Abstract
In order to ensure the stable operation of the coal tar suspension bed hydrogenation unit, the asphaltene flocculation and the influencing factors of the raw material were studied. The coal tar asphalt initial floc point determination method was studied, and effects of composition molecular properties and structural parameters of heavy oil on asphaltene flocculation phenomenon in coal tar were analyzed. High temperature coal tar A, middle and low temperature coal tar >320 ℃ heavy fraction B and blending coal tar C（churning oil of A and B）were studied. Initial asphalt flocculation point of sample A, B, C was measured by photometer method. Samples were separated into saturates, aromatic, resin and asphaltene fractions. The coal tars and SARA were characterized by element analysis, molecular weight and NMR. The results showed that these three samples were unstable and asphaltene settled in varying degrees. The colloidal stability order was A>B>C. SARA composition and properties played a decisive role on colloidal stability together. Because sample A had highly condensed ring aromatic hydrocarbon, short and less side chains, large ratio of resin/ asphaltene, the aromaticity and molecular weight of SARA were distribution continuously, so asphaltene dispersion was good. Asphaltene flocculation happened extensively of sample C because of the mismatching of compositions and characters of sample A and B.
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