Thinner Border Permeate Carrier for Spiral Wound Membranes
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Solution Overview
Problem
The existing spiral wound membrane elements face issues with reduced active membrane area and blocked permeate channels due to adhesive spreading during the manufacturing process, which limits permeate throughput and membrane leaf placement in pressure vessels.
Innovation Solution
A permeate carrier with thinner borders is used, featuring a transition to control adhesive spreading, thereby maintaining an adequate adhesive width and preventing blockage of permeate channels, which increases the active membrane area and allows for more membrane leaves in a given pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied to seal membrane sheets along the permeate carrier edges, then the membrane sheets are joined together, but the adhesive spreads during compression causing reduction in active membrane area and potential blockage of permeate channels
Solution Approach 1:
The permeate carrier is designed with a thinner border region at its edges, creating a localized structural variation. This thinner border area serves as a dedicated zone for adhesive application and spreading, while the central thicker region maintains full thickness to preserve active membrane area. The local quality change in border thickness allows adhesive to spread within the border without encroaching on the active membrane area.
Solution Approach 2:
The permeate carrier is segmented into functionally distinct regions: a thinner border region for adhesive containment and a thicker central region for maintaining active membrane area and supporting membrane sheets. This segmentation separates the adhesive function from the active membrane function, allowing each region to optimize its specific purpose without interfering with the other.
2Stability of the object's composition
If compression is applied to spread adhesive during winding, then membrane sheets are sealed together, but adhesive lines widen reducing active membrane area
Solution Approach 1:
The thinner border region provides a designated zone where adhesive can spread under compression without reducing the active membrane area in the central thicker region. This local quality variation ensures that sealing integrity is maintained while preserving maximum active membrane area.
3Strength
If adhesive is applied to provide adequate sealing width, then membrane sheets are securely joined, but permeate channels may be blocked by adhesive bulges
Solution Approach 1:
The thinner border region serves as a sacrificial zone that accommodates adhesive bulges and spreading without affecting the thicker central region where permeate channels are located. This ensures adequate sealing width is achieved while preventing blockage of permeate channels in the active membrane area.
Solution Approach 2:
The thinner border acts as an intermediary zone between the adhesive application area and the active membrane area. It mediates the conflict between needing adequate adhesive width for sealing and preventing adhesive intrusion into permeate channels by providing a buffer region that absorbs the adhesive spreading.
4Ease of manufacture
If uniform thickness permeate carrier is used, then manufacturing is simpler, but adhesive spreading cannot be controlled and active membrane area is reduced
Solution Approach 1:
The permeate carrier features local quality variation with thinner borders and a thicker central region. This design balances manufacturing simplicity with functional performance by creating a controlled thickness gradient that manages adhesive spreading while preserving active membrane area, rather than requiring completely uniform thickness throughout.
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 enhances permeate throughput by increasing the active membrane area within a pressure vessel, reducing adhesive-induced membrane area loss and channel blockages, allowing for higher permeate flux without affecting solute rejection or fouling tendency.
Implementation Method 1
Compression applied to the membrane leaf before or while winding the leaf around a central tube, or both, causes the adhesive to penetrate through the permeate carrier to join the two membrane sheets together
Implementation Method 2
The compression applied to the membrane leaf also causes the lines of adhesive to spread or widen, possibly in an uneven manner
Data Source
AI summary
A permeate carrier to be described in detail below has side edges, alternatively called borders, that are thinner than a central part of the permeate carrier. Adhesive is applied to the side edges to form a seal when a membrane leaf is formed around the permeate carrier. After the membrane leaf is wound around a central tube, the side edges extend in a spiral around the central tube. The transition between the side edges and the central part of the permeate carrier helps prevent adhesive from flowing into the central part of the permeate carrier. The reduced thickness of the side edges also reduces an increase in diameter at the ends of an element that might otherwise be caused by the adhesive.