In Situ Acid Cleaning of Turbine Hot Gas Flowpath Components
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Solution Overview
Problem
Turbine engines experience performance degradation due to environmental contaminant fouling, particularly CaO—MgO—Al2O3-SiO2 (CMAS) and other deposits, which accumulate on hot gas flowpath components, leading to increased temperatures, thermal alteration, and reduced durability of thermal barrier coatings, resulting in unplanned engine removals and decreased efficiency.
Innovation Solution
An acid-including detergent, such as citric acid-based solutions, is introduced into the hot gas flowpath to dissolve and remove accumulated contaminants like CMAS partial melt from turbine engine components, including those with thermal barrier coatings, restoring compliance and aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If turbine engines operate in environments with environmental contaminants, then they can fly through certain routes and perform their function, but contaminant fouling accumulates on hot gas flowpath components leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by introducing and applying the acid-including detergent to the hot gas flowpath components before the contaminant fouling becomes severe enough to cause engine failure. This preventive maintenance approach allows the engine to continue operating through contaminated environments while periodically restoring performance by dissolving accumulated contaminants, thus maintaining both route flexibility and reliability.
2Strength
If thermal barrier coatings are used on hot gas flowpath components, then component durability at high temperatures is enhanced, but contaminant accumulation infiltrates the TBC coating leading to spallation
Solution Approach 1:
The patent converts the harmful effect of contaminant accumulation into a beneficial cleaning process. The acid-including detergent specifically targets and dissolves the contaminant layers (including CMAS) that have infiltrated the TBC coating, transforming the problematic contaminant-TBC interaction into a removable substance that can be eliminated without damaging the underlying TBC structure or substrate.
Solution Approach 2:
The patent changes the chemical parameters of the contaminant layer by introducing an acid-including detergent that alters the chemical composition and solubility characteristics of the accumulated contaminants. This allows the contaminants to transition from an adherent, infiltrated state to a dissolved state that can be easily removed, thereby preventing TBC spallation and restoring component durability.
3Quantity of substance
If cooling circuits are blocked by contaminant accumulation, then fouling material forms layers in cooling passages, but this decreases cooling efficiency and increases component temperatures
Solution Approach 1:
The patent applies the extraction principle by removing the contaminant fouling material from the cooling passages and hot gas flowpath components. The acid-including detergent penetrates the cooling circuits and dissolves the accumulated contaminants, extracting them from the system and restoring unobstructed coolant flow, thereby decreasing component temperatures back to design levels.
4Ease of operation
If water wash treatments are used to clean turbine components, then they are simple to apply, but they are not successful in removing typical accumulated contaminants and reaction products
Solution Approach 1:
The patent changes the chemical parameters of the cleaning agent from neutral water to an acid-including detergent solution. This parameter change enables the cleaning solution to chemically react with and dissolve the alkaline and amphoteric contaminant substances (such as CMAS and sulfate deposits) that water alone cannot remove, while maintaining the simplicity of application through existing water delivery systems.
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 method effectively removes CMAS and other contaminants, preventing TBC spallation, restoring cooling efficiency, extending engine life, reducing operating temperatures, and enhancing engine power and stall margin.
Implementation Method 1
An acid-including detergent, such as citric acid-based solutions, is introduced into the hot gas flowpath to dissolve and remove accumulated contaminants like CMAS partial melt from turbine engine components
Data Source
AI summary
The present disclosure provides methods and systems for in situ cleaning of hot gas flowpath components of a turbine engine that form portions of a hot gas flowpath extending through the turbine. The hot gas flowpath components may include a layer of accumulated contaminants on first portions thereof that form a respective portion of the hot gas flowpath. The first portions may include a thermal battier coating (TBC), and the layer of accumulated contaminants may overlie the TBC and at least partially infiltrate into the TBC. The accumulated contaminants may include CaO—MgO—Al2O3-SiO2 (CMAS) partial melt. The methods may include introducing an acid-including detergent into the hot gas flowpath of the turbine engine and onto the hot gas flowpath components to clean the accumulated contaminants from the first surfaces of the components.