Performance Characteristics of PAG-Based Synthetic Turbine Fluid in GE 7FA Turbines A Non-Varnishing Lubricant for Heavy Duty Gas Turbines Govind Khemchandani, Ph.D. The Dow Chemical Company STLE 2012 Annual Meeting, May 6-10, 2012, The Renaissance Grand Hotel and the America's Center, St. Louis Session: Power Generation I
Objectives PAG-based Synthetic Turbine Fluid performs better because base fluid inherent properties matter Successful trials in GE 7 FA heavy duty gas turbine confirm non-varnishing performance No gel, varnish or particulates on last chance filter after three years of continuous use in GE 7 FA turbines
Varnish, Varnish, Varnish TLT Magazine, January Varying degrees of varnished servo valve filters 2008 TLT Magazine, April 2011
Defining the Opportunity Heavy Duty Gas Turbines Common sump - lube oil & hydraulic system varnishing IGV s and/or GCV s are driving trips Significant cost due to varnish related trips (lost revenue & maintenance) Standard lube oil tests incapable of varnish detection Varnish removal filter skids expensive and need regular Monitoring Degradation of hydrocarbon turbine oils continue to persist
Gas Turbine Operators: Why Evaluate and Specify PAG-based Turbine Fluid Technology End Users will have less trips and longer servicelife by using PAG-based turbine fluids with outstanding varnish-free performance End Users can implement a varnish-free solution faster by leveraging PAG s experience and data in turbo machinery applications
PAG Technology: Designed to Refined OSP PO BO
What is Different? Group I-III Group I Solvent treated for color improvement Group II>III = Non-Polar Base Oil hydro-processing, hydrotreating, catalytic de-waxing and hydrocracking techniques Group IV Polyalpha olefins (PAO) Non- polar Group I-IV No oxygen in molecule PAO s are all carbon and hydrogen Group V PAG s are Polar Every 3 rd atom is oxygen CHEMICAL COMPOSITION Oxygen rich polymer providing polarity and non varnishing ability in turbo-systems
Aniline Point for Various Base Stocks
Equipment Reliability Varnish Elimination Oxidation of Hydrocarbon Oils and PAGs
PAGs Tribological Performance New Way to Measure Friction Properties
Evidence of Technical Solution Turbine Fluid Conversions Converted 10 gas turbines since 2007 All fluid conditions track well Consistent measurements of TAN, Particle Count, Metals, AO, & Water Content No Varnish Formation Base Load Peaker Peaker/Cyclic
Evidence of Technical Solution Tribological Characterization Mini-Traction Machine (MTM) Traction Curve of Turbine Fluids Conditions: 70 C, 0.8 Gpa Load @ 1000 mm/sec Low coefficient of friction can generate operating energy savings Lower traction coefficients than a petroleum-based turbine oil even in presence of water Confirmed by a decrease in temperature measurements of operating turbine bearings @ Calpine & Plaquemine turbines
Equipment Reliability Wear Performance Four Ball Wear Test ASTM D 4172 Test Conditions: 40Kg, 1200 rpm, 1 hour, 75 C PAG s have inherent anti-wear protection Not reliant on additives like traditional oils Wear 0.70 mm after Five years in Peaker Turbine
Evidence of Technical Solution Specification PAG-based Turbine Fluid PAG-based Turbine Fluid After 5 years use in a Peaker Turbine Foam Tendency, ASTM D892, ml Seq. I 10/0 10/0 Seq. II 0/0 0/0 Seq. III 0/0 5/0 Air Release, ASTM D3427 (Minutes @ 50 C) 0.4 0.4 Excellent air release for both neat fluid and fluid after five years in peaking turbine Lower air release times than those typical of petroleum and hydrocarbon-based turbine fluids (4.0 to 5.0 recently tested) - GEK 32568G Spec requires 5.0 max Prolonged air release times can lead to pump cavitations, micro dieseling, premature oxidation, and component wear.
AEP Last Chance Filter Tear Down After Three Years Filter Body/Baffle with Ends Stainless Steel Mesh Paper Filter Wire Screen
Experimental: Last Chance Filter Analysis Method: Oblique reflected light microscopy (LM) Instrument: Leica WILD MZ-16 stereo-zoom light microscope equipped with a Nikon DXM 1200 digital camera and ACT-1 image acquisition software Sample Preparation: Samples were imaged using oblique reflected light (fiber optic light and ring lamp) Extracted Oil: Subjected to ICP analysis All metals were <1 ppm (Fe, Ni,Al,Sn,Ag,Cr, Pb,Si,B) K, Ca were <10ppm
Paint Compatibility Test: P23E-AL-0204 Rev. E Experimental Paint: A8B95 1-Part Gold Phenolic-Epoxy Primer (GE approved Paint) Thinner: D5E11 n-butyl Acetate Oils: PAG based Turbine Fluid Petroleum based Turbine Oil Surface Preparation Sec 4.5: Sand blasted steel panels Paint Preparation: Sec 4.6 Coating Applications: Sec 4.7 30 Days Immersion Testing @ 200 F Delta E is defined as total color difference between sample and the standard Oil Type Delta E PAG based Turbine Fluid 11.81 PAG based Turbine Fluid 11.42 PAG based Turbine Fluid 12.12 Petroleum based Turbine Oil 21.30 Petroleum based Turbine Oil 20.46 Petroleum based Turbine Oil 20.49
Paint Coated Panels: 30 Days Immersed @ 200 F No sign of wrinkling, blistering, or peeling Petroleum turbine oil darker in color vs. PAG turbine fluid Standard PAG Turbine Fluid Petroleum Turbine Oil
Evidence of Technical Solution: Peer Reviewed & Published Research Papers Tribological Characteristics of PAG based Synthetic Turbine Fluid, Khemchandani, G., Technische Akademie Esslingen (TAE), 17 th International Colloquium Tribology, January 19-21, 2010, Stttgart/Ostfildern, Germany Non-varnishing and Tribological Characteristics of Polyalkylene Glycol-based Synthetic Turbine Fluid, Khemchandani, G., Lubrication Science (2011), DOI: 10.1002/ls.165,Wiley, NewYork GE 7 FA Conferences, 2009, 2010 and 2011, PAG-based Turbine Fluid Presentations by David Wilkes of AEP, Khemchandani, & Jeff Freeman of DOW GE 7EA User Group Zeroed In On Oil Analysis and Selection, Turbo-Machinery International January/February 2012 Turbine Lubricants: Biodegradable, Preventative Alternatives, Power Engineering, February 2012 Fighting Friction, Chemical & Engineering News, October 11,2010
Performance Advantages of Polyalkylene Glycol Turbine Fluid Non-Sludge or Varnish Forming significant maintenance cost reduction Less Potential for Micro-Dieseling excellent low foaming and airrelease properties Reduced Static Discharge outstanding heat transfer Hydrolytic Stability no breakdown or reaction with water High Temperature Stability longer oil life and increased reliability Reduced Friction high viscosity index allows use of low viscosity grade Detergency keeps systems clean and free of staining or sticky residue Proven Experience with Turbo-Machinery operating in severe conditions and tight clearances
Thank You! Govind Khemchandani, Ph.D. The Dow Chemical Company GVKhemchandani@dow.com