It is usually selected for products which are highly viscous or in paste / syrup forms products having a tendency to scale or salt out during evaporation can also be handled in this evaporator. The rotating blades of this evaporators ensure that no material stays on the heat transfer surface for long duration thus preventing thermal degradation. The liquid flow can be bottom to top or top to bottom. This flow pattern depends on the fluid properties, chances of scale or crystal formation. This system can be used along with the falling film or forced circulation evaporators as last finisher stage.