A three-element feedwater regulator is controlled by which of the following?

A three-element feedwater regulator is designed to control the feedwater supply to a boiler or steam drum based on three critical parameters: steam flow, feedwater flow, and drum level. The integration of these three elements allows for a more precise and responsive control system that keeps the drum water level stable while accommodating variations in steam demand.

Steam flow measurements provide information about how much steam is being generated and consumed, which affects the amount of feedwater that needs to be supplied. Feedwater flow indicates the current rate of water being fed into the system, ensuring that supply aligns with demand. The drum level measurement is crucial because it ensures that the water level remains within safe operating limits for the boiler, preventing conditions like low-water levels that could be dangerous.

By continuously monitoring these three variables and adjusting the feedwater flow accordingly, the three-element system is able to maintain optimal conditions for steam production, improving efficiency and safety. This interplay is what makes this control method superior to those relying on just one or two factors.