U.S. Environmental Protection Agency Industrial Environmental Research
Office of Research and Development Laboratory
Research Triangle Park, North Carolina 27711
EPA-600/7-77-140
December 1977
PARTICULATE CONTROL WITH
CLEANABLE CARTRIDGE FILTERS
USING DOUBLE-LAYER MEDIA
Interagency
Energy-Environment
Research and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S.
Environmental Protection Agency, have been grouped into seven series.
These seven broad categories were established to facilitate further
development and application of environmental technology. Elimination
of traditional grouping was consciously planned to foster technology
transfer and a maximum interface in related fields. The seven series
are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from
the effort funded under the 17-agehcy Federal Energy/Environment
Research and Development Program. These studies relate to EPA's
mission to protect the public health and welfare from adverse effects
of pollutants associated with energy systems. The goal of the Program
is to assure the rapid development of domestic energy supplies in an
environmentally—compatible manner by providing the necessary
environmental data and control technology. Investigations include
analyses of the transport of energy-related pollutants and their health
and ecological effects; assessments of, and development of, control
technologies for energy systems; and integrated assessments of a wide
range of energy-related environmental issues.
REVIEW NOTICE
This report has been reviewed by the participating Federal
Agencies, and approved for publication. Approval does not
signify that the contents necessarily reflect the views and
policies of the Government, nor does mention of trade names
or commercial products constitute endorsement or recommen-
dation for use.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
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EPA-600/7-77-140
December 1977
PARTICULATE CONTROL WITH
CLEANABLE CARTRIDGE FILTERS
USING DOUBLE-LAYER MEDIA
by
William J. Krisko and Michael A. Shackleton
Donaldson Company, Inc.
P.O. Box 1299
Minneapolis, Minnesota 55440
Contract No. 68-02-1878
ROAP No. 77AAU-006
Program Element No. EHB525
EPA Project Officer Dennis C. Drehmel
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, N.C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
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Disclaimer Statement
This report has been reviewed by Donaldson Company,
Inc., the Environmental Protection Agency, and
approved for publication. Approval does not signify
that the contents necessarily reflect the views and
policies of the Environmental Protection Agency,
nor does mention of trade names or commercial
products constitute endorsement or recommendation
for use.
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PREFACE
This report presents results of a study to assess the feasibility of a new concept in
fine particle filtration termed Nonwoven Double Mat Filters. The double mat
filter consists of a fine fiber filtration layer supported by a porous substrate pro-
viding physical strength to the resulting double mat filtration medium. A theoretical
basis for fine particle control with this medium is presented. Test results with
0.3 n m DOP smoke confirmed that the design objective of 90 percent collection
efficiency could be obtained. Pressure drop characteristics during pulse-jet
cleaning of AC Fine test dust, from flat-sheets, was similar to that of felt bag-
house media; while collection efficiency was approximately 99.5 percent for felts,
the double mat filter medium achieved a collection efficiency of >99.999 percent
for AC Fine. Preliminary economic analysis indicates that the double mat media
in a cartridge configuration will provide a less costly filtration system than the
standard bag house. This saving is a result of the system size reduction possible
with the pleated cartridge and the potentially higher air-to-cloth ratios with the
fine fiber media. These analyses were conducted under Phase I of this contract.
Phase II evaluated the fine particle control characteristics of double mat filtration
media in a pulse-jet cleaning cartridge filter configuration. Both laboratory and
field tests proved the media to be capable of high dust removal efficiency of fine
particles (<3/im) while achieving good pulse-jet cleaning characteristics.
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TABLE OF CONTENTS
PREFACE i
LIST OF FIGURES Hi
LIST OF TABLES vii
LIST OF ABBREVIATIONS AND SYMBOLS ?x
ACKNOWLEDGMENTS x
Sections
1.0 INTRODUCTION 1
2.0 CONCLUSIONS 3
3.0 RECOMMENDATIONS 7
4.0 THEORETICAL ANALYSIS 9
5.0 PRELIMINARY EXPERIMENTS 23
5.1 OOP Penetration Tests 23
5.2 SEM Analysis 41
5.3 Dust Loading Tests 56
5.4 Pressure Drop Tests 90
6.0 PLEATED CARTRIDGE LABORATORY TESTS 95
6.1 Pleated Cartridge Dust Tests 95
6.2 DOP Penetration Tests 103
7.0 FIELD TESTS 109
7.1 Tests at Cornelius Company 110
7.1.1 Particulate Characterization 110
7.1.2 Performance Tests 125
7.2 Tests at Northern Malleable Iron Company 132
7.2.1 Particulate Characterization 136
7.2.2 Performance Tests 141
8.0 ECONOMIC ANALYSIS 147
8.1 Dust Control from a Vertical Lime Rock Kiln 147
8.2 Particulate Removal from the Exhaust Gas of a Glass-Melting 165
Furnace
8.3 Conclusion 165
9.0 GLOSSARY 183
1 0.0 REFERENCES 185
1 1.0 CONVERSION FACTORS 187
TECHNICAL REPORT DATA 189
ii
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LIST OF FIGURES
Figure Poge
4-1 Filter Efficiency as a Function of Basis Weight 10
4-2 G(M) Versus "M" for Torgeson Theory 15
4-3 Basis Weight as Function of Fiber Diameter 18
4-4 Pressure Drop as a Function of Fiber Diameter 20
5-1 DOP Penetration as a Function of Basis Weight 25
5-2 Penetration Tests of Various Media 27
5-3 Penetration as a Function of Basis Weight 31
5-4 Penetration as a Function of Airflow Velocity 32
5-5 Efficiency of Media Samples 34
5-6 Effect of Needle Holes on Efficiency 36
5-7 Penetration as a Function of Basis Weight 39
5-8 Efficiency as a Function of Airflow Velocity 40
5-9 SEM Photomicrograph of Fine Fibers (8/26/75) 42
5-10 Measurement Technique Used to Estimate Average Fiber Diameter 43
5-11 Downstream Side of Media (9/18/75) 45
5-12 Upstream Side of Media (9/18/75) 45
5-13 S EM Photom icrograph of Fiber Bed (l /16/76) 46
5-14 SEM Photom icrograph of Fiber Bed (2/26/76) 47
5-15 SEM Photomicrograph of Gore-Tex Filter Material 49
5-16 5K Photom icrograph of Media Sample (4/10/76) 50
5-17 5K Photom icrograph of Media Sam pie (5/14/76) 50
5-18 5K Photomicrograph of Media Sample (5/17/76) 51
5-19 IK Photomicrograph of Media Sample (4/10/76) 51
5-20 IK Photomicrograph of Media Sample (5/14/76) 52
5-21 2K Photomicrograph of Media Sample (5/17/76) 52
5-22 200X Photomicrograph of Media Sample (4/10/76) 53
5-23 200X Photom icrograph of Media Sample (5/17/76) 53
5-24 200X Photomicrograph of Media Sample Backing 54
5-25 400X Edge View of Media Sample (5/17/76) 55
5-26 5K Photomicrograph of Media Sample (5/17/76) 55
5-27 Flat Sheet Pulse Jet Test Rig 57
5-28 Flat Sheet Pulse Jet Cleaning Test Rig 58
iii
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LIST OF FIGURES (continued)
Figure Page
5-29 Particle Size Distribution of AC Fine Test Dust 59
5-30 Media Cleanability Evaluation 71
5-31 Pressure Drop as a Function of Time (Test #16) 72
5-32 Operating Pressure Drop as a Function of Time (Test #18) 77
5-33 Operating Pressure Drop as a Function of Time (Test #23) 79
5-34 Operating Pressure Drop as a Function of Time (Test #24) 81
5-35 Operating Pressure Drop as a Function of Time (Test #25) 83
5-36 Operating Pressure Drop as a Function of Time (Test #26) 85
5-37 Operating Pressure Drop as a Function of Time (lest #27) 86
5-38 Operating Pressure Drop as a Function of Time (Test #28) 88
5-39 Fine Fiber Layer Broken from Felt Backing 89
5-40 Pressure Drop as a Function of Time (Test #29) 91
5-41 Difference Between Actual and Predicted Pressure Drop for
Filters Capable of 90% Collection of 0.3a m DOP 92
6-1 Pressure Drop Life Characteristics 97
6-2 Pressure Drop Life Characteristics 99
6-3 Pressure Drop Life Characteristics 101
6-4 Pressure Drop Life Characteristics 102
6-5 Particle Size Distribution of Feed & Effluent Dust 104
6-6 Efficiency as a Function of Air-to-Cloth Ratio 105
7-1 Welding Table at Cornelius Company 111
7-2 Installation at Cornelius Company - Welding Fume 112
7-3 Test Setup at Cornelius Company 113
7-4 Pressure Drop Characteristics Field Test Unit at Cornelius
Company 114
7-5 820 Magnification of Welding Fume - Stage 4 of Andersen
Sampler 117
7-6 10K SEM Micrograph of Ambient Welding Fume 118
7-7 10K SEM Micrograph of Upstream and Downstream Samples of
Welding Fume 119
IV
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LIST OF FIGURES (Continued)
Figure Page
7-8 20K SEM Micrograph of Upstream & Downstream Samples of
We Id ing Fume 120
7-9 SEM Micrographs of Welding Fume - Upstream 121
7-10 SEM Micrographs of Welding Fume - Downstream 122
7-11 10K TEM Micrograph of Upstream & Downstream Samples of
Welding Fume 123
7-12 50K TEM Micrograph of Upstream and Downstream Samples of
Welding Fume 124
7-13 Operating Pressure Drop as a Function of Time (Cornelius Co.) 128
7-14 Dirty versus Clean Filter Elements - Cornelius Company - Welding
Fume 129
7-15 Innoculation Process at Northern Malleable Iron Company 133
7-16 Installation at Northern Malleable Iron Compny 134
7-17 Test Setup at Northern Malleable Iron Company 135
7-18 Particle Size Spectrum Analysis Northern Malleable Iron Companyl37
7-19 10K TEM Micrograph of Upstream and Downstream Samples of
MgO Particulate 138
7-20 SEM Micrographs of MgO Particulate - Upstream 139
7-21 SEM Micrograph of MgO Particulate - Downstream 140
7-22 Dirty versus Clean Filter Cartridges - Northern Malleable -
MgO Emission 144
7-23 Failed Filter Cartridge - Light Spot Indicates Hole in Media 145
7-24 Operating Pressure Drop as a Function of Time (Northern
Malleable Iron Company) 146
8-1 Capital Costs for Electrostatic Precipitators for Vertical Lime
Rock Kilns (High Efficiency) 148
8-2 Annual Costs for Electrostatic Precipitators for Vertical Lime
Rock Kilns (High Efficiency) 150
8-3 Capital Costs for Wet Scrubbers for Vertical Lime Rock Kilns
(High Efficiency) 152
8-4 Annual Costs for Wet Scrubbers for Vertical Lime Rock Kilns
(High Efficiency) 154
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LIST OF FIGURES (Continued)
Figure Page
8-5 Capital Costs for Fabric Filters for Vertical Lime Rock Kilns 156
8-6 Annual Costs for Fabric Filters for Vertical Lime Rock Kilns 158
8-7 Capital Costs for Cartridge Filters for Vertical Lime Rock Kilns 160
8-8 Annual Costs for Cartridge Filter for Vertical Lime Rock Kilns 162
8-9 Annual Cost Comparison for Electrostatic Precipitators, Wet
Scrubbers, Fabric Filters and Cartridge Filters (High Efficiency) 164
8-10 Capital Cost of Electrostatic Precipitators for Glass-Melting
Furnace 167
8-11 Annual Cost of Electrostatic Precipitators for Glass-Melting
Furnace 169
8-12 Capital Cost of Wet Scrubbers for Glass-Melting Furnace 171
8-13 Annual Cost of Wet Scrubbers for Glass-Melting Furnace 173
8-14 Capital Cost of Fabric Filters for Glass-Melting Furnace 175
8-15 Annual Cost of Fabric Filters for r lass 177
8-16 Capital Cost of Cartridge Filters for Glass-Melting Furnace 179
8-17 Annual Cost of Cartridge Filters for G lass-Melting Furnace 181
8-18 Annual Cost Comparison for Electrostatic Precipitators, Wet
Scrubbers, Fabric Filters and Cartridge Filters for Glass-
Melting Furnace 182
VI
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LIST OF TABLES
Table Page
4-1 Langmuir Pressure Drop 19
4-2 Langmuir Pressure Drop with Knudsen Number Correction 21
5-1 Results of Multiple Sheet Testing of Medium (8/26/75) 24
5-2 Physical Data 37
5-3 Physical Data 38
5-4 OOP Efficiency of Medium (4/10/76) 41
5-5 Clean Filter Pressure Drop 90
7-1 Andersen Cascade Impactor Data for Cornelius Company -
Upstream Particle Size 115
7-2 DOP Efficiency of Cartridges for Field Test at Cornelius
Company 126
7-3 Overall Mass Efficiency for Field Test at Cornelius Company 126
7-4 Fractional Efficiency for Field Test at Cornelius Company 126
7-5 Pulse-Cleaning Durability Tests 130
7-6 Andersen Cascade Impactor Data for Northern Malleable-
Upstream Particle Size 131
7-7 DOP Efficiency of Elements for Field Test at Northern
Malleable Iron Company 141
7-8 Overall Mass Efficiency for Field Test at Northern Malleable
Iron Company 142
7-9 Fractional Efficiency for Field Test at Northern Malleable
Iron Company 142
8-1 Estimated Capital Cost Data (Costs in Dollars) for Electrostatic
Precipitators for Vertical Lime Rock Kilns 149
8-2 Annual Operating Data (Costs in $/Yr) ft>r Electrostatic Precip-
itators for Vertical Lime Rock Kilns 151
8-3 Estimated Capital Cost Data (Costs in Dollars) for Wet Scrubbers
for Vertical Lime Rock Kilns 153
8-4 Annual Operating Cost Data (Costs in $AO for Wet Scrubbers
for Vertical Lime Rock Kilns 155
vii
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LIST OF TABLES (Continued)
Table
8-5 Estimated Capital Cost Data (Costs in Dollars) for Fabric Filters
for Vertical Lime Rock Kilns 157
8-6 Annual Operating Cost Data (Cost in $/Vr) for Fabric Filters for
Vertical Lime Rock Kilns 159
8-7 Estimated Capital Cost Data (Costs in Dollars) for Cartridge
Filters for Vertical Lime Rock Kilns 161
8-8 Annual Operating Cost Data (Costs in $/Yr) for Cartridge Filters
for Vertical Lime Rock Kilns 163
8-9 Estimated Capital Cost Data (Costs in Dollars) for Electrostatic
Precipitators for Glass-Melting Furnace 166
8-10 Annual Operating Cost Data (Costs in $Ar) for Electrostatic Pre-
cipitators for G lass-Melting Furnace 168
8-11 Estimated Capital Cost Data (Costs in Dollars) for Wet Scrubbers
for G lass-Melting Furnace 170
8-12 Annual Operating Cost Data (Costs in $/Yr) for Wet Scrubbers
for Glass-Melting Furnace 172
8-13 Estimated Capital Cost Data (Costs in Dollars) for Fabric Filters
for G lass-Melting Furnace 174
8-14 Annual Operating Cost Data (Costs in $Ar) for Fabric Filters for
Glass-Melting Furnace 176
8-15 Estimated Capital Cost Data (Costs in Dollars) for Cartridge
Filters for Glass-Melting Furnace 178
8-16 Annual Operating Cost Data (Costs in $/Vr) for Cartridge Filters
for Glass-Melting Furnace 180
viii
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ABBREVIATIONS AND SYMBOLS
o
am /min = actual cubic meters per minute
C1 = Cunningham correction factor
CQ = drag coefficient
d, = fiber diameter
dp = particle diameter
OOP = dioctylphthalate
K, = interception parameter
K = Knudsen number
n
K = impaction parameter
d = length of filter bed measured in direction of gas flow
LA Process Wt = Los Angeles process weight requirements
In = logarithm to base e
N = Peclet number
N« r = Reynold's number, fiber diameter
P = gas pressure
ppsi = points per square inch
S = solidarity factor, the ratio of the total projected area of fibers
to the face area of the filter mat in the direction of gas flow
SEM = scanning electron micrograph
*i
sm /min = standard cubic meters per minute
T = gas temperature
U = upstream velocity
w1 = basis weight
T)D = single fiber efficiency for collecting by diffusion
= single fiber efficiency resulting from diffusion, interception and
impaction
= single fiber efficiency resulting from interception and impaction
17 = effective efficiency of a single fiber
X = mean free path of air molecule
\L = viscosity of gas
Pf = fiber density
P = gas density
y
p = particle density
P ix
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ACKNOWLEDGMENTS
The work presented in this report was performed by the Protective Systems Department
of the CORAD Division of Donaldson Company, Inc. The work was performed as
Phase I of Contract 68-02-1878 for the Environmental Protection Agency, Research
Triangle Park, North Carolina.
Technical direction from EPA was provided by Dr. Dennis Drehmel, Project Officer.
At Donaldson Company, the Principal Investigator during Phase I and part of Phase II
was Michael Shackleton. William Krisko was the Principal Investigator during the
field testing portion of this contract. Harry Camplin performed many of the tests
and Gene Grassel, Ron Sundberg and Bob Frey provided technical consultation.
Approved for:
Donaldson Company, Inc,
>hn H. Scott
'Contracts Manager
(Date) 20 Oct 1977
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1.0 INTRODUCTION
Fabric filtration is a historic means of dust control. It has enjoyed wide acceptance
in varied applications to remove particles from gas streams. Through tailoring of
filter media and proper design application, almost any degree of collection efficiency
of any dust distribution can be achieved. Historically, efficiency has been evaluated
on the basis of mass removal. Since large particles (>3|Lim) are inherently easier to
remove than small particles (<3^m)/ high efficiency has been obtained even with
significant numbers of small particles penetrating the filter.
In recent years, environmental hazards have been associated with the presence of
submicrometer and other fine particles. For this reason, the development of economic
means of controlling fine particles is desirable.
Improvement in collection efficiency can be achieved by simply making a filter bed
thicker, thus increasing the basis weight of the filter (its weight per unit area). How-
ever, to achieve high collection efficiency of particles with ordinary filter fibers may
lead to excessively thick filter beds which operate at a high pressure drop and are
difficult to clean.
Examination of design equations for fabric filters reveals that collection efficiency for
a given particle is a function of fiber diameter. This functional relationship is such
that collection efficiency is increased as fiber diameter is decreased.
For a given efficiency, the required filter bed thickness is also decreased as fiber
diameter is decreased. Analysis indicates that if fiber diameter is made small enough,
the filter bed thickness can be reduced to reasonable values, giving a good probability
of excellent cleanability as well as satisfactory collection efficiency of submicrometer
particles. In order to provide structural strength to a filter bed of a very thin layer of
fine fibers, the fine fiber filter is supported upon a backing medium. Ideally, this
backing medium is very porous to allow minimum resistance to airflow. The combination
of a porous backing medium with a filtration layer of fine fibers is referred to as a
double mat filter.
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The central purpose of Contract 68-02-1878 was to examine and demonstrate the
effectiveness of filters made from fine fibers capable of collecting submicrometer
particles in an economic manner.
Our approach to this investigation involved two phases. During Phase I, the
theoretical basis for the work was documented and developmental testing to select
a suitable media composition for work in Phase II was accomplished. Phase II
included testing in a pulse-jet filter unit in both the laboratory and in the field.
This report presents the results of work in Phases I and II of this contract.
