Gas Turbine Combustor Staging Control for Partial Load Efficiency
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Solution Overview
Problem
Conventional gas turbines with swirl vanes on the outer peripheral surface of fuel nozzles face challenges in maintaining an optimal fuel-air ratio during partial load operations, leading to increased carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions and decreased combustion efficiency.
Innovation Solution
A combustor design with swirl vanes on the fuel nozzle that includes injection holes, fuel passages, and valves controlled by a control section to adjust fuel injection based on load conditions, ensuring a local high fuel-air ratio near each swirl vane even under partial load, thereby reducing CO and UHC emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fuel is injected from all swirl vanes during partial load operation, then the fuel-air ratio becomes too low, but this causes increased CO and UHC emissions and decreased combustion efficiency
Solution Approach 1:
The fuel injection system is segmented into multiple independently controllable fuel passages, each serving specific swirl vanes. During partial load operation, the control section selectively opens only certain fuel passages (e.g., corresponding to inner swirl vanes) while closing others (e.g., outer swirl vanes), thereby segmenting the fuel distribution to maintain optimal local fuel-air ratios and reduce harmful emissions.
Solution Approach 2:
The fuel injection system employs dynamically adjustable fuel passages with controllable valves that can open or close based on real-time load conditions. The control section dynamically selects which fuel passages to activate, enabling the system to adapt the fuel-air ratio to match varying load requirements and prevent harmful emissions during partial load operation.
2Productivity
If fuel is injected from all swirl vanes during partial load operation, then combustion occurs across the entire burner, but this decreases combustion efficiency due to low fuel concentration
Solution Approach 1:
The fuel injection system provides different fuel supply characteristics to different regions of the burner. By selectively opening fuel passages for specific swirl vanes (e.g., inner swirl vanes) while closing others (e.g., outer swirl vanes), the system creates localized high fuel-concentration zones where combustion is most efficient, rather than distributing low-concentration fuel uniformly across all swirl vanes.
3Object-generated harmful factors
If the fuel-air ratio is maintained in a specific range for lean premixed combustion, then CO and UHC generation is suppressed, but this becomes difficult to maintain under partial load with conventional injection systems
Solution Approach 1:
The system employs dynamically controllable valves in each fuel passage that can open or close based on real-time load conditions. The control section adjusts which fuel passages are active to maintain the fuel-air ratio within the specific range required for lean premixed combustion, adapting seamlessly to varying load conditions from full load to partial load operation.
Solution Approach 2:
The system changes the operational parameters of the fuel injection system by selectively activating different fuel passages based on load conditions. This parameter adjustment allows the fuel-air ratio to be maintained within the optimal specific range across varying operating conditions, suppressing CO and UHC generation while maintaining adaptability.
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 design effectively reduces CO and UHC emissions and enhances combustion efficiency by maintaining a high fuel-air ratio locally near the swirl vanes during partial load operations, ensuring efficient operation of the gas turbine.
Implementation Method 1
swirl vanes which progressively curve from an upstream side toward a downstream side of a flow of air flowing along the axial direction of the fuel nozzle in order to swirl the air around the fuel nozzle
Implementation Method 2
a fuel supplied from a fuel nozzle and compressed air are mixed and burned. A combustion gas produced by combustion
Data Source
AI summary
A combustor 500 is composed of a plurality of premixed combustion burners 100 each comprising a fuel nozzle 110 provided in a burner tube 120, the fuel nozzle 110 having a plurality of swirl vanes 130 on an outer peripheral surface thereof. Injection holes 133a, 133b are formed in each swirl vane 130. Staging control is exercised such that when a gas turbine is in a full load state, a fuel is injected through the injection holes 133a, 133b of all the swirl vanes 130, and when the gas turbine is under a partial load, the fuel is injected only through the injection holes 133a, 133b of a specific number of the swirl vanes 130 adjacent in a circumferential direction, and fuel injection through the injection holes 133a, 133b of the remaining swirl vanes 130 is stopped. By performing such staging control over fuel injection or its stoppage for the swirl vanes 130, a fuel-air ratio can be increased locally, generation of CO and UHC can be suppressed, and high efficiency combustion can be achieved, even under the partial load.