The closed-loop disc dryer adopts multiple new technologies such as closed-loop system, automatic transmission of pressure difference, online oxygen detection, spraying and solvent recovery, and intelligent automatic control. It is an optimization and upgrade of traditional explosion-proof disc drying technology, which can solve the drying problems of organic solvent recovery, easy oxidation and toxic materials. It is safe, environmentally friendly and energy-saving, suitable for free flowing, non adhesive, extremely fine powders (below 100 mesh) and granular materials with wide particle size distribution, as well as drying and organic solvent recovery of materials containing organic solvents.

The closed-loop disc dryer is specifically designed for organic solvents such as alcohol, acetone, NMP, DMF, etc., using an inert gas medium formed by circulating nitrogen gas instead of the usual air solvent. In response to the low flash point, slight toxicity, flammability, and explosiveness of organic solvents, the following protective measures have been specially designed:

The upper layer of nitrogen explosion-proof: According to the inert gas properties of nitrogen, the entire pipeline adopts nitrogen circulation, and the system can only operate normally when the oxygen content is below 3%.

D Level 2 industrial control explosion-proof: When the pressure exceeds 3000pa, the safety valve can be opened to release pressure.

D Three layer explosion-proof plate: When the pressure inside the disc dryer system chamber rises abnormally, the explosion-proof plate at the top of the tower automatically opens to release the explosion.

D Four layer whole machine explosion-proof: with internal ventilation system, suitable for harmful gases. Can prevent oxidation, avoid danger, improve quality, achieve sterility and dust-free.

Drying process: The heat carrier is introduced into a fixed multi-layer hollow disk, and the wet material in contact with the metal disk surface is indirectly heated by conduction. Under the mechanical stirring effect similar to a plow shaped rake blade, the moisture in the moving material is continuously evaporated and vaporized at the boiling point of the operating state. The moisture leaves the equipment through the moisture outlet, and qualified dried products are obtained at the bottom.

Before use, the closed-loop disc dryer uses nitrogen to replace the air in the system, so that the oxygen content in the system reaches the safe concentration of the solvent. Wet materials enter the drying machine through the feeding port on the equipment in a sealed container. The air supply fan sends filtered nitrogen gas, which is heated by a heater to the temperature required for the drying process. It then enters the disc dryer to remove the evaporated moisture. During the drying process, the humid and hot gas carries a small amount of micro powder and passes through the dust collector to separate all micro powders above 2um into gas-solid in the dust collector. Solid dust is collected in the dust collector, and the gas enters the multi-stage condenser (finned condenser has low pressure drop and good condensation effect) to condense the solvent in the humid and hot gas. The condensed solvent is collected in a collection tank and stored (zero emission to air, recyclable). After condensation and dehumidification, the dry nitrogen gas is then sent to the heater for circulation through a blower.

(1) After nitrogen circulation disc drying, the hot and humid gases containing solvents enter the condenser to condense the solvents in the gas (with a solvent recovery rate of over 95%), which can both recover the solvents and condense the dehumidified dry gas. The recovered solvent can be recycled again, which can save costs and will not cause environmental pollution due to exhaust emissions. Hot and humid gases undergo condensation dehumidification, resulting in lower humidity inside the gas (compared to ordinary boiling drying) and stronger drying ability, making them more suitable for moisture absorbing materials that are affected by humidity environments.

(2) The nitrogen circulation disc dryer is a fully enclosed structure, and the equipment is filled with inert gas (such as nitrogen) inside. When drying anaerobic materials or materials containing flammable and explosive solvents, there is no oxygen in the gas, making it impossible to burn or oxidize. This can effectively prevent equipment from catching fire or exploding during production, making it safer than ordinary equipment.

(3) Vertical installation, complete insulation, high utilization rate of heat source and waste heat. Evaporation requires only 1.1-1.4 kg of steam per kilogram of water. In addition, the required power is only about 1/10 of that of the rotary cylinder dryer, which is economically feasible;

(4) The discharge speed of exhaust gas or steam is low, and there is less dust flying, which can meet the requirements of the three waste emission standards and improve the working environment. It is particularly suitable for drying pesticide raw materials without the need for dust removal equipment;

(5) If combined appropriately with other devices, solvents and dry paste materials can also be recovered. It can also be used for various product thermal processing processes such as roasting and sublimation.

(6) The temperature of each layer of material tray can be controlled to achieve the specified temperature distribution. Drying, cooling, and using can obtain dry products with uniform quality and low mechanical stress;

Drying, pyrolysis, combustion, cooling, reaction, sublimation

（1） Organic chemical products

（2） Inorganic chemical products

（3） Medicine and food

（4） Feed and fertilizer