克拉玛依减渣热转化前后的溶解度参数研究

Solubility parameters of Karamay vacuum residue and its thermocracking residue

对克拉玛依减渣进行适度热转化,确定了其裂解深度最大且不结焦的条件。利用超临界萃取分馏技术,将克拉玛依减渣及其热转化残渣油分离成一系列窄馏分和萃余残渣,对窄馏分及萃余残渣的性质(相对分子质量、密度、残炭、C、H、N、S元素和金属元素等)进行了表征。用改进的方法测定了萃余残渣的溶解度参数,并根据性质计算了各个窄馏分的溶解度参数,克拉玛依减渣及其热转化残渣油萃余残渣的溶解度参数分别为18.27MPa1/2和19.79MPa1/2;从溶解度参数的角度解释了渣油加工过程中的分相、结焦等问题。

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°C (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.