Alternating Offset U-Bend Support for Steam Generator Tube Stability
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Solution Overview
Problem
Nuclear steam generators face challenges in supporting U-bend tube sections under high heat and varying conditions, leading to gaps between coolant tubes and support bars due to dilation and contraction, which can cause tube instability and vibration.
Innovation Solution
A support system using a combination of thicker and thinner flat bars to laterally support U-tubes, imparting a serpentine path and maintaining contact through alternating offsets, thereby accommodating size and shape changes of the tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional uniform support bars are used to support U-bend tubes, then the support structure is simple and easy to manufacture, but gaps form between tubes and support bars due to thermal dilation and contraction, causing tube instability and vibration
Solution Approach 1:
The patent applies asymmetry by using flat bars of alternating thicknesses (thicker and thinner bars) instead of uniform thickness bars. This asymmetric arrangement creates varying offsets that accommodate the thermal dilation and contraction of U-bend tubes, maintaining continuous contact between tubes and support bars while preventing gaps and instability.
Solution Approach 2:
The patent implements local quality by varying the thickness of flat bars at different locations along the support structure. Thicker bars provide greater support where needed, while thinner bars accommodate different thermal expansion requirements, allowing each local region to be optimized for its specific thermal and mechanical conditions.
2Reliability
If thicker flat bars are used to reduce gaps between tubes and support bars, then tube support stability improves, but the support structure becomes more complex and harder to manufacture
Solution Approach 1:
The patent segments the support structure into multiple flat bars with different thicknesses arranged in an alternating pattern. This segmentation allows each bar to be manufactured to standard thickness specifications, simplifying production while the varied segmentation pattern collectively provides the necessary accommodation for thermal expansion and maintains tube stability.
3Adaptability or versatility
If the support structure accommodates thermal expansion and contraction, then tube stability is maintained, but the structure becomes more complex with alternating thickness bars
Solution Approach 1:
The patent changes the physical parameter of flat bar thickness to create alternating thicker and thinner bars. This parameter variation enables the support structure to adapt to thermal expansion and contraction of U-bend tubes by providing varying offsets, maintaining tube contact and stability while accommodating size and shape changes during operation.
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 solution effectively prevents tube bending or folding, maintains tube stability under intense conditions, and reduces gaps between tubes and support bars, ensuring reliable heat transfer and vibration damping.
Implementation Method 1
The improved support system is particularly useful for accommodating the dilation and contraction of coolant tubes and other elements caused by the extreme and varying conditions inside a steam generator
Data Source
AI summary
Arrangement for supporting U-bend tube sections in the high heat environment of steam generators using flat bars. The invention uses a combination of thicker and thinner flat bars to impart a serpentine path to the arc of the normally curvilinear U-tubes. The support system accommodates the dilation and contraction of coolant tubes and other elements caused by the extreme and varying conditions inside a steam generator, and which can cause gaps between coolant tubes and prior art tube support bars. Bars of alternating thickness provide alternating offsets to tensionally push and support each tube on multiple sides and in multiple locations, and this tension keeps the tubes in contact with at least some flat bars on multiple sides regardless of size and shape changes. Support arrangement includes a set of fan bars, each fan bar including thick and thin flat bars projecting up and out from a collector bar.