Overview of Nitrogen Circulating Boiling Drying Machine Equipment
The nitrogen circulation boiling dryer is a specialized equipment for drying organic solvent powders. The unit uses nitrogen (or other inert gas) as the drying cycle gas, which prevents oxidation of the materials during the drying process and recovers organic solvents. Sealed boiling dryer is generally used for drying powders of organic solvents such as ethanol, acetone, hexane, etc. The equipment adopts explosion-proof design, and the drying process is safe and environmentally friendly.
Before use, the nitrogen circulation boiling 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 boiling bed to perform heat and mass transfer (drying) on the material added through the differential feeding port. After the feeding is completed, it is dried to the desired final humidity of the material. 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. After drying, the materials on the hot air distribution plate are placed into the lower cylinder by the flipping mechanism, and then input into a sealed container for storage and packaging through a vacuum pump or airflow conveying system (both incoming and outgoing materials are operated in a sealed environment, and there is no dust in the workshop).

Process flow diagram of nitrogen circulation boiling dryer

Equipment structure of nitrogen circulation boiling dryer
The nitrogen circulating boiling dryer consists of an air filter, an air heater, a drying bed, a granulation spray gun, a separation chamber, a filtration chamber, an exhaust duct, an induced draft fan, a chimney, a control system, etc.
1. Host: The host consists of a bottom inlet chamber, a drying bed, a separation chamber, and a filtration chamber.
2. Air filter: filtered by primary and medium efficiency air filters, ensuring a cleanliness level of 300000 for the incoming air.
3. Air heater: Using stainless steel tubes wrapped around aluminum fins, it improves the heat transfer coefficient of the heat exchanger while ensuring no rust or foreign objects fall off.
4. Exhaust system
Composed of exhaust duct, induced draft fan, and muffler, the induced draft fan is installed separately from the main engine, with a noise level of ≤ 80 decibels. The air volume can be adjusted by frequency conversion, and the fluidization state can be continuously adjusted. Therefore, this machine is suitable for a wide feeding range and can also adapt well to the air volume requirements of different material conditions.
5. Mixing mechanism
The use of a built-in rake tooth mixing mechanism in the material truck can assist in fluidization, prevent the phenomenon of dead bed caused by material flow in the drying process, maintain a stable fluidized state, and ensure uniform moisture content of the material after drying.

Schematic diagram of nitrogen circulation boiling dryer structure

Technical characteristics of nitrogen circulation boiling dryer
1. PLC touch screen operation, easy to operate, stable, with strict interlocking function, will not cause human error.
2. The cleaning method is pulse bag cleaning, with continuous offline cleaning and dust removal during operation. The cleaning effect is much better than online pulse cleaning and cylinder shaking bag cleaning methods, avoiding material bed death during drying.
3. Equipped with a pull-out hard skeleton cloth bag, it ensures the bag area and cleaning effect while reducing the poor working environment for workers when dismantling and washing the bag. It is easy to remove the cloth bag from the equipment without drilling into the cylinder.
4. The equipment uses its own induced draft fan to automatically load materials under negative pressure, reducing manual operation and alleviating labor intensity for workers.
5. The equipment achieves automatic closed discharge through an automatic discharge device, reducing cross contamination of materials and labor intensity for workers.
6. The equipment contains a mixing structure that can prevent material trays and dead beds. Make the material fluidized and boil for better drying effect.
7. The equipment adopts a closed circular structure, with no dead corners, easy and rapid cleaning, no cross contamination, and meets GMP requirements.
8. After docking with the pneumatic conveying system, it can achieve fully automatic continuous operation function without human control (optional).
9. There is a drainage device at the bottom of the host, which can quickly drain the accumulated water during machine cleaning;
10. The entire equipment is easy to operate, disassemble, clean, and meets the requirements of "GMP";
11. The whole machine has good sealing performance and operates under negative pressure, which is more in line with GMP standards;
12. The double shaking bag anti-static bag filter (or stainless steel blowback filter can be used if there are special requirements) is sealed with a rubber expansion seal ring between the filter chamber, and has compressed air detection function to ensure reliable sealing. Design dust sensors for exhaust ducts and interlock them with PLC control systems to ensure product safety during the production process.
13. You can choose between a 2Bar or 10Bar dust storm design to ensure the safety of personnel, equipment, and the environment, with reliable grounding.
14. We can provide an online dry granulation unit for lifting flip discharge or an online granulation unit for vacuum discharge to achieve dust-free discharge, which meets the current GMP dust-free production requirements.