A Design Approach For Creep Fatigue Evaluation Of Hydrogenation Reactor Made Of 2.25Cr1MoV Steel

Hydrogenation reactor suffers from a combination of high temperature, high pressure and cyclic loads in the process of service, and the effects of creep fatigue interaction and thermal stress must be taken into account in design. At present, there are few creep fatigue interaction design methods of high temperature component and these methods are very complicated to use. ASME code case 2605 provides a creep fatigue life design method for hydrogenation equipment made of 2.25Cr1 MoV steel based on Omega creep damage model. In this paper, different failure modes of hydrogenation reactor are considered in the design, a design example of the joint of cylinder and nozzle is introduced to conduct life design under creep fatigue interaction. Meanwhile, the skirt is optimized to reduce the thermal stress. This study has important significance on the design and safe operation of hydrogenation reactor or other high-temperature vessels and pipeline.Omega creep method can be used to assess the remaining life of equipment in high temperature service. This paper introduces the method of Omega creep damage method and how to obtain Omega parameters experimentally. Meanwhile, creep tests at 455? under different stress levels were conducted, and Omega creep method is used for the remaining life prediction of the samples. The prediction results show that when the samples enter the third stage of creep, remaining life predicted by Omega method is in good agreement with the experiment results. From Omega creep formulas in the ASME Code, we can figure that multiaxial damage parameter ?m decreases with the increase of temperature and stress. While multiaxial factor Kt is greater than 0.5, the multiaxial damage parameters ?m grows rapidly.With the finite element analysis software ANSYS, the elastic and inelastic analysis methods are used to check the strength of the joint of cylinder and nozzle structure of hydrogenation equipment. The results show that the strength check meets the requirements. Then creep fatigue life of the structure is checked using the method of ASME case 2605, and the effect of operating temperature and pressure on the design life is discussed. The results show that creep fatigue damage evaluation meets the safety requirements, and the joint of cylinder and nozzle appears stress concentration. Due to creep strain, the stress value and the rate of creep damage accumulation decrease with the increase of creep time. At the same time, the creep damage increases with the increase of operating temperature and pressure. In addition, the fatigue stress amplitude has greater influence on the life of structure. According to the results, some improvements on creep fatigue life of structure are proposed.The thermal stress of skirt structure of hydrogenation reactor is analyzed and optimized design of the size is conducted. The results show that the thermostat in the skirt can effectively reduce the thermal stress. The increase of thermostat height and the fillet can effectively reduce the thermal stress.