&EPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 2771 1
EPA-600/7-79-087
March 1979
Test of Fabric
iltration Materials
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide-range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/7-79-087
March 1979
Test of Fabric
Filtration Materials
by
Jan R. Koscianowski, Lidia Koscianowska, and Maria Szablewicz
Institute of Industry of Cement Building Materials
45-641 Opole
21 Oswiecimska Str., Poland
Public Law 480
Project P-5-533-4
Program Element No. EHE624
ROAP21ADJ-094
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
-------
ACKNOWLEDGEMENT
The authors would like to 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.
11
-------
CONTENTS
Page
Acknowledgement ii
Figures v
Tables x
SECTION I CONCLUSIONS 1
SECTION II RECOMMENDATIONS 4
SECTION III INTRODUCTION 5
Testing of Woven Textile Filtration Materials 5
Research Objectives 8
General Program 8
Laboratory Testing 8
Large Scale Testing 9
Comparative Analysis 9
Detailed Program 9
Laboratory Tests 9
Large Scale Testing 10
Auxiliary Studies 10
Fabric and Dust Selection 10
SECTION IV LABORATORY TESTING OF FILTRATION 18
Introduction 18
Equipment and Procedures 24
Results and Discussion 27
Air Flow Through Clean Filtration Fabrics 27
Laboratory Testing of Filtration Fabrics 46
Cotton and Nylon Fabrics 58
Polyester Fabrics 60
Nomex Fabrics 62
Glass Fabrics 62
iii
-------
CONTENTS (continued)
Page
Testing of Duct/Canal Formation Mechanism 65
Filtration Resistance Variation in Laboratory Testing 75
Conclusions 75
SECTION V LARGE SCALE TESTING OF FILTRATION 79
Introduction 79
Equipment and Procedures 80
Results and Discussion 91
Basic Test 91
The Influence of Hopper Efficiency on Conducted Experiments . . 104
Fractional Efficiency of Fabrics 112
Filtration Resistance 122
Conclusions 133
SECTION VI STUDY OF THE REGENERATION PROPERTIES OF FABRICS 135
Introduction 135
Results and Discussion 139
Conclusions 151
SECTION VII COMPARISON OF THE FILTRATION PROPERTIES OF POLISH AND U.S.
FABRICS 154
Introduction 154
Analysis of Filtration Properties 155
Natural Fiber Fabrics 155
Polyester Fabrics 155
Polyamide Fabrics 170
Glass Fabrics 170
Conclusions 170
REFERENCES 171
APPENDIX A 173
B 208
C 237
D 248
E 251
iv
-------
FIGURES
N°r Page
1 Dust Filtration Type 1 21
2 Increase of pressure drop in time during Dust Filtration
Type 1 22
3 Illustration of laboratory stand 25
4 Diagram of the laboratory test stand 26
5 Hydraulic characteristic of polyester fabrics 28
6 Hydraulic characteristic of glass, cotton, and nylon
fabrics 29
7 Hydraulic characteristic of Nomex fabrics 29
8 Specific hydraulic resistance of polyester fabrics 33
9 Variation of specific hydraulic resistance of glass,
cotton, and nylon fabrics 34
10 Variation of specific hydraulic resistance of Nomex
fabrics 34
11 Resistance coefficient, Kp of a woven fabric 35
12 Dependence of resistance coefficient K, on free area 38
13 Dependence of resistance coefficient K, on fabric
porosity 41
14 Dependence of resistance coefficient K., on porosity
function 42
15 Dependence of resistance coefficient K, on fabric
weight 44
16 Dependence of resistance coefficient K-^ on air
permeability 45
17 Superficial structure of fabrics 59
18 Ducts/canals distribution on polyester fabric covered
with talc (style no. 865B) 61
19 Comparison of surface structure of staple and continuous
filament Nomex fiber fabrics 63
20 Relationship between duct/number and: 1) A/C, and 2)
final pressure drop 67
-------
FIGURES (continued)
No.
21 Histogram showing the size distribution of duct/canal
equivalent diameter (exp 1, series 2) 69
22 Histogram showing size distribution of duct/canal
equivalent diameter (exp. 2, series 2) 70
23 Superficial structure of model fabric 72
24 Kinds of free areas in woven structure (Q53-878) 73
25 Duct/canal shape 74
26 Illustration of large-scale stand 81
27 Diagram of the large-scale test stand 83
28 Construction of bags 85
29 Diagram of regeneration cycles 86
30 Diagram of cascade impactor measurement system 88
31 Photography of cascade impactor measurement system 89
32 Velocity distribution in duct 90
33 Time variation of filtration resistance for fabric
C866B (dust: separated talc) 93
34 Time variation of filtration resistance for fabric
C866B (dust: unseparated coal) 94
35 Correlation between measurement efficiency and dust
balance efficiency for experiments for fabric C890B
dusted with cement at q = 60 m3/m2 hr Ill
36 Fractional efficiency of polyester and cotton fabrics
(cement dust at q = 80 m3/m2 hr, L = 400 g/m2, and
c. = 10 g/m3) . .g ° 116
37 Fractional efficiency of Nomex, glass, and polyamide
fabrics (cement dust at q =80 m3/m2 hr, L = 400 g/m2,
and ci = 10 g/m3) . . . .9 ° 117
38 Fractional efficiency of polyester fabrics (fly ash at
LO = 400 g/m2 and c^ = 10 g/m3) 118
39 Fractional efficiency of Nomex and glass fabrics (fly ash
at LQ = 400 g/m2 and c. = 10 g/m3) 119
40 Fractional efficiency of cotton and polyamide fabrics
(fly ash at LQ = 400 g/m2 and c^ = 10 g/m3) 120
41 Variation of filtration resistance in time for fabric
style no. 862B (cement dust at q =60 m3/m2 hr) 127
42 Variation of filtration resistance in time for fabric
style no. C890B (cement dust at q =60 m3/m2 hr) 128
y
vi
-------
FIGURES (continued)
No. Page
43 Variation of filtration resistance in time for fabric
style no. C892B (cement dust at q =60 m3/m2 hr) 129
44 Variation of filtration resistance in time for fabric
style no. Q53-875 (cement dust at q = 60 m3/m2 hr) 130
45 Variation of filtration resistance in time for fabric
style no. Q53-870 (cement dust at q =60 m3/m2 hr) 131
46 Variation of filtration resistance in time for fabric
style no. Q53-878 (cement dust at q =60 m3/m2 hr) 132
47 Theoretical plot of filtration and regeneration process .... 137
48 Realistic behavior of filtration and regeneration process . . . 138
49 Theoretical plot of susceptibility for regeneration
vs. time 140
50 Empirical time dependence of susceptibility for regeneration
(cement dust, q = 60 m3/m2 hr) 146
51 Microscopic pictures of testing dusts (a-cement, b-coal,
c-fly ash, d-talc) 152
52 Comparison of filtration properties of Polish and U.S.
fabrics (wool, cotton) 156
53 Comparison of regeneration properties of Polish and U.S.
fabrics (wool, cotton) 157
54 Comparison of filtration properties of Polish and U.S.
polyester fabrics 158
55 Comparison of regeneration properties of Polish and U.S.
polyester fabrics 159
56 Comparison of filtration properties of Polish and U.S.
polyester fabrics 160
57 Comparison of regeneration properties of Polish and U.S.
polyester fabrics 161
58 Comparison of filtration properties of Polish and U.S.
polyester fabrics 162
59 Comparison of regeneration properties of Polish and U.S.
polyester fabrics 163
60 Comparison of filtration properties of Polish and U.S.
polyester fabrics 164
61 Comparison of regeneration properties of Polish and U.S.
polyester fabrics 165
62 Comparison of filtration properties of Polish and U.S.
polyamide fabrics 166
vii
-------
FIGURES (continued)
Np^ Page
63 Comparison of regeneration properties of Polish and U.S.
polyamide fabrics 167
64 Comparison of filtration properties of Polish and U.S.
glass fabrics 168
65 Comparison of regeneration properties of Polish and U.S.
glass fabrics 169
A-l Particle size distribution of cement test dusts: 1 -
for laboratory testing; 2 - for large scale testing 174
A-2 Particle size distribution of coal test dusts: 1 - for
laboratory testing; 2 - for large scale testing 175
A-3 Particle size distribution of talc test dust 176
A-4 Particle size distribution of fly ash test dust 177
A-5 Filtration resistance vs. filtration time for fabric
style no. 960 178
A-6 Filtration resistance vs. filtration time for fabric
style no. 960 179
A-7 Filtration resistance vs. filtration time for fabric
style no. 862B 180
A-8 Filtration resistance vs. filtration time for fabric
style no. 862B 181
A-9 Filtration resistance vs. filtration time for fabric
style no. C866B 182
A-10 Filtration resistance vs. filtration time for fabric
style no. C866B 183
A-ll Filtration resistance vs. filtration time for fabric
style no. C868B 184
A-12 Filtration resistance vs. filtration time for fabric
style no. C868B 185
A-13 Filtration resistance vs. filtration time for fabric
style no. 865B 186
A-14 Filtration resistance vs. filtration time for fabric
style no. 865B 187
A-15 Filtration resistance vs. filtration time for fabric
style no. C890B 188
A-16 Filtration resistance vs. filtration time for fabric
style no. C890B 189
A-17 Filtration resistance vs. filtration time for fabric
style no. C892B 190
A-18 Filtration resistance vs. filtration time for fabric
style no. C892B 191
viii
-------
FIGURES (continued)
No. Page
A-19 Filtration resistance vs. filtration time for fabric
style no. 852 192
A-20 Filtration resistance vs. filtration time for fabric
style no. 852 193
A-21 Filtration resistance vs. filtration time for fabric
style no. 853 194
A-22 Filtration resistance vs. filtration time for fabric
style no. 853 195
A-23 Filtration resistance vs. filtration time for fabric
style no. 190R 196
A-24 Filtration resistance vs. filtration time for fabric
style no. 190R 197
A-25 Filtration resistance vs. filtration time for fabric
style no. 850B 198
A-26 Filtration resistance vs. filtration time for fabric
style no. 850B 199
A-27 Filtration resistance vs. filtration time for fabric
style no. 802B 200
A-28 Filtration resistance vs. filtration time for fabric
style no. 802B 201
A-29 Filtration resistance vs. filtration time for fabric
style no. Q53-875 202
A-30 Filtration resistance vs. filtration time for fabric
style no. Q53-875 203
A-31 Filtration resistance vs. filtration time for fabric
style no. Q53-870 204
A-32 Filtration resistance vs. filtration time for fabric
style no. Q53-870 205
A-33 Filtration resistance vs. filtration time for fabric
style no. Q53-878 206
A-34 Filtration resistance vs. filtration time 207
ix
-------
TABLES
No.
1 Fabric Parameters 12
2 Physical Properties of Testing Dusts 13
3 Particle Size Distribution of Cement Dust 14
4 Particle Size Distribution of Coal Dust 15
5 Particle Size Distribution of Talc 16
6 Particle Size Distribution of Fly Ash 16
7 Chemical Properties of Testing Dusts 17
8 Empirical Functions of Hydraulic Resistances of Filtra-
tion Fabrics 30
9 Empirical Functions of Specific Hydraulic Resistances
of Filtration Fabrics 32
10 Resistance Coefficients of Woven Fabrics 37
11 Additional Energy Losses 39
12 Porosities ej and s2 of Filtration Fabrics 40
13 Air Permeability of Dust Filtration Polyester Fabrics
Manufactured in Poland 46
14 Air Permeability of U.S. Filtration Fabrics 47
15 Laboratory Efficiencies (in percent) of Tested Filtra-
tion Fabrics 48
16 Filtration Resistances at Laboratory Testing 54
17 Classification of Fabrics According to Obtained Outlet
Concentration 56
18 Number of Ducts/Canals Observed in Laboratory Testing. . . 64
19 Number of Ducts/Canals Observed During Testing of
Fabric Style Q53-878 - Series 1 65
20 Number of Ducts/Canals Observed During Testing of Fabric
Style Q53-878 - Series 2 66
21 Average Equivalent Diameter for Experiments of Series 2. . 71
22 Effective Drag SE and Specific Resistance Coefficient
K2 in Laboratory Tests 76
-------
TABLES (continued)
No. Page
23 Large-Scale Efficiency (in percent) of Tested Filtra-
tion Fabrics. -. . . 95
24 Classification of Fabrics According to Outlet Concen-
tration ;..-;' 101
, _ •*
25 Efficiencies Ej2. EU» and £„ Calculated By Dust Balance. . 105
26 MMD For Feed.Dust, Bag Dust, and Hopper Dust 11Q
27 Fractional Efficiency of Fabrics Tested With Cement. ... 112
28 Fractional Efficiency of Fabrics Tested with Fly Ash . . . 114
29 MMD of Outlet Dust - Cascade Impactor Measurements. . . . . 121
30 Sp and Specific Resistance Coefficient in Large
Scale Tests 123
31 Rate of Increase of Filtration Resistance 125
32 Susceptibility for Regeneration (in. percent) of Fabrics
Tested with Cement at q = 60 m3/m2hr. ......... 141
33 Susceptibility for Regeneration (in percent) of Fabrics
Tested with Cement at q =80 m3/m2hr. 142
~lg
34 Susceptibility for Regeneration <-in percent) of Fabrics
Tested with Coal at q = 60 m3/m2hr. . . . 142
35 Susceptibility for Regeneration (in percent) of Fabrics
Tested with Coal at q_ = 80 m3/m2hr 143
36 Susceptibility for Regeneration (in percent) of Fabrics
Tested with Talc at q = 60 m3/m2hr 143
37 Susceptibility for Regeneration (in percent) of Fabrics
Tested with- Talc at q = 80 m3/m2hr 144
38 Susceptibility for Regeneration (in percent) of Fabrics
Tested with Fly Ash at q = 60 m3/m2hr 144
39 Susceptibility for Regeneration (in percent) of Fabrics
Tested with Fly Ash at q =80 m3/m2hr .......... 145
40 Regeneration Properties of Tested Fabrics 148
XI
-------
SECTION I
CONCLUSIONS
Results obtained from laboratory and large scale tests on fifteen kinds
of filtration fabrics manufactured in the United States confirmed some of
the observations made during previous tests conducted on Polish filtration
fabrics. The tests contributed to the enlargement of knowledge about the
dust filtration process, especially concerning the effect of filter structure
on dust collection efficiency. Because of the fixed testing program, some
observations that warranted further investigation could not be pursued and
were deferred to further tests.
It is important to notice that apart from the general purpose of the
program, i.e., the determination of the filtration and regeneration properties
of the tested fabrics, the completion of this program made available a lot
of general information concerning the dust filtration process.
Detailed conclusions about each section are enclosed at the end of the
respective sections. Following here are general conclusions resulting from
the total research program.
Examination of the hydraulic properties of fabrics under clean air
flow show that air permeability is too weak and imprecise a parameter
for classifying filtration fabrics. Any comparison of effects of
changing fabric technological parameters upon the hydraulic properties
of fabric should be carried out at constant air flow: one of the
statistical methods can be used. The structural parameter previously
proposed to characterize the woven structure of a filtration
material--Free Area (FA)--cannot be used for continuous filament
fabrics because of structural deformations during the weaving
process and/or air flow.
Air flows through clean woven structures in the range of q = 50 -
o •) 9
180 m /m hr are placed in the transition region between laminar
and turbulent flow.
-------
Because of the complicated character of flow due to the periodic-
ity of the woven structure, there are additional energy losses
proportional to the ratio b/q , where b is a constant coefficient
for certain structures and q is the gas loading of the filtration
area (the air-to-cloth ratio).
The ratio b/q reaches the lowest value for turbulent flow after
9
which the flow resistances depend upon the resistance coefficient
K-. and the square of the gas loading of the filtration area (the
air-to-cloth ratio).
The structural parameters of a woven fabric—free area, porosity,
fabric weight, and air permeability—are not correlated with K^.
Both the laboratory and the large scale tests confirmed the good
filtration properties of the U.S. as well as the Polish fabrics.
The observed influence of air-to-cloth (A/C) ratio on filtration
efficiency and on filtration resistance confirms the test results
obtained previously. Some unexpected dependencies (the ocassional
increase of dust collection efficiency with air-to-cloth [A/C]
ratio) are probably caused by electrostatic effects.
The existence of a definite critical value of pressure drpp,
causing duct/canal formation, was proven during laboratory testing.
More careful microscopic and structural examinations of the fabrics
led to the conclusion that the ducts/canals form in the voids
created by the interlacing warp and fill yarns where the dust cake
has the lowest mechanical strength. This newly discovered effect
was called the "basket effect." It is characteristic of all woven
materials. The magnitude of the basket effect depends upon the
kind of fiber, the method of yarn production, and the production
conditions of the fabric.
Each kind of filtration material has a specific A/C ratio at which
it achieves the highest level of filtration efficiency. The
testing conditions for glass fabrics were already beyond the
optimium A/C ratio so these fabrics displayed the lowest filtration
efficiencies of the fabrics tested. The decrease of efficiency
was caused by the basket effect, leading to duct/canal formation
at all A/C ratios investigated.
-------
Examination of the regeneration properties confirm that they
depend mainly upon the kind of raw textile materials, the kind of
dust, and the superficial structure of the dust cake and fabric.
The regeneration properties do not depend upon the A/C ratio
during the filtration process.
-------
SECTION II
RECOMMENDATIONS
This project made possible the compilation of very valuable empirical
data concerning Dust Filtration Process Type I, as well as Dust Filtration
Process Type III. The obtained experimental data should now be used to
mathematically model dust filtration processes.
Besides the major objective of the project, the flow of clean air
through woven structures and also the mechanism of dust cake defect forma-
tion were examined. The suggestion is made that further investigations
should concentrate mainly on physical descriptions of the woven fabric
structure and the dust cake.
The knowledge gained from the research performed during this project is
of itself not sufficient for complete process understanding. The necessity
of the further investigations suggested above results from a preliminary
probabilistic mathematical model of dust filtration as previously described.
-------
SECTION III
INTRODUCTION
TESTING OF WOVEN TEXTILE FILTRATION MATERIALS
In the most general sense, filtration is defined as a process for the
removal of dispersed solid particles from a fluid stream (dispersed medium)
during flow through a porous medium (ref. 1).
Depending on the state of the dispersion medium, the type of the dispersed
and porous mediums, and the conditions of the process, the following charac-
teristic kinds of filtration processes can be distinguished (ref. 2):
High efficiency air filtration,
Air filtration, and
Dust filtration.
In dust filtration processes, it is generally assumed that:
The process operates in the range of superheated steams (dry
steam) and the thermodynamic state of the dispersion medium is
above the dewpoint temperature at all times,
The aerosol is regarded as a 2-phase system (solid/gas), which,
under certain conditions, is quasi-stable,
The particles of the dispersed solid state have definite physical/
chemical properties characteristic of certain materials,
Precipitated particles in or on the structure of the filtration
medium can displace each other in the filtration structure; they
do not become permanent elements of the structure,
Filtration media are characterized by certain physical properties,
depending on fiber raw material and method of fabric formation.
Furthermore, it is worthwhile to notice that initial aerosol parameters
(temperature, humdity, dust concentration, etc.) and also filtration param-
eters (A/C ratio, dust loading of filtration area, etc.) are not constant
during a true dust filtration process but are changing randomly. It there-
fore follows that the final parameters of the aerosol and the qualitative/
-------
quantitative parameters of the process vary as a function of time and are
never stable. So, a description of the filtration process by functional
dependencies is very difficult and even in some cases impossible because
these dependencies are of a stochastic, not functional, character (ref. 3).
From a mathematical point of view, the dust filtration process is a multi-
parameter stochastic process. The above statement is based on statistical
analysis of rich empirical material (ref. 3).
This situation forces the use of specific testing methods and specific
data processing techniques so as to be compatible with probabilistic model-
ling of the dust filtration process. Work on this problem continues and
there is hope that a complete probabilistic model of dust filtration, ade-
quate for optimization of filtration structures and parameters and also able
to specify test methods and interpretation, will eventually be developed.
Because the probabilistic model of the dust filtration process is empirical,
its development and verification require extensive, coordinated test data.
At present there is no theoretical base, so tests are carried out under
conditions thought to best simulate true dust filtration. In many cases,
these tests help solve existing problems; nevertheless, the results always
have local character and cannot be generalized.
Depending on the application, the testing can be carried out in labora-
tory scale, large scale, pilot scale, or industrial scale. So, testing of
filtration materials, depending upon the purpose of their testing, can have
utilitarian and scientific character.
The laboratory and large scale tests always have scientific character.
The values of the initial aerosol parameters and filtration parameters
selected depend on the research program. Because of costs, the examining or
the testing of filtration materials are seldom carried out in pilot and
industrial scale. In addition, initial values of aerosol and filtration
parameters are forced by local conditions and are not representative.
The obtained data can be put in series according to definite depend-
encies:
Efficiency vs. A/C ratio, E = f(q ),
Efficiency vs. covered with dust structure, E = f(LQ),
Increase in filtration resistance vs. A/C ratio, AP = f(q ),
y
etc.
-------
In this way we can obtain cross sections of the dust filtration process
expressed as functional dependencies and which represent mathematical models
for the mean values of the examined parameters.
Based on the comparative analysis of the same filtration process cross
section, but for different examined parameters (different fabrics), we can
draw qualitative and quantitative conclusions.
The purpose of testing filtration fabrics manufactured in the United
States was to define their filtration properties and to compare them with
filtration fabrics of Polish production. According to the general program,
the testing of U.S. fabrics was conducted at one level of initial concentra-
tion, one level of dust cover, and two A/C ratios. The conditions were the
same for laboratory and large scale.
It is important to notice that from both a mathematical and a physical
viewpoint, the dust filtration process is different in the laboratory and at
large scale because of the vastly different dust fills that characterize the
two filtration mediums. In a previous report of this project, we proposed
to distinguish three main kinds of dust filtration processes: Dust Filtration
Process Types I, II, and III (ref. 4). Dust Filtration Process Type I is
characteristic of laboratory scale tests and Dust Filtration Process Type
III is characteristic of large scale tests. The correlation between these
two types of dust filtration processes is outside the scope of this work.
Such a correlation would require much parametric variation.
In this program, study of filtration effects is based on a comparative
analysis of fabric filters from a qualitative and quantitative point of
view. In the opinion of the researchers, all fabrics selected for tests
meet the definition of a good filtration fabric.
The assumed criteria are:
Final concentration,
Average value of efficiency, and
Final filtration resistance.
By establishing acceptable limits for these variables, it is possible to
classify the examined filtration fabrics.
-------
RESEARCH OBJECTIVES
The basic research objectives of this program, which was financed by
the EPA and conducted by the Institute of Cement Building Materials in
Opole, were established as:
Determination of the dust removal efficiency of the fabrics manu-
factured in the United States (supplied by EPA),
Determination of the hydraulic characteristics of both the clean
fabrics and of dusty fabrics during the filtration process,
Compilation and comparative analysis of the results for the deter-
mination of the qualitative parameters of the tested fabrics,
Evaluation of the regeneration properties of the fabrics,".,and
Comparison of the filtration properties of Polish and U.S. fabrics.
The total research program will include laboratory testing, large,scale
testing, and auxiliary studies.
GENERAL PROGRAM
Laboratory Testing
Laboratory testing was accomplished on 15 kinds of filtration fabrics
and 4 types of dust and was measured under the following conditions:
Dust concentration in the air at the inlet of the test chamber:
10 g/m3 ± 10%.
Dust covering of the filtration structure:
400 g/m2
with AP<250 mm of water.
A/C ratio:
60 m3/m2/hr
80 m3/m2/hr.
Humidity of the dispersion medium (not adjustable):
RH = 55% ± 10.
Temperature of the dispersion medium: 20 to 30° C.
Dispersion medium: atmospheric air.
Pressure: atmospheric.
8
-------
Large Scale Testing
Large scale tests were scheduled using filtration bags with an operat-
ing length of 3,300 mm and the same dusts as used in the laboratory testing.
Test conditions were:
Dust concentration in the air at the inlet of the test chamber:
10 g/m3 ± 10%.
Dust covering of the filtration structure:
400 g/m2
with AP<250 mm of water.
A/C ratios:
60 m3/m2/hr
80 m3/m2/hr.
Humidity of the dispersion medium (not adjustable):
RH = 65% ± 10.
Temperature of the dispersion medium: 20 to 30° C.
Dispersion medium: atmospheric air.
Pressure: atmospheric.
Comparative Analysis
The purpose of the comparative analysis was to determine, qualitatively,
the dust filtration performance of the fabrics based on tests using four
types of dust. The obtained test results will be used for further investiga-
tions of the probabilistic model of the dust filtration process (Project
P-5-533-3).
DETAILED PROGRAM
Laboratory Tests
Preparation of the separated dusts (cement, coal, talc, and fly
ash) using the ALPINE separator,
Determination of the physical-chemical properties of the separated
and unseparated dusts,
Testing of the filtration fabrics received from the United States
(15 kinds) using the following dusts: cement, coal, talc, and fly
ash; and
-------
Compilation and analysis of the results.
Large Scale Testing
Separation, by the subcontractor, of test dusts (cement, talc, and
fly ash),
Determination of the physical-chemical properties of the separated
and unseparated dusts,
Testing of 15 kinds of filtration fabrics received from the United
States and 4 types of dust (cement, coal, talc, and fly ash),
Estimation of the fractional efficiency of the filtration fabrics
using the cascade impactor, and
Compilation and analysis of the results.
Auxiliary Studies
Testing of hydraulic properties of filtration fabrics during clean
air flow,
Determination of filtration fabric parameters according to Polish
standards,
Special testing of filtration fabrics concerning structural param-
eters, using a scanning microscope,
Determination of the regeneration properties of the fabrics, and
Comparison of fabric properties of both Polish and U.S. produc-
tion.
