克拉玛依减渣热转化前后的溶解度参数研究

The solubility parameters are important in removal of pitch by solvent and the deposition of coke during transportation of asphaltene and petroleum processing technology. The thermo-cracking of Karamay vacuum residue （VR） was carried out to find the optimum condition at which the VR was thermally cracked deeply without the coke formation. The VR and the cracked residue after distillation at 500 ℃ (Re VR) were separated by supercritical fluid extraction and fractionation (SFEF) technique. The narrow fractions and non-extractable end-cuts were obtained accordingly. Each residue and their narrow fractions were characterized by average molecular weight, carbon residue, elemental contents (CHNS), metal contents and SARA composition (saturate, aromatic, resin and asphaltene). The solubility parameters of two end-cuts were determined by measuring the solubility in a series of toluene-pentane solvent mixtures, and then the solubility parameters of the fractions were calculated according to the properties. Compared with VR, the SFEF fractions and end-cut of Re VR have more unfavorable properties such as lower H/C ratio, more content of nitrogen and metals. Although the end-cut occupies only 10.4% of Re VR, it enriches most part of the impurity. The solubility parameters of the end-cuts from VR and Re VR are 18.27 MPa1/2 and 19.79 MPa1/2. The coke deposition in the processing of vacuum residue was studied in view of solubility parameter. The difference of solubility parameter between end-cut and the extractable fraction is the key to affect the stability of vacuum residue. When the difference amounts to 6.37 MPa1/2, coke will deposit under the conditions of thermo-cracking of Karamay vacuum residue.