A Study On The Aromatics Separation From Coal Liquefaction Oil And The Temperature-Viscosity Characteristic Of Coal-oil Slurry

Coal liquefaction oil is a good raw material for aromatics production owing to its richness in naphthenic and aromatic hydrocarbons. The solvent separation of aromatics from the coal liquefaction oil can enhance the quality of the oil, and has also been proved to be a new method to product aromatic compounds. The aromatics separation experiment showed that the temperature and extractant/oil ratio were important factors affecting the extraction process, and the selectivity of extractant declined with the increase in temperature and the decrease in extractant/oil ratio. The suitable extractant condition was also found specific to the coal liquefaction oil. A self-designed experimental device was set up to investigate the mass transfer process in the furfural extraction of model compounds. The results showed that the mass transfer rates of n-heptane and tetralin increased with temperature. With temperature rising from40℃to55℃, the ratio of mass transfer rates of tetralin to n-heptane decreased from2.41to1.63, which agreed with the conclusion that the aromatics extraction selectivity decreases with temperature rising. The extraction mass transfer process complied with the assumption of two-film theory and the mass transfer resistance depended on the liquid film resistance. The mass transfer processes of tetralin and n-heptane were endothermic, whose activation energies were107.95KJ/mol and126.50KJ/mol. An experimental study of temperature-viscosity characteristic of coal-oil slurry was conducted. When the temperature was below200℃, the viscosity of coal-oil slurry first decreased with the rise in temperature and then levelled off at13mPa-s at160℃. It was also found that the viscosity of coal-oil slurry decreased with the coal/oil ratio and the water content of lignite coal. The experiment results of thermal dissolution treatment on coal-oil slurry showed that when the temperature was further risen up to300℃, the viscosity of thermal dissolution treated coal-oil slurry increased accordingly and peaked at340℃. The viscosity of the thermal dissolution treated coal-oil slurry at340℃was31mPa-s at the measuring temperature of160℃, which was more than double the viscosity of raw coal-oil slurry.