calculate quantity of steam in the vessel -

Question

Calculate quantity of steam in the vessel - thermodynamics:

A closed metallic boiler drum having capacity of 0.24m3 contains steam at pressure of 11bar and a temperature of 200ºC. Calculate quantity of steam in the vessel. At what value of pressure in the vessel will the steam be dry and saturated if vessel is cooled?                                                                                                                   

Sol.: Given that:

Capacity of drum V₁  = 0.24m3

Pressure of steam P₁  = 11bar

Temperature of steam T₁  =   200ºC

At pressure 11bar from the super heated steam table

At 10 bar and T = 200ºC; Å =0.2060m3/kg

At 12 bar and T = 200ºC; Å =0.1693 m3/kg

By using linear interpolation method:

(Å - 0.2060)/(0.1693 - 0.206) = (11 - 10)/(12 - 10)

Å = 0.18765 m3/kg

Quantity of steam = V/Å = 0.24/0.18765 = 1.2789 kg

From the Saturated steam table

At 11bar; T_sat  = 184.09ºC

2000C > 184.09ºC

That is, steam is superheated

If vessel is cooled until the steam becomes dry saturated, its volume will remain same but the pressure of it will change.

From Saturated steam table; corresponding to Åg  = 0.18765, pressure is 1122.7KPa          .......ANS