GB685719A - Improvements in or relating to distillation processes and apparatus - Google Patents

Abstract

High boiling liquids are distilled or deodorized by passing the liquid successively through two or more compartments arranged in series in a single vessel, each compartment being provided with a circulator, such as a riser-tube dipping in the liquid and having an inlet for a propellant vapour, which raises the liquid in the compartment and causes it to impinge against <PICT:0685719/III/1> <PICT:0685719/III/2> <PICT:0685719/III/3> a baffle disposed in the vapour space of the vessel, the liquid being heated (distilling) or cooled (deodorizing) during its passage through the circulator by a heat exchanger disposed in the circulator. The distillation of mineral oils, glycerine and fatty acids, and the deodorization of oils, fats, waxes and resins (natural or synthetic), are referred to. The process is preferably carried out under reduced pressure. The annular space between cylinder 2 and the wall of distillation-still 1 is divided into eight compartments 4 by partitions 3; and the cylinder and the compartments each contain a circulator 5. Each circulator comprises a dip-pipe 6, and a riser-tube 7 which is supplied with steam or hydrocarbon vapour through line 10, and which contains heating-tubes 8. The distilland is introduced into the central circulator through line 15, and is lifted to, and dispersed in the vapour space of the central compartment where partial vaporization takes place. Part of the remaining liquid, which collects in the lower part of the still, re-enters the central circulator through opening 9; and the rest flows through opening 16 into the first compartment 4 where it is lifted by the circulator in that compartment. The unvaporized liquid passes through the succeeding compartments 4 via openings 17, and is finally discharged from the last compartment through line 18. The liquid is circulated separately in each compartment. The distillation-temperature may be kept higher in the first compartments than in the last ones. In order that the residence-time of the liquid in the still may be as short as possible (so as to avoid thermal decomposition), the liquid-content and the liquid-level are both kept low, and the bottom 19 of the central chamber is disposed higher than the bottom 20 of the still. The mixture of distilland-vapours and lift-vapours, is withdrawn through outlet 28 into a vacuum plant. If a plurality of fractions is required, the vapour space of the still is subdivided into compartments each of which is provided with a separate conduit leading to a separate condenser; and the compartments may be subjected to different degrees of vacuum. A similar apparatus designed for holding greater depths of liquid, which is suitable for the deodorization of oils, is also described. In this apparatus the central chamber is separated from the annular chambers by a double wall. The oil is introduced into one of the annular chambers, and is withdrawn from the central chamber. The heating tubes may be the double type wherein the heating steam flows up the inner tube (which is open at the top) and then flows down the annular space between the inner and the outer tube (which is closed at the top). The heating element shown in Fig. 6 comprises a central tube 26 provided with several branch tubes 27. Heating steam is supplied through line 13 and the condensate is discharged through line 14, or vice versa. Specifications 225,552, [Class 32], 546,416 and 608,595 are referred to.