Control of Particulates: Particulate control mechanisms

Unit: 2

Control of Particulates:

Particulate control mechanisms

Gravity settler:

Introduction:

A Gravity settler is a type of industrial equipment used to separate particles from a liquid or gas mixture based on their specific gravity. It typically consists of a tall, cylindrical tank with a conical bottom, into which the mixture is introduced at the top. As the mixture flows down through the tank, the heavier particles settle to the bottom and are collected, while the lighter particles continue to flow out the top. Gravity settlers are commonly used in industries such as water treatment, chemical processing, and mining.

Working :

The working principle of a gravity settler is based on the fact that particles of different densities will settle at different rates when suspended in a liquid or gas mixture. The mixture is introduced at the top of the settler and flows down through the tank, where it is separated into different layers based on the density of the particles.

The heavier particles, such as sediment or mineral particles, will settle to the bottom of the tank and are collected, while the lighter particles, such as oil or gas bubbles, will rise to the top and are removed. The process of settling and separation continues until the particles have reached a steady state, at which point the liquid or gas at the top of the tank is relatively clear of particles, while the bottom of the tank is mostly filled with the heavier particles.

The design of a gravity settler plays a crucial role in its efficiency. The taller and wider the tank, the longer the particles will have to settle, and the more efficient the separation will be. Additionally, the use of a conical bottom helps to concentrate the heavier particles at the bottom of the tank, making it easier to remove them.

Gravity settler Construction

A gravity settler typically consists of a tall, cylindrical tank with a conical bottom, which is known as the settling chamber. The settling chamber is often made of steel or other durable materials that can withstand the corrosive nature of some liquids or gases that are processed. The top of the chamber is open to allow the mixture to be introduced, and the bottom of the chamber is connected to a valve or pipe for the removal of the settled particles.

The settling chamber is usually supported by a strong framework to ensure stability and safety. The inside of the chamber is usually smooth and without any obstacles to prevent clogging or the accumulation of particles. A sloping bottom allows the particles to settle easily and to be discharged at the lowest point of the cone.

An inlet pipe is connected to the top of the settler to introduce the mixture, and an outlet pipe is connected to the top of the settler to discharge the clarified liquid. The outlet pipe is usually located above the highest point of the settled particles, to ensure that only clarified liquid is discharged.

Some gravity settlers may also include additional features such as internal baffles, which help to increase the efficiency of the settling process by slowing down the flow of the mixture and allowing more time for the particles to settle.

Overall, gravity settlers are relatively simple and cost-effective devices that can be used to separate particles from a variety of liquid or gas mixtures.

Components :

A gravity settler typically consists of the following components:

Tank: The main component of a gravity settler is the tank, which is usually made of stainless steel or other corrosion-resistant materials. It is typically cylindrical in shape with a conical bottom.

Inlet: The mixture to be separated is introduced into the top of the tank through an inlet.

Outlet: The liquid or gas mixture exits the top of the tank through an outlet.

Launder: The launder is the channel that surrounds the tank and collects the settled particles.

Overflow: An overflow is provided to ensure that the level of the liquid in the tank does not exceed a certain level.

Scrapers: Scrapers are used to remove the settled particles from the bottom of the tank and transport them to the launder.

Agitator: An agitator is used to keep the mixture in the tank in motion and prevent the particles from settling too quickly.

Control valves: Control valves are used to regulate the flow rate and pressure of the mixture entering and exiting the tank.

Level indicator: A level indicator is used to monitor the level of liquid in the tank.

Access Manholes: Access manholes are provided for maintenance and cleaning of the tank.

Industrial applications :

Gravity settlers are commonly used in a variety of industrial applications, including:

Water Treatment: Gravity settlers are used in municipal and industrial wastewater treatment to remove suspended solids and other heavy particles from the water.

Chemical Processing: In the chemical industry, gravity settlers are used to separate liquids of different densities, such as oil and water, and to purify liquids by removing impurities.

Mining: Gravity settlers are used in the mining industry to separate valuable minerals from waste material.

Petroleum Refining: Gravity settlers are used in petroleum refineries to separate different components of crude oil, such as water, oil, and sediment.

Food and beverage industry: Gravity settlers are used to separate solid particles from liquids in the food and beverage industry, such as in the clarification of fruit juices.

Pharmaceuticals: Gravity settlers are used in the pharmaceutical industry to separate solid particles from liquids in the production of drugs.

