Vessel (Reactor) – Fused Polymer Removed from Mixing Vessel

Operator using polymeric water lance with 360 degree viability B.A Manually removing polymer after cutting External view of vessel Drain off demonstrates minimal waste created Morning cleaning information

Dense water cleaning saves replacement of mixing vessel

This company produces polyester and alkyd resins, gelcoats and conventional and inverse water-based polymers from five manufacturing sites across the world, including the plant in Northamptonshire, UK, featured in this case study.

The contents of a polymer mixing vessel at the UK plant of this global manufacturer of polyester and alkyd resins became fused solid following a process error. Chiselling out the fused styrene was too time consuming and was ultimately unsuccessful, while replacement was too costly and traumatic an option to consider. In less than two weeks of intensive work, Tube Tech cut out the polymer in blocks using ultra-high pressure, low-volume, ‘polymerised’ water and restored the vessel to duty.

Challenge:

  • A 5 metre high x 2.5 metre diameter polymer mixing vessel became unserviceable following a process error that caused its content to fuse into a solid mass of styrene.
  • The plant’s operators had tried chiselling the hard styrene out, but after several weeks had made little impression on it.
  • Replacement of the vessel would be expensive, take too long and be problematic structurally.
  • Cleaning could be complicated by the heating coils around the wall of the vessel, as any cleaning solution would have to be able to reach behind them to remove the styrene.

Solution:

  • Tube Tech devised two solutions to take to site.
  • Method one involved entering the vessel with one man in a 360 degree visibility, half air breathing apparatus and equipped with a jetting lance.
  • Method two was based on a remote system.
  • Until there was room in the vessel for an operative, the work started with a remote head, removing styrene from the manway.
  • Once the manway was cleared, Tube Tech used a WysperJet, running at up to 60kpsi but producing very low water volumes. This combination is extremely powerful but has little reactive force, so is not tiring for the operator.
  • The lance does have to be held very close to the target as the water’s energy dissipates rapidly.
  • Much of the 2-3 litres of water disperses as water vapour, leaving little to be pumped out.
  • Having an operator work safely in the vessel meant that it was possible to safely cut away the styrene behind the heating coil and around the central mixing shaft and paddles completely.
  • The styrene deposit was progressively cut up in chunks which were then removed via the manway.
  • Even with the cutting power at Tube Tech’s disposal it took nearly two weeks continuous working to remove all the rock-solid styrene and get the mixing vessel back to full working order.

Tube Tech Comment

Tube Tech MD and Technical Director, Mike Watson, said: “On other work we have carried out on reactor and mixing vessels that have suffered process problems, we have been able to deal with the contents fairly easily. In this case, however, because the vessel contents had cured into a rock solid mass, we had to come up with a cleaning method that would have enough power to break up the styrene without flooding the vessel with water while our operative was at work and that was the ultra-high pressure, low-volume, polymer-infused water. It’s quite ironic that polymer in the jetting stream was used to remove polymer. Once we got down to the drain at the bottom, of course, it wasn’t such a problem – but that took several days of tough work. Happily, the client got his vessel back into production quickly without the trauma and expense of replacement.”

Client Comment

“We were facing some tough decisions when we realised that manual removal with chipping hammers and chisels was having little impact on the mass of styrene in the vessel. In two weeks we had only managed to remove a couple of bucketfuls! Ordering a new vessel would have meant a wait of many months for a replacement and we would have had to carry out major construction works to get the old vessel out and install the replacement. When Tube Tech stated they had worked out a removal method that would save the vessel, we were sceptical it could be done, but were only too willing to let them try it. I have to say we were surprised and delighted with the results.”

For more information or to discuss your cleaning challenge call us on +44 1268 786999 or e-mail info@tubetech.com, alternatively click here to fill out our contact form.

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