Repeat Problem 9.54 for a closed feedwater heater where the extraction steam is pumped to the boiler pressure before being combined with the condenser feedwater, as shown in Fig. 9.18. Assume isentropic turbines and pumps.

Problem 9.54

Consider a 600-MW regenerative-Rankine-cycle steam power plant with an open feedwater heater, as shown in Fig. 9.17. The boiler pressure is 1000 psia, the extraction pressure is 200 psia, and the condenser pressure is 1 psia. The high-pressure turbine inlet temperature is 1000 F. The water leaving the condenser is saturated liquid. The exit state of the feedwater heater is also saturated liquid. Determine the thermal efficiency of the power plant and the boiler mass flow rate (lb_m/hr).

Fig 9.17

Figure 9.18

m Boiler moorv N Pump 2 m m ym (1-y) m Open feed- water heater (a) 3 53 6 Pump 1 Turbine (1-y) m Condenser Temperature, T 21 m y m (1-y) m Entropy, s (b) 5 3 m 4 (1-y) m S