Tunable Transition Duct Side Seals for Gas Turbine Emissions Control
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Solution Overview
Problem
Gas turbine engines face challenges in controlling emissions and combustion dynamics, particularly due to issues like lean blowout and excessive combustion dynamics caused by rapid pressure changes, which existing air control methods, such as dilution holes, often exacerbate carbon monoxide emissions.
Innovation Solution
A tunable side seal system is introduced, comprising a combustion liner, flow sleeve, and end cap with adjustable openings in the seals between transition ducts and the turbine inlet, allowing a controlled portion of airflow to bypass the combustion system, enabling precise regulation of airflow to maintain optimal fuel-air mixtures and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dilution holes are added to control combustion air flow, then combustion dynamics are controlled, but carbon monoxide emissions increase
Solution Approach 1:
A transition duct with adjustable side seals is introduced as an intermediary component between the combustion liner and turbine inlet. This transition duct provides a separate airflow control mechanism that bypasses the combustion zone, allowing combustion dynamics control without introducing additional air through the combustion liner dilution holes, thereby avoiding increased CO emissions.
Solution Approach 2:
The airflow control function is segmented into two independent paths: (1) air flow through the combustion liner for combustion process control, and (2) air flow through the transition duct side seals for combustion dynamics control. This segmentation allows independent optimization of each path to avoid the trade-off between combustion stability and emissions.
2Reliability
If air flow to combustion system is increased to prevent lean blowout, then combustion stability improves, but combustion efficiency decreases
Solution Approach 1:
The transition duct acts as an intermediary airflow path that introduces air downstream of the combustion zone. This allows the combustion process to maintain its optimal fuel-air mixture for high efficiency, while the transition duct provides additional air to stabilize combustion dynamics and prevent lean blowout conditions.
3Ease of manufacture
If fixed seals are used between transition ducts and turbine inlet, then manufacturing is simplified, but combustion tuning flexibility is reduced
Solution Approach 1:
The side seals incorporate adjustable openings that can be modified to change airflow characteristics. This dynamic feature allows the seals to be tuned for different operating conditions and combustion configurations, providing versatility while maintaining a relatively simple sealed construction that is easy to manufacture.
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 tunable side seal system effectively regulates airflow, preventing lean blowout and excessive combustion dynamics, thereby improving combustion efficiency and reducing emissions by allowing for precise adjustment of air bypass, enhancing operational stability and environmental compliance.
Implementation Method 1
A plurality of tunable side seals are positioned between adjacent transition ducts and an inlet of the turbine. The plurality of side seals each have one or more openings located therein that permit a controlled amount of air to pass therethrough and bypass the combustion system.
Data Source
AI summary
A system and method for tuning a gas turbine combustion system having a plurality of seals positioned between the combustion system and the turbine inlet is disclosed. The system and method provide ways of permitting a predetermined amount of compressed air to bypass the combustion system and enter the turbine so as to control emissions and dynamics of the combustion system. The seals contain a plurality of holes to meter airflow passing therethrough and are positioned such that they can be removed from the engine and modified to increase or decrease the amount of air passing therethrough.