Mechanism on interaction between charged particles and wax crystals of waxy oils under high-voltage electric field

Key words:  waxy crude oil  electrorheological effect  wax particles  charged particle  mechanism

Abstract:

The application of an electric field to the waxy oil near its pour point can significantly improve its cold flowability. The charged particles' accumulation on the surfaces of the wax crystals under the electric field is the essential mechanism of this method. This study aims to investigate the interaction between the charged particles and wax particles. Two types of waxy crude oils with significant difference of viscosity reduction under the action of electric field were selected. Then the apparent viscosity, the impedance, and the lattice parameters of the wax particles were measured. The results show that the impedance of oil 1# increases after the electric treatment, while the lattice parameters of wax particles at the treatment temperature remain unchanged, but they change dramatically after the oil sample is cooled to 2 ℃.Conversely, for waxy oil 2# whose viscosity cannot be reduced by the electric treatment, its impedance does not change after the electric treatment, and the lattice parameters of wax particles are also unchanged after being cooled to 2 ℃. The adhesion of charged particles on the surface of wax particles under the electric field is the essential reason for viscosity reduction. Additionally, the inability of some waxy crude oils to undergo viscosity reduction via electric treatment is due to the self-association of charged particles, which hinders their absorption on the surfaces of the wax particles.