Spiral Electrodeionization Device Segregated Ionic Flows
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Solution Overview
Problem
Current electrodialysis and electrodeionization devices face challenges such as complex and costly fabrication, operational inefficiencies due to dimensional instability of membranes and beads, and issues with scaling and fouling, particularly when treating fluids with high ion concentrations or extreme pH levels.
Innovation Solution
A spiral EDI device design featuring conductive electrodes and selectively permeable membranes spirally wound around a central core, with spacers maintaining a gap between membranes to allow fluid flow, and ion exchange material in both dilute and concentrate chambers, ensuring uniform current distribution and preventing scaling through strategic flow path design and seal placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat plate stacks or conventional spiral designs are used, then demineralization function is achieved, but fabrication complexity and cost increase
Solution Approach 1:
The device is divided into multiple modular cells arranged in series between electrodes. Each cell contains a diluate chamber and a concentrate chamber separated by ion-exchange membranes, allowing independent fabrication and assembly of standardized units that reduce overall fabrication complexity
Solution Approach 2:
Multiple membrane-spacer assemblies are nested within a single housing structure, with membranes wound or stacked in a compact configuration. This nesting approach allows multiple functional layers to be integrated into one device unit, reducing the number of separate components and simplifying fabrication
2Reliability
If membranes and beads are used without stabilization, then ion exchange function is provided, but dimensional instability occurs affecting operation
Solution Approach 1:
Rigid spacer elements are strategically positioned at specific locations within the cell to provide localized structural support to the membranes. These spacers maintain consistent spacing and prevent membrane collapse or deformation during operation, ensuring dimensional stability where most needed
Solution Approach 2:
The device combines flexible ion-exchange membranes with rigid spacer structures and supportive housing elements to create a composite system. This composite construction provides the necessary dimensional stability while maintaining the functional properties of the membrane materials
3Productivity
If conventional flow paths are used, then fluid treatment is achieved, but scaling and fouling occur particularly at high ion concentrations
Solution Approach 1:
The device incorporates periodic flow reversal capability, allowing the flow direction to be alternated between forward and reverse directions. This periodic action prevents scale and fouling accumulation by periodically dislodging deposits from membrane surfaces, maintaining high demineralization efficiency during extended operation
Solution Approach 2:
A separate concentrate stream is extracted and removed from the system, carrying away concentrated ions and potential scale-forming materials before they can deposit on membranes. This extraction of the harmful concentrate phase prevents scaling and fouling in the diluate product stream
4Productivity
If uniform current distribution is not ensured, then electrode function is provided, but operational inefficiencies occur
Solution Approach 1:
Electrode structures are designed with equipotential surfaces that distribute electrical potential uniformly across the membrane active area. This equipotential design ensures uniform current density distribution, maximizing operational efficiency and preventing localized energy losses or hot spots
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
The spiral design enhances demineralization efficiency, reduces operational complexity, and minimizes scaling by maintaining uniform current distribution and flow path control, leading to improved cost-effectiveness and longer operational stability.
Implementation Method 1
an electrical potential is applied across the membranes transverse to the flow to maintain an ionic current that demineralizes the feed fluid, moving ionizable species from the feed fluid in one channel, through the membranes, and into adjacent channels
Implementation Method 2
The presence of exchange material in the treatment channels or cells enhances the active fluid interaction area and the capture of ions from the feed
Implementation Method 3
The ion exchange material is continuously maintained in an at least partially regenerated (active) state by water splitting
Data Source
AI summary
Some embodiments of the invention relate to an electrodeionization device that includes comprising a generally cylindrical housing. The cylindrical housing includes a cylindrical inner core and an inner electrode that extends around the inner core. The cylindrical housing includes a leaf arranged as a spiral winding about the inner electrode and an outer electrode that extends about the spiral winding. Active treatment cells are defined by spaces within the spiral winding and by interleaf spaces thereof. One or more sealing bands extend between membranes of the spiral winding to define fluid flow.