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How Freezing Cold Temperatures Impact Level Instrumentation

Abnormally low temperatures not only wreak havoc on power grids causing widespread outages, but also upstream at the power plant. Steam drum level is the most critical measurement to keep a power plant running and provide a reliable flow of electricity to the grid. During the extreme cold, there are often reports of instrumentation hardware freezing and subsequently forced (unplanned) shutdowns due to unreliable level measurement.

Level instrumentation is no stranger to harsh environmental and process conditions; however, various types of level transmitters have different modes of operation and points of failure that make their reliability more (or less) susceptible to extreme climates. Differential pressure (DP) transmitters are often relied upon for level measurement in steam drums and their large installed base breeds familiarity with engineers, operators and technicians. This familiarity is a benefit to utilizing DP for level, but it does not necessarily mean it is the best fit for every application.

DP is an inferred method of level measurement that traditionally requires impulse lines or capillary tubing along with the use of condensate pots in steam applications. The additional hardware requirements are subject to their environmental surroundings and become a common point of failure due to water freezing within the condensate pots and lines/tubing.

In steam drums when the level transmitter is not functioning or provides erroneous outputs, it results in inefficient plant operation and potentially unplanned shutdowns. Guided Wave Radar (GWR) transmitters, an alternative solution to DP, output direct level measurement without requiring all the additional hardware. With GWR, there are no calibration requirements and level measurement is independent of fluctuating process conditions.
 

GWR provides an attractive alternative over DP for steam drum operation in power plants:

  • Enable operator decisions based on direct level measurement; removing the inferred calibration and excessive variables that must be accounted for (e.g., condensate pots, impulse lines, manifold sequencing, P&T related density correction, etc.)
  • Accurately manage normal water level during start-up, base load, cycling and duct burner operations to optimize steam-water separation
  • Prevent carryover associated with coating of critical HRSG and turbine components for improved hardware lifecycle management
  • Reduce upfront installation and commissioning as well as long-term maintenance costs while adhering to the ASME Boiler Pressure Vessel Code
  • Make excessive blowdowns (level too high) or disruptions in boiler natural circulation (level too low) concerns of the past

For any industry that has challenging steam applications (i.e., Power, Refining, Chemical, Pulp & Paper), GWR reduces complexity and has become the level measurement technology of choice.

Contact us directly for more info or download our "Comprehensive Approach to Steam Drum Level Control" brochure.