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2.0 CONCLUSIONS
Examination of design equations for fabric filtration indicate that fabric filters
constructed from submicrometer diameter fibers could have significant advantages
for fine particle collection. The theoretical relationship between filter performance
and fiber diameter is presented in Section 4.0. It is shown theoretically that filters
constructed from submicrometer fibers are capable of high efficiency collection
(90 percent) of fine particles (0.3 n m). Because of the effectiveness of fine fibers,
filters constructed from them have basis weights approximately 10 gm/m (0.29 oz/yd )
and is only capable of 10 to 20 percent collection of 0.3 ^m particles. The low
basis weights possible with fine fibers result in a filtration layer so thin that it is
barely perceptible to the naked eye when deposited upon a paper-type filter backing
medium. This thin filtration layer encourages surface collection of particles which
enhances cleaning.
Results of OOP efficiency testing conducted under the contract show that fine fiber
filters with low basis weights are capable of high collection efficiency. Scanning
electron micrographs tend to confirm the theoretical relationship between fiber
diameter and basis weight of the fine fiber filters.
Dust feeding tests were conducted on various media using AC Fine test dust at 50 mm/sec
air-to-cloth ratio in a flat-sheet pulse jet test rig. At this velocity, woven polyester-
sateen filter media had a low efficiency and a rapid rate of pressure drop increase.
Dacron felt bag ho use filter material had better efficiency (99.5 percent) and a slow
rate of pressure drop increase with time. These results are similar to those expected
for the test conditions and provide confidence that the test rig simulated performance
in a full scale filter unit. Tests of fine fiber media indicated that pressure drop
performance during dust feeding tests was similar to felt; that is, a relatively low
and stable pressure drop was maintained. Overall collection efficiency of AC Fine
test dust was much higher for the fine fiber materials than for felt; greater than
99.999 percent by weight was measured for most samples.
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Two types of backing materials were evaluated for the Fine fiber filters during Phase I.
These were felt and synthetic paper filter media. In general, tests involving the
felt backing indicated poor adhesion between the fine fiber surface and the backing,
resulting in damage to the fine fiber layer. Tests where the fine fiber layer was
deposited on a dacron-paper media backing showed good performance. Filter media
in this form is also more appropriate for application in a cartridge filter.
Dust tests were conducted in the laboratory on pleated cartridges under Phase II.
Cleaning pressures and air-to-cloth ratios were varied. The pressure drop of the
cartridges was stabilized at an acceptable level when 689 K Pa of cleaning pressure
was used. The test data indicated that collection efficiency for AC Fine test dust
is a function of air-to-cloth ratio. (The fine fiber media can achieve the same
collection efficiency as standard media, but at higher air-to-cloth ratio.) Fine
fiber media can run at air-to-cloth ratio of 8 to 1 at the same efficiency as standard
media, at a 2 to 1 air-to-cloth ratio. Cleaning pulse pressure had no effect on
collection efficiency.
Field tests at two different sites were conducted under Phase II on pleated cartridge
filter units using the fine fiber media and with both sites presenting fine particle
emission. One site was a welding fume and the other site consisted of magnesium
oxide from a metallurgical process. The particulates were characterized at each
site and the overall mass efficiency and fractional efficiency were determined for
the systems. The overall mass efficiency was 97.6 percent on the welding fume and
99.95 percent on the magnesium oxide.
Preliminary economic analysis indicated that fine particles can be efficiently removed
using the filter cartridge configuration with fine fiber media at costs significantly
less than for standard fabric filter application. There are two primary reasons for
this cost advantage. These are:
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I) The cartridge configuration allows a major reduction in the volume
of a filter unit for a given through-put flow rate and air-to-cloth
ratio. This advantage results from the compactness achieved by pleating
the filter medium. Significant cost reduction is achieved with this
technique even with standard filter media. When using standard media,
as with baghouse fabric filters, high efficiency collection of fine
particles is achieved only at very low air-to-cloth ratios (on the
order of 5 mm/sec).
2) The fine fiber media allows high efficiency collection of fine
particles at increased air-to-cloth ratio. This fact results in further
reduction in the size of filtration equipment. Our flat-sheet
cleaning tests indicate that at an air-to-cloth ratio of 50 mm/sec
pressure drop performance of the fine fiber media is similar to standard
baghouse felt, while collection efficiency of AC Fine test dust is
increased from 99.5 percent for felt to nearly absolute for the fine
fiber media.
In a cartridge filter fine fiber air cleaning application, the only
component likely to cost more than present systems is the filter medium
itself. Even conservative estimates for this cost are overwhelmed by
the cost savings resulting from the size reduction obtainable from
use of the cartridge configuration and the higher air-to-cloth
ratios of the fine fiber medium.
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3.0 RECOMMENDATIONS
Based on the encouraging results to date, it is recommended that the fine fiber media
be further demonstrated in a pulse-jet cleaned dust collector on a larger scale — at
least 10,000 cfin. The system could be Installed at a site that presents an industrial
emission of fine particles (<3Mm size). Some of these emissions include: non-ferrous
salvage operations, welding fumes, ferroalloy fumes from a cupola or electric
furnace, carbon black, solid waste combustion, spray drying operations and asphaltic
pavement manufacturing.
The Tor it Division of Donaldson Company has a line of dust collectors using pulse-
cleaned pleated cartridge filters that could be applied. For example, there is a
TD 6120 that uses 32 filter cartridges for an actual total filter area of 6124 sq. ft.
Using standard filter media and an air-to-cloth ratio of 1.5, the airflow would be
9186 cfm. However, with the fine fiber cartridges and an air-to-cloth ratio 3 to 1,
the airflow could be increased to 18,372 cfm. Since the double mat filter media
permits higher inlet velocities and substantially increased air-to-cloth ratios, it may
be necessary to modify the dust collector design and to relocate the air inlet. Also,
it might be necessary to use baffles between elements which may minimize re-
entrainment from the increased velocity.
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4.0 THEORETICAL ANALYSIS OF THE EFFECT OF FIBER DIAMETER ON
PARTICLE COLLECTION
Collection efficiency for 0.3 U m diameter DOP particles is predicted as a function
of filter basis weight with fiber diameter as a parameter.
Particle collection in fibrous beds is influenced primarily by three basic collection
mechanisms: Direct interception, inertial impact ion and diffusion. Examination of
the equations describing the effects of each of these mechanisms reveals that fiber
diameter is a parameter in each of them.
The following analysis will result in a prediction of particle collection efficiency for
0.3 Mm diameter DOP particles as a function of basis weight for a filter bed composed
of 1.0 U m diameter fibers. Figure 4-1 presents the results of this analysis as well as
analyses for other fiber diameters determined in the same manner.
Given:
Fibers
Fiber diameter d = 1.0 U m = 0.0001 cm
o
Fiber density (nylon) p f = 1 .135 gm/cm
Particles (DOP)
Particle diameter dp = 0.3 u m = 0.00003 cm
o
Particle density p p = 0.984 gm/cm
Gas Stream
Upstream velocity U =2.54 cm/sec
-4
Viscosity M = 1.8 x 10 gm/cm sec
y
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io.oi
40 50 60 ? 70 80 90 100 1:C 120 130
Basis Weight gm/m
Figure 4-1. Fitter Efficiency as a Function of Basis Weight
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—3 3
Gas density P =1.2x10 gm/cm
y
Gas temperature T = 300 K
Gas pressure P = 76 cm Hg
Reynolds number is:
"g
3 3
I =2.54 cm/sec 1 .2 x 10 gm/cm 0.0001 cm
Ref - q — - -
1.8x1 0~4 gm/cm sec
Since N,» , is < I, the flow is viscous.
The Cunningham correction factor (C1) at 76 cm Hg is given by:
C = || + 2TX10"8 [2.79 + 0.894 exp f -2.47 x IP7 dp
[_ dp I IT
C 4 + 2 (300) x IP"8 [2.79+ 0.894 exp f-2.47 x IP7 (0.3 x 10"4)
^ 0.3 x IO-4 I I 300
C -1.573
The Pec let number is:
N . Uodf = Uod
pe D C1 K T
P
K = Boltzmann's constant
11
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N = 2.54 cm/sec (1 x IP"4 cm) 3 v (1.8 x IP"4 gm/cm sec) 3x10" cm
Pe 1.573 (1.38 x IO-16 gm cm* P K sec2) (300°K)
N +198.5
Pe
The drag coefficient is calculated from:
C = 8
NRef[2-'"
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The impact Ion parameter K is:
K =
P
dp
U C'
9Ug df
K = (3 x IP"5 cm?(0.984 gm/cm3) (2.54 cm/sec) 1 .573
P 9 (1 .8 x 10"4 gm/sec cm) (1 x 10"4 cm)
K = 0.02184
P
Single fiber efficiency resulting from interception and impoction is given by:
T},|=0.0518
CD N Ref
= 0.0518 0774) 1.<
I 2
= 0.01405
3/2
+ 0.16
0.3
3/2 +
0.16
(0.5+0.8 K,) -E. -0.1051K, -E-
0.5+ 0.8 (.3)
0.02184
-0.1052 (.3) 0.02184
\ 2
•I1]
Since the Reynolds number (N« ,) is < 0.5, the Torgeson equation for single fiber
efficiency when diffusion, interception and impact ion are all operative can be used
= 0.75 Tf +FG(M)
where:
F =
D
0.6
N
Pe
0.6
Kp
2
(r N \ ~°'*
CPNRef 1 N
Pe
F = 1.01255
13
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and:
M = CD NRef K . 5/2
= 14.668
G (M) is then determined from the curve, Figure 4-2, as:
G (M) = 1.38
Substituting:
TJ D|p = 0.75 (0.01405) + 1.01255 (1.38) 0.03686
= 0.06204
Kimura and linoya provide an equation for effective efficiency t? of a single fiber
as follows:
11 s= n DIP [ ] +10(NRef) °]
Effective efficiency provides a measure of the effect of neighboring fibers within a
fiber bed.
The factor ff is the volume fraction of a fibrous bed which is solid. For this analysis,
assume a is 0.1. Then:
T?S = 0.06204 (1+10 (1.69 x 10~3) ]/3 (0.1)1
T? = 0.0694
14
-------
0.1
10
100
1000
«*«*»*«
*******
***###»
Figure 4-2 . G(M) «**»«** for Torgeson Theory
***««*»
»»»#*»#
#»*#*»*
#»*#**#
#**»*#»
-------
Whitfay has provided the following equation,
E = 1 - exp (- 7? S)
s
to describe the collection effciency of a bed of clean fibers on particles of a specified
size. The term "S" is the solidarity factor which is the ratio of the total projected area
of the fibers to the face area of the filter mat in the direction of gas flow.
The solidarity factor is expressed as:
S= *l a 4w'
Where £- is the length of filter bed measured in the direction of gas flow and w* is
the basis weight or weight per unit area of the filter bed.
In this analysis, we are trying to achieve 90 percent collection efficiency of 0.3 m
OOP particles. Therefore, from:
E = 1 - exp (- Tj S)
S In e = In (I - E)
S= -Ml-E)
T? In e
S= -In (1-0.9)
0.0694 (1)
S = 33.2
Therefore, for 1 .Oum diameter fibers, 33.2 solidarity factors are required to achieve a
filter bed capable of collecting 90 percent of 0.3 n m OOP particles.
16
-------
The basis weight required to achieve this many solidarity factors is determined from:
4 w'
S =
w1 =
rV
4
3
, = 1.1 35 gm/cm (0.0001 cm) 33.2
w =
4
2
w1 =0.002959 gm/cm
2
w' = 29.6 gm/m
This result is plotted on Figure 4-1 with the curve extrapolated to show efficiency as a
function of basis weight for filter beds of 1 .0 /im diameter fibers. The performance of
filter beds constructed from other fiber diameters is also shown on Figure 4-1 .
Basis weight as a function of fiber diameter for constant efficiency is presented on
Figure 4-3.
Pressure Drop
Longmuir developed an equation to predict pressure drop in a fabric filter as follows:
£p= 8 a M g Uo
_
(-1/2 In a+ a -»V4+3/4) df
where:
a = fiber volume fraction of the filter =0.1 for this analysis
f = fiber diameter in cm
-4
Mg = gas viscosity = 1.8 x 10 gm/cm sec
Uo = upstream gas velocity = 2.54 cm/sec
= filter bed thickness in cm (fn
17
-------
500
10
far!? CHtiM^eidKj&St: flfrPfy^K-^f
: j :~: ; : • ! : : i JTrN iTtt rrrTI-T-t:t:
• • < • • T - • J J f-f ..,-,-.-.-:- *• 1--T-
. , . . 4 , J ., i , . . r . . t- -T- i 4-
: . :| :;:. i | n M ,;..;; i;:
Averoge Fiber Diameter (jun)
Figure 4-3. Basis Weiaht as Function of Fiber Diameter
18
-------
Filter bed thickness is given by,
w1
For this ana lysis,
* =0.1
o
Oc =1.135 gm/cm
Substituting into the above equation yields pressure drop as a function of fiber diameter
for filter beds capable of 90 percent collection efficiency of 0.3 am diameter particles
at a filtration velocity of 2.54 cm/sec.
Table 4-1 summarizes this analysis. Pressure drop as a function of fiber diameter is
plotted as Figure 4-4.
Table 4-1. Langmuir Pressure Drop
Fiber diameter
df (cm)
5x 10
1 x 10"5
3xlO"5
-5
7x 10
-4
1 xlO
SxlO-4
Filter bed Thickness
JL (cm)
5.61 x 10"5
3.03 xlO"4
2.97xlO~3
_2
1.38x10
2.61 xlO"2
1.633X10"1
Pressure Drop
o
AP (gm/cm )
1.68
2.27
2.47
2.11
1.95
1.36
Pressure Drop
AP (mm H2O)
16.8
22.7
24.7
21.1
19.5
13.6
Yeh and Liu have developed a correction for slip flow using the Knudsen number
Applying this correction to Langmuir's equation yields:
19
-------
.
: .1 .1 |.
-I..
l .;:
:, :Hi: .
35
Langmuir
J .'
O - A P *'
30
--
1 In o,
2
'9
4(1+ICn)
F-=f)
25
20
O
CN
Q.
8.
o
I
(A
10
,
=1.8x10 gm/cm sec
*:"* '!.-"J I; •-r
F : •!:' V,- 4 -r-- '
df/2
X = 0.0653Mm @20°C
_ ^ ^
pi" I " " . -I. . '
' ~
• r
OKi£.
I?,.;--4. 90% Efficiency of 0.3/zm OOP i :;
-^-i
1 2
Effective Fiber Diameter (Jim)
Figure 4-4. Pressure Drop os a Function of Fiber Diameter
20
-------
p =
-1/2 In o< -
4 0
Where:
d,/2
X = 0.0653 Mm @ 20°C
= mean free path of gas molecules
Pressure drop using this equation is shown in Table 4-2,
Table 4-2. Langmuir Pressure Drop with Knudsen Number Correction
Fiber diameter
df (cm)
5xlO"6
1 x 10"5
3xlO"5
7xlO"5
-4
1 xlO
SxlO"4
Knudsen Number
K
n
2.612
1.306
0.4353
0.1866
0.1306
0.0435
Filter Bed Thickness
5.61 x 10"5
3.03xlO"4
2.97xlO"3
1 .38 x 10"2
2.61 x 10"2
1.633x 10"1
Pressure Drop
A P (gm/cm )
Q-.77
1.18
1.65
1.68
1.64
1.27
Pressure Drop
AP (mm H2O)
7.7
11.8
16.5
16.8
16.4
12.7
These results are plotted on Figure 4-4. This analysis indicates that there should be
no severe pressure drop penalty when employing fabric filters made from fine fibers.
21
-------
5.0 PRELIMINARY EXPERIMENTS
Preliminary experiments during Phase I were of three types. These were:
1) DOP penetration tests to relate basis weight to collection efficiency
2) Scanning electron micrograph analysis of fine fibers to relate fiber
diameter to basis weight
3) Dust loading tests in a flat-sheet pulse-jet test rig to simulate performance
in a pulse-jet fabric filter
5.1 DOP Penetration Tests
One of the design objectives of the contract is to produce a cleanable filter media capable
of collecting 0.3u m DOP at an efficiency of 90 percent. To meet this objective, DOP
penetration tests were used to evaluate various media during Phase I. We have been
successful in producing filter media from fine fibers which have high collection efficiency
and low basis weight. In general, the theoretical relationship shown on Figure 4-1 was
confirmed by the data.
The first sample produced for testing under the contract was a thin layer of fine fibers
deposited on a light-weight backing material. The fine fiber sheet was then removed from
the backing material and tested alone. Table 5-1 presents the results of testing multiple
sheets of this material for basis weight, permeability and penetration. This material is
designated medium (8/26/75) because it was made August 26, 1975.
The penetration data is plotted on Figure 5-1 showing a comparison with calculated
performance. This first sample had an apparent average fiber diameter of about 3(J m.
To obtain the necessary strength in the media, the fine fiber layer must be supported on
a backing material. Felt was the first material evaluated as a backing medium. After
first determining that the fine fibers could not be separated and handled on a carding
machine, the following double mat samples were produced by needle-punching. A *41
23
-------
Table 5-1. Results of Multiple Sheet Testing of Medium (8/26/75)
Number of Sheets
1
2
3
4
5
6
Basis Weight
2
(gnri/m )
26.16
53.28
78.47
104.14
125.94
153.55
Permeability
(m3/min@ 1.27cm HjO)
20.61
18.00
12.60
5.34
4.53
3.54
Penetration
(%)
66
43
29
20
13
9.7
24
-------
Calculated for 3.0 u m Fiber Bed (nylon)
U = 2.54 cm/sec
90% Efficiency
MEASURED DATA
MULTIPLE SHEETS
OF FIBERS (8/26/75)
U = (2.68 cm/sec)
Calculated for 1 .0 u m Fiber Bed
U =2.54 cm/sec (nylon)
90% efficiency
Figure 5-1. OOP Penetration as a
Function of Basis Weight
10 20 30 40 50 60 70 80 90
01
?9.99
-------
needle was used with about 16 needles per cm (40 needles per inch). The machine was
set at 250 punches per minute.
• Sample Number 1:
Two layers of 2 oz (68 gm/m2), 3 denier polyester were needled to a
10x10 scrim. Then six layers of the fine fibers were placed on top of
this backing with the scrim between the fibers and backing. The fine fiber
layer was needle-punched into the backing material. This method resulted
in poor adhesion of the fine fibers to the backing. The needles also left
obvious holes in the fine fiber layer.
• Sample Number 2:
Six layers of fine fibers were needled to the same backing material with
the needles passing first through the backing material. This carried some
of the felt fibers through the hole in the fine fiber layer and seemed to
result in good adhesion.
• Sample Number 3:
Six layers of fine fibers were placed over the some backing, as in Samples
2
1 and 2 with the scrim between the fibers and back. Then a 2 oz (68 gm/m )
polyester sheet was placed over the fine fiber layer. The sample was then
needle punched. This method resulted in good adhesion but the layer of
felt over the fine fiber layer was considered likely to interfere with cleaning
of the fine fiber layer.
In order to illustrate the relative performance of the fine fiber filter, penetration tests
using 0.3 ju m DOP smoke were made on a variety of materials. Figure 5-2 shows the
results of this testing as a function of airflow velocity. This data illustrates the
effectiveness of the fine fibers for collection of fine particles. Even a single layer with
a basis weight of 26 gm/m was more effective than standard baghouse filter media. Also
illustrated is the degradation caused by the needle punching. Note the difference in
collection efficiency between six layers of the fine fibers (Sample M) and media Sample
No. 2 which contained six layers of fine fibers with needle holes.
