Contamination Control For Wind Turbines ASME Graduate Student Workshop October 2009 Bill Needelman Chief Science Advisor Donaldson Company, Inc
Study by Professor E. Rabinowicz, MIT Six to seven percent of the Gross National Product is required just to repair the damage caused by mechanical wear. Note: Currently ~$1 trillion Loss of Usefulness Obsolescence (15%) Surface Degradation (70%) Accidents (15%) Corrosion (20%) Mechanical Wear (50%) Abrasion Fatigue Adhesion
Wind Turbine Reliability & Performance 25 % of Cost of Ownership of Wind Turbines is Maintenance Reliability Problems Gearbox > Blades > Generators 80% Of Operating Problems Due to GBX Mostly Gearbox Repair & Replacement Bearings are #1 Cause of Gearbox Failures Most Gearbox Warrantees ~2 Years, Costly Repairs Start ~4 th Year 90% Anticipated Energy Production 5% GBX, 3% Wind, 2% All Others
Hard Particle Damage Bearing Fatigue Hard Ductile (e.g. T15 & 52100 Steel) Hard Rigid (e.g. Al2O3 & SiC) Hard Friable (e.g. TiC) 1 Life Relative to Non-Dented Bearings 0.1 0.01 0.001 40 50 60 70 80 90 100 110 120 130 Debris Particle Size Ref: Kotzalas & Needelman, AWEA Wind Power Conf, 2008
Outline Problems Caused by Oil Contamination Particle Filters Water Contamination Control Best Practices Benefits & Conclusions
Types of Contaminants Particles - Hard & Soft Water Air/Gases Fuels, Acids, Glycols
What is a MICRON? MICRON Unit of Measurement 1 Millionth of a Meter (micrometer) Or.000039" µ = Micron Symbol PARTICLE SIZE 100µ=Grain of table salt 70µ=Typical human hair diameter 40µ=Lower limit of visibility 10µ=Talcum powder 2µ=Bacteria 1µ 100 µ 10 µ 40µ
The Particle Zoo
19/17/15 18/16/14 20/19/17 21/20/18 23/22/20 21/20/18 26/24/22 16/15/13 15/14/12 TOO DIRTY TO EVALUATE
Major Types & Sources of Hard Particle Contaminants in Wind Turbines Hard Particles Manufacturing Swarf Machine Chips, Casting Sand, Grinding Debris, Abrasives Internal Wear Debris Gear Tooth Wear Internal Corrosion Products Rust, Aluminum Oxide Environmental Grit Airborne Mineral Dust, Sand Bath Tub Model
Hard Particle Problems Rolling Contact Fatigue Abrasive Wear & Erosion Lubricant Oxidation
Mechanical Wear By Hard Particles Abrasive Wear Adhesive Wear All Three Forms of Wear Result in Loss of Clearance, Rough Surfaces, and Greater Friction Rolling Contact Fatigue
Gear Tooth Contacts Sliding Contacts Rolling Contact
Gear Friction Increases As Gear Tooth Surface Roughens
Rolling Contact Fatigue: Surface Origin Spalls Spalled Area Initiation point Roller Path 16
Older Bearings Failed By Sub-surface Initiated Fatigue Spalling Load Dynamic Fluid Film Thickness (µm) Slag Inclusion In Steel
Particles & Surface Initiated Fatigue Particle Caught Load
Particles & Surface Initiated Fatigue Load Surface Dented, Crack Initiation
Particles & Surface Initiated Fatigue Load Crack Propagation Cracks Spread With Repeated Cycles
Particles & Surface Initiated Fatigue Fatigue Spall Crater Forms Hard Particles Released Load Spall
The Challenge Cleaner Gear Oil Drier Gear Oil Same For Hydraulic Fluids
❷ ❸ ❹ ❸ ❷ ❶ Element Design DT Steel Std ❶ 1 Outer Wrap Collapse n/a High Collapse n/a n/a epoxy coated steel for stainless steel ❷ support and for support and 2 Support Mesh (2) spacing spacing DT Steel Coreless epoxy coated steel for support and spacing ❸ 3 Flow Control Layers (2) ❹ 4 Synteq Media synthetic layers to strengthen media thin glass-fiber media for performance synthetic layers to strengthen media thin glass-fiber media for performance synthetic layers to strengthen media thin glass-fiber media for performance
Filter Media Types - Wire Mesh - Cellulose - Synthetic (Glass Fiber)
Pressure Loss Across A Filter Element ( P) Pressure Loss Flow Rate X Viscosity X Tortuosity Gear Oil Oils: High Viscosity Gear Boxes: Moderate Flow Rates Fine Filters: High Tortuosity
Pore Structure Graded Pore Filter Media
State-Of-The Art Filter Media Conventional Media Resin Bonded New Media Bi-Component
Bicomponent Binder Fiber Glass microfibers Thermoplastic B Sheath Thermoplastic A Core
Bi-Component Filter Medium
Bi-Component Filter Medium Glass microfibers Thermoplastic binder fiber
