Overview of rake dryer
A rake dryer is an intermittent drying equipment that uses indirect heating as its core, combined with mechanical stirring (rake teeth) and vacuum environment. It is mainly used to process materials that are difficult to flow, such as paste, paste, powder, and granular. It is particularly suitable for materials that are heat sensitive, prone to oxidation, require solvent recovery, or contain organic solvents (such as pharmaceutical raw materials, food additives, dye intermediates, resins, coatings, etc.). Its core feature is to evenly heat the material through rake teeth stirring, and to cooperate with a vacuum system to reduce the drying temperature, avoiding material deterioration or oxidation. It is widely used in industries such as chemical, pharmaceutical, food, dye, pesticide, etc.
Working principle
The drying process of the rake dryer is based on the synergistic effect of "indirect heating+mechanical flipping+vacuum dehumidification", and the specific process is as follows:
Material feeding: The material to be dried (paste, paste, etc.) is added from the top or side feeding port of the dryer, filling a certain space of the dryer cylinder (usually 1/3-1/2 of the volume).
Heating and stirring: The dryer cylinder is equipped with a jacket (or an internal heating tube) on the outside, and the heat medium (steam, thermal oil, hot water, etc.) transfers heat through the jacket/heating tube, keeping the heating surface in contact with the material on the inner wall of the cylinder at high temperature. At the same time, the rake teeth agitator driven by the motor inside the cylinder (rake teeth are symmetrically distributed and can rotate forward and backward) continuously flips and stirs the material, pushing it towards the heating surface and breaking up the clumped material, continuously updating the surface of the material, uniformly contacting the heat source, and accelerating the vaporization of water or solvents.
Vacuum dehumidification: The dryer is connected to the vacuum system (vacuum pump), and a certain degree of vacuum is maintained inside the cylinder (usually 0.06-0.095MPa). In a vacuum environment, the boiling point of water or solvents in the material is significantly reduced (for example, when the vacuum degree is 0.09MPa, the boiling point of water is about 45 ℃), which can quickly vaporize at lower temperatures and avoid high-temperature decomposition of thermosensitive materials; At the same time, the vaporized water vapor or solvent vapor is discharged through the condenser at the top of the cylinder (when recovering the solvent) or directly through the vacuum pipeline under vacuum suction, completing dehumidification.
Discharge: When the material is dried to the set moisture content (usually ≤ 0.5%), stop heating and stirring, and discharge the dried powder or granular material through the bottom discharge port (manual or automatic).

Main features 
Strong material adaptability: it can handle paste, paste, powder, granular and other forms of materials, especially for materials with high viscosity and easy caking (such as carboxymethyl cellulose, adhesives, etc.), while spray drying, fluidized bed drying and other equipment are difficult to handle such materials.
Thermally sensitive materials are friendly: indirect heating (without direct contact with open flames or hot air)+vacuum low-temperature drying (usually 50-100 ℃) can minimize the thermal decomposition or denaturation of thermosensitive materials (such as antibiotics, enzyme preparations, vitamins).
High drying uniformity: The forced stirring of the rake teeth ensures full contact between the material and the heating surface, avoiding local overheating or uneven drying, especially suitable for fine chemical or pharmaceutical products that require high drying uniformity.
Convenient solvent recovery: The vacuum system can be combined with a condenser to efficiently recover volatile organic solvents (such as ethanol and acetone) from materials, reducing environmental pressure and raw material loss. It is suitable for handling materials containing valuable solvents.
Low oxidation risk: The vacuum environment can isolate air, prevent materials from oxidizing and deteriorating during the drying process (such as oils and fats in food and easily oxidizable intermediates in chemicals), and reduce the risk of dust explosions.

Technical Parameter

Model	1000 type	User	Wuxi, Jiangsu
Sector	Electroplating wastewater	Design processing capacity	≥1t/h
Heating form	Steam	Concentration	Supersaturation concentration
Evaporating temperature	90℃	Equipment material	Titanium material+316L