FABRIC AND DUST SELECTION
Fifteen types of filtration fabrics, manufactured in the United States
and supplied by EPA, were selected for use in the major part of the testing
under Project P-5-533-4. These selected fabrics are produced from the
following raw materials:
Cotton (staple fiber):
No. 960
®
Dacron polyester (staple fiber):
No. 862B
No. C866B
No. C868B
10
-------
Dacron polyester (continuous filament):
No. 865B (staple fill)
No. C890B
No. C892B
(R)
Nomex aromatic nylon (staple fiber):
No. 852
No. 853
No. 190R
®
Nomex aromatic nylon (continuous filament):
No. 850B
Nylon polyamide (staple fiber):
No. 802B
Glass (staple fiber):
No. Q53-875~
Glass (continuous filament):
No. Q53-870
No. Q53-878 (texturized fill).
Technical characteristics of these fabrics are shown in Table 1.
Cement dust, coal dust, talc, and fly ash were selected as test dusts.
These industrial dusts were taken from appropriate points of the production
processing line so as to preserve realistic physical-chemical properties.
According to contractor wishes, separated dusts were used. Test dusts for
laboratory testing were separated by the ALPINE separator. For large scale
tests, the dusts were separated by subcontractors.
In accordance with suggestions from Dr. James H. Turner, the EPA Project
Officer, testing under this project was of only those dust samples contain-
ing no more than 10 percent, by weight, of particles with a diameter greater
than 20 \jm. Because of the explosive properties of coal dusts, the subcon-
tractor would not accept the responsibility of separating the dusts for
large scale tests. So, it was approved by the Project Officer to conduct
laboratory tests on separated and unseparated coal dust, but large scale
tests only on unseparated coal dusts.
The physical and chemical properties of the test dusts are shown in
Tables 2 through 7 and Figures A-l through A-4.
11
-------
TABLE 1. FABRIC PARAMETERS
Parameter
Fabric weight
Thread count
10 cm:
warp
fill
Thickness
(pressure
20 g/cm2)
Tensile
strength:
warp
fill
Elongation
during tension:
warp
fill
Bursting
strength
(ball diameter
10 mm)
Abrasion resis-
tance t
Permeability
Weave
Unit
9/m2
mm
kg/ 5cm
kg/5cm
%
%
kg
Fabrics
960
337
384
238
0.74
99
103
15
14
41.5
8628
330
138
110
0.87
162
125
35
42
69.5
C866B
379
164
138
0.92
212
162
34
44
97.5
C8688
438
164
158
0.96
210
221
34
42
113.0
865B
337
302
178
0.63
330
135
41
37
92.5
C890B
168
292
262
0.24
170
136
20
34
58.5
C892B
151
254
232
0.24
162
122
29
33
71.5
852
292
122
100
0.92
148
120
30
23
75.0
653 190R
350 510
154
144
1.08 1.79
175 67.4
148 108
28 19
28 56
92.0 82.0
850
155
380
288
0.24
188
151
40
35
82.0
802B
401
140
136
1.08
173
179
41
44
91.0
Q53-875
281
210
204
0.31
176
160
3.9
4.1
t
Q53-870
282
210
204
0.30
188
196
3.5
4.1
t
Q53-878
451
176
96
0.56
475
248
6
6
t
Number of
•strokes
rubbl ng
through
dm3/m2/s
at 10 mm
of water
for
275
45
4
~T
615
382
1
890
240
2
-2*
960
163
2
-TS
640
166
3
-I*
160
107
3 ,
"r
215
70
3 7
-1Z
450
457
1
1
920 1100§
1760
187 97
2
"*
180
148
3
-Tz
1330
140
2 ;
2
70
226
1
3
55
58
3
"I"
225
219
3
-T5
*A11 the values have been determined according to Polish standards.
tUnder the pressure of the ball, the threads displace, but do not break.
^Conditions of testing: Measuring instrument type STOLL, loading 0.907 kG, grinder-abrasive paper No. 600.
§Rubbing to interlayer.
-------
TABLE 2. PHYSICAL PROPERTIES OF TESTING DUSTS*
Parameter
Kind of dust
Cement
After separation
Before separation
Coal
After separation
Before separation
Talc
After separation
Before separation
Fly ash
After separation
Before separation
Angle of
repose
dust
(on glass
surface)
41°50'
55°20'
44040-
62°
90°
90°
61°67'
57°33'
Poured
dust
weight
of
1 liter
(in
g/dm3)
898.33
736.67
571.67
406.67
498.30
446.70
610.00
560.00
Cone
angle of
heaped
dust
47°17'
48°09'
41°49'
49°56'
40°01'
61°45'
46° 15'
45°56'
Jogged
dust
weight
(in
g/cm3)
1.40
1.13
0.77
0.62
0.87
0.77
1.03
0.858-
1.018
All the values have been determined according to Polish standards.
13
-------
TABLE 3. PARTICLE SIZE DISTRIBUTION OF CEMENT DUST
Separated
(for laboratory scale)
Separated
(for large scale)
Separated
(for large scale)
Density: 2.86
Range of
particle
size in ym
< 2.13
2.13- 3.91
3.91- 5.92
5.92- 9.17
9.17-14.20
14.20-23.67
23.67-28.99
28.99-32.54
>32.54
g/cm3
Percent
by
weight
6.70
10.80
16.80
23.10
24.10
16.30
2.10
0.10
-
Density:
Range of
particle
size in ym
< 2.15
2.15- 3.95
3.95- 5.99
5.99- 9.28
9.28-14.37
14.37-23.95
23.95-29.34
29.34-32.93
32.93-60.00
>60.00
2.78 g/cm3
Percent
by
weight
11.91
18.90
30.19
24.89
10.46
3.02
0.43
0.07
0.13
-
Density: 2.857
Range of
particle
size in ym
< 2.17
2.17- 3.97
3.97- 6.02
6.02- 9.34
9.34-14.46
14.46-24.09
24.09-29.52
29.52-33.13
>33.13
g/cm3
Percent
by
weight
9.85
17.90
34.06
25.52
10.08
2.82
0.33
0.21
-
-------
TABLE 4. PARTICLE SIZE DISTRIBUTION OF COAL DUST
on
Separated
(for laboratory scale)
Unseparated
(for large scale)
Unseparated
(for large scale)
Density:
Range of
particle
size in urn
< 2.38
2.38- 4.11
4.11- 8.31
8.31-12.10
12.10-20.72
20.72-36.13
36.13-45.08
45.08-51.77
51.77-60.00
> 60.00
1.55 g/cm3
Percent
by
weight
7.15
13.86
30.20
21.51
23.88
3.21
0.09
0.02
0.01
0.07
Density:
Range of
particle
size in ym
< 2.95
2.95- 5.41
5.41- 8.19
8.19-12.70
12.70-19.67
19.67-32.78
32.78-40.16
40.16-45.08
45.08-60.00
69-88
88-150
150-200
>200
1.48 g/cm3
Percent
by
weight
4.70
6.89
9.90
11.28
10.86
12.07
4.26
2.25
8.56
10.95
12.98
3.50
2.80
Density: 1.50
Range of
particle
size in ym
< 2.42
2.42- 4.18
4.18- 8.44
8.44-12.29
12.29-21.06
21.06-36.72
36.72-45.82
45.82-52.62
52.62-60.00
60-88
88-150
150-200
>200
g/cm3
Percent
by
weight
2.72
4.68
6.06
12.52
12.80
12.51
5.85
3.23
7.02
9.70
14.00
4.56
4.35
-------
TABLE 5. PARTICLE SIZE DISTRIBUTION OF TALC
Separated
(for laboratory and
large scale)
Separated
(for large scale)
Density: 2.80
Range of
particle
size in ym
< 2.15
2.15- 3.95
3.95- 5.99
5.99- 9.28
9.28-14.37
14.37-23.95
23.95-29.34
29.34-32.93
>32.93
g/cm3
Percent
by
weight
6.86
14.00
20.52
25.61
18.96
11.49
2.04
0.52
Density: 2.78
Range of
particle
size in ym
< 1.77
1.77- 3.05
3.05- 6.17
6.17- 8.98
8.98-15.39
15.39-26.83
26.83-33.47
g/cm3
Percent
by
weight
4.93
11.39
17.14
41.37
22.45
2.72
TABLE 6. PARTICLE SIZE DISTRIBUTION OF FLY ASH
Separated
(for laboratory and large scale)
Density: 2.27 g/cm3
Range of
particle
size in ym
< 2.38
2.38- 4.37
4.37- 6.62
6.62-10.26
10.26-15.89
15.89-26.49
26.49-32.45
>32.45
Percent
by
weight
11.06
20.72
33.61
25.81
8.20
0.58
0.02
16
-------
TABLE 7. CHEMICAL PROPERTIES OF TESTING DUSTS
Kind of test dust
Component
Unit Separated
cement
test dust
Unseparated
coal
test dust
Separated
coal
test dust
Separated
fly ash
test dust
Loss of
roasting
Si02
Ti02
Fe203
A1203
CaO
MgO
S03
Na20
K20
TOTAL
6.93
21.32
-
+, 2.37
.? 6.73
* 54.36
-° 1.99
-------
SECTION IV
LABORATORY TESTING OF FILTRATION
INTRODUCTION
Laboratory testing of filtration fabrics is conducted mainly to deter-
mine the time dependence of the efficiency and the pressure drop during a
single dust cycle—from a given initial state to a predetermined final state
using a non-varying aerosol.
Usually laboratory testing is completed by measuring the hydraulic
characteristics of the test materials, i.e., the determination of resistance
variations as a function of A/C ratio. The hydraulic resistance of clean
air flow through filtration structures depends upon the structural param-
eters of the filtration structure. Generally, two kinds of structural
parameters can be distinguished:
1. Physical parameters of structure (porosity, density of packing,
etc.), and
2. Technological parameters of structure (diameter of fiber, diameter
of thread, the kind of weave, etc.).
Correlations between the physical and the technological parameters of
woven filtration materials have not previously been made nor has the effect
of technological parameters on chosen physical parameters characterizing the
material been examined during both clean air flow and flow during the dust
filtration process. Because of the extremely complicated composition of the
fabric structure, the comparison of certain types of woven material structures
is conducted by comparing their hydraulic properties during clean air flow
only.
Permeability is a commonly used parameter describing the value of air
flow through a unit area at a definite pressure drop. Pressure drop has
been standardized as:
18
-------
0.5 in. of water - United States,
20 mm of water (sometimes 10 mm of water) - Poland.
Based on the results of testing different fabrics, it can be said that
the permeability of certain fabrics (manufactured under the same technolog-
ical conditions) from different series can vary greatly. It is caused by
the heterogeneity and quality of the raw materials, by specification of the
spinning and weaving processes, and also by finishing operations.
From a mathematical viewpoint, permeability is not a representative
enough parameter for comparing woven filtration fabrics. It is better to
compare hydraulic characteristics as defined in the following equation:
AP = f(qg). (1)
In order to characterize woven filtration fabrics, the parameter called
"free area," FA, calculated from technological parameters, was introduced
(refs. 5, 6).
FA = 100 - (nodo!0 + nwdw!0 - n^d^) (2)
where FA = free area, in,percent,
n = number of warp threads/10 cm,
n = number of fill threads/10 cm,
W
d = diameter of warp yarn, in cm, and
d = diameter of fill yarn, in cm.
W
In the phase I report of this project, it was proven that because of
thread deformation in continuous filament polyester, nylon, and glass fabrics
the calculation of FA does not correspond to the pressure drop obtained
during clean air flow. Staple fiber threads also show the deformation, but
it is very small. Moreover, FA does not consider the presence of "free
fiber" in spaces not filled by yarn, which also influences the flow resist-
ance and filtration effects.
To apply FA as a technological structural parameter, it is necessary to
define the method of determining the diameter of the warp and fill yarns
(ref. 5).
The diameter of the yarns can be calculated from the metrical numbers
of the yarn or can be measured using a microscope, taking deformation into
consideration. In the second case, the analytical size is either the long
19
-------
or the short projected dimension. Sometimes, the diameter of the yarn is
calculated as the average of the lengthwise projected dimensions of the
yarn.
So, we can obtain three different diameters, resulting in three values
of FA. It should be added that FA does not concern the spatial structure of
fabrics. The laboratory filtration process is not the same as the indus-
trial fabric collector process where the filtration medium has reached a
definite state-of-balance. The laboratory process has been defined as Dust
Filtration Type I (refs. 2, 3).
Dust Filtration Type I is the initial phase of the complete process,
when the fabric first begins operation as a filtration medium. This phase
ends when the pressure drop across the fabric reaches a predetermined level
for a given A/C ratio.
Dust Filtration Type I is presented in Figure 1. The initial state is
described by AP (pressure drop of the pure clean fabric structure) at q =
constant and q = 0, so that L = 0. The final state of the process is
described by AP.., (final pressure drop) at q = constant, q_ = constant, and
i\ 9 P
L = L = LN + Lp. (Lp represents the dust in the dust cake that will be
removed during regeneration; LN represents the dust not removed during
regeneration.) On both laboratory and industrial scale the dust filling of
the structure (L..) is determined by weighing after a specific regeneration
cycle.
Because of the long time required to reach a constant quantity of
residual dust remaining in the fabric, the dust filling of the structure in
laboratory conditions is very small and is only an auxiliary parameter for
interpretation of results.
Described by initial and final pressure drop, dust filtration is charac-
terized by a certain effectiveness, the measurement of which is the average
efficiency of dust collection, Ej. Subscript "I" indicates that efficiency
concerns Dust Filtration Type I.
The filtration pressure drop in time is shown in Figure 2. During the
first phase of the process, the increase of filtration resistance is very
2
fast and has a parabolic character of the general form y = ax + bx + c with
a<0 to point A, the point of inflexion. Beyond point A, the increase also
has parabolic character but with a>0.
20
-------
Figure 1. Dust Filtration Type I
21
-------
g
to
£3
85
Phase '
AP,
Phase 2
Straight line
approximation
q
. = constant
= constant
FILTRATION TIM3
Figure 2. Increase of pressure drop in time during Dust
Filtration Type I.
22
-------
The length of phase 1 and 2 depends on the kind of filtration material,
the kind of dust, and its particle size distribution. The rate of increase
of resistance depends on the above variables and also on the A/C ratio (ref.
7).
For some dust-fabric systems the dependence AP = f(tp) or AP = f(LQ)
can be approximated by a straight line. The hypothesis can be made that
during phase 1 there is filling of the free spaces of the filtration medium
and from the point of inflexion on the dust cake starts to build (ref. 8).
Because there is no theory interpreting the results of laboratory
testing of filtration fabrics, comparative analysis is widely applied. To
facilitate the comparative analysis, a systematic format can be applied.
Concerning the efficiency of dust collection, the test results can be
classified by levels of analytically estimated final concentrations. Concern-
ing the pressure drop with filtration time, the results are usually approxi-
mated to the following dependence using linear regression:
AP = f(tF) = bo + bjtp. (3)
Regarding this dependence as the first approximation of a process that
really has parabolic character, it is possible to compare the filtration
resistances between different dust-fabric systems.
According to Stephan, Walsh, and Herrick (ref. 9), the value b from
equation (3) is proportional to Sr, the effective drag.
S£ = bo/qg (4)
where S£ = effective drag, in mm^O/m/hr,
b = effective pressure drop, in mmH90,
o 32
q = A/C ratio, in m /m hr.
y
The value b-. is proportional to K^, the specific dust-fabric resis-
tivity according to the following dependence:
fg
2
where Kp = specific dust-fabric resistivity, in (mmH20/m/hr)/(g/m ),
b.. = coefficient, in mmH^O/hr,
23
-------
c. = initial concentration, in g/m ,
"* 32
q = A/C ratio, in m /m hr.
The rate of increase of filtration resistance during the filtration
process can be described by the following dependence:
v • -- • "i (6)
where VAf> = rate of increase of filtration resistance, in
AP
AP = pressure drop, in mmH^O,
tF = filtration time, in hours.
It depends on the properties of the filtration medium (dust- fabric
system) and also on filtration parameters.
EQUIPMENT AND PROCEDURES
Laboratory testing of selected filtration fabrics was conducted on a
stand, illustrated in Figure 3, specially designed by the IPWMB and adapted
for the testing of flat fabric specimens under ambient air conditions.
This stand includes a test chamber, a rotameter for measuring flow
intensity, a needle valve to control flow intensity, a vibrating-injecting
dust feeder, a micromanometer to measure pressure drop, and a vacuum pump
(see Figure 4). The testing chamber, the main part of the stand, is equipped
with a diffuser at the inlet end, a fabric specimen table, and a control
o
filter table at the outlet end. A round fabric specimen with a 100 cm test
area is positioned in the middle of the table, supported by wire net screen-
ing 4 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 disc with a 200
2
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:
24
-------
1
Figure 3. Illustration of laboratory stand.
25
-------
FLOW CONTROL VALVE
DUST FEEDER
FILTER CHAMBER
INCLINED MANOMETERS
FILTER TEST STAND \
PAPER FILTER
Figure 4. Diagram of the laboratory test stand.
26
-------
100
_ Gz _ Gc " Go _ Gz (7)
where E = dust collection efficiency in percent,
G = weight in grams of dust collected on the fabric,
G = weight in grams of dust collected on the control
filter, and
G = weight in grams of dust fed into the testing
chamber.
During testing the temperature and humidity of the ambient air were
recorded. The fabric samples and control filters were conditioned in ambient
air for 72 hours.
Using the laboratory test stand, the following data can be obtained:
Mean filtration efficiency,
Hydraulic characteristics of filtration materials during
clean air flow,
Increases in hydraulic resistance during dusty air flow,
Degree of filling of filtration materials.
Although specially designed for the laboratory testing of woven filtra-
tion fabrics, this stand can also be used for laboratory testing of other
filtration materials, e.g., felt.
RESULTS AND DISCUSSION
Air Flow Through Clean Filtration Fabrics
The testing of hydraulic resistances of clean filtration fabrics during
3 2
air flow was conducted for A/C's in the range of 50 - 180 m /m hr. Five
series of measurements were done on all fabrics to determine the average
values of hydraulic resistance. The results are shown in Table B-l.
Based on the average values of hydraulic resistance for certain A/C's,
the curves of hydraulic resistance, as a function of A/C ratio, were drawn.
They are shown on Figures 5 through 7.
The dependences AP = f/(q ) for each kind of fabric were determined
using the least squares method. It appeared that the empirical data best
approximated the parabolas. The results of the calculations, in the form of
empirical dependences, are shown in Table 8.
27
-------
12
10
8
O Style No. C892B
V Style No. C890B
D Style No. 865B
® Style No. C868B
0 Style No. C866B
Style No. 862B
50
100
150
200
AIR-TO-CLOTH RATIO IN m3/m2 hr.
Figure 5. Hydraulic characteristic of polyester fabrics.
28
-------
8
o
CM
8
Cotton 960
O Glass Q53-870
0 Nylon 802B
Glass Q53-878
Glass Q53-875
0
0 50 100 150 200
GAS LOADING OF FILTRATION AREA, A/C, IN m3/m2 hr.
Figure 6. Hydraulic characteristic of glass, cotton, and
nylon fabrics.
o
tvi
V Style No. 190R
O Style No. 850
° Style No. 853
* Style No. 852
M
P
0 *
0
50
GAS LOADING OF FILTRATION AREA, A/C, IN nT/rrf hr.
Figure 7. Hydraulic characteristic of Nomex fabrics.
29
-------
TABLE 8. EMPIRICAL FUNCTIONS OF HYDRAULIC RESISTANCES
OF FILTRATION FABRICS
Type
of
fabric
Cotton
Dacron®
Dacron®
Nomex®
Nomex®
Nylon
Glass
Glass
Function*
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-879
Q53-878
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
AP
= 0.6533q 2 -
= 0.0674q 2 -
= 0.1450q 2 -
= 0.2104q 2 -
= 0.2227q 2 -
= 0.2315q 2 -
= 0.3905q 2 -
= 0.0595q 2 H
= 0.1509q 2 H
= 0.2261q 2 J
= 0.1705q 2 H
= 0.2401q 2 H
= 0.0736q 2 H
9
= 0.5629q 2 H
g
= 0.1471q 2 ^
f 3.3369q
f 0.1292q
H 0.3403qg
H 0.6380q
H 1.0278q
i- 1.0679q
i- 1.7511qg
i- 0.1880q
i- 0.6922q
i- 1.2202q
H 0.6549q
i- 0.8076q
i- 0.2258q
i- Z.lllOq
i- 0.3326q
- 0.1475
+ 0.0022
- 0.0030
- 0.0080
- 0.0770
+ 0.0190
- 0.0300
- 0.0035
- 0.0140
- 0.0350
+ 0.0174
- 0.0110
- 0.0110
- 0.1871
- 0.0140
*q in m3/m2 min.
30
-------
The specific hydraulic resistance of the porous layer, according to the
Darcy equation for turbulent flow (ref. 10), is:
APi = AP/b = iq (qg)2 (8)
where AP. = specific hydraulic resistance of porous layer in
mmHpO/mm,
AP = hydraulic resistance in mmHLO,
b = thickness of porous layer in mm,
K' = resistance coefficient, and
32
q = A/C ratio in m /m min.
The dependence of the specific hydraulic resistance of the tested fabrics as
a function of A/C ratio, in the form of equations, is presented in Table 9.
The above equations are shown in the form of curves in Figures 8 through 10.
Neglecting the free terms of the equations in Tables 8 and 9 (the parabola
must cross the point of coordinates 0,0) and taking into consideration
equation (8), we get:
AP. = AP/b = Kj_ (qg)2 = aqg + bqg
so K' = a + — -. (10)
qg
The resistance coefficient Kl of the Darcy equation (equation. 10) is
not a stable value characterizing the filtration structure, but is a func-
tion of A/C ratio. Its functional dependence is presented in Figure 11.
The function is a hyperbola with asymptotes, q =0 and KI=a.
Because of the absence of physical and also mathematical descriptions
of woven filtration structures, it is very difficult to define the kind of
flow through the clean structure over the range of A/C ratio studied. It
was only ascertained that the flow is between laminar and turbulent flow.
Assuming the above, the discussion of dependence (10) was carried out. The
following are conclusions of the discussion:
31
-------
TABLE 9. EMPIRICAL FUNCTIONS OF SPECIFIC HYDRAULIC RESISTANCES
OF FILTRATION FABRICS
Type
of
fabric
Cotton
Dacron®
Dacron®
Nomex
Nomex®
Nylon
Glass
Glass
Function*
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
AP.
AP.
APi
APi
APi
AP.
APi
APi
APi
AP.
APi
AP.
APi
AP.
AP.
= 0.8828q 2 -
= 0.0775q 2 -
= 0.1576q 2 •
= 0.2192q 2 -
= 0.3535q 2 J
= 0.9645q 2 J
= 1.6271qg2 H
= 0.0647q 2 -
= 0.1397q 2 H
= 0.1263q 2 H
= 0.7104q 2 H
= 0.2223q 2 H
= 0.2374q 2 H
s?
= 1.8763q 2 H
= 0.2627q 2 H
H 4.5093q
i- 0.1485q
t- 0.3699q
H 0.6646q
i- 1.6314q
i- 4.4496q
H 7.2962q
i- 0.2043q
i- 0.6409q
i- 0.6817q
H 0.7478q
i- 0.7478q
H 0.7284q
H 7.0367q
H 0.5939q
g
- 0.1993
+ 0.0025
- 0.0033
- 0.0083
- 0.1222
+ 0.0792
- 0.1250
- 0.0038
- 0.0129
- 0.0195
- 0.0725
- 0.0100
- 0.0355
- 0.6236
- 0.0250
*q in m3/m2 min.
32
-------
15.
o
CM
I
o
O
O
s
CO
O Dacron C892B
V Dacron C890B
D Dacron 865B
Dacron C868B
Dacron C866B
Dacron 862B
50
100
150
200
A/C RATIO IN m3/m2 hr
Figure 8. Specific hydraulic resistance of polyester fabrics,
33
-------
a
ac
•
o
K
to
O Glass Q53-870
V Cotton 960
D Glass Q53-875
D Nylon 802B
A Glass Q53-S78
IOD
A/C RATIO IN m3/m2 hr
180
Figure 9. Variation of specific hydraulic resistance of glass, cotton,
and nylon fabrics.
V Nomax 190R
O Nos»x 853
A Nomftx 852
O Noswx 850B
o
IM
i
to
e
CO
A/C RATIO IN m3/m2 hr
Figure 10. Variation of specific hydraulic resistance of
Nomex fabrics.
34
-------
o
o
o
CO
I—I
co
UJ
o:
A/C RATIO AREA
Figure 11. Resistance coefficient, Kj, of a woven fabric,
35
-------
Value K-, = a statistical parameter characterizing the woven struc-
ture. It is the so-called resistance coefficient of a woven
fabric,
Because of the complicated character of flow, due to periodicity
of the woven structure, there are additional energy losses propor-
tional to the ratio b/q .
The ratio b/q reaches the lowest values, tending towards "a", at
9
increasing A/C ratio—that means at increasing values of Reynolds
numbe
form:
number. Thus for high values of q , the dependence (10) is of the
y
Ki = a = Kr
From equation (9) then:
APi = AP/b = 1^ (qg)2.
We propose to call 1C, which is dependent on the woven material
structure and the character of the air flow, the function of woven
fabric resistance.
From equation (10), the resistance coefficients for individual filtration
materials were determined. They are shown in Table 10.
