Premix Burner Fuel Staging for Gas Turbine Stability
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Solution Overview
Problem
Premix burners for gas turbines face challenges in maintaining combustion stability and reducing pollutant emissions across varying operating conditions, particularly due to thermo-acoustic oscillations and flashback issues, which limit their operational range and efficiency.
Innovation Solution
The burner design incorporates a swirl generator and a downstream mixer tube with additional fuel feeds in the transition section, allowing for flexible fuel staging and introduction of gaseous and liquid fuels through a fuel lance, enabling precise control of fuel distribution and intermixing to stabilize combustion and reduce oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a premix burner uses a swirl generator and mixer tube design, then combustion stability is improved, but thermo-acoustic oscillations occur limiting operational range
Solution Approach 1:
The burner is divided into multiple functional sections: a swirl generator section with tangential air inlet slots creating swirled flow, and a downstream mixer tube section for fuel-air mixing. This segmentation allows each section to be optimized independently - the swirl generator provides flow stabilization while the mixer tube enables flexible fuel staging, thus maintaining combustion stability across varying operational conditions without triggering thermo-acoustic oscillations
Solution Approach 2:
The burner incorporates multiple controllable fuel feeds (central nozzle, wall feeds, transition section feeds) that can be dynamically adjusted based on operating conditions. This dynamic fuel staging capability allows the burner to adapt to different load ranges and fuel types, expanding the operational range while maintaining stable combustion through optimized fuel distribution patterns
2Adaptability or versatility
If additional fuel feeds are added in the transition section, then fuel staging flexibility is improved, but device complexity increases
Solution Approach 1:
The transition section is designed with multi-functional feed openings that can accommodate different fuel injection strategies. These openings serve multiple purposes: they can introduce additional fuel feeds for staging, maintain structural integrity of the transition section, and facilitate smooth flow transition between the swirl generator and mixer tube. This multi-functionality provides fuel staging flexibility without proportionally increasing structural complexity
3Productivity
If fuel is injected through multiple feeds, then combustion efficiency across varying conditions is improved, but manufacturing precision requirements increase
Solution Approach 1:
Different feed openings are positioned at specific locations along the transition section and mixer tube, with each opening optimized for its local function. The central nozzle is positioned at the burner head center, wall feeds are distributed circumferentially, and transition section feeds are located where flow conditions favor mixing. This localized optimization allows each feed to contribute efficiently to combustion while tolerating normal manufacturing variations in positioning
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 enhances combustion stability and flexibility, reducing pollutant emissions and thermo-acoustic oscillations, allowing for efficient operation across a wide range of conditions by optimizing fuel staging and intermixing within the burner.
Implementation Method 1
a double-cone burner, which creates a closed swirled flow in the cone head, which flow, on account of the increasing swirl along the cone point
Implementation Method 2
changes into an annular swirled flow with backflow in the core
Implementation Method 3
The flow from the swirl generator in this case is transferred smoothly into the mixer tube. This takes place as a result of a transition geometry which comprises transfer passages
Implementation Method 4
In the mixer tube itself, the axial velocity profile has a distinct maximum on the axis and consequently prevents flashbacks in this region
Data Source
AI summary
A premix burner is provided, with a swirl generator and a downstream mixer tube for combusting gaseous and liquid fuel which during entry of combustion air is introduced into the burner interior space of the swirl generator and/or is introduced into the burner interior of the swirl generator on a burner axis, and also with a fuel lance which is arranged on the burner axis. The premix burner, in the transition section from the swirl generator to the mixer tube, includes at least one additional feed for introducing gaseous and/or liquid premix fuel from the wall region into the burner interior space of the mixer tube.