Airflow drying is to blow mud, powder or block wet material into the drying cylinder with the flue gas (or hot air) sent from the combustion furnace, and the wet material is in contact with the hot air flow for high-speed movement. Vaporize to get dry. The airflow drying is characterized by high gas velocity, usually 20-40 m/s, and the material particles are suspended in the airflow. The heat transfer coefficient between gas and solid and the heat transfer surface area are large, and the drying effect is large. better. In addition, the structure is simple, the cost is low, the moving parts are few, the construction and maintenance are easy, and the operation is stable and easy to control. However, from the perspective of the entire drying system, due to the high airflow speed, the friction between the material and the wall during the conveying process and the collision between the materials form a resistance to consume large power, and the drying cylinder requires a height of more than 10 meters. Recycling equipment requirements are also higher. [next] Fluorine Tubes,Fluoroplastic Extruded And Mold Tube,Fluoroplastic Ptfe Tube For Heater,Fluoroplastic Pipes Molded Ptfe Tubes Mianyang Prochema Commercial Co.,Ltd. , https://www.gustek.com
The airflow dryer is a drying device consisting of one or several upright cylinders, a drying device, and a feeding device, a combustion furnace, a cyclone, a fan and a discharge device. As shown below. The wet material is fed from the feeding device 1 into the pulverizer 8 at the bottom of the air drying cylinder, and the flue gas (or hot air) from the combustion furnace simultaneously fed into the pulverizer is blown into the air drying cylinder. The wet material is dispersed and suspended in the air stream by the high-speed moving hot gas to obtain a dry, and the dried material is discharged from the bottom after the airflow enters the cyclone, and the exhaust gas is discharged into the atmosphere through the fan. 
At present, many excellent methods have been developed in order to reduce the height of the drying cylinder and obtain better drying effect. It is known from the drying experiment that the movement of the particles in the drying cylinder is divided into an accelerated motion phase and a constant velocity motion phase, usually an acceleration phase. It is completed within 1 to 3 meters above the feeding port. When the wet material enters the bottom of the drying cylinder, its rising speed Ï… m is zero, the air flow speed is Ï… n , and the relative velocity Ï… t (Ï… t = Ï… n - Ï… m ) between the air flow and the particles is the maximum. The flow heat transfer coefficient is also large; when the material is blown by the airflow, it accelerates continuously, and the rising speed Ï… m rises from zero to a certain value, and the relative velocity Ï… t between the gas and the material particles gradually decreases until it equals the sedimentation velocity of the particles in the airflow. When Ï… 0 , that is, Ï… t = Ï… 0 = (Ï… n - Ï… m ), the particles are no longer accelerated and maintain a constant speed rise.
To this end, to reduce the height of the drying cylinder and obtain a good drying effect, the role of the acceleration section at the bottom of the drying cylinder should be fully utilized. At present, the following improvement measures are adopted;
(1) Multi-stage airflow dryer: The 2~3 airflow drying equipment is used in series, which increases the number of acceleration sections and reduces the total height of the drying cylinder.
(2) Pulsed airflow dryer: replaces the straight pipe with a pulse tube that alternately reduces and enlarges the diameter, so that the material to be dried is alternately reduced and enlarged in diameter, and is subjected to the action of high-speed airflow and inertia of the movement of the particle itself. The relative velocity and heat transfer area between the gas stream and the particles are increased, thereby increasing the heat transfer and vaporization speed.
(3) Inverted cone airflow dryer: the drying tube is provided with a large and small inverted cone, so that the airflow speed is gradually lowered from bottom to top, and the particles of the dried material are suspended at different heights in the tube according to different particle sizes. It is dried.
(4) Cyclone dryer: A cyclone separator is used as a dryer. The airflow entrains the material into the cyclone airflow dryer in a tangential direction, and generates centrifugal acceleration along the wall, so that the material particles are in a state of suspension and rotation, thereby increasing the relative speed and dry area between the gas and the solid to strengthen the drying process.
Panzhihua iron ore processing plant (design) by an air drying means drying an aqueous 14%, particle size of 0.4 to 0 mm titanium ore, drying tube diameter dc common 400 mm 4, the desired total flow rate of hot air 20000 m when /, the processing capacity of 16 tons / total coal consumption of 1.8 t / ilmenite after drying is less than 1% water.