CYCLONE SEPARATOR SIMULATION

                                                                                                     CYCLONE SEPARATOR SIMULATION

Cyclone Separator:-

Cyclone Separators are separation devices that use the principle of inertia to remove the particulate matter from flue gases. Cyclone separators work much like a centrifuge, but with a continuous feed of dirty air. In a cyclone separator, dirty flue gas is fed into a chamber. The inside of the chamber creates a spiral vortex, similar to a tornado. The lighter components of this gas have less inertia, so it is easier for them to be influenced by the vortex and travel up it. Contrarily, larger components of particulate matter have more inertia and are not as easily influenced by the vortex. Since these larger particles have difficulty following the high-speed spiral motion of the gas and the vortex, the particles hit the inside walls of the container and drop down into a collection hopper. These chambers are shaped like an upside-down cone to promote the collection of these particles at the bottom of the container. The cleaned flue gas escapes out the top of the chamber. Out of all of the particulate-control devices, cyclone separators are among the least expensive. They are often used as a pre-treatment before the flue gas enters more effective pollution control devices. Therefore, cyclone separators can be seen as \"rough separators\" before the flue gas reaches the fine filtration stages. 

There are several advantages and disadvantages in using cyclone separators. First, cyclone separators are beneficial because they are not expensive to install or maintain, and they have no moving parts. This keeps maintenance and operating costs low. Second, the removed particulate matter is collected when dry, which makes it easier to dispose of. Finally, these units take up very little space. Although effective, there are also disadvantages in using cyclone separators. Mainly because the standard models are not able to collect particulate matter that is smaller than 10 micrometers effectively and the machines are unable to handle sticky or tacky materials well.

Emperical Models used for cyclone separator efficiency:-

1) Lozia and leith model:- 

Lozia and leith model is based on force balance. The model assumes that a particle carried by the vortex endures the influence of two forces, viz: a centrifugal force and flow resistance. The collection efficiency of the particle diameter dpi can be calculated from:-

`etai = (1)/(1+(d_(pc)/d_(p.i))^beta`

β is an expression for slope parameter derived based on statistical analysis of experimental data of a cyclone.

2) Li and Wang model:- 

Li and Wang model include particle bounce or re-entrainment and turbulent diffusion at the cyclone wall. A two- dimensional analytical expression of particle distribution of the cyclone is obtained. The resultant expression of the collection efficiency for a particle of any size is given as 

`etai = 1-exp{-lambda theta_1}`

3) Lapple model:-

Lapple model was based on force balance without considering the flow resistance. Lapple assumed that a particle entering the cyclone is evenly distributed across the inlet opening. The particle that travels from inlet half-width to the wall in the cyclone is collected with 50% efficiency. The efficiency of collection of any size is given by:-

`etai = 1/(1+((d_pc)/(d_p.i))^2`

3)  Koch and Licht Model:-

Koch and Licht collection theory recognised the inherently turnulent nature of cyclones and the distribution of gas residence times within the cyclone.

Koch and Licht described the particle motion in the entry and collection regions by the following assumptions:

• The tangential velocity of a particle is equal to the tangential velocity of the gas flow, i.e there is no slip in the tangential direction between the particle and the gas.
• The tangential velocity is related to the radius of cyclone by μ Rn = constant.

A force balance and an equation on the particles collection yields the grade efficiency as:-

`etai = 1-exp{-2[(G tau_i Q)/D^3 (n+1)]^(0.5/(n+1)) }`

CYCLONE SEPARATOR SIMULATION:-

Model of Cyclone Separator:

Volume Extracted:- Using the Volume extraction tool from the prepare option in the space claim the following volume is extracted, upo which the simulation is performed.

The different faces of the model are named as follows:-

CASE 1:- 

In this case four different analysis are performed on the cyclone separator model by applying four different boundary conditions (viz. Reflect, Trap, Escape, Wall Jet) on the inlet, keeping the number of particles same for all the conditions. The diameter of the injections is 5e-06m.

Mesh:- The element size is kept as 10mm and the number of elements are 407492

1) REFLECT:-

Number Tracked= 364; Escaped=122; Incomplete= 242; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.016067 kg/s

Mass flow at outlet 2 = -0.0408727 kg/s

Particle Track:                                                                                                                           Vortex:

2) ESCAPE

Number Tracked= 364; Escaped=122; Incomplete= 242; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.016067 kg/s

Mass flow at outlet 2 = -0.0408727 kg/s

Particle Track:                                                                                                                           Vortex:

3) TRAP

Number Tracked= 364; Escaped=122; Incomplete= 242; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.016067 kg/s

Mass flow at outlet 2 = -0.0408727 kg/s

Particle Track:                                                                                                                           Vortex:

4)WALL-JET:-

Number Tracked= 364; Escaped=122; Incomplete= 242; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.016067 kg/s

Mass flow at outlet 2 = -0.0408727 kg/s

Particle Track:                                                                                                                           Vortex:

CASE 2:- In this case the analysis is done on the cyclone separator model by varying the number of particles at the inlet and applying the same boundary condition i.e Reflect. The diameter of the injections is 5e-06m.

1) Mesh size = 8mm; Number of elements = 701803

Number Tracked= 498; Escaped= 260; Incomplete= 238; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.0152094 kg/s

Mass flow at outlet 2 = -0.0417244 kg/s

Particle Track:                                                                                                                           Vortex:

2) Mesh size = 7mm; Number of elements = 971623

Number Tracked= 642; Escaped= 616; Incomplete= 26; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.0148868 kg/s

Mass flow at outlet 2 = -0.0420536 kg/s

Particle Track:                                                                                                                           Vortex:

3) Mesh size = 5mm; Number of elements = 2207436

Number Tracked= 1298; Escaped= 295; Incomplete= 1003; Aborted= 0; Trapped= 0; Evaporated= 0; Incomplete Parallel= 0

Mass flow at inlet = 0.0569625 kg/s

Mass flow at outlet 1 = -0.013885 kg/s

Mass flow at outlet 2 = -0.0429875 kg/s

Particle Track:                                                                                                                           Vortex: