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2.2 daily operations 
Use, maintenance and troubleshooting of centrifugal spray dryer
Abstract: Starting from the introduction of centrifugal spray dryer, the use, maintenance and fault treatment of centrifugal spray dryer are discussed.
Key words: centrifugal spray dryer; use; maintenance; fault handling
1 Introduction to centrifugal spray dryer
2 centrifugal spray dryer use
2.1 Preparation before use
Before use, check the following: (1) Check the joints of the bearing and sealing parts of each device for looseness; (2) Check the lubricating oil condition of each mechanical component and whether the water, wind, and slurry valve ports are in the house. (3) Check whether the sealing material is installed at the pipe joint, and then connect it to ensure that unheated air is not allowed to enter the drying chamber; (4) Check whether the door and the observation window are closed and leaking; (5) Check if the rotation direction of the centrifugal fan is correct; (6) Check if the adjustment butterfly valve at the outlet of the centrifugal fan is open, do not close the butterfly valve, otherwise the electric heater and the air inlet pipe will be damaged, which must cause sufficient attention. (7) Check if the connecting pipe of the feed pump is connected, whether the direction of rotation of the motor and the pump is correct; (8) Check whether the top of the drying chamber is placed at the top of the spray head to avoid air leakage; (9) Lubrication of the atomizer Is the oil cooling pipe joint connected and the cooling water turned on?
Then, turn on the power to check whether the voltage and the meter are normal. Finally, check the amount and concentration of the slurry in the slurry mixing tank. If there is any problem, it should be eliminated in time.
(1) First turn on the centrifugal fan, then turn on the electric heating, and check if there is any air leakage. If it is normal, the barrel body can be preheated. The hot air preheating determines the evaporation capacity of the drying equipment, without affecting the quality of the dried material. Under the premise, the inlet air temperature should be increased as much as possible; (2) When preheating, the valve at the bottom of the drying chamber and the lower part of the cyclone separator must be closed to prevent cold air from entering the drying chamber and reducing the preheating efficiency; (3) When the inlet temperature of the drying chamber reaches 180 °C~220 °C, the centrifugal nozzle is turned on. When the nozzle reaches the maximum speed, the feed pump is turned on, and the feed liquid is added. The feeding amount should be small to large, otherwise the sticking phenomenon will occur until Adjust to the appropriate amount. The concentration of the feed liquid should be prepared according to the temperature of the dry nature of the material to ensure good fluidity of the finished product after drying; (4) The temperature and humidity of the dried product depend on the exhaust air temperature, and the exhaust air temperature is guaranteed during operation. It is extremely important to be a constant, depending on the amount of feed, the feed adjustment is stable, and the outlet temperature is not changed. If the solid content and flow rate of the feed liquid changes, the outlet temperature will also change; (5) the product temperature is too low, which can reduce the feed amount to increase the outlet temperature. The temperature of the product is too high, and vice versa. For heat sensitive materials with lower product temperature, the amount of material can be increased to reduce the exhaust air temperature, but the humidity of the product will be increased accordingly; (6) The finished product after drying is collected in the lower part of the tower body and the pollinator at the lower part of the cyclone separator Before the pollinator is not filled, it should be exchanged. When the pollinator is replaced, the above butterfly valve must be closed before closing; (7) If the dried product is hygroscopic, the cyclone and its pipe, the pollinator The parts are wrapped with insulation material to avoid moisture absorption and moisture absorption of the dried product.
In addition, for materials with low heat sensitivity and low softening point, when the exhaust air temperature is too high, the material softens and the cooling air volume needs to be increased.
2.3 end and cleaning
End of 2.3.1
After the centrifugal spray dryer is in normal operation, it should also check the operation of each system regularly and record the process parameters. At the end, the heating device should be shut down first, and the liquid should be replaced by water to rinse the residual material of the tube, and then the pump is turned off. When the inlet temperature is reduced below 100 °C, the operation of the blower and the blower can be stopped. Then clean the remaining materials in the drying tower and the precipitator, turn off the dust collector and the 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. The blower and feed pump should be shut down first. If there is a sudden power outage, the tower body should be naturally cooled, 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 disc should be removed, immersed in water, and the residual material washed with water. Brush it with a brush when it is not washed with water. Because the residual material on the spray plate will bring about the unbalance of the spray, which will seriously affect the service life of the spray head and even damage other parts. Do not lay down after the nozzle is finished and during transportation. Improper placement will cause the spindle to bend and affect the use, so it should be placed in a fixed frame.
