Cross-Flow Rotating Packed Bed for Gas Capture
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Solution Overview
Problem
Current rotating packed bed (RPB) gas capture systems for carbon capture and storage (CCS) are large and inefficient, requiring significant space and volume, and struggle with uniform sorbent distribution and axial gas flow, which affects mass transfer efficiency.
Innovation Solution
A cross-flow RPB design with concentric packing materials and sorbent redistribution systems ensures uniform sorbent distribution and reduced axial sorbent flow, allowing for higher gas velocities and intensified mass transfer, reducing equipment size and weight while maintaining high mass transfer rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional packed columns are used for carbon dioxide capture, then mass transfer between flue gas and sorbent can be achieved, but the equipment volume becomes very large (15-20 meters diameter, 20-40 meters height)
Solution Approach 1:
The patent applies dynamic rotation to the packed bed, transforming it from a static to a rotating structure. This rotation creates artificial gravity that enhances mass transfer efficiency between gas and liquid phases, allowing the same capture capacity to be achieved in a much smaller volume. The rotating packed bed (RPB) technology intensifies the contact between flue gas and sorbent through centrifugal forces and improved mixing.
Solution Approach 2:
The patent changes the operating parameters by introducing rotation speed as a new control variable. By varying the rotation speed of the packed bed, the artificial gravity and mass transfer coefficients can be optimized. This parameter change enables high capture efficiency in a compact configuration, resolving the contradiction between capture capacity and equipment volume.
2Volume of stationary object
If rotating packed bed is used to reduce equipment volume, then compact design is achieved, but uniform sorbent distribution and axial gas flow become problematic
Solution Approach 1:
The patent segments the sorbent distribution system by introducing multiple injection points and distribution zones within the rotating packed bed. This segmentation ensures that sorbent is introduced at multiple locations, promoting uniform distribution throughout the packing material despite the rotational motion. The segmented approach prevents localized accumulation and maintains consistent mass transfer zones.
Solution Approach 2:
The patent introduces an intermediary distribution mechanism (such as distribution plates or nozzles) between the sorbent inlet and the mass transfer zone. This intermediary component mediates the sorbent flow, ensuring uniform distribution across the rotating packed bed while maintaining the compact design. The intermediary structure compensates for the challenges of maintaining uniformity in a rotating system.
3Productivity
If higher gas velocities are used in RPB, then mass transfer intensity increases, but equipment design becomes more challenging due to centrifugal effects
Solution Approach 1:
The patent utilizes the dynamic rotation to manage centrifugal effects rather than treating them as unwanted forces. By carefully designing the rotation speed and packing configuration, the centrifugal forces enhance gas-liquid contact and mass transfer intensity. The dynamic design allows higher gas velocities to be accommodated while maintaining effective mass transfer, resolving the contradiction between productivity and design complexity.
Solution Approach 2:
The patent applies local quality optimization by varying the packing material properties, porosity, and structure at different radial positions within the RPB. This local customization allows the system to handle higher gas velocities effectively in different zones, with the inner regions optimized for gas distribution and outer regions optimized for mass transfer. This localized approach manages the complexity while enhancing productivity.
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 cross-flow RPB design achieves significant reductions in equipment size and weight, enabling efficient carbon dioxide capture with higher gas flow velocities and mass transfer rates, making it suitable for compact applications like offshore platforms and retrofitting existing installations.
Implementation Method 1
In an RPB, the mass transfer occurs in a packing that is rotated. Due to the artificial gravity that is introduced by the rotation, the effective contact area between the gas and sorbent is increased without causing early flooding.
Implementation Method 2
A sorbent is used to capture carbon dioxide from flue gas that has been generated by fossil fuel combustion. The sorbent is typically a liquid, such as monoethanolamine, MEA.
Data Source
AI summary
Disclosed herein is a rotating packed bed, RPB, for mass transfer between a sorbent and a gas, the RPB comprising: a central chamber arranged to receive a flow of a sorbent that is a liquid; and a flow path for the sorbent between the central chamber and a region for mass transfer between a gas and the sorbent; wherein, in use, the flow of sorbent through the region for mass transfer is substantially in cross-flow with the flow of gas through the region for mass transfer. Advantageously, mass transfer between a liquid sorbent and a gas is improved.