Question

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

Answer 1

Given that:

Capacity of drum V1 = 0.24m3

Pressure of steam P1 = 11bar

Temperature of steam T1 = 200C

At pressure 11bar from super heated steam table

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

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

Using linear interpolation:

( – 0.2060)/(0.1693 – 0.206) = (11 – 10)/(12 – 10)

= 0.18765 m3/kg

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

From Saturated steam table

At 11bar; Tsat = 184.09C

2000C > 184.09C

i.e. steam is superheated

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

From Saturated steam table; corresponding to g = 0.18765, the pressure is 1122.7KPa