module 9 - fuel systems.pdf
TRANSCRIPT
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Barinas Power Plant
Fuel Systems
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Fuel Systems
LIQUID FUEL SYSTEM
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Learning ObjectivesUpon completion of this training, participants will beable to:
Identify the basic system components and trace theliquid fuel delivery path.
Describe the basic principles of operation for the fuelpump, bypass valve, and the pressurizing and drainvalve.
Describe the purpose and operation of the air assistsystem.
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Liquid Fuel SystemPURPOSE
Provides clean, high pressure, regulated fuel to the fuelnozzles.
REQUIREMENTS
Specification: TPM FR-1 specifies liquid fuel requirements for
stationary gas turbines.
Clean fuel is essential to prevent fuel nozzle clogging. Clogged nozzles will result in a poor spray pattern that
affects temperature distribution and leads to hot-section distress.
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Liquid Fuel SystemBASIC GROUPS
Fuel Forwarding (External)
Gas Generator (at the power unit)
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Liquid Fuel SystemFUEL FORWARDING SYSTEM
PURPOSE
Pre-conditions fuel for delivery to the gas generator(power unit) mounted system components.
COMPONENTS Fuel Storage Tank
AC and DC powered pumps
Heated Fuel Filters Flowmeter and Fire Valve
Fuel Heater
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Liquid Fuel SystemPUMPS
AC powered centrifugal pumps provide full flow atmaximum power.
Optional DC pump provides flow to start one gasgenerator and accelerate to minimum power.
Wire mesh strainer mounted in-line acts to protectfrom large foreign objects.
Bypass orifice recirculates fuel when flowrequirements drop.
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Liquid Fuel SystemFILTERS
10 micron nominal
FIRE VALVE Magnetically held open. Will close in the event of an
enclosure fire.FUEL HEATER
Fuel recirculates to the storage tank to provide warmfuel delivery at start.
Heater turns off after gas generator starts.
Heaters turned back on after shut down.
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Liquid Fuel System
FUEL FORWARDING SYSTEM - TYPICAL
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Liquid Fuel Sys. - Gas Generator ComponentsPURPOSE
Supplies high-pressure metered fuel to the combustionsection.
COMPONENTS AND SUBSYSTEMS
Gas generator driven Main Fuel Pump. Liquid Fuel Throttle Valve (Modulating Valve).
Bypass Valve.
Pressurizing and Dump Valve. Fuel Manifolds and Fuel Nozzles.
Air Assist.
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Liquid Fuel Sys. - Gas Generator Components
BASIC LIQUID FUEL SYSTEM SCHEMATIC
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Liquid Fuel Sys. - Gas Generator ComponentsMAIN FUEL PUMP
Driven by gas generator through accessory gearbox.
Centrifugal "boost" stage located opposite the driveend. Boost stage is driven through a gear train andhas a shear section.
Boost pressure passes through a 60x60 mesh filter.Filter will bypass if it becomes clogged.
Positive displacement gear stage provides dischargeto the Liquid Fuel Throttle Valve.
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Liquid Fuel Sys. - Gas Generator Components Internal pressure relief valve provides bypass for low
flow conditions. Adjusted to limit pressure to amaximum of 835-845 psig.
Bypass from throttle valve returns to the pump andenters same path as boost stage discharge.
Pressure taps are provided at key locations forinstrumenting pump to check performance.
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Liquid Fuel Sys. - Gas Generator Components
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Liquid Fuel Sys. - Gas Generator ComponentsBYPASS VALVELOCATIONInstalled in line between throttle valve and P&D valve.FEATURES Redundant shutoff for liquid fuel supply. 125 VDC solenoid operated. Energized - valve opens to let fuel flow to P&D. De-energized - spring pressure closes valve to let fuel
flow bypass.
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Liquid Fuel Sys. - Gas Generator Components Electrical signal from Free Turbine (N3) N3 overspeed = Shutdown. Loss of N3 signal = Shutdown.
