Safety operating instructions for centrifugal spray dryers

Use, maintenance and troubleshooting of centrifugal spray dryer
The following checks should be made before using the centrifugal spray dryer:
1. Check whether the connections between the bearings and sealing parts of each device of the centrifugal spray dryer are loose;
2. Check the lubricating oil condition of each mechanical component and whether each water, air, slurry pipe valve port, etc. is in the required position;
3. Check whether the sealing material is installed at the pipe connection, and then connect it to ensure that unheated air does not enter the drying room;
4. Check whether the centrifugal spray dryer door and observation window are closed and whether there is air leakage;
5. Check whether the rotation direction of the centrifugal fan of the centrifugal spray dryer is correct;
6. Check whether the regulating butterfly valve at the outlet of the centrifugal fan of the centrifugal spray dryer opens the sludge dryer. Do not close the butterfly valve, otherwise the electric heater and air inlet pipe will be damaged. This must be paid full attention to;
7. Check whether the connecting pipe of the feed pump is connected properly and whether the rotation direction of the motor and pump is correct;
8. Check whether the spray head placed on the top of the drying chamber of the centrifugal spray dryer is properly covered to avoid air leakage;
9. Whether the atomizer lubricating oil cooling pipe joint is connected properly and the cooling water is turned on.
Then, turn on the power and check whether the voltage and instruments are normal. Finally, check the amount and concentration of the slurry in the slurry mixing barrel. If any problems occur, they should be eliminated in time.
Precautions and safety hazards for using centrifugal spray dryer
1. When the oxygen concentration does not reach 21%, it is strictly prohibited to open the inspection door; otherwise, it may cause the operator to become hypoxic and suffocate.
2. When turning on the freezer, the circulating water must be turned on;
3. During closed operation, when spraying organic solvents (such as ethanol, xylene, etc.), the oxygen concentration must be controlled below 5% (you can introduce N2 again or restart the machine to make the oxygen concentration reach the required value), otherwise the organic solvent There is a risk of burning or explosion.
4. When the spray drying equipment is in operation, do not touch the rotating parts (atomizer, atomization disk, belt, motor blade)
5. When the spray drying equipment is in operation or for a period of time after shutdown, its surface temperature is relatively high. Please do not touch the bag filter, cyclone separator, air duct, atomizer, exhaust fan, observation window and other components with your hands.
6. Before each drive, the two refueling ports of the atomizer must be filled with oil;
7. Please do not enter the drying tower until the temperature of the spray drying equipment drops to normal temperature.
8. When opening and closing the inspection door, disassembling and assembling the air duct, cyclone separator, and atomizer, be careful of your hands and fingers being pinched.
Daily operation of centrifugal spray dryer
1. First turn on the centrifugal fan, then turn on the electric heating, and check whether there is air leakage. If it is normal, you can preheat the barrel. Because hot air preheating determines the evaporation capacity of the drying equipment, it does not affect the quality of the material to be dried. Under the premise, the inlet air temperature should be increased as much as possible;
2. During preheating, the valves at the bottom of the drying chamber of the centrifugal spray dryer and the discharge port of the cyclone separator must be closed to prevent cold air from entering the drying chamber and reducing the preheating efficiency;
3. When the maximum temperature of the drying chamber reaches the target 180℃~220℃, turn on the centrifugal nozzle. When the nozzle reaches the maximum speed, turn on the feed pump and add the feed liquid. The feed amount should be from small to large, otherwise it will occur. Sticky wall phenomenon until adjusted to the appropriate amount. The concentration of the material liquid should be formulated according to the drying properties and temperature of the material to ensure that the finished product has good fluidity after drying;
4. The temperature and humidity of the dried finished product depend on the exhaust air temperature. During operation, it is extremely important to ensure that the exhaust air temperature is a constant. This depends on the size of the feed amount. The feed amount is adjusted stably and the outlet temperature is Unchangeable. If the solid content and flow rate of the feed liquid change, the outlet temperature will also change;
5. If the product temperature is too low, the feeding amount can be reduced to increase the outlet temperature. If the temperature of the product is too high, the opposite will happen. For heat-sensitive materials with lower product temperatures, the amount of material can be increased to reduce the exhaust temperature, but the humidity of the product will increase accordingly;
6. The dried finished products are collected in the pollinators at the bottom of the tower and the cyclone separator. The pollinators should be replaced before they are full. When replacing the pollinators, the butterfly valve above must be closed first. ;
7. If the dried finished product is hygroscopic, the cyclone separator, its pipes, and the pollinator should be wrapped with insulating materials to prevent the dried finished product from absorbing moisture.
In addition, for materials with heat sensitivity and low softening point, when the exhaust air temperature is too high, the materials will soften, and the cooling air volume needs to be increased.
Finishing and Cleaning
After the centrifugal spray dryer is operating normally, materials should be collected regularly, the operation of each system should be checked regularly, and each process parameter should be recorded. At the end, the heating device should be shut down first, and water should be used to replace the material liquid to flush the remaining material liquid in the material pipe, and then the material pump should be turned off. When the temperature drops below 100°C, the supply fan and exhaust fan can be stopped. Then clean the remaining materials in the drying tower and dust collector, turn off the dust collector and air hammer, and finally turn off the main power supply to complete the production operation. In case of emergency, the equipment must be shut down immediately, and the blower and material pump should be shut down first. If there is a sudden power outage, the tower body should be allowed to cool down naturally, then the drain valve should be opened, the slurry in the slurry pipeline should be drained, and the equipment should be cleaned.
In addition, after use, the spray plate should be removed, immersed in water, and the remaining material should be cleaned with water. If it cannot be washed off with water, it should be scrubbed with a brush. Because the residual material on the spray disk will cause spray imbalance, seriously affecting the service life of the nozzle and even damaging other parts. Do not place the nozzle lying down after completion of work and during transportation. Improper placement will cause the spindle to bend and affect use, so it should be placed with a fixed frame.
Clean
In order to ensure the cleaning of the drying tower body, its pipes and the parts that are in contact with the finished product, and to obtain the best products, regular cleaning equipment is necessary. When the product type is changed, or the equipment has been stopped for more than 24 hours without cleaning, a comprehensive and thorough cleaning should be performed.
The cleaning method can be dry cleaning, wet cleaning or chemical cleaning according to the actual situation.
Dry cleaning: Clean with a brush and vacuum cleaner (suitable for small dryers).
Wet cleaning: Use hot water of 60~80℃ for cleaning.
Chemical cleaning: Cleaning with alkali, acid and various detergents. Among them, acid washing: prepare HNO3 into a solution with a concentration of 1~2%, and the heating temperature does not exceed 65°C for washing, and then wash with water; alkali washing: prepare NaOH into a solution with a concentration of 0.5~1%, and the heating temperature does not exceed 65°C. ℃ for washing, and then rinse with clean water.
After wet cleaning and chemical washing, the equipment and components should be installed and disinfected at high temperature for 15 to 30 minutes.
When cleaning the equipment, be careful not to use chlorine and its compounds.
The cleaning of the air filter should be based on the surrounding environmental conditions, that is, the level of dust content in the air. Generally, it should be cleaned once every 3 to 6 weeks if the dust content is high, and once every 6 to 8 weeks if the dust content is low. The stainless steel filaments among them, after being washed with alkali cleaning, should still be evenly laid into the frame of the air filter and sprayed with light spindle oil or vacuum pump oil.