Pulp and paper: Gravity settlers are used in the pulp and paper industry to separate solid particles from liquids in the production of paper.

Power Generation: Gravity settlers are used in power generation to separate solid particles from liquids in the cooling towers.

These are some of the common industrial applications where gravity settlers are used.

Gravity settler performance parameters :

There are several performance parameters that can be used to evaluate the effectiveness of a gravity settler. These include:

Separation Efficiency: This is a measure of how effectively the gravity settler is able to separate the particles based on their specific gravity. It is typically expressed as a percentage of the total number of particles that are collected at the bottom of the tank.

Throughput: This is the amount of liquid or gas mixture that can be processed by the gravity settler in a given period of time, usually measured in cubic meters per hour or gallons per minute.

Pressure drop: This is the difference in pressure between the inlet and outlet of the gravity settler, and is a measure of the resistance to flow through the device.

Solids loading: This is the amount of solids that can be processed by the gravity settler before the performance starts to degrade.

Settling velocity: This is the speed of the particles as they settle to the bottom of the tank.

Efficiency of the bottom discharge mechanism : Efficiency of the bottom discharge mechanism play crucial role for continuous process and reduce the downtime for maintenance.

Compaction : This is the amount of solids that are collected at the bottom of the tank and the degree of compaction.

Scale-up: This is the ability of the gravity settler to handle increased flow rates and/or increased solids loading without a significant loss in performance.

Overall, the performance of a gravity settler is affected by many factors such as particle size and distribution, fluid properties, and the design of the device.

Venturi scrubber:

Introduction, Working Principle, Construction, Components, Industrial applications,

Performance Parameters

A Venturi scrubber is a type of air pollution control device that is used to remove particulate matter and gaseous pollutants from industrial exhaust streams. The device uses the principle of a Venturi nozzle to create a pressure drop and increase the velocity of the exhaust stream. As the exhaust stream passes through the narrow section of the nozzle, it is mixed with a scrubbing liquid, typically water, which is introduced through a separate inlet.

The high-velocity exhaust stream and scrubbing liquid create a turbulent mixing zone, where the pollutants are effectively scrubbed from the air. The scrubbed exhaust stream is then discharged to the atmosphere, while the pollutants are captured in the scrubbing liquid, which is typically sent to a separate treatment system for further processing. Venturi scrubbers are commonly used in industries such as power generation, cement production, and metal processing.

Venturi Scrubber Working Principle :

A Venturi scrubber is a type of air pollution control device that uses the principle of a Venturi tube to mix and atomize a liquid scrubbing solution with dirty air or gas streams. The dirty air or gas stream is drawn into the Venturi scrubber through an inlet and is then forced through a constriction in the tube, which increases the velocity of the air stream and causes a decrease in pressure. This decrease in pressure creates a suction effect that pulls the liquid scrubbing solution into the air stream.

As the air stream and liquid solution mix, the pollutants in the air are absorbed by the liquid and removed from the air stream. The cleaned air or gas then exits the Venturi scrubber through an outlet. The liquid solution, now containing the pollutants, is collected at the bottom of the Venturi scrubber and is typically sent to a treatment system for further processing or disposal.

Venturi scrubbers are commonly used to remove particulate matter, sulfur dioxide, and other gases from industrial exhaust streams. They are particularly effective for removing fine particulate matter, and can achieve high removal efficiencies even at low liquid-to-gas ratios. Venturi scrubbers are also known for their ability to operate at high temperatures and pressures, and for their low maintenance requirements.

Venturi scrubber Construction

A Venturi scrubber is a type of air pollution control equipment that uses the principle of a Venturi tube to mix water and contaminated air. The basic construction of a Venturi scrubber includes:

Inlet: The inlet section where the contaminated air is drawn into the scrubber.

Venturi section: This is the core of the scrubber where the air stream is constricted to create a pressure drop. This pressure drop causes an increase in the velocity of the air stream and also causes water to be drawn into the air stream through a separate water inlet.

Diffuser: The diffuser section is located after the Venturi section and it is designed to recover the pressure drop and reduce the velocity of the air stream.

Spray nozzle: The spray nozzle is used to atomize the water and spray it into the air stream. The water droplets act as a scrubbing media to remove the pollutants.

Demister : A Demister is typically located at the top of the scrubber to remove the water droplets from the air stream.

Outlet: The outlet section is where the clean air is discharged.