26
-------
100
90
80
70
60
50
tn
a.
o
40
x
o
J
£ 30
10
:;:~ r
-
See Attached
Pages for
Lefter-Code
Clarification
5 10
Airflow Velocity (mm/sec)
Figwe 5-2. Penetration Tests of Various Media
27
-------
Code Number Identification for Figure 5*2.
Code No.
A Woven Polyester Felt «
Perm = 4.38 m3/min/rn @ 1.27 cm HjO
B Polyester TwilL 9
Perm = 5.06 m/mm/m @ 1.27 cm
C Polyester Sateen 9
Perm = 3.78 m3/min/rn @ 1.27 cm
D Polypropylene Felt «
Perm =8.53 m3/min/m @ 1.27 cm HjO
E Cotton Sateen « 9
Perm = 4.10 rn /min/m @ 1 «27 cm HjO
F Felted Dacron « 9
Perm = 25.45 rn/min/m @ 1.27 cm HjO
G DURALIFE®!! (Commercial Filter Paper)
Perm =6.40 m3/min/m2 @ 1.27 cm HjO
H 1 Layer Fine Fibers (8/26/75)
Perm =20.61 m3/min/mz@ 1.27 cm H«0
Basis Weight = 26.16 gm/m2 i
I 2 Layer Fine Fibers (8/26/75)
Perm = 18.00 m3/min/m . @ 1.27 cm H?0
Basis Weight = 53.28 gm/m?
J 3 Layers Fine Fibers (8/26/75)
Perm = 12.60 m3/min/m2© 1.27 cm HO0
Basis Weight = 78.47 gm/m2 i
K 4 Layers Fine Fibers (8/26/75)
Perm =5.34 m3/min/m2 @ 1,,27 cm H00
Basis Weight = 104.14 gm/mZ *
I 5 Layers Fine Fibers (8/26/75)
Perm = 4.53 m3/min/m2 @ 1,27 cm H00
Basis Weight = 125.94 gm/mZ Z
M 6 Layers Fine Fibers (8/26/75)
Perm =3.54 m3/min/n/ @ L27 cm H«0
Basis Weight = 153.55 am/mZ 2
)URALIFE is a registered trademark of Donaldson Company, Inc., Minneapolis, MN. 55435
28
-------
Code Number Identification for Figure 5-2 (continued)
Code No.
N 7 Layers Fine FJbers (8/26/75)
Perm = 3.07 mVmin/m @ U27
rm . mmnm cm H«0
Basis Weight = 1 82 .37 gm/mz
2 2 Layers 2 Oz., 3 Denier Polyester Needled ('41)
to Scrim- then Needled jnto 6 Layers of Fine Fibers (8/26/75)
Perm ^3.66 rn /min/m* @ 1 .27 cm H^O
2A Same as 2 but with One Additional Layer of Fine
Fibers (8/26/75) Cemented Over Needle Holes
Perm = 3.35 m3/min/m2@ 1 .27 cm H00
29
-------
A second run of fine fiber media was produced in an attempt to reduce the average fiber
diameter. This medium was produced on 9/18/75 and is referred to as medium (9/18/75).
Figure 5-3 shows that a reduction in average fiber diameter was accomplished. Multiple
layers of medium (9/18/75) were tested for OOP efficiency as a function of airflow velocity.
This data is plotted in Figure 5-4. Because of the smaller average fiber diameter,
Q
100 gm/m of medium (9/18/75) could achieve an efficiency of 90 percent on 0.3/i m
o
DOP; while over 150 gm/m of medium (8/26/75) was required to achieve the same
efficiency.
Using medium (9/18/75), additional double mat filter samples were produced. As in
Sample No. 2 above, a scrim was needled to a felt backing; then the fine fibers were
needled to the scrim/felt by needling through the felt into the fine fibers.
The following samples were obtained:
• Sample Number 4:
Single layer fine fiber 9/18/75
6 denier felt - 22 x 18 scrim
Laminated at 300 points per square inch (pps?)
Re-needled at 250 ppsi
• Sample Number 5:
Same as No. 4 but re-needled at 200 ppsi
• Sample Number 6:
Double layer of fine fibers
6 denier felt - 22 x 18 scrim
Laminated at 300 ppsi
Re-needled at 200 ppsi
• Sample Number 7:
Single layer of fine fiber
6 denier felt - 10 x 10 scrim
Laminated at 300 pps!
Re-needled at 200 ppsi
30
-------
Data
8-26-75
U =2.68 cm/sec
Calc'jIaM I .0/1 m
Fiber Bed
U ^2.54 cm/sec
o
x
U
c
— 99.9
140
. 2
Basis We^iit - gm/m
Figure 5-3. Penelrolicn as o FincH^n of 9asis V/ciyhf
31
-------
100
90
80
70
60
50
.8
o
Q40
o
u
.1 30
i
20
10
1 Lay«r FIM Fibers fr/181/75 li.
2
I -(
I1: "
t-
;• j •
:."ii; :fe:iii
•i'
,, r .--n.-.;.
i
, 11
. r.
-I '
: I—i '
] : i :r
i
4
-^
-h
I .1
I I
• v:
I .'•->:
i::- k
OU 80 100
Airflow Velocify (mm/sec)
120
140
160
Figure 5-4. Penetration as a Function of Airflow Velocity
32
-------
• Sample Number 8:
Double layer of fine fiber
6 denier felt - 10 x 10 scrim
Laminated at 300 ppsi
Re-needled at 200 ppsi
• Sample Number 9:
Single layer of fine fibers
3 denier felt -10x10 scrim
Laminated at 300 ppsi
Re-needled at 200 ppsi
• Sample Number 10:
Double layer of fine fibers
3 denier felt -10x10 scrim
Laminated at 300 pps?
Re-needled at 200 ppsi
• One additional sample was produced by fastening two layers of fine fibers
to a backing of 3 denier felt with a 10 x 10 scrim. The adhesion was
accomplished by sonic welding on a 2.5 cm square grid pattern. Visually,
this method seemed to result in a strong bond between the materials.
The felt and scrims used in these samples were dacron.
DOP penetration tests using 0.3/im OOP smoke were made on the media samples.
Figure 5-5 shows collection efficiency for the samples. This figure shows the degradation
in performance by the needle holes. The performance of one and two layers of these
fibers alone are also presented. Media Samples 4 through 10 are shown in the range
of 30 to 60 percent efficiency. These samples consisted of one or two layers of fibers
needle-punched to a backing material. In general, the samples fabricated from one layer
of fiber had slightly lower efficiency than those with two layers of fibers. Samples
designated 4A through 10A had an additional layer of fibers placed over the needle holes.
Significant recovery of efficiency was achieved from this additional layer of fibers. Note
33
-------
100
90
80
70
60
Q.
o
Q
50
CO
o^
t40
u
c
0)
30
20
10
. •'.'^^Jatty'*'*'---
''mi
rrr-
. a
-^^
-+-; - -I:-,- HiMrHP
IS' i
i ;^
—
i ;;
I
Felt
V2 Ldx*rf Fibe:
x N Sonic
Weldediin^.bcr,
Gri^Tb, BdcWng
'
—
ppsi/22 xfilS Scrim
:ri^
Same ias 1^4. 4_bbt Ndedled at 200 ppsi, 22 x 18
Denier Fifltj 2 Layers Rb«rs; Needled 2
•- '• '
im
^ ^l)«f*ier
iJ-t Layer F&ett; ivrfeedle4r2DOrpp5T;ho x It)
TCT Fibers,
ie
Ftb«r$
H 10 x 10 ScHffl
1 •' :
'i
_L
6012:00 pesM 0 xiQ acnmt
j4j ; | ;. ; . . ^T ,
; :' *•''•
20
40
60 80 100
Airflow Velocity (mm/sec)
120
140
160
Figure 5-5. Efficiency of Media Samples
34
-------
also that samples with either one or two layers of fine fibers achieved about the same
performance with an additional layer of fibers placed over the needle-holed surface.
Also shown is one data point for a sonic welded sample. Two layers of fibers were placed
over a backing of 3 denier felt with a 10 x 10 scrim and welded to the backing in a 2.54 cm
grid pattern. This data point shows that the sonic welding method of adhesion does not
degrade efficiency.
In order to further examine the effect of the needle holes, we counted the number of
2
holes per square inch (6.45 cm ) in Samples 4 and 5. These two samples were produced
with the needle punch machine set at 250 points per square inch and 200 points per
square inch (ppsi) nominal. Efficiency was then plotted as a function of the number of
needle holes to produce the data shown on Figure 5-6. This data shows a clear functional
relationship between the number of holes and the loss in efficiency.
Other physical data for the samples are tabulated in Tables 5-2 and 5-3. The average
thickness of a single layer of fine fibers (9/18/75) was 0.0335 cm.
Continuing efforts to reduce fiber diameter resulted in medium (1/26/76). Figure 5-7
presents penetration by 0.3 Mm OOP as a function of basis weight for this material. Also
presented are calculated results for 1 to 3 am fiber beds and results of testing earlier
samples of double mat filters. These results show that the medium (1/26/76) has an
average fiber diameter of less than 1.0 urn. Only the basts weight of the fine fiber layer
is presented. Collection efficiency of the backing material on OOP particles is
essentially zero. The data presented was produced by testing multiple thicknesses of two
O __
runs. The first run (-0-) had a basis weight of 8.4 gm/m . The second run (-Q-) had a
O
basis weight of 11.1 gm/m . Figure 5-8 presents collection efficiency for 0.3 um OOP
as a function of airflow velocity for a Gore-Tex (-0-) medium. It is apparent from this
data that greater than 90 percent collection efficiency of 0.3a m particles can be
achieved for these materials from fiber beds of only 10 to 12 gm/m* basis weight.
An attempt to produce a fine fiber media sample with the capability of collecting 0.3u m
OOP at an efficiency of 90 percent in a single sheet resulted in medium 4/10/76. This
O
material had a basis weight of 20.67 gm/m on a felt backing. Efficiency of collection
for 0.3u m DOP as a function of airflow velocity is as follows:
35
-------
.TJ—. :|^'-:|! " ;•; j^.ji-IJH-;:--:
:tT •;.; ~ :-jTv- :-*i.:'rH&;4nr'
-TTT ""^f^" •jti:ttr-J|^*1tr -
|: :'rri^H-;- fe 3% r^
••Hi! ' rip -;H. ' ;;••• •'' ::H...
i i •
]:~^" r : ~i •
:
i: r1 *•• ,: i
•:ri ••: — -trr-;-- • •*-•-^rirf r r - 7
v..i;-^: "^i '
/
Number of Needle Holes per Inch (6.45 cm ) *41 Needle
Figure 5-6. Effect of Needle Holes on Efficiency
36
-------
Table 5-2. Physical Data
Sample
1 (9/18)
1 + 2
1 +2+3
1 +2+3+4
Sub 4, 5, 6
Sub 7, 8
Sub 9, 10
4
4A
5
5A
6
6A
7
7A
8
8A
9
9A
10
10A
Permeability
3, . / 2
m /min/m
@ 1 .27 cm H20
6.64
3.17
1.93
1.51
130.36
116.71
99.95
7.76
4.10
12.10
4.65
5.05
3.14
20.11
5.68
5.35
2.98
12.41
4.44
6.95
3.32
Pore Size
(micrometer average)
-
-
-
-
-
-
346.4
225
-
268
-
202
-
262
-
204
-
223
-
146
-
Basis weight
*)
(gm/m )
-
-
-
-
-
-
-
306,125
-
285.87
-
332.71
-
270.89
-
310
-
280.96
-
311.65
—
37
-------
Table 5-3. Physical Data
Sample
4
5
6
7
8
9
10
9&10
Backing
*
Strength Dry
(Newton/5 cm strip)
154
147
183
167
168
137
137
:
^=^^=^^^=
wire
felt
wire
felt
wire
felt
wire
felt
wire
felt
wire
felt
wire
felt
wire
felt
Mullen Burst
(Pascal)
1.37xl06
1.37xl06
1.37x106
1.37xl06
1.37xl06
1.37xl06
9.85 xlO5
1.15xl06
l.OSxlO6
1.02xl06
1.02xl06
l.OSxlO6
1.21 xlO6
1.06xl06
9.81 x 105
9.58 x 105
Thickness
(Average cm)
-ss===^nMia
0.332
0.317
0.317
0.341
0.299
0.309
0.265
0.265
0.298
0.258
0.258
38
-------
^-- Data 8-26-75-
o= 26.B mm/tec i ! :
= 1 rnTFT.TTTITr! •
;:: i i-ii •!: f i-j
{ : i i
/jec~~rT~| ! i i
:TrrrrrT>-cT:-Tr
1 • : : -I : ! •• • • ; : : • : I i : i :
I T -:•:.::!'-:; i :!!
j- Basis Weight; = .11 '.\ gm/n? per sfeef j:
I t* ' i • I .' I ' . | . I T " ) ! » 1 i. ' ( *
U-L'-t V'-1-
?.l±n V • r
'• '"Calculated ).
•:: ; • j i 11 • i i • !-M i ; .-
;.::!; V i l : J : : i : :
i-:-i. i ! Vpl :-t I T ;.:':.
\T:u2r?frft nirt/sB
• f . -^ It « • « I
99.99
10 20 30 40 50 60 70 BO 90 100 110 120 130 140
Basis Weight gm/m
Figure 5-7. Penetration as a Function of Basis Weight
39
-------
£T
O
a
E
=1
«
.
O
£
fr 40
c
O
"u 30
c
20
10
~]
1 Layer/ 11.1 gm/m
/
2 Layers, 22.2 gm/m'
2 Layers, 16.8 gm/m
Fine Fibers
Fine Fibers
100
90
80 __
70
60
50
60 80 100 120
Airflow Velocity (mm/sec)
160
-------
Table 5-4. OOP Efficiency of Medium (4/10/76)
Airflow Velocity
mm/sec
26.8
53.5
71.1
142.2
Paper Backing DOP
Efficiency %
92
88
92.7
90
Felt Backing DOP
Efficiency %
90
82
88
85
This fine fiber material had an apparent fiber diameter larger than medium sample (1/26/76),
O
as indicated by the basis weight of about 20 gm/m with a DOP efficiency of approximately
90 percent. The earlier results indicated that the basis weight should have been about
2
10 gm/m .
Two additional samples were produced to have a target DOP efficiency of 90 percent.
O
One of these, medium sample 5/14/76, had a basis weight of 3.9 gm/m and a DOP
efficiency of 91.8 percent. The other, medium sample 5/17/76, had a basis weight of
O
0.5 gm/m and a OOP efficiency of 90 percent.
5.2
SEM Analysis
During Phase I, scanning electron micrographs (SEM) were made of various fine fiber samples
to assist in relating basis weight to fiber diameter.
Scanning electron photomicrographs of the fine fibers produced for the first run of media
samples (8/26/75) were made at 3K magnification. Two samples were photographed with
five pictures taken of each at random locations. The fiber diameter varied from about
0.1 urn to about lOfi m. Our analysis indicated that the average fiber diameter of one
sample was 2.02 fz m and of the other sample 1.82 ji m. Figure 5-9 shows two of the
pictures taken. These photographs show clumping of fibers which tends to make the fibers
behave as though they were larger in diameter. Fiber diameters were measured with a
scale in lines (3) as shown on the sketch on Figure 5-10. Each fiber intersecting a line
was measured and the results averaged.
41
-------
0.3 cm = 1
Basis Weight = 150 gm/rn ft 90 % DQP Efficiency
Figure 5-9. SEM Photomicrograph of Fine Fibers (#8/26/75)
42
-------
Up
SEM
Photo
Across
Diagonal
Figure 5-10. Measurement Technique Used to Estimate Average
Fiber Diameter
43
-------
Results from this measurement differ from the OOP tests and theoretical analysis. The DOP
efficiency as a function of basis weight curve (Figure 5-1) indicated an average diameter
close to 3 um; while the analysis from photographs indicated an average diameter closer
to 2 u m. Calculations predict a fiber diameter of about 2.5 a m for 90 percent DOP
efficiency. (See Figure 4-3.) This difference may be attributed to the difficulty of
determining the effective diameter of clumps of fiber and to the filtration effects caused
by the range from 0.1 u m to 10am of the actual fiber diameter. Considering the
range of fiber diameters seen in the photographs, a difference of only one micrometer is
good agreement.
Scanning electron micrographs (SEM) were made of both sides of a piece of fine fiber
medium (9/18/75). Figure 5-11 shows a typical picture taken on one side of this material
and Figure 5-12 shows the other side. The average diameter of fibers from Figure 5-11
was determined to be 1.24 um. The average fiber diameter of the side shown on
Figure 5-12 was 0.98u m. The fibers shown in Figure 5-11 appear to lie essentially in
one direction while those in Figure 5-12 seem more randomly oriented. This results from
the way in which the fibers are laid down. Fibers from Figure 5-12 are on the upstream
side during fabrication and contain more fiber ends. This may also explain the apparent
smaller average fiber diameter seen in Figure 5-12. This medium would achieve an
o
efficiency of 90 percent collection of DOP with a basis weight of 100 gm/m . Theoretical
analysis indicates that a uniform bed of 2.0Mm fibers would achieve a collection
2
efficiency for 0.3 um DOP of 90 percent with a basis weight of 100 gm/m . Once again,
considering the difficulties of measuring clumped fibers and the range of fiber size present,
this is good agreement with theory.
Fine fiber media samples designated (1/26/76) were produced in two runs. One of the
n
samples had a basis weight of 8.4 gm/m and a DOP efficiency of 85.5 percent. The
ty
other had a basis weight of 11.1 gm/m and a DOP efficiency of 95.8 percent. Figure 5-7
shows efficiency as a function of basis weight for this material. As seen from the curve
on Figure 5-7, this material should exhibit 90 percent DOP efficiency with a basis
weight of 11 gm/m .
Scanning electron photomicrographs were made for these materials. Figure 5-13 presents
two photographs of the 8.4 gm/m basis weight material magnified 5,000 times. Figure 5-14
presents a similar photograph of the 11.1 gm/m basis weight material. Gore-Tex filter
44
-------
Basis Weight = 100 gm/m2 • 90% DO? Efficiency
Figure 5-1 1 . Downstream Side of Media (9/18/75)
[-«- 0.3 cm = 1 .Oum
Basis Weight = 100 gm/m2 ^ 90% OOP Efficiency
Figure 5-12. Upstream Side of Media (9/18/75)
45
-------
Magnification 5 K
5 mm = 1 \i m
Basis Weight = 11 gm/m for 90% DQP Efficiency
Figure 5-13. SEM Photomicrograph of Fiber Bed (1/16/76)
(8.4 gm/m2 Basis Weight)
46
-------
Magnification 5 K
*\ [+— 5 mm = 1/im
Basis Weight = 1 1 gm/m2 for 90% OOP Efficiency
Figure 5-14. SEM Photomicrograph of Fiber Bed (1/26/76) (11 .1 gm/m2 Basis Weight)
47
-------
material is shown in Figure 5-15 at the same magnification. These photographs reveal the
extremely fine fibers present in all three materials. They also confirm the results predicted
from theory for fine fiber collection. The average fiber size is < 1 .Oym and, as shown on
Figure 5-7, filtration performance as a function of basis weight is in agreement with
theory for fiber size < 1.0 u m. Theory predicts a fiber diameter of 0.57^m for a uniform
bed of fibers achieving 90 percent OOP efficiency with a basis weight of 11 gm/m .
