Numerical Simulation of Thermal-Mechanical Stress Field of Coke Drum Considering Deformation

The coke drum is subjected to a combination of thermal-mechanical loads during operation, so its safety and reliability must be considered in actual production. In each production cycle, the thermal stress generated by temperature fluctuations in the coke drum is the main cause of structural failure. Based on this, a long-term service carbon steel coke drum was used as the research object and a method was proposed to evaluate the universality of the bulged coke drums in this paper. The details are as follows: firstly, the deformed coke drum was processed into a finite element geometric model by internal laser scanning detection. Then, the thermal mechanical coupled finite element analysis was performed on the two regions with large deformation based on the dynamic thermal boundary method. Next, the stresses and strains of the perfect geometry were analyzed and compared. Finally, the stress and strain distribution levels of different bulging patterns are obtained. These results indicate that the maximum stress and the maximum strain of the deformed region were increased by 35% and 77%, respectively, compared with the perfect geometry. Therefore, when evaluating the remaining life of the coke drums, bulges must be taken into account. Furthermore, this method proposed in this paper can provide guidance and reference for the life assessment of coke drums.

Large-Aperture Real-Time Compensated Collimating Wavefront Error Detection Method

This paper proposes a real-time compensated pentaprism scanning wavefront detection method to achieve real-time compensation for scanning errors occurring during prism movement along a guide rail. The method is based on existing pentaprism scanning wavefront detection technology and it is realized by applying self-collimation-based three-dimensional error compensation. Using theoretical and data analyses of a detection experiment, the reliability of the optimized pentaprism scanning detection method is verified, thus effectively ensuring the reasonable estimation of the interferometry surface measurement uncertainty.