Hydroelectric power plants



Duplomatic has traditionally been involved in the renewable energy sector.

After the applications made in geothermal energy dating back to the early 90s, Duplomatic has supplied hydraulic components and systems in the hydroelectric sector for the refurbishment or installation of new water plants.

It should be borne in mind that in Italy the number of installed power plants is around 4400 units for a production of about 50 terawatt hours and the power plants are present in all regions. Hydroelectricity generates more than 40% of energy produced from renewables.

Hydraulic turbines are divided into 3 broad categories which are named after their inventors:

- the Kaplan turbine is used in the presence of a low hydraulic head (less than 20 meters), but with a high water flow rate. The fluid reaches the turbine through a spiral duct and a fixed distributor that gives the water a swirling rotation that generates the motion of the impeller. By orienting the impeller blades it is possible to optimize the rotation speed according to the different flow rates while maintaining a high efficiency (around 90%). The blades are adjusted hydraulically with servo-actuators controlled in closed position loop, controlled by proportional feedback valves.

- The Francis turbine is used when the hydraulic jump is around 150 meters with a water flow rate that is not excessive. This type of turbine has only one adjustment: the distributor blades. In the Francis turbine, the water reaches the impeller through a spiral duct and a distributor directs the flow towards the blades of the impeller itself. The turbine is adjusted by varying the angle of incidence of the blades in the distributor and this function is achieved with hydraulic servo-actuators controlled by proportional valves.

- The Pelton turbine is installed in locations that can exploit a high water head with modest water flow rates, generally less than 10 m³ / sec. The turbine has a wheel with spoon-shaped blades applied and is rotated by the water jet controlled by servo-actuators that operate in a closed position loop. Closed-loop control of the plugs (which act as chokes) and the tiles (which partially divert the water flow) is carried out with the use of proportional valves with integrated electronics.

Hydraulics at the service of water plants are not limited to proportional drives; it is in fact important to emphasize the safety required by this type of systems which very often operate without the help of on-site personnel. There are therefore accumulation groups capable of supplying the safety phase of the system in the event of pump stoppage and low leakage valves for the activation of the input valves in the turbine and for the activation of the by-pass. Always bearing in mind the need to redundant the most critical and essential components for the proper functioning of the system.



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