If a boiler generates saturated steam at 125.3 psig, how much heat is required to change the water into steam if the feed water temperature is 240°F? SG-0004

Correct Answer: Option A — 983.4 Btu/lb

Enthalpy required is the difference between total heat of steam at the saturation pressure (approx. 1223.4 Btu/lb) and the sensible heat of feedwater entering at 240°F (approx. 240 Btu/lb), yielding approximately 983.4 Btu/lb per marine thermodynamic calculations.