Pneumatic conveying series

Product Introduction:

Also known as air transport, it USES the energy of air flow to transport granular materials along the direction of air flow in a closed pipe, which is a specific application of fluidization technology. The pneumatic conveying device is simple in structure and easy to operate. It can be used for horizontal, vertical or inclined transportation. In the process of conveying, it can also be used for physical operation or some chemical operation such as heating, cooling, drying, airflow classification of materials, etc. Compared with mechanical transport, the energy consumption of this method is large, the particles are vulnerable to damage, equipment is also vulnerable to abrasion. It is not suitable for pneumatic conveying materials with high water content, adhesion or static electricity generation in high speed motion. The main characteristics of pneumatic conveying are large conveying volume, long conveying distance and high conveying speed. It can load in one place and then unload in many places. According to the density of particles in the transport pipeline, pneumatic transport is divided into: thin pneumatic transport

Phase transport: the solid content is lower than 1-10kg/m3, the operating gas speed is high (about 18-30m /s), and the transport distance is basically within 300m. Now mature equipment material seal pump, transport operation is simple no mechanical rotating parts, low pressure, no maintenance, maintenance free! (2) Dense phase transport: the transport process with a solid content of 10-30kg/m3 or a solid-gas ratio greater than 25. Lower operating air speed and higher air pressure. At present, the mature equipment warehouse pump has a conveying distance of more than 500m, which is suitable for long-distance conveying. However, this equipment has many valves and more pneumatic and electric equipment. High conveying pressure, all pipes need wear - resistant materials. Intermittent tank type dense phase transport. It is to add the particles into the pressure tank in batches, and then ventilate and blow loose. After the tank reaches a certain pressure, open the material valve and blow the granular materials into the conveying pipe for transportation. Pulse conveying (FIG. 4) is to pass a stream of compressed air into the lower tank to blow loose the material; The other pulse compressed air flow with a frequency of 20 ~ 40min-1 blows into the inlet of the feeding pipe, forming alternately arranged small section of material column and small section of air column in the pipe and pushing forward by air pressure. Negative pressure transport:

Pneumatic conveying

The pressure in the pipeline is lower than atmospheric pressure, self-suction feeding, but discharging under negative pressure, can transport the distance is short; Advantages: equipment investment, small load. Disadvantages: high running velocity, serious pipe wear, wear loopholes can not be detected!

When dilute phase transport is carried out in horizontal pipelines, the gas velocity should be higher, so that the particles are dispersed and suspended in the airflow. When the gas velocity decreases to a certain critical value, the particles will begin to deposit in the lower part of the tube wall. This critical gas velocity is called deposition velocity. This is the lower limit of gas velocity in dilute phase horizontal transport. When the operating gas velocity is lower than this value, the sedimentary layer appears in the tube, the flow passage section decreases, and the airflow still runs at the deposition rate above the sedimentary layer.

When the air velocity is high, the particles are dispersed and suspended in the air flow. When the conveying volume of particles is constant, the solid content in the pipeline increases with the decrease of gas velocity. When the gas velocity is reduced to a certain critical value, the airflow can no longer disperse the dense particles evenly, and the particles converge into a plunger shape, resulting in a surge phenomenon (see), and a sharp rise in pressure drop. This critical speed is called choking speed, which is the lower limit of gas speed when dilute phase is delivered vertically upward. For the particles with uniform particle size, the deposition rate is approximately equal to the choking rate. However, for materials with certain particle size distribution, the deposition rate will be 2 ~ 6 times of the choking rate

Pneumatic conveying can be roughly divided into two types according to the working principle: suction and pressure. Suction pneumatic conveying means that the atmosphere and materials are sucked into the pipe together and transported by low-pressure airflow, so it is also called vacuum suction. Pneumatic conveying is the conveyance of materials driven by compressed air higher than atmospheric pressure.