Erosion in Cyclone Separator

Introduction:

A cyclone separator is primarily an air pollution control device and is used to separate pollutants or any matter particles from air as it passes through it. Since the walls of the cyclone separator are continuously bombarded by particles, there will be erosion happening on the surface of the separator.

Erosion can take place in varying scales on surfaces that come in contact with particles through direct impingement or at an angle. Various studies have been carried out on cyclone separator to study the amount of erosion that takes place. Erosion is usually found to take place in the lower part of the cone since the solid particles appear to have a concentrated presence in that region [1].

Objective:

This objective of the project is to demonstrate the use of erosion modelling in ANSYS FLUENT.

Geometry preparation:

For this project, a model of a cyclone separator is imported into SpaceClaim as shown in below:

The fluid volume was extracted using SpaceClaim tools as shown below:

Meshing:

The model was meshed after giving appropriate named selections for the inlet and the two outlets.

Meshed model of cyclone separator

Activating erosion using DPM:

A DPM model needs to be enabled to study erosion. DPM stands for Discrete Phase model and is used to study the trajectory of dispersed particles in the larger fluid volume. The injected particles are modelled as separate secondary phases in addition to the continuous fluid volume. In FLUENT, erosion can be activated in DPM model as shown below:

This basically tells the solver to calculate certain variables that are a part of the DPM model. In this case, it helps us to track the erosion on the walls of the cyclone separator. A steady state analysis with gravity enabled was run and the erosion rate was plotted in the contour as shown in Fig a.

Results:

Fig a

The maximum erosion rate as shown in Fig a is very minute for the inlet velocity of 3m/s given. Here the injected particle was anthracite. Depending on the injected particle and the injected velocity, the erosion rate can substantially increase.

Fig b

Conclusion:

The results shown in Fig b closely agree with the findings of S.B.Reddy Karri [1] that erosion mainly takes place in the lower cone of cyclone separators. This erosion model can be used for other models where erosion can take place.

References:

[1] S.B.Reddy Karri, Rey Cocco et al. “Erosion in Second Stage Cyclones: Effects of Cyclone Length and Outlet Gas Velo