Membrane-Cryogenic CO2 Separation for Lower-Energy Flue Gas Capture
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Solution Overview
Problem
Current methods for CO2 recovery from effluent gas streams are inefficient due to the lack of integration between membrane separation and cryogenic phase separation, leading to high energy requirements and increased costs, particularly in capturing over 90% of CO2 from flue gases of existing pulverized coal power plants with minimal cost escalation.
Innovation Solution
A method integrating gas membrane separation with cryogenic phase separation, utilizing specific polymeric materials like polyimides and polysulfones, and optimizing pressure and temperature conditions to achieve greater than 90% CO2 recovery with less than 35% increase in electricity costs, using a combination of membrane separation and cryogenic phase separation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If membrane separation and distillation are performed in isolation with temperature and pressure adjustments before each process, then CO2 separation is achieved, but energy requirements become inefficient
Solution Approach 1:
The patent combines membrane separation and distillation processes into an integrated system where the membrane unit operates at high pressure and the distillation unit operates at low pressure, with the membrane permeate directly fed to the distillation column. This merging eliminates intermediate compression and heating steps, reducing energy consumption while maintaining high CO2 recovery efficiency.
Solution Approach 2:
The patent optimizes operating parameters by maintaining the membrane unit at high pressure (30-100 bar) and the distillation unit at low pressure (1-10 bar), with temperature adjustments only where necessary. This parameter optimization reduces the energy required for temperature and pressure adjustments between processes.
2Manufacturing precision
If multiple methods (membrane separation and distillation) are used for CO2 recovery, then CO2 separation efficiency improves, but integration of the two methods has been overlooked leading to increased energy consumption
Solution Approach 1:
The patent creates a continuous process where CO2-rich permeate from the membrane unit is directly fed to the distillation column without interruption. This continuous operation eliminates idle time and redundant processing steps, maintaining high separation efficiency while reducing energy loss through optimized heat integration and eliminated intermediate cooling/heating cycles.
3Quantity of substance
If flue gas from pulverized coal power plants is processed for CO2 recovery, then CO2 capture is achieved, but cost escalation exceeds acceptable limits
Solution Approach 1:
The patent employs heat integration where the exothermic condensation process in the distillation unit provides heat for the membrane unit and other process streams. This self-service heat exchange system reduces external energy requirements, lowering operational costs while maintaining high CO2 recovery amounts from flue gas processing.
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 integrated method effectively recovers over 90% of CO2 from flue gas streams with reduced energy consumption and operational costs, eliminating the need for external refrigeration and enhancing the efficiency of CO2 capture from coal-fired power plants.
Implementation Method 1
a polymeric membrane which selectively separates CO2 from other components in the CO2-containing gas mixture
Implementation Method 2
cooling the CO2-rich stream to condense CO2 therein
Implementation Method 3
compressing the CO2-containing gas mixture to a pressure from 3 bar to 60 bar
Implementation Method 4
depressurizing the CO2-rich liquid to a pressure from 1 bar to 30 bar
Data Source
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AI summary
A method of obtaining carbon dioxide from a CO2 - containing gas mixture, said method comprising the steps of flowing the cooled gas mixture into a gas separation membrane module to produce a carbon dioxide -rich permeate and a carbon dioxide- lean non-permeate, separating the partially condensed compressed carbon dioxide -rich permeate into a C02 rich liquid and a C02 lean vapor stream, providing cold energy with one or more streams selected from the group consisting of the cold carbon dioxide- lean stream, the C02 lean vapor stream, and a portion of the C02 rich liquid.