Question

In a steam power plant the steam entry condition to turbine is P = 4 MPa, T = 400°C. h = 3213.6 kj/kg and The stream condition at turbine exit is P = 3.5 MPa. T = 392°C, h = 3202.6 kj/kg and From the turbine a heat loss of 8.5 kJ/kg is observed. What is the steam flow rate? Assume diameter of pipe = 0.2 m

$\upsilon =0.073m^3/kg.$

• A. 53.4 kg/s
• B. 40.2 kg/s
• C. 45.3 kg/s
• D. 112.1 kg/s

Answer 1

The correct option is A 53.4 kg/s

$h_1=3213.6kJ/kg$ $$k_2=3202.6kJ/kg$$

$Q=-8.5kJ/kg$

By SFEE, $$h_1+\frac{V_1^2}{2000}-8.5=h_2+\frac{V_2^2}{2000}$$

$\Rightarrow 5000=V_2^2-V_1^2$

$\Rightarrow \frac{A_1{V}_1}{v_1}=\frac{A_2{V}_2}{v_2}$

$\Rightarrow \frac{V_1}{0.073}=\frac{V_2}{0.084}$

$\Rightarrow V_1=0.869V_2$

$\Rightarrow V_2=142.9m/s$

$m_s=\frac{A_2{V}_2}{v_2}=\frac{\frac{\pi }{4}\times {0.2}^2\times 142.9}{0.084}=53.44kg/s$