Effects of pH on rheological characteristics and stability of petroleum coke water slurry

In this study, the effects of pH on slurrying properties of petroleum coke water slurry（PCWS） were investigated. The slurrying concentration, rheological characteristics and stability of PCWS were studied with four different types of additives at pH varying from 5 to 11.The results showed that the slurrying concentration, rheological characteristics and stability of PCWS all increased at first and then decreased with increasing pH from 5 to 11,and a pH of around 9 was found to be the most favorable acid–alkali environment to all these three slurrying properties. It was also indicated that only in a moderate alkaline environment can the additives be active enough to react with particle surfaces sufficiently to obtain good slurrying concentration and form a stable three-dimensional network structure, which can support strong pseudoplastic characteristics and good stability. An acid environment was a very unfavorable factor to the slurrying properties of PCWS.

Inherent relations between yield stress and stability of bubble petroleum coke water slurry

The stability of petroleum coke water slurry（PCWS） is currently a hot topic. The inherent relationship between yield stress and stability of bubble-PCWS was studied through orthogonal experiments and range analysis in this work. The results showed that the stability of bubble-PCWS was positively related to the yield stress and that the yield stress could be greatly impacted by the operation conditions during preparation of bubble-PCWS. The main factors affecting the yield stress of bubble-PCWS were solid concentration, aeration time and dosage of frother. However, the effects of aperture size of air distribution plates and type of frother on the yield stress were slight within the experimental range. The optimal conditions for the greatest yield stress were as follows： aeration time of 30 min, solid concentration of 65 wt%, frother dosage of0.030 wt% of the air-dried pulverized petroleum coke, aperture size of air distribution plate of 2-5 lm and AOS frother.The yield stress and the pour rate of bubble-PCWS under this optimum operation condition could reach maxima of more than 0.4 Pa and 96%, respectively.

Effects of the physical and chemical properties of petroleum coke on its slurryability

In this study, the effects of particle size distribution （PSD）, chemical composition and pore structure of petroleum coke on the slurryability of petroleum coke water slurry （PCWS） were investigated. Four petroleum cokes were studied, and they showed completely different slurryability. The solid concentration at fixed viscosity （i.e. apparent viscosity of 1000 mPa） （SCFV） of four PCWSs is different from each other, with the highest value of 70.9%, and lowest of 62.1%. The apparent viscosity of the four PCWSs all increased with an increase of the solid concentration. The results showed that the PSD, inherent moisture content, specific surface area and pore volume of petroleum coke were key factors to affect the slurryability. The slurryability was enhanced with increasing PSD range and particle packing fraction, and with decreasing inherent moisture content, specific surface area and pore volume.