EPA/450/2-81/017e
U.S. Environmental Protection Agency
Air Pollution Training Institute
COURSE 81:422
3rd Edition
AIR POLLUTION CONTROL
ORIENTATION COURSE
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Unit 5
Control Techniques for Gaseous and Particulate Pollutants
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United States Air Pollution Training Institute EPA 450/2-81-017e
Environmental Protection MD 20 June 1981
Agency Environmental Research Center
Research Triangle Park NC 27711
Air
APTI
Course S 1:422 3rd Edition
Air Pollution Control
Orientation Course
Units
Control Techniques for Gaseous
and Paniculate Pollutants
Prepared By: Under Contract No.
Northrop Services, Inc. 68-02-2374
P. 0. Box 12313 EPA Project Officer
Research Triangle Park, NC 27709 R. E. Townsend
United States Environmental Protection Agency
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
******
This is one of nine self-instructional units in the
Air Pollution Control Orientation Course SI:422.
This unit consists of a cassette tape and this flip-
book, which you will use simultaneously.
Turn the page and read the tips on effective use
of this material.
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Tips for Effective Use *>f This Material
1. Listen to the recorded script while you go through this flipbook. The recorded
portion is coordinated with the flipbook. Wait for the tape to finish the details
of one point before studying the next point on the page.
2. When you hear a "beep" on the tape, direct your attention to the next page in
the flipbook.
3. Pay attention to both words and pictures they both convey important informa-
tion. The flipbook will usually summarize main points or give examples.
4. Stop the tape at any point if you wish to spend more time reading a page in the
flipbook. Rewind the tape if you wish to review a portion of the script.
5. Review the lesson objectives before answering the questions at the end of each
lesson. Ask yourself whether you have mastered the information indicated in the
objectives.
6. Answer the questions. They will help you assess your progress in mastering the
course materials.
7. Check your answers. The correct responses can be found on the page(s) fol-
lowing the questions.
8. If you answer a question incorrectly, review the flipbook material covering the
subject matter. Now Turn On the Tape Recorder and Begin Lesson I.
11
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Lesson I: Control Techniques Not Requiring
Control Devices
Objectives
1. Name the two physical forms of air pollutants.
2. Identify four techniques for reducing pollutant emissions that do not require
the use of emission control devices.
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Two Forms of Air Pollutants
Gaseous
Particulate
Primary Gaseous Pollutants
sulfur oxides odors
acid gases carbon monoxide
nitrogen oxides hydrocarbons
Common Particulate Pollutants
cement dust metal fumes
smoke fly ash
acid mists
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Emission Reduction Techniques
Not Using Emission Control Devices
Process change
Change in fuel
Good Operating practices
good housekeeping
maintenance
Plant shutdown
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Process Change
Fossil-fuel fired,
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Change in Fuel
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Good Operating Practices
Bad
Good
ri^?,v%
&
Bad
Good
Good Housekeeping Maintenance
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Plant Shutdown
8
National Emission Estimates
1970-1977
(Millions of metric tons/year)
Year
1970
1971
1972
1973
1974
1975
1976
1977
TSP(a)
22.2
20.9
19.6
19.2
17.0
13.7
13.2
12.4
S0x(a)
29.8
28.3
29.6
30.2
28.4
26.1
27.2
27.4
N0x(a)
19.6
20.2
21.6
22.3
21.7
21.0
22.8
23.1
VOC(b)
29.5
29.1
29.6
29.7
28.6
26.9
28.7
28.3
CO
102.2
102.5
103.8
103.5
99.7
96.9
102.9
102.7
(a) FSF Total Suspended Paniculate matter in the case ot emissions, just paniculate
mailer
SO\ Sulfur Oxides
NOx - Oxides of Nitrogen
(b) V'OC - Volatile Organic Compounds hydrocarbons etc.
9
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':
Gray or black emissions
from smoke stacks are
easily seen by everyone
but no one sees the
gaseous emissions.
