Molecular Dynamics Simulation of Pulsed Electric Field O/W Emulsion Demulsification

doi:10.7503/cjcu20210139

Abstract

Abstract:

The aggregation behavior of two heavy oil droplets in an O/W emulsion system in a pulsed electric field was studied by molecular dynamics method. By changing the simulation parameters of duty cycle， the aggregation of oil droplets under certain electric field intensity and the relation between electric field intensity parameters and duty cycle parameters during electric field demulsification were discussed. At the same time， the charge distribution and the accumulation mechanism of oil droplets in the electric field were explained from the microscopic point of view by analysis methods of electrostatic potential distribution， interaction potential energy and adsorption structure statistics. The simulation results showed that：（1） the duty cycle could be adjusted to control the applied time of electric field. Oil droplets accumulate at electric field in the range of 0.40—0.75 V/nm， and the duty cycle decreases with the increase of electric field intensity；（2） the oil droplets deforme and the charge is polarized in the electric field， and the negatively charged asphaltene molecules guid the droplet to move in the opposite direction of the electric field；（3） the asphaltenes are at the interface of two oil droplets in the process of aggregation without electric field， and van der Waals action is the main force for oil droplets' aggregation. Meanwhile， asphaltenes at the interface of oil droplets form π-π binding conformation with surrounding molecules， which enhances the interaction between oil droplets.

Key words: Bidirectional pulsed electric field（BPEF）, Heavy oil droplet, Electric field intensity, Duty cycle, Molecular dynamics

CLC Number:

O641

TrendMD:

LIU Shasha, ZHANG Heng, YUAN Shiling, LIU Chengbu. Molecular Dynamics Simulation of Pulsed Electric Field O/W Emulsion Demulsification[J]. Chem. J. Chinese Universities, 2021, 42(7): 2170.

Figures/Tables 10

References 29

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Component of oil		Number
Asphaltene	Asp1	4
	Asp2	4
Resin	Resin 1	5
	Resin 2	5
	Resin 3	5
	Resin 4	5
	Resin 5	5
	Resin 6	5
Hydrocarbon	Benzene	13
	Cycloheptane	35
	Cyclohexane	22
	Heptane	29
	Hexane	32
	Nonane	40
	Octane	34
	Toluene	35

Component of oil		Number
Asphaltene	Asp1	4
	Asp2	4
Resin	Resin 1	5
	Resin 2	5
	Resin 3	5
	Resin 4	5
	Resin 5	5
	Resin 6	5
Hydrocarbon	Benzene	13
	Cycloheptane	35
	Cyclohexane	22
	Heptane	29
	Hexane	32
	Nonane	40
	Octane	34
	Toluene	35

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