Handbook of Turbomachinery Second Edition Revised - Ventech!

Figure 17 Enlarged portion of the Mollier diagram illustrating typical fossil and
nuclear turbine expansion lines.
fossil unit cycles. This can be seen by reference to Fig. 17, which shows the
lower pressures and enthalpies of the steam in both nonreheat and reheat
nuclear cycles when compared to fossil units. Nuclear cycles have lower
steam parameters, typically 6–7 MPa (870–1015 psia or 60–70 bar) and
(260–290 8C 500–554 8F), with around 0.25% moisture and very large flow
rates (approximately 4,000 lbm of steam per second in a 1200 MW plant). In
some PWR designs, steam is produced at a slight superheat. As a result of
these steam conditions, there is considerable difference between the HP
turbine of nuclear and fossil units. Predicted exit wetness ranges typically
are 13–17%, with actual values being somewhat less because of moisture
removal by drainage devices and steam extraction.
Copyright © 2003 Marcel Dekker, Inc.