Delayed Coke Units ... on shapes

Delayed Coke Units, one of the dirty and dangerous facilities of the Oil & Gas Industry in the world, every turnaround rise up a huge amount tasks that challenge any project team.

---

Find out how do the project team complete a 40 tons devices maintenance in site, and in the middle of the internal coke drum’s repair in just 45 days.

When the client presented such a requirement, the entire engineering team thought that it would be impossible but after countless hours of work and coordination, we succeeded to complete the Major Maintenance of the Coke Drums Unheading System on site within the expected time and complying with all customer requirements and international standards. In this technical article, I will briefly describe the work for illustrative purposes, without leaving out the most interesting details of the plan.

The sliding devices of 36 inches on top and 60 inches on the bottom, in conjunction with the Hydraulic Power System (HPU), are the mechanical devices used to open and close the Coke Drums in the processes of Catalytic Cracking, sub-process used to upgrade the heavy crudes.

When the unheading devices spare parts were confirmed on site, the project team started the maintenance by the bottom valves, recording the assembly sequences and the conditions of the components removed. Once the team polled out the whole auxiliaries services; cooling water, condensate discharge, hydraulic system, power supply and field instrumentation, the team got free to reach the internal components.

Bottom Unheading Devices. BUD

To address those 40 tons big devices, the project deployed a lifting system that hung from the main coke drum structure, which allowed the team to unmount the BUDs from the lower flange coke drum. Using these lifting system the bottom device was settled down upon the floor of the DCU bottom platform.

Due to the internal coke drum cladding repair, the team split the device into two big pieces, the first one was the actuator and upper bonnet and the other was the body and lower bonnet.

Once the coke drum bottom flange was free for internals repairs, the dynamic seals and its related components were replaces on the device body.

Finally, the upper bonnets and its actuators came back to the upgrader, and after the team settle the lifting plan, the whole valve was in a single piece back again.

Coke Drum Unheading Control System

The instrumentation and control system were disconnected, recording the status and condition of each element. The biggest challenge was to maintain the integrity of the conductors, instruments, connections, junction boxes, in the middle of the drum welding repairs and mechanical maintenance of the valves, however everything was reconnected, and the maintenance of the PLC cards, PLC, CPU, Power Supply, and the grounding system was completed on time.

When the time of commission and start up the system again arrived, that was, the time of truth!

In those moments where the work is completed but has not been tested "almost finished”!!!!!,

it is recommended greater focus and determination to integrate again all the parts, according to the engineering and manufacture specifications.

Since the client will have the pressure to start as soon as possible, the client is requiring 100% of the facilities available, to start to recirculate the product.

Finally, after some adjustments to the hydraulic system, servo valves, o-rings, everything started to go according to the manufacture design specifications, the project improved the opening and closing times of the 60-inch gates from 25 min to less than 5 min, and it was recorded a saving in steam consumption of approximately 7%.

The project management was supported by an excellent teamwork, the planning was highlighted by the production of daily progress reports, which allowed us to keep internal and external stakeholders, clients, project manager informed, among others.

Contract administration completed the 100% of the valuations with a billing of 100% at the project close, in addition, 9 claims were submitted for changes in scope of work and time extensions attributable to the client, which represented new income to the project equivalent to 7% of the offer, also it was reached 18350 HH without accidents, developing a culture of safety in all maneuvers and activities carried out.

I hope you have enjoyed this article, the final client started the Delayed Coke Unit with no inconvenient with an incredible unheading devices performance.