Drying/ concentration

With thermal drying, the moisture contained in a moist substance is brought into a gas state through warming and the resulting vaporisation or evaporation and the arising moisture vapour is drawn away. The dried commodity is created.

The apparatus, plant and machinery with which DVA carries out drying processes is called a contact dryer. DVA offers its customers nearly all apparatus for contact drying.

With contact drying, the commodity to be dried comes directly into contact with the heated tank or well wall.

The liquid which evaporates, i.e. becomes a vapour, is appropriately suctioned or transported away.

  • Bucket dryer
  • Drum dryer
 

A tank wall can also serve as a radiation source to implement so-called radiation drying. See picture.

The effectiveness and the entry of the temperature into the commodity to be dried is therefore considerably lower than with contact drying.

  • Conveyor dryer
  • Chamber dryer
 

In contrast to this is convection drying.

Here the commodity to be dried is dried with a heated air or gas stream. This procedure can be very energy intensive, particulalyr in the field of eddy-current drying. 

  • Chamber dryer
  • Conveyor dryer
  • Drum dryer
  • Vortex dryer
 

Drying commodities and residual moisture


Drying or solid-liquid separation processes overall are often defined by their so-called residual moisture. Here, when centrifuging residual moisture this refers to free (surface) water.

When centrifuging and pressing, a maximum residual moisture of 30-40% cannot usually be surpassed.

With the DVA contact dryer, residual moistures measured in ppm can be achieved and depending on crystal or pore structures, even water of crystallisation can be expelled at high temperatures and with the help of a vacuum.