Simulation of an Electrostatic Precipitator

Electrostatic precipitators are widely used in various industries to control emission levels. These are particulate collection devices that remove particles from a flowing gas using the force induced on ions. Using ElecNet with the particle trajectory tracking tool, it is possible to carry out realistic design and simulations of engineering devices such as the electrostatic precipitator.

Consider the architecture of an actual precipitator as shown here. This device consists of an inlet-outlet casing through which particulate laden gas flows into an area where a series of particulate collection sheets are placed. These sheets of metal are maintained at certain voltages, after passing through which, clean air is deposited at the other end of the casing.

The model has been solved using ElecNet’s 3D electrostatic solver and particle trajectory has been followed using the Trajectory Evaluator.

Results

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The electrode potentials and electric field between the two collection plates are shown here.

Using the Trajectory Evaluator tool, we track the path of charged particles which are simulated from the entrance of the inlet in the model. Consider a particle with mass 5 amu with a net charge of -1.67e-27 C placed in the air gap between the metal sheets. The collection plates are set to be between -5 and + 5 V. The z coordinates of the position, velocity and acceleration of this particle, evaluated using the Trajectory evaluator are shown in the figures below.

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The position of the charged particle along the z-axis inside the precipitator versus time.

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The velocity of the charged particle along the z-axis inside the precipitator versus time.

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The acceleration of the charged particle along the z-axis inside the precipitator versus time.

Given a uniform, linear voltage distribution and separation of 1mm between the collection plates, a constant force is expected to be imparted on the charge, as is confirmed by the results. Also, the Trajectory Evaluator contains an in-built collision detection mechanism so that once the particle has been collected by the collection plate (at t=.014 s and z=1 mm), the tracker automatically stops computing the trajectory further.

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To complement the results shown here, consider the same particle but this time, de-ionized. The results on the right show that this particle is not affected by the electric field, as is expected. Coupled with the previous results, this illustrates the fact that when multiple particles are considered, the Trajectory evaluator is able to handle them simultaneously.

During the design cycle, the user may be interested in changing the geometry or any other input of the device to compare their performance parameters. ElecNet’s powerful parameterization tool allows the user to set up a family of models with ease. For example, if the separations between the collection plates are parameterized to be 1, 2, 3, 4, and 5 mm., the parameterized set of models are all stored in a single file and can be analyzed simultaneously.

The trajectory Evaluator allows the user to specify complete particle state information for multiple numbers of particles. The user may specify the charge, mass, position components, initial energy, frequency of time varying fields, time to flight etc. To simulate coupled gas dynamics, it is possible to interface ElecNet with a hydrodynamic solver.