As can be seen from the compiled data, continuous filament fabrics,
(also cotton fabrics) independent of the kind of raw material, have the
highest values of coefficient K,. It is very interesting that the addi-
tional energy losses for these fabrics, as measured by the coefficient b/q
are the highest. The preliminary explanation of this phenomenon was made in
Project P-5-533-3 concerning the determination of the structural parameters
of woven filtration materials.
Accordingly, to correlate the values of the resistance coefficient of
the woven filtration material, Kp with some technological and structural
parameters, the effect of these parameters on the value of the resistance
coefficient was examined. Considered were the structural parameters of free
area, calculated porosity, fabric weight, and air permeability. The correla-
tion between free area, determined according to the metrical number of the
yarn (Table B-2), and the resistance coefficient of the fabrics is presented
in Figure 12.
36
-------
TABLE 10. RESISTANCE COEFFICIENTS OF WOVEN FABRICS
Type
of
fabric
Cotton
Dacron®
Dacron®
Nomex®
Nomex®
Nylon
Glass
Glass
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
Fabric number in
Figures 12 through
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Resistance coefficient
KI
0.8828
0.0775
0.1576
0.2192
0.3535
0.9645
1.6271
0.0647
0.1397
0.1263
0.7104
0.2223
0.2374
1.8763
0.2627
The staple filament fabrics, or fabrics having a staple warp or a
staple fill, show the correct correlation. But continuous filament fabrics
show behavior in disagreement with hydraulic principles, increasing in
resistance coefficient with increase of free area. The above disagreement
was observed during the examination of the dependence between the fabric
hydraulic resistance at a constant A/C (q = constant), and the value FA as
reported in the first phase of this project. The hypothesized deformation
of continuous filament yarn, looking to errors between the calculated (the
yarn cross section was assumed to be circular) and true value of FA, was
ascertained by microscope examination.
37
-------
CO
CO
2.0
o
8
8
ft
i.o
70
o 11
fiber
10 15 20
FREE AREA in percent
25
14<
15° ii3
30
Figure 12. Dependence of resistance coefficient K, on free area.
-------
TABLE 11. ADDITIONAL ENERGY LOSSES
Type
of
fabric
Cotton
Dacron®
Dacron
Nomex®
Nomex®
Nylon
Glass
Glass
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
Value of ratio b/q
from 9
equation 10
4.5093
0.1485
0.3699
0.6646
1.6314
4.4496
7.2962
0.2043
0.6409
0.6817
2.7287
2.7478
0.7284
7.0367
0.5939
Considering the above deformation, in the second phase of this project,
FA was also determined by projected sizes. Projected sizes take account of
the deformation of yarns. It appeared that FA calculated in this way took
on negative values, so for further discussion of these structures, the FA
should be assumed to be zero. Thus we come to the conclusion that, for
continuous filament fabrics, FA is not a very selective structural parameter,
especially for fabrics with high yarn count.
Because of the porosity effect on the fabric resistance coefficient,
K-., two porosities were defined. The first was based on the thickness of
the fabric measured under the load (see Table 11) and the second, the thick-
39
-------
TABLE 12. POROSITIES EI AND e2 OF FILTRATION FABRICS
Type
of
f abri c
Cotton
Dacron®
Dacron®
Nomex
Nomex®
Nylon
Glass
Glass
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
Calculated
porosity
£1
0.71
0.73
0.57
0.67
0.62
0.49
0.54
0.72
0.72
0.75
0.43
0.68
0.66
0.65
0.70
Calculated
porosity
£2
0.52
0.70
0.63
0.78
0.58
0.66
0.69
0.74
0.60
0.57
0.60
0.67
0.65
0.66
Note: The following specific densities were assumed for calculation:
glass fiber =2.65 g/cm3, polyester fiber =1.38 g/cm3, polyamide fiber
1.14 g/cm3, and cotton fiber =1.55 g/cm3.
ness of the fabric calculated from technological parameters. The obtained
values of e1 and &2 and are shown in Table 12.
In the diagrams presented in Figure 13 (K, vs. e), the points for
individual fabrics are marked. As seen in the figure, a clear dependency
was not obtained; but the points for the continuous filament fabrics were
particularly dispersed. The correct trend was obtained for the staple fiber
fabrics—the porosity increases with decreasing values of resistance coeffi-
cient Kj. Additionally, the influence of the porosity function (l-e)/e on
K.^ was examined. The obtained dependencies were similar as in the case of
porosity (see Figure 14).
40
-------
H
O
I
O
O
co
M
fr";
-
1.5 '
1.0 .
'
•
0.5--
.
o -
07
06
D 1
O ^1
^ - ° ^ 4
D 3 ^T^g^ 10
Q <£.
1 1 I
0.4 0.5 0.6 0.7 (
0
07
©11
05
15[%313
9 m 03
12 a 2 Q D8
0.8 0.4
0.5 0.6
0.7 0.8
POROSITY 6 1
POROSITY £
Figure 13. Dependence of resistance coefficient K, on fabric porosity.
-------
ro
2.0
1.5
« i.o
Pu
CE C
IST
P
en
07
?
0.3 0.5 0.7
POROSITY FUNCTION
0.9 1.1
1 -e.
07
06
PI
O11
4 05
D 13 cP15 _Q42—
— 8TGT132 2> D
1.3 0.2
0.4
0.6
0.8
POROSITY FUNCTION
Figure 14. Dependence of resistance coefficient K, on porosity function.
-------
Concluding, the above analysis of the effect of porosity on the resist-
ance coefficient K, confirmed the existence of flow peculiarities during
clean air flow through woven structures. It can be assumed that the periodic-
ity of the woven structures causes the specific flow, and that porosity.
which describes flow through homogenous structures, cannot be regarded as a
structural parameter.
Figure 15 shows the correlation between the resistance coefficient K,
and fabric weight, which is an important technological parameter. Despite
the fact that the points are quite dispersed, the dependence is clear. The
conclusion is that increase in fabric weight causes an increase in the
resistance coefficient. An especially quick increase of the curve is ob-
served for continuous filament fabrics. Small changes in fabric weight lead
to considerable increase of the resistance coefficient.
The big difference between continuous filament and staple fiber fabrics
can be observed in the correlation between K, and air permeability. Air
permeability, which is still one of the most important technological param-
eters and simultaneously is a qualitative parameter used for the estimation
of fabric homogeneity, has a noteable relationship with both the resistance
coefficient and filtration resistance.
From the curves presented in Figure 16 an important conclusion, concern-
ing the permissible tolerance of air permeability for woven filtration
fabrics, follows. A wide range of air permeability for staple fiber fabrics
(also texturized) is permissible as long as it does not cause significant
changes in the resistance coefficient, thus lowering the dust collection
efficiency.
But for continuous filament fabrics [very quick increase of value K-, =
f(air permeability)] a wide variation in air permeability tolerance causes
considerable variations in filtration resistance.
In Poland, the tolerance in air permeability is determined by so-called
branch standards concerning the technological requirements that must be met
by fabrics. Table 13 illustrates the air permeability for polyester fabrics.
As seen in Table 13, the range of permissible air permeability is quite wide
and reaches, on the average, 50 percent of the extreme values.
43
-------
4»
•is.
2.0
o
1.0 1
1
H
O6
O11
O 5
12
100
200
300
400
FABRIC WEIGHT In g/ta*
10
500
600
Figure 15. Dependence of resistance coefficient K^ on fabric weight.
-------
en
2.0
O
§
O
1.0
0
0
O14
O?
Q1
06
O11
05
12Ct]4
D10 39
015
Q
3
D13
10 15 20 25
AIR PERMEABILITY in ra3/m2rnin.
30
Figure 16. Dependence of resistance coefficient K, on air permeability.
-------
TABLE 13. AIR PERMEABILITY OF DUST FILTRATION POLYESTER
FABRICS MANUFACTURED IN POLAND
(According to NB-70/7547-05)
Parameter
ET-1
Air permeability
in m3/m2min 11-17
at AP = 20 mmH20
Kind of fabric
ET-3 ET-4 ET-30
15-22 12-18 12-18
Concerning U.S. fabrics, there was not enough technological data for a
full analysis of the effect of air permeability on their resistance coeffi-
cient. It was noted, however, that the air permeability for two shipments
of fabric Q53-878 differed very much and were for the first part 16.78
32 32
m /m min, and for the second part 22.23 m /m min (see Table 14). This
observation leads to the assumption that U.S. standards also have quite
large ranges of tolerance in air permeability for woven filtration materials.
In conclusion, it can be said that:
Air flows through clean woven structures in the range of q =
32 ^
50 - 180 m /m /hr are placed in the transition region of
flow,
The differences concerning the hydraulic properties between
the continuous filament and staple fiber fabrics probably
result from the differences in the character of flow (addi-
tional energy losses),
The complicated character of air flow provides for additional
energy losses, which decrease with increasing q ,
Structural parameters used today, concerning the woven struc-
tures, are not correlated with K-,.
Laboratory Testing of Filtration Fabrics
The results of laboratory testing conducted during this project are
shown in Tables 15 and 16. Figures A-5 through A-34 illustrate differences
46
-------
TABLE 14. AIR PERMEABILITY OF U.S. FILTRATION FABRICS
Type
of
fabric
Cotton
Dacron®
Dacron®
Nomex®
Nomex®
Nylon
Glass
Glass
Air permeability in m3
960
862B
C866B
C892B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
According to
producer
at AP = 0.5 in
--
21.34
12.19
9.14
10.67
5.49
3.05
22.86
10.67
9.14
6.71
12.80
15.85
4.27
14.63
According to
measurements
at AP = 0.5 in
3.14
29.95
18.90
11.58
11.50
7.55
4.93
29.31
12.74
9.43
12.23
11.11
20.04
6.48
16.78*
22.23t
/m2 min
According to
measurements
at AP = 20 mm
4.72
37.36
23.60
14.98
16.60
10.36
7.07
40.13
15.63
12.12
14.64
13.36
22.83
7.84
19.59*
29.16t
* First delivery.
t Second delivery.
of filtration resistances as a function of filtration time. To evaluate the
filtration materials, a comparative analysis was applied. It included all
fabrics in the same raw material group. The two main criteria used for
comparison were the average obtained efficiency of dust collection and its
variation as a function of A/C ratio-, and the obtained filtration resist-
ances at certain values of A/C ratio. Table 17 gives a better presentation
47
-------
TABLE 15. LABORATORY EFFICIENCIES (in percent) OF TESTED
FILTRATION FABRICS (ci = 10 g/m3, LQ = 400 g/m2)
Type % area Efficiency
of filtration in m3/m2 (in
fabric hr) percent)
Cotton Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
/s\
Dacron^ polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex® aromatic nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
Testing with
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
cement
99.962
99.980
99.830
99.744
99.933
99.928
99.943
99.953
99.949
99.935
99.588
98,179
99.871
99.454
99.771
99.867
99.945
99.896
99.948
99.937
99.352
98.642
Outlet
concentration
(In
g/m3)
0.0039
0.0020
0.0173
0.0261
0.0068
0.0070
0.0058
0.0046
0.0050
0.0063
0.0413
0.1789
0.0125
0.0549
0.0231
0.0130
0.0053
0.0106
0.0053
0.0060
0.0658
0.1379
(continued)
48
-------
TABLE 15. (continued)
Outlet
Type ^g area Efficiency concentration
of filtration in m3/m2 (in (in
fabric hr) percent) g/m3)
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
Cotton Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron polyester
Style No. 865B
Style No. C890B
Style No. C892B
60
80
60
80
60
80
60
80
Testing with
60
80
60
80
60
80
60
80
60
80
60
80
60
80
99.962
99.964
97.540
84.633
95.026
86.384
94.513
85.104
separated coal
99.959
99.966
99.894
98.388
99.928
99.928
99.921
99.936
99.949
99.867
99.793
98.644
99.755
99.117
0.0038
0.0036
0.2550
1.5163
0.5083
1.3127
0.5530
1.4682
0.0043
0.0034
0.0110
0.1646
0.0075
0.0075
0.0080
0.0065
0.0050
0.0133
0.0210
0.1367
0.0250
0.0866
(continued)
49
-------
TABLE 15. (continued)
Outlet
Type qg area Efficiency concentration
of filtration in ms/m2 (in (in
fabric hr) percent) g/m3)
Nomex® aromatic nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Testing with
60
80
60
80
60
80
99.906
99.906
99.946
99.960
99.975
99.982
99.687
99.087
99.954
99.984
98.597
82.179
93.032
82.054
96.036
78.321
unseparated coal
99.678
98.743
99.934
99.915
99.945
99.921
0.0095
0.0095
0.0055
0.0041
0.0025
0.0019
0.0318
0.1829
0.0045
0.0015
0.1413
1.7613
0.7088
1.4801
0.4041
2.2051
0.0323
0.1273
0.0065
0.0085
0.0053
0.0080
(continued)
50
-------
TABLE 15. (continued)
Type g area
of filtration in ms/m2
fabric hr)
/B\
Dacron^ polyester
Style No. 865B
Style No. C890B
Style No. C892B
Cotton
Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron® polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex® aromatic nylon
Style No. 852
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Outlet
Efficiency concentration
(in (in
percent) g/m3)
99.874
99.879
99.634
98.763
99.690
99.189
Testing with talc
99.988
99.992
99.869
98.970
99.943
99.943
99.956
99.968
99.970
99.949
99.766
99.376
99.764
99.550
99.957
99.944
0.0123
0.0119
0.0375
0.1244
0.0305
0.0782
0.0012
0.0007
0.0133
0.1060
0.0058
0.0058
0.0045
0.0031
0.0030
0.0051
0.0243
0.0612
0.0245
0.0448
0.0043
0.0057
(continued)
51
-------
TABLE 15. (continued)
q
Type g area
of filtration in m3/m2
fabric hr)
Style No. 853
Style No. 190R
(R)
Nomex^ aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
Cotton Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron® polyester
Style No. 865B
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Outlet
Efficiency concentration
(in (in
percent) g/m3)
99.944
99.919
99.965
99.973
98.996
87.416
99.970
99.972
88.647
70.319
93.647
85.974
91.743
80.808
Testing with fly ash
99.980
99.989
99.741
99.760
99.845
99.795
99.887
99.895
99.895
99.781
0.0057
0.0082
0.0035
0.0027
0.1013
0.2645
0.0030
0.0029
1.2048
2.9567
0.6648
1.4140
0.8363
1.8464
0.0023
0.0011
0.0260
0.0440
0.0158
0.0206
0.0114
0.0107
0.0109
0.0220
52
(continued)
-------
TABLE 15. (continued)
q
Type g area
of filtration in m3/m2
fabric hr)
Style No. C890B
Style NO. C892B
Nomex® aromati c nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Outlet
Efficiency concentration
(in (in
percent) g/m3)
99.905
99.589
99.947
99.468
99.850
99.771
99.907
99.844
99.869
99.954
99.675
99.575
99.897
99.831
99.195
97.841
99.135
98.044
99.184
97.321
0.0094
0.0409
0.0058
0.0510
0.0155
0.0223
0.0093
0.0151
0.0133
0.0048
0.0328
0.0416
0.0105
0.0172
0.0081
0.2132
0.0877
0.2007
0.0838
0.2710
53
-------
TABLE 16. FILTRATION RESISTANCES AT LABORATORY TESTING (in
Type
of filtration
fabrics
Cotton
Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex® aromatic nylon
Style No. 852
Style No. 853
qg
(in
m3/m2 hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Separated
cement
31.60
48.35
22.51
37.45
22.21
36.42
23.70
38.24
32.31
60.99
43.06
66.05
58.86
99.22
20.22
38.71
18.80
38.24
Separated
coal
39.97
77.58
28.44
59.09*
35.63
67.31
31.60
65.57
40.93
77.42
63.60
107.76
66.99
126.56
31.44
59.72
30.89
65.65
Kind of dust
Unseparated
coal
—
18.87
41.00*
20.35
46.05
21.27
48.82
25.15
65.41
42.58
43.38
45.35
100.01
—
—
Separated
talc
36.28
68.41
28.52
38.63
22.83
41.23
25.09
44.16
35.15
71.73
54.11
95.43
60.91
113.60
23.46
47.80
26.23
47.87
Separated
fly ash
17.03
38.87
12.64
26.07
13.37
26.62
12.64
24.88
20.16
41.87
23.04
48.90
26.70
65.57
10.90
21.05
11.75
23.13
(continued)
-------
TABLE 16. (continued)
01
Type
of filtration
fabrics
Style No. 190R
Nome>o^ aromatic nylon
Style No. 850B
Nylon poly amide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Glass
Style No. Q53-878
qg
(in
m3/m2 hr)
60
80
60
80
60
80
60
80
60
80
60
80
Separated
cement
20.29
37.32
44.64
73.79
21.68
36.18
43.45*
63.04*
59.09*
88.32*
33.58*
44.71*
Separated
coal
29.48
66.36
53.56
99.86*
29.15
59.33
54.04
64.46*
58.46*
92.43*
45.51*
49.53*
Kind of dust
Unseparated Separated
coal talc
27.34
50.09
47.40
92.75
20.79
46.61
34.13
39.50
58.70
79.95
30.18
40.61
Separated
fly ash
11.44
27.77
23.96
48.43
13.21
25.99
33.49
60.75
39.34
84.37
28.75
53.01*
*0bserved ducts/canals formation.
-------
TABLE 17. CLASSIFICATION OF FABRICS ACCORDING TO OBTAINED OUTLET CONCENTRATION
Kind %
nf Mn
dust m3/m2hr) Below 0.0025-
0.0025 0.0050
Sep. cement 60 960
865B
802B
80 960 C868B
802B
Sep. coal 60 190R 960
865B
802B
80 190R 960
802B 853
Unsep. coal 60
80
Sep. talc 60 960 C868B
865B
852
190R
802B
Outlet
0.0050-
0.01
C866B
C868B
853
190R
C866B
865B
190R
C866B
C868B
852
853
C866B
C868B
852
C866B
C868B
C866B
C868B
C866B
853
concentration in
0.01- 0.05-
0.05 0.1
862B 850B
C890B
C892B
852
862B C892B
852
853
862B
C890B
C892B
850B
865B C892B
862B
865B
C890B
C892B
865B C892B
862B
C890B
C892B
9/m3
0.1-
0.5
Q53-875
C890B
850B
Q53-875
Q53-878
862B
C890B
850B
862B
C890B
850B
0.5- Above
1.0 1.0
Q53-870
Q53-878
Q53-875
Q53-870
Q53-878
Q53-870
Q53-875
Q53-870
Q53-878
Q53-870 Q53-875
Q53-878
(continued)
-------
TABLE 17. (continued)
en
Kind 9g Outlet
U 1 V • I '
dust m3/m2hr) Below 0.0025- 0.0050-
0.0025 0.0050 0.01
80 960 C868B C866B
190R 865B
802B 852
853
Sep. fly ash 60 960 C890B
C892B
853
80 960 190R
concentration in g/m3
0.01- 0.05- 0.1- 0.5-
0.05 0.1 0.5 1.0
C892B C890B 862B
850B
862B Q53-875
C866B Q53-870
C868B Q53-878
865B
852
190R
850B
802B
862B Q53-875
C866B Q53-870
C868B Q53-878
865B
C890B
C892B
852
853
850B
802B
Above
1.0
Q53-875
Q53-870
-------
of the obtained results. It classifies the individual types of fabrics
according to calculated final concentrations following specific filtration
cycles.
Cotton and Nylon Fabrics
Because cotton and nylon fabrics were represented by only Cotton 960
and Nylon 802B, they will be discussed in one chapter, in spite of the fact
that they are two different kinds of fabrics.
These two fabrics appeared to have the highest dust collection effi-
ciency among all fabrics tested. It is very interesting to notice that
fabric Nylon 802B, independent of the test dust (except fly ash) and the A/C
ratio always showed a dust collection efficiency, E = 99.96 percent. With
fly ash, dust collection efficiency decreased considerably to the value E =
99.89 percent at q = 60 m /m hr, and decreased even more to E = 99.83
9 3 p
percent at q = 80 m /m hr.
y
Both fabrics showed the tendency to increase dust collection efficiency
at increasing A/C ratio. This tendency is probably caused by electrostatic
effects.
It was found that such high dust collection efficiency results from
staple fibers used for fabric production (cotton fiber has definite sizes)
and from good filling of spatial and superficial structure by fibers.
Staple fibers tend to fill partly free areas in the fabric with "free fibers."
The effect of "free fibers" on fabric structure is illustrated in Figure 17.
Filtration resistances measured by static pressure gradient at q =
constant at the end of the filtration cycle (see Table 16), are different
for these fabrics. Fabric Cotton 960 shows higher filtration resistances,
which is characteristic for this group of fabrics. Fabric Nylon 802B is
characterized by low values of filtration resistances. It was observed that
fly ash produces the lowest values of filtration resistances for both fabrics
and these values are similar. This is interesting because the degree of
pulverization for all the test dusts is the same or similar, so the spatial
structure of the dust cake built on the fabrics should be similar, giving
comparable hydraulic effects. To explain this phenomenon the following
hypothesis was made: the fly ash particles differ from particles of all the
other test dusts. This hypothesis was proven by microscopic examination of
the dusts.
58
-------
Photo credit: SEM by K. Skudlanski, Electronic Microscopy Laboratory of
Wroclaw Polytechnic.
a. Cotton style no. 960
b. Nylon polyamide style no. 802B
Figure 17. Superficial structure of fabrics,
-------
Polyester Fabrics
Polyester fabrics make up the largest group of test fabrics but the
fibers, as well as technological parameters, that make up this fabric group
differ very much. The effect of staple fibers vs continuous filament fibers
on filtration efficiency and on hydraulic resistance are very apparent.
The lowest value of efficiency in the group of polyester fabrics was
recorded for fabrics C890B and C892B manufactured with polyester continuous
filament fiber—values a little lower than those for fabric 862B manufac-
tured with polyester staple fiber. Fabric 862B has a much more porous
structure than the other fabrics.
The big decrease of filtration efficiency below 99 percent, when test-
3 2
ing with coal and talc dusts, and at an A/C ratio of 80 m /m hr, was caused
by dust cake cracking and the formation of ducts/canals. The distribution
of ducts/canals on the dust cake surface is shown on Figure 18. The mechanism
of duct/canal formation is caused by dust cake structural defects and is a
result of the static pressure gradient. The ducts/canals are observed in
the areas of the structure not filled with fibers (areas between threads).
The formation of ducts/canals was also observed during the testing of fabric
C890B with cement and separated coal dust.
Staple fiber fabrics C866B and C868B have the best filtration properties,
taking laboratory filtration efficiency as a criterion. The obtained filtra-
tion efficiencies were 99.9+ percent for all types of dusts and two levels
of A/C ratio. Slightly poorer properties were shown by continuous filament
fabric 865B and staple fiber fabric 862B. Filtration resistances of these
three types of polyester continuous filament fabrics are two times higher
than those of the polyester staple fiber fabrics.
The additional testings were conducted for polyester fabrics using
unseparated coal dust to obtain more results necessary for analysis on a
large scale. Large scale tests were conducted only on unseparated coal dust
because of the explosive hazard associated with preparing and handling a
size-separated coal dust sample.
The difference in the particle size distribution of the separated and
unseparated dusts is quite large. Average particle size is:
Unseparated dust d™ = 28 urn (MMD)
Separated dust d5Q = 7.5 \jm (MMD).
60
-------
Figure 18. Ducts/canals distribution on polyester fabric
covered with talc (style no. 865B).
61
-------
In spite of large differences in the fractional composition of the
laboratory scale test dusts filtration efficiency is similar. Filtration
resistances of the unseparated dusts were 30-45 percent lower than those of
the separated dusts. Again, as with the cotton and nylon fabrics, the
lowest filtration resistances of the polyester fabrics were with fly ash.
Nomex Fabrics
The results obtained during Nomex fabric testing are similar to those
of the polyester fabrics.
Much worse filtration properties are observed for continuous filament
fabric 850 than for the other fabrics. The formation of ducts/canals was
observed during testing of fabric 850 with cement and separated coal dust.
The formations had a great influence on the filtration efficiency. The
fabric showed good filtration properties only for fly ash.
Figure 19 compares the surface structure of the two types of Nomex
fabrics. As before Nomex fabrics showed the lowest filtration resistances
when filtering fly ash.
Glass Fabrics
Among the efficiencies obtained for all kinds of fabrics and types of
dusts used, the lowest values of filtration efficiency were observed for
glass fabrics tested at laboratory scale.
The low values of efficiency are caused by duct/canal formation, which
favors the process of dust particle penetration through the fabric/dust
structure. Duct/canal formation is characteristic of glass fabrics. Glass
fibers have a very small coefficient of friction, which is why threads and
fibers displace during the production process, creating "free areas" not
filled with fabric material.
These free areas can increase their surface area during air flow and
thereby increase their effect on the average dust collection efficiency.
Comparing the calculated final concentration determined from experimental
data, very apparent effects of structural parameters on filtration properties
can be observed. They are included in Table 17. (In this table, the final
concentrations were placed in classes that enable the analysis of fabric
behavior under the different kinds of dust and A/C ratios. Concerning the
glass fabrics, the considerable increase of final concentration with increas-
ing q was observed. It is explained by duct/canal formation.)
y
62
-------
Photo credit: SEM by K. Skudlanski, Electronic Microscopy Laboratory of
Wroc/Iaw Polytechnic.
a. Staple fibers (style no. 853)
b. Continuous filament fibers (style no. 850B)
Figure 19. Comparison of surface structure of staple and
continuous filament Nomex fiber fabrics.
