Dust and pollutants are unavoidable and are found in various forms produced from different sources. Dust particles, also termed Particulate Matter (PM) are released in the atmosphere that are varied in size and composition. Particulates with a diameter of more than 2.5 μm are termed coarse particulates, whereas particulates with a diameter less than 2.5 μm. Such particulates are generated from various sources, out of which three main sources are Chemical Reactions, Combustion from Industries, and mechanically generated. Among these, combustion from industries results in particles containing carbon or soot, heavy metals, and ash particles. In most cases, combustion pollutants are fine particulates ranging between 0.1 to 2.5 μm.
What is an Electrostatic Precipitator?
An electrostatic precipitator is pollution control equipment that captures dust particulates released from industrial operations. The objective of electrostatic precipitators is to prevent the release of dust particulates into the atmosphere. It separates the dust particles from the released gases with electrical energy by charging the particles positively or negatively. It leads to it being attracted to the collector plate that contains the opposite charge. These particles are then disposed of as either dry particulates or wet particulates by cleansing them with water. Electrostatic precipitators are the ideal choice as pollution control equipment with an efficiency of up to 99%
Structure of Electrostatic Precipitators:
An electrostatic precipitator mainly consists of 4 components viz. gas distribution plates, discharge electrodes, collection plates or pipes, and rappers. The gas distribution plates are made up of several plates that are pierced with holes to maintain the flow distribution of the gases. The electrodes that are discharged are generally divided into three to four fields. The electrodes discharged are activated with a single transformer-rectifier (T-R) supply that creates ions that later come in contact with particles in the gases and administer electrical charge to it.
The collection surface is either collection plates or pipes that serves as the surface for collecting the particulates. Finally, the rapper removes the collected particulates from the surface.
Working of Electrostatic Precipitators:
The main processes followed in electrostatic precipitators are as follows:
1. Charging:
In most cases, the electrodes for collecting are electrically grounded and connected with the positive end of the high-voltage power supply. The discharged electrodes are released into a flue gas stream and joined to the negative end of the power source. An electric field is created between the discharges and collecting electrodes as the discharge electrodes display an active glow termed corona. When the flue gases are passing through the electric field, the particulates adapts a negative charge
Collecting:
The negatively charged particulates are attracted towards the collecting surface. Resistance is an important factor of particulates. Less resistivity indicates the better capability of charging and getting collected in the Electrostatic precipitators. The particulates remain on the collecting surface because of the forces of the electric field.
2.Cleaning:
Cleaning involves the rapping process, which is performed by striking or vibrating the surface to dispose of the particulates. It is necessary to clean the collecting surface frequently for efficient performance. The disposed particulates with minimum re-entrainment from the collecting surfaces are transferred into hoppers that are, later on, emptied.
Types of Electrostatic Precipitators:
Electrostatic precipitators are of two types that are, dry electrostatic precipitators and wet electrostatic precipitators. Dry electrostatic precipitators are the most commonly used one among industries that generate hot process particulates ranging from 50 to 450 degrees Celsius. The primary difference between both types of precipitators is the method of cleaning them. The dry electrostatic precipitators are cleaned by the vibration of the collecting surface that releases the collected particulates with the process known as rapping. In wet precipitators, the collector surface is cleaned with water. It is highly used with sticky particulates.
Applications of Electrostatic Precipitators:
One of the most used fuel particulates in this pollution control equipment is coal. Since coal is the highly used fuel for generating steam in the industrial process, it is natural to surmise that electrostatic precipitators are required to dispose of coal particulates. Apart from coal, oil-fired steam boilers as well require precipitators to get rid of the released particulates that are similar to coal.
Steam boilers using wood chips or wood bark as fuel prefer electrostatic precipitators to collect ash from the gases.
Industries that Use Electrostatic Precipitators:
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Although Electrostatic Precipitators are used in various process plants, some of the major industries using them are:
- Iron and Steel
- Copper
- Zinc
- Aluminum
- Stainless Steel
- Dairy
- Sugar
- Palm Oil
- Power Generation
- Distilleries
- Paper and Packaging
- Plywood
- Chemical
- Pharmaceutical
- Textile
- Food
- Refineries and Petrochemical
Rakhoh has always aimed for an advanced and sustainable society by manufacturing world-class quality products and pollution control equipment like Electrostatic Precipitators. It is highly efficient and reliable with minimal maintenance requirements and low operational costs. Electrostatic Precipitators are ideal for disposing of waste pollutants as they cause harm to the environment.