Electrolyzer Outlet Line Droplet Formation for Stray Current Reduction

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Solution Overview

Problem

Existing electrolyzers with series-connected electrolytic cells experience significant efficiency losses and corrosion due to stray currents, particularly in NaCl electrolysis with oxygen-consuming cathodes, which are challenging to minimize without increasing costs and space requirements.

Innovation Solution

Designing the discharge or feed lines as substantially vertically oriented tubes with peripheral openings that create a discontinuous volume flow with droplet formation, increasing electrical resistance and preventing continuous current conduction between cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If the cross-section of inlet and outlet channels is reduced to increase electrical resistance, then stray currents are reduced, but the volumetric flow rate of electrolyte cannot be sufficiently discharged

Engineering Contradiction:
Improvestray currentsVSAvoidvolumetric flow rate
Core Design Contradiction:
Object-generated harmful factorsVSProductivity

Solution Approach 1:

The outlet channel is segmented into multiple smaller outlet openings distributed along the channel. This segmentation increases the total electrical resistance path for stray currents while maintaining sufficient total cross-sectional area for electrolyte discharge, thus reducing stray currents without compromising volumetric flow rate

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of reducing the cross-section in one dimension, the solution distributes multiple small outlets along the length of the outlet channel, utilizing the longitudinal dimension. This approach increases electrical resistance through distributed small openings while maintaining adequate total flow capacity through the cumulative effect of multiple outlets

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-generated harmful factors

If outlet tubes are lengthened to reduce stray currents, then electrical resistance increases, but costs and space requirements for peripheral equipment increase

Engineering Contradiction:
Improvestray currentsVSAvoidspace requirements
Core Design Contradiction:
Object-generated harmful factorsVSArea of stationary object

Solution Approach 1:

Rather than using a single long outlet tube, the system uses multiple short outlet openings distributed along the channel. This segmentation achieves the desired electrical resistance through the distributed small openings without requiring increased tube length, thereby reducing space requirements and peripheral equipment costs

Inventive Principle:
Principle #1Segmentation

3Object-generated harmful factors

If gas is injected into inlet and outlet systems to induce bubble formation for increasing electrical resistance, then stray currents are reduced, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improvestray currentsVSAvoidsystem complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The outlet openings themselves generate the desired electrical resistance effect through their geometry and distribution, without requiring additional gas injection systems. The system serves itself by using the inherent properties of the outlet structure to achieve stray current reduction, eliminating the need for complex gas injection equipment and associated maintenance

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The gas injection system, which adds complexity, is completely removed from the design. Instead, the electrical resistance is achieved through the outlet opening configuration alone, extracting the unnecessary complexity while retaining the functional benefit of stray current reduction

Inventive Principle:
Principle #2Taking out (Extraction)

4Object-generated harmful factors

If freely rotating impellers are used to generate discontinuous volumetric flow, then stray currents are reduced, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improvestray currentsVSAvoidmaintenance requirements
Core Design Contradiction:
Object-generated harmful factorsVSEase of repair

Solution Approach 1:

The outlet openings passively generate discontinuous flow patterns and electrical resistance through their geometry and distribution, without requiring active impeller mechanisms. This self-service approach eliminates moving parts that would require maintenance, while still achieving the desired stray current reduction

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The mechanically complex impeller system is completely removed from the design. The desired flow disruption and electrical resistance effects are achieved through the outlet opening configuration alone, extracting the unnecessary mechanical complexity while maintaining the functional benefit

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution effectively minimizes stray currents, reduces maintenance and costs, and allows for a compact arrangement with reduced space requirements, while maintaining high electrical resistance, thereby enhancing the efficiency and safety of the electrolysis process.

Implementation Method 1

the electrolyte flows out in a volume flow that is at least temporarily discontinuous, with droplet formation

Methodology Applied
Scientific EffectDroplet formation:

Implementation Method 2

a specific volumetric flow rate of the electrolytes must be discharged... increasing the electrical resistance in the common inlet and outlet channels

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

Initially, the flow at exit is approximately horizontal and radial around the circumference of the outlet or inlet line, and then, due to gravity, it is deflected. The outflow of the electrolyte from a single opening in the outlet or inlet line thus follows a curved path, roughly comparable to a parabolic trajectory.

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3469118B1Electrolyzer and method for operating an electrolyzer
Publication Date: 2020.07.01 THYSSENKRUPP UHDE CHLORINE ENGINEERS GMBH
  • EP3469118B1 patent drawingFigure 1~2
  • EP3469118B1 patent drawingFigure 3~5
  • EP3469118B1 patent drawing

AI summary

The invention relates to an electrolyzer comprising at least two electrolysis cells which are connected in series and which are connected together via supply and discharge systems. Each electrolysis cell has at least one discharge line for electrolyte, and each electrolysis cell has at least one supply line which leads into the electrolysis cells for electrolyte. According to the invention, at least one discharge line (12) or at least one supply line is provided with at least one opening via which electrolyte flows out at an at least temporally discontinuous volumetric flow rate (13), thereby forming drops. Because drops are formed, the electrolyte solution flowing out is no longer in electrically conductive contact with the liquid (15) in the liquid collector (20). By virtue of this effect of a temporal interruption of the flow line, the electric resistance is significantly increased and stray flows between the discharge system and the individual electrolysis cells are prevented.