Newsletter nr. 5 - New hydropower plant

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SUPPLY OF #6 TURBINE INLET SPHERICAL VALVE (DN800 PN31) During year 2011, Vortex Hydra was contacted from a Guatemalan private Company for a project of a new Hydropower plant in Guatemala with 6 identical Pelton Turbines (supplied from Tecnomecanica de Guatemala, S.A. see photo below). Vortex Hydra has supplied during year 2012 the #6 turbine inlet spherical Valves (DN800 PN31) with all the pertinent accessories, such as upstream pipe, dismantling joint, by-pass, seals' control panel (see Drawing at side). These valves are used in the hydroelectric power plant as turbine protection to guarantee the emergency shut-off of the pressurized water flow of the penstock. They are placed immediately before the turbines and they work automatically to shut-off the water flow in case of any turbine malfunction, lack of power or any other specified condition. The shutter is actuated by hydraulic cylinders moving it from the completely opened position to the completely closed position by rotating of 90° on side trunnions. The valve in the open position has a fluid way which is essentially shaped as a straight cylinder with approximately the same head losses as would occur in an equivalent length of pipe.


In order to guarantee the fast closure of the valve in lack of power, a suitable counterweight is installed on the shutter arm. Once the shutter is closed, the perfect water tightness is guaranteed by the Main Operational Seal (downstream of the valve) when the mobile sealing ring, housed in the valve’s body, closes against the fixed sealing ring, bolted to the shutter (both rings are made of stainless steel with different grade of hardness). In case maintenance is necessary on the Main Operational Seal, in the upstream side of the valve is installed the Maintenance Seal with the same concept and functionality, in this way the downstream part of the valve is completely independent and it becomes possible to operate without dewatering the penstock. Furthermore, it is also a redundant safety for all the other maintenance operations where both seal systems can be used simultaneously. Both Seal Systems are operated by means of the penstock’s pressurized water through a dedicated seals control panel.


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