Gas Turbine Combustor Injector Layout for Low-Load NOx Control
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Solution Overview
Problem
Existing gas turbines face challenges in expanding their low load operating range and minimizing the generation of NOx emissions, particularly due to inadequate mixing of fuel and air in the combustion process.
Innovation Solution
A combustor design featuring a liner with a transition piece and a fluid-flowing sleeve, incorporating an injector with an injection pipe and air supply unit that guides air inwardly to enhance mixing, and a fuel supply unit to inject fuel centrally, optimizing the combustion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the low load operating range is expanded, then the adaptability of the gas turbine is improved, but the combustion efficiency deteriorates due to inadequate fuel-air mixing
Solution Approach 1:
The injector is divided into multiple air supply units arranged circumferentially, each independently supplying air to specific regions. This segmentation allows optimized air-fuel mixing at different zones, improving combustion efficiency across various load conditions while expanding the operable range.
Solution Approach 2:
The air supply units are arranged in the circumferential direction around the injection pipe, creating a three-dimensional mixing pattern. This circumferential arrangement enhances fuel-air mixing by introducing air from multiple directions simultaneously, resolving the contradiction between expanded operating range and maintained combustion efficiency.
2Productivity
If the fuel and air mixing is improved, then the combustion vibration is reduced and power generation efficiency is improved, but the device complexity increases due to additional air supply units
Solution Approach 1:
The air supply units are integrated into the injector structure that is already mounted on the combustion chamber wall. The air supply channels are formed within the injector body itself, merging the air supply function with the existing injector structure rather than adding separate components, thus reducing overall device complexity.
Solution Approach 2:
The injector structure serves multiple functions: it supplies fuel through the central pipe, supplies air through the circumferential units, and provides structural mounting on the combustion chamber wall. This multi-functionality reduces the need for separate components, improving power generation efficiency without proportionally increasing device complexity.
3Reliability
If the fuel supply amount is increased, then the combustion efficiency is improved, but the NOx emissions increase due to excessive fuel-air ratio
Solution Approach 1:
Different air supply units are positioned at specific circumferential locations to create localized mixing zones. This allows precise control of the fuel-air ratio in different regions of the combustion chamber, enabling efficient combustion while controlling peak temperatures and reducing NOx emissions through optimized local air-fuel distribution.
Solution Approach 2:
Air is supplied through the air supply units before or simultaneously with fuel injection, pre-positioning the air in the combustion zone. This preliminary air supply ensures proper mixing occurs before combustion, allowing efficient burning at lower peak temperatures that reduce NOx formation while maintaining combustion efficiency.
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 design expands the low load operating range of the gas turbine and minimizes NOx emissions by improving fuel-air mixing, leading to more efficient combustion and reduced emissions.
Implementation Method 1
an outlet area is formed at a front end of the air supply unit, which is configured to guide a direction of the air to be directed toward a center of the injection pipe
Implementation Method 2
When supplying the fuel mixed with the compressed air to the combustion chamber, it is important to increase a degree of mixing of air and fuel
Implementation Method 3
a combustor configured to generate combustion gas by combusting compressed air supplied from the compressor and the fuel
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A combustor (10) including a liner (11) provided with a combustion chamber at an inner side of which a mixture of fuel and compressed air is combusted, a transition piece (12) connected to an end of the liner, a fluid-flowing sleeve (13) disposed at an outer side of the liner and the transition piece, and at least one injector (200) configured to inject the mixture of fuel and air by being disposed on the liner or the transition piece, wherein the injector includes an injection pipe (210) connected to the liner or the transition piece, a fuel supply unit (220) configured to supply the fuel from a center part of a rear end of the injection pipe (210), and an air supply unit (230) configured to supply the air from an inner circumferential part of the rear end of the injection pipe (230).