GB998022A - Improvements in apparatus for treating liquid in the form of a film - Google Patents

Abstract

998,022. Evaporators of the film-type. LUWA A.G. Nov. 13, 1961 [Nov. 14, 1960], No. 40525/61. Heading B1B. In the evaporator shown the liquid to be evaporated, supplied through pipe 7, is distributed as a film over the hot inner surface of tubular wall 5 by radial blades mounted on a rotary shaft 3, and the blade assembly comprises two sections, the upper section consisting of rigid blades 13b extending almost to wall 5 and the lower section consisting of blades 16 connected by rings 15 to supports 13a so that they move towards or away from the wall 5 when the speed of rotation is increased or decreased, respectively. The rotating blades 13b in the upper section continuously agitate and respread the film on the inner surface of wall 5 and promote evaporation. In the lower section of the evaporator the blades 16 are flung outwards by the rotation of the shaft so that they bear against wall-surface 5, spreading the liquid in a thinner film on the surface. In a modified construction, there is slight clearance between wall-surface 5 and the outer edges of blades 16 in their most radiallyextended position. The concentrated liquid is withdrawn from the evaporator via pipe 6, and the vapours pass out of the top of the evaporator via a separator 2. The evaporator casing is provided with two jackets 8 and 9, through which heating fluid or cooling fluid may be passed, thus producing a temperature gradient down the evaporator if desired. The fastening arrangement between the supports 13a and the blades 16 is such that the blades may be easily removed for cleaning.