Waste Energy Recovering in Water Pipelines by Using Pumps Running as Turbines

The present work assesses the possibility of installing pumps turbines (PATs) in water purification plants for the recovery of energy lost in the processes of high altitude spring water treatment. In particular, two Calabrian sites, Casali (CS) and Sersale (CZ), where hourly water flow rates data are available, offer the possibility of installing cheap plants of the type described. To select a pump in reverse operation (PAT), under the conditions assigned by the aqueduct users needs, a procedure was carried out that uses statistical correlations between the flow rates ratios and head ratios at the BEP in the two modus operandi of the PAT by varying the specific speed. This procedure has provided a first indication about the choice of suitable pumps among those commercially available, candidates for the above said sites. Then, a numerical code, developed in previous works, has been employed to estimate the performance of the selected pumps, running as turbines, by using input data given in the manufacturers’ catalogues. In the following, the energy yields for different operating conditions of purification water plants were calculated.