Berlín geothermal project, preliminary power plant design

Abstract

The main objectives of this report are to determine the optimum pressure for the technical operation of a geothermal field and optimize the turbine selection. Calculations are made to guide the selection of the first condensing power plant in the Berlín geothermal field in El Salvador. Silica content in the Berlín wells is relatively high; saturation of amorphous silica is reached at about 10 bar-a. The most important result obtained showed that the optimum wellhead pressure is in the range 7-10 bar-a. For a single flow and single pressure turbine, a 560 mm last stage blade length is selected. The power output is 30 MWe with minimum exhaust loss of 15.63 kJ/kg, annular velocity of 177 m/s and a specific steam consumption of 1.85 kg/s per MWe. Management strategies to deal with silica scaling are presented.