EPA-600/2-76-074
March 1976
Environmental Protection Technology Series
EFFECT OF FILTRATION PARAMETERS ON
DUST CLEANING FABRICS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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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 five series. These five 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 five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U. S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-074
March 1976
EFFECT OF
FILTRATION PARAMETERS
ON DUST CLEANING FABRICS
by
Jan R. Koscianowski and Lidia Koscianowska
Institute of Industry of Cement Building Materials
45-641 Opole
Oswiecimska Str. 21 POLAND
PL-460 Agreement No. 5-533-3
ROAPNo. 21ADJ-094
Program Element No. 1AB012
EPA Project Officer: James H. Turner
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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TABLE OF CONTENTS
Page
LIST OF FIGURES v
LIST OF TABLES xi
ACKNOWLEDGMENT xii
SECTION I - CONCLUSIONS 1
SECTION II - RECOMMENDATIONS 2
SECTION III - INTRODUCTION 3
INVESTIGATION OF DUST FILTRATION PROCESSES 3
PROBLEMS IN DUST FILTRATION 5
RESEARCH OBJECTIVES 7
GENERAL PROGRAM 8
Laboratory Testing 8
Definition of Structural Parameters for Fabric . . 9
Definition of Structural Parameters for Dust
Layers 9
Testing of Electrostatic Properties of Dusts
and Fabrics 10
DETAILED PROGRAM FOR FIRST PHASE 10
Laboratory Tests 10
Definition of Structural Parameters for Fabrics. . 11
Definition of the Structural Parameters of
Dust Layers 11
Definition of Characteristic Properties of
Dusts and Fabrics 11
FABRIC AND DUST SELECTION 11
SECTION IV - LABORATORY TESTING OF FILTRATION 15
EQUIPMENT AND PROCEDURES 15
RESULTS AND DISCUSSION 18
CONCLUSIONS 22
SECTION V - BASIC RESEARCH ON A MODEL FOR DUST FILTRATION . 23
INTRODUCTION 23
Dust Filtration Type I 24
Dust Filtration Type^II 25
Dust Filtration Type III 25
STUDY OF FILTER MEDIUM PARAMETERS 27
Introduction 27
Fabric Selection 29
Equipment and Procedures 29
Results and Discussion 29
Conclusions 30
in
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TABLE OF CONTENTS (cont.)
Pa^e
STUDY OF DUST PARAMETERS 57
Introduction 57
Equipment and Procedures 57
Results and Discussion , 58
Conclusions , . . 59
STUDY OF THE ELECTROSTATIC PROPERTIES OF DUSTS
AND FABRICS 59
Introduction 59
Dust Electrification 60
Specific Resistivity of Dusts 60
Specific Resistivity of Fabrics 60
Discussion and Conclusions 61
APPENDIX A: FIGURES Al THROUGH A101 62
APPENDIX B: BAHCO SEPARATOR 164
APPENDIX C: SARTONIUS SEDIMENTATION BALANCE 165
APPENDIX D: ALPINE MULTI-PLESC SEPARATOR 166
APPENDIX E: AIR PERMEABILITY TESTING DEVICE 168
APPENDIX F: TENSIL TESTING MACHINE 169
APPENDIX G: LIST OF NOMENCLATURE 171
APPENDIX H: METRIC CONVERSIONS 173
IV
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LIST OF FIGURES
Figure Page
1 Illustration of Laboratory Stand '. . 15
2 Diagram of the Laboratory Test Stand 16
A-l Particle Size Distribution for Cement Dust 63
A-2 Particle Size Distribution for Coal Dust 64
A-3 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric ET-4 (separated dust) 65
A-4 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric ET-30 (separated dust) 66
A-5 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric F-tor 5 (separated dust) 67
A-6 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric PT-15 (separated dust) 68
A-7 Pressure Difference vs. Filtration Time for Coal Dust
and Dust and Fabric ET-4 (separated dust) 69
A-8 Pressure Difference vs. Filtration Time for Coal Dust
and Fabric ET-30 (separated dust) 70
A-9 Pressure Difference vs. Filtration Time for Coal Dust
and Fabric F-tor 5 (separated dust) 71
A-10 Pressure Difference vs. Filtration Time for Coal Dust
and Fabric PT-15 (separated dust) 72
A-ll Pressure Difference vs. Dust Load for Cement Dust
and Fabric ET-4 (separated dust) 73
A-12 Pressure Difference vs. Dust Load for Cement Dust
and Fabric ET-30 (separated dust) 74
A-13 Pressure Difference vs. Dust Load for Cement Dust
and Fabric F-tor 5 (separated dust) 75
A-14 Pressure Difference vs. Dust Load for Cement Dust
Fabric PT-15 (separated dust) 76
A-l5 Pressure Difference vs. Dust Load for Coal Dust and
Fabric ET-4 (separated dust) 77
A-16 Pressure Difference vs. Dust Load for Dust and Fabric
ET-30 (separated dust) 78
A-l7 Pressure Difference vs. Dust Load for Coal Dust
and Fabric F-tor 5 (separated dust) 79
A-18 Pressure Difference vs. Dust Load for Coal Dust
and Fabric PT-15 (separated dust) 80
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LIST OF FIGURES (cont.)
Figure Page
A-19 Efficiency vs. Filtration Rate for Cement Dust and
Fabric ET-4 (separated dust) 81
A-20 Efficiency vs. Filtration Rate for Cement Dust and
Fabric ET-30 (separated dust) ... 82
A-21 Efficiency vs. Filtration Rate for Cement Dust and
Fabric F-tor 5 (separated dust) 83
A-22 Efficiency vs. Filtration Rate for Cement Dust and
Fabric PT-15 (separated dust) 84
A-23 Efficiency vs. Filtration Rate for Coal Dust and
Fabric ET-4 (separated dust) 85
A-24 Efficiency vs. Filtration Rate for Coal Dust and
Fabric ET-30 (separated dust) 86
A-25 Efficiency vs. Filtration Rate for Coal Dust and
Fabric F-tor 5 (separated dust) 87
A-26 Efficiency vs. Filtration Rate for Coal Dust and
Fabric PT-15 (separated dust) 88
A-27 Efficiency vs. Dust Load for Cement Dust and
Fabric ET-4 (separated dust) 89
A-28 Efficiency vs. Dust Load for Cement Dust and
Fabric ET-30 (separated dust) 90
A-29 Efficiency vs. Dust Load for Cement Dust and
Fabric F-tor 5 (separated dust) 91
A-30 Efficiency vs. Dust Load for Cement Dust and
Fabric PT-15 (separated dust) 92
A-31 Efficiency vs. Dust Load for Coal Dust and Fabric
ET-4 (separated dust) 93
A-32 Efficiency vs. Dust Load for Coal Dust and Fabric
ET-30 (separated dust) 94
A-33 Efficiency vs. Dust Load for Coal Dust and Fabric
F-tor 5 (separated dust) 95
A-34 Efficiency vs. Dust Load for Coal Dust and Fabric
PT-15 (separated dust) 95
A-35 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric ET-4 (unseparated dust) 97
A-36 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric ET-30 (unseparated dust) 98
A-37 Pressure Difference vs. Filtration Time for Cement
Dust and Fabric F-tor 5 (unseparated dust) 99
VI
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LIST OF FIGURES (cont.)
Figure Page
A-38 Pressure Difference vs. Filtration Time for Cement Dust
and Fabric ET-4 (unseparated dust) 100
A-39 Pressure Difference vs. Filtration Time for Coal Dust
and Fabric ET-4 (unseparated dust) 101
A-40 Pressure Difference vs. Filtration Time for Coal Dust
and Fabric ET-30 (unseparated dust) 102
A-41 Pressure Difference vs. Dust Load for Cement Dust and
Fabric ET-4 (unseparated dust) 103
A-42 Pressure Difference vs. Dust Load for Cement Dust and
Fabric ET-30 (unseparated dust) 104
A-43 Pressure Difference vs. Dust Load for Cement Dust and
Fabric F-tor 5 (unseparated dust) 105
A-44 Pressure Difference vs. Dust Load for Cement Dust and
Fabric PT-15 (unseparated dust) 106
A-45 Pressure Difference vs. Dust Load for Coal Dust and
Fabric ET-4 (unseparated dust) 107
A-46 Pressure Difference vs. Dust Load for Coal Dust and
Fabric ET-30 (unseparated dust) 108
A-47 Efficiency vs. Filtration Rate for Cement Dust and
Fabric ET-4 (unseparated dust) 109
A-48 Efficiency vs. Filtration Rate for Cement Dust and
Fabric ET-30 (unseparated dust) 110
A-49 Efficiency vs. Filtration Rate for Cement Dust and
Fabric F-tor 5 (unseparated dust) Ill
A-50 Efficiency vs. Filtration Rate for Cement Dust and
Fabric PT-15 (unseparated dust) 112
A-51 Efficiency vs. Filtration Rate for Coal Dust and
Fabric ET-4 (unseparated dust) 113
A-52 Efficiency vs. Filtration Rate for Coal Dust and
Fabric ET-30 (unseparated dust) 114
A-53 Efficiency vs. Dust Load for Cement Dust and Fabric
ET-4 (unseparated dust) 115
A-54 Efficiency vs. Dust Load for Cement Dust and Fabric
F-tor 5 (unseparated dust) 116
Vti
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LIST OF FIGURES (cont.)
Figure Page
A-55 Efficiency vs. Dust Load for Cement Dust and Fabric
F-tor 5 (unseparated dust) 117
A-56 Efficiency vs. Dust Load for Cement Dust and Fabric
PT-15 (unseparated dust) 118
A-57 Efficiency vs. Dust Load for Coal Dust and Fabric
ET-4 (unseparated dust) 119
A-58 Efficiency vs. Dust Load for Coal Dust and Fabric
ET-30 (unseparated dust) 120
A-59 Ducts/Canals in Coal and Cement Dust 121
A-60 Types of Dust Filtration 122
A-61 Surfaces of Clean Fabric WT-201 (wool fiber) 123
A-62 Clean Fabric WT-201 124
A-63 Surfaces of Clean Fabric BT-57 (cotton fiber) .... 125
A-64 Clean Fabric BT-57 126
A-65 Surfaces of Clean Fabric WBT-210 (wool-cotton fiber) . 127
A-66 Clean Fabric WBT-210 128
A-67 Surfaces of Clean Fabric ET-4 (polyester fiber) ... . . 129
A-68 Clean Fabric ET-4 130
A-69 Surfaces of Clean Fabric ST-1 (glass fiber) 131
A-70 Clean Fabric ST-1 132
^
A-71 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type Wt-201 (wool-high velocity) .... 133
A-72 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WT-202 (wool-high velocity) .... 134
A-73 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WT-203 (wool-high velocity) .... 135
A-74 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WT-207 (wool-high velocity) .... 136
A-75 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type BT-57 (cotton-high velocity) . . . 137
A-76 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type BWA-1539 (cotton-high velocity) . . 133
A-77 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WBT-206 (wool/cotton-high velocity) 139
van
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LIST OF FIGURES (cont.)
Figure Page
A-78
A- 79
A-80
A-81
A-82
A-83
A-84
A-85
A-86
A- 87
A-88
A-89
A-90
A-91
A- 92
A-93
A-94
A- 95
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WBT-210 (wool /cotton-high velocity)
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-1 (polyester-high velocity) . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-2 (polyester-high velocity) . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-3
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-4 (polyester-high velocity) . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-30 (polyester-high velocity) . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-1 (glass-high velocity)
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-13 (glass-high velocity) ....
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-41 (glass-high velocity) ....
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WT-201 (wool -low velocity)
Dependence of Pressure Drop Vs. Filtration Rate for
Pure Fabric Type WT-202 (wool -low velocity)
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WT-203 (wool -low velocity)
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type BT-57 (cotton- low velocity) ....
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type BWA-1539 (cotton-low velocity) . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WBT-210 (wool /cotton-low velocity) .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-1 (polyester-low velocity) . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-2 (polyester-low velocity). . . .
Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-3 (polyester-low velocity) . . .
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
IX
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LIST OF FIGURES (cont.)
Figure Page
A-96 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-4 (polyester-low velocity) ... 158
A-97 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-30 (polyester-low velocity) . . 159
A-98 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-1 (glass-low velocity) 160
A-99 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-13 (glass-low velocity) .... 161
A-100 Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ST-41 (glass-low velocity) . . . . 162
3 Particle Size Distribution of Tested Dusts 163
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LIST OF TABLES
Tab!e Page
1 Fabric Parameters 13
2 Particle Size Distribution of Test Dusts 14
3 Permeability of Filtration Fabrics 18
4 Filtration Resistance for Separated Dusts 19
5 Filtration Resistance for Unseparated Dusts 20
6 Optimum Gas Loading of Fabrics 22
7 Structural Parameters of Wool Fiber Fabrics 31
8 Structural Parameters of Cotton Fiber Fabrics 37
9 Structural Parameters of Polyester Fiber Fabrics .... 45
10 Structural Parameters of Glass Fiber Fabrics 51
11 Comparison of Dust Parameters ..,,,.,,,,,,, 58
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ACKNOWLDEGMENT
As authors, we thank each employee of the United States Environmental
Protection Agency who participated in this endeavor for their contribution
and help. Special thanks for help and support throughout the program
are extended to our Project Officer, Dr. James H. Turner.
XII
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SECTION I
CONCLUSIONS
The test measurements on filtration fabrics and mathematical analysis of
the results led to the following initial conclusions:
0 Depending on the conditions of the experiments, dust filtration
processes can be classified as one of three types:
Type I - the initial phase, starting with unused fabric and
terminating when the pressure drop reaches a predetermined
level;
Type II - the middle phase, terminated when the residual dust load
in the fabric remains constant after each cleaning cycle; and
Type III - the last phase, characterized by the fabric being fully
filled with dust and having a stabilized value of pressure
drop and residual dust load immediately after cleaning.
