Drum dryers, coolers/ Vacuum drum dryer

Drum dryers are film dryers in which the product only comes into direct contact with the necessary drying temperature for a few seconds therefore ensuring particularly quick drying.
With this type of drying, the product to be dried comes into extensive contact with the heated drums. 
Thanks to the many years of experience of DVA, this drying procedure can be implemented in a way more gentle to the product by using a vacuum.

Various application possibilities

  • Used for the drying of solutions, suspensions and/or doughy or pasty substances.

Principle of two-drum dryers/coolers

Drum dryers are used for the continual drying of solutions, suspensions and pastes of different consistencies and viscosities. The drums are usually heated with steam or thermal oil. Using a dosing system, the wet product is distributed between the drums. The gap between the drums can be set between 0.1 and 2 mm.

The wet product applied is distributed evenly on the hot drums and the moisture content evaporates during the partial rotation of the drums. After approximately a ¾ turn, the now dry product is removed by a scraper. Depending on its consistency, it falls as a film, in scales or as a powder and can be fed into the next processing stage via the appropriate conveyor.


Operation at normal pressure and vacuum possible.

The apparatus consists of a sturdy metal housing, which contains the drums, scraper and the loading and discharge mechanisms.

 

Principle of one-drum dryer/cooler


In principle, the one-drum dryer/cooler functions similarly to the two-drum dryer/cooler.
In this apparatus, product application takes place however via a product sump and is sprayed out and/or is applied from above via product application drums.
The dried product is removed by a scraper and can be fed back in for further processing.

Vacuum drum dryers are always used when products to be processed are temperature-sensitive and easily disintegrate or oxidise during the drying process.

 

Materials 

  • The drum surfaces are usually made of hard chrome-plated or specially coated hard metal. 
  • The drum body consists of GG and/or a welded construction of carbon steel or stainless steel.
  • The housing is usually stainless steel.

Drum cooler


In drum coolers, whether one or two-drum coolers, heat is removed from the product. Drum coolers are primarily used for the crystallisation of saturated solutions and for the cooling and freezing of melted products.

The drums are cooled with water or brine. The crystallised, chilled and solidified product adheres to the surfaces of the cool drums, is removed from there with scrapers and is usually fed into the next processing stage in scale form via the product exit or is packaged. Roller coolers are characterised in comparison to other continuous freezing procedures by their simple process control and high user-friendliness.

Application possibilities:


  • Cooling and freezing of melted substances and suspensions for the production of homogenous structures.

 

Product result/procedural parameters


The product result is influenced by the following procedural parameters:

  • Operating speed of the drums
  • Temperature
  • Drum gap
  • Vacuum (if present)

Process and procedure optimisation


Vacuum drum dryers are always used when products to be processed are temperature-sensitive and easily disintegrate or oxidise during the drying process.