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Electrostatic Precipitator – Class 12 | Chapter – 16 | Biology Short Notes Series PDF

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Electrostatic Precipitator: An Electrostatic Precipitator (ESP) is a device used to remove particulate matter (such as dust, ash, and smoke) from a gas stream. It works by applying a high voltage electrical field to the gas stream, which attracts the particulate matter and causes it to be deposited on charged plates or electrodes within the ESP. ESPs are commonly used in industrial processes to control air pollution, particularly from coal-fired power plants, cement kilns, and other sources of particulate emissions. They are also used in various other applications, such as in the food industry to control the emission of flour dust from grain processing, and in the chemical industry to remove particles from reactor exhaust gases.

Working Principle of Electrostatic Precipitator

The working principle of an Electrostatic Precipitator (ESP) is based on the phenomenon of electrostatic attraction. Here’s how it works:

  • A high voltage electrical field is applied between a series of electrodes and collection plates. The electrodes are typically made of metal and are charged to a high voltage, typically between 20 and 100 kilovolts.
  • The particulate-laden gas stream is introduced into the ESP and flows through the electrical field created between the electrodes and the collection plates.
  • As the particulate matter in the gas stream passes through the electrical field, it becomes charged and is attracted to the collection plates, which are maintained at a lower potential.
  • The collected particulate matter is deposited on the collection plates, and is removed periodically by mechanical rapping or pulsing, which causes the particulate matter to fall into a hopper or ash bin for disposal.

  • The cleaned gas exits the ESP and continues on to the next process or is released into the atmosphere.

Types of Electrostatic Precipitator

Electrostatic Precipitators (ESPs) can be classified into two main types based on the configuration of their electrodes and collection plates:

  • Plate Type Electrostatic Precipitator: This type of ESP uses parallel plates as both electrodes and collection plates. The particulate-laden gas stream passes between the plates, and the charged particulate matter is attracted to the plates and deposited there.
  • Tube Type Electrostatic Precipitator: This type of ESP uses cylindrical tubes as the electrodes, with a series of collection plates surrounding the tubes. The particulate-laden gas stream flows through the tubes, and the charged particulate matter is attracted to the collection plates and deposited there.

Advantages of Electrostatic Precipitator

Electrostatic Precipitators (ESPs) have several advantages over other air pollution control technologies:

  • High Efficiency: ESPs have a high efficiency in removing particulate matter from the gas stream, with collection efficiencies of up to 99.9% possible.
  • Wide Range of Application: ESPs can be used to remove particulate matter from a wide range of industrial processes, including flue gas from boilers, kilns, and furnaces; gas streams from chemical plants and power plants; and emissions from steelmaking and other metal processing operations.
  • Low Maintenance: ESPs require relatively low maintenance, as the electrodes and collection plates can be cleaned and maintained without shutting down the process.
  • Low Operating Costs: ESPs have low operating costs, as they do not require the use of chemicals or other consumables, and have low energy requirements.
  • Compact Design: ESPs have a compact design, which allows for easy installation and integration into existing processes and facilities.
  • Environmentally Friendly: ESPs do not generate any secondary pollutants or contribute to greenhouse gas emissions, making them an environmentally friendly solution for air pollution control.

  • Long Operating Life: ESPs have a long operating life, with many units still in service after several decades of operation.

Disadvantages of Electrostatic Precipitator

Electrostatic Precipitators (ESPs) have some disadvantages that need to be considered when evaluating their use for air pollution control:

  • High Capital Cost: ESPs can have a high capital cost, as they require specialized equipment and materials.
  • Complex Design: ESPs can have a complex design, with multiple stages and components, which can make them difficult to operate and maintain.
  • Limited Particulate Size Range: ESPs have limited capabilities for removing very fine or very large particulate matter, as the charging and collection process is most effective for particles in a certain size range.
  • Voltage Requirements: ESPs require high voltage to effectively charge and collect the particulate matter, which can be challenging to achieve for some applications.
  • Moisture Effects: ESPs can be affected by the presence of moisture in the gas stream, as it can reduce the effectiveness of the charging and collection process.
  • Limited Efficiency for Certain Particulate Types: ESPs can be less effective in removing certain types of particulate matter, such as those with low electrical conductivity or those with a low density.
  • Re-entrainment: ESPs can be prone to re-entrainment, where collected particulate matter is re-released back into the gas stream due to vibrations or other causes.

  • High Energy Requirements: ESPs can have high energy requirements, especially for high-voltage systems, which can increase operating costs.

Applications of Electrostatic Precipitator

Electrostatic Precipitators (ESPs) are widely used in various industrial applications to remove particulate matter from gas streams. Some of the main applications include:

  • Power Generation: ESPs are commonly used in power generation to remove fly ash, unburned carbon, and other particulate matter from the flue gases produced by coal-fired boilers.
  • Steel Production: ESPs are used in steel production to remove particulate matter, such as iron oxide and carbon, from the exhaust gases generated during the production process.
  • Cement Production: ESPs are used in cement production to remove particulate matter, such as calcium oxide and carbon, from the exhaust gases generated during the production process.
  • Incineration: ESPs are used in incineration to remove particulate matter, such as heavy metals and dioxins, from the exhaust gases generated during the incineration of waste.
  • Chemical and Petrochemical Production: ESPs are used in chemical and petrochemical production to remove particulate matter, such as organic compounds and heavy metals, from the exhaust gases generated during the production process.

  • Mining Operations: ESPs are used in mining operations to remove particulate matter, such as dust and minerals, from the exhaust gases generated during the mining process.

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By Team Learning Mantras