Effective shutdown purge system and method for electrolyzer stacks

Abstract

An electrolysis system includes an electrolyzer stack, a water source, and a cathode-side purging system. The electrolyzer stack has an anode side and a cathode side. The water source is fluidically coupled to an inlet of the anode side of the electrolyzer stack. The cathode-side purging system is fluidically coupled to a first and second outlet of the cathode side.

What is claimed is: 
     
         1 . An electrolysis system comprising:
 an electrolyzer stack having an anode side configured to convert water into oxygen gas and hydrogen protons and a cathode side configured to convert the hydrogen protons into hydrogen gas,   a water source fluidically coupled to an inlet of the anode side of the electrolyzer stack to provide the water to the anode side, and   a cathode-side purging system that is configured to be transitioned between an electrolyzer-on state and an electrolyzer-off state and includes a water reservoir, an outlet conduit fluidically coupled between a first outlet and a second outlet of the cathode side and the water reservoir, and an inlet conduit fluidically coupled between the water reservoir and the second outlet of the cathode side.   
     
     
         2 . The electrolysis system of  claim 1 , wherein the cathode-side purging system is configured to collect the water from the cathode side of the electrolyzer stack to provide at least a portion of a stored water in the water reservoir when the cathode-side purging system is in the electrolyzer-on state. 
     
     
         3 . The electrolysis system of  claim 1 , wherein the electrolyzer stack is positioned above a floor and the cathode-side purging system is above the electrolyzer stack relative to the floor. 
     
     
         4 . The electrolysis system of  claim 1 , wherein the water reservoir is configured to store a volume of a stored water, the volume of the stored water being at least equal to a holding volume of the cathode side of the electrolyzer stack. 
     
     
         5 . The electrolysis system of  claim 4 , wherein the volume of the stored water is at least two times the holding volume of the cathode side of the electrolyzer stack. 
     
     
         6 . The electrolysis system of  claim 1 , wherein the cathode-side purging system further includes a valve coupled to the inlet conduit to selectively direct a stored water from the reservoir, the valve being changeable between a closed configuration in which the stored water is blocked from flowing past the valve and an open configuration in which the stored water can flow past the valve and into the cathode side of the electrolyzer stack. 
     
     
         7 . The electrolysis system of  claim 6 , wherein the valve is a normally-open control valve that is configured to automatically change between the closed configuration when the cathode-side purging system is in the electrolyzer-on state and the open configuration when the cathode-side purging system is in electrolyzer-off state. 
     
     
         8 . The electrolysis system of  claim 1 , wherein the cathode-side purging system further includes a priming conduit fluidically coupled to the reservoir to deliver a priming water to the reservoir to provide at least a portion of a stored water in the reservoir when the cathode-side purging system is in the electrolyzer-off state. 
     
     
         9 . A purging system for an electrolyzer stack comprising:
 a reservoir configured to store a volume of a stored water,   an outlet conduit fluidically coupled between a first and second outlet of a cathode side of an electrolyzer stack and the reservoir, and   an inlet conduit fluidically coupled between the reservoir and the outlet conduit, the inlet conduit having a valve that is changeable from a closed configuration and an open configuration.   
     
     
         10 . The purging system of  claim 9 , wherein the outlet conduit includes a first segment extending between the first outlet and a meeting point, a second segment extending between the second outlet and the inlet conduit, a third segment extending between the inlet conduit and the meeting point, and a fourth segment extending between the meeting point and the reservoir. 
     
     
         11 . The purging system of  claim 10 , wherein the stored water flows from the reservoir, into the inlet conduit, into the second segment, and through the second outlet of the cathode side of the electrolyzer stack when the valve is in the open configuration. 
     
     
         12 . The purging system of  claim 9 , wherein the valve is a normally-open control valve that is configured to automatically change between the closed configuration when the purging system is an electrolyzer-on state and the open configuration when the purging system is in an electrolyzer-off state. 
     
     
         13 . The purging system of  claim 9 , wherein the purging system further includes a priming conduit fluidically coupled to the reservoir to deliver priming water to the reservoir to provide at least a portion of the stored water. 
     
     
         14 . The purging system of  claim 9 , wherein the volume of the stored water is at least a holding volume of the cathode side of the electrolyzer stack. 
     
     
         15 . The purging system of  claim 9 , wherein the reservoir is positioned above a floor and at least the water-distributing conduit and the electrolyzer stack are located below the reservoir relative to the floor. 
     
     
         16 . A method for reducing degradation of an electrolyzer stack, the method comprising:
 operating an electrolyzer stack, wherein the electrolyzer stack is located above a floor and includes an anode side and a cathode side, the anode side providing a crossover water that is directed to the cathode side,   positioning a cathode-side purging system above the electrolyzer stack relative to the floor, the cathode-side purging system including a reservoir for holding a stored water, an outlet conduit fluidically coupled between a first outlet and a second outlet of the cathode side and the reservoir, and an inlet conduit fluidically coupled between the reservoir and the second outlet of the cathode side,   operating the cathode-side purging system in an electrolyzer-on state where hydrogen gas and the crossover water is directed from the cathode side and into the reservoir via the outlet conduit, wherein at least a portion of the stored water is the crossover water,   de-energizing the electrolyzer stack, and   upon de-energizing the electrolyzer stack, operating the cathode-side purging system in an electrolyzer-off state.   
     
     
         17 . The method of  claim 16 , further comprising:
 priming the cathode-side purging system with a priming water to provide the stored water when the cathode-side purging system is in the electrolyzer-off state so that a volume of the stored water is at least equal to a holding volume of the cathode side of the electrolyzer stack when the cathode-side purging system is changed to the electrolyzer-on state.   
     
     
         18 . The method of  claim 17 , wherein the volume of the stored water is at least two times the holding volume of the cathode side of the electrolyzer stack. 
     
     
         19 . The method of  claim 16 , wherein the cathode-side purging system further includes a valve coupled to the inlet conduit to selectively direct the stored water from the reservoir, the valve being changeable between a closed configuration in which the stored water is blocked from flowing past the valve and an open configuration in which the stored water can flow past the valve and into the cathode side of the electrolyzer stack. 
     
     
         20 . The method of  claim 19 , wherein the valve is a normally-open control valve that is configured to automatically change between the closed configuration when the cathode-side purging system is in the electrolyzer-on state and the open configuration when the cathode-side purging system is in the electrolyzer-off state.