Air Pollution Control Equipment Quiz

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Questions and Answers

Which method is NOT commonly used for pollution control operations to destroy or capture gases?

Electrolysis (correct)

Condensation

Adsorption

Absorption

What is a key factor in selecting air pollution control equipment?

Duration of operation

Exhaust gas characteristics from emissions tests (correct)

Cost of installation

Color of the emissions

Which device is primarily used for collecting particulate emissions from a gas stream?

Cyclone (correct)

Thermal incinerator

Catalytic incinerator

Boiler

What parameter is NOT included in the exhaust gas characteristics for air pollution control?

Plant aesthetics Signup and view all the answers

Which of the following control devices is best suited for capturing larger particles before using further treatment?

Settling chamber Signup and view all the answers

Which of the following represents a process characteristic that affects pollution control equipment selection?

Anticipated changes in control regulations Signup and view all the answers

Which combination of devices is likely to yield the best collection efficiency for particulate emissions?

Settling chamber followed by electrostatic precipitator Signup and view all the answers

What is the purpose of a scrubber in air pollution control?

To neutralize harmful gases Signup and view all the answers

What distinguishes fugitive emission points from other emission sources?

They are unconfined before reaching the atmosphere. Signup and view all the answers

Which of the following is NOT a step in the control strategy for industrial environmental impact?

Creation of new emission sources Signup and view all the answers

What is the primary function of tall exhaust stacks in pollution control?

To distribute pollutants more effectively into the atmosphere. Signup and view all the answers

What type of control procedures can be implemented for stationary sources of pollution?

Changing plant operations. Signup and view all the answers

Which of the following measures contributes to the compliance with emission standards?

Implementation of pollution prevention techniques. Signup and view all the answers

What was a common misconception about the use of elevated exhaust stacks?

They would reduce nearby community effects. Signup and view all the answers

What is one negative outcome of using tall exhaust stacks?

Transfer of pollution to another location. Signup and view all the answers

Which pollution control technology approach emphasizes practical solutions?

Instilling common sense solutions. Signup and view all the answers

What is a primary source of air pollution from stationary sources?

Incomplete combustion of fuel Signup and view all the answers

Which pollutant is commonly emitted from fossil fuel fired boilers?

Sulfur dioxide Signup and view all the answers

Which category includes emissions from auxiliary losses of compounds?

Volatile Organic Compounds Signup and view all the answers

What type of emission is associated with oxidizing processes?

Waste emissions Signup and view all the answers

What factors affect the specific type of pollutants emitted from stationary sources?

Specific process operations Signup and view all the answers

Metallurgical plants are known to emit which of the following?

Iron oxides Signup and view all the answers

Which of these is NOT a source of air pollution from stationary sources?

Volcanic eruptions Signup and view all the answers

What is a characteristic of gaseous emissions from industrial plants?

They are often dependent on the product being manufactured. Signup and view all the answers

What is one of the primary advantages of gravity settlers?

Low initial cost and maintenance Signup and view all the answers

Which type of fabric filter can operate at the highest temperature limit?

Fiberglass Signup and view all the answers

Which of the following materials is NOT suitable for fabric filters?

Wet air systems Signup and view all the answers

What mechanism is commonly employed for the cleaning of fabric filters?

Reverse air Signup and view all the answers

In a pressure system for fabric filtration, how do gases typically enter the baghouse?

Through the cleanout or hopper Signup and view all the answers

What is the approximate efficiency of baghouse filters for particles larger than 5 μm?

99.5% Signup and view all the answers

Hybrid systems for air control devices combine which of the following components?

Electrostatic precipitation and mechanical collectors Signup and view all the answers

Which type of industrial collector is referred to as a cyclone?

Centrifugal separator Signup and view all the answers

What is a primary characteristic of electrostatic precipitators (ESPs)?

They are used almost universally in power plants. Signup and view all the answers

Which type of electrostatic precipitator configuration is most commonly installed?

Plate Signup and view all the answers

Under which condition is a wet scrubber most likely used?

When air is wet and possibly corrosive. Signup and view all the answers

How do electrostatic precipitators typically remove collected particles?

Through a rapping mechanism. Signup and view all the answers

What is a key feature of wet scrubbers?

They often utilize water to assist in removal. Signup and view all the answers

What is the role of a venturi scrubber?

To assist in gas absorption. Signup and view all the answers

What electrical potential can electrostatic precipitators typically operate at?

30-75 kV Signup and view all the answers

What type of particles are electrostatic precipitators particularly effective in removing?

