GB809685A - Improvements relating to water demineralizing units particularly for domestic supplysystems - Google Patents

Abstract

809,685. Softening water; ion-exchange apparatus. GENERAL ELECTRIC CO. May 11, 1956 [May 12, 1955 ; June 29, 1955], No. 14731/56. Class 46. [Also in Groups XI and XXXVI]. Water intended for a domestic supply system and derived from a hard-water source is passed at 93 into a perforated distribution ring 96 and falls thence on to a bed of mixed ion-exchange resins occupying an annular chamber 32 lying between inner and outer diaphragms 31 and 29 respectively. Demineralized water emerges into a lower compartment 28 whence the bulk passes out at 103, while a minor proportion passes through a check valve 111 and upwards between the diaphragm 31 and an anode 33 (thus forming the anolyte), and a further minor proportion passes through a check valve 109 and upwards between the diaphragm 29 and the casing 11 constituting the earthed cathode (thus forming the catholyte). The demineralization is performed mainly by ion-exchange and to a less extent by electrodialysis. During the time that water is not being withdrawn from the apparatus the ion-exchange bed is being regenerated by electrolytically-produced hydrogen and hydroxyl ions while cations and anions previously present in the raw water are conveyed by electrodialysis from the resins into the catholyte moving upwards in the catholyte chamber 30 and into the anolyte moving upwards in the anolyte chamber 34 respectively. These liquids meet at the top of a cylindrical baffle 87 between the anode 33 and a dome 49, 53 and flow downwards into a mixing chamber 116, whence they leave the apparatus at 114. Small amounts of oxygen and hydrogen evolved at the anode and cathode respectively pass upwards into an upper dome section 50 where they combine harmlessly in the presence of a mass of catalyst 118 contained in a bag. The diaphragm 29 comprises a perforated outer sleeve of mild steel and two inner sleeves, e.g. of wood, preferably poplar ; the outer sleeve is coated with insulating material. The diaphragm 31 comprises a perforated inner sleeve of, e.g. thermoplastic resin and an outer sleeve, e.g. of wood, preferably poplar. The D.C. potential maintained between the anode and cathode may be provided by an A.C source and rectifier, the A.C. source also providing current for electric heating elements on the outside of a water storage tank through which the demineralized water passes on its way to use (see Group XI). Reference has been directed by the Comptroller to Specification 776,469 [Group XXXVI].