Alaqua products

In falling film evaporators the liquid product usually enters the evaporator at the top. In the top head the product is evenly distributed into the heating tubes. A thin film enters the heating tube and flows downwards at boiling temperature and is partially evaporated. In most cases steam is used for heating the evaporator. The product and the vapors inside the heating tubes both flow downwards in a parallel flow. This gravity-induced downward movement is increasingly augmented by the co-current vapor flow. The separation of the concentrated product from its vapor takes place in the vapor separator.

These operate on a “thermo-siphon” principle. Feed product enters the bottom of the heating tubes and as it heats, steam begins to form. The ascending force of this steam produced during the boiling causes liquid and vapors to flow upwards in parallel flow. At the same time the production of vapor increases and the product is pressed as a thin film on the walls of the tubes, and the liquid rises upwards. This upward movement against gravity has the beneficial effect of creating a high degree of turbulence in the liquid. This is advantageous during evaporation of viscous products and products that have a tendency to foul the heating surfaces.

In evaporators with MVR, the heating medium in the first effect is vapor developed in the same effect, compressed to a higher temperature by means of a fan or blower (MVR).