Flamesheet Combustor Contoured Liner Reducing Recirculation
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Solution Overview
Problem
Existing gas turbine combustion systems face challenges in controlling the fuel-air mixture injection due to difficulties in adjusting airflow, leading to varying fuel-air premixture quantities and high emissions, particularly NOx and CO, which are not effectively managed by traditional diffusion nozzles and single-stage combustion designs.
Innovation Solution
A hemispherical dome assembly is integrated into the gas turbine combustor to direct the fuel-air mixture through a series of passageways with controlled radial heights, ensuring a predetermined velocity and minimizing recirculation zones by using a thermal barrier coating and chamfered profiles, thereby regulating the flow and preventing flashback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If diffusion type nozzles are used for fuel-air mixing, then the combustion system is simple in structure, but emissions of NOx and CO are high
Solution Approach 1:
The combustion system is divided into multiple stages with separate fuel and air staging. The fuel injector has multiple injection stages (first stage, second stage, third stage) that inject fuel at different times and locations. Air is staged through multiple paths including premix air and combuster air, allowing controlled mixing and combustion at different zones, which reduces emissions while maintaining system functionality
Solution Approach 2:
A premixing zone is introduced as an intermediary region between fuel injection and combustion. Fuel and air are premixed in this zone before entering the combustion chamber, allowing for more controlled and efficient combustion that reduces harmful emissions. The premixing zone acts as a mediator that enables better fuel-air mixing compared to direct diffusion combustion
2Object-generated harmful factors
If multiple combustion stages are used to reduce emissions, then emissions control is improved, but the complexity of controlling fuel-air premixture increases
Solution Approach 1:
The fuel injection system is made dynamic with multiple injection stages that can be activated at different times. The fuel injector can switch between first stage, second stage, and third stage injection depending on operating conditions. This dynamic control allows flexible adjustment of fuel-air mixing ratios to optimize emissions control while adapting to varying engine loads and conditions
Solution Approach 2:
Different regions of the combustion system are given different functions and properties. The premixing zone is designed with specific geometry to promote mixing, while the combustion chamber is designed for efficient burning. Fuel injectors are positioned at different locations (radial, axial, tangential) to create locally optimized fuel-air mixtures in different zones, allowing emissions control without requiring complex system-wide control mechanisms
3Device complexity
If air flow to combustor is controlled by combustion liner openings, then the combustion system is simple to design, but air flow is not readily adjustable leading to varying fuel-air premixture quantities
Solution Approach 1:
The air flow control system is made adjustable through movable components. The air control valve can be positioned at different angles to vary the amount of air entering the combustion system. This dynamic adjustability allows the fuel-air mixture quantity to be controlled according to operating conditions, replacing the fixed opening design with a controllable mechanism
Solution Approach 2:
The air control valve serves multiple functions: it controls the quantity of air entering the combustor, adjusts the fuel-air mixture ratio, and can adapt to different operating conditions (idle, partial load, full load). This multi-functional component provides both structural simplicity and operational versatility, allowing a single mechanism to handle various air flow requirements
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 enhances control over the fuel-air mixture velocity, reduces emissions by maintaining the mixture attached to the dome assembly, and minimizes recirculation zones, improving combustor stability and reducing the risk of flame anchoring at the inlet end, leading to more efficient combustion and lower pollutant emissions.
Implementation Method 1
a hemispherical dome is positioned proximate an inlet to a combustion liner to direct the fuel-air mixture in a more effective way to better control the velocity of the fuel-air mixture entering the combustion liner while minimizing the adverse aerodynamic effects at a combustion liner inlet region
Implementation Method 2
using a thermal barrier coating
Data Source
AI summary
The present invention discloses a novel apparatus and way for reducing the recirculation zone at the inlet end of a combustor. The recirculation zone is reduced by altering the geometry of the inlet end through a tapering of the liner wall thickness and a tapering of the thermal barrier coating to reduce the bluff body effect at the combustion liner inlet end.