Air Pollution Control
Equipment
Introduction
This article will take an in-depth look at air pollution
control equipment.
You will learn about:
What is Air Pollution Control Equipment?
History of Air Control Equipment
Types of Air Pollution Control Equipment
Applications of Air Pollution Control Equipment
Maintenance Tips for Air Pollution Control Equipment
Air Pollution Prevention Tips
And much more...
Chapter 1: What is Air Pollution Control
Equipment? How Does it Work?
Considerations When Choosing This
Equipment
The term "air pollution control equipment" refers to
systems that stop a range of solid and gaseous pollutants
from entering the atmosphere, primarily through industrial
exhaust stacks (chimneys). These controls are divided
into two categories: ones that limit the emissions of acidic
gasses and those that limit the emissions of particulate
matter.
How Does Air Pollution Control Equipment
Work?
There are three primary ways that air pollution control
technology can operate:
1. Chemical Modification: In this technique, a
hazardous chemical is changed into an inert
chemical. Typically, flue gas desulphurization is used.
Selective catalytic reduction and non-catalytic
reduction methods are used to control the emissions
of nitrogen oxides from stationary by converting
nitrogen oxides (NOx) into molecular nitrogen (N2).
Technicians may use biofiltration, thermal oxidation,
or catalytic oxidation.
2. Hazard Removal: The most prevalent and
straightforward air purification method is to eliminate
hazards from the air. There are numerous ways to
accomplish this, but air filter systems are typically
used.
Monitoring Air Pollution Control Equipment
Since operational environments and conditions vary from
one facility to another, for any particular classified source,
selecting the proper monitoring equipment or method
entails more than just performance comparisons and
basic costs. Every installation and facility requires a
different type of monitoring equipment, a decision that is
based on several factors.
Considerations when Choosing Air Pollution Control
Equipment
Before deciding, it is crucial to consider the physical
and chemical characteristics of the pollutant and
waste gas stream.
Monitoring equipment must be compatible with the
system for which it will be used; carefully review the
regulatory or permitting restrictions and other related
reporting requirements.
How and where samples are collected, processed,
and disposed of affects the chosen equipment.
They ought to adhere to standards for calibration and
accuracy.
Quality is the most important consideration when
selecting monitoring equipment; make sure the
quality satisfies the quality control standards.
All equipment needs maintenance. Make sure
maintenance service is easy.
The monitoring must not obstruct the management
and safety system.
All these elements will aid in purchasing monitoring
equipment to meet the needs.
Chapter 2: History of Air Pollution
Equipment
One of the results of the Industrial Revolution was the
rapid rise in air pollution produced by fuels burned during
industrial processes. In addition, as industries grew and
expanded, natural resources like wood, coal, water, and
land were overused.
By the middle of the 20th century, people started to
notice the effects of unrestrained industrialization. For
instance, air pollution in Donora, Pennsylvania, which had
reached deadly levels, resulted in the deaths of 20 people
and the illness of 7,000 more in 1948. London underwent
a period known as "The Great Smog" in 1952. This thick,
impenetrable fog resulted from sulfur particles combined
with the gasses from burning coal. In addition to animals,
12,000 people perished during the five-day haze. An air
pollution disaster brought on by the Union Carbide factory
in Bhopal, India, in 1984 resulted in the sickness or injury
of between 150,000 and 600,000 residents as well as the
death of close to 4,000 manufacturing workers.
Governments worldwide have implemented various clean
air regulations to combat these horrible catastrophes. For
instance, the UK government enacted the first Clean Air
Act in 1956. This halted the burning of coal in cities. In
1970, the United States adopted its own Clean Air Act.
After the clean air legislation passed, companies started
using different air pollution control equipment that had
been created much earlier. One was the electrostatic
precipitator, which German mathematician Dr. M. Hohlfeld
created in 1824. Around 80 years later, in 1907, Professor
Frederick Gardner Cottrell obtained a patent for the first
mass-producible electrostatic precipitator. At that time, a
precipitator captured, treated, and eliminated sulphuric
acid.
