Brief introduction of air flow type rotary flash dryer

The hot air required for the production of the air flow type rotary flash dryer is sent to the hot furnace by the blower After being heated, the air is divided into two ways to enter the dryer: one is tangential from the bottom side of the dryer, forming a high-speed and low-pressure rotary jet air flow, while the other is from the center at the bottom of the flash dryer, forming a flow air flow The material enters the drying cylinder through the screw feeder and falls down to meet the two air streams The heat and mass transfer process is carried out The moisture is gradually removed and the material is dried After the gas-solid separation of the flash dryer exhaust gas by the cyclone separator and bag separator twice, the exhaust gas is discharged to the atmosphere by the induced draft fan, and the products are respectively discharged to the product storage tank by the bottom of the cyclone separator and bag separator and the star discharger The smaller particles are suspended in the rotating air flow, which is driven by the rotating air flow to rise spirally Under the action of the rotating force field, the relative velocity between the particles and the air flow is larger, which makes the heat and mass transfer coefficient increase again At the same time, under the action of centrifugal force and the rapid low pressure of the central air flow, the larger particles float up and flow spirally along the different positions of the dryer radius The larger particles are close to the wall of the cylinder, causing friction with the wall surface, further granulating the particles, and the fine particles constantly turn, reducing the critical water content and shortening the diffusion distance of internal water to the surface, Thus, the drying speed is still high, and part of the combined moisture in the material is removed As the fine particles move along the helix, the contact time between the material and the hot air flow is increased, which creates favorable conditions for removing the combined water The air flow rotary flash dryer flash quickly, dry wet materials enter the dryer through the screw feeder, small particles float up with the rotating hot air flow, and larger particles fall down With the increase of the heat and mass transfer coefficient, the wet mass can quickly remove the moisture Under the action of the tangential hot gas flow, the dry mass can collide, shear and break each other, so as to achieve the micronization On the one hand, the air flow rotary flash dryer reduces the diffusion distance of water in materials, on the other hand, it also increases the gas-solid contact area, which is conducive to the vaporization of water in materials Some of the larger particles still fall faster than the settling speed In the inverted cone-shaped space, the velocity gradient of hot air is established (from the bottom to the bottom, the velocity gradually becomes smaller, after Zui, it becomes a fixed value), so as to ensure that the lower large particles and the upper small particles are in the fluidization state, so that the material is fluidized and dried, and the water removal is accelerated When the larger particles fall near the bottom gap, the drying active area of the rotary flash dryer is very thin with the high temperature, high speed negative pressure air drying and eddy current fluidization drying in the bottom gap When the particles rotate near the wall, the air velocity in the rotating gas layer is very high, but the air velocity in the center of the drying chamber is very low, so it is difficult to take the particles out of the drying chamber Therefore, a central riser is installed in the center of the bottom of the equipment On the one hand, the turbulence degree of the air flow is added On the other hand, the fine particles after drying are turbulent and upward to eliminate the "dead zone" of the original equipment, strengthen the drying of the central area, and smoothly bring the particles out of the dryer, thus increasing the output of the materials, that is, the air flow drying area At the interface between the updraft and the rotating airflow of the riser, the materials interfere with each other and collide with each other, forming a vortex fluidization drying area between the two airflow, once again strengthening the drying Due to the effect of high-speed and low-pressure in the central area, the fine particles move to the center after the eddy current fluidization drying, and are brought out with the rising air flow The dried fine particles in the rotating air flow supplement the eddy current fluidization area, which greatly reduces the concentration of the rotating fluidization area, increases the hot air capacity, accelerates the heat and mass transfer process, and accelerates the water vaporization speed The axial apparent gas velocity is generally 3-5M S The air velocity in the annular space of the hot air distributor is 30-60m S the air velocity of the central air inlet should be three times of the settling velocity under the average particle size of the central part.