0 Although laboratory testing of Filtration Type I is not comparable
to industrial-scale testing, it does provide data about filtration
mechanisms which are important to further theoretical exploration.
0 Excessive filtration velocity can destroy the dust cake structure
through creation of ducts/canals, lowering the dust removal
efficiency.
0 Further research is required to determine the effects of electro-
static properties on dust filtration processes.
More specific conclusions on each aspect of this work are included in the
individual sections.
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SECTION II
RECOMMENDATIONS
Further research is necessary under the program. It should emphasize
the physical aspects of dust filtration processes and provide a sta-
tistical presentation of empirical data.
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SECTION III
INTRODUCTION
INVESTIGATION OF DUST FILTRATION PROCESSES
Fabric filters are widely used in industrial dust removal systems, the
types varying by production processes. In the cement, lime, and gypsum
industry, they have been used in both cool and hot gas filtration pro-
cesses, working at temperatures below and above 140° C, respectively.
Fabric filters have the following advantages for use in production
processes:
0 High efficiency of dust collection;
0 High fractional efficiency for fine dust particles;
0 Low sensitivity to physical and chemical changes in the dust;
0 Collection of dry matter of the same size distribution as in the
inlet gas;
0 Simple design, capable of operation without special training;
0 Reliability of operation;
0 Possibility of multichamber construction for flexibility in
meeting size requirements.
These advantages of fabric filters outweigh their disadvantages:
0 Sensitivity to the humidity of gases, especially when the dew-
point is exceeded;
0 High filtration resistance;
0 High operating costs because of periodic filtration bag replace-
ment.
Though known for many years, the dust filtration process for the removal
of dust particles from a gas stream has not been fully studied. In this,
1t differs from the air filtration process which has a theoretical base.
An increasing amount of research into dust filtration problems is being
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conducted in the macroscopic range, but only a few studies are concerned
with the microscopic or molecular range. Though the results of such
research represent only a part of the needed information, they are
important to the further study of filtration processes.
Analysis of the published data on the dust filtration process leads to
the following conclusions:
0 The dust filtration process is more complicated than that of air
filtration; the use of empirical data for theoretical research
into the former is therefore more difficult.
0 Empirical data indicate closely defined relationships between
dusts and fabrics which can be generalized.
0 Available dust cake theory, though giving general information on
changes in hydraulic resistance, does not consider parameters of
the dust cake structure.
° Application of classic theory of filtration to dust filtration
conditions is not justified because of quite different process
parameters.
0 At present we have no theoretical explanation of several peculiar-
ities of the dust filtration process; this leads to inconsisten-
cies between empirical expositions and fact, especially for
certain combinations of dust and fabrics.
Consequently, the selection of types of dust and of fabric for parti-
cular filtration parameters requires laboratory-scale, pilot-scale, and
sometimes industrial-scale experimentation. The most important require-
ments relate to the cleanliness of emitted industrial gases. The need
for further research on the dust filtration process is related to the
fact that it seems to be the most economic method for control of sources
of large amounts of air pollution.
The well-known electrostatic precipitators probably will never achieve
as high an economic effectiveness as that of dust filtration processes
(particularly for fine particle collection) because of the specificity
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of the electrostatic method of dust collection. This method is limited
by many factors; in some cases, its use requires prior treatment of
gases in a cooling tower, or an increase in the area of the collecting
electrodes. Although the application of prior gas cooling occurs in
some fabric filtration installations (because of the temperature limita-
tions of the filtration materials), research on new filtration materials
will eliminate this requirement, an achievement not possible for electro-
static precipitators.
Wet scrubbing has been limited by some technological factors (e.g.,
conditions in the cement and food industries), but it generally seems to
be the best solution from an investment, as well as an operating, point
of view.
There is increasing concern in the legislatures of many countries as to
dust emission (and particularly its physical and chemical properties,
fractional composition, etc.). The factors outlined above will be impor-
tant to the determination, in the near future, of what kind of filtration
devices are to be used. In this situation, continuing research into the
dust filtration process will become indispensable.
Accordingly, future research on the filtration processes should have two
purposes:
0 Dissemination of data on dry dust filtration by the use of filtra-
tion fabrics;
0 Determination of future objectives of research programs.
PROBLEMS IN DUST FILTRATION
The general qualitative parameters characterizing dust filtration fabrics
in industrial units are:
0 Mean dust removal efficiency;
0 Filtration resistance as a function of the dust layer;
0 Filtration velocity.
-------
These parameters are not concerned with any classification as to quality
of the structure of fabrics, but only to the types and kinds of fabric
and of the gas and dust media in which the filtration process is tested.
The only quantitative parameter which characterizes the structure of
fabrics resulting from their manufacture (except the technical conditions
of production) is permeability, which defines the magnitude of gas flow
through the fabric, measured at a given static pressure (0.5 inch of
water for U.S. standards and 20 mm of water for Polish standards).
It is evident that permeability is not an adequate structural parameter
for describing either clean or dusty gas flow. For that reason, it is
necessary to establish quantitative definitions of parameters for fabric
structure. Research experience and methodology for air filtration are
not applicable to dust filtration fabrics.
The present inadequate knowledge of the dust filtration process and the
lack of quantitative and qualitative definitions make it difficult at
present to design appropriate structures for filtration fabrics (e.g.,
those of known performance characteristics under defined operating condi-
tions).
Accordingly, the determination of optimal structural designs must be
done by testing fabrics for:
0 Thermal resistance;
0 Dynamic resistance;
0 Mechanical strength;
0 Water absorption, capacity, etc.
The most useful results would be obtained from large-scale industrial
test measurements under all conditions of filtration and regeneration.
However, this is not an economical method, and it probably will be
reserved for special dust removal problems.
-------
The primary dust filtration research need at present ts for the quanti-
fication of structural parameters so as to permit meaningful testing and
classification of filtration fabric structures.
A secondary need is to examine the electrostatic properties of dust and
fabrics as a means of increasing dust collection efficiency. This
requires an understanding of the basic electrodynamic processes.
From the macroscopic/economic point of view, the useful solutions emerge
from consideration of the entire complex of physical and chemical pro-
cesses of dust filtration.
RESEARCH OBJECTIVES
The basic objectives of the program financed by the EPA and conducted by
the Institute of Cement Building Materials in Opole were established as:
0 A viable description of the effects of structural parameters on
pressure drops, using gas flow through clean filtration fabrics.
0 A viable description of the effects of structural parameters of
the fabric and of the dust cake on pressure drops during the
filtration process.
0 A viable description of the dependence between dust collection
efficiencies and the variables of the dust filtration process.
0 Testing, by mathematical modeling, of those fabric structures
with the best filtration properties.
Total program research will include the following:
0 Laboratory testing, including that of dust and fabrics;
0 Large-scale testing;
0 Auxiliary studies;
0 Application of mathematical methods including modeling.
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GENERAL PROGRAM
Laboratory Testing
Laboratory testing was accomplished on four kinds of filtration fabrics
and two types of dust, measured under the following conditions:
0 Dust concentrations in the afr at inlet of the test chamber:
10 g/m3 ± 10%.
0 Dust loadings of filtration area of:
100 g/m2
400 g/m2
700 g/m2
with AP < 250 mm of water.
0 Gas loadings of the filtration area of:
3 2
60 m /m /hour
80 m3/m2/hour
120 m3/m2/hour.
0 Humidity of dispersion medium (not adjustable):
RH = 40% ± 10.
0 Temperature of dispersion medium: 20° to 30° C.
0 Dispersion medium: atmospheric air.
0 Pressure: atmospheric pressure.
Large-Scale Testing
Large-scale tests were scheduled using filtration bags with an operating
length of 3000 mm and the same dusts used in laboratory testing. Test
conditions were:
Dust concentration in the air at the inlet of the test chamber:
10 g/m3 ± 10%.
Dust loading of filtration area of:
500 g/m2
700 g/m2
with AP < 250 mm of water.
Gas loadings of the filtration area of:
60 m3/m2/hour
80 m3/m2/hour.
8
0
-------
0 Humidity of dispersion medium (not adjustable):
RH 40% ± 10.
0 Temperature of dispersion medium: 20° to 30° C.
0 Dispersion medium: atmospheric air.
0 Pressure: atmospheric pressure.
Definition of Structural Parameters for Fabric
Research for the definition of structural parameters for fabric included
the following methods:
0 Analytical,
0 Measurement,
0 Experimental.
Measurements and analyses concerned and included:
0 The geometry of the spatial structures of fabrics,
0 The technological parameters and production variables of fabrics
and fabric structures,
0 The technological parameters and production variables of threads
and filaments,
0 Microscopic tests, etc.
The parameters defined by analyses and measurements under atmospheric
air flows were evaluated experimentally. Study was of four types of
filtration fabrics, all manufactured in Poland and each differing as to
raw material, filament diameter, weave, etc. A literature search was
included in this program.
Definition of Structural Parameters for Dust Layers
Industrial polydispersed dust layers used in the testing program were
characterized by particular physical and chemical properties. The
research program for dust layers will be conducted in the same manner as
that for fabrics, using the following methods:
-------
0 Analytical,
0 Measurement,
0 Experimental.
Testing of Electrostatic Properties of Dusts and Fabrics
Determination of the electrostatic value of dusts and fabrics was accom-
plished using the same materials for both laboratory and large-scale
testing.
Testing included:
0 Electrification of dusts by the Kunkel-Hansen method,
0 Determination of the influence of the gas medium on dust
electrification,
0 Determination of the specific resistance of dust layers,
0 Determination of the kinetics of the fabric electrification pro-
cess during both clean and dusty air flows,
0 Determination of the specific resistance of fabrics (superficial
and through the fabric), and
0 Determination of the other electrostatic effects during the dust
filtration process.
DETAILED PROGRAM FOR FIRST PHASE
Laboratory Tests
0 Completion of the entire testing program and compilation and
preliminary analysis of the results.
0 Completion of auxiliary tests on fabrics for definition of basic
technological and production parameters, and
0 Completion of auxiliary tests on dusts for determination of
physical and chemical properties.
10
-------
Definition of Structural Parameters for Fabrics
0 Selection of test fabrics and definition of their primary and
derivative parameters, both technological and production related,
0 Determination of the hydraulic characteristics of test fabrics
during clean air flow with maximum filtration velocities, and
0 Compilation and preliminary analysis of the results.
Definition of the Structural Parameters of Dust Layers
0 Determination of the normal range of dust pulverization, and
0 Compilation and preliminary analysis of the results.
Definition of Characteristic Properties of Dusts and Fabrics
0 Definition of electrification, by the Kunkel-Hansen method, of
cement and coal dusts;
0 Determination of the specific resistance of dust layers;
0 Definition of the resistivity, both superficial and through the
fabric, for the following filtration fabrics:
ET-30
ET-4
F-tor 5
PT-15;
0 Summary and preliminary analysis of the results.
FABRIC AND DUST SELECTION
Four types of filtration fabric, differing as to spatial structure, were
selected for use in the major part of the testing under Project No.
5-553-3. These selected fabrics are produced from the following raw
>
materials:
0 Polyester (staple fiber):
Fabric ET-30 (EWA-1540)
Fabric ET-4
0 Polyester (continuous filament)
Fabric F-tor 5
11
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0 Polyamide (continuous filament)
Fabric PT-15.
Technical characteristics of these fabrics are shown in Table 1.
The following were selected as test dusts:
0 Cement dust,
0 Coal dust.
These industrial dusts were selected because of their chemical compo-
sition and their uniform particle size. Samples for testing were taken
from appropriate points in the production processing line.
The selection of dust samples is dependent on various physical and
chemical properties. Instead of testing material as sampled, testing
under this project, in accordance with suggestions from Dr. James H.
Turner, EPA Project Officer, was of only those dust samples containing
no more than 10 percent by weight of particles with diameters greater than
20 ym. For laboratory testing, this separation was done by use of the
ALPINE separator. For the large-scale tests, the dusts will be presep-
arated and prepared by subcontractors. The characteristics of the test
dusts before and after separation are shown in Table 2 and Figures A-l
and A-2.
12
-------
Table 1. FABRIC PARAMETERS
PARAMETER
1
Width of fabric
Kind of yarn: warp
fill
Thread count in
10 cm: warp
fill
Fabric weight
Thickness -
(pressure "lOOg/cm )
Tensile strength,
less than: warp
fill
Elongation during
tension, no more
than: warp
fill
Permeabi 1 i ty
Weave
Finishing
UNIT
2
cm
g / m2
mm
KG/ 5cm width
KG/5cm width
%
%
m /m min
at 20 mm H?0
-
FABRICS
ET-4 ET-30 F-tor 5 PT-15
PS*
3
as required
BOTexZ x 2S
ISOTex Z
180j5
126-5
450-31
_
220
260
70
50
18-24
V-z
steaming
Measured
4
36
45,21Tex x 2
178,25 Tex
180
126
428 .1
0.92
240
310
51
35
20.73
1 z
steaming
PS*
5
140^4
21TexZ x 2S
21TexZ x 2S
477^10
276-6
365^25
-
250
130
6
50
12-18
2 ,
1 Z
thermal
stabiliza-
tion,
washing
Measured
6
135
22,15Tex x 2
21,99Tex x 2
488
274
361.6
0.74
323
182
60
48
7.54
2 z
thermal
stabiliza-
tion,
washing
PS*
7
140^4
Td 125/2.
