Patent GB-687874-A (GB)
Title: Method and apparatus for conducting ion exchange operations
Inventor: WILCOX ARNOLD L
IPC: B01J47/10
Filed: 1950-08-09
Abstract: 687,874. Purifying liquids. DORR CO. Aug. 9, 1950, No. 19824/50. Class 46 In the method of continuously regenerating exhausted granular ion exchange material in which the .material passes continuously downwardly first through a regeneration zone Z3, Fig. 1, and then through a rinsing zone Z2 while a subsided and submerged body of the material is continually 'present in each zone although in transit, and in which rinse water 29 passes continuously upwardly. through the rinsing zone Z2 in countercurrent to the exchange material and thus becomes enriched with regenerant chemical, a mixing zone M is maintained functionally interposed between the rinsing and regeneration zones and substantially free from exchange material in transit, fresh regenerant chemical is continuously added at 33 to spent rinse water in the mixing zone M to produce fresh regenerant solution, and this regenerant solution 30 is passed upwardly through the regeneration zone Z3 and discharged as spent regenerant solution at 34. Externally of a tower 10 in which the zones Z2, Z3 and M are established the exchange material may passcontinuously downwardly through an exhaustion zone Z1 in a tank 11 to which liquid to be treated (e.g. hard water) is admitted at 19 and from which treated liquid (e.g. soft water) is withdrawn at 20. Exhausted ion-exchange material is withdrawn through a conduit 14 from just above a perforate supporting plate 17 and regenerated and rinsed material fed back to the tank 11 along a conduit 12. The mixing zone M is maintained substantially free from exchange material by the interposition in the tower 10 of a partition 23 having small perforations 25 through which regenerant liquid passes upwards and a spout 24 through which exchange material passes downwards. In the apparatus of Fig. 2 the transport of the exchange material is effected and controlled by water supplied under pressure from a header H. Regenerated and rinsed exchange material slides down conical baffles 47, 47a, Fig. 4, and the conical bottom of a tower 35 through a valve V1 into the horizontal section 37b of a transfer conduit 37 and is impelled along it and to an exhausting (e.g. softening) tank 36 by water from the header H forced along a conduit 56 through a control valve 56a. The rate of flow of the slurry thus formed is observed on an indicator 60a connected to a Venturi flow-meter 60. The valves VI and 56a are preferably maintained at a fixed setting, while the rate of transit of exchange material through the whole apparatus is controlled by water passing from the header H through a pipe 58 via a valve 58a and flow-meter 58b. This water passes into the transfer conduit 37 at 59, some exerting a back-pressure along the section 37b and the remainder passing up the vertical section 37c of the conduit 37 as further diluent for the slurry. The end of the conduit 37 which feeds into the tank 36 is provided with a restrieted orifice 61 to ensure that the maximum rate of flow of slurry into the tank 36 corresponds to the maximum rate of passage of exchange material through the tower 35. This maximum slurry rate is .reached when no water is permitted to pass along the pipe 58, valve VI is fully open and valve 56a is set to provide the required quantity of carrier water. Exhausted exchange material is conveyed from the tank 36 up a conduit 38 by an ejector 67 to which water is supplied at a controlled and measured rate frcm the header H, the resultant slurry being discharged into a reservoir 39 at the top of the regeneration tower at a rate slightly greater than that at which it gravitates through a neck 42 in the bottom 41 of the reservoir. Excess slurry flows back into the tank 36 through a pipe 40. As in Fig. 1 the liquid flow in the tower 35 is substantially upward and is initiated by rinse water supplied from the header H along a pipe 49 to a series of concentric circular pipes 49a, Fig. 4, perforated along their upper surfaces. The plate 44 separating the rinsing zone below it from the regenerating zone above it (corresponding to the plate 23 of Fig. 1) is provided with a number of spouts 45 for the downward. discharge of material each having a length such that the 'pumping' effect due to them on the liquid,above the partition is counterbalanced by the loss in head encountered by the liauid passing upwardly through the holes in the partition, to minimize the downward transfer of solution. Fresh concentrated regenerant solution is introduced from a tank 48c through a pipe 48 and a pipe grid (not shown on Fig. 2) which occupies the mixing zone M which is free from solids and formed between the spouts 45. The pipe grid is perforated along its upper surface. Spent regenerant solution passes to waste via a pipe 53 leading from a space 52 formed between a bed 43 and the reservoir bottom 41. The mixing zone M<SP>1</SP> may alternatively consist of a pipe 73, Fig. 6,. (not shown), outside the tower 35, to which water is pumped from the region surrounding the spouts 45, and into which concentrated regenerant solution. is introduced into the regenerating zone by means of a pipe ring just above the plate 44. The pipe 48 is of course in that case dispensed with. In Fig. 7 a softening tank 79 is disposed immediately above the regeneration and rinsing tower 80, the exchange material discharging directly into the tower 80, which has no reservoir. Regenerated and rinsed material is conveyed up a pipe 89 by water passing along a pipe 95 from a header H<SP>1</SP>, the rate being controlled by water fed to an ejector 90 along a pipe 97. Rinse water is introduced at 83, and concentrated regenerant solution at 95 from a tank 87 surmounted by a storage bin, e.g. for rock salt, 88.