Question 346Steam Plants - Assistant Engineer

The correct answer is D) load change. During periods of load change, the boiler feed water control valve varies the unity relationship between steam and water flow in order to maintain proper water level in the boiler. This is necessary to accommodate the changing steam demand, ensuring a stable and consistent water supply to the boiler during fluctuations in load. The other options are incorrect because: A) Steady boiler load does not require the feed water control valve to actively vary the steam-water relationship. B) Minimum boiler load would not necessitate the feed water control valve to make adjustments. C) Overload operation, while challenging, would still require the feed water control valve to maintain the appropriate steam-water balance.