Electrolytic Cell Scale Prevention via Polarity Reversal

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Solution Overview

Problem

Existing electrolytic cells for seawater chlorination face significant challenges with scale buildup, which reduces disinfection efficiency and increases pressure drop, and current solutions either complicate the system, reduce electrode lifetime, or are impractical for subsea applications.

Innovation Solution

The electrolytic cell design features equal-sized anodes and cathodes made from the same material, with a mixed metal oxide coating, and a power supply system that reverses polarity at regular intervals, along with a frame structure that lowers the active electrode area and uses non-conductive materials to reduce scale accumulation, while an active load helps discharge residual charge and vent hydrogen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If polarity is reversed cyclically to remove scale deposits, then scale buildup is prevented, but electrode lifetime is reduced and electrodes may be damaged

Engineering Contradiction:
Improvescale buildupVSAvoidelectrode lifetime
Core Design Contradiction:
Object-affected harmful factorsVSDuration of action of stationary object

Solution Approach 1:

The patent extracts and removes the harmful scale deposits from the cathode surface using a mechanical scraping element that physically removes the scale without requiring polarity reversal. This separates the scale removal function from the electrode operation, allowing electrodes to maintain their optimized polarity-specific design while still preventing scale buildup.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a scraping element as an intermediary mechanism between the electrode and scale deposit. This mediator performs the scale removal function without directly involving the electrode in the removal process, thereby protecting the electrode from the damaging effects of cyclic polarity reversal while still achieving scale prevention.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If electrodes are optimized for specific polarity functions, then disinfection efficiency is improved, but scale buildup occurs on cathodes

Engineering Contradiction:
Improvedisinfection efficiencyVSAvoidscale buildup
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the scale removal function from the electrode itself and assigns it to a separate scraping mechanism. This allows the electrode to remain optimized for its specific polarity function (anode or cathode) while the independent scraper handles scale removal, eliminating the trade-off between optimization and scale prevention.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The scraping element is designed to automatically remove scale deposits as they form on the cathode surface during operation. This self-service mechanism continuously maintains the cathode surface without requiring system shutdown, polarity reversal, or manual intervention, allowing the electrode to maintain its optimized performance.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If mechanical scrapers are used to remove scale, then scale buildup is prevented, but device complexity and cost increase

Engineering Contradiction:
Improvescale buildupVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The scraping element is designed to operate automatically during normal cell operation, using the existing flow conditions and electrical field to drive scale removal. The system serves itself by continuously maintaining the electrode surface without requiring external mechanical intervention, complex control systems, or additional power consumption beyond normal operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The scraping mechanism is designed to be simple and maintainable, with the ability to easily replace or clean the scraping element itself. This minimizes the overall system complexity by focusing on a single, simple removal mechanism rather than a complex integrated system.

Inventive Principle:
Principle #34Discarding and recovering

4Object-affected harmful factors

If pressurized water jets are used to decrease scale formation, then scale buildup is reduced, but device complexity and cost increase

Engineering Contradiction:
Improvescale buildupVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of using external pressurized water jets, the patent utilizes the natural conditions within the electrolytic cell itself - the existing fluid flow and electrical field - to drive the scale removal process. The system leverages its own operating parameters to achieve scale prevention without requiring additional complex subsystems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical pressurized water jet system with a simpler scraping mechanism that operates passively during normal cell operation. This substitution eliminates the need for complex water delivery systems, pressure control mechanisms, and associated infrastructure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 effectively prevents scale buildup, maintains high disinfection efficiency, and extends electrode and power supply lifetime, making it suitable for long-term subsea operation without frequent maintenance.

Implementation Method 1

An electrolytic cell for producing an oxidating agent, the electrolytic cell comprising a plurality of anodes and cathodes... a power supply system that reverses polarity at regular intervals

Methodology Applied
Scientific EffectElectrolysis: Electrolysis

Implementation Method 2

Electrochemical production of oxidants via electro chlorinators and hydroxyl radical generators is well known and widely used in the water treatment industry

Methodology Applied
Scientific EffectElectrochemical reaction: Redox Reactions

Implementation Method 3

Water and oxygen reduction reactions near the cathode cause the release of oxidants and creation of an alkaline environment

Methodology Applied
Scientific EffectWater reduction reaction: Electrolysis

Implementation Method 4

oxidation reactions at the anode cause an acidic environment

Methodology Applied
Scientific EffectOxidation reaction: Oxidation

Implementation Method 5

a frame structure that lowers the active electrode area and uses non-conductive materials to reduce scale accumulation

Methodology Applied
Scientific EffectGeometric configuration effect: Geometry

Data Source

PatentEP4382493A1Device, system and method for preventing scale
Publication Date: 2024.06.12 GRANT PRIDECO LP
  • EP4382493A1 patent drawingFigure 1
  • EP4382493A1 patent drawingFigure 2A~2B
  • EP4382493A1 patent drawingFigure 3

AI summary

There is disclosed an electrolytic cell for producing an oxidating agent, the electrolytic cell comprising a plurality of anodes and cathodes, wherein the anodes and cathodes are of substantially equal, geometrical shape. There is also disclosed an electrolytic system including such an electrolytic cell as well as an apparatus for cleaning seawater and a method for operating the electrolytic system.