Hot Coke

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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, hot coke is a very real hazard. A jet of cutting water hitting 700°F coke …

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Heading Up

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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 basis, heading up the coke drum and reconnect­ing the resid feed line takes about 30 …

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Dual Purpose Cutting Head

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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 head was found to be impractical and is no longer available. The head permits switching …

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Coke Cutting

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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 hole is hydraulically drilled down the center of the coke drum using the pilot cutting …

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Drainage Problems

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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 against the head. Remove all but four bolts. Then loosen the remaining four bolts so …

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Keep Drain Free to Shorten Coking Cycle

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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 nozzle in the bottom head. This effect is especially pronounced when shot (i.e., BB-size pellet) …

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Pneumatic Vapor Valve to Shorten Coking Cycle

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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 deposits on valve internal parts. Removing the insula­tion on piping upstream of the vapor valves …

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