Additionally, the scrubber may include a water treatment system to remove pollutants and impurities from the water before it is reused.

The construction of the scrubber will vary depending on the type of pollutants being removed and the specific application. Some scrubbers are designed to handle high temperatures and corrosive materials, while others are designed to handle large volumes of air.

Venturi scrubber Components

A Venturi scrubber is a device used to remove particulate matter or other pollutants from a gas stream. It typically consists of the following components:

Inlet: The inlet is where the contaminated gas stream enters the scrubber.

Venturi section: This is the heart of the scrubber and where the gas stream is accelerated and mixed with the scrubbing liquid. The Venturi section is typically a tapered nozzle that increases the velocity of the gas stream, which creates a low pressure area that draws in the scrubbing liquid.

scrubbing liquid distributor: This component is used to distribute the scrubbing liquid evenly across the gas stream as it enters the Venturi section.

Demister Or Mist Eliminator: This component is used to remove droplets of liquid that are carried out of the scrubber by the cleaned gas stream.

Collection chamber: The collection chamber is where the particulate matter and other pollutants are removed from the gas stream and collected.

Outlet: The outlet is where the cleaned gas stream exits the scrubber.

Recirculation pump: This component is used to recirculate the scrubbing liquid back to the scrubbing liquid distributor.

Control valves: These are used to regulate the flow of gas and liquid in the scrubber and to maintain the desired pressure drop.

Air-water separator: This component is used to separate the water and particulate matter from the gas stream before it exits the scrubber.

Drain: The drain is used to remove the collected particulate matter and other pollutants from the scrubber.

Heating system : Some venturi scrubber require heating system to maintain the temperature of the scrubbing liquid or the gas stream.

Note that the specific components and design of a Venturi scrubber may vary depending on the application and the type of pollutants being removed.

Industrial applications

Venturi scrubbers are widely used in a variety of industrial applications for the removal of particulate matter and other pollutants from gas streams. Some common industrial applications include:

Air Pollution Control: Venturi scrubbers are commonly used in power plants, cement plants, and other industrial facilities to remove particulate matter, sulfur dioxide, and other pollutants from flue gas.

Pharmaceuticals And Biotech: Venturi scrubbers are used in the pharmaceutical and biotech industries to remove particulate matter and volatile organic compounds (VOCs) from process exhaust gases.

Chemicals and Petrochemicals: Venturi scrubbers are used in the chemical and petrochemical industries to remove particulate matter and VOCs from process exhaust gases.

Food and beverage: Venturi scrubbers are used in the food and beverage industry to remove particulate matter and VOCs from process exhaust gases.

Metal working and welding: Venturi scrubbers are used in metal working and welding operations to remove welding smoke and other pollutants from the exhaust gases.

Mining: Venturi scrubbers are used in mining operations to remove particulate matter and other pollutants from exhaust gases produced by drilling and blasting.

Wood working: Venturi scrubbers are used in wood working operations to remove sawdust and other particulate matter from the exhaust gases.

Glass Manufacturing: Venturi scrubbers are used in glass manufacturing operations to remove particulate matter and other pollutants from exhaust gases.

Pulp and paper: Venturi scrubbers are used in the pulp and paper industry to remove particulate matter and other pollutants from exhaust gases.

The specific design and operation of a Venturi scrubber will vary depending on the application and the specific pollutants to be removed.

Performance Parameters

Performance parameters for a Venturi scrubber include:

Collection Efficiency: The degree to which the scrubber is able to remove pollutants from the gas stream. This is typically measured as a percentage.

Pressure drop: The amount of pressure that is lost as the gas stream passes through the scrubber. This is typically measured in inches of water column (in. WC) or pascals (Pa).

Gas flow rate: The rate at which the gas stream is passing through the scrubber, typically measured in cubic feet per minute (CFM) or cubic meters per hour (m3/h).

Liquid Flow Rate: The rate at which the scrubbing liquid is being introduced into the scrubber, typically measured in gallons per minute (GPM) or liters per hour (L/h).

Liquid-to-gas ratio (L/G): The ratio of the liquid flow rate to the gas flow rate, typically measured in gallons per 1000 cubic feet (gal/1000 ft3) or liters per cubic meter (L/m3).

Note that these are the common parameters that are used to measure the performance of a Venturi scrubber, and other parameters may also be used depending on the specific application and design of the scrubber.