Td 250/1
540^12
376-12
271-13
-
346
276
20
30
-
2
crude
Measured
8
140
Td 136,37
Td 253,52
528
360
307,5
0.50
310
225
37
15
14.6
2
crude
PS*
9
85±1
Td 210/1
Td 210/1
564il2
360-1 1
272^14
-
300
200
60
40
-
3
3
stabilized
Measured
10
85
Td 228,43
Td 233,77
545
363
247
0.39
336
233
43
28
3.65
3
3
stabilized
*Polish standards
-------
Table 2. PARTICLE SIZE DISTRIBUTION OF TEST DUSTS
a. Before separation
Range of
Particle size
in vim
< 5
5 - 10
10 - 20
20 - 30
30 - 60
> 60
Percent by weight
Cement dust
12 - 18
12 - 20
13 - 22
11 - 14
27 - 22
25-4
Coal dust
9.5
15.0
25.5
16.0
19-5
14.5
b. After separation
Range of
Percent by weight
r a i u i v* i c *> i i.c
in urn
< §
5-10
10 - 20
> 60
Cement dust
26 - 33
25 - 37
44 - 27
5 - 3
Coal dust
26.0
42.0
30.2
1.8
14
-------
SECTION IV
LABORATORY TESTING OF FILTRATION
EQUIPMENT AND PROCEDURES
Laboratory testing of selected filtration fabrics was conducted on a
stand (illustrated in Figure 1) specially designed by the I.P.W.M.B.
and adapted for the testing of flat fabric specimens under ambient air
conditions.
Figure 1. Illustration of laboratory stand.
This stand includes the following (see Figure 2):
0 Testing chamber,
0 Rotameter for measuring flow intensity,
0 Needle valve to control flow intensity,
0 Vibrato-injecting dust feeder,
0 Micromanometer to measure pressure drop, and
0 Vacuum pump.
15
-------
FLOW CONTROL VALVE.
;INCLINED MANOMETERS
FILTER TEST STAND
Figure 2. Diagram of the Laboratory Test Stand.
16
-------
The testing chamber, which is the main part of the stand, is equipped with:
0 Diffuser at the inlet end,
0 Fabric specimen table, and
0 Control filter table at the outlet end.
o
A round fabric specimen of 100 cm test area was positioned in the middle
of the table, supported by wire net screening (4.0 cm along one side).
In testing, dusty air flows through the fabric from the top downward,
with the inlet diffuser providing a uniform flow throughout the entire
test area of the fabric. After passing through the fabric specimen, the
air then passes through a control filter of soft batting and paper (a
2
disc with a 200-cm test area). The control filter is positioned on the
table at the outlet end, supported by wire net screening (1 cm along one
side).
Average dust collection efficiency was determined by weighing the fabric
specimen and the control filter and then applying the following equation:
where G = weight (grams) of dust collected on the fabric,
G = weight (grams) of dust collected on the control filter,
G = weight (grams) of dust fed into the testing chamber.
c.
During the test run, measurements were recorded for 72 hours of the tem-
perature and humidity of the ambient air.
With this stand, the following data can be obtained:
° Mean filtration efficiency,
0 Hydraulic characteristics of filtration materials during clean
air flow,
0 Increases in hydraulic resistance during dusty air flow, and
0 Saturation degree of filtration materials.
17
-------
Though specially designed for the laboratory testing of woven filtration
fabrics, this stand can also be used for laboratory testing of other
filtration materials (e.g., felt).
RESULTS AND DISCUSSION
The results of the laboratory tests conducted under this project are
shown in Figures A-3 through A-34. A table presenting these results
will be included in the final report. Because studies are continuing of
structural parameter definitions of filtration fabrics and dust layers,
Section IV of this interim report addresses the results displayed in
Table 1 only partially or without conclusions.
Permeability is generally agreed to be one of the more important indices
for characterizing a pure structure. The results of testing of permea-
bility are contained in Table 3.
Table 3. PERMEABILITY OF FILTRATION FABRICS (In m3/m2/minute)
ET-4
20.70
ET-30
7.54
F-tor 5
14.60
PT-15
3.65
Table 4 shows the effect of differences in fabric and in dust on filtra-
tion resistance as measured by final pressure drop readings for the types
of fabrics and dust layers tested.
The filtration resistance of fabric (as measured by pressure drop) seems
to have no functional correlation to its permeability. The permeability
of fabric F-tor 5 is twice that of fabric ET-30, but its filtration resis-
tance reaches an approximately equal level. These fabrics have other
similarities, such as the number of threads per 10 cm, the thickness of
the yarn, and a weave using two threads as weft and warp in the plait (as
contrasted to the skew weave of fabrics ET-4 and PT-15 which uses only
18
-------
Table 4. FILTRATION RESISTANCE (in mm hUO) FOP. SEPARATED DUSTS
(Dust concentration of C = 10 g/m3 and L = 300 g/nr)
Gas loading
of filtra-
tion area
rrrVm2/hr
60
80
120
Kind
of dust
Cement
Coal
Cement
Coal
Cement
Coal
Kind of fabric
ET-4 ET-30 F-tor 5 PT-15
20
29
35
48
68
93
35
40
52
65
103
140
33
40
55
72
128
160
47
72
70
88
178
208
one yarn). But fabrics F-tor 5 and ET-30 differ as to type of fiber and
finish, ET-30 being of staple fiber and F-tor 5 of continuous filament.
The conclusion is that fabrics of continuous filament have a faster
build-up of dust and a slightly higher filtration resistance than do
those of staple fiber.
As to the effect of type of dust on filtration resistance (for size dis-
tribution of MMD-7.5 ym), Table 4 shows that the latter is higher for
coal dust than for cement dust for all fabrics tested. This finding
probably reflects the following:
0 A correspondence between construction and shape of dust particles
and the differing forms of dust cake structure,
0 Differences in the penetration processes of dust particles inside
fabric filter structures, and
0 Different effects of electrostatic forces.
Because they are of interest, the results, obtained by similar research
performed by I.P.W.M.B. on unseparated dusts and dust concentration C =
30 g/m3, are shown in Table 5 (and are plotted in Figures A-35 through
A-58).
19
-------
Table 5. FILTRATION RESISTANCE (in mm H20) FOR UNSEPARATED DUSTS
(Dust concentration of C = 30 g/m3 and L = 300 g/m2)
Gas loading
.^ ^ ^ «£ T -- ^
of filtra-
tion area
60
80
120
I/ _j
Kind
of dust
Cement
Coal
Cement
Coal
Cement
Coal
Kind of fabric
ET-4
12
13
25
22
45
36
ET-30
20
17
42
29
84
'66
F-tor 5
20
--
40
78
--
PT-15
26
20
56
--
100
79
In the case of unseparated dusts with particles of similar size (Table 2,
MMD = ca. 20 pro), an increased effect of the kind of fabric on filtration
resistance was noted. Higher filtration resistance occurred in cement
dusts. Filtration efficiency, following gas loading, is charted by type
of fabric and of dust in Figures A-19 through A-34. For comparison with
similar effects for unseparated dusts, the results of the I.P.W.M.B.
tests are shown in Figures A-47 through A-58.
Considering the effects on filtration efficiency of types of dust and of
fabrics in any given filtration situation, it was noted that:
0 For all combinations of dusts and fabrics, with dust loads of
2 2
400 g/m and 700 g/m , increases in gas loading corresponded to
decreases in filtration efficiency.
2
0 With dust loading of 100 g/m , increases in gas loading corre-
sponded to increased filtration efficiency (very small, about
0.1%) for the following combinations:
ET-30 and cement dust
PT-15 and cement and coal dusts.
20
-------
p
0 For fabric F-tor 5 with coal dust load of 100 g/m , gas loading
3 2
at 80 m /m /hour resulted in a minimum level of filtration
efficiency.
0 Fabric ET-4 in combination with both cement and coal dusts
showed changes in filtration efficiency to be closely related
o p
to changes in gas loading, starting from gas load of 80 m /m /
hour. Also noted for this fabric was dust cake breaking and
the formation of ducts/canals (see Figures A-27, A-31, A-53
-------
Table 6. OPTIMUM GAS LOADING OF FABRICS
Fabric
ET-4
ET-30
F-tor 5
PT-15
Optimum gas loading, q
32 "
m /m /hour
Cement dust
80
120
60
120
Coal dust
60
60
60
80
These are optimum gas loadings for Dust Filtration Type I. Large-scale
testing under Dust Filtration Type III will use fabrics containing residual
dust so that optimum gas loadings may be different.
A full analysis of the results will be prepared following large-scale
testing and investigation of electrostatic effects.
CONCLUSIONS
0 Laboratory testing was of flat fabric specimens under Dust Filtration
Type I (unused fabric with no residual dust and no cleaning).
0 Though not applicable to Dust Filtration Type III (industrial-
scale) testing, Type I test results provide knowledge of
particular filtration mechanisms.
0 Abnormalities in the n = f(q ) function are caused by electro-
static effects.
22
-------
SECTION V
BASIC RESEARCH ON A MODEL FOR DUST FILTRATION
INTRODUCTION
Classic filtration theory, first developed by Langrriuir, was later ex-
panded to include various filtration media and processes in order to
determine optimum filtration structures (fiber filters) for high-effi-
ciency atmospheric air filtration where dust concentration is low (cor-
responding to real dust concentrations in atmospheric air of from 0.005
to 20/30 mg/m ). The basic physical model was of an isolated elemental
fiber placed in a stream of continuously flowing gas. Observing the
flow of gas past the isolated fiber, the following basic mechanisms
were identified as indicators of the efficiency of the filtration pro-
cess:
0 Interception,
0 Inertia! contact, and
0 Diffusion.
Further studies, taking into consideration interferential effects (e.g.,
the influences of adjacent fibers and of aerosol poly-dispersion) indi-
cated other filtration mechanisms, such as electrostatic forces, thermo-
phoresis, etc.
The derivation of empirical or semiempirical equations suitable for ap-
lication to industrial operations necessitated simplications (e.g.,
omission of some of the filtration mechanisms). Thus, some of the re-
sults were of limited applicability.
For organizing both theoretical and experimental studies of air filtra-
tion with fiber filters, two types of filtration are defined:
0 Stationary filtration, which includes all processes taking place
between the dust particles and the clean filtration structure;
and
23
-------
0 Nonstatlonary filtration, which includes those processes occur-
ring between the filtration structure and the "settled" adjacent
dust particles.
Stationary filtration is the first phase of the complete filtration pro-
cess. Nonstationary filtration occurs subsequently when the filtration,
structure is filled with dust particles. The lower the dust concentra-
tion in the dispersed medium, the longer the duration of fiber utiliza-
tion and the longer the duration of the stationary filtration phase.
For dust filtration, conditions are quite different. In dust filtration,
there is a much greater particle concentration (50 to 60 g/m ), with
variation in shape and in physical and chemical properties often present.
The construction of the spatial structure of the filtration media is
another very important differentiation between air and dust filtration
processes. Generally, a pure filtration medium structure is not a char-
acteristic of the dust filtration process; rather the structure becomes
filled with dust.
It is difficult to classify portions of the dust filtration process
solely as to the occurrence and duration of stationary or nonstationary
filtration phases. It is possible, however, to identify distinct
stages in the complete process. These are designated as Dust Filtration
Types I, II, and III, as depicted in Figure A-60.
Dust Filtration Type I
This is the initial phase of the complete process, when the fabric first
begins operation as a filtration medium. This phase ends when the pres-
sure drop characterizing the dust-to-fabric ratio reaches a predetermined
level. This phase includes:
0 Stationary filtration during the initial capture of dust parti-
cles (corresponding to classic filtration theory),
0 Nonstationary filtration when the fabric structure is being
filled, and
24
-------
0 "Ductive" filtration when the dust cake is being formed and as it be-
comes a filter layer for successive impinging dust particles.
Dust Filtration Type II
This second phase continues until the fabric is fully filled with dust
(i.e., a stabilized quantity of residual dust remains in the fabric
structure after its regeneration).
The duration of Dust Filtration Type II depends on the properties of
both dust and fabric and on the intensity of regeneration. This phase
includes:
0 Nonstationary filtration,
0 "Ductive" filtration.
Dust Filtration Type III
This phase occurs when a stable level of filling of the fabric by dust
has been reached and when the pressure drop returns to a constant level
during regenerations. As for Dust Filtration Type II, this phase
includes:
0 Nonstationary filtration,
0 "Ductive" filtration.
But Type III differs from Type II in that Type II lasts until the fabric
structure is filled with dust to a predetermined amount functionally re-
lated to the pressure drop; Type III occurs thereafter.
Particular phases of the dust filtration process correspond to predeter-
mined values in the dust-fabric ratio for:
0 Pressure drop,
0 Quantity of dust.
The following conditions are postulated:
0 Pure fabric structure is characterized by
25
-------
AP, where q = constant, q = 0, and L = 0.
where AP is the pressure drop for a stated static gas loading of
q and dust loading q_ = 0
9 P 2
L = grams dust/m of fabric.
NOTE: In textile technology, an equivalent parameter is used,
such as permeability, which is defined by air flow inten-
sity (which affects pressure drop).
0 A fully filled structure is one bearing a certain amount of dust,
accumulated during the filtration process or retained during re-
generation but which is without a dust cake. This is character-
ized by:
AP,., where q = constant, q = constant, and L = I.,, the
characteristic value for fabric filled with dust.
0 A structure covered with dust is a fully filled structure with a
dust cake on its working face. This is described as:
AP. , where q = constant, q = constant, L = L = LN + L =
g/m of dust cake, and L = the characteristic value for
filtration structure covered with dust;
Lo LN + V
A pure structure characterizes the condition of the nonworking face of
the filter before the onset of Dust Filtration Type I. A built-up struc-
ture characterizes the end of nonstationary filtration and the duration
of "ductive" filtration during Dust Filtration Type III.
All the intermediate stages of Dust Filtration Types I and II need addi-
tional characteristic values, as, for example, LNR = built-up fabric
after regeneration.
For describing all these intermediate stages during experimentation and
to facilitate comparison of test results, the concept of "fabric-filling"
(with dust) is set forth according to:
26
-------
g _ !_
1 LN
where LN = fabric filling for a given regeneration schedule (Dust n'l-
tration Type III),
l^ = fabric filling at point i during Dust Filtration Types I and
II,
$.. = fabric filling amount for cycle i.
These definitions and characterizations of the dust filtration process
have particular physical significance and can provide means for rational
selection of experimental materials.
From a practical point of view, the most important dust filtration type
is Type III, under which the parameters determine hydraulic character-
istics and dust removal efficiency.
STUDY OF FILTER MEDIUM PARAMETERS
Introduction
Fabrics exhibit both spatial and superficial features of their structure.
These features result from the method of fabric manufacture, generally a
weaving of fill threads into the longitudinal warp threads. The result
is a spatial structure of the intersections of fill and warp threads.
Differences between fill and warp threads and in the configuration of
the weaving distinguish one weave from another and one type of fabrics
from another.
Fabrics are manufactured from:
0 Natural fibers such as wool and cotton;
0 Synthetic fibers such as elane, torlen, etc.;
0 Inorganic fibers such as glass;, and
0 Metallic fibers.
27
-------
A single fiber has a distinctive length, diameter, surface structure,
etc., all of which are important to basic filtration mechanisms. It
should be noted that when considering fiber structure, individual prop-
erties of the fiber can cause unexpected effects in the filtration pro-
cess.
From a technical point of view, the characteristic parameters of fabric
are:
0 The yarn count,[see ASTM D 1907], which determines the linear
density of the thread
M = n x In
m m
where n = number of weighed threads,
In = length of thread (straight),
m = mass of weighed threads.
0 Density of warp and fill as determined by the number of threads
along the warp and the fill.
0 Weave, which defines the way the threads are crossed.
These parameters affect the thickness of the fabric, its weight,
strength, elasticity, etc.
Additionally, the following structural parameters can be specified:
0 Relative packing of warp and fill,
0 Superficial packing of yarns,
0 Degree of packing of yarn within the fabric,
0 Thickness of fabric,
0 Porosity of fabric,
0 Measurement of open (interstitial) area, and
0 Observed volume of fabric.
It should be noted that the structure of filtration fabrics is suffi-
ciently variable that it is difficult to arrive at a standard classifi-
cation for all structures or even to compare one with another.
28
-------
The main purpose of this project is to define structural parameters and
to correlate them to technological parameters. For that reason, initial
efforts concentrated on investigating clean air flows through various
fabric structures.
Fabric Selection
The following Polish fabrics were selected for study:
0 Natural fiber fabrics:
0 Wool: WT-201, WT-202, WT-203, WT-207
0 Cotton: BT-57, BWA-1539
0 Wool/Cotton: WBT-208, WBT-210.
0 Synthetic fiber fabrics:
0 Polyester: ET-1, ET-2, ET-3, ET-4, ET-30.
0 Inorganic fiber fabrics:
0 Glass: ST-1, ST-13, ST-41.
Figures A-61 through A-70 are illustrations of the superficial structures
and sections across warp and fill for fabrics representative of those
listed above.
Equipment and Procedures
The study of a clean air flow through selected fabric structures was per-
formed for low and high values of gas loading. Measurements were taken
using the equipment described in Appendixes B-F.
For greater accuracy, the ASUKANIA im'cromanometer was used for low-value
air flow testing. The results of 30 measurement tests are shown in
Figures A-71 through A-100. Detailed protocols of these tests will be
included in the final report. The resultant definitions of structural
parameters of tested fabrics (using Polish standards) are shown in Tables
7 through 10 (at the end of this section).
Results and Discussion
The testing of air flow through pure filtration structures for high values
29
-------
of gas loading, with application of AP = f(q ) = f(v)(where v = average
velocity of the air flow before reaching the filtration structure),
proved the parabolic character of the function.
Also studied, on the basis of empirical data, was the variation in flow
velocity for particular classes of pressure drop, by application of the
X KOLMOGOROW test. After reduction of the variations measured, it was
proven that velocity variation is statistically normal, with a confi-
dence level of 0.01.
This fact substantiates the claim that an air flow through fabric is a
composite process, with a definite density function. An appropriate
mathematical explanation will be presented later (as part of the report
on the second phase of this project) because of its size. Further
studies in this area will be based on a large amount of statistical data
(from additional testing) pertinent to the following problems:
0 Functional dependences for particular kinds of fabric,
0 An analogy for structural measurements in the air flow process,
0 Correlation of technological and functional parameters of the
structure to its physical parameters.
Under high gas loading, changes of pressure drop, as a function of flow
velocity, indicate turbulent air flow through the filtration medium
structure. Under low gas loading, AP = f(v) curves are almost linear,
indicating a different type of air flow.
Conclusions
0 The flow of clean air through a filtration fabric structure is a
stochastic process.
0 In certain values of pressure drop, variations in air flow velocity
(measured in front of the fabric structure) are normally distributed.
0 Air flows differ under low and high gas loading values, having
differing definite physical aspects from the point of view of
spatial structure.
30
-------
Table 7. STRUCTURAL PARAMETERS OF WOOL FIBER FABRICS
CO
PARAMETER
1
Count of yarn Nmo
Average
Nmw
Average
Proportion between warp count
of yarn and fill count of yarn
Nmo/Nmw
Average
KIND OF FABRIC
WT-201
2
6.0335
5.9619
5.9416
6.4465
6.0950
6.0432
6.4622
5.4574
5.8286
5.9479
0.9984
0.4226
1.0887
1.1060
0.9039
WT-202
3
7.9713
8.6168
8.3543
7.9475
8.2224
9.4694
9.7966
9.9045
10.9660
10.0341
0.8419
0.8797
0.8435
0.7247
0.8225
WT-203
4
11.2913
10.6126
9.9406
10.6148
1 1 . 5705
10.7549
9.7087
10.6780
0.9759
0.9868
1.0239
0.9955
WT-207
5
6.7016
6.9662
6.9459
7.4919
7.0264
9.5156
9.8639
9.0570
10.2812
9.6794
0.7043
0.7062
0.7669
0.7287
0.7265
-------
Table 7 (continued)
1
Number of threads
on 10 cm no
Average
nw
Average
Yarn density (no/nw)
Average
Relative warp and fill
packing Zo
Average
2
124
124
121
120
122
95
95
94
96
95
1.3053
1.3053
1.2872
1 . 2500
1.2870
68.66
69.06
67.50
64.28
67.38
3
179
179
177
176
178
154
155
157
159
156
1.1623
1.1419
1.1274
1.0069
1.1096
86.23
82.94
83.29
84.91
84.34
4
196
195
176
189
177
173
153
168
1.1073
1.1272
1.1503
1.1283
79.33
81.40
75.91
78.88
5
170
171
171
173
171
165
168
161
167
165
1.0303
1.0179
1.0621
1.0359
1.0366
89.30
88.12
88.26
85.96
87.91
-------
Table 7 (continued)
OJ
CO
1
1 ' " - , . .- ._.-.-
Relative warp and fill
packing Zw
Average
Superficial packing
with yarn Zt
Average
Complete packing of
yarn in fabric Eo
Average
Ew
Average
2__
52.56
50.83
54.73
54.08
53.05
85.13
84.75
85.29
83.60
84.69
102.97
102.23
102.72
98.08
101.50
78.87
77.28
80.93
77.79
78.82
_==L_
68.07
67.35
67.85
65.29
67.14
95.60
94.43
94.63
94.76
94.86
125.79
121.85
121.53
121.03
122.55
105.17
103.25
104.79
103.64
104.21
__ 4
70.76
71.73
66.78
69.76
93.96
94.74
92.00
93.57
118.52
121.82
114.31
118.22
118.22
99.73
107.84
106.58
104.72
5
-i- -
72.74
72.74
72.77
70.82
72.27
97.08
99.76
96.80
95.90
97.39
126.78
125.80
126.92
122.66
125.54
116.06
116.04
114.32
112.32
114.69
-------
Table 7 (continued)
1
Distance between
axis of threads ]0
Average
Iw
Average
Diameter of yarns do
Average
dw
Average
2
0.8064
0.8064
0.8264
0.8333
0.8181
1.0526
1.0526
1.0638 -
1.0417
1.0527
0.5537
0.5569
0.5578
0.5356
0.5512
0.5533
0.5360
0.5822
0.5634
0.5587
3
0.5586
0.5586
0.5650
0.5682
0.5626
0.6493
0.6452
0.6369
0.5682
0.6249
0.4817
0.4634
0.4706
0.4824
0.4745
0.4420
0.4345
0.4321
0.4106
0.4298
4
0.5102
0.5128
0.5682
0.5304
0.5650
0.5780
0.6536
0.5989
0.4048
0.4174
0.4313
0.4178
0.3998
0.4146
0.4364
0.4169
5
0.5882
0.5848
0.5848
0.5780
0.5840
0.6061
0.5952
0.6211
0.5988
0.6053
0.5253
0.5153
0.5161
0.4969
0.5134
0.4408
0.4330
0.4520
0.4241
0.4375
CO
-------
Table 7 (continued)
CO
en
1
Length and width inside
FA between threads ko
Average
kw
Average
Free area
Average
2
Free area for 100 cm
Average
2
0.2527
0.2494
0.2686
0.2877
0.2646
0.4993
0.5173
0.4816
0.4783
0.4941
0.1262
0.1291
0.1293
0.1424
0.1318
14.87
15.22
14.72
16.40
15.30
3
0.0769
0.0852
0.0944
0.0858
0.0856
0.2073
0.2707
0.2048
0.2183
0.2253
0.0159
0.0201
0.0193
0.0187
0.0185
4.40
5.57
5.37
5.24
5.15
4
0.1054
0.0954
0.1369
0.1126
0.1652
0.1634
0.2172
0.1819
0.0174
0.0156
0.0297
0.0209
6.04
5.26
8.01
6.44
5
0.0629
0.0695
0.0687
0.0811
0.0706
0.1653
0.1622
0.1691
0.1747
0.1678
0.0104
0.0113
0.0116
0.0142
0.0119
2.92
3.24
3.20
4.10
3.37
-------
Table 7 (continued)
CO
1
Thickness of fabric
in millimeters
Average
Porosity of fabric
(by mercury)
Average
Apparent specific volume
of fabric 100 g/cm2
50 g/cm
Proportion of warp
and fill plaiting
Average
2
