The working principle of spray dryer:
After the air passes through the filter and the heating device, it enters the hot air distributor on the top of the drying chamber. The hot air passing through the hot air distributor evenly enters the drying chamber and flows in a spiral shape. At the same time, the material is sent to the centrifugal installed on the top of the drying chamber. In the spray head, the material liquid is atomized into very small mist droplets, which greatly increases the surface area of the material liquid and the hot air, and the water evaporates quickly, forming a dry product in a very short time.
The spray dryer has fast drying speed, high efficiency, few procedures, and manpower saving. Especially for heat-sensitive materials, it can maintain its color, fragrance, and taste, and the product quality is excellent. problem. The possible problems in production and their causes and remedial measures are summarized as follows for reference during operation.
The wall sticking phenomenon is serious (there are sticky wet powder everywhere in the dry room)
Reasons: 1. The feed volume is too large to fully evaporate
2. Before spraying, the drying chamber is not heated enough
3. When starting to spray, the unloading flow rate is adjusted too large
4. The added liquid is unstable
Solution: appropriately reduce the feed volume; appropriately increase the inlet and outlet temperature of the hot air; at the beginning of spraying, the flow rate should be small, gradually increase, and adjust until appropriate; check whether the pipeline is blocked, adjust the solid content of the material, and ensure the material Liquid fluidity.
Product moisture content is too high
The exhaust air temperature is the main factor affecting the moisture content of the finished product, so the reason for the high moisture content of the product is generally that the exhaust air temperature is too low. The exhaust air temperature can be adjusted by the amount of feed. Therefore, the corresponding measure is to appropriately reduce the feed volume to increase the exhaust air temperature.
Low product purity and excessive impurities
Reason:
1. Poor air filtration
2. The powder is mixed into the finished product
3. The purity of raw materials is not high
4. The equipment is not cleaned thoroughly
Solution: Check whether the filter material in the air filter is evenly laid and whether the filter has been used for too long. If it is too long, it should be replaced immediately; check the coke powder at the hot air inlet to overcome the vortex; filter the material liquid before operation; clean the equipment again.
Product powder is too fine (too fine product particles will affect its solubility and preparation performance)
Reason: The solid content is too low or the feed volume is too small.
Solution: increase the solid content of the material liquid, increase the feed volume, and increase the inlet air temperature.
The phenomenon of running powder is serious (the product yield is low and the loss of running powder is too much, which greatly affects the yield of the finished product)
Reason: The separation effect of the cyclone separator is poor.
Solution: If this happens, check whether the cyclone separator is deformed due to knocks or collisions; improve the air-tightness of the inlet and outlet of the cyclone separator, and check whether the inner wall and the discharge port are blocked by material accumulation. Of course, the separation efficiency is also related to the specific gravity and particle size of the powder. For some materials, a second stage of dust removal can be added as needed.
Centrifugal nozzle speed is too low
The main reason is that the parts of the centrifugal nozzle are out of order, so stop using the nozzle and check the internal parts of the nozzle.
Evaporation is too low
Reason:
1. The air volume of the entire system is reduced
2. The inlet temperature of the hot air is low
3. The equipment has air leakage and cold air enters the drying room
solution:
1. Check whether the speed of the centrifuge is normal
2. Check whether the position of the centrifuge regulating valve is correct
3. Check if the air filter and air heater pipes are blocked
4. Check whether the grid voltage is normal
5. Check whether the electric heater is working properly
6. Check whether the connection of each component of the equipment is sealed
There is noise or vibration when the centrifugal nozzle is running
Reason: Mainly due to the improper cleaning and maintenance of the nozzle, the residual material in the nozzle or the bending and deformation of the spindle may be caused by the poor dynamic balance of the centrifugal disk.
Solution: Check if there are any residual substances in the spray plate, if there is any, clean it in time; if the spindle is found to be abnormal, replace it; re-adjust or replace the dynamic balance of the centrifugal plate.
