Experimental study on viscosity reduction for residual oil by ultrasonic

Abstract

Because of characteristics of large density, high viscosity and poor mobility, the processing and transportation of residual oil are difficult and challenging, viscosity reduction of residual oil is of great significance. In this paper, the effects of different placement forms of ultrasonic transducers on the sound pressure distribution of ultrasonic inside a cubic container have been simulated, the characteristics of oil bath heating and ultrasonic viscosity reduction were compared, viscosity reduction rule of residual oil was experimentally analyzed by utilizing Response Surface Method under conditions of changing ultrasonic exposure time, power and action mode, the mechanism of viscosity reduction was studied by applying Fourier transform infrared spectrometer, the viscosity retentivity experiment was carried out at last. Experiments were conducted using two kinds of residual oil, and results show that ultrasonic effect on the viscosity reduction of residual oil is significant, the higher viscosity of residual oil, the better effect of ultrasonic, ultrasonic power and exposure time are the significant factors affecting the viscosity reduction rate of residual oil. The maximum viscosity reduction rate is obtained under condition of ultrasonic power is 900W, exposure time is 14min and action mode of exposure time is 2s and interrupting time is 2s, viscosity reduction rate reaching up to 63.95%. The infrared spectroscopy results show that light component in residual oil increased. The viscosity retentivity experiment results show that the viscosity reduction effect remains very well. This paper can provide data reference for the application of ultrasonic in the field of viscosity reduction for residual oil.

Ultrasonic and Heat Treatment of Crude Oils

“…The results of the study [44] show that the viscosity of liquids decreases under the influence of ultrasound, and it can be explained by heating and cavitation in the liquid. In this paper, the recommendations set out in [32] were adopted, namely, ultrasonic treatment of oil was compared with heat treatment to the same temperatures.…”

“…Viscosity reduction mechanisms of oil treated by ultrasonic mainly include cavitation effect, mechanical vibration, and thermal effect [32]. It is necessary to investigate the oil heating to the same temperature as it was after the ultrasonic treatment to better understand the mechanism of the effect of ultrasonic treatment of oil.…”

“…It is necessary to investigate the oil heating to the same temperature as it was after the ultrasonic treatment to better understand the mechanism of the effect of ultrasonic treatment of oil. Such a study was conducted in [32]. However, residual oil was used in the experiment.…”

The mechanism of ultrasonic irradiation effect on viscosity variations of heavy crude oil

“…Shi et al [17] hypothesized that ultrasonic irradiation destroyed the ‘cage effect’ of heavy oil samples through the severe cavitation and mechanical vibration, and also damaged the C—C bond, leading to a reduction in viscosity. Huang et al [18] applied Fourier Transform Infrared Spectrometer (herein referred to as ‘FTIR’) to analyze the residual oil samples and reported the largest VRR after ultrasonic treatment. Their researches indicated that the increase in the content of light component alkanes was caused by the high temperature, high pressure, and high speed microjet generated by ultrasonic cavitation.…”

“…Some scholars [16] , [17] , [18] have claimed that ultrasound can break the carbon chains, one of the main reasons for the reduction in viscosity. However, limited research has applied relevant chemical analysis methodologies to prove that the change in the structure of oil samples was caused by a break in the carbon chains.…”