1.41
1.61
1.47
1.56
1.51
54.75
56.55
54.89
55.91
55 . 53
3.63
4.384
0.54
0.58
0.52
0.60
0.56
3
1.48
1.50
1.47
1.46
1.48
2.48
3.551
0.72
0.72
0.75
0.81
0.75
4
1.46
1.48
1.49
1.48
84.37
84.33
84.58
84.43
3.50
4.64
0.48
0.47
0.86
0.60
5
1.54
1.56
1.60
1.51
1.55
81.00
80.30
80.46
81.81
80.89
3.43
4.094
0.97
0.97
1.00
0.94
0.97
-------
Table 8, STRUCTURAL PARAMETERS OF COTTON FIBER FABRICS
OJ
PARAMETER
1
Count of yarn Nmo
Average
Nmw
Average
KIND OF FABRIC
BT-47
2
6.4191
6.1299
6.0999
5.9573
6.1516
6.3506
6.4935
6.1982
6.1918
6.3085
BWA-1539
3
30.4000
33.5962
33.9936
28.8108
31.7002
29.4086
27.5757
25.7970
26.9458
27.6818
WBT-208
4
16.7251
17.3094
17.7294
17.8849
17.4122
8.1086
6.7595
8.1710
7.4271
7.6166
WBT-210
5
28.0976
25.5213
28.1565
27.1990
23.5457
23.8865
24.9655
25.9103
12.4784
12.2585
11.8907
1 1 . 5486
12.0617
11.6877
11.9916
11.9882
-------
Table 8 (Continued)
CO
CO
1
Proportion between warp count
of yarn and fill count of yarn
Nmo/Nmw
Average
Number of threads on 10 cm
no
Average
nw
Average
2
1.0108
0.9440
0.9841
0.9631
0.9755
122
120
122
122
122
107
108
108
106
107
3
1.0337
1.2183
1.2686
1.0692
1.1475
371
371
372
376
-
373
216
215
218
220
217
4
2.0631
2.5608
2.1698
2.4081
2.3005
224
224
216
216
220
164
158
164
162
162
5
2.2517
2.0819
2.3688
2.5552
1.9521
2.0437
2.0819
2.1908
168
193
183
186
187
183
184
183
280
270
254
258
246
288
277
267
-------
Table 8 (Continued)
u>
IO
1
Yarn density no/nw
Average
Relative warp and fill
packing Zo
Average
Zw
Average
2
1.1402
1.1111
1.1296
1.1509
1.1330
60.18
60.58
61.74
62.47
'
61.24
53.07
52.98
54.22
53.25
53.38
3
1.7176
1.7256
1 . 7064
1.7091
1.7147
84.10
80.01
79.76
87.55
82.86
49.79
51.18
52.64
52.98
51.65
4
1.3659
1.4172
1.3171
1.3333
*
1.3583
68.46
67.31
64.13
63.83
65.93
78.34
82.65
78.01
80.85
79.96
5
0.6000
0.6655
0.7291
0.7209
0.7602
0.6352
0.6643
0.6836
39.71
47.75
43.82
44.57
48.18
46.81
43.03
44.84
107.61
112.65
99.00
103.26
96.33
114.56
106.82
105.75
-------
Table 8 (Continued)
1
Superficial packing
with yarn Zt
Average
Complete packing of
yarn in fabric Eo
Average
Ew
Average
2
81.31
81.47
82.49
82.46
81.93
90.44
90.02
92.38
93.12
91.49
79.49
80.25
81.50
80.40
80.40
3
92.02
90.24
90.42
94.15
99.71
118.33
115.36
115.68
115.68
116.26
69.37
69.72
71.32
71.32
75.03
4
93.17
94.33
92.11
93.07
93.17
121.96
127.05
115.50
117.72
120.56
103.41
106.79
102.37
104.79
104.34
5
104.60
106.61
99.44
101.81
98.10
107.75
103.68
103.14
71.93
85.24
80.51
81.79
84.80
83.20
82.14
81.37
140.83
148.55
128.56
134.16
128.02
151.35
141.23
138.96
-------
Table 8 (Continued)
1
Distance between
axis of threads To
Average
Iw
Average
. Diameter of yarns do
Average
2
0.8T97
0.8333
0.8197
0.8197
0.8231
0.9346
0.9259
0.9259
0.9434
0.9325
0.4933
0.5048
0.5061
0.5121
0.5041
3
0.2695
0.2695
0.2688
0.2659
0.2684
0.4630
0.4651
0.4587
0.4545
0.4603
0.2267
0.2157
0.2144
0.2329
0.2224
4
0.4464
0.4464
0.4630
0.4630
0.4547
0.6097
0.6329
0.6097
0.6173
0.6174
0.3056
0.3056
0.2969
0.2955
0.3009
5
0.5952
0.5181
0.5376
0.5376
0.5347
0. 5464
0.5435
0.5447
0.3571
0.3448
0.3984
0.3876
0.4065
0.3472
0.3676
0.3727
0.2358
0.2474
0.2356
0.2396
0.2576
0.2558
0.2501
0.2460
-------
Table 8 (Continued)
1
Diameter of yarn dw
Average
Length and width inside
FA between threads ko
Average
kw
Average
2
0.4960
0.4906
0.5020
0. 5024
0.4978
0.3264
0.3285
0.3136
0.3076
0.3190
0.4386
0.4353
0-4329
0-4410
0.4347
3
0.2305
0. 2380
0.2414
0. 2408
0.2377
0.0428
0.0538
0. 0544
0.0330
0. 0460
0.2325
0.2271
0.2173
0.2137
0. 2770
4
0.4777
0.5231
0.4757
0.4991
0.4939
0.1408
0.1408
0.1661
0.1675
0.1538
0.1320
0.1098
0.1340
0.1183
0.1233
5
0.3850
0.3885
0.3944
0.4002
0.3916
0.3978
0.3927
0.3929
0.3020
0.2771
0.2896
0.0040'
-
0.0149
0. 0095
ro
-------
Table 8 (Continued)
1
Free area
Average
Free area for 100 cm^
Average
Thickness of fabric
in millimeters
Average
2
0.1432
0.1420
0.1320
0.1356
0.1387
18.69
18.54
17.52
17.54
18.07
1.09
1.06
1.07
1.08
1.08
3
0.0099
0.0122
0.0118
0.0070
0.0102
7.98
9.75
9.59
5.84
8.29
0.50
0.51
0.49
0.52
0,51
4
0.0186
0-0155
0.0223
0.0198
0.0191
6.83
5.47
7.84
6.93
6.77
1.48
1.49
1.50
1.53
1.50
5
0.0012
0.0041
0.0027
0.57
1.90
1.24
1.08
1.10
1.10
1.08
1.09
1.09
1.09
CO
-------
Table 8 (Continued)
1
Porosity of fabric
(by mercury)
Average
Apparent specific volume 9
of fabric 100 g/cm
50 g/cm2
Proportion of warp
and fil 1 plaiting
Average
2
73.83
73.11
76.16
76.24
74.84
2.39
2.419
1.03
1.23
1.15
1.05
1.12
3
75.55
76.32
77.71
75.85
76.11
2.18
2.486
0.68
0.71
0.67
0.70
0.69
4
83.51
83.40
83.36
83.37
83.06
83.34
3.45
4.043
0.82
0.79
0.79
0.77
0.79
5
82.20
80.82
79.40
80.64
84.06
81.42
3.56
4.601
0.61
0.48
0.87
0.76
1.16
0.73
0.57
0.74
-------
Table 9. STRUCTURAL PARAMETERS OF POLYESTER FIBER FABRICS
en
PARAMETER
1
Count of year Nmo
Average
Nmw
Average
Proportion between
warp count of yarn
and fill count
Nmo/Nmw
Average
KIND OF FABRIC
ET-1
2
9.4897
9.7401
9.8545
9.6558
9.6558
5.0331
5.0749
5.9312
5.3777
5.3542
1.8855
1.8995
1.6615
1.7923
1 .8097
ET-2
3
10.6249
10.9467
10.5413
10.7829
10.7829
5.3376
5.5390
5.7394
5.5221
5.5345
1.9906
1.9763
1.8367
1.9954
1 .9498
ET-3
4
9.7466
10.0348
9.3603
9.7118
9.7118
5.1710
4.5130
4.7089
5.1487
5.8854
1 .8849
2.2235
1.9878
1.8851
1 .9953
ET-4
5
11.4172
10.8564
11.2745
11.0512
11.0512
5.3791
5.3791
5.8032
6.0520
5.6092
2.1225
1.8708
1.9428
1.7609
1 .9243
ET-30
6
24.0044
21.4031
22.5833
22,5727
22.5727
22.7111
22.7111
22.9240
21.9914
22.7459
1.0569
0.0569
0-9851
1.0140
0-9931
-------
Table 9 (continued)
en
1
Number of threads
on 10 cm no
Average
nw
Average
Yarn density no/nw
Average
Relative warp and
fill packing Zo
Average
2
185
200
196
186
192
141
141
140
139
141
1.312
1.4184
1 . 4000
1.3381
1.3671
81.69
87.60
84.92
81.47
83.92
3
183
184
182
184
183
96
93
95
94
95
1.9063
1.9785
1.9158
1.9574
1.9395
76.34
75.62
76.23
75.40
75.90
4
212
220
212
201
211
124
124
125
125
125
1 . 7097
1 . 7742
1 . 6960
1.6080
1.6969
92.35
94.44
94.22
87.76
92.19
5
177
176
176
176
176
124
120
124
125
123
1.4274
1 . 4667
1.4194
1 . 4080
1 . 4304
71.24
72.64
71.28
73.33
72.12
6
246
246
248
249
247
278
276
276
278
277
0.8849
0.8913
0.8986
0.8957
0.8926
68.28
72.32
71.43
71.72
70.94
-------
Table 9 (continued)
1
Relative warp and
fill packing Zw
Average
Superficial packing
with yarn It
Average
Complete packing of
yarn in fabric Eo
Average
Ew
Average
2
85.54
85.11
78.19
81.52
82.57
97.34
98.15
96.71
96.58
97.20
137.75
147.96
139.64
136.00
140.34
115.59
116.59
108.51
111.95
113.26
3
56.52
53.75
53.92
54.40
56.65
89.71
88.73
89.05
88.78
89.07
130.22
128.79
127.89
128.64
128. 89
76.54
72.86
73.82
73.35
74.14
4
74.16
79.40
78.34
74.92
76.71
98.02
98.86
98.86
96.93
98.18
155.75
164.90
160.64
148.00
157.32
101.18
106.06
106.11
102.21
103.89
5
72.72
71.55
70.00
69.10
70.84
92.16
92.22
91.38
91.76
91.88
123.13
125.10
120.68
121.98
122.94
97.67
96.31
95.11
95.14
96.06
6
79.33
77.67
80.61
80.61
79.56
93.44
93.82
94.46
94.52
94.06
91.66
95.40
94.46
95.78
94.33
105.03
104.72
105.48
107.31
105.64
-------
Table 9 (continued)
00
1
Distance between
axis of threads lo
Average
Iw
Average
Diameter of yarns do
Average
dw
Average
2
0.5405
0.5000
0.5102
0.5376
0.5221
0.7092
0.7092
0.7143
0.7194
0.7130
0.4415
0.4380
0.4332
0.4380
0.4377
0.6061
0.6036
0.5585
0.5864
0.5887
3
0.5464
0.5435
0.5494
0.5435
0.5457
1.0417
1.0753
1.0523
1.0638
1.0583
0.4172
0.4110
0.4188
0.4098
0.4142
0.5887
0.5780
0.5676
0.5787
0.5782
4
0.4717
0.4545
0.4717
0.4975
0.4739
0.8064
0.8064
0.8000
0.8000
0.8032
0.4356
0.4293
0.4444
0.4366
0.4365
0.5981
0.6403
0.6267
0.5994
0.6161
5
0.5650
0.5682
0.5682
0.5682
0.5674
0.8064
0.8333
0.8064
0.8000
0.8115
0.4025
0.4127
0.4050
0.4167
0.4092
0.5864
0.5962
0.5645
0.5528
0.5749
6
0.4065
0.4065
0.4032
0.4016
0.4045
0.3597
0.3623
0.3623
0.3598
0.3610
0.2775
0.2940
0.2862
0.2880
0.2864
0.2853
0.2814
0.2840
0.2900
0.2852
-------
Table 9 (continued)
1
Length and width
inside FA between
threads ko
Average
kw
Average
Free area
Average
2
Free area for 100 cm
Average
2
0.0990
0.0620
0.0770
0.0996
0.0844
0.1031
0.1056
0.1558
0.1330
0.1244
0.0102
0.0065
0.0120
0.0132
0.0105
2.66
1.87
3,29
3.43
2.81
3
0.1292
0.1325
0.1306
0.1337
0.1315
0.4530
0.4973
0.4850
0.4851
0.4801
0.0585
0.0659
0.0633
0.0649
0.0632
10.29
11.27
10.96
11.22
10.94
4
0.0361
0.0252
0.0273
0.0609
0.0374
0.2083
0.1661
0.1733
0.2006
0.1871
0.0357
0.0369
0.0395
0.0374
0.0374
1.98
1.14
1.25
3.07
1.86
5
0.1625
0.1555
0.1632
0.1515
0.1582
0.2200
0.2371
0.2419
0.2472
0.2366
0.0075
0.0042
0.0047
0.0122
0.0072
7.85
7.79
8.62
8.24
8.13
6
0.1290
0.1125
0.1170
0.1136
0.1180
0.0744
0.0809
0.0757
0.0697
0.0751
0.0096
0.0091
0.0089
0.0079
0.0089
6.56
6.18
6.27
5.25
6.07
-------
Table 9 (continued)
en
o
1
Thickness of fabric
in millimeters
Average
Porosity of fabric
(by mercury)
Average
Apparent specific «
volume of fabric 100 g/cm
50 g/cm
Proportion of warp
and fill plaiting
Average
2
1.44
1.40
1.35
1.32
1.38
76.66
76.06
76.34
75.32
76.10
2.71
3.059
2.32
1.81
1.77
1.79
1.92
3
0.84
0.83
0.82
0.81
0.83
61.82
60.60
63.53
63.04
62.25
1.065
0.901
1.63
1.39
1.39
1,425
1.46
4
1.44
1.45
1.42
1.45
1.44
79.50
79.66
81.97
79.97
80.28
2.82
4.14
0.94
- 0.94
0.95
0.96
0.95
5
0.91
0.92
0.94
0.93
0.93
67.74
65.84
67.66
66.64
66.97
2.10
2.14
3.04
3.44
3.41
3.21
3.28
6
0.62
0.61
0.62
0.60
0.61
54.75
54.89
55.91
54.24
54.95
1.98
1.913
3.86
3.61
3.11
3.07
3.41
-------
Table 10. STRUCTURAL PARAMETERS OF GLASS FIBER FABRICS
cn
PARAMETER
1
Count of yarn Nmo
Average
Nmw
Average
Proportion between warp count
of yarn and fill count of yarn
Nmo/Nmw
Average
. - - - ...in.
