Impingement Cooling Sleeve Combustor Liner
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Solution Overview
Problem
Gas turbine can combustors face challenges with air flow mal-distribution, which affects the fuel-air ratio and NOx levels, making it difficult to achieve low NOx emissions while maintaining high efficiency and low pressure loss.
Innovation Solution
The design incorporates a cylindrical housing with a coaxially disposed impingement cooling sleeve that directs combustion air against the combustor liner, providing uniform air flow and improved mixing, combined with film cooling to optimize flow conditions and reduce NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If impingement cooling is used to cool the combustor liner, then cooling efficiency is improved, but air flow mal-distribution occurs affecting fuel-air ratio uniformity
Solution Approach 1:
The patent applies different cooling strategies to different regions of the combustor liner. Impingement cooling is used in the reaction zone where high heat flux requires aggressive cooling, while film cooling is used in other zones. This localized differentiation allows optimal cooling efficiency in each region while minimizing negative effects on flow distribution and fuel-air mixing.
Solution Approach 2:
The cooling system is segmented into multiple independent cooling air passages, each supplying cooling air to specific zones of the combustor liner. This segmentation allows independent control and optimization of cooling air flow in each zone, preventing mal-distribution that would affect overall fuel-air ratio uniformity while maintaining effective cooling where needed.
2Temperature
If cooling air flow is increased to improve cooling efficiency, then liner cooling is improved, but pressure loss increases
Solution Approach 1:
The patent uses partial cooling air extraction from the combustion air stream rather than requiring separate excessive cooling air supplies. By taking a portion of the combustion air for cooling purposes through dedicated passages, the system achieves effective liner cooling without the additional pressure loss that would result from separate cooling air systems or excessive cooling air extraction.
3Temperature
If film cooling is used to cool the combustor liner, then cooling is provided, but carbon monoxide emissions increase
Solution Approach 1:
The patent selectively applies impingement cooling in the reaction zone where complete combustion occurs, rather than using film cooling which would introduce cool air into the combustion zone and create incomplete combustion products. This localized application of appropriate cooling methods reduces carbon monoxide emissions while maintaining necessary liner cooling.
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 configuration achieves more uniform fuel-air mixing, stable combustion, reduced NOx emissions, and minimized temperature deviations, while maximizing cooling efficiency and reducing liner wall temperatures.
Implementation Method 1
an impingement cooling sleeve coaxially disposed between the housing and the combustion liner and extending axially from the closed housing end for a substantial length of the combustion zone. The impingement cooling sleeve has a plurality of apertures sized and distributed to direct combustion air against the radially outer surface of the portion of the combustor liner defining the combustion zone, for impingement cooling.
Implementation Method 2
Air for combustion flows along passage 26 directly to swirl vanes 28 where it is mixed with fuel and admitted to combustion zone 16, to undergo combustion.
Implementation Method 3
A recirculation zone or pattern 32 is established by the swirling air/fuel mixture and the can component geometry, to stabilize combustion.
Implementation Method 4
The type of configuration shown in Fig. 1 may be used in a simple low NOx combustor where impingement cooling is preferred to that of film cooling.
Data Source
Figure 1~2
AI summary
A can combustor includes a generally cylindrical housing having an interior, an axis, and a closed axial end. The closed axial end includes means for introducing fuel to the housing interior. A generally cylindrical combustor liner is disposed coaxially within the housing and configured to define with the housing respective radially outer passages for combustion air and for dilution air, and also respective radially inner volumes for a combustion zone and a dilution zone. The combustion zone is disposed axially adjacent the closed housing end, and the dilution zone is disposed axially distant the closed housing end. The can combustor also includes an impingement cooling sleeve coaxially disposed between the housing and the combustor liner and extending axially from the closed housing end for a substantial length of the combustion zone. The sleeve has a plurality of apertures sized and distributed to direct combustion air against the radially outer surface of the portion of the combustor liner defining the combustion zone, for impingement cooling. Essentially all of the combustion air flows through the impingement cooling apertures prior to admission to the combustion zone. A small portion of the impingement cooling air may be used for film cooling of the liner proximate the closed housing end.