Integrated Composite Membrane for Spiral-Wound Filtration
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Solution Overview
Problem
Spiral-wound membrane filtration elements face flow restriction and membrane fouling due to the presence of separate feed and permeate spacers, which hinder optimal performance in applications like pressure retarded osmosis, forward osmosis, and reverse osmosis.
Innovation Solution
A 3-layer membrane sheet integrates the membrane polymer, permeate carrier, and feed spacer features, with the polysulfone layer incorporating feed spacer patterns and a thicker, more porous polyethylene layer acting as both the support and permeate carrier, and incorporating channels to direct flow, reducing resistance and fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate feed and permeate spacers are used in spiral-wound membrane elements, then structural support and flow path definition are provided, but flow restriction and pressure drop increase significantly
Solution Approach 1:
The patent combines the feed spacer and permeate spacer into a single integrated spacer structure with alternating flow channels. This merging eliminates the need for separate spacer components and reduces the number of interfaces between spacers and membrane, thereby reducing flow restriction and pressure drop while maintaining structural support and flow path definition.
Solution Approach 2:
The integrated spacer performs multiple functions simultaneously: it defines both feed and permeate flow paths, provides structural support to the membrane element, and maintains spacing between membrane layers. This multi-functionality reduces the overall complexity and improves flow efficiency compared to using separate specialized spacers.
2Reliability
If separate feed and permeate spacers are used, then flow paths are defined, but areas of flow restriction contribute significantly to membrane fouling via biological growth, scale formation, and particle capture
Solution Approach 1:
By merging the feed spacer and permeate spacer into a single integrated structure, the patent reduces the number of components and interfaces where fouling can occur. The integrated design eliminates gaps and irregularities between separate spacers, creating smoother flow paths that reduce particle capture and biological growth, thereby improving resistance to fouling.
Solution Approach 2:
The integrated spacer is designed with varying local properties to optimize different regions: wider channels in areas prone to fouling to reduce flow restriction, and appropriately sized channels in other areas to maintain separation efficiency. This local optimization reduces fouling while managing device complexity.
3Adaptability or versatility
If conventional casting methods are used for polymer coating, then membrane sheets are produced, but the design integration of membrane, permeate carrier, and feed spacer features is limited
Solution Approach 1:
The patent merges the membrane layer, permeate carrier, and feed spacer features into a single integrated composite structure. This allows for tailored design of flow channels and spacer features directly within the membrane assembly, enhancing adaptability and versatility while streamlining manufacturing by reducing the number of separate components that need to be assembled.
Data Source
AI summary
Embodiments of the present invention provide the integration of the function of the feed spacer, the permeate carrier, or both, as a part of the membrane sheet in a spiral wound membrane element.