The benefits of any condensate recovery system are well documented in industries relying on steam generation for their processes. Condensate has real value in that every gallon recovered spares the cost of additional makeup water, makeup water treatment and/or wasteful discharge to municipal or other systems. Oftentimes, it is the instrumentation, or lack thereof, that limits the performance of the overall system causing the recovery process to fall short of financial expectations.
This blog post, part of the Magnetrol® series based on a new steam generation white paper, discusses the applications and pitfalls of level measurement in the condensate recovery cycle, as well as level instrumentation for these applications.
Level Measurement Challenges and Considerations
Three areas of particular interest relative to efficiency when it comes to level controls are the condensate receiver and main condensate tanks, condensate pumps and associated valves as well as any shell and tube heat exchangers/condensers.
The condensate receiver tanks accept blow-through steam and condensate from various steam process groups throughout a plant. Condensate is later pumped to the main condensate tank where it is stored pending reintroduction into the steam generation cycle.
The shell and tube heat exchanger/condenser allows what would otherwise be waste energy to be recovered in the form of flash steam from the receiver tank to preheat makeup water or other process fluids through the heat of condensation. The resulting condensate drains back to the condensate or condensate receiver tank.
The level transmitter on the condensate receiver tank facilitates the automatic management of the condensate level to ensure adequate capacity is available to accommodate (recover) condensate from various plant processes as well as maintaining sufficient headspace in the vessel for the creation of flash steam. Aside from being a critical asset for the plant, the condensate in the condensate receiver tank also protects valves and condensate pump seals from direct exposure to high temperature steam while maintaining a minimum head pressure on the pump. This prevents hardware damage; expensive maintenance and downtime of the receiver tank; and subsequent ripple effects on the steam generation cycle and makeup water requirements.
Lastly, the level transmitter provides the control signals for the valves and condensate pump necessary to transfer condensate from the receiver to the main condensate tank, ensuring approximately 15 percent level retention for the aforementioned reasons. At this point, the main condensate tank level transmitters take over to manage boiler feed water supply to service steam generation demand.
Level Measurement Solutions
For condensate recovery applications, guided wave radar (GWR) transmitters and magnetic level indicators provide reliable, efficient level measurement. These technologies are unaffected by process conditions and can return accurate readings despite the steam and high pressure in condensate tanks. They require no calibration and have no moving parts, reducing instrument error. MAGNETROL has designed its guided wave radar transmitter, the Eclipse® Model 706, and its magnetic level indicators, the Atlas™ and Aurora®, specifically to withstand the high-temperature steam environments present in the condensate recovery cycle. With reliable, precise instrumentation, the condensate recovery system can perform as designed and inefficiency can be reduced. The new GWR steam probe has condensation return vents that help eliminate condensation in the probe, delays in signal transmission and level measurement errors.
For more information on level measurement solutions for condensate recovery or other steam generation applications, download the steam generation white paper.