Patent ID: 9580821
Date: 2017-02-28
CPC Classifications: C25B,Y02E

Claim:
1. A control method of a differential pressure water electrolysis system during depressurizing, the differential pressure water electrolysis system including a differential pressure water electrolysis device configured to perform electrolysis of water and generate oxygen at the anode side, while generating hydrogen at the cathode side at a higher pressure than that of the oxygen, a gas-liquid separator configured to perform gas-liquid separation of hydrogen derived from the differential pressure water electrolysis device, a discharge tube to discharge liquid water stored in the gas-liquid separator, an open/close valve to open and close the discharge tube, and a depressurization valve provided on a depressurizing tube to reduce pressure at the cathode side of the differential pressure water electrolysis device, which is opened when depressurizing, the method comprising: setting a reference water level of the gas-liquid separator for normal operations at which the liquid water stored in the gas-liquid separator is discharged to the discharge tube; setting a depressurization reference water level, which is a lower water level than the reference water level, at which the liquid water stored in the gas-liquid separator is discharged to the discharge tube when depressurizing; opening the depressurization valve to reduce pressure at the cathode side after operation of the differential pressure water electrolysis device has been stopped; and switching a permissible water level upper limit value, at which the open/close valve is opened, from the reference water level to the depressurization reference water level when the depressurization valve is opened.