Category Archives for Process Troubleshooting

Hot Coke

If a refiner is to operate on a short coke drum cycle, he can expect to encounter pockets of hot coke that the drum cooling water has not had time to quench. During the coke-cutting portion of the decoking cycle, … Continue reading

19. July 2013 by Jack
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Heading Up

As soon as the cutting water pump is shutdown, the decoking crew immediately begins replacing the top and bottom heads. Both heads must be worked on simultaneously. Flange surfaces are prepared while the coke cutting is in progress. On this … Continue reading

19. July 2013 by Jack
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Dual Purpose Cutting Head

This coke-cutting procedure involves the use of a combination coke-cutting/drilling tool made by Pacific Pumps (Dresser Industries), as shown in Figure 2-12. This cutting head is currently in use in a large minority of U.S. cokers. The Worthington dual-purpose cutting … Continue reading

19. July 2013 by Jack
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Coke Cutting

Cutting time varies with the hardness of the coke, the condition of the hydraulic cutting nozzles, and the available cutting water pressure. Of equal significance is the skill and experience of the person cutting the coke. Initially, a 4-ft diameter … Continue reading

19. July 2013 by Jack
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Drainage Problems

If the drum is not draining properly, the decoking crew should proceed as follows: Wait as long as possible without jeopardizing the cycle. Set the bottom carriage—which is used to slide the bottom head out from under the coke drum—up … Continue reading

19. July 2013 by Jack
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Bottom Head Removal to Shorten Coking Cycle

The decoking crew should begin unbolting the bottom head while the drum is still draining. Leaving every third bolt in place, the drum depressured and mostly drained, keeps the head secured. As soon as the worker unbolting the head sees … Continue reading

10. July 2013 by Jack
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Recid Line to Bottom Head to Shorten Coking Cycle

Many cokers have a removable spool piece between the bottom head of the coke drum and the resid feed line. This section of piping must be disconnected every cycle. Usually, it is not possible to drop the bottom head without … Continue reading

10. July 2013 by Jack
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Automatic Water Filling to Shorten Coking Cycle

Once the switch has been completed and a small flow of steam (4,000-5,000 Ib/hr for a 20-ft diameter drum) has been estabished, the vapor valve on the full drum will be slowly reopened. Meanwhile, the operators should be lining up … Continue reading

10. July 2013 by Jack
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Keep Drain Free to Shorten Coking Cycle

One of the frequent causes of extended coke drum cycles is the difficulty in filling the drum with cooling water. Once feed is switched out of a coke drum, the coke tends to settle back and partially plug the feed … Continue reading

10. July 2013 by Jack
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Pneumatic Vapor Valve to Shorten Coking Cycle

Coke drum overhead vapor valves are massive affairs. Switching a pair of 20-ft diameter drums may require the manipulation of four 18-in. and four 12-in. valves. Size aside, the vapor valves are difficult to open and close because of coke … Continue reading

10. July 2013 by Jack
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