Gas Turbine Combustor Nozzle Segmentation for Stability
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Solution Overview
Problem
Weak pre-mixed combustion systems in gas turbines face instability due to fluctuations in the pressure ratio of fuel to air, leading to unstable heat release and noise, which affects the operation and mechanical lifespan of the combustion system.
Innovation Solution
A combustion apparatus with a fuel flow rate control valve and dual fuel channels in the nozzle allows for precise control of the pressure ratio of fuel mixed with air, minimizing fluctuations in the mixing ratio and reducing unstable heat release by distributing fuel through one or both channels based on pressure ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a weak pre-mixed combustion system is used to achieve low NOx emissions, then emission quality is improved, but combustion stability deteriorates due to operation near the reaction weak limit
Solution Approach 1:
The fuel supply system is segmented into multiple independent fuel channels (first fuel channel, second fuel channel, third fuel channel) with separate control valves. This allows independent adjustment of fuel flow in each channel to maintain stable combustion while operating at weak pre-mixed conditions for low NOx emissions.
Solution Approach 2:
The system dynamically changes the pressure ratio parameter of fuel to air mixing ratio through coordinated control of multiple fuel flow control valves. By adjusting the pressure ratio, the system maintains stable combustion operation even at weak pre-mixed conditions that minimize NOx generation.
2Stability of the object's composition
If the pressure ratio of supplied air/fuel is increased to improve mixing, then mixing efficiency is improved, but combustion stability deteriorates due to swirl generation
Solution Approach 1:
The fuel supply is divided into multiple channels with independent pressure control. This segmentation allows the system to achieve uniform mixing ratio without excessive pressure ratio that would cause swirl, by distributing fuel through multiple controlled pathways.
Solution Approach 2:
The system uses feedback control through multiple fuel flow control valves that respond to pressure ratio changes. When pressure ratio increases cause swirl and instability, the feedback mechanism adjusts fuel flow distribution to maintain stable combustion while preserving mixing efficiency.
3Object-generated harmful factors
If fuel and air are completely pre-mixed to achieve weak combustion, then emission quality is improved, but heat release stability deteriorates
Solution Approach 1:
The pre-mixed fuel supply system is segmented into multiple independently controlled fuel channels. This allows precise control of fuel distribution to maintain stable heat release while achieving complete pre-mixing for low emissions.
Solution Approach 2:
The system dynamically adjusts the pressure ratio parameter across multiple fuel channels to maintain stable heat release characteristics. By coordinating pressure ratio control across channels, the system achieves complete pre-mixing for emission reduction while preventing heat release instability.
Data Source
AI summary
A combustion apparatus can avoid instability in combustion by controlling a pressure ratio of fuel mixed with air. The combustion apparatus includes a casing; a pilot nozzle disposed at the center of the casing and supplied with fuel by a pilot fuel supply pipe; and a plurality of main nozzles arranged around the pilot nozzle and supplied with fuel by a main fuel supply pipe, each main nozzle including a pair of parallel fuel channels each extending to a respective fuel spray position within the main nozzle. A gas turbine adopting the combustion apparatus includes a plurality of combustors, each combustor including the casing, pilot nozzle, and plurality of main nozzles, with each main nozzle having first and second fuel channels respectively extending to a fuel spray position of the corresponding fuel channel. A pilot manifold connects the respective pilot nozzles, and a main manifold connects the respective main nozzles.