Single-Rotor RPB Design for Centrifugal Stress Reduction
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Solution Overview
Problem
Conventional rotating packed bed (RPB) units with a two-rotor design experience significant deflections and structural damages due to high centrifugal forces, leading to potential failure during operation, as the annular permeable packing elements are subjected to excessive mechanical stresses beyond the ultimate tensile strength of the rotor material.
Innovation Solution
A single-rotor design with concentric rings of packing elements and metallic plates, where the metallic rings are placed at regular or variable intervals to enhance stiffness and mechanical strength, reducing deflections and fatigue, and utilizing a single shaft for rotation to minimize structural failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a two-rotor design with annular permeable packing elements is used, then mass transfer surface area is increased, but structural strength and reliability deteriorate due to excessive centrifugal forces causing deflections and mechanical stresses beyond ultimate tensile strength
Solution Approach 1:
The rotor is segmented into a modular structure comprising a central hub, multiple radial spokes, and an outer rim, with packing elements distributed across the rim. This segmentation distributes the centrifugal forces across multiple structural components rather than concentrating them, preventing excessive deflections and mechanical stresses while maintaining large mass transfer surface area through the distributed packing elements.
Solution Approach 2:
The rotor employs a composite structure combining a rigid central hub and radial spokes made of high-strength material with the packing elements fixed to the outer rim. This composite design provides the necessary structural strength to withstand centrifugal forces at high rotational speeds while maintaining the large surface area required for effective mass transfer.
2Productivity
If packing elements are subjected to high centrifugal forces to achieve process intensification, then mass transfer rates improve, but mechanical stress increases causing structural damage and potential failure
Solution Approach 1:
The rotor is designed to operate at controlled high rotational speeds that generate the centrifugal forces necessary for process intensification and high mass transfer rates. The dynamic design includes proper balancing and speed control mechanisms that maintain operational reliability by preventing excessive mechanical stresses while achieving the required mass transfer performance.
Solution Approach 2:
The rotor structure incorporates built-in mechanical strength and stiffness through its hub-spoke-rim configuration, providing a cushioning effect against the centrifugal forces generated during high-speed rotation. This preemptive structural reinforcement prevents structural damage and potential failure before they can occur, ensuring operational reliability during process intensification.
3Stability of the object's composition
If a single-rotor design with metallic plates and rings is implemented, then structural robustness and stiffness are enhanced, but device complexity increases due to additional components
Solution Approach 1:
The single rotor is segmented into functional modules: a central hub for shaft connection, radial spokes for structural support, and an outer rim for packing element mounting. This segmentation achieves structural robustness and stiffness through each component's optimized geometry while keeping the overall design manageable through modular construction principles.
Solution Approach 2:
The hub-spoke-rim structure serves multiple functions simultaneously: the hub provides rotational support and force transmission, the spokes provide structural stiffness and distribute centrifugal loads, and the rim provides the mounting surface for packing elements. This multi-functionality reduces device complexity by consolidating structural and functional requirements into a single integrated rotor design.
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 single-rotor design provides a robust and sturdy setup, minimizing deflections among concentric rings and reducing mechanical stresses, thereby ensuring the RPB unit's operational safety and longevity by maintaining a factor of safety of 2.5 against shear and torsion loads and ensuring adequate bearing life and rotor balance.
Implementation Method 1
The rotor rotates at high speed to generate centrifugal forces that drive liquid radially outward and gas radially inward through the packing elements
Implementation Method 2
The metallic rings are placed at regular or variable intervals to enhance stiffness and mechanical strength, reducing deflections and fatigue
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 2(d)~2(e)
AI summary
A rotor for rotating packed bed units (RPBs) is described. The rotor comprises a first plate and a second plate. The rotor further comprises a plurality of sets of rings concentrically interposed between the first plate and the second plate. Each set of rings comprises a plurality of rings are arranged cylindrically. Further, each ring comprises a plurality of packing elements. The rotor further comprises at least one metallic ring interposed between the plurality of sets of rings.