Gas Turbine Fuel Routing System for Load Rejection Stability
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Solution Overview
Problem
Gas turbine engines experience significant generator speed overshoot when an electrical load is suddenly removed, leading to potential equipment damage and costly restart cycles, as existing solutions provide insufficient margin to over-frequency limits and are inadequate for modern, lighter, and less expensive generators.
Innovation Solution
A fuel routing system with a primary fuel circuit, a secondary fuel circuit, and a main fuel flow control valve that restricts fuel flow upon load removal, routing fuel to a subset of fuel nozzles through a secondary fuel circuit, along with check valves to prevent backflow, allowing for controlled fuel reduction and maintaining combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fuel flow is quickly reduced to minimum level upon load removal, then generator speed overshoot is reduced, but combustion stability is compromised and shutdown margin is insufficient
Solution Approach 1:
The fuel nozzles are segmented into two distinct groups: a first group that receives reduced fuel flow and a second group that receives increased fuel flow. This segmentation allows different portions of the combustor to operate under different fuel flow conditions, enabling overall fuel reduction while maintaining combustion stability in critical areas.
Solution Approach 2:
Different fuel flow rates are applied to different locations within the combustor. The first group of fuel nozzles receives reduced fuel flow to decrease overall fuel consumption and generator speed overshoot, while the second group of fuel nozzles receives increased fuel flow to maintain combustion stability and prevent flameout in critical combustion zones.
2Speed
If fuel flow is reduced to minimum level, then generator speed overshoot is reduced, but restart capability is lost requiring costly shutdown cycles
Solution Approach 1:
The fuel delivery system is segmented into multiple controllable groups of fuel nozzles, allowing selective fuel flow management. This enables the system to reduce overall fuel flow to mitigate speed overshoot while maintaining sufficient fuel supply in the second group of nozzles to sustain combustion and enable rapid restart without full shutdown cycles.
3Reliability
If fuel is routed to all fuel nozzles, then combustion stability is maintained, but generator speed overshoot increases
Solution Approach 1:
The system applies different fuel flow qualities to different spatial locations within the combustor. The first group of fuel nozzles receives reduced fuel flow quality to limit overall fuel input and reduce generator speed overshoot, while the second group of fuel nozzles receives increased or maintained fuel flow quality to preserve combustion stability in critical combustion zones.
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 reduces generator speed overshoot and prevents unnecessary shutdowns by staged fuel reduction to a subset of fuel nozzles, maintaining operational stability and reducing the frequency of costly restarts.
Implementation Method 1
a plurality of check valves located between the secondary fuel circuit and the primary fuel circuit for restricting the fuel flow from the secondary fuel circuit to the primary fuel circuit
Implementation Method 2
a main fuel flow control valve disposed in the primary fuel circuit for restricting fuel flow to the fuel distribution manifold upon removal of an electrical load operably coupled to the gas turbine engine
Implementation Method 3
a plurality of fuel nozzles configured to direct fuel to the combustor chamber
Implementation Method 4
a fuel distribution manifold which directs fuel to a combustion chamber
Data Source
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AI summary
A fuel routing system 30 of a gas turbine engine 10 includes a primary fuel circuit 32 in communication with a fuel source and a fuel distribution manifold 34. Also included is a secondary fuel circuit 50 extending from the primary fuel circuit 32 to a plurality of fuel nozzles 52 configured to direct fuel to a plurality of combustor chambers. Further included is a main fuel flow control valve 41 disposed in the primary fuel circuit 32 for restricting a fuel flow to the fuel distribution manifold 34 upon removal of an electrical load operably coupled to the gas turbine engine 10. Yet further included is a plurality of check valves 60 disposed between the secondary fuel circuit 50 and the primary fuel circuit 32 for restricting the fuel flow between the secondary fuel circuit 50 and the primary fuel circuit 32.