2.3.2 Cleaning
In order to ensure the cleaning of the drying tower body and its pipes and all the parts in contact with the finished product, it is necessary to obtain first-class products and regular cleaning equipment. When the product variety is changed, or if the equipment has been discontinued for more than 24 hours without being cleaned, a thorough and thorough cleaning should be carried out.
The cleaning method can be selected according to the actual choice of dry cleaning, wet washing or chemical washing.
Dry cleaning: Clean with a brush or vacuum cleaner (for small dryers).
Wet wash: Wash with hot water at 60~80 °C.
Chemical washing: Wash with lye, acid and various detergents. Among them, pickling: HNO3 is formulated into a 1~2% concentration solution, the heating temperature is not more than 65 °C for washing, and then washed with water; alkali washing: NaOH is formulated into a 0.5~1% concentration solution, the heating temperature does not exceed 65 Wash at °C and then rinse with water.
After wet and chemical washing, the equipment and components should be installed and autoclaved for 15~30min.
When cleaning equipment, be careful not to wash with chlorine and its compounds.
The cleaning of the air filter should be based on the surrounding environmental conditions, that is, the amount of dust in the air. It should be cleaned once every 3 to 6 weeks, and cleaned once every 6 to 8 weeks with low dust content. The stainless steel filaments, after washing with the alkali washing method, should be evenly laid into the frame of the air filter and sprayed with light spindle oil or vacuum pump oil.
3 centrifugal spray dryer maintenance
4 common troubleshooting of centrifugal spray dryer
4.8 Operating vibration is large, there is noise
Reasons: (1) the atomization disc is unbalanced; (2) the shaft is bent; (3) the bearing or the shifting gear is worn or damaged; (4) the lubricating oil is of poor quality.
Processing: (1) correct the balance of the atomizing disk; (2) correct or replace the shaft; (3) replace the bearing or gear; (4) check the lubrication oil supply system and oil quality.
4.9 bearing temperature is significantly increased
Reasons: (1) oil hole is blocked, oil quantity is reduced; (2) oil quality is not good; (3) cooling water pipe is blocked; (4) bearing is worn or damaged.
Treatment: (1) check the oil hole; (2) change the oil; (3) check the cooling water pipe; (4) replace the bearing.
4.10 poor sealing
Reasons: (1) aging of the seal ring; (2) loose fasteners; (3) loose support.
Handling: (1) replace the sealing gasket; (2) tighten; (3) adjust the position of the bracket and tighten.
4.11 pulse bag filter dust removal
Reasons: (1) improper selection of cloth bags; (2) blockage and damage of the bag; (3) excessive pulse period; (4) poor grounding; (5) damage of the pulse valve.
Disposal: (1) select a bag with higher filtration accuracy; (2) clean or replace the bag; (3) adjust the cycle of backflushing; (4) check the ground wire; (5) replace the pulse valve.
If it is equipped with a water filter, the water filter of the water filter will spray water. Cause: The water retaining net is blocked. Handling: Clean or replace the water retaining net.
4.12 Rapping electric hammer does not work or malfunction
Causes: (1) Circuit failure; (2) The energization time is not synchronized with the hammer action; (3) The spring resilience is insufficient.
Processing: (1) repair circuit; (2) adjust the power-on action time; (3) replace the spring.
4.13 Self-controlled agenda system failure
Reasons: (1) The instrument itself is out of order; (2) The instrument line is in poor contact or aging; (3) The air source system is unstable or the air line is leaking; (4) The action mechanism is damaged.
Handling: (1) repair or replace the instrument; (2) exchange or repair the instrument line; (3) trap leakage regulation; (4) repair and adjust the action mechanism.
4.14 The air volume is too small
Cause: The filter pressure difference is too small
Disposal: Check the filter to see if it is clogged. Under normal circumstances, the initial filtration should be cleaned every shift.
4.15 atomizer oil leakage
Cause: Negative pressure is too high
Treatment: adjust the pressure of the spray tower cylinder so that its negative pressure remains ≤3000Pa
5 Conclusion
This paper starts with the introduction of centrifugal spray dryer and discusses the use, maintenance and troubleshooting of centrifugal spray dryer. The purpose is to enable a centrifugal spray dryer having a large evaporation area, a short drying time, and less damage to active ingredients to exert a greater effect.