A three-dimensional two-phase flow model with phase change inside a tube of petrochemical pre-heaters

The transport of fluids in industrial units takes place usually inside cylindrical ducts. Multiphase systems flowing inside pipes are very common and many times there are also mass, energy and momentum transfer. Two-phase flow is found in many petrochemical processes, as is the case of preheating furnaces where normally the liquid vaporizes as it flows inside the heater. In the great majority of these heaters, there is a phase change from liquid to gas. The objective of this work is to simulate the two-phase gas–liquid flow of crude oil inside pipes of petrochemical fired heaters with the use of a Computational Fluid Dynamics (CFD) model to be later used in the prediction of coke formation through a thermal cracking model and a ternary solubility diagram for the petrol feed, according to Souza et al. [28]. The CFD free software OpenFOAM was used. There is a growing interest in the use of the OpenFoam project and many successful models have been implemented using this software. New routines were implemented to estimate temperature and concentration inside the tube, taking into consideration the interaction between the phases. To estimate the momentum it was used a phase intensive formulation for dispersed two-phase flow already implemented in OpenFOAM. The temperature profiles were predicted. The k-epsilon model was used to describe the turbulence and a vaporization model was implemented to estimate the phase change. A kinetic reaction net for crude oil with seven lumps was used in order to predict the thermal cracking of the crude oil.