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Liquid Fuel Sys. - Gas Generator Components
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Liquid Fuel Sys. - Gas Generator ComponentsPRESSURIZING AND DUMP VALVE
LOCATION
Mounted on Diffuser at 6 o'clock position. Contains apressurizing section and a drain (dump) section.
PURPOSE Supplies fuel to the primary nozzles during light off
and start.
Provides air assist through secondary nozzles. Provides fuel to secondary nozzles at high power
settings. Drains fuel manifolds at shutdown.
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Liquid Fuel Sys. - Gas Generator Components
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Liquid Fuel Sys. - Gas Generator ComponentsOPERATION
Metered fuel passes through mesh filter.
Fuel pressure (125 psi) from throttle valve acts onpiston and closes drain poppet.
Fuel pressure opens the pressurizing valve and fuelflows through the primary outlets.
Air assist pressure for fuel atomization during start isprovided through secondary outlets untilapproximately 5200 RPM N2.
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Liquid Fuel Sys. - Gas Generator Components At about 250 psig, fuel pressure opens the
pressurizing valve further to provide fuel flow throughthe secondary outlets for high power operation.
At shutdown, pressure signal from throttle valve dropsand lets spring pressure open the overboard drain.Pressurizing valve closes and primary sections of fuelmanifolds drain while air assist purges the secondary.
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Liquid Fuel Sys. - Gas Generator Components
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Liquid Fuel Sys. - Gas Generator ComponentsAIR ASSIST
PURPOSE
Improves fuel atomization during starting by injectinghigh pressure air into the secondary flow section offuel system. This helps fuel mixture lightoff at coldstart when using typical marine standard fuels.
Purges secondary manifold at shutdown.COMPONENTS
Filter
Solenoid Check valve
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Liquid Fuel Sys. - Gas Generator ComponentsOPERATION
As the start sequence begins, fuel will only be suppliedthrough the primary path.
A signal from the fuel control energizes the solenoid,permitting high pressure filtered air to flow upstreamand unseat the check valve.
From the check valve, air flows through the secondarysection of P&D valve and into the secondary supply tothe fuel nozzles.
After lightoff, the fuel control de-energizes thesolenoid at about 5200 N2 RPM to shut off the airsupply. Check valve seats to prevent fuel from flowingto the air assist system.
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Liquid Fuel Sys. - Gas Generator Components
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Liquid Fuel Sys. - Gas Generator ComponentsFUEL NOZZLES AND COMBUSTION FUEL SUPPLYPURPOSEDeliver precisely measured fuel spray to combustionchambers for atomization and ignition.DESCRIPTION Two manifolds each having four nozzle clusters. 48 Nozzles, arranged in clusters of six for each
combustion chamber. Nozzles fit in stator swirler guides on dome of
chamber. Two fuel paths, primary and secondary.
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Liquid Fuel Sys. - Gas Generator Components Primary flow is constant during operation. Secondary
flow occurs during high power operation. The constant primary flow cools the secondary
discharge area to reduce coking that could occur whenfuel is not flowing at lower power.
Air blast from HPC flows through stator swirlers toatomize the fuel.
Nozzles are precision manufactured to closetolerances to produce optimal spray pattern.
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Liquid Fuel Sys. - Gas Generator Components
COMBUSTION FUEL SUPPLY
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Liquid Fuel Sys. - Gas Generator Components
LIQUID FUEL NOZZLE
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Fuel Systems
GAS FUEL SYSTEM
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Learning ObjectivesUpon completion of this training, participantswill be able to: Identify the basic system components and trace the
gas fuel delivery path.
Describe the basic safety features of the fire valve andredundant shutoffs.
Describe the features of the throttle valve.
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Gas Fuel SystemPURPOSE
Provides gaseous fuel delivery system used in place ofliquid fuel.
COMPONENTS
Fire Valve. Strainer.
Flowmeter.
Shutoff Valves. Throttle Valve (Modulating Valve).
Fuel Manifolds and Nozzles.
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Gas Fuel System
BASIC GAS FUEL SYSTEM
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Gas Fuel SystemFIRE VALVE
PURPOSE
Emergency shutoff for system protection.LOCATION
As close as possible to the access door.
