United States Air Pollution Training Institute EPA 450/2-80-067
Environmental Protection MD20 April 1980
Agency Environmental Research Center i
Research Triangle Park NC 27711 C>'
Air
A D T I Do not remove. This document
F^ •II should be retained in the EPA
X"% f*» m^^^ /I1Q Region 5 Library Collection.
Control of Particulate
Emissions
Student Workbook
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United States
Environmental Protection
Agency
Air Pollution Training Institute
MD20
Environmental Research Center
Research Triangle Park NC 27711
EPA 450/2-80-067
April 1980
APTI
Course 413
Control of Particulate
Emissions
Student Workbook
Prepared By
O. Beachler
Northrop Services, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
Under Contract No.
68-02-2374
EPA Project Officer
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
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Notice
This is not an official policy and standards document. The opinions, findings, and
conclusions are those of the authors and not necessarily those of the Environmental
Protection Agency. Every attempt has been made to represent the present state of
the art as well as subject areas still under evaluation. Any mention of products or
organizations does not constitute endorsement by the United States Environmental
Protection Agency.
Availability of Copies of This Document
This document is issued by the Manpower and technical Information Branch. Con-
trol Programs Development Division. Office of Air Quality Planning and Standards.
USEPA. It was developed for use in training courses pirsemed by the EPA Aii Pollu-
tion Training Institute and others receiving contractual or grant support from the
Institute. Other organizations are welcome to use the document for training purposes.
Schools or governmental air pollution control agencies establishing training programs
may receive single copies of this document, free of charge, from the Air Pollution
Training Institute, USEPA. MD-20. Research Triangle Park. NC 27711. Others may
obtain copies, for a fee. from the National Technical Information Service. 5823 Port
Royal Road. Springfield. YA 22161.
•-" AcsauCf
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j**08H
1 AIR POLLUTION TRAINING INSTITUTE
" MANPOWER AND TECHNICAL INFORMATION BRANCH
CONTROL PROGRAMS DEVELOPMENT DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
The Air Pollution Training Institute (1) conducts training for personnel working on the develop-
ment and improvement of state, and local governmental, and EPA air pollution control programs,
as well as for personnel in industry and academic institutions; (2) provides consultation and other
training assistance to governmental agencies, educational institutions, industrial organizations, and
others engaged in air pollution training activities; and (3) promotes the development and improve-
ment of air pollution training programs in educational institutions and state, regional, and local
governmental air pollution control agencies. Much of the program is now conducted by an on-site
contractor, Northrop Services, Inc
One of the principal mechanisms utilized to meet the Institute's goals is the intensive short term
technical training course A full-time professional staff is responsible for the design, development,
and presentation of these courses In addition the services of scientists, engineers, and specialists
from other EPA programs governmental agencies, industries, and universities are used to augment
and reinforce the Institute staff in the development and presentation of technical material
Individual course objectives and desired learning outcomes are delineated to meet specific program
needs through training. Subject matter areas covered include air pollution source studies, atmos-
pheric dispersion, and air quality management These courses arc presented in the Institute's resi-
dent classrooms and laboratories and at various field locations
R. Alan Schueler /James A. Jahntie
Program Manager / Technical Director
Northrop Services, Inc. Northrop Services, Inc.
Jean jf Schueneman
Chief, Manpower & Technical
Information Branch
lit
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TABLE OF CONTENTS
1-1 Drag Coefficient and Settling Velocity 1
1 -2 Settling Velocity and Drag Force 2
2-1 Log-normal Distribution 3
2-2 Log-normal Distribution, Geometric Mean and Standard Deviation 4
2-3 Particle Size Distribution 5
3-1 Settling Chamber — Minimum Particle Size 8
3-2 Settling Chamber —Operating Efficiency 9
4-1 Cyclone — Overall Collection Efficiency Using Lapple's Method 10
4-2 Cyclone — Dimensions and Number of New Cyclones Required 11
4-3 Cyclone —Overall Collection Efficiency and Mass of Dust Collected 12
4-4 Cyclone Collection Efficiency 14
5-1 ESP Problem 17
5-2 ESP Problem 18
5-3 ESP Problem 19
5-4 ESP Problem 20
6-1 Fabric Filters —Number of Bag Calculations 21
6-2 Fabric Filters —Number of Bags and Pressure Drop 22
6-3 Fabric Filters —Number of Bags and Cleaning Frequency 23
6-4 Fabric Filters —Design of Filter Bag 24
7-1 Contact Power Theory Application 25
7-2 Contact Power Theory Application 26
7-3 Cut Power Rule 27
7-4 Johnstone Equation for Venturi Scrubbers 29
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1.1 Drag Coefficient and Settling Velocity
A spherical limestone particle is 400 /xm in diameter, specific gravity = 2.67.
