Nested Fuel Nozzle Combustor for Gas Turbine Emission Reduction
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Solution Overview
Problem
Current gas turbines face challenges in efficiently mixing and combusting liquid fuel, leading to incomplete combustion and increased emissions of nitrogen oxides, as existing combustors struggle to effectively divide liquid fuel into small droplets and mix it with compressed air.
Innovation Solution
The combustor design features a nozzle casing with multiple first and second fuel nozzles arranged along an annular line, each with specific fuel and air injection passages that inject fuel at predetermined angles, and includes water supply passages to mix with air, promoting even fuel-air mixing and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid fuel is injected into the combustion chamber using conventional nozzles, then fuel delivery is achieved, but the liquid fuel is not effectively divided into small droplets leading to incomplete mixing and combustion
Solution Approach 1:
The fuel injection system is segmented into multiple injection passages (first and second fuel injection passages) within each nozzle, arranged radially around the central axis. This segmentation allows the fuel to be divided into multiple streams that can be further atomized by air injection, creating smaller and more uniform droplet sizes compared to a single injection passage design.
Solution Approach 2:
Different regions of the nozzle are designed with different injection characteristics. The first fuel injection passage delivers fuel along the central axis while the second fuel injection passage delivers fuel radially outward. The air injection passage is positioned to interact with the fuel at specific locations, creating locally optimized atomization zones that enhance overall droplet uniformity.
2Manufacturing precision
If fuel injection passages are designed to improve atomization, then droplet size is reduced, but the structural complexity of the nozzle increases
Solution Approach 1:
The nozzle adopts a nested structure where the first fuel injection passage is positioned concentrically within the second fuel injection passage, and the air injection passage is positioned to interact with both fuel passages. This nesting allows multiple injection functions to be integrated within a single nozzle body, achieving complex atomization patterns without proportionally increasing external dimensions or manufacturing complexity.
Solution Approach 2:
Each nozzle assembly serves multiple functions: the first fuel injection passage provides central fuel delivery, the second fuel injection passage provides radial fuel delivery, and the air injection passage provides atomization assistance. This multi-functionality is achieved within a compact nozzle structure, avoiding the need for separate components for each function and thereby limiting overall complexity increase.
3Productivity
If multiple fuel nozzles are arranged along an annular line, then fuel-air mixing is improved, but the risk of nozzle clogging increases
Solution Approach 1:
The air injection passage acts as an intermediary between the fuel injection passages and the combustion chamber. By introducing air at the point of fuel delivery, it creates a pre-mix zone that promotes immediate vaporization and dispersion of fuel droplets. This intermediary air flow prevents fuel from stagnating in the injection passages, thereby reducing clogging risk while enhancing mixing efficiency.
4Manufacturing precision
If fuel is injected at high pressure to improve atomization, then droplet size is reduced, but energy consumption increases
Solution Approach 1:
The system utilizes pneumatic assistance through the air injection passage to achieve effective atomization. Instead of relying solely on high-pressure fuel injection, compressed air is introduced to interact with the fuel streams, providing the additional energy needed for droplet formation. This pneumatic approach reduces the required fuel injection pressure while maintaining atomization quality, thereby lowering overall energy consumption.
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 design ensures even mixing of liquid fuel and compressed air, reducing emissions and preventing nozzle clogging, while enhancing combustion efficiency and reducing nitrogen oxide production.
Implementation Method 1
a second fuel injection passage enclosing the first fuel injection passage, and configured to inject liquid fuel into the combustion chamber at a predetermined spray angle with respect to the first center line
Implementation Method 2
a first air injection passage enclosing the second fuel injection passage, and configured to inject air to be mixed with the injected liquid fuel from the second fuel injection passage
Implementation Method 3
a first water supply passage communicating with the first air injection passage and configured to supply water to the first air injection passage, and the water and the air may be mixed with each other in the first air injection passage and injected from the first air injection passage
Data Source
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AI summary
A combustor includes a plurality of fuel nozzles arranged in a nozzle casing. Each fuel nozzle includes a first fuel injection passage disposed at the axial center of the fuel nozzle and configured to inject liquid fuel into a combustion chamber. A second fuel injection passage encloses the first fuel injection passage and injects liquid fuel into the combustion chamber at a predetermined spray angle with respect to a center line of the fuel nozzle. A first air injection passage encloses the second fuel injection passage and injects air to be mixed with the injected liquid fuel from the second fuel injection passage. At the combustion chamber end, opposing surfaces of the first and second fuel injection passages are each inclined with respect to the center line and are separated by a space through which the liquid fuel of the second fuel injection passage is injected.