Gas Turbine Combustor U-Shaped Cooling Passage
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Solution Overview
Problem
Industrial gas turbine combustors face challenges in reducing nitrogen oxide (NOx) emissions and improving cooling performance to manage increasing combustion gas temperatures, which are exacerbated by the need to balance cooling air and combustion air ratios.
Innovation Solution
A gas turbine combustor design featuring a cylindrical combustion chamber with an annular passage system that allows combustion air to flow through an outer casing and a U-shaped passage within the combustion chamber wall, enabling efficient convection and film cooling, reducing the amount of cooling air while increasing combustion air, thereby enhancing cooling performance and reducing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of cooling air is increased to improve cooling performance, then the cooling performance is improved, but the amount of combustion air decreases
Solution Approach 1:
The cooling air flow path is segmented into multiple sections: an inlet section, a first passage extending in the axial direction, a second passage for return flow, and jet holes. This segmentation allows the cooling air to be delivered efficiently to the combustion chamber wall while maintaining sufficient combustion air supply.
Solution Approach 2:
The cooling air flow direction is inverted by configuring the second passage to extend in the opposite axial direction, causing the cooling air to flow back toward the upstream side before being jetted through the jet holes. This reverse flow configuration improves cooling efficiency by creating a more effective cooling pattern along the combustion chamber wall.
2Productivity
If the combustion gas temperature is increased to improve efficiency, then the efficiency is improved, but the amount of NOx emissions increases
Solution Approach 1:
Cooling air is supplied in advance through the passages to pre-cool the combustion chamber wall before the combustion gas arrives. This preliminary cooling action allows higher combustion gas temperatures to be maintained without excessive wall temperatures, enabling higher efficiency operation while controlling NOx emissions through adequate cooling air management.
3Temperature
If the amount of cooling air is increased to reduce wall temperature, then the cooling performance is improved, but the mixture ratio increases making it difficult to reduce NOx emissions
Solution Approach 1:
Cooling air is delivered locally to specific regions of the combustion chamber wall through strategically positioned jet holes and passages. This localized cooling approach ensures that cooling is applied only where needed on the wall surface, improving cooling efficiency while minimizing the total amount of cooling air required, thereby preserving more air for combustion and maintaining lower NOx emissions.
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 design improves cooling performance and reduces NOx emissions by optimizing the flow of cooling air, allowing for increased combustion air and lower NOx production, resulting in a more reliable gas turbine combustor.
Implementation Method 1
a path through which cooling air is passed is formed in the combustion chamber wall and the method uses both convection cooling achieved by the cooling air passing through the path and film cooling achieved by air that comes out of the path
Implementation Method 2
film cooling achieved by air that comes out of the path
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
There is provided a gas turbine combustor (3) capable of improving cooling performance of a combustion chamber (5) thereof and reducing the amount of NOx emissions. The gas turbine combustor (3) includes: a cylindrical combustion chamber that burns combustion air (14) and fuel to thereby produce combustion gas; an outer casing disposed concentrically on an outside of the combustion chamber (5); an end cover disposed at an upstream side end portion of the outer casing; an annular passage formed by an outer peripheral surface of the combustion chamber (5)and an inner peripheral surface of the outer casing (7), the annular passage allowing the combustion air to flow therethrough; and a passage formed inside a combustion chamber wall between the outer peripheral surface and an inner peripheral surface of the combustion chamber (5), the passage having a U-shape turned sideways and having ends disposed on an upstream side in a transverse cross-sectional view, in which the passage includes a first passage that extends in parallel with an axial direction of the combustion chamber (5) and has a supply hole (104) on a first end side thereof, the supply hole communicating with an outside of the combustion chamber wall, and a second passage that has a second end side communicating with a second end side of the first passage and has a jet hole (107) on a first end side thereof, the jet hole communicating with an inside of the combustion chamber wall.