Field Data: GE 1.5 MW 7000 6000 Hydac Current 10um10 um Turbine #5 >4um >6um 5000 >14um Particles/ml 4000 3000 2000 DT New 5um 5 XP um 1000 0 12/1/08 1/1/09 2/1/09 3/4/09 4/4/09 5/5/09 6/5/09 7/6/09 8/6/09 Dates
Dissolved & Free Water Dissolved Water Below Saturation Free Water Bulk Separation Free Water Emulsified
Major Sources of Water Contamination in Wind Turbines Water Vapor - Humidity Rain (Through Vents & Seals) New Oil
Oil Has A Relative Humidity (RH) At Equilibrium RH of Air Equals RH of Oil (RH Oil = %Saturation) 50% RH Air Water Molecules 50% RH Oil
Humidification Water moves from high relative humidity to low relative humidity 8 0 Moisture Content (% Saturation) 7 0 6 0 5 0 4 0 3 0 2 0 1 0 0 Mobil DTE PM 220 in contact with air controlled at 90 o F & 80% RH 0 8 16 2 4 T im e (H o u rs)
Problems Caused by Water Contamination in Wind Turbines Rolling Contact Fatigue Adhesive Wear Additive Dumping Oil Oxidation
Water Damage Bearing Fatigue 10 SAE 20 + R&O SAE 5 + EP (100/X)^0.6 Navy Data Relative Fatigue Life 1 0.1 10 100 1000 Water Concentration in Lubricant (PPM) Ref: Kotzalas & Needelman, AWEA Wind Power Conf, 2008
Water Water & Fatigue & Rolling Crack Contact Propagation Fatigue Oil + Dissolve Water Forced Into Cracks in the Contact Zone Load Hydrogen Embrittlement
Loss of Fluid Film Lubrication & Adhesive Wear Load Low Viscosity Water Not Able To Support Load Film Collapses Dynamic Fluid Film Thickness (um)
Water Damage Additive Drop-Out Fouled & Disabled Oil-Level Sensor
Water Damage Additive Drop-Out Courtesy COT-Puritech, Inc. Fouled & Disabled Thermostat
Keeping Gear Oils & Hydraulic Fluids Dry in Wind Turbines Prevention Minimize Ingression Removal Rapid
Regenerable Breather Dryer
Inhalation Captures H 2 O Exhalation Regenerates By Releasing H 2 O
Dry Air Blanket System TRAP Breather with Tee and Relief Valve Customer Supplied Flow Meter (Optional to adjust compressed air usage as required) Inlet Port Inlet & Outlet Installed On Opposite Corners Ideal Outlet Port Customer Supplied Shut-off Valve Orifice ARV-3: P568606 ARV-10: P568799 (Must be installed for proper operation of ARV) Reservoir Customer Supplied Shut-off Valve (Required for maintenance of unit) Customer Supplied Pressure Regulator with Guage (set to 100 psi) Ultrapac ARV-3: P568790 ARV-10: P568791 Incoming Compressed Air
Dry Air Blanket System Humid Air Saturated Oil Purging Humid Air Saturated Oil Dry Air Moisture Desorbing from Oil Dry Air Dry Oil Time
Pressure Swing Adsorption Dryer Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ] x H 2 O - 10 Angstrom Molecular Sieve
Dry Air Blanket Keeping Oil in Contact With Very Dry Air Head Space Air Relative Humidity (%) 80 70 60 50 40 30 20 10 0 Reservoir Head Space Air 20 200 6 2 Exchanges/hour 0 8 16 24 Tim e (Hours) Oil Percent Saturation (%) 80 70 60 50 40 30 20 10 0 Reservoir Oil 6 20 200 0.0 8.0 16.0 24.0 Time (Hours) 2
Best Practices Total Contamination Control Plan 1) Design 2) Roll-Off Cleanliness 3) Transportation 4) On-Site Storage 5) Clean Maintenance Practices 6) Ingression Prevention 7) Rapid Removal
Best Practices For Ingression Prevention & Rapid Removal Regenerable Breather Dryer with 3 Micron Filter Dry Air System Cooler Inline Filter β 5(c) =1000 Gearbox Offline Water Absorption Filter Offline Filter β 3(c) =1000 Objectives: ISO 14/12/10. 125 ppm max
Bearing Life Factors 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NASA/STLE Roller Bearing Life Factors for Wind Turbines 2um 5 um 8 um 10 um 12 um 0 5 10 15 20 25 30 35 40 Filter Rating Where (C) = 1000 (Microns) Adapted from Needelman & Zaretsky, STLE Annual Mtg. Proc. May 09
NASA/STLE Model Water Contamination & Bearing Life 7.0 Relative Bearing Life 6.0 5.0 4.0 3.0 2.0 1.0 Target Maintaining Dry Oil Estimated To Increase Bearing Life ~200% Current 0.0 0 100 200 300 400 500 600 Water (ppm)
Conclusions Benefits Of Excellent Contam Control Greater Gearbox Reliability More Uptime, More Production Extended Warrantees Up To 5 Year Gear Oil Life Needed Coherent Contamination Control Plan Use Best Technologies & Practices
Thank You For Your Interest Questions? Comments?