DESCRIPTION Held "open" by 125 VDC power supply.
If temperature exceeds 450F inside the enclosurevalve will close.
Must be manually reset using lever on valve onceactivated.
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Gas Fuel System
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Gas Fuel SystemSTRAINER
PURPOSE
Prevents foreign matter from entering components inthe system.
LOCATION Installed in line between the Fire Valve and the shutoff
valve.
Has cleanable mesh screen.
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Gas Fuel System
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Gas Fuel SystemFLOWMETER
PURPOSE
Provides an accurate indication of gas flow rate to theengine controller for comparison to power levelrequirements.LOCATION
Located in line before the shutoff valves.
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Gas Fuel SystemDESCRIPTION AND OPERATION
This unit is a highly accurate turbine fuel flow meter. Itis delivered factory calibrated and certified for specificflows and temperature ranges.
Turbine rotation inside the flowmeter generates anelectrical signal that is proportional to gas flow.
The signal is supplied to the control system where it isused to make decisions to adjust the throttle valve.
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Gas Fuel System
TYPICAL GAS FLOW METER
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Gas Fuel SystemSHUTOFF VALVES
PURPOSE
Emergency (redundant) shutoff for the gas fuel supply.Closes when there is a power failure, EGT over limits, orN3 overspeed occurs.DESCRIPTION
Solenoid operated spring poppet valve that uses gasline pressure to seat and unseat.
Located in line between flowmeter and throttle valve.
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Gas Fuel SystemOPERATION
During normal operation, solenoid is powered toactivate a plunger which opens a vent. Gas escapesfrom back side of piston through the vent. Pistonunseats and gas flows through supply line.
When power is removed, solenoid releases plungerand vent closes. Gas flows to back side of piston andworks with spring pressure to close the valve and stopgas flow.
Automatically signaled by the control system. Alsocan be manually controlled from a switch on operatorcontrol panel.
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Gas Fuel System
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Gas Fuel SystemFUEL THROTTLE VALVE (MODULATING VALVE)
PURPOSE
Controls flow of gas fuel to the engine.DESCRIPTION
Installed in-line after the gas shutoff valves. Useselectrical power to increase or decrease fuel flow inresponse to the SPC2A control.
Three sections: Actuator and feedback
Throttle
Bypass
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Gas Fuel SystemOPERATION
Electric motor drives gear train to position the throttlevalve. Feedback potentiometer (variable resistor)provides valve position and rate of change to preventovershoot.
Minimum light-off flow for starting is provided througha by-pass orifice.
A second by-pass orifice was previously used for 100psi operation in conjunction with a solenoid. Nowblocked off and not used.
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Gas Fuel System
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Gas Fuel SystemEXTERNAL FUEL MANIFOLDS
PURPOSE
Provide the flowpath for gas fuel to enter the internalfuel manifolds and fuel nozzles.
DESCRIPTIONExternal manifolds feed gas from throttle valve to foursets of internal manifolds
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Gas Fuel System
GAS FUEL EXTERNAL MANIFOLDS (Typical)
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Gas Fuel SystemINTERNAL FUEL MANIFOLDS
PURPOSE
Provide the flowpath for gas fuel between the externalfuel manifolds and the fuel nozzles.
DESCRIPTIONEach internal manifold has two clusters of six nozzles.Nozzles fit into swirler guides on dome of chamber.
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Gas Fuel System
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Gas Fuel SystemFUEL NOZZLES
PURPOSE
Mixes gas fuel with compressor discharge air in thecombustion chamber for ignition.
DESCRIPTION Nozzles fit into swirler guides on dome of chamber.
Air blast from HPC flows through stator swirlers andmixes with gas flow.
Nozzles are precision manufactured to produceoptimal discharge and resulting flame pattern.
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Gas Fuel System Field maintenance is limited to complete nozzle
replacement. Always replace nozzles in complete sets to assure
equal supply and flame pattern.
