Multi-stage electrodialysis stack electrode reversal system and method of operation
AssigneeIonics, Incorporated
InventorDouglas R. Brown
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Abstract
An improved electrodialysis stack electrode reversal system and method of operation is disclosed in which each of the electrode pairs forming an electrical stage in such stack are reversed on a sequential stage by stage basis. The sequential reversal is timed to occur in each of the series connected stages as the desired dilute product stream clears the stage substantially decreasing the amount of loss of partially treated product.
Claims7
In a multi-stage electrodialysis fluid treatment system comprised of a plurality of series connected stages, each stage arranged to further desalt the dilute product stream output of the previous stage, each stage composed of an anode and a cathode separated by at least one cell pair of salt diluting and salt concentrating chambers defined by alternating anion and cation permselective membranes, each stage connected to its associate stages by fluid passage means for each of the dilute and concentrated product streams generated by said stages, each stage further having polarity reversing means for periodically changing the polarity of said electrodes, said system further having fluid passage control means for directing the flow of said dilute and concentrated product streams, the improvement which comprises switching means for sequentially activating said polarity reversing means stage by stage on a time staggered basis in order of the dilute product salt content.
In the method of operating a multi-stage electrodialysis fluid treatment system comprised of a plurality of series connected stages, each stage arranged to further desalt the dilute product or stream output of the previous stage, each stage composed of an amode and a cathode separated by at least one cell pair of salt diluting and salt concentrating chambers defined by alternating anion and cation permselective membranes, each stage connected to its associate stages by fluid passage means for each of the dilute and concentrated product streams generated by said stages, each stage further having polarity reversing means for periodically changing the polarity of said electrodes, said system further having fluid passage control means for directing the flow of said dilute and concentrated product streams, the improvement which comprises the step of sequentially activating said polarity reversing means stage by stage on a time staggered basis in order of the dilute product salt content.
Dependencies are inferred from the claim text.