In a three-element feedwater regulating system, which quantities are measured?

In a three-element feedwater regulating system, which quantities are measured?

• A. Water Quality
• B. Fuel Flow, Air Flow, and Draft
• C. Steam Flow, Feedwater Flow, and Water Level
• D. Boiler Pressure, Temperature, and Humidity

Answer: (C)

In a three-element feedwater regulating system, the measurements are steam flow, feedwater flow, and boiler drum water level. Steam flow reflects the current steam demand or load on the boiler, so the control needs to boost feedwater as steam demand rises. Measuring feedwater flow shows exactly how much water is being supplied, allowing the system to adjust accurately to meet the demand. Monitoring the water level in the boiler drum ensures the level stays within safe limits—too low can expose tubes and cause damage, while too high can cause water carryover into the steam. Water quality, combustion variables like fuel flow, air flow, and draft, and other boiler parameters such as pressure, temperature, or humidity are not the trio used for this specific feedwater regulation approach.