Concentric Electrode Pairs for Stable Polarity Reversal

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Solution Overview

Problem

Concentric electrolytic cells with periodic polarity reversal face challenges in maintaining constant current intensity and process voltage due to varying electrode areas, limiting their application to small-scale, non-planar geometries like cylindrical designs, where edge effects are significant and operational efficiency is compromised.

Innovation Solution

A monopolar electrolysis cell design featuring external and internal electrode pairs with constant interelectrode gap, separated by insulating elements, allowing alternating polarity operation without changing anodic and cathodic areas, and using titanium or conductive diamond electrodes with catalytic coatings to optimize performance across various electrolytic processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If concentric electrode geometry is used to reduce cell volume, then volume efficiency is improved, but current transmission stability deteriorates due to varying electrode areas during polarity reversal

Engineering Contradiction:
Improvecell volumeVSAvoidcurrent transmission stability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The electrode system is segmented into multiple pairs of electrodes (first pair and second pair) arranged concentrically. Each pair can be independently controlled to provide alternating active electrode areas during polarity reversal, thereby maintaining stable current transmission while utilizing compact concentric geometry for reduced cell volume.

Inventive Principle:
Principle #1Segmentation

2Reliability

If periodic polarity reversal is applied to prevent scaling, then electrode surface cleanliness is improved, but process parameter stability deteriorates due to varying electrode areas

Engineering Contradiction:
Improveelectrode surface cleanlinessVSAvoidprocess parameter stability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically switches between different electrode pairs based on polarity reversal requirements. During each half-cycle, the appropriate electrode pair is activated to maintain constant effective electrode area, thereby preserving process parameter stability (current intensity and voltage) while still achieving periodic polarity reversal for preventing scaling.

Inventive Principle:
Principle #15Dynamics

3Reliability

If planar electrode geometry is used to maintain constant electrode area, then current transmission stability is improved, but cell volume efficiency deteriorates

Engineering Contradiction:
Improvecurrent transmission stabilityVSAvoidcell volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

Multiple electrode pairs are nested concentrically within each other, with inner electrodes positioned within the space defined by outer electrodes. This nested arrangement allows maintaining constant effective electrode area for stable current transmission while significantly reducing the overall cell volume compared to planar geometries.

Inventive Principle:
Principle #7Nested doll (Nesting)

4Volume of moving object

If concentric electrode pairs with different sizes are used, then volume efficiency is improved, but operation with periodic current reversal becomes difficult

Engineering Contradiction:
Improvecell volumeVSAvoidperiodic current reversal operation
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The electrode system is divided into multiple pairs with different sizes arranged concentrically. By selectively activating specific pairs during polarity reversal cycles, the system maintains constant effective electrode area despite the concentric configuration, thereby enabling easy operation with periodic current reversal while achieving compact volume.

Inventive Principle:
Principle #1Segmentation

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 maintains consistent anodic and cathodic areas during polarity reversal, minimizing edge effects and optimizing current transmission, ensuring stable production of species like active chlorine with improved operational efficiency and reduced volume usage.

Implementation Method 1

electrolysing diluted alkaline brines to produce active chlorine (that is, a mixture of hypochlorite and hypochlorous acid with possible traces of dissolved free chlorine and other species at equilibrium) at the anode

Methodology Applied
Scientific EffectElectrolysis: Electrolysis

Implementation Method 2

the surface working cathodically for a half cycle to start functioning as the anode upon reversal, being subject to a local acidification which favours dissolution of the precipitate previously formed

Methodology Applied
Scientific EffectDissolution:

Implementation Method 3

organic residues which tend to oligomerise upon the electrode surface, and which sometimes may be removed by the mechanical and chemical action of nascent hydrogen in the subsequent cathodic cycle

Methodology Applied
Scientific EffectMechanical and chemical action:

Data Source

PatentEP2861784B1Electrolytic cell equipped with concentric electrode pairs
Publication Date: 2016.06.29 INDUSTRIE DE NORA SPA
  • EP2861784B1 patent drawingFigure 1
  • EP2861784B1 patent drawingFigure 2

AI summary

The invention relates to an electrochemical cell, particularly useful in electrochemical processes carried out with periodic reversal of polarity. The cell is equipped with concentric pairs of electrodes arranged in such a way that, in each stage of the process, the cathodic area is equal to the anodic area.