The Importance of Boiler Drum Level Controls

Drum level controls keep the level of water in a boiler within the limits specified by the manufacturer. If the water level rises too high or falls too low, the boiler may perform less efficiently, leak or fail altogether.

Drum Level

If the drum level rises too high, water may not be properly separated from steam in the drum and be carried over into the turbine, where it can cause extensive damage. Similarly, if the drum level falls too low, the boiler tubes may become uncovered leading to overheating, cracking and rupturing.

Feedwater Valve

Drum level controls may consist of one, two or three elements. They not only provide automatic control of the drum level, but an indication of the position of the feedwater valve -- which controls the drum level during filling and startup -- and manual control over it.

Alarm

Drum level controls also typically include alarm contacts, which sense abnormal level conditions and sound an audible alarm corresponding to low or high water levels. Alarm contacts are typically probe type sensors inserted into the water column of the boiler.

References

• Invensys: Boiler Drum Level Control
• Clark Reliance: A Guide to Boiler Drum Level Equipment and Control Concepts
• InTech: Boiler Drum Level Control