Stepped HRSG Tube Restraints for Uniform Exhaust Flow

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Solution Overview

Problem

Heat recovery steam generators (HRSG) face challenges in evenly distributing exhaust gases due to their larger size compared to gas turbines, leading to increased pressure losses and reduced effectiveness, which is exacerbated by uneven flow distribution and design constraints such as tube strength, maintenance costs, and durability.

Innovation Solution

The implementation of stepped, angled, or scalloped tube restraints that are vertically aligned and angled between 10 to 60 degrees to guide exhaust gases more evenly across the HRSG, enhancing heat transfer and reducing pressure losses by distributing flow more uniformly throughout the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If HRSG is made substantially larger to increase heat transfer surface area, then heat transfer effectiveness is improved, but exhaust gas flow distribution becomes uneven and pressure losses increase

Engineering Contradiction:

Improveheat transfer effectivenessVSAvoidpressure losses

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The HRSG is divided into multiple vertical zones with tube restraints at different heights, creating segmented flow paths that distribute exhaust gases more evenly across the heat transfer surface area, reducing localized pressure losses while maintaining overall heat transfer effectiveness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tube restraints are positioned at different vertical heights and angled orientations, adding vertical and angular dimensions to the flow distribution mechanism, which enables more uniform exhaust gas distribution across the large HRSG volume without increasing horizontal flow resistance

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If tube restraints are added to improve flow distribution, then exhaust gas distribution is improved, but device complexity and material costs increase

Engineering Contradiction:

Improveflow distribution efficiencyVSAvoidstructure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Tube restraints are strategically positioned only at specific vertical zones where flow distribution problems occur, rather than uniformly throughout the entire HRSG, reducing overall structural complexity while achieving improved flow distribution where most needed

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Tube restraints are designed with angled and curved geometries that naturally guide exhaust gas flow patterns, using geometric design rather than complex mechanical components to achieve flow distribution, thereby reducing device complexity

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Productivity

If tube restraints are angled to guide exhaust flow upward, then flow distribution to upper portions is improved, but tube strength and structural stability may be compromised

Engineering Contradiction:

Improveflow distribution uniformityVSAvoidtube strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The restraint system is segmented into multiple discrete tube support points at different heights, distributing mechanical loads across multiple locations rather than concentrating stress, thereby maintaining tube strength while enabling angled flow guidance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tube restraints are positioned asymmetrically at specific angles optimized for flow guidance, rather than symmetric horizontal positioning, allowing upward flow direction while structural analysis ensures tube strength requirements are met through strategic placement

Inventive Principle:

Principle #4Asymmetry

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

This solution improves the overall effectiveness of HRSG by increasing the utilization of upper portions, reducing pressure losses, and maintaining robustness while minimizing additional material and labor costs compared to conventional designs.

Implementation Method 1

The stepped tube restraints are designed to guide exhaust gases, redirecting flow upward and distributing it more uniformly across the heat recovery steam generator

Methodology Applied

Scientific EffectFlow guidance:

Implementation Method 2

Heat recovery steam generators use exhaust gases from gas turbine engines to produce steam at various pressures, temperatures, and flow rates

Methodology Applied

Scientific EffectHeat transfer: Convection

Data Source

PatentUS10907821B2HRSG with stepped tube restraints

Publication Date: 2021.02.02 GE INFRASTRUCTURE TECH LLC

AI summary

A heat recovery steam generator (HRSG) includes: a plurality of vertically-aligned HRSG tubes; and a plurality of stepped tube restraints coupled to the plurality of vertically aligned HRSG tubes. Each stepped tube restraint includes a plurality of tube restraints. The plurality of tube restraints are arranged in an array such that each successive tube restrain is vertically higher than and axially aft of an adjacent tube restraint.