What is the optimum cycle time?

Shorter is not always better. When we look around the world, delayed coker cycle times vary from 10.5 hours to 48+ hours.

Typically, fuel grade cokers are striving to lower cycle time and increase throughput while anode/premium grade cokers are adjusting (shorter or longer) their cycle time to ensure high quality petcoke production. Overall throughput and conversion must be considered when optimizing cycle time. By going to shorter cycles, if the equipment reliability becomes a problem, then slowdowns and/or bypasses can impact the total throughput or utilization. Therefore, finding the right cycle time can be a balancing act with many parameters.

The common convention is to speak of cycle time in terms of drum fill time. However, a complete 'lap' from a single point in the cycle to that same point again on the same drum is typically double (2x) the quoted cycle time for 1 single drum. For example, if a drum was operation on 15h cycle (fill time) and cutting were to begin at 0900 on Wednesday on drum A, the next cut should (see troubleshooting or FAQs) occur on drum B at midnight (0000), while the next cut on drum A should occur on the 1500 on Thursday.