Corrosion Sensor with Segmented Probes for Turbine Monitoring

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Solution Overview

Problem

High-efficiency gas turbine components face rapid corrosion due to metallic impurities in fuels, which are difficult to remove and form corrosive oxides that degrade alloys and thermal barrier coatings, leading to significant maintenance challenges and inefficiencies.

Innovation Solution

A corrosion sensor system with probes of varying cross-sectional areas, encased in ceramic sheaths, measures resistance changes to quantify corrosion rates in real-time, allowing for continuous monitoring and adjustment of inhibitor dosages without shutdowns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal barrier coatings are used to protect nickel-based and cobalt-based alloys, then corrosion resistance is improved, but molten oxides can still attack and degrade the thermal barrier coatings

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmolten oxide attack
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a metallic plug as an intermediary component between the thermal barrier coating and the corrosive environment. This plug serves as a sacrificial barrier that reacts with molten oxides before they can reach and degrade the thermal barrier coating, thereby protecting the coating while allowing the system to maintain its corrosion resistance function

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If inhibitors are used to neutralize corrosive oxides, then corrosion is reduced, but significant amounts of inhibitors are needed and corrosion still occurs

Engineering Contradiction:
Improvecorrosion protectionVSAvoidinhibitor dosage
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent implements a feedback mechanism by measuring the electrical resistance of probes embedded in the thermal barrier coating. Changes in resistance provide real-time feedback about the coating's integrity and corrosion state, allowing for dynamic adjustment of inhibitor dosage to maintain optimal protection while minimizing chemical usage

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple probes with different cross-sectional areas are used, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvecorrosion measurement accuracyVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the sensing element into multiple discrete probes, each with a specific cross-sectional area. This segmentation allows each probe to respond differently to corrosion effects, providing multiple data points that improve measurement accuracy while keeping each individual probe structurally simple

Inventive Principle:
Principle #1Segmentation

4Productivity

If continuous corrosion monitoring is implemented, then operational efficiency is improved, but maintenance requirements increase

Engineering Contradiction:
Improveoperational efficiencyVSAvoidmaintenance complexity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The corrosion sensor system is designed to be self-diagnosing, automatically measuring its own electrical resistance and providing direct feedback about its operational status and the coating's integrity. This self-service capability eliminates the need for complex external monitoring systems and reduces maintenance complexity while enabling continuous operational efficiency monitoring

Inventive Principle:
Principle #25Self-service

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 system provides direct, real-time corrosion data, enabling effective inhibitor dosage adjustments and extending turbine component lifespan by detecting corrosion early and accurately, thus improving operational efficiency and reducing maintenance costs.

Implementation Method 1

The ceramic sheath electrically isolates each first end and each second end of the probes from the metallic plug and the other first ends and second ends

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

measuring a plurality of ohmic resistances across a plurality of probes of a corrosion sensor during operation of a turbine

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentEP3246693B1Corrosion sensor, corrosion monitoring system, and method of quantifying corrosion
Publication Date: 2021.12.15 GENERAL ELECTRIC CO
  • EP3246693B1 patent drawingFigure 1~2
  • EP3246693B1 patent drawingFigure 3
  • EP3246693B1 patent drawingFigure 4

AI summary

A corrosion monitoring system (110) includes at least one corrosion sensor (100). The corrosion sensor (100) includes a metallic plug (104) having at least one opening, at least one ceramic sheath (106) in the opening of the metallic plug (104), and a plurality of probes (102). Each probe (102) has a central portion with a predetermined cross sectional area extending from the metallic plug (104). The ceramic sheath (106) electrically isolates each first end and each second end of the probes (102) from the metallic plug (104) and the other first ends and second ends. The probes (102) are sized to provide a range of predetermined cross sectional areas of the central portions. Such arrangement permits to extend the lifespan of the system since when one probe has been completely corroded, measurement can be switched to another probe having a higher cross sectional area and which is still operational.The corrosion monitoring system (110) also includes a resistance meter (112) measuring an ohmic resistance for at least one of the probes (102) and a computer (116) determining a corrosion rate by correlating a rate of change of the ohmic resistance to the corrosion rate of the probe (102). The corrosion monitoring system (100) is particularly suitable for real-time corrosion monitoring of components in the hot gas path of turbines.