1.
PRESENTED BY:
 ARVIND KUMAR(aec
agra chemical engg.)

2.
 Cyclone separators provide a method of removing
particulate matter from air streams at low cost and
low maintenance.
 In general, a cyclone consists of an upper cylindrical
part referred to as the barrel and a lower conical part
referred to as cone.
 The air stream enters tangentially at the top of the
barrel and travels downward into the cone forming an
outer vortex. The increasing air velocity in the outer
vortex results in a centrifugal force on the particles
separating them from the air stream.
 When the air reaches the bottom of the cone, an
inner vortex is created reversing direction and exiting
out the top as clean air while the particulates fall into
the dust collection chamber attached to the bottom
of the cyclone.

3.
 In the agricultural processing industry, 2D2D (Shepherd
and Lapple, 1939) and 1D3D (Parnell and Davis, 1979)
cyclone designs are the most commonly used abatement
devices for particulate matter control.
 The D’s in the 2D2D designation refer to the barrel
diameter of the cyclone. The numbers preceding the D’s
relate to the length of the barrel and cone
sections, respectively.
 A 2D2D cyclone has barrel and cone lengths of two times
the barrel diameter, whereas the 1D3D cyclone has a
barrel length equal to the barrel diameter and a cone
length of three times the barrel diameter.
 The configurations of these two cyclone designs are shown
in figure 2. Previous research (Wang, 2000) indicated
that, compared to other cyclone designs, 1D3D and 2D2D
are the most efficient cyclone collectors for fine dust
(particle diameters less than 100 μm).

4.
CYCLONE SEPARATORS
** Works on the principle of spinning the gas stream so that particles of
higher mass fall out in proportion to the velocity.
** The tendency of particles to move in a straight line when the
direction of the gas stream is changed is the primary mechanism of
imparting centrifugal motion.
** Removes particles of diameter > 10 microns. But efficiency is > 95%
only for particles greater than 25 microns.
** There are however three different types: high volume cyclone (low
efficiency), medium cyclone and high efficiency cyclone (low
throughputs).

5.
Bottom Inlet Cyclone Separator

6.
 Cyclones and centrifugal collectors are
utilized in various industries.
 such as chemical, coal mining and
handling, combustion fly ash, metal
melting, metal working, metal mining, rock
products, plastics and wood products.
 Common uses of cyclones and inertial
separators are the collection of
grinding, crushing, conveying, machining, mi
xing, sanding, blending and materials
handling dust and for particle collection

7.
Co llection Efficienc y of a Cyc lone:
** First, the number of revolutions Ne in the outer vortex is given by
(1)
** To be collected the particles must strike the wall within the amount of
time the gas travels in the outer vortex. The gas residence time in the
outer vortex is given by
(2)
** Maximum radial distance travelled by a particle is the width of the
inlet du ct W. Assume that centrifugal force quickly accelerates the
particle to its terminal velocity in the radial direction. The terminal
velocity that will allow a particle to be collected in time  is
t
(3)
Remember that Vt is given by the Stokes law
(4)
Eliminating  between (2) and (3) and equating (3) to (4) we get
t
The above gives the minimum particle diameter that will be collected.

8.
The theoretical equation derived has a major flaw – it states that all
particles with diameter larger than dp will be collected with 100%
efficiency, which is NOT correct.
Lapple derived a semi-empirical relationship which gives the “50% cut
diameter” dpc., which is the diameter of particles collected with 50%
efficiency.
Lapple then derived a general curve for standard conventional cyclones
that can be used to predict the collection efficiency of any given particle
size. This has been further enhanced by an algebraic relationship
between collection efficiency and cut diameter obtained by Theodore
and DePaola:
Note that is the collection efficiency for the jth particle size range and
j
dpj is the characteristic diameter for that size range.
The overall efficiency of the cyclone is the weighted average of the
efficiencies for various size ranges

9.
Percent collection efficiency
L1 = L2 = 2Do
H = W/2 = Do/2
De = Dd/2 = Do/2
dpj/dpc

10.
 Diameter: 6 to 10” (15 to 25 cm)
 Inlet Velocities: 50 to 60 ft/s (15 to 20
cm/s)
 Volumetric Rates:
◦ 500 to 1000 ft3/s (15 to 20 m3/min)
◦ Capacities as high as 30,000 ft3/min have been
manufactured.

11.
•Large diameter cyclones are less efficient than small diameter ones.
•However, large D will have lower P.
•P in cyclones related to the number of velocity heads of loss, Hv
Vg2  g H v
P(inches of fluid) 
2 g L
•Note: Vg2/2g is one velocity head (Vg is the inlet gas velocity)
•L corrects for P in terms of fluid height.
* Lapple’s observation: HW
Hv  K  2 K = 16 for std. Cyclone
D (tangential gas entry)
e
Vg2  g HW
P  K  2
2 g L De
P : simple cyclones (0.5 to 2” of water); high efficiency (2 to 6” water).

12.
(Know dp from size distribution curve, Qp, Tg, P from stack sampling)
Choose a dpc
Repeat with different dpc
(Obtain required efficiency)
Locate optimum dpc on optimization
curve to get correct D)
1
  P 2Q2 
2
 Q2 D1 
3 2
D2  D1 
 Q   and P2  P 
1

2 
 P1 1   Q1 D2 
Note: Q1 = 0.094 m3/s; P1 = 1,000 kg/m3; D1 = 0.254 m.

13.
 Hc: height of cyclone inlet duct (m)
 Hv: pressure drop expressed in number of inlet velocity heads
 K: (1) cyclone pressure drop constant (equations 7 and 10)
 (2) orifice meter coefficient
 (3) cut-point correction factor
 K1D3D: cut-point correction factor for 1D3D cyclone
 K2D2D: cut-point correction factor for 2D2D cyclone
 L: (1) air stream travel distance in the
 outer vortex (m)
 (2) total inlet loading rate ( equation
 78 only g/m3)
 L1: air stream travel distance in the barrel part (m)
 L2: air stream travel distance in the cone part (m)
 Lc: length of cyclone body (m)