Month: May 2016

Electrostatic Precipitators: Way to Kill Industrial Flue Gas

industrial air pollution

Okay, ‘electrostatic precipitator’ is way too technical. Let’s call these machines the scrubbers. They are inherently static-electricity filters, designed to steal dust, soot, ash, and grime from industrial smoke. It goes without asking that they contribute to the minimisation of air pollution. Yes, they are a technological marvel.

Want To Know How A Scrubber Works?

Comb your hair vigorously on a cold, dry day, You’ll notice that the strands cling on to the teeth of the comb. Well, that’s static electricity.

ESPAs the comb rubs against your tresses repeatedly, the electrons break free from them and settle on it instead. At this point of time, your hair is positively charged and the comb negatively. This explains the weird attraction.

Something of the like happens in a scrubber as well. Industrial smoke is actually an aerosol. It may look like gas, but the properties are different. That’s solid suspended in a gaseous medium. The suspended particles are unburned carbon.

The idea is to ‘rub’ the particles so that they receive an electrical charge. These when passes through a medium with the opposite charge, can be pulled out and removed.

Simple, right? Wrong.

There’s more.

Industrial smoke, aka flue gas, is forced through two electrodes inside a smokestack. The negative electrode imparts negative electrical charge to the suspended particles. The second electrode is the positive one and located up or beyond the negative electrode. They attract the charged particles.

Until this point, it is more or less similar to the hair strands attaching to the comb. However, the challenge is to get rid of the pulled particles from the electrode, which is also known as the collector plate.

It needs to be shaken from time to time so that the older particles are emptied and there’s room for newer particles. This can be done manually by brushing or, automatically using an automated shaker or rapper, after which, the particles are disposed of.

ESP at a industry

What Are The Typical Activities Of A Scrubber?

If we go by the above explanation of how a scrubber works, here are the six typical activities that take place inside it:

1. Ionisation – The particles are charged.
2. Migration – The particles are taken to the collector plate.
3. Collection – The particles are collected onto the collector plate.
4. Neutralisation – The particles are neutralised on the collector plate so that they fall.
5. Dislodging – The particles are dislodged onto a hopper.
6. Removal – The particles are carried from the hopper for disposal or recycling.

Which Particulate Properties Affect Electrostatic Precipitators?

Various electrostatic precipitators are designed for particles of various sizes, chemical compositions, and amounts. Here are the two most important aspects of suspended particles that normally affect these scrubbers:

• Electrical resistivity
• Particle size distribution

Other aspects include:

• Temperature of the flue gas
• Its moisture content
• Overall design of the machine
• Whether the rapper is manual or automated
• Whether single-stage or multi-stage scrubbing
• Whether the removed particles should be disposed of or recycled.
• Heterogeneity of the pollutants that the flue gas contains

So, now that you know the scrubber inside out and the loads of environmental benefits it brings, why not have it installed in your industrial plant as well? Like they say, let the machine take care of the machine while we enjoy a good life.