Modular Alkaline Electrolyzer Layout for Stray Current Isolation
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Solution Overview
Problem
Industrial multi-megawatt alkaline water electrolyzer systems face challenges with low operating voltage and current efficiency due to stray electric currents, leading to increased investment costs and energy losses, particularly as the number of series-connected electrolysis cells increases.
Innovation Solution
The electrolyzer system is designed with electrolyzer elements that are electrically connected in series but have galvanically separated water and gas outlets, allowing for higher operating voltage without sacrificing current efficiency, enabling the use of modern transistor-based power converter technology and reducing stray electric currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of series-connected electrolysis cells is increased to achieve higher operating voltage, then the power output is improved, but stray electric currents increase causing current efficiency to deteriorate
Solution Approach 1:
The electrolyzer system is divided into multiple independent electrolyzer elements, each with its own water inlet and gas outlet channels. These elements are connected in series electrically but are galvanically separated through the channel system, allowing high voltage operation while preventing stray current paths between elements.
Solution Approach 2:
A channel system acts as an intermediary between electrolyzer elements, conducting electrolyte from separator tanks back to the electrolyzer stack. This channel system is designed to break galvanic connections, serving as an electrical insulator that prevents stray current flow while maintaining electrolyte circulation.
2Power
If the number of series-connected electrolysis cells is increased to achieve higher operating voltage, then the power output is improved, but investment costs increase
Solution Approach 1:
The system uses modular electrolyzer elements that can be configured in series to achieve desired voltage levels. This segmentation allows flexible system design where standard modules are combined, reducing overall investment costs compared to custom high-voltage systems.
Solution Approach 2:
The invention changes the electrical connection parameters between electrolyzer elements by introducing galvanic separation through the channel system. This allows operating at higher voltages with reduced current, optimizing the voltage-current relationship to reduce resistive losses and improve overall system efficiency.
3Power
If more electrolyte circulation channels are provided to support more series-connected cells, then the voltage is improved, but stray electric currents increase
Solution Approach 1:
The channel system serves as an intermediary electrolyte conduit that is electrically isolated between electrolyzer elements. By designing these channels to break galvanic connections, the system enables electrolyte circulation necessary for multiple series-connected cells while preventing stray current paths that would otherwise form through the electrolyte.
4Power
If thyristor-based supply converters are used to handle high power, then the power output is improved, but energy losses increase
Solution Approach 1:
The invention changes the operating parameters by achieving higher voltage through series connection of galvanically separated elements, which reduces the current required for the same power output. This parameter change (higher voltage, lower current) reduces resistive losses and allows the use of more efficient transistor-based power converters instead of thyristor-based systems.
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 modular design achieves higher current efficiency and lower operating voltage, reducing energy losses and investment costs, while facilitating easier maintenance and automation of the electrolyzer system.
Implementation Method 1
An electrochemical process where material interacts with electrodes can be for example an electrolysis process such as e.g. water electrolysis where electrical energy is converted into chemical energy carried by hydrogen gas H2
Implementation Method 2
The ionic conductivity needed for electrolysis is caused by hydroxide ions OH- which can penetrate the porous diaphragm
Implementation Method 3
The extra heat can be removed from the electrolyte by a heat exchanger to keep operating temperature within a suitable range
Data Source
AI summary
An electrolyzer system comprises electrolyzer elements (101) each comprising an electrolyzer stack (104) constituted by electrolysis cells. Furthermore, each electrolyzer element comprises a water inlet (106), a hydrogen separator tank (107) having a hydrogen outlet (108), an oxygen separator tank (109) having an oxygen outlet (110), and a channel system (111) for conducting electrolyte from the hydrogen separator tank and from the oxygen separator tank to the electrolyzer stack. The electrolyzer stacks of the electrolyzer elements are electrically connected to each other so that direct voltage of the electrolyzer system is a sum of direct voltages of the electrolyzer stacks of two or more of the electrolyzer elements. The water inlets, the hydrogen outlets, and the oxygen outlets of different ones of the electrolyzer elements are galvanically separated from each other. This enables the direct voltage of the electrolyzer system to have a desired value with low stray electric currents.