar dangers or even worse, so we should not take it lightly

for dangerous and flammable materials, do not stop mixing halfway, because when mixing stops, the materials cannot be fully mixed, the reaction is poor, and a large amount of accumulation; When the mixing is resumed, a large number of unreacted materials are mixed rapidly and react violently, which often leads to charging, combustion and explosion hazards. Therefore, the operating system should stipulate that if the mixing stops due to failure, the feeding should be stopped immediately, and the sample should be cooled quickly. After clamping, the holder must be loosened before stretching; When the mixing is resumed, the feeding can be continued and the normal operation can be resumed only after the temperature is stable and the reaction is normal

the agitator should be maintained regularly to strictly prevent uneven mixing of materials caused by the disconnection of the agitator, and finally the sudden reaction will lead to violent flushing, or even explosion and fire. The agitator shall be flexible to prevent the motor from catching up and catching fire due to excessive temperature rise

the agitator shall have sufficient mechanical strength to prevent accidents caused by friction with the reactor wall due to deformation

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