Liu Daoyin

Effect of Operating Conditions on Discharge Characteristics of Petroleum Coke Powder from a Top-Discharge Blow Tank at High Pressure

Discharge experiments of petroleum coke powders were carried out in a pilot-scale top-discharge blow tank at high pressure. The effects of operating conditions (including fluidizing gas flow rate, blow tank pressure, differential pressure between blow tank and receiving tank, supplementary gas flow rate) on solid discharge rate and solid loading ratio were investigated. The results indicate that the maximum solid discharge rate corresponds to the most effective fluidization of the powders near the riser inlet when the fluidizing gas flow rate reaches a critical value. The solid loading ratio shows the same variation tendency as solid discharge rate with increasing fluidizing gas flow rate, which first increases then decreases. Increasing blow tank pressure can improve the fluidization of powders in the tank, which contributes to the increase of solid discharge rate; however, it would not change the basic discharge law. As the differential pressure between blow tank and receiving tank increases, the solid discharge rate increases, while the solid loading ratio first increases then decreases. Solid discharge rate and solid loading ratio both decrease as supplementary gas flow rate increases. A modified solid discharge rate prediction model is proposed for the top-discharge blow tank at high pressure with errors below ±12%.

Effect of powder properties on discharge characteristics of cohesive carbonaceous fuel powders from a top discharge blow tank at high pressure

Abstract Discharge experiments of two cohesive carbonaceous fuel powders (anthracite coal and petroleum coke) were carried out in a top discharge blow tank experimental system with design pressure up to 6.4 MPa. The effects of powder properties (particle size and powder category) on the discharge characteristics (including solid discharge rate, solids loading ratio, and discharge stability) from the top discharge blow tank at high pressure were investigated. Meanwhile, shear tests with a ShearTrac II shear tester were performed to investigate the flowability of these two cohesive powders. The results indicate that there exists a near-linear relationship between major consolidation stress and flow function (FF). As particle size decreases, the values of FF decrease and powder flowability becomes worse. However, as particle size decreases, the particle suspension velocity decreases correspondingly, and the gas permeability becomes worse and gas maintain ability becomes better, which contribute to higher solid discharge rate and better discharge stability, whereas solids loading ratio may have opposite variation tendency. Compared to petroleum coke with similar particle size, anthracite coal has better flowability and can obtain higher solid discharge rate and solids loading ratio, as well as better discharge stability. During the discharge processes of petroleum coke, it was found that as the number of discharge experiment increases, the discharge stability decreases correspondingly. After petroleum coke being discharged continuously for 4–6 times, the discharge process could not start again, adhesion phenomena of petroleum coke to the wall of conveying pipelines could be observed.