Slick operations4 December 2011
Lubricants can play an important role in the efficient operation and construction of hydropower plants. Shell illustrates how some of its products have proved their worth at projects worldwide
Shell Lubricants has launched a new, improved range of Shell Gadus greases. Designed to meet the challenges of operational equipment in some of the most extreme conditions, the new grease is being put to good use by Hydro Tasmania in Australia.
Generating over 80% of Tasmania’s electricity needs and providing peak load electricity to the Australian mainland via a sub-sea transmission line, Hydro Tasmania operates 30 hydropower stations across six high rainfall water catchments in Tasmania. At some of these power stations the hydro turbines are located 180m below water level where the Shell greases have been developed for lubrication in wet conditions.
Grease in this environment must provide a low friction surface. This will allow for smooth turbine operation and resist water wash-out caused by the high volume and velocity feed water coming down from the power stations which range from one of the smallest (Nieterana mini hydro plant at just 2.2MW) up to the 432MW capacity Gordon station.
Nieterana uses a horizontal Francis turbine with a flow of approximately 8.5m3/sec. The Gordon station is located 183m underground and is supplied with water from Lake Gordon through a 137m high vertical shaft, connected to three Francis turbines. The Gordon turbines consume approximately 83m3/sec at full load, with a head up to 192m.
Gadus S2 V220AC is an extreme-pressure, red multipurpose grease for wet environments, used to lubricate bearings of the control systems of the turbine and water inlet gate valves. It is a grease relied upon to provide good wear protection and bearing life for moderate to high speed bearings and is reported to have outstanding mechanical stability in the presence of water. As part of the Shell Gadus range it also offers the reliability, long life span and superior performance required for the latest generation of power equipment.
Gadus S2 V220AC has been designed to protect equipment from wear and tear and can help increase service life by providing:
• Protection from bearings: it passes the four-ball weld test at 315kg. This exceeds the 250kg minimum weld load that a grease must pass to be classified as having good load carrying properties (ISO 6743-9).
• Good corrosion protection: it achieves a rating of 3 in synthetic water bearing corrosion tests. (A rating of 0 represents no visible corrosion and 5 indicates more than 10% corrosion).
• Over 100 hours of bearing life at 120oC.
• Good mechanical stability in the presence of water.
In April 2011 Shell announced the launch of its new improved portfolio of industrial lubricants and greases. The result of a three-year process, the new portfolio has been restructured and refreshed to help customers select the right level of protection for their equipment.
Amarpreet Singh at Shell Lubricants explains: ‘Shell Gadus is the new unifying name for Shell greases, creating one of the largest global grease brands. The range of products has been developed to deliver value through enhanced wear protection, long grease life and increased system efficiency.’
Shell’s international research and development team has worked in close co-operation with customers and equipment makers to create new greases that come with quality assurance. The company says that they are designed to outperform conventional greases by combining a wide range of thickener technologies which keep the grease in place under different conditions. In addition innovative oils provide efficient lubrication and protection. Shell’s expertise also combines the cost savings available from the wide range of the company’s products, and offers reliable global supplies. The company states that its stringent quality control processes ensure that every batch, no matter where in the world, gives the same high performance level.
‘Research into the way our customers choose and use lubricants revealed that they often find the array of choices confusing and complex. While recognising the importance of the correct lubricant choice and application, they also welcomed changes that would make the process simpler,’ said Craig Schneider, Vice President of Marketing for Shell North America. ‘With this in mind we have redesigned our range of industrial lubricants, removing products with overlapping applications – or whose technology had been replaced by more advanced formulae – while improving choice by selectively adding speciality and synthetic products.’
As part of this new portfolio, Shell Gadus has made it simpler for customers to compare product benefits and performance while taking into account other variables such as compatible thickeners, base oil viscosity, National Lubricating Grease Institute grade and any other special performance characteristics that make a grease suited for a specific or unique customer challenge. To aid the selection process, the range is based around key tiers, each offering increasing levels of performance and protection, including: Entry, Mainline, Premium and Advanced, which uses the latest synthetic, high-performance technology.
Also listed among Shell’s hydro customers is Brazilian-based construction company Consorcio Camargo Correa. While excavating river stone during the recent construction of a Venezuelan dam, water contamination was causing rapid wear on the bucket pins and bushes of Consorcio’s excavation machines.
Water resistance became increasingly critical to ensure a reduction in operation costs. The company’s heavy machinery was being exposed to water while extracting the stone to crush for concrete. These conditions watered down the existing lubricant very quickly resulting in the need to replace bucket pins and bushes every 250 hours. As maintenance costs and unscheduled down time spiralled, a lubricant with water resistant components was critical.
Shell recommended its Albida HDX2 which is a high performance, extreme pressure multipurpose grease, with strong water resistance. The use of this helped to achieve a number of positive results for the dam project, including:
• An extension in excavator component life from 250 to 350hrs.
• An increase in productivity due to the availability of equipment.
• A reduction in maintenance and labour costs to change components.
• A reduction in unscheduled downtime.
Indeed an estimated 28% reduction in operational costs was achieved which was calculated as an annual saving of US$3.8M.
Another hydro customer also reported savings of approximately US$72,000. A pumped storage operator was experiencing an increase in turbine bearing temperatures which was causing serious wear and production outages. Poor bearing design was recognised as the cause of the problem but Shell was asked whether lubrication support could help to resolve the issue.
After a thorough inspection and an assessment, Shell recommended using its Turbo GT46 turbine oil. The operator reported savings of US$72,000 in avoided downtime. The plant also experienced an immediate 8oC decrease in thrust bearing temperatures which gave the company time to work on an engineering solution.