Texas Tower (VCFE Platformer) Mechanical External Shell Side Cleaning – World First!

2 x Texas Towers cleaned in 5 shifts (Down from 24 shifts)

Safety, speed and cleanliness were deemed the most important factors by the 230,00bpd (crude) and 17,000bpd (lubricant) French refinery. The two V.C.F.E. (Texas Tower) combine feed/effluent exchangers were last cleaned on the Shell and Tube side in 2001 when it took 24 shifts to clean each VCFE Texas Tower, using traditional high pressure water jetting guns and lances but was deemed dangerous, slow and very inefficient with very little improvement in performance.

ROT / HIT (Reactor Outlet Temperature – V – Heater Inlet Temperatures)

• Cold Approach Graph
• Cleaning Hot Approach Graph
• Heat Transfer Coefficient Graph

The Challenge

  • Heat transfer in both Texas Towers had been reducing since 2001 and there was no record of deposit characteristics.
  • From their past Texas Tower cleaning experiences Tube Tech knew that gummy and coke like deposits settle in certain areas of the exchanger.
  • Accidentally carry over of several cubic metres of light oil compounded shell side fouling of both Platformer V.C.F.E. Texas Towers. This light oil was suspected to have burnt off at high temperature leaving a hard layer of hydro carbons of unknown thickness, volume, consistency or location.
  • When previous attempts in 2001 on a not so dirty exchanger had limited success it was obvious that neither traditional 1000 bar jetting nor chemical cleaning would remove a likely hydrocarbon coke formation deep in between the tubes of the shell.
  • The client was very concerned having tried several chemical and water jetting contractors around the world but none guaranteed success due to the limited access.
  • With a critical shut down schedule the client was desperate to have both the shell side and tube side of both vertical combined feed/effluent exchangers cleaned within a 6 day window instead of the previous 24 and at the same time remove the coke.

Solution

  • Both platformer combined feed exchangers were pulled and suspended vertically in parallel to their respective shells.
  • Both Texas Towers were cleaned with an ingenious innovation called Shell Jett which used ultrasound, mechanical oscillation and pressures up to 55,000 psi.
  • The combined effect of this highly unique jetting process was faster than anyone had predicted.
  • 7% of blockages were drilled from the 3612 tubes, in preparation for de-scaling with Tube Tech’s ceramic darTT.
  • Each darTT was handmade to fit the 14.83mm tube ID and debris from within the tubes was collected beneath the two Texas Towers.

Tube Tech Comment

Mike Watson, Technical and Managing Director : “This challenge brought out the best in all of us and our suppliers. In house trials at our headquarters provided a solution that achieved results way beyond anyone expectations. An exceptionally safe and successful contract was completed in an incredible 5 x 10 hour shifts.

This new technology paves the way for mechanical cleaning of any shell side, any heavily fouling within any square pitch exchanger with line of sight, be it Crude, FCC, even polymer deposits. It will be of great benefit to many refineries and industries worldwide.

The deposits removed from both shell and tube side were shown to contain a great deal of iron oxide and heavy hydrocarbons. Our client reports that the shell and tube side clean has seen a dramatic improvement in the heat transfer rate between the two vertical combined feed/effluent exchangers.

On a personal note, the biggest buzz is when clients genuinely commit to the importance of team work, honesty and seamless communication. This client was one of the best we have ever had the pleasure to work with.

Images and videos associated with this project are available via Tube Tech International
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