Redesign and Structural analysis of agitator shaft for reactor pressure vessel

Abstract

Agitator shaft is important component of agitation system used in reactor pressure vessel. Failure of agitator shaft leads to breakdown of whole plant. The existing agitator undergoes deflection; not suitable for uniform mixing of fluid, also time required for agitation is more. One of the major parameter to increase the overall performance of agitator shaft is to reduce deflection. The work is carried out to reduce deflection by optimizing the design or by using different materials like SS, SS304 and SS305. This dissertation work is aimed to redesign existing single impeller agitator shaft by using SS316 material with double impeller. This results in improved overall performance by minimizing deflection of agitator. Redesigned impeller agitator shaft is modeled using CAD modeling software. Stress analysis of the shaft subjected to combined loading was done using FEA software. These results were compared with experimental values observed by company. It is observed that the deflection of redesigned agitator is 0.8375 mm which is reduced by 14.997% than exiting agitator. Redesigned agitator shaft with SS316 material and double impeller reduces deflection by 14.997% to 0.8375mm. Equivalent stress (80.916 MPa) is within permissible limits, improving mixing performance. Selecting another material for agitator increase strength, ductility corrosion resistance. By increasing no. of impellers improves mixing time, provide balancing reduce deformation.