Study On Conductivity Of Residue During Thermal Process Through In Situ Equipment And The Influencing Factors

The asphaltenes contribute a lot to the conductivity of the residues. During residue processing, there may be an intrinsic relationship between the conductivity and the coking performance, so we firstly constructed an in situ measuring device which can measure the conductivity of heavy oil on-line during thermal process. And it will be of great significance in theory and reality to measure the changes of electrical conductivity of residual oil during thermal reaction and study its relation with coking performance of the system.The in situ measuring device was an autoclave reactor with a pair of parallel electrodes which was home-made in it, and studied the conductivity of Middle East Atmospheric Residue(MEAR), Ta He Atmospheric Residue(THAR) and Sha Qing Vacuum Residue(SQVR) during thermal process. The results showed that the values of conductivity increased firstly, appeared an maximum, and then decreased as the thermal reaction time going on. The viscosity of the SQVR’s thermal reaction was tested using Rheometer, and the results showed that the viscosity of the system decreased gradually with the reaction time; however, the decrease of viscosity would result in the increase of electrophoretic mobility of charged particles, which leaded to the increase of the system’s conductivity. The thermal samples of SQVR were separated into four fractions by liquid-solid adsorption chromatography and the conductivity of the fractions was measured. It was shown that the main conductive material of residue was asphaltene, and during the thermal process, electrical conductivity of asphaltene increased firstly and then decreased, but the conductivity of resin and aromatic decreased by degrees.During the thermal reaction, it exist both cracking and condensation reaction, and the four components transform into each other, so the content of four fractions varied, and the asphaltene, resin and aromatic condensed into coke, which decreased the charged particles in residue, so the conductivity decreased; but with the reaction going on, the viscosity of residue system gradually reduced, which would increase the conductivity. At the beginning of thermal reaction, the effect of the former was less than the latter, so the conductivity of residue increased; but with the reaction going on, the effect of the the former was more than the latter, so the conductivity of residue began to decrease.