Crystallization vacuum evaporator with a heat pump

  • Concentrate in semi-solid state
  • No liquid waste
  • Reusable concentrate
  • Suitable for highly concentrated inlet solutions
  • Suitable for thermally instable and highly corrosive solutions
  • Best performace at low volumes of inlet solution
  • Batch operation

Crystallization vacuum evaporators AQUADEST-KR uses circulation heat pump as a cooling and heating element. Vacuum is provided by ejector jet.

Crystallization vacuum evaporators AQUADEST-KR can be used as a second step of concentration. First step of concentration can be made by using evaporators AQUADEST-D or AQUADEST-K. Concentrate out of these two evaporators can be fed into AQUADEST-KR and further concentrated up to semi-solid state. This sollution achieves highest reduction of concentrate volume.

Semi-solid concentrate can be transformed to solid state crystals using Big-bags. Crystals can be then either reused in the production process or has to be disposed. The leachate from Big-bag is fed back to inlet of crystallization vacuum evaporator. Therefore there is no liquid waste that would need to be otherwise disposed.

The pressure in the boiling chamber is 6-7 kPa. The boiling point of water is at 35-40 °C. Energy consumption per one liter of distillate starts at 0,2 kWh.

Solution for:

  • Concentrated waste waters
  • Concentrates from membrane separation processes (retentates - Reverse osmosis)
  • Rinse water after quenching in salt baths
  • Waste water containing solid insoluble solution
  • Further concentration of concentrate out of AQUADEST-D and AQUADEST-K

Material options for AQUADEST-VR:

  • Stainless steel 316 L/Ti
  • Super-duplex SAF 2507
  • Nickel alloy 2.4819

Material is always designed with respect to inlet solution.

Technology process

Inlet solution is fed into the boiling chamber, where it heats up through heating jacket of the heat pump. The solution doesn't circulate in the boiling chamber.

Due to heating and low pressure in the boiling chamber the solution boils. Evaporated part of solution rises to the top part of boiling chamber, where it condeses on cooling heat exchanger of the heat pump.The condesed part is called distillate. Distilate is sucked out of heat exchanger with the ejector jet into retention tank, later out of the evaporator.

Unevaporated part of the solution stays in the boiling and forms crystals on the surface of boiling chamber. To ensure maximal effectivity of heat transfer, evaporater is equiped with the scraper which continously wipes the surface clean.

Heating and cooling is provided by the heat pump circuit. This circuit is made out of two heat exchangers, a compressor and a fan. Freon-free coolant is used as a medium in the heat pump circuit.

Our crystallization evaporators are characterized by batch operation. This means that the inlet solution is fed into the boiling chamber. Once it reaches desired maximum concentration, the whole volume of boiling chamber is released. When the batch is released automatical cleaning system cleans the inside of the boiling chamber with the distillate. During the evaporation fresh inlet solution is continously fed into the boiling chamber to increase the volume of concentrate for a single batch.

Product portfolio

  Distillate production [l/day] Operational performance [kW]
AQUADEST - KR 250 250 3
AQUADEST - KR 500 500 5
AQUADEST - KR 1 000 1 000 9
AQUADEST - KR 2 000 2 000 17
AQUADEST - KR 3 000 3 000 25