For achieving rapid drying rate in a spray dryer, the diameter of the particles in the feed should be in the range of __________ microns (1 mm = 1000 microns).

ANS:B - 10-60

Certainly! In spray drying, the size of the particles in the feed material plays a crucial role in determining the efficiency and effectiveness of the drying process. Here's an explanation of why a particle diameter range of 10-60 microns is preferred for achieving rapid drying rates:

1. Surface Area: The surface area of a particle increases as its diameter decreases. Smaller particles have a larger surface area relative to their volume compared to larger particles. In the range of 10-60 microns, particles have a sufficiently large surface area to facilitate rapid evaporation of moisture during the drying process.
2. Moisture Removal: The primary goal of spray drying is to remove moisture from the feed material. Smaller particles offer more surface area for moisture to evaporate from, leading to faster drying rates. This is crucial for achieving high throughput in industrial-scale spray drying operations.
3. Uniform Drying: Having particles within the 10-60 micron range helps to ensure uniform drying throughout the material. If particles are too large, the drying process may be slower and less uniform, leading to variations in product quality. Conversely, if particles are too small, they may agglomerate or form clumps, hindering the drying process.
4. Handling and Processing: Particles in the 10-60 micron range are typically easy to handle and process in a spray dryer. They can be effectively dispersed in the drying chamber and maintain a consistent flow throughout the process. This contributes to the overall efficiency and reliability of the drying operation.