Calculate the drag coefficient CD and the settling velocity vt in 70°F air.
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1.2 Settling Velocity and Drag Force
Particles 20 microns in diameter at 70 °F with a specific gravity of 1.8 flow in
a duct. The density of H2O is 62.4, the density of air is 0.075 Ik and the
viscosity of air is 1.23 X 10" 5Jb_ ft3
ft-sec.
(a) Calculate the settling velocity
(b) Calculate the Drag Force
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2.1 Log-normal Distribution
Let's say you have collected some data on particle mass concentration with an
optical particle counter or an Anderson Impactor. The following data was
collected.
dp range concentration
0.1-0.2 10
0.2-0.5 13.2
0.5-2 20
2-5 13.2
5-10 10
How can you tell if these data represent a log normal distribution or some
other distribution?
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2.2 Log-normal Distribution, Geometric Mean and Standard Deviation
Given the following particle size data:
Size range Mass concentration
dp n
<0.1 0.04
0.1- 0.2 0.76
0.2- 0.5 15.07
0.5- 2.0 68.26
2.0- 5.0 15.07
5.0-10.0 0.76
<10.0 0.04
Verify that this distribution is approximately log-normal, and find the
geometric mean and the geometric standard deviation.
Hint: determine the percentage mass larger than d max in each size range.
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2.3 Particle Size Distribution
Given the following distributions obtained from size differentiating
equipment:
Particle size Distribution A Distribution B
dp (microns) /tg/m3 ,ug/m3
<0.62 2575 875
0.62- 1.0 33.15 11.05
1.0 - 1.2 17.85 7.65
1.2 - 3.0 102.0 40.8
3.0 - 8.0 63.75 15.3
8.0 -10.0 5.1 1.692
<10.0 7.65 0.008
(a) Is either distribution A or distribution B log-normal
(b) If so, what is the geometric mean and standard deviation.
(Use the sheet of log probability paper provided if necessary.)
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3.1 Settling Chamber—Minimum Particle Size
A hydrochloric acid mist in air at 25°C is to be collected in a gravity settler.
The unit is 30 ft wide, 20 ft high, and 50 ft long. The actual volumetric flow
rate of the "acidic" gas is 50 ftVsec. Calculate the smallest mist droplet
(spherical in shape) that will be entirely collected by the settler. The specific
gravity of the acid is equal to 1.6. Assume the acid concentration to be
uniform through the inlet cross section of the unit.
Assume Stoke's Law applies and at 25°C /* = 0.0185 cp,
1 cp = 6.72xlO~4-^-
ft-sec
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3.2 Settling Chamber — Operating Efficiency
A gravity settler 5 meters wide, 10 meters long, and 2 meters high, is used to
trap particles with diameters of 10 /mi. The gas flow rate is 0.4 mVsec per
second. Calculate the operating efficiency of a settling chamber for the data
given below. Assume Stokes law regime and a Cunningham correction factor
of 1.0.
Qp= 1.10 gm/cm
e = 1.2xlO~3 gm/cm
cm — sec
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4.1 Cyclone—Overall Collection Efficiency Using Lapple's Method
The particle size distribution of a dust from a cement kiln is provided below:
Particle size (microns) % Wt
1
5
10
20
30
40
50
60
>60
3
20
15
20
16
10
6
The following information is also known:
Gas Viscosity
Particle Specific Gravity
Inlet Gas Velocity to Cyclone
Effective Number of Turns within Cyclone
Cyclone Diameter
Cyclone Inlet Width
0.02 centipoise (cp)
2.9
50 ft/sec
5
10 ft
2.5 ft
(a) Determine the cut size particle diameter, i.e., diameter of particle col-
lected at 50% efficiency, and estimate the overall collection efficiency
using Lapple's Method.
(b) If the same cyclone is used, but the inlet gas velocity is increased to 60
ft/sec and the gas viscosity changes to 0.018 cp (all else remaining the
same), find the new cut size particle diameter and determine the new
overall collection efficiency using Lapple's Method.
10
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4.2 Cyclone—Dimensions and Number of New Cyclones Required
A large-diameter conventional cyclone (no vanes) handles 5,000 acfm of a
particulate-laden gas exhaust stream (QG = 0.076 Ib/ft3) from a certain
metallurgical operation. The cyclone diameter if 4 ft. The remaining dimen-
sions may be found from Figure 4.2.1 (in the manual). In an attempt to
increase efficiency, a group of new cyclones is to be designed with the same
geometrical proportions and pressure drop as the single cyclone. If the
diameter of the small cyclone is to be 6 in., what will the dimensions of the
new group be? How many will be needed to handle the original flow rate at
the same pressure drop?
11
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4.3 Cyclone—Overall Collection Efficiency
(a) The size, mass, and cyclone collection efficiency data for a gas containing
limestone dust are given below. *"
Particle diameter, /*m Wt % Collection efficiency, %
0-5 2 4
5~10 8 6
10-20 13 20
20-30 26 32
30-50 12 78
50-75 11 89
75-100 9 95
100-200 8 98
200- 11 99 +
Calculate the overall collection efficiency of the unit.
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(b) If the inlet dust loading in the previous problem is 2.2 grains/ft3 and the
quantity of gas processed is 150,000 acfm, calculate the mass of
limestone collected daily.
13
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4.4 Cyclone Collection Efficiency
Determine loss and collection efficiency for a cyclone from the following
information.
(1) collection efficiency curve —figure 1
(2) size-efficiency curve —figure 2
(3) size distribution by weight
Particle size % by Wt
Micron Less than
10 .1
15 1.0
26 10.0
40 32.0
67 70.0
100 90.0
>100 100.0
(4) weight of inlet loading —50 Ib/hr.
14
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ESP Problem
An electrostatic precipitator consists of two parallel 10 ft high by 16 ft wide
plates with corona wires positioned half way between the plates. Find the
effective migration velocity at a flow rate of 35 acfs if the required collection
efficiency is 95%.
17
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5.2 ESP Problem
A horizontal-flow-single-stage electrostatic precipitator is used to remove par-
ticulates from a dry process gas stream of a Portland cement manufacturing
plant. The precipitator consists of multiple ducts formed by collecting plates
14 ft wide by 16 ft high and placed 9 inches apart. The rate of flow through
each duct is estimated to be 2400 acfm and the content of dust is 5
grains/ft3. Assume w = 0.19 ft/sec.
(a) Calculate the collection efficiency.
(b) Calculate the amount of dust collected by a duct each day.
18
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5.3 ESP Problem
An electrostatic precipitator has three ducts with plates 12 ft wide and 12 ft
high. The plates are 8 inches apart.
(a) Assuming a uniform distribution of particles and a drift velocity of
0.4 ft/sec, calculate the collection efficiency at a rate of flow of
4,000 acfm at 20°C and 1 atm.
(b) Calculate the efficiency if one duct were fed 50% of the gas and the
others 25% each.
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5.4 ESP Problem
A precipitator consists of two Stages each with five plates in a series (see figure
below). The corona wires between any two plates are independently controlled
so that the remainder of the unit can be operated in the event of a wire failure.
The following operating conditions exist:
Gas Flow Rate 10,000 acfm
Plate Dimensions 10 ftx 15 ft
Drift Velocity 19.0 ft/min Section 1
16.3 ft/min Section 2
Top view
Stage 1
Stage 2
(a) Determine the normal operating efficiency.
