Page 76 - Handbook of Energy Engineering Calculations

hour; at zero load, steam flow is 50,000 lb/h (22,700 kg/h). What is the steam
rate in pounds (kg) per kWh at 4/4, ¾, 2/4, and ¼ load?

Calculation Procedure:

1. Write the steam-flow equation for this turbogenerator
The curve of steam consumption, called the Willian’s line, is practically a
straight line for steam turbines operating without overloads. Hence, we can

assume a straight line for this turbogenerator. If the Willian’s line is extended
to intercept the Y (vertical) axis for total steam flow per hour, this intercept
represents the steam required to operate the turbine when delivering no

power. This no-load steam flow—50,000 lb/h (22,700 kg/h) for this turbine—
is the flow rate required to overcome the friction of the turbine and the
windage, governor and oil-pump drive power, etc., and for meeting the losses
caused by turbulence, leakage, and radiation under no-load conditions.
Using the data provided, the steam rate equation can be written as [(50/L)

+ 9.5] = (F/L) = [50 + (1000 − 50)/100(L)]/(L), where F = full-load steam
flow, lb/h (kg/h); L = load percent.

2. Compute the steam flow at various loads
Use the equation above thus:

Related Calculations. The Willian’s line is a useful tool for analyzing steam-
turbine steam requirements. As a check on its validity, compare actual turbine
performance steam conditions with those computed using this procedure. The
agreement is startlingly accurate.

REHEATING-REGENERATIVE STEAM TURBINE CYCLE
ENERGY ANALYSIS