Answer: Analyzing Regenerative CyclesA power plant

Chapter 8, Problem 63P

(choose chapter or problem)

A power plant operates on a regenerative vapor power cycle with two feedwater heaters. Steam enters the first turbine stage as \(12 \mathrm{MPa}, 520^{\circ} \mathrm{C}\) and expands in three stages to the condenser pressure of \(6 \mathrm{kPa}\). Between the first and second stages, some steam is diverted to a closed feedwater heater at \(1 \mathrm{MPa}\), with saturated liquid condensate being pumped ahead into the boiler feedwater line. The feedwater leaves the closed heater at \(12 \mathrm{MPa}, 170^{\circ} \mathrm{C}\). Steam is extracted between the second and third turbine stages at \(0.15 \mathrm{MPa}\) and fed into an open feedwater heater operating at that pressure. Saturated liquid at \(0.15 \mathrm{MPa}\) leaves the open feedwater heater. For isentropic processes in the pumps and turbines, determine for the cycle (a) the thermal efficiency and (b) the mass flow rate into the first-stage turbine, in \(\mathrm{kg} / \mathrm{h}\), if the net power developed is \(320 \mathrm{MW}\).