Particulate%20Matter

1
Particulate Matter and its Removal
2
Particulate Matter Overview

• Can be solid or liquid particles
• Usually defined in terms of PM10 and PM2.5
  where the subscript refers to the diameter of
  the particle in microns ? 10 or 2.5
• Reduces visibility in the atmosphere
• Causes health problems related to the
  respiratory system and circulatory system

3
Relative sizes of particles in air
4
Relative sizes of particles in air
PM10
PM2.5
5
Particulate Matter Standards

• High-volume samplers measured PM by Total
  Suspended Particulate Matter (TSP). TSP usually
  less than 25-50 µg/m3. Concentrations measured
  usually around 260 µg/m3 .
• Based on research in the 1960s and 1970s, the
  human respiratory system was found to be affected
  by PM that was finer than what high-volume
  samplers measured.
• A new standard based on PM10 was established
  using a 24-hour concentration of 150 µg/m3.

6
Particulate Matter Standards EPA in 1997 as
amended 2006
The EPA set a new stricter standard that
regulated fine particulate matter (PM2.5) in
1997 65 µg/m3 measured over a 24-hour period and
15 µg/m3 averaged over a year. The EPA announced
in 2006 that it revised the level of the 24-hour
PM-2.5 standard to 35 micrograms per cubic meter
(µg/m3) and retained the level of the annual
PM-2.5 standard at 15 µg/m3. The EPA announced
the designations for nonattainment for the PM-2.5
2006 Standard, October 8, 2009. The current
number of areas that violate the PM-2.5 2006
Standard is 31 and the number of counties that
violate is currently 120. A map of the EPA's
PM2.5 designations for nonattainment can be
reviewed by clicking here.
7
Non-attainment areas PM 2.5 Yesterday
http//www.airnow.gov/
8
Key to air quality levels


Air Quality IndexLevels of Health Concern NumericalValue Meaning
Good 0 to 50 Air quality is considered satisfactory, and air pollution poses little or no risk
Moderate 51 to 100 Air quality is acceptable however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups 101 to 150 Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy 151 to 200 Everyone may begin to experience health effects members of sensitive groups may experience more serious health effects.
Very Unhealthy 201 to 300 Health alert everyone may experience more serious health effects
Hazardous 301 to 500 Health warnings of emergency conditions. The entire population is more likely to be affected.
9
Non-attainment areas PM 2.5 Today
10
Polk County Health Department Polk County Air
Quality
Takes PM readings every 24 hours
Weighted annual mean PM 2.5 10
µg/m3 (http//www.city-data.com/city/Des-Moines-Io
wa.html) Link
http//www.airnow.gov/index.cfm?actionairnow.show
mappollutantPM2.5
11
PM 2.5 in Iowa yesterday
12
PM 2.5 in Iowa last year
13
Sources of PM

• motor vehicles
• wood burning stoves and fireplaces
• dust from construction, landfills, and
  agriculture, mining
• wildfires and brush/waste burning
• industrial sources
• windblown dust from open lands

14
Health Effects

• Aggravates conditions such as asthma,
  bronchitis, emphysema
• Can trigger asthma attacks
• Makes it difficult to breathe
• Can cause premature death in elderly people or
  people with heart disease and respiratory
  diseases
• Can cause future health problems in children
  (such as asthma, increased illness)

15
Effects on Visibility

• Most haze is not natural, it is caused by air
  pollution
• Air pollution, especially particulate matter,
  scatters and absorbs light
• Sulfates particles are very effective in
  scattering light, especially in humid conditions

16
Denver, CO, (top) and Great Smokey Mountains
National Park (bottom) in good visibility
and bad visibility
17
Cleaning up Particulate Matter Control
Equipment

• Gravity and Inertial Separators
• Mechanical Collectors (Cyclones)
• Scrubbers
• Electrostatic Precipitators
• Fabric Filters

18
Type 1
19
(No Transcript)
20
Archimedess Principle
Archimedess Principle
Examination of the nature of buoyancy shows that
the buoyant force on a volume of water and a
submerged object of the same volume is the same.
Since it exactly supports the volume of water, it
follows that the buoyant force on any submerged
object is equal to the weight of the water
displaced. This is the essence of Archimedes
principle.
21
Analysis of Forces Acting On a Settling
Particle
Determining the terminal settling velocity of a
particle
22
Terminal Velocity of a Particle
Expressing the terminal settling velocity of a
particle
An expression for Vs from the submerged weight of
the particle, W, and the fluid drag force,
D   The drag force on a particle is given by
  D CD?g Ap Vt2/2   The suspended weight
of the particle can be expressed as   W (?
- ?g)g ?s   Since D W, the above, after
substituting Ap and ?p for particle diameter d
 
_______________ Vt / 4 (? - ?g) gd
? 3?l CD
23
Stokess Law
Re lt 1, CD 24 /Re Vs g (? -?g)
d2 18 ? Vs g ? d2
18 ?
24
Pathways of particles around media particles
25
B
A
C
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
Type 2 Mechanical Collectors Cyclones

• Specific types include
• Involute cyclone separator
• Vane-axial centrifugal separator
• Large-diameter cyclones
• Small-diameter multi-cyclones

36
Mechanical Collectors Cyclones
Advantages Good for larger PM Disadvantages
Poor efficiency for finer PM Difficult removing
sticky or wet PM
37
Cyclones - A Large-Diameter Involute Cyclone
Separator
38
Involute Inlets
39
Cyclones - A small-diameter vane- axial
centrifugal separator
40
(No Transcript)
41
Type 3 Scrubbers

• Specific types include
• Venturis
• Impingement and Sieve Plates
• Spray Towers
• Mechanically Aided
• Condensation Growth
• Packed Beds

• Ejector
• Mobile Bed
• Catenary Grid
• Froth Tower
• Oriented Fiber Pad
• Wetted Mist Eliminators

42
Scrubbers
Advantages Good efficiency, can collect
(potentially explosive) gaseous pollutants as
well as PM, small size Disadvantages Requires a
lot of water, generates waste stream
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
Venturi Scrubbers
48
Type 4 Electrostatic Precipitators

• Types include
• Dry, negatively charged
• Wet-walled, negatively charged
• Two-stage, positively charged

49
Electrostatic Precipitators
Advantages Good efficiency Disadvantages
Dependent upon resistivity of PM, cannot be used
around explosive gases
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
Wet Electrostatic Precipitators
54
Electrostatic Plates
List of suppliers of equipment http//www.eco-web.
com/cgi-local/sfc?aindex/index.htmlbindex/categ
ory/4.4.html
55
(No Transcript)
56
(No Transcript)
57
Type 5 Fabric Filters / Baghouses

• Types include
• Reverse air-type
• Pulse jet

58
Fabric Filters / Baghouses
Advantages Good efficiency for various sizes of
particles Disadvantages Not to be used around
corrosive substances, explosive gases, or sticky
and wet particles
59
(No Transcript)
60
(No Transcript)
61
(No Transcript)
62
(No Transcript)
63
(No Transcript)
64
(No Transcript)
65
(No Transcript)
66
(No Transcript)
67
(No Transcript)
68
Technology - Media Cross Section



69
Growth of Fungi On Inside of Filter
Material Here Aspergillus sp.
70
(No Transcript)
71
(No Transcript)
72
Sources

1. EPA
2. American Lung Association
3. Polk County Health Department

73
Assignment Particulates
Do Problems at the end of Chapter 5 5-3, 5-5,
5-23, 5-53 Hand in by Thursday, February 10,
2010