Introduction to Spray Drying Coffee

Spray drying coffee is used in the production of a wide variety of consumer goods, from the food we eat, to the medicines that keep us safe and healthy.

It is used throughout the food manufacturing and pharmaceutical industries to rapidly dry liquid product feed into a powdered material using heated gas for a variety of consumer and industrial applications.  

The process begins when a liquid coffee feed is passed through a special nozzle called an atomizer.

The atomizer disperses the liquid stream as a mist of fine droplets into a heated gas atmosphere to facilitate the drying process. There are various nozzle designs such as pressure nozzles and rotary nozzles. The type of atomizer used will vary by application.  

example of spray drying coffee

As the product feed is dispersed into the drying chamber the droplets rapidly dry as the liquid evaporates the dried particles fall through the drying chamber for collection using a variety of methods and packaging.

 For further processing and distribution, the heating gas is vented back into the atmosphere.

 This is the simplest form of spray drying coffee otherwise known as a single pass system.

Several major components make up a typical spray drying system the process begins when the product feed is delivered from the feed tank through the feed line to the atomizer which is located at the top of the drying chamber.

Drying gas is introduced to the drying chamber through the inlet heap. 

The atomizer disperses the product feed as a fine mist of droplets into the drying gas.

Once the coffee has dried the particles pass through the system to the collection chamber where the material is deposited into powder bags.

 The heating gas is then vented out through the outlet heap.

 In any spray drying system there are several key control variables that affect the success of the process.

Feed rate, inlet temperature and outlet temperature these variables are all tied together by the boundary value of drying gas flow.

 The drying gas flow is usually held steady at a high value while the others get adjusted to optimal levels for production.

 On any given coffee, the specific method of adjustment will vary by system design and setup.

Spray drying systems can exist across multiple floors and through multiple graded spaces. 

More importantly a lot of what happens is often occurring between floors because the spray drying operation can consist of equipment that passes through multiple levels.

It’s important to understand the scale of the entire operation and not just what is visible on any given floor at the most basic level.

A spray drying coffee system is composed of a feed tank atomizer drying chamber collection chamber

Heater control panels intakes exhausts and various fans and pumps.

 All these components are connected and work through a series of ducts to help move the products and gases through the system during production.

Like any complex system there are safety factors that must be considered.

 The most important safety aspects for the common coffee spray drying operation are asphyxiation powder contact and explosion control. 

Depending on the type of drying gas in use, asphyxiation can pose a significant danger.

Gas leaks can be hazardous or fatal without the proper safety precautions and monitoring equipment.

 If the spray drying coffee process is being used for material that includes an api powder, contact with the skin can pose a danger to operators.

Api mixtures can be considered potent which means that inhalation and or human contact with the powder can produce an effect even at low doses.

Explosion risks are also a very real danger dust gas and heat can all serve as potential trigger points for disaster.

Dust for example can be exponentially more explosive than dynamite.

Explosion controls to mitigate the danger include redundant kill switches fire suppression systems and even explosion vents.

The explosion coefficient and flammability of the product will ultimately dictate the design and implementation of the explosion suppression system.

Spray drying coffee is just one of the many steps that it takes to deliver products to the consumer

It is a critical component in the manufacturing chain with its own unique systems processes and safety considerations.