DIFFUSION


Prescalding

Important energy savings can be obtained by the installation of a prescalder.
The juice is heated with calories which would otherwise be lost and therefore leads to lower overall energy consumption.
Two types of equipment can be contemplated: the belt type (De Smet type) and the mixer type.
The choice of equipment depends on the cossettes Siline length of and therefore on the diffusion type installed.
A well selected prescalder can lead to up to 20% energy savings.

The design of the De Smet Prescalder is based on the well proven De Smet continuous diffuser used worldwide in the sugar industry.

The specific feature of the De Smet Prescalder is that a very thick layer of freshly sliced cossettes
is spread onto a perforated conveyor belt system, whereby:
  • cossettes do not mix or rub or spoil and their physical qualities do not deteriorate,
  • the total amount of draft juice drawn off from the diffuser is completely cooled down,
  • the layer of cossettes is sprayed by warm draft juice, from a carefully selected number of juice distributors,
  • cossettes residence time in the Prescalder is of short retention time,
  • the short retention time of draft juice in the Prescalder prevents fermentation,

The De Smet Prescalder is not fitted with foam breakers, since there is no foam formation.
Its installation into existing factories is also extremely easy.


Beet diffusion

Several types of beet diffusers exist:

  • Horizontal types : De Smet and RT
  • Vertical type

The choice of the type of diffuser depends on following factors:

  • extraction efficiency
  • juice quality
  • required draft
  • operating flexibility
  • available space
  • investment cost
  • maintenance cost
  • ease of operation

Cane Diffusion

The advantages of the cane diffuser process, as compared to the traditional milling process, can be listed as follows:

  • lower investment cost
  • high extraction efficiency
  • better juice quality
  • lower maintenance cost

The De Smet cane diffuser is the most commonly used one in the world.

The operation of the diffuser is based on systematic counter current washing of the prepared cane by means of imbibition water.

In practice, this is achieved by forming a bed of prepared cane on a screen conveyor.
Water is added at the discharge end of the conveyor and percolates through the bed of material and belt conveyor.
The water extracts the sugar and the thin juice thus formed is collected in a hopper.
This juice is moved forwards by pumping until the juice reaches
maximum concentration at the feed end of the diffuser.

Two types of De Smet diffusers are available :

  • The Bagasse Type diffuser to process first mill bagasse ;
  • The Cane Type diffuser to process shredded cane .

Main features of De Smet diffusers are as follows:

  • Simplicity
  • Efficiency
  • Low maintenance costs
  • Low operational costs
  • Mechanical reliability
  • Wide turn-down ratio