(b) During operation, a wire breaks in Stage 1. As a result, all of the wires in
that row are shorted and ineffective, but the others function normally.
Calculate the collection efficiency under these conditions.
(c) Similarly, a wire breaks in Stage 2 after Stage 1 is repaired. What is the
overall collection efficiency of the unit under these conditions?
20
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6.1 Fabric Filters—Number of Bag Calculation
Small scale tests showed that filtration of an air stream containing one grain
of particulates per cubic foot of air gave a maximum pressure drop of
5 inches of water at a flow rate of 3 ftVmin per square foot of filtering
surface.
(a) Calculate the horsepower required for a fan for a flow rate of
6,000 ftVmin. through the baghouse.
(b) Calculate the number of 0.5 ft diameter by 10 ft filtering bags required
for the system.
Assume an over-all fan-motor efficiency of 63%.
[flow rate cfm] X [Ap ins. H2O][1.575 X 10 ~4]
hp = — (Chemical Engr. Handbook)
efficiency (fan)
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6.2 Fabric Filters—Number of Bags and Pressure Drop
A plywood mill plans to install a fabric filter as an air cleaning device.
(a) How many bags, each 8 inches in diameter and 12 ft long, must be used
to treat the exhaust gas which has a paniculate loading of 2 grains/ft3
and the exhaust fan is rated at 7,000 ftVmin?
(b) If the pressure drop is given by the formula
Ap = Apclean fabric + Apdust cake
Estimate the pressure drop after four hours of operation if the resistance
coefficients of the filter and dust cake are, respectively. kt - 0.8 inches
water/ft min. and k2 = 3 inches water/(lb/dust/ft2 cloth area) (ft/min,
filtering velocity). Assume velocity is 2 ft/min.
22
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6.3 Fabric Filters—Number of Bags and Cleaning Frequency
A plant emits 50,000 acfm of gas with a dust loading of 5 grains ft3. The
dust is collected by a fabric filter at 98% efficiency when the average filtra-
tion velocity is 10 ft/min. The pressure drop is given by
Ap = 0.2v+5c;v2t
where:
Ap is the pressure drop in inches of water,
v is the filtration velocity in ft/min,
c; is the dust concentration in lb/ft3 of gas,
t is the time in minutes since bags were cleaned.
(a) How many cylindrical bags, 1 ft in diameter and 15 ft high will be
needed?
(b) The system is designed to begin cleaning when the pressure drop reaches
8 inches of water. How frequently should the bags be cleaned?
23
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6.4 Fabric Filters—Design of Filter Bag
It is proposed to install a pulse-jet fabric filter system to clean a 10,000 scfm
air stream at 250°F, containing 4 grains/ft3 of pollutant. For a 99% effi-
ciency, the average air-to-cloth ratio is 2.5 cfm ft2 cloth. The following in-
formation, given by filter bag manufacturers, is available at the beginning of
the selection process:
Filter bag A B CD
Tensile strength Excellent Above average Fair Excellent
Recommended
maximum operation
temperature, °F 260 275 260 220
Resistance factor 0.9 1.0 0.5 0.9
Relative cost
per bag 2.6 3.8 1.0 2.0
Standard size 8"xl6' 10"xl6' 1"X16' 1'X 20'
(a) Determine the filtering area required for this operation.
(b) Based on the required area and the above information, select the most
suitable filter bag and calculate the number of them that should be used.
The proposal of a pulsed jet device using strong forces to clean the bags
necessitates the selection of a fabric with at least above average tensile-
strength.
24
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7.1 Contact Power Theory Application
A vendor proposed to use a spray tower on a lime kiln operation to reduce
the discharge of solids to the atmosphere. The inlet loading of the gas stream
from the kiln is 5.0 grains/ft3 and is to be reduced to 0.05 in order to meet
state regulations. The vendor's design calls for a water pressure drop of 80 psi
and a pressure drop across the tower of 5.0 in. H2O. The gas flow rate is
10,000 acfm, and a water rate of 50 gal/min is proposed. Assume the con-
tact power theory to apply.