63
-------
TABLE 18. NUMBER OF DUCTS/CANALS OBSERVED IN LABORATORY TESTING
(Testing of glass fabrics with separated coal dust)
Kind of Fabric
Q53-875
Q53-870
Q53-878
A/C(m3/m2hr)
60
80
60
80
60
80
Number of ducts/canals
102
16
42
7
69
The number of ducts/canals is quite large, as presented in Table 18
2
which gives the number per 100 cm for separated coal dust (laboratory
scale). There is a correlation between the number of formed ducts/canals
and the filtration efficiency.
The operating conditions of the laboratory tests are too severe to be
practical for field use of the glass fabrics. The formation of canals dur-
ing the filtration process is an undesirable situation.
By relating duct/canal formation to an upset of force balance in the
dust cake structure (and which depends upon the dust properties and the
superficial structure of fabric), the hypothesis can be made that there is a
certain value of static pressure gradient for each fabric/dust cake system
which results in static balance. It is possible to estimate this value
experimentally, determining simultaneously the highest permissible A/C. The
formation of ducts/canals was confirmed by Holland's examination (ref. 11).
The problem of defects formation in dust cake structure should be verified
in Dust Filtration Process Type Ill—conditions characteristic of industrial
dust collectors.
Filtration resistances in glass fabrics are higher than those for
polyester and Nomex fabrics. The highest values of resistance are reached
by glass fabrics made of continuous filament fabric Q53-870. It is interest-
64
-------
ing that the application of texturized yarn in the fill of fabric Q53-878
did not cause an increase in efficiency, compared to continuous filament
fabric Q53-870, but caused only a decrease in filtration resistance. A
similar effect of yarn texturization on the filtration properties of glass
fabric was observed during the testing of Polish prototype glass fabrics.
Testing of Duct/Canal Formation Mechanism
Taking into consideration the importance of the effect of duct/canal
formation on the most representative qualitative parameter of filtration—
dust collection efficiency—additional testing and structural examination
were conducted to learn more about the mechanism of duct/canal formation.
Tests-
Tests were carried out on a laboratory stand according to the method
prescribed in a previous report. Glass fabric Q53-878 and separated cement
dust were used for the testing.
3 2
Two series of test were made over an A/C range of 50 - 200 m /m hr.
The first series, the results of which are presented in Table 19, was to
determine the dependence of canal number density upon A/C. The second
TABLE 19. NUMBER OF DUCTS/CANALS OBSERVED DURING TESTING OF
FABRIC STYLE Q53-878 - SERIES 1
(TEMPERATURE: 20-22° C, RH = 61-64%, B = 740 mmHg)
Gas
loading
of filtra-
tion area
(A/C) m3/m2hr
50
60
80
100
120
150
200
Final
pressure
drop
mmH20
29.62
33.97
51.35
61.62
72.68
79.00
96.38
Dust
loading
of filtra-
tion area
g/m2hr
465.5
698.4
870.4
1,075.0
1,093.2
1,296.0
1,804.0
Dust
covering
of filtra-
tion area
g/m2
195.5
230.5
217.6
215.0
185.8
168.5
180.4
Number
of
ducts/
canals
_ _
1
21
96
140
200
260
65
-------
series was conducted twice (experiments 1 and 2) and was to determine the
size as well the number of canals as a function of A/C ratio. The results
are shown in Table 20 and Table B-3. The main reason for the testing was to
obtain the dusty fabric samples for the counting and measurement of the
canals; a similar dust cover was used in both the first and the second
series.
The dependence of the number of canals upon A/C ratio and final pressure
drop is presented in Figure 20. The correlation can be seen, but because of
the small number of measurements, this correlation cannot be expressed
analytically.
TABLE 20. NUMBER OF DUCTS/CANALS OBSERVED DURING TESTING OF
FABRIC STYLE Q53-878 - SERIES 2
(TEMPERATURE: 20-22° C, RH = 61-64%, B = 740 mmHg)
Gas
loading
of filtra-
tion area
(A/C) m3/m2hr
50
60
80
100
120
150
200
Final
pressure
drop
mmH20
17.40
26.81
63.20
79.00
88.48
106.70
158.00
Dust
loading
of filtra-
tion area
g/m2hr
500
600
800
1,000
1,200
1,500
2,000
Dust
covering
of filtra-
tion area
g/m2
85
102
200
200
216
195
400
Number
of
ducts/
canals
—
3
2
39
43
66
48
90
100
180
160
210
66
-------
3 200
|
GO
Q
u_
o
LU
CO
100
0
A/C in m3/m2 hr
200
to
t/J
o
o
u.
o
on
LU
CO
200
100
Figure 20.
0 50 100 150
FINAL PRESSURE DROP in nunHgO
Relationship between number of ducts/canals and:
1) A/C, and 2) final pressure drop.
67
-------
Based on the data from Table B-3 (the results of measurements of the
geometrical size of the ducts/canals), verification of canals of equivalent
diameter size distribution was done by applying the Kolmogorov A. criterion.
The equivalent diameter was considered a characteristic value because
of the kind of hydraulic phenomena occurring during duct/canal formation.
Figures 21 and 22 show the equivalent diameter distribution for experiments
1 and 2, the second series of testing. The hypothesis of a normal distribu-
tion was confirmed in 50 percent of the cases at a significance level of a =
0.05. It is presumed that by increasing the number of experiments, there
would be no basis for rejecting the hypothesis of a normal distribution.
The confirmation of the normal distribution hypothesis was very important
because during the development of the probabilistic model of the dust filtra-
tion process (Project 5-533-3) it was ascertained that the structural pro-
perties of fabrics have a normal distribution.
Table 21 includes the sizes and standard deviations of the mean equiva-
lent diameter. From these values the average equivalent diameter, independent
of A/C ratio, is in the range of 80-85 urn. Despite the large standard
deviation, the data lead to the conclusion that the woven structure has a
large surface area, a characteristic that influences dust cake defects. As
a result of this conclusion, additional microscopic examinations of the
clean fabric structure and of the dust cake surface were made.
Structural examination of fabrics - "basket effect"—
Microscopic examination of the model fabric (hemp cord of weave 3/1)
was made in order to obtain information about free area formation between
the fill and warp yarns. It appeared (Figure 23) that the model fabric,
which did not show the free areas in a vertical (normal) direction to the
surface, has characteristic right triangles of not-filled areas between the
fill and warp yarns, oriented, askew to fabric surface, but normally (verti-
cally) to fill years (Figure 23b).
The decision was made to carry out structural microscopic examination
of all test fabrics. The examinations were done by the Electronic Micro-
scopy Laboratory of Wroc/aw Polytechnic, directed by Dr. Krzysztof Skudlarski.
A scanning microscope Stereoscan 180, manufactured by Cambridge Instruments
in England, was used for the examinations.
68
-------
en
II
IT
0,4
0.3_
0.2-
0.1-
r
x
•
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
X
X
X
X
\
\
\
X
X
x
X
X
x
X
X
X
X
\
X
X
X
X
X
\
X
r
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
^
X
X
X
X
\ ^
\ XI
V V 1
0
V 80
nr= 79.5 ym
G = 66.4 ym
N = 31
Normal
(^
rx
r\
[\
^
\
X
X
X
X
X
X
X
X
\
X
X
X
X
X
X
^
X
X
X
x
X
X
X
X
X
X
X
X
X
X
X
X
X
n
\
X
X
X
X
X
X
X
X
x
x
\
X
\
s
X
X
X
X
X
X
X
X
X
X
X
x
\
X
X
X
xl
yj
^J
x]
q = 100
my = 80.0 ym
G = 29.8 ym
N = 20
Normal
x
X
X
X
\
\
\
X
X
X
x
X
X
X
X
X
X
\
X
X
X
V
T
\
\
\
\
\
\
\
\
X
\
\
x
\
\
\
X
X
\
X
\
\
\
\
\
\
\
\
\
\
\
^T
X
X
X
X
x
\
x
x
x
\
\
x
x
v
^
>l
Iq = 12°
r = 86.1 ym
G = 73.6 ym
* = 28
formal
E
T
X
S
\
X
X
X
\
X
\
X
X
X
X
X
\
\
\
X
\
\
\
v
x
x
\
\
x
x
x
\
\
X
X
X
\
X
X
x
x
X
X
X
X
X
X
\
\
^
x
x
\
\
\
X
\
X
X
X
\
'
\
X
X,
X
X
X
x
\
X
1
OT
q = 150
FIT = 81.6 ym
G = 89.2 ym
N = 47
^
X
\
V
\
\
\
\
\
\
\
X
\
\
X
X
\
X
X
x
X
X
x
x
X
X
X
X
X
X
X
s.
\<
x
\
\
V
\
V
\
x
x
X
\
X
\
X
x
\
0
\
x
x
X
X
\
\
x
X
x
x
X
\
X
X
\
X
X
X
x
X
^\
\
•
*x
x
X
X
X _
\ x/
X X
X X
\ \
X X
^ Vs
qq = 200
my = 73.2 ym
G = 62.2 ym
N = 52
Figure 21. Histogram showing the size distribution of duct/canal
equivalent diameter (exp. 1, series 2).
-------
0.5
0.4 "
0.3 -
0.2 -
0.1 .
^
s
s
S
•
s
s
s
\
\
s
\
^
\
\
s
s
\
^
s
s
s
\
\
rr
\
s
s
s
\
s
\
s
s
\
\
s
\
\
\
\
s
s
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
CT
sj
o
q = 80
m9 = 84.7 ym
5 = 15.8 ym
N = 35
rv
KJs
KK
KJs
KJs
^
\
\
\
\
s
\
\
\
s
\
\
\
\
\
s
\
\
\
\
\
\
\
\
s.
\
\
\
\
\
\
\
\
\
\
\
\
\
\
s
\
\
\
\
T1
\
\
\
\
\ ^^
\ VfNj
s S|N
\ six]
S. vK.1
q = 100
m9 = 98.7 ym
G = 69.9 ym
N = 15
Normal
Mi
\
\
\
\
\
\
\
\
\
\
\
\
\
^
m
\
\
\
\
\
\
\
\
\
\
\
\
\
\
S
\
\
n
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
s
r
\
\
\
\
\
la = 120
r = 87.0 ym
G = 40.7 ym
1 = 23
r
b
«
\
s
s
\
s
\
s
s
s
s
\
s
\
s
V
s
\
\
s
\
N
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
s
«
s
s
\
\
s
s
s
\
s
s
\
\
\
s
N
\
s
\
\
V
^
sj
\^l
OKI
q = 150
m9 = 82.1 ym
G = 63.1 ym
N = 42
?
N
\
V
S
s
s
s
s
•s,
s
s
s,
s
\
s
\
X
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\!
^
\
\
\
\
\
\
\
\
\
S
\
\
\
\
\
\
T
\
\
\
\
\
\
\
\
q = 200
my = 81.5 ym
G = 50.8 ym
N = 33
Normal
Figure 22. Histogram showing size distribution of duct/canal
equivalent diameter (exp. 2, series 2).
-------
TABLE 21. AVERAGE EQUIVALENT DIAMETER FOR EXPERIMENTS OF SERIES 2
Gas loading of
filtration area
(A/C) m3/m2hr
1
80
100
120
150
200
Mean equivalent
diameter
urn
2
79.59
84.70
80.80
98.70
86.10
87.00
81.60
82.15
73.20
81.50
Standard
deviation
urn
3
66.4
15.8
29.8
69.9
73.6
40.7
89.2
63.1
62.2
50.8
Figure 24 shows two characteristic types of free area appearing in the
fabric structure. The first type, already taken into consideration and
characterized by FA, is in the fabric plane. The second type, related to
the canal formation phenomenon and not included in the FA value, occurs in a
plane askew to the fabric surface. The average size of the equivalent
diameter (based on photographs) for the free areas viewed in an askew plane
is 100 - 150 urn. Considering the very poor and not representative photo-
graphical material, it can be said preliminarily, that structural examina-
tion confirms the experiments in which the statistical equivalent diameter
of the canals was calculated to be 80-85 jjm. More careful photographic
examination of canal shapes and their spatial composition confirms their
askew direction to the fabric plane (Figure 25) and is consistent with askew
placement of free areas in the fabric.
Because of their characteristic shape and similarity to the spatial
structure of wicker products, the newly recognized existence of askew free
areas and their relationship to dust cake defects was called the "basket
71
-------
a. Vertical view
b. Askew view
Figure 23. Superficial structure of model fabric,
-------
I
Figure 24. Kinds of free areas in woven structure (Q53-878).
73
Photo credit: SEM by K. Skudlanski, Electronic Microscopy Laboratory of
Wrocjaw Polytechnic.
-------
' **-
Figure 25. Duct/canal shape.
74
-------
effect." It can be preliminarily said that the basket effect depends mainly
on the kind of weave, the kind of fiber and its raw material, and also on
yarn diameter and take-up degree of warp and fill. Continuous filament
yarns of high elasticity favor large free area formation, so the basket
effect is very apparent on such fibers (glass fabric). Staple fiber yarns
of lower elasticity show smaller basket effects. More detailed discussion
of this problem will be included in the final report of Project 5-533-3.
Filtration Resistance Variation in Laboratory Testing
The linear regression method was used for calculating laboratory and
large scale filtration resistances. The data were obtained from measurement
reports that are enclosed in this report or are in the archives of IPWMB.
Equations approximating the time increase of filtration resistance by straight
lines were obtained. The effective drag and the fabric-dust resistivity
were calculated from these equations with the help of dependencies (4) and
(5). The results are compiled in Table 22.
Table 22 is also auxiliary material for the discussion of increase of
filtration resistance in time, discussed in the next section of this document.
CONCLUSIONS
Under test conditions, i.e., at a specific A/C ratio and its dust
cover and for the separated dusts of cement, coal, talc, and fly
ash, the following fabrics can be regarded as satisfactory from a
qualitative point of view:
cotton fabrics: style 960;
polyamide fabrics: style 802B
polyester fabrics: styles 865B, 862B, C866B, and C868B;
Nomex fabrics: styles 190R, 852, and 853;
glass fabrics: style Q53-875.
Polyester and Nomex fabrics made with continuous filament and
polyamid fabric 802B achieve good filtration properties at lower
A/C, q = 60 m3/m2hr.
Test conditions were too rigid for the glass fabrics because of
their structural and mechanical parameters; the consequent forma-
tion of dust cake defects in the form of ducts/canals considerably
decreased their filtration efficiency.
75
-------
CTl
TABLE 22. EFFECTIVE DRAG S£ [in (mmH20/m/hr)] AND SPECIFIC RESISTANCE
COEFFICIENT K2[in (mmH20/m/hr)/(g/m2)] IN LABORATORY TESTS
Type
of
fabric
Cotton
960
Dacron®
862B
C866B
C868B
Dacron®
865B
C890B
C892B
Y
in m3/
m2hr
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Effective drag SE
Sep.
cement
4.6
6.3
0.5
0.7
-0.9
1.8
1.5
2.1
5.4
13.9
17.5
21.8
25.2
40.0
Sep.
coal
1.5
1.3
-4.4
-5.7
-3.4
-4.7
-2.4
0.7
1.4
0.4
14.8
17.3
22.1
31.9
Unsep.
coal
—
-0.9
-3.3
-0.3
-2.5
-1.1
-2.8
2.0
4.2
11.2
19.1
17.2
31.9
Sep.
talc
0.7
0.3
-3.2
-2.0
-2.7
-0.3
10.2
-1.9
0.4
3.3
11.5
15.1
18.8
28.7
Sep.
fly
ash
5.1
6.6
1.1
0.8
0.9
1.1
1.5
2.1
6.1
10.1
11.9
18.9
17.7
32.1
Specific resistance coefficient K2
Sep.
cement
0.07
0.07
0.05
0.07
0.06
0.06
0.05
0.06
0.07
0.08
0.06
0.07
0.08
0.08
Sep. Unsep.
coal coal
0.09
0.14
0.08
0.12
0.10
0.13
0.08
0.12
0.10
0.13
0.12
0.15
0.11
0.16
--
0.05
0.08
0.05
0.09
0.05
0.09
0.06
0.11
0.08
0.12
0.07
0.10
Sep.
talc
0.09
0.12
0.08
0.07
0.06
0.06
0.02
0.08
0.09
0.12
0.10
0.13
0.10
0.13
Sep.
ny
ash
0.03
0.05
0.03
0.04
0.03
0.04
0.03
0.05
0.04
0.05
0.03
0.04
0.02
0.04
(continued)
-------
TABLE 22. (continued)
Type
of
fabric
Nomex®
852
853
190R
Nomex®
850
Nylon
802B
Glass
Q53-875
Glass
Q53-870
Q53-878
qg
in m3/
m2hr
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Effective drag SF
' Sep.
cement
-0.3
2.5
0.7
15.4
-2.2
-3.7
20.6
20.2
-0.3
-0.2
6.7
18.1
25.0
28.1
8.3
4.8
Sep.
coal
-4.0
-7.2
2.5
-3.6
-3.3
-6.8
12.7
18.6
-0.9
-1.4
12.3
15.6
21.0
24.7
7.7
12.1
Unsep. Sep.
coal talc
-2.
-3.
-1.
-4.
-2.
-3.
13.
11.
-0.
-2.
6.
4.
18.
20.
7.
-0.
0
8
8
3
2
1
7
5
9
4
7
3
1
8
1
6
Sep.
fly
ash
1.4
0.6
0.3
0.7
0.4
-0.6
12.6
17.0
1.2
0.7
11.6
20.9
22.5
34.4
11.3
17.0
Specific resistance coefficient K2
Sep.
cement
0.05
0.06
0.04
0.07
0.05
0.07
0.06
0.08
0.05
0.12
0.07
0.07
0.08
0.08
0.06
0.08
Sep.
coal
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
Unsep.
coal
08
12
08
13
08
13
10
14
08
11
10
08
09
11
09
06
Sep.
talc
0.06
0.09
0.07
0.09
0.07
0.10
0.08
0.14
0.05
0.09
0.07
0.06
0.10
0.10
0.06
0.09
Sep.
fly
ash
0.02
0.03
0.03
0.04
0.03
0.05
0.03
0.05
0.03
0.04
0.05
0.06
0.04
0.07
0.04
0.06
-------
Observed and documented large ranges of final concentrations
(varying with the fabric type and depending upon the type of dust
and the A/C) are characteristic of Dust Filtration Process Type
I—when the structure has not yet reached the state-of-balance.
Duct/canal formation during dust filtration through woven filtra-
tion materials was explained.
The effect of fabric structure on dust cake defects via the basket
effect was ascertained. Basket effect is connected with the
presence of not-filled-by-yarn areas askew to the fabric surface.
The degree of the effect depends upon the technological parameters
of the materials.
78
-------
SECTION V
LARGE SCALE TESTING OF FILTRATION
INTRODUCTION
Large scale testing is a main phase of the qualitative testing of the
filtration materials. The dust collection efficiency and the filtration
resistance as a function of A/C are estimated.
Because the filtration process in large scale (Dust Filtration Type
III) is equivalent to the processes taking place in an industrial fabric
dust collector, the experience obtained during large scale experimentation
can be applied directly to engineering research and practice.
The basic objective of the large scale experiments is the determination
of all relevant dependencies among the process parameters after the filtra-
tion test material has reached a state-of-balance under a specific set of
test conditions. The state-of-balance is characterized by a constant gradient
of static pressure after regeneration (AP^i/) and, corresponding to it, a
constant amount of dust (LNK) remaining in the spatial structure of the
filtration material.
Because large scale testing is very labor-consuming, the basic test
experiments, determining the total efficiency and filtration resistance,
usually include measurements of fractional efficiency regeneration suscept-
ibility, etc. so that test results are enriched.
As with the laboratory scale tests, the absence of a theoretical base
for the process favors a comparative analysis of test results. For constant
fabric test conditions, the quality of the filtration fabrics is very often
estimated from the outlet dust concentrations.
According to Stephan, Walsh, and Herrick, filtration resistance depends
on the filtration material and dust and can be easily analyzed and compared
after the determination of the empirical effective drag and permeability of
a dust-fabric system. However, this interpretation is not entirely accurate
79
-------
since unequal dust cake often exists on different filtration material surfaces,
both before and after regeneration. The calcuated factors, based on mean
measurement values, reveal specific fabric properties that depend on the
type of dust and the filtration parameters.
The determination of the true value of the dust cover on the filter is
an important element of large scale testing. Usually with test stands the
dust is introduced to the hopper and then to the filtration bag. The mechanical
efficiency of the hopper depends on the kind of dust and its pulverization,
and also on the gas velocity. So, basing the examination only on the measure-
ment of dust fed to the test stand, we obtain an effective drag and perme-
ability of the dust-fabric system, but they cannot be compared to other
tests.
The big disadvantage of large scale testing is that there is no chance
to observe the surface of the filtration test material after contact with
the dust. Defects in dust cake structure and also the appearance of other
effects, e.g., basket effect, can be deduced only from the obtained measure-
ment values.
EQUIPMENT AND PROCEDURES
Large scale testing of EPA-selected filtration fabrics was conducted on
an apparatus specially designed by IPWMB (single compartment baghouse). The
apparatus is illustrated in Figure 26 and includes a filter chamber, collec-
tion hopper, dust feeder, fans, pipelines and valves, and a control and
measurement system.
The filter chamber, of cylindrical form, (diameter 700 mm and length
3,520 mm) is composed of four separate sections tightly connected together.
This type of construction permits the filter bags to be of various lengths.
The last section of the filter chamber is the head, on which an arbitrary
mechanical regeneration system can be installed. The filter chamber is
thermally insulated. There is a collection hopper in the lower part of the
filter chamber. The filter bag, 710 to 3,250 mm in length and 200 mm in
diameter, is installed off center from the filter chamber axis because of
the presence of an isotopic probe used for the measurement of dust cake
thickness deposited on the filter bag. The total filtration area is 2.01 m2
80
-------
Figure 26. Illustration of large-scale stand,
81
-------
o
and the net area, 1.884 m . A diagram of the single compartment baghouse
with a control and measurement system is shown in Figure 27. The test dust
is fed into circulation by a screw dust feeder with a capacity of 0.5 to 15
kg/hr ± 10 percent. A variable gear regulates the capacity of the screw
dust feeder.
The single compartment baghouse is equipped with two fans:
1. Main fan - type MWW 14, used for keeping negative pressure in
all test apparatus and for producing gas flow throughout the
filter chamber. Main fan capacity is 1,200 m /hr and total
pressure is 600 mm of water.
2. Reverse air fan - type WP 20/1, used for reverse air flow (in
the opposite direction to the gas flow during the filtration
process). Reverse fan capacity is 1,200 m /hr and total
pressure is 300 mm of water.
Both the reverse and circulating gas systems are equipped with elec-
tric heaters, type NP-27, so as to maintain dry filtration conditions in the
filter chamber. Control valves on the pipelines allow control of the A/C at
the desired values and assure continuous load on the fans. Actuations of
particular systems and instruments of the single compartment baghouse are
remotely controlled from the control desk in the operational room.
The control system works either in a manual mode or an automatic mode
according to one of the following three variants of filter bag regeneration:
1) reverse air flow regeneration, 2) mechanical regeneration, or 3) mechanical
regeneration with simultaneous reverse air flow. It is equipped with several
sensors and control-measurement devices for recording the following parameters:
Humidity of gas,
Temperature of gas,
Rate of flow,
Static pressure,
Dust concentration before and after filter chamber,
Time of particular filtration cycles, and
Temperature and humidity of air in the laboratory.
General experimental conditions are:
Maximum length of filter bag: 3,500 mm,
82
-------
MECHANICAL SHAKER
00
GJ
(VIBRATOR)
FILTER BAG
DUST FEEDER
BAG DAMPER
INLET OF AIR
ELECTRIC HEATER *p
COLLECTION HOPPER
INCLINED
OF REVIAIR
MANOMETER
ELECTRIC H.
REVERSE FAN
Figure 27. Diagram of the large-scale test stand.
-------
Construction of filter bag: as in Figure 28,
Dispersion medium: atmospheric air without any adjustable param-
eters,
Regeneration system: reverse air flow and mechanical vibration
but without reverse air flow during the last cycle before a-
measurement,
Manner of regeneration: as shown in Figure 29,
Reverse air loading: 20 percent more than A/C during filtration
cycle,
Measurement of dust concentration after filter chamber: by aspira-
tion method (in some measurements particle size distribution was
done with an Andersen cascade impactor),
Conduction of experiments on bags fully filled with dust: by
multiple repetition of filtration-regeneration cycles.
A detailed description of the preparatory and auxiliary work performed
during large scale fabric testing was included in the periodical report of
phase I of this project.
The dust collection efficiency of the one-bag compartment was deter-
mined by weighing the dust in the cleaned gases. The total efficiency was
calculated from the relation:
G "* G
'T1
100 =
100 (11)
where: E,-, = total efficiency, in percent,
G = total weight of the dust introduced to the hopper
of the test chamber, in grams,
GQ = weight of dust in the cleaned gases (measurement of
dust emission), in grams,
c.j = initial dust concentration fed to the compartment, in
g/m , and
c = outlet3dust concentration from the compartment,
in g/m .
In addition to the total efficiency of the one-bag compartment, the hopper
efficiency and bag efficiency were calculated by the dust balance method
(weighing method). In this method the total efficiency was calculated from
the relation:
E = GH + GB + GR + GN x 100
c
where: ET? = total efficiency, in percent,
84
-------
500
8
700
B
_2QQ_
3300
700
00
en
COTTON ROPE
JP/5
W
400
8-6
1:1
WIRE RING
Figure 28. Construction of bags.
-------
FILTRATION
Delay
1 minute
Re-
verse
15 s
Delay
3 minute
REGENERATION
FILTRATION
CYCLE
CYCLE
CYCLE
a/ For Research Objectives.
