(639d) Effect of Outlet Gas Velocity and Solids Loading On Erosion in 2nd Stage Cyclones

 S. B. Reddy Karri^*, Ray Cocco and Ted M. Knowlton

Particulate Solid Research, Inc.

4201 W. 36th Street, Chicago, IL 60632, USA

ABSTRACT

Severe erosion in the lower cone and in the upper dipleg of second stage cyclones have been observed in commercial cyclones.  The main objective of this study is to shed light on the mechanism by which this erosion takes place, and how different design and operating parameters affect the erosion.  Experimental data on how parameters such as the cyclone inlet solids loading and gas outlet velocity affect second stage cyclone erosion are presented.  The outlet gas velocity was varied by changing the size of the vortex tube diameter.  The effect of a vortex stabilizer on cyclone cone erosion is also discussed.

INTRODUCTION

Petroleum refineries have increased their focus on improving unit reliability, and reducing operational and maintenance costs.  Refiners operating fluid catalytic cracking (FCC) units are under increasing pressure to improve the profitability by increasing run lengths between major turnarounds.  Because their cyclones have high efficiencies, FCC process operators are now concerned with longer campaign durations, and would like to improve cyclone reliability.  The 2008 NPRA survey and other surveys (1,2) revealed that FCCU cyclone reliability (3,4) was a major concern for refineries. 

Particulate Solid Research, Inc. (PSRI) conducts research and testing programs that address common concerns of member companies.  These programs are guided by elected technical advisors from member companies.  One (1) recent PSRI program studied and benchmarked different FCC cyclone technologies, since cyclone erosion and reliability are highlighted as the major concerns of FCC operation for member companies in recent surveys.  The most pervasive problem is erosion in the secondary cyclone, particularly in the lower cone and in the transition to the dipleg, which is the focus of the study.

1. Solomon Associates LLC , 2006 Solomon FCC Events Determining TAR Timing Survey, 2006
2. Grace Davison Survey, FCC Conference in Dublin, California, USA, 2002
3. Zenz, F.A., Cyclone Separators, in Manual on Disposal of Refinery Wastes Volume on Atmospheric Emissions, Chapter 11, American Petroleum Institute, Pub. No. 931, Washington, D.C. (1975).
4. Tenney, Ed., FCC Cyclone Problems And How They Can Be Overcome With Current Designs, Presented at the Grace-Davison FCC Technology Conference, Toledo, Spain (1992).