Fatigue life prediction of delayed coke drums

As part of the global study that PDVSA is carrying out in the area of delay ed cooking, this paper presents an assessment of a 1Cr-1/2Mo coke drum that operates in high temperature cyclic service. The goal of this assessment w as to estimate the fatigue life of a delayed coke drum through the evaluati on of measured strains and temperatures in the middle portion of the vessel . To achieve this goal, results from a field study and a finite element ana lysis were used to investigate the response of the coke drum under differen t operating conditions. The study showed that under current operating condi tions, fatigue life of vessels reaches 21 years, and it was predicted that small reduction in the initial cooling rates doubles the drum's fatigue lif e. Operators can use the results from this study to help managing their cok e drum life cycle by balancing the need for reliability with production rat es.