FILTRATION
Delay
1 minute
Vibra-
tion
10 sec
20 sec
30 sec
Delay
3 minute
CYCLE
REGENERATION CYCLE
b/ For Final Cycle.
Figure 29. Diagram of regeneration cycles.
86
-------
GU = weight of dust in hopper before regeneration cycle,
in grams,
Gg = weight of dust from bag after regeneration, in grams,
Gj, = weight of dust removed from hopper during reverse air
regeneration, in grams,
G., = dust filling of bag, in grams, and
G« = total weight of dust introduced to the hopper during
filtration, in grams.
The efficiency of the hopper was calculated according to the relation:
EH = GH/GC x 100 (13)
where EH = hopper efficiency, in percent.
The efficiency of the tested bag, taking into consideration the dust
precipitated in the hopper, was calculated from the dust balance based on
the relation:
GR + GR + GN GC ~ ^GH + GR^
ER = ——p—- x 100 = ^ x 100 (14)
where: Eg = bag efficiency, in percent.
For some experiments, measurements of the fractional composition of the
dust in the cleaned gases were accomplished using a cascade impactor manufac-
tured by 2000, Inc. and provided by EPA. The measurements were made simul-
taneously with the measurements of the dust concentration in the outlet
gases by an aspiration method. The measurement system is shown in Figures
30 and 31, and includes a suction probe with a sampling nozzle (8 mm in
diameter), an Andersen cascade impactor, a rotameter, gas meter, vacuum
pump, and cutoff and control valves.
The dusty air was drawn isokinetically from a point 88 mm from the duct
wall, i.e., at the point where the gas velocity reaches the mean value in
the duct cross section. The velocity distribution in the duct at q = 60
32 32
m /m hr and q = 80 m /m hr is shown in Figure 32. To guarantee isokinetic
9
suction, the suction velocity was 20 percent higher than the gas velocity in
87
-------
1. Suction probe
2. Andersen Cascade Impactor
3. Rotamoter
4. Gas-meter
3. Vacuum pump
6, Thermometer
7, 8. Valves
Figure 30. Diagram of cascade impactor measurement system.
88
-------
Figure 31. Photograph of cascade impactor
measurement system.
89
-------
W
m|s
3 •
2
1
^
• — x-
I
I
I
I
I
I
-^-^
a-
20 40 60 fiO 100 120 d[mm]
at q » 60 or/nThr.
20 40 60 80 100 SO d[mm]
at q « 80 m*/m hr.
o
Figure 32. Velocity distribution in duct.
90
-------
the duct (the coefficient was established experimentally). Total sampling
time equalled the time of five basic measurement cycles. The dust collected
on the individual impactor stages was weighed with an accuracy of 0.00005 g.
All further operations concerning the true dust particle diameter were
conducted according to instructions received with the impactor.
The emission behind the measurement chamber was calculated from the
following relation:
m. 60
EM = \ (15)
where: EM = emission, in grams/hr,
m. = weight of dust on i-th impactor stage, in grams, and
t = suction time, in minutes.
Dust concentration in the cleaned gases was calculated according to the
relation:
CQ = EM/Q (16)
o
where: c = outlet concentration, in g/m ,
EM = emission, in g/hr, and
o
Q = total gas flow through impactor, in m /hr.
Fractional efficiency was calculated according to the equation:
m (1 - ET) m
EFR ' mw * 10° <17>
where: EFR = fractional efficiency, in percent,
ET = total efficiency of measurement chamber, in percent,
m = weight percent of a specific dust fraction introduced
to measurement chamber, in percent, and
m = weight percent of same dust fraction leaving the
measurement chamber, in percent.
RESULTS AND DISCUSSION
Basic Test
The initial large scale testing was conducted on separated talc.
Because of the special physical properties of this dust (see Table 2) several
91
-------
technical difficulties were encountered in achieving the test conditions
assumed in the detailed testing program. The most difficult were keeping the
inlet dust concentration of the air going into the test chamber at a stable
level of 10 g/m3 ± 10 percent, and preventing dust precipitation in the
lines.
For keeping the initial dust concentration in air at the required
level, within the established tolerance, it was necessary to improve the
dust feeder installed on the large scale test stand. Aeration of the dust
was done in the dust feeder chamber before the screw conveyor. This opera-
tion gave good results, increasing the uniformity of the dust feed to the
required level. This improved dust feeder was used during the entire program.
The next problem, prevention of dust precipitation, was solved by using
suitable vibrators and by changing the diameters of the pipelines.
These problems were eventually overcome, but some fabric tests with
separated talc reflect the effects of these early problems in the form of:
Exceeding the allowed tolerance in dust concentration (in tests at
3 2
q = 60 m /m hr) for fabrics:
853 (12.03 g/m3)
190R (11.87 g/m3)
852 (11.60 g/m3),
Overrunning the assumed dust loading of filtration area (L )
during the introductory filtration cycles, i.e., during the filling
of the fabric structure.
It is worthwhile to notice that the established levels of dust loading of
filtration area (LQ) for the measurement cycles and tests of all other kinds
of dusts were kept correctly. Figures 33 and 34 show exemplary pressure
differences in filtration time for fabric C866B using separated talc and
nonseparated coal dust.
The results of large scale testing calculated according to dependence
(11) are shown in Table 23. Table 23 also contains mean values of filtra-
tion efficiency and outlet concentrations obtained during five measurement
cycles conducted after reaching the state-of-balance with reverse air flow
regeneration. The detailed reports of individual experiments are in the
archives of the Dust Filtration Division of IPWMB, Opole. The results were
92
-------
ID
OJ
O
CM
fx,
^
°
80 mj/tf
400 g/m2
10 g/m3
Dust: sep. talc
100
200 300 400 500 500
FILTRATION TIME in minutes
700
Figure 33. Time variation of filtration resistance for fabric
C866B (dust: separated talc).
-------
10
o
f
M
a » 00
- 400 g/B2
2DD 300 400 500 600
FILTRATION TIME in mlnutea
TOO
Figure 34. Time variation of filtration resistance for fabric
C866B (dust: unseparated coal).
-------
TABLE 23. LARGE-SCALE EFFICIENCY (in percent) OF TESTED
FILTRATION FABRICS (c.=lQ g/m3, LQ=400 g/m2)
Type
of filtration
fabric
Cotton Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron® polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex® aromatic nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
A/C
(in
m3/m2hr)
Testing
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Efficiency
(in
percent)
with cement
99.945
99.974
99.966
99.912
99.997
99.971
99.999
99.994
99.978
99.989
99.985
99.979
99.991
99.981
99.999
99.979
99.992
99.974
99.963
99.965
99.991
99.986
Outlet
concentra-
tion (in
g/m3)
0.0006
0.0028
0.0032
0.0085
0.0003
0.0029
0.0001
0.0006
0.0021
0.0011
0.0015
0.0020
0.0009
0.0018
0.0001
0.0021
0.0007
0.0026
0.0041
0.0036
0.0010
0.0014
(continued)
95
-------
TABLE 23. (continued)
Type A/C Efficiency
of filtration (in (in
fabric m3/m2hr) percent)
Nylon polyamide
Style No. 802B
Glass Style No. Q53-875
Glass Style No. Q53-870
Glass Style No. Q53-878
Cotton Style No. 960
(R)
Dacron polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron® polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex® aromatic nylon
Style No. 852
Style No. 853
60
80
60
80
60
80
60
80
Testing with coal
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
99.987
99.979
99.991
99.921
99.986
99.565
99. 968
99.913
99.917
99.984
99.782
99.805
99.955
99.623
99.936
99.912
99.986
99.994
99.950
99.972
99.957
99.976
99.989
99.974
99.718
99.979
outlet
concentra-
tion (in
g/m3)
0.0013
0.0021
0.0010
0.0074
0. 0014
0.0444
0.0032
0.0082
0.0090
0.0016
0.0226
0.0181
0.0044
0.0037
0.0017
0.0100
0.0015
0.0006
0.0053
0.0027
0. 0044
0.0024
0.0010
0.0024
0.0287
0.0019
(continued)
96
-------
TABLE 23. (continued)
Type A/C Efficiency
of filtration (in in •
fabric m3/m2hr) percent)
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass Style No. Q53-875
Glass Style No. Q53-870
Glass Style No. Q53-878
Cotton Style No. 960
Dacron® polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron® polyester
Style No. 865B
Style No. C890B
Style No. C892B
60
80
60
80
60
80
60
80
60
80
60
80
Testing with talc
60
80
60
80
60
80
60
80
60
80
60
80
60
80
99.989
99.978
99.959
99.989
99.815
99.986
99.896
99.895
99.817
99.783
99.678
99.501
99.985
99.825
99.975
99.685
99.989
99.958
99.959
99.854
99.966
99.947
99.964
99.966
99.911
99.307
outlet
concentra-
tion (in
g/m3)
0.0012
0.0021
0.0043
0.0010
0.0174
0.0015
0.0128
0.0099
0.0193
0.0223
0.0323
0.0495
0.0016
0.0148
0.0026
0.0330
0.0012
0.0047
0.0038
0.0131
0.0033
0.0050
0.0034
0.0032
0.0079
0.0658
(continued)
97
-------
TABLE 23. (continued)
Type A/C
of filtration (in
fabric m3/m2hr)
Nomex® aromatic nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass Style No. Q53-875
Glass Style No. Q53-870
Glass Style No. Q53-878
Cotton Style No. 960
(R)
Dacron polyester
Style No. 862B
Style No. C866B
Style No. C868B
(R)
Dacron^ polyester
Style No. 865B
Style No. C890B
Style No. C892B
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Testing with
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Efficiency
in
percent)
99.963
99.864
99.983
99.928
99.992
99.944
99.996
99.995
99.996
99.842
99.951
99.952
99.597
99.690
99.889
98.876
fly ash
99.976
99.929
99.864
99.863
99.920
99.951
99.825
99.965
99.798
99.534
99.878
99.641
99.981
99.495
outlet
concentra-
tion (in
g/m3)
0.0043
0.0126
0.0021
0.0069
0.0010
0.0051
0.0005
0.0004
0.0004
0.0155
0.0048
0.0046
0.0406
0.0304
0.0108
0.1123
0.0025
0.0072
0.0142
0.0141
0.0084
0.0049
0.0169
0.0034
0.0198
0.0462
0.0113
0.0365
0.0018
0.0475
98
(continued)
-------
TABLE 23. (continued)
Type
of filtration
fabric
Nomex® aromatic nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex® aromatic nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass Style No. Q53-870
Glass Style No. Q53-870
Style No. Q53-878
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Efficiency
(in
percent)
99.919
99.896
—
—
99.973
99.958
99.992
99.951
99.957
99.930
99.974
99.958
99.929
99.827
99.975
99.951
outlet
concentra-
tion (in
g/m3)
0.0079
0.0100
--
--
0.0027
0.0043
0.0008
0.0049
0.0041
0.0066
0.0025
0.0040
0.0074
0.0171
0.0025
0.0049
99
-------
systematized for the purpose of carrying out the comparative analysis (similar
to laboratory scale) according to the recorded values of final (outlet) dust
concentration. The same ranges of dust concentration were established for
fabric classification in the laboratory scale, as shown shown in Table 24.
Compared with the laboratory scale results, the filtration efficiency of
fabrics examined in large scale was higher, so a larger number of the fabrics
fall in classes of lower outlet dust concentration. This confirms the
nonequivalence of the effects of Dust Filtration Types I and III. On struc-
tures fully filled with dust, the filtration process differs between large
scale and laboratory scale.
Results given in Tables 23 and 24 indicate that all fabrics (except
C892B and Q53-878 tested with talc at a = 80 m3/m2hr) have satisfactory
" 3
dust collection efficiency, giving final dust concentrations below 50 mg/m .
Concerning glass fiber fabric Q53-878, it can be said that the decrease of
efficiency resulted because of operation at an unsuitable A/C ratio. Concern-
ing polyester fabric C892B, lower values of efficiency, as compared to other
fabrics, probably result from structural properties. Taking into considera-
tion the kind of dust, the best filtration effects were obtained for cement
dust and the worst for fly ash.
Natural fiber fabrics, represented by cotton fabric 960, showed good
filtration efficiency during testing with cement and coal dust. The effi-
ciency of this fabric decreased during testing with talc and fly ash. A
decrease in dust filtration efficiency, with increase in A/C ratio, was •
observed. It is possible that it is connected to electrostatic effects.
The group of polyester fabrics, represented by staple fiber fabrics
862B, C866B, and C868B and continuous filament fabrics 865B, C890B, and
C892B, showed no influence of the kind of fiber on filtration effects. The
fabrics of this group showed good dust collection efficiency for cement and
coal dusts, but showed much worse collection efficiencies for talc and fly
ash. Even worse efficiencies were observed for q higher than 60 m3/m2hr
for talc and for all ranges of A/C for fly ash.
Similar efficiencies were observed for Nomex fabrics, except for con-
tinuous filament fabric 850. Among all tested fabrics, this fabric gave the
best dust collection efficiencies (also the highest fly ash collection
efficiencies).
100
-------
TABLE 24. CLASSIFICATION OF FABRICS ACCORDING TO OUTLET CONCENTRATION
Kind
of
dust
Cement
Coal
A/C
(in below
m3/m2hr) 0.0025
60 960
C866B
C868B
865B
C890B
C892B
852
853
850B
802B
Q53-875
Q53-870
80 C868B
865B
C890B
C892B
852
850B
802B
60 C868B
865B
852
190R
Outlet concentration in g/m3
0.0025- 0.0050- 0.01- 0.05- 0.1-
0.0050 0.01 0.05 .1 0.5
862B
190R
Q53-878
960 862B Q53-870
C866B Q53-875
853 Q53-878
190R
C866B 960 862B
C892B C890B 853
850B 802B
Q53-875
Q53-870
Q53-878
(continued)
-------
TABLE 24. (continued)
o
ISS
Kind A/C
of (in
dust m3/m2hr)
80
Talc 60
80
Fly ash 60
below
0.0025
960
865B
C892B
852
853
190R
850B
802B
960
C866B
853
190R
850B
802B
850B
C892B
850B
Outlet
0.0025-
0.0050
C866B
C890B
862B
C868B
865B
C890B
852
Q53-875
C866B
865B
C890B
Q53-875
960
190R
802B
Q53-875
Q53-878
concentration
0.0050-
0.01
C868B
Q53-875
C892B
853
190R
C866B
852
Q53-870
in g/m3
0.01-
0.05
862B
Q53-870
Q53-878
Q53-870
Q53-878
960
862B
C868B
852
802B
Q53-878
862B
C868B
865B
C890B
0.05- O.I-
.I 0.5
C892B Q53-878
(continued)
-------
TABLE 24. (continued)
Outlet concentration in
Kind A/C
of (in below 0.0025-
dust m3/m2hr) 0.0025 0.0050
80 C866B
C868B
190R
850B
Q53-875
Q53-878
0.0050-
0.01
960
852
802B
g/m3
0.01-
0.05
862B
865B
C890B
C892B
Q53-870
0.05- O.I-
.I 0.5
o
co
-------
Polyamide fabric 802B (staple fiber, similar to cotton fabric 960)
showed interesting properties, especially during testing with coal dust.
Glass fabrics were represented by three types of fabrics of different
construction. They showed better efficiencies in large scale than in'labora-
tory scale. However, among all fabrics tested, the efficiencies of glass
fabrics were the lowest. It is interesting, however, that in spite of the
quite rigid testing conditions, good filtration properties for fly ash were
observed. The influence of A/C on the dust collection efficiency was observed
in individual tests.
The Influence of Hopper Efficiency on Conducted Experiments
To determine the influence of the separating hopper on the experiments,
the dust balances for each of five measurement cycles were:
1. Weight of dust precipitated in the hopper during the filtra-
tion cycle (after shutting the hopper damper),
2. Weight of dust removed from the fabric structure during
regeneration, which is a value equivalent to the dust cake,
3. Weight of dust added to the bag by the reverse air cleaning,
4. Weight of residual dust in the fabric structure after the
regeneration cycle, which equals the final filling of fabric,
5. Weight of dust introduced to the 1-bag compartment by the feeder.
Based on the above amounts of dust and according to equations (12), (13),
and (14), the total 1-bag compartment efficiency, hopper efficiency, and bag
efficiency were calculated. The results are shown in Table 25.
During the testing, samples were taken from the following points of the
system:
From the hopper during the filtration process (before regenera-
tion),
From a bag, i.e., the dust covering the bag, as dust cake,
and
From the dust feeder.
The fractional compositions for these samples were determined. Based on
fractional composition, HMD (d5Q) was estimated. The results are presented
in Table 26.
104
-------
TABLE 25. EFFICIENCIES ET2, and Eg CALCULATED BY
DUST BALANCE
Type
of filtra-
tion fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
960
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Total
efficiency
(in percent)
Testing with
99.995
99.974
99.966
99.912
99.997
99.971
99.999
99.994
99.978
99.989
99.985
99.980
99.991
99.981
99.999
99.979
99.993
99.974
99.963
99.965
99.988
99.986
99.987
99.979
99.991
99.921
99.986
99.567
99.968
99.913
Testing with
99.917
99.984
Hopper
efficiency
(in percent)
cement
81.601
75.059
80.137
70.068
82.542
71.138
82.732
66.769
79.735
72.613
83.745
75.445
84. 112
78.361
76.287
63.332
81.972
69.092
76.088
74.978
83.814
73.759
80.180
70.743
83.590
74.059
86.818
75.283
83.051
75.145
coal
75.974
68.586
Bag
efficiency
(in percent)
99.972
99.893
99.825
99.704
99.983
99.898
99.993
99.981
99.893
99.958
99.910
99.917
99.942
99.912
99.994
99.943
99.957
99.915
99.841
99.855
99.941
99.946
99.932
99.930
99.944
99.694
99.893
98. 247
99.810
99.652
99.655
99.951
(continued)
105
-------
TABLE 25. (continued)
Type
of filtra-
tion fabric
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q52-875
Q53-870
Q53-878
960
862B
C866B
C868B
865B
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Total
efficiency
(in percent)
99.782
99.805
99.955
99.963
99.984
99.912
99.976
99.993
99.950
99.972
99.959
99.975
99.989
99.974
99.718
99.979
99.987
99.979
99.959
99.990
99.815
99. 985
99.875
99.895
99.817
99.783
99.679
99.503
Testing with
99.985
99.832
99.975
99.685
99.989
99.958
99.959
99.854
99.966
99.947
Hopper
efficiency
(in percent)
71.991
71.570
74.944
70.957
71.856
71.138
77.375
70.659
76.923
72.738
73.789
71.927
72.414
69.146
71.435
72.527
72.983
68.936
75.980
72.064
76.252
70.039
72.804
73.752
74. 513
72.360
73.987
72.026
talc
68.319
60.175
70.013
57.781
67.128
58.870
66.114
57.604
61.034
56.761
Bag
efficiency
(in percent)
99.223
99.314
99.822
99.871
99.943
99.694
99.937
99.978
99.781
99.898
99.843
99.913
99.962
99.917
99.011
99.924
99.953
99.931
99.828
99.964
99.221
99.952
99.541
99.600
99.281
99.215
98. 767
98.223
99.953
99.578
99.917
99.255
99.966
99.898
99.881
99.656
99.913
99.877
(continued)
106
-------
TABLE 25. (continued)
Type
of filtra-
tion fabric
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
960
862B
C866B
C868B
865B
C890B
C892B
852
853
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Total
efficiency
(in percent)
99.964
99.966
99.911
99.311
99.963
99.863
99.983
99.928
99.991
99.944
99.996
99.995
99.996
99.842
99.951
99.953
99.584
99.681
99.889
98.884
Testing with
99.976
99.932
99.864
99.863
99.914
99.951
99.823
99.965
99.798
99.536
99.878
99.643
99.981
99.498
99.921
99.896
-
-
Hopper
efficiency
(in percent)
63.848
59.439
66.968
58.551
67.044
58.556
62.140
55.875
63.700
54.562
74.268
62.613
60.583
54.604
66.221
58.712
65.315
60.478
62.708
57.578
fly ash
69.364
46.277
49.351
41.622
55.190
42.501
53.080
48.037
39.116
41.447
44.296
53.184
59.693
52.894
69.229
46.785
-
—
Bag
efficiency
(in percent)
99.901
99.917
99.730
98.340
99.887
99.664
99.955
99.837
99.977
99.877
99.984
99.987
99.991
99.651
99.854
99.886
98.800
99.337
99.702
97.367
99.919
99.863
99.732
99.764
99.808
99.915
99.619
99.932
99.667
99.208
99.780
99.237
99.954
98.933
99.742
99.804
-
-
(continued
107
-------
TABLE 25. (continued)
Type
of filtra-
tion fabric
190R
850B
802B
Q53-875
Q53-870
Q53-878
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
Total
efficiency
(in percent)
99.973
99.957
99.992
99.951
99.957
99.934
99.974
99.958
99.942
99.827
99.974
99.951
Hopper
efficiency
(in percent)
59.064
65.823
53.884
52.263
56.651
51.357
68.201
50.772
63.514
53.985
55.678
46.018
Bag
efficiency
(in percent)
99.931
99.868
99.393
99.897
99.899
99.860
99.918
99.914
99.806
99.612
99.940
99.909
It appeared that the hopper efficiency is quite high and is as follows:
Cement dust
Coal dust
Talc
Fly ash
63.3 - 86.8%
68.5 - 77.4%
54.5 - 74.2%
41.4 - 69.4%
Taking A/C ratio into consideration (different velocities in the hopper),
hopper efficiencies were:
Cement dust: at q = 60 m3/m2hr, EH = 76 - 86.8%
q = 80 m3/m2hr, Eu = 63.3 - 78.3%
Unseparated coal dust:
Talc:
Fly ash:
at q = 60 m3/m2hr
q = 80 m3/m2hr
at q = 60 m3/m2hr
qn = 80 m3/m2hr, Eu = 54.5 - 62.6%
EH = 71.4 - 77.4%
EH = 68.5 - 73.7%
EH = 60.5 - 74.2%
-LI
at qg = 60 m3/m2hr, EH = 39.1 - 69.4%
qn = 80 m3/m2hr, Eu = 41.4 - 53.9%
y "
108
-------
It can be seen then that hopper efficiency depends on the A/C ratio, the
dust density, and the aerodynamic coefficient of dust grain shape. This is
in accordance with the theoretical base of the mechanical dust collector's
operation.
The fractionating action of the hopper is clearly seen by comparing the
mean grain diameter (MMD) of the feed dust probed from the bag and the
hopper. In spite of the use of highly pulverized separated dusts, charac-
terized by MMD in the range of 5.2 - 6.8 |jm (coal dust is not taken into
consideration), the dusts were further separated because of the fractionating
properties of the hopper (its construction and geometrical proportions).
The pulverized dust from the bag (see Table 26) is characterized by an MMD =
4.0 - 5.5 urn with the fraction above 20 urn, not exceeding 1% (the assumption
was 10 percent).
So we come to the conclusion that the dust collection efficiencies of
the tested fabrics were actually determined using dusts of higher pulveriza-
tion than would be assumed from the fractional composition of the feed dust.
Comparing the dust collection efficiencies presented in Table 25 (calcu-
lated from dust balance) with and without the hopper efficiency, it appears
that the differences are considerable. Lower efficiencies were obtained for
the bag itself than for the entire chamber, including the hopper efficiency
(ETp). Two efficiencies were calculated; one based on measurements (Ey-,)
and the other from dust balance (Eyo)- The above total efficiencies of the
chamber are very well correlated, which confirms the accuracy of the testings
Figure 35 shows the comparison of measurement and dust balance efficiencies
for fabric C890B tested with cement dust. Because of the high hopper effi-
ciency, the filtration cycles were lengthened as necessary, in order to
2
maintain a constant L = 400 g/m .
The true concentration of dust at the bag inlet can be calculated from
the equation:
SB = ci U-EH'
3
where: c.D = dust concentration at the bag inlet, in g/m ,
1 D
c. = initial concentration at the compartment inlet, in
g/m , and
EM = hopper efficiency,
n
109
-------
TABLE 26. HMD FOR FEED DUST, BAG DUST, AND HOPPER DUST
Kind of dust
MMD of cement
dust (in (jm)
Type of
filtration
fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
from
fee-
der
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
5.2
from
bag
4.2
4.5
3.8
-
5.0
5.1
3.9
4.5
4.1
4.5
4.2
4.7
4.3
4.4
3.9
4.6
4.1
4.4
4.6
4.2
4.4
4.5
4.2
4.2
4.0
4.6
4.3
-
4.0
4.6
from
hop-
per
5.9
7.6
5.8
-
6.2
5.3
6.0
5.0
5.6
5.6
5.3
6.2
-
5.8
6.3
5.6
5.5
6.2
5.6
7.8
5.5
7.0
6.5
6.0
6.4
6.4
5.9
-
5.8
6.1
MMD of coal
dust (in urn)
from
fee-
der
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
from
bag
7.0
7.5
7.3
7.4
6.8
7.5
7.8
7.9
6.5
-
6.6
7.0
7.1
9.0
7.0
7.8
8.0
7.5
6.6
7.3
6.3
8.5
7.2
8.0
7.5
-
7.2
7.2
8.8
7.0
from
hop-
per
50
51
53
55
46
51
53
58
48
-
55
-
55
53
50
58
53
53
53
56
47
53
46
52
56
-
50
56
54
55
MMD of talc
dust (in urn)
from
fee-
der
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.2
6.8
6.8
6.8
6.8
6.2
6.8
6.2
from
bag
4.4
5.5
4.3
4.5
4.3
4.4
4.7
4.5
-
-
4.2
4.6
4.6
4.8
4.3
4.6
4.7
4.8
5.0
4.8
4.7
4.7
4.5
5.0
-
-
4.6
4.4
4.5
4.6
from
hop-
per
8.2
7.3
8.0
8.5
8.0
8.0
8.7
7.8
-
-
8.2
8.6
8.0
8.9
8.2
9.5
9.2
10.5
8.9
9.5
8.3
7.9
8.2
8.3
-
-
8.2
8.3
7.3
9.6
MMD of fly ash
dust (in urn)
from
fee-
der
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
from
bag
4.8
5.0
4.5
4.4
4.5
5.0
4.4
4.8
4.2
4.9
5.7
5.0
5.1
5.1
4.4
5.5
-
-
5.0
4.4
5.2
4.7
5.5
5.0
4.5
4.3
4.3
4.5
4.5
4.5
from
hop-
per
6.0
6.7
6.4
5.7
5.3
7.3
5.8
6.5
6.2
8.0
6.0
8.5
6.2
6.8
5.8
6.6
-
-
6.0
5.3
6.8
6.0
6.7
7.8
5.8
6.2
6.0
5.8
5.3
6.0
-------
DUST BALANCE EFFICIENCY, percent
Figure 35. Correlation between measurement efficiency
and dust balance efficiency for experiments
for fabric C890B dusted with cement at
a = 60 m3/m2 hr.