Cyclone separator:

Introduction, Working Principle, Construction, Components, Industrial applications, performance parameters

Cyclone Separator Introduction

A cyclone separator is a type of mechanical separator that uses centrifugal force to separate particles from a fluid. It typically consists of a cylindrical chamber with a conical top and bottom, and an inlet and outlet for the fluid. The fluid enters the chamber tangentially, creating a spinning motion that causes the heavier particles to be thrown to the outer wall of the chamber, where they can be collected. The cleaner fluid exits through the outlet. Cyclone separators are commonly used in industrial settings to remove dust and other particulate matter from air or gas streams.

Working Principle

A cyclone separator is a type of mechanical separator that uses centrifugal force to separate particles from a fluid. It works by creating a spiral flow of fluid through a cylindrical chamber, with a conical section at the bottom. As the fluid enters the cyclone, it is forced to spin rapidly due to the shape of the chamber. This spinning motion causes the heavier particles to be thrown towards the outer wall of the chamber, while the lighter particles are pulled towards the center.

The heavier particles then fall to the bottom of the conical section and are collected in a hopper or discharge pipe. The lighter particles, on the other hand, continue to move up the chamber and are discharged through the top of the cyclone.

Cyclone separators are commonly used in industrial processes, such as dust collection, air purification, and water treatment. They are also used in a variety of other applications, including separating particles from gases and liquids. The efficiency of a cyclone separator depends on several factors, including the size and shape of the chamber, the flow rate of the fluid, and the density of the particles being separated.

CONSTRUCTION :

A cyclone separator is a mechanical device that uses centrifugal force to separate particles from a fluid stream. The basic construction of a cyclone separator consists of the following

COMPONENTS:

Inlet: The inlet is the point where the fluid stream enters the separator. It is typically a pipe or duct that leads into the separator body.

Body: The body of the separator is the main component that houses the internal components of the separator. It is typically made of metal or plastic and is cylindrical in shape.

Vortex Finder: The vortex finder is a tube that extends from the top of the separator body and is used to guide the fluid stream into the cyclonic separation area.

Cylinder: The cylinder is the internal component of the separator that creates the centrifugal force needed to separate the particles from the fluid stream. It is typically a cone or a spiral shape that is located at the base of the separator body.

Outlet: The outlet is the point where the separated particles exit the separator. It is typically a pipe or duct that leads out of the separator body.

Clean Fluid Outlet: The clean fluid outlet is the point where the fluid stream exits the separator after the particles have been separated. It is typically a pipe or duct that leads out of the separator body.

Support structure: The support structure is the framework that holds the separator in place and provides stability. It is typically made of metal or plastic and may include legs or brackets to mount the separator to a wall or floor.

COMPONENTS

A cyclone separator typically has the following components:

Cylindrical Body: This is the main component of the separator and is used to create a centrifugal force that separates particles from the fluid.

Inlet: This is where the fluid enters the separator. It is usually located at the top of the cylindrical body.

Outlet: This is where the fluid exits the separator. It is usually located at the bottom of the cylindrical body.

Vortex Finder: This component is used to guide the flow of fluid through the separator and to maintain a stable vortex.

Collection chamber: This is where the separated particles are collected. It is located at the bottom of the separator and is connected to the outlet.

Drain: This is used to remove the collected particles from the collection chamber.

Optional: Some cyclone separators may also have additional components such as a dustbin, a bag house and/or a blower.

Industrial applications

Power Generation: Cyclone separators are used to remove dust and other particulate matter from the air in power plants. This improves the efficiency of the power generation process and reduces the risk of equipment damage.

Oil and Gas Industry: Cyclone separators are used in the oil and gas industry to separate oil, water, and gas in the production process. They are also used to remove sand and other debris from natural gas pipelines.

Cement Industry: Cyclone separators are used in cement plants to remove dust and other particulate matter from the air. This improves the air quality in the plant and reduces the risk of equipment damage.

Pharmaceutical Industry: Cyclone separators are used in the pharmaceutical industry to separate solid particles from liquids. This is important in the production of tablets and capsules.

Food Processing Industry: Cyclone separators are used in the food processing industry to separate solids from liquids. This is important in the production of jams, jellies, and other food products.

Chemical Industry: Cyclone separators are used in the chemical industry to separate particles from liquids and gases. This is important in the production of chemicals, pesticides, and fertilizers.

Pulp and Paper Industry: Cyclone separators are used in the pulp and paper industry to remove dust and other particulate matter from the air. This improves the air quality in the plant and reduces the risk of equipment damage.

