Actively Cooled Fuel Controls Presentation

Actively Cooled Fuel Controls: Enhancing Liquid Fuel System ReliabilityPresenter: Schuyler McElrathJASC: Jansen’s Aircraft Systems Controls, Inc.2303 W. Alameda Dr.Tempe, AZ 85282Phone: 602-438-4400Fax: 602-438-4420Email: engineering@jasc-controls.comwww.jasc-controls.com484 010001020304050607080901002 transfers in50 attempts33 transfersin 33 attemptsCompletedtransfersFailed transfersSuccess rateStarts on dieselfuel2500% improvement in transfer reliability rates. Successful transfer rate improved from 4% to 100% during the test period, August 2004 to September 2005.1998 - 2004 August 2004 - September 20058000+ hours of operation with WCLFCV’s during 200596,000 cumulative hours of check valve operation without a failureHistory of Check Valve Failures1950- 19981. Different variations of Ball & Spring Check Valve designs utilized: All failed within 2 years of operation requiring fleet wide replacements for in-warranty units. 2. Soft seat check valves: seal melts due to high temperatures, valves stick shut 3. excessive leaks when particulates are trapped between ball and seat during fired shutdowns, 4. ball and/or seat damaged by particles traveling through valve at high velocity,5. Flow Instability: High frequency oscillation at various pressures and flows; resulted in premature wear of valve internal components, hydraulic hammer caused cycle fatigue failures (breakage) of fuel tubing, resulting in turbine compartment leaksJASC check valve design features1. Flow stability addressed by incorporating Hem Holtz resonator circuit. This feature will dampen flow divider generated pressure signature of 90 psi pk-pk to 5 psi pk-pk for the entire flow range. Eliminates high frequency oscillation, hydraulic hammer and fatigue related tubing failures.2. Vespel seal material rated for continuous service of 575 degrees “F”, can withstand short intervals of 700 degrees. Abnormal conditions which expose material to 1000+ degrees will only result in charring and cause material to crack. There is no risk of disintegration or material moving downstream to block nozzle orifices.3. Contamination tolerant design: Multiple injections of 480 grams of Arizona road dust failed to impact the check valve functionality. Feature allows valve to function properly in spite of catastrophic filter failure4. Knife edge seat decreases risk of particles being trapped between the poppet and seat . As little 5 psi of backpressure will embed particulate into the seat and allow the valve to close.Current liquid fuel system issues in dual fuel applications1. Transfer reliability impacted2. Multiple start attempts required when firing on distillate3. Excessive exhaust temperature spreads4. Liquid fuel system pressurized by purge air/CPD5. Check valve or 3-way purge valve refurbishment or replacement required after gas operation due to coking6. Contamination related failures during commissioning7. Coking of fuel lines8. Liquid Fuel Thermal Expansion during gas operation9. Complete evacuation of liquid fuel lines back to flow divider or beyond10. Trips at load during transfer attemptsStandard Liquid Fuel Check Valve InstallationHigh Temperatures cause cokingFuelOxygenTemperatureWhen operating a dual fuel turbine on gaseous fuel the liquid fuel system is idle. Stationary fuel in close proximity to the combustor is exposed to high temperatures, above 250 degrees “F”, which oxidize the fuel and turn it into a hard substance which coats the internal surfaces of the check valve components, restricting their movement. Once this occurs the check valve will not open and close properly.Lower the temperature and eliminate coke formationExample of coking in ball & spring check valve designCoking – Primary Cause for Failed TransferA standard Liquid Fuel Check Valve showing the realized coking potential.Coking recovered from inside this check valve during disassemblyWater Cooling of Flame DetectorExtending Concept to Liquid Fuel Check ValvesInstalled in 6FA• Design Benefits and Expectations– Low cost and ease of installation.• Added connections to cooling water supply and return.• Installed tubing distribution supply and return ring in turbine compartment.• Cooling requirement is .25 to 1 GPM per check valve.• 40 to 80 psi of water pressure.• No controls modifications needed.– Improved fuel transfer ability.– Improved start up reliability on diesel fuel.