(See Figure 4-3.)
The following media samples all had efficiencies of approximately 90 percent collection
of 0.3 p m DO P. Medium (4/10/76) had a basis weight of 20.6 gm/m2. Medium (5/14/76)
had a basis weight of 3.9 gm/m . Medium 5/17/76 had a basis weight of 0.5 gm/m .
All three of these samples, produced from the same basic material, perform approximately
the same (90 percent OOP efficiency). A likely explanation for their different basis
weights is that there is a difference in their average fiber diameter. A series of SEM
photomicrographs were made to illustrate this difference in fiber diameter. Figure 5-16,
5-17 and 5-18 were taken at 5K magnification and show the three samples in descending
order of basis weight. (This should also be their descending order of average fiber diameter.)
This change in fiber diameter can be seen in the photograph even though its effect is
masked by the presence of some filming of material in sample (4/10/76) and the nodules
seen in all the pictures. The Figures 5-19 and 5-20 were taken at IK magnification and
the difference in fiber diameter is readily apparent. Figure 5-20 shows a piece of
exposed backing fiber through a small opening in the fine fiber face. Figure 5-21 was
taken at 2K because the fibers were not easily seen at IK. Figures 5-22 and 5-23 provide
the best illustration of the difference. They show the largest (4/10/76) and smallest
(5/17/76) basis weight (fiber diameter) material at 200X magnification. Figure 5-24
illustrates the backing material at 200X.
Figure 5-25 shows a view of the cut edge of sample (5/17/76) taken at 400X magnification.
In this picture, the bottom surface is the fine fiber layer. Figure 5-26 shows the back
side (inside surface) of the fine fiber layer at 5K magnification. The picture was taken
through an opening in the cut edge of the sample. The calculations shown on Figure 4-3
were used to determine the average diameters shown on the SEM photomicrographs.
48
-------
Magnification 5 K
- M U -
5 mm =
Figure 5-15. SEM Photomicrograph of Gore-Tex Filter Material
49
-------
mm =
Figure 5-16.
5K Photomicrograph of Media Sample (4/10/76)
Basis Weight = 20.6g/m2
Calculated Average Fiber Diameter = 0.85
m
Hh-
5 mm = lju m
Figure 5-17. 5K Photomicrograph of Media Sample (5/14/76)
Basis Weight = 3.9 gm/m2
Calculated Average Fiber Diameter = 0.3
m
50
-------
HK
5 mm - 1 u m
Figure 5-18. 5K Photomicrograph of Media Sample (5/17/76)
Basis Weight = 0.5 gm/m
Calculated Average Fiber Diameter = 0.1 1 n m
1 mm = 1 u
m
Figure 5-19. 1 K Photomicrograph of Media Sample (4/10/76)
Basis Weight = 20.6 gm/n/
Calculated Average Fiber Diameter = 0.85um
51
-------
1 mm = 1 U
m
Figure 5-20. 1 K Photomicrograph of Media Sample (5/14/76)
Basis Weight = 3.9 gm/m2
Calculated Average Fiber Diameter = 0.35U m
mm
= lu
m
Figure 5-21. 2K Photomicrograph of Media Sample (5/17/76)
Basis Weight = 0.5 gm/m2
Calculated Average Fiber Diameter = 0.11 um
52
-------
4 mm = 20
m
Figure 5-22 200X Photomicrograph of Media Sample
Basis Weight = 20.6 g/m2
Calculated Average Fiber Diameter = 0.85
4 mm = 20 (I m
Figure 5-23. 200X Photomicrograph of Media Sample
Basis Weight = 0.5 g/m2
Calculated Average Fiber Diameter = 0.11 Mm
53
-------
4 mm = 20 Urn
Figure 5-24. 200X Photomicrograph of Media Sample Backing
54
-------
4 mm = 1 0 u m
Backing Media Surface
Total Media
Thickness
0.14 mm
Fine Fiber Surface
Figure 5-25. 400X Edge View of Media Sample (5/17/76)
5 mm = 1 a m
Figure 5-26.
5K Photomicrograph of Media Sample (5/17/76)
(View of lower edge in Figure 5-25)
55
-------
5.3 Dust Loading Tests
The third major category of Phase I tests was designed to evaluate the cleanability of
various filter media by simulating pulse-jet performance. This testing was accomplished
in a flat-sheet pulse jet test rig. Figure 5-27 is a simplified sketch of the apparatus. A
photograph of the test set-up is shown in Figure 5-28. These dust loading tests allowed
us to generate curves of pressure drop as a function of time tor comparative evaluation
of various media.
Initial tests were designed to establish baseline performance of standard bag house media.
These early tests were attempted at high air-to-cloth ratios in order to accelerate the
tests. After the first few tests, we reduced the air-to-cloth ratio from 101.6 mm/sec to
50.8 mm/sec.
Standard AC Fine test dust was used in these tests. A particle size distribution showing
the tolerance band for AC Fine test dust is included on Figure 5-29.
The following is a short description of each test conducted in the flat-sheet test rig.
Test No. 1
A polyester sateen medium sample was tested under the following conditions:
Air-to-Cloth Ratio = 101.6 mm/sec
2
Dust Feed Concentration = 67.2 mg/m
(AC Fine)
Cleaning Pulse Pressure = 413.4 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 57 sec
Initial pressure drop across the medium was 25.4 mm K^O. The test was terminated when
the pressure drop reached 254 mm h^O. Total time of the test was 21.61 minutes. Residual
dust loading, the weight per unit area of dust remaining on the media sample, was 6.952
f\
gm/m . Overall dust loading is the weight of dust collected on the sample, plus the
56
-------
Pressure Drop
Mon itor
Air Inlet
and Dust
Feed
Wright Dust
Feeder
Pulse Cleaning
Venturi
Flat-Sheer
Media Holder
To Absolute Filter
Dust Hopper
Figure 5-27. Flat Sheet Pulse Jet Test Rig
-------
Absolute Pilfer
Pulse Control
Filter Holder
Compressed
Air Line
Surge Tanks
Dust Feeder
Dust Hopper
Figure 5-28. Flat-Sheet Pulse-Jet Cleaning Test Rig
58
-------
UJ
N
W)
5
2
UJ
-J
a*
Silica dull. IXI.65 a-n/m3
r^-:-:.:^---^
rsrrrJ-r- - - l :~yJr
i r^ — -•!•-•.•
- '.TnT"''"""'"'' ' -Jr t
DONALDSON CO. INC
RESEARCH DIVISION
DATE BY
FILE
II U
PARTICLE DIAMETER, microri
I I III I II'.MI'IIMIIMII.-l I JJ.I' « HIM! l«
I U I • • « I • 1
Figure 5-29. Particle Size Distribution of AC Fine Test Dust
-------
weight of dust collected upstream of the sample. In this test, overall dust loading was
7.856 gm/m2. Efficiency is calculated by dividing the weight of dust collected upstream
(on media sample, in the hopper and upstream air ducts) by the weight collected upstream
plus the weight collected on the downstream absolute (dust that passed through the test
medium). For this test, efficiency was 71.1 percent. Only a small amount of dust was
removed by the cleaning pulse.
Test No. 2
Test No. 2 was intended to duplicate Test No. 1. A second polyester sateen medium
sample was tested to the following;
A?r-to-Cloth Ratio = 101.6 mm/sec
2
Dust Feed Concentration = 86.4 mg/m
(AC Fine)
Cleaning Pulse FVessure = 413.4 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 57 sec
Initial pressure drop was 28 mm HjO. The test was terminated when pressure drop
reached 254 mm HLO. Total time to reach this pressure drop was 21.5 minutes.
rt
Residual Dust Loading = 7.029 gm/m
Overall Dust Loading = 8.524 gm/m
Efficiency = 70.4 percent
Again, overall dust loading is only slightly larger than residual dust loading, indicating
that most of the dust stayed on the filter medium. This test essentially repeated the
performance of Test No. 1.
Test No. 3
(R)
Donaldson Company standard medium DURALIFE w 11 was selected for this test under the
following parameters:
DURALIFE is a registered trademark of Donaldson Company, Inc., Mpls., MN 55440
60
-------
Air-to-Cloth Ratio = 101.6 mm/sec
-------
Initial pressure drop was about 10 mm HjO. The test was terminated after 104 minutes
when pressure drop reached 254 mm hLO. During the first half of the test, the dust feeder
was malfunctioning causing a low dust feed rate. After this was corrected, the pressure
drop increased with time at approximately a linear rate until the end of the test.
2
Residual Dust Loading = 6.34 gm/m
O
Overall Dust Loading = 45.0 gm/m
Efficiency = 94.37 percent
Two differences between Test No. 4 and No. 3 are the increased efficiency in Test No. 4
and the lower residual dust loading, indicating that a relatively large weight fraction of
the dust fed was removed from the medium by the cleaning pulses. A reasonable
explanation for these differences is that the fine dust fraction remained on the medium.
This could cause both the high pressure drop for a small residual dust loading and the
increased efficiency.
Test No. 5
Polyester sateen was used in this test at higher dust feeding rates. Test rig parameters
were:
Air-to-Cloth Ratio = 101.6 mm/sec
Q
Dust Feed Concentration = 273.5mg/m
(AC Fine)
Cleaning Pulse Pressure = 413.4 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
Initial pressure drop was 25 mm r^O. A pressure drop of 254 mm H«O was reached after
6.0 minutes. With pressure drop at 254 mm h^O, the dust screw was shut off so no
additional dust was fed. Two cleaning pulses did not reduce the pressure drop significantly,
A solenoid-operated relief valve downstream of the absolute filter was turned on, to open
when the cleaning pulse valve operated. This also had little effect on the pressure drop.
Cleaning pulse pressure was then set at 551 K Pa. Pulsing at this pressure reduced the
medium pressure drop by 56 mm h^O. The dust feeder injection air which had been on
62
-------
during these tests without dust feed was shut off and the system pulsed at 551 K Pa. This
reduced pressure drop an additional 114 mm HjO to a value of 89 mm hLO. At these
settings the dust feed was started again. After 4.58 additional minutes of operation,
pressure drop reached 254 mm HjO and the test was terminated. Total dust feeding time
was 10.50 minutes.
o
Residual Dust Loading = 10.16gm/m
Overall Dust Loading = 15.82gm/m3
Efficiency = 89.87 percent
Test No. 6
A polyester sateen medium sample was installed in the test rig at the following settings:
Air-fo-Cloth Ratio = 101.6 mm/sec
o
Dust Feed Concentration = 247.6 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
The downstream solenoid-operated relief valve was connected to operate with the
cleaning pulse solenoid for this test. Full scale pressure drop of 254 mm HjO was
reached in 5.5 minutes. At this time the dust feed and dust feeder air were shut off and
the cleaning pulses allowed to continue. After 10 pulses, the medium pressure drop was
reduced only 16 mm HLO. In order to examine the effects of different cleaning pulse
pressure settings, only the filter medium was removed for the next test. Residual dust
loading from Test No. 6 was 7.82 gm/m . The efficiency and overall dust loading were
not determined.
Test No. 7
Test conditions for Test No. 7 were the same as for No. 6 except that the cleaning pulse
pressure was cut in half to 275.6 K Pa. Test rig settings for the polyester sateen medium
were:
63
-------
Air-to-Cloth Ratio = 101.6 mm/sec
o
Dust Feed Concentration = 247.6 mg/m
(AC Fine)
Cleaning Pulse Pressure = 275.6 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
With the solenoid relief valve in operation, it took 4.0 minutes to reach 254 mm h^O
pressure drop. Dust feed and dust feeder air were shut off and the 275.6 K Pa pulse
allowed to continue. This did not reduce the pressure drop. Increasing the cleaning
pressure to 413.4 K Pa had little effect on the pressure drop. When the cleaning pressure
was increased to 551.2 K Pa, the pressure drop across the media was reduced by 86 mm
o
HjO. Residual dust loading was 6.12 gm/m .
Test No. 8
A new sheet of polyester sateen was installed with the test rig settings as follows:
Air-to-Cloth Ratio = 101.6 mm/sec
q
Dust Feed Concentration = 247.6 mg/m
(AC Fine)
Cleaning Pulse Pressure = 413.4 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 25 sec
Pressure drop was allowed to rise to 254 mm HgO without pulsing. This occurred after
7.25 minutes. Dust feed and dust feeder air were turned off for pulsing. Pulsing at
413.4 K Pa reduced pressure drop to 226 mm HjO. Pulsing at 551.2 K Pa further reduced
pressure drop to 74 mm H^O. Pulse pressure was increased to 620 K Pa and additional
pulsing at this pressure lowered pressure drop to 47 mm HjO. Dust was fed again with no
pulsing until a pressure drop of 254 mm HjO was reached. This took 4.55 min. Pulsing
without dust feed at 620 K Pa lowered pressure drop to 57 mm HLO. This sequence of
feeding dust and then cleaning was continued to the end of the test. Cleaning-down
pressure drop as a function of time is shown in the following chart:
64
-------
Cumulative Dust Feeding
Time (min)
7.25
11.80
15.71
18.71
21.99
24.0
25.76
27.56
28.67
29.67
30.35
30.7
*
Cleaned Down FVessure Drop
(mm H2O)
47
57
76
89
127
162
185
188
198
203
215
227
235
* The last clean-down sequence was performed with the pulse interval shortened to one
pulse every 5 seconds rather than one every 25 seconds. This did not result in any
apparent improvement.
The time presented is the cumulative total dust feeding time. Between each cleaning
cycle the pressure drop was allowed to rise to 254 mm H«O. Residual dust loading was
2
16.5gm/m .
The same absolute filters were used for Tests 6, 7 and 8, so no efficiency data was
collected. Dust concentration was averaged for all three tests.
Test No. 9
For Test No. 9, the air-to-cloth ratio of the polyester sateen medium was reduced. The
following test rig settings were used:
65
-------
Air-to-C loth Ratio = 50. 8 mm/sec
2
Dust Feed Concentration = 513.5mg/m
(AC Fine)
Cleaning Pulse Pressure = 551 .2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 54 sec
The solenoid-operated relief valve was not used in this test. Pulsing took place at
intervals while dust feeding. Maximum pressure drop of 254 mm HgO was reached after
108.16 minutes.
2
Residual Dust Loading = 59.2 gm/m
O
Overall Dust Loading = 167.2 gm/m
Efficiency = 98 .66 percent
At this lower air-to-cloth ratio some improvement in both efficiency and cleaning was
noted.
Test No. 10
Dust feed concentration was reduced to the polyester sateen medium for Test No. 10.
The test rig settings were as follows:
Air-to-Cloth Ratio = 50 .8 mm/sec
q
Dust Feed Concentration = 259.1 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551 .2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 54 sec
A total of 288 minutes was required to reach a pressure drop of 254 mm HjO across the
medium.
2
Residual Dust Loading = 61 .1 gm/m
O
Overall Dust Loading = 223 .3 gm/m
Efficiency = 98.13 percent
66
-------
This test produced expected results based on performance from Test No. 9.
Test No. 11
This test was intended to duplicate Test No. 10; however, the dust feeder malfunctioned
during the test and the test was abandoned.
Test No. 12
A polyester sateen medium was tested with test rig settings as follows:
Air-to-Cloth Ratio = 50.8 mm/sec
Dust Feed Concentration = 327.2 mg/m3
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 53 sec
Maximum pressure drop of 254 mm H«O was reached after- 317.25 minutes.
2
Residual Dust Loading = 65.4gm/m
O
Overall Dust Loading = 311.8 gm/m
Efficiency = 98.52 percent
Overall dust loading included dust that was lying in the ducts upstream of the filter
media holder. This had not been included in previous tests. This additional dust plus
the increased time required to reach 254 mm HjO pressure drop contributed to the
increased overall dust loading from this test.
Test No. 13
Polyester sateen was tested again at the following test rig settings:
Air-to-Cloth Ratio = 50.8 mm/sec
o
Dust Feed Concentration = 484.7 mg/m
(AC Fine)
67
-------
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 53 sec
Maximum pressure drop of 254 mm HjO was reached after 435.16 minutes of dust feeding.
2
Residual Dust Loading = 82.1 gm/m
Overall Dust Loading = 642.2 gm/m
Efficiency = 99.75 percent
Several leaks in the test rig were discovered and repaired during the course of this test.
These repairs are possibly the reason for improved performance.
Test No. 14
The pulse duration was shortened for this test. A polyester sateen medium sample was
used with test rig settings as follows:
Air-to-Cloth Ratio = 45 mm/sec
2
Dust Feed Concentration < = 389.7 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 40 ms
Cleaning Pulse Interval = 53.5 sec
Full scale pressure drop of 254 mm HjO was reached after 40.43 minutes of operation.
2
Residual Dust Loading = 35.2 gm/m
2
Overall Dust Loading = 46.3 gm/m
Efficiency = 96.39 percent
Reducing the pulse duration lowered efficiency as well as life.
68
-------
Test No. 15
This test was abandoned because the dust feeder introduced a slug of dust which caused
a jump in pressure drop and settled out in the feeder tube.
Test No. 16
Prior to running this test, additional small leaks in the test rig were discovered and
eliminated. Also, the compressed airline delivering cleaning air to the solenoid valve was
replaced with a larger tube to ensure that maximum cleaning flow is delivered during the
cleaning pulse. A polyester sateen sample was installed and tested with the following
test rig settings:
Air-to-Cloth Ratio
Dust Feed Concentration
(AC Fine)
Cleaning Pulse Pressure
Cleaning Pulse Duration
Cleaning Pulse Interval
= 45 mm/sec
t
= 604.6 mg/nrT
= 551.2 K Pa
= 120 ms
= 53.5 sec
The test was terminated when pressure drop reached 254 mm HjO after 751 minutes.
During the test, dust was deposited in various parts of the system. For this test:
5.12952 gm collected in 25 mm dia feed tube
8.03000 gm collected in 150 mm dia tube
13.15952 gm total drop-out
9.509 gm collected from the upstream hopper
0.76023 gm collected on test medium
2.00596 gm collected on downstream absolute
12.27519 gm dust fed out including drop-out dust
69
-------
Ignoring the drop-out dust:
2
Residual Dust Loading = 45.4gm/m
O
Overall Dust Loading = 613gm/m
Efficiency = 83.65 percent
Dust Feed
(AC Fine)
o
Dust Feed Concentration = 1165.4mg/m
Including the drop-out dust:
2
Residual Dust Loading = 45.4gm/m
Overa 11 Dust Load ing = 1398.7 gm/m
Efficiency = 92.11 percent_
Dust Feed
(AC Fine)
o
Dust Feed Concentration = 2224.8 mg/m
2
Test filter media area is = 0.01675 m
FVevious test calculations have included the drop-out dust.
It is likely that the dust we have termed drop-out dust has settled in the tubes bacuase
of the low air velocity there. However, there is a possibility that some of it has been
blown back by the cleaning pulse. A Coulter Counter analysis of samples taken from
the 25 mm dia feed tube, from the 150 mm dia tube and from the hopper is presented in
Figure 5-30. This analysis shows that the drop-out dust tends to be a larger size fraction
that that which is collected in the hopper. In any case, the dust being collected by
the test filter media has a particle size distribution finer that AC Fine.
A plot of pressure drop across the test filter medium as a function of time is shown in
Figure 5-31. This curve shows the large difference between maximum pressure drop and
cleaned-down pressure drop. We have concluded the test when maximum pressure drop
reaches: 254 mm HgO. Using this definition for filter life, the length of the test is a
function of the dust feed rate since if the dust feed rate were reduced, the spread between
cleaned-down pressure drop and maximum pressure drop would also be reduced because
of the fixed time between these two extremes with each c leaning pulse.
