Deposits and scale extracted with novel engineering approach

Summary

A process malfunction involving the Waste Heat Recovery Unit (WHRU/hot oil heater) at a gas plant resulted in contamination with oil, which had been subjected to temperatures in excess of the usual high operational norm. Tube Tech were able to avoid cutting the serpentine coil and helped the client avoid costly replacement of the WHRU/hot oil heater.

Building a WHRU mock up Initial visual inspection of WHRU Internal view after initial water jet to revel tubes Items found within pipework Multiple 180 degree bend to negotiate Side view of WHRU serpentine arrangement Morning cleaning information

Challenge

  • The 250 metres of 2-inch diameter serpentine pipe work within the WHRU became coated with a thick, hard carbonised deposit.
  • The past experience of the manufacturer of the WHRU suggested the problem could only be solved by replacing the unit.
  • The clients’ initial cleaning option of removing the WHRU/hot oil heater module, would have meant three weeks of down time.
  • There was also substantial performance reduction and the additional costs of alternative ways of heating oil for production.
  • A traditional approach would have included removing the serpentine and cutting off the U-bends which would have taken at least six operational days plus another six for re-installation.

Solution

  • Tube Tech, which believes that it is the only time a WHRU/hot oil heater serpentine descale has been performed in-situ, carried out the whole operation in three days dealing with the WHRU’s 21 bends on each 2-inch tube – 25 ft above the ground.
  • Tube Tech avoided cutting the serpentine coil. Deposits and scale were extracted using a device specifically developed by Tube Tech to overcome the difficulty of access through a 10-inch header flange at a 90 degree angle to all 2-inch serpentine tubes.

Client Comment

A Process Reliability Engineer said: “The manufacturer told us that in its experience the only way to deal with our problem was a replacement. Tube Tech avoided that with a novel engineering approach. They did a first-class job. To take the whole thing out, replace it, plus structural support costs and craneage, we were looking at perhaps £500,000.”

Tube Tech Comment

Scott Donson, Technical Sales Manager: “This contract was a perfect opportunity for us to once again challenge traditional cleaning methods and we were pleased to have helped the client avoid the expense and inconvenience of replacing the WHRU/hot oil cooler.”

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