Q&A ’13: How to troubleshoot hydroprocessing reactor turnarounds
By Billy Thinnes
DALLAS -- Randy Alexander from Reactor Resources closed out the Hydroprocessing Principles & Practices technical session at the AFPM Q&A and Technology Forum by discussing issues associated with hydroprocessing reactor turnarounds.
Mr. Alexander was equal parts expert, teacher, moderator, cajoler and philosopher as he held court during his presentation. His folksy charm and willingness to solicit opinions from the audience at various points during his talk facilitated one of the best session conversations during this year's Q&A and Technology Forum.
Planning. Much advance work must go into organizing a turnaround and catalyst change. Mr. Alexander said that work starts with monitoring reactor conditions and catalytic activity. He noted that any planning worth its salt should commence from 12 to 18 months in advance of the catalyst change. On the subject of scheduling, Mr. Alexander was frank: prepare for delays. He said the earlier a refiner can begin soliciting contractors for maintenance work, the better. "Keep in mind you aren't the only refinery to be in turnaround when you are planning this," he said.
Another key aspect to consider is how a refiner plans to sulfide the catalyst. "If you are going to use preactivation, you will need more lead time," he noted.
Once a plant's maintenance plan is set, meetings should immediately start with turnaround groups. "Define schedule restraints as clearly as possible," Mr. Alexander recommended. "There could be other units coming down at the same times. Coordinate with the other engineers and units. Assign specific tasks to individuals as much as possible. Evaluate your staffing requirements. You will need extra engineers for the units since you will have around-the-clock coverage."
Mr. Alexander is also a strong proponent of staging the equipment coming onsite. Whether this equipment is cranes, cleaning equipment or catalyst bins, plant management must appropriately allocate spacing at the site and not allow work dates to sneak up.
"We like to do job walks," Mr. Alexander said. He and his team decide where to locate equipment trailers onsite, and discus appropriate connection points. He also said it is essential to develop contingency plans.
Activate. A catalyst will not do anything until it is activated. Within hydrocarbon and chemical processing, three techniques are used for activating catalyst. The first is in-situ sulfiding. This process is the lowest in cost and is the industry standard. It usually takes 24 to 30 hours for the sulfiding step to execute. However, there are some negatives associated with this technique; mainly that the refiner must bring in sulfur chemicals. H2S levels must also be monitored.
Presulfurization is the second technique. In this instance, sulfur is delivered on the catalyst. Such a setup demands a higher cost than in-situ sulfiding. Another negative is the potential for exotherms.
The last widely used sulfiding technique on the market is preactivation, which offers the fastest startup time. The catalyst is delivered in active form and ready to go, with no exotherms. One negative to this approach is that the cost is quite high. With this option, the refiner must also organize bin rental and budget for more lead time/scheduling.
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