Two-Stage Membrane Separation With Turbine-Driven Permeate Compression
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Solution Overview
Problem
Existing membrane separation processes for hydrogen and carbon dioxide mixtures are inefficient in energy use and yield, particularly due to energy loss during expansion of residual gases, which can be prohibitive when electricity is cheap.
Innovation Solution
A process involving reheating the mixture in a heat exchanger, followed by membrane separation in two stages, with permeate cooling and compression in a booster compressor, and residue expansion in a turbine to drive the compressor, optimizing energy use and increasing separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the residue from membrane separation is expanded in a valve, then the equipment is simple, but energy is lost during expansion
Solution Approach 1:
The invention converts the harmful energy loss during expansion into useful work by using a turbine to expand the residue gas. The turbine generates mechanical energy that drives the booster compressor, transforming what would be wasted energy into a useful function that reduces overall energy consumption of the system.
Solution Approach 2:
The system achieves self-service by using the expansion energy of the residue gas to power the booster compressor through the turbine. The residue gas itself provides the energy needed for its own compression, reducing external energy input requirements and improving overall system efficiency.
2Productivity
If permeate is compressed in a booster compressor, then separation yield increases, but energy consumption increases
Solution Approach 1:
The invention merges the function of the turbine and booster compressor into an integrated energy exchange system. The turbine and compressor are coupled such that the turbine drives the compressor, combining the expansion of residue gas with the compression of permeate to create a synergistic energy recovery system.
Solution Approach 2:
The system converts the wasted expansion energy of residue gas into useful compression work for the permeate. By using the turbine-compressor coupling, the energy that would be lost during residue expansion is transformed into the compression energy needed for permeate, reducing external energy requirements.
3Productivity
If multiple membrane separation units are used, then CO2 capture yield increases, but device complexity increases
Solution Approach 1:
The invention extracts and recovers energy from the residue gas stream using a turbine, separating this energy recovery function from the membrane separation units themselves. This allows the membrane units to focus on separation while the turbine handles energy recovery, reducing the overall complexity needed to achieve high CO2 capture yields.
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 process enhances energy efficiency and yield by reducing permeate pressure, increasing separation efficiency, and allowing higher CO2 capture and hydrogen production with fewer units, while maintaining selectivity and reducing recompression energy.
Implementation Method 1
heating of the mixture in a heat exchanger up to a first temperature
Implementation Method 2
cooling of at least one portion of the first permeate in the heat exchanger
Implementation Method 3
permeation of the mixture reheated to the first temperature, in a first membrane separation unit making it possible to obtain a first permeate which is hydrogen and carbon dioxide enriched
Implementation Method 4
the second residue is expanded in a turbine
Implementation Method 5
at least one portion of the first permeate, cooled in the heat exchanger, is compressed in a booster compressor
Data Source
AI summary
A process for membrane separation of a mixture containing as main, or even major, components hydrogen and carbon dioxide and also at least one other component, for example chosen from the following group: carbon monoxide, methane and nitrogen, including: heating of the mixture in the heat exchanger, permeation of the reheated mixture in a first membrane separation unit making it possible to obtain a first permeate which is a hydrogen and carbon dioxide enriched relative to the mixture, and a first residue which is hydrogen and carbon dioxide lean, permeation of the first residue in a second membrane separation unit making it possible to obtain a second residue, at least one portion of the first permeate is compressed in a booster compressor and the second residue is expanded in a turbine, the booster compressor being driven by the turbine.