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Experimental and numerical study of Stairmand cyclone separators: a comparison of the results of small-scale and large-scale cyclones

  • Halil I. Erol
  • Oguz TurgutEmail author
  • Rahmi Unal
Original
First Online:

Abstract

Gas cyclone separators are employed to separate particles from gas. In this study, the effect of the vortex finder diameter, inlet velocity and particle size on the flow field and the performance of a large industrial Stairmand cyclone has been studied both experimentally and numerically. The vortex finder diameters used are 0.40, 0.45, 0.50 and 0.55 times the cyclone diameter. Cyclones with body diameters of 700 mm and 254 mm are used. Cyclone inlet velocity is changed from 11.5 m∙s−1 to 19 m∙s−1. Particle size is varied between 1 and 13 μm. Whether the correlations obtained for small-scale cyclones are valid for large-scale cyclones has been investigated. The three-dimensional numerical study is carried out by using ANSYS Fluent 17.0 software package for incompressible turbulent flow condition. Reynolds stress model is chosen as the turbulence model. Sawdust ash is used as particles. The results of numerical study are compared with the results of experimental study and literature. Results are found to be consistent with each other. It is seen that cyclone collection efficiency and pressure drop increase when both vortex finder diameter decreases and inlet velocity increases, but 50% cut-off diameter decreases. Results show that the correlations obtained for small sampling cyclones may not be appropriate for large-scale cyclones.

Keywords

Cyclone separators Reynolds stress model CFD Experimental study Vortex finder 

Nomenclature

a

cyclone inlet height, m.

b

cyclone inlet width, m.

B

cone-tip diameter, m.

c

length of inlet section, m.

CD

the drag coefficient, −.

D

cyclone body diameter, m.

Dc

core diameter of cyclone, m.

De

vortex finder diameter, m.

Dh

hydraulic diameter, m.

Dp

particle diameter, m.

D50

particle cut-off diameter, m.

gi

gravitational acceleration in i-direction, m∙s−2.

h

height of cyclone cylinder part, m.

he

vortex finder length outside the cyclone, m.

ΔH

dimensionless parameter, −.

H

cyclone height, m.

I

turbulent intensity level, −.

k

fluctuating kinetic energy, m2∙s−2.

ΔP

pressure drop, Pa.

\( \overline{\mathrm{P}} \)

mean pressure, Pa.

P

fluctuating kinetic energy production, m2∙s−3.

Pij

turbulence production term, m2∙s−3.

Q

volume flow rate, m3∙s−1.

R

radius of cyclone, m.

Rc

core diameter, m.

Re

Reynolds number, −.

Rep

particle relative Reynolds number, −.

Rij

Reynolds stress tensor, m2∙s−2.

s

extension vortex finder inside the cyclone, m.

t

time, s.

Uavg

average velocity, m∙s−1.

\( \overline{{\mathrm{u}}_{\mathrm{i}}} \)

mean velocity in the i-direction, m∙s−1.

ui

i-component fluid velocity, m∙s−1.

Uin

inlet velocity, m∙s−1.

u′i

ith fluctuating velocity component, m∙s−1.

upi

particle velocity in i-direction, m∙s−1.

Vtmax

maximum tangential velocity, m∙s−1.

xi

coordinate system, m.

Greek symbols

δij

Kronecker delta, −.

ε

turbulence dissipation rate, m2∙s−3.

μ

dynamic viscosity, kg∙m−1·s−1.

ρ

gas density, kg∙m−3.

ρp

particle density, kg∙m−3.

ν

kinematic viscosity, m2∙s−1.

νt

turbulent (eddy) kinematic viscosity, m2∙s−1.

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Notes

Acknowledgments

Analyzing of particle size using Malvern Mastersizer E instrument was carried out by third author. The remaining parts of the present study were performed by first and second authors.

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Engineering Faculty, Department of Mechanical Engineering & Clean Energy Research and Application Center (TEMENAR)Gazi UniversityAnkaraTurkey

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