Small particles from gas streams. Signup and view all the answers

Which hybrid system is specifically designed to handle wet filtration processes?

Wet electrostatic precipitators Signup and view all the answers

What is the cut diameter for which a cyclone collector achieves 50% particle removal efficiency?

$10 , ext{μm}$ Signup and view all the answers

Which of the following describes the operational principle of cyclones?

Relies on inertial effects without moving parts Signup and view all the answers

What is the maximum particle size that cyclones can efficiently handle?

50 μm Signup and view all the answers

In the given formula for cut diameter, what does $H$ represent?

Height of the cyclone Signup and view all the answers

What is the significance of the dynamic viscosity ($, ext{μ}$) in the cut diameter formula?

It determines gas resistance Signup and view all the answers

Given the conditions for a standard cyclone, what is the effective number of turns ($, ext{θ}$)?

37.7 Signup and view all the answers

What does the variable $, ext{ρp}$ denote in the context of the cyclone formula?

Particle density Signup and view all the answers

Study Notes

Air Pollution Control of Stationary Sources

Stationary sources of air pollution often result from incomplete fuel combustion or industrial processes.
The types of pollutants emitted depend on the specific process.
Examples of pollutants from fossil fuel boilers include ash, sulfur dioxide, nitrogen oxides, mercury, and possibly vanadium.
Metallurgical plants may emit metal dusts like iron oxides, sometimes fluorides, and chlorides.
Industrial plants producing inorganic chemicals release various gases depending on their product.
Odorous organic waste gases can also come from organochemical and petrochemical plants.

Industrial Pollutant Sources

Industrial pollutant sources can be categorized based on their process operations.
Process Operations: Characterized by incomplete chemical reactions, leading to unconverted reactants or reaction yields lower than theoretical maximum.
Atmospheric Releases: Results from the release of process secondary components or impurities from raw materials.
Auxiliary Losses: Losses of compounds like volatile organic solvents, carbon disulfide, hydrogen sulfide, and fluorine compounds during various industrial processes.

Waste Emissions

Emission points can originate from multiple points and may not be centrally collected.
Air release points (e.g., stack, duct, vent) are categorized and can be fugitive or area point sources.
Fugitive points are not confined by stacks or ducts before entering the atmosphere.
Whether a source is considered a point or fugitive depends on emission confinement.

Industrial Process Operation Air Emission Points

A table categorizing process operations and fugitive sources.
- Process Operations: Reactors, distillation systems, vacuum systems, combustion stacks, blow molding, spray drying equipment, and extrusion machines
- Fugitive Sources: Valves, pump seals, flanges, connectors, compressors, open-ended lines, pressure relief devices, equipment cleaning, handling, storage, loading, storage tank breathing losses, loading/unloading, line venting, packaging and container loading, surface area sources

Pollution Control

Pollution control can include the implementation of effective control technology, changes in production processes, and pollution prevention measures.
Compliance with emission standards depends on effectively applying appropriate stationary source control measures.

PM Control Procedures

Control procedures for stationary pollution sources may involve using tall smokestacks, plant operation adjustments, and effective control devices.
A four-step control strategy for industrial impacts may include eliminating the problem source, modifying it, relocating it, and choosing the right control technology.

Exhaust Stacks

Exhaust stacks elevate emissions to disperse them more effectively, reducing local pollution impact.
In the past, elevated stacks prevented nearby communities from experiencing pollutant impacts, despite not eliminating the problem but transferring it.
Some concerns about regional and transboundary effects like acid rain led to shift in pollution control strategies.

Plant Operations

Operational changes like pre-treating process materials, fuel or material substitutions, and modifications to manufacturing processes can reduce pollutant emissions.
Coal washing is an example of pre-treatment to reduce particulate matter and sulfur emissions from coal.
Clean fuel substitution during refining (e.g., natural gas, low-sulfur fuel oil) is another pollution control measure.

Plant Maintenance

Plant maintenance plays a crucial role in reducing emissions from stationary sources.
Improperly maintained equipment, particularly combustion equipment, frequently leads to significant pollutant releases.
Scheduled maintenance for vats, valves, transmission lines helps reduce fugitive and exhaust emissions and prevent accidents.

Control Technology

Advanced control technologies involve devices to destroy or recover gaseous/particulate matter.
Controlling operations can include combustion, adsorption, absorption, and condensation.
Control devices include thermal incinerators, catalytic incinerators, flares, boilers, process heaters, carbon absorbers, spray towers, and surface condensers.
Selecting proper equipment depends on exhaust gas characteristics (flow rate, temp., efficiency, particle size & distribution), process, and site characteristics.

