HOBAS Sand Trap

Reliable Separation of Solids in Small Hydropower Plants

The sand trap is a key component for removing solids in small hydropower systems. After large stones and woody debris are held back by a screen at the weir, the sand trap separates smaller solids such as gravel, sand, and silt from the river water. It thereby prevents sedimentary deposits from building up in the penstock. This in turn, extends the hydropower plant’s operating time and maintenance intervals, protects the turbine from excessive wear, and increases the facility’s service life.

HOBAS has developed a particularly effective, prefabricated sand trap which is built of glass fiber reinforced pipes. Thanks to the modular system and low weight, the HOBAS Sand Trap is transported to the installation site and integrated into the power plant system very easily. A flushing unit, which can be fully automated on request, reliably cleans the sand trap from separated solids.

How the HOBAS Sand Trap works:

The coarsely cleaned river water enters the sand trap through an inlet pipe. Due to the stilling chamber's cross-sectional enlargement, the water flow velocity decreases and turbulences in the flow are reduced. Vertical stilling slats help stabilize the water flow. In the settling chamber, the solids sink down into the sedimentation system and are then rinsed out of the sand trap through a flushing pipe, which can be opened for this purpose. Special sensors to automate the flushing can be integrated on request. During the flushing process, the turbine remains in operation, ensuring continuous power generation and maximal plant exploitation.

The The efficiency of the settling system and flushing function of the HOBAS Sand Trap have been proven and verified by means of a numerical simulation model at the ČVUT Prague (Czech Technical University in Prague) and a hydraulic model at the BOKU Vienna (University of Natural Resources and Life Sciences in Vienna).

Each HOBAS Sand Trap is tailored to the given requirements with regard to numerous factors including the solids’ size and settling times as well as the inlet flow velocity. This guarantees best possible settling and flushing performance and optimized long-term performance of the hydropower plant.

Advantages of the HOBAS Sand Trap:

  • Reliable separation of solids
  • Effective flushing system for the safe removal of sediments from the sand trap
  • Unhindered operation of the turbine during the flushing process
  • Easy mounting thanks to prefabricated units
  • Little space and excavation required during installation
  • Individual design for optimal performance
  • Easy handling thanks to low weight
  • Installation in remote areas possible

For technical details, possible designs and information regarding installation please contact your HOBAS Sales Representative.