Patent GB-825438-A (GB)
Title: Improvements in and relating to distillation apparatus
IPC: B01D3/10
Filed: 1957-03-15
Abstract: <PICT:0825438/III/1> <PICT:0825438/III/2> <PICT:0825438/III/3> <PICT:0825438/III/4> <PICT:0825438/III/5> <PICT:0825438/III/6> <PICT:0825438/III/7> Distillation apparatus comprises an upright cylindrical wall 31 (Fig. 1) surrounded by a heating-jacket 65, a horizontal rotatable plate 89 in the upper end of the cylinder, and wiper blades 133 which are mounted for rotation and sweep over the interior surface of the cylindrical wall, the working faces of the blades having oblique grooves or slots.  The apparatus is evacuated by a diffusion pump 221 which extends up through the bottom of the still, and is covered by conical hood 223 and skirt 225.  The stack of the pump is cooled by coil 231, which is also wound round the exhaust conduit 237.  The plate is rotated on shaft 79 by motor 81. Heating fluid is passed through jacket 65 by means of conduits 67, 69.  The distilland, which is supplied through inlet 91, flows to the rotating plate via pressure-relief valve 93 and pipe 95.  The liquid flows outwardly over the plate in a thin film, and is degassed.  The liquid flows from the plate on to the hot wall 31 via conduits 98 which pass through wall 97.  Screwed to conduits 98 are nozzles 99 (Fig. 2) which terminate close to wall 31.  As the liquid flows out of the nozzles against the wall, it is subjected to the action of the wiper blades.  The wiper mechanism comprises vertical channels 111, the upper ends of which are welded to the outer edge of plate 89 as well as to an additional support plate 113.  The bottom ends of channels 111 are connected to ring 119.  The channels are open where they face radially outwards towards wall 31.  As shaft 79 rotates, carrying plates 89 and 113 with it, the vertical channels likewise rotate about the vertical axis of the still.  Extending vertically within each channel are three blades 131, 133, 135 made of carbon or synthetic resin, which can be clamped in adjustable lateral positions by bolts extending tightly through holes in blade 133 and through horizontal slots in blades 131 and 135.  The distilland leaving each conduit 99 flows into the adjacent notch 136 between blades 135 and 133.  Blade 133 is in engagement with wall 31; and the wall-contacting face of the blade is provided with a series of oblique grooves 139 (Fig. 5) which increase the rate of downward flow of the film of distilland on wall 31.  In another embodiment, the grooves are inclined in the opposite direction to that shown in Fig. 5, and in this case the flow of the distilland is slowed down, thereby giving increased contact time.  As the liquid flows down the hot wall, part of it is evaporated.  The unevaporated liquid is collected in gutter 151, and is removed through pipe 155.  The vapours are condensed on vertical tubes 161 (Figs. 1 and 9) the ends of which are welded to annular headers 163, 165.  Refrigerant is supplied to header 165 through conduit 171, and it leaves the upper header through conduit 173.  Radial flanges 181 welded to the exteriors of the condenser tubes prevent droplets of entrained liquid being drawn inwardly into the centre of the still and the diffusion pump.  The condensate flows down into gutter 251, and is withdrawn through conduit 255.  When the still is to be used for non-molecular distillation, liquid-entrainment in the vapours reaching the condenser is reduced by semi-circular vertical members 191, 193 (Fig. 14), the ends of which are welded on to arcuate plates which are bolted to plate 113 and ring 119.  These semi-circular members are made of highly polished metal and reduce heat loss from the evaporation surface to the condenser.  Another still is described which may be used either for molecular distillation or for long-path distillation at low pressure or atmospheric pressure, without dismantling the still.  In this embodiment the still is surrounded by two separate jackets, one above the other; and the rotor does not extend down into the lower part of still.  When it is used for long-path distillation, the tubular condenser in the upper part of the still is inoperative, but cooling medium is passed through the lower jacket.  In the embodiment shown in Fig. 17, the upper and lower condenser headers 163 and 165 are connected to jacket 65 via a compressor 335 and an expansion valve 333, respectively; so that the same medium supplied as liquid refrigerant to the condenser tubes 161 is used as heating vapour in jacket 65.  For distillation at high temperature, silicone oils or polymers of chlorotrifluoroethylene may be used in the closed thermal circuit.  In the still shown in Fig. 19, which is suitable for the concentration of fruit juices, there is no internal condenser, and a steam ejector 355 is provided to evacuate the water-vapour which evaporates from the juice.  The mixed steam discharged from the ejector is passed via conduit 361 into jacket 65, where it is employed to heat the cylindrical wall of the still.  A mixture of hot water and steam is withdrawn from the jacket and passed to barometric condenser 367.  Specification 807,857 is referred to.