Dynamic Flange Design for Thermal Shock Resistance

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Solution Overview

Problem

Existing expansion joints for gas turbine systems face challenges with high operating temperatures up to 1250°F and rapid start-up times, leading to increased thermal gradients, mechanical stresses, and fatigue, particularly due to the limitations of materials like Armco #409 stainless steel and the welded designs used in current flanges.

Innovation Solution

A two-step rolled stainless steel dynamic flange with a cylindrical inner sleeve and optional expansion slots, where the flange is welded perpendicular to the sleeve, reducing the number of critical welds and incorporating a skip welding technique to minimize stress and fatigue, while maintaining flexibility and thermal resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional welded flange designs are used, then structural strength is provided, but stress and fatigue increase due to thermal gradients and rapid start-up conditions

Engineering Contradiction:

Improvestructural strengthVSAvoidstress and fatigue resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The flange is divided into multiple segments that can move independently relative to each other, allowing the structure to accommodate thermal expansion and contraction without generating excessive stress. The segmented design includes expansion joints and flexible connections that enable each segment to respond independently to thermal gradients, thereby reducing overall stress and fatigue in the system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flange design incorporates dynamic elements such as flexible connections and expansion joints that allow the structure to adapt and move in response to changing thermal conditions. This dynamic capability enables the flange to absorb thermal stresses during rapid start-up and shutdown cycles, preventing stress concentration and fatigue failure while maintaining structural integrity.

Inventive Principle:

Principle #15Dynamics

2Strength

If more welds are used to ensure secure connection, then joint strength improves, but weld-related stress and fatigue increase

Engineering Contradiction:

Improvejoint strengthVSAvoidweld fatigue resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention extracts or eliminates unnecessary welds from the flange assembly by using mechanical connections, friction-grip joints, or expansion joint designs that achieve secure connections without relying on extensive welding. This reduction in weld quantity directly decreases the sources of stress concentration and fatigue initiation, while alternative connection methods maintain or improve joint strength.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The design introduces intermediary elements such as expansion joints, flexible connectors, or damping components between flange sections. These intermediaries absorb thermal stresses and prevent stress transmission to welded joints, allowing fewer welds to be used while maintaining secure connections and reducing weld-related fatigue.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If the flange is made rigid to maintain structural integrity, then strength is improved, but flexibility to accommodate thermal expansion is reduced

Engineering Contradiction:

Improvestructural integrityVSAvoidthermal expansion accommodation

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention employs flexible components such as expansion joints, bellows, or flexible connectors within the flange assembly. These flexible elements can deform and expand or contract in response to thermal changes, accommodating thermal expansion while maintaining the overall structural integrity of the rigid flange sections through controlled flexibility.

Inventive Principle:

Principle #30Flexible shells and thin films

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 withstands temperatures above 1250°F and rapid start-up conditions, reducing stress and fatigue, and extending the cycle life of the expansion joint by minimizing weld-related issues and maintaining a secure seal for hot gas transfer.

Implementation Method 1

control thermal expansion and contraction of such duct

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

withstand thermal shock due to the quick rise in temperature

Methodology Applied

Scientific EffectThermal shock: Thermal Shock

Implementation Method 3

the flange is welded and perpendicular to the outer surface of the inner sleeve

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS10605401B2Expansion joint containing dynamic flange

Publication Date: 2020.03.31 FRENZELIT WERKE GMBH & CO KG

AI summary

An expansion joint that includes a rolled two-step shaped stainless steel dynamic flange welded atop a cylindrical inner sleeve, such that the inner sleeve connects on one end to gas exhaust, such that the expansion joint withstands thermal shock due to quick rise in temperatures.