1 a new concept for lifting spillway gates bryan leyland msc, fiee, fimeche, fipenz consulting...
TRANSCRIPT
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A new concept for lifting
spillway gates
Bryan Leyland MSc, FIEE, FIMechE, FIPENZ Consulting Engineer
New Zealand
www.bryanleyland.co.nz
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“I believe that spillway gates should have a
backup operating system that does not
need an external power supply or
human intervention”
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The systemEach gate has two independent sets of hydraulic rams in a novel configuration
One set is powered by a conventional hydraulic system with electric pumps
The backup set is powered by a pump driven by a water turbine
If the lake level is too high, water overtops a weir and drives the turbine
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Background•Something like 30% of dam failures are caused by spillway gates failing to open*
•Dams have failed in less than a 10 year flood because all the gates failed to open
•Most modern gates are lifted by hydraulic rams
•Emergency backup operation usually involves manual intervention and, in many cases, manual lifting
• *Prof Raymond Lafitte
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How many strong men do you need to raise a 30 tonne gate?
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Typical conventional lifting gear
Masjed es Soleyman, Iran
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Typical pumping unitClyde Dam, New Zealand
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So what is wrong with current practice?
•Totally reliant on the integrity of a pair of tension cylinders and associated hydraulic system
If one cylinder fails, most gates fail to open
Must have one or more backup power supplies
•Cylinder and hydraulics are expensive
>$1 m for a large gate
Cylinders can have 15 - 20 m stroke
>$300,000 each
•Does not have 100% independent backup8
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The New Concept•Duplicated rams and independent hydraulicsProvides 100% backupBackup system operated directly by water level
a system proven in New ZealandUses low cost “push” rams instead of expensive
tension cylindersany good machine shop can make them
Does not require a mass of concrete to carry ram pivotCost saving of 25% - 50%
•Lower cost - higher reliability!
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Patea Gates NZ 2 - 10 x 10mUse a single push ram
Simpler and cheaper thanthan 2 tension cylinders
Water turbine backup
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Godwin “Bootstrap” gate at Yarrawonga
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ChainWheel
Ram
Ram and lifting chainProof of concept
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New Concept gate ram
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Gate closed andopen
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Gate closed and open
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Suitable Pelton Turbine to drive pump
Made by Eco-Inn in New Zealand
Cost ~$500
~1 kW max
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Other applications
Backup system can be used as sole lifting system for small or less critical gates
Same system can be used to raise vertical lift gates
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SummaryThe only system that provides 100% independent backup
Backup system
operated directly by water level
completely independent units
Uses low cost “push” rams instead of expensive tension cylinders
any good machine shop can make them
One AC hydraulic pumping unit can serve several gates
• Lower cost: better reliability!