CO2 Separation Device with Membrane Recycling System
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Solution Overview
Problem
The membrane separation method using CO2 separation membranes struggles with low efficiency in reducing CO2 concentration in non-permeable gas to 2% or less, leading to residual CO2 in valuable gases like methane and hydrogen, and increased concentration of other substances in permeable gas, which reduces the collection rate of valuable gases, especially in natural gas with varying CO2 concentrations between 3 and 75%.
Innovation Solution
A CO2 separation device with multiple membrane separators and a recycling system that reintroduces permeable gas back into the source gas stream to increase CO2 partial pressure, improving the driving force for membrane separation and enhancing the purity of both non-permeable CO2 and permeable methane gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If membrane separation is used to remove CO2 from natural gas, then CO2 concentration in non-permeable gas is reduced, but separation efficiency decreases and CO2 remains in non-permeable gas when CO2 concentration is lowered to 2% or less
Solution Approach 1:
The single membrane separation process is divided into multiple stages: a first membrane separator for initial CO2 removal, followed by a second membrane separator for further purification. This segmentation allows each stage to operate at optimal conditions, achieving both high separation efficiency and low residual CO2 concentration in the non-permeable gas stream.
Solution Approach 2:
The first membrane separator performs preliminary CO2 removal to reduce CO2 concentration to a level suitable for the second membrane separator. This preliminary action prevents the second separator from being overwhelmed by high CO2 loads, improving overall separation efficiency while achieving the target CO2 concentration of 2% or less in the final non-permeable gas.
2Quantity of substance
If CO2 concentration in source gas is low, then permeable gas contains higher concentration of other substances, but collection rate of valuable gas decreases
Solution Approach 1:
The system changes the operating parameters of the membrane separators to optimize separation performance for low CO2 concentration source gases. By adjusting pressure differences and flow rates across the membrane stages, the system maintains high collection rates for valuable gases while achieving effective CO2 removal even when source gas contains only 3-75% CO2.
3Force
If pressure difference through membrane is used as driving force, then gas permeation occurs, but CO2 concentration cannot be reduced to 2% or less in non-permeable gas
Solution Approach 1:
The single pressure-driven membrane separation is segmented into multiple stages. The first membrane separator operates at one pressure difference to achieve bulk CO2 removal, then the second membrane separator operates at a different pressure difference to achieve final purification. This segmentation allows each stage to use pressure difference effectively while achieving the stringent 2% or less CO2 concentration requirement in the non-permeable gas.
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 recycling system increases CO2 concentration in the source gas, improving the separation efficiency and purity of CO2 and methane, thereby increasing the collection rate of valuable gases and reducing residual CO2 in non-permeable gas.
Implementation Method 1
membrane separation method by using CO2 separation membrane to obtain non-permeable gas in the separation membrane from which CO2 has been removed from mixed natural gas having CO2 concentration of 3 to 75% by selectively condensing CO2 to permeable gas side of the separation membrane
Data Source
AI summary
A source gas introduction line for introducing source gas containing CO2, a first membrane separator for membrane-separating CO2 from source gas, a first permeable gas discharge line for discharging first permeable gas permeated by membrane separation of the first membrane separator, a first non-permeable gas discharge line for discharging first non-permeable gas not permeated by membrane separation of the first membrane separator, a second membrane separator provided at a downstream side of the first membrane separator and for further membrane-separating CO2 from the first non-permeable gas, a second permeable gas discharge line for discharging second permeable gas permeated by membrane separation of the second membrane separator, a second permeable gas return line branched from a part of the second permeable gas discharge line and for returning the second permeable gas to a source gas side, and a CO2 concentration meter are included.