10
Lesson I
Questions
1. Name the two forms of air pollutants.
2. Four of the following are methods of pollutant reduction that do not require
the use of emission control devices. Which one is not?
a. tall chimneys d. change in fuel
b. plant shutdown e. process change
c. good operating practices
Answers on next page.
11
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Lesson I
Answers
1. gaseous, paniculate
2. a. tall chimneys
After checking your responses, please turn on the tape recorder.
12
Lesson II: Control Techniques for Gaseous
Emissions
Objectives
1. Name the four main techniques used in devices that control gaseous emissions.
2. Identify the definition of each of the following terms: absorption, adsorption,
condensation, and combustion.
3. Given a diagram of a control device (as it appears in this flipbook), name the
control device and tell whether it is of the adsorption, absorption, condensa-
tion, or combustion type.
4. Identify the factors that must be considered when choosing a device for the
control of gaseous emissions.
13
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Control Techniques for
Gaseous Emissions
Adsorption
Absorption
Condensation
Combustion
14
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Adsorption
The removal of a gaseous pollu-
tant from a gas stream by allow
ing the pollutant molecules in
the gas stream to become
attached to a solid surface.
15
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Adsorption Design Factors
Nature of the contaminant
Surface area of adsorbent
Temperature and pressure
Nature of adsorbent
16
How do we dispose of adsorbents?
Dispose of both the
pollutant and the
adsorbent together
17
Remove the
pollutant from the
solid surface and
re-use adsorbent bed
(regeneration)
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Adsorption Systems
Nonregenerative
Have thin beds
Commonly used where
there are low concen-
trations of pollutants
in a gas stream
Regenerative
Have thick beds
Used for solvent or
hydrocarbon recovery
Regenerative System
Clean gas out
A
Dirty
gas in
Steam for
regeneration
18
Pollutant and steam out
Dirty gas in
Water out
r< Water in
Particulate
filter
Clean gases
X
Cooling coil
(if required)
Blower
Unit #1-
Removing
pollutants
Activated
carbon
Regenerative
System
Unit #2-
Being
regenerated
Activated
carbon
Collected
pollutant
Clean air out
Low pressure steam
for regeneration
1 Q
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Absorption
The dissolving of a gaseous
pollutant in a liquid solvent
20
Factors Affecting Absorption
Type of pollutant
Type of solvent
Temperature of system
Pressure on system
21
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With absorption equipment we
try to get as much gas-liquid
mixing as possible.
22
Absorption Equipment
Spray tower
Spray-chamber
Venturi scrubber
Packed column
23
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nr Clean gas out
Packed
Column
Liquid in
Packing material
Dirty gas in
Liquid and pollutant out
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Condensation occurs when:
Pressure increased
Heat extracted from a system
(the most economical method
is temperature reduction)
25
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Condensers are usually used
in conjunction with:
afterburners
absorbers
adsorption units
26
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Surface Condenser
(Temperature Reduction)
Cooling
medium
Clean gas out
in
Cooling
medium V
Condensate out
out
27
NJ
Cooling medium: water or air
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Clean gas out
Contact
Condenser
(Temperature
Reduction)
Dirty
gas in
Water
in
28
Water and condensate out
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Combustion
The result of the combination of
oxygen with a combustible
material, usually accompanied
by heat and light
29
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Combustion is commonly used
as a control technique for
hydrocarbon emissions.
30
Combustion Equipment
Flare
Thermal incinerator
Catalytic incinerator
31
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Flare
32
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Thermal Incinerator
(Afterburner)
Dirty
gas
Fuel
and
air
Dirty
gas
Ave. temp:
1400-1500 °F
I
Clean
out
33
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Catalytic Incinerator
Fuel
Air
Dirty
gas
Preheat
burner
Catalyst
600-900DF
800-1100°F
Clean
out
34
Choice of Control Technique
Some questions to consider:
1. Will the pollutant burn?
2. Is the product of combustion a pollutant?
3. Is the pollutant soluble in water or another solvent?
4. Can the pollutant be easily condensed?
5. Is carbon adsorption applicable?
6. What is the age of the plant?
7. Is re-use of pollutant desirable?
8. What is the impact of control cost on selling price of the product?
9. What are equipment costs?
10. What are utility requirements?
35
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Lesson II
Questions
1. Name the four main techniques used in devices that control gaseous emissions.
2. The phrase, "the removal of a gaseous pollutant from a gas stream by allowing
the pollutant molecules to become attached to a solid surface" defines which of
the following terms?
