Spiral-Wound Filter Elements with High Flux and Low Pressure Drop
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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, leading to 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
Development of improved spiral-wound filter elements that achieve permeate fluxes of at least 70% of cassette filter performance with a feed channel pressure drop no more than 1.2 times that of cassette filters, featuring compact designs and the ability to be used in single-pass TFF systems without the need for compression housings or liners, utilizing high turbulence-promoting feed screens and optimized membrane configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional spiral-wound filter elements are used, then the system is simpler in structure, but the permeate flux is much lower than cassette filters
Solution Approach 1:
The patent applies parameter changes by modifying the feed channel dimensions (reducing height and width), changing the screen mesh configuration (higher mesh count, smaller opening size), and adjusting the spiral wrap tightness to increase turbulence and reduce boundary layer thickness, thereby significantly improving mass transfer and permeate flux while maintaining the simple spiral-wound structure
2Productivity
If the feed channel length is increased to achieve similar flux as cassette filters, then the permeate flux improves, but the feed channel pressure drop increases significantly
Solution Approach 1:
The patent changes multiple parameters simultaneously: reduces feed channel height from conventional dimensions to approximately 0.04-0.08 inches, reduces feed channel width to approximately 0.1-0.2 inches, increases screen mesh count to 100-200 meshes per inch, and decreases screen opening size to 0.004-0.008 inches. These changes collectively increase turbulence velocity and reduce boundary layer thickness, improving mass transfer coefficient and permeate flux while keeping pressure drop increases within acceptable limits (no more than 1.2 times that of cassette filters)
3Productivity
If cassette filters are used, then high mass transfer rate is achieved, but compression holder assemblies with thick stainless steel plates and alignment rods are required
Solution Approach 1:
The patent extracts and eliminates the complex compression holder assembly (thick stainless steel plates, alignment rods, nuts, hydraulic pistons) by designing a spiral-wound filter element that maintains its structural integrity and feed channel geometry without external compression. The element is encapsulated in a flexible membrane envelope that provides self-support, removing the need for cumbersome holder assemblies while achieving comparable mass transfer rates
4Reliability
If cassette filters are isolated from housing assemblies using liner plates or plastic jackets, then contamination is prevented, but the cost and complexity of filtration systems increase
Solution Approach 1:
The patent applies the disposable principle by making the entire spiral-wound filter element single-use. The element is supplied pre-sterilized and pre-assembled in a flexible membrane envelope, eliminating the need for reusable housing assemblies, liner plates, or plastic jackets. After use, the entire element is discarded, preventing contamination risk while reducing system complexity and cost. This approach trades the reusability of expensive housings for the simplicity and safety of disposable elements
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 improved spiral-wound filter elements achieve high permeate flux with minimal pressure drop, offering cassette-like performance in a compact and user-friendly format, suitable for TFF systems, and can be used in single-use applications without the complexity of compression housings, enhancing ease of use and reducing costs.
Implementation Method 1
utilizing high turbulence-promoting feed screens and optimized membrane configurations
Implementation Method 2
separating the liquid feed into permeate and retentate in the filter element
Data Source
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.