GB807857A - Improvements in or relating to distillation apparatus - Google Patents

Abstract

<PICT:0807857/III/1> <PICT:0807857/III/2> Vacuum distillation apparatus comprises a surface of revolution which has an upright axis and is arranged to be heated, means for supplying liquid to the surface so as to flow downwardly thereover in a film, a member mounted for rotation about the axis, and a plurality of wiper elements mounted one above the other with respect to the axis of the member and arranged to rotate with the member, each element having an axial length less than the axial length of the surface and being free to move radially independently of the other elements so as to engage the surface under centrifugal force as the member is rotated. Distilland is pumped through a pipe 88 (Fig. 1) into a tubular shaft 37, which is rotated by a pulley 67, and then through a needle valve in an assembly 91 by pipes 109 to nozzles 111, the volume delivered to the nozzles being proportional to the pressure of the distilland. The distilland is sprayed by the rotating nozzles on to a heated cylindrical vaporization surface 61, down which it flows as a film which is thinned by wipers 116 mounted in channels 113 rotating with the nozzles 111. The wipers 116 are loose in the channels 113 and shift outwardly by centrifugal force to contact surface 61. Half the wipers have surface-engaging ports on their upper and lower edges with cut-back portions between, and the other half have cut-back portions on their upper and lower edges with surface-engaging portions between, the wipers being mounted in the same horizontal plane complementary to each other. As the wipers rotate the surface-engaging parts thin the film on the surface 61, surplus liquid passing through slots in the wipers to be thrown back on the surface by centrifugal force and redistributed by the cutback portions and then rewiped again. The pressure of the wipers on the heated surface 61 is controlled by varying the speed of rotation of shaft 37. Distillate condenses on a cooled coil of piping 47 and drips into a trough defined by a wall 28 and flows through an outlet 38. Residue flows into an annular collector 59 and through an outlet 62. A condenser 126 cools the lower wall 17 of the apparatus forming condensate which flows through the outlet 39. A vacuum is applied through a conduit 33. The upper part of the apparatus forms a high vacuum distillation unit and the lower part a low vacuum unit. Both condensers 47 and 126 may be operated together to separate liquids of lower and higher boiling points from a mixture, or one or other condenser may be operated above. In a modification the unit has a sloping wall.