70
-------
JS
(A
*
CLEAKABlg MEDIA BVHUU.T10* MHCH
O #1 Peed Tub* Duit Dropout
u #3 Scivcnt* Abiolut* Dropout
DONALDSON CO. INC
RESEARCH DIVISION
OATC '-30-76 BY ^
FILE
I I II I Mil'III UUIIUMIMIIIIIIIIIt
U I U I • t • I «
t I I I II 14
PARTICLE
DIAMETER, micrcnt
Figure 5-30. Media Cleanability Evaluation
-------
300
250
200
o
5
K)
O
100
50
Ji-*»:. : '" P-:
.
1 :.(::;•
''-fcr
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= 92.11%:
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- .. —,... ., —»-—»-—
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rr.t-- pnjj .1-- : - -1- ' . ^^~
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|V Cleaned Down
-
r' "
• _^r^ -4 ' - *
1
200 300 400 500 600
Time (minutes)
700
900 1000
Figure 5-31 . Pressure Drop as a Function of Time
-------
Test No. 17
A polyester sateen medium was tested under the following conditions:
Air-to-Cloth Ratio = 50.8 mm/sec
o
Dust Feed Concentration = 716 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
Initial pressure drop was 19 mm h^O. The test was terminated when pressure drop reached
254 mm HOO. Total time to reach this pressure drop was 188.58 minutes. Residual dust
. 2
loading, the weight per unit area of dust remaining on the media sample, was 29.8 gm/m .
Overall dust loading is the weight of dust collected on the sample, plus the weight of
o
dust collected upstream of the sample. In this test, overall dust loading was 391.4 gm/m .
Efficiency is calculated by dividing the weight of dust collected upstream (on media
sample, in the hopper and upstream air ducts) by the weight collected on the downstream
absolute (dust that passed through the test medium). For this test, efficiency was
95.1 percent.
Test No. 18
A polyester sateen medium sample was tested with the following test rig settings:
Air-te-Cloth Ratio = 50.8 mm/sec
3
Dust Feed Concentration = 710.6 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
Initial pressure drop was 13 mm HjO. Maximum pressure drop of 254 mm HjO was
reached after 366.25 minutes of operation.
reached after 366.25 minutes of operation.
73
-------
2
Residual Dust Loading = 44.0 gm/m
O
Overall Dust Loading = 741.0 gm/m
Efficiency = 93.42 percent
Test No. 19
A polyester sateen medium was tested at the following test rig settings:
Air-to-Cloth Ratio = 50.8 mm/sec
2
Dust Feed Concentration = 741.3 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
Initial pressure drop was 19 mm r^O. Maximum pressure drop of 254 mm HjO was
reached after 289 minutes.
2
Residual Dust Loading = 34.9 gm/m
2
Overall Dust Loading = 592.7 gm/m
Efficiency = 94.05 percent
Test No. 20
For this test, a felted dacron medium sample was used in the test rig with the following
test settings:
Air-to-Cloth Ratio = 50.8 mm/sec
o
Dust Feed Concentration = 734.5 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
74
-------
Initial pressure drop was 2.5 mm H2O. Thes test was terminated after 2117 minutes
(35.28 hours) because it appeared that the test could last for many more hours without
adding to our knowledge of its loading characteristics. Final pressure drop, just prior
to a cleaning pulse, was 123 mm H.O.
2
Residual Dust Loading = 94.9gm/m
Overall Dust Loading = 4732 gm/m
Efficiency = 99.85 percent
As expected, this test shows that felt at these relatively high air-to-cloth ratios and
in the pulse-jet cleaning mode performs better than polyester sateen.
Test No. 21
A felted dacron medium sample was again used in the test rig with the following test
rig settings:
Air-to-Cloth Ratio = 50.8 mm/sec
2
Dust Feed Concentration = 475.4 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
Initial pressure drop was 3.8 mm HjO. The test was terminated after 2271.6 minutes
(37.86 hours). Final pressure drop was 66 mm HjO.
2
Residual Dust Loading = 115.4 gm/m
Overall Dust Loading = 3278 gm/m
Efficiency = 99.59 percent
Tests No. 20 and No. 21 produced similar results except that the lower dust feeding rate
in Test No. 21 resulted in lower operating pressure drop.
75
-------
Test No. 22
This was the first test in which a sample of the experimental media was used. A fine
fiber havir
were used.
2
fiber having a basis weight of 11.1 gm/m was tested. The foMowing test rig settings
Air-to-Cloth Ratio = 50.8 mm/sec
Q
Dust Feed Concentration = 429.0 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
This medium has a collection efficiency of 95 percent when tested with DOP particles.
The initial pressure drop was 87.6 mm hUO. Pressure drop reached 254 mm hUO after
1972.2 minutes (32.87 hours), at which time the test was terminated.
2
Residual Dust Loading = 12.74 gm/m
Overa 11 Dust Load ing = 2578.6 gm/m
Efficiency = 99.9997 percent
We feel the relatively high initial pressure drop was caused by the low permeability
of this medium; however, other factors may have been involved. After this test, there
was a 10 mm wide band across the medium sample which appeared cleaner than the
rest of the sample. If this strip was not passing air, this could have contributed fo the
pressure drop. The low residual dust loading indicates that cleaning was good. The '.
downstream absolute filter gained only 0.00011 gm of dust which resulted in the very
high efficiency shown above.
Operating Pressure Drop Curve
Figure 5-32 shows operating pressure drop as a function of time for polyester sateen
(Test No. 18), felted dacron (Test No. 21), and tor the fine fiber sample (1/26/76)
rt
with basis weight 11.1 gm/m (Test No. 22). Operating pressure drop in this curve is
the pressure drop just prior to a cleaning pulse.
76
-------
AiMO-ClotK M«o = 50.8 mm.
wing! Pulse
: Poise
assure = 551
ning Pulse mteryal; = 55 5
l.Tgtrj/m', Test No. 22
20
Time (hours)
30
40
Figure 5-32. Operating Pressure Drop As a Function of Time
-------
Test No. 23
An experimental fine fiber medium (type 1/26/76) was tested. It had a basis weight of
fine fibers i
were used:
o
fine fibers of 8.4 gm/m . The following flat-sheet pulse-|et cleaning test rig settings
Air-to-Cloth Ratio = 50. 8 mm/sec
o
Dust Feed Concentration = 706.5 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551 .2 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 51 .43 hours. Pressure drop was 72.4 mm HO at the end
of the test.
9
Residual Dust Loading = 17.72 gm/m
Overall Dust Loading = 6644.8 gm/m
Efficiency = 99.9948 percent
DOP efficiency for this material was 75 percent at the test airflow velocity. Figure 5-33
shows a plot of pressure drop as a function of time for this test.
Test No. 24
An experimental media was tested. The backing for this medium consisted of a 3 denier
felt needle punched to a 10 x 10 scrim. Two layers of fine fibers produced (9/18/75)
were attached to the backing by sonic welding in a 2.5 cm square grid pattern. This
sample was tested for DOP efficiency and was 90 percent efficient in the collection of
DOP smoke. The following flat-sheet pulse jet cleaning test rig settings ware used:
Air-to-Cloth Ratio = 50.8 mm/sec
2
Dust Feed Concentration = 61 0.6 mg/m
(AC Fine)
Cleaning Pulse Pressure = 551 .2 K Pa
78
-------
250]
Test Dust = AC Fine
200
Cdiectlpn Effictency
»• r
Rcrffd F 50.8 mm/see
se Pressure = 55T .2 K Pa
se Duratteri
A!r-to-Clotf
Pu
Cledrifng Pu _ ..._._,_ ...-__
Cleaning Pulse Interval- & sec '
Q.
I
S
I
•6
I
o
Figure 5-33. Operating Pressure Drop As A Function of Time
-------
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 44.77 hours. Pressure drop was 124.5 mm HjO at the end
of the test.
«
Residual Dust Loading* = 251.6 gm/m
O
Overall Dust Loading = 4998.3 gm/m
Efficiency = 99.9998 percent
*Note that the residual dust loading is higher than in previous tests. This was caused by
an error in mounting the test sample in the test rig. The sample was installed backwards
resulting in the fine fiber side being downstream. Figure 5-34 presents a plot of pressure
drop as a function of time. The more rapid pressure drop rate of rise was probably caused
by loading of the exposed felt side.
Test No. 25
An experimental medium designated as No. 9A was tested. It consisted of a 3 denier
felt with one layer of fine fibers (9/18/76) needled to the felt at 200 ppsi. Between
these two layers was a 10 x 10 scrim. One additional layer of fine fibers (9/18/75) was
placed over the needled fine fiber layer and secured to it with Scotch SPRA-Mount
artist adhesive (Cat. No. 6065). The following flat-sheet pulse-jet cleaning test rig
settings were used:
Air-to-Cloth Ratio = 50.8 mm/sec
Dust Feed Concentration = 593.3mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
This test was terminated after 37.45 hours when pressure drop was 68.6 mm H2O.
80
-------
oo
250
O
CN
X
E
J.
a.
o
200
150
100
fc
Q.
O
50
.1. -
' ~T: f ._[""" 2*{!-:|" ""fr;""1 FTr""~ "
rfetSt -r :-} - " • : 5~ -.:... . :.,
TpstjNp^ ?4|rt'';" »': ' ":: 4... [ • ' • -| L__p-!_ , _...:___ . '_-._.'U-: —» -T
3 Penier Fefjt (10 x 10 ScrJm) Backing ,. S^S^SS?^ /
Tiwn idvAti PfnA Fik^r, »"o/iftS «;«n^- rAirfto-tioTh «««rio - w.q meryal =[$5-sac . i:;
Collectiojh EfRcIency = 99.9998%
For"
.- i "' :
..
P, Fin* Fiber Side Was
DownsfreonC
-| rrr -r^=f— - r tr— rnrpr r|rT:
r
—v
I
- .-.•
.J, . " .: •'
i§ ! si
: '
1
' " - :
1 ii: ' i:: -±'^
•'
•
i
10
15 20 25
Time (hours)
30
35
40
45
50
Figure 5-34. Operating Pressure Drop As a Function of Time
-------
At the end of the test:
2
Residual Dust Load ing = 34.6gm/m
Overall Dust Loading = 4077.9gm/m
Efficiency = 99.9999 percent
Media Sample No. 9A had a OOP efficiency of 83.5 percent at the test velocity.
Figure 5-35 shows a plot of pressure drop as a function of time for this test. Dust was fed
to the fine fiber side of this sample.
Following the test, the fine fiber layer appeared to have loosened from the backing but
had not developed any holes or come loose in the fixture clamping area.
Test No. 26
An experimental medium designated as No. IDA was tested.
It consisted of a 3 denier felt with two layers of fine fibers (9/18/75) needled to the felt
at 200 ppsi. Between the felt and the fine layer was a 10 x 10 scrim. One additional
layer of fine fibers (9/18/75) was placed over the needled fine fiber layer and secured
to it with Scotch SPRA-Mount Artist adhesive (Cat. No. 6065). The following flat-sheet
pulse-jet cleaning test rig settings were used.
Air-to-Cloth Ratio =50.8 mm/sec
2 3
Dust Feed Concentration = 656.5m/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 36.87 hours, when the pressure drop had reached
92.7mm H2O.
2
Residual Dust Loading = 51.05 gm/m
2
Overall Dust Loading = 4426.5 gm/m
Efficiency = 99.9836 percent
82
-------
00
. i 1 *T"",!-.- *,:'„, ,.
: • ••£ ..." - '•' I . ; .
F-.a-.r-r
15 • 20 25
Time (hours)
Figure 5-35. Operating rVessure Drop As a Function of Time
-------
Media Sample 10A had a DOP efficiency of 85 percent at the test velocity. Figure 5-36
shows a plot of pressure drop as a function of time for this test.
Following the test, it was noted that the adhesive bonded fine fiber layer had ruptured
in several places.
Test No. 27
An experimental media (4/10/76) with dacron paper backing was tested. The fine fiber
layer had a basis weight of 20.67 gm/m and ° DOP efficiency at the test velocity of
88 percent. The following flat-sheet pulse-jet cleaning test rig settings were used:
Air-fo-Cloth Ratio = 50.8 mm/sec
2 o
Dust Feed Concentration = 671 m /m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 35.17 hours when pressure drop had reached 81.3 mm HLO.
2
Residual Dust Loading = 16.1 gm/m
Overall Dust Loading = 4316.8 gm/m
Efficiency = 99.9999 percent
This medium produced very good efficiency with excellent cleanability as evidenced by
low residual dust loading. Figure 5-37 presents a plot of operating pressure drop as a
function of time for the test.
Test No. 28
The experimental medium (4/10/76) with felt backing was tested. The fine fiber layer
had a basis weight of 22.57 gm/m and a DOP efficiency at the test velocity of 82 percent,
The following flat-shee* pulse-jet cleaning test rig settings were used:
84
-------
a
04
E
a.
8
a
S
ct
I
"o
10
15
20 25
Time (hours)
Figure 5-36. Operating Pressure Drop as a Function of Time
-------
I
o.
I
§
I
I
"o
I
O
200
100
i'C;
• ••4-
im
37: , *™t •""".:• . 'I .1 " " " "T* *7T. "i
• -i-J:_:, i , u::[_ ; ,--.;:
• r~n -r- ••^•T- ffh -=I;-T n- "'-
, !•
Ourdfif)n
-H
.-r»
— -4-:
.._L!3': 4": - 'J '•:-. L '
10
15 20 25
Time (hours)
30
J-.-1-:
35
40
Figure 5-37. Operating Pressure Drop as a Function of Time
-------
Air-to-Cloth Ratio = 50.8 mm/sec
Dust Feed Concentration = 662.9 m2/m3
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 36.02 hours. Pressure drop was 78.7 mm HLO at the end of
the test.
2
Residual Dust Loading = 63.2gm/m
Overall Dust Loading = 4363.4gm/m
Efficiency = 99.9015 percent
Pressure drop as a function of time for this test is plotted as Figure 5-38.
During this test, large pieces of the fine fiber layer were broken off from the test sheet.
Figure 5-39 shows a photograph of the test sheet after the test. Because of the loss of some
of the fine fiber layer, the residual dust loading value is incorrect.
Test No. 29
A sample of the lowest basis weight material (5/17/76) was installed in the flat-sheet test
rig. As in previous tests, standard AC Fine test dust was used. The following flat-sheet
pulse-jet test rig settings were used:
Air-to-Cloth Ratio = 50.8 mm/sec
«j
Dust Feed Concentration = 626.8mg/m
(AC Fine)
Cleaning Pulse Pressure = 551.2 K Pa
Cleaning Pulse Duration = 120ms
Cleaning Pulse Interval = 55 sec
The test was terminated after 75.2 hours. Pressure drop was 59.7 mm HjO at the end of
the test.
87
-------
00
00
o
cs
a.
o2
§
r " " ~=', "r- "
10
15 20 25
Time (hours)
35
40
Figure 5-38. Operating Pressure Drop as a Function of Time
-------
Test Sample from Test No. 28
Fine Fiber Medium (4/10/76) on Felt Backing
Figure 5-39. Fine Fiber Layer Broken from Felt Backing
89
-------
At the end of the test:
Residual Dust Loading
Overall Dust Loading
Efficiency
= 11.1 gm/r
m
= 8621 gm/m
= 99.9984 percent
This media sample had a DOP efficiency of 90 percent at the test velocity.
Figure 5-40 shows a plot of pressure drop as a function*of time for this test.
5.4
Pressure Drop Tests
Pressure drop was measured lor several fine fiber filter media samples. These samples all
had DOP efficiency values of approximately 90 percent. Using their measured basis
weights, their effective fiber diameter was determined from the curve on Figure 4-3.
This data is presented in Table 5-5 below and plotted on Figure 5-41.
Table 5-5. Clean Filter Pressure Drop
Test No.
Identification
22
24
26
27
29
—
—
—
—
DOP
Efficiency %
95
90
85
88
90
90
85
89
85
Basis Weight
gm/m
11.1
107.2
162
20.67
0.5
6.85
6.70
20.15
3.46
Effective Fiber
dia^t m
0.58
2.15
2.87
0.82
0.12
0.45
0.44
0.80
0.30
Pressure Drop
mm h^O
24.5
4.1
2.8
1.9
3.5
3.35
3.99
6.60
3.94
As can be seen on Figure 5-41, this data does not agree with the value predicted by
Langmuir's pressure drop equation. Langmuir's equation does predict pressure drop values
as low as the data for 20pm fibers. Data from Test No. 22 was higher than the predicted
90
-------
5 10
20
30
40 50
Time (hours)
60
70
80
Figure 5-40. Pressure Drop as a Function of Time
-------
Langmuir with Knudsen No. Correction
+ Kn &* - I)2 _^
4 (1 + KJ 1 +
For: UQ = 2.54 cm/sec
•UG = 1.8 x 10 gm/cm sec
X =0.0653um@20°C
X = Pressure Drop Data Points
Effective Fiber Diameter
Figure 5-41. Difference Between Actual and Predicted Pressure Drop
for Filters Capable of 90% Collection of 0.3 urn OOP
92
-------
value. Test No. 22 also indicated anomalously high pressure drop during dust feeding.
The theoretical curve is for a OOP efficiency of 90 percent and for filter beds of uniform
size fibers with solidity (e<) of 0.1. Several of these parameters are different in the
actual filter beds tested. These differences may explain the difference between theoretical
and actual &P; however, it seems unlikely because of the relatively large differences
seen. Fortunately, the actual pressure drop measured is less than the predicted value;
consequently, it does not present a problem in the sense of interfering with performance
as a practical filter system. For this reason and because the contract is not funded to
pursue an explanation for such differences, we cannot at this time attempt to seek an
explanation. We will, however, continue to collect this pressure drop data as
opportunities arise with new filter media samples.
93
-------
6.0 PLEATED CARTRIDGE LABORATORY TESTS
Laboratory testing was performed on pleated cartridges using fine fiber media in
Phase II. The tests consisted of dust loading in a Torit model pulse-jet air cleaner
and DOP penetration tests on individual cartridges before and after the dust tests.
The dust tests indicated high collection efficiencies on AC Fine test dust. Also, it
was found that 689 K Pa of cleaning pressure is desirable in order to attain
stabilized pressure drop during dust loading.
The DOP penetration tests were performed at air-to-cloth ratios from 10 mm/sec up
to 50 mm/sec both before and after the dust tests. The efficiencies were high and
there was no degradation in performance due to dust loading and pulse cleaning.
The following paragraphs describe these tests in detail.
6.1 Pleated Cartridge Dust Tests
Dust tests were performed using fine fiber media in a cylindrical pleated cartridge con-
figuration. Three pleated cartridge filters were installed into a Torit model TD pulse-jet
air cleaner. The objective of these tests was to determine pressure drop as a function
of air-to-cloth ratio and cleaning pulse pressure. Pulse duration was fixed at 120
milliseconds. Pulse interval was nominally 60 seconds so that one of the three
elements was pulsed once every 20 seconds. AC Fine test dust was also used for this
series of tests. The three element filter unit has a nominal airflow capacity of 28.3
nP/min and was operated at rated flow for this test sequence. Air-to-cloth ratio was
varied by changing the element configuration in terms of the pleat spacing and the
axial length of the cylindrical element. Pleat depth was 5 cm for all the tested
elements. The following table describes the element configuration.
