Question

A steam power plant is based on the Rankine cycle with reheat (refer to the figure below). Steam is produced by the boiler/superheater (H-1) at 100 bar and 600 C at a rate of 2.5 kgs. This is expanded to 10 bar in the turbine T-1 and then reheated to 600 °C in heater H-2. The steam is then expanded in turbine T-2 to a pressure of 0.1 bar. The steam is then condensed in condenser (C-1) which operates at 0.1 bar. The liquid water leaving the condenser may be assumed to be saturated. The condensate is returned, via pump P-1, to the boiler as feed. Turbines T-1 and T-2 have 90% efficiencies. The power required for pump P-1 may be assumed to be negligible. Calculate i) the power (kW) produced in each turbine (T-1, T-2) i) the duty (kJ-hr) of each heater (H-1, H-2) ii) the duty (k-hr) of the condenser (C-1), and iv) the thermal cycle efficiency. Is the steam leaving turbine T-2 wet or dry? Note: The enthalpy of saturated liquid water at 0.1 bar is 191.81 kJ-kg1 T-2 (turbine) H-1 (boiler) T-1 (turbine) H-2 (boiler) C-1 (condenser) P-1 (pump)

Answer 1

0 Solution Given data 100 6o1 0 baT 5 Moss Plow Tate- 3.5 9e H1 H2

下s diagYom EnthalPhy at state hg 3625-3 Entsofy at state 6.9089 K H Prom the table at o bor The Satuated Steam entophy . The entrephy is higher than b 53 state ( i Supes hea tey from Sufer heater tabte

he -ha ho-h 3625-3-hs 3625-3 2131 69 = 900 1.055 kJlu hu enthalthy at c and oba se,uteedel state Mou)

cwhere So 2 ent X5 0.9838 5 →Tre entrophy at 51스 g.o290 hs 19.83 o-983r (a

Nouu 3647.9 hs 0.9 39 7.9-2545 .91 h。 19,.askr / kg Volume l'oloaylo-3 규/Kg specific ad Stage -V K3JKg Lo oo Power Pro duced Turbine (T ha-h 35 3 300 o55) wTSo 6195 ku oTg2-5 (3697.9-661 2591, 85 kw

8558.67 ks|sec 3697.9 300l. 055) 174a-11 k |sec -5 2661-K-191-23) 2 c173 . 325ド汀ムec net work dome Since the Rump wo K İ Or sidered as negligible. net work dme i Sumot uwok done by t an Ta and

werk ouut heat inRt Uresmal ト1 + H2 1560.มี25+2591.95 8558 67(742 4o3 from the oe hs -2661. 16 kkg ushich is greate than the Sourates Vapaur enthalphy at o-to boy S he StateSupea ted stat The steam having T- i dvy