1. Project Background
Located deep within the Rhône Valley in the Canton of Valais, Switzerland, this medium-sized run-of-river hydropower station was originally constructed in the 1980s. With changing hydrological conditions caused by Alpine snowmelt and the ongoing modernization of the plant’s automation systems, the existing cooling water circulation system began facing significant challenges. The old pump suffered from declining efficiency and was highly susceptible to cavitation and vibration during low-water-level operation in dry seasons.
As part of the station’s auxiliary equipment modernization program, the project team planned to replace the aging unit with a new vertical long shaft pump. Due to Switzerland’s specific power supply standard (400V/50Hz), limited installation space, and the customer’s stringent requirements for equipment reliability, service life, and documentation quality, the project became not only a procurement task but also a comprehensive test of the supplier’s engineering integration capabilities.
2. Technical Solution and Pump Selection Strategy
To accommodate fluctuating submerged depths at the intake structure (up to 3.75 meters) and meet the large-flow cooling water demand, the engineering team selected the 200LC-23-37KW Vertical Long Shaft Pump. Rather than using a standard off-the-shelf product, the solution was specifically optimized for the project’s operating conditions.
① Hydraulic Performance Matching
The pump was designed with a flow rate of 360 m³/h and a head of 20.2 m, perfectly matching the resistance curve of the hydropower station’s cooling water circulation system.
Considering the seasonal variation in sediment content commonly found in Swiss mountain rivers, the impeller was manufactured from ZG230-450 cast steel. Compared with conventional cast iron impellers, this material offers significantly improved resistance to abrasive wear caused by sand and suspended particles, helping to extend maintenance intervals and service life.
② Upgraded Material Configuration
Material selection for wetted components was critical due to the long-term submerged operating environment.
The suction bell, diffuser bowl, and wear rings were manufactured from HT250 high-strength gray cast iron, providing excellent casting performance for complex hydraulic passages while also offering reliable corrosion resistance and reduced hydraulic losses.
The main shaft was produced from heat-treated 40Cr alloy steel, combined with 45# steel shaft sleeves. This configuration ensures sufficient rigidity at the operating speed of 1450 rpm, effectively minimizing shaft deflection and vibration typically associated with long shaft pump applications.
③ Drive System Compatibility
The pump was equipped with a YE3-225S-4P-37KW high-efficiency motor with an IP55 protection rating, fully compliant with Switzerland’s three-phase 400V / 50Hz industrial power standard.
The pump was designed for counterclockwise rotation, matching the orientation of the existing check valves and pipeline layout at the site. This eliminated the risk of thread loosening or operational issues caused by incorrect rotational direction.
3. Project Results
Following commissioning, the vertical long shaft pump significantly improved the stability of the hydropower station’s cooling water circulation system. The cavitation noise and vibration issues previously experienced during low-water-level operation were completely eliminated.
Thanks to the combination of a Q235B carbon steel column pipe and high-quality guide bearings, the pump has demonstrated stable operation, low vibration levels, and excellent reliability. The upgraded system not only enhanced cooling water delivery efficiency but also reduced maintenance requirements, providing a long-term and dependable solution for the hydropower station’s operational needs.
