Axially Traversable Fuel Nozzle Assemblies for Combustor Dynamics Control
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Solution Overview
Problem
Premixed combustion systems for gas turbines face challenges in managing acoustic instabilities and NOx emissions due to limitations in adjusting flame shape and convective times, which are critical for dynamics control and operability within the narrow operational window of these systems.
Innovation Solution
The combustor design features axially traversing fuel nozzle assemblies with a center body, inner and outer shrouds, and an actuator mechanism that allows for adjustable axial movement of these components, enabling precise control over flame shape and convective times without impacting NOx emissions or operability, and eliminates the need for a combustion cap by shaping nozzles to fill inter-nozzle gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If fuel nozzles are arranged in a common axial plane to change flame shape, then flame shape control is improved, but nozzle-to-nozzle flame front interactions occur reducing stability
Solution Approach 1:
The patent transitions from a two-dimensional common axial plane arrangement to a three-dimensional staggered axial arrangement where nozzles are positioned at different axial locations. This dimensional change allows independent control of flame shape and convective times, eliminating detrimental flame front interactions while maintaining shape control capabilities.
Solution Approach 2:
The patent implements adjustable and traversable nozzle assemblies that can dynamically change their axial positions during operation. This dynamic capability allows the system to optimize flame shape and convective times for different operating conditions, resolving the stability issue by enabling active control rather than fixed geometric arrangements.
2Loss of time
If non-uniform fuel distribution is used in distinct axial locations to change convective times, then convective time control is improved, but flame holding location issues arise reducing operability
Solution Approach 1:
The patent employs adjustable and traversable nozzle assemblies that can dynamically reposition along the axial direction. This allows the system to optimize convective times for different operating conditions without creating fixed flame holding locations, as the nozzle positions can be changed to adapt to varying operational requirements.
Solution Approach 2:
The patent changes the axial position parameter of the fuel nozzles to control convective times. By making this parameter adjustable and traversable, the system can optimize performance across different operating conditions without the detrimental fixed flame holding location effects of non-uniform static distributions.
3Stability of the object's composition
If uniform fuel distribution is maintained in a common plane to avoid flame front interactions, then stability is improved, but NOx emissions increase due to higher local flame temperatures
Solution Approach 1:
The patent moves from a common axial plane arrangement to staggered axial locations, adding the axial dimension as a control variable. This enables non-uniform fuel distribution in the axial direction while maintaining stability through proper staggering, thereby reducing local flame temperatures and NOx emissions without sacrificing stability.
Solution Approach 2:
The patent changes the axial position parameter of fuel nozzles to create controlled non-uniform distributions. This allows optimization of local flame temperatures to reduce NOx emissions while maintaining stability through the staggered arrangement that prevents detrimental flame front interactions.
4Device complexity
If fixed nozzle positions are used to simplify the system, then device complexity is reduced, but the ability to control flame shape and convective times across wide operating conditions is limited
Solution Approach 1:
The patent implements adjustable and traversable nozzle assemblies that can change positions during operation. While this increases device complexity compared to fixed nozzles, it enables wide operational windows by allowing dynamic optimization of flame shape and convective times for different operating conditions, particularly for dynamics mitigation in premixed combustion.
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 mitigates acoustic instabilities and improves turndown capabilities while maintaining low NOx emissions and enhancing reliability by allowing for dynamic adjustments of flame shape and convective times, and eliminates the reliability issues associated with the combustion cap, achieving a more flexible and efficient combustion process.
Implementation Method 1
cooling air is introduced in a space between the inner and outer shrouds and exiting from the plurality of cooling holes... the cooling air in the space between the inner and outer shrouds cools a portion of the inner shroud
Data Source
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AI summary
A combustor (100, 300, 400) includes a central fuel nozzle assembly (304) and a plurality of outer fuel nozzle assemblies (308), each of the plurality of outer fuel nozzle assemblies (308) having a center body (310) and an outer shroud (312), the plurality of outer fuel nozzle assemblies (308) being configured to abut one another in a surrounding relationship to the central cylinder (304) such that no gaps are present between any two abutting ones of the plurality of outer fuel nozzle assemblies (308). One or more of the plurality of fuel nozzle assemblies (104, 304, 308) may traverse axially back and forth according to embodiments of the invention.