Cyclone separator performance parameters

Collection efficiency: the percentage of particles or droplets that are successfully separated and collected by the cyclone separator.

Pressure Drop: the difference in pressure between the inlet and outlet of the cyclone separator. This parameter is used to measure the resistance to airflow through the system.

Cut size: the size of particle or droplet that is effectively separated by the cyclone separator.

Flow Rate: the amount of fluid or air that is processed by the cyclone separator per unit of time.

Vortex finder diameter: the diameter of the vortex finder, which is the component of the cyclone separator that separates the particles or droplets from the fluid or air.

Inlet velocity: the velocity of the fluid or air entering the cyclone separator.

Outlet velocity: the velocity of the fluid or air exiting the cyclone separator.

Length-to-diameter ratio: the ratio of the height of the cyclone separator to the diameter of the vortex finder, which affects the performance of the separator.

Solids loading: the amount of solids in the fluid or air that is processed by the cyclone separator.

Operating Temperature: the temperature at which the cyclone separator is operating, which can affect the performance of the separator.

Bag Filters:

Introduction, Working Principle, Types of bag materials, Cleaning mechanisms of bag filter, Construction, Components, Industrial applications, performance parameters

Introduction :

Bag filters are a type of air filter that use bags made of various materials, such as polypropylene or nylon, to trap particulates and other contaminants from the air. They are commonly used in industrial settings to remove pollutants from air streams before they are released into the environment, as well as in HVAC systems to improve indoor air quality. Bag filters can be designed to remove particles of different sizes and can be made with varying degrees of efficiency. They are relatively low-maintenance and can be easily replaced when they become clogged.

Working Principle :

Bag filters, also known as fabric filters, are air pollution control devices that use a fabric bag to remove particulate matter from the air. They work on the principle of mechanical filtration, where the particulate matter is captured on the surface of the fabric bag as the air passes through it.

The process begins with dirty air entering the filter housing and passing through the fabric bag. The particulate matter in the air is trapped on the surface of the bag, while the clean air exits through the other side. The bags are typically made of a synthetic material, such as polypropylene or nylon, which can withstand high temperatures and are resistant to abrasion.

The bags are usually arranged in a vertical configuration, with the dirty air entering at the bottom and the clean air exiting at the top. The bags can be arranged in a single row or in multiple rows, depending on the application.

As the bags become clogged with particulate matter, the pressure drop across the filter increases, indicating that it is time to change the bags. The bags can be easily replaced by removing them from the filter housing and installing new ones.

Bag filters are commonly used in industrial settings, such as power plants and cement factories, as well as in commercial and residential HVAC systems. They are effective at removing large particulate matter, such as dust and debris, but may not be as effective at removing smaller particles, such as smoke and fumes.

Types Of Bag Materials :

Polypropylene (PP) - This material is commonly used in bag filters due to its chemical resistance, high temperature tolerance, and low cost.

Polyester (PET) - PET is a strong and durable material that is resistant to most chemicals and high temperatures. It is also commonly used in bag filters.

Nylon (PA) - Nylon is a synthetic material that is known for its strength and durability. It is also resistant to most chemicals and high temperatures, making it a popular choice for bag filters.

Polyphenylene Oxide (PPO) - PPO is a thermoplastic material that is resistant to chemicals and high temperatures. It is also known for its excellent electrical insulation properties.

Polytetrafluoroethylene (PTFE) - PTFE is a fluoropolymer material that is known for its excellent chemical resistance and high temperature tolerance. It is also commonly used in bag filters due to its non-stick properties.

Acrylic (PMMA) - Acrylic is a thermoplastic material that is known for its high transparency and resistance to most chemicals. It is also commonly used in bag filters due to its high temperature tolerance.

Glass Fiber (GF) - Glass fiber is a material that is known for its high strength and temperature resistance. It is also commonly used in bag filters due to its excellent chemical resistance properties.

Cleaning Mechanisms Of Bag Filters :

Bag filters use mechanical or pneumatic cleaning mechanisms to remove trapped particles from the filter media. These mechanisms work by physically shaking or pulsing the filter bags to dislodge and remove the trapped particles.

Mechanical cleaning mechanisms include:

Reverse air: The filter bags are shaken by high-pressure air that is directed through the filter in the opposite direction of the airflow. This causes the trapped particles to be dislodged and collected in a hopper.

