Water Electrolysis Gas Flushing for Safe Wide-Range Operation
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Solution Overview
Problem
Water electrolysis processes face efficiency losses and safety risks due to electrolyte concentration imbalances and gas crossover, leading to catastrophic explosions and reduced operational power range, particularly in installations powered by renewable resources with varying current densities.
Innovation Solution
A water electrolysis process that includes detecting unsafe dioxygen to dihydrogen or dihydrogen to dioxygen ratios and flushing either dihydrogen or dioxygen into the respective compartments using controlled gas flushing systems to maintain safe operation across a wide range of current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If electrolyte streams from anodic and cathodic compartments are mixed together to balance concentration gradients, then electrolyte concentration balance is improved, but gas mixing occurs leading to explosive mixtures and safety risks
Solution Approach 1:
The system divides the electrolyte recirculation into separate streams: one stream recirculates electrolyte from the anodic compartment back to anodic compartments, and another stream recirculates electrolyte from the cathodic compartment back to cathodic compartments. This segmentation prevents mixing of gases from opposite compartments while maintaining electrolyte concentration balance through independent control of each stream.
Solution Approach 2:
The patent introduces a mixing chamber as an intermediary component where electrolyte streams can be safely mixed after gas separation has occurred. The mixing chamber is designed to prevent gas contamination during the mixing process, allowing concentration balance to be achieved without direct exposure to explosive gas mixtures.
2Reliability
If electrolyte streams from anodic and cathodic compartments are kept separate to avoid gas mixing, then safety is improved, but electrolyte concentration imbalance occurs leading to efficiency losses
Solution Approach 1:
The system implements separate recirculation loops for anodic and cathodic electrolyte streams, each maintaining its own concentration balance independently. This segmentation ensures safety by preventing gas mixing while allowing each stream to be optimized for its respective compartment's concentration requirements.
Solution Approach 2:
The patent applies different recirculation strategies to different compartments: the anodic stream is recirculated to anodic compartments and the cathodic stream to cathodic compartments. This local quality approach allows each compartment type to maintain its optimal electrolyte concentration independently, preserving electrolyzer efficiency while ensuring safety.
3Reliability
If gas flushing is applied to maintain safe gas ratios in electrolyte, then safety is improved, but device complexity increases due to additional gas injection systems
Solution Approach 1:
The system uses the produced gases themselves (hydrogen from cathodic compartment and oxygen from anodic compartment) as the flushing agents. By recycling these gases back into their respective electrolyte streams, the system maintains safe gas ratios without requiring external gas sources or complex additional injection systems, thus improving safety while minimizing added complexity.
Solution Approach 2:
The produced gases serve dual functions: they are the primary products to be collected and utilized, and simultaneously serve as flushing agents to maintain safe gas concentrations in the electrolyte streams. This multi-functionality eliminates the need for separate flushing gas systems, reducing overall device complexity while maintaining safety.
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
Ensures safe and efficient operation by preventing explosive gas mixtures and maintaining efficiency by diluting gases to safe thresholds, reducing shutdowns and production losses in electrolyzers.
Implementation Method 1
supplying an electric current between the anode and the cathode of the or each cell to electrolyze water within the or each cell, and produce dioxygen in the anodic compartment and dihydrogen in the cathodic compartment
Implementation Method 2
In each cell, dihydrogen is produced at a negative electrode (cathode) separated by a membrane from the positive electrode (anode) where dioxygen is produced
Implementation Method 3
separating the mixture of electrolyte and dioxygen in a dioxygen separator to obtain a dioxygen stream and a dioxygen containing electrolyte stream
Data Source
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AI summary
The process comprises: - recovering a mixture of electrolyte and dioxygen from an anodic compartment (19B) and separating it in a dioxygen separator (60) to obtain a dioxygen stream and a dioxygen containing electrolyte stream; - recovering a mixture of electrolyte and dihydrogen from an cathodic compartment (19A) and separating it in a dihydrogen separator (49) to obtain a dihydrogen stream and a dihydrogen containing electrolyte stream ; - recirculating the dioxygen containing electrolyte stream and the dihydrogen containing electrolyte stream. Upon detection of conditions susceptible of leading to a dioxygen to dihydrogen ratio greater than a safety OTH threshold in the cathodic compartment (19A) or/and to a dihydrogen to dioxygen ratio greater than a safety HTO threshold in the anodic compartment (19B), flushing dihydrogen in electrolyte fed to the or each cathodic compartment (19A), and/or flushing dioxygen in electrolyte fed to the or each anodic compartment (19B).