cyclone separator, procedures and operations

cyclone separator, procedures and operations

1. Cyclone Separator / Centrifugal Separator

2. Overview Basic Definition Objectives Working Principle Design Procedure Types Advantages/Disadvantages Industrial Usage

3. A centrifugal separator stationary mechanical device that utilizes centrifugal force to separate solid or liquid particles from a carrier gas Cyclones have no moving parts and available in many shapes and sizes, for example from the small 1 and 2 cm diameter source sampling cyclones which are used for particle size analysis to the large 5 m diameter cyclone separators used after wet scrubbers. What it is…

4. Classification of the dust collectors…

5. Forces Inertia a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force. Centripetal force a force that acts on a body moving in a circular path and is directed towards the center around which the body is moving . Centrifugal force a force, arising from the body's inertia, which appears to act on a body moving in a circular path and is directed away from the center around which the body is moving.

6. The flow enters near the top through the tangential inlet, which gives rise to an axially descending spiral of gas and a centrifugal force field that causes the incoming particles to concentrate along, and spiral down, the inner walls of the cyclone separator. Working principle The collected particulates are allowed to exit out an underflow pipe while the gas phase reverses its axial direction of flow and exits out through the vortex finder (gas outlet tube) .

7. Lets make things a bit c l ear … Vortex Finder Tangential inlet duct Bar r el Cone Dust Collector

8. Design procedures

9. Vertical cyclone separator Horizontal cyclone separator Multiple cyclone separator Single cyclone separator TYPES

10. Design Parameters a = inlet height b = inlet width Dx = vortex finder diameter Ht = total height of cyclone h = cylinder height S = Vortex finder diameter Bc = cone tip diameter

11. Working Principle The particle laden gas is introduced through a tangential inlet into the cylinder at high velocity which imparts a whirling motion to the gas by generating a centrifugal force. Centrifugal force acting on particles in a spinning gas stream is greater than the gravitational force. Particles of much smaller size can be eliminated as compared to gravity settlers. The particle laden gas undergoes a spiral motion directed towards the cone.

12. The vortex develops enough centrifugal force to throw the particles radially towards the walls of the cone. At the bottom of the cone, the gas flows in the reverse direction to form an inner vortex spirally upwards until it exits from the cyclone. The separated particles slide down the cylinder owing to the gravitational force and collect at the bottom.

13. The commonly employed equipment have a tangential inlet with axial dust discharge. The other variants include tangential inlet with peripheral dust discharge, axial inlet with axial dust discharge or peripheral dust discharge. Cyclones are generally sized from the diameter of the cylinder. The ratio of typical parameters could be derived with respect to the cylinder diameter D 0.

14. The body force acting on the particle is given by ‘mg’ where m - mass of particle g – centrifugal acceleration The unbalanced centripetal force acting on the particle is f c = mV t /r V t  tangential velocity of the particle R  radius of rotation

15. The design factors have greater effect on the collection efficiency in cyclone separator Smaller diameter, higher is efficiency because centrifugal action increases with decreasing radius of rotation Cyclone efficiency is >90% with particle diameter of <10 microns >95 % with particle size of diameter 20 microns.

16. Advantages of cyclones are the collected product remains dry and, normally useful. low capital investment and maintenance costs in most applications. very compact in most applications. no moving parts. Can handle large volume of gas at high temperature can, in some processes, handle sticky or tacky solids with proper liquid irrigation. can separate either solids or liquid particulates; sometimes both.

17. Some disadvantages of cyclones are low efficiency for particle sizes below their ‘cut-off diameter when operated under low solids- loading conditions. usually higher pressure loss than other separator types, including bag filters and low pressure drop scrubbers. subject to erosive wear and fouling if solids being processed are abrasive or ‘sticky.

18. power stations spray dryers fluidized bed and reactor riser systems (such as catalytic crackers) synthetic detergent production units food processing plants crushing, separation, grinding and calcining operations in the mineral and chemical industries fossil and wood-waste fired combustion units vacuum cleaning machines dust sampling equipment ship unloading installations Industrial usage

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