Question

Steam at gauge pressure of 1.5Mpa is supplied to a steam turbine, which rejects it to a condenser at a vacuum of 710mm Hg after expansion. Find the inlet and exhaust steam pressure in pascal, assuming barometer pressure as 76cm of Hg and density of Hg as 13.6×10³ kg/m^3.

Answer 1

 P_gauge = 1.5 × 10⁶ N/m²

 P_vacc = 710 mm of Hg

 P_atm = 76 cm of Hg = 101.3 × 10³ N/m²

 P_inlet = ? 

P_inlet = P_abs = P_gauge(inlet)+ P_atm

 = 1.5 × 10⁶ + 101.3 × 10³

 P_inlet = 1.601 × 10⁶ Pa           .......ANS

 Since discharge is at vacuum i.e.;

 P_exhaust = P_abs = P_atm – P_vacc

 = 101.3 × 10³ – 13.6 × 10³ × 9.81 × 710/1000

 P_exhaust = 6.66 × 10⁶ Pa        .......ANS

 ANS: P_inlet = 1.6×10⁶Pa, P_exhaust = 6.66×10³Pa