Introduction to spray dryer


Spray drying is a drying method that uses a atomizer to disperse the raw material liquid into droplets and dry the droplets with hot gas (air, nitrogen or superheated water vapor) to obtain products. The raw material liquid of spray drying can be solution, emulsion, suspension, or molten liquid or paste liquid. The dried products can be made into powder, granular The atomizer is the key component of spray drying



What is the working principle of spray dryer?


After being filtered and heated, the air enters the air distributor on the top of the dryer, and the hot air enters the drying chamber in a spiral shape. The feed liquid passes through the high-speed centrifugal atomizer on the top of the tower body, and the (rotating) spray becomes a very fine mist like liquid bead. The product can be dried into a finished product in a very short time by parallel flow contact with the hot air. The finished product is continuously output from the bottom of the drying tower and the cyclone separator, and the exhaust gas is discharged by the induced draft fan


What are the characteristics of spray dryer?


1. The tower body has a cold air jacket;


2. The tower is equipped with an automatic vibration device;


3. The tower body and pipelines are equipped with quick opening cleaning holes and drainage holes;


4. Automatic control of constant temperature feeding tank;


5. Manual high-pressure washing tower random accessories;


6. The part in contact with the material is made of stainless steel material; (or made entirely of stainless steel)


7. The material collection adopts a two-stage cyclone dust removal device, or a one-stage cyclone dust collector and a wet dust collector


8. Automatic control and continuous device for inlet air temperature;


9. Equipped with an air scanning device;



How to solve wall sticking of spray drying tower?


1. The material feeding speed is too fast and the amount is too large, resulting in incomplete drying


2. Failure to follow the instructions in the equipment operation manual and failure to heat the main tower of the equipment


3. The material itself has viscosity and will clump below a certain temperature (such as 60 degrees)



Solution:


1. It can slow down the feeding speed and adjust the feeding conveying pump appropriately


2. Increase import and export temperatures


3. Observe whether there is material blockage in the equipment


4. It is very important to select a good manufacturer. You can modify the spray drying and add an air sweep device and a cold air spacer sleeve


What is the cause of unstable pressure of spray drying tower?


1. The unstable negative pressure inside the tower can cause significant temperature fluctuations at the top of the tower. I'm not sure if your tower has a blower. If it's a dual fan, 1. If the two fans are running at an inappropriate frequency, you should choose the appropriate frequency to run. Generally, the blower frequency is only 50%


2. If there is positive pressure inside the tower, it should be controlled at a slight negative pressure at both the top and bottom of the tower


3. You can start the induced draft fan first, but not the blower, and check how much pressure fluctuates inside the tower, etc; For a single fan: check if the lower air inlet, fan impeller, etc. are normal or abnormal



What factors will affect the effect of spray drying tower?


For different materials, choose the corresponding atomizer to dry out the finished product with good effect. Changzhou Yuanze Drying spray Dryer atomizes. In fact, the atomization of spray Dryer is related to the product moisture, particle size, and wall adhesion. According to the different atomization methods of products, many users encounter uneven product moisture, particle size The problem of clumping and wall sticking on the tower or cone of the equipment is related to the moisture content, particle size, and wall sticking of the product



What should be paid attention to during the operation of spray drying tower?


1. Firstly, turn on the centrifugal fan, then turn on the heater and check for air leakage. If it is normal, preheating can be carried out. As hot air preheating determines the evaporation capacity of the drying equipment, the inlet air temperature should be increased as much as possible without affecting the quality of the dried material


2. When preheating, the atomizer should be placed at the top of the drying chamber, and the drying chamber and the discharge port of the cyclone separator must be sealed to prevent cold air from entering the drying chamber and reducing preheating efficiency


3. When the inlet temperature of the drying chamber reaches the set temperature, turn on the centrifugal nozzle. When the spray nozzle reaches the maximum speed, turn on the feed pump, add clean water and spray for 10 minutes, and then replace it with liquid feed. The feed volume should be increased from small to large, or wall sticking will occur until it is adjusted to appropriate requirements. The concentration of liquid feed should be prepared according to the drying properties of the materials to ensure good fluidity of the dried finished products


4. The temperature and humidity of the dried product depend on the exhaust temperature. It is extremely important to maintain a constant exhaust temperature during operation, which depends on the size of the feed amount. The discharge amount is stable, and the outlet temperature is relatively stable. 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 high, the feeding amount can be reduced to increase the outlet temperature. If the product temperature is too low, the opposite is true. For thermosensitive materials with lower product temperatures, the feeding amount can be increased to reduce the exhaust temperature, but the product temperature will correspondingly increase


6. Collect dried finished products. In the lower part of the cyclone separator, the pollinator should be replaced before it is fully filled. When replacing the pollinator, the butterfly valve on top must be closed before proceeding


7. If the dried product has hygroscopicity, the cyclone separator and its pipelines, as well as the parts of the pollinator, should be wrapped with insulation materials to avoid moisture regain and absorption of the dried product