Influence of heavy oil composition structure on the rheological properties of coal-oil slurry
Xinjiang,with abundant low-rank coal and heavy oil resources,holds significant potential for the coal-oil co-liquefaction in-dustry.However,poor fluidity of heavy oil considerably hinders its development.To examine the impact of the compositional structure of heavy oil on the rheological properties of coal-oil slurry,in this work,five types of heavy oils with distinct properties and two types of in-dustrial circulating solvent oils were selected,and the variation in the rheological properties of the Shangwan coal-oil slurry was investiga-ted.In addition,the compositional structure of the vacuum residue heavy oil was regulated via pre-hydrogenation.Based on the analysis of the composition,structure,and rheological properties of heavy oil,the influence of the compositional structure of heavy oil on the rheolog-ical properties of coal-oil slurry was revealed.The results indicate that heavy oil in its original state belongs to the Newtonian fluid.How-ever,the addition of coal powder promotes the transform into a pseudoplastic fluid,displaying shear-thinning characteristics.High content of resin and asphaltene components in heavy oil leads to high viscosity of the formed coal-oil slurry.In addition,the rich thixotropic struc-ture within the system makes the non-Newtonian fluid characteristics more pronounced.The pre-hydrogenation of vacuum residue heavy oil significantly decreases the viscosity of the resultant coal-oil slurry.Notably,the viscosity of the coal-oil slurry by using pre-hydrogen-ation heavy oil at 380 ℃ for 2 h decreases to 451 mPa·s at 135 ℃.Pre-hydrogenation facilitates the breakdown of long chains in vacuum residue oil into short-chain hydrocarbons,the resin and asphaltene components in vacuum residue oil are transformed into saturated and aromatic components,thereby inhibiting the formation of micelles and reducing the viscosity of the coal-oil slurry.In particular,after pre-hydrogenation at 380 ℃ for 2 h,the resin content was decreased by about 21％compared to the untreated sample,the weight average mo-lecular weight declines to 1 594 Da,and the H content at β position of the aromatic ring increases by about 20％.
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