Exhaust Gas Characteristics

Exhaust gas flow rate, temperature, control efficiency, particle size, distribution, particle resistivity, emission composition, corrosiveness, moisture, stack pressure, and combustibility/flammability properties.

Process or Site Characteristics

Reuse/recycling of collected emissions, availability of space, electrical power, water, wastewater treatment facilities, frequency of start/stop, environmental conditions, control regulation changes, and raw material changes.

Control Devices for Particulate Emissions

Technologies for controlling particulate matter aim to remove particles from exhaust streams.
The choice for an appropriate device depends on various factors (e.g., particle size, composition).
- Devices used include: gravity settlers, mechanical collectors (cyclones), electrostatic precipitators (ESPs), scrubbers, fabric filters, and hybrid systems.
- Combining multiple devices often yields the best efficiency.

Equipment: Gravity Settlers/Chambers

Gravity settlers/chambers, used industrially, remove solid/liquid waste from gas streams.
Simple construction, low cost, maintenance, and waste disposal are their advantages

Equipment: Mechanical Collectors/Cyclones

Centrifugal separators, commonly known as cyclones, are employed in industry to remove solid/liquid particles from gas streams.

Equipment: Fabric Filters/Bag Houses

Filtration processes use various fabric filter types.
- Differences include fabric type, cleaning mechanism, and equipment
- Operation can be either push or pull through the bag house

Baghouse Filter

Efficiency is similar to a home vacuum cleaner (e.g., >99.5% for <1 µm particles).
Materials used for filters include natural fibers, synthetics, and fiberglass.
Cleaning methods include shaker, reverse air, and pulse jet.

Hybrid Systems

Hybrid systems combine various control mechanisms like fabric filtration and electrostatic precipitation.
- Examples currently used include: wet electrostatic precipitators, ionizing wet scrubbers, dry scrubbers, and electrostatically augmented fabric filtration.

Cyclones

Cyclones, economical devices, remove 50-100µm size particles, with simple designs and no moving parts; they rely on inertia.
Their effectiveness extends to particles as small as 10µm.

Electrostatic Precipitator (ESP)

High-efficiency, dry collectors for particulates.
High electrical direct current potential (30-75 kV) used to charge particles that are then collected on plates and removed.
Two common types: tubular, and plate.

Electrostatic precipitators (ESPs)

Satisfactory for removing small particles from moving gas streams, commonly used in power plants to remove fly ash.
Two types: tubular (cylindrical collection tubes) and plate (vast majority of installed).
Removal occurs primarily through rapping.

Wet Scrubbers

Used when air conditions are wet, corrosive, or hot.
- Baghouses cannot be applied under these conditions.
- Enhanced efficiency achieved in combination with a venturi scrubber and a cyclone.

Scrubbers (Venturi Scrubbers)

Wet scrubbing involves bringing contaminated gas streams into intimate contact with liquids (usually water).
This method is used to remove particulate matter from a carrier gas stream through gas absorption.

Comparison of Air Pollution Control Devices

A graph comparing removal efficiency against particle size for various devices (settling chambers, simple cyclones, high-efficiency cyclones, ESPs, spray tower wet scrubbers, venturi scrubbers, and bag filters).

Effectiveness of Air Pollution Control Devices

A diagram showing different control devices with their corresponding pollutant size ranges.

Gaseous Emissions Control

The preferred method for controlling gaseous pollutants is using add-on devices for pollutant destruction or recovery.
Control equipment includes thermal incinerators, catalytic incinerators, flares, boilers, process heaters, carbon absorbers, absorbers, and condensers.

Thermal Incinerator

Used for destroying volatile organic compounds (VOCs) and waste by controlled high-temperature burning.
High efficiency (up to 99.99%).

Catalytic Incinerator

Similar to thermal incinerators but use catalysts to increase oxidation reaction rates at lower temperatures, leading to lower operating costs and smaller system size.
Catalysts commonly used include platinum and palladium.

Flares

Used as a last resort for disposing of gases with low recyclable value, or not easily combustible.
Common in refineries, petroleum production facilities, and chemical plants to manage low MW VOCs

Boilers and Process Heaters

Typically used for heat production.
Useful in recycling pollutants with high heating values and sufficient amounts into combustion process (only for those that do not affect burner performance).

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Description

Test your knowledge on air pollution control methods and equipment. This quiz covers critical factors in selecting air pollution control devices, as well as the functions of various tools used to manage emissions. Answer questions on scrubbers, exhaust characteristics, and particulate emission collection.