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Gas Fuel System
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Fuel Systems
DUAL FUEL SYSTEM
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Learning ObjectivesUpon completion of this training, participants will beable to: Describe the purpose, function, and operation of the
dual fuel system.
Highlight the special purpose solenoid valves.
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Dual Fuel SystemPURPOSE
Permits selection for operation on either liquid or gasfuels.
DESCRIPTION
The liquid and gas systems function independently asselected. Their function and operation are essentiallythe same as the previously described separate liquidand gas systems.
Most components are assembled on a fuel skid plateas a modular unit.
External fuel manifolds and the fuel nozzles areunique, permitting delivery of either fuel type.
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Dual Fuel SystemOPERATION
Usually starts are made on gas fuel. Transfers toliquid (or gas) are made at a stabilized IDLE.
Starts can also be made in the liquid fuel mode.
An electrically controlled clutch disengages the liquidfuel pump when gas fuel operation is selected.
Liquid fuel recirculates to the supply tank during gasfuel operation
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Dual Fuel SystemSPECIAL SOLENOID VALVES
GAS ASSIST VALVES
Introduce gas fuel to the gas section of the fuelmanifolds to improve light off during a liquid fuel start.
LIQUID MANIFOLD PURGE Opens during gas fuel operation to provide gas flow
through the liquid fuel section of the fuel manifolds.
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Dual Fuel SystemLIQUID SUPPLY VENT
Opens at shutdown to drain the liquid fuel supplybetween shutoff valve No. 2 and the check valve.
LIQUID MANIFOLD DUMP
Opens at shutdown to drain the liquid fuel supplybetween the check valve and the fuel nozzles.
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Dual Fuel System
TYPICAL DUAL FUEL SYSTEM
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Dual Fuel SystemELECTRICALLY CONTROLLED CLUTCH
PURPOSE
Permits disengagement of liquid fuel pump drive duringgas fuel operation. Reduces running time and wear onfuel pump.
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Dual Fuel System
FUEL PUMP CLUTCH
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Dual Fuel SystemMANIFOLDS AND TUBES
Gas supply manifolds are identical to the gas fuelsystem.
Elbow connectors to the internal manifolds are "tee"fittings.
Liquid fuel tubes introduce liquid fuel supply at the"tee" fittings.
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Dual Fuel System
DUAL FUEL SUPPLY CONNECTION
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Dual Fuel SystemDUAL FUEL NOZZLE
PURPOSE
Atomizes fuel for combustion.
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Dual Fuel System
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Dual Fuel SystemFUEL PLATE ASSEMBLY
PURPOSE
Provides clean, high pressure, regulated fuel to the fuelnozzles.
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Dual Fuel System
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Dual Fuel System
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Water Injection SystemPURPOSEMixes and injects de-mineralized water into the fuelsystem. This aids in controlling combustiontemperature for reduced Nitrogen Oxide (Nox)emissions.OPERATIONLIQUID FUEL Water is injected directly into the fuel distribution
block where it "mixes" with liquid fuel and the flow isdelivered through the normal liquid fuel system.
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Water Injection SystemGAS FUEL During gas fuel operation the fuel shut off valve is
blocking liquid flow from the main fuel pump. Water isinjected and delivered to the fuel nozzles using thesame liquid fuel path and mixes with the gas fuel at thefuel nozzles.
SHUTDOWN Dump solenoid opens to drain water from system. 25
psi air purge makes sure all water is removed fromsystem.
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Water Injection System
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Are there any questions?
Review the sections learning objectives.
Fuel SystemsFuel SystemsLearning ObjectivesLiquid Fuel SystemLiquid Fuel SystemLiquid Fuel SystemLiquid Fuel SystemLiquid Fuel SystemLiquid Fuel SystemLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsLiquid Fuel Sys. - Gas Generator ComponentsFuel SystemsLearning ObjectivesGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemGas Fuel SystemFuel SystemsLearning ObjectivesDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemDual Fuel SystemWater Injection SystemWater Injection SystemWater Injection SystemSlide Number 73