SOEC Hydrogen Routing to Protect Methanation Catalysts
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Solution Overview
Problem
The presence of oxygen gas in exhaust gases from carbon dioxide emission sources can lead to catalyst deterioration in the methanation reactor due to oxidation, which is a concern in existing electrolysis systems.
Innovation Solution
An electrolysis system with a solid oxide electrolysis stack, an oxygen consumption device, and a control device that switches the supply destination of hydrogen-containing gas based on oxygen concentration to prevent oxygen from reaching the generating device, using an oxygen consumption device to consume oxygen gas and maintain catalyst integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exhaust gas containing oxygen is supplied to the methanation reactor, then the carbon dioxide conversion process can proceed, but the catalyst deteriorates due to oxidation
Solution Approach 1:
The system divides the exhaust gas processing into separate stages: first removing oxygen through the solid oxide electrolysis stack, then supplying the oxygen-free gas to the methanation reactor. This segmentation prevents oxygen from contacting the catalyst while maintaining carbon dioxide conversion capability
Solution Approach 2:
The solid oxide electrolysis stack acts as an intermediary device between the exhaust gas source and the methanation reactor. It selectively removes oxygen from the exhaust gas, providing a purified gas stream to the reactor that protects the catalyst while enabling carbon dioxide conversion
2Reliability
If oxygen removal is implemented through the solid oxide electrolysis stack, then catalyst protection is achieved, but system complexity increases
Solution Approach 1:
The solid oxide electrolysis stack performs multiple functions: it removes oxygen to protect the catalyst, generates hydrogen for potential methanation, and can operate in fuel cell mode to generate electricity. This multi-functionality justifies the added complexity by providing multiple benefits from a single device
Solution Approach 2:
The system changes the oxygen concentration parameter in the exhaust gas stream by passing it through the solid oxide electrolysis stack. This parameter modification (oxygen removal) enables catalyst protection while the control system adjusts operating parameters to optimize overall system performance
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
Prevents oxygen from reaching the generating device, thereby alleviating catalyst deterioration and improving hydrogen utilization efficiency.
Implementation Method 1
a solid oxide electrolysis stack that electrolyzes carbon dioxide gas and water vapor
Implementation Method 2
an oxygen consumption device that consumes, using hydrogen, oxygen gas in exhaust gas containing the carbon dioxide gas
Data Source
AI summary
An electrolysis system includes: an oxygen consumption device that consumes, using hydrogen, oxygen gas in exhaust gas; a valve device that is configured to switch a supply destination of the hydrogen-containing gas output from a solid oxide electrolysis stack to either one of the oxygen consumption device or a generating device; and a control device that controls the valve device according to the oxygen concentration in the exhaust gas output from the oxygen consumption device to switch the supply destination of the hydrogen-containing gas.