Sequential Combustor Air Flow Ratio Control
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Solution Overview
Problem
Gas turbine combustor assemblies face challenges in fuel flexibility, particularly with high reactive fuels like hydrogen, which cause NOx emissions and flame instability, limiting operational flexibility and increasing the risk of flashback due to flame position changes.
Innovation Solution
A sequential combustor assembly with an air supply circuit and adjusting device that controls the air flow ratio between the first and second-stage combustors, allowing real-time adjustment to maintain desired temperature and flame position, thereby accommodating a broader range of fuel reactivity and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high reactive fuels like hydrogen are used in the combustor assembly, then the fuel reactivity and energy efficiency are improved, but NOx emissions increase and flame stability deteriorates due to flame position moving upstream
Solution Approach 1:
The combustor assembly is divided into two separate combustors: a first combustor for initial combustion and a second combustor for final combustion. This segmentation allows the first combustor to handle high reactive fuels while the second combustor completes combustion under controlled conditions, reducing NOx emissions and maintaining flame stability.
Solution Approach 2:
A mixer is introduced as an intermediary component between the first and second combustors. The mixer conditions the hot gas stream from the first combustor before it enters the second combustor, controlling the temperature and composition to prevent excessive NOx formation while maintaining stable combustion of high reactive fuels.
2Use of energy by moving object
If high reactive fuels are used, then the energy efficiency is improved, but flame position moves upstream increasing the risk of flashback and burner overheating
Solution Approach 1:
The combustion process is segmented into two stages across separate combustors. The first combustor handles the high reactive fuel combustion while the second combustor provides a controlled environment for completing the combustion, preventing flashback and burner overheating through physical separation and staged combustion.
Solution Approach 2:
The mixer acts as an intermediary that conditions the gas stream between combustors, controlling temperature and flow characteristics to stabilize the flame position and prevent upstream propagation that could cause flashback or burner damage.
3Reliability
If the flame position is controlled by adjusting inlet temperature, then the flame position can be maintained, but the operating window becomes narrow limiting fuel flexibility
Solution Approach 1:
The two-stage combustor design segments the combustion process, allowing each combustor to be optimized for different fuel types and reactivity levels. This enables broader fuel flexibility while maintaining flame position control through the staged combustion approach rather than relying solely on inlet temperature adjustment.
Solution Approach 2:
The system dynamically adapts to different fuel types by adjusting the operation of each combustor stage independently. The mixer dynamically conditions the intermediate stream based on the specific fuel being used, expanding the operating window and fuel flexibility while maintaining reliable flame position control.
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 solution enables reliable control of the second-stage combustor inlet temperature, broadening the fuel reactivity range and reducing emissions by adjusting air flow rates to stabilize the flame position, enhancing operational flexibility and performance.
Implementation Method 1
a first burner (20) fed with at least one first fuel and supplied with air... configured to generate, in use, at least one first flame
Implementation Method 2
a second burner (21) fed with at least one second fuel and being supplied with the mixed hot gas... configured to generate, in use, a second flame
Implementation Method 3
a mixer (11) arranged between the first-stage combustor (8) and the second-stage combustor (9)... the second line (31) is configured to supply air into the mixer (11)
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
A sequential combustor assembly for a gas turbine assembly comprises: • a first-stage combustor (8) comprising at least one first burner (20) fed with at least one first fuel and configured to generate, in use, at least one first flame (22); • a second-stage combustor (9) arranged downstream the first-stage combustor (8) and fed by the hot gas leaving the first-stage combustor (8); the second-stage combustor (9) comprising at least one second burner (21) fed with at least one second fuel and being configured to generate, in use, a second flame (23); • an air supply circuit (25) comprising: - a first line (30) configured to supply air to the at least one first burner (20) of the first-stage combustor (8); - a second line (31) configured to supply air downstream the at least one first flame (22) and upstream the second-stage combustor (9); - an adjusting device (33) configured to adjust a first air flow rate in the first line (30) and a second air flow rate in the second line (31) so as to control the ratio between the first air flow rate and the second air flow rate.