Spray Drying: What Are The Benefits Of Spraying And How Does It Work?

A spray dryer is something that converts a liquid into a solid powder. It is used in several areas such as food processing, pharmaceutical industry, etc. The some spray dried products include instant coffee, milk powder, paint powder, egg powders, resins and detergents.

To say in simple words, spray drying system is what undertakes the complete process – right from receiving liquid feed at an end and packing into a container at the other end from where it is ready to transport.

However, sometimes, mainly in larger plants, a few other processes are added as to make the processing cost as much affordable as possible. Take for example milk processing plant where evaporation technologies are used to raise the feed solids as much as possible.

What are the advantages of spray drying?

Most industries where drying is required, use the spray drying method for its several incredible benefits. In addition to the benefits for mil processing plants, spray drying also has many benefits for pharmaceutical industry, such as:

·         Spray-drying is a scalable process for the production of dry pharmaceutical powders.

·         New devices enable pure drug nanonization and production of submicron drug carriers.

·         Controlling particle properties during process allows specific therapy applications.

·         Spray-drying is an effective means to overcome biopharmaceutical drawbacks of drugs.

·         This technology has become a key player for the production of inhalable drugs.

How does spray drying work?

There are different types of spray drying systems, and spray dryers come in various shapes and sizes but the way they work remains the same.

Spray drying is an evaporation process –widely used method to producing powder from liquids.

Basically, spray drying system has three main parts: a large chamber through which extremely hot air (or a different gas) is passed, a feed pump to supply raw liquid, and an atomizer that helps the formation of droplets.

In addition, there is a drum of cyclone which is used to collect the resulting products.

The solution is fed into spray dryer using a nozzle called atomizing device – which breaks down the feed solution into individual spheres. The work of nozzle is to make the droplets as small as possible and maximize the heat transfer and vaporization rate. The size of droplets varies, depending on the size of nozzles used.

Drying chambers is like a storage silos. The volume of the chamber depends on the heath exposure time required for the feed materials being dried. A burner heats the gas (often air) to force it into the main chamber where feed solution is atomized to develop into small droplets.

On contact with the hot gas the visible powder particles are case hardened, but the core is still in molten state.  The particles then are made to get into contact with hot air that strips remaining moisture from the rest of particles. And thus come out solid particles which are easily made into powder.