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An Innovative Approach to Solving Design Challenges of Thermowell

Rosemount X-Well Technology, a non intrusive process temperature monitoring system. A thermowell and temperature sensor assembly is the most frequently used method of measuring a temperature internal to a process. Thermowells allow for direct sensor immersion into a process, but in doing so, also introduce a possible leak point and safety concern.

Emerson approaches the problem of thermowells from the bottom up. Solutions to thermowell design challenges may range from prevention of thermowell issues to elimination of the thermowell itself.

 Of significant interest are two possible approaches to the thermowell challenge. The first is suppression of the negative effects on the thermowell induced by process conditions through the use of a twisted square thermowell design versus the traditional cylindrical design. The fixed separation point established by the traditional cylindrical design can allow ribbons of vortices to synchronize and shed uniformly, applying forces on the thermowell. The continuously changing separation point on the twisted square design causes chaotic vortex shedding and the upstream vortex disrupts the downstream and vice versa, so that the mean and max stresses on the twisted square are much lower than the fatigue limit.

 The other approach is elimination of the thermowell altogether. For some time, manufacturers have attempted to solve the problem of thermowell design complexity by using surface temperature measurements. These seem ideal since they require no penetration into the process, eliminating the leak potential, requiring no wake calculations, and enabling far simpler installation and maintenance. The downsides of surface measurement, however, are that they are far less accurate or repeatable, and therefore, have made surface temperature an inappropriate substitute for thermowells – until now.

 Emerson engineers knew that by implementing an algorithm with an understanding of the thermal conductive properties of the temperature measurement assembly and corresponding piping or vessel, a surface temperature sensor solution could be developed to accurately calculate internal process temperature. The result is Rosemount X-well technology, a non-intrusive process temperature monitoring system. (See picture to the left.)The Rosemount X-well technology:

  • Compensates and corrects for environmental effects
  • Measures ambient (T1) temperature and pipe surface temperature (T2)
  • Uses measurement assembly’s and process piping thermal conductivity properties to calculate heat flow through assembly
  • Extrapolates accurate process temperature inside the pipe (T3)

 This new technology provides:

  • Accurate process temperature measurement without requiring any intrusions or penetrations into the process
  • Elimination of possible leak points
  • Simplified specification, installation and maintenance
    • 65% reduction in design and engineering time
    • 70%+ reduction in installation time
    • No wake frequency calculations
  • Additional measurement points without process shutdown

 Rosemount X-well technology is suitable for many applications, including the majority of pipe processes:

  • Pipeline monitoring
  • Small line size applications
  • Retrofit projects that need new points
  • Pipelines requiring frequent cleaning
  • High velocities
  • Slurries and heavy particulate fluids
  • Clean-In-Place (CIP) processes
  • High viscosity fluids
  • Harsh processes requiring exotic materials

 The non-intrusive technology has been used successfully in many challenging applications.

Do you have an application where the new Rosemount X-well technology might solve problems? Let us know in the comments.

Do you have an application where the new Rosemount X-well technology m

ight solve problems?