Oil Processing: Delayed Coking

Why has coke drum height (T/T) not exceeded 29,261 millimeters (96 feet)?

Increasing coke drum height, while not as beneficial as larger drum diameter, results in greater coke bed volume and avoidance of reduced fill cycle times.  Mechanical design, capital cost and safety-related issues are responsible for setting the current height limit:

Drill Stem System Design

Coke cutting system vendors have developed “standard” design methodologies for the support and operations (extension  & retraction) of the drill stem.   Vendor design costs may be difficult to justify without an assured market for taller coke drums.

Coke Drum Structure Cost

Every meter of coke drum height escalates the cost of support structure and piping.

Safety

Every meter of coke drum height escalates the safety risks associated with operations and maintenance associated with having personnel accessing, working and evacuating from higher elevation above grade.

Increased coke drum structure height escalates the safety risks associated with nearby flares, furnace stacks and air traffic.