Drum Level Control

Damage to the steam drum, boiler and turbine can result from inaccurate drum level control.

If the drum level falls below setpoint, there is risk of the boiler running dry. If the level is higher than setpoint, there is risk that wet steam could carry over to the turbine, causing damage to the turbine blades.

During startup when the pressure drops across the drum level control valves are very high, there is the possibility for severe cavitation that can cause damage to the valves, and downstream piping and equipment.

Application challenges with continuous boiler water level measurement:

Changing steam dielectric and water density as a result of pressure and temperature changes
A narrow control-range
Redundant level measurement requirement

Control Associates and its instrumentation division Pro-Tech Solutions can address these process control challenges plus meet redundant level control requirements with the Rosemount™ 5300 Guided Wave Radar (GWR) level transmitter with high temperature, high pressure seal, and Dynamic Vapor Compensation, paired with the Rosemount™ 3051S differential pressure transmitter.

During startup the pressure drop across the drum level control valve can produce damaging cavitation.

The high pressure (HP) and intermediate pressure (IP) drum level control application is fairly moderate during typical plant operation. However, during startup the pressure drop across the valves, particularly the HP drum level control valve can produce damaging cavitation.

The Fisher™ HP and IP drum level control valves offered by Control Associates are specified with the Cavitrol™ anti-cavitation trim option to control or eliminate cavitation during startup, while providing the rangeability required for smooth transition to normal operation.