Ammonia Synthesis Tower Multilayered Cylinder Stress Analysis

Ammonia converter is chemical plant works in the high temperature, high pressure and causticity environment. The ammonia converter canister might adopts multi-layer tied up structure as a typical high pressure vessel to increase material utilization ratio and save cost. But what is the stress distribution of the multi-layer plate forced under prestress and what is the affection of tied up steel plate number to the stress distribution are important problems of the ammonia converter canister manufacture and operation in the future. At present, it is rare to find the analysis about stress and intensity of the multi-layer tied up high pressure vessel, and prestress influence was almost not considered by them. Based on the elasticity and finite element method(FEM) theory, the dissertation researches on the stress analysis and intensity evaluate of a multi-layer tied up ammonia converter canister, and the different stress distribution under different operational mode. The results will supply reference for the design and manufacture of ammonia converter canister and other similar structure high pressure vessel.The article focuses on the following aspects of work:(1) Study the structural feature and manufacturing process, establish tied up prestress calculation mathematical model, solve tied up layer prestress deduction approach and mathematical calculation formula, and get magnitude of stress of each tied up canister steel plate stress finally.(2) Build up 3D entity model according to the structure design requirement and materiel property of ammonia converter. And calculate the stress distribution under the operated pressuer (non-prestress) operational mode and stress distribution nearby the welding line of canister with end enclosure by using FEM.(3) Solve the canister total working stress after cooperating the operated pressuer stress and the tied up prestress.(4) Evaluate the canister's total working stress, improve and optimize the structure.(5) Design a usefull package analysis calculation program of multi-layer tied up canister prestress; it makes things convenient for engineering staff.To sum up, the study identifies the ammonia converter canister stress distribution during manufacture and working process. Using numerical calculation method and FEM for the modeling analysis to get stress. It provides a new way of thinking and methods to further improve the ammonia converter canister structure in the future.