project status

Latest News

January 2010


New Aletas y Birlos site launch.


x-id tubes


    What is X-ID®?


  • X-ID is an internally enhanced tube.
  • Tube augmentation (passive or active) techniques are used to increase the heat transfer rate.
  • The augmentation in an X-ID tube is achieved by helical ribs on the inside of the tube.
  • Ribs modify the behavior of the fluid flow leading to heat transfer augmentation.


    Why do we need tube-side enhancement?


  • Four resistances to heat transfer.

From the flue gas in the tubes to the tube wall 91 %
Through the thickness of the tube wall 0.75 %
Fouling 6.25 %
From the tube wall to the water on the shell-side 2 %

  • Overall heat transfer controlled by the tube side.
  • Increasing the tube-side heat transfer significantly increases the overall heat transfer.




    How does the X-ID tube work?


  • In flow over a plate or in a pipe, the fluid boundary layer builds up with distance and provides increased resistance to heat transfer.
  • grafica01


    Developed View – Helical Ribs


  • Rib height, pitch, profile, spacing, helix angle are all design parameters.
  • grafica2


    Increased steam space in X-ID boilers


      4-pass bare tube 2 pass X-ID
    Tube count 232 x 2.5” o.d. 224 x 2.0” o.d.
    Heating surface 2558 2126
    Heating surface / BHP 5.12 4.25
    Steam volume (ft3) 95.36 155.6
    Boiler efficiency 82.4 81.2
    Boiler pressure drop 6.0 2.5


    X-ID Tubes in Firetube Boilers

    Advantages of X-ID tubes


  • Inside heat transfer rate 85% greater than bare tube.
  • Increased boiler efficiency.
  • Number of tubes in boiler can be reduced.
  • X-ID boiler requires less space (smaller design size).
  • Cost savings on larger boilers up to 20%.


nuestras ventajas