Question

2. Power Plant Turbine Calculation: A power plant boiler operates at 10 MPa and heats water (H:0) to 600 °C after which it passes through a turbine for power generation. The H20 is discharged from the turbine at 8 kPa x = 0.90. The mass flow rate of H20 through the power plant is m = 110kg/s. (a) Calculate the actual turbine work w rurdize = ? MW. (b) Assuming adiabatic and reversible operation of the turbine, what is the value ofx at the turbine exit? ©) Use the value of x in part (b) to calculate the ideal turbine work. W Turbine, (MW). Then calculate the turbine thermal efficiency.

Answer 1

Calculating sailent point enthalpies using steam table of water , we can solve this problem as below-
sol: The data provided in the question are as below- Boiler 104 kpa. pressure 10 mpa = PH condenser , PL 8 kPa ) - Boiler outlet temperature 6oo'c Actual drynes less fraction at the turbine exit G 2 Congo Mass flocs rate of water, in = 110 kg/sec. We have to find out a) Actual turbine work in mW Ideal at the turbine exit. b) 6) Ideal turbine work in mu Turbine thermal efficiency * Process 1-2 - Expansion 2-3- Isobaric heat rejection. 3-4:- Pump work 4-1:- I sobaric heat addition. T-9 diagram t T Actual turbine , ܙܕܶܐ work (t) = h, ha Ideal turbine work, hi-hes. (WT) I PL 3 282 s

can be obtained from the steam Properties of H₂O table as beloci - hi = 3625,3 kJ/14 At 10 moa f Good A 6.9028 KJ kg K At hf KJ Pt &g - skra :- 173.378 KJ118 ng 2576.76 1kg 0.59088 KI I kaki 8.23114 KJ / FJ K oo100 84 m 0.84 m3/kg Actual Expansion - (1-2) = hi-hq 3625.3 - ha Now, he ha (hghg 173.378 + 0.90 (2576176-1731378) 9 f (IWT) a X 2336.422 KJ 1 kg a) Actual turbine work, (wala 362 5.37 2336-422 1288.88 KJ leg for in 110 kg / sec work actual. turtine KW m x 1288 88 al 2 110 x 1288.88 MW 3 11 141.776 mW Ans (a),

b ) Ideal has =ht Now, Expansion (1-28) + dag (hg- hs) $i = $25 0.59088 + xas (8.23114 -0.59088) Kas = 018261 or, 6.9028 = OY, :. has 173.378 + 0.8261 ( 25 2576.FO -173:378 2158.812 KJ lig b) Therefore, value of a at turbine exit - 1018261) Aug (1) c) work (WT) I 1) Ideal turbine in Chichas) 110 ( 3625.3- 110x (3625:3 2158, .812) kw V 2158.812) 3 MW 161.314 = MW Aus (C). رکاوN turbine thermal efficiency, in Whet Heat supplied (QS) (WIA WA where, Qs - Wp = pump work tou-hy.

h3 = =hg 173, 37% ET [ h4 = hz + 2 (PH-PL) 13. 3+8 + о бој00 84 (16ч. 8 193: 454 ИЈ | Fa с. Lр 2 — 143. 3+ 8 + 18 3 4 5 = 10, 626 вт (F7 4s 2 h, - hч 36 25. 3 - 183. ЧЅ = 344) • 846 1 ) fх °, | 38, 38 = 4 То, от 6 344, 46 1) 37 • 15 7. Ans