Forward Osmosis Membrane Integrity Evaluation via Transmembrane Pressure
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Solution Overview
Problem
Existing forward osmosis membranes used in dialysis fluid production are prone to undetected integrity issues, allowing transport of components other than water, which can compromise the quality of the dialysis fluid.
Innovation Solution
A method and control arrangement for evaluating the integrity of forward osmosis membranes by monitoring transmembrane pressure (TMP) after stopping fluid flows, analyzing the TMP's magnitude, relaxation rate, and comparing against predefined criteria to detect integrity errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forward osmosis membranes are used to separate water from contaminants, then water separation efficiency is improved, but undetected integrity issues may allow non-water components to transport across the membrane
Solution Approach 1:
The patent applies preliminary action by performing integrity testing of the forward osmosis membrane before it is put into service. The method involves stopping fluid flows, allowing TMP to reach maximum value, and monitoring pressure characteristics to detect integrity issues beforehand, preventing compromised membranes from entering operation.
Solution Approach 2:
The patent implements feedback by continuously monitoring transmembrane pressure (TMP) and its relaxation characteristics after flow cessation. The control arrangement analyzes TMP magnitude, relaxation rate, and compares against predefined criteria to provide real-time feedback on membrane integrity, enabling detection of subtle integrity issues that would otherwise go unnoticed.
2Measurement precision
If membrane integrity testing is performed continuously, then detection capability is improved, but system complexity and operational disruption increase
Solution Approach 1:
The patent applies periodic action by conducting integrity tests at specific intervals rather than continuously. The method involves stopping fluid flows, allowing TMP to reach maximum value, and monitoring for a predetermined time period. This periodic approach maintains detection capability while reducing system complexity and operational disruption compared to continuous monitoring.
Solution Approach 2:
The patent implements self-service by utilizing the membrane's own operational characteristics (TMP relaxation behavior) as the detection mechanism. The membrane's natural pressure relaxation after flow cessation provides the test signal, eliminating the need for external complex testing equipment and reducing system complexity while maintaining measurement precision.
3Productivity
If flow rates are increased to improve dialysis fluid production, then productivity is improved, but transmembrane pressure variations make integrity detection more difficult
Solution Approach 1:
The patent applies preliminary action by performing integrity testing before the membrane is put into high-productivity operation. The testing is conducted under controlled conditions with predetermined flow rates, allowing the membrane to be evaluated for integrity issues before it enters service at higher productivity levels where TMP variations would obscure detection.
Solution Approach 2:
The patent implements dynamics by adapting the testing protocol to the membrane's operational state. The method involves dynamically adjusting flow rates during testing to reach maximum TMP, then monitoring the relaxation phase. This dynamic approach allows integrity detection to be performed under conditions that replicate high-productivity operation while maintaining detection precision through controlled variable changes.
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
Provides a reliable and automated way to assess membrane integrity, enabling detection of small leaks and solute transport, ensuring the quality of dialysis fluid production.
Implementation Method 1
A FO-membrane is typically designed to be more or less exclusively selective towards water molecules, which enables the FO-membrane to separate water from all other contaminants
Implementation Method 2
An osmotic pressure difference between a feed solution and a draw solution separated by the FO-membrane is used for extracting pure water from the feed solution to the dialysis concentrate
Data Source
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AI summary
A control arrangement (10) and method for evaluating the integrity of a forward osmosis (FO-) membrane (2c) of a FO device (2) in a dialysis solution generation apparatus (1), the FO-membrane (2c) separating a feed side (2a; 2b) and a draw side (2a; 2b) of the FO device (2), the FO-device (2) comprising a feed inlet port (Ein) and a feed outlet port (Eout) in fluid communication with the feed side (2a; 2b), and a draw inlet port (Lin) and a draw outlet port (Lout) in fluid communication with the draw side (2a; 2b). The method comprises providing (S1) a flow of feed solution at the feed side (2a; 2b) via the feed inlet port (Ein) and providing (S2) a flow of draw solution at the draw side (2a; 2b) via the draw inlet port (Lin), with an osmotic pressure at the draw side (2a; 2b) that is higher than an osmotic pressure at the feed side (2a; 2b), whereby water is extracted from the feed side (2a; 2b) to the draw side (2a; 2b) to dilute the draw solution. The method further comprises stopping (S3) flow via the draw inlet port (Lin), the feed inlet port (Ein) and the feed outlet port (Eout); whereby water will continue to be extracted from the feed side (2a; 2b) to the draw side (2a; 2b), until a transmembrane pressure (TMP) between the draw side (2a; 2b) and the feed side (2a; 2b) has reached a maximum value. The method further comprises monitoring (S4) one or more pressures indicative of the TMP; and evaluating the integrity (S8) of the FO-membrane based on monitored one or more parameters including the one or more pressures indicative of the TMP. The disclosure also relates to a solution generation apparatus (1) for generating dialysis solution.