Particle Deposition Mechanisms: Impaction

Cyclone Separator

Radial force balance for a particle in the rotating flow in a cyclone is given as

(1)

For small particles, , it follows that

(2)

or

(3)

where  is used.

It is assumed that

(4)

Equation (3) then becomes

(5)

or

(6)

The number of turns needed to deposit the particles of size d (that is, moving the particles from the radius a to the side wall at r=b) is given by

(7)

or

(8)

Alternatively, the smallest particle that can be removed in  turns is given by

(9)

In practice, an approximate expression

(10)

is used, where U is the mean inlet velocity.