Design of an Electrocoalescer Cell for Oil–Water Separation: Comparison of Droplet Distribution

The oil industry faces significant challenges in the treatment and disposal of oily effluents, as large volumes are generated during refining. Oil–water separation methods have received increasing attention, particularly electrocoalescence, which uses external electric fields to induce the coalescence of water droplets in oil–water emulsions, favoring separation. This work presents an experimental and simulation study focused on the design of an electrostatic oil–water separation cell, evaluating the influence of the electric field on the droplet size distribution.

he experimental setup conditions are as follows:

Simulation tool: FEMM 4.2 to define the electrode shape; emulsion composed of 60% mineral oil + 40% distilled water with dye. Applied electric field: 1 kV, 1 kHz, for 1 minute; droplet size analysis using ImageJ software.

The experimental comparison is as follows:

Control (C1–C4): without direct action of the electrodes. Electrodes (EDGE1–EDGE4): regions under the influence of the electric field.

According to the results, the distribution in the control is the predominance of droplets <1.5 µm, characterizing low spontaneous coalescence; reduction in the frequency of microdroplets (<1 µm); greater presence of droplets between 1.6 and 3 µm; increase in the average diameter to 1.6–2.6 µm; occurrence of larger droplets (>6 µm), absent in the control; Increased separation efficiency due to the reduction of critical microdroplets; greater heterogeneity in the distribution near the electrodes, possibly due to irregularities in the electric field and local turbulence.

The electrocoalescence process proved to be efficient in oil–water separation, promoting increases in the average droplet diameter and reduction in the microdroplet fraction, favoring decantation. Improvement in overall process efficiency compared to the control. However, the observed heterogeneity suggests the need for optimizations in electrode positioning and electric field intensity to standardize the coalescent action.