The operation method of the negative pressure drying granulator can be divided into the following steps, which are explained in combination with the modular design characteristics and closed operation requirements:
1、 Preparation before operation
1. Material pretreatment
(1) Ensure that the particle size of the raw material is ≤ 100 mesh and the free water content is<1.5%. If necessary, dry or sieve it.
（2）Check the sealing of the negative pressure system, confirm that there are no gaps at the connection between the sealing cover and the host, and that the glove box is functioning properly.
2. Equipment inspection and debugging
（1）Check the surface of the pressure roller (straight/mesh/smooth surface) and the meshing state with the ring mold, and adjust the gap between the pressure roller to 0.1-0.3mm.
（2）Confirm that the pressure error of the hydraulic system is ≤ 0.2MPa, lubricate the moving parts such as bearings and motors.
（3）Install a whole particle sieve with the corresponding aperture (usually 16-60 mesh) and clean the residual material.
2、 Startup and parameter setting
1. Start sequence
（1）Start the dust removal system from the back to the front, then turn on the negative pressure sealing cover, cooling water circulation, main motor, and feeding mechanism in sequence.
（2）Initial stage: Close the steam valve, run the feeding screw at low speed (15-20Hz), and discharge the aged material from the ring mold to the ground.
2. Parameter settings
（1）Set the roller pressure (adjusted to 8-15MPa according to material characteristics) and feeding speed (matching the required tablet thickness).
（2）Open the steam valve and gradually increase the steam volume until the material temperature reaches 50-60 ℃. Observe that the material is in a loose mass after tempering.
3、 Operation monitoring and adjustment
1. Production process control
（1）Negative pressure monitoring: Maintain a negative pressure value of ≥ -50Pa inside the sealed enclosure to prevent dust leakage.
（2）Particle quality: Real time detection of particle size (16-60 mesh accounting for ≥ 70%), hardness (unbreakable by hand), and color uniformity.
2. Exception handling
（1）Blockage: Immediately stop the machine, remove the pressure roller from the glove box to clean any residue, and check the filling status of the feeding screw;
（2）Loose particles: Increase the pressure of the pressure roller or reduce the feeding speed.
3. Load optimization
（1）Gradually increase the feeding speed to stabilize the main motor current at 90% of the rated value (full load).
（2）Monitor the fluctuation of tablet thickness (± 0.1mm) through the PLC interface and dynamically adjust the gap between the pressure rollers.
4、 End operation
1. Shutdown process
（1）Close the steam valve → stop feeding → turn off the main motor after the ring mold is emptied → stop the cooling water circulation → turn off the negative pressure system.
（2）Collect finished particles, sieve and separate fine powder (can be returned for re granulation).
2. Cleaning and maintenance
（1）Disassemble the pressure roller, ring mold, and screen mesh, clean residual materials with a soft brush, and disinfect stainless steel components with 75% ethanol.
（2）Check the wear of the pressure roller (replace if the diameter changes by ≥ 0.5mm every month), lubricate the chain and bearings.
5、 Key operational points
1. Negative pressure control: Maintain glove box operation throughout the entire process, and do not directly open the sealed cover.
2. Anti sticking treatment: For easily sticky materials, pre coat the surface of the pressure roller with magnesium stearate or use a water cooling system (cool down to below 40 ℃).
3. Safety protection: In case of abnormal shutdown, the main power supply should be cut off first, and it is strictly prohibited to disassemble the pressure roller components with power on.
Through the above process, efficient granulation with material yield>95% and dust leakage rate<0.1% can be achieved.