Gas Separation Process Using Selective Membrane Modules
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Solution Overview
Problem
Current gas separation units face challenges in efficiently separating mixtures of non-polar and polar gases, particularly in removing large amounts of polar gases like CO2 and H2S from mixtures with non-polar gases like CH4, due to poor selectivity and permeance, leading to slow separation processes.
Innovation Solution
A process involving a gas separation unit with at least two gas-separation modules arranged in order of decreasing selectivity for polar gases, where the feed gas comprising 1 to 35 mol% polar gases is passed through, utilizing spiral-wound gas-separation modules with specific membrane configurations to achieve both good non-polar gas/polar gas selectivity and permeance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional gas-separation modules with identical selectivity are used, then the separation process is simple, but the selectivity and permeance are insufficient for rapidly removing large amounts of polar gases
Solution Approach 1:
The gas separation unit is divided into multiple gas-separation modules with different selectivities arranged in series. The first module has high selectivity for rapid initial separation, while the second module has lower selectivity for fine-tuning the separation. This segmentation allows the system to achieve both high productivity and appropriate complexity by matching module characteristics to separation stages.
Solution Approach 2:
Different regions of the separation process use modules with locally optimized properties. The first module position uses high-selectivity membranes for rapid polar gas removal, while subsequent positions use lower-selectivity modules. This local quality optimization ensures each part of the system contributes maximally to the overall separation efficiency.
2Manufacturing precision
If high selectivity membranes are used, then polar gas removal efficiency improves, but permeance decreases leading to slower separation
Solution Approach 1:
The separation function is segmented across multiple modules with different membrane selectivities. The first module uses high-selectivity membranes to achieve efficient polar gas removal, while the second module uses lower-selectivity membranes with higher permeance to maintain overall productivity. This segmentation resolves the contradiction by distributing the separation task across modules with complementary characteristics.
Solution Approach 2:
The membrane selectivity parameter is changed between modules rather than using a single membrane type throughout. The first module operates with high-selectivity membranes (αCO2/CH4 > 20), while the second module uses lower-selectivity membranes (αCO2/CH4 = 5-15). This parameter change allows optimization of both selectivity and permeance at different stages of the separation process.
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
This approach enables rapid and selective separation of polar gases from non-polar gases, improving the efficiency of gas separation by enhancing both selectivity and permeance, thus overcoming the limitations of existing technologies.
Implementation Method 1
Each gas-separation module comprises a gas-selective membrane which separates gas into a permeate which passes through the membrane and a retentate which does not pass through that membrane
Data Source
AI summary
A process for separating a feed gas comprising polar and non-polar gases into a gas mixture enriched in polar gas(es) and a gas mixture depleted in polar gas(es), the process comprising passing the feed gas through a gas separation unit comprising at least two gas-separation modules in order of decreasing selectivity for the polar gas(es), wherein the feed gas entering the gas separation unit comprises 1 to 35 mol % of polar gas(es).