95
-------
E lement Active Length (cm)
Number of Pleats
Filter Area (m2)
Air-to-Cloth Ratio (mm/sec)
10
53.3
286
15.48
20
53.3
143
7.74
35
28.7
151
4.42
50
26.9
113
3.09
In order to obtain a baseline for comparison, three standard production elements were
tested. Air-to-cloth ratio for the standard element tests was 9.25 mm/sec. Cleaning
pulse pressure was 413 K Pa with pulse duration of 120 ms. Cleaning pulse interval was
once every 58.2 seconds for each element or once every 19.4 seconds in the three
element system. Pressure drop as a function of time for this test is shown on Figure 6.1 .
This test was terminated after 35.32 hours. During the test, 52,992 grams of dust
were fed to the air cleaner. The dust collected on the absolute filter weighed 27.63
grams. This yielded an overall efficiency of 99.95 percent.
Three fine fiber elements were installed for testing at an air-to-cloth ratio of 10 mm/sec.
Cleaning pulse pressure was held at 413 K Pa with pulse duration of 120 ms. The cleaning
pulse interval was set so that each of the three elements were pulsed once every 58.2
seconds. This resulted in the three element system pulsing once every 19.4 seconds.
2
Pressure drop as a function of time for a dust feed rate of 812.2 mg/m , is shown on
Figure 6.1. During the 39.15 hours of this test, 54,194 grams of dust were fed to the
system. Only 0.05 grams of dust penetrated the system and were collected on the
absolute filter. This resulted in an overall efficiency of 99.9999 percent. As can be
seen from the curve at this pulse pressure and air-to-cloth ratio pressure drop, equilibrium
was not obtained.
Three new fine fiber elements were installed for tests at air-to-cloth ratio of 20 mm/sec.
o
Using AC Fine test dust at a concentration of 883 mg/m , the elements were allowed
96
-------
350
300
250
200
1 \
508 mm @ 39 hrs
50
O = Fine Fiber Elements
DOP = 96 - 98%
m = Standard Media
AC Fine test dust
Cleaning Pulse
Pressure = 413 K Pa
Duration = 120 ms
Interval = 58 sec
25 30 35
Time (Hours)
Figure 6-1 . Pressure Drop Life Characteristics
40
45
50
-------
to reach a pressure drop of 726 mm HLO at a cleaning pulse pressure of 413 K Pa. This
occurred after 23.5 hours of operation. Pulse duration was 120 ms and pulse interval
was 58 seconds or one pulse every 19 seconds for the three elements.
After completing this test at 413 K Pa, primary flow was reduced to a value resulting
in 25 mm HLO pressure drop.
Cleaning pressure was set to 689 K Pa and the elements were cleaned without dust feed-
's
ing. Following this, the primary flow was increased to 28.3 m min (rated flow) and the
unit was operated at a pulse pressure of 551 K Pa for 20 minutes without dust feeding.
Pressure drop was then 178 mm H«O. Dust feeding was started and continued for one
hour. At the end of the hour, pressure drop had risen to 193 mm HjO. Cleaning
pulse pressure was then increased to 689 K Pa and the unit was operated for one more
hour. At the end of this hour, pressure drop was reduced to 170 mm HLO. These
results indicated that by proper selection of cleaning pulse pressure, one can control
pressure drop while feeding dust. To obtain an indication of long term effects, opera-
tion was continued with cleaning pulse pressure set at 551 at K Pa. The test was
terminated after 46.4 additional hours of operation. Pressure drop had risen to 229 mm
HLO. This entire test sequence is plotted on Figure 6-2.
During the first 23.5 hours of the test with cleaning pulse pressure set at 413 K Pa,
35,252 grams of dust were fed to the system. The absolute filter collected 0.74 grams
which penetrated the elements. This resulted in an efficiency of 99.9979 percent.
During the final 46.4 hours of the test with cleaning pulse pressure set at 551 K Pa,
69,652 grams of dust were fed to the system. The absolute filter gained 0.39 grams
resulting in 99.9994 percent collection efficiency.
New fine fiber elements were installed for both tests at air-to-cloth ratios of 35 to 50
mm/sec. For these tests AC Fine test dust was fed to the elements at a concentration
2
of 883 mg/m . Pulse duration (120 ms) and interval (58 seconds or one pulse every
98
-------
726mm H20@ 23.5 hours
350
689 K Pa, Low Flow
No Dust Fed
551 K Pa
!= 99.9994%
Air-to-Cloth Ratio = 20 mm/sec
AC Fine Test Dust
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 58 sec
10
20
30 40 50 60 70
Time (hours) 883 mg/m3
Figure 6-2. Pressure Drop Life Characteristics
80
90
-------
19 seconds for the three elements) were the some as previous tests at air-to-cloth ratios
of 10 and 20 mm/sec. Both tests were initially run with a cleaning pulse pressure of
413 K Pa which was later increased to 551 K Pa, then 689 K Pa for the second and
third portion of the test.
Figure 6.3 shows operating pressure drop as a function of time for the initial test at
413 K Pa as well as the following test at 551 K Pa and the final test at 689 K Pa.
At the end of the 551 K Pa test, pressure drop was reduced by cleaning at 689 K Pa
with primary flow reduced to a level resulting in about 25 mm HLO without dust feed-
ing . This procedure reduced operating pressure drop to 254 mm hLO at rated flow.
The test was then continued at 689 K Pa. After 56.08 additional hours of operation,
pressure drop had risen to 330 mm H_). At this point the test was stopped. During
the test at 689 K Pa 84,120 grams of dust were fed to the system with 5.58 grams
penetrating the elements. This resulted in an overall efficiency for this portion of
the test of 99.9934 percent.
New elements were installed in a second test unit for tests at an air-to-cloth ratio of
50 mm/sec. Figure 6-4 shows operating pressure drop as a function of time for the
initial test at 413 K Pa as well as the following test at 551 K Pa, and the final test
at 689 K Pa.
At the end of the 551 K Pa test pressure drop was reduced by cleaning at 689 K Pa
with primary flow reduced to a level resulting in about 25 mm hLO without dust
feeding. This procedure reduced operating pressure drop to 157 mm hUO at rated
flow. The test was then continued at 689 K Pa. After 19.7 additional hours of
operation pressure drop had risen to 256.5 mm hLO. At this point the test was
stopped. During this test at 689 K Pa,29,618 grams of dust was fed to the system with
76.47 grams penetrating the elements. This resulted in an overall efficiency of
99.7418 percent.
100
-------
400
513mm H20@8.6hrs
551 K Pa, Low Flow
No Dust Fed
I 1
JJ = 99.923 %
551 K Pa
689 K Pa, Low Flow
No Dust Fed
689 K Pa
11=99.9934%
t? =99.983%
413 K Pa
Air-to-Cloth Ratio = 35 mm/sec
AC Fine Test Dust
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 58 sec
10
30
40
50
60
70
80
90
100
10
Time (Hours) @ 883 mg/m*
Figure 6-3. Pressure Drop Life Characteristics
-------
350
300
250
E 200
E
o.
Q
£
I
150
100
50
0
508 mm HjO® 1.72 hours
413 K Pa
551 K Pa Low Flow
No Dust Fed
=99.890%
689 K Pa
Tj = 99.7418%
•551 K Pa
364%
689 K Pa Low Flow
No Dust Fed
Air-to-Cloth Ratio = 50 mm/sec
AC Fine Test Dust
Cleaning Pulse Duration = 120 ms
Cleaning Pulse Interval = 58 sec
10
20
30
40
50
60
70
80
90
Time (hours) @ 883 mg/nT
Figure 6-4. Pressure Drop Life Characteristics
-------
During these tests the dust which passed the test elements was collected on an
absolute filter located downstream of the pulse Jet unit. For both the tests at
35 mm/sec and at 50 mm/sec air-to-cloth ratio, the dust collected in the absolute
filter was washed out and analyzed by Coulter Counter. The resulting particle size
distribution is plotted on Figure 6-5. The AC Fine feed dust particle size distribution
is also shown. Note that while the averaged particle size has been reduced, there
are still some relatively large particles present in the dust which passed the fine
fiber filter. This is an expected result for a barrier filter. Even though the mass
removal efficiency is very high, a few large particles can still penetrate the filter.
This is because a filter is a "probability" device and not a screen.
Tests at higher air-to-cloth ratios have shown a decrease in overall efficiency for
AC Fine test dust. Collection efficiency for AC Fine test dust is plotted on Figure
6-6 as a function of air-to-cloth ratio, with cleaning pulse pressure as a parameter.
This data indicates that collection efficiency for AC Fine test dust is a function of
air-to-cloth ratio. It further indicates that the fine fiber media can achieve the
same collection efficiency as standard media, but at a higher air-to-cloth ratio.
In these tests, fine fiber media can operate at 8 to 1 at the same efficiency as
standard media at 2 to 1 air-to-cloth ratio.
Also note that there appears to be little difference between efficiency obtained from
tests at different cleaning pulse pressure. This indicates that the changes in efficiency
are related to the primary flow velocity.
6.2 DOP Penetration Tests
Efficiency for collection of 0.3 U m DOP was measured before and after the dust
tests of the pleated elements. The following table presents the results of these tests:
103
-------
I M I 4 t I » t • J 1* I U • « I « I I t It
I I I«M
0Ab*Dlu*e Flltw from Eltmcnli Teited o»
4
-------
05tondord Media, 12 % OOP
AQOFirwFiberMedla. fir98% OOP
AC Fbw T«» Durt
99.9999
to 20 33
Alr-to-Cloth Ratio (mm/Me)
Figure 6-6. Efficiency as a Function of Air-to-Cloth Ratio
105
-------
Air-fo-Cloth Ratio
(mm/sec)
_.»
10
—
—
20
—
—
35
—
—
50
— —
Initial (Clean) DOP
Efficiency (%)
98.0
96.0
96.0
98.0
98.5
98.5
99.8
99.9
98.0
93.0
99.0
99.5
Post Dust Test
DOP Efficiency (%)
99.2
98.5
98.5
99.8
99.9
99.85
98.5
99.3
99.0
99.8
99.8
99.8
One element tested at air-to-cloth ratio of 50 mm/sec, when clean, had an anomalously
low DOP efficiency (93%). If the result for this element is ignored, the remainder of
the data suggests that DOP efficiency is only weakly influenced by air-to-cloth ratio.
As expected, DOP efficiency from a dirty filter is higher than from a clean filter because
the dust cake is providing some filtration.
The filter medium from which these elements were fabricated collected 85 to 90 percent
of DOP smoke in a flat sheet test, while pleated cartridge DOP results were > 98 percent.
Our tests to determine if the DOP machine was giving erroneous results indicate that
this difference is real.
A possible explanation for this improved efficiency is that in the pleated configura-
tion, a DOP particle approaches the medium at a shallow angle. This then requires
106
-------
that the particle alter direction within the medium to follow a given flow line.
This curved path is longer than a path straight through the medium. The longer
curved path effectively increases the thickness of the medium. See the sketch
below.
Media Thickness
Path length t 2 >
The reason this phenomenon is not more pronounced in standard media is that
standard media is considerably thicker than the fine fiber media and a curved path
length through it is proportionally closer to the path length straight through the
medium. See the sketch below.
Flow line
Path length t2 =
107
-------
7.0 FIELD TESTS
The purpose of the field tests was to demonstrate the performance of filter cartridges
made from fine fiber media on actual industrial emissions, which have a high
percentage of submicrometer particles. Two sites were selected: Cornelius
Company (welding fume emissions), and the Northern Malleable Iron Company
(magnesium oxide emissions). These tests were aimed at characterizing the
particles and determining the efficiency and life of the fine fiber filter cartridges.
The particulate characterization tests consisted of Coulter Counter analysis,
Andersen Cascade Impactor sampling, scanning electron micrographs, transmission
electron micrographs, solubility tests and x-ray dispersive radiation analysis. The
performance tests were directed at determining overall mass efficiency by means
of gravimetric sampling, fractional efficiency using an Andersen Cascade Impactor,
and filter loading and durability evaluations.
Tests results indicated that the particle size spectrum at both sites contained a high
percentage of submicrometer particles. According to the Andersen Cascade Impactor
data, particles below 2/i m were measured at over 65 percent for the welding fume
and over 53 percent for the magnesium oxide emission. The overall mass efficiency
of the fine fiber filters on each emission was high; 97.6 percent average for the
welding fume and 99.95 percent for the magnesium oxide fume.
A media failure occurred at the Northern Malleable site. The substrate media fatigued
and allowed dust to pass sometime between 408.6 hours and 539.6 hours of operation.
It is felt, however, that a stronger substrate media will solve this durability problem.
Subsequent to this failure, one of the filter units was run in the laboratory at an
accelerated cleaning pulse interval to determine if pulse cleaning affected the
durability of the media. DOP penetration tests indicated no media failure after
112,626 pulses per element. This is equivalent to 1877.1 hours of operating time
at the normal pulse interval.
The following paragraphs describe results of the field tests.
109
-------
7.1 Tests at Cornelius Company (Welding Fume Emission)
Field tests were started at Cornelius Company in March 1977- The emissions at this
site were from welding operations at individual welding tables.
Figure 7-1 illustrates an individual welding table. Air is drawn through rectangular
openings in the table and is routed through a duct to a large dust collector. The
fine fiber filter unit was fitted to one of the individual welding tables as shown
in Figure 7-2.
Figure 7-3 is a schematic illustration of the test setup. This filter unit was run at
o
an air-to-cloth ratio of 35 mm/sec and an airflow of 28.3 m /min. Figure 7-4
shows the pressure drop of this unit with clean filter elements. The pressure drop
for this system was monitored throughout the test program to obtain the projected
life or pressure drop versus time.
7.1 .1 Particulate Characterization -Welding Fume
The following analyses were performed to characterize the welding fume: Coulter
Counter, Andersen Cascade Impactor sampling, scanning electron microscopy,
transmission electron microscopy, solubility tests, and x-ray analysis.
The Coulter Counter analysis on this particulate material was inconclusive. One
analysis indicated a D50 of about 4u m, whereas, the other indicated about 99
percent of the sample below 4
Solubility tests were conducted on samples to determine the percentage of oil in
the emission. Both benzene and petroleum ether were used as solvents. It was
felt that a high percentage of the emission was organic or carbon based because the
steel was not degreased prior to welding. The results indicated that oil represented
20 to 50 percent of the sample, which e
-------
Figure 7-1 . Welding Table at Cornelius Company
-------
Figure 7-2. Installation at Cornelius Company - Welding Fume
112
-------
Cleaning Air
Supply
Welding Bench
Filter Element (3 used).
Cyclopac without
Element Used as
Spark Arrester
SystemAP
Qc Airflow
I
Flowmeter
\
Pump
Figure 7-3. Test Setup at Cornelius Company
-------
1000
Airflow (m /min)
Figure 7-4. Pressure Drop Characteristics Field Test Unit at
Cornelius Company
114
-------
An upstream duct sample was scanned with an x-ray dispersive radiation technique.
This scan indicated a low iron content in relation to bulk signal; consequently, it
was estimated that approximately 80 percent of the welding fume could be organic
or carbon base.
Samples of porticulate material were viewed under an optical microscope. The
majority of upstream particles appeared to be under I Mm in diameter. There also
were some larger (up to 20 Urn in diameter) spheric a I-shaped particles that were
apparently metallic. This shape indicated that these particles were generated with
a welding torch. The large number of small organic particles was a result of oil
contamination on the welded steel.
A six-stage Andersen dust sampler was used to sample the upstream duct. Table
7-1 presents the percent of emission in a given size range (Note: 56.1 percent of
the particles are below 0.3 Mm).
Table 7-1. Andersen Cascade Impactor Data for Cornelius Company - Upstream
Particle Size
Particle Size Range
(micrometer)
<0.3
0.3 - 1 .0
1.0-2.0
2.0-3.3
3.3 - 5.5
5.5 - 9.2
9.2 - 20.0
Upstream
% Per Size Range
56.10
4.53
4.64
2.51
4.68
9.71
17.83
Upstream
% Less Than Size
56.10
60.63
65.27
67.78
72.46
82.17
100.00
115
-------
Figure 7-5 presents photographs of the participate material, both upstream and down-
stream of the filter unit, collected on the fourth stage of the Andersen Cascade
impactor. The fourth stage of the Andersen Cascade impactor collects particles
ranging from 2.0 to 3.3 Mm. For the downstream sample, three stages were removed
to obtain weighable samples in a reasonable amount of time. Consequently, the
downstream fourth stage collected particles from 2.0 to 5.5 U m. As expected, the
upstream sample indicated the presence of some oil particles.
Both scanning electron micrographs and transmission electron micrographs confirmed
the existence of a high number of submicrometer particles in the welding fume.
Figure 7-6 presents an SEM micrograph, at IOK magnification, of the ambient
sample at the welding table. The 2.5 /j m spherical particle in the center of the
photomicrograph is undoubtedly a metal particle formed during the welding operation.
Figure 7-7 shows SEM micrographs of both upstream and downstream samples, at IOK
magnification.
Figure 7-8 is the same as Figure 7-7 except at 20K magnification.
Figure 7-9 presents SEM micrographs of the upstream sample of welding fume at IOK
and50K.
Figure 7-10 shows downstream samples at the same magnification. The space
between the white bars is 0.5 urn. One can readily see from these micrographs
that there are many particles around 0.05u m in diameter. The dark and rather
uniform circles in the Nuclepore membrane are holes which are all close to 0.4^m
in diameter.
Transmission election micrographs were also taken and are presented on Figures
7-11 and 7-12, at IOK and 50K, respectively. These micrographs indicate chains
116
-------
"* 5 K m
Downstream (2.0-5.5 M m)
5 JU m
Upstream (2.0 - 3.3 U m)
Figure 7-5. 820 Magnification of Welding Fume - Stage 4 of Andersen Sampler (Downstream
Sample Taken with 3 Stages Removed)
-------
Figure 7-6. 10K SEM Micrograph of Ambient Welding Fume
118
-------
-o
m
m
Downstream
Upstream
Figure 7-7. 10K SEM Micrograph of Upstream and Downstream Samples of
Welding Fume
-------
— 1 (J m
Downstream
Upstream
Figure 7-8. 20K SEM Micrograph of Upstream and Downstream Samples of
Welding Fume
-------
Cornelius Upstream
IO,OOOX
Cornelius Upstream
50,OOOX
Figure 7-9. SEM Micrographs of Welding Fume - Upsrream
121
-------
Cornelius Downstream
10,OOOX
Cornelius Downstream
50,OOOX
Figure 7-10. SEM Micrographs of Welding Fume - Downstream
122
-------
0 -* /'" v
•% 1^
Urn
Downstream
U m
Upstream
Figure 7-11. 'OK TEM Micrograph of Upstream and Downstream Samples of Welding Fume
-------
CO
( *-«— 0.1 urn
Downstream
0.1 a m
Upstream
Figure 7-12. 50K TEM Micrograph of Upstream and Downstream Samples of Welding
Fume
-------
of portlculates or flocculates In both upstream and downstream samples. Again,
many submicrometer particles are present in the samples.
7.1.2 Performance Tests - Cornelius Company
The performance tests of the fine fiber cartridge filter unit of Cornelius Company
involved the following: DOP penetration tests of clean cartridges, overall mass
efficiency, fractional efficiency, filter dust loading and durability tests. The filter
unit at Cornelius Company was operated at an air-to-cloth ratio of 35 mm/sec for
all field performance tests.
The filter cartridges were tested for DOP efficiency prior to field tests. Table 7-2
presents the efficiency on 0.3 U m diameter DOP particles. The tests were run at
an air-to-cloth ratio of 50 mm/sec.
