Processo de separação água/óleo usando sistema modular de membranas cerâmicas: modelagem avançada e simulação via CFD.

Abstract

Petroleum is the main source of energy in the world. During its extraction and refining, a large amount of residual water is released, with a high percentage of oil and other chemical compounds highly toxic to the environment and humans. Currently, the water/ oil separation process through membranes is one of the main methods used to treat this produced water, due to its cost-benefit, long working life of the membranes and low energy consumption. In this sense, this work presents an in-depth review of the main processes for treating produced water, highlighting ceramic membranes, the current advancement of this technology and the application of Computational Fluid Dynamics (CFD) in the membrane filtration process. Additionally, a numerical study of the water/oil separation process using porous ceramic membranes was performed with the aid of a structured mesh using the commercial software ANSYS FLUENT® 15.0. A numerical model in steady state, applied to an incompressible fluid, flowing in a turbulent and/or laminar regime inside the separation module, based on the Eulerian-Eulerian approach and the 𝑘�-𝜔� SST (Shear-Stress Transport) turbulence model. The main objective was to numerically study the behavior of the water/oil separation process in the filtration module as a function of the variation in mass flow (ṁ), oil concentration at the entrance (𝐶�0), diameter of the oil particles (𝑑�𝑝�), permeability (𝐾�) and porosity (𝜀�) of the membranes. The results indicate that the model generated and applied adequately simulated the filtration process. The increase from 0.5 to 1.5 kg/s of ṁ significantly influenced transmembrane pressure (Δ𝑃�), raising it approximately 6.71 times. This high-pressure gradient between the external and internal surfaces led to a greater filtration flow. Both variations in 𝑑�𝑝� and 𝜀� of the membranes did not influence the module filtration characteristics. In turn, the higher the 𝐾� of the membranes, the lower the Δ𝑃�, the greater the average oil concentration in the permeate and concentrate outlets, the greater the average oil flow in the permeate outlets, as well as, the greater the average velocity of the permeate flow mixture at the permeate outlets and lower the average oil flow at the permeate outlets. These results showed that the filter separator has a good potential for water/oil separation process.