Permeate Carrier Border Design for Spiral Wound Membrane Elements
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Solution Overview
Problem
Spiral wound membrane elements face limitations in permeate flow due to increased thickness at the ends caused by adhesive sealing, which reduces the active membrane area and allows fewer membrane leaves to fit within a given pressure vessel diameter, leading to reduced permeate throughput and potential fouling issues.
Innovation Solution
The use of permeate carriers with thinner borders and narrower edges that allow adhesive to spread and penetrate, reducing the thickness of the membrane leaf and preventing blockage of permeate channels, thereby increasing the active membrane area and allowing more membrane leaves to be accommodated within a pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is applied to seal membrane sheets along edges, then the membrane sheets are joined together to form a sealed structure, but the thickness at the ends increases due to adhesive accumulation
Solution Approach 1:
The permeate carrier is designed with varying thickness: a thinner border region at the edges and a thicker central region in the middle. This local quality variation allows adhesive to be contained within the thinner border area during sealing, preventing excessive adhesive accumulation that would increase end thickness, while the thicker central region maintains structural integrity and support for the membrane sheets.
2Productivity
If more membrane leaves are packed into a pressure vessel, then the total membrane area increases for higher permeate throughput, but the increased thickness at ends reduces the number of leaves that can fit
Solution Approach 1:
By making the border regions of the permeate carrier thinner while keeping the central region thicker, the design reduces the overall thickness contribution at the ends of membrane leaves. This allows more membrane leaves to be packed into the same pressure vessel volume, increasing total membrane area and permeate throughput without compromising the structural support function.
3Ease of manufacture
If adhesive lines are applied to seal membrane edges, then the membrane leaf structure is formed, but the active membrane area is reduced due to adhesive coverage
Solution Approach 1:
The thinner border region of the permeate carrier provides a dedicated zone for adhesive application and containment. This local quality variation allows adhesive to be confined to the border area, minimizing the intrusion of adhesive into the active membrane region and preserving maximum active membrane area while still achieving effective sealing.
4Ease of manufacture
If the permeate carrier has uniform thickness, then manufacturing is simplified, but adhesive spreading is uncontrolled and may block permeate channels
Solution Approach 1:
The permeate carrier features a thinner border region and a thicker central region. The thinner border acts as a controlled zone that guides and limits adhesive spreading, preventing adhesive from encroaching on the central region where permeate channels are located. This local quality variation maintains manufacturing simplicity while ensuring reliable permeate channel flow.
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 flow without affecting solute rejection or increasing energy input, allowing for higher membrane area utilization and reduced fouling tendencies by minimizing adhesive contribution to the thickness at the side edges and preventing channel blockages.
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
A transition between the relatively thin border and the central part of the permeate carrier resists adhesive spreading into the central part of the permeate carrier beyond the transition
Data Source
AI summary
Membrane elements that use multiple membrane leaves may have a limited total active membrane area due to an increased diameter at the ends of the element. Membrane leaves may comprise a permeate carrier positioned between one or more membrane sheets. Adhesive may be used to seal one or more edges of the membrane leaf. The membrane sheets, permeate carrier and the adhesive contribute to the thickness of the edges of the membrane leaf and the diameter at the ends of the element. A reduced thickness of the edges of the permeate carrier may reduce the diameter at the ends of an element. Another permeate carrier sheet may also be used that is distanced from at least one edge of the membrane sheet so the permeate carrier sheet does not contribute towards the increased diameter at the ends of the element.