Patent ID: 8329020
Filing Date: 2012-12-11
Classification: C25B,Y02E

Abstract:
1. A system shutdown method for shutting down a water electrolysis system that includes a water electrolysis apparatus for electrolyzing water with an electric current supplied from a DC power supply to generate hydrogen and oxygen, a hydrogen outlet passage disposed downstream of and connected to a hydrogen outlet of the water electrolysis apparatus which discharges a high-pressure hydrogen under a pressure higher than a normal pressure, and a high-pressure hydrogen processing apparatus connected to the hydrogen outlet passage, and refining the discharged high-pressure hydrogen; the system shutdown method comprising: closing an outlet valve connected to an outlet port of the high-pressure hydrogen processing apparatus, and shutting down the water electrolysis apparatus; closing an inlet valve disposed on the hydrogen outlet passage and connected to an inlet port of the high-pressure hydrogen processing apparatus; releasing the pressure of the high-pressure hydrogen from the water electrolysis apparatus independently from the high-pressure hydrogen processing apparatus, with a pressure releasing device, the pressure releasing device being connected between the hydrogen outlet and the inlet valve and including a bleeder passage branched from the hydrogen outlet passage, to discharge only hydrogen in the hydrogen outlet passage upstream of the inlet valve and hydrogen in the water electrolysis apparatus, under a condition where the high-pressure hydrogen processing apparatus remains pressurized with the inlet valve; and stopping releasing the pressure of the high-pressure hydrogen from the water electrolysis apparatus when the pressure of the high-pressure hydrogen from the water electrolysis apparatus drops to an atmospheric pressure.