Pressurized Electrolyser Floating Head Design
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Solution Overview
Problem
Existing pressurized electrolysers face limitations in operating at high pressures due to mechanical stress, leakage risks, and parasitic currents, particularly when using water as a pressurizing medium, and struggle to efficiently produce hydrogen at pressures required for hydrogen storage and fuel-cell vehicles.
Innovation Solution
A pressurized electrolyser design featuring a cell stack with a stationary and floating head configuration, where the first terminal end plate is integral with the pressure vessel and the second end plate is free to move, using a gas as the pressurizing medium, and incorporating insulated electric connections and O-ring gaskets for fluid-tightness, allowing operation at pressures up to 700 bar without external compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the cell stack is operated under high internal pressure, then hydrogen production pressure is improved, but mechanical stress on cell frames and end plates increases causing leakage and structural failure
Solution Approach 1:
The pressure containment function is segmented from the electrolysis cell stack to an external pressure vessel. The cell stack focuses on electrolysis while the pressure vessel handles pressure containment, allowing high internal pressure operation without compromising cell frame integrity.
Solution Approach 2:
A pressure vessel acts as an intermediary between the cell stack and the external environment. This intermediary contains the high-pressure electrolyte and gases, protecting the cell stack components from direct mechanical stress while enabling high-pressure hydrogen production.
2Ease of operation
If cables and fluid connections are passed through the pressure vessel, then electrical and fluid inputs/outputs are enabled, but tightness is compromised and leakage risks increase
Solution Approach 1:
The problematic cable and fluid connection passages through the pressure vessel are eliminated. Instead, connections are made at the end plates which are already part of the pressure containment structure, removing the source of potential leakage while maintaining operational connectivity.
Solution Approach 2:
The electrical and fluid connection functions are merged with the end plate structure. The end plates serve dual purposes: maintaining pressure containment and providing connection points for cables and fluid lines, eliminating separate penetration points that would compromise tightness.
3Stress or pressure
If water is used as pressurizing medium, then pressure containment is achieved, but parasitic currents and short circuits occur due to electrolyte leakage
Solution Approach 1:
The pressure vessel creates a controlled intermediary environment where non-conductive pressurizing gas can be used instead of conductive water. This intermediary approach prevents direct contact between conductive electrolyte and the pressurizing medium, eliminating parasitic current pathways while maintaining pressure containment.
4Stress or pressure
If multi-stage compressors are used to compress hydrogen to storage pressure, then hydrogen storage pressure is achieved, but energy consumption and cost increase
Solution Approach 1:
The electrolyser system itself provides the pressurization function through its integrated pressure vessel design. The electrolysis process operates directly at high pressure without requiring external compression equipment, making the system self-sufficient and eliminating the energy losses associated with multi-stage compression.
Solution Approach 2:
The compression function is extracted from the overall hydrogen production system. Instead of producing hydrogen at low pressure and then compressing it, the system directly produces hydrogen at the required storage pressure, removing the compression step and its associated energy consumption.
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 design ensures safe and reliable hydrogen production at high pressures, reducing energy costs by eliminating the need for multi-stage compression, minimizing leakage risks, and preventing parasitic currents, making hydrogen a more viable energy carrier.
Implementation Method 1
electrolysis of water, the produced gases are collected therefrom
Implementation Method 2
the space inside the pressure tube and outside the cell block is put under hydraulic pressure by the electrolyte feed to the electrolysis cells
Implementation Method 3
the second terminal end plate is inside the vessel and is free to move in a longitudinal direction relative to the first terminal end plate and to the vessel, in response to thermal expansion or contraction
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An electrolyser (100) comprising an electrolysis cell stack (101) inside a pressure vessel (115), wherein the first terminal end plate (107a) of the cell stack is integral with one a closed ends of the pressure vessel, thus forming a stationary head (107) of the cell stack equipped with the fluid and electric connections, and the second terminal end plate (108a) of the cell stack is inside the vessel and is free to move in a longitudinal direction in response to thermal expansion or contraction, thus forming a floating head (108) of the stack. The pressure vessel (115) is preferably pressurized using a gaseous product obtained in the process of electrolysis.