Automatic flushing of sand traps to make them more efficient

Goal

To develop, test and market an automatic sand trap flushing system, in order to increase the long-term productivity of hydroelectric turbines.

Partners

Stahleinbau und Maschinen AG, HES-SO Valais-Wallis (Institute of Systems Engineering), EPFL (Hydraulic constructions laboratory), The Ark Foundation

Stahleinbau und Maschinen SA has been based at Ackersand/Stalden, in the Upper Valais, since its creation in 1956. In its early days, the company was concerned with steel structures and supplying equipment for tunnels and excavation work.

Through partnerships with Von Roll AG and ABB, it has diversified its activities, which now include the manufacture of equipment for the rail transport and hydroelectric industries. Its products are exported worldwide.

Content of the project

The innovation project developed in partnership with The Ark concerns the design of a new automatic flushing system for sand traps. A sand trap is an essential component of every water intake, whether the water is for hydroelectric power generation, irrigation of vineyards, or drinking. Its purpose is to remove a large part of the sand carried along by the water, before that water reaches a turbine or irrigation network. Although most people are aware of the impact of sand in drinking water or irrigation water, its devastating effect on hydroelectricity generation equipment is less well-known. Sand is a powerful abrasive and it erodes the vanes of a turbine wheel in no time. Catching the sand in a sand trap increases the lifespan of the equipment, and therefore its productivity.

The sand or other organic matter (wood, leaves, etc.) must be flushed from the sand trap regularly. This cleaning is currently performed manually and covers the whole sand trap. The Ark’s project was launched in order to implement an automatic flushing system, controlled remotely via sensors. The aim was to minimise not only the water wasted when the equipment was flushed but also the maintenance costs. Flushing the trap a portion at a time also reduces variations in the water level so that it does not rise suddenly.

Practical outcomes

Stahleinbau und Maschinen AG has been able to develop an innovative flushing system that combines aspects of an old design of sand trap, dating from the 1950s, with the latest approaches and technology. Computer simulations of the flow have been carried out by the HES-SO Valais-Wallis and EPFL, the other partners in the project.

This project has enabled the experience and competences of each partner to be combined to best advantage, in order to develop a new flushing system that offers several innovative advantages (efficiency and safety of operation) whilst being cost-effective. The project team is now ready to implement it on a real-life scale.