Hydraulic machinery | The Authors misure2 [Istantaneo]
60 50 40 30 20 10
8 16 31.5 63
Above: Figure 8: New distributor final noise measurement in most exposed private house
125 250 500 1 k 2 k 4 k 8 k 16 k
valve whose oil servomotor is directly connected to the distributor servomotor. Consequently, the new distributor configuration had to be fully compatible with the existing relief valve system.
Bibliography
Den Hartog – Mechanical vibration – McGraw-Hill Book Company, Inc. 1956
P.Caretti,
S.Cartapani,
L.Papetti – Penstock resonance due to RSI pressure pulsations on Francis turbines: a case study in a revamped plant – Graz- Hydro 2024
P.Caretti,
A.Cannata,
A.Prato – Mompantero anni 1938-2018. Perchè le turbine Francis possono fare “cantare” le condotte forzate – Padova – Hydromatters 2019
Techydro undertook the design of the new distributor assembly, carefully minimizing the impact on existing turbine components. At the same time, additional enhancements were implemented, including: A redesigned shaft seal arrangement to reduce water leakage; enlarged relief pipes to minimize axial thrust by improving seal flow control; and upstream covers split into two parts to facilitate maintenance and dismantling. Comparative drawings (Figure 7) illustrate the differences between the new 24-wicket gate configuration and the previous 16-gate design.
By optimizing the linkage dimensions and verifying
Below: Figure 9: Generator DE bearing vibration spectra with new distributor
the resulting loads, it was possible to retain the existing servomotor without modification. Commissioning of the unit confirmed not only proper turbine operation but also validated the numerical analysis results. Notably, it eliminated vibration excitation in the penstock, thus preventing tonal effects. This is supported by noise measurements taken during the day at the most exposed nearby residence, showing a level of Leq = 49.6 dB(A), with corresponding spectra (Figure 8). Furthermore, vibration spectra from the DE bearing at full power (5.5 MW) showed that the RSI pressure pulsation component at 283.4 Hz was entirely eliminated (Figure 9). Transient tests validated the proper functioning of the new distributor in conjunction with the existing relief valve. These tests also determined the optimal final stroke of the distributor servomotor, which was set at 65% to precisely deliver the concession flow of 3.00 m3
/sec.
Paolo Caretti graduated in 1987 in mechanical engineering at the Politecnico of Milano. In 1991 joined Riva Hydroart (from 1993 Voith Hydro Milano) working as hydraulic and mechanical engineer in engineering dept. In February 2016 he started up his own hydro-mechanical activity (HMSS of Paolo Caretti) and operate as a consultant on hydro machinery.
Andrea Cannata graduated at the Politecnico of Milano in mechanical engineering in 2008. In 2009 joined Enel Produzione, from 2013 to 2017 head of Verampio and Pallanzeno Hydro power plants (7 HPP, ~330MW in Toce basin), then from 2017 to 2024 head of Northern Western Area Maintenance (110 HPP, ~2.700 MW in Piedmont Region). Nowadays head of HPP commissioning unit of O&M Hydro Italy. Author of several publications about hydroelectric industrial history and technical publications.
Adalberto Bramati graduated in 1976 in mechanical engineering at the Politecnico of Milan. In 1977 joined Hydroart (then Voith Riva Hydro), Milan, and in 1992 became Director of the Technical Office and in 1999 member of the Management Committee of the Voith Group. Since 2001 he started up as Managing Director and Technical Manager of Techydro S.r.l., Vimercate (MB):
Fulvio Ferrari graduated in 1978 in mechanical engineering at the University of Genoa. From 1980 to 2001worked in the R&D and in the Technical Dept. of Hydroart (then Voith Riva Hydro), Milan. From 2002 to 2019 worked as Technical and Quality Manager at Pompe Cucchi S.r.l. (gear pumps), Opera (MI). Since 2020 collaborates with Techydro S.r.l., Vimercate (MB).
[1] 18.10.2024 - 10:59:34 0.4 0.3 0.2 0.1 0 0 200 Hz 400
Marco Lauro graduated in 1989 in Mechanical engineering at Università di Genova. From September 1990 to June 1992 in charge to Aeritalia, now Alenia, Space Division as technician for scientific satellites. From 1992 to 2010 technical expert and internal reference for O&M technical support. From 2011 to 30/12/2015 within GLOBAL GENERATION – Hydro Technical Line. Then Head of Genova Coal Thermal Power Plant. From 30/09/2017 within O&M Hydro as technical support manager for Enel worldwide hydro power plants
Diego Giors graduated from ITIS Enzo Ferrari in 2004, from 2007 to 2019 he was a technical assistant at Enel Green Power as a technical employee of the Operating Unit operating in Val di Susa. From 2019 to today in Enel Green Power spa - O&M Hydro. Within the Hydro Technology Line, he is responsible for the Venaus Operating Unit with a fleet of 12 plants and 15 generating units and 3 large dams.
28 | June 2025 |
www.waterpowermagazine.com
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