Process info: Extraction in sugar production

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Sugar beet extraction (BAT for Food, Drink and Milk Industries, June 2005)

In general, the extraction of sugar from sugar beet or sugar crane is similar. The beets are cut into thin slices called cossettes. They are passed into a water-based countercurrent extraction apparatus, called diffuser, and emerge as impure sugar juice and beet pulp. The fresh water used in the extraction process is actually condensed water from the subsequent evaporation steps together with recurculated water from the pulp pressing. The temperature inside the diffuser is 68 to 72°C.

Description of equipment (BAT for Food, Drink and Milk Industries, June 2005)

Three types of diffusers are used:

a) Horizontal diffusers:

Horizontal diffusers are large revolving drums, separated into cells by a helix attached to the interior surface. As the drum and helix revolve, the juice, which stays at the bottom of the vessel, is transported countercurrently to the cossettes, i.e. the exhausted beet pulp leaves the diffuser at the same end where the fresh water enters.

b) Vertical diffusers:

Vertical diffusers are composed of an extractor with two main and distinct parts, i.e. the countercurrent mixer and the extraction tower. The tower is a 14 to 20 meters high cylinder. Inside the tower, a tubular shaft rotates slowly. Special helicoidal steel pieces, or flights, are fitted on the shaft and move the cossettes upwards. The juice and the cossettes move countercurrently.

c) Slope diffusers:

Slope diffusers consist essentially of a U-shaped sloping vessel in which two overlapping screws with opposite pitches rotate. Fresh cossettes fall from a conveyor belt into the tower end. The cossettes are transported upwards by the two screws to a paddle wheel, which lifts the exhausted cossettes out of the extractor. Fresh water is introduced at the upper end and the sugar juice leaves the extractor through a screen at the lower end.


a) Changes in the process

No information is available.

b) Changes in the energy distribution system
  • Use of evaporator condensate in sugar extraction: (BAT in the Food, Drink and Milk Industries, June 2005)
a) Description of the technology:
The use of evaporator condensate in sugar extraction from sugar beet results in less energy consumption.
b) Description of suitable energy supply systems:
A heat exchanger circuit will be used. Electricity will be consumed for pumping the condensate around the circuit.
c) Possible energy savings reachable by those measures:
No information available.
d) Economic evaluations:
No information available.

c) Changes in the heat supply system

No information is available.

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