Fuel Oxygen Reduction Unit for Gas Turbine Wind-Down
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Solution Overview
Problem
Aircraft gas turbine engines face the challenge of fuel coking due to high temperatures during shutdown, which can lead to component damage and reduced efficiency, as the fuel system is not adequately conditioned to withstand residual heat without forming solid particles.
Innovation Solution
A method involving a fuel oxygen reduction unit that reduces the oxygen content of fuel in the nozzles to less than 20 parts per million during the wind-down condition, ensuring the fuel can withstand high temperatures without coking, by operating the unit to deplete oxygen levels in the fuel nozzles before engine shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel is heated during engine operations to increase combustion efficiency, then combustion efficiency is improved, but fuel coking occurs forming solid particles that clog fuel system components
Solution Approach 1:
The fuel oxygen reduction unit is operated during a wind down condition (before engine shutdown) to reduce the oxygen content of fuel in the fuel nozzles to less than 20 parts per million. This preliminary action removes oxygen from the fuel before the engine shuts down and residual heat remains, preventing the fuel from coking when exposed to high temperatures after shutdown.
Solution Approach 2:
By reducing the oxygen content of the fuel to less than 20 parts per million, the fuel is placed in an oxygen-depleted (inert) state. This inert environment prevents oxidation and coking reactions that would otherwise occur when the fuel is heated by residual engine heat during shutdown, allowing the fuel to withstand high temperatures without forming solid particles.
2Stability of the object's composition
If oxygen content of fuel is reduced to prevent coking, then fuel stability is improved, but additional equipment and operational complexity are required
Solution Approach 1:
The fuel oxygen reduction unit is integrated into the existing fuel system and can serve multiple functions: it operates during wind down conditions to prevent coking, and can potentially operate during other engine conditions to maintain fuel quality. This multi-functionality justifies the addition of the device by providing broader benefits beyond just preventing coking during shutdown.
Solution Approach 2:
The invention changes the oxygen content parameter of the fuel from normal levels to less than 20 parts per million during wind down conditions. This parameter change (oxygen reduction) is achieved through the fuel oxygen reduction unit, which uses controlled oxidation or other chemical processes to remove oxygen from the fuel, thereby stabilizing the fuel composition and preventing coking.
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
Prevents fuel coking and subsequent component damage by ensuring the fuel in the nozzles remains below a critical oxygen threshold, even after engine shutdown, thus maintaining engine integrity and performance.
Implementation Method 1
operating a fuel oxygen reduction unit to reduce an oxygen content of the flow of fuel provided to the fuel nozzle
Data Source
AI summary
In one exemplary embodiment of the present disclosure, a method of operating a fuel system for an aeronautical gas turbine engine is provided. The method includes: providing a flow of fuel to a fuel nozzle of the aeronautical gas turbine engine during a wind down condition; operating a fuel oxygen reduction unit to reduce an oxygen content of the flow of fuel provided to the fuel nozzle of the aeronautical gas turbine engine during the wind down condition; and ceasing providing the flow of fuel to the fuel nozzle of the aeronautical gas turbine engine, the fuel nozzle comprising a volume of fuel after ceasing providing the flow of fuel to the fuel nozzle; wherein operating the fuel oxygen reduction unit comprises operating the fuel oxygen reduction unit to reduce an oxygen content of the volume of fuel in the fuel nozzle to less than 20 parts per million.