Gas Separation Membrane Sweep Gas Pressure Control
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Solution Overview
Problem
Typical gas separation methods using a sweep gas do not effectively enhance permeation efficiency, particularly when the partial pressure of the target gas in the feed gas is less than or equal to the total pressure in the permeate-side space due to a small amount of the gas permeating the membrane.
Innovation Solution
The method involves flowing a sweep gas containing a third gas into the permeate-side space of a gas separation membrane, where the partial pressure of a first gas in the feed gas is less than or equal to the total pressure, while supplying a feed gas containing the first, second, and third gases, ensuring a higher permeation rate of the first gas compared to the second gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a sweep gas is introduced into the permeate-side space to enhance permeation efficiency, then the permeation rate of the target gas increases, but the total pressure in the permeate-side space increases, which reduces the partial pressure difference and diminishes the driving force for permeation when the feed gas contains a small amount of the target gas
Solution Approach 1:
The invention changes the pressure parameters by maintaining the permeate-side space at a reduced total pressure (lower than the feed-side space pressure) while introducing the sweep gas. This parameter change allows the sweep gas to enhance permeation efficiency through increased gas flow and reduced partial pressure of the target gas in the permeate stream, without significantly reducing the overall partial pressure difference driving force, thus resolving the contradiction between improving permeation efficiency and maintaining adequate driving pressure
2Productivity
If the partial pressure of the target gas in the feed gas is less than or equal to the total pressure in the permeate-side space, then the conventional sweep gas method cannot effectively enhance permeation, but introducing additional sweep gas further increases total pressure and reduces the effectiveness of the separation process
Solution Approach 1:
The invention changes the pressure parameter relationship by operating with permeate-side total pressure lower than feed-side pressure, creating a favorable pressure gradient that enables effective permeation even when the target gas partial pressure in feed is low. This parameter change allows conventional sweep gas methods to become effective in previously intractable conditions without adding complex process equipment
Solution Approach 2:
Instead of introducing sweep gas at atmospheric or elevated pressure as in conventional methods, the invention introduces the sweep gas into a reduced-pressure permeate-side space, inverting the conventional pressure relationship. This inversion allows the sweep gas to effectively reduce the partial pressure of the target gas in the permeate stream without creating excessive total pressure that would counteract the permeation driving force
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 enhances the permeation efficiency of the gas separation membrane by increasing the permeation rate of the first gas and concentrating the second gas in the non-permeate fraction.
Implementation Method 1
a permeation rate of the first gas is greater than a permeation rate of the second gas in the gas separation membrane
Data Source
AI summary
The gas separation method is executed under a condition in which a partial pressure of a first gas (G1) in a feed gas that contains at least mutually different gases being the first gas (G1), a second gas (G2) and a third gas (G3) becomes less than or equal to the total pressure of a permeate-side space (S2) of a gas separation membrane (30). The gas separation method includes a step of causing flow of a sweep gas that contains at least the third gas (G3) into the permeate-side space (S2) of the gas separation membrane (30) while supplying a feed gas to a feed-side space (S1) of the gas separation membrane (30). The permeation rate of the first gas (G1) in the gas separation membrane (30) is greater than the permeation rate of the second gas (G2).