GB669104A - Improvements in or relating to distillation - Google Patents

Abstract

Rectification is effected by disposing in the vapour-outlet of the still one or more heat-exchangers (termed "calorifiers") each comprising pipes provided with external fins, and passing cooling-fluid through the pipes which are arranged so that the vapours flow over the pipes in a direction at right angles to the flow of cooling-fluid. The apparatus shown in Fig. 1 is suitable for the distillation of crude glycerine under <PICT:0669104/III/1> <PICT:0669104/III/2> 20 mm. pressure (abs.). The crude is charged to still 11 which is heated by 16 atm. (gauge) steam supplied to coil 13. The vapours pass through duct 14 wherein are placed three calorifiers 15, 16, 17. Water boiling at 151 DEG C. (4 atm. gauge) is present in the pipes of calorifier 15, and the steam evolved is partly condensed in vessel 19, the condensate being returned to the calorifier through pipe 20. The uncondensed steam from vessel 19 is superheated and passed through the liquid in the still in a pipe 21. Make-up water is introduced through pipe 34. The cooling system of calorifier 16 is similar to that of calorifier 15. Calorifier 17 is supplied with cold water through line 22. The glycerine condensed on the fins of the calorifiers, is withdrawn through pipes 24. The apparatus shown in Fig. 2 is suitable for the distillation of a mixture of fatty acids at 5 mm. pressure (abs.). Column 26 has five calorifiers 27 to 31 and five baffle-plates 32. The two lower calorifiers are cooled with a boiling mixture of 50 per cent diphenyl and 50 per cent diphenyl oxide, while the three upper ones are cooled with boiling water. The vapours from the boiling liquids are condensed in vessels 19, and the condensates are re-circulated to the calorifiers by pumps 33. The pressure on the boiling liquids may be controlled by valves on pipes 21. By varying the pressure only such an amount of the process-vapours is condensed on each calorifier as corresponds to the portion of one fatty acid in the vapours. The various condensates are discharged from baffle-plates 32 through pipes 24; the condensates may be poured over the lower calorifiers or returned directly to the still 25. Vapours may also be passed from the top towards the bottom of a series of superposed calorifiers. The calorifiers may be placed in a slanting position; the fins then act like cascades. Each calorifier may be provided with two pipelines, the upper one of which is fed by a liquid whose temperature is lower than that of the liquid-film on the outsides of the fins, and the lower one of which is fed by a liquid whose temperature is higher than this liquid-film. The distillation of mineral oils and tars also is referred to.