SUBMERGED WATER INTAKE, FISH-FRIENDLY (SWIFF) SCREENS
PURPOSE
Water intake systems using traditional travelling band screens are often faced with the problem of debris carry-over and marine life mortality as a result of fish impingement and entrainment on the screen. They are not well suited for water-life recovery and return. Often, these screens can be difficult to retrofit with fish-saving technologies. The BEAUDREY SWIFF screen has been developed to overcome these problems and can be considered as an alternative technology to traditional travelling band screens.
The BEAUDREY-patented “SWIFF” screen (Submerged Water Intake, Fish-Friendly Screen) is designed to protect all forms of water-life (fish, eels, etc.). It is thus particularly suited where fish-protection is mandatory. It is however also a solution where the maintenance of all other types of screening machines is costly.
It is particularly adapted where water approach velocity requirements are low.
DESCRIPTION
The SWIFF screen is a horizontal cylindrical drum-shaped structure the surface of which consists of a screening element divided into deep compartments.
Life-forms are collected in the deep compartments of the submerged cylinder’s external surface. As the drum rotates, each compartment passes in front of the backwash suction scoop which removes the debris by reversing the flow through the mesh.
Suction is created by a special fish and eel-friendly pump that sends the fish, eels and debris back to the sea or river via pipelines.
The screen normally rotates at low speed with the pump in service and switches to high speed if, in spite of the low-speed rotation, the head-loss continues to rise.
The screen is designed to be lifted up using an existing overhead crane. It is then locked into position on deck and all the items requiring maintenance are fully accessible from the deck.
Reverse rotation is provided should large debris block the SWIFF screen’s operation.
It is easy to operate and maintain, all equipment can be lifted out of the water in four hours or less for inspection. It has fewer moving parts than a traditional travelling band screen which allows for easier, less frequent and lower-cost maintenance, and also allows it to hold up in continuous operation.
The SWIFF screen has been designed to minimize the time a fish is in contact with the screen. The rotating screening wheel can be completely cleared in one minute.
The SWIFF screen is specially adapted to all sites where water approach velocity requirements are low.
APPLICATION
Fossil and nuclear power plants, chemical plants, desalination plants, manufacturing plants, refineries, irrigation.
ADVANTAGES
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Can be retrofitted in any existing screening plant with no alterations to civil works
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Can be retrofitted to replace almost any type of existing water screen without changing approach velocity and screening surface
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Easy to install and remove
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Uses backwash pumps especially designed to protect fish and eels
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Totally submerged system which ensures water-life is never removed from the water
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Fully-submerged screen element held between two vertical wall-plates
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The surface of the screening element is divided into deep compartments
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Reverse rotation in case of large debris-induced blockage
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Can be designed with several pumps for redundant applications
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Main shaft rotation ensured by ball bearings protected by a mechanical sealing device similar to submerged pumps
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Fully customizable
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No debris carry-over
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Resistant to high H2O pressure differentials
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Installed with NOCLING™ anti-fiber screening panels for water with high fibrous content (screening sieve available)
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Easy to operate and maintain; all equipment can be lifted out of the water in three hours or less for inspection.
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Fewer moving parts than a traditional travelling band screen allows for easier, less frequent and lower-cost maintenance
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Slid into wall guides, it can easily be lifted out for maintenance without dewatering the pit.
MATERIALS
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Wall-plates
Painted carbon steel or stainless steel (AISI 304L, AISI 316L, duplex or super-duplex stainless steel). -
Cylindrical screening structure
AISI 304L, AISI 316L stainless steel, duplex or super-duplex stainless steel, composite materials -
Screening medium
Stainless steel mesh, composite screening medium,
Stainless steel wedge-wire elements, AISI 316L, duplex or super-duplex stainless steel -
Nuts and bolts:
Duplex or super-duplex stainless steel
Other materials are available upon request.
SIZES
The following table gives SWIFF SCREEN sizes for :
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1x1 mm to 2x2 mm mesh aperture
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0,15 m/s approach velocity
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Outlet velocity limited to 1,1 m/s (Outlet water velocity can be increased according to site's main pump )
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Module limited to 1,5 can be increased to 1,6
