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The Value of Displacer Switch Technology for Level Detection in a Condensate Drip Leg

Displacer switch technology can provide highly accurate level detection for many applications in the power generation industry, including the steam generation process. However, detecting level within the condensate drip leg or drip trap of a main steamline is a very challenging task for many power companies.

To accurately measure this very difficult application, you need to implement highly reliable level instrumentation, but only a few manufacturers today are able to provide the technology that this process requires. To find the right solution for your facility, it is important to understand how displacement type liquid level technology functions within the condensate drip traps of a steam boiler.

Main Steamline Drip Traps
To prevent turbine water induction, you can install condensate drip traps (or drip legs) along your plant’s main steam lines, steam extraction lines, and hot or cold reheats. Many companies place these drip traps along their super-heated steam lines to collect particles of moisture and drain off the accumulated condensate. When a displacer level switch senses the upper level in a drip trap, it will trigger the opening of a valve to dump the accumulated condensate.

In this application, plant operators face the challenge of preventing particles of moisture from escaping the condensate collection systems and entering the turbines, which can cause significant damage. In addition, level controls in condensate drip legs must contend with very high temperatures and pressures.

Application Example – Steam Boilers
Using displacer switches – such as the Magnetrol® Model B40 float-actuated switch – is a proven way to provide accurate level control for your plant’s steam boilers. For example, a utility company recently implemented this solution when it needed to reliably maintain dry steam in a steamline with service conditions of 3000 PSIG and +697°F.

Installing multiple float-actuated switches in strategic locations along the steamline – such as on the drip trap (as shown above) – enabled the company to detect any steam condensation that occurred. This type of external sealed cage float switch also features thick walls and a counterweighted design, which made it an ideal solution for the extreme conditions within this application.

For More Information
To learn more about displacer switches, including the MAGNETROL Model B40 float-actuated switch, you can also download the MAGNETROL Buoyancy Products technology bulletin.