A Rational Methodology for Determination of Service Life for a Delayed Coke Drum

Abstract

Delayed coking is an essential technology in the upgrading of heavy hydrocarbons in the Canadian oil sands for producing saleable liquid and gas products in order to sustain a viable national energy industry. Delayed coking units contain among the largest pressure vessels used in heavy industry and are operated under severe thermo-mechanical loading conditions. Beginning in the late 1950’s, it was recognized that drum shell cracking presented a major source of reduced unit reliability affecting safety and financial viability of the delayed coking process. There are very few focused studies in the open literature on coke drums investigating the root cause, the mitigation of the thermo-mechanical failure mechanism and remaining life prediction. This work is a continuation of prior work to define, in detail, the thermo-mechanical loading of coke drums and evaluate its impact on service life. The available operating data in the open literature is limited and problematic; thus, the access given to proprietary data was invaluable in completing this effort. In order to best serve the industry, this thesis has used as much data, techniques and methodologies currently available in the industry to perform the service life determination so that industry practitioners may implement this work without resorting to difficult and unnecessarily complicated methods and, better, to honour the vigor of industry practices and the contributions of the many mechanical engineers who developed them.