Key Takeaways & Executive Findings
- •• • Increasing ejection gas velocity from 12 to 16 m/s reduces fine particle proportion in coarse fraction from 14% to 12%, directly improving classification sharpness for FCC catalyst separation. • • Raising bed linear velocity from 0.15 to 0.25 m/s increases pressure drop by up to 15%, with dimensionless standard deviation below 5%, confirming stable operation under varying load. • • Higher inlet particle concentration (30 to 70 g/m3) shifts cut size dc50 toward smaller diameters, enhancing fine particle removal but risking selectivity loss due to excessive entrainment. • • Synergistic tuning of ejection gas velocity and inlet concentration enables simultaneous improvement of classification efficiency and selectivity, offering a pathway to optimize catalyst utilization in coupled FCC-pyrolysis units.
Abstract
The development of efficient catalyst classification technologies is crucial for optimizing fluid catalytic cracking (FCC) and catalytic pyrolysis coupling processes, where distinct particle size distributions are required for different reaction pathways. In this study, a large-scale cold-model experimental platform of a multi-arm vortex separator is established to explore the influence of operating conditions on classification behavior. Systematic experiments are conducted by changing ejection gas velocity (8~20 m/s), inlet particle concentration (30~70 g/m3), and bed linear velocity (0.15~0.25 m/s). The results demonstrate that ejection gas velocity governs classification sharpness by controlling the entrainment of fines within the coarse fraction. The increase in ejection gas velocity enlarges the upward axial gas velocity inside the device, thereby enhancing the entrainment effect on particles near the vortex arm outlets. Increasing the ejection gas velocity from 12 to 16 m/s reduces proportion of fine particles in coarse components from 14% to 12%. The inlet particle concentration imposes competing effects on classification performance: while higher concentrations promote agglomeration and modify turbulence distribution, excessive loading intensifies fine-particle entrainment, thereby diminishing classification selectivity. The system maintains stable pressure drop characteristics under different bed linear velocities, with the pressure drop increasing by maximum of about 15% when the bed linear velocity is raised from 0.15 m/s to 0.25 m/s. Analysis of grade efficiency curves reveals classical S-shaped profiles with cut sizes (dc50) shifting under different operating regimes. Higher particle concentrations reduces dc50, favoring fine-particle removal, while higher ejection gas velocities enlarge dc50, moving the classification boundary toward larger sizes. These findings confirm the synergistic effect of ejection gas velocity and inlet concentration, highlighting that rational parameter matching can simultaneously improve efficiency and selectivity. Beyond the experimental findings, this work emphasizes the broader applicability of multi-arm vortex separators in refining and petrochemical processes. By enabling precise adjustment of particle size distribution, the system offers a promising pathway for enhancing catalyst utilization, extending catalyst lifetime, and facilitating process intensification in coupled FCC-pyrolysis units.
1. Introduction
Fluid catalytic cracking (FCC) and catalytic pyrolysis coupling processes demand precise control over catalyst particle size distribution to optimize reaction pathways and product yields. Conventional classification technologies often suffer from poor sharpness and limited tunability, leading to inefficient catalyst utilization and accelerated deactivation. The multi-arm vortex separator presents a novel approach, but its classification performance under industrially relevant conditions remains inadequately characterized.
This study addresses the bottleneck by systematically investigating the effects of ejection gas velocity, inlet particle concentration, and bed linear velocity on classification behavior in a large-scale cold-model setup. The experimental protocol provides quantitative relationships between operating parameters and key performance indicators such as grade efficiency, cut size, and pressure drop, enabling rational design and optimization for industrial implementation.
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Binghao YUAN, Jiaxu ZHANG, Chenglin E, Chunxi LU (2026). Experimental Study on Classification Performance of Multi-Arm Vortex Separator. The Chinese Journal of Process Engineering. https://doi.org/10.12034/j.issn.1009-606X.225246
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Frequently Asked Questions
What is the effect of ejection gas velocity on the entrainment of fine particles in the coarse fraction?
Increasing ejection gas velocity from 12 to 16 m/s reduces the proportion of fine particles (≤40 μm) in the coarse fraction from 14% to 12%, as higher upward axial gas velocity enhances the elutriation of fines from the vortex arm outlets.
How does inlet particle concentration influence the cut size (dc50) and classification selectivity?
Higher inlet particle concentrations (30 to 70 g/m3) promote agglomeration and reduce turbulence, leading to a decrease in dc50 and favoring fine-particle removal. However, excessive loading intensifies fine-particle entrainment, which can diminish classification selectivity.
What is the pressure drop behavior under varying bed linear velocities?
The pressure drop increases by a maximum of about 15% when bed linear velocity is raised from 0.15 to 0.25 m/s, with dimensionless standard deviation consistently below 5%, indicating stable operation with minimal pressure fluctuations.
Can the multi-arm vortex separator achieve both high efficiency and high selectivity simultaneously?
Yes, by rationally matching ejection gas velocity and inlet concentration, the system can optimize both classification efficiency and selectivity, as demonstrated by the synergistic effects observed in the study.
What are the practical implications for FCC and catalytic pyrolysis processes?
The ability to precisely adjust particle size distribution enables enhanced catalyst utilization, extended catalyst lifetime, and process intensification in coupled FCC-pyrolysis units, offering a promising pathway for industrial application.
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