CFB cyclones at high temperature: Operational results and design assessment--颗粒学报PARTICUOLOGY

Dewil, R., Baeyens, J., & Caerts, B. (2008). CFB cyclones at high temperature: Operational results and design assessment. Particuology, 6(3), 149–156. https://doi.org/10.1016/j.partic.2008.01.002

CFB cyclones at high temperature: Operational results and design assessment

Raf Dewil ^a *, Jan Baeyens ^b, Bart Caerts ^c

a Department of Chemical Engineering, Associated Faculty of Technology and Bio-sciences, Campus De Nayer, Katholieke Universiteit Leuven, Jan De Nayerlaan 5, B-2860 Sint-Katelijne-Waver, Belgium
b Department of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
c Department of Chemical Engineering, Katholieke Universiteit Leuven, Willem De Croylaan 46, B-3001 Heverlee, Belgium

10.1016/j.partic.2008.01.002

Volume 6, Issue 3, June 2008, Pages 149-156

Received 6 October 2007, Accepted 21 January 2008, Available online 14 May 2008.

E-mail: raf.dewil@skynet.be

Highlights

Abstract

Pressure drop and cut size measurements are reported for a full scale cyclone operating within a 58 MW_th CFB-combustor unit at 775 °C.

The paper reviews the vast number of equations to calculate the pressure drop and separation efficiency of cyclones, generally for operation at ambient temperature and at low Cs [<0.5]. None of the literature correlations predicts the pressure drop with a fair accuracy within the range of experimental operating conditions. The cut size d₅₀ can be estimated using direct empirical methods or using the Stokes number, Stk₅₀. Both methods were used to compare measured and predicted values of d₅₀. With the exception of Muschelknautz and Krambrock, none of the equations made accurate predictions.

Finally, an alternative method to determine the friction factor of the pressure drop equation (Euler number, Eu) and of the cut size is proposed. The Eu number is determined from the geometry of common cyclones, and the derived value of Stk₅₀ defines more accurate cut sizes. The remaining discrepancy of less than 5%, when compared with the measured values, is tentatively explained in terms of a reduced cyclone diameter due to the solids layer formed near its wall. Further measurements, mostly using positron emission particle tracking, elucidate the particle motion in the cyclone and both tracking results and the influence of the particle movement on Eu and Stk₅₀ will be discussed in a follow-up paper.

Graphical abstract

Keywords

Cyclone; High loading; High temperature; Combustor

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