Lightoff Fuel Pressure Reduction System for Gas Turbine Ignition
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Solution Overview
Problem
Existing gas turbine engines face challenges in accurately controlling fuel flow during ignition due to high errors associated with small fuel openings, leading to uncertainties in start-up success.
Innovation Solution
A lightoff fuel pressure reduction system (LFPRS) that includes a valve on the main flow path, a pressure reducing regulator on a bypass flow path, and a vent between the valve and fuel control valves, which reduces fuel pressure to an ignition pressure, allowing for more accurate fuel metering during ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the fuel control valves are controlled to be nearly closed during ignition to provide small amount of fuel, then the fuel flow quantity is reduced to ignition level, but the metering accuracy deteriorates with up to 50% error
Solution Approach 1:
The system performs preliminary pressure reduction through the pressure reducing regulator before fuel reaches the control valves during ignition. By pre-reducing pressure in the bypass line, the system enables accurate metering at low flow rates without requiring the control valves to be nearly closed, thus maintaining measurement precision while achieving the required small fuel quantity.
Solution Approach 2:
The pressure reducing regulator acts as an intermediary device between the facility fuel supply and the fuel control valves. It mediates the fuel pressure to provide a reduced pressure signal during ignition, allowing the control valves to operate in a more favorable pressure range for accurate metering even at low flow rates.
2Stress or pressure
If the facility fuel pressure supply regulator is set to full power level, then the fuel pressure is sufficient for high power operation, but the fuel pressure is too high for accurate ignition metering
Solution Approach 1:
The system dynamically adjusts fuel pressure based on operational phase. During ignition, the pressure reducing regulator reduces pressure through the bypass line to enable accurate metering. During full power operation, the main fuel control valves modulate the higher pressure supply to achieve required flow rates, allowing the system to adapt pressure levels to match operational requirements.
Solution Approach 2:
The fuel supply system is segmented into two parallel paths: a main line for high pressure/full power operation and a bypass line with pressure reducing regulator for low pressure/ignition operation. This segmentation allows simultaneous capability for both high pressure supply and low pressure accurate metering without compromise.
3Quantity of substance
If the fuel control valves are nearly closed during ignition, then the small fuel opening provides required ignition fuel flow, but the error in metering increases to approximately 50%
Solution Approach 1:
The system changes the pressure parameter during ignition by reducing it through the pressure reducing regulator in the bypass line. This parameter change transforms the operating conditions at the fuel control valves, allowing them to maintain better control precision even when delivering small ignition fuel flow rates, as the reduced pressure improves the relationship between valve opening and actual flow rate.
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 LFPRS system reduces the likelihood of start-up failures by accurately controlling fuel flow during ignition, ensuring reliable engine start-up and transition to operational pressure.
Implementation Method 1
the pressure reducing regulator reduces pressure in a portion of the main flow path that is downstream from the LFPRS valve to an ignition pressure
Data Source
AI summary
Traditionally, during ignition of a gas turbine engine, the fuel control valves are controlled to be nearly closed, in order to provide the small amount of fuel that is necessary to ignite the gas turbine engine. The error that is inherent in providing fuel flow through small openings results in a higher likelihood of start-up failures. Accordingly, a lightoff fuel pressure reduction system is disclosed that uses a pressure reducing regulator on a bypass flow path to temporarily reduce the pressure of fuel supplied to the fuel control valves. In this case, the fuel control valves may be maintained in a more open position during the ignition phase, which reduces the likelihood of ignition failures.