a. condensation d. adsorption
b. absorption e. evaporation
c. combustion f. none of the above
36
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Clean gas out
3. The diagram at the right
depicts which of the following "
type of control device?
a. adsorption
b. absorption
c. combustion
Liquid in
Packing material
Dirty gas in
Liquid and condensate out
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4. The device depicted in question No. 3 is a:
a. flare. d. regeneration adsorber.
b. surface condenser. e. contact condenser.
c. catalytic incinerator. f. packed column.
38
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5. Which of the following is not a factor to consider when choosing a device for
the control of gaseous emissions?
a. color of the pollutant d. age of the plant
b. equipment costs e. whether or not the pollutant
c. whether or not the pollutant can be reused
will burn f. solubility of the pollutant
Answers on next page.
39
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Lesson II
Answers
1. adsorption, absorption, condensation, and combustion
2. d. adsorption
3. b. absorption
4. f. packed column
5. a. color of the pollutant
After checking your responses, please turn on the tape recorder.
40
Lesson III: Control Techniques for
Particulate Emissions
Objectives
1. Name the 4 types of paniculate matter.
2. Categorize each of the 4 types of paniculate matter as either solid or liquid.
3. Identify the factors that must be considered before choosing a paniculate con-
trol device.
4. Name the 5 main types of paniculate control devices.
5. Given a diagram or picture of a control device (as it appears in this flipbook),
name the control device.
6. Describe, briefly, the ideal solution to the problem of collected paniculate
matter disposal.
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42
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Common Terms Used to Describe
Particulate Matter
Solid
Dust
Smoke
Fumes
Liquid
Mist
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Information Needed About Gases and Particles
Particle size
Gas flow rate
Temperature
Moisture content
Type and concentration of particles in gas stream
Significant characteristics of particles abrasive,
explosive, flammable, acidic, etc.
Degree of Control Desired (i.e. efficiency)
weight of particles enteringweight of particles leaving
Efficiency
total weight entering control equipment
44
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Particulate Control Devices
Settling chamber
Cyclone
Wet collector (scrubber)
Electrostatic precipitator
Fabric filter (baghouse)
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Settling Chamber
Dirty gas in
Clean gas out
Collection force: gravity
Collection efficiency: low
Initial cost: inexpensive
Operating cost: low
Dust hoppers
46
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Outlet
tube
Dirty
gas in
Cone
Dust
hopper
Clean
gas out
Cyclone
Cylinder
Collection efficiency: low to medium
Initial cost: inexpensive
Operating cost: low
Collected
dust out
4-7
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Several small
cyclones are used
together to increase
collection efficiency.
48
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Clean gas out
Dirty
gas in
gas out
Outlet tube
Spin vanes
Multiple Cyclone
t
Collector Element
Collected
dust out
49
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Wet
Collector
(Scrubber)
Spray
C
ollection efficiency: medium to high
Initial cost: moderate
Operating cost: high
Clean gas out
Water and condensate out
50
High
voltage
Electrostatic Precipitator
to plates (Plate Type)
to wires
Dirty
gas in
Discharge
electrode (wire)
gas ,n ,'^
'*
Collection efficiency: medium to high
Initial cost: high
Operating cost: moderate to high
Weights
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Electrostatic Precipitator
(Tube Type)
Dirty
gas in
Clean
gas out
Dirty
gas in
52
Clean
gas out;
mf|||F
Spray
Discharge
electrode
(wire)
Weights
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Mechanism for shaking,
rapping, or vibrating bags
Clean
air out
Dirty
air in
Fabric Filter
(Baghouse)
Collection efficiency: high
Initial cost: high
Operating cost: high
Clean
air
out
air in
53
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Particulate control systems often
require two or more control devices to
obtain the highest possible efficiency.
