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Furnace Tube Decoking “ON-LINE!” at Far East Distillate Synthesis Plant – World First!

Blocked serpentine furnace coils cleared in one day

Summary

The request from the client was to develop a procedure in order to remove severe blockages of coke which had formed some distance along the inside of 2 x 100mm diameter 45m long serpentine furnace tubes. Additionally Tube Tech was asked whether it believed it possible to unblock both lines whilst the unit was online and operating at 430 degrees centigrade so as to avoid incurring costly production downtime for the plant.

Challenge

Tube Tech accepted the challenge to create a system that would not only unblock and decoke the furnace tubes but achieve this whilst online.
It was the first time Tube Tech had tackled such a tube cleaning challenge and set about fabricating a half-size furnace replica at its UK headquarters in order to demonstrate, as close to reality, the feasibility of carrying out this tube cleaning task at 430C on-line.
A globally recognised petrochemical consultant on behalf of the client witnessed the successful trials at Tube Tech and approved its use for the Asian client.

Solution

The trials at Tube Tech were carried out in three stages.
The heat was quenched by a constantly-monitored injection of water with the resultant steam being safely contained and guided away through high-temperature seals.
The furnace tubes were navigated by means of a modified high-pressure jetting lance, modified to withstand the severe temperatures and high torque which it would encounter within the furnace tubes. Buoyancy pockets would assist the drill in reaching the “coal face.”
Having practiced the procedure many times with military precision at 430 degrees C in the furnace replica they unfortunately found, due to other critical site requirements, that the blocked furnace was to remain offline for that day only ever reaching 120 degrees C during the entire furnace unblocking operation.
As a result all blockages located along both 45m serpentines were cleared in 1 day instead of the anticipated 3 days as temperatures were more forgiving for both personnel and equipment.

Tube Tech Comment

Mike Watson, Technical & Managing Director: “Whilst we were unable to carry out cleaning online at 430 degrees C we were confident our procedures would have been up to the task due to exhaustive and successful trials carried out in the UK . It must be said however that even navigating 45m of bends to unblock rock solid coke formation at 120 degrees C is no easy task and may in itself be a world first. Of course furnace de-coke and cleaning online for the client would have been the icing on the cake. Nevertheless it delighted the client to hear we had broken through both blocked serpentine furnace coils so quickly, which was to substantially improve the furnaces performance.”

Clients can be contacted via Tube Tech for references.

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Refineries (Onshore - Downstream) Case Studies