JUNE/JULY 2013 | £5.25 - Wind Energy Network

LubricantsLubricantsHelping operators optimisepower output in harshenvironmentsIn the previous issue Rob Pears,ExxonMobil Fuels & Lubricantsdiscussed viable solutions to addresscommon gearbox performanceconcerns. In this issue, Rob continuesto share best practice insightswith wind turbine operators, witha particular focus on maintainingoptimum wind turbine productivityin the face of particularly harshenvironments, such as thoseencountered offshore.Proper gearbox lubrication is essential formaximising wind turbine performance.However, as technology has evolved theburden on lubricants has grown. Becausetoday’s gearboxes must support heavierloads than ever before, operators arelooking for lubricants that can successfullyminimise wear and provide extended drainintervals.Q1: What are some of theconsiderations that go intolubricating a wind turbinegearbox?A1: Wind turbine gearboxes have uniquelubrication needs compared to otherindustrial sectors. As well as addressingthe standard needs of high load bearinggearbox components, we must alsoconsider the stresses a gearbox enduresin this particular application.Standing hundreds of feet high offshore,and often situated in remote locations,wind turbines operate in wide temperatureranges and are vulnerable to wear,water contamination, rust and corrosion.Furthermore, their hard-to-reach locationscan make routine maintenance visits verycostly. Therefore, any in-service lubricantsmust last as long as possible and offersufficient equipment protection to avoidunscheduled downtime.Q2: How has wind turbinelubrication changed over time?A2: In the past, gearbox lubricant changeswere typically carried out every 18 monthsfor mineral gear oils and every 3 years forsynthetic alternatives.Today, as gearbox technology has vastlyimproved, wind turbine operators aredemanding enhanced performance fromtheir lubricants. Extended drain intervalsare of particular concern, as a complete“drain-flush-fill” cost can exceed $5,000(USD) for a MW mid-range sized turbinefor the lubricant alone.The total cost is further compoundedby other overheads such as labour,production downtime, equipment repairand the prohibitively high cost of vesselhire for offshore installations.So, not only must wind turbine gearboxlubricants provide protection from theelements, but to meet the expectationof operators, they have to do so foran exceptionally long period of time tokeep costs down. Some operators arelooking for lubricants that deliver oil drainintervals of up to and beyond five years.Regular use of an used oil analysis,such as ExxonMobil’s Signum, enablesmaintenance professionals to monitorthe condition of the equipment and thelubricant to increase oil drain intervals.Q3: Is it a challenge to meetthese elevated performancestandards?A3: It can be challenging. But, atExxonMobil, we are well-equippedto handle this challenge through ourtechnology leadership and applicationexpertise in the wind sector. Thanks toour scientifically engineered approachto product development, excellentindustry insight and technical knowhowwe have been able to deliver highperformance lubricants, optimised forindividual applications. We refer to thisas “ExxonMobil’s Balanced FormulationApproach.”No matter what sector we are workingin or what specific performancecharacteristics the product requires, thisprocess enables us to develop lubricantsthat deliver exceptional performanceacross all critical areas—such as oxidativestability, component wear protection,corrosion control, filterability, watertolerance, shear stability and extremetemperatureperformance.The balanced formulation approachis a two-fold concept. First, our teamof scientists evaluates the lubricantdesign in a series of stringent laboratorytests to determine its performancecapabilities. Then, we take our lubricantcandidate out into the field and conducta full-scale, dynamic testing on actualindustrial equipment. A product hasto excel in both tests before it receivesthe ExxonMobil seal of approval. Forwind turbine gearboxes, we recommendMobilgear SHC XMP 320.Q4: What are the characteristicsof Mobilgear SHC XMP 320 thatmake it an excellent productfor wind turbine gearboxes?A4: We work in close co-operation withthe Original Equipment Manufacturersworldwide to formulate superior lubricanttechnology that addresses operationalchallenges encountered in the mostharsh environments such as theoffshore energy sector.A case in point, Mobilgear SHC XMP 320is designed to provide optimumequipment protection andextend the oil life even underthe extreme conditions windturbines endure.This high performance gearoil is now being used to protectmore than 40,000 wind turbinegearboxes worldwide.Rob PearsExxonMobil Fuels &Lubricantswww.exxonmobil.co.ukClick to view more info82 www.windenergynetwork.co.ukwww.windenergynetwork.co.uk 83