Structured Adsorbent Beds for Low-Pressure CO2 Capture
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Solution Overview
Problem
Current CO2 capture technologies, such as chemical absorption and traditional Temperature Swing Adsorption (TSA) processes, face inefficiencies and high costs due to high energy consumption, large equipment requirements, and low adsorbent loading when dealing with low-pressure, low-concentration CO2 sources like flue gas, especially when trying to reduce cycle time and maintain productivity.
Innovation Solution
A rapid thermal swing adsorption (RTSA) method utilizing structured adsorbent beds with parallel passage contactor designs, such as monoliths, laminates, and fabrics, which reduces pressure drop and increases mass transfer and heat transfer rates, allowing for faster cycle times and higher adsorbent loading without increasing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional TSA with standard adsorbent particles is used, then adsorption capacity is maintained, but cycle time is too long (greater than 1 hour)
Solution Approach 1:
The patent uses structured adsorbent materials with controlled pore structures (monoliths, laminates, fabrics) that provide high surface area for adsorption while maintaining open pathways for rapid gas flow. These porous structured materials enable fast mass transfer and short cycle times without sacrificing adsorption capacity.
Solution Approach 2:
The patent transitions from conventional three-dimensional packed bed adsorbents to two-dimensional structured adsorbents (laminates, fabrics, monoliths). This dimensional change reduces the gas passage length and increases the surface area to volume ratio, enabling rapid adsorption and desorption cycles in minutes rather than hours.
2Productivity
If adsorbent particle size is reduced to decrease cycle time, then mass transfer rate increases, but pressure drop increases and fluidization occurs
Solution Approach 1:
The patent employs porous structured adsorbents with optimized pore size distributions that allow rapid mass transfer while maintaining mechanical strength. The porous structure provides internal pathways for gas flow that prevent pressure build-up and fluidization, even at high gas velocities required for short cycle times.
Solution Approach 2:
The patent uses composite structured adsorbents combining multiple materials with complementary properties. For example, combining high-surface-area adsorbent particles with a porous support structure creates a composite that maintains particle integrity while providing open pathways for gas flow, preventing fluidization at high gas velocities.
3Productivity
If adsorbent bed depth is reduced to decrease cycle time, then adsorption time shortens, but adsorbent loading decreases
Solution Approach 1:
The patent transitions from deep bed adsorption to thin-bed structured adsorption where the adsorption surface area is dramatically increased through two-dimensional structures. This allows short contact times (minutes) while maintaining high adsorbent loading through increased surface area to volume ratio.
Solution Approach 2:
The patent uses porous structured adsorbents with high internal surface area that provide extensive adsorption capacity within thin beds. The porous structure allows rapid penetration of gas through the thin bed while maintaining high contact efficiency, achieving both short adsorption times and high adsorbent loading.
4Productivity
If chemical absorption with MEA solvent is used, then CO2 removal efficiency is high, but regeneration energy requirements are high
Solution Approach 1:
The patent replaces chemical absorption processes with physical adsorption using structured adsorbents. This substitution eliminates the need for high-temperature steam regeneration required by chemical absorption, reducing energy consumption while maintaining high CO2 removal efficiency through selective adsorption and pressure swing cycles.
Solution Approach 2:
The patent changes the operating parameters from chemical absorption (high temperature, high pressure) to physical adsorption (moderate temperature, variable pressure). By using pressure swing adsorption with structured materials, the process achieves efficient CO2 capture with lower energy requirements, particularly avoiding the high regeneration energy needed for chemical solvent regeneration.
5Productivity
If compression is applied to increase CO2 concentration, then CO2 capture efficiency improves, but energy consumption increases
Solution Approach 1:
The patent replaces mechanical compression with pressure swing adsorption using structured adsorbents. The process utilizes pressure differentials to drive gas through the adsorbent bed, enabling CO2 capture without energy-intensive compression. The structured adsorbents provide high surface area for efficient adsorption at atmospheric or low pressures, eliminating the need for high-pressure compression.
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 RTSA method significantly enhances CO2 productivity by achieving faster cycle speeds, lower pressure drops, and higher overall adsorbent loading, making it economically viable for large gas flow applications, particularly in capturing CO2 from low-pressure sources with concentrations between 5 to 30% in flue gas.
Implementation Method 1
Temperature Swing Adsorption method for separating a first component, comprising a more adsorbable component, from a feed stream
Implementation Method 2
Heating the adsorbent structure to desorb the adsorbed first component by means of circulating a heating stream
Implementation Method 3
cooling the structure by means of passing through it more than 50% of the stream enriched in the second component
Implementation Method 4
Temperature Swing Adsorption method for separating a first component, comprising a more adsorbable component, from a feed stream
Data Source
AI summary
A Temperature Swing Adsorption method for separating a first component, comprising a more adsorbable component, from a feed stream comprising more than 50 mol % of a second component, comprising a less adsorbable component, is provided. The method includes providing an adsorbent structure suitable for adsorbing the first component, the structure being of the parallel passage contactor type, and cyclically implementing the following steps. Passing the feed stream through the adsorbent structure thus adsorbing the first component and producing a stream depleted in the first component and enriched in the second component. Heating the adsorbent structure to desorb the adsorbed first component by means of circulating a heating stream enriched in the first component at a temperature suitable for regeneration. And cooling the structure by means of passing through it more than 50% of the stream enriched in the second component produced in the step a).