Session: 03-05-01 New Inspection Technologies and Facilities II

Paper Number: 133995

133995 - Vaporization-Induced Vibrations Affecting a Crude-Oil Storage Tank and Its Piping System 

Abstract: 

A crude-oil storage tank experienced noticeable vibrations as it was being filled. The crude-oil was considered volatile as its vapor pressure was near the atmospheric pressure.  This caused the system to experience unsteady phase change during different stages of the filling process. Possible causes for the problem were investigated using Computational Fluid Dynamics (CFD) followed by Finite Element Analysis (FEA) simulations which analyzed the integrity of the storage tank’s components and its piping system. The sequence of simulations was designed on a troubleshooting basis since the real-life cause of the vibrations problem was unknown. The resulting Fluid-Structure Interaction (FSI) model started by considering three CFD scenarios. First, investigating the multi-phase flow through the tank’s piping system at a low fill level. In this scenario, all the tank’s components including the piping system would experience a multiphase flow. Thus, it was important to investigate if the unsteadiness stemming from the multiphase phenomenon in the piping system could cause mechanical vibrations in the piping/tank connections which consequently could shake the tank itself. The multiphase flow in the piping system manifested itself as a stratified flow with insignificant unsteadiness, which eliminated the possibility of the first scenario to be the cause of the vibrations problem. Second and third scenarios investigated the effects of phase-change inside the tank at intermediate and high fill levels, respectively. In these two scenarios, the liquid inside the tank would be flashing at a certain height governed by the oil’s vapor pressure. The phase transition in this unsteady event was captured in the CFD model and its resulting forces on the tank’s components were transferred to the FEA problem. These forces exhibited strong unsteadiness accompanied by high force magnitudes acting on the tank’s floating roof. The FEA model following the CFD simulation showed that this floating roof which was connected to the tank’s shell by springs experienced high vibrations due to the flashing event which could be noticed in real-life observations; however, their respective dynamic stresses were found acceptable.

Presenting Author: Ahmed Bayram Wood PLC

Presenting Author Biography: Ahmed Bayram is currently a CFD consultant at Wood PLC. He obtained his PhD in computational mechanics from the University of Calgary mechanical engineering department where he developed novel finite-element based formulations for modelling multi-phase, multi-fluid flows on moving hydrodynamic objects. His experience includes aerospace, marine, and energy applications with emphasis on the modelling perspective. He has worked on multiple advanced projects with Wood PLC involving FSI and complex multiphase systems.

Authors:

Ahmed Bayram Wood PLC
Ehsan Askarimahvelati Wood PLC
Christian Chauvet Wood PLC
Chris Harper Wood PLC