Page 308 - Steam Turbines Design, Applications, and Rerating

282 Chapter Fourteen

(a)

(b)
Figure 14.14 Mechanical losses of single-valve, single-stage, high back-pressure
turbines, 8 in/200 mm exhaust, 3000 hp/2250 kW. (Elliott Company, Jeannette, Pa.)

Using metric dimensions,
3600
TSR = kg/(kWh)
h 1 − h 2
where h 1 is the enthalpy in kJ/kg of steam at the turbine inlet, and
h 2 is the enthalpy in kJ/kg of steam at the exhaust pressure and at
the inlet entropy.
Step 2: Determine base steam rate (BSR) using Figs. 14.5 through
14.9, based on TSR, turbine speed, and turbine frame.
Step 3: Determine the mechanical loss using Figs. 14.10 through
14.14, based on turbine speed, exhaust pressure, and turbine frame.
Step 4: Determine superheat (use Table 14.5 or 14.6).
Step 5: Determine the superheat correction factor (SCF) using Fig.
14.15, knowing superheat and TSR.