Premix Fuel Nozzle Assembly for Gas Turbine Combustor Flame Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In gas turbine combustors, the introduction of purge air through a gas only cartridge can destabilize the pilot flame in premixed pilot nozzles, impacting the performance and emissions of the combustor, especially when liquid fuel is not available or cost-effective.
Innovation Solution
A dual fuel premix fuel nozzle assembly with a pilot premix nozzle and a gas only cartridge configuration that includes a premix tip with premix tubes and a fuel plenum, where the purge air is directed axially through the nozzle to minimize its impact on the pilot flame, maintaining stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If purge air is directed through the gas only cartridge to cool the cartridge tip, then the cartridge tip temperature is maintained within acceptable levels, but the pilot flame stability deteriorates
Solution Approach 1:
The air passage is segmented into two separate passages: a first air passage that directs purge air axially through the gas only cartridge for cooling, and a second air passage that directs pilot air to the pilot premix nozzle for flame stabilization. This segmentation allows independent control of cooling airflow and pilot airflow, resolving the contradiction between cartridge tip cooling and pilot flame stability.
Solution Approach 2:
The center body acts as an intermediary structure that houses both air passages and directs them to their respective destinations. The center body enables the purge air and pilot air to flow separately through dedicated passages, preventing the harmful mixing of purge air with the pilot flame while still achieving the cooling function.
2Adaptability or versatility
If a gas only cartridge is installed instead of a liquid fuel nozzle, then the combustor operates without liquid fuel capability, but the pilot flame becomes unstable due to purge air interference
Solution Approach 1:
The air passage is segmented into two separate passages: a first air passage that directs purge air axially through the gas only cartridge for cooling, and a second air passage that directs pilot air to the pilot premix nozzle for flame stabilization. This segmentation allows independent control of cooling airflow and pilot airflow, resolving the contradiction between cartridge tip cooling and pilot flame stability.
Solution Approach 2:
Different regions of the nozzle assembly are assigned different functions: the first air passage provides local cooling to the gas only cartridge tip, while the second air passage provides dedicated airflow to the pilot premix nozzle. This local differentiation ensures that purge air does not interfere with the pilot flame while still achieving cooling where needed.
3Temperature
If purge air flows from the gas only cartridge into the pilot flame, then the cartridge is cooled effectively, but the pilot flame stability decreases impacting combustor performance
Solution Approach 1:
The air passage is segmented into two separate passages: a first air passage that directs purge air axially through the gas only cartridge for cooling, and a second air passage that directs pilot air to the pilot premix nozzle for flame stabilization. This segmentation allows independent control of cooling airflow and pilot airflow, resolving the contradiction between cartridge tip cooling and pilot flame stability.
Solution Approach 2:
The harmful effect of purge air mixing with the pilot flame is eliminated by extracting the pilot airflow path from the purge airflow path. The second air passage is specifically designed to deliver pilot air directly to the pilot premix nozzle, separating it from the purge air flow that cools the cartridge, thus removing the destabilizing effect on the pilot flame.
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 configuration enhances the stability of the pilot flame and maintains optimal performance and emissions even when operating without liquid fuel, improving the operational efficiency and reducing the need for costly backup fuel systems.
Implementation Method 1
the gaseous fuel is typically injected into a swirling flow of compressed air flowing through an annular passage defined between the center body and an outer burner tube, thus premixing the gaseous fuel with the compressed air before it is directed into a combustion zone
Implementation Method 2
Purge air is directed through the gas only cartridge to keep the cartridge tip temperatures to within acceptable levels during operation of the combustor
Implementation Method 3
The fuel ports provide for fluid communication between the fuel plenum and the premix passages
Data Source
AI summary
A premix fuel nozzle assembly includes a center body including a sleeve having an inner surface and a pilot premix fuel nozzle assembly that extends axially through the center body within the sleeve and defines a pilot air passage within the center body. The pilot premix fuel nozzle assembly includes a premix tip having a plurality of premix tubes that define premix passages in fluid communication with the pilot air passage. At least one of the premix tubes includes a fuel port. The premix fuel nozzle assembly further includes a pilot fuel flow path that is defined radially between the pilot premix fuel nozzle assembly and the inner surface of the sleeve and a fuel plenum that is at least partially defined between the sleeve inner surface and an outer surface of the premix tip. The fuel ports provide for fluid communication between the fuel plenum and the premix passages.