Performance Prediction of Centrifugal Norm Pumps Operating as Turbines

Pump-as-turbines (PAT) has been widely used during the last decade as one of the most interesting technologies in the field of energy recovery. Many studies and papers have been published in which the performance of the pumps in the turbine operating regime were analysed. Since horizontal single stage centrifugal norm pumps are most commonly used as PATs, their performances are analysed in this paper. Most of the research was related to individual pump aggregates or smaller groups and to obtaining their performance curves in turbine random mode. In this work, extensive experimental, numerical, and theoretical investigations were conducted to obtain complete dimensionless performance characteristics of single stage centrifugal norm pumps operating as turbines. One of the goals was to form a simple analytical expression that will, for this type of aggregate, map the pump operating characteristic to the appropriate turbine operating regime. By using the expressions obtained and presented in the paperwork, engineers are enabled to make the appropriate choice of pump aggregate for operation in turbine random mode for potential locations. For this purpose, the procedure for choosing the appropriate PAT aggregate or parallel operation of aggregates and the analysis of their operation on the existing system are presented in the paper. This innovative procedure allows us to select quickly PAT aggregates for a potential location and carry out appropriate techno-economic analyses and analyses of possible energy savings.