| 摘要 |
<p><PICT:0685295/III/1> Neat soap is purified by a continuous method in which, after being washed in a number of stages with a brine having a concentration slightly above the critical concentration (i.e. the concentration above which the soap will not dissolve in the brine), the neat soap is mixed with water or very dilute caustic alkali so that part of it is converted to nigre, the unconverted neat soap constituting the desired purified soap and the nigre being treated with brine for the production of a mixture of neat soap and brine having a concentration suitable for its use in the washing step. In the figure, neat soap, which may be prepared by the complete saponification of fatty substances with caustic soda solution having a concentration higher than 30 per cent, is fed into four-stage washing tower 1 through inlet 7, while a mixture of neat soap and brine is fed into the tower through line 19. This mixture of neat soap and brine has a brine concentration slightly above the critical concentration (e.g. a brine concentration not exceeding 13.39 per cent is employed if the critical concentration is 13 per cent), and is produced by the treatment of nigre with brine, as mentioned above. Each stage of washing tower 1 comprises a mixing chamber 3, provided with a mechanical mixer operated by an electric motor, and a separating chamber 4, soap ascending the tower and brine descending. In the lowermost stage, brine from the separating chamber 4 of the stage above enters mixing chamber 3 through line 8 and is mixed with neat soap entering through inlet 7, the mixture being discharged into the lowermost separating chamber 4 through line 5. Brine from the lowermost separating chamber 4 is discharged through line 11, which soap from this chamber rises through line 6 to the mixing chamber 3 of the stage above. The remaining stages operate similarly while soap from the uppermost separating chamber 4 rises through perforations in the bottom of fitting chamber 2. Water is fed into fitting chamber 2 through line 9 and mixed with the soap by means of mixer 21. The mixture passes through line 12 into settling vessel 13, from which nigre is withdrawn through line 20 and purified neat soap overflows into vessel 15. Brine is fed into mixer 17 and is mixed with the nigre entering through line 20, thereby converting the nigre to neat soap. The mixture of brine and neat soap thus formed is recycled to tower 1 through line 19, as already stated. The whole system is preferably kept at a temperature of 80-95 DEG C., while both the washing brine and the fitting water are freed from occluded gases before use.</p> |
