PF evaporator is a plate evaporator working as a forced circulation flash evaporator. A pump recirculates the liquid between the cyclone separator vessel and the PF plate evaporator. The re-circulation creates a highly turbulent flow of the liquid inside evaporator. In the evaporator, boiling does not take place in the plate heat exchanger but the liquid to be concentrated is just heated under pressure. The actual evaporation takes place when the heated liquid is discharged to the separator vessel where the pressure is released and the liquid then flashes.
Vacuum is applied in the system to decrease the boiling temperature. The vacuum is created by condensing the vapour from the last effect in a condenser, e.g. the highly efficient and compact condenser. A vacuum pump is normally used to remove the non-condensable gases.
A complete PF evaporator system includes the plate evaporators, pre heaters, separator vessels, TVR or MVR, recirculation pumps, instruments, valves, ducting, piping and a control panel.