Evaporation falls into the concentration stage of downstream processing and is widely used to
concentrate foods, chemicals, and salvage solvents. The goal of evaporation is to vaporize most
of the water from a solution containing a desired product. After initial pre-treatment and
separation, a solution often contains over 85% water. This is not suitable for industry usage
because of the cost associated with processing such a large quantity of solution, such as the need
for larger equipment. Evaporators are used for reducing product volume, remove water prior to
drying, and to improve product storage life.
Evaporation Process Principles
Evaporation is an operation used to remove a liquid from a solution, suspension, or emulsion by
boiling off some of the liquid. It is thus a thermal separation, or thermal concentration, process.
Evaporation is a highly energy-efficient way of removing water or other liquids and thus the
primary process for the production of concentrates. Process time can be shortened by distributing
the liquid to a greater surface area, or by using a higher temperature. Higher temperatures
combined with longer residence times can, however, cause degrading of many foodstuffs.
In most cases it is essential that the product is subject to minimal thermal degradation during the
evaporation process, requiring that temperature and time exposure must be minimized. This and
other requirements brought on by the physical characteristics of the processed product have
resulted in the development of a large range of different evaporator types. Additional demands
for energy efficiency and minimized environmental impact have driven development toward
very innovative plant configurations and equipment design.
Criteria for Selection of Evaporator Plant Concept
During the design of evaporation plants, numerous, sometimes contradictory, requirements have
to be considered. They determine which type of construction and arrangement is chosen, and the
resulting process and economic d