Effusion Cooled Baffle for Gas Turbine Combustor
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Solution Overview
Problem
Gas turbines with sequential combustion face challenges in reducing NOx emissions, particularly when using hydrogen-rich syngas fuels, which produce higher flame speeds and temperatures, leading to increased NOx production and thermoacoustic oscillations.
Innovation Solution
A combustor design with a baffle that splits the flame into two less intense flames by creating a transition region between the mixing and combustion areas, reducing peak temperatures and NOx production, and incorporating cooling to distribute heat evenly, thereby reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen-rich syngas fuels are used to increase flame speed and temperature, then combustion efficiency is improved, but NOx emissions increase
Solution Approach 1:
The combustor is divided into a mixing region and a combustion region separated by a combustion front panel. Fuel is introduced and mixed with combustion gases in the mixing region, then the mixed gases are burned in the combustion region. This spatial segmentation allows controlled mixing before combustion, reducing peak flame temperatures and NOx emissions while maintaining combustion efficiency.
Solution Approach 2:
The combustion front panel acts as an intermediary structure between the mixing region and combustion region. It controls the transition of mixed gases from the mixing region to the combustion region, enabling staged combustion that reduces peak temperatures and NOx formation while maintaining efficient energy release.
2Object-generated harmful factors
If a baffle is introduced to split the flame and reduce peak temperatures, then NOx emissions are reduced, but device complexity increases
Solution Approach 1:
A baffle is introduced in the combustion region to split the flame into multiple zones. This segmentation of the flame structure distributes heat release, reduces peak temperatures, and lowers NOx emissions. The baffle is a relatively simple component that achieves complex thermal management through geometric division.
Solution Approach 2:
The baffle creates local variations in the combustion environment, producing regions with different temperature and heat release characteristics. This local quality differentiation allows certain zones to have reduced peak temperatures for NOx control, while other zones maintain efficient combustion.
3Object-generated harmful factors
If cooling is applied to the baffle to reduce flame temperature, then NOx emissions are reduced, but energy loss increases
Solution Approach 1:
Cooling air is introduced to the baffle, utilizing phase transition and heat absorption principles. The cooling air absorbs thermal energy from the baffle and surrounding combustion gases, reducing peak flame temperatures and NOx emissions. The thermal energy absorbed by the cooling air is subsequently utilized in the combustion process, minimizing net energy loss.
Solution Approach 2:
The cooled baffle acts as a thermal intermediary between the combustion gases and the combustor liner. It absorbs excess heat through the cooling process, reducing peak temperatures and NOx formation, while the cooling air itself becomes part of the combustion system, converting potential energy loss into useful thermal energy for 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
The baffle design significantly reduces NOx emissions and thermoacoustic oscillations by distributing heat and lowering peak flame temperatures, while maintaining turbine inlet temperature and allowing for less stringent fuel-air mixing control.
Implementation Method 1
the baffle is cooled by a cooling fluid or cooling air. The cooling provided to the baffle improves the cooling of the flame contributing to further reduction in NOx
Implementation Method 2
fuel is burnt in a first combustor and the hot combustion gases are passed through a first turbine and subsequently supplied to a secondary combustor into which additional fuel is introduced. The combustion of the hot gases and the fuel is completed in the secondary combustor
Data Source
AI summary
A combustor (1) for a gas turbine engine, particularly for a gas turbine having sequential combustion, includes a combustor wall (4) defining a mixing region (5) and a combustion region (6). The mixing region (5) has at least one first inlet (2) for introducing combustion air into the mixing region (5) and at least one second inlet for introducing fuel into the mixing region (5), the combustion region (6) extending downstream of the mixing region. The mixing region (5) crosses over to the combustion region (6) in a transition region (14). A baffle (9) extends from the transition region (14) generally in the downstream direction (15), forming at least one space (10) between the combustor wall (4) and the baffle (9).