RCTSA CO2 Capture Using Compression Heat
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Solution Overview
Problem
Current temperature swing adsorption (TSA) processes for CO2 capture from flue gas face inefficiencies due to long cycle times, heat management challenges, and energy losses, particularly when separating CO2 from flue gas streams for sequestration, as they often require extensive heating and have difficulties in recovering heat effectively.
Innovation Solution
A rapid cycle thermal swing adsorption (RCTSA) process using a parallel channel contactor with microporous adsorbent materials, where CO2 is captured from flue gas streams, heated to desorb CO2, and the heat from the compressed CO2-rich stream is reused for regeneration, with a cycle time of less than 2 minutes to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional TSA processes are used for CO2 capture, then CO2 separation is achieved, but cycle times are long and energy efficiency is low
Solution Approach 1:
The patent implements rapid cyclic switching between multiple contactors (at least three contactors in sequence) where each contactor undergoes quick adsorption-desorption cycles. The system alternates between feeding flue gas to active contactors and rapidly heating/regenerating them, achieving cycle times of minutes rather than hours. This periodic action with multiple contactors in series enables continuous high-rate CO2 capture while minimizing idle time.
Solution Approach 2:
The patent pre-heats the adsorbent material in dedicated contactors before they are needed for CO2 capture. By maintaining contactors in a pre-conditioned state (pre-heated and ready for adsorption), the system eliminates the time lag associated with heating adsorbents on-demand. This preliminary preparation of adsorbent beds enables immediate high-capacity CO2 uptake when flue gas is introduced.
2Quantity of substance
If high temperatures are used for desorption, then CO2 release is enhanced, but energy consumption increases
Solution Approach 1:
The patent combines the heating function with the CO2 desorption function in the same contactor. The contactor that has completed CO2 capture is directly fed with heating gas (such as flue gas or process gas) that raises the temperature and simultaneously drives CO2 desorption. This merging of heating and desorption operations in a single vessel eliminates the need for separate heating steps and reduces overall energy consumption.
Solution Approach 2:
The patent utilizes the heat that would otherwise be wasted in the flue gas stream (a harmful waste heat) as the heating source for desorption. By routing hot flue gas or process gas through the adsorbent bed during regeneration, the system converts waste thermal energy into useful heating for CO2 release, significantly reducing the energy penalty of the desorption step.
3Loss of energy
If heat is recovered from compressed CO2 stream, then energy efficiency improves, but heat management complexity increases
Solution Approach 1:
The patent maintains continuous operation by having multiple contactors in different phases of the adsorption-desorption cycle simultaneously. While one contactor is being heated for desorption, another is capturing CO2, and a third is being cooled. This continuous cycling through multiple contactors ensures that heat recovery operations are always active and synchronized with compression operations, maintaining steady-state energy efficiency without intermittent shutdowns or complex batch operations.
Solution Approach 2:
The patent uses a heat exchanger as an intermediary device to transfer heat from the compressed CO2 stream to the incoming flue gas or process gas that will be used for desorption. This intermediary heat exchange mechanism efficiently captures waste heat from compression and redirects it to the desorption process, reducing energy losses while avoiding direct thermal contact between streams and simplifying heat management.
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 significantly reduces energy requirements for CO2 capture, achieves high CO2 purity (>95 mol%), and minimizes energy spent on diluents like nitrogen, while efficiently managing heat through interstage cooling and thermal wave regeneration, enabling continuous processing with multiple contactors.
Implementation Method 1
a) conducting said flue gas stream to a temperature swing adsorption gas separation unit wherein the gas separation unit contains at least one adsorbent contactor... wherein the surface of said flow channels is comprised of an adsorbent material that is capable of adsorbing CO2 from said flue gas stream
Implementation Method 2
c) heating said contactor having CO2 adsorbed thereon to an effective temperature that results in the desorption of at least a fraction of CO2
Implementation Method 3
d) compressing said CO2-rich stream to a pressure in excess of about 6.9 MPa (1000 psig) thereby resulting in a compressed CO2-rich stream whose temperature has been substantially raised during compressing
Implementation Method 4
e) cooling said compressed CO2-rich stream by use of a suitable heat-exchange fluid at a first temperature that captures heat from said CO2-rich stream
Implementation Method 5
efficiently managing heat through interstage cooling and thermal wave regeneration
Data Source
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AI summary
Adsorption of CO2 from flue gas streams using temperature swing adsorption. The resulting CO2 rich stream is compressed for sequestration into a subterranean formation and at least a portion of the heat of compression is used in the desorption step of the temperature swing adsorption process.