Ill
-------
Fractional Efficiency of Fabrics
The measurements of fabric fractional efficiency were made for the
following dusts and values of A/C:
3 2
Cement dust; qn = 80 m /m hr,
9 32
Fly ash; q = 60 and 80 m /m hr.
TABLE 27. FRACTIONAL EFFICIENCY OF FABRICS TESTED WITH CEMENT
(at q = 80 m3/m2hr, LQ = 400 g/m2, and c.. = 10 g/m3 )
Fractional efficiency (in percent) in the
ranges:
Type of
filtration fabrics
Cotton Style No. 960
Dacron polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex aromat. nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex aromat. nylon
Style No. 850B
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
0-2 pm
99.828
99.411
99.871
99.950
*
99.852
99.837
*
*
99.740
99.888
99.803
99.374
96.033t
97.111*
*
2-3 urn
99.937
99.863
99.957
99.989
99.959
99.970
*
*
99.923
99.977
100.000
99.876
99.571
99.126
3-5 urn
99.986
99.934
99.995
99.998
*
99.997
100.000
.*
*
100.000
99.995
99.993
99.968
99.794
99.677
*
5-10 urn
100.000
99.987
99.969
99.999
*
99.994
99.996
*
99.989
99.998
99.995
99.991
100.000
99.975
above
10 urn
100.000
100.000
100.000
100.000
*
100.000
100.000
*
100.00
100.000
100.000
100.000
100.000
100.000
*
*No data—amount of dust in the impactor too small to be measured
tFor not fully filled structure.
tAfter reaching state of equilibrium.
112
-------
The calculated values of efficiencies are compiled in Tables 27 and 28.
Figures 36 through 40 show fractional efficiency as a function of dust
grain diameter.
During the analysis of the measurements, it was observed that in many
cases the outlet dust concentrations estimated by the cascade impactor were
much lower than the concentrations estimated by the aspiration method (filtra-
tion sampling), even though the impactor measurement procedures were in
accordance with the instructions. This discrepancy is probably caused by
instantaneous duct velocity fluctuations, so that aspirated gas sample is
not isokinetic. The possibility of some measurement mistakes connected with
the application of the new measurement method, however, is not excluded.
The analysis of the fractional composition of the outlet dusts (in the
clean air behind the test chamber) showed that the standard deviation from
the mean grain diameter (MMD) is on the average about Q> = 2 urn, which
proves the fractionating influence of the dust-fabric system (see Table 29).
An increase in the mean dust grain diameter with increasing A/C ratio was
observed.
Plots of fractional efficiency as a function of grain diameter were
obtained during fabric testing with separated cement dust (see Figures 36
and 37). The plots conform to our predictions. Each fabric has a definite
grain diameter for which the efficiency reaches 100 percent.
The influence of the filtration structure on the formation of a definite
dust cake structure can be seen. Hence the dust fabric system is character-
ized by the grain size, above which the efficiency is 100 percent.
The curves shown in Figures 38 through 40 have behaviors different than
those presented in Figure 36 and 37. They represent the variations of
fractional efficiency as a function of grain diameter during testing with
separated talc.
It is interesting that in the range of fine fractions, there are some
grain sizes at which the efficiencies are higher than expected by us. The
characteristic decreases in efficiency were observed. They had been observed
before and during research concerning fractional efficiency problems. A
significant increase of dust collection efficiency was observed for fractions
above 2 urn.
113
-------
TABLE 28. FRACTIONAL EFFICIENCY OF FABRICS TESTED WITH FLY ASH (at q = 60 and
80 m3/m2hr, L = 400 g/m2, and c. = 10 g/m3) 9
Type of
filtration fabrics
Cotton Style No. 960
Dacron polyester
Style No. 862B
Style No. C866B
Style No. C868B
Dacron polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex aromat. nylon
Style No. 852
Style No. 853
Style No. 190R
Nomex aromat. nylon
Style No. 850B
Nylon polyamide
Style No. 802B
A/C
(in
m3/m2hr)
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
0-2 Mm
99.953
99.756
99.883
99.665
99.720
99.838
99.476
99.865
99.342
98.919
99.712
98.733
99.931
98.191
99. 745
99.791
-
100.000
99.798
*
99.856
99.830
99.699
Fractional
2-3 M""
99.556
99.670
98.623
98.866
100.000
99.808
100.000
100.000
100.000
97.224
100. 000
97.767
100.000
97.551
100.000
99.294
-
98.056
99.841
*
99.583
100.000
99.701
efficiency (in
ranges:
3~5 Mi"
99.961
99.539
99.428
99.691
99.715
99.917
99.477
99.890
99.200
98.996
99.402
99.546
99.927
99.293
99.678
99.756
-
97.981
100.000
*
99.915
99.893
99.948
percent)
5-10 M"i
100.000
100.000
99.972
99.972
100.000
99.981
99.962
99.984
99.993
99.773
99.978
99.953
99.998
99.887
99.985
99.962
-
100.000
100.000
*
99.995
100.000
99.992
in the
above
10 MI"
100.000
100.000
99.996
100.000
99.992
100.000
99.961
100.000
99.993
100.000
99.997
100.000
99.999
100.000
100.000
100.000
-
100.000
100.000
*
100.000
100.000
100.000
(continued)
-------
TABLE 28. (continued)
Type. of
filtration fabrics
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
A/C
(in
m3/m2hr)
60
80
60
80
60
80
Fractional
efficiency (in percent) in the
ranges:
0-2 urn
99.885
99.918
*
99.563
99.877
99.846
2-3 pm
100.000
99.793
*
98.986
100.000
99.720
3-5 |jm
99.914
99.913
*
99.682
99.944
99.912
5-10 IJITI
99.984
99.973
*
99.928
99.995
99.987
above
10 (jm
100.000
100.000
*
100.000
99.995
100. 000
*Absent data—amount of dust in the impactor too small to be measured.
-------
en
99,90
99,90
99,70
99,60
99,50'
M 99,40
99,30
99,20
99,10 -
99,00 -"
8626
C3668
10
10
C868B
C690B
' 5 '
0 D
csgae
ORAIN DIAMETER in
yuffl
960
0' ' '5 ' 10
Figure 36. Fractional efficiency of polyester and cotton fabrics
(cement dust at q = 80 m3/m2 hr, L = 400 g/m2, and
c1 = 10 g/m3). g °
-------
100,00i
-p
C!
I 99,50-
0>
04
99,00-
u
8 98,501
o
&4
I
98,00-
97,50 -
97,00^
GRAIN DIAIJIETER in urn
Figure 37. Fractional efficiency of Nomex, glass, and polyamide fabrics
(cement dust at q = 80 m3/m2 hr, L = 400 g/m2, and c. = 10 g/m3).
y w i
-------
00
100,00-
99,50-
£ 99,00-
o 96,50
97,50-
97,00
0 5 10
ORAIN DIAMETER, in
w
Figure 38. Fractional efficiency of polyester fabrics (fly ash at
|_Q = 400 g/m2 and c.. = 10 g/m3).
-------
100,001
-p
p
« 99,50
rH
r-*-*
•H
o
CJ
99,00-
96,50-
O
98,00J
C»AIN DIAMETER, in yum
Figure 39. Fractional efficiency of Nomex and glass fabrics (fly ash at
LQ = 400 g/m2 and c. = 10 g/m3).
-------
100,00
8
S,
3 8,70
u 98,50
M
99,30
«,2D
98.IQ
99,00
0 5 t 0 5
ORAXK DIAPETSR,
Figure 40. Fractional efficiency of cotton and polyamide fabrics
(fly ash at I_Q = 400 g/m2 and ^ = 10 g/m3).
120
-------
TABLE 29. HMD OF OUTLET DUST - CASCADE IMPACTOR MEASUREMENTS
Type of
filtration fabric
Cotton
Style No. 960
®
Dacron polyester
Style No. 862B
Style No. C866B
Style No. C868B
®
Dacron polyester
Style No. 865B
Style No. C890B
Style No. C892B
Nomex®
Style No. 852
Style No. 853
Style No. 190R
Nomex
Style No. 850B
Nylon polyamide
Style No. 802B
Glass
Style No. Q53-875
Glass
Style No. Q53-870
Style No. Q53-878
A/C in
m3/m2hr
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Cement
MMD (jm
-
0.95
-
1.40
-
2.30
-
1.20
-
-
-
1.15
-
0.88
-
1.80
-
—
-
1.15
-
1.10
-
0.86
-
1.20
-
1.10
0.70
-
0.70
Kind
a pm
-
2.57
-
1.94
-
3.65
-
1.79
-
-
-
2.40
-
2.32
-
3.83
-
-
-
2.09
-
2.20
-
2.10
-
1.97
-
1.83
2.92
-
6.36
of dust
Fly
MMD |jm
-
1.70
1.90
1.90
1.37
1.65
1.75
1.10
1.63
1.76
1.75
1.26
1.70
1.35
1.20
1.78
-
-
-
—
-
1.68
1.45
1.30
1.50
2.35
1.73
2.00
1.10
1.70
ash
a \im
-
1.89
1.81
1.81
2.11
2.36
2.69
2.20
1.89
2.32
1.90
2.17
1.75
2.25
2.45
1.78
-
—
-
—
-
1.77
1.71
1.94
2.03
2.47
2.31
2.15
3.33
2.13
121
-------
Filtration Resistance
In the introduction to Section IV, the filtration resistances were
discussed from two viewpoints:
1. The obtained final filtration resistance (APK) of a structure
2
covered with dust LQ = 400 g/m , and
2. The obtained effective drag ($E) and resistance coefficient (K2)
of a definite dust-fabric system.
In both cases, the respective values of the two viewpoints were discussed
for the same values of A/C; the regeneration system was the same during all
experiments. The final resistance, APK> was presented in Tables B-4 through
B-19. AP., was similar within a given raw material group, but did depend upon
i\
the type (continuous vs. staple) fiber.
For the most populous group, polyester fabrics, higher filtration
resistances were observed with the continuous filament fabrics. The same
observation was made for Nomex and glass fabrics.
Analyzing the variation of final resistance with respect to the kind of
test dust, it can be said that dusts of cement, coal, and talc show similar
hydraulic effects. Much lower final resistances were observed during all
tests with fly ash.
It is interesting that coal dust, which in the large scale testing was
an unseparated dust of MMD = 30 urn, showed a final resistance during all
tests similar to that recorded for separated cement dust and talc, even
though particle size composition of the unseparted coal dust differed signi-
ficantly from that of the separated dusts. This would prove that grain
shape has a greater influence on the filtration resistance of a dust-fabric
system than the degree of pulverization. The above observation was confirmed
by laboratory scale testings (Table 16). The highest observed filtration
resistances (measured by final pressure drop) were obtained for separated
coal dust in all laboratory tests. It is possible that this phenomenon is
connected with electrostatic effects. Coal dust has very special electro-
static properties.
From equations (4) and (5), the effective drag and resistance coeffi-
cients for the dust-fabric systems were determined for the mean values of
filtration resistance as a function of time over five measurement cycles.
The results of the calculations are presented in Table 30. Table 31 includes
122
-------
TABLE 30. S£ (in irroHgO/m/hr) AND SPECIFIC RESISTANCE
COEFFICIENT KZ (in mmHgO/m/hr/g/m2) IN LARGE SCALE TESTS
Effective drag SE
Type
of
fabric
Cotton
960
Dacron®
862B
C866B
L J
£ C868B
Dacron®
865B
C890B
C892B
Nomex®
852
853
190R
qg
3in2
m /m hr
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
Sep.
cement
0.48
16.77
11.70
13.12
12.40
10.58
15.55
15.84
16.46
18.84
20.32
26.92
13.93
30.59
11.03
11.71
12.92
12.36
7.75
5.65
Unsep.
coal
17.20
16.82
10.06
9.00
8.83
10.98
10.52
7.05
10.03
12.34
18.52
25.23
24.37
20.67
11.57
7.52
10.37
8.87
7.45
5.47
Sep.
talc
13.46
9.91
7.40
7.26
7.67
6.80
10.05
10.27
11.99
11.89
21.92
23.30
15.27
15.11
6.75
8.56
9.12
8.91
4.45
5.00
Sep.
fly
ash
17.95
13.27
10.58
9.21
9.90
11.14
10.51
9.83
14.29
17.19
16.01
21.49
18.92
20.05
16.19
11.16
—
—
5.44
4.23
Specific resistance
Sep.
cement
0.31
0.07
0.06
0.06
0.06
0.07
0.06
0.06
0.06
0.05
0.04
0.06
0.05
0.05
0.07
0.09
0.08
0.10
0.08
0.10
Unsep.
coal
0.06
0.08
0.07
0.05
0.06
0.03
0.07
0.06
0.05
0.06
0.05
0.07
0.08
0.05
0.07
0.05
0.08
0.06
0.08
0.05
coefficient K2
Sep.
talc
0.06
0.11
0.06
0.07
0.06
0.08
0.05
0.05
0.07
0.06
0.07
0.06
0.05
0.05
0.07
0.06
0.10
0.06
0.06
0.05
Sep.
fly
ash
0.04
0.07
0.04
0.04
0.04
0.05
0.04
0.04
0.04
0.05
0.03
0.03
0.04
0.04
-0.03
0.09
—
—
0.05
0.09
(continued)
-------
TABLE 30. (continued)
Effective drag SE
Type
of
fabric
Nomex®
850
Nylon
802B
Glass
K Q53-875
^
Glass
Q53-870
Q53-878
qg
31n2
nT/m hr
60
80
60
80
60
80
60
80
60
80
Sep.
cement
22.17
24.58
11.59
12.06
20.88
21.91
30.38
29.50
17.72
19.35
Unsep.
coal
21.16
22.47
8.24
7.79
23.81
21.75
33.35
28.92
17.68
16.55
Sep.
talc
17.87
19.43
12.45
9.82
22.08
16.66
21.66
31.52
16.61
16.13
Sep.
fly
ash
17.49
20.08
10.37
11.73
18.33
21.52
25.43
22.01
11.28
15.61
Specific resistance
Sep.
cement
0.04
0.05
0.06
0.07
0.05
0.06
0.06
0.05
0.06
0.05
Unsep.
coal
0.05
0.04
0.05
0.06
0.08
0.06
0.08
0.06
0.07
0.07
coefficient K2
Sep.
talc
0.06
0.08
0.07
0.05
0.08
0.07
0.06
0.09
0.07
0.07
Sep.
fly
ash
0.03
0.03
0.05
0.05
0.04
0.04
0.04
0.04
0.05
0.05
-------
TABLE 31. RATE OF INCREASE OF FILTRATION RESISTANCE
Kind of dust
Type
of
fabric
Cotton
960
Dacron®
862B
C866B
C868B
Dacron
865B
C890B
C892B
Nomex®
852
853
190R
Nomex®
850B
Nylon
802B
Glass
Q53-875
Glass
Q53-870
Q53-878
Sep.
V
60
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
58
12
11
10
11
07
09
16
14
20
07
12
08
08
10
cement
V
80
0.31
0.29
0.36
0.35
0.25
0.24
0.17
0.56
0.58
0.47
0.24
0.35
0.27
0.23
0.24
Unsep.
V
60
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
14
21
16
20
12
10
20
18
23
22
12
12
21
19
19
coal
V
80
0.45
0.27
0.13
0.29
0.30
0.32
0.25
0.29
0.30
0.28
0.22
0.35
0.29
0.30
0.37
Sep.
V
60
0.18
0.19
0.21
0.18
0.26
0.26
0.18
0.22
0.36
0.22
0.15
0.26
0.28
0.22
0.28
talc
V
80
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
77
54
57
39
46
41
35
47
49
44
51
41
53
63
55
Sep. fly ash
V V
60 80
0.11
0.20
0.19
0.20
0.24
0.19
0.14
--
--
0.22
0.15
0.24
0.12
0.15
0.22
0.65
0.43
0.53
0.38
0.50
0.28
0.30
0.89
--
0.57
0.29
0.44
0.35
0.31
0.51
the increase of pressure drop in time calculated according to equation (6).
As it can be seen from the compilated data, S£ as well as K,, depend upon the
raw material of the fabric, the kind of fiber (staple, continuous filament),
and the kind of dust.
125
-------
Continuous filament fabrics show a considerable increase of S£ with
increasing A/C. It probably results from the very good structural filling
of the spatial area with yarns of indefinite length. The spatial area of
staple fiber yarns is very porous, so S£ shows only very small variations as
a function of A/C ratio. A more apparent influence of A/C upon filtration
resistance is observed when analyzing the rate of increase of filtration
resistance (see Table 31).
In conclusion, it is worth pointing out that the calculated values, S£
and K2, have only statistical significance because they are the secondary
values of external process parameters measured during the run. They are not
directly functionally dependent on physical parameters characterizing the
process or structural parameters. Application of the values of S^ and Kg
has practical importance only in predicting a filtration resistance for
process conditions similar to the conditions of the experiment.
The values of SE and K_ obtained in the laboratory tests, although
similar, do not correlate with those of the large scale tests (especially
for polyester fabrics). The calculation of negative values of Sr for the
laboratory studies proves that the time variation of the filtration resist-
ance has a parabolic character and cannot be assumed to be linear.
During the large scale fabric testing the influence of the superficial
structure of the fabric on dust cake formation was observed. It made obtain-
ing an assumed final resistance in time difficult. Analysis of the resist-
ance variation in time led to the conclusion that the prolonged experimental
time required to build up a predetermined pressure drop was caused by the
"sliding effect" of dust cake. This effect was characteristic of the glass
and polyester continuous filament fabrics tested with separated cement dust.
The variation of filtration resistance in time is shown in Figures 41 through
46. [A similar influence of superficial structure on filtration resistances
was described by Donovan, Daniel, and Turner (ref. 13). J The "sliding
effect" of dust cake is characterized by decrease of K2 in time. It decreases
to the moment of obtaining the mean value characteristic for the specific
process.
The data just discussed lead mainly to one conclusion, i.e. it is
necessary to study and understand the structural parameters characteristic
of woven fabric structure and its dust cake. Only in this manner will it be
126
-------
ro
AP
mm HgO
o
CM
8
EH
20-
10-
IV
50 75 100
TIME, In minutes
Figure 41. Variation of filtration resistance in time for fabric
style no. 862B (cement dust at q = 60 m3/m2 hr).
-------
oo
AP
mmHgO
SO-
0
• •*
.••'
50
100 iso aw
TIME, in ainutaa
B|f
,••
250 tfnin]
Figure 42. Variation of filtration resistance in time for fabric
style no. C890B (cement dust at q = 60 m3/m2 hr).
-------
AP
mm \\£
o 40
CM
o
^ 30
•t
M
O
R
20-
10
fc.
50
100
150
200
250 r[min]
TIME, in minutes
Figure 43. Variation of filtration resistance in time for fabric
style no. C892B (cement dust at q = 60 m3/m2 hr).
-------
AP
mm HzO
o
CM
G
•H
O
M
EH
s
40-
30-
20-
10-
V
.•
••
50 fOO 150
TIME, in minutes
200
r jrun]
Figure 44. Variation of filtration resistance in time for fabric
style no. Q53-875 (cement dust at q = 60 m3/m2 hr).
-------
(A)
AP
mm HgO
o
CM
40 -
o 30
20-
10
..
• •
50
100 150 200
TIME, in minutes
25D
Figure 45. Variation of filtration resistance in time for fabric
style no. Q53-870 (cement dust at q = 60 m3/m2 hr).
-------
oo
o mm
CM
8
AP
Hi
40-
30 ^
20
1(H
50 100 150
TIME, In minutes
200
[min]
Figure 46. Variation of filtration resistance in time for fabric
style no. Q53-878 (cement dust at q = 60 m3/m2 hr).
-------
possible to control the filtration resistance, and thus the filtration
process in accordance with design goals. So, the concepts developed by
Stephan, Walsh, and Herrick for interpreting their results gives some
indication of the differences in hydraulic effects in a'dust-fabric system,
but does not explain the mechanisms of the phenomena.
CONCLUSIONS
The basic large scale tests identified the following types of
fabrics as having the best filtration properties for the various
test dusts:
Cement dust
Cotton fabric
Polyester fabrics
Nomex fabrics
Polyamide fabric
Coal dust
Cotton fabric
Polyester fabrics
Nomex fabrics
Talc
Polyester fabrics
No. 960
Nos. C866B
C868B
865B
C890B
C892B
Nos. 852
853
190R
850B
No. 802B
No. 960
Nos. C866B
865B
C890B
C892B
Nos. 852
190R
850B
Nos. C866B
865B
C890B
133
-------
Nomex fabrics Nos. 190R
850B
Glass fabric No. Q53-875
Fly ash
Cotton fabric No. 960
Polyester fabric No. C866B
Nomex fabrics Nos. 190R
850B
Polyamide fabric No. 802B
Glass fabric Nos. Q53-875
Q53-878
Because of the hopper fractionating properties, the dust collec-
tion efficiency of the tested fabrics was actually determined for
dusts of higher pulverization than the feed dust.
The average hopper efficiencies are in the range 40 - 86 percent.
Each dust-fabric system, depending on the kind of dust and the
type of fabric, has a specific fractional efficiency (the limit
grain size above which the collection efficiency is 100 percent).
A characteristic decrease of fractional efficiencies was observed
during testing of fabrics with fly ash.
The effective drag and specific dust-fabric resistance coefficient
was determined for all combinations of fabrics and dusts.
Calculated values of S£ and K2 have only statistical significance
because they are not explicit functions of the physical parameters
characterizing the process or the fabric structural parameters.
134
-------
SECTION VI
STUDY OF THE REGENERATION PROPERTIES OF FABRICS
INTRODUCTION
The filtration fabric assumes the following states during its use in a
fabric filter:
Clean fabric - the fabric before initial contact with the
dirty gas,
Fully filled fabric - the used, dirty fabric after regenera-
tion but before additional contact with the dirty gas medium.
Equilibrium is assumed to have been reached in that the
quantity of dust in/on the fabric is assumed to be constant
from regeneration cycle to regeneration cycle. Before equil-
ibrium is reached the fabric is simply filled with dust not
fully filled.
Covered with dust fabric - the fabric fully filled with dust
and with a dust cake. Dust cake's thickness depends on time
of contact with dirty gas.
These stages of filtration fabrics are determined by the resistivity (static
pressure drop) of the fabric (at a constant A/C):
AP = clean fabric resistance,
APNK = fully filled fabric resistance, and
APK = covered with dust fabric resistance.
Employing the principle of superposition, the following relation can be
assumed (at q = constant):
APK = APNK + APW (19)
where AP.. = dust cake resistance.
This dependence is not very precise (because the real thickness of the dust
cake formed on the filtration structure during the filtration process is
135
-------
unknown), but it is sufficient for technical purposes. Equation 19 is also
of practical value in adjusting the fabric regeneration process. The covered
with dust fabric resistance, the final resistance in a given filtration
cycle, depends on the clean fabric resistance, the physical-chemical pro-
perties of the dust, and the A/C ratio.
Figure 47 shows a theoretical and experimental plot of filtration and
regeneration processes in a bag filter, with labels identifying the charac-
teristic values. In a theoretical plot, at a constant A/C ratio and a
constant dust loading of filtration area, the filtration time of each fil-
tration cycle is constant, which causes the final resistance in each cycle
to reach the value AP,, = constant. However, in practice, where all values
i\
characterizing the gas and dust loads vary in time, and we can take into
consideration only their means, the behavior of the hydraulic pressure drop
is completely different (see Figure 48).
The duty cycle of a filtration fabric in the bag filter depends, to a
great extent, on how the regeneration system is regulated. When regulation
is based on constant filtration time (determined experimentally for the mean
parameters of the aerosol at the dust collector inlet):
tfl =tp'2 = ... =tF'n (20)
where tr- = filtration time of cycle i.
With this method of regulation, AP., can take on arbitrary values proportional
to variations of the aerosol state at the dust collector inlet (illustrated
by a discontinuous line in Figure 48). In the case of periodical regulation,
when the filtration time depends upon the state reached by the dust-fabric
system, as characterized by the assumed and established value APK, there is:
tF1 * tF2 * ... * tfn. (21)
In this case APK is constant (illustrated by a continuous line in Figure 48).
For a given concentration, the final resistance of the covered with dust
fabric should be reached at a constant level of AP.,.
K
136
-------
CO
O
8
CO
CO
w
TIME
Figure 47. Theoretical plot of filtration and regeneration process.