– Check valve life of 20 years or moreWater Cooled Liquid Fuel Check ValveDevelopmental Water Cooled LFCV with a welded sleeveProduction Water Cooled LFCV using a cast sleeveAll variants of the Water Cooled LFCV use the same internal components as the standard LFCVInstalled in 6FACW SupplyCW ReturnWCLF Check ValveWater lines rated to 1500 psi, operating pressure 40 to 80 psiUncooled vs. Cooled Check ValvesUncooled Check Valve Water Cooled Check ValveLess than 100 fired hours 1,300 fired hours Failed Transfers - Trips0510152025303540High Exhaust Spread High Exhaust Temp Loss of Flame OtherMost Common Trip During Transfer – High Exhaust Spread Temp.Cause – Stuck Liquid Fuel Check Valves due to coking.Typical gas turbine failure modes during transfer attempts4 trips related to nitrogen valve control problemExhaust temperature spread, maximum temperature and loss of flame are key indicators of check valve condition, i.e. sealing properly, opening and closing without restriction. Note that there have been zeroincidents in major categories since the WCLFCV’s were installed in August 2004.BeforeWCLFCV'sInstallationAfter WCLFCV’sinstallationActively Cooled Fuel Controls: Enhancing Liquid Fuel System Reliability1. JASC water cooled liquid fuel check valves addresses all previous failure modes and the most recent, coking. 2. Eliminate high exhaust temperature related trips due to sticking check valves.3. Refurbish and perform maintenance on liquid fuel check valves every 4 or 5 years during scheduled major outages.4. Eliminate the need for multiple starts in order to purge air from your liquid fuel system.5. Low installation costs, readily applied to all frame sizes.6. No controls modifications required.7. Simple to assemble or disassemble before and after scheduled maintenance.8. Ability to exercise your liquid fuel system regularly without worrying about the condition of your fuel controls.The future of Actively Cooled Fuel Controls: Enhancing Liquid Fuel System Reliability• Water Cooled Combining valve design features– Replaces liquid fuel check valve– Replaces purge air valves– Replaces fuel distributor valve– Integral strainer to eliminate contamination failures– Eliminate coking and leak related issues on all 3 major componentsThe JASC Water-Cooled Combining Valve33--Way Purge Valve Overview:Way Purge Valve Overview:Replaces Liquid Fuel & Purge Air Check ValvesOver 3000 Units in Field OperationNo Active Water Cooling (currently) -Units in High-Temperature Locations are Prone to Internal Coke FormationNo Particle Trap - Seals are Typically Damaged During Initial Firings Due to Large Particulate Contamination of the FuelThe WaterThe Water--Cooled Combining Valve:Cooled Combining Valve:Valve is Designed to Emulate Functions of Current OEM Fuel Distributor ValveAddresses Specific Issues of Current Valves to Improve Overall Liquid Fuel System Reliability:Effective Water-Cooling DesignStaged Fuel DeliverySmall Quiescent Internal Fuel VolumeRemovable Fuel Inlet ScreenPilot Air Actuation can be Incorporated (if required)Valve / Bracket AssemblyBracket OnlyFuel InletWater InletPurge Air InletMounting SurfacesCradleFuel Distribution PortsWater Cooling has arrived• Combining Valve design used for DLN applications• Bolt-on configuration• Technology can be readily applied to all dual fuel gas turbine applicationsRESULTSMax. Temp. Spool “Balloon” Surface: 187 °FAvg. Temp. Water at Discharge Port: 152 °FStatic fuel in cavityMax. fuel temp is Max. fuel temp is sufficiently sufficiently belowbelowcoking temperaturecoking temperatureWater Cooling Thermal Analysis, Current Valve @ 1.5 GPM Worst Case Boundary ConditionsNote that max. temp Note that max. temp occurs occurs away fromaway fromspool seal regionspool seal regionMax. Temp. Fuel:210 °FCost Analysis Considerations• Installation of both systems is relatively simple• Tap into existing water system• Maintenance only required during major outages• Significantly improved Transfer reliability • Elimination of coking related failures• Elimination of contamination related failures• Enhanced start capability on liquid fuel• Elimination of trips associated with high exhaust temperature spreadsSummary• JASC has had great success developing complete systems or integral components which resolve process control problems in a variety of industries and applications.• Continuous improvement of existing designs provides our customers with products which exceed all expectations.• Our goal is to provide our customers with a level of service which is unparalleled. • We actively seek opportunities to apply our problem solving ability to your issues. JASC Contact InformationJASCJansen's Aircraft Systems Controls, Inc.2303 W. Alameda DriveTempe, AZ 85282Website: www.jasc-controls.comPhone: 602-438-4400Fax: 602-438-4420Email: Sales@jasc-controls.comEmail: Kevin@jasc-controls.com Technical product information Contacts: Harvey Jansen, President/CEOKevin Deutscher, Operations ManagerSchuyler McElrathSchuyler McElrathSMTC, INC.SMTC, INC.JASC Gas Turbine System’s ConsultantJASC Gas Turbine System’s ConsultantPO Box 17203PO Box 17203Greenville, SC 29606Greenville, SC 29606Phone: 864Phone: 864--350350--43324332Fax:Fax: 864864--220220--59135913Email: Email: smcelr8176@aol.comsmcelr8176@aol.com