Gravimetric samples were taken simultaneously, upstream and downstream of the filter
unit, to determine the overall mass efficiency which is presented in Table 7-3.
(The average of five different efficiencies is 97.6 percent.) Also presented in this
table is the upstream concentration. The concentration of particles at this site was
relatively low (less than 1.0 mg/m j .
Fractional efficiency data was obtained using an Andersen Cascade impactor.
Because of the low downstream concentrations, only three of the six stages were used
so that weigtable samples could be obtained. Only one Andersen dust sampler was
used for these tests so the upstream and downstream samples were not concurrent.
Table 7-4 presents the fractional efficiency data obtained at Cornelius Company.
125
-------
Table 7-2. DOP Efficiency of Cartridges for Field
Test at Cornelius Company
Element
No.
Fl
F3
F5
Efficiency on
0.3 m dia. DOP
85%
95
80
Air-to-Cloth Ratio
DOP Test
50 mm/sec
50
50
Field Test
35 mm/sec
35
35
Table 7-3. Overall Mass Efficiency for Field
Test at Cornelius Company
Upstream Concentration
(mg/rrQ
Overall Mass Efficiency
0.666
0.715
0.599
0.600
0.916
97.6%
99.3
97.0
95.7
98.4
97.6% average
Table 7-4. Fractional Efficiency for Field
Test at Cornelius Company
Particle Size Range
(micrometers)
<0.3
0.3-2.0
2.0-5.5
5.5 - 20.0
Efficiency
(%)
91.7%
87.1
79.8
95.0
126
-------
The pressure drop and redia durability of the filter unit were monitored throughout
the field tests. The pressure drop of the unit rose from 182.5 mm HjO to 342.9 mm
H2O and remained stable. The filter media maintained its integrity throughout the
test. Figure 7-13 presents a curve of operating pressure drop versus time.
These field tests were terminated on 15 July 1977 after 87.2 hours of operation at
the request of Cornelius Company. The request was prompted by their need for the
floor space that the filter unit occupied. Both the accumulated operating time and
the dust loading were quite low during the test period because of infrequent use of
the welding table. Consequently, the premature removal of this unit did not
pose any problem, and the sampling tests at this site were accomplished. A photo-
graph of a dirty element from the test side next to a clean element is shown on
Figure 7-14. The contaminant is similar in appearance to soot.
Laboratory tests were conducted on the filter unit which was removed from Cornelius
Company to determine the durability of the filter medium with regard to cleaning
pressure. These tests consisted of operating the unit at an accelerated cleaning
pulse interval; and periodically measuring the DOP penetration across the unit. The
inlet temperature was ambient and no dust was fed. The unit was run at an air-to-
cloth ratio of 35 mm/sec and a cleaning pressure of 689 K Pa. To accelerate the
test, each element was pulsed at a rate of one element every five seconds, instead
of 20 seconds. DOP penetration tests indicated no media failure after 112,626
cleaning pulses per element (equivalent to 1877.1 hours of operation time for a
filter unit with each element being cleaned every 20 seconds).
Table 7-5 presents the DOP penetration data token during the tests. Initially, DOP
penetration was at 0.50 percent, with 5,706 pulses per element, which includes
the number of pulses accumulated from tests at Cornelius Company. On 30 August
1977, DOP penetration was 1.9 percent after 112,623 pulses per element. The
filter unit pressure drop decreased from 312.42 mm HjO to 279.40 mm HjO. The
increase in DOP penetration and the decrease in pressure drop can both be attributed
127
-------
400
O
CM
1
0.
O
Q
I
300
200
cr
fi.
O
100
20
40
60
Time (hours)
80
100
120
Figure 7-13.'. Operating Pressure Drop as a Function of Time (Cornelius Company)
128
-------
ro
O
Figure 7-14. Dirty versus Clean Filter Elements -
Cornelius Company - Welding Fume
-------
Table 7-5. Pulse-Cleaning Durability Tests
Date
8/5/77
8/8/77
8/9/77
8/10/77
8/11/77
*8/12/77
8/12/77
8/15/77
8/16/77
8/18/77
8/21/77
8/23/77
8/30/77
Accumulated
Pulses per Element
5,706
6,186
6,690
7,194
8,634
9,954
10,410
27,714
32,274
43,602
66.642
84,042
112,626
Equivalent
Operating Time (hrs)
95.1
103.1
111.5
119.9
143.9
165.9
173.5
461.9
537.9
726.7
1110.7
1400.7
1877.1
Unit Pressure
Drop (mm HjO)
312.42
299.72
322.58
317.50
309.88
—
304.80
284.48
287.02
287.02
287.02
287.02
279.40
DCP
Penetration (%)
0.50
0.30
0.30
0.32
0.46
—
0.64
.20
.50
.50
.60
.50
.90
* Increased pulse interval from once every 20 seconds to once every 5 seconds.
130
-------
Table 7-6. Andersen Cascade Impactor Data for
Northern Malleable - Upstream Particle Size
Particle Size Range
(micrometers)
<0.3
0.3-1.0
1.0-2.0
2.0-3.3
3.3-5.5
5.5 - 9.2
9.2 - 20.0
Upstream
% Per Size Range
13.80
11.06
28.83
19.92
12.03
8.40
5.97
Upstream
% Less Than Size
13.80
24.86
53.69
73.61
85.64
94.03
100.00
131
-------
to the cleaning of the dust cake from the elements that accumulated during the tests
at Cornelius Company.
Trese tests were prompted by an element failure at an air-to-cloth ratio of 25 mm/sec,
at Northern Malleable Iron Company. However, the damaged elements were not only
subjected to the cleaning pulses but also to dust loading and an inlet temperature of
I50°F. These elements had a greater pressure drop across the media due to the dust
loading, resulting in greater deflection and stresses in the media during pulsing.
7.2 Tests at Northern Malleable Iron Company (Magnesium Oxide Emission)
The field tests began at Northern Malleable Iron Company in April 1977. The
emissions at this site are from a manganese innoculation process in the making of
malleable iron.(A high percentage of magnesium oxide emanates from this process.)
Figure 7-15 illustrates these emissions. Immediately behind the cupola, next to the
person in this photograph, is a vertical ventilation hood. Air is drawn through this
hood and is routed through ducting to a bag ho use dust collector located on the outside
of the building. The fine fiber filter unit was located next to the bag ho use. A portion
of the air going to the bag ho use was routed to the fine fiber filter unit.
Figure 7-16 depicts the installation at Northern Malleable.
Figure 7-17 is a schematic illustration of the test setup. The unit was run at three
different air-to-cloth ratios during the testing: 35 mm/sec, 25 mm/sec, and 12 mm/sec,
The pressure drop was monitored throughout the testing. The pressure drop did not
stabilize while operating at an air-to-cloth ratio of 35 mm/sec. The elements were
subsequently replaced and the test run at 25 mm/sec. Again, the pressure drop did
not stabi lize and again a media failure occurred between 408.6 hours and 539.6
hours of operation. The elements were again replaced and the unit was run at an
air-to-cloth ratio of 12 mm/sec until 30 August 77. The unit accumulated 443.2
•
hours of operation without failure and the pressure drop was stabilized.
132
-------
Figure 7-15. Innoculafion Process at Northern Malleable Iron Company
133
-------
Figure 7-16. Installation at Northern Malleable Iron Company
134
-------
ft
20 in. dia.
Torit
Bag ho use
CO
Ul
f Cleaning Air T
*-6
Filter Element (3 used)
Pump
Figure 7-17. Test Setup at Northern Malleable Iron Company
Innoculation Hood
-------
7.2.1 Particulate Characterization (Magnesium Oxide Emission)
In order to characterize the magnesium oxide emission, the following analyses were
performed: Coulter Counter, Andersen Cascade Impactor sampling, scanning
electron microscopy, transmission electron microscopy and x-ray analysis.
Coulter Counter analysis was performed on samples of the emission taken at a point
2.4 meters above the innoculating process and from the collected particles in the
bin of the bag ho use. Figure 7-18 presents the particle size spectrums. (Note: the
D50 of the sample in the bag ho use bin is less than 2.4 Mm).
An x-ray dispersive radiation technique was used to scan particles on both upstream and
downstream samples. Analysis of a large cubic particle on a downstream sample re-
vealed that it was high in magnesium. Magnesium oxide has a typical cubic shape.
A spherical particle from the upstream sample was found to be comprised mostly of
manganese and iron. A relatively high content of silica was also present.
A six-stage Andersen dust sampler was used to sample the upstream duct. Table 7-6
presents the percent of emission in a given size range. Over 53 percent of the
particles are below 2.0 Um.
Scanning electron micrographs and transmission electron micrographs both confirmed
the existence of a high number of submierometer particles in the magnesium oxide
em ission.
Figure 7-19 depicts transmission electron micrographs of the MgO part icu I ate from
upstream and downstream samples at IOK magnification. One can readily see the
cubic shape of the MgO particles and a large number of submierometer particles.
Scanning electron micrographs are shown on Figures 7-20 and 7-21 at 2K and IOK
magnification. Figure 7-20 is the upstream sample and Figure 7-21 presents the
downstream sample. (The space between the white lines is 0.5u m). These micro-
graphs also show the characteristic cubic shape of the magnesium oxide part icu I ate.
136
-------
CO
U4
N
Q
Ul
10
5
NORT1 EPN MALLEAfLE IRON COMPANY
(TO Element Inquiry)
-v MemLranc iampic B Ir Ahove
___ Inno-nirttinn
T] Grosi Sample - Bin of Torit Baghoine
* > • ' * i n ij t j.* i * »
PARTICLE DIAMETER, microns
Tl I IU I I II I lllniilllilUllillllJ ill*4llll|ll
1 U 1
Figure 7-18. Particle Size Spectrum Analysis Northern Malleable Iron Company
-------
LJ
00
»* * v;
™* 1 u m
Downstream
1 u m
Upstream
Figure 7-19. 10K ^^ Micrograph of Upstream and Downstream Samples of
MgO Particulate
-------
Northern Upstream
2,OOOX
Northern Upstream
10,OOOX
Figure 7-20. SEM Microaraphs of Mg O Particulate - Upstream
139
-------
Northern Downstream
2,OOOX
Northern Downstream
10,OOOX
Figure 7-21 . SEM Micrograph of Mg O Particulate - Downstream
140
-------
The dork and rather uniform circles are the holes in the Nuclepore membrane. A
greater number of large particles is apparent in the downstream sample than the
upstream sample showing that some solubility penetration is occurring. (Magnesium
oxide is slightly soluble in water and also in acids and ammonium salts).
7.2.2 Performance Tests - Norther Malleable Iron Company
The performance tests of the fine fiber cartridge filter unit at Northern Malleable
Iron Company involved the following: OOP penetration tests of clean cartridges,
overall mass efficiency, fractional efficiency, filter dust loading and durability.
The filter unit at Northern Malleable was operated at air-to-cloth ratios of 35 mm/sec,
25 mm/sec, and 12 mm/sec.
The filter elements were tests for DOP efficiency prior to field tests. Table 7-7
presents the efficiency on 0.3 Mm diameter DOP particles. These tests were run at
an air-to-cloth ratio of 50 mm/sec.
Table 7-7. DOP Efficiency of Elements for Field
Test at Northern Malleable Iron Co.
Element
No.
F2
F4
F6
F7
F8
F9
F10
Fll
F12
Efficiency on
0.3 m dia. DOP
91%
« 90
90
95
97
94
Not available
Not available
Not available
Air-to -Cloth Ratio
DOP Test
50 mm/sec
50
50
50
50
50
—
--
— —
Field Test
35 mm/sec
35
35
25
25
25
12
12
12
141
-------
Gravimetric samples were taken simultaneously upstream and downstream of the filter
unit to determine overall mass efficiency. Table 7-8 presents the overall mass
efficiency data. The average of two different efficiency tests is 99.95 percent.
Also presented in this table is the upstream concentration. The concentration of
particulate material at this site was many times higher than at Cornelius Company
(185.4 mg/m average for Northern Malleable versus 0.7 mg/m average at
Cornelius).
Table 7-8. Overall Mass Efficiency for Field
Test at Northern Malleable Iron Co.
Upstream Concentration
(mg/m3)
Overall Mass Efficiency
179.0
191.7
99.96%
99.93
99.95% average
Fractional efficiency data was obtained using an Andersen Cascade I mpactor. Be-
cause the downstream concentrations are very low, only three of the six stages were
used so that weighable samples could be obtained. Only one Andersen dust sampler
was used so the upstream and downstream samples were not concurrent. Table 7-9
presents the fractional efficiency data.
Table 7-9. Fractional Efficiency for Field Test
at Northern Malleable Iron Co.
Particle Size Range
(micrometers)
<0.3
0.3-2.0
2.0-5.5
5.5 - 20.0
Efficiency
w
96.63
99.04
97.92
98.53
142
-------
The pressure drop and media durability of the system were monitored throughout the
field tests. Initially, the filter unit was run at an air-to-cloth ratio of 35 mm/sec.
After 160 hours of operation at this air-to-cloth ratio, the system pressure drop had
increased from 182.88 mm HjO to 571.5 mm H2). The cartridges were subsequently
replaced and the air-to-cloth ratio adjusted to 20 mm/sec. Testing was continued
until 539.6 hours had accumulated, at which time the filter unit restriction had
risen to 546.1 mm h^O and dust was visibly passing through the filter unit. This
failure occurred sometime between 408.6 hours and 539.6 hours. The filter elements
were inspected and was found that the substrate media had fatigued and there were
holes in the media.
Figure 7-22 shows a filter element loaded with the white magnesium oxide compared
to a clean filter element.
Figure 7-23 shows one of the holes that developed in the filter medium during the
tests at an air-to-cloth ratio of 25 mm/sec. ( It appears as a very light area because
the element is illuminated from inside with a lightbulb). It is felt that, as the
pressure drop across the medium increased due to dust loading, there was greater
deflection and stress in the medium during pulse cleaning. Also, the inlet temperature
of the gas at this site is I50°F. A stronger substrate medium would probably alleviate
this problem. Tests were resumed at Northern Malleable with clean filter cartridges
and were run at an air-fo-cloth ratio of 12 mm/sec. No failures occurred after
443.2 hours of operation. The pressure drop appeared stable at approximately 290
mm hUO.
Figure 7-24 presents the operating pressure drop as a function of time for the three
air-fo-cloth ratios 35 mm/sec, 25 mm/sec, and 12 mm/sec. The tests at 12 mm/sec
concluded the field testing to be performed under this contract as of 30 August
1977.
143
-------
Figure 7-22. Dirty versus Clean Filter Cartridges -
Northern Malleable -MqO Er
ission
-------
Figure 7-23. Failed Filter Cartridge - Light
Spot Indicates Hole in Media
-------
546.1 mm H-O
289.6 mm HjO
Air-to-Cloth Ratio = 12 mm/sec
Air-torCloth Ratio =25 mm/sec
O Air-to-Cloth Ratio = 35 mm/sec
280 320
40
160 200 240
Time (hours)
«*.* 3.2
539.6
Figure 7-24. Operating FVessure Drop as a Function of Time (Northern Malleable Iron Company)
-------
8.0 ECONOMIC ANALYSIS
To illustrate the cost advantages of the double mat filter in a cartridge configuration, two
examples are presented. These examples consist of dust control problems to which four
methods of control are applied for cost comparisons. The data for electrostatic precipitation,
scrubbers and bag ho use filters are taken from "Air Pollution Control Technology and Costs
in Seven Selected Areas", EPA-450/3-73-010, December 1973. The cost data for the
cartridge filter analysis was obtained from Torit Division Donaldson Company, Inc. and
is valid for December 1975. To obtain a conservative estimate, air-to-cloth ratio was
held at about 1 for the cartridge filter application and the cost of filter cartridges was
estimated to be one and one-half times that of the current cartridges using standard media.
Consequently, this cost estimate does not include potential savings from operating at
high air-to-cloth ratio.
Note that the four methods of control presented here do not provide equal performance.
If submicrometer particles must be controlled, only the barrier filter option is available.
Also, in the event that fine particles must be controlled, the double mat filter will
provide superior performance over conventional media.
8.1 Dust Control from a Vertical Lime Rock Kiln
The first example selected is dust control from a vertical lime rock kiln (Report EPA-450/
3-73-010, December 1973).
The filter removes entrained limestone and lime dust from the exhaust gas of a vertical
lime rock kiln. The kiln is fired with natural gas. A portion of the hot exhaust gas from
the calcining zone is recirculated for heat recovery. The kiln is fed with 15 to 20 cm
sized pieces of high calcium limestone.
The exhaust gas is brought from the kiln exhaust ports to a location 6.1 meters outside of
the kiln enclosure by means of a fan. The filter will be located in an area free of space
limitations. The fan follows the filter and the fan outlet is 1.5 meters above grade.
Tables 8-1 through 8-8 and Figures 8-1 through 8-9 give cost comparison data on the
four methods of dust control from a vertical lime rock kiln.
147
-------
500,000
100,000
_0
~0
••-
O
- 10,000
•5.
1,000
—
||
100
1000
3
Gas Flow (am /min )
11
8 "';
2000
Figure 8-1. Capital Costs for Electrostatic Precipitators for Vertical Lime Rock
Kilns (High Efficiency)
148
-------
Table 8-1 . Estimated Capital Cost Data (Cosh in Dollars) for Electrostatic
Precipitators for Vertical Lime Rock Kilns
Effluent Gas Flow
amvmin
°C
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am'*
kg/hr
Cleaned Gas Flow
amvmin
oc
sm^/min
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/am3
fcg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations *
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other J
(4) Total Cost
>
LA Process Wt.
Small
Large
High Efficiency
Small
722.08
135
521 .03
12
3.02
130.86
722.08
135
521 .03
12
0.023
0.99
99.24
67,745
25,838
60,060
,
153,643
Large
1441.3
135
1039.2
12
3.23
278.96
1441.3
135
1039.2
12
0.023
1.98
99.29
95,515
38,225
82,350
216,090
149
-------
500,000
100,000
~B 10,000
"O
1,000
1,000
o
Gas Flow (am /min)
2,000
Figure 8-2. Annual Costs for Electrostatic Precipitators for Vertical Lime Rock Kilns
(High Efficiency)
150
-------
Table 8-2. Annual Operating Data (Costs In $/fr) for Electrostatic Precipitators
for Vertical Lime Rock Kilns
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator *
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6Ar
$6Ar
$.01lAw-hr
10% of
Capital
LA Process Wt.
Small
Large
High Efficiency
Small
2,000
2,000
1,072
1,072
600
600
3,036
3,036
6,708
15,364
22,072
Large
2,000
2,000
2,139
2,139
1,200
1,200
5,984
5,984
11,323
21 ,609
32,932
-------
500,000
100,000
U1
D
10,000
u
Q.
O
1,000
Gas
1000
3
Flow (am /min)
2000
Figure 8-3. Capital Costs for Wet Scrubbers for Vertical Lime Rock Kilns
(High Efficiency)
152
-------
Table 8-3. Estimated Capital Cost Data (Costs in Dollars) for
Wet Scrubbers for Vertical Lime Rock Kilns
Effluent Gas Flow
am3/min
°C
sm3/min
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am3
kg/hr
Cleaned Gas Flow
am^/min
°C
smvmin
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/am^
kg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan
-------
500,000
100,000
10,000
l/l
o
U
1,000
1000
Gas Flow (am /min)
2000
Figure 8 "4. Annual Costs for Wet Scrubbers for Vertical Lime Rock
Kilns (High Efficiency)
154
-------
Table 8-4. Annual Operating Cost Data (Cosh in $/YO for Wet Scrubbers for
Vertical Lime Rock Kilns
Operating Cost Item
Operating Factor, HrAear
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (FVocess)
Water (Cooling)
Chemicals, Specif/
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6Ar
$.01lAw-hr
S.066AJ2
10% of
Capital
LA Process Wt.
