Cyclonic Dust Collectors

Principles of Operation

HOW CYCLONIC COLLECTORS WORK
The basic principles of cyclonic separation is extremely simple.

  1. Dirty gas is guided into a cylindrical tube at high velocity in a way that sets up a whirling action inside the tube.
     
  2. The whirling action generates centrifugal forces. These forces throw the particles of dust suspended in the gas against the inside tube wall.

    The particles then fall downward and out a discharge throat at the tube bottom. Cleaned gases exit from the top.
     
  3. The centrifugal forces depend upon the velocity of the gas and the tube radius in which it is whirled.


Small tube diameters and higher inlet gas velocities create larger centrifugal forces.

This relationship is expressed by the mathematical formula:


MULTICLONES
 

In Multiclone  collectors, the gas enters axially from the top of the tube.

The whirling action is set up by directional vanes positioned in the path of the incoming gas.
These vanes also help to uniformly distribute the gas around the tube circumference. 
Collector Tube
Diameter		 Pressure
Drop kPa

Gas
Temp
C

 Particle Specific Gravity
Multiclone 9 230 0.75 230 2.5
Multiclone 12 300 0.75 230 2.5
Multiclone 24 600 0.75 230 2.5
Cyclone 1800 0.75 230 2.5


GAS TYPE DICTATES CHOICE

The type of dust to be collected determines the type of cyclonic collector to be used. Particle size, weight and shape affect the centrifugal force acting on the particulate entering the collecting tube. Generally, larger, denser dust particles are easier to collect than smaller or less dense particles. 

THE SMALLER THE TUBE DIAMETER, THE HIGHER THE EFFICIENCY.

 In general, for particles of the same size, shape and density, smaller collecting tubes will achieve higher collection efficiencies. 

Particles whirling in a smaller tube will have larger centrifugal forces exerted on them. Larger centrifugal forces will yield higher collection efficiencies.

A typical dust collected in the four main cyclonic collectors produced the following test data. 

 

 

 

 


Note that the Multiclone 9 achieved the highest collection efficiency followed closely by the slightly larger Multiclone 12 collecting tube. 

There are limitations on the tube diameter for some applications. 

Plugging may occur in smaller diameter collecting tubes for extremely heavy dust loads or very sticky dusts. In these cases, using a larger diameter tube will reduce the possibility of plugging. 

 

 

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