Fatigue Analysis of Coke Drum Hot Box
Delayed coke drums are integral part of delayed coking unit in petroleum refineries which converts petroleum
residue into higher value petroleum coke by thermal cracking process. Coke drums experience thermal and pressure
variations during process. Temperature fluctuations are severe and causes repetitive thermal stresses which leads to the
fatigue failure at various locations and skirt to cone junction is being one of the critical. The purpose of the present study is
to find an optimized skirt Hot-box junction geometry which will minimize thermal stresses and improve fatigue life.
Axisymmetric model of coke drum is developed in ANSYS. Transient thermal analysis followed by structural analysis is
carried out to obtain the stresses induced in coke drum during the cycle. Fatigue life is evaluated as per ASME BPVC Sec.
VIII Div. 2 based on the stresses obtained. Key parameters like hotbox length, crotch radius, skirt thickness etc. are varied
and their effect on the fatigue life is observed.
Keywords - Coke drum, Hot Box,Fatigue life, Thermal Fatigue.