Author(s): M. A. Angulo; A. Rivetti; C. V. Lucino; S. O. Liscia

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Keywords: Pump station; submergence; free surface vortex

Abstract: Thermal power plants require water cooling pump stations to inject fresh water into the condenser. Generally, these pump stations have vertical mixed-flow pumps with large flows and low-to-medium heads that take water from rivers or reservoirs. Under certain natural conditions, water sources can reach extraordinarily low levels, thus affecting pump operation as the minimum recommended submergence might not be met, causing the power plant to be powered off. This causes both a very high loss of profit for the company and a decrease in the available power for the electrical supply system. Therefore, expanding the range of submergence under which pumps could be operated safely for special, transitory, and emergencies is an alternative worth exploring. Pump operation below the minimum level gives rise to unacceptable vortices on the free surface, air entrainment inside the circuit, higher mechanical vibrations, and lower efficiencies due to higher pre-swirl at the suction bell. Because of this, an anti-vortex device is proposed to prevent free surface vortex formation to allow the operation of the pump over a wider range of submergence. The device has a grating shape and was designed and optimized based on scale model tests performed on a typical pump bay following the ANSI standard intake design. Flow analyses through particle image velocimetry (PIV), acoustic Doppler velocimetry (ADV) velocity profiles, and swirl-meter measurements were carried out for a range of levels under the minimum and then compared with the device installed under the same conditions. Experiments proved the effectiveness of the solution to reduce free surface vortex formation and pre-swirl, allowing pumps to operate down to half of the recommended submergence.

DOI: https://doi.org/10.26077/3fa1-7f82

Year: 2022