How spray drying works

Spray drying is the method of drying any wet material, called the liquid feed, by using a hot gas, usually just plain air as we breathe. However, some sensitive materials such as pharmaceuticals and ethanol demands for oxygen-free drying conditions. Here nitrogen gas is used because it is also very cheap.

The drying process
The drying process is usually a very fast one step process and thereby further handling of the material is eliminated. During the drying process the liquid feed is sent through an evaporator (sometimes also called an atomizer), which, as the name clearly states, atomises the liquid feed and produces extremely small droplets, which are further sent into the drying chamber. There are several different drying applications such as ddgs drying, Ring dryers, solids drying and Small scale dryers. Most often the technique is used in the food and pharmaceutical industry as part of the encapsulation process where the product is termed “the load”.

Example of the drying process
An example of a drying process is as follows: A substance (the load) is mixed and homogenized with an amphipathic (having both hydrophilic and hydrophobic properties) carrier. The mixing suspension is termed “the slurry” and is usually water. Then the slurry is sent into the drying chamber and heated to a temperature above the boiling point of water, thus enabling an efficient atomization. Note that the amphipathic properties of the carrier is extremely important for successfully producing these droplets.