Experience in the operation of large axial-flow pumps on main canals

Abstract

1. Operating experience and full-scale investigations made it possible to evaluate the effectiveness of designs that have been adopted and to formulate the main requirements imposed on the design of pumps and pressure pipes for pumping stations intended to operate in a sequence on main canals. Among the priority tasks to provide reliability of large pumping equipment with respect to parameters and performance are: provision of a high accuracy in the manufacture and assembly of the working elements and flow part of pumps; consideration when designing pumps of the conditions of their interaction with pipelines in transient and steady regimes. 2. To reduce the fluctuating loads on the pump and to limit the starting currents in the motor at small heads, the pumps should be started at small vane angles. In the case of large starting heads, with the danger of falling into an unstable operating regime when the vacuum-breaking valve is open, and also with horizontal inserts at the beginning of the pressure pipes, the pump should be started at medium or even large vane angles, which may be determined by full-scale tests. Horizontal inserts at the beginning of the pipe should be avoided at new stations being designed. 3. The pump should be stopped if necessary to bring it out of the saddle regime and then started at a large vane angle. 4. Pumps with a hydraulic drive for turning the impeller vanes should be stopped at large vane angles. This reduces the magnitude and time of action of dynamic loads, increases pump reliability, and lengthens its service life.