Gas Turbine Combustor Ignition via Phase-Matched Cross Fire Tubes
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Solution Overview
Problem
Gas turbine combustors face challenges in achieving low NOx emissions and preventing flashback while maintaining efficient ignition, particularly when increasing fuel/air ratios lead to thermal shock and sudden temperature increases during ignition.
Innovation Solution
A gas turbine combustor design featuring a combustion chamber with fueling nozzles and air injection holes forming coaxial jet flows, supported by phase-matched cross fire tubes and supports, allowing for controlled fuel/air ratios and reduced combustion air supply to manage thermal shock and enhance flame stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel/air ratio is increased to improve ignition reliability and reduce thermal shock, then ignition stability is improved, but NOx emissions increase due to higher flame temperature
Solution Approach 1:
The burner is divided into multiple independent nozzle groups arranged in different phases, allowing selective activation of specific nozzle groups during ignition. This segmentation enables controlled fuel/air ratio management - using higher fuel/air ratio only in specific phases for reliable ignition, while other phases operate at lower ratios to minimize NOx emissions.
Solution Approach 2:
Different nozzle groups are configured with different fuel/air ratios tailored to their specific functions. The ignition-phase nozzles operate at higher fuel/air ratios for reliable flame establishment, while non-ignition-phase nozzles operate at lower ratios for low NOx emissions. This local differentiation of operating conditions resolves the contradiction between ignition reliability and emissions control.
2Stability of the object's composition
If the fuel/air ratio is increased to ensure stable combustion, then combustion stability is improved, but thermal shock and sudden temperature increases occur during ignition
Solution Approach 1:
The system prepares multiple nozzle groups in different phases beforehand, with each group pre-configured for specific operating conditions. During ignition, only the appropriate phase nozzles are activated with elevated fuel/air ratios, avoiding the need to increase fuel/air ratio across the entire system. This preliminary configuration enables stable combustion initiation without system-wide thermal shock.
3Productivity
If cross fire tubes are used to propagate combustion gases between combustors, then ignition efficiency is improved, but phase mismatch between supports and cross fire tubes causes reduced flame propagation
Solution Approach 1:
The support structures are intentionally designed with asymmetric phase positioning relative to the cross fire tubes. By placing supports at specific non-symmetric phases, the system optimizes the flow path of combustion gases from ignited combustors through cross fire tubes to adjacent combustors. This asymmetric configuration ensures proper phase alignment for reliable flame propagation while maintaining the benefits of cross-fire ignition.
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 achieves low NOx emissions and stable combustion by optimizing fuel/air ratios and reducing thermal shock, ensuring reliable ignition and operation of multiple combustors with improved flame propagation and reduced pressure losses.
Implementation Method 1
a plurality of fueling nozzles and a plurality of air injection holes are coaxially arranged and a plurality of coaxial jet flows of fuel and air are supplied to a combustion chamber and burned therein
Implementation Method 2
The combustion chamber is positioned downstream of the premixer to burn the premixed fuel and air
Implementation Method 3
The adjacent combustors are connected to each other via tubes called cross fire tubes, through which combustion gases from the ignited combustors propagate through the cross fire tubes to the adjacent combustors
Data Source
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AI summary
Disclosed is a gas turbine combustor equipped with a burner (6) constructed to fire a plurality of combustors (2) at the same time at a fuel/air ratio suitable for gas turbine ignition. A plurality of supports (15) mounted for fixing an air injection hole plate (38) to the combustor (2) are provided at substantially the same phase position as that of cross fire tubes, and combustion air allocations are adjusted. Thus, flame propagation during gas turbine ignition is accelerated and all combustor cans are fired. In addition, porous plates are disposed downstream of the supports (15) and the combustion air allocations are readjusted. Furthermore, air injection holes (32) proximate to the cross fire tubes are particularly reduced in diameter to further adjust the combustion air allocations.