Transformation behaviors of vanadium and nickel during petroleum coke and coal co-gasification

The transformation behaviors of vanadium and nickel during petroleum coke co-gasification with coal may cause ash-related fouling, slagging, and corrosion problems. In this work, we investigated the evolution of occurrence modes, volatilization behaviors, and speciation of vanadium and nickel in the process of steam co-gasification of petroleum coke and coal over the temperature range of 1100-1500 degrees C. The results showed that the main chemical states of vanadium and nickel in raw petroleum coke were organic matter and "stable forms", of which vanadium and nickel associated with organic matter were thoroughly converted into other chemical states. The volatilities of vanadium and nickel in petroleum coke increased slightly from 1100 degrees C to 1500 degrees C, however the addition of coal inhibited their volatilization behaviors. Moreover, residence time had little effect on the release of vanadium and nickel. The crystalline phases of vanadium-bearing species, i.e., vanadium trioxide and coulsonite, as well as those of nickel-bearing species, i.e., nickel sulfide and elemental nickel, were formed in high-temperature ash. In addition, the diffraction peaks corresponding to another vanadium species, calcium orthovanadate, were found in the high-temperature ash of SX40%/HB60% with a coal content of 60 wt.%.