Sacrificial Temperature Coupons for Turbomachinery Exposure Mapping
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Solution Overview
Problem
Existing temperature measurement systems in combustion turbines, such as hardwired thermocouples, provide low spatial resolution and cannot accurately measure temperatures at locations distant from their installation, leading to inaccurate understanding of component exposure temperatures during failures.
Innovation Solution
A sacrificial coupon system is used to determine actual component temperatures by measuring the thickness of oxide layers formed on coupons attached to turbine components, which are then correlated with historical thermal data to calculate temperature offsets and apply them to sensor readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardwired thermocouples are used to measure temperatures, then temperature measurement capability is provided, but spatial resolution remains low and accurate component temperature measurement is lost
Solution Approach 1:
The patent employs sacrificial coupons made of inexpensive materials that are intentionally designed to be consumed or degraded by oxidation at high temperatures. These coupons serve as temporary temperature indicators that are replaced periodically, eliminating the need for expensive, complex hardwired thermocouples while providing accurate component temperature data through oxide layer analysis.
Solution Approach 2:
The patent replaces the mechanical/electrical thermocouple measurement system with a chemical-based measurement approach. Instead of using electrical contacts to measure temperature, the system uses chemical oxidation reactions on the coupon surface, where the oxide layer thickness and composition serve as a record of temperature exposure, thereby substituting a complex electrical measurement system with a simpler chemical indicator system.
2Measurement precision
If thermocouples are installed close to components, then temperature measurement is possible, but the measurement location is limited and cannot capture temperatures at distant locations
Solution Approach 1:
The patent divides the temperature measurement function into multiple separate sacrificial coupons that can be placed at different locations throughout the combustion turbine. Each coupon independently records the temperature history at its specific location, allowing comprehensive temperature mapping across multiple components without requiring a single complex measurement system. This segmentation enables versatile temperature monitoring at various positions including those difficult to reach with traditional thermocouples.
3Measurement precision
If oxide layer thickness is measured on coupons, then accurate component temperature is determined, but coupon material is consumed by oxidation
Solution Approach 1:
The sacrificial coupons are deliberately designed to be consumed by oxidation during their service life. The coupon material is selected to be inexpensive and readily oxidizable, forming measurable oxide layers that record temperature history. Once the coupon is sufficiently oxidized or reaches its service life, it is replaced with a fresh coupon, accepting the material consumption as an acceptable cost for obtaining accurate temperature data.
Solution Approach 2:
The patent converts the harmful effect of oxidation, which normally causes material degradation and failure, into a beneficial measurement mechanism. The oxidation process that would normally destroy the coupon material is harnessed to create a measurable oxide layer whose thickness and composition provide accurate information about temperature exposure. The harmful chemical reaction becomes the useful sensing mechanism.
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 method provides accurate, high-resolution temperature measurements at component locations, enhancing the accuracy of failure analysis and thermal history monitoring without damaging the components.
Implementation Method 1
determining a thickness of an oxide layer that has formed on a coupon attached to the component
Data Source
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AI summary
A method and a system enables a temperature (408) to which a component (200) within a turbomachine (100) was exposed, to be determined. The method includes operating the turbomachine (100) including the component (200) for an elapsed period of time, determining a thickness (410) of an oxide layer (302) that has formed on a coupon (300) attached to the component (200), and determining a temperature offset based on the thickness measurement (410) of the oxide layer (302). The method also includes determining the temperature (408) to which the component (200) was exposed using the temperature offset, and outputting the temperature (408) to which the component was exposed.