METHOD AND APPARATUS FOR CONTROLLING THE ELECTRICAL POWER APPLIED TO AN ELECTRICALLY DRIVEN OXYGEN SEPARATION DEVICE HAVING ONE OR MORE COMPOSITE MEMBRANE ELEMENTS TO SEPARATE OXYGEN FROM AN OXYGEN CONTAINING FEED

摘要

A method and apparatus for controlling the electrical power applied to an electrically driven oxygen separation device having one or more composite membrane elements to separate oxygen from an oxygen containing feed. The composite membrane elements have a resistance increasing during the operation thereof that would act to reduce oxygen output if applied voltage were held constant. In order to increase the time interval for renewing the composite membrane elements, the electrical potential difference is controlled such that the electric current drawn by the elements remains at a substantially constant level by increasing the electrical potential difference as the resistance increases until a predetermined voltage level is reached. Once this level is obtained, the electrical potential difference is maintained at a constant level and the electric current being drawn and the oxygen output is allowed to decay to a predetermined low level after which the element or elements are replaced.