The slurrying properties of slurry fuels made of petroleum coke and petrochemical sludge

Petroleum coke and petrochemical sludge are the two main by-products of the petroleum chemical industry. They can be disposed and utilized efficiently and cheaply in the form of petroleum coke–sludge slurry (PCSS). The high-quality slurry fuels of low viscosity and good stability can be prepared by petroleum coke and petrochemical sludge, making use of their complementary advantages during the slurrying process. The properties of slurryability, rheology, stability and fluidity were analyzed. The results showed that the fixed-viscosity solid concentration (SCfv) decreased obviously with increasing the sludge mixing proportion (SMP). SC1000, the solid concentration corresponding to 1000 mPa s, and SC1500, corresponding to 1500 mPa s, of petroleum coke–water slurry (PCWS) was 69.04% and 70.51% respectively when no sludge was added, whereas they decreased 8.42 and 8.54 percentage point when SMP = 6.5 wt.%, and further decreased to 51.98% and 53.81% respectively when SMP = 26 wt.%. The flow behavior of slurry was changed from shear-thickening to shear-thinning after adding petrochemical sludge, and the pseudoplastic behavior was enhanced with increasing either the solid content or SMP. The rheological characteristics fitted perfectly the Herschel–Bulkley model (R2 > 0.998). Moreover, the sludge produced a significant effect to improve slurry stability.

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► The fixed-viscosity solid content of slurry decreases sharply with increasing SMP.
► Sludge changes the rheological behavior of PCWS from dilatant to pseudoplastic.
► The slurries show higher levels of shear-thinning behavior with increasing SMP.
► Petrochemical sludge greatly enhances the stability of the PCSSs.
► Loose microstructures and hydrophilic groups lead to poor slurryability of sludge.