Permeate Sheet Coating for Molded Channels and High Packing Density
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Solution Overview
Problem
Flat sheet membrane modules have low packing densities and high manufacturing costs compared to hollow fiber membranes, and they cannot be vigorously backwashed for effective cleaning.
Innovation Solution
A permeate sheet with precision-molded permeate channels is created by bonding two non-woven substrate sheets with semi-cylindrical depressions, allowing for increased packing density and mechanical cleaning without frames, and coated with a polymeric membrane layer using a specialized coating device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat sheet membrane modules are used, then manufacturing cost is reduced and robustness is improved, but packing density deteriorates
Solution Approach 1:
The invention uses curved or undulating membrane surfaces instead of flat sheets. The membrane is formed with waves, ridges, or contours that increase the surface area within the same module volume, thereby improving packing density while maintaining the robustness and manufacturing advantages of flat sheet membranes.
Solution Approach 2:
The invention transitions from two-dimensional flat membrane surfaces to three-dimensional curved surfaces. By adding dimensional complexity through waves and contours, the membrane surface area is dramatically increased without proportionally increasing the module volume, thus improving packing density.
2Strength
If flat sheet membrane panels are used, then structural robustness is improved, but mechanical cleaning capability deteriorates
Solution Approach 1:
The curved membrane surface allows backwash water to flow more effectively across the membrane during mechanical cleaning. The contours and waves create pathways that enhance the mechanical scouring action of backwash water, improving cleaning capability while maintaining structural robustness.
3Productivity
If hollow fiber membranes are used, then packing density is improved, but material flexibility and cost-effectiveness deteriorate
Solution Approach 1:
The invention applies curvature to flat sheet membranes to achieve packing densities comparable to hollow fiber membranes. This allows the use of more flexible and cost-effective flat sheet membrane materials while achieving high packing density through geometric optimization rather than relying on hollow fiber structures.
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 solution enhances packing density and cleaning efficiency, reducing costs and improving performance to match or exceed hollow fiber systems, while enabling the use of rigid polymers and novel membrane materials.
Implementation Method 1
the substrate is coated with a dope and quenched or coagulated to form a membrane sheet
Implementation Method 2
a semi-porous membrane layer on both sides of the substrate sheet to form a membrane sheet
Data Source
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AI summary
A coating device having one or more dope outlets, a coating knife, and a guide section configured to engage the protrusions on a membrane substrate, the coating device defining a slot adapted to receive the membrane substrate. A process for coating a permeate sheet having protrusions formed thereupon consists of drawing the permeate sheet through a coating knife having a pattern corresponding to the permeate sheet while providing a dope to both sides of the sheet. Another device and process incorporates a cylindrical roller and a platen.