Corona Discharge Assisted Oil in Water and Water in Oil Separator

Technology      

The present technology uses electrodes in order to establish corona discharge, a sharp electrode (emitter) and a blunt grounded electrode (collector). A gaseous medium is also needed, which can be air or other gases either below, at, or above atmospheric pressure. The blunt grounded electrode is placed in the emulsion, while the sharp end is in contact with the gaseous medium. When a potential difference between a sharp and blunt electrode is applied, above the corona discharge threshold, the imposed electrical field becomes strong enough around the sharp tip, resulting in partial ionization of the surrounding neutral gaseous molecules. The cloud of ions are generated and accelerated towards the low potential region.   

Problem Addressed

Methods of emulsion separation are very diverse and challenging:Gravity: Although the most common method, in order to separate emulsions, they must be pretreated with chemicals and heated after gravity separation. Physical: These methods can include heating, centrifugation, filteration, ultrafiltration and membranes, and reverse osmosis. However, these do have limitations in capital costs of high-energy consumption for large volumes and degeneration of the membrane coating materials.Electrostatic: Energy consumption is low for the destabilization of the emulsion, however, this method suffers severe limitations.  In conventional electrocoalescencers, both electrodes are immersed in the emulsions. This method will not function properly when the content of water in the emulsion is too high. Additionally, electrostatic discharge may introduce dangers of explosions, corrosion of the electrode or electrode coatings, and increase the contamination due to the chemical decomposition of the oil around the electrodes.  

Advantages 

• The high voltage electrode has no contact with the emulsion given that the voltage drop occurs between the electrodes, thus significantly reducing the chance of arc or electrostatic breakdown
• Corona discharge can inject large volume charge densities in the emulsion so that the strong non-uniformity of the electric field in the non-homogenous emulsion medium may increase the chance of coalescence  

Publications

Self-Similarity of Contact Line Depinning from Textured Surfaces. Nature Communications 4, (February 2013): Article 1491.