Re-circulation evaporator for “Potato juice”

SiccaDania has developed a concept called “One-In-All-Out”. A concept that can be applied to the worldwide industry of starch manufacturing - proven for potato juice and chemical wastewater and good for many more applications.

SiccaDania has, in close cooperation with the Danish potato industry developed a concept called “One-In-All-Out” with a unique potato evaporator. The One-In-All-Out concept 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 are retained. 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.

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. The recovered water is 41.600 kg/h, which means only 3.400 kg/hr of 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 meters and a weight of app. 110 ton.

Under vacuum, the water is boiled off 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 led to the shell side of the calandria, where it condenses. The latent heat of the vapour is used for boiling water at the tube side.

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

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

As the plant is built as a recirculation evaporator the amount of water in each pipe is easily adjusted to a flow that 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 are 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 wastewater
  • 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 that is non-heat sensitive and for non-human consumption

Formerly, the same re-circulation evaporator technology has been used for:

  • Concentrating NaOH for reuse in the dairy industry
  • Concentrating sodium sulphate for cleaning wastewater from aluminium manufacture
  • Concentrating copper sulphate for cleaning wastewater from print plate manufacturer
  • Concentrating boiled water from frozen vegetable production – this was then used as animal feed