geothermal power plant projects in central america - Orkustofnun

FIGURE 14: T-s diagram of single-flash cycleSteam separatorAfter the separator, the flow has a slightly higher quality mixture, where the fluid is separated into twocomponents: saturated vapor at station 2 and saturated liquid at station 5 as the separation process ismodeled at constant pressure (isobaric). The steam mass fraction that goes to the turbine is given byEquation 5 = (5)Defined over an energy balance in the separator, the mass flow rate of the steam is written as = (6)TurbineSaturated steam, which is a small fraction of the total geothermal fluid, is expanded in the turbine,where some of the steam energy is transformed into mechanical energy in the shaft. In an idealturbine, it is assumed to be a constant entropy process (isentropic) from the inlet at station 2 to theideal exit at point 3s. The isentropic enthalpy at 3s is then calculated from the pressure at point 3 andthe entropy at point 2. The expansion is irreversible, and the steam entropy is higher. Turbines areclassified with an isentropic efficiency parameter that is given by the manufacturer, defined as = ,(7)From Equation 7 above, the real turbine exit at station 3 can be calculated. The total power output ofthe turbine is given by = ( h − h ) (8)The total electricity generated is equal to the work output of the turbine multiplied by the generatorefficiency, written as = (9)16