Drying of Foods: Part II. Spray Drying
Spray drying is a unit operation widely used in the food processing industry. A spray dryer system has five essential elements: an air heater, drying chamber, system for dispersing material to be dried as droplets in the drying chamber, system for collecting dry particles from the air, and one or more blowers for moving air through the system. Indirect heating is often used in the food industry to avoid contamination of food with carbon or dirt from fuel and contact with combustible products that could impart foreign flavors or odors. The advantages of the operation are that the process is continuous and adaptable to full automatic control, which increases product output without adding labor. The purpose of the laboratory exercise is to familiarize the student with a spray-drying operation and some variables that affect the characteristics of the final product. Determination of heat and mass balance will be practiced to find the thermal and evaporative efficiency of the system.