For example,
Cyclone
to collect large
particles
Electrostatic
Precipitator
to collect
remaining
small particles
54
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Disposal of Collected Material
Most dry particulate material
will be disposed of in land-fills
or dumps.
Water slurries go to basins or
sewers or treatment plants.
The ideal solution is to recycle the collected material.
55
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Lesson III
Questions
1. Name at least four common kinds of paniculate matter.
2. Which of the following is (are) liquid particle(s)?
a. dust c. fumes
b. mist d. smoke
3. Which of the following should be considered before choosing a particulate
control device?
a. moisture content of stack gas d. type & concentration of
b. gas flow rate particles
c. characteristics of particles e. temperature
f. all of the above
56
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4. Name the five main types of particulate control devices.
5. The control device depicted at the right is a(n)-.
a. settling chamber.
b. cyclone.
c. wet collector.
d. electrostatic precipitator.
e. fabric filter.
f. none of the above.
6. Describe briefly the ideal solution to the problem of
collected particulate matter disposal.
Spra
Water and condensate out
Answers on next page.
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Lesson III
Answers
1. dust, smoke, fumes, mist
2. b. mist
3. f. all of the above
4. settling chamber
cyclone
wet collector (or scrubber)
electrostatic precipitator
fabric filter (or baghouse)
5. c. wet collector (or scrubber)
6. The recycling of the collected material
After checking your responses, review any material that you are not sure of, and
then take the Unit Test which begins on the next page.
58
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Unit Test
The two physical forms of air pollutants are:
a. liquid and paniculate. d. gaseous and vaporous.
b. liquid and gaseous. e. none of the above.
c. gaseous and paniculate.
Which of the following is not a method for reducing pollutant emissions?
a. tall chimneys d. process change
b. plant shutdown e. good operating practices
c. change in fuel
-o
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3. Which of the following is not a technique used in devices that control gaseous
emissions?
a. adsorption d. combustion
b. condensation e. electrostatic precipitation
c. absorption
4. The phrase "the dissolving of a gaseous pollutant in a liquid solvent" defines
which of the following terms?
a. adsorption d. combustion
b. absorption e. none of the above
c. condensation
60
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The diagram at the right depicts
which of the following types of
control device?
a. adsorption
absorption
combustion
condensation
electrostatic precipitation
b.
c.
d.
e.
Clean gas out
A
Regenerative System
Dirty
gas in
Pollutant and steam
Steam for
regeneration
61
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6. Which of the following must be considered when choosing a device for the
control of gaseous emissions?
a. equipment costs d. whether or not the pollutant
b. whether or not the pollutant can be reused
will burn e. solubility of the pollutant
c. age of the plant
7. Which of the following is not a common kind of paniculate matter?
a. mist d. vapor
b. dust e. fumes
c. smoke
8. Which of the following should be considered before choosing a device to
control paniculate pollutants?
a. moisture content of stack gas d. type and concentration of
b. gas flow rate particles
c. characteristics of particles e. temperature
f. all of the above
62
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9. The control device depicted at the right is a(n):
a. settling chamber.
b. cyclone.
c. wet collector. Dirty gas in
d. electrostatic precipitator. r-..:. A;
e. fabric filter.
A A Clean gas out
Outlet tube
Spin vanes
t Collected
dust out
Collector Element
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10. Describe briefly the ideal solution to the problem of collected particulate
matter disposal.
Answers on next page.
64
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Answers
1. c. gaseous and particulate
2. a. tall chimneys
3. e. electrostatic precipitation
4. b. absorption
5. a. adsorption
6. a-e. equipment costs, whether or not the pollutant will burn, age of the plant,
whether or not the pollutant can be reused, and solubility of the
pollutant.
7. d. vapor
8. f. all of the above
9. b. cyclone
10. The recycling of the collected material.
65
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