Compact spiral-wound membrane filter elements
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Solution Overview
Problem
Conventional spiral-wound filter elements have lower flux compared to cassette filters, requiring impractically large pumps or long filtration flow paths, resulting in systems that are neither compact nor easy to use, and they suffer from increased feed channel pressure drops when attempting to match cassette filter performance.
Innovation Solution
The development of spiral-wound filter elements with permeate fluxes at least 70% of mass transfer limited permeate flux of cassette filters and feed channel pressure drops no more than 1.2 times that of cassette filters, achieved through optimized design features such as high turbulence-promoting feed screens, thin permeate screens, and efficient assembly methods, allowing for compact and efficient operation without the need for compression housings or liners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional spiral-wound membrane elements are used, then the system is simpler in structure (no compression holder needed), but the flux is much lower than cassette filters
Solution Approach 1:
The patent changes the geometric parameters of the spiral-wound element, specifically reducing the feed channel height from conventional values to approximately 0.5-2 mm, and optimizing the ratio of feed channel length to membrane area. This parameter optimization enables the spiral-wound element to achieve flux comparable to cassette filters while maintaining the structural simplicity advantage.
Solution Approach 2:
The patent transitions from the conventional spiral-wound configuration to a planar-wound or folded-sheet configuration that maintains the spiral-wound advantage of eliminating compression holders while achieving cassette-filter-level flux through optimized flow path geometry and reduced channel heights.
2Productivity
If the feed channel length is increased to achieve higher flux, then the permeate flux increases, but the feed channel pressure drop increases significantly
Solution Approach 1:
The patent optimizes the feed channel height parameter to approximately 0.5-2 mm, which reduces hydraulic resistance and allows longer effective feed channel lengths to be used without excessive pressure drops. This enables achieving high permeate flux while controlling feed channel pressure drop to no more than 1.2 times that of reference cassette filters.
Solution Approach 2:
The patent divides the filtration process into multiple stages or uses multiple smaller spiral-wound elements in series, each with optimized feed channel lengths, rather than using one extremely long feed channel. This segmentation maintains high overall flux while limiting pressure drop in each segment.
3Productivity
If spiral-wound elements are designed to match cassette filter performance, then permeate flux improves, but feed channel pressure drop increases greatly
Solution Approach 1:
The patent carefully balances the feed channel height parameter (optimizing it to 0.5-2 mm) and the feed channel length-to-membrane area ratio to achieve permeate flux of at least 70% of mass transfer limited permeate flux of reference cassette filters while keeping feed channel pressure drop to no more than 1.2 times that of reference cassette filters.
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
These spiral-wound filter elements provide cassette-like performance with improved permeate flux and reduced pressure drop, enabling compact and user-friendly filtration systems that are suitable alternatives to cassette filters, particularly for single-use applications.
Implementation Method 1
a spiral-wound filter element useful for tangential flow filtration that includes a feed channel, a retentate channel, a permeate channel, a turbulence promoter in the feed channel, and a membrane separating the feed channel from the permeate channel
Implementation Method 2
a turbulence promoter in the feed channel
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral- wound filter elements having cassette-like performance.