Water Electrolysis System Pressure Control via Reverse Voltage
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Solution Overview
Problem
In water electrolysis systems, rapid pressure reduction during operation stoppage can cause hydrogen gas expansion, leading to blisters in the solid polymer electrolytic membrane and hydrogen leakage to the anode side, degrading the catalyst and reducing water electrolysis performance.
Innovation Solution
A method involving the application of an electrolytic current while opening an on-off valve in the pressure release line, with the electrolytic current adjusted based on detected specific resistance or conductivity of the water, to gradually reduce pressure and prevent hydrogen leakage, using a detection device to monitor and control the electrolytic current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydrogen pressure is rapidly reduced after stopping water electrolysis, then the stopping process is completed quickly, but hydrogen gas expands and produces blisters in the solid polymer electrolytic membrane
Solution Approach 1:
The patent applies a reverse voltage (electrolytic current) to the electrolytic membrane before and during the pressure reduction process. This preliminary action of applying reverse voltage prevents hydrogen gas expansion by maintaining the membrane's structural integrity and preventing blister formation during the subsequent pressure reduction phase.
Solution Approach 2:
The patent changes the electrical parameter by applying a reverse voltage (electrolytic current) with a specific magnitude and time duration. This parameter change controls the hydrogen pressure reduction rate and prevents membrane damage while enabling relatively quick pressure equalization between the cathode and anode sides.
2Reliability
If hydrogen pressure is gradually reduced to prevent membrane damage, then membrane integrity is maintained, but the pressure reduction takes considerable time and hydrogen permeates to the anode side
Solution Approach 1:
The reverse voltage is applied in advance and maintained during the pressure reduction process, creating a protective effect that allows faster pressure reduction without membrane damage. This preliminary protective action prevents hydrogen permeation to the anode side even during accelerated pressure reduction.
Solution Approach 2:
The patent converts the potentially harmful effect of rapid pressure reduction (which would cause membrane damage) into a beneficial process by applying reverse voltage. The reverse voltage transforms the harmful hydrogen expansion into a controlled process that actually helps maintain membrane integrity while enabling faster pressure equalization.
3Stress or pressure
If hydrogen permeates to the anode side during pressure reduction, then pressure equalization occurs, but the anode catalyst is reduced by hydrogen and water electrolysis performance degrades
Solution Approach 1:
The reverse voltage application converts the harmful effect of hydrogen permeation to the anode side into a beneficial process. The reverse voltage causes hydrogen ions that permeate to the anode side to be protonated again and return to the cathode side through the membrane pump effect, thus preventing catalyst reduction and maintaining performance.
Solution Approach 2:
By changing the electrical parameter (applying reverse voltage with specific magnitude and duration), the patent controls the behavior of hydrogen ions during pressure reduction. This parameter change ensures that even if some hydrogen permeates to the anode side, it is converted back and returned to the cathode side, preventing catalyst degradation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively inhibits the flow-out of the membrane component and reduces hydrogen consumption, thereby improving the overall efficiency and longevity of the water electrolysis system by maintaining the integrity of the catalyst and membrane.
Implementation Method 1
The hydrogen ions permeate through the solid polymer electrolytic membrane to the cathode side
Implementation Method 2
water is decomposed to produce hydrogen ions (protons). The hydrogen ions permeate through the solid polymer electrolytic membrane to the cathode side, and are bonded with electrons to produce hydrogen
Data Source
AI summary
In a method of stopping an operation of a water electrolysis system, an on-off valve disposed in a pressure release line communicating with a cathode side of an electrolytic membrane is opened while an electrolytic current is applied between power feeders to electrolyze water for generating oxygen on an anode side of the electrolytic membrane and high pressure hydrogen having a higher pressure than a pressure of the oxygen on the cathode side. A value of the electrolytic current is reduced in a predetermined cycle or continuously. One of a specific resistance and conductivity of water to be supplied to the high pressure hydrogen producing apparatus is detected. The value of the electrolytic current is increased if the specific resistance is equal to or lower than a first predetermined value, or if the conductivity is equal to or higher than a second predetermined value.