INVESTIGATION OF THE EFFECT OF TEMPERATURE FIELDS OF DELAYED COKING REACTOR BODIES ON THE STRESS-STRAIN STATE OF THE MATERIAL

Abstract

The article continues to explore the topic of damage to DCR (delayed coking reactors) or coke drums during operation. Based on the temporary localization of damage formation during the cooling stage, the most critical stage of the technological process during the operation of the DCR is determined and a damage mechanism is proposed in the form of the influence of an uneven temperature distribution over the DCR body. The description of method for studying the temperature field on the outer surface of the body of the DCR using original mobile temperature measuring devices is given. The results of research with data on the distributions and actual values of temperature differences along the outer surface of the body of the DCR during operation are presented. The DCR with a material design made of stainless steel was selected as the object of research. The case of damage in the form of cracking of the welded joint of the body during the operation of the DCR with the occurrence of a leak is considered. To justify the occurrence of damage in the form of corrugations, calculations of the stress-strain state (SSS) of the material of the body elements are carried out. The applied finite element complex «ANSYS» is used for calculations. As the initial data for SSS calculations, the results of studies of the temperature distribution over the outer surface of the DCR are used. During the calculations, it was found that at the cooling stage, the greatest stresses in the body material correspond to the level of the yield strength of the material and lead to irreversible plastic deformation with the occurrence of the process of accumulation of deformations (ratcheting process). A comparison is being made with data from foreign studies of the operating conditions of the DCR. As measures to prevent operational damage to the DCR, it is proposed to change the technical requirements for steels for the manufacture of main parts in terms of increasing the level of mechanical properties (tensile strength and yield strength). Recommendations are formulated on the material execution of the DCR, the design and manufacture of the DCR.