Staged Fluidized Bed for CO2 Capture
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Solution Overview
Problem
Existing CO2 capture technologies face challenges in achieving efficient mass and heat transfer, leading to high energy penalties and increased costs, particularly in fixed bed systems and moving bed systems with inadequate contact time and heat management.
Innovation Solution
The use of staged fluidized beds with counter-current flow of gas and sorbent, where the sorbent is sequentially fluidized in multiple beds to maximize CO2 uptake and facilitate efficient heat transfer, allowing for effective regeneration and reuse of the sorbent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed beds are used for CO2 capture, then the bed structure can be simple and stationary, but the system requires heating and cooling for each regeneration and adsorption step, increasing energy consumption
Solution Approach 1:
The patent employs moving beds instead of fixed beds, allowing the sorbent to be continuously circulated between adsorption and regeneration zones. This dynamic approach eliminates the need to heat and cool the entire bed structure for each cycle, as only the moving sorbent particles require temperature changes, significantly reducing energy consumption while maintaining structural simplicity
2Stress or pressure
If moving bed system with cross flow is used, then pressure drop is low, but contact time between gas and sorbent is insufficient, reducing CO2 capture efficiency
Solution Approach 1:
The patent divides the moving bed system into multiple staged zones with different flow patterns. By segmenting the contactor into sections with varying residence times and flow configurations, the system maintains low overall pressure drop while providing sufficient contact time in critical zones, thereby improving CO2 capture efficiency without sacrificing pressure characteristics
3Quantity of substance
If counter-current reactor with internal cooling is used, then CO2 loading on sorbent is maximized, but heat and mass transfer are insufficient to manage heat generated during adsorption and heat lost during regeneration
Solution Approach 1:
The patent implements continuous countercurrent circulation of sorbent between adsorption and regeneration zones. This continuous operation allows heat generated during exothermic adsorption to be continuously transferred to the incoming cool sorbent, while heat required for regeneration is continuously supplied. The continuous flow ensures optimal heat and mass transfer throughout the system, maintaining high CO2 loading while effectively managing thermal energy
4Device complexity
If gas/solids contacting in moving bed system is used, then the system is simpler than fixed bed, but gas/solids contacting efficiency is poor, reducing mass transfer
Solution Approach 1:
The patent applies different local conditions within the moving bed system, including varied flow velocities, staged contact zones, and localized mixing elements. These local modifications enhance gas-solids contacting efficiency in specific regions without increasing overall system complexity, thereby improving mass transfer while maintaining the simplicity of the moving bed configuration
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 reduces the energy penalty and cost associated with CO2 capture, enhances CO2 uptake, and minimizes aqueous waste generation, while maintaining effective mass and heat transfer, enabling efficient CO2 capture and regeneration.
Implementation Method 1
a gas stream comprising a target constituent to be removed by a solid sorbent
Implementation Method 2
heat transfer in such a system are unlikely to be sufficient to manage the heat generated during the exothermic adsorption and the heat lost due to the endothermic regeneration
Implementation Method 3
effective mass and heat transfer
Data Source
AI summary
The present disclosure is directed to a process that allows dry sorbents to remove a target constituent, such as carbon dioxide (CO2), from a gas stream. A staged fluidized bed separator enables gas and sorbent to move in opposite directions. The sorbent is loaded with target constituent in the separator. It is then transferred to a regenerator where the target constituent is stripped. The temperature of the separator and regenerator are controlled. After it is removed from the regenerator, the sorbent is then transferred back to the separator.