Small
Large
High Efficiency
Small
8,000
1,290
727
727
4,841
191
5,032
7,049
3,847
10,896
Large
8,000
2,007
1,283
1,283
15,726
647
16,373
19,663
6,299
25,962
-------
500,000
100,000
c
_0
~o
3,
1
- 10,000
o
'o.
3
LOGO
2000
Gas Flow (am /min)
Figure 8-5. Capital Costs for Fabric Filters for Vertical Lime Rock Kilns
156
-------
Table 8-5. Estimated Capital Cost Data (Costs in Dollars) for
Fabric Filters for Vertical Lime Rock Kilns
Effluent Gas Flow
amvmin
°C
sm^/min
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am3
kgAr
Cleaned Gas Flow
amvmin
smvmin
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/arrfi
kg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b Pump(s)
(c) (c) Damper(s) Emer . Temp .
Tern p. Air
(d) Conditioning ,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations M
& Support
Ductwork
Stack
*€lecfrical
Piping
* Insulation
Painting
Supervision
*Startup
Performance Test
Other J
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
206.7
135
150.08
12
2.95
36.6
206.7
135
150.08
12
.023
.286
99.22
30,573
2,556
2,000
5,850
29,234
70,213
Large
722.08
135
521.03
12
3.02
130.86
722.08
135
521.03
12
.023
0.99
99.24
78,427
6,213
2,000
5,850
52,318
144,808
*Not Included;
157
-------
500,000
100,000
= 10,000
-
1,000
1000
Gas Flow (am /mm)
2000
Figure 8-6. Annual Costs for Fabric Filters for Vertical Lime Rock Kilns
158
-------
Table 8-6. Annual Operating Cost Data (Cost in $AO for Fabric Filters for
Vertical Lime Rock Kilns
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor »
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr.
$.01lAw-hr
10% of
Capital
LA Process Wt.
Small
Large
High Efficiency
Small
8,000
9,000
200
9,200
400
400
1,980
1,980
11,580
6,821
18,401
Large
8,000
12,000
600
12,600
1,400
1,400
6,600
6,600
20,600
14,481
35,081
-------
500,000
100,000
_D
"o
-
10,000
CL
D
U
1,000
1000
Gas Flow (am /min)
2000
Figure 8-7. Capital Costs for Cartridge Filters for Vertical Lime Rock Kilns
160
-------
Table 8-7. Estimated Capital Cost Data (Costs in Dollars) for
Cartridge Filters for Vertical Lime Rock Kilns
Effluent Gas Flow
amy/min
°C
smvmin
Moisture Content, Vol %
Effluent Contaminant Loading
/'S
am0
kg/hr
Cleaned Gas Flow
amvmin
°C
sm^/min
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/arn^
kg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fanfs)
(b) Pump(s)
(c) Damper(s) Emer.Temp.
Air
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork *
Stack
'Electrical
Piping >
"Insulation
Painting
Supervision
"Startup
Performance Test
Other '
(4) Total Cost
LA Process Wt.
Small
8,170
21,925
Large
20,530
39,238
High Efficiency
Small
206.7
135
150.08
12
2.95
36.6
206.7
135
150.08
12
* .023
«.28
**
2,556
2,000
5,850
40,501
Large
722.08
135
521 .03
12
3.02
130.86
722.08
135
521.03
12
-=.023
*.99
**
6,213
2,000
5,850
73,830
*Not Included
**Cartridge Filter Media is 90 % Efficiency on OOP compared to 10%
Fabric (Filters. The "Cleaning Efficiency" should be 99.9 % plus.
- 20% for Standard
161
-------
500,000
100,000
=| 10,000
T3
s
u
Gas Flow (am /m!n)
Figure 8-8.
Costs
fer
V^cd U.e Roc. Kilns
162
-------
Table 8-%. Annual Operating Cost Data (Cosh in $/W) for Cartridge Filters for
Vertical Lime Rock Kilns
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hr
10% of
Capital
LA Process Wt.
Small
Large
High Efficiency
Small
8,000
2,400
2,400
1,440
1,440
1,980
1,980
5,820
4,050
9,870
Large
8,000
6,400
6,400
17920
1,920
6,600
6,600
14,920
7,383
22,303
-------
500,000
A = Electrostatic Preci pita tors
B = Wet Scrubber
C = Fabric Fi Ifer
D = Cartridge Fi Iter
100,000
10,000
_D
~0
3
,000
1000
Gas Flow (am /min)
2000
Figure 8-9. Annual Cost Comparison for Electrostatic Precipitators,
Wet Scrubbers, Fabric Filters and Cartridge Filters
(High Efficiency)
164
-------
8.2 Porticulate Removal From the Exhaust Gas of a Glass-Melting Furnace
The second example selected is a glass-melting furnace (Report EPA-450/3-74-060
December 1974).
A filter removes particulate matter from the exhaust gas of a glass-melting furnace. The
furnace is fired with No. 5 fuel oil using 40 percent excess combustion air.
The exhaust gas is to be brought from the furnace exhaust ports to a location 9.1 meters
outside of the furnace enclosure by means of a fan. The filter is at ground level in an
area beyond the ductwork which is free of space limitations. The fan precedes the filter.
The abatement system continuously reduces the furnace outlet loading to the levels
specified.
This application requires a filter media which will withstand temperatures up to 260°C.
The present cartridge filter media will not meet this requirement; however, for this analysis,
we are assuming that a filter media could be developed that would meet the high temperature
requirement. Heat recovery could also be employed to reduce the exhaust gas temperature.
This would, of course, increase the capital costs; however, the savings could possibly be
recovered from use of the energy removed from the exhaust gas.
Tables 8-9 through 8-16 and Figures8-10 through 8-18 give cost comparison data for this
example.
8.3 Conclusion*
These two examples show that barrier filter units employing cartridge filters are more
competitive than standard bog house units and can easily be shown to be the lowest cost
alternative in many cases.
165
-------
Table 8-9. Estimated Capital Cost Data (Costs in Dollars) for
Electrostatic Freeipitafors for Glass-Melting Furnace
Effluent Gas Flow
am3/min
<>C
sm3/"iin
Moisture Content, Vol %
Effluent Contaminant Loading
/ Q ^*
am/am0
kg/hr
Cleaned Gas Flow
am3/min
OC
smvmin
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/am*
kg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s}<
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
Model Study
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Medium Efficiency
Small
Large
High Efficiency
Small
707.9
385
317.15
12
.183
7.66
707.9
385
317.15
12
.023
.97
88
94,312
4,800
1,309
3,530
5,066
249,796
358,813
Large
1699
385
758.89
12
.183
18.37
1-699
385
758.89
12
.023
2.33
88
152,285
6,700
3,067
4,120
8,280
339,321
513,773
166
-------
500,000
100,000
I
1
10,000
1,000
1000
3
Cleaned Gas Flow (am /min)
2000
Figure 8-10. Capital Cost of Electrostatic Precipitators for Glass-Melting
Furnace
167
-------
Table8 -10. Annual Operating Cost Data (Costs in $/Yr) for
Electrostatic PrecipJtators for Glass-Melting Furnace
Operating Cost Item
Operating Factor, Hr//ear 8,600
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hr
16% of
Capital
LA Process Wt.
Small
Large
High Efficiency
Small
240
75
315
550
550
6,467
6,467
7,332
57,410
64,742
Large
240
125
365
550
550
11,146
11,146
12,061
82,204
94,265
-------
500,000
100,000
1,000
1000
3
Cleaned Gas Flow (am /min)
2000
Figure 8-11. Annual Cost of Electrostatic Precipitators for Glass-Melting Furnace
169
-------
Tobleft-11. Estimated Capital Cost Data (Costs in Dollars) for
Wet Scrubbers for Glass-Melting Furnace
Effluent Gas Flow
anrymin
. 3 / .
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am
kg/hr
Cleaned Gas Flow
am /min
sm^/min
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/amj
kgA
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other '
>
(4) Total Cost
Medium Efficiency
Small
Large
High Efficiency
Small
707.92
385
317.15
12
.183
7.67
483.91
66.7
379.45
26
.023
.603
92
13,983
37,363
1,725
175
17,493
8,233
3,950
62,298
145,220
Large
1699
385
758.89
12
.183
18.37
1053.39
66.7
911.80
26
.023
1.45
^\rt
92
22,418
70,455
2,698
250
30,493
8,828
3,950
82,518
221,610
170
-------
500,000
100,000
I
~o
T 10,000
I ft *
o
u
1,000
2000
Cleaned Gas Flow (am /min)
Figure 8-12. Capital Cost of Wet Scrubbers for Glass-Melting Furnace
171
-------
Table 8-12. Annual Operating Cost Data (Costs in $/Year) for
Wet Scrubbers for Glass-Melting Furnace
Operating Cost Item
Operating Factor, Hr/Year 8,600
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Totckl Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6Ar
$8/hr
$6/hr
$.01lAw-hr
$.066A£
$.0132A£
16%of
Capital
Medium Efficiency
Small
Large
High Efficiency
Small
6,300
1,600
7,900
1,950
750
2,700
1,250
1,250
17,683
1,506
353
19,542
31,392
23,235
54,627
Large
6,300
1,600
7,900
1,950
875
2,825
2,375
2,375
42,834
3,264
844
46,942
60,042
35,458
95,500
-------
500,000
100,000
8 10,000
u
1,000
2000
Cleaned Gas Flow (am /min)
Figure 8-13. Annual Cost of Wet Scrubbers for Glass-Melting Furnace
173
-------
Table 8-13. Estimated Capital Cost Data (Costs in Dollars)
for Fabric Filters for Glass-Melting Furnace
Effluent Gas Flow
amvmin
°C
sm^/min
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am3
kgAr
Cleaned Gas Flow
amvmin
°Q»
smvmin
^
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
am/am3
kg/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering >
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
>
Medium Efficiency
Small
Large
High Efficiency
Small
707.92
385
317.15
12
.229
7.67
529.53
218.3
312.15
12
.023
.726
91
78r871
7,673
8,823
21 ,871
3,619
17,838
10,000
8,229
2,090
7,500
500
27,375
*
7,830
1,060
3,000
57,911
264,190
Large
1699
385
758.89
12
.229
18.37
1267.18
218.3
758.89
12
.023
1.74
91
147,338
15,730
11,744
47,432
4,563
22,450
17,250
12,696
3,120
10,000
850
45,638
*
11,515
1,560
4,000
112,983
468,949
* Included in (1) above
174
-------
500,000
100,000
I
-8
10,000
1,000
2000
Cleaned Gas Flow (am /min)
Figure 8-14. Capital Cost of Fabric Filters for Glass-Melting Furnace
175
-------
Table 8-14. Annual Operating Cost Data (Costs tn $/Year) for Fabric
Filters for Glass-Melting Furnace
Operating Cost Item
Operating Factor, Mr/Year 8,600
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials & Replacement
Parts
Total
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr.
$8Ar.
$6/hr
$0.011 /kw-hr
16% of
Capital
Medium Efficiency
Small
Large
High Efficiency
Small
2,681
835
3,516
1,679
11,773
13,452
16,763
16,763
33,731
42,270
76,001
Large
3,984
922
4,906
2,674
22,108
24,782
30,739
30,739
60,427
75,032
135,459
-------
500,000
100,000
A
§ 10,000
1,000
2000
Cleaned Gas Flow (am /min)
Figure 8-15. Annual Cost of Fabric Filters for Glass-Melting Furnace
177
-------
Table 8-15* Estimated Capital Cost Data (Costs in Dollars) for
Cartridge Filters for Glass-Me I ting Furnace
Effluent Gas Flow
am^/min
°C
sm3/min
Moisture Content, Vol %
Effluent Contaminant Loading
gm/am3
kgAr
Cleaned Gas Flow
am^/min
oC
sm3/min
Moisture Content, Vol %
Cleaned Gas Contaminant
Loading
gm/am3
kgAr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
0>) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering 1
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other ,
>
(4) Total Cost
Medium Efficiency
Small
20,530
5,000
13,680
43,435
172,678
Large
51,325
8,625
22,820
84,740
313,170
High Efficiency
Small
707.92
385
317.15
12
,229
7.67
529.53
218.3
317.15
12
*.023
*.726
**
7,673
8,823
21,871
3,619
17,838:
8,229
2,090
7,500
500
*
7,830
1,060
3,000
Large
1699
385
758.89
12
.229
18.37
1267.18
218.3
758.89
12
-e .023
«1.74
**
15,730
11,744
47,432
4,563
22,450
12,696
3,120
10,000
850
*
11,515
1,560
4,000 .
* Included in (1) above
Cartridge Filter Media is 90% Efficiency on DOP compared to 10% - 20% for Standard
Fabric Filters. The "Cleaning Efficiency" should be 99.9% plus.
**
178
-------
500,000
100,000
10,000
1,000
2000
Cleaned Gas Flow (am /min)
Figure 8-16. Capital Cost of Cartridge Filters for Glass-Melting Furnace
179
-------
Table 8-16, Annual Operating Cost Data (Costs In $Aear) for Cartridge Filter
for Glass-Melting Furnace
Operating Cost Item
Operating Factor, Hr/Year 8,600
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials & Replacement
Parts
Total
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6Ar
$.011/kw-hr
16% of
Capital
Medium Efficiency
Small
3,840
5,519
25,798
27,628
53,426
Large
9,600
12,274
47,919
50,107
98,026
High Efficiency
Small
2,681
835
3,516
1,679
16,763
16,763
Large
3,984
V22
4,906
2,674
30,739
30,739
-------
500,000
100,000
I
A
8
u
10,000
1,000
I 1 Li :-
Hti
1
:0«n
£>TAL
lit
100
1000
o
Cleaned Gas Flow (am /min)
2000
Figure 8-17. Annual Cost of Cartridge Filters for Glass-Melting Furnace
181
-------
A - Electrostatic Precipitators
B = Wet Scrubbers
C = Fabric Filters
D = Cartridge Filters
500,000
100,000
o
~D
O
U
10,000
1,000
1000
Cleaned Gas Flow (am /min)
2000
Figure 8-18. Annual Cost Comparison for Electrostatic Precipitators, Wet
Scrubbers, Fabric Filters and Cartridge Filters for Glass-
Melting Furnace
182
-------
9.0 GLOSSARY
Air-to-Cloth Ratio - Amount of air volume in ratio to area of cloth in filter.
Basis Weight - Weight per unit area of the filter bed.
Double Mat Filter - Combination of a porous backing medium with a filtration layer
of fine fibers.
Efficiency - Weight collected upstream divided by the weight collected upstream plus
the weight collected on the downstream absolute.
Filter Bed - Mat of fibers designed to allow the passage of gas but to collect particles
entrained in the gas.
Fine Particle - Particle less than 3 Jim in diameter.
Overall Dust Loading - Weight of dust collected on the sample plus the weight of dust
collected upstream of the sample expressed as weight per unit area,
Residual Dust Loading - Weight per unit area of dust remaining on the media sample.
Scrim - Durable fabric, usually used for added strength.
Turnkey System - Includes design, all labor and materials, equipment fabrication,
___^__^__^_ %
erection and start-up.
183
-------
10.0 REFERENCES
Caivert, Seymour, etal. Scrubber Handbook, Volume 1, A.P.T., Inc., P.O. Box 71,
Riverside, California (1972).
Hard!son, UC., Air Pollution Control Technology and Costs in Seven Selected Areas,
EPA-450/3-73-010, pp 481-559/(1973).
Steenberg, UR., Air Pollution Control Technology and Costs; Seven Selected Emission
Sources, EPA-450/3-74-060, pp 99-140 (1974).
Yeh, Hsu-Chi, and Liu, Benjamin Y.H., "Aerosol Filtration by Fibrous Filters- I.
Theoretical", Aerosol Science, Vol 5, pp 191-204 (1974)
185
-------
11.0
CONVERSION FACTORS
As required by the contract, metric units are used throughout this report. For English
units, the following conversion factors are provided:
To Convert
2
Basis weight (gm/m )
Permeability (m3/min/m2@
12.7mmH20)
Pressure (mm hLO)
Pressure (Pascal)
Velocity (mm/sec)
Newton /50 mm strip
Air-to -C loth-Ratio (mm/sec)
Dust F*ed Concentration
(mg/nrO
Dust Loading (gm/m )
Meter
m /min
/ 3
gm/m
kg/hr
Multiply by
(0.029467)
(3.2808)
(0.03937)
(l.4513x 10"4)
(0.19685)
(0.22857)
0.19685
2.83168 x 10"5
0.092903
3.281
35.31466
0.436996
2.20462
To Obtain
oz/yd
crni/ft2@iin. H20
in. H20
psi
ft/min
lbsj/2 in. strip
ft/min
gm/ft3
gm/ft2
foot
cfm
gr/ft3
IbAr
187
-------
TECHNICAL REPORT DATA
(nease read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-77-140
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Participate Control with Cleanable Cartridge Filters
Using Double-Layer Media
5. REPORT DATE
December 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
William J. Krisko and Michael A. Shackleton
8. PERFORMING ORGANIZATION REPORT NO.
EPA-001
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Donaldson Company, Lie.
P.O. Box 1299
Minneapolis, Minnesota 55440
10. PROGRAM ELEMENT NO.
1AB012; ROAP 21ADL-029
11. CONTRACT/GRANT NO.
68-02-1878
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final: 6/75-10/77
14. SPONSORING AGENCY CODE
EPA/600/13
^.SUPPLEMENTARYNOTEST£RL-RTP project officer is Dennis C. Drehmel, Mail Drop 61,
919/541-2925.
16. ABSTRACT
The report gives results of a detailed assessment 01 the feasibility 01 a
new concept in fine particle filtration, nonwoven, double-mat, cartridge filters. The
filter consists of a fine fiber filtration layer supported by a porous substrate providing
physical strength to the resulting filtration media. A theoretical basis for fine par-
ticle control with this media is presented. Test results with 0. 3 micrometer DOP
smoke confirmed that the design objective of 90% collection efficiency was obtainable.
Preliminary economic analysis indicates that the cartridge filter will be less costly
than the standard baghouse. The saving is a result of the smaller system possible
with the pleated cartridge and the potentially higher air-to-cloth ratios with the fine
fiber media. The analyses comprised Phase I of the contract. Phase n evaluated the
fine particle control characteristics of the media in a pulse-jet cleaning cartridge
configuration. Both laboratory and field tests proved the media capable of high dust
removal efficiency of fine particles «3 micrometers) while achieving good pulse-jet
cleaning characteristics.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Croup
Air Pollution
Dust Control
Smoke
Filtration
Emission
Nonwoven Fabrics
Kilns
Furnaces
Electrostatic Pre-
cipitation
Calcium Oxides
Scrubbers.
18. DISTRIBUTU
Air Pollution Control
Stationary Sources
Particulates
Fabric Filters
Double Mat Filters
Cartridge Filters
Baghouses
13B
21B
07D
11E
13A_
13A
13H
07B
21. NO. OF PAGES
189
TRIBUTION STATEMENT
Unlimited
IB. SECURITY CLASS (This Report)
Unclassified
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 222
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