Introduction: Electrostatic Smoke Precipitator
Electrostatic precipitation is a method to remove particulate matter from the air flow. This is one of the important industrial application, where PM or dust particle need to remove from the waste gas stream. A major advantage of this method is that this adds minimum resistance to the air flow. Impurities are attracted towards charged plates and separated from the flow. This type of devices are generally used to collect ash after coal burning.
Step 1: How It Works:
In electrostatic precipitator smoke is charged high voltage electrode, then it is passed over another electrode having opposite charge. so ionized particles attract towards it and separated from the gas stream.
In the image, an example of plate precipitator is given. The initial stage, smoke is passed through the negative electrode (blue colored rod). this electrode has high voltage such that smoke particle gets ionized due to corona discharge. Than ionized particle is passed though positively charged plate. These charged particles are attracted towards positive electrode due to the electrostatic force. So the layer of particle builds upon the electrode and separated from the flow.
Step 2: Material Required to Make One:
Making smoke precipitator is a fairly simple to make for demonstration purpose but for the actual application, it is required to consider multiple parameters that affect collection efficiency. So, we would try to make a smoke precipitator that just works (no optimization).
- To make electrostatic smoke precipitator following material would be required: The high voltage source, It can be an induction coil, ignition coil, Tesla coil. (Here I am going to use a ready-made high voltage module available on hobby market at a cheap rate typically known as 3.7V-6V to 400kV DC step up power module (output is not 400kV)) and battery and/or driver to power it.
- Smoke source, ex. incense, a cigarette would work.
- Aluminum foil,
- Copper wires,
- Plastic bottles (or anything that can be used as the container)
Step 3: Preparing Electrodes:
First, we need to prepare a negative electrode using some branched wire. I have made it by soldering multiple copper wire to each other. Having multiple sharp edges will increase corona discharge so the ionization of the smoke.
Then this wire branch needs to fix with a container. Here I had attached wire branches to the neck of the plastic bottle. there is also one provision/cut on the bottom to place some smoke source. we will apply the negative charge to this electrode. So first smoke will interact with this electrode and ionize, then it will go to positive electrodes
To make a container with a negative electrode I am using two paper cups. I have placed Aluminium foil inside and a wire connected with it that will goes to Positive terminal of the power supply. The module I am using does not have any type of indication for positive or negative. Identifying the negative terminal is not difficult just place a candle flame in between two plates (no electric breakdown or corona discharge in-between so plate should be far enough with each other). Flame get attracted towards one of the terminals that is negative.
The overall setup as shown in the above image, in which smoke first interact with negative terminal then passes through paper cups having positive electrode inside.
Now complete setup is ready to be tested. First place smoke source (ex. incense or cigarette-like source) and observe smoke out from upper face. After turning ON the power source and keep observing it for a few seconds. A significant reduction in smoke output can be observed. After a run of few seconds ( or maybe minutes) deposition at the positive electrode can be observed.