Pilot Lance Premixing in Gas Turbine Burners for Low-NOx H2 Fuel
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Solution Overview
Problem
Existing gas turbine assemblies face challenges in using highly reactive fuels like hydrogen (H2) due to increased NOx emissions and flashback risks, while existing solutions to divert fuel to pilot lances result in high NOx emissions and system complexity.
Innovation Solution
A premix burner with a pilot lance that includes a mixing volume within the pilot lance, where H2-based fuel mixes with air before reaching the pilot nozzles, reducing NOx emissions by premixing highly reactive fuels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If highly reactive fuel (H2) is fed to premix nozzles, then fuel flexibility is improved, but NOx emissions increase and flashback risk increases
Solution Approach 1:
The fuel delivery system is segmented into two separate pathways: a first fuel source connected to premix nozzles for common fuels, and a second fuel source connected to inner nozzles within the pilot lance for highly reactive fuels. This segmentation allows selective operation based on fuel type, preventing H2 flashback and NOx emissions while maintaining fuel flexibility.
Solution Approach 2:
The pilot lance acts as an intermediary component that receives highly reactive fuel through inner nozzles and mixes it with air from the swirler before injection into the combustion chamber. This intermediary mixing process reduces the reactivity of H2 fuel, preventing flashback and reducing NOx emissions while maintaining the ability to use highly reactive fuels.
2Reliability
If highly reactive fuel (H2) is fed to pilot lance, then flame stability is improved, but NOx emissions increase
Solution Approach 1:
Air is introduced into the pilot lance through the swirler before the highly reactive fuel reaches the pilot nozzles. This preliminary mixing of air and fuel reduces the reactivity of H2, allowing stable flame formation without excessive NOx emissions. The preliminary action of air injection prevents the harmful effects of direct H2 combustion.
3Object-generated harmful factors
If common fuel is fed to premix nozzles, then low NOx emission is achieved, but fuel flexibility is limited
Solution Approach 1:
The burner system is designed with multi-functionality to handle different fuel types: common fuels (natural gas, propane) are delivered through premix nozzles for low NOx operation, while highly reactive fuels (H2, ethane, propane) are delivered through the pilot lance inner nozzles. This universal design allows the same burner to operate efficiently with various fuel compositions, expanding fuel flexibility while maintaining low emissions capability.
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 premixing of H2-based fuel with air in the pilot lance volume minimizes NOx emissions and stabilizes the flame, addressing flashback issues without increasing emissions or system complexity.
Implementation Method 1
a swirler configured for swirling an air flow and provided with premix nozzles connected to a first gas fuel source
Implementation Method 2
at least an inner duct extending inside the corresponding main duct, wherein each inner duct has a first end connected to a second or pilot gas fuel source and a second end provided with an inner nozzle arranged upstream the pilot nozzles of the corresponding main duct so that between the inner nozzle and the corresponding pilot nozzle a mixing volume is present
Implementation Method 3
a combustor for adding fuel the compressed air and generating a hot gas flow
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Premix burner (34) of a gas turbine assembly, the premix burner comprising: a swirler (35)configured for swirling an air flow and provided with premix nozzles (36) connected to a first gas fuel source; a pilot lance (38) comprising: a cylindrical casing (39) having a base connected to the first gas fuel source and a tip (40) provided with a plurality of gas nozzles (41); at least a main duct (42) configured for being a channel for pilot fuel or compressed air and extending inside the casing from the base to the tip, each main duct having a tip end provided with at least a pilot nozzle (45); the premix burner moreover comprises at least an inner duct (44) extending inside the corresponding main duct, each inner duct having a first end connected to a second gas fuel source and a second end provided with an inner nozzle arranged upstream the pilot nozzles of the corresponding main duct so that between the inner nozzle and the corresponding pilot nozzle a mixing volume (46) is present for mixing H2-based gas fuel source fed into the inner duct and compressed air fed into the main duct.