Study On Structural Parameters Optimization Of End Cover Of Final Polymerization Kettle Used In Three-reactor Configuration

End cover plays a vital role in Final polymerization kettle for three-reactor configuration. End cover with jacket belongs to the non-standard pressure vessel part, so it would result in the conservative design according to original standard and the increasing of material and transport cost. As a result, it is significant to study on structural parameters optimization of end cover. The thesis mainly do research on the structure optimization based on the modern structure design method and reference on the product of company. The major research work is as follows:(1) The parametric finite element model is built based on the parametric modeling theory; To get the rational boundary condition, the load situation of end cover under the working environment is analyzed; Compared the theoretical value with the calculated value by finite element analysis tool under simplified model and single mechanical load, the error is relatively small so the reliability of simulation method is verified.(2) Respectively calculating the stress distribution of the end cover on the mechanical load, temperature load and mechanical load-thermal coupling by finite element software-ANSYS, thermal stress is relatively larger in actual working environment. The hazardous area is mainly concentrated in the transition area between the upper and lower seal plate and other components so that 5 research paths are determined. According to pressure vessel strength assessment criterion, the stress classification theory and stress linearization method, the stress intensity of end cover based on the research paths is checked, and find the primary local membrane stress, as well as the sum of primary and secondary stress are in accordance with corresponding category of allowable stress.(3) The main structure parameters—the thickness of the upper and lower seal plate as well as the number of structure support are determined, and stress changing law of each path with the change of the structure parameters is researched, and two schemes—optimize thickness of upper and lower seal plate under 8 structure supports and 12 structure supports are put forward. Setting a reasonable objective function, design variables and state variables, two optimization results of different structure supports are concluded. According to pressure vessel strength assessment criterion, the scheme of 8 structure supports is more reasonable. Compared with the original design scheme, the optimized scheme has a 7.48% reduction in weight and reduces the complexity of the structure.