Gas Turbine Combustor Nozzle Fuel Concentration Control
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Solution Overview
Problem
In gas turbines with premixed combustion type combustors, the mixing of cooling air with premixed gas before the flame front leads to non-uniform fuel concentration, resulting in locally high flame temperatures and increased NOx production.
Innovation Solution
The combustor design includes first nozzles with fuel concentration gradients along their axial direction, ensuring a uniform fuel concentration at the flame front by varying the fuel discharge quantities and areas of fuel discharge holes, which are connected to independent fuel supply paths, allowing for precise control of fuel concentration distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is supplied to cool the combustor basket and transition piece, then the combustor components are cooled down, but the fuel concentration of the premixed gas becomes non-uniform and locally high temperature sections are created
Solution Approach 1:
The patent applies preliminary action by adjusting the fuel concentration distribution in the premixed gas before it reaches the flame front. The fuel concentration is made higher in regions where cooling air is mixed in, so that even after cooling air dilution, the fuel concentration remains uniform at the flame front. This pre-compensation ensures uniform combustion temperature and prevents NOx generation while allowing effective cooling of combustor components.
Solution Approach 2:
The patent applies local quality by creating non-uniform fuel concentration distribution in the premixed gas at different radial positions. Specifically, the fuel concentration is made higher in the central region and lower in the outer region where cooling air mixes in. This localized adjustment of fuel concentration compensates for the non-uniform mixing of cooling air, ensuring uniform flame temperature across the combustion chamber.
2Manufacturing precision
If uniform fuel concentration is maintained in the premixed gas outlet, then the fuel concentration distribution is uniform, but non-uniform fuel concentration at the flame front occurs due to cooling air mixing
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the fuel concentration distribution before the premixed gas reaches the flame front. The fuel concentration is deliberately made non-uniform in the outlet of the premixed gas (higher in central region, lower in outer region) to compensate for the expected dilution by cooling air. This ensures that after cooling air mixing, the fuel concentration becomes uniform at the flame front, preventing local high temperature sections and NOx generation.
3Stability of the object's composition
If the fuel concentration is increased in the central region of the premixed gas, then the flame temperature uniformity is improved, but the fuel concentration distribution becomes non-uniform
Solution Approach 1:
The patent applies local quality by creating deliberately non-uniform fuel concentration distribution in the premixed gas outlet, with higher fuel concentration in the central region and lower in the outer region. This non-uniform distribution is designed to compensate for the non-uniform mixing of cooling air, ensuring that after cooling air dilution, the fuel concentration becomes uniform at the flame front, achieving stable and uniform flame temperature.
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 maintains a uniform flame temperature along the axial direction, reducing NOx generation by ensuring consistent fuel concentration across the flame front, even when cooling air is mixed in.
Implementation Method 1
a combustor that includes a combustor basket to which compressed air is supplied from a compressor, a plurality of main nozzles annularly disposed along the inner periphery of the combustor basket, and a pilot nozzle that is disposed on the center axis of the combustor basket and that holds a pilot flame. This type of combustor performs premixed combustion by supplying premixed gas of fuel and compressed air to the inside of the combustor basket by the main nozzles and igniting the premixed gas using the pilot flame.
Implementation Method 2
a transition piece in which the combustor basket is connected to a base end thereof and which burns the premixed gas supplied from the first nozzles, thereby forming a flame front
Data Source
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AI summary
This combustor is provided with: inner cylinders (12) through wich air (A) is fed from outside; a plurality of first nozzles (14) that is annularly disposed along the inner periphery of the inner cylinders (12), and feed a premixed gas (M) of air (A) and fuel (f) to the inside of the inner cylinders (12); and tail pipes (15) having proximal ends (15b) to which the inner cylinders (12) are connected, said tail pipes (15) forming a flame front (F) that broadens to the outer peripheral side toward the distal side in the axial direction hough the combustion 4 premixed gas (M) that has to fed from the first nozzles (14). Each first nozzle (14) changes the fuel concentration around the central axis of said first nozzle (14) and supplies the premixed gas (M) in such a manner that the flame front (F) attains a uniform temperature in the axial direction.