Page 73 - Handbook of Energy Engineering Calculations

ENERGY TEST DATA FOR STEAM POWER PLANT
PERFORMANCE

A test on an industrial turbogenerator gave these data: 29,760 kW delivered
with a throttle flow of 307,590 lb/h (139,646 kg/h) of steam at 245 lb/in 2
(abs) (1688 kPa) with superheat at the throttle of 252°F (454°C); exhaust

pressure 0.964 in (2.45 cm) Hg (abs); pressure at the one bleed point, Fig.
11a, 28.73 in (72.97 cm) Hg (abs); temperature of feedwater leaving bleed
heater 163°F (72.8°C). For the corresponding ideal unit, find: (a) percent
throttle steam bled, (b) net work for each pound of throttle steam, (c) ideal
steam rate, and (d) cycle efficiency. For the actual unit, find: (e) the

combined steam rate, (f) combined thermal efficiency, and (g) combined
engine efficiency.

Calculation Procedure:

1. Determine the steam properties at key points in the cycle

Using a Mollier chart and the steam tables, plot the cycle as in Fig. 11b.
Then, S = 1.676; H = 1366 Btu/lb (3183 kJ/kg); H = 1160 Btu/lb (2577
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1
2
2
kJ/kg); P = 14.11 lb/in (abs) (97.2 kPa); H = 130.85 Btu/lb (304.9 kJ/kg);
3
2
2
P = 5.089 lb/in (abs) (35.1 kPa); H = 46.92 Btu/lb (109.3 kJ/kg); P =
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3
4
2
0.4735 lb/in (abs) (3.3 kPa); H = 177.9 Btu/lb (414.5 kJ/kg).
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