Patent GB-569899-A (GB)
Title: Improvements relating to the treatment of water and other aqueous solutions of electrolytes
IPC: B01J49/00
Filed: 1943-11-04
Abstract: 569,899. Softening water. PERMUTIT CO., Ltd. Nov. 4, 1943, No. 18326. Convention date, Dec. 9, 1942. [Class 46] Water is softened or electrolytes are removed from solution to leave a very low degree of dissolved salt or electrolyte by successive given volumes, each being repeatedly passed first through a bed of cation-exchange material charged with hydrogen ions and then through a bed of anion-exchange material charged with hydroxyl ions. The repeated passage of the water or solution is continued until an electric conductivity test shows that the required low degree of concentration has been reached. The given volume is chosen so that the exchange capacity of the materials is a multiple of the quantity of electrolyte in the given volume; regeneration of the materials can thus be kept in step with the treatment of the water and preferably the regeneration is effected after the first and before the last of the repeated passages of one of the given volumes. As shown in Fig. 1, a volume of raw water admitted from pipe 13 past a valve 14 passes through a pipe 15 and valve 16 to a bed of cation-exchange material 11 charged with hydrogen ions and passes thence by a pipe 33 and valve 36 to a bed of acid-removal material 31 charged with hydroxyl ions which it leaves through a pipe 39 fitted with an electric conductivity meter 50 and valve 56 to fill tank 58. The admission of raw water is then stopped by closure of valve 14 and a pump 70 is started to circulate the once-treated water from the tank 58 through pipe 71, an opened valve 75 and pipe 15 and so through the two beds 11, 31 to fill a tank 59, the valve 56 having been closed and valves 57 and 67 opened. This circulation of the volume so separated is repeated, the treated water being alternately directed to tank 58 or tank 59, until the electric conductivity meter 50 shows the desired low degree of dissolved salts, whereupon the treated water is directed from the tank 58 or 59 to a storage tank 78 by opening a valve 77 and closing the valve 75; at the same time a fresh supply of raw water is admitted by opening the valve 14. A blower 83 is fitted to the storage tanks to remove carbon dioxide from the treated water as it cascades over slats 82. Regeneration is effected at any desired stage in the repeated circulation, the partly-treated water being retained in the tank 58 or 59. The regeneration includes backwashing, treatment of the beds 11, 31 with, respectively, dilute acid and alkali drawn in by raw-water injector action, and rinsing beds 11, 31 respectively with raw water and effluent from the bed 11. An electrical system for the automatic control of the complete operation is described, Fig. 4 (not shown). The process is applicable for the removal of unwanted salts in manufacturing processes such as the removal of sodium chloride in solutions of glycerol from saponification reactions, or in glycols from chlorohydrin hydrolysis, for the removal of sodium formate from a penta-erythritol solution, for the removal of electrolytes from sugar juices, and for the purification of gelatin. Specification 545,842 is referred to.