The Clean Air Act of 1990 made periodic monitoring of
some specified pollutants at various stationary sources a
requirement. Monitoring equipment is just as vital as
pollution control equipment to comply with legal
restrictions and monitoring requirements. Data on
particulate matter and gaseous pollutants are kept with
monitoring equipment, which is important for auditing and
obtaining licenses for new and existing plants.
Additionally, emissions are monitored to evaluate the
effectiveness of the pollution control systems and the
status of health and safety inside a facility.
The commitment of many people has resulted in a
significant reduction in VOC and HAP emissions during
the past few years. However, global climate change has
brought carbon emissions to the forefront of concern. As
a result, policymakers and environmentalists are
collaborating to draft legislation to reduce carbon
emissions drastically. Given these recent and impending
laws, manufacturers may need to be ready to discover
alternatives to incinerators and oxidizers. These
alternatives include filtering system components like mist
collectors, wet scrubbers, dry scrubbers, electrostatic
precipitators, etc.
Leading Air Pollution Control
Manufacturers and Suppliers
Anguil Environmental Systems, Inc.
Dürr Systems, Inc.
The CMM Group
Pollution Systems
Ducon Environmental Systems
Chapter 3: Types of Air Pollution
Control Equipment
With the rising concern for sustainability and pollution
control, every industrial operation has some form of a
pollution control system to reduce emissions of organic
compounds (VOCs), hazardous air pollutants (HAPs), and
greenhouse gasses (GHG). Regular inspections,
certifications, and government oversight necessitate and
require the implementation of such processes.
Air pollution control equipment manufacturers provide
their customers with a wide assortment of alternatives
that fit the specific conditions and environment where
they will be installed.
Carbon Adsorbers
Another type of air pollution control equipment is a carbon
adsorber that filters polluted air as it passes over or
through an activated carbon bed. The carbon bed
adsorbs and traps the VOCs as the air stream passes,
releasing only clean air.
Many different processes and valuable materials,
including lithium hydroxide, sodium hydroxide, amines
(such as monoethanolamine), minerals, and zeolites, can
be used in carbon absorbers (ex., serpentinite).
Air Scrubbers
It is an air purification system that filters or cools the
airstream as it enters the scrubber to remove particulate
matter from the air. Wet and dry air scrubbers are
distinguished by how they remove particles. An air
scrubber's main purpose is to purify the air after it has
been polluted with harmful gasses, chemicals, fumes, and
pollutants.
Wet Air Scrubbers
Wet air scrubbers employ liquid solvents, while dry
scrubbers use solid materials to remove pollutants. Both
eliminate associated odors and gas contaminants from
industrial exhaust streams. Wet air scrubbers often
remove more pollutants from the air than dry air scrubbers
do. As they prevent pollutants from contaminating outside
air, they are essential for industrial manufacturing or
wastewater treatment plants. Wet air scrubbers can come
in various shapes and sizes and can be used in any
industry that releases air pollutants.
Wet air scrubbers work by absorbing contaminants with
water or a water-based solvent. The contaminated gas
enters the wet scrubber from the bottom, moves upward
via the packed bed, and the downward-moving solvent
sprays. Before the gas leaves the scrubber, it travels
through a mist eliminator to catch any droplets. The
contaminants are caught in the solvent droplets. In a
metal or composite container, the liquid solvent is
contained. The solvent is passed through by
contaminated gas. As it does so, the scrubber emits clean
gas while the solvent absorbs the pollutants.
The solvent's composition impacts how well it can remove
impurities. The electric charge of the solvent is a crucial
component. The solvent's ability to bond with various
inorganic contaminants depends on its charge, which
might be positive, negative, or neutral.
Dry Air Scrubbers
To target specific contaminants, dry air scrubbers quickly
spray chemicals into the exhaust stream. Pollutants fall
out of the air stream due to the reaction between the
reagent and the pollutants. A dry air scrubber is
environmentally benign since the collected particles and
spray are either burned off in the heat of the air stream or
caught in a filter.
A dry air scrubber requires no removal or storage of
wastewater, making operation more cost-effective. Dry
scrubbers are primarily used to catch solvents and acidic
vapors.
Electrostatic Precipitators
These filterless devices remove solid, droplet-shaped,
gaseous, or liquid particles from the air using an electric
charge. It is a tool for reducing air pollution that filters
pollutants out of the smokestacks of factories,
manufacturing facilities, and power plants. The
electrostatic precipitator collects smoke or gas as it exits
a burner or furnace by passing the gas or smoke over
wires or plates. This process gives the gas or smoke a
static charge, which is then collected on a second plate
with a negative charge, where the pollutant particles are
held. With only a small quantity of electrical energy,
electrostatic precipitators can be precisely tuned to meet
the requirements of the pollution circumstances.
Most enterprises produce their goods using fossil fuels,
which causes smoke to be released into the atmosphere
that comprises soot, ashes, and unburned CO2. Using an
electric charge, electrostatic precipitators (ESPs) remove
the soot, ashes, and unburned carbon dioxide from the
smoke and release clean air or smoke into the sky. Since
these dangerous particles can harm people, the
environment, and structures, extraction of these particles
is crucial.
Particulate matter from contaminated air is removed using
electrostatic precipitators. Dust, smoke, soot, ashes, and
fumes are a few examples of the various types of
particulate matter.
Oxidizers
Oxidizers utilize thermal decomposition, also known as
incinerators, to treat waste gasses or plant emissions that
include dangerous chemicals. The preheated waste gas is
oxidized in oxidizers, which resemble burners or reactors
and operate at temperatures of up to 1832 °F (1,000 °C).
Thermal oxidizers convert HAPs and VOCs with organic or
hydrocarbon bases into carbon dioxide and water. The
waste gas stream is first introduced into the combustion
chamber while a high-draft fan provides air. The supplied
air volume is kept at levels that will burn the flammable
substances. The air is supplied in addition to producing
complete combustion to dilute the waste gas stream to
safe levels. Unless a suitable concentration monitoring
system exists, where the maximum LEL can be extended
to 50%, the (LEL) at the combustion chamber must be at
most 25% for safe operation. The chamber and the vent
system may explode if the LEL of the waste gas
compounds is reached.
To operate safely, the combustion chamber's combustible
gas concentration should not exceed 25% of the lower
explosive limit (LEL). However, upstream monitoring can
occasionally allow for up to 50% deviations. The waste
gas stream is ignited in the combustion chamber after
diluting it. The gas is burned using a guided burner or
igniter. The heat produced is minimal because the gas is
diluted with air. Additional auxiliary fuel is pumped into the
system to maintain chamber temperatures if the
combustion is not self-sustaining.
Some oxidizers can burn continuously without the use of
additional fuel. For instance, catalytic oxidizers use
catalyst media—a substance that speeds up a chemical
reaction without depleting itself—to help the reaction. As a
result, there is reduced fuel consumption and a lower
operating temperature than with a thermal oxidizer. To
save even more energy, air-to-air heat exchangers may
preheat the input air with the hot, treated exhaust gas at
the output.
Utilizing the chamber's exhaust heat is another approach
to raising the temperature inside the chamber without
consuming a lot of extra fuel. The heat energy in the
exhaust gasses after burning would be lost if discharged
immediately. Instead, heat is transferred from the intake
air stream to the exhaust air stream using heat
exchangers. As a result, less heat is needed to ignite the
warmed air that enters the chamber. The air can be
warmed up using ceramic media inside the combustion
chamber.
The heat from the earlier reaction is absorbed by the
ceramic media and transferred to the entering stream of
gasses.
Through a stack, the exhaust gasses are vented into the
atmosphere. A stack is typically built to naturally transfer
air from the combustion chamber. First, several sampletaking probes are arranged in a row along the stack. Then,
systems for monitoring emissions process the samples.
