Study On Physical Properties Of Low Carbon Steel 20g And The Deformation Mechanism Of Coke Drum

Coke drum is the key equipment of delayed coking device in petrochemical industry. Due to the severe service conditions, once occurring failure will result in the serous consequence such as personal casualty and tremendous economic losses. It has practical meaning and economic value to prolong the service life of coke drum and its safe and stable operation in a longer period. Base on the mechanical property ,this article regards coke tower of delayed coking workshop of Changling Refining and Chemical Works as the research object,and accomplished of following content: Based on the analysis and the experimental studies of mechanics performance of low carbon steel 20g, especially the change of mechanical property such as the modulus of elasticity and yield strength, and the corresponding relationship between the degree of pearlite spheroidization and the material mechanics performance. This article also presents theoretical formulas of deflections internal stresses and thermal stresses in cylindrical shells subjected to axial-symmetrical temperature distributions. The transient heat transfer between the drum wail and cooling water rising up with steady rate was simulated numerically using FEM, and the time history of the stress and strain fields were also acquired with direct coupling method. The calculation results indicate that along with the decrease of modulus of elasticity and yield strength, the loin-drum deformation is unavoidable in coke drum operation,which is the result of the development of material degradation, the decreasing of the modulus of elasticity and yield strength, and the difference in intensity and stiffness welding seam and low carbon steel 20g. As the accumulation of plastic deformation, and under the effect of so great heat stress, the local yield is produced in the heat affected zone of welds and then developed and accumulated, leading to the loin-drum deformation of the coke drum.