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Effects of Asymmetric Feeding on Gas-Solid-Liquid Transport and Catalytic Cracking Reaction in the Feed Zone of Riser

Effects of Asymmetric Feeding on Gas-Solid-Liquid Transport and Catalytic Cracking Reaction in the Feed Zone of Riser

Authors: 
Zhang, B. - Presenter, New Jersey Institute of Technology
Zhu, C. - Presenter, New Jersey Institute of Technology
He, P. - Presenter, Ohio State University

Asymmetric feeding of liquid reactants and catalytic solids are common in the operation of fluid catalytic cracking (FCC) riser reactors. The asymmetric feeding of solids can be caused by the designed-geometry of J-bend right before the riser inlet or unbalanced operation of wall-steam feeding. A possible measure of balancing the asymmetric feed of catalysts is to introduce liquid jets in an accordingly asymmetric feeding. The asymmetric feeding will cause complicated three-phase interactions, in terms of the transport and phase-change characteristics of each interacting phase, in the feed zone of a riser reactor. This study has developed a theoretical framework with an inertia-based multi-spray interaction, which considers not only a complex geometric intervene of mutual-penetration sprays but also the individual spray properties and feeding operations. Apart from the dominant axial flow direction, based on the unbalance of local pressure and species concentration, a model to calculate radial transport of both gas and solid phases is also derived. The inlet condition of asymmetric feeding of catalysts is based on CFD simulation of gas-solid flow through J-bend as well as from available experiment data. Our model predicts a noticeable difference of reaction and flow characteristics between symmetric and asymmetric feedings, such as changes in droplet penetration, spray coverage and local catalytic to oil (CTO) ratio.

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