Pulse jet: The filter bags are shaken by high-pressure bursts of air that are directed through the filter in the same direction of the airflow. This causes the trapped particles to be dislodged and collected in a hopper.

Shaker: The filter bags are physically shaken by a mechanical device that is connected to the filter housing. This causes the trapped particles to be dislodged and collected in a hopper.

Pneumatic cleaning mechanisms include:

Air knife: The filter bags are shaken by high-pressure bursts of air that are directed through a nozzle that is positioned in close proximity to the filter bags. This causes the trapped particles to be dislodged and collected in a hopper.

Construction :

Bag filters are air pollution control devices that remove particulate matter from industrial exhaust gases by trapping the particles in a filter bag. The cleaning of bag filters is typically done by shaking or reversing the airflow through the filter to dislodge the collected particulate matter, which is then removed from the filter bag. In some cases, a pulse jet cleaning system may be used to clean the filter bags by injecting short bursts of compressed air into the filter bags to break up the collected particulate matter.

Construction of bag filters typically involves installing a housing that contains the filter bags, an air inlet, and an air outlet. The filter bags are made of a material that is able to trap the particulate matter, such as felt or woven fabric. The bags are suspended inside the housing, and the exhaust gas is forced to flow through the bags before being released to the atmosphere. Additional components, such as pre-filters, fans, and controls, may also be incorporated into the system to improve its performance and efficiency.

Bag Filters Cleaning Components :

Filter Media: This is the material that captures particles and pollutants from the air or fluid. Common materials used in bag filters include polypropylene, polyester, and cellulose.

Support Cage: This is the frame that holds the filter media in place and prevents it from collapsing. The support cage can be made of metal or plastic.

End Caps: These are the caps that seal the ends of the filter bag and keep the filter media securely in place.

Gasket: This is the seal that prevents air or fluid from bypassing the filter media. The gasket is typically made of rubber or silicone.

Cleaning Mechanism: This is the device or method used to remove the accumulated particles and pollutants from the filter media. Common cleaning mechanisms include mechanical shaking, reverse air flow, and ultrasonic cleaning.

Access Doors: These are the openings in the filter housing that allow for the removal and replacement of the filter bags.

Drainage System: This is the system that collects and disposes of the pollutants removed from the air or fluid by the filter media. It can include a drain valve, a collection tray, or a pump.

Industrial applications :

Power Generation: Bag filters are used in power plants to filter out particulate matter from the exhaust gases of boilers and turbines.

Cement production: Bag filters are used to filter out dust and particulate matter from the air in cement plants.

Steel production: Bag filters are used to filter out dust and particulate matter from the air in steel mills and foundries.

Pharmaceutical production: Bag filters are used to filter out dust and particulate matter from the air in pharmaceutical manufacturing facilities.

Food and Beverage Production: Bag filters are used to filter out dust and particulate matter from the air in food and beverage manufacturing facilities.

Mining: Bag filters are used to filter out dust and particulate matter from the air in mining operations.

Woodworking: Bag filters are used to filter out dust and particulate matter from the air in woodworking operations.

Chemical production: Bag filters are used to filter out dust and particulate matter from the air in chemical manufacturing facilities.

Textile manufacturing: Bag filters are used to filter out dust and particulate matter from the air in textile manufacturing facilities.

Automotive production: Bag filters are used to filter out dust and particulate matter from the air in automotive manufacturing facilities.

Bag Filters Performance Parameters :

Efficiency: The ability of the filter to remove particles from the air stream. This is typically measured in terms of percentage of particles removed at a specific particle size.

Pressure Drop: The resistance to airflow through the filter. This is measured in inches of water or pascals.

Service Life: The amount of time the filter can be used before needing to be replaced. This can vary based on factors such as the type of filter media and the level of contamination in the air stream.

Dust Holding Capacity: The amount of dust that can be collected by the filter before it needs to be replaced. This is usually measured in grams of dust per square foot of filter area.

Cleanability: The ease with which the filter can be cleaned and/or replaced. This can vary depending on the type of filter and the design of the filter housing.

Fire Resistance: The ability of the filter to resist ignition or combustion. This can be important for safety in certain environments.

Weatherability: The ability of the filter to withstand exposure to various weather conditions, such as humidity, temperature fluctuations, and exposure to sunlight.

Cost: The overall cost of the filter, including the initial purchase price and ongoing maintenance costs.

