CFD investigation of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser with bottom airlift loop mixer

This paper presents a CFD modeling of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser together with a bottom airlift loop mixer. By extending a validated gas–solid flow model to incorporate feedstock vaporization and 12-lump kinetic model, a three-phase flow and reaction model is established. CFD analysis is performed, and the effects of operating parameters are thus evaluated. The results indicate that the bottom airlift loop mixer causes the hot and the cool catalyst well mix and obtains a uniform catalyst temperature at riser inlet. There exists optimal product distribution, with a maximum light liquid yield at about 30.0 m of up the riser. Product yields are more sensitive to injection angle than to feedstock droplet size and reaction temperature. A catalyst-to-oil ratio in the range of 7–8 and a shorter reaction time of 3.02 s are preferable for a higher light liquid yield.

Hydrodynamics, heat transfer and cracking reaction in a heavy oil riser together with bottom airlift loop mixer are investigated by using CFD method. The bottom mixer causes the hot and the cool catalysts well mix. There exist optimal product distributions in the riser. Product yields are more sensitive to injection angle than to droplet size of feedstock and reaction temperature. A catalyst-to-oil ratio in the range of 7–8 and a shorter reaction time of 3.02 s are preferable for a higher light liquid yield.Figure optionsDownload high-quality image (70 K)Download as PowerPoint slideHighlights
► Well mixing of the hot and cool catalysts is achieved in airlift loop mixer.
► There exist optimal product distributions in the riser.
► Product yields are more sensitive to injection angle than to droplet size of feedstock.
► Catalyst-to-oil ratio and reaction time significantly affect the product distribution.