GB683529A - Improvements in or relating to the washing and finishing of soap - Google Patents

Abstract

<PICT:0683529/III/1> Soap is washed and finished by passing the hot soap and lyes in controlled amounts alternately and intermittently in countercurrent flow through a horizontal series of chambers, the soap outlet and lye inlet at the top of one chamber being connected to the soap inlet and lye outlet at the bottom of the chamber next in the series in the direction of flow of the soap, the mixture being allowed to settle between successive passages of the soap or lyes. The soap and lyes are preferably maintained at a temperature between 180 DEG and 200 DEG F. In a suitable plant, six washing chambers 11...16 are used with connecting pipes 17, hot water jacket 21, sight glasses 20, cocks 120 for connecting the bottoms of adjacent chambers, drain cocks 22, 23 for sampling &c., and stirring arms in each chamber mounted on a shaft passing through the series of chambers. Each of the pipes 17 is provied with baffle means such as a baffle plate 18, 19 near its ends so as to prevent undue mixing of lyes with lyes and soap with soap during passage of liquid from one chamber to another. The chamber 11 is connected to a spent lye settling tank 24 having a heat-exchanger 25 connected to a hot water tank used for the jackets and the soap finishing. A soap boiling pan or continuous saponification plant is connected through pump 26 to inlet 27, and a soap outlet pipe 28 from the last chamber leads to three water-jacketed crutching pans 29, 30 and 31 for finishing. Two nigre pans 32, 33 fitted with steam coils, jackets and stirrers are provied, and are connected through their outlets 36 to jacketed lye storage tanks 37, 38 through a filter 39, and also to the crutching pans. Outlets from the latter connect to the lye storage tanks 37, 38 and also to a soap settling pan 40. The lyes are pumped through the washing chambers by a pump 137. In operation, the soap scraps in one of the nigre pans are melted with nigre from the pan 40 and after graining with brine and lyes, the settled lyes are run through the filter 39 to one of the storage tanks 37, 38. Further lyes, brine and water are added to the nigre tank in sufficient quantity together with those run off for the whole of the soap run. Controlled amounts of the lyes are now pumped into the washing chambers from the tanks 37, 38, the cocks at the tops of the chambers and the connecting cocks 120 being opened. The cocks are then closed and soap pumped into the first chamber until it is full. The pump is stopped and a settling time allowed. Pumping of soap is then recommenced until the second chamber si full and again the pump is stopped and settling time allowed. The process is repeated until all the chambers are full of soap and the original controlled amounts of lye. Thereafter when an equivalent amount of soap is passed into the first chamber an equivalent amount of soap passes from the last chamber 16 to one of the crutching pans for finishing. Pumping of soap is then stopped. A volume of lyes equal to that in the last chamber is then pumped therein, an equal volume of lyes being displaced from the end or first chamber. Pumping of lyes is then stopped and, after settling, pumping of soap recommenced. The washed soap in one of the crutching pans together with some grained soap from one of the nigre pans is settled, any lye run off, and then crutched with added water for finishing. The batch is then run off into the soap settling pan 40. In a modification, the top of each washing chamber is provied with a perforated plate inclined from the edge of the top of the chamber to the upper end of the connecting pipe and a similar perforated plate is arranged at the bottom of each chamber. This is to prevent the undue mixing aforesaid. If desired each of the chambers may also be provided with a honeycomb of vertical, square-sectioned, pipes about one quarter the height of the chamber and resting on the bottom perforated plate.