KIND OF FABRIC
ST-1
2
7.5362
7.6135
7.6079
7.7094
7.6168
7. 3200
7.5787
7.6400
7. 7599
7.5747
1.0295
1.0046
0.9958
0.9935
1.0059
.^^^^^^^^^-^ ^^^^-'^-'-H
ST-1 3
3
7.5398
7.5636
7.5695
7.5228
7.5489
7.4835
7.5221
7.6347
7.3860
7.5066
1.0075
1.0063
0.9915
1.0185
1.0060
l-.^^^^BW^^^^WM^K.^B^^^^^^BH^BM-mfel-P-ml
ST-41
4
7.5782
7.6193
7.5789
8.3057
7.7705
7.5173
7.4642
7.5844
7.7862
7.5880
1.0081
1.0208
0.9993
1.0667
1.0237
*^~~* ^^^^^^.^^^^^^^^^^a
-------
Table 10 (continued)
ro
1
Number of threads on 10 cm
no
Average
nw
Average
Yarn density (no/nw)
Average
Relative warp and fill
packing Zo
Average
2
239
240
239
238
238
110
108
108
112
no
2.1727
2.2222
2.2130
2.1250
2.1832
61.38
61.33
61.09
60.42
.61,06
3
363
364
364
364
364
159
156
154
159
157
2.2830
2.3330
2.3636
2.2893
2.3172
94.48
93.32
93.28
93.55
93.66
4
244
243
242
244
243
151
156
150
154
153
1.6159
1.5577
1.1633
1 . 5844
1.4803
62.48
62.07
61.97
59.69
61.55
-------
Table 10 (continued)
en
CO
1
Relative warp and fill
packing Zw
Average
Superficial packing
with yarn It
Average
Complete packing of
yarn in fabric Eo
Average
Ew
Average
2
28.66
27.66
27.55
28.34
28.05
72.45
72.03
71.81
71.64
71.98
92.51
92.04
91.58
90.53
91.66
42.79
41.46
41.35
42.56
42.04
3
40.97
40.09
39.29
41.24
40.40
96.74
96.00
95.92
96.21
96.22
139.95
140.12
139.73
138.95
139.69
61 . 39
60.09
59.03
61.68
60.55
4
38.82
40.26
39.40
38.91
39.35
77.05
77.14
76.57
75.38
76.54
93.85
93.41
92.96
90.52
92.62
58.16
60.17
57.60
57.75
58.42
-------
Table 10 (continued)
01
1
Distance between axis
of threads lo
Average
Iw
Average
Diameter of yarns do
Average
dw
Average
2
0.4184
0.4167
0.4184
0.4202
0.4184
0.9091
0.9259
0.9259
0.8928
0.9134
0.2568
0.2555
0.2556
0.2539
0.2555
0.2605
0.2561
0.2551
0.2530
0.2562
3
0.2755
0..2747
0.2747
0.2747
0.2749
0.6289
0.6410
0.6493
0.6289
0.6370
0.2567
0.2564
0.2563
0.2570
0.2566
0.2577
0.2570
0.2551
0.2594
0.2573
4
0.4098
0.4115
0.4132
0.4098
0.4111
0.6622
0.6410
0.6667
0.6493
0.6548
0.2561
0.2554
0.2561
0.2446
0.2531
0.2571
0.2580
0.2560
0.2527
0.2560
-------
Table 10 (continued)
en
en
1
Length and width inside
FA between threads ko
Average
kw
Average
Free area
Average
2
Free area for 100 cm
Average
2
0.1616
0.1612
0.1628
0.1663
0.1630
0.6486
0.6698
0.6708
0.6398
0.6573
0.1048
0.1080
0.1092
0.1064
0.1071
27.56
27.98
28.19
28.36
.28.02
3
0.0188
0.0183
0.0184
0.0177
0.0183
0.3712
0.3840
0.2942
0.3695
0.3547
0.0070
0.0070
0.0072
0.0065
0.0069
4.02
4.00
4.07
3.79
3.97
4
0.1537
0.1561
0.1571
0.1652
0.1580
0.4051
0.3830
0.4707
0.3966
0.4139
0.0623
0.0599
0.0645
0.0655
0.0631
22.95
22.67
24.06
24.62
23.58
-------
Table 10 (continued)
en
CTl
1
Thickness of fabric
in millimeters
Average
Porosity of fabric
(by mercury)
Average
Apparent specific ^
volume of fabric 100 g/cm
2
50 g/cm
Proportion of warp and
fill plaiting
Average
2
0.53
0.54
0.55
0.52
0.54
60.18
59.38
61.58
59.31
60.11
1.19
0.903
4.0
3.64
4.0
2.67
3.58
3
0.76
0.79
0.78
0.80
0.78
67.55
64.25
66.54
65.64
66.00
1.13
1.115
2.1
2.0
1.7
2.2
2.0
4
0.61
0.62
0.64
0.60
0.62
62.34
62.72
62.42
62.02
62.38
1.15
1.02
4.04
4.00
4.5
4.45
4.25
-------
STUDY OF DUST PARAMETERS
Introduction
i i
Dusts have been characterized by various parameters depending upon the
extent of data availabJe. Investigation of the structure of a dust cake
starts with its size distribution and shapein other words, the param-
eters determining the mutual configuration of the particles. Size dis-
tribution has been presented mostly by a statistical distribution of the
particles and the derivative quantity MMD.
From the dust filtration point of view, of paramount interest is a param-
eter for dust defining size distribution at two points:
0 In suspension in front of the filtration medium surface; and
0 In the dusty layer on the filtration structure's surface, with a
correlation between these two sets of data.
Variations in a solid body have been linked to its specific surface.
This is also true of initial studies on dust parameters which included
identifying specific surfaces for selected dusts varying as to size
distribution, shape, chemical properties, etc.
Equipment and Procedures
Four kinds of dust were studied for specific surfaces and other param-
eters linked to size distribution:
0 cement,
0 coal,
0 hydrated lime,
0 talc.
Particle size distribution of each of the tested dusts measured by use
of the BAHCO centrifugal separator is shown in Figure A-101.
Identified were two sizes of specific surface, depending on this physical
aspect:
57
-------
0 kinetics specific surface,
0 stationary (static) specific surface.
The kinetics specific surface is the total external surface, including
available pores in the particles. Measurement of kinetic specific surfaces
has been accomplished by IPWMB using LEA-NURSE apparatus.
Identification of the stationary specific surface was done by the Estab-
lishment of Catalysis and Physics of Surface of the Polish Academy of
Sciences in Cracow using the BET apparatus and argon or krypton (for
hydrated lime) as an adsorbent.
Results and Discussion
Table 11 compares the weighted average of 15 measurements of specific
surface sizes (stationary and kinetic), the fractional composition of
the dust (MMD in ym), and the size of the d < 20 ym population.
Table 11. COMPARISION OF DUST PARAMETERS
Kind of
Dust
Cement
Coal
Talc
Hydra ted Lime
Average value
of statfc
specific
surface
(in cm2/g)
1 7840 +
907
38642 +
1660
37180 +
3460
104020 +
3980
Average value
of kinetic
specific
surface
(in cm2/g)
3411
3438
5374
9319
MMD
(in ym)
32.0
21
12
9
Part of
fraction less
than 20 ym (in
percent)
ca 45
ca 48
ca 70
ca 80
58
-------
From these test results, it is noted that:
0 Both stationary and kinetic specific surfaces have lowest
values for cement dust and highest for hydrated lime;
0 The average size of dust particles, MMD, is highest for cement
dust and lowest for hydrated lime dust;
0 Population of d < 20 ym is greatest for lime dust and least for
cement dust.
Stationary specific surface is not strongly dependent on the particle
size distribution for particles less than 20 um in diameter. For exam-
ple, coal dust and talc, with Widely different particle size distribu-
tions, exhibit about the same stationary specific surface, but cement
and talc exhibit different values for stationary specific surface. Kin
etic specific surface correlates somewhat better with particle size
distribution. Thus, the hypothesis is advanced that kinetic specific
surface is a reliable indicator of particle size distribution in the range
below 20 um.
Conclusions
0 Kinetic specific surface is the best parameter for defining size
distribution as characterized by the below-20 ym fraction;
0 This hypothesis will be proven by later research.
f
STUDY OF ELECTROSTATIC PROPERTIES OF DUSTS AND FABRICS
Introduction
i""-1""
A literature search and our own research point to the very important role
of electrostatic phenomena in the dust filtration process. As a part of
work to develop a filtration model, further research must be undertaken in
this area so as to fill the gaps in existing empirical information.
Initially under this project, the electrostatic properties of dusts and
fabrics in a stationary condition were tested. Later, tests were conducted
under the dynamic conditions of a dispersed medium flow. Experiments
59
-------
were conducted by the Technical Physic of Wroclaw Polytechnic, managed
by Dr. Anna Szaynok. The results of these experiments will be included
in the report on the second phase of the project.
Dust Electrification
Dust electrification was measured by the Kunkel-Hansen method. The para-
meters defining the degree of dust cloud electrification are:
0 Average charge,
0 Standard deviation.
Average charge refers to the quantity of positive or negative charges
within a given class of particles. The amount of electrification can be
related to the standard deviation of the average charge. Investigation
of dust electrification was conducted for nonfractionated dusts and also
for the following fractions of dust:
0 Cement dust: 0 - 1.7 ym
1.7 - 2.94 ym
2.94 - 5.95 urn
0 Coal dust: 0 - 2.46 ym
2.46 - 4.40 ym
Fractionation of the dust was done by the BAHCO centrifugal device.
The measurements and separation were performed under laboratory conditions,
Specific Resistivity of Dusts
F0r unsepanatdd dust samples, specific resistivity was measured between
electrodes in a cylindrical chamber. Resistivity was measured under
varying electric field intensities and with variable pressures exerted
on the dust layer.
Specific Resistivity of Fabrics
Superficial specific resistivity and resistivity across the fabric were
measured for the following types of fabrics:
0 ET-4
0 ET-30
60
-------
0 F-tor 5
0 PT-15
Measurements were made in a specially designed set of electrodes. The
method of measurement will be described in the report for the second phase
of the project.
Discussion and Conclusions
0 Measurements of the electrification of unseparated cement dust
showed that for the particle size distribution of 4.8 to 8.5 ym,
there was a greater number of negative charges (q = ca. 23 e), and
the electrification was o = ca. 70 e. For unseparated coal dust
with particle size distribution of 8.60 to 13.0 ym, there was a
greater number of positive charges (q = ca. 30 e.), and the
electrification was a ca. 350 e.
0 The dependence of the charge of particles on the diameters (within
the test range of measurement) is linear for both positive and
negative charges.
0 Electrification of coal dust is less than that for fractionated
cement dusts, probably because of the effect of mechanical sep-
aration and the electro insulation properties of the particles.
° Resistivity of dust layers at 105° C temperature is different for
dried and undried layers. That of dry dust layers increased (on
the average of two magnitudes), suggesting high electrical
conductivity of the moisture in undried dusts.
0 Resistivity decreased nonlinearly when the intensity of the
electrical field was increased.
0 Resistivity also decreased nonlinearly with an increase in pressure
between electrodes. This function reached a minimum at pressures
within the experimental ranged.
0 For all fabrics tested, changes in resistivity measured through the
fabric were observed with changes in the intensity of the electric
field.
0 The dependence of fabric resistivity on pressure was clearly observed:
as pressure increases, resistivity decreases.
0 An influence on the superficial resistivity of fabrics by changes in
the intensity of the electric field was not observed.
61
-------
APPENDIX A
62
-------
(U
N
(0
(O
4->
S-
OJ
2!
01
CJ3
ii
LiJ
300
PARTICLE DIAMETER (ym)
Figure A-l. Particle Size Distribution for Cement Dust
(A - before separation; O- after separa-
tion).
63
-------
QJ
N
to
to
to
to
01
n:
CD
0.5
2345
10 20 30 40 50
PARTICLE DIAMETER (ym)
100
,300 300
CD
N
i
to
a
0)
M
(O
4->
I/)
i-
O)
(->
1C
O)
CD
Figure A-2. Particle Size Distribution for Coal Dust
(A - before separation, O - after separa-
tion).
64
-------
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
-120m3/m2h
20 30 40
FILTRATION TIME (minutes)
Figure A-3. Pressure Difference vs. Filtration Time for
Cement Dust and Fabric ET-4 (separated
dust).
65
-------
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
PI -120 m3/m2h
20 30 40 50
FILTRATION TIME (minutes)
Figure A-4. Pressure Difference vs. Filtration Time for
Cement Dust and Fabric ET-30 (separated
dust).
66
-------
CL)
4->
fO
LU
cc
CO
CO
LU
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
' -120 m3/m2h
20 30 ID _JO.
FILTRATION TIME (minutes)
Figure A-5. Pressure Difference vs. Filtration Time for
Cement Dust and Fabric F-tor-5 (separated
dust).
67
-------
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
-120 m3/m2h
20 30 « 50
FILTRATION TIME (minutes)
Figure A-6. Pressure Difference vs. Filtration Time for
Cement Dust and Fabric PT-15 (separated
dust).
68
-------
-------
i-
O)
p
fO
O
CO
CO
FILTRATION RATE
O - 60 m3/mzh
- 80 m3/m2h
-120 m3/m2h
0
20 30 40 50
FILTRATION TIME (minutes)
Figure A-8. Pressure Difference vs. Filtration Time for
Coal Dust and Fabric ET-30 (separated dust).
70
-------
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
D -120 m3/m2h
20 30 40 50
FILTRATION TIME (minutes)
70
Figure A-9. Pressure Difference vs. Filtration Time for
Coal Dust and Fabric F-tor-5 (separated
dust).
71
-------
O)
*->
to
UJ
O
z:
UJ
Q£
UJ
00
UJ
a:
a.
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
-120 m3/m2h
2Q 30 40 50 60
FILTRATION TIME (minutes)
Figure A-10. Pressure Difference vs. Filtration Time for
Coal Dust and Fabric PT-15 (separated dust).
72
-------
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
-120 m3/m2h
200 500 400 500
DUST LOAD (gm/m2)
TOO
Figure A-ll. Pressure Difference vs. Dust Load for
Cement Dust and Fabric ET-4 (separated
dust).
73
-------
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
D -120 m3/m2h
300 400 500
DUST LOAD (gm/m2)
Figure A-12. Pressure Difference vs. Dust Load for
Cement Dust and Fabric ET-30 (separated
dust).
74
-------
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
D - 120 m3/m2h
500 400 500
DUST LOAD (gm/m2)
Figure A-13. Pressure Difference vs. Dust Load for Cement
Dust and Fabric F-tor-5 (separated dust).
75
-------
s.
O)
O
z
LJj
a:
UJ
u_
y_
H-1
Q
CO
CO
UJ
a:
a.
FILTRATION RATE
- 60 m3/m2h
- 80 m3/m2h
-120 m3/m2h
300 m 500
DUST LOAD (gm/m2)
Figure A-14. Pressure Difference vs. Dust Load for
Cement Dust and Fabric PT-15 (separated
dust).
76
-------
HJ
UJ
O
LU
U_
o:
rs
C/J
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
.-120 m3/m2h
300 400 300
DUST LOAD (gm/m2)
Figure A-15. Pressure Difference vs. Dust Load for
Coal Dust and Fabric ET-4 (separated
dust).
77
-------
5-
0)
4J
to
o:
UJ
oo
co
LU
a:
D.
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
-120 m3/mzh
DUST LOAD (gm/m2)
Figure A-16. Pressure Difference vs. Dust Load for
Dust and Fabric ET-30 (separated dust).
