GB748307A - Film evaporator having an improved feeding means - Google Patents

Abstract

<PICT:0748307/III/1> A film evaporator of the type which has a cylindrical evaporating surface disposed in a vertical position is provided with a liquid feeding means comprising an annular compartment which is rotated inside the upper end of the heated cylinder, said compartment being bounded above and below by two horizontal flanges which extend closely adjacent to the inner surface of the cylinder and being supplied with liquid through an inlet which discharges into the open side of the compartment. The liquid flows from the compartment into the evaporator proper through the gap between the lower flange and the inner surface of the cylinder. The feeding means obviate the foaming of liquids, for instance glues, particularly when the evaporation is carried out in vacuo. In the Fig. the anular compartment 1 which is bounded by flanges 16 and 17 is U-shaped; it is connected to shaft 2 by spokes 19. A circular projection 4 is provided in the compartment, dividing it into an upper chamber 7 and a lower chamber 13. The evaporating surface 5 is heated by jacket 9; and the evaporator is maintained at subatmospheric pressure. Liquid is introduced through pipes 3 into chamber 13. The sudden drop in pressure and the heated surface cause flash-evaporization of part of the entering liquid; but projection 4 prevents liquid droplets being carried upwards in the rising vapours. Some of the vapour passes up through openings 8 in flange 17, and the remainder passes up through gap 18 between flange 17 and surface 5. The liquid flows downwards through gap 6 between flange 16 and surface 5 into the interior of the main evaporator 15. The vapours formed therein flow upwards through spokes 19. The united vapours leaving the top of the evaporator pass to a condenser (not shown). An embodiment is described wherein a ring and brush device is provided for the separation of entrained liquid from the vajour generated in the main evaporator.