What does a three element feedwater regulator primarily measure?

A three element feedwater regulator is designed primarily to improve the control of water fed into a steam drum, and it specifically measures the drum water level. The three elements it typically includes are the drum level, steam flow, and feedwater flow. By measuring these elements, the regulator can maintain the optimal level of water in the drum, ensuring safe and efficient operation of the boiler system.

The focus on drum water level is critical because maintaining this level within a set range is essential for preventing issues such as water carryover to the steam, which can lead to damage to downstream equipment. While steam flow and water flow are also important in the overall system, they serve more as additional data points that enhance the monitoring and control of the drum water level rather than being the primary measurement that the regulator acts upon.