Temperature vacuum swing adsorption process suited for carbon capture to regenerate sorbents using the CO2 product gas as the heat transfer medium
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Solution Overview
Problem
Solid sorbents like zeolites in direct air capture (DAC) processes face challenges due to low thermal conductivity, requiring complex and costly heat transfer systems for regeneration, and existing heating methods either consume additional energy or reduce CO2 capture capacity.
Innovation Solution
A modified temperature vacuum swing adsorption (TVSA) process utilizing CO2 as the heating medium, either alone or in conjunction with internal or external heaters, to efficiently heat the adsorbent bed and achieve high-purity CO2 product streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heating methods (external heaters, steam, or flowing gas) are used to regenerate the sorbent bed, then the sorbent can be regenerated, but additional energy is consumed or the CO2 product stream is diluted
Solution Approach 1:
The CO2 product gas, which would otherwise be wasted, is recirculated through the sorbent bed to provide the heat necessary for regeneration. The system uses its own output (CO2 gas) to serve the heating function, eliminating the need for external energy inputs while maintaining regeneration effectiveness
Solution Approach 2:
Instead of discarding the CO2 gas after capture, the system recovers and recirculates it through the sorbent bed during the regeneration phase. This recovered CO2 serves dual purposes: it provides the necessary heat for desorption and ensures high purity of the final CO2 product stream
2Reliability
If conventional heating methods (external heaters, steam, or flowing gas) are used to regenerate the sorbent bed, then the sorbent can be regenerated, but the CO2 product stream purity is reduced due to dilution
Solution Approach 1:
The CO2 product gas is used to heat the sorbent bed during regeneration, ensuring that only CO2 is present in the system during this phase. This self-heating approach prevents contamination from external gases and maintains high product purity
Solution Approach 2:
The CO2 gas is recovered and recirculated through the sorbent bed, ensuring that the heating medium is pure CO2. This prevents dilution of the product stream with air or other gases that would occur with conventional heating methods
3Temperature
If steam is used to heat the sorbent bed, then heating is effective, but CO2 capture capacity is reduced and sorbent stability is compromised
Solution Approach 1:
The system changes the heating medium from steam to CO2 gas, altering the chemical environment during regeneration. This parameter change prevents the capacity reduction and stability issues associated with steam exposure while maintaining effective heating through the recirculated CO2
4Temperature
If closely packed heat exchangers are used to heat the sorbent bed, then heating efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The sorbent bed is heated by the recirculated CO2 gas flowing directly through it, eliminating the need for separate heat exchanger systems. The CO2 itself serves as the heating medium, simplifying the overall device architecture while maintaining heating efficiency
Solution Approach 2:
The system uses gas flow (CO2 recirculation) to transfer heat through the sorbent bed, utilizing pneumatic principles to achieve heating without complex thermal contact systems. This approach simplifies the hardware while maintaining effective heat transfer
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 enables efficient heating of the sorbent bed, reduces energy consumption, and maintains high CO2 capture efficiency and purity, particularly when using zeolites, by leveraging the product CO2 gas for regeneration.
Implementation Method 1
utilizing the product CO2 gas as the heat transfer medium
Implementation Method 2
the temperature is increased to a point where the species of interest, i.e., carbon dioxide, starts to desorb
Implementation Method 3
the temperature is increased to a point where the species of interest, i.e., carbon dioxide, starts to desorb
Data Source
AI summary
Solid sorbents, and especially zeolites, are attractive candidates for CO2 direct air capture (DAC) and point source capture applications because of their potential for high selectivity, fast kinetics, and low energy CO2 capture cycles. A common issue with solid sorbents, including zeolites, is their low thermal conductivity, which makes them difficult to heat for regeneration without using complex and expensive heat transfer systems. This invention utilizes a modified TVSA process which utilizes the product CO2 gas itself as the heating medium for the adsorbent bed, alone or in conjunction with internal or external heaters. The use of CO2 as a heating medium allows efficient heating of the sorbent bed and enables high purity CO2 product.