Patent GB-491315-A (GB)
Title: Improvements in or relating to soap and process of and apparatus for producing soap
IPC: C11D13/00
Filed: 1937-01-28
Abstract: In the process of making soap described in the parent Specification in which after saponification a stream of the saponified mixture containing soap and glycerine is continuously released into a chamber maintained under a vacuum, the molten soap withdrawn from the chamber is cooled while in substantially anhydrous condition and preferably out of contact with air to form a friable mass capable of adsorbing moisture.  Heated fatty oil, and saponifying agent such as caustic soda or potash are supplied in controlled proportions from tanks 10, 11 respectively to a mixer 14 from which the mixture is forced under pressure through a heated pipe 19 at a temperature of 455 to 518 DEG F. in which saponification is effected.  The products consisting of soap, glycerine and also steam if an aqueous saponifying agent is used, are discharged through a nozzle 27 at about 500 to 570 DEG  F. and impinge upon the wall of a chamber 25 which is preferably heated and is maintained at low pressure.  The molten soap moves downwards in a thin stream to the base, and glycerine vapours and steam are removed by a vacuum pump 36 through a pipe 29 and are condensed separately.  Hot gases may be introduced through a pipe 42.  The molten anhydrous soap is removed from the bottom of the chamber 25 by a scraper 45 and flows into two jacketed troughs 47, which may be cooled or heated.  Each trough is extended to form a cylindrical housing 49, in which is mounted a conveyer screw 50, the helical vanes of which may be continuous, or formed into flights separated by spaces in which are mounted projecting members which break up the soap stream.  The discharge end of the conveyer is enlarged at 65 to compress the soap.  The soap is cooled during progress through the chamber 49 by a surrounding cooling jacket 48 and by a cooling pipe 64 in the conveyer.  The soap is discharged through grids 70, 71 consisting of water-cooled tubes through which the soap passes to a transversely mounted conveyer 80.  This is similar to the conveyer 50 and is provided with cooling jacket and inner tube, and the conveyer screw is enlarged at the discharge end, but the conveyer rotates at a high speed.  The soap may be discharged from the conveyer 80 if further treatment is unnecessary, or it may be discharged into a conveyer 100 to which soap fillers may be admitted through a conveyer 103 and incorporated in the soap.  The resulting soap is extruded through a perforated plate 104, and falls as a powder or small masses between water-cooled rotating rolls 107, 108.  Water may be admitted through a spray 112 which <PICT:0491315/III/1> wets the roll 107, and is then adsorbed by the thin layer of soap. The soap is removed from the rolls by scrapers 118 and falls through a throat 119 to water-cooled rolls 120, 121 where further moisture may be added.  The soap is removed by scrapers 124 and falls on a belt conveyer 125 which feeds a hopper 126.  The soap is in flake form but may be compressed and extruded into bars in a screw 129.  In an example, a mixture of tallow and coconut oil is treated with caustic soda solution.  In the pipe 15 a pressure of 350 to 450 lb. is maintained, the pressure in the discharge pipe 22 being about 50 lb. and the temperature at 500 DEG  F.  The molten anhydrous soap collected at the bottom of the chamber 25 is at about 500 DEG  F.  In the screw conveyer system the soap is rapidly cooled in 4 to 20 minutes to a temperature below 300 DEG  F. and preferably 200 DEG  F.  The rapid cooling promotes the formation of "incipient planes of fracture," whereby after discharge and gentle crushing a powdery soap is obtained.