Safe Life Estimation of Coke Drum in Service Environment

Abstract

It is generally known that delayed coke drums are operated under severe conditions by cyclic heating and quenching operation. It makes them susceptible to thermal fatigue. Therefore, fatigue failures have been identified in the skirt to shell junctures. In this study, the high-temperature fatigue crack initiation (HTFCI) life, Ni , and high-temperature fatigue (HTF) life, Nf , have been experimentally determined under two kinds of load spectrum by using specimens of 14Cr1MoR steel plate butt-weld. Comparing two groups of experimental result, the interaction between fatigue and creep is not significant at the test temperature. Furthermore, the expressions of HTFCI life and HTF life of 14Cr1MoR steel plate butt-weld are presented by regression analysis of the test results. According to the ANSYS finite element numerical simulation, the maximum equivalent strain amplitude of the connection weld area between the coke drum body and the skirt is 0.0032619. Taking account of the fatigue life safety coefficient and the number of heating and cooling cycles of coke drum in a year, the analysis shows that the safe life of coke drum is about 18 years, but the fatigue cracks occur in 8.6 years. As a result, this approach can be used to evaluate the safe life of delayed coke drums and can help for the maintenance of the equipment.