Polymeric Gas Separation Membrane Simultaneous Stretching Leaching
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Solution Overview
Problem
Existing gas separation membranes face a trade-off between gas flux and selectivity, where increasing gas flux through stretching reduces selectivity, limiting the efficiency and cost-effectiveness of gas separation systems.
Innovation Solution
A method of making polymeric fibers for gas separation membranes by simultaneously stretching and leaching solvent and non-solvent components, using polysulfone with a specific composition and controlled roller speeds to balance tensioning and extraction rates, enhancing both gas flux and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fiber is stretched to increase gas flux, then gas flux is improved, but selectivity is reduced
Solution Approach 1:
The patent combines the stretching process and solvent extraction process into a single simultaneous operation. The fiber is stretched while the solvent and non-solvent are being leached out, allowing both flux enhancement and selectivity preservation to occur together rather than sequentially. This merging resolves the contradiction by achieving both goals in one integrated process step.
Solution Approach 2:
The patent changes the physical and chemical parameters during the simultaneous stretching and extraction process. Specifically, it controls the composition ratio of solvent to non-solvent (2.0-3.0:1), the stretching rate, and the timing of the process to optimize both flux and selectivity. By carefully controlling these parameters, the patent achieves improved gas flux while maintaining selectivity, resolving the traditional trade-off between these two properties.
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 method results in polymeric fibers with improved gas flux and selectivity, reducing capital costs and increasing the efficiency of gas separation processes while avoiding the traditional loss of selectivity with increased stretching.
Implementation Method 1
Various polymers have the property that they allow different gases to flow through, or permeate, the membrane, at different rates
Implementation Method 2
The gas that preferentially flows through the membrane wall is called the 'permeate' gas, and the gas that tends not to flow through the membrane is called the 'non-permeate' or 'retentate' gas
Implementation Method 3
the solvent and non-solvent components of the spin dope are leached from the fiber
Data Source
AI summary
A polymeric fiber for use in gas separation is formed from a spin dope which includes solvent and non-solvent materials. The fiber is passed through a quench bath, and then a leach bath, in which the solvent and non-solvent are removed. The quench bath and the leach bath include sets of rollers which transport the fiber through the system. Each set of rollers in the leach bath operates at a speed which is greater than or equal to the speed of the rollers which are immediately upstream. Thus, the fiber is stretched, in different amounts, at the same time that the solvent and non-solvent are being removed, and while the fiber is still wet. The resulting fiber has been found to exhibit superior flux and selectivity properties.