Transformation Characteristics Of Vanadium And Nickel Of High Sulfur Petroleum Coke During Gasification

With the rapid development of the global economy,energy consumption is increasing dramatically.Deep processing of inferior and heavy oils with high sulfur content leads to a continuous increase in the production of the by-product of high sulfur petroleum coke.Gasification of high sulfur petroleum coke is an efficient and clean way to meet the requirements of environmental protection.In order to achieve an alternative resolvent for slagging and erosion problems related to Ni and V,the migration mechanism of Ni and V and the evolution characteristics of minerals during petroleum coke gasification were investigated in this paper.The steam gasification experiments of petroleum coke from different sources were carried out in a micro-fluidized bed gasifier,combined with the sequential chemical extraction method described by Tessier.The occurrence and migration mechanism of vanadium and nickel in petroleum coke gasification were revealed.The following conclusions were obtained.Nickel in petroleum coke has various occurrence forms,while vanadium mainly exists in organic matter and residual form.Volatility of Ni is positively correlated with gasification temperature and sulfur content.The V bound to organic matter decomposes at the initial stage of gasification and mainly transforms into residual form.Compared with other forms,the formation of exchangeable V is more obviously affected by temperature.The thermodynamic equilibrium simulations of migration characteristics of vanadium and nickel species in petroleum coke gasification process were also carried out by FactSage software.The results reveal the transformation between Ni₃S₂ and Ni,V₂O₃ and FeV₂O₄,and the content of Fe and S has obvious influence on the transformation of V minerals.Finally,the co-gasification experiments of petroleum coke mixed with synthetic ash were carried out in a high temperature fixed bed gasifier.The evolution characteristics of minerals in petroleum coke ash under gasification conditions were studied.The following conclusions were obtained.The main minerals in petroleum coke gasification ash are feldspar?CaAl₂Si₂O₈?,iron spinel?FeAl₂O₄?,NiO,Ni,SiO₂,Ni₃S₂,FeV₂O₄,V₂O₃ and Fe₃O₄.The increase of gasification temperature is conducive to the formation of low melting point minerals?CaAl₂Si₂O₈ and FeAl₂O₄?.The increase of SiO₂/Al₂O₃ ratio promotes the transformation of FeV₂O₄ to V₂O₃.The increase of Fe₂O₃/CaO ratio inhibits the formation of CaAl₂Si₂O₈ and is conducive to the formation of FeV₂O₄.The increase of V₂O₅/NiO ratio will not change the types of minerals in gasification ash.