Distribution of Vanadium, Nickel, and Other Trace Metals in Soot and Char from Asphaltene Pyrolysis and Gasification
2016
Kurian, Vinoj | Gupta, Rajender
Vanadium (V) and nickel (Ni) are the most abundant and troublesome metals present in oil sands. During upgrading of the oil sand bitumen, these metals become concentrated in the heavier fraction asphaltenes. Any thermochemical conversion of asphaltene causes the release of these trace metals, and their distribution in the products poses concerns with toxicity, corrosion, and fouling. The pyrolysis, partial oxidation, and steam gasification experiments of asphaltene were carried out in an electrically heated atmospheric entrained-flow reactor, and the products char and soot are analyzed for the trace metal content. It is observed that the main metals present in the char and soot are V and Ni. During pyrolysis, with an increase in the temperature, the quantity of V and Ni present in char decreases as a result of the increased liberation into the gas phase. However, more liberated V and Ni were not captured by soot formed in the same experiment. During partial oxidation of asphaltenes, an increase in the stoichiometric oxygen content decreases the soot yield. The V and Ni contents in both the char and soot decrease with an increase in the stoichiometric oxygen ratio. The V content increases with the increase in the steam/fuel ratio in both char and soot obtained from steam gasification. With the increase in the steam/fuel ratio, the Ni content slightly decreases in char but increases to more than double in soot. Understanding the interaction of inorganic matter with char and soot will help in solving post-gasification fouling and erosion problems.
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