78
-------
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
- 120 m3/m2h
300 400 500
DUST LOAD (gm/m2) ;
600
700
Figure A-17. Pressure Difference vs. Dust Load for Coal
Dust and Fabric F-tor-5 (separated dust).
79
-------
400
FILTRATION RATE
- 60 m3/m2h
- 80 m3/m2h
-120 m3/m2h
00 200 300 400 500 600
DUST LOAD (gm/m2)
Figure A-18. Pressure Difference vs. Dust Load for Coal
Dust and Fabric PT-15 (separated dust).
80
-------
-M
JZ
O)
DUST LOADING
O - 100 g/m2 '
- 400 g/m2 :
- 700 g/m2
o
-------
fOO
en
f
01
0)
u
99,9
o 99,6
99.7
DUST LOADING
O - 100 g/m2
- 400 g/m2
- 700 g/m2
80
FILTRATION RATE, (m3/hr/m2)
120
Figure A-20. Efficiency vs. Filtration Rate for Cement
Dust and Fabric ET-30 (separated dust).
82
-------
DUST LOADING
O - 100 g/m2
- 400 g/m2
Q - 700 g/m
50 100
FILTRATION RATE (m3/hr/m2)
Figure A-21. Efficiency vs. Filtration Rate for Cement
Dust and Fabric F-tor-5 (separated dust).
83
-------
JOO
CT>
r
O)
-(->
c
0)
i.
-------
JC
o>
r-
OJ
M
C
O)
o
01
Q.
>-
O
DUST LOADING
O - 100 g/m2
A - 400 g/m2
D - 700 g/m2
60
FILTRATION RATE (m3/hr/m2)
Figure A-23. Efficiency vs. Filtration Rate for Coal
Dust and Fabric ET-4 (separated dust).
85
-------
too
99,9
en
r-
0)
c
0)
O
s_
0)
a.
ga?
u_
u.
ui
9ft6
99.5
60
O- 100 g/m2
A - 400 g/m2
D - 700 g/m2
SO 100
FILTRATION RATE (m3/hr/m2)
120
Figure A-24. Efficiency vs. Filtration Rate for Coal
Dust and Fabric ET-30 (separated dust).
86
-------
- 100 g/m2
A- 400 g/m2
- 700 g/m2
80 100
FILTRATION RATE (m3/hr/m2)
Figure A-25.
Efficiency vs. Filtration Rate for Coal
Dust and Fabric F-tor 5 (separated dust).
87
-------
O - 100 g/m2
A - 400 g/m2
D - 700 g/tn2
.c
en
*->
c
£ 99.92
QL
S 99,90
100
FILTRATION RATE (mVhr/m2)
120
Figure A-26
Efficiency vs. Filtration Rate for Coal
Dust and Fabric PT-15 (separated dust).
-------
100
9918
en
QJ
-------
too
O)
$
M
C
0)
o
0)
Q.
>- ,
O
UJ
999
:FILTRATION RATE
9917
A - 80 m3/m2h
Q - 120 m3/m2h
0 100 200 300 400 500
DUST LOAD (gm/m2)
600
Figure A-28. Efficiency vs. Dust Load for Cement Dust
and Fabric ET-30 (separated dust).
90
-------
FILTRATION RATE
O -
60 m3/m h
A - 80 m3/m2h
- 120 m3/m2h
300 400 500
DUST LOAD (gm/m2)
Figure A-29.
Efficiency vs. Dust Load for
Cement Dust and Fabric F-tor 5
(separated dust).
91
-------
-C
CD
Ol
o
-------
FORMATION OF DUCTS/CANALS
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
D - 120 m3/m2h
200 300 400 500
DUST LOAD (gm/m2)
Figure A-31. Efficiency vs. Dust Load for
Coal Dust and Fabric ET-4
(separated dust).
93
-------
O - 60 m3/m2h
A - 80 m3/m2h
- 120 m3/m2h
9B.5
200 300 400 500
DUST LOAD (gm/m2)
TOO
Figure A-32. Efficiency vs. Dust Load for Coal Dust
and Fabric ET-30 (separated dust).
94
-------
FILTRATION RATE
O - 60 m3/m2h
- 80 m3/m2h
- 120 m3/m2h
200 300 400 500
DUST LOAD (gm/m2)
700
Figure A-33. Efficiency vs. Dust Load for Coal Dust
and Fabric F-tor 5 (separated dust).
95
-------
en
r
0>
0)
0
eu
Q.
>-
o
u_
U-
- 60 m3/m2h
- 80 m3/m2h
D - 120 m3/m2h
300 400 500
DUST LOAD (gm/m2)
Figure A-34. Efficiency vs. Dust Load for Goal Dust
and Fabric PT-15 (separated dust).
96
-------
O - 60 m3/m2h
- 80 m3/m2h
D - 120 m3/m2h
8 2 16
FILTRATION TIME (minutes)
Figure A-35.
Pressure Difference vs. Filtration Time
for Cement Dust and Fabric ET-4
(unseparated dust).
-------
s-
-------
s-
O)
4->
s
o
z
to
UJ
a:
a.
O - 60 m3/m2h
- 80 m3/m2h
D - 120 m3/m2h
4 g 12 16
- FILTRATION TIME (minutes)
Figure A-37.
Pressure Difference vs. Filtration
Time for Cement Dust and Fabric F-tor 5
(unseparated dust).
99
-------
1
U_
iI
a
ui
on
:z>
to
CO
LU
a:
a.
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
D - 120 m3/m2h
8 f2 16
i FILTRATION TIME (minutes)
Figure A-38. Pressure Difference vs. Filtration Time
for Cement Dust and Fabric PT- 15
(unseparated dust).
100
-------
FILTRATION RATE
O - 60 m3/m2h
A - 80 m3/m2h
- 120 m3/m2h
8 12 16
"FILTRATION TIME (minutes)
Figure A-39.
Pressure Difference vs. Filtration Time
for Coal Dust and Fabric ET-4
(unseparated dust).
101
-------
S-
o>
-»->
3
o
UJ
00
CO
UJ
- 60 m3/m2h
- 80 m3/m2h
D - 120 m3/ni2h
8 12 16
FILTRATION TIME (minutes)
Figure A-40. Pressure Difference vs. Filtration Time
for Coal Dust and Fabric ET-30
(unseparate dust).
102
-------
O - 60 m3/m2h
A - 80 m3/m2h
Cl - 120 m3/m2h
300 CO 500
DUST LOAD (gm/m2)
Figure A-41. Pressure Difference vs. Dust Load for
Cement Dust and Fabric ET-4
(unseparated dust).
103
-------
- 60 m3/m2h
- 80 m3/m2h
D - 120 m3/m2h
300 400 500
DUST LOAD (gm/m2)
Figure A-42. Pressure Difference vs. Dust Load
for Cement Dust and Fabric ET-30
(unseparated dust).
104
-------
O - 60 m3/m2h
- 80 m3/m2h
D - 120 m3/m2h
0 CO 200 300 400 500 600 TOO
' DUST LOAD (gm/m2)
Figure A-43. Pressure Difference vs. Dust Load
for Cement Dust and Fabric F-tor 5
(unseparated dust).
105
-------
OJ
M-
O
UJ
a:
UJ
tO
to
UJ
O - 60 m3/m2h
A - 80 m3/m2h
D - 120 m3/m2h
300 400 500
DUST LOAD (gm/m2)
Figure A-44.
Pressure Difference vs. Dust Load
for Cement Dust and Fabric PT-15
(unseparated dust).
106
-------
O - 60 m3/m2h
A - 80 m3/m2h
D - 120 m3/m2h
100
200
300 m 500
DUST LOAD (gm/fli2)
Figure A-45. Pressure Difference vs. Dust Load
for Coal Dust and Fabric ET-4
(unseparated dust).
107
-------
s-
§
a:
oo
CO
- 60 m3/m2h
A - 80 m3/m2h
- 120 m3/m2h
300 CO 500
DUST LOAD (gm/m2)
Figure A-46. Pressure Difference vs. Dust Load
for Coal Dust and Fabric ET-30
(unseparated dust).
108
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
- 700 g/m2
FILTRATION RATE (m3/hr/m2)
Figure A-47. Efficiency vs. Filtration Rate for
Cement Dust and Fabric ET-4
(unseparated dust).
109
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
- 700 g/m2
80 100
FILTRATION RATE (m3/hr/m2)
Figure A-48.
Efficiency vs. Filtration Rate
for Cement Dust and Fabric ET-30
(unseparated dust).
110
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
- 700 g/m2
96
FILTRATION RATE (m3/hr/m2)
Figure A-49.
Efficiency vs. Filtration Rate
for Cement Dust and Fabric F-tor
(unseparated dust).
m
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
Q - 700 g/m2
FILTRATION RATE (m3/hr/m2)
Figure A-50.
Efficiency vs. Filtration Rate
for Cement Dust and Fabric PT-15
(unseparated dust).
112
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
Q - 700 g/m2
60
FILTRATION RATE (m3/hr/m2)
Figure A-51.
Efficiency vs. Filtration Rate
for Coal Dust and Fabric ET-4
(unseparated dust).
113
-------
DUST LOADING
O - 100 g/m2
A - 400 g/m2
- 700 g/m2
80 CO
FILTRATION RATE (m3/fir/m2)
Figure A-52.
Efficiency vs. Filtration Rate
for Coal Dust and Fabric ET-30
(unseparated dust).
114
-------
Q - 60 m3/m2h
800
DUST LOAD (gm/nr)
Figure A-53. Efficiency vs. Dust Load for Cement Dust
and Fabric ET-4 (unseparated dust).
115
-------
U - 120 m3/m2h
DUST LOAD (gm/nr)
Figure A-54. Efficiency vs. Dust Load for Cement Dust
and Fabric ET-30 (unseparated dust).
116
-------
Q - 60 m3/m2h
DUST LOAD (gm/nr)
"' Figure A-55. Efficiency vs. Dust Load for Cement Dust
and Fabric F-tor 5 (unseparated dust).
117
-------
O>
r-
d)
3
-------
Q - 60 m3/m2h
too
DUST LOAD (gm/nr)
Figure A-57. Efficiency vs. Dust Load for Coal Dust
and Fabric ET-4 (unseparated dust).
119
-------
A - 80 m3/m8h
D - 120 m3/m8h
99.6
100 200
300 400
500 600
700
DUST LOAD (gm/nT)
Figure A-58. Efficiency vs. Dust Load for Coal Dust
and Fabric ET-30 (unseparated dust).
120
-------
Cement dust
Coal dust
Figure A-59.
Ducts/Canals in Coal and Cement Dust
(3x magnification)
32 3
q = 120 m /m min, L = 700 g/m .
121
-------
IX)
rv>
Q.
o
0£.
a
I
CO
CO
LU
ca
a.
REGENERATION
DUST FILTRATION
TYPE I
REGENERATION
/
DUST / DUST
FILTRATION, /FILTRATION
STABILIZED VALUE
INCREASE PRESSURE DROP
AFTER REGENERATION
OF PRESSURE DROP
qg = const. - m3/m2/hr.
qp = const. - g/m
APo
TIME
Figure A-60. Types of Dust Filtration.
-------
»
V.
/
'.
Inlet
Outlet
Figure A-61.
Surfaces of Clean Fabric WT-201
(wool fiber).
123
-------
Across warp
Across fill
Figure A-62. Clean Fabric WT-201
124
-------
Inlet
Outlet
Figure A-63. Surfaces of Clean Fabric BT-57
(cotton fiber).
125
-------
Across warp
Across fill
Figure A-64. Clean Fabric BT-57.
126
-------
Inlet
I
Figure A-65. Surfaces of Clean Fabric WBT-210
(wool-cotton fiber).
127
-------
Across warp
Across fill
Figure A-66. Clean Fabric WBT-210.
128
-------
u*-***«t
Inlet
Outlet
Figure A-67. Surfaces of Clean Fabric ET-4
(polyester fiber).
129
-------
Across warp
Across fill
Figure A-68. Clean Fabric ET-4,
130
-------
Inlet
Outlet
Figure A-69.
Surfaces of Clean Fabric ST-1
(glass fiber).
131
-------
Across warp
Across fill
Figure A-70. Clean Fabric ST-1
132
-------
CO
CO
FILTRATION RATE (m3/hr/m2)
Figure A-71.
Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-201 (wool-high velocity)
-------
0
, FILTRATION RATE (m3/hr/m2)
Figure A-72. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-202 (wool-high velocity)
134
-------
CO
en
FILTRATION RATE (m3/hr/m2)
Figure A-73. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-203 (wool-high velocity).
-------
s-
-------
s-
OJ
A->
CO
UJ
co
CO
UJ
o:
a.
0 20 40 80
FILTRATION RATE (m?/hr/m2)
Figure A-75. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type BT-57 (cotton-high velocity)
137
-------
5-
»
tO
4-
O
UJ
o
z
UJ
C£.
UJ
u_
u_
I I
o
Ul
Q-
20
FILTRATION RATE
60
Figure A-76.
Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type BWA-1539 (catton-high velocity)
138
-------
to
3=
UJ
o
CO
CO
Q_
FILTRATION RATE (m3/hr/m )
Figure A-77. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WBT-206 (wool/cotton-high velocity)
139
-------
S-
0)
4J
-------
s_
0)
-M
10
O
z
UJ
on
cc
=>
00
CO
UJ
o:
Q.
0
0 20
FILTRATION RATE (m3/hr/m2)
60
Figure A-79. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ET-1 (polyester-high velocity)
141
-------
.FILTRATION RATE (m3/hr/m2)
Figure A-80. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ET-2 (polyester-high velocity)
142
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-81. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-3
143
-------
0
FILTRATION RATE
(m3/hr/m2)
Figure A-82. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-4 (polyester-high velocity).
