The operation steps of the rotary flash dryer can be divided into the following key steps, which are explained in detail based on equipment characteristics and safety regulations:
1、 Preparation before operation
1. Equipment inspection
Confirm that there are no abnormalities in the fan, mixer, inlet/outlet, and other components, and check if the power, water, and gas sources are stable (voltage fluctuations should be ≤ ± 5%).
Verify the sealing of steam and compressed air pipelines, and the pressure gauge should display a working pressure of 0.5-0.6 MPa.
For heat sensitive materials (such as aluminum hydroxide), the cooling water system needs to be tested in advance to ensure that the bottom cooling device can maintain the material temperature ≤ 200 ℃.
2. Security protection
Operators are required to wear dust masks (N95 grade), heat-resistant gloves, and goggles, especially when handling viscous materials, additional anti adhesive work clothes should be provided.
Check the integrity of the explosion-proof membrane. Before operating flammable and explosive materials (such as dye intermediates), the oxygen concentration in the system needs to be replaced to<10%.
2、 Startup process
1. Start the induced draft fan
Use star delta voltage reduction starting (power ≥ 30kW models), observe the ammeter to reach the rated value and run steadily (about 2-3 minutes).
Adjust the butterfly valve of the induced draft fan to maintain a slight negative pressure of -50~-100Pa in the system to prevent dust leakage.
2. Heat source and feed control
Open the steam valve to raise the temperature, and set the inlet temperature according to the material characteristics (such as 180-220 ℃ for calcium carbonate and ≤ 150 ℃ for food grade materials).
Start the variable frequency feeder, control the initial feeding amount at the rated 30%, and gradually increase it to the design value after the outlet temperature stabilizes at 90-100 ℃.
For high humidity materials (initial moisture content>80%), a pulse blowback system (frequency 0.5-1Hz) should be used to prevent bag blockage.
3、 Key points of operation monitoring
1. Real time parameter adjustment
The temperature fluctuation in the mixing chamber should be ≤ ± 5 ℃, and balance can be achieved by adjusting the feed rate and steam valve opening.
Current monitoring: A sudden increase of 20% in the current of the mixer motor may indicate material blockage and requires immediate shutdown for inspection.
2. Exception handling
When the discharge is interrupted, priority should be given to lightly tapping the fan housing with a wooden hammer; If it is ineffective, stop the machine for cleaning, and it is strictly prohibited to operate with faults.
When the temperature of the hot air rises abnormally, it is necessary to urgently cut off the heat source and activate the cooling water protection system.
4、 Shutdown specifications
1. Programmed shutdown
First, close the feed valve and continue blowing for 10 minutes to remove excess material (to prevent wet material from clumping).
Stop the blower and induced draft fan in reverse order, and finally turn off the main power.
Titanium equipment needs to be purged with nitrogen for 30 minutes to prevent oxidation.
2. Maintenance requirements
Clean up the accumulated material in the cyclone separator every week and check the wear of the mixing blade (if it exceeds 2mm, it needs to be replaced).
The bearing lubrication uses high-temperature lithium grease (replenished every 500 hours).
5、 Special material handling
1. Thermally sensitive materials, such as amino acid salts, require segmented drying (with a gradient decrease in inlet temperature from 160 ℃ to 140 ℃) and inert gas protection.
2. High viscosity materials, such as carrageenan, need to be pre crushed to a particle size of<5mm and added with 0.5% anti adhesive agent (such as silica).
6、 Attention:
1. It is strictly prohibited to open the maintenance door during operation (internal wind speed can reach 30-60m/s).
2. When the pressure difference of the bag filter exceeds 1500Pa, it needs to be cleaned immediately.
3. Food grade equipment should be disinfected with 75% alcohol on the contact surface after each use.