Abstract: The upsizing of hydrogenation reactors has led to a significant increase in the demand for large-diameter openings in reactor shells. Compared with traditional head openings, the shell opening structure is subjected to worse stress conditions and is prone to forming failure-prone zones under high-temperature creep. Taking the 2.25Cr-1Mo-V steel hydrogenation reactor shell-nozzle structure as the research object, this paper adopts the Omega creep constitutive model to carry out simulation research on creep damage evolution. The influence laws of opening diameter (600~1000 mm) and operating temperature (444~474 ℃) on creep damage accumulation are analyzed, and the effects of nozzle inner fillet radius (25~100 mm) and nozzle wall thickness (290~390 mm) on opening reinforcement effect are investigated from the perspective of structural design. The results show that the maximum Mises stress zone does not coincide with the location of maximum creep damage; the maximum stress value and its location hardly change with time, while both the magnitude and location of creep damage have obvious time dependence. This indicates that the maximum stress cannot be used as a substitute for the maximum creep damage as the failure criterion in creep strength and life design. The increase in opening diameter and temperature both significantly accelerate creep damage, and a 10℃ increase in temperature can reduce the structural creep life by about 50%. The nozzle inner fillet radius has a limited control effect on long-term creep damage, while increasing the nozzle wall thickness can significantly inhibit the development of damage. The research results clarify the creep damage evolution law of the shell opening structure of large-scale hydrogenation reactors, confirm the necessity of creep damage analysis, and provide a theoretical basis for the opening reinforcement and safety design of equipment.

Key words: hydrogenation reactor, creep damage, Omega constitutive model, finite element simulation