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hSand Trapfor Small Hydropower Plants


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he sand trap is a key component for removing solids in small hydro-

ower systems. After large stones and woody debris are held back by acreen at the weir, the sand trap separates smaller solids such as gravel,

and and silt from the river water. It thereby prevents sedimentary depos-

s from building up in the penstock. This, in turn, extends the hydropowerants operating time and maintenance intervals, protects the turbine

om excessive wear and increases the facilitys service life.

OBAS has developed a particularly effective, prefabricated sand traphich is built out of glass ber reinforced pipes. Thanks to the precast

nits and low weight, the HOBAS Sand Trap is transported to the installa-on site and integrated into the power plant system very easily. A ushingnit, which can be fully automated on request, reliably cleans the sand

ap from separated solids.

6 Flushing Pipe (automatable)The solids are then rinsed out of the sand trapthrough a ushing pipe that is opened for thispurpose. On request, special sensors are inte-

grated to control the ushing automatically. Theturbine does not need to be turned off during

the ushing process. This ensures the continousgeneration of hydroelectric energy.

9 Outlet Pipe to PenstockThe cleaned river water exits the sand trap

through an outlet pipe which is connected to thepenstock. The penstock then conveys the water

to the power house.

1 Inlet PipeAfter the river water has passed the screen andis thereby cleaned of large solids, it enters the

sand trap through an inlet pipe.

3 Stilling SlatsThe settling of solids is increased by factory-mounted vertical slats. They calm turbulence

in the ow, especially that perpendicular to thedirection of ow.

hSand Trap

Reliable Separation of Solids at SmallHydropower Plants

5 Sedimentation SystemThe particles collect in the sedimentation sys-

tem inside the settling chamber. The HOBASSand Trap is designed in a way to prevent the

settled solids from being stirred up and re-intro-

duced into the water very effectively.

7 Inspection OpeningThe sand trap can be accessed through afactory-mounted HOBAS GRP Inspection Man-

hole that is equipped with a manhole cover. Theaccessibility of sand traps with larger structural

lengths can be improved by means of additional

manholes.

2 Stilling ChamberA cross-sectional enlargement in the rst part ofthe sand trap reduces the ow velocity consider-ably. This way, solids can subsequently settle.

4 Settling ChamberAs an effect of the water's reduced ow veloci-ty, the solids sink down to the bottom of the

settling chamber, right into the integrated sedi-

mentation system.

AdvantageshSand Trap

OReliable separationof solids

OEffective ushing systemfor the safe removal

of sediments from the sand trap

OUnhindered operation of the turbine duringthe ushing processOEasy mountingthanks to prefabricated units

OLittle space and excavation requiredduringinstallation

OIndividual designfor optimal performance

OEasy handling thanks to low weight

OInstallation in remote areas possible

ow the HOBAS Sand Trap works

he coarsely cleaned river water enters the sandap through an inlet pipe. Due to the stilling

hamber's cross-sectional enlargement, the wa-

er ow velocity decreases and turbulence in theow is reduced. Vertical stilling slats aid the wa -er ow stabilization. In the settling chamber, theolids sink down into the sedimentation system

nd are then rinsed out of the sand trap throughushing pipe, which can be opened for thisurpose. Special sensors to automate theushing can be integrated on request. Duringe ushing process, the turbine continues to

perate unhindered, ensuring continuous powereneration and maximal plant exploitation.

he optimal settling system and the efcientushing function of the HOBAS Sand Trap have

een proven and veried by means of a numeri -al simulation model at the VUT Prague (Czechechnical University in Prague) and a hydraulicodel at the BOKU Vienna (University of Naturalesources and Life Sciences in Vienna).

ach HOBAS Sand Trap is custom-tailored toe given requirements with regard to numer-

us factors, including the solids size and settlingmes as well as the inlet ow velocity of theater. This guarantees the best possible settling

nd ushing performance of the sand trap andn optimal long-term performance of the hydro-

ower plant.

8 Overow PlateA tilted overow plate at the end of the sand trap

ensures that the suction of the outlet pipe can-

not rinse out the settled solids into the penstock.


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No part of this document may be reproduced or utilized in any form or by any means without our prior written permission. All information in the document

is correct at the time of going to press. However, we reserve the right to make changes without notice, in particular to technical data. The data given is not

binding and must therefore be checked in each individual case and revised as appropriate.

EGroup Worldwide

HOBAS manufactures and markets HOBAS GRP Pipe

Systems. The HOBAS Network includes HOBAS Production

Facilities and Sales Organizations in Europe and throughout

the world.

EEngineering Austria

Pischeldorfer Strasse 128

9020 Klagenfurt | Austria

T +43.463.48 24 24 | F +43.463.48 21 21

[email protected] | www.hobas.com

Publication: 09/2013

When developing and manufacturing HOBAS Products, we are dedicated to

conserving resources and respecting the environment. Visit our website tond out more about the HOBAS Environmental Policy.

hobas sand trap e

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