Correlations of the Droplet Size-Velocity of the Two-Phase, Air/Liquid Spray Using a Particle-Dynamic-Analyzer

In the heavy oil process industry preheated bitumen and steam are mixed upstream of the feed nozzle and subsequently injected into fluid bed coker reactors via feed nozzles. To achieve high liquid product yields, the bitumen should contact a large number of fluidized coke particles quickly and uniformly. One of the drawbacks of the spray issuing from the nozzle is the potential pulsation within the spray and in the feeding conduit, which is highly undesirable to yield high productivity. These pulsations result in poor atomization and in most instances, a slug of liquid is ejected out of the nozzle. It would be valuable to investigate under which two-phase fluid conditions this pulsation aggravates. It would also be beneficial to examine the detailed spray map with changing air-to-liquid ratio (ALR) by mass and void fraction (α). The average void fraction in the feeding conduit was measured by a pneumatic controlled quick-closing-valve (QCV). The length and diameter of the feeding conduit was 36.8 cm and 6.35 mm, respectively. The experiments were performed using mixtures of air with water at water flow rates of 1.50 to 7.50 kg / min and air-to-liquid (ALR) mass ratios of 0.30 to 9.3%. This study indicates that there exists a strong positive correlation between the droplet diameter and axial velocity at the center of the spray. A positive correlation also exists in between the spray center and periphery. However, a strong negative correlation exists at the periphery of the spray. Knowledge from this study would help the heavy oil process industry to upgrade their heavy oil upgrading process and increase the product yield.Copyright © 2008 by ASME