Flameless Burner Recirculation Zone for Lean Combustion Stability
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Solution Overview
Problem
Conventional methods for achieving stable combustion in gas turbine engines under very lean conditions face instability issues, leading to potential lean flame blowout and acoustic wave problems, which are difficult to mitigate without recirculation ducts or heat exchangers.
Innovation Solution
A flameless burner design that includes a primary swirl generating chamber with an air swirler to create a recirculation zone, combined with fuel injection mechanisms that inject fuel into the recirculated combustion product gases, promoting a swirling flow and distributed combustion reaction without the need for recirculation ducts or heat exchangers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional lean combustion methods are used, then fuel efficiency is improved, but flame stability deteriorates leading to lean blowout and acoustic instabilities
Solution Approach 1:
The combustion process is segmented into distinct zones: a recirculation zone containing hot combustion products, a mixing zone where fuel and oxidizer combine, and a reaction zone. This segmentation allows the hot recirculating gases to provide distributed heating throughout the combustion chamber, stabilizing the flame without requiring a concentrated flame front, thereby preventing lean blowout while maintaining fuel efficiency.
Solution Approach 2:
Hot combustion products act as an intermediary medium that transfers thermal energy from the reaction zone to the fuel-oxidizer mixture in the recirculation zone. This intermediary heat transfer mechanism stabilizes the combustion process by preheating the reactants and maintaining ignition temperatures throughout the chamber, eliminating acoustic instabilities while preserving lean combustion efficiency.
2Reliability
If recirculation ducts and heat exchangers are added to achieve flameless combustion, then flame stability is improved, but device complexity and structural weight increase
Solution Approach 1:
The recirculation function and combustion chamber function are merged into a single integrated structure. The combustion chamber itself serves as the recirculation zone, eliminating the need for separate recirculation ducts and external heat exchangers. This integration maintains flame stability through hot gas recirculation while significantly reducing device complexity and structural weight.
Solution Approach 2:
The combustion chamber performs multiple functions simultaneously: it serves as the reaction zone, the recirculation chamber, and the heat exchange medium. This multi-functionality eliminates the need for dedicated recirculation ducts and external heat exchangers, achieving flameless combustion stability without increasing device complexity or adding structural components.
3Reliability
If recirculation ducts and heat exchangers are added to achieve flameless combustion, then flame stability is improved, but manufacturing cost and maintenance requirements increase
Solution Approach 1:
The recirculation function and combustion chamber function are merged into a single integrated structure. The combustion chamber itself serves as the recirculation zone, eliminating the need for separate recirculation ducts and external heat exchangers. This integration maintains flame stability through hot gas recirculation while significantly reducing device complexity and structural weight.
Solution Approach 2:
The combustion chamber performs multiple functions simultaneously: it serves as the reaction zone, the recirculation chamber, and the heat exchange medium. This multi-functionality eliminates the need for dedicated recirculation ducts and external heat exchangers, achieving flameless combustion stability without increasing device complexity or adding structural components.
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 burner achieves stable, low-emission combustion at very lean fuel-to-air ratios, reducing NOX and CO emissions below 10 ppm, and maintains flame stability without the need for heavy recirculation ducts or heat exchangers, enhancing operational efficiency and reducing structural stress.
Implementation Method 1
receive compressor discharge air through the air swirler thereby forming a recirculation zone that entrains downstream combustion product gases toward the burner body
Implementation Method 2
forming a recirculation zone that entrains downstream combustion product gases toward the burner body
Implementation Method 3
high temperature oxidizer reacts with fuel at very high levels of turbulence in a distributed reaction zone
Implementation Method 4
high temperature oxidizer reacts with fuel at very high levels of turbulence in a distributed reaction zone
Data Source
AI summary
A flameless burner for a gas turbine engine includes a burner body having a longitudinal axis, an upstream section and a downstream section. The upstream section of the burner body defines a primary swirl generating chamber having air swirlers associated therewith. The primary swirl generating chamber is adapted and configured to receive compressor discharge air through the air swirlers. The strong swirl of the compressor discharge air forms a recirculation zone that entrains combustion product gases toward the burner body. Fuel injectors are operatively connected to the downstream section of the burner body for issuing fuel into the recirculated combustion product gases.