Additional downstream or stream equipment is required
due to the possibility of acid-forming substances and
particle debris in the waste gas stream. Scrubbers,
particularly wet ones, are a common option for removing
acid vapors.
A strong electric field is used by wet electrostatic
precipitators (WESP), a method of controlling particulate
matter, to charge and collect particles and droplets onto a
collection surface. As a gas stream passes through the
collection section, a discharge electrode charges the
particles negatively. As a result, the particles are drawn to
the grounded surface of the collection electrode by their
negative charge. WESPs function at low-pressure drops
and remove over 90% of the collected material.
Catalytic Oxidizers
Catalytic oxidizers use high heat or elemental additions to
burn VOCs.
Thermal oxidizers extract oxygen from volatile organic
compounds (VOCs) by soaking contaminated air in
platinum or palladium. Non-toxic byproducts like nitrogen
and oxygen are produced throughout the process.
Either of these processes could be regenerative or
recuperative. Because it enables companies to recycle
heat and save expenses, this feature benefits industrial
manufacturing facilities in the agricultural,
mining/geochemical, pharmaceutical, auto, and other
sectors that lose money running pollution control systems
inside and outside.
Regenerative Thermal Oxidizers
Ceramic heat transfer beds are used by regenerative
thermal oxidizers (RTOs) to recover as much energy
emitted during oxidation as is practical. Usually, this
amounts to 90% to 95%. The first step of the procedure is
heating the entering waste gasses directed by control
valves. The intake temperature is then increased from the
ambient level to levels close to combustion. Less heat
transfer occurs because the ceramic bed cools down as
the incoming gasses absorb the most heat. The control
valves then divert the intake flow to another heated
ceramic bed. Finally, to be ready for another heating
phase, the cold ceramic bed goes through a heat
regeneration phase from the exhaust gasses.
Recuperative Oxidizers
In contrast, recuperative oxidizers warm-up polluted gas
in an energy recovery chamber using shells, tubes, plates,
or another type of traditional heat exchanger. By using the
energy released by oxidized VOCs, they can sustain
themselves. Through the heat exchanger, the operation
begins by raising the temperature of the incoming waste
gas. After burning, the mixture of waste gas and the air is
released to the stack after passing through the other side
of the heat exchanger. Next, the heat exchanger increases
the intake temperature by recovering heat from the
exhaust. The two types of heat exchangers are plate and
shell and tube. Thermal oxidizers with plate heat
exchangers have higher thermal efficiency at lower
operating temperatures and need less capital investment.
On the other hand, heat exchangers with shells and tubes
are favored at higher operating temperatures.
Direct-Fired Thermal Oxidizers
The simplest thermal oxidizers are direct-fired thermal
oxidizers (DFTO), commonly referred to as afterburners.
They don't use preheating or heat recovery techniques
when introducing the waste gas stream into the
combustion chamber. Instead, the hot air stays in the
firing chamber for a predetermined period after entering,
known as the residence or dwell time.
When the desired thermal destruction rate efficiency
(DRE) is obtained, the firing chamber operates at 1800 °F
to 2200 °F (982-1204 °C) with airflow rates of 500 cu ft
to 50,000 cu ft. Emissions are controlled during this time.
Safe air and water vapor are released once the DFTO has
processed the emissions. The least amount of capital is
required to achieve emission compliance with DFTOs,
which have a 99% efficiency rate for destroying
hydrocarbons.
Flameless Thermal Oxidizers (FTO)
This thermal oxidizer uses specially created non-catalytic
ceramic beds with good thermal and flow dispersion
qualities. Unlike other thermal oxidizers, this one premixes
the air and waste gasses before introducing them to the
combustion chamber. Burners or earlier processes
preheat the combustion. When the air and gas mixture
enters the combustion chamber, the high temperatures
cause them to ignite. Burners and electric heaters are
used to heat ceramic media to operational temperatures
when the exothermic reaction of the air and gasses is
insufficient.
