Combined removal experiment of multiple impurities from W/O emulsions under high frequency pulsed electric field: Study on laws of desalination, decalcification, and deacidification

Abstract

Electrocoalescence is widely used to dehydrate crude oil, but impurities in crude oil are extremely complex, which greatly weaken the effect of dehydration. To understand the coupling law of various impurities, a static demulsification experiment was conducted under a high frequency and high voltage pulsed electric field to investigate the effects of electric field parameters (voltage, frequency, pulse width ratio), emulsification strength, electrocoalescence time, water content, acid value, injection alkali ratio, calcium content, decalcification agent concentration and removal process on desalination, decalcification, and deacidification. The results showed that the desalination and decalcification rates varied synchronously with the electric field parameters and water content. Additionally, the desalination and decalcification rates decreased with the emulsification strength, alkali injection ratio, acid value, and calcium content. Further, they increased first and then decreased with decalcifier concentration. The deacidification rate did not vary with the electric field parameters, but it strengthened with the water content and alkali injection ratio. Conversely, it decreased with the acid value, calcium content, and decalcifier concentration. Additionally, it increased first and then decreased with the emulsification intensity. The best removal procedure is deacidification followed by decalcification. These findings are helpful to achieve the combined removal of various impurities in crude oil.