Experimental and numerical simulation of charge injection effect of sawtooth electrostatic elimination electrodes in oil products

Objective Low-conductivity oil products are prone to electrostatic accumulation due to friction during pipeline transportation, which poses a risk of fire or explosion. To effectively eliminate static electricity, a charge injection device composed of sawtooth electrodes has been developed. This device injects charges with an opposite polarity to the electrostatic charges present in the oil products. By neutralizing these electrostatic charges, the risk of electrostatic accumulation can be mitigated.

Methods After establishing a charge injection experiment platform specifically for low-conductivity oil products and preparing small-sized sawtooth electrodes, experiments were conducted to analyze the charge injection effect of the electrodes at various twist angles in oil products with different physical properties. Numerical simulation was also conducted on charge injection under different twist angles to further investigate factors influencing the charge injection effect. Further analysis clarified how different factors, including voltage and oil product flow rate, affect the amount of charge injected. Additionally, the sensitivity of these factors on the charge injection effect was quantified through sensitivity analysis.

Results The sawtooth electrodes were identified as effective in increasing the charge density of oil products, with a notable influence on the charge injection effect associated with their twist angles. The optimal charge injection effect was observed at a twist angle of 720° , resulting in an average charge density of 0.00119 C/m³ at the outlet of the charge injection device. While the influence of varying physical properties of the oil product on the charge injection effect was noted, the specific mechanism has not been fully clarified. Increasing the oil flow rate led to a diminished charge injection effect, suggesting that an optimal oil flow rate is below 0.5 m/s. In contrast, an increase in voltage resulted in a significant improvement in the charge injection effect. However, given the potential risk of oil breakdown associated with excessively high voltage, the voltage should be maintained at approximately 15 kV. The sensitivity analysis indicated that voltage had the largest influence on the charge injection effect, with a sensitivity value of 0.64182, followed by the twist angle with a sensitivity value of 0.25539. The analysis also revealed that the oil flow rate had the smallest influence, with a sensitivity value of only 0.10709.

Conclusion This study demonstrates the efficacy of sawtooth electrodes in reducing the risk of electrostatic accumulation during the pipeline transportation of low-conductivity oil products. Controlling voltage and optimizing the electrode structure provide essential technical support for ensuring electrostatic safety during oil product transport. Future research should focus on the following aspects: the charge injection mechanism under high flow rates; the influence of oil physical properties on the charge injection effect; the applicability of electrodes under varying pipe diameters and flow conditions.