Title : CFD simulation of crude petroleum boiling process inside reboilers
Abstract:
An advanced coupled simulation has been performed in order to analyze the performance of re-boiling process of crude petroleum flowing inside reboilers. This work includes analysis of fire heater and crude boiling process. The proposed model is composed from Heptane fire heater and a reboiler. The convective and radiative heat flux produced from burner is transferred to the crude oil flowing inside the pipe. The proposed computational model is composed of two phases — Simulation of fire by using Fire Dynamics Simulator software (FDS) version 5.0 and then a Nucleate boiling computation of the crude oil. FDS code is formulated based on CFD of fire-driven fluid flow. The FDS numerical solution carried out using Large Eddy Simulation (LES) method. FDS software calculates simultaneously the temperature, density, pressure, velocity, and chemical composition within each numerical grid cell at each discrete time step. It also calculates the temperature, convective and radiative heat flux. The thermophysical properties (such as: thermal conductivity, heat capacity, surface tension, viscosity) of the crude oil were estimated by using empirical correlations. The thermal heat transfer to evaporating two-phase crude oil mixture occur by bubble generation at the wall (nucleate boiling) has been calculated by using Chen correlation. It has been assumed that overall convective heat transfer coefficient is composed from the nucleate boiling convective coefficient and the forced turbulent convective coefficient. The former is calculated by Forster Zuber empirical equation. The latter is computed from the Dittus-Boelter relationship. This work can be further extended to include also the structural integrity aspects of the reboiler metal pipe by using COMSOL Multiphysics software.
