Patent EP-1762546-B1 (EP)
Inventor: CLASSEN EGBERT
IPC: C02F1/461
Filed: 2006-08-31
Granted: 2011-08-17
Abstract: The electrochemical, batch-wise softening of water in dishwasher with electro-chemical reactor (1) with electrodes (3, 4), has introducing the water into the reactor and applying electrical voltage difference between the anodic- and cathodic electrode to electro-chemically soften the water in a single treatment phase, discharging the softened water. Lime is not removed anodically, that is through pole reversals of the electrodes, from cathodic electrode. Apart from the treatment phase, an even number of pole reversals of the electrodes takes place before and after each regeneration phase. The electrochemical, batch-wise softening of water in dishwasher with electro-chemical reactor (1) with electrodes (3, 4), includes introducing the water into the reactor and applying electrical voltage difference between the anodic- and cathodic electrode to electro-chemically soften the water in a single treatment phase, discharging the softened water. Lime is not removed anodically, that is through pole reversals of the electrodes, from cathodic electrode. Apart from the treatment phase, an even number of pole reversals of the electrodes takes place before and after each regeneration phase. No electrical voltage difference between the anodic- and cathodic electrodes is applied during the discharge of the softened water in order to utilize the remaining, lasting after-effect of the electro-chemical softening potential after switching the electrical voltage difference off between the electrodes. A reduction of pH value of the softened water into the acidic range takes place through an anodic carbon dioxide formation to avoid stain formation and/or to improve the washing efficiency in clear and intermediate rinsing processes in the dishwasher. The calcium carbonate crystals forming at the cathode are partly carried along with the softened water for use as rinsing water and act as seed crystals, on which precipitating lime deposits. The softened water is stored temporally in a separate buffer tank before used as the rinsing water. The cathodic electrode exhibits a porous structure and is composed partly from graphite or carbon felt (10), which exhibits high affinity to carbonate salts and which is brought as an exterior shroud to the inner metal parts of the cathodic electrode for conducting current to facilitate the deposition of the carbonate salts on the electrodes. The anodic electrode exhibits a smooth surface structure and is made from titanium, titanium alloys or coated flat or expanded titanium metal, or other metals for conducting the current. The softening speed is regulated by rotational speed of the water in the reactor and/or incident-flow velocity of the water to the electrodes and/or temperature of the water in the reactor and/or the current density at the electrodes and/or the voltage difference applied between the electrodes and/or the pH value of the water in the reactor. The temperature of the water is increased with a heating device (9) and/or the rotational speed and/or the incident-flow velocity of the water are regulated with a circulation pump (8) and/or a rolling rotor in the electro-chemical reactor and/or the pH value of the water is regulated by letting off the developing carbon dioxide from the closed electro-chemical reactor with a ventilation valve (6). An independent claim is included for dishwasher.