Angled Lifting Lug for Rotary Air Preheater Basket
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Solution Overview
Problem
Existing lifting systems for low profile heater baskets in rotary regenerative air preheaters suffer from thread degradation, misalignment, and corrosion issues, leading to costly repairs and inefficiencies in handling and installation.
Innovation Solution
A lifting arrangement featuring angled, triangular-shaped lifting lugs with a cylindrical hook engaging portion and longitudinal notches, designed to conform to the basket's corners, minimizing obstruction and ensuring secure engagement with hook elements and shackles for safe and efficient lifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded eyebolts and flat plate lifting lugs are used, then lifting capability is achieved, but thread degradation, corrosion, and seizure occur over time requiring costly repairs
Solution Approach 1:
The patent extracts the threaded connection component (eyebolt and threaded hole) from the lifting lug assembly, replacing it with a smooth bore hole that receives a pin or rod. This eliminates the threads entirely from the lifting lug structure, removing the source of thread degradation, seizure, and stripping problems while maintaining the lifting function through a simpler pin-based connection system
Solution Approach 2:
Instead of creating threads in the lifting lug (as in conventional designs), the patent inverts the approach by providing a smooth bore hole that accepts an external pin or rod. The lifting force is transferred through this pin rather than through threaded engagement, fundamentally reversing the connection methodology to eliminate thread-related failures
2Force
If lifting lugs are positioned at basket corners, then lifting capability is achieved, but gas flow obstruction increases
Solution Approach 1:
The patent replaces the conventional flat plate lifting lug with a curved, arc-shaped lifting lug that follows the contour of the basket corner. This curved design reduces the protrusion into the gas flow path while maintaining structural strength and lifting capability, thereby minimizing gas flow obstruction compared to flat plate designs
Solution Approach 2:
The lifting lug is designed with non-uniform thickness and curvature, being thicker at the attachment points for strength and thinner at the outer edge to reduce gas flow obstruction. This local variation in geometry optimizes both mechanical performance and fluid flow characteristics
3Force
If flat plate lifting lugs are used, then lifting capability is achieved, but misalignment and improper engagement occur
Solution Approach 1:
The lifting lug features an asymmetric design with a rounded leading edge and a tapered trailing edge. The rounded leading edge facilitates proper alignment and engagement with the lifting hook, while the tapered trailing edge provides a clear engagement surface. This asymmetric geometry ensures reliable hook attachment and prevents misalignment issues encountered with symmetric flat plate designs
Data Source
AI summary
A lifting lug is disclosed for use with a low profile heater basket. The lifting lug can include a corner portion including first and second legs. The first and second legs are coupled to each other at respective first ends. The first and second legs can be oriented at an angle with respect to each other. The angle can be from 82.5-degrees to 97.5-degrees. The lifting lug can further include a hook engaging portion having first and second ends connected to respective second ends of the first and second legs. The hook engaging portion has a cylindrical cross-sectional shape. Further, an outer surface of the hook engaging portion is recessed from a bottom surface of a plane formed by bottom surfaces of the first and second legs. Other embodiments are disclosed and claimed.