-------
to
00
TIME
Figure 48. Realistic behavior of filtration and regeneration process.
-------
Multiple repetition of the filtration-regeneration cycles leads to
increases in the filled-fabric resistance, measured after regeneration.
This increase tends towards a constant value, APNK, for the established methods
of regeneration as a result of a fabric structure with large specific surface
and thickness. It is easy to determine fabric susceptibility for regenera-
tion by measuring the final resistance of a fully filled fabric for a specific
regeneration system. To facilitate the comparison of filtration fabrics,
the following formula for susceptibility for regeneration was derived (for
constant q and q ):
AFV ' AP«
S
R APK - AP
where APNK = established final, fully filled fabric resistance for
a definite system of regeneration, in mmhLO,
AP = clean fabric resistance, in mmH^O, and
APK = established final covered with dust fabric resistance,
in
The values of fabric susceptibility for regeneration are between 0 and 100
percent. Because the intensity of regeneration as well as the susceptibil-
ity for regeneration are complicated functions of time, as shown in Figure
49, the use of equation (22) requires standardization of the regeneration
time.
RESULTS AND DISCUSSION
Estimation of the regeneration properties of the test group of fabrics
was based on the susceptibility for regeneration formula (equation 22) pre-
viously noted in this section. Appropriate values of pressure drop were
taken from data recorded during large scale testing as shown in Tables B-4
through B-19. The susceptibility for regeneration was calculated for four
stages of the regeneration cycle as follows:
After reverse flow regeneration, SRn,
After 10 seconds mechanical shaking (vibration),
• . After 20 seconds mechanical shaking (vibration),
After 30 seconds mechanical shaking (vibration), SRM3-
139
-------
At stable value of AP., and for a mechanical
stable regeneration system.
TIME
Figure 49. Theoretical plot of susceptibility for regeneration
vs. time.
140
-------
The test results for various test dusts and A/C's are shown in Tables
32 through 39.
Actual variations of susceptibility for regeneration as a function of
time for fabrics C866B, C868B, and Q53-875, tested with cement dust at q =
32 -9
60 m/m hr, are presented in Figure 50.
The susceptibility for regeneration, which is to a great degree a
property of the filtration fabric surface, depends on adhesion effects at
the fabric/dust cake interface. So it depends on fiber properties (and/or
the fiber coatings), as well as dust properties. The interaction of dust
TABLE 32. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH CEMENT AT q = 60 m3/m2hr
y
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
S *
51.14
78.51
73.42
61.14
70.50
89.60
91.00
69.11
58.10
72.07
79.83
62.29
88.74
74.54
83.41
*»t
47.03
82.25
68.92
62.88
78.93
92.20
92.60
68.06
49.72
72.07
92.11
64.00
89.01
61.93
85.25
V
47.03
85.98
72.97
65.50
79.69
91.04
92.60
68.06
50.84
72.07
93.86
64.00
90.38
68.24
87.40
SRM3§
45.21
89.25
75.68
65.94
80.84
91.33
91.96
70.16
51.40
72.07
93.86
64.00
91.21
67.54
87.40
*s
ts
+s
§s
RR
RM1
RM2
RM3
reverse air flow regeneration.
10 seconds mechanical shaking.
20 seconds mechanical shaking.
30 seconds mechanical shaking.
141
-------
TABLE 33. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH CEMENT AT q = 80 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
SRR
59.91
85.93
76.13
49.21
84.75
86.79
86.04
72.55
62.40
82.80
76.98
75.00
86.08
71.38
88.53
SRM1
50.86
89.52
73.87
60.20
67.76
80.75
76.08
67.84
57.85
81.53
73.48
66.67
88.43
63.88
85.28
SRM2
48.28
91.62
76.45
61.18
77.34
87.93
85.23
68.63
59.09
78.98
82.32
68.48
95.30
75.47
91.13
SRM3
48.28
93.41
79.03
61.84
80.83
88.74
85.23
72.16
59.09
78.98
82.51
68.48
95.66
73.42
91.13
TABLE 34. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH COAL AT q = 60 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
RR
58.20
83.90
79.60
78.40
82.20
83.30
86.10
75.20
70.90
80.60
77.30
77.40
89.10
76.60
88.90
RM1
55.40
83.90
78.70
78.00
75.90
83.30
85.50
73.20
68.40
77.50
74.00
75.30
84.30
69.20
85.80
s
RM2
55.40
84.60
80.10
77.30
77.10
79.50
84.70
72.40
69.60
77.50
71.70
74.70
84.90
66.70
85.10
RM3
55.40
85.00
81.50
77.30
78.30
78.60
84.70
73.20
69.60
79.40
70.00
75.30
85.50
64.70
85.10
142
-------
TABLE 35. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH COAL AT q =80 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
$
RR
62.80
84.50
83.10
80.70
86.60
85.90
83.10
84.20
76.30
84.10
77.40
75.70
88.40
84.80
92/20
s
RM1
57.70
82.00
81.40
78.90
86.90
76.70
77.50
84.60
69.80
79.30
60.90
74.50
80.40
79.50
92.40
s
RM2
56.50
82.90
81.60
80.30
85.90
75.40
73.90
82.70
68.30
80.90
64.60
74.50
80.40
79.50
91.80
s
RMS
55.00
83.80
82.40
81.00
85.90
74.40
76.90
83.80
67.80
81.90
67.30
74.50
82.00
80.40
91.80
TABLE 36. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH TALC AT q = 60 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
s
RR
67.30
81.10
77.10
68.90
79.20
70.20
75.90
86.30
43.40
83.10
64.30
70.30
77.60
67.10
73.90
s
RM1
63.60
81.10
78.00
70.90
79.50
69.10
70.90
90.60
40.40
79.50
65.30
63.60
72.70
63.00
70.70
s
61.40
82.70
74.80
69.40
79.50
71.30
73.90
89.80
38.20
78.70
65.10
63.20
79.10
63.00
70.70
s
61.40
83.70
74.80
69.90
80.10
72.40
74.70
90.00
38.20
78.70
64.50
63.20
80.90
62.50
71.50
143
-------
TABLE 37. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH TALC AT q = 80 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
SRR
63.20
85.90
78.10
68.70
83.50
80.10
84.60
74.60
57.50
80.50
73.10
68.90
86.10
75.00
77.70
SRM1
61.30
83.80
73.40
62.20
77.80
71.70
85.20
54.90
56.30
78.50
69.50
64.80
80.70
71.30
74.20
SRM2
60.70
84.40
75.20
62.60
78.00
71.20
90.30
59.20
57.30
77.90
68.60
63.90
79.20
69.60
73.80
SRM3
60.70
85.00
77.10
63.70
78.60
71.90
91.70
60.60
57.30
78.50
68.90
64.80
80.20
69.90
74.20
TABLE 38. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH FLY ASH AT q = 60 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
SRR
43.48
68.35
46.81
58.06
69.80
73.48
69.83
66.23
—
56.58
65.57
62.34
59.76
55.59
64.00
SRM1
21.74
75.54
32.62
57.42
66.83
62.72
72.20
72.85
—
56.58
58.61
29.22
59.36
60.61
64.00
SRM2
23.37
77.70
38.30
58.06
72.77
70.25
58.98
73.51
59.21
63.11
37.66
57.54
56.17
65.33
SRM3
29.35
79.86
40.43
60.00
75.25
75.27
91.52
76.82
56.58
63.11
42.21
52.99
51.95
64.00
144
-------
TABLE 39. SUSCEPTIBILITY FOR REGENERATION (in percent) OF
FABRICS TESTED WITH FLY ASH AT q =80 m3/m2hr
Susceptibility for regeneration
Kind
of
fabric
Style 960
Style 862B
Style C866B
Style C868B
Style 865B
Style C890B
Style C892B
Style 852
Style 853
Style 190R
Style 850B
Style 802B
Style Q53-875
Style Q53-870
Style Q53-878
s
R
56.62
66.89
60.19
64.10
63.91
79.57
77.94
58.25
--
70.83
62.09
51.98
79.82
74.52
73.21
s
RM1
47.44
78.15
43.06
61.54
62.69
77.40
74.82
6.31
--
15.62
65.35
47.46
73.54
85.75
66.07
s
RM2
45.30
81.46
46.76
61.54
69.42
79.09
78.90
8.74
--
15.62
64.19
48.02
76.91
86.45
68.57
RM3
45.30
84.11
49.54
62.56
71.87
79.09
77.70
11.17
--
17.71
63.95
48.02
77.80
88.08
68.57
particles and fibers is conditioned by different kinds of mechanisms. The
main mechanisms causing adhesion effects are molecular forces, electrostatic
forces, and capillary attraction. In dry filtration the role of capillary
forces is much less than that of electrostatic effects. The testing con-
ducted at our Institute confirms the great influence of electrostatic effects
not only on filtration fabric efficiency, but also on susceptibility for
regeneration.
For preliminary interpretation of the calculated values of susceptibil-
ity for regeneration, the following criteria (based on experimental results
obtained up to now) were developed:
Susceptibility for regeneration SR > 80 percent is good,
Susceptibility for regeneration 80 > SR > 70 percent is satisfac-
tory,
Susceptibility for regeneration SR < 70 percent is bad.
145
-------
£
100
50
C8§§§-
C863B
Regeneration by reverse air
flow at regeneration tlae
» 15 seconds j
s =
j RR
J SDD =
P RR
1 ^ =
^RR
3 ID
73.42% for
61.14% for
88.74% for
C866B
C868B
Q53-875
k 3
REQENKK&TIC8? TIME, in seconds
Figure 50. Empirical time dependence of susceptibility for regeneration
during mechanical regeneration (cement dust, q = 60 m3/m2 hr).
146
-------
Table 40 classifies the fabrics according to their susceptibility for regenera-
tion with various dusts at the given A/C ratio.
Because each fabric was tested over 16 experimental conditions (4 kinds
of dust, 2 levels of q 2 regeneration systems), the percent of experiments
y
where the fabric could be regarded as good or satisfactory, from the regenera-
tion viewpoint, was calculated.
The fabrics that in at least 50 percent of the 16 experiments can be
regarded as having good SR, are as follow.
Percent of cases
Fabric showing good regeneration
862B 68.7
Q53-875 56.2
Q53-878 50
C890B 50
C892B 50
The fabrics that in at least 50 percent of the 16 experiments show satisfac-
tory regeneration properties are as follow.
Percent of cases
showing satisfactory
Fabric regeneration
862B
C892B
C890B
Q53-875
Q53-878
190R
C866B
865B
852
Q53-870
850B
87.5
87.5
81.3
75
75
75
68.7
68.7
56.2
56.2
50
As can be gathered from these data, the best regeneration properties are
shown by fabrics with polyester and glass fibers. Nomex fabrics have only
average regeneration properties. Because the group of fabrics with good
regeneration properties include both continuous filament and staple fiber
fabrics, it can be presumed that the fiber style does not influence the
regeneration properties as much as the applied weave and the fabric finishing.
147
-------
TABLE 40. REGENERATION PROPERTIES OF TESTED FABRICS
Susceptibility for
regeneration
Kinrl A/C
Regeneration of (in
system dust m3/m2hr) Good
Reverse air cement 60 C890B
flow C892B
Q53-875
Q53-878
80 862B
865B
C890B
C892B
190R
Q53-875
Q53-878
Unsep. 60 862B
coal 865B
C890B
C892B
190R
Q53-875
Q53-878
80 862B
C866B
C868B
865B
C890B
C892B
852
190R
Q53-875
Q53-870
Q53-878
Talc 60 862B
852
190R
Satisfactory
862B
C866B
8656
190R
850B
Q53-870
C866B
852
850B
802B
Q53-870
C866B
C868B
852
853
850B
802B
Q53-870
853
850B
802B
C866B
865B
C890B
C892B
(continued)
148
-------
TABLE 40. (continued)
Susceptibility for
regeneration
VI~A Mr
Regeneration
system
Mechanical
(10 sec.
vibration)
of (in
dust m3/m2hr) Good
80 862B
865B
C890B
C892B
190R
Q53-875
Fly ash 60
80
Cement 60 862B
C890B
C892B
850B
Q53-870
Q53-878
80 862B
C890B
190R
Q53-875
Q53-878
Unsep. 60 862B
Coal C890B
C892B
Q53-875
Q53-878
Satisfactory
802B
Q53-875
Q53-878
C866B
852
850B
Q53-870
Q53-878
C890B
C890B
C892B
190R
Q53-875
Q53-870
Q53-878
865B
190R
C866B
C892B
850B
C866B
C868B
865B
852
190R
850B
(continued)
149
-------
TABLE 40. (continued)
Susceptibility for
regeneration
Regeneration
system
Nina
of
dust
H/U —
(in
m3/m2hr)
Good Satisfactory
802B
80 862B
C866B
865B
852
Q53-875
Q53-878
Talc 60 862B
852
80 862B
C892B
Q53-875
Fly ash 60
80 Q53-870
C868B
C890B
C892B
190R
802B
Q53-870
C866B
C868B
865B
C892B
190R
Q53-875
Q53-878
C866B
865B
C890B
190R
Q53-870
Q53-878
862B
C892B
852
862B
C890B
C892B
Q53-875
150
-------
Overall, mechanical regeneration exhibits lower susceptibility for
regeneration than regeneration with reverse air flow, although in some
cases, the opposite was observed. However, it should be pointed out that
the longer mechanical regeneration time (longer than 10 seconds) generally
did not increase the regeneration effects. So, the hypothesis can be made
that the most important factor is the first impulse applied to the dust/cake
fabric interface.
Concerning the problem of correlating regeneration susceptibility with
the kind of test dust, the worst results were obtained for fly ash. There
were no fabrics that could be regarded as having good susceptibility for
regeneration with fly ash and there were only six fabrics that showed satis-
factory regeneration properties. Both regeneration systems were investigated.
It is interesting that the group of fabrics with satisfactory regeneration
properties included all three glass fabrics which were designed especially
for filtration of gas containing fly ash. The relationship between suscept-
ibility for regeneration and the kind of dust should be the object for more
detailed examinations.
At present it can be said that the fiber plastic, the grain shape, and
the difference in fractional composition are decisive in this matter. All
the cases discussed above are connected with the adhesion phenomenon (electro-
static effects) that appear at the boundary between the fiber surface and
the dust grain surface. Figure 51 is a comparison of dust grain shapes and
individual grain surfaces.
CONCLUSIONS
The experiments described above lead to the following conclusions
concerning fabric regeneration susceptibility and regeneration systems.
The regeneration properties depend upon the kind of dust, the kind
of plastic of the filtration structure, the kind of weave, and the
method of fabric finishing.
To obtain good regeneration, mixed regeneration systems should be
applied—only under certain conditions should a single regeneration
system be applied, e.g., regeneration of glass fabrics with reverse
air flow.
151
-------
Figure 51. Microscopic pictures of testing dusts (a-cement, b-coal , c-fly ash,
d-talc).
152
Photo credit: SEM by K. Skudlanski, Electronic Microscopy Laboratory of
Wroclaw Polytechnic.
-------
Mechanical regeneration using vibration is most effective during
the initial part of the regeneration process. Hence, longer
regeneration time does not increase the regeneration effects but
can reduce the life of the filtration material.
Overall fly ash showed the worst regeneration properties, being
considerably lower in regeneration susceptibility than the other
dusts tested.
153
-------
SECTION VII
COMPARISON OF THE FILTRATION PROPERTIES OF POLISH
AND U.S. FABRICS
INTRODUCTION
The analysis and comparison of the filtration properties of the Polish
and U.S. fabrics presented in this section was based on results of labora-
tory and large scale testing conducted during this project and on previously
obtained data (from Polish fabrics). Advantage was also taken of results of
Polish polyester and polyamide fabric testing conducted during Project
3
5-533-3 (testing with initial concentration c. = 10 g/m ). (The testing
conditions for Polish fabrics conducted during the years 1969 - 1974 dif-
fered from those assumed for Projects 5-533-3 and 5-533-4).
First of all, the experiments in both the laboratory and on large scale
were conducted with dusts having fractional composition as well as other
physical-chemical properties the same as those of dusts sampled directly
from specific points of the appropriate technological process. The basic
test dusts were cement, coal, and hydrated lime. Some experiments were
carried out on dusts from rotary kilns (with the dust precipitated in the
dust collection systems) and from limestone grinding.
The test conditions were as follow:
o
Initial concentration: 30 g/m .
A/C ratio: 60, 80, and 120 m3/m2hr.
Dust covering of filtration structure: 100, 400, and 700
g/m2.
Temperature: irregular.
Humidity: ambient.
Dispersing medium: atmospheric air at ambient temperature.
Because of the higher initial concentrations (U.S. fabrics were tested at c.
= 10 g/m ), the Polish fabrics were tested at higher dust loading of filtra-
tion area q = 1800 - 3600 g/m2hr.
154
-------
Taking into consideration the above differences in the test conditions,
the comparison of Polish and U.S. fabrics is general rather than complete
because some parameters cannot be compared.
ANALYSIS OF FILTRATION PROPERTIES
The analysis of filtration properties concerns the definite material
groups of fabrics. Figures 52 through 65 represent the qualitative properties
of fabrics such as:
Efficiency, outlet concentration, and filtration resistance obtained
on laboratory scale,
Efficiency, outlet concentration, and filtration resistance obtained
on large scale, and
Fabric filling and resistance of filled structure on laboratory
and large scale.
3 2
The data show test results at an A/C ratio of q = 60 m /m hr and a structure
covered with cement dust, L^ = 400 g/m . The basic technical data concerning
Polish fabrics were added as auxiliary material (Table B-21). As can be
seen from the comparison, Polish as well as U.S. fabrics are characterized
by very high dust collection efficiency.
Natural Fiber Fabrics
This group was represented by wool and cotton fabrics.
Wool: WT-202 and WT-203
Cotton: BT-57 and Cotton 960.
At high dust collection efficiency, the natural fiber fabrics showed different
filtration resistances and quite high structure filling. U.S. cotton 960
and Polish BT-57 have similar dust collection efficiencies of 99.9 percent.
The lower filtration resistances of fabric BT-57 result from its testing
with dusts of lower pulverization (MMD = 36 urn).
Polyester Fabrics
The group of polyester fabrics was represented by:
Staple fiber polyester fabrics
155
-------
en
o>
DO
99,8
99,6
99,4-
99,0
CF
n
60
50
30-1
H
3'9nc
E3JLE
-
CH Unsep. cement dust (c^ = 30 g/m ), lab. scale
f\
DID Unsep. cement dust (c. = 30 g/m ), large scale
o
Sep. cement dust (c^ = 10 g/m ), lab. scale
•3
Sep. cement dust (ci = 10 g/m ), large scale
o
Unsep. kiln dust (c,. = 30 g/m ), lab, scale
Aft
MI
60-
50-
30-
20-
n
OJ CO
Figure 52. Comparison of filtration properties of Polish and U.S.
fabrics (wool, cotton).
-------
C7I
LN
240-
220-
200-
180-
160-
MO-
120-
100-
80-
60-
40-
20-
0
:qfm2]
|
I
r
»
1
1
1
1
1
i
^
§
1
-------
tn
00
100
99,8
99,6
99,4-
99,2
99,0
[mg|mj]
60 -I
40
30
60-
50-
40
30
20
10
0
ET-3 8628 8668 C868B
ET-3 B62B 866B C8688
ET-3 862B 8668 C668B
Figure 54. Comparison of filtration properties of Polish and U.S.
polyester fabrics.
-------
Ul
10
IN
i *
240-
220-
200-
180-
160-
140-
120-
60
40
20
0
I
1
X
X
APN
50
30-
20
10
0
ET-3 8B28 866B CB68B
ET-3 862B 8666 C86BB
Figure 55. Comparison of regeneration properties of Polish and U.S.
polyester fabrics.
-------
E
K
100
99,4-
ET-4
CF
BO
50j
30
20
10
8S26 8668 Cfl68B
ET-4
Aflc
Qfilnfl
60-1
40-
30-
3D-
8628 S666 C866B
ET-4 8688 966 B CS68B
Figure 56. Comparison of filtration properties of Polish and U.S.
polyester fabrics.
-------
LN
en
240-
220-
200-
tafl.
160-
140-
120
100
80
60
40
20
0
AFh
50-
40-
30-
20
10-
0.5 0,5
061
11-4
8668 C868B
EH 8628 S65B C868B
Figure 57. Comparison of regeneration properties of Polish and U.S.
polyester fabrics.
-------
CT>
PO
100.
990.
996-
99,4-
99,2-
99,0.
v
CF
[mglrrfj
60-
50-
40-
20-
10-
_Q
APK
60
50
40
30
20
ET-30 B62B 8668 C8668
ET-30 862B 86BB C8S8B
ET-30 8626 8668 C868B
Figure 58. Comparison of filtration properties of Polish and U.S.
polyester fabrics.
-------
en
to
LN,
200-
180
160
MO
120
100
80
60
40
20
0
60
50
10
30
20
10-I
031
ET-30 8638 866 B C86SB
ET-3D 8638 866B CB6B8
Figure 59. Comparison of regeneration properties of Polish and U.S.
polyester fabrics.
-------
CD
CF
[mg/rrf]
60-
50-
20-
10-
0
Jp
APK
/
/
/x
FtorS S65B C890B C8928
FtorS 8658 C8908 CB928 FtorS 8658 C890B C6928
Figure 60. Comparison of filtration properties of Polish and U.S.
polyester fabrics.
-------
CTl
On
350-
240-
220-
200-
IflQ-
160-
140-
120-
100-
80-
60-
40-
20-
0 -
IN
[g/m2!
wm
1 — 71
A x
^
x,
^
|
|
X
X
g
X
o
^
APN
CkB/nfl
-
50-
40 -
30-
20-
10-
^H ^H D
ITTTI
Fiji TO
FtorS 865B C890B C892B Fbr5 8658 C8906 C8928
Figure 61. Comparison of regeneration properties of Polish and U.S.
polyester fabrics.
-------
a>
E
C 1 •!
[i]
-
100 -
99,8-
99,6-
99,4-
99,2-
99,0
CF
[mg|m J
60-
~7~
/
/
/
x
x
x
1
^
/
/
/
x
x
x
/
x
x
x
C*1
*c
^
1
1
<
\
>
50-
40-
30-
20-
10-
Q
1 If IT / fin I
1 MJ I'll J
60-
50-
40-
30-
20-
10-
7
yX
x
x
x
x
x
x
x
x
X
x
X
C/tn
/ >?
X*S
/K
PT-15 8028
PH5
8028
PT-15
8028
Figure 62. Comparison of filtration properties of Polish and U.S.
polyamide fabrics.
-------
en
•vj
26D
240-
220-
200-
180
160
140-
iao-
100
80-
60-
40-
20
n
LN
felm2]
21$ $
1
I
/>
o
8
X
X
v
I
APN
'[kfilm2]
_
-
50-
40-
30-
20-
10-
0
'mA ilH
PT-15 8028 PT-15 8038
Figure 63. Comparison of regeneration properties of Polish and U.S.
polyamide fabrics.
-------
CTl
00
CF
£
M
100-
99,8-
99,&.
99,4-
99,2-
99,0
70-
60-
50-
— f
|
...
i
:^
1
Vs-
*^
i
'^1
^
T
!
ina
1
\
$
•c
X
X
40-
30-
20-
ig-
0
CO
*T 2 «o
^ 3 5
to
1
^9
!?1
1
«D
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
X
x
x
X
X
x
DkG/rSd
70-
60-
50
40
3D
20
10
^3
3 o
1
i
r|
^t
T?
^i
:?
,r*^
ft
*f
«!
'4
~#
*a>
/
/
/
/
/
/
/
/
^
'
X
^
**
V
^
-------
CTl
ID
LN
[gM
100.
80
60
40
20-
0
40
30
0 PJ.
CO
•
cO
ur>
ir~-
C3Q
Figure 65. Comparison of regeneration properties of Polish and U.S.
glass fabrics.
-------
ET-3, ET-4, ET-30 - Polish production,
862B, C866B, C868B - U.S. production,
Continuous filament polyester fabrics
F-tor 6 - Polish production,
865B, C890B, C892B - U.S. production.
Polyester fabrics are most often used in industrial dust collectors because
of the advantages of polyester fiber.
Staple fiber polyester fabrics have filtration properties similar to
natural fabrics, but have much higher mechanical strength. The fabric
structure favors high efficiencies and low filtration resistivities. Regard-
ing filtration properties, fabric ET-30 produced for the cement industry
equals U.S. fabrics C866B and C868B. Higher filtration resistances for
finer dusts, compared to those of fabrics C866B and C868B, result from its
more compact structure. Compared to staple fiber fabrics, the continuous
filament fabrics show lower filling of structure (LN) and higher filtration
resistances.
Dust collection efficiency, after reaching a steady state, is also very
high, but to a larger degree depends upon q because of the "basket effect"
and interyarn areas (in plain fabric). Fabric F-tor 5 showed filtration
properties similar to U.S fabrics C890B and C892B.
Polyamide Fabrics
This group of fabrics is represented by two fabrics: U.S. staple fiber
fabric 802B and Polish continuous filament fabric PT-15. Dust collection
efficiencies are on the same level, but fabric PT-15 showed higher filtra-
tion resistance. The same reasons as stated above caused lower filling of
structure (I_N) of fabric PT-15 than of fabric No. 802B.
Glass Fabrics
Figures 64 and 65 show the results of the Polish prototype glass fabric
tested with dust from the rotary kiln (HMD = 16 urn) at q =80 m3/m2hr
(laboratory scale). This fabric is produced as fabric ST-7. Similar to
Q53-875, this fabric is also manufactured with staple fibers. The finishing
of the fabrics is different: prototype ST-7 is silicated and fabric Q53-875
is graphited.
