Page 110 - Handbook of Energy Engineering Calculations

17,060,000/403 = 42,300 lb/h (19,035 kg/h) of steam. Then the full-load
steam rate of the turbine, lb/kWh = (steam flow, lb/h)/(kW output at full load)
= 42,300/5000 = 8.46 lb/kWh (3.8 kg/kWh).

Related Calculations. Use this general procedure to determine the available
energy, theoretical and actual heat rates, and full-load output and steam rate

for any stationary, marine, or portable condensing steam turbine operating
within the ranges of Figs. 30 and 31. If the actual performance curves are
available, use them instead of Figs. 30 and 31. The curves given here are
suitable for all preliminary estimates for condensing turbines operating with

exhaust pressures of 1 or 3 inHg absolute (3.4 or 10.2 kPa). Many modern
turbines operate under these conditions.

STEAM-TURBINE REGENERATIVE-CYCLE

PERFORMANCE

2
When throttle steam is at 1000 lb/in (abs) (6895 kPa) and 800°F (426.7°C)
and the exhaust pressure is 1 inHg (3.4 kPa) absolute, a 5000-kW condensing
turbine has an actual heat rate of 11,350 Btu/kWh (11,974.9 kJ/kWh). Three
feedwater heaters are added to the cycle, Fig. 32 to heat the feedwater to 70
percent of the maximum possible enthalpy rise. What is the actual heat rate of

the turbine? If 10 heaters instead of 3 were used and the water enthalpy were
raised to 90 percent of the maximum possible rise in these 10 heaters, would
the reduction in the actual heat rate be appreciable?