EVALUATION OF THE OPERATION OF A PUMP USED AS A TURBINE (PAT) UNDER REAL OPERATING CONDITIONS IN A DRINKING WATER TREATMENT STATION (DWTS)

This paper analyzes the performance under real conditions of an axial flow hydraulic pump used as a turbine (Pump as Turbine or PaT) in a Drinking Water Treatment Station (DWTS). The DWTS is located at the municipality of Baiona (NW of Spain) and is supplied from a reservoir located at a height of about 50 m above the level of the plant. The existing difference in level at the intake makes it necessary to regulate the flow at the plant inlet by means of a valve, for which, prior to the development of the generation installation, a gate valve was used. In order to take advantage of the existing difference in level, a 6 kW micro-generation system was put into service using a PaT supported by a butterfly valve for flow regulation. The main reasons for choosing this generation system were the high cost of small turbines for the characteristics of the hydraulic connection of the DWTS and the limited availability of this type of device. The system is in service and being monitored by a SCADA since July 2019 so there is a relevant amount of records that allows analyzing different operating conditions. In the sizing of a BUTU system it is necessary to estimate the behavior as a turbine since the pump manufacturer only provides data in operation as a pump. There is a large literature proposing methods for estimating the performance of BUTU systems, however, the most widely accepted methods are those validated experimentally, as intended in this article. Keywords: PaT, renewable generation, micro-hydraulics