SIMPLIFIED THERMO-ELASTO-PLASTIC ANALYSIS MODELS FOR DETERMINATION OF GLOBAL AND LOCAL STRESSES IN COKE DRUMS

Coke drums are major pressure vessels used in petroleum refineries. In this paper, two simplified analytical models based on thermo-elasto-plastic constitutive theory have been developed to evaluate global and local stresses in coke drums during their operation cycles. The first model considers the temperature and internal pressure cycle experienced by a drum shell element consisting of clad and base steels. The second model is an axisymmetric circular cladding plate model experiencing a non-uniform temperature distribution history. The latter model considers the effects of severe local nonuniform temperature distributions produced by the hot/cold spots appearing randomly in coke drums during the water quenching stage. The predicted results by the simplified models are in agreement with the results obtained from much complicated and time-consuming finite element analysis (FEA) models for the coke drums. Corresponding software packages for application of the two simplified analysis models (SAM) have also been developed. The developed SAM and software could be a more convenient analysis tool for coke drum designers and engineers in comparison to the use of FEA software package.