Análisis y evaluación del uso de turbinas para la recuperación de energía en redes hidráulicas a presión

Abstract

This thesis aims to evaluate the possibility of using unused hydraulic energy in urban water distribution systems, and reusing energy in urban water distribution systems. For this purpose, the feasibility and possible alternatives of installing conventional turbines and / or pumps that function as turbines (PATs = Pumps as Turbines) at the head of pressure hydraulic networks in three locations in the province of Huelva have been studied and evaluated. These are La Puebla de Guzmán, Cañaveral de León and Aracena (Andalusia, southwestern Spain). Sensitivity analises have been carried out in order to select the best alternatives taking the following stages into account: (a) Study of the viability and efficiency of the installation of turbines and / or PATs in hydraulic networks; (b) Determination of the required hydraulic capacity of the turbines and / or PATs; (c) Characterization and evaluation of the optimal points for installation in the hydraulic networks under study; and (d) Hydraulic and economic evaluation of the possible generation of electrical energy. The evaluation of the recoverable amount of hydraulic energy in water distribution systems requires the application of the energy conservation equation, taking into account the Darcy-Weisbach equation for the calculation of head losses. An energy flow head diagram with different working ranges of turbines and commercial PATs has been prepared for the selection of the suitable hydraulic machine. The results obtained in the Aracena hydraulic network show that the best solution would be the installation of a 2 kW BANKI turbine that could generate an approximate annual energy of 17.52 MWh/year. In the Cañaveral de León water supply system, it is proposed to install a 0.75 kW BANKI turbine with a possible power generation of 6.57 MWh/year. In the case of La Puebla de Guzmán, the results show different possible installation locations for a Francis turbine, which could generate energy of 280 MWh/year. On the other hand, a computer program has been designed and developed, using the JAVA language, which integrates the methodology developed and allows us to automatically calculate the type and hydraulic capacity of the turbines and/or PATs that could be installed considering the conditions and hydraulic restrictions of a specific water distribution system. In addition, this application provides how much annual energy could be recovered from the hydraulic network under pressure. For this calculation, the program takes into account the daily operating hours of the turbine and/or PATs to be installed. The program allows two calculation options. For the first and simpler option, it is only necessary to enter the flow rate and the net head available as input variables, in addition to the expected hours of operation of the hydraulic machine. The second option should be used when the net available head of energy in the hydraulic network is not known. In this case, the program calculates the head losses to calculate, from the gross head of available energy, the net head. In this case, the input variables to the program are: the flow, the gross head of energy and the characteristics of the pipes (diameter, length and material).