A New Visual Test Method for the Toluene Insolubles in Petroleum Fractions

Toluene insolubles (TI) are recognized as coking precursors produced at the initial stage of a thermal reaction. The traditional methods can only give the overall yield of TI; however, more detailed information, such as the size distribution and the shape parameters of TI, cannot be provided. In the present work, a new visual test method for the TI in oil products was developed based on the digital microscopic image processing technology and the statistical method. This method can give the overall yields of TI and provide the particle size distribution and the shape parameters. The optimized test conditions were determined by investigating the influencing factors. The calibration results of this method showed that the relative error of volume concentration is 5% and the overall error of particle size distribution is less than 5%. Moreover, the detectable concentration of this method is much lower than that of the traditional methods.