Axially Staged Combustion System for Turbomachine Fuel Flexibility
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Solution Overview
Problem
Turbomachines lack fuel flexibility, often using expensive or excessively volatile fuels, which can lead to inefficient operations and increased pollutant emissions.
Innovation Solution
An axially staged combustion system with a transition piece that allows for flexible fuel injection modes, including axially staged injection and late lean injection, enabling the use of high and low heating value fuels, reducing emissions and improving combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional single-stage combustion is used, then the combustor structure is simple, but fuel flexibility is limited and fuel costs are high
Solution Approach 1:
The combustion system is divided into multiple axially staged combustion zones within the combustor and transition piece. Primary fuel is burned in the combustor while secondary fuel is burned in the transition piece, allowing different fuel types to be combusted in different zones. This segmentation enables fuel flexibility without requiring multiple separate combustors.
Solution Approach 2:
The patent introduces axial staging along the flow direction, adding a spatial dimension to fuel injection and combustion. By arranging fuel injectors at different axial positions (combustor and transition piece), the system can handle multiple fuel types simultaneously or alternatively, resolving the contradiction between simplicity and fuel flexibility.
2Use of energy by moving object
If high heating value fuel is used, then energy density is high, but flameholding capability may be insufficient in certain zones
Solution Approach 1:
Different fuel types are injected at different axial locations based on local flow conditions and flameholding requirements. The primary fuel injector in the combustor and secondary fuel injector in the transition piece can be optimized for different fuel properties, allowing high heating value fuel to be used where energy density is prioritized while maintaining flameholding capability where needed.
3Productivity
If fuel injection is performed early in the combustor, then combustion efficiency is high, but thermal acoustics instability may occur
Solution Approach 1:
The combustion process is segmented into primary combustion in the combustor and secondary combustion in the transition piece. This spatial segmentation allows optimization of combustion efficiency in the combustor while using the transition piece as a diffusion flame zone that is less prone to thermal acoustics instability, thus resolving the contradiction between combustion efficiency and stability.
4Object-affected harmful factors
If late lean injection is used, then thermal acoustics stability is improved, but combustion efficiency may be reduced
Solution Approach 1:
By adding the axial dimension for staged injection, the system can implement late lean injection in the transition piece while maintaining overall combustion efficiency through the combined effect of primary and secondary combustion zones. The spatial separation allows each zone to be optimized for its specific function.
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 system provides increased fuel flexibility, wider operational temperature windows, and enhanced flameholding capabilities, reducing fuel costs and pollutant emissions while maintaining power generation efficiency.
Implementation Method 1
The combustor includes a liner formed to define an interior in which fuel and air are combustible to produce a working fluid
Data Source
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Figure 5
AI summary
A turbomachine (10) including a combustor (20) in which fuel is combustible to produce a working fluid, a turbine section (30), which is receptive of the working fluid for power generation operations, a transition piece (40) in which additional fuel is combustible, the transition piece being disposed to transport the working fluid from the combustor to the turbine section and a staged combustion system (50) coupled to the combustor and the transition piece. The staged combustion system is configured to blend components of the fuel and the additional fuel in multiple modes.