The atomizer is one of the important parts of the spray dryer. The amount of cold air required should be calculated according to the thermal balance.
The composition of each part is basically the same as that of the spray dryer, only the heat source is changed to the refrigerant. The refrigerant can be cold water, ice water, brine, fluorine, ammonia, etc. For cooling at room temperature, no cooler is required.
Generally speaking, spray dryers are similar to spray dryers, but they still have absolute advantages over spray dryers in some fields. At present, spray cooling technology has just developed in China and has not yet been promoted. The maturity of technology believes that spray cooling technology will have a unique value in the industry.
For the spray dryer, the atomizer can be said to be one of the important parts in the spray dryer, and the drying effect depends largely on the atomization effect. Starting from the study of the atomization mechanism, the study of spray drying technology is also necessary.
The effect of atomization is to improve the effect of spray drying and increase the dispersion of the solution to a large extent. Only increasing the surface area can increase the drying speed and shorten the drying time. In general, we are divided into 3 types: drip, filament, and film atomization. There are three common atomizers: the rotary atomizer, pneumatic atomizer, and pressure atomizer.
1. Rotary atomizer: The viscosity and surface tension of the solution affect the atomization process. When water droplets form, they are thrown from the edge of the disc. The wheel speed and feed solution speed are high, and the material is drawn into many liquid filaments in a hemispherical shape. As the fluid volume increases, the fluid volume also increases. When saturation is reached, the liquid filaments become thicker, but the number is constant. The liquid line is easily broken into small droplets.
2. Pneumatic atomizer: The difference in gas-liquid velocity is very small. When the wind speed is large, the friction of the liquid saw is very large. One end of the liquid column is fixed, and the other end is drawn into an elongated line. Water droplets formed after the fracture was completed.
3. Pressure atomizer: the solution flows out from the nozzle, and the droplets are split into droplets. The cause of this phenomenon is the formation of surface tension, forming unstable cylindrical droplets. Because the diameter of the liquid flow is smaller than the average, a liquid film is formed at this location. Because the surface tension of the film is greater than the thickness of the film, the liquid will transfer to a thin place, become a long line, and then be divided into droplets. As the solution gradually increases, the liquid column will vibrate in the horizontal and vertical directions. A solution to the spiral vibration of filaments, which breaks down into many small droplets quickly at the ends of the filament.