{pboot:sort scode=4}

Rotary flash dryer is a drying equipment that integrates drying technology and fluidization technology. According to the structure of the flash dryer, the working process can be divided into four stages: crushing, gas-solid contact, drying, and grading. These four working processes cannot be simultaneously possessed by other dryers.

1. Crushing, as flash dryers are mainly used for drying paste like materials, the materials are immediately crushed by stirring blades and high-speed airflow after entering the dryer, in order to increase the dispersion of the materials and the surface area of wet materials per unit volume to a certain extent.

2. Gas solid mixing, flash drying machines generally use air as the heat carrier, and whether the gas solid mixing can be effectively achieved is the main factor affecting the drying rate. The stirring blade of the flash dryer crushes the material and produces a dispersing effect, while the air entering the dryer is also in a turbulent state, quickly achieving gas-solid mixing. At the same time, the block shaped material falls downwards under the action of gravity. Due to the inverted cone structure at the bottom of the dryer, the airflow velocity is very high, up to 60ms. It can ensure that the block material is in a good fluidized state and surrounded by hot air.

3. In the drying stage, after the material is crushed, it is blown up by the high-speed rotating hot air flow from the bottom, forming a relatively stable fluidized layer in the drying chamber. In the drying process of mass and heat transfer between materials and hot air, most of the moisture evaporates during this stage. Materials with high moisture content and small surface area have high density. When they fall in the drying chamber, due to the high gas velocity at the bottom, the falling speed becomes zero after a certain distance, and gravity and buoyancy are balanced. After further crushing and evaporation of moisture, the buoyancy of the material is greater than gravity, and the material begins to move upward. After classification, it is discharged from the dryer.

4. In the grading stage, the classifier is a circular baffle installed at the top of the flash dryer. Due to the centrifugal force, during the process of the material rising with the airflow, large and wet materials have a larger rotation radius. When the rotation radius is greater than that of the grading ring, they are blocked in the drying chamber until they meet the requirements before being discharged from the dryer through the classifier. When the material is added to the dryer, it is in a rotating fluidized state. After being crushed, the diameter of the clumps rapidly decreases and the water evaporates.