Page 349 - Steam Turbines Design, Applications, and Rerating

Elliott Shortcut Selection Method for Steam Turbines 323

Figure 15.10 Performance map for typical extraction turbine, metric
units. (Elliott Company, Jeannette, Pa.)

Locate Point C at 3970 hp and 150,000 lb/h throttle flow. Now draw line C-D par-
allel to A-B and another line C to B. Label A-B “Zero lb/h extraction at 250 psig”
and C-D “150,000 lb/h extraction at 250 psig.”
Notice that the general shape of the diagram and the slopes of the
lines are determined mainly by the steam conditions used. The turbine
investigated here could be built, but one must remember that we have
dealt only with the thermodynamic aspects of this application. The
mechanical aspects, such as blade stresses, nozzle flow limits, cooling
steam, and other factors must also be checked.