Mist Collectors
Mist collectors, often known as mist or moistureeliminator filters, are air pollution management tools that
remove moisture and vapor from gas streams, such as
smoke, oil, mist, etc. The liquid droplets are separated
from the gas using fine mesh filters, which are then
collected in a different chamber for processing and,
possibly, recovery and reuse.
With some types delivering 99.9% efficiency for particles
with a diameter of less than 0.3 mm, mist collectors
maintain high filtration efficiencies for submicron liquid
particles. Mist collectors can process caustic and acidic
gas streams. However, they cannot process gas streams
with large particulates because they could clog the
collector's filter. Additionally, they are not employed in
applications where the temperature exceeds 120 °F (48
°C).
Cyclone Dust Collectors
Cyclones, also known as cyclone dust collectors, are air
pollution control tools that separate dry particulate matter
from gaseous pollutants like air filters. Cyclones, however,
use centrifugal force to collect and remove particulates
rather than a filtration medium. Gas streams enter a
cyclone and move through the cylindrical chamber in a
spiral motion. Large particles are propelled against the
chamber wall by the swirling motion, which reduces their
inertia and causes them to fall into the collection hopper
below for additional processing and disposal. Upward and
out of the cyclone, the cleansed gas streams continue.
With larger or smaller particle sizes, efficiency rises or
falls correspondingly. After cyclones are in an air pollution
control system, smaller particles are typically removed
using other filtering devices, such as baghouses.
Catalytic Reactors
Selective catalytic reduction (SCR) systems, also known
as catalytic reactors. These air pollution control
technologies are frequently used to reduce nitrogen oxide
(NOx) emissions caused by the combustion of fossil fuels
in industrial applications. The industrial exhaust and
pollutants are initially exposed to ammonia, which
interacts with the NOx molecules to create nitrogen and
oxygen. These devices, like incinerators, also use different
catalysts that allow some lingering gaseous pollutants to
proceed through combustion for additional processing
and reduction. For example, the three-way catalytic
converter in a car's exhaust system is used to lower the
levels of NOx, CO, and other VOCs in the engine
emissions, making modern autos one typical place where
catalytic reactors are utilized.
SCR systems can achieve more than 90% efficiency for
reducing and removing NOx, while other gaseous
pollutants can achieve 99.99% efficiency with less energy
than incinerators. However, despite their high potential
efficiency, SCR systems are only appropriate for some
gaseous pollution reduction applications due to their high
cost and inability to process emissions and exhaustcontaining particulates.
Biofilters
These filters use microorganisms to reduce and remove
water-soluble chemicals in their air pollution management
process. The microorganisms used include bacteria and
fungi. Biofilters eliminate pollutants to lessen their
presence in industrial emissions and exhaust, much like
incineration systems do. The microorganisms in biofilters,
however, take in and break down gaseous pollutants like
VOCs and organic HAP without producing byproducts
usually created during combustion, such as NOx and CO.
Over 98% efficiency is achievable with these devices.
Chapter 4: Applications and
Maintenance of Air Pollution
Equipment
Applications of Air Pollution Control
Equipment
Equipment used in industrial processes to control air
pollution is essential and needs to be addressed. Any
industry can be named, and it will become clear how
much toxic material it releases into the environment due
to its operations. The petroleum, oil, coal, metal, chemical,
and waste management sectors are a few major
companies that have contributed significantly to
environmental pollution.
Industrial procedures – including sourcing raw materials,
manufacturing the final product, maintaining the site and
machinery, and transporting the product to different
locations – result in some pollution. Volatile hydrocarbons
are released when fossil fuels are burned. Carbon dioxide
and sulfur dioxide are produced when wood and coal are
used as fuel, and a significant amount of harmful carbon
comes from automobiles. Every industrial process
produces emissions that contaminate the air, the soil, or
the water.
1. Reducing the discharge of dangerous gasses and
stopping the spread of air and water pollution are the
objectives of industrial air pollution control
equipment.
2. Protect any remaining natural resources for future
generations.
3. Reduce pollution-related risks to health that can be
inhaled or otherwise ingested.
Additionally, homes, cars, and other moving objects use
non-industrial air pollution control technology. For
instance, filtration technology in the home clears air
conditioners of impurities like pet dander, allergies, mold
spores, and dust.
In addition, precision filtration systems reduce vehicle
emissions from engines, exhaust pipes, and air
conditioning systems.
Maintenance of Air Pollution Control
Equipment
1. By doing routine tests all year long, you can prevent
sudden shutdowns. Make a monthly schedule for
testing the alarm system, intake valves, or control
components. Manufacturers can assist in identifying
faults before they impact output by ensuring the
equipment is operating as planned. These tests can
also guarantee the accuracy of the emission values
used to meet EPA regulations.
2. Unwanted debris and dirt can accumulate inside the
unit over time, reducing how well the system
functions. Manufacturers can prolong the life of the
equipment by designating specific days for thorough
equipment cleanings. Consistent checks ensure that
equipment goes smoothly without being inspected,
regardless of whether the equipment needs a
thorough cleaning every time.
3. In some circumstances, the machinery can need
replacement components or the help of a
professional in pollution control units. Adding a yearly
or biannual visit with an expert can help
manufacturers discover bigger concerns concealed
from the untrained eye, even if the equipment
appears to function well. In addition, manufacturers
can save costs related to employee training on
difficult repairs by using maintenance specialists.
Chapter 5: Continuous Emission
Monitoring Systems (CEMS)
Many facilities use continuous emissions monitoring
systems (CEMS) tools to monitor, control, and report
emissions. Various instruments are employed as
monitoring equipment to directly measure the
concentration of particulate matter and gaseous
chemicals at various locations. These are frequent spots
in a stack or duct. They also take note of a waste gas
stream's physical characteristics, such as opacity. The
New Source Performance Standard (NSPS) and the New
Source Review (NSR) call for monitoring emissions at
large sources of pollution. Additionally, some EPA
requirements mandate continuous emissions monitoring.
Along with parametric monitoring, continuous emissions
monitoring aids technicians in adhering to the Compliance
Assurance Monitoring (CAM) rules.
Parametric Monitoring
Emissions are measured in parametric monitoring by
monitoring important parameters related to the operating
status of process equipment or air pollution control
equipment. Pollutant emission levels and monitored
control parameters form the basis of parametric
monitoring. CAM regulation has helped parametric
monitoring gain some acceptance because it is a more
adaptable and affordable method for demonstrating
compliance.
Chapter 5: Air Pollution Prevention
Tips
1. Use public transport whenever possible. For
example, a bus can carry about 40 to 50 people at a
time, while cars can only carry approximately one to
four. Therefore, bus transit is better for the
environment.
2. Use smart air filtering technology. Pollution can also
enter indoor spaces. Consider getting an indoor air
pollution control system. These systems keep the
home environment clean while ensuring safe living for
the user and their loved ones.
3. Use clever waste management strategies. People's
bad behaviors are to blame for the increase in air
pollution. As a result, it is important to dispose of
waste responsibly and follow legal requirements.
4. To prevent the release of toxic chemicals and other
pollutants into the environment, industries should
implement sound waste management strategies.
5. Adopt eco-friendly habits. People and corporations
should adhere to practices that have no negative
effects on the environment.
6. Create a maintenance schedule for the equipment
that controls pollutants and follow it. For the greatest
performance, industrial and domestic pollution
control equipment must be serviced periodically.
7. Avoid using products containing chemicals. Products
with chemicals should be used sparingly or outside
the house. Examples include paints and perfumes.
Utilizing goods with low chemical content and
organic qualities is another option.
8. Lastly, implement afforestation by planting and
cultivating as many trees as possible. The act of
planting trees improves the ecosystem greatly and
aids in the release of oxygen.
Leading Air Pollution Control
Manufacturers and Suppliers
Anguil Environmental Systems, Inc.
Dürr Systems, Inc.
The CMM Group
Pollution Systems
Ducon Environmental Systems
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