Hydroelectric power is an environmentally friendly, reliable and flexible source of electricity used around the globe since the late 19th century.
The Tesla Hydroelectric Facility is located on a mountainside near Colorado Springs (USA), was constructed in the early 1990s and its Pelton turbine has been in service since 1997. The facility encompasses an Energy Dissipating Structure (EDS) which is used as a bypass when the hydroelectric power plant is offline and must dissipate 750 psi of head from the upstream reservoir, after which the water can flow by gravity to the water treatment plant located downstream.
The EDS was originally equipped with 36” vertical sleeve valves in concrete stilling wells. These valves experienced extreme cavitation at the nozzles under normal operation. Several attempts by the manufacturer to improve performance by repairing and retrofitting these experimental sleeve valves were unsuccessful. In 2010-2012 the owner proceeded with the purchase and installation of 36” plunger valves as a replacement for the sleeve valves, in an effort to improve the reliability and service life of the EDS facility. The plunger valves required various modifications by the manufacturer to function as intended, yet the operational problems persisted. Severe cavitation, extreme vibrations affecting the EDS structure, and jet-engine noise levels of up to 130 dB(A) occurred during operation due to inadequate valve design, which also led to repeated serious functional issues. Ultimately one of the plunger valves failed during operation which created a serious safety issue.
Due to the criticality of the Tesla EDS for the local water supply system, and previous relevant experience at other hydro plants, Mokveld was selected to develop a customized replacement that would fit in the existing piping and solve the problem. We accepted the challenge, analyzed the application with all parameters and supplied a highly engineered and optimized 36” anti-cavitation axial control valve in late 2019, well in advance of the scheduled delivery date and in ideal coordination with the contractor’s fast-track project schedule. It was imperative that the installation had to be carried out prior to the plant maintenance shutdown so that the bypass line with the new valve could fulfill its task. On-time delivery was therefore of great importance for the continuity of drinking water supply to thousands of residents via the treatment plant which relies on the safe and consistent operation of the EDS.
The valve was commissioned in December 2019. Typically the bypass is operated for a few weeks per year when the turbine is offline for annual maintenance. In this project the need was extended to a period of 2-3 months since the plant required a major refurbishment. However, due to the Covid-19 pandemic the work was delayed and the bypass actually had to be in use for almost 5 months.
Mokveld’s innovative solution passed this ultimate test with flying colors: In June 2020, after the work was completed and the hydroelectric plant was back online, the valve was removed for inspection and no signs of cavitation, wear or erosion were found.
With this tailor-made advanced solution, a reliable operation of the Tesla Energy Dissipating Structure was successfully implemented. Mokveld’s unsurpassed zero-cavitation trim technology and streamlined axial flow eliminates cavitation and vibrations, providing maximum availability and peace of mind for many years to come!
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In order to ensure you continue to benefit from valves that offer high capacity and safety as standard, we offer a range of modernisation services. For more information about our modernisation services, please contact your Mokveld support office or representative.