Electrostatic Precipitator Overview
In the early 1900s, Frederick Gardner Cottrell created electrostatic precipitators, sometimes known as ESPs. These devices are now crucial for regulating industrial air pollution.
A Basic Overview of How ESPs Operate
ESPs filter out gaseous or airborne dust particles using electricity. Even though they are imperceptible to the human eye, these microscopic particles pose a real threat to human health. The ESP cleans the air by charging the particles and attracting them to plates, where they are trapped.
Important Points:
- ESPs are capable of removing up to 99% of microscopic particles from gases.
- In polluting sectors such as thermal power plants and steel mills, these devices are important.
- ESPs help avoid health issues including bronchitis and lung damage while also reducing air pollution, improving vision, and the consequences of climate change.
To reduce pollution from factories, this is a quick and easy solution.
Table of Contents
The Importance of ESP for Cleaning Flue Gas
An ESP is a piece of equipment that filters out dust from flue gas that is released by various sources, such as boilers. The operation of a boiler or factory results in the production of flue gas, which may include dust or ash. By collecting these dust particles, the ESP may then emit a clean gas, significantly lowering environmental pollution levels.
When fuel is burned in an industrial operation, such as a boiler or furnace, a byproduct known as flue gas is released into the atmosphere. Burning fossil fuels (coal, oil, natural gas, etc.) releases gases into the atmosphere. Some of the substances that may be found in these gases are carbon dioxide (CO2), water vapour (H2O), sulphur oxides (SOx), nitrogen oxides (NOx), and dust particles (like ash).
In order to limit pollution, it is necessary to clean the flue gas before it is released via a stack or chimney. Equipment such as ESPs removes ash and particles from the petrol.
The ESP Principle at Its Core
First, let’s define the corona effect, as that is the fundamental concept of an ESP.
When the air or gas around a conductor (such as an electrical wire or equipment) gets partially ionised due to an extremely high voltage, an electrical phenomenon known as the Corona Effect (also called Corona Discharge) occurs. When this happens, the air around the conductor begins to conduct electricity and produce ions. This process may be audible as a buzzing sound and visible as a blue or purple light.
When humidity is high, this behavior is more common near electrical poles or equipment that uses high voltage.
The Corona Effect and Extrasensory Phenomenon
An integral aspect of the process by which ESPs function is the corona effect, which has a direct relationship to them. Here is how the connection is structured:
- The Corona Effect and Its Function:
The corona effect is purposefully generated in ESPs. A corona discharge is the result of moving high-voltage electrical current through an electrical conductor, such as an electrode. This ionises gas molecules in the vicinity by releasing electrons. Particles of air pollution become negatively charged when they hit with ionised gas, which already has a negative charge. - Collecting Pollutant Particles: The ESP’s positively charged collector plates grab the pollutant particles (dust, smoke, ash) once they assume a negative charge. Particles adhere to the plates upon impact, resulting in the expulsion of clean air.
- Energy Loss Management: An effective way for pollution management is creating ions by corona discharge and charging the particles. However, there is some energy loss as a side consequence of this process. Consequently, in order to reduce energy loss, ESP designs make sure that the corona effect is managed.
The Fundamentals of ESP Functioning
Following this basic idea, an ESP’s main function is to separate gas from dust.
- A corona discharge is produced by providing the discharge electrode with a high voltage source. This Corona discharge produces negative ions.
- Dust With Negative Ions: The dust particles in the flue gas are negatively charged as they go through the ESP.
Thirdly, an electric field is used to collect dust by drawing the dust particles, which are electrically charged, to the collecting electrode. Particles of dust cling to the electrode that collects them. - Dust Removal: Various methods are used to eliminate the dust that has settled on the collecting electrode:
- To eliminate dust, Dry ESP makes use of scraping brushes or rapping hammers.
- Wet ESP uses flushing water to remove the particles.
An ESP’s ability to purify gas and separate dust particles in this way is fundamental for limiting air pollution.
A Method for Removing Dust by Using an Electrostatic Precipitator (Dry ESP)
Dry electrostatic precipitators (Dry ESPs) remove dust in the following ways:

- Charging: Particles in the dust-laden gas are given a negative charge by high-voltage electrodes when they enter the ESP. Corona discharge is responsible for this phenomenon, which occurs when an electric field ionises the air, causing its particles to be negatively charged.
- Collection: The second step is collection, when the charged particles are drawn to the plates that are grounded. The positively charged plates attract the gas stream’s negatively charged dust particles, which cling to them. Particle resistivity and gas velocity determine the process efficiency.
- Accumulation: A coating of dust forms on the collecting plates as time goes on. Particles cling to the plates due to electric field and cohesive forces.
