Jet mill explosion: airflow crushing process production problems and equipment safety measures

The airflow pulverization process has problems in production and safety measures during operation of the airflow pulverizing equipment:

The jet mill, also known as Fluid Energy Mill, or Jet Mill, is an efficient ultrafine crushing device. Different from the traditional mechanical pulverizer principle, it is a huge kinetic energy generated by the high-speed airflow generated by the high-pressure gas passing through the nozzle, so that the material particles collide with each other, or collide with a fixed plate (such as an impact plate) to achieve the purpose of pulverization. of. Because the uncaptured dust particles in the jet mill crushing sample have a suitable particle size and distribution state: the general particle size is less than 5 μm, the dispersion stability in air is good, and it is easy to reach the explosion limit.

Noise problem

Both research and production practices have shown that the higher the gas flow rate, the finer the product obtained. When ultra-fine products are to be obtained, the speed of the airflow must be supersonic. In order to obtain a finer product, the speed of the airflow has been increased to 2-5 Mach numbers. However, as the airflow velocity and the Mach number increase, the noise generated by the high-speed airflow increases, especially for the disc-type jet mill with direct discharge, when the airflow speed exceeds 3 Mach, the discharge port The actual noise value in the vicinity is above 130 dB (A), which seriously affects the physical and mental health of the operator, makes the hearing declining, palpitation, and the hearing loss cannot be recovered. The snoring makes people unable to concentrate, distraction, and often leads to accidents. Because the structure of the jet mill itself is special, that is, the exhaust port is used for the discharge of high-pressure gas and the discharge of ultra-fine powder products, the design of the muffler is required to reduce noise and not affect the discharge, which is proposed for the structural design of the muffler. Very strict requirements. At present, multi-stage cyclone separators and large dust removal equipment and auxiliary equipment such as exhaust fans are usually connected at the discharge port.

Safety problems in the manufacture of ultrafine powder by jet mill

Includes may cause respiratory pneumoconiosis and dust explosions. The dust particle size obtained by the jet mill crushing sample is basically below 5 μm, and the dust below 5 μm is the most harmful to the human body. Therefore, the probability of using a jet mill to break the sample operator's pneumoconiosis occupational disease will increase significantly. At the same time, after the dust is scattered in the air to form a dust cloud, dust explosion may occur. Because the uncaptured dust particles in the jet mill crushing sample have a suitable particle size and distribution state: the general particle size is less than 5 μm, the dispersion stability in air is good, and it is easy to reach the explosion limit. The consequences of dust explosions are also extremely serious.

If there is enough combustion air around these particles and the minimum ignition energy is available, then a dust explosion is likely to occur. Moreover, the shock wave generated by the local dust cloud explosion causes a large amount of deposited dust to fly and mix with the air, and it is possible to form a secondary explosion. Because dust explosion has the characteristics of large energy, serious damage, short burst time, etc., it is easy to cause incomplete combustion, resulting in a large amount of carbon monoxide gas to poison people. Therefore, the consequences of dust explosions are extremely serious.

Safety measures during operation of airflow pulverizing equipment

In order to reduce dust hazard as much as possible, in addition to dust removal equipment and protection, the following management measures are required: (1) Increase the humidity of the working area, strengthen ventilation and ventilation, and reserve fire extinguishing equipment. (2) As the dust leaks slightly during the manufacturing process, dust will emerge and cause pollution in the work area. Therefore, the tightness at the joint should be ensured. (3) According to the regulations, the operating personnel should be equipped with protective equipment, and the operators should also develop the habit of wearing protective equipment according to the regulations. (4) Maintain and manage the existing dustproof equipment! Ensure its normal operation and play a dustproof role. While capital investment, technological innovation, and improve the level of automation and operational efficiency dust dust-proof equipment.