Patent GB-688489-A (GB)
Title: Improvements relating to ion-exchange processes and plants
Inventor: BLIGHT FRANK CHARLES
IPC: B01J49/00
Filed: 1950-06-14
Abstract: 688,489. Purifying by ion exchange. PERMUTIT CO., Ltd. June 8, 1951 [June 14, 1950], No. 14893/50. Addition to 624,884 and 637,279. Class 46 [Also in Groups XXXV and XXXVI] In the treatment of liquid for the removal of cations by two or more cationexchangers working in parallel the conductivity'of the effluent from any one of the exchanges is compared with conductivity of the effluent from the remaining exchangers or with the conductivity of a blend of the first-named effluent and at least one other of the effluents whereby the time when regeneration of any one exchanger should be initiated or (after the regeneration stage) rinsing should be stopped and the working stage begun can be determined. Each one of a battery of three cation-exchangers of which the first, 1, and the third, 3, are shown, is controlled by a rotary multi-port valve 4. In its first position the valve allows water supplied through a pipe 5 to flow via pipe 6 to the top of the exchange material and, on emerging from the bottom of the material as an acid effluent through a pipe 7, to flow to service through a pipe 8. A small fraction of the effluent drains away through a conductivity cell Al. In the second position of the valve water from the pipe 5 flows downwards through the pipe 7, upwards through the material to backwash it and leaves through a pipe 11 to the drain 10. In the third position water from the pipe 5 flows through an injector in the valve 4 and draws in a fixed quantity of regenerating acid from a tank 31 through a pipe 32, the acid solution formed flowing downwards through the material, and the effluent after passing through the valve 4 flowing to drain through a pipe 13. A small fraction of this effluent also flows through the cell Al. In the fourth and final position the material is rinsed downwardly by water entering through the pipe 6 and leaving by 13. When rinsing is complete the valve 4 is returned to its initial position. A common main 14 for treated water has tappings to drain equal in number to the number of cation-exchangers, each tapping containing a conductivity cell, e.g. A2. The valve 4 is driven in step-wise fashion by a motor including in its circuit a contact arm which turns with the valve. Two of the segments over which the contact arm moves-those controlling movement of the valve from the working to the backwashing position respectively-are in circuit with a further circuit which includes the conductivity cells A1 and A2. The arrangement is such that when the effluent from the exchanger 1 becomes less acid on exhaustion of the material the motor is set in motion to move the valve to the second (backwashing) position. The periods for backwashing and regeneration and the movement of the valve to regeneration and rinsing positions respectively are governed by other conventional electrical devices. At some time between the beginning of backwashing and the beginning of rinsing the conductivity of the effluent passing through the cell A1 rises above that of the effluent passing through the cell A2. When washing is complete the two conductivities become nearly equal and the cell circuit operates through the motor to bring the valve to its working stage position.