- Cleaning: In order to keep the collecting plates efficient and keep dust out of the gas stream, it is necessary to clean the collected dust from them periodically. In order to remove the dust, mechanical rappers or vibrators provide regulated impacts. Hopper collection and disposal systems catch the loosened particles as they fall into them.
- Disposal: To keep the dust out of the gas stream, it is removed from the hoppers using screw conveyors or rotary airlocks.
An efficient instrument for managing air pollution in industrial environments, dry ESPs reach high levels of particle removal effectiveness, frequently surpassing 99%, thanks to this procedure.
Methods for Removing Dry ESP Dust: A Rapping Hammer and a Scraping Brush
To purify the air, a Dry ESP filters out dry dust particles in the petrol. Particular procedures are used for the removal of dust that has settled on collecting plates or electrodes. The scraping brush and the rapping hammer are two tools that may be used to remove dust:
In order for the collecting plates to keep gathering dust, these two procedures assist in cleaning the dry ESP of any built-up dust. For the ESP to work properly, this procedure is repeated.
A Substantially Wet Electrostatic Precipitator
A wet electrostatic precipitator (wet ESP), which is a type of ESP, uses an additional step in the particle matter removal process. This step involves spraying the gas stream with water or moisture. In situations where a standard dry ESP would not be able to adequately filter gases or pollutants that are wet or sticky, wet ESPs are used.
The Operation of Wet ESPs:
- Particle Charging: Similar to dry ESPs, gas stream contaminants (e.g., dust, fumes, aerosols) are electrically charged using corona discharge.
- Collection on plates: These contaminants, which have charges, adhere to surfaces or plates that have opposing charges.
- Water Spray: A wet ESP involves the periodic use of water spray to clean the collection plates or tubes. Plates won’t become caked with sticky or wet particles after using this spray to wash them away.
- Moist Pollutants: Wet ESPs are great at getting rid of greasy particles, sulphuric acid mist, and small particles that cling to water vapour, among other wet pollutants.
Wet ESPs Have Many Advantages:
- Stick Particle Removal: Unlike dry ESPs, wet ESPs are capable of easily removing pollutants like mist, odors, or greasy particles.
Because more particles are collected with water droplets, wet ESPs are more effective in humid conditions or with wet gas streams. This leads to improved efficiency. - Wet ESPs are safer than dry ones in areas prone to fires because water is constantly being utilised, which eliminates the sparks and fire dangers that are typical with dry ESPs.
Key Use Cases: Wet ESPs find use in chemical, pulp & paper, and other operations that produce exhaust gases, including acidic mist or other wet or moist pollutants.
New Developments in ESP Technology
In comparison to older, more conventional ESP designs, the Moving Electrode Type ESP (MEEP) is more sophisticated and unique. The benefits and how it works are as follows:

- Moving Collecting Plates: The first feature is the moving collecting plates, which are not stationary but rather in a dynamic state. Particularly effective in removing dust with high resistance, this motion helps keep the plates clean.
- Use of Brushes: To clean the plates, step two is to utilise movable brushes. As dust settles on the plates, the brushes make short work of it by scraping them.
- Improved Performance: The moving electrode system enhances performance by making dust collection and removal more efficient. This includes managing high-resistivity dust, which is difficult for conventional ESPs to do.
- Compact Design: The MEEP is smaller than conventional ESPs without sacrificing performance due to its compact design.
For better pollution management in manufacturing operations, this redesigned ESP is more efficient in removing complicated dust particles.
Enhancements to Energy Savings in Energy Storage Devices
Modern ESP technology has made a number of improvements to how energy is used, which makes them more useful and cheaper. How to do it:
- Reduced Air Resistance: Modern ESP designs have made great strides in reducing the amount of energy needed to propel air through the system. Overall, this leads to less energy being used.
- Advanced Power Supply Systems: ESPs with modern technology have advanced power supply systems that effectively transfer voltage and current using high-frequency methods. Improved energy utilisation results in less energy being unused.
- Pulse Energisation: This method, as mentioned before, involves sending brief bursts of high voltage to the electrodes that are used for discharge. Pulses like this efficiently charge dust particles while reducing overall power use.
- Automatic Voltage Control: ESP Systems with automated Voltage Control: These days, ESP systems are equipped with automated voltage control, which stops electric sparks and arcs (incorrect current flow). This safeguards the system from harm while minimising energy waste.
These upgrades make it possible for ESPs to gather dust particles more effectively while using less power. Although ESPs were more expensive to install, they are now more cost-effective in the long run because to energy savings, and they have less of an effect on the environment.
1 thought on “What Are Electrostatic Precipitators (ESP) and How Do They Improve Air Quality?”