DESALT MVR FC crystallizer is a vacuum evaporation unit by mechanical vapour recompression (MVR) and forced circulation (FC).

This crystallizer uses the Roots blower to compress the vapour which is evaporated from the wastewater to rise its temperature and pressure. This vapour is reused as heating source to evaporate the wastewater again.

Our evaporators DESALT MVR FC 1500-2500

Main features

  • Fully automatic operation (working cycle 24 hours/day).
  • Evaporation occurs thanks to vapour recompression generated by a Roots type vacuum pump.
  • The crystallizer uses saturated steam for start-up and during operation.
  • Supporting structure made of stainless steel AISI 304.
  • Wastewater inlet and condensate outlet automatically operated.
  • Digital and analogue control instruments for the automatic monitoring of the system.
  • Control by PLC Siemens S7; display of main parameters by LCD Touch Screen.
  • Cylindrical evaporation vessel vertical type with conical bottom to make the separation of solids easier.
  • Evaporation vessel incorporates an outer jacket heat exchanger to provide a small amount of steam during the heating phase as well as during operation for temperature maintenance.
  • Evaporation vessel fitted with an external shell and tube heat exchanger. The process liquid flows inside the tube bundle at high speed, thanks to the recirculation pump, getting the calories necessary for the crystallization, thus avoiding the stratification on the exchange surface.
  • Manual valve for taking product samples during processing.
  • The vacuum pump (Roots-type blower) draws off the water vapour from the evaporation vessel, compressed it to atmospheric pressure and pumps the compressed vapour to the condensation area (shell and tube heat exchanger) of the evaporator. The vacuum pump is driven by V-belts from the electric motor located underneath the vacuum pump.
  • Condensation of the evaporated wastewater takes place in the shell and tube heat exchanger through which the water to be treated passes.
  • The condensate is stored in a distillate tank and discharged by means of the distillate pump controlled by level switches.
  • The pre-heater transfers the heat of distillate to the in-flowing wastewater.
  • Automatic circuit for concentrate discharge with extraction pump, pneumatic and manual valves.
  • The automatic discharge function is programmable by a timer for a complete customization of the process.
  • Other control devices for concentrate discharge (conductivity or density meter) on demand.
  • The automatic system is complete with pneumatic valve and rotating nozzle. The circuit allows the dosage of cleaning agents inside the crystallizer. The wash cycle time can be adjusted from the control panel according to the actual needs.
  • Automatic system with foam formation sensor and variable setting control. The circuit allows the automatic injection of antifoam products inside the crystallizer: the quantity of injected antifoam is adjustable by the control panel according to the actual needs.
  • Siemens PLC control unit and touch screen control panel.
  • Electrical panel, protection IP 54.
  • Automatic overload cut-out for all motors.
  • 24 volts auxiliary circuit.
  • Wiring made in flame proofs cables.
  • Level control regulators for tanks and outside reservoirs level.

Technical specs

Parameters DESALT MVR FC 1500 DESALT MVR FC 2500
Distillate production per hour/minute (1) 1500 L/h (6.6 GPM) 2500 L/h (11 GPM)
Absorbed power - 160 kWh
Electrical consumption (2) 64 kWh/m3distillate
(0.242 kWh/Gdistillate)
64 kWh/m3distillate
(0.242 kWh/Gdistillate)
Saturated steam <3 barg
in operation/Heating phase
110/180 kg/h
(243/397 Lb/h)
180/300 kg/h
(397/661 Lb/h)
Evaporation temperature 90°C (194°F) 90°C (194°F)
Dimensions (L x W x H) (3) 7300 x 2200 x 6200 mm
(23.95 x 7.22 x 20.34 ft)
8100 x 2450 x 7511 mm
(26.57 x 8.04 x 24.64 ft)
Electrical characteristics (4) 400 V III + N + Pe / 50 Hz 400 V III + N + Pe / 50 Hz

(1) Data refer to clean water when working continuously in standard conditions (T = 20 °C, P = 1013 mbar).
(2) Electricity consumption expressed in kWh per m3 of distillate produced.
(3) Dimensions are approximate and should be verified during the detailed engineering phase.
(4) Other voltage on demand.


Description SAF 2507 AISI 904L
Supporting structure AISI 304 AISI 304
Vertical evaporation vessel Upper side AISI 316
Lower side SAF 2507
Upper side AISI 316
Lower side AISI 904L
Shell and tube heat exchanger Tube side SAF 2507
Shell side AISI 316
Tube side AISI 904L
Shell side AISI 316
Vacuum pump (Roots blower) Rotors: cast iron
Casing: cast iron
Rotors: cast iron
Casing: cast iron
Valves, pipes and components in contact with concentrate SAF 2507/GRP AISI 904L
Valves, pipes and components in contact with distillate AISI 316 AISI 316
Other valves, pipes and components (antifoam, cleaning) AISI 316 AISI 316