Die surface hot pelleting system-Spray granulation
There are many different pelletizing line designs on the market, which are divided into two categories according to the arrangement of the pelleting process time: cold pelleting system and die surface hot pelleting system.
There are three basic types of die heating systems, namely spray pelletizer, water jet (water ring) pelletizer and underwater pelletizer. The typical composition is similar to that of a cold cutting system and includes a die, a cutting chamber, an electric rotary blade knife, a cooling medium, and a method of drying the pellets (if water cooling is used).
Spray granulation machine, spray granulation is the solution, slurry or suspension spray in the hot air flow of the drying room with the atomizer, so that the solvent (water) quickly evaporated and dried to prepare fine particles. It consists of two processes: spraying and drying. The process of concentration, drying and granulation is completed in a few seconds, and the water content of the raw material liquid can reach 70%~80%. The process for drying is called spray drying, and the process for granulation is called spray granulation. The liquid is first sprayed into mist droplets, and after the water is evaporated by the hot air, the solid phase in the droplets will gather into dry particles. Spray granulation is almost the only method for preparing fine particles with an average particle size of tens to hundreds of microns using micron and sub-micron ultrafine systems.
Common applications: chemical, pharmaceutical, food and other industries.
In the process of spray granulation, the droplets evaporate after heat, the water gradually disappears, and the solid particles contained in them gradually concentrate, and finally agglomerate into the required particles under the action of liquid bridge force. In the process of changing from fog to particles, collision will also occur, coalesces into a larger micronucleus, and the coalescence of micronucleus and the adsorption coating of particles on the nucleus are the main mechanism for the formation of larger particles. The above process must be completed before the water in the particles is completely removed, otherwise the particles will be difficult to increase again. After drying, the liquid bridge is transferred to the solid bridge, and the dry particles are combined with the fixed bridge force. However, because there is no external force, the strength of the particles prepared by spray granulation is not very high, and it is porous. The size of the droplets and the concentration of the liquid determine the size of the primary particles. The lower the concentration, the better the atomization effect, the smaller the primary particles formed, but limited by the amount of water evaporation, the concentration of the feed liquid can not be too low. The process of agglomeration and cladding of particles can be controlled by changing the hot air movement law in the dry chamber, so as to adjust the particle size of the product. The amount and temperature of hot air blowing can directly affect the drying strength and the retention time of the material in the dryer, which is also a means to adjust the particle size of the product. However, the range of particle size adjustment in spray granulation is very limited.
More information or request about the blades, please contact SHJ knife.
