doi:10.16186/j.cnki.1673-9787.2021120070

Received:2022/12/21

Revised:2023/03/01

Published:2024/03/25

Remediation of insulating oil contaminated soil by pulsed discharge plasma

CHEN Chongming，GONG Yunqian，ZHOU Huibo，CHE Kai

State Grid Hebei Electric Power Research Institute，Shijiazhuang 050021，Hebei，China

Abstract: Objectives In order to investigate the influence and mechanism of plasma process parameters on the degradation of insulating oil， Methods six factors such as peak voltage，moisture content，frequency，etc were selected to analyzed the oil treatment efficiency on needle-plate pulsed discharge plasma experimental system. Results The results showed that the order of parameters affecting the degradation rate of insulation oil was peak voltage，water content，concentration of insulation oil，air flow rate，frequency，treatment time.The peak voltage should be higher than 10 kV in order to degrade insulation oil，and high peak voltage could increase degradation rate and shorten processing time.The highest degradation rate and energy efficiency could reach 88.13% and 43.71 mg/kJ，respectively.The degradation rate decreased with the increase of insulation oil concentration.The increase of moisture content could promote oil degradation due to the increase of•OH amount.However，high moisture content inhibited soil degradation because the transportation of active ions was limited by the reduction of soil permeability and increase of soil aggregation.An increase in the initial mass fraction of insulating oil can reduce the degradation rate，but when the mass fraction is high，the degradation amount decreases due to the inability of the insulating oil components in the soil inner layer to come into contact with highly active substances.The insulation oil in soil is mainly saturated hydrocarbon before and after treatment，and low-carbon alkanes are easily degraded.The degradation rate gradually decreases with the increase of carbon number.The degradation effect of 4 cyclic aromatic hydrocarbons was better than that of 2-3 cyclic aromatic hydrocarbons.The content of aromatic hydrocarbons above 4 cyclic increased after treatment because of the condensation of small hydrocarbons with benzene rings under high temperature and the formation of polymer aromatic hydrocarbons. Conclusions The research results can provide reference for the study of plasma remediation of insulating oil contaminated soil.

Key words:pulsed discharge；plasma；soil remediation；insulation oil；degradation