Emerald Group Publishing Limited
Copyright © 2004, Emerald Group Publishing Limited
Tough job – gentle touch
Tough job – gentle touch
Keywords: Tube Tech International, Aluminium, Tubing, Cleaning
As a company with a growing reputation for handling some of industry's toughest cleaning jobs, Tube Tech International has proved that it is capable of the gentle touch, too.
Tube Tech has broken through the pressure barrier on cleaning aluminium tubes, a material with a big potential for sustaining damage during descaling operations. The radical new approach to cleaning notoriously-tenacious scale from within aluminium tubed furfural exchangers brought substantial benefits at the BP Coryton refinery in Essex (Plate 2).
Plate 2 Tube Tech's innovation in the bullet
The project heralded the success of another Tube Tech innovation, which enabled a particularly delicate hairpin heat exchanger to be completely cleaned in situ for the first time. This reduced down time by 3 days and cut the risk of damage normally associated with removing this type of tube bundle for cleaning.
Tube Tech convinced BP it was possible to break through the barrier of 200 bar water pressure (3,625 psi approx.) which had earlier been imposed to avoid damage to the aluminium tubes. Tube Tech's research and development team pioneered a combined pressure and mechanical device increasing pressure up to 2,500 bar (40,000 psi approx) for removing coke deposits.
Where the conventional process only removed 20 per cent of blockages and scale on the straight legs alone, Tube Tech's three-stage process using a sensitive mechanical device coupled with exceptionally low volumes of water achieved 90 per cent coke removal. Initially, each tube was cleaned using a patented Softdrill lance made from “intelligent” metals to prevent damage to the tube wall. These soften on entering the “U” tube and stiffen on extraction. An oscillating motion drills the blockage using a mixture of water and the occasional infusion of food grade media at 12 times the pressure and four times the speed of the conventional approach. Finally, a Tube Tech-developed micro turbine, rotating under controlled hydraulic pressure, is guided through.
Tony Kernp, TIPS Planning Team Leader at BP Coryton said: “Tube Tech's specialist capabilities are excellent. This particular type of coke deposit is very stubborn to remove. A traditional 200 bar pressure had limited success on the straights and tends to compact on the U-bends rather than remove it”.
“By not having to remove the tube bundle from its shell we reduced equipment down time by about half. The fact that we were able to achieve a very high standard of cleanliness was a true testament to Tube Tech's abilities”.
“Not having to disturb the heat exchanger will lengthen its life and, from the higher standard of cleanliness reached, we would expect to see longer periods between cleaning.”
Tube Tech's Managing Director, Mike Watson said: “We built the test rig at our own expense so we were able to investigate thoroughly our ideas. We had to strike a delicate balance between effectively removing the coke, even in the bends, while ensuring no damage to the aluminium”.
Among the benefits of using the system we developed were that the exchanger was cleaned in situ; down time reduced by 3 days; and blockage removal increased from 20 to 90 per cent while the potential damage to aluminium tubes was eliminated. “BP is also very pleased with the subsequent reduced costs and the improved performance of the unit”.
For more information, visit our Web site: www.tubetech.com