Pilot Injector Recirculation Zone for Gas Turbine CO Reduction
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Solution Overview
Problem
Gas turbine combustors face challenges in reducing carbon monoxide emissions, especially at lower power settings where inefficient fuel mixing and quenching of combustion products lead to non-compliance with emission regulations, and existing solutions like catalysts and lower flame temperature combustors are costly or limit operational revenue.
Innovation Solution
The apparatus includes a radial swirler, fuel injectors, and a recirculation area created by an annular extension within the pilot injector of a gas turbine combustor, which anchors the pilot flame and increases residence time for complete combustion reactions, preventing CO quenching and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the powerplant operates at lower power settings to save fuel costs, then fuel consumption is reduced, but carbon monoxide emissions increase and compliance with emission regulations becomes difficult
Solution Approach 1:
The combustor is divided into distinct functional zones: a first region with a pilot flame for stable combustion at low loads, and a second region for main combustion. This segmentation allows each zone to operate optimally under different load conditions, enabling compliant CO emissions even at lower power settings where fuel savings are achieved.
Solution Approach 2:
A recirculation zone is introduced as an intermediary region between the pilot flame and the main combustion area. This recirculation zone traps hot combustion gases and redirects them to enhance mixing and complete combustion of CO before exhaust, acting as a mediator that enables low-load operation without excessive emissions.
2Object-generated harmful factors
If catalysts are used to transform carbon monoxide into water and carbon dioxide, then emission compliance is achieved, but the cost of the powerplant increases
Solution Approach 1:
The combustor design enables self-service combustion completion through its internal recirculation zone, which naturally promotes complete combustion of CO without requiring external catalysts or additional emission control systems. The hot recirculated gases themselves provide the necessary conditions for CO oxidation, eliminating the need for costly catalytic converters.
3Object-generated harmful factors
If lower flame temperature combustors are used to reduce emissions, then carbon monoxide emissions are reduced, but the cost of the powerplant increases
Solution Approach 1:
Different regions of the combustor are designed with different qualities: the pilot region maintains high temperature for stable ignition, while the recirculation zone provides controlled mixing and the second region completes combustion. This local differentiation achieves emission compliance without requiring a complete redesign of the entire combustor at higher cost.
4Object-generated harmful factors
If the powerplant operates at full-load condition, then emission levels are lowest and compliance is easiest, but the amount of revenue generated is maximized only when operating at demanded power settings
Solution Approach 1:
The combustor is designed with dynamic capabilities to adapt to varying load conditions. The pilot flame and recirculation zone work together to maintain stable, compliant combustion across the entire operating envelope, allowing the powerplant to dynamically adjust output to match demand while consistently meeting emission regulations.
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 effectively reduces carbon monoxide emissions by ensuring complete combustion reactions occur before the flame interacts with cooler air, maintaining compliance with emission regulations across varying power settings without the need for costly catalysts or reduced operational time.
Implementation Method 1
It is in this recirculation area, of lower pressure, that the pilot flame will anchor and burn
Implementation Method 2
the pilot flame is anchored further upstream so as to establish a greater residence time in which the pilot flame is to burn and complete the reactions to minimize CO formation
Implementation Method 3
The preferred embodiment of the pilot injector comprises a radial swirler, at least one fuel injector, a passageway formed between first and second spaced walls, a means for establishing a recirculation area adjacent to the pilot injector
Data Source
AI summary
The present invention discloses an apparatus and method for reducing the carbon monoxide emissions emitted by a pilot injector of a gas turbine combustor. Multiple embodiments of a means for establishing a recirculation zone are disclosed whereby a portion of the fuel and air mixture from the pilot injector recirculates and a flame is held, thereby increasing the local reaction temperature at the desired location and lowering carbon monoxide emissions.