A coke drum experiences operating conditions that are severe and unrelenting, and their lifespans reflect this. In this paper, a coupled thermal-mechanical model of an operating coke drum is presented. The impacts of important operating parameters, such as the cycle time and quench rate, on an ideal operating cycle and a cycle that produces hotspots are discussed. The model is constructed in three stages: (i) the through-wall temperature distribution is probabilistically determined using a Bayesian inverse approach that calculates the heat flux profile on the inside of the drum wall from a temperature reading on the outside of the wall; (ii) a thermal-mechanical finite element analysis of the drum wall is conducted using the heat flux profile as a spatially and temporally varying boundary condition — to obtain the stress and strain behavior at a critical location (weld seam) on the drum; and (iii) hotspots are introduced in the vicinity of the weld through a novel approach, and their impact on the plastic behavior of the drum wall is examined. The influence of the operating conditions on the behavior of the coke drum is to be incorporated into a financial analysis of the entire coke drum’s life cycle — in a companion paper — to determine an optimal operating strategy.

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