(1) Will the spray tower meet regulations?
(2) What total pressure loss is required to meet regulations?
(3) Propose a set of operating conditions that will meet the standard. The
maximum gas and water pressure drop across the unit are 15 in. H2O and
100 psi, respectively.
(4) What conclusions can be drawn concerning the use of a spray tower for
this application.
25
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7.2 Contact Power Theory Application
The installation of a venturi scrubber is proposed to reduce the discharge of
particulates from an open-hearth steel furnace operation. Preliminary design
information suggests a water and gas pressure drop across the scrubber of
5.0 psi and 36 in. H2O, respectively. A liquid-to-gas ratio of 6.0
gal/min/1,000 acfm is usually employed in this application. Estimate the
collection efficiency of the proposed venturi scrubber. Assume contact power
theory to apply.
26
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7.3 Cut Power Rule
What would be the pressure drop required on a venturi scrubber to achieve
an overall collection efficiency of 99.3% for paniculate matter having a mass-
median aerodynamic diameter of 5^m with particle size deviation, a , of 2.0 /
27
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7.4 Equation for Venturi Scrubbers
A fly ash laden gas stream is to be cleaned by a venturi scrubber using a
liquid-to-gas ratio of 8.5 gal/1000 ft3. The efficiency can be calculated from
Where f]-l is the fractional efficiency of collection of particles of size dpi. The
fly ash has a particle density of 0.7 gm/cm3, and k = 200 ftVgal.
Use a throat velocity of 272 ft/sec, a liquid-to-gas ratio of 8.5 gal/1000 ft3,
and a gas viscosity of 1.5 X 10 ~5 Ib/ft sec. The particle size distribution is:
dpi (microns) % by Weight
<= 0.10 0.01
0.1 0.5 0.21
0.6 1.0 0.78
1.1 5.0 13.0
6.0-10.0 16.0
11.0-15.0 12.0
16.0-20.0 8.0
> 20.0 50.0
Make use of the Nukiyama and Tanasawasa relationship.
29
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before computing)
! - - * • i o i-T
RECIPIENT'S ACCESSIOJ*NO
4. TITLE AND SUBTITLE
APTI Course 413
Control of Participate Emissions
Student Workbook
7 AUTHOR(S)
D. S. Beachler
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Northrop Services, Inc.
P. 0. Box 12313
Research Triangle Park, NC 27709
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Manpower & Technical Information Branch
Research Triangle Park, NC 27711
15. SUPPLEMENTARY NOTES
. REPORT DATE
April 1980
6. PERFORMING ORGANIZATION CODE
PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
B18A2C
11. CONTRACT/GRANT NO.
68-02-2374
13 TYPE OF REPORT AND PERIOD COVERED
Student Workbook
14. SPONSORING AGENCY CODE
EPA Project Officer for this workbook is R. E. Townsend, EPA-ERC, MD-17, RTP, NC 2771
16. ABSTRACT
. ABŁp I M«U I if /IT?
This workbook contains problems for the Air Pollution Training Institute s Course 413
"Control of Particulate Emissions". The problems cover calculation of collection
efficiencies pressure drop values, and particle size distributions for such
emTss on co ntrSl devices as settling chambers, cyclones, electrostatic P'ecipitators,
Smhnisps and wet collectors. The workbook, when used with the Student Manual,
E?A 450/2180 066!du?ing the lecture sessions, is part of comprehensive training in
particulate control.
The course also has an Instructor's Guide, EPA 450/2-80-068, which should be used
in conducting the course.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Personnel training
Air pollution control
Dust collectors
DISTRIBUTION STATEMENT
Unlimited
I.IDENTIFIERS/OPEN ENDED TERMS
Training Exercises
19. SECURITY CLASS (ThisReport)
Unclassified
20. SECURITY CLASS (This page)
Unclassified
COSATI Field/Group
13B
51
68A
21. NO. OF PAGES
34
22. PRICE
EPA Form 2220-1 (9-7»)
30
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