Spiral Wound Filter Assembly Radial Flow Scaling
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Solution Overview
Problem
Residential reverse osmosis systems face challenges in operating at high recovery rates due to scale formation from calcium and bicarbonate ions, as they lack pH adjustment or scale inhibitor options, leading to reduced membrane efficiency and lifespan.
Innovation Solution
A filter assembly with a spiral wound membrane module, end cap, and brine seal design that promotes radial feed flow, reduces flux in high concentration areas, and prevents feed flow bypass, allowing for higher recovery operations while minimizing scaling by incorporating a porous outer surface and strategically positioned brine seal to manage pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If residential RO systems operate at high recovery rates, then water production efficiency is improved, but scale formation increases due to concentrated calcium and bicarbonate ions
Solution Approach 1:
The feed flow is segmented into multiple pathways through the spiral wound module, creating numerous small flow channels between membrane leaves. This segmentation prevents localized concentration buildup by distributing feed flow across many parallel paths, reducing the tendency for scale formation while maintaining high overall recovery rates
Solution Approach 2:
The invention transitions from traditional axial feed flow to radial feed flow geometry. Feed enters at the center and flows outward radially through the spiral bundle, creating a two-dimensional flow pattern that enhances mixing and prevents concentration polarization in any single location, thereby reducing scale formation risk at high recoveries
2Object-affected harmful factors
If feed flow velocity is increased to reduce scaling, then scale formation is reduced, but pressure drop increases
Solution Approach 1:
By dividing the feed flow into many parallel channels through the spiral leaves, the velocity in each individual channel can be optimized. The segmented flow path provides sufficient velocity to prevent scaling while distributing the pressure drop across multiple channels, preventing excessive pressure loss
Solution Approach 2:
The radial flow configuration creates dynamic flow patterns with varying velocities across the module radius. Feed velocity is naturally higher near the center and decreases toward the periphery, creating self-regulating flow conditions that prevent scaling without requiring uniformly high velocities throughout, thus managing pressure drop more efficiently
3Ease of manufacture
If conventional axial feed flow is used, then module construction is simple, but feed flow bypass occurs and flux is non-uniform
Solution Approach 1:
The invention adopts radial feed flow geometry where feed enters at the center and flows outward in a two-dimensional pattern. This dimensional change eliminates the bypass issues inherent in axial flow by creating a natural pressure gradient that drives feed through all spiral leaves uniformly, ensuring consistent flux distribution while remaining manufacturable
Solution Approach 2:
The radial flow configuration creates an asymmetric flow pattern concentrated near the center that naturally directs feed through the membrane area. This asymmetric geometry prevents the symmetric bypass paths that occur in axial flow, ensuring feed is forced through the membrane rather than short-circuiting, thereby improving flux uniformity
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
Enables higher recovery rates with reduced susceptibility to scaling, maintaining membrane efficiency and extending system lifespan by ensuring uniform feed flow and pressure management.
Implementation Method 1
a brine seal (65) having a radially extending flexible lip (70) defining a maximum outer diameter adapted to engage the inner chamber of the pressure vessel
Implementation Method 2
In operation, pressurized feed fluid is passed across the surface of the membrane envelope and the applied pressure causes a portion of the 'solvent' (e.g. water) to pass through the membrane (i.e. forming a 'permeate'), while 'solutes' (e.g. salts) are unable to pass through the membrane
Implementation Method 3
the applied pressure causes a portion of the 'solvent' (e.g. water) to pass through the membrane
Implementation Method 4
In another embodiment, the assembly provides a higher feed flow velocity than is typical for the same operating recovery
Data Source
AI summary
A filter assembly adapted for insertion into an inner chamber of a pressure vessel, wherein the assembly includes: a spiral wound membrane module (2) comprising at least one membrane envelope (4) and feed spacer sheet (6) concentrically wound about a central permeate tube (8) extending along an axis (X) forming an inlet scroll face (30) and outlet scroll face (32) and a cylindrical outer peripheral surface (38), an end cap (33) having a surface (72) covering a portion of the inlet scroll face (30) and at least one opening (76) in the end cap surface (72) near the permeate tube for permitting fluid to flow through the inlet scroll face (30) and into the feed spacer sheet (6) of the module (2), and a brine seal (65) having a radially extending flexible lip (70) defining a maximum outer diameter adapted to engage the inner chamber of the pressure vessel; wherein the brine seal is sealed to the end cap (33).