Page 111 - Handbook of Energy Engineering Calculations
P. 111
FIGURE 32 Regenerative feedwater heating.
Calculation Procedure:
1. Determine the actual enthalpy rise of the feedwater
2
Enter Fig. 33 at the throttle pressure of 1000 lb/in (abs) (6895 kPa), and
project vertically upward to the 1-inHg (3.4-kPa) absolute back-pressure
curve. At the left, read the maximum possible feedwater enthalpy rise as 495
Btu/lb (1151.4 kJ/kg). Since the actual rise is limited to 70 percent of the
maximum possible rise by the conditions of the design, the actual enthalpy
rise = (495) (0.70) = 346.5 Btu/lb (805.9 kJ/kg).
FIGURE 33 Feedwater enthalpy rise.
2. Determine the heat-rate and heater-number correction factors
