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

2 x Texas Towers down from 24 shifts each to 5 shifts for both

Summary

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) platformer 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.

Challenge

The 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.
What compounded an already inefficient heat transfer problem was that the operator had accidentally allowed several cubic metres of light oil to carry over into the shell side of both Platformer V.C.F.E. Texas Towers. It was unknown if it was also in the tubes.
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 as they had tried several chemical and water jetting contractors around the world but none were able to assure the client of likely 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. Manpower alone was not the answer and Tube Tech went to the drawing board to come up with a unique solution.
- Shell Side
  - The shell side of both Texas Towers were cleaned with an ingenious ultrasound and oscillating device.
  - Water pressures in excess of 40,000 psi combined with a polymeric water to increase the impact on the deposit, were used in conjunction with the agitating action of the oscillating lance.
  - What the jet did not remove, the vibration did.
  - The combined effect of this highly unique jetting process was better than anyone had anticipated.
- Tube Side
  - Tube Tech safely and quickly drilled ca 7% of blockages from the 3612 tubes contained in both bundles, in preparation for de-scaling with Tube Tech’s unique twin ceramic darTT technologies.
  - Each projectile 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. Trial after trial eventually provided us 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, of any heavily fouled square pitch exchanger, be it Crude, FCC, even polymer deposits. It will be of great benefit to many refineries and industries world wide.

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 I get, working with clients, is when they 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”.

Clients can be contacted via Tube Tech for references.

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