Abstract

During certain maintenance or capacity-building tasks of operating refinery equipment (e.g. reactors, regenerators, etc.), it is often necessary to remove and subsequently hoist the upper hemispherical head of the equipment. In the lifting phase, the head must be maintained in such a way that the welding between it and the body of the vessel is feasible to perform. This welding can be performed if the deformations in the periphery of the head base are small, otherwise additional adjustment processes must be carried out that can delay the commissioning of the equipment inducing economic losses. In the planning of the hoisting, the determination of the position and the number of ears to be used is important, this will affect the distribution of the loads and consequently the deformations that the periphery of the head will experience. This paper presents a finite element analysis of a hemispheric head of a regenerator during the lifting process. The head is subjected to the action of gravity loads and external loads produced by structural elements connected to the head. In the lifting process, the head is also subjected to the tension forces generated by the lifting cables. From the numerical model, a parametric study was carried out to determine the optimal arrangement of the hoisting clips taking into account the deformations in the periphery of the head base, in order to guarantee the welding process with the body of the vessel. Additionally, the use of a stiffening ring and its influence on the deformation of the head were analyzed.