Hybrid CO2 Separation Using Membranes and Cryogenic Condensation
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Solution Overview
Problem
Current methods for recovering CO2 from effluent gas streams are inefficient due to the lack of integration between membrane separation and distillation processes, leading to high energy requirements and limited CO2 recovery rates, especially in flue gases from coal power plants.
Innovation Solution
A method combining gas membrane separation with cryogenic phase separation, using polymeric materials like polyimides and polysulfones in gas separation membranes, followed by cryogenic phase separation to achieve high CO2 recovery rates with reduced energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If membrane separation and distillation are performed in isolation with separate temperature and pressure adjustments, then CO2 separation is achieved, but energy requirements become excessive
Solution Approach 1:
The patent combines membrane separation and distillation into an integrated hybrid system where the membrane unit operates at elevated temperatures (300-400°C) and pressures (20-80 bar) directly coupled with the distillation column. This eliminates separate temperature and pressure adjustments between units, reducing energy consumption while maintaining high CO2 recovery efficiency through continuous operation of both processes at optimized conditions.
Solution Approach 2:
The patent changes the operating parameters of the membrane separation unit to operate at elevated temperatures (300-400°C) and pressures (20-80 bar), which are higher than conventional membrane operations. This parameter change enables the membrane unit to function efficiently at conditions compatible with distillation, reducing the energy penalty of temperature and pressure adjustments while improving overall CO2 recovery productivity.
2Productivity
If multiple CO2 removal methods are used, then CO2 recovery rate increases, but integration of methods for energy savings is overlooked
Solution Approach 1:
The patent merges membrane separation and distillation into a single integrated process flow where the membrane unit feeds directly into the distillation column. This combination achieves high CO2 recovery rates (>90%) while simplifying process integration compared to treating the methods as separate sequential operations, as the hybrid system operates as a unified process with shared optimization parameters.
3Productivity
If CO2 is recovered from flue gases with high recovery rates, then greenhouse gas emissions reduction is achieved, but cost of electricity increases by more than 35%
Solution Approach 1:
The patent changes the operating parameters to elevated temperatures (300-400°C) and pressures (20-80 bar) for the membrane unit, which improves CO2 permeability and selectivity. This enables high CO2 recovery rates (>90%) while reducing the energy penalty compared to conventional low-temperature membrane operations followed by distillation, thereby limiting the electricity cost increase to less than 35%.
Solution Approach 2:
The patent combines membrane separation and distillation into a hybrid system that achieves high CO2 recovery rates (>90%) from flue gases. The integration allows the system to leverage the high selectivity of membranes at elevated temperatures with the high purity capability of distillation, achieving >90% CO2 recovery while limiting electricity cost increases to less than 35% through optimized joint operation.
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 integrated method achieves greater than 90% CO2 recovery from flue gases with a less than 35% increase in electricity costs, eliminating the need for external refrigeration and reducing operational expenses.
Implementation Method 1
The polymeric material has a CO2 solubility at 35° C. and 10 bar pressure of >0.03 [(cm3 of CO2 at STP)/(cm3 of polymeric material)(cmHg)]
Implementation Method 2
The polymeric material has a CO2 solubility at 35° C. and 10 bar pressure of >0.03 [(cm3 of CO2 at STP)/(cm3 of polymeric material)(cmHg)]
Implementation Method 3
The cooled, compressed carbon dioxide-rich stream is subjected to cryogenic phase separation to produce a CO2 rich liquid and a CO2 lean vapor stream
Data Source
AI summary
Disclosed are methods of obtaining carbon dioxide from a CO2-containing gas mixture. The methods combine the benefits of gas membrane separation with cryogenic temperatures.