Spray drying is a spray drying chamber, after the use of the raw material dispersion liquid atomizer into fine droplets, and drying medium (hot air) drying to obtain a process of contacting the solid product. Raw material liquid may be a solution, suspension or emulsion, liquid or cream may also be melted liquid paste. According to the requirements of the dried product can be made of powdered, granular, hollow spheres or granular group. Most of the drying medium used is air. But prone to combustion or explosion in the air the organic solvent should be used an inert gas (mostly with nitrogen) or the like as the drying medium. So, under what circumstances, to use closed loop spray dryer it? The following lists the seven kinds of situations, as follows:
1: starting material liquid from the solid and an organic solvent (into ethanol, acetone, etc.) composition;
2: Requires full recovery of organic solvents;
3: dry powder, granular solid toxic products;
4: Do not allow odor, solvent vapors and particulate matter to escape and prevent air pollution to the environment;
5: Dust in the air, may form explosive mixtures;
6: You must prevent the explosion of organic solvents and fire danger;
7: During the drying process, due to oxidation, dust and does not allow contact with oxygen.
When any one of the above, it must choose a closed cycle spray dryer.