Electrodeionization Apparatus with Barrier Cells for Scale Control
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Solution Overview
Problem
Electrically-driven separation apparatuses, such as electrodeionization devices, face challenges in reducing scale formation, particularly in treating water with high hardness or silica content, which limits their effectiveness and increases operational costs due to the need for additional pretreatment processes.
Innovation Solution
The implementation of electrodeionization apparatuses with barrier cells and layered media configurations that ionically isolate scale-forming species, combined with acidic solution addition and degasification, to inhibit scale formation and improve current distribution, allowing for the treatment of water with higher hardness without additional pretreatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrodeionization apparatus is used to treat water with high hardness, then scale formation occurs, but additional pretreatment processes are required which increase device complexity and cost
Solution Approach 1:
The concentrating compartment is divided into multiple zones with different media types (cation exchange media, anion exchange media, inert media) arranged in specific patterns. This segmentation creates regions that selectively transport and concentrate different ions, preventing scale-forming species from accumulating at membrane surfaces while maintaining effective water treatment.
Solution Approach 2:
Different media are placed in specific locations within the concentrating compartment - cation exchange media in first zones, anion exchange media in second zones, and inert media in third zones. This local differentiation of media properties creates optimal conditions for ion transport and scale prevention in each region, allowing the system to handle high hardness water without pretreatment.
2Reliability
If electrodeionization apparatus treats water with high silica content, then scale formation occurs, but additional pretreatment processes are required which increase operational costs
Solution Approach 1:
The concentrating compartment is segmented into zones with cation exchange media, anion exchange media, and inert media. This segmentation creates specific flow paths and concentration zones that prevent silica and other scale-forming species from reaching saturation levels at membrane surfaces, eliminating the need for expensive pretreatment processes.
Solution Approach 2:
Inert media are introduced as intermediary elements between the ion-exchange media and the membranes. These inert media zones act as buffer regions that modify ion transport and prevent direct contact between concentrated scale-forming species and membrane surfaces, reducing scale formation without requiring additional pretreatment steps.
3Productivity
If traditional electrodeionization configuration is used, then current distribution is uneven, but treatment efficiency decreases
Solution Approach 1:
Different media are strategically positioned in specific zones of the concentrating compartment to create local variations in ion transport properties. This local differentiation ensures more uniform current distribution across the membrane surfaces while maintaining high treatment efficiency through optimized ion concentration pathways.
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 approach reduces the likelihood of scale formation, enhances the reliability and efficiency of water treatment, and eliminates the need for costly pretreatment processes, enabling the treatment of water with higher hardness levels while maintaining water quality comparable to systems using two-pass reverse osmosis.
Implementation Method 1
electrodeionization apparatus with barrier cells and layered media configurations that ionically isolate scale-forming species
Implementation Method 2
electrically-driven separation apparatuses such as electrodeionization devices
Implementation Method 3
combined with acidic solution addition and degasification, to inhibit scale formation
Implementation Method 4
combined with acidic solution addition and degasification, to inhibit scale formation
Data Source
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AI summary
Electrodeionisation devices having low scale potential as well water treatment methods using the device are disclosed. The device may have a variety of configurations such as a first depleting compartment disposed between the anode compartment and the cathode compartment, a concentrating compartment in ionic coummunication with the depleting compartment, a second depleting compartment in ionic communication with the concentrating compartment and a first barrier cell in ionic communication with and disposed between the first depleting compartment and at lest one of the anode compartment and the cathode compartment. The device may also have configuration directed to the layering of the anionic exchange resin beads and/or have at l-east one compartment that provides a dominating resistance resulting in a uniform current distribution throughout the apparatus. Temperature control may be provided. It is also possible to arrange for parallel liquid flow.