Staged Fuel Injectors with Screening Plates for Gas Turbine Combustion
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Solution Overview
Problem
Conventional combustion systems in gas turbines face efficiency limitations due to high NOx emissions at increased firing temperatures, and staged injectors poorly condition air flow, leading to uneven fuel/air mixtures and increased engine degradation.
Innovation Solution
A staged injector design with a steep angle of injection and a cover forming a surrounding plenum, featuring lateral vanes and a screening plate with apertures, to improve air flow conditioning and mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If firing temperatures are increased to improve engine efficiency, then engine efficiency is improved, but NOx emissions increase
Solution Approach 1:
The combustor is divided into multiple zones with staged injectors positioned at different axial locations. The forward injector and downstream staged injectors create separate combustion regions, allowing different portions of the combustion process to occur at different temperatures and stages, thereby reducing peak NOx formation while maintaining overall efficiency
Solution Approach 2:
Air is pre-mixed with fuel in the staged injectors before the combustion zone, creating a controlled mixture that burns more completely and at lower peak temperatures. This preliminary mixing action reduces NOx formation by avoiding high-temperature direct combustion of pure fuel
2Stability of the object's composition
If staged injectors are used to increase air volume and improve mixing, then fuel/air mixing is improved, but aerodynamic pressure losses increase
Solution Approach 1:
The injector design incorporates local flow conditioning features including curved surfaces, flow directing vanes, and strategically positioned air inlets that create localized high-energy flow regions. These local modifications ensure proper mixing and flow attachment without requiring excessive overall air volume that would cause system-wide pressure losses
Solution Approach 2:
The staged injectors utilize three-dimensional flow patterns with axial, radial, and tangential flow components. The downstream injectors are positioned at angles that create conical flow patterns, adding dimensional complexity to the mixing process and improving fuel/air homogeneity without proportionally increasing pressure losses
3Device complexity
If conventional staged injector designs are used, then device complexity is reduced, but flow conditioning performance deteriorates
Solution Approach 1:
Multiple flow conditioning functions are merged into integrated components: the injector housing incorporates flow directing vanes, air inlets, and mixing chambers as unified structures. This integration achieves proper flow conditioning while avoiding the complexity of separate conditioning devices
Solution Approach 2:
The injector design employs curved surfaces and rounded flow paths instead of sharp corners and flat surfaces. The conical arrangement of downstream injectors and curved flow directing surfaces create smooth flow transitions that improve air flow characteristics and mixing while maintaining relatively simple geometric forms
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
Enhances fuel/air mixing, reduces NOx emissions, and increases firing temperatures while maintaining efficient engine performance and minimizing aerodynamic pressure losses.
Implementation Method 1
A screening plate may be formed within the side wall of the cover that includes a multitude of apertures configured to condition the flow of air entering the device
Implementation Method 2
Another issue related to staged injectors relates to how poorly conventional designs perform in regard to premixing fuel and air before delivery to the combustion zone
Implementation Method 3
the combustor may include an inner radial wall that defines a combustion zone downstream of a forward nozzle and, downstream of that, the staged injector
Data Source
AI summary
A staged injector in a combustor of a gas turbine. The staged injector may include an injector tube comprising a lateral wall enclosing an injection passageway that extends between an outlet and inlet. An outboard segment of the injector tube may include an exterior face. A cover may be formed about the outboard segment so form a surrounding plenum. The cover may include a side wall that radially overlaps the outboard segment and forms a first portion of the surrounding plenum therebetween. A ceiling wall of the cover may form a second portion of the surrounding plenum. A screening plate may be formed within the side wall of the cover that includes a multitude of apertures configured to fluidly connect the first portion of the surrounding plenum with a feed cavity formed exterior to the side wall.