Effect of static bed height in the upper fluidized bed on flow behavior in the lower riser section of a coupled reactor--颗粒学报PARTICUOLOGY

Wang, D., Lu, C., & Yan, C. (2009). Effect of static bed height in the upper fluidized bed on flow behavior in the lower riser section of a coupled reactor. Particuology, 7(1), 19–25. https://doi.org/10.1016/j.partic.2008.11.005

Effect of static bed height in the upper fluidized bed on flow behavior in the lower riser section of a coupled reactor

Dewu Wang, Chunxi Lu^*, Chaoyu Yan

State Key Laboratory of Heavy Oil, China University of Petroleum, Beijing 102249, China

10.1016/j.partic.2008.11.005

Volume 7, Issue 1, 18 February 2009, Pages 19-25

Received 24 July 2008, Accepted 3 November 2008, Available online 13 January 2009.

E-mail: lcxing@cup.edu.cn

Highlights

Abstract

To study olefin reduction by using an auxiliary reactor for FCC naphtha upgrading, a large-scale cold model of a riser-bed coupled to an upper fluidized bed was established. The effect of static bed height in the upper fluidized bed on particle flow behavior in the lower riser was investigated experimentally. A restriction index of solids holdup was used to evaluate quantitatively the restrictive effect of the upper fluidized bed. Experimental results show that, under the restrictive effect of the upper fluidized bed, the riser could be divided into three regions in the longitudinal direction: accelerating, fully developed and restriction. The axial distribution of solids holdup in the riser is characterized by large solids holdup in the top and bottom sections and small solids holdup in the middle section. Overall solids holdup increased with increasing static bed height in the upper fluidized bed, while particle velocity decreased. Such restrictive effect of the upper fluidized bed could extend from the middle and top sections to the whole riser volume when riser outlet resistance is increased, which increases with increasing static bed height in the upper fluidized bed. The upper bed exerts the strongest restriction on the area close to the riser outlet.

Graphical abstract

Keywords

Coupled reactor; RiserFluidized bed; Static bed height; Flow behavior; Restriction

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