Electrostatic Precipitator:

Introduction, Working Principle, ionization or corona formation, particles charging

mechanisms, particle collection, particles removal, Types of ESP, Construction,

Components, Industrial applications, performance parameters

Introduction :

An electrostatic precipitator (ESP) is an air pollution control device that uses an electric field to remove particles from a gas stream. It works by charging the particles in the air stream, which then attach to negatively charged plates or wires within the device. The collected particles can then be removed and disposed of properly.

ESPs are commonly used in industrial settings, such as power plants and cement factories, to remove particles such as dust, ash, and smoke. They can also be used in other applications, such as in HVAC systems to remove indoor air pollutants. ESPs are considered to be highly efficient at removing particulate matter and are able to handle high flow rates and high temperatures.

Working Principle

An electrostatic precipitator (ESP) is a device that uses electrical forces to remove particles from an air or gas stream. The basic working principle of an ESP is as follows:

The air or gas stream containing the particles is directed through a series of electrodes, which are typically made of metal.

The electrodes are charged with a high voltage electrical charge, which creates an electrical field around them.

As the particles pass through the electrical field, they become charged and are attracted to the electrodes.

The particles are then collected on the electrodes, where they are removed and disposed of.

To prevent re-entrainment of the collected particles, the ESP is equipped with a removal system, such as a mechanical rapping system, to dislodge the particles from the electrodes.

The purified air or gas is then discharged from the ESP.

The ESP is used in many industrial processes such as power generation, chemical production, cement production and waste incineration, where it can be used to remove particulate matter from the air or gas stream.

It is important to note that electrostatic precipitator efficiency is affected by many factors such as particle size, particle shape, and electrical characteristics of the particles, and the temperature and humidity of the air or gas stream.

Ionization Or Corona Formation

Electrostatic precipitators (ESPs) use ionization or corona formation to remove particles from an air stream. The ionization process creates charged particles by exposing the air stream to a high voltage electric field. The charged particles are then attracted to and collected on oppositely charged plates or electrodes.

The process of ionization or corona formation in an ESP involves the following steps:

A high voltage electric field is created by applying a voltage between the electrodes in the ESP.
The air stream is exposed to this electric field, causing some of the air molecules to become ionized.
The ionized particles are then attracted to the oppositely charged electrodes, where they are collected.
The collected particles are then removed from the electrodes by various methods such as mechanical shaking, vibration or compressed air.

The efficiency of an ESP is highly dependent on the voltage applied, the distance between electrodes and the particle size. ESPs are typically used in industrial settings to remove particles from exhaust gases, but can also be used in other applications such as air purification or pollution control.

Particles Charging :

An electrostatic precipitator (ESP) is a device that uses electrostatic forces to remove particles from a gas or liquid stream. The particles in the stream are given an electrical charge by passing through a high-voltage field, and then they are collected on electrodes with the opposite charge. The collected particles can then be removed from the electrodes through a variety of methods, such as shaking or blowing them off. The charging of particles in ESPs is an important aspect of their operation, as it determines how effectively the particles can be removed from the gas or liquid stream.

Electrostatic Precipitator Mechanisms :

An electrostatic precipitator (ESP) is a device that uses an electric field to remove particles from a gas stream. The mechanism of an ESP consists of several components, including:

The inlet section, where the gas stream enters the ESP and is directed towards the collection electrodes.

The collection electrodes, which are typically made of metal plates or wire meshes. These electrodes are charged with a high voltage, typically in the range of 30,000 to 150,000 volts.

The discharge electrodes, which are located between the collection electrodes. These electrodes are usually made of thin wires and are connected to the opposite polarity of the collection electrodes.

The ionizer, which creates ions in the gas stream by corona discharge or radioactive sources. These ions attach to the particles in the gas stream, making them more susceptible to the electric field.

The dust collector, which is located at the bottom of the ESP and collects the particles that are removed from the gas stream. These particles can be collected in hoppers, bags, or cyclones.

The control system, which includes the power supply, voltage and current regulators, and monitoring devices to ensure the proper operation of the ESP.

The basic principle of an ESP is that the charged particles in the gas stream are attracted to the oppositely charged collection electrodes, where they are collected and removed from the gas stream. The efficiency of an ESP depends on several factors, including the strength of the electric field, the ionization of the particles, and the design of the collection and discharge electrodes.

