(421r) Investigations on an Empirical Pressure Drop Calculation Model for Uniflow Cyclones

MCI – The Entrepreneurial School, Environmental, Process & Energy Engineering, Maximilianstraße 2, A-6020 Innsbruck, AUSTRIA

Abstract

Uniflow cyclones used for the separation of particles from gases are characterized - compared to standard reverse flow cyclones – by a very compact design. This advantage allows plant operators an easy implementation in existing piping systems. Therefore fine dust emissions can be reduced by a low fabrication effort. Uniflow cyclones can be used independently or as an upstream dedusting device. The application as an upstream deduster can significantly increase the lifetime of downstream fabric filters. Uniflow cyclones are widley used in automotive filtration systems, catalytic processes and in some FCC applications [1,2,3]. Even though the principle is well-known, there is hardly any literature which investigates the design, the estimated efficiency or pressure drop. To close this gap the MCI is driving research activities since 2008 to improve the separation efficiency of uniflow cyclones by optimizing the geometric design [4,5]. The main objective of this study is to shed light on the prediction of the occurring pressure drop at different operating conditions to facilitate engineering work. For this purpose the fundamentals of fluid mechanics are used to build the basic calculation equations of the pressure drop in the three major parts of uniflow cyclones by passing gas through them. The superordinate aim is to set up a user-friendly calculation model to predict the occurring pressure drop as a function of the operating conditions and the geometric design. Therefore the conservation of energy referred to Bernoulliis taken to calculate the local and continuous energy losses caused by dissipation. The pressure drop coefficients are elevated by empirical testing series.

Applying the model on already existing uniflow cyclones show a very high conformity to the measured pressure data. The determination of the pressure drop coefficients have been executed on uniflow cyclones with a D_CYCLONEof 32mm. The predicted pressure drops show a maximum deviation from the measured results of ±15%. These comparisons have been carried out on uniflow cyclones in a scale compared to the experimental cyclone from 2:1 up to 1:10.

[1]            Gauthier, T.A., Briens, C.I., Bergougnou, M.A., Galtier, P., Uniflow cyclone efficiency study, Powder Technology, Nr.62: 217-225, 1990.

[2]            Kraxner, M., Muschelknautz, U., Karri, S.B.R., Cocco, R., Knowlton, T.M., Applicability of a Uniflow Cyclone as a Third Stage Separator in the FCC-Process, AIChE - American Institute of Chemical Engineers - Annual Meeting, Minneapolis / Minnesota USA, 2011.

[3]            Peng, W., Hoffmann, A. C., Separation Characteristics of Swirl-Tube Dust Separators, AIChE Journal, Nr.50: 87-96, 2004.

[4]            Muschelknautz, U., Pattis, P., Reinalter, M., Kraxner, M., Design Criteria of Uniflow Cyclones for the Separation of Solid Particles from Gases, CFB10 – 10th International Conference on Circulating Fluidized Beds and Fluidized Bed Technology, Sunriver/OR, 2011.

[5]            Kraxner, M., Empirische Ermittlung von Auslegungskriterien für Gleichstromzyklone in Multizyklonblöcken, Dissertation, TU München, 2013.