Design of Steam & Gas Turbines P.M.V. Subbarao Professor Department of Mechanical Engineering Indian Institute of Technology, Delhi A Table of Geometrical Details…..
Multistage Impulse Turbine : GE Product
What If it is A Single Stage Impulse Turbine
500 MW Steam Turbines in Indian Power Plants m_hp m_ip m_lp Mass Flow rate (tons/hr) 1534 1380 1141 MS CRH HRH Ex 5 Ex 4 Ex 3 Ex 2 Ex 1 Cond P (MPa) T (0C) h (kJ/kg) Mass flow rate (kg/s) 16.677 537 3396 4.454 344.8 3069 4.013 3530 766.67 1.922 430.4 3316 26.81 0.7456 300.6 3060 19.12((BFP) 22.09 0.267 194.8 2857 12.47 0.1361 135.8 2745 22.62 0.0278 67.37 2507 10.13 0.0092 44.15 2386
Plant Layout & Energy Balance Diagram
Approximate Rotor Inlet Conditions
General Rules for Steam Path Design For HP Axial (flow) velocity at the inlet is 40 m/sec and at the outlet 65 m/sec. (> 5 Mpa) For IP axial velocity of steam at the inlet is 60 m/sec and at the outlet 80 m/sec (5 Mpa – 0.3 Mpa) For LP axial velocity of steam at the inlet is 75 m/sec and at the outlet of last front stage is 130 m/sec. (<0.3 Mpa) Maximum mean blade speed used so far: 450 m/s Generally acceptable range of inlet flow angle(a1) : 150 to 200
Inlet Velocity Diagram U Vr1 Va1 Vr2 Va2 b1 a1 a2 b2
U Vr1 Va1 Vr2 Va2 b1 a1 a2 b2
Steam turbine design
y F
With known value of U , change enthalpy is obtained . For reaction turbine maximum efficiency occurs at loading factor From change in enthalpy absolute velocity of steam can be obtained
Range of turbine Design Parameter High Pressure Gas Turbine: Maximum AN2 : 2.5×107 – 3.3 ×107 m2.rpm2. Stage loading coefficient: 1.4 – 2.0 Stage Exit Mach Number: 0.4 – 0.5 Low Pressure Gas Turbine: Inlet mass flow rate: 195 – 215 kg/m2.s Hub/tip ratio: .35-.5 Max. Stage loading (based on hub): 2.4 Exit Mach Number: 0.4 – 0.5
L/F=2 L/F=1 L/F=0.5 L/F=0 (b1+b2) b1
90-a2 90-b1 F=0.5 90-a1
(b1+b2) b1