144
-------
0
FILTRATION RATE
(m3/hr/m2)
Figure A-83. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-30 (polyesterrhigh velocity).
145
-------
s-
-------
s-
O)
4->
as
o
z.
LU
OL
Q£
rs
oo
LU
O.
20
0
0
FILTRATION RATE
(m3/hr/m2)
Figure A-85.
Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ST-13 (glass-high velocity),
147
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-86. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ST-41 (glass-high velocity).
148
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-87. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-201 (wool-low velocity).
149
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-88. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-202 (wool-low velocity).
150
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-89. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type WT-203 (wool-low velocity).
151
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-90. Dependence of Pressure Drop vs. Filtration
Rate for Pure Fabric Type BT-57 (cotton-
low velocity).
152
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-91. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type BWA-1539 (cotton-low velocity).
153
-------
10
0
FILTRATION RATE
(m3/hr/m2)
Figure A-92. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type WBT-210 (wool/cotton-low velocity).
154
-------
10
I FILTRATION RATE
(m3/hr/m2)
Figure A-93. Dependence of Pressure Drop vs. Filtration Rate for|
Pure Fabric Type ET-1 (polyester-^ow velocity).
155
-------
0
'FILTRATION RATE
(m3/hr/m2)
figure A-94. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-2 ( polyester-low velocity).
156
-------
FILTRATION RATE
(m3/hr/m2)
Figure A-95. Dependence of Pressure Drop vs. Filtration Rate for
Pure Fabric Type ET-3 (polyester-low velocity).
157
-------
to
FILTRATION RATE
(m3/hr/m2)
Figure A-96. Dependence of Pressure Drop vs. Filtration Rate for I
Pure Fabric Type ET-4 (polyester-low velocity).
158
-------
FILTRATION RATE ,
(m3/hr/m2)
figure A-97, Dependence of Pressure Drop vs. Filtration Rate for \
Pure Fabric Type ET-30 (polyester-low velocity).
159
-------
10
FILTRATION RATE
(m3/hr/m2)
Figure A-98. Dependence of Pressure Drop vs. Filtration Rate -
for Pure Fabric Type ST-1 (glass-low velocity).
160
-------
FILTRATION RATE
fm3/hr/m2}
Figure A-99. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ST-13 (glass-low velocity).
161
-------
0
FILTRATION RATE
(m3/hr/m2)
Figure A-100. Dependence of Pressure Drop vs. Filtration Rate
for Pure Fabric Type ST-41 (glass-low velocity).
162
-------
CO
to
CO
CO
0)
CD
JO ZQ 30 C50
PARTICLE DIAMETER (ym)
300
Figure 3. Particle Size Distribution of Tested Dusts
(1 - hydrated lime, 2 - talc, 3 - coal,
4 - cement).
163
-------
APPENDIX B
BAHCO CENTRIFUGAL MICROPARTICLE SEPARATOR (Establissements Neu Lille,
France, Manufacturer)
Concept of Operation
The concept of operation of the BAHCO device is the separation of dry
solid particulate matter into an eluriated or fine fraction, and a
settled or coarse fraction, by subjecting particles to a centrifugal
force opposed by air drag. A weighed sample is introduced into a spiral
air current, of suitable tangential and radial velocities, created by
vanes of a fan.
Depending on the size, density, and shape of the particles, a certain
fraction of the sample (the settled, coarse particles) is accelerated
by centrifugal force to the periphery, collected into a catch basin, and
subsequently weighed. The fine fraction is carried out of the sifting
chamber through the fan vanes; its weight is taken as the difference
in weight of the coarse fraction measured before and after separation.
A sample of about 10 grams is required.
164
-------
APPENDIX C
SARTORIUS SEDIMENTATION BALANCE (Sartorius-Werke Aktiengesellschaft, 34,
Gottingen, West Germany, Manufacturer).
Application
This sedimentation balance operates according to Stokes Law. The test
sample is mixed with an appropriate liquid. Settled or suspended dry
matter can be used. The balance automatically records, during the test,
the amount of sediment settling onto a specially shaped pan.
This balance is used to obtain the curve of tested particle distribution
with a definition range of from 1 to 60 um.
Under good conditions, the distribution of size particles up to 150 vim
can be defined. By changing the distance of the particle fall (5, 10 or
20 cm), the duration of the test can be varied, depending on the range
of the size particles. If the dust particles are not spherically shaped,
only relative values are obtainable.
Concept of Operation
This device is equipped with a main balance bar. From the right hook
is suspended a sedimentation pan or plate; from the left hook are sus-
pended ring weight balances to equalize the displacement force of the
sedimentation pan.
On the middle of the main balance bar, there is a mirror lighted through
a lens. When the balance bar tilts, the light hits a photocell supplying
power to a "JAG" motor. The motor twists a wire, causing the balance
bar to return to the "0" point.
This cycle is repeated whenever the sedimentation pan or plate contains
2 mg of tested dust.
Each operation of the motor is recorded as a 0.08 cm horizontal displace-
ment on the recording device.
165
-------
APPENDIX D
MULTI-PLESC ALPINE SEPARATOR (Labor - Zickzacksichter 100 MZR: ALPINE
Aktiengesellschaft Mashinfabrik und Eisengiesserei, Augsburg, West
Germany, Manufacturer)
Technical Data
Separator:
Blower:
Revolutions: 2400 - 20,000 rev/min.
Air flow: 15-53 Nm3/hr
Static vacuum: About 1500 - 1600 mm of water
Air flow: 100 m3/hr
Alpine Filter:
Filtration area: 1 square meter
Feeder:
Maximum capacity (ground limestone): About 10 kg/hr
Application
This device is used for the following
1. Definition of dust size distribution for dust samples over 50
grams.
2. Collection of several dust size fractions, within approximately
1 kg, in laboratory scale tests.
3. Separation of dry matter into two fractions, with quantities of
a few kg/hr, in large-scale tests.
The range of separation for ground limestone is from 1 to 75 microns.
In this range, separation can be adjusted to any desired value.
Operation
This separator operates by cross streams of air and dust. The concept
is that of a zigzag tube, each section containing a lifting vortex. The
separated material slides down and passes across the stream of air, then
ascends and passes again through the air stream. Separation occurs
during each crossing of the air stream. Several zigzag tubes are radially
166
-------
mounted on a rotating disc, which permits sharpness of separation
to a lower limit of 1 micron. The separated material is moved into
the separator area by a screw feeder, and separated particles are removed
by mixing with air in the cyclone, 125 GAZ.
167
-------
APPENDIX E
AIR PERMEABILITY TESTING DEVICE, TYPE ALT-2/FF-1 (Metefem, Budapest,
Hungary, Manufacturer)
Technical Data
Size of test area: 10, 20, 50, 100 cm2
Range of manometer measurements: 0 - 30 mm of water
30-100 mm of water
100 - 200 mm of water
Range of tube rotameter measurements
(tolerance of +. 5% of upper value of
the range): 5-60 liters/hr
20 -200 liters/hr
150 - 750 liters/hr
500 - 3000 liters/hr
2500 - 12000 liters/hr
Maximum air flow through test fabric
(by use of suction fan): 800 liters/hr
Principle of Operation
A suction fan draws air through the test area of fabric; a vertical
manometer measures the air flow.
The manometer indicates the pressure differential between surfaces of
the fabric. The rotameter indicates the quantity of air flowing through
the fabric test area, with stabilized pressure differential.
From average measurements, an air permeability value is obtained,
expressed as the quantity, in cubic meters, of air flowing through a
square meter of test fabric each minute.
168
-------
APPENDIX F
TENSIL TESTING MACHINE TYPE PMGw 500 (Serial 2170/R 18/68 (1968), FEB
Thuringer Industriewerk, Ranestein, East Germany, Manufacturer)
Technical Data
Speed: 20 - 250 mm/min
Test sample length (excluding
clamp areas) 100, 200, 300, 360, 400,
500 mm.
Elongation: 0 - 200 mm
Maximum force loading: 500 kp
Range of Measurement: 0 - 100 kp
0 - 250 kp
0 - 500 kp
The machine is equipped with a recording device.
Application
This machine is designed to test the elongation and tensil strength of
fabrics, texrope belting, sailcloth, hardboard, etc.
Principle of Operation
A sample of fabric is held by a pair of clamps and is stretched, by
moving the lower clamp, until it breaks. The amount of elongation is
measured as the distance between the upper and lower clamps (excluding
the fabric in the clamp) under a defined load.
To meet Polish standards, test specimens are cut along warp and weft
of the fabric, with dimensions of:
Width: 50 + 0.5 mm.
Length: About 150 mm longer than the distance between clamps.
For fabrics with elongation less than 150.percent, the distance between
clamps should be set as 200 mm; for those with elongation greater then
150 percent, the distance should be set as 100 mm.
169
-------
The duration of movement of the lower clamp is defined as the difference
between when tension is applied and when the fabric breaks (equals
30 + 10 sec).
The measurement of the strength of the sample is the maximum loading
(which caused its breakage) with defined elongation (read from the scale
of elongation).
170
-------
APPENDIX G
LIST OF NOMENCLATURE
C = dust concentration
EQ = complete packing of yarn in fabric
GC = weight of dust fed into testing chamber
G = weight of dust collected on control filter
GZ = weight of dust collected on the fabric
L = weight of dust/unit area of fabric
L.J = fabric filling at point i during dust filtration types I and II
LN = fabric filling for a given regeneration cycle (Dust Filtration Type III)
LN = characteristic value for fabric filled with dust but not having a
dust cake
L = characteristic value of dust loading for a fabric filled with dust
and a dust cake
L = dust loading
IW1D = mean particle diameter
N = yarn count
N = warp count of yarn
lilO
Nm,, = fill count of yarn
rnw
N 3/hr = normal cubic meter/hr; normal cubic meter is at pressure of 760 mmHg
n and temperature of 0°C
RH = relative humidity
Z = relative warp and fill packing
Z. = superficial packing with yarn
Z = relative warp and fill packing
do = diameter of yarns
e = charge on electron; number of electrons
ko = length and width inside FA between threads
171
-------
kp = kilopound force
In = length of thread
lo = distances between axis of threads
m = mass of weighed threads
n = number of weighed threads in a fabric
no = number of threads
no/nw = yarn density
q = number of changes
qg = gas loading
q = dust loading
v = average velocity of the air flow before reaching the filter structure
6.. = fabric filling parameter for cycle i
n = dust collection efficiency
a = electrification parameter
AP = pressure drop for a static gas loading for q and no dust load
APK = pressure drop for a fully filled fabric with a dust cake
AP.. = pressure drop for a fully filled fabric without a dust cake
172
-------
APPENDIX H
METRIC CONVERSIONS
Although EPA's policy is to use metric units for quantitative
descriptions, this report uses certain non-metric units where it is felt
that doing so will facilitate understanding by a majority of the readers
of this report.
METRIC
1 newton/m
1 Kg(wt)/cm2 = 9.8 x 104 N/m2
1 liter
1 cal = 4.19 joule
1 joule
1 cm
1 gram
1 Kg
1 ym = 10"6m
|°C
D
32
i gram
3
meter
i gram
2
meter
1 m3/m2/hr
1 mm of HpO pressure drop =
., 98.06 dyne/cm2 =
.0735 mmHg =
.0073 cmHg
NON-METRIC
.0000099 atm
.971 atm
.0353 ft3 = .00629 bbl
,00397'BID
.000948 BTU
.3937 in = .0328 ft
15.43 grains
2.222 Ibs = .0011 tons
.00003937 in
°F
.437 grains/ft*
1.433 r = .029502 oz/yard
fr
3.28 ft3/ft2/hr
.0029 in of Hg = .000097 atm
173
-------
TECHNICAL REPORT DATA
(Please read /usovctions on ihe reverse before completing)
1. REPORT NO.
EPA-600/2-76-074
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Effect of Filtration Parameters on Dust Cleaning
Fabrics
5. REPORT DATE
March 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Jan R. Koscianowski and Lidia Koscianowska
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Institute of Industry of Cement Building Materials
45-641 Opole (IPWMB)
Oswiecimska Str. 21 POLAND
10. PROGRAM ELEMENT NO.
1AB012; ROAP 21ADJ-094
11. CONTRACT/GRANT NO.
PL-480 Agreement 5-533-3
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
Phase 1 Final: 6/73-1/76
14. SPONSORING AGENCY CODE
EPA-ORD
is.SUPPLEMENTARY NOTESPr0ject officer for this report is J. H. Turner, Mail Drop 61,
Ext 2925.
16. ABSTRACT
repOrt covers the first phase of research into the dependence of fil-
tration efficiency on filtration parameters and fabrics. It gives results of laboratory
tests of three types of polyester fabrics and one polyamid fabric in the filtration of
cement and coal dusts with particles of mass median diameter of 7. 5 micrometers.
Noted during the tests were: the relationship between the type of dust and filtration
process parameters; and the effect of electrostatic properties on the filtration pro-
cess. The dust filtration process was classified into three filtration types. The
structure of filtration fabrics was tested on the basis of air flow through 16 fabric
samples in two ranges of air flow velocity. The stochastic character of air flow
through the fabrics was verified. Structural parameters of the fabrics , as well as
derivative parameters , were measured and observed phenomena were analyzed from
an analytical viewpoint. The report also covers results of cement and coal dust
electrification tests and fabric resistance measurements.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Fabrics
Dusts
Filtration
Electrostatics
Efficiency
Polyester Fibers
Cements
Coal Dust
b.lDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
Fabric Filters
Polyamid Fibers
Fabric Resistance
c. COS AT I P'icld/Group
13B
HE
11G
07D
20C
14A
11B,13C
21D
8. DISTRIBUTION STATEMEN1
Unlimited
19. SECURITY CLASS (Tills Report)
Unclassified
21. NO. OF PAGES
186
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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