Hydrogen Purifier Oxygen Control for Catalyst Protection
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Solution Overview
Problem
The concentration of oxygen in hydrogen gas produced by alkaline water electrolysis varies with operating conditions, leading to increased temperature and humidity in deoxygenation processes, which can degrade catalysts and cause equipment failures and inaccuracies in monitoring devices.
Innovation Solution
A method to control the oxygen concentration in hydrogen gas to be fed to a purifier, maintaining it below 0.5 volume % across various current densities, using mechanisms such as controlling the circulation flow rate of the electrolytic solution and feeding purified hydrogen to stabilize the oxygen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of oxygen in hydrogen gas increases due to variations in electrolysis operating conditions, then the purification process becomes more intensive, but this causes local temperature increase in the deoxidizing catalyst, leading to catalyst degradation
Solution Approach 1:
The patent applies preliminary action by controlling the oxygen concentration in the hydrogen gas before it enters the purification stage. By maintaining oxygen concentration below 0.5 volume% through optimized electrolysis operation, the system prevents excessive temperature rise in the catalyst before the purification process begins, thereby protecting the catalyst from degradation
Solution Approach 2:
The patent employs parameter changes by strictly controlling the oxygen concentration parameter in the hydrogen gas to be less than 0.5 volume%. This parameter control ensures that the catalytic reaction does not generate excessive heat, thereby maintaining catalyst temperature within safe operating limits and extending catalyst life
2Reliability
If the oxygen concentration in hydrogen gas increases, then more catalytic reaction occurs to remove oxygen, but this generates more water, creating a humid atmosphere that degrades the catalyst
Solution Approach 1:
The system performs preliminary control of oxygen concentration in the hydrogen gas before purification, maintaining it below 0.5 volume%. This preliminary action prevents excessive water generation during the catalytic reaction, thereby avoiding the formation of a humid atmosphere that would degrade the catalyst
Solution Approach 2:
By controlling the oxygen concentration parameter to be less than 0.5 volume%, the patent limits the extent of catalytic reaction and consequently the water generation. This parameter control prevents excessive humidity in the purification system, protecting the catalyst from degradation
3Reliability
If the oxygen concentration in hydrogen gas fluctuates, then the purification process becomes unstable, but this causes fluctuations in temperature and pressure, leading to equipment failures and measurement inaccuracies
Solution Approach 1:
The patent applies preliminary control by maintaining oxygen concentration in the hydrogen gas below 0.5 volume% before the purification stage. This preliminary stabilization of gas composition prevents subsequent fluctuations in temperature and pressure during purification, thereby ensuring equipment stability and measurement accuracy
Solution Approach 2:
By controlling the oxygen concentration parameter to remain stable and below 0.5 volume%, the patent prevents fluctuations in the purification process. This stable parameter control avoids temperature and pressure variations that would otherwise cause equipment failures and measurement inaccuracies
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 stabilization of oxygen concentration in hydrogen gas prevents catalyst degradation, improves purification efficiency, and extends the service life of monitoring devices and equipment, ensuring consistent hydrogen production.
Implementation Method 1
water is electrolyzed to generate hydrogen on the cathode side and oxygen on the anode side
Implementation Method 2
oxygen is caused to react with hydrogen with an aid of a deoxidizing catalyst or the like described in PTL 1 to convert oxygen into water
Data Source
AI summary
A method of producing hydrogen using a water electrolysis system comprising at least an electrolyzer and a purifier for removing oxygen in a hydrogen gas generated in the electrolyzer. The method includes controlling a concentration of oxygen in a hydrogen gas to be introduced to the purifier to be constantly less than 0.5 volume % when the electrolyzer is operated at least under a current density of 0.5 kA/m2 or greater; and further controlling Ob/Oa to be less than 10.0, where Oa represents the concentration of oxygen in the hydrogen gas to be introduced to the purifier when the electrolyzer is operated under a current density of 2.0 kA/m2, and Ob represents the concentration of oxygen in the hydrogen gas to be introduced to the purifier when the electrolyzer is operated under a current density of 0.2 kA/m2.