Patent ID: 11913124
Assignee: HITACHI ZOSEN CORPORATION
Field: Surface technology, coating (Chemistry)
Classification: CPC C  Y | IPC C

Claim 3:
4. A method of recovering performance of a water electrolysis system which includes a water electrolysis stack having a solid polymer membrane, a positive electrode provided on one surface of the solid polymer membrane, and a negative electrode provided on the other surface of the solid polymer membrane, the method comprising the steps of:
bringing an operating state of the water electrolysis system into a state of low-temperature operation in which a temperature of water fed to the water electrolysis stack is lower than a temperature of water fed to the water electrolysis stack during ordinary operation in which water electrolysis is carried out by the water electrolysis stack;
in the state of the low-temperature operation, passing an electric current through each of the positive electrode and the negative electrode
in a state of the ordinary operation, measuring a voltage occurring between the positive electrode and the negative electrode;
measuring an electric conductivity of hydrogen blow water generated on a negative electrode side of the water electrolysis stack;
comparing the voltage occurring between the positive electrode and the negative electrode with a first threshold; and
comparing the electric conductivity with a second threshold,
in a case where (i) the voltage occurring between the positive electrode and the negative electrode is equal to or higher than the first threshold and (ii) the electric conductivity is equal to or higher than the second threshold, the operating state of the water electrolysis system being brought into the state of the low-temperature operation.