A power plant operates a regenerative Rankine cycle with a reheat, one closed and one open feedwater heater and has a net power output of 1.2 x 109 Btu/hr. When the steam exits the boiler it's temperature is 1000°F and its pressure is 1400psi. At the exit of the first stage of the turbine the pressure has dropped to 500psi where some of the steam is bled off to go to the closed feedwater heater and the remaining steam goes back to the boilers for reheating. The steam is reheated back up to 900°F before entering the second stage of the turbine. . After the second stage turbine some steam is bled off at 120psi to go to the open feedwater heater and the remaining steam passes through the third stage turbine. The condenser operates at 2psi Condensate exits the bottom of the closed feedwater heater as a saturated liquid at 500psi and is trapped back to the open feedwater heater. The working fluid leaves the closed feedwater heater at boiler pressure and a temperature equal to the saturation temperature at 500psi. The turbines and pumps both have and isentropic efficiency of 85%.
Determine:
a) The specific work of the turbine in Btu/lbm
b) The specific work of the pumps in Btu/lbm
c) The mass flow rate of steam exiting the boiler in lbm/hr
d) The needed rate of heat transfer into the boiler in Btu/hr
e) The thermal efficiency of the cycle.
m) Draw the T-s diagram for this cycle and label all points MAKING SURE THEY ARE IN THE CORRECT PLACES WITH REGARDS TO PHASE.