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

Claim 2:
3. 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;
comparing the voltage occurring between the positive electrode and the negative electrode with a first threshold,
in a case where the voltage occurring between the positive electrode and the negative electrode is equal to or higher than the first threshold, the operating state of the water electrolysis system being brought into the state of the low-temperature operation,
measuring an electric conductivity of hydrogen blow water generated on a negative electrode side of the water electrolysis stack; and
comparing the electric conductivity with a third threshold,
in a case where the electric conductivity is equal to or lower than the third threshold, the low-temperature operation of the water electrolysis system being ended.