Late Lean Injection Combustor Premixing Conduit
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Solution Overview
Problem
Gas turbine engines produce significant pollutants like NOx and CO during combustion, and existing late lean injection (LLI) methods do not effectively reduce NOx emissions while increasing energy consumption.
Innovation Solution
A LLI combustor assembly with a flow sleeve annulus and elongate premixing conduit for premixing compressor discharge air with a second fuel before injection into a second interior, enhancing energy consumption without significant NOx increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LLI involves injection of combustible materials into high energy fluids downstream from the normal combustion zone, then CO consumption increases and energy of high energy fluids increases, but NOx emissions may increase
Solution Approach 1:
The patent applies preliminary action by premixing the second fuel with compressor discharge air in an elongate premixing conduit before injection. This pre-mixing process ensures proper fuel-air ratio is established upstream, allowing the fuel to be more effectively consumed in the downstream region without creating conditions that promote NOx formation. The premixing occurs in a controlled manner before the fuel enters the high-energy fluid stream.
Solution Approach 2:
The patent uses compressor discharge air as an intermediary medium. Instead of injecting pure fuel directly into the hot high-energy fluids, the fuel is first mixed with cooler compressor discharge air in the premixing conduit. This intermediary mixing step moderates the temperature and composition of the injected mixture, enabling CO consumption while limiting conditions that lead to NOx formation.
2Power
If combustor produces high energy fluids for power generation, then mechanical energy for power and electricity generation is derived, but pollutants such as NOx and CO are produced
Solution Approach 1:
The patent changes key parameters of the combustion process by introducing a second fuel injection system with premixing. The fuel composition, temperature, and mixing ratio are altered by combining second fuel with compressor discharge air before injection. These parameter changes enable the system to maintain power generation while modifying the combustion characteristics to reduce pollutant formation.
Solution Approach 2:
The patent segments the combustion process into distinct zones: a normal combustion zone for primary power generation and a downstream injection zone for additional fuel combustion. By dividing the combustion process and treating different regions separately with different fuel injection strategies, the system can optimize power generation in one zone while controlling emissions in another.
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 solution effectively increases CO consumption with minimal NOx increase, improving energy efficiency and reducing pollutant emissions in gas turbine engines.
Implementation Method 1
the at least one elongate premixing conduit may be in fluid communication with a compressor discharge air and the second fuel such that the compressor discharge air and the second fuel are premixed within the elongate premixing conduit
Implementation Method 2
mixtures of fuel and gas are combusted within a combustor disposed upstream from a transition piece and a turbine. The combustor produces high energy fluids
Implementation Method 3
the combustible materials injected at this location increase the temperature and energy of the high energy fluids
Data Source
AI summary
A late lean injection combustor assembly may include a first interior in which a first fuel supplied thereto is combustible, a flow sleeve annulus including a second interior in which a second fuel supplied thereto is combustible, at least one fuel injector disposed about the second interior, and at least one elongate premixing conduit disposed about the flow sleeve annulus and in fluid communication with the at least one fuel injector. The at least one elongate premixing conduit may be in fluid communication with a compressor discharge air and the second fuel such that the compressor discharge air and the second fuel are premixed within the elongate premixing conduit before entering the second interior by way of the at least one fuel injector.