Electrostatic Precipitator Particle collection :

An electrostatic precipitator (ESP) is a device that uses an electric field to remove particles from a gas stream. The particles are charged by passing them through a corona, which is created by a high-voltage electrode. The charged particles are then attracted to a series of collector plates, which are grounded. The collected particles are removed from the plates by mechanical means, such as rapping or vibration. ESPs are commonly used in power plants, cement plants, and other industrial facilities to control air pollution.

Electrostatic Precipitator Particles Removal :

An electrostatic precipitator (ESP) is a device that removes particles from a gas stream using an electric field. The particles are charged as they pass through the ESP and are then attracted to electrodes, where they are collected and removed from the gas stream. ESPs are commonly used in industrial settings to remove particulate matter from exhaust gases, such as those emitted by power plants, cement plants, and other heavy industries. They are also used in some air purification systems to remove pollutants from indoor air. The efficiency of an ESP can vary depending on factors such as the size and nature of the particles being removed, the strength of the electric field, and the design of the electrodes.

Types of ESP :

There are Several Types of Electrostatic precipitators, including:

Plate-Type ESP: This type of ESP uses a series of parallel plates as electrodes. The particles are charged as they pass through the ESP and are then attracted to the plates, where they are collected and removed.

Wire-Type ESP: This type of ESP uses a series of wires as electrodes. The particles are charged as they pass through the ESP and are then attracted to the wires, where they are collected and removed.

Hybrid ESP: This type of ESP combines the features of both plate-type and wire-type ESPs. It uses a combination of plates and wires as electrodes to remove particles from the gas stream.

Dry ESP: This type of ESP uses dry-condition to remove particles from the gas stream. no moisture is used in the ESP.

Wet ESP: This type of ESP uses a moisture to remove particles from the gas stream. Moisture is used to help neutralize the particles and make them easier to collect.

Pulse-jet ESP: This type of ESP uses pulses of compressed air to remove particles from the gas stream. The compressed air creates a strong force that pushes the particles towards the electrodes, where they are collected and removed.

Rapping-type ESP: This type of ESP uses mechanical rapping to remove particles from the electrodes. A series of hammers or mechanical rapping devices are used to knock the particles off the electrodes, where they are collected and removed.

Components :

An electrostatic precipitator (ESP) is a device that uses an electric field to remove particles from a gas stream. The basic components of an ESP include:

Power supply: This provides the high voltage electrical energy needed to generate the electric field.

Electrodes: These are the metal plates or wires that carry the electrical charge. They are usually made of stainless steel or aluminum.

Insulators: These are used to prevent electrical arcing between the electrodes and collecting plates. They are usually made of ceramic or plastic.

Gas Ducts: These are the pipes or ducts that carry the gas stream through the ESP.

Control system: This includes the control panel and monitoring equipment used to control and monitor the operation of the ESP.

Ash Handling System: This includes the equipment used to remove the collected particles from the ESP and transport them to a storage or disposal area.

Maintenance access doors and panels: These provide access to the interior of the ESP for maintenance and inspection.

Supporting structure: This includes the framework and supports that hold the ESP components in place.

Electrostatic precipitators (ESPs) are air pollution control devices that remove particles from a gas stream using an electric field. The performance of an ESP can be evaluated using several parameters, including:

Collection Efficiency: This is the percentage of particulate matter that is removed from the gas stream by the ESP. It is usually measured by comparing the concentration of particles before and after the ESP.

Pressure Drop: This is the increase in gas pressure caused by the ESP as it passes through the device. A high pressure drop can increase the energy consumption of the ESP and make it more difficult to maintain the desired flow rate.

Current Efficiency: This is the ratio of the total current passing through the ESP to the current that is actually used to charge the particles. A high current efficiency indicates that a smaller amount of energy is required to remove a given amount of particles.

Ash resistivity: This is the resistance to the flow of electric current through the collected particulate matter. A high ash resistivity can indicate that the ESP is not functioning properly, as it may indicate that the particulate matter is not being effectively charged by the ESP.

Cleaning frequency: This is the frequency at which the ESP needs to be cleaned to maintain its efficiency. A high cleaning frequency may indicate that the ESP is not functioning properly.

De-dusting time: The time required to remove a specific amount of dust from the ESP.

Re-entrainment: This is the amount of dust that is re-entrained in the gas stream after it has passed through the ESP.

ESP age and condition: ESP's performance may decrease as it ages, so its age and condition must be taken into account when evaluating its performance.

Control of Particulates: Particulate control mechanisms

Unit: 2