GB882254A - Improvements relating to monobed ion-exchange methods and apparatus - Google Patents

Abstract

882,254. Ion-exchange. ZWICKY, J. F. Feb. 22, 1960 [March 2, 1959 ; March 24, 1959], Nos. 7192/59 and 10184/59. Class 46. A monobed resin mixture 1 is disposed between top and bottom porous diaphragms 16 and 3 respectively, the vessel 2, being provided with single ports 5 and 6 at the top and bottom and with an intermediate annular port 17 communicating with the interior of the vessel through an annular porous diaphragm 18. For separation, the port 5 is connected to vacuum and the port 6 to the supply of water, while the intermediate port 17 is cut off by keeping the valve 20 closed. Separation is effected with the plane of separation between the lower, cation, resin and the anion resin approximately at 21. For regenerating the anion resin, the port 5 is connected to a supply of caustic-soda solution and the port 6 to a source of vacuum, while the intermediate port 17 remains cut off. For regenerating the cation resin, the valve 9 is closed, the port 6 remains connected to vacuum and the intermediate port 17 is connected to a supply of acid. There is a flow of acid through the lower, cation, part of the separated bed only. For a washing stage, if required, the port 5 may be connected to vacuum and the port 6 to the supply of deionised water, while the intermediate port 17 is cut off, so that there is an upward washing flow. However, the bed can be dried effectively by the vacuum at the end of the cycle and in this case no washing will be required at the end of the regeneration steps. As an alternative for the above-described regeneration under vacuum, regeneration under gravity may be employed. In this case, a final washing stage should be used. Remixing is effected, with the column wet, by applying suction, by the vacuum pump, to the port 5 at the top of the column, while the port 6 at the lower end of the column is connected to atmosphere. Large bubbles of air are entrained through the water-resin mixture and cause remixture of the resins. For normal running of the column, the port 5 is connected to the supply of raw water and the port 6 to the vessel or system receiving the treated water, the intermediate port 17 remaining cut off. The water is thereby de-ionised in downward flow through the column 1. After regeneration, it may be convenient to use the vacuum pump to draw off the first of the treated water, that is until the said water is fit for delivery to the said vessel or system. Normal running may be under gravity or under pressure applied to the column 1 from above. A modification of the above method is also described in which there is no intermediate port for regeneration.