Coiled Membrane Module for Countercurrent Diffusion Dialysis
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Solution Overview
Problem
The high investment and operating costs of diffusion dialysis systems, primarily due to the expensive membrane modules required for large-scale industrial implementation, and the challenge of achieving countercurrent flow in membrane coils for Donnan dialysis, which has not been successfully converted from flat to hollow fiber or tube geometry.
Innovation Solution
A membrane module design featuring at least two flow channels formed by winding sections of membrane foil around a central body with spacers, allowing for countercurrent operation and efficient fluid flow, utilizing sealing elements and deflection foils to create separate flow channels and ensure sealing, and materials like polypropylene and polyethylene for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plate-and-frame systems with sealing frames are used, then tight sealing can be achieved, but device complexity and investment costs increase significantly
Solution Approach 1:
The module is divided into repeating units, each consisting of a membrane element with integrated sealing structures. Each unit is self-contained with its own sealing mechanism, allowing modular assembly without complex global sealing systems. The segmentation of functions (membrane separation, sealing, structural support) into distinct but integrated components simplifies the overall design while maintaining reliability.
Solution Approach 2:
The sealing elements are nested within the membrane structure itself, with sealing frames integrated directly into the membrane element assembly. The membrane is positioned within a frame structure that provides both mechanical support and sealing functionality, eliminating the need for separate external sealing systems. This nested integration reduces the number of discrete parts and simplifies assembly.
2Reliability
If conventional plate-and-frame systems with high contact pressure are used, then tight sealing is achieved, but operating costs and device complexity increase
Solution Approach 1:
The sealing elements are pre-assembled and pre-positioned within the membrane structure during manufacturing, ensuring proper alignment and contact pressure distribution before the module is installed. The sealing frames are pre-configured with the membrane in a controlled manufacturing environment, eliminating the need for complex field assembly and high-pressure installation procedures.
Solution Approach 2:
The sealing mechanism transitions from relying on high contact pressure to utilizing optimized geometric parameters of the sealing elements. The sealing frame cross-section and membrane positioning are designed with specific dimensional parameters that create effective sealing through structural geometry rather than excessive pressure, reducing both manufacturing complexity and operating costs.
3Productivity
If large membrane areas are used for industrial implementation, then processing capacity increases, but investment costs increase
Solution Approach 1:
Large membrane areas are achieved through parallel assembly of multiple identical module units rather than creating a single large complex structure. Each unit maintains a simple, standardized design that is easy to manufacture and install, while the overall system capacity scales linearly with the number of units. This segmentation allows industrial-scale processing capacity while maintaining simplicity at the component level.
Solution Approach 2:
The membrane element design is universal and can be replicated indefinitely with the same simple structure. Each module unit serves multiple functions (separation, sealing, structural support, flow distribution) within a single integrated design, allowing scalable deployment without increasing per-unit complexity. The same basic design can be used for different application scales by simply adding or removing identical units.
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 cost-effective and efficient recovery of acids and bases through countercurrent dialysis, with the membrane module capable of regenerating 10 to 15 liters of acid or lye per hour and maintaining over 95% acid recovery and 99% salt retention, with a service life of approximately 2 years and over 100 cubic meters of acid recovery per year.
Implementation Method 1
The Donnan effect is based on the concentration difference between two solutions separated by a semipermeable membrane
Implementation Method 2
at least one first section of at least one membrane film and at least one second section of the at least one membrane film onto a central body
Implementation Method 3
a winding of the at least one first section is spaced apart from a winding of the at least one second section by at least one spacer, whereby two separate flow channels are formed during winding
Implementation Method 4
The at least one first section of the at least one membrane film is attached to at least one first sealing element which is attached to the central body and clamps the at least one first section of the at least one membrane film for sealing
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a membrane module (10a, 10b) for the diffusion dialysis of fluids, having at least two flow channels (8a, 8b) which are made by coiling at least one first section (3a) of at least one membrane film and at least one second section (3b) of the at least one membrane film onto a central body (1). A coil of the at least one first section (3a) is spaced from a coil of the at least one second section (3b) by at least one spacer (9), whereby two separate flow channels (8a, 8b) are formed upon coiling, each flow channel being delimited by the at least one membrane film.