By John Aumuller
Delayed cokers are an essential unit in oil sands plants and refineries since introduction of this technology to industry in the early 1930’s. The delayed coker drum operates under severe service conditions of not only high temperature to 900°F (482°C) but also quenching to near ambient temperatures. The drums are also operated in a batch manner of approximately 24 hours which contribute to the severe, thermo-mechanical cyclic loading. Notable problems identified in a number of industry surveys undertaken by the API since the 1950’s include:
Other problems have been incrementally resolved through recognition of the thermo-mechanical damage mechanism and implementing fatigue compatible design and construction.
With society demanding reduction and minimization of carbon based energy production to halt and even reverse climate warming, industry operators need to anticipate possible stranding of facility assets. With coke drums being one of the most costly investments in their facilities, owners of existing units will want to operate existing equipment to the true limit of useable service life; owners contemplating new investment will want to design, construct, and operate this equipment in an optimal manner to maximize investment return.
The various methodologies, both direct and indirect, to evaluate thermo-mechanical damage to a coke drum have been unsatisfactory, yielding uncertain input to repair and replacement decisions. Bulging damage has complicated this evaluation.
Carmagen has worked over the past 10 years with leading researchers and manufacturers to reconcile the available industry methodologies, such as the ASME VIII Division 2, ASME III Codes and ASME / API fitness-for-service standards to develop a robust and effective solution technique to accurately assess coke drums and provide accurate service life determination, especially for damaged coke drums. While these documents form the basis of a solution methodology, they do not address the notion of service life and the fit-for-purpose techniques required to effectively determine the true useable life of this equipment as it deteriorates in service.
During the upcoming ASME PVP2016 Pressure Vessels & Piping Conference in Vancouver, British Columbia, Carmagen will present a paper outlining this methodology and invite attendees to share their experiences and current equipment problems.