Feed stream is introduced to the evaporator, typically through a heat exchanger or preheating stage to bring the temperature of the solution close to the boiling point. The solution is then fed into the evaporator chamber maintained at low pressure by a vacuum pump.

This low-pressure environment allows the solution to boil at a lower temperature than normal atmospheric conditions, reducing the amount of heat required to achieve evaporation.

As the solution is heated, water vapor is released and condensed on the cooler surfaces of the evaporator chamber. This condensed water is collected and removed from the system, leaving behind a more concentrated solution which can be further processed, recycled, or disposed of as needed.