Evaporation technology for “Potato juice”

Proven for potato juice and chemical waste water, good for many more applications.

SiccaDania have, in close cooperation with the Danish potato industry developed a concept called “one in all out”. A concept which can be applied to the worldwide industry of starch manufacturing. The process is a three-step process: First the starch is removed. After, the byproduct is processed, and proteins regained. Finally, the residue is concentrated. The boiled water from the first process is reused in the rest of the starch process, thus reducing the water amount. The concentrate is used as fertiliser in the potato fields, thus adding vital minerals to the ground. Before the use of the “One In All Out” process, the residue from the protein process was also returned to the fields, however in a non-concentrated form, which significantly increased the transportation costs compared to the new set-up.

Calandria with wrap around vapour/liquid separator

Calandria with wrap around vapour/liquid separator

The evaporator used for the purpose is a falling film re-circulation evaporator. Due to the huge water demand for processing potatoes the evaporator dimensions are huge. An example is the calandria (left side). This calandria is for 45.000 kg/h potato juice/hr. Recovered water is 41.600 kg/h, which means only 3.400 kg/hr concentrated fertiliser for transportation, thereby reducing the transportation cost. The biggest plant so far built has a feed of 90 ton/h. For this the calandria has a height of 32 meter and a weight of app. 110 ton.

Under vacuum, the water is boiled of in the calandria as vapour. This vapour is cleaned for droplets in a separator wrapped around the calandria itself, thereby reducing the plants footprint. The vapour is compressed in a special built centrifugal fan and lead to the shell side of the calandria, where it condenses. The latent heat of the vapour is used for boiling of water at the tube side.

The condensed water is the part which is reused as water elsewhere in the processes.

The energy consumption of the plant is 15-16 kW / ton water evaporated.

As the plant is built as a recirculation evaporator the amount of water in each pipe can be easily be adjusted to a flow which secures a long running time without compromising the feed flow.

To avoid manual work at the evaporator everything is computer controlled and the plant is built with cleaning in place (CIP). This plant will be cleaned once a week.

It is essential to the cleanness of the evaporated water that no or very limited amounts of components in the product is more volatile than water

Due to the flexibility of feed flow this type of plant should be considered in cases where one would like to remove water from a stream of fluid with limited solids in the stream. It could be:

  • Chemical waste water.
  • Chemical components.
  • Wash water from fruit and vegetable productions
  • Degassed manure from Bio-gas manufacture.
  • Pre-concentration of algae.
  • Products with solids up to 2-3 mm in diameter.
  • Reducing water in a product which is non heat sensitive and for non-human consumption.

Formerly the same technology has been used for:

  • Concentrating NaOH for reuse in dairy industry
  • Concentrating sodium sulphate for cleaning waste water from aluminium manufacture.
  • Concentrating copper sulphate for cleaning waste water from print plate manufacturer.
  • Concentrating boiled water from frozen vegetable production – this was then used as animal feed.
Insulated centrifugal fan for vapor compression.

Insulated centrifugal fan for vapor compression.