170
-------
Because of large differences in the test conditions, it is nearly
impossible to compare filtration properties. Prototype ST-7 was tested in
industrial conditions, yielding a dust collection efficiency of 99.95 percent
3 2
at q = 45 m /m hr and MMD = 8 - 20 urn, at an average gas temperature of
260° C. Based on these results, it can be said that this fabric has very
good filtration properties.
CONCLUSIONS
Comparison of Polish and U.S. woven filtration fabrics, made of different
materials, confirms their very good filtration properties in all analyzed
cases. Also, the conclusion can be made that the woven filtration fabrics
are good filter media for industrial applications. Apart from good filtration
properties, they have high mechanical strength, which in industrial conditions
results in long periods of operation. From a costs viewpoint, the polyester
fabrics are the most attractive for engineering applications.
171
-------
REFERENCES
1. Davies, C. N. Aerosol Science. Academic Press, London and New York.
1966.
2. Koscianowski, J. R., and L. Koscianowska. Effect of Filtration Param-
eters on Dust Cleaning Fabrics, Phase I. EPA-600/2-76-074, U.S.
Environmental Protection Agency, March 1976.
3. Koscianowski, J. R. , and L. Koscianowska. Effect of Filtration Param-
eters on Dust Cleaning Fabrics, Phase II. (in press).
4. Koscianowski, J. R., L. Koscianowska, and M. Szablewicz. Test of
Fabric Filtration Materials, Phase I. (in press).
5. Draemel, D. C. Relationship Between Fabric Structure and Filtration
Performance in Dust Filtration. EPA-R2-73-288, U.S. Environmental
Protection Agency, July 1973.
6. Billings, C. E., and J. Wilder. Handbook of Fabric Filter Technology,
Vol. I. Fabric Filter Systems Study. EPA publication APTD 0690, NTIS
No. PB-200 648, December 1970.
7. Billings, C. E. Fabric Filter Installations for Flue Gas Fly Ash
Control, Status Report. Powder Technology, Vol. 18. 1977. pp. 79-110.
8. Dennis, R., R. W. Cass, and R. R. Hall. Observed Dust Dislodgement
From Woven Fabrics and Its Measured and Predicted Effect on Filter
Performance. Paper 77-32.3 presented to 70th APCA Meeting, Toronto,
Ontario, June 1977.
9. Stephan, D. G., G. W. Walsh, and R. A. Herrick. Concepts in Fabric Air
Filtration. Am Ind Hyg Ass J. , Vol. 21. February 1960. pp. 1-14.
10. Troskolariski, T. A. Hydrodynamika Techniczna, Vol. II. Hydraulika,
Warszawa, PWT, 1954.
11. Holland, C. R. , and E. Rothwell. Model Studies of Fabric Dust Filtra-
tion, Filtration and Separation. Vol. 14, No. 1 (January/February
1977). pp. 30-36.
12. Operating Instructions for Andersen Stack Sampling Equipment.
13. Donovan, R. P., B. E. Daniel, and J. H. Turner. EPA Fabric Filtration
Studies: 3. Performance of Filter Bags Made From Expanded PTFE Laminate,
EPA-600/2-76-168c, U.S. Environmental Protection Agency, December 1976.
172
-------
APPENDIX A
173
-------
99,9
99,5
99
95
go
-~r ~.~L-_-1— ^i1-^- — . '_ \.._c_4/~_
z
0,1
0,5
ID
20
30
40
50
60
70
SO
LU
N
Q
LU
I
90
LU
5E
LU
C£
vo
95
96 ^
97 £
LU
99
1 2345 10 20 3D ® 50
PARTICLE DIAMETER MICROMETERS
100
Figure A-l. Particle size distribution of cement test
dusts: 1 - for laboratory testing; 2 - for
large scale testing.
174
-------
4=M44
99,5
99
95
90
80
70
Q
Ul
50
40
30
X
UJ
10
~r
•.---rrtrt:
•r~M-—H'-r-H 1 V4- ' ' ' ' '
mt^Bi-"4^-V:^i^
= ._4^i_H .. -F- ; ; i-f/ r- •- : : Y~f-~ r^sr-
—---1--I i_i__——•! •- t ---r _ i--—i/i-t,---'-••. :AL-S-—-:^-^?.
0,1
0,5
ID
^70
12
I I i I
_._j 1—
•i-+- >—;• •
H -t-
±
ir±
8D
90
or
95
96
97
gs
-------
10 20 30 43 50
.-ARTICLE DIAMETER, MICROMETERS
Figure A-3. Particle size distribution of talc
test dust.
100
176
-------
. r.- - -.^.: --:r^-^^-.
i I'! u ;--] -t j : - .-.ii-r--—^t±r==
(D
Q
LU
I
LU
<
LU
X
o
LU
99
0;3 1 2345 10 20 30 40 50 100
PARTICLE DIAMETER, MICROMETERS
Figure A-4. Particle size distribution of fly ash
test dust.
177
-------
o
CM
o
S3
IS
a
en
w
a;
,-3
M
80
70
60
50
O
separated cement
separated coal
q =60 m3/m2hr
5
g
.80 m3/m2hr
10 20 3D
FILTRATION TIME in minutes
Figure A-5. Filtration resistance vs. filtration time
for fabric style no. 960.
178
-------
80
7D
60
D
X
separated talc
separated fly ash
•x 2
q-60 nr/m hr
q -80 m3/m2hr
10 20 30
FILTRATION TIME in minutes
Figure A-6. Filtration resistance vs. filtration time
for fabric style no. 960.
179
-------
50
O
A
V
I
eparated calment
separated coal
unseparated coal
q -60 m'/m hr
a .80 m3/m2hr
10 20 30
FILTRATION TIME in minutes
Figure A-7. Filtration resistance vs. filtration time
for fabric style no. 862B.
180
-------
60
D separated talc
X separated fly ash
•2 2
q »60 nr/m hr
10 20 30
FILTRATION TIME in minutes
Figure A-8. Filtration resistance vs. filtration time
for fabric style no. 862B.
181
-------
70
Q
separated cement
separated coal
onseparated coal
<1 »80 m /m hr
O
10 20 30
FILTRATION TIME In minutes
Figure A-9. Filtration resistance vs. filtration time
for fabric style no. C866B.
182
-------
separated talc
separated fly ash
•» p
q «60 nr/m hr
10 20 30
FILTRATION TIME in minutes
Figure A-10. Filtration resistance vs. filtration time
for fabric style no. C866B.
183
-------
i
a
a 40
g
B
separated coal
imiMtpft rated coal
fO 3D 30
FILTRATION TIME in minutes
Figure A-ll. Filtration resistance vs. filtration time
for fabric style no. C868B.
184
-------
separated talc
separated fly ash _
•x 2
q =60 nr/m hr
q »80 m5/m2hr
10 20 30
FILTRATION TIME in minutes
Figure A-12. Filtration resistance vs. filtration time
for fabric style no. C868B.
185
-------
o
fvl
70
60
0
H
ri
O
A
V
separated cement
separated coal
unseparated
q =60 m*
g ^2
q =80 m /m hr
S
10 ft 3D
FILTRATION TIME in minutes
Figure A-13.
Filtration resistance vs. filtration time
for fabric style no. 865B.
186
-------
separated talc
separated fly ash
q -.60 m^/nftir
J
10 20 3D
FILTRATION TIME In minutes
Figure A-14.
Filtration resistance vs. filtration time
for fabric style no. 865B.
187
-------
o
CM
i
8 fl
M
b,
»«p»rat»d cwwnt
•«par»ted coal
un»«parftt«d coal
20 30
FILTRATICW TIME in minutes
Figure A-15.
Filtration resistance vs. filtration time
for fabric style no. C890B.
188
-------
110
100
90
separated talc
— X separated fly ash.
q »60 nr/m hr
q -80 nr/m hr
S
10 20 30
FILTRATION TIME in minutes
Figure A-16.
Filtration resistance vs. filtration time
for fabric style no. C890B.
189
-------
CO
DL,
separated cement
separated coal
unseparated coal
FILTRATION TIME In minutes
Figure A-17. Filtration resistance vs. filtration time
for fabric style no. C892B.
190
-------
separated talc
separated fly ash
nr/inhr.
10 20 30
FILTRATION TIME In minutes
Figure A-18.
Filtration resistance vs. filtration time
for fabric style no. C892B.
191
-------
60
50
O
A
V
separated cement
separated coal
unseparated coal
•» «
q »60 nr/m hr.
Figure A-19.
FILTRATION TEffi in minutes
Filtration resistance vs. filtration time
for fabric style no. 852.
192
-------
separated talc
separated fly ash
•Z <}
q =60 nr/m hr.
20 30
FILTRATION TIME in minutes
Figure A-20. Filtration resistance vs. filtration time
for fabric style no. 852.
193
-------
separated cement
separated coal
•r •}
q =60 nr/m hr.
Figure A-21.
10 SO 30
FILTRATION TIT-IE in minutes
Filtration resistance vs. filtration time
for fabric style no. 853.
194
-------
separated talc
separated fly ash
q =60 nr/ir
£ Tt 1
q =80 nr/m hr.
S
ID 20 30
FILTRATION TIME in minutes
Figure A-22. Filtration resistance vs. filtration time
for fabric style no. 853.
195
-------
70
••parated cement
0«parat*d coal
«60
.80
Figure A-23.
10 20 30
FILTRATION TIME In minutes
Filtration resistance vs. filtration time
for fabric style no. 190R.
196
-------
70
60
D separated talc
X separated fly ash
•T O
q =60 m /m hr.
o
/O 20 30
FILTRATION TIME In minutes
40
Figure A-24. Filtration resistance vs. filtration time
for fabric style no. 190R.
197
-------
110
100
90
O separated cement
A separated coal
-z 2
q =60 nr/:n hr.
Z ^2.
q,T=QO m^/m hr.
10 20 30
FILTRATION TIME in minutes
Figure A-25.
Filtration resistance vs. filtration time
for fabric style no. 850B.
198
-------
no
100
separated talc
separated fly ash
10 20 30
FILTRATION TEffi in minutes
40
Figure A-26. Filtration resistance vs. filtration time
for fabric style no. 850B.
199
-------
70
o
OJ
i
to
M
to
S
60
O separated cement
A separated coal
q»SO ar/m hr.
q «80 m'/m hr.
X-
Figure A-27.
ID ao 3o
FILTRATION TIME in minutes
Filtration resistance vs. filtration time
for fabric style no. 802B.
200
-------
60
D
X
separated talc
separated fly ash
q =60 nrVm2hr.
q =80 m3/m2hr.
10 20 30 41
FILTRATION TIME in r.iinutcs
Figure A-28. Filtration resistance vs. filtration time
for fabric style no. 802B.
201
-------
7D
60
O
A
separated cement
separated coal
q-60 m3/rn2hr.
ro so 30
FILTRATION TIME in minutes
Figure A-29. Filtration resistance vs. filtration time
for fabric style no. Q53-875.
202
-------
separated talc
separated fly ash
q =60 m^/m2hr.
10 20 30
FILTRATION TIT-IE in minutes
Figure A-30. Filtration resistance vs. filtration time
for fabric style no. Q53-875.
203
-------
flO
100
O
o
-------
110
100
90
D
X
separated talc
separated fly ash
q =50 .n /ra hr.
V 2
tn /m hr
/O
FILTRATION TIMU iu minutes
Figure A-32. Filtration resistance vs. filtration time
for fabric style no. Q53-870.
205
-------
70
60
o
A
separated cement
separated coal
•z o
=60 or/in hr.
*cr
o
•z 2
=80 ttr/m hr.
10 2D~ 30
FILTPJvTIOM TI3E in minutes
Figure A-33. Filtration resistance vs. filtration time
for fabric style no. Q53-878.
206
-------
P] separated talc
y separated fly ash
601 q_«60 m5/m2hr.
qg=80 m"Vm2hr«
10 20 30 40
FILTRATION TEE in minutes
Figure A-34. Filtration resistance vs. filtration time
for fabric style no. Q53-878.
207
-------
APPENDIX B
208
-------
TABLE B-l. PRESSURE DROP (in mmH20) vs. GAS LOADING OF FILTRATION AREA FOR PURE FABRICS
Kind
of
fabric
960
Average
862B
Average
C866B
Average
C868B
Average
50
2.77
3.08
3.16
2.84
2.84
2.94
0.16
0.16
0.16
0.19
0.16
0.17
0.40
0.40
0.47
0.40
0.32
0.40
0.79
0.71
0.63
0.63
0.63
0.68
60
3.63
3.79
3.87
3.40
3.48
3.63
0.19
0.19
0.19
0.22
0.19
0.20
0.47
0.47
0.55
0.47
0.40
0.47
0.87
0.87
0.79
0.79
0.79
0.82
80
5.29
5.29
5.61
4.98
5.06
5.25
0.25
0.25
0.28
0.32
0.28
0.28
0.63
0.71
0.79
0.71
0.55
0.68
1.26
1.26
1.19
1.11
1.11
1.19
qg
100
7.11
7.27
7.90
7.03
7.19
7.30
0.35
0.38
0.38
0.44
0.38
0.39
0.95
0.95
1.11
0.95
0.71
0.93
1.74
1.66
1.58
1.50
1.50
1.60
in m3/m2hr
120
8.85
9.64
10.19
9.09
9.32
9.42
0.51
0.51
0.51
0.60
0.54
0.53
1.26
1.26
1.50
1.34
1.03
1.28
2.29
2.21
2.31
1.98
2.05
2.13
140
10.83
11.77
12.32
11.14
11.38
11.49
0.66
0.66
0.66
0.79
0.70
0.69
1.58
1.58
1.98
1.74
1.34
1.64
2.92
2.84
2.69
2.45
2.61
2.70
160
12.72
13.98
14.54
13.04
13.19
13.49
0.79
0.82
0.82
0.95
0.82
0.84
1.90
1.90
2.29
2.05
1.58
1.94
3.56
3.40
3.16
2.92
3.08
3.22
180
14.62
16.04
16.59
14.85
15.01
15.42
0.92
0.95
0.95
1.11
0.98
0.98
2.29
2.21
2.69
2.45
1.82
2.29
4.11
3.95
3.63
3.40
3.63
3.74
Conditions
Temp. Rel . Atm.
Hum. Press.
°C % mmHq
20 47 745
20 42 748
23 47 742
(continued)
-------
TABLE B-l. (continued)
Kind
of
fabric
365B
Average
C890B
ro
i— '
Average
C892B
Average
852
Average
50
0.63
0.79
0.79
1.03
0.95
0.84
1.19
1.03
1.03
1.26
0.95
1.09
1.50
1.50
1.66
1.74
1.90
1.66
0.16
0.19
0.22
0.19
0.19
0.19
60
0.95
1.03
1.03
1.26
1.19
1.09
1.42
1.26
1.26
1.50
1.19
1.33
1.82
1.82
2.13
2.21
2.37
2.07
0.24
0.25
0.25
0.22
0.25
0.24
80
1.26
1.50
1.50
1.90
1.82
1.58
2.05
1.74
1.82
2.13
1.58
1.86
2.61
2.69
3.00
3.08
3.32
2.94
0.32
0.35
0.38
0.35
0.35
0.35
qg in
10U
1.90
2.21
2.21
2.69
2.61
2.32
2.69
2.29
2.37
2.37
2.13
2.37
3.48
3.79
4.03
4.03
4.58
3.98
0.47
0.47
0.51
0.44
0.47
0.47
m3/m2hr
IZO
2.53
2.84
2.84
3.48
3.40
3.01
3.48
2.92
3.00
3.63
2.6.9
3.14
4.50
4.82
5.21
5.21
5.77
5.10
0.55
0.60
0.66
0.60
0.63
0.61
140
3.00
3.48
3.48
4.19
4.11
3.65
4.19
3.48
3.63
4.35
3.24
3.78
5.53
5.77
6.32
6.56
7.19
6.27
0.71
0.79
0.85
0.76
0.79
0.78
IbU
3.48
3.95
3.95
4.99
4.82
4.24
5.06
4.11
4.27
5.21
3.79
4.49
6.64
6.79
7.66
7.74
8.53
7.47
0.87
0.92
1.01
0.89
0.95
0.93
Conditions
Temp. Rel . Atm.
Hum. Press.
181) °l % mmHq
3.95 20 47 745
4.66
4.74
5.61
5.53
4.90
6.00 22 35 742
4.98
4.98
6.16
4.42
5.31
7.74 22 35 742
7.82
8.77
8.93
10.03
8.63
1.03 23 53 746
1.11
1.14
1.04
1.07
1.08
(continued)
-------
TABLE B-l. (continued)
Kind
of
fabric
853
Average
190R
Average
850B
Average
802 B
Average
q in m3/m2hr
y
50
0.63
0.79
0.63
0.63
0.55
0.65
1.11
1.19
1.03
1.11
1.11
1.11
0.63
0.63
0.63
0.63
0.63
0.63
0.87
0.79
0.79
0.87
0.95
0.85
60
0.79
0.95
0.79
0.79
0.71
0.81
1.34
1.42
1.26
1.42
1.34
1.36
0.79
0.79
0.79
0.79
0.79
0.79
1.03
0.95
0.95
1.03
1.11
1.01
80
1.11
1.42
1.11
1.19
1.03
1.17
1.90
2.05
1.82
1.97
1.98
1.94
1.11
1.11
1.11
1.19
1.11
1.13
1.50
1.34
1.34
1.50
1.58
1.45
100
1.50
1.83
1.42
1.50
1.34
1.52
2.53
2.77
2.45
2.61
2.61
2.59
1.50
1.50
1.50
1.58
1.50
1.52
1.98
1.74
1.82
2.05
2.13
1.94
120
1.98
2.45
1.90
2.05
1.74
2.02
3.32
3.63
3.24
3.40
3.40
3.40
1.98
1.98
1.98
2.13
2.05
2.02
2.69
2.29
2.45
2.69
2.92
2.61
140
2.37
3.00
2.29
2.53
2.12
2.46
4.03
4.42
3.95
4.19
4.19
4.16
2.53
2.45
2.45
2.61
2.53
2.51
3.40
2.92
3.00
3.40
3.63
3.27
160
2.84
3.56
2.77
3.00
2.61
2.96
4.74
5.14
4.58
4.90
4.90
4.85
3.00
2.92
2.92
3.00
2.92
2.95
4.03
3.48
3.63
4.03
4.35
3.90
180
3.24
4.11
3.08
3.40
2.92
3.35
5.37
5.93
5.29
5.61
5.61
5.56
3.63
3.32
3.32
3.48
3.40
3.43
4.66
3.95
4.19
4.66
4.98
4.49
Conditions
Temp. Rel . Atm.
Hum. Press.
°C % mmHq
23 48 750
23 54 746
23 48 750
23 47 742
(continued)
-------
TABLE B-l. (continued)
ro
Kind
of
fabric
Q53-875
Average
Q53-870
Average
Q53-979
50
0.22
0.22
0.22
0.22
0.22
0.22
1.90
1.90
1.90
1.90
1.90
1.90
0.35
0.35
0.38
0.35
0.38
60
0.28
0.32
0.25
0.25
0.28
0.2C
2.21
2.21
2.21
2.21
2.21
2.21
0.44
0.44
0.47
0.44
0.44
80
0.41
0.44
0.38
0.38
0.41
0.40
3.32
3.48
3.32
3.32
3.48
3.38
0.66
0.63
0.70
0.60
0.69
V
100
0.54
0.57
0.51
0.54
0.57
0.55
5.06
5.06
4.74
4.90
5.06
4.96
0.92
0.89
0.95
0.95
0.98
n m3/m2hr
120
0.76
0.79
0.73
0.76
0.79
0.77
6.64
6.64
6.32
6.48
6.64
6.54
1.26
1.20
1 1.30
1.26
1.33
140
0.95
0.98
0.89
0.92
1.01
0.95
8.22
8.06
7.90
7.90
8.06
8.03
1.61
1.55
1.65
1.61
1.65
160
1.11
1.14
1.07
1.11
1.17
1.12
9.64
9.48
9.32
9.48
9.64
9.51
1.92
1.83
1.98
1.96
1.98
180
1.26
1.33
1.26
1.30
1.33
1.30
11.22
11.06
10.74
10.90
11.06
11.00
2.24
2.17
2.34
2.28
2.31
Conditions
Temp. Rel . Atm.
Hum. Press.
°C % mmHg
25 50 747
26 38 747
25 50 747
Average
0.36 0.45
0.66
0.94
1.27
1.61
1.93
2.27
-------
TABLE B-2. YARN PARAMETERS
(Accomplished by Textile Institute in Lodz)
Kind
of
fabric
Polyester -
862B
warp
fill
MC866B
co
warp
fill
C868B
warp
fill
Polyester -
865B
warp
fill
C890B
warp
fill
C892B
warp
fill
Diameter
of
fiber
in
ym
staple fiber
19.2
19.0
--
--
22.0
22.0
continuous fi
24.2
18.9
23.2
23.4
23.4
23.8
Number
of fibers
in cross-
section
of yarn
230
266
307
276
215
180
lament fiber
100
209
50
50
50
50
Tex
of
yarn
112.7
137.0
119.3
113.6
135.8
138.1
67.1
79.2
29.2
30.1
29.8
30.9
Parameter
Diameter
of fiber
calculated
from
Tex in
ym
443
489
456
445
487
491
388
372
256
260
259
264
Project-
ing
diameter
of yarn,
width/
thickness
in
urn
616/422
683/431
573/455
645/431
543/430
573/439
400/240
527/320
343/173
368/164
—
"
Degree
of
yarn
flatten
0.32
0.33
0.21
0.33
0.21
0.23
0.40
0.39
0.50
0.55
--
_ _
Number
of
twist
in
n/meter
279
235
394
268
399
279
274
399
133
146
without
twist
21
(continued)
-------
TABLE B-2. (continued)
Kind
of
fabric
Nomex -
852
warp
fill
853
warp
fill
Nomex -
Diameter Number
of of fibers
fiber in cross-
in section
ym of yarn
staple fiber
continuous filament fiber
350B
warp
fill
Polyamide - staple fiber
802 B
warp
fill
Natural
960
warp
fill
fiber - cotton
__
Tex
in
yarn
119.4
122.7
110.0
118.8
22.5
22.2
119.5
137.5
39.8
66.8
Parameter
Diameter
of fiber
calculated
from
Tex in
ym
519
525
497
518
225
224
519
556
250
323
Project-
ing
diameter
of yarn,
width/
thickness
in
ym
679/533
852/655
325/218
478/360
Number
Degree of
of twist
yarn in
flatten n/meter
334
331
314
334
160
200
0.22 416
0.23 238
0.33 871
0.25 515
(continued)
-------
TABLE B-2. (continued)
INS
Kind
of
fabric
Glass -
Q53-875
warp
fill
Glass -
Q53-870
warp
fill
Q53-878
warp
fill
Diameter
of
fiber
in
ym
staple fiber
--
--
continuous filament
—
—
—
—
Number
of fibers
in cross-
section
of yarn
--
--
fiber
—
—
--
—
Tex
of
yarn
67.6
66.2
67.5
68.6
138.8
211.5
Parameter
Diameter
of fiber
calculated
from
Tex in
ym
216
214
216
217
309
383
Project-
ing
diameter
of yarn,
width/
thickness
in
ym
443/175
442/183
445/186
474/167
558/278
891/395
Dearee
of
yarn
flatten
0.60
0.57
0.58
0.65
0.50
0.56
Number
of
twist
in
n/meter
145
126
144
128
146
81
-------
TABLE B-3. SIZE OF DUCTS/CANALS FORMED DURING TESTING
OF GLASS FABRIC Q53-878 WITH SEPARATED CEMENT
qg
in
m3/m2hr
60
80
100
Size of ducts/
canals
a x b
in
um
Series 2 experiment 1
80x150
50X100
30X90
50X220
60X150
50X200
90X110
30X70
60X220
60X170
20X70
110X200
120X240
110X200
10*160
70X170
100X110
70X100
60X160
40X100
70X180
90X260
60X110
30X70
20X130
60X110
30X60
50X100
30X60
20X110
50X50
60X190
90X120
60X110
60X160
110X180
60X220
50X190
20X170
20X150
Equivalent
diameter
d = 4ab / a + b
in
ym
104.35
66.67
45.00
81.48
85.71
80.00
99.00
42.00
94.28
88.69
31.10
141.93
160.00
141.93
18.82
99.17
104.76
82.35
87.27
57.14
100.80
133.71
77.65
42.00
34.67
77.65
40.00
66.67
40.00
33.85
50.00
91.20
102.86
77.65
87.27
136.55
94.29
79.17
35.79
35.29
(continued)
216
-------
TABLE B-3. (continued)
qg
in
m3/m2hr
120
Size of ducts/
canals
a x b
in
urn
60x150
30x110
10x110
70x160
100x120
80x150
40x80
70x150
80x100
100x130
20x170
80x200
60x150
100x100
150x150
70x220
110x220
50x200
20x180
60x250
30x130
60x150
100x180
40x100
120x250
70x180
50x230
20x200
60x150
60x280
40x200
50x120
50x170
60x200
20x170
100x200
50x220
120x220
30x150
50x150
50x50
50x50
Equivalent
diameter
d = 4ab / a + b
in
Mm
85.71
47.14
18.33
97.39
109.09
104 35
53.33
95.45
88.89
113.04
35.79
114.29
85.71
100.00
150.00
160.21
146.67
80.00
36.00
96.77
48.75
85.71
128.57
57.14
133.33
100.80
82.14
36.36
85.71
98.82
66.67
70.59
77.27
92.31
35.79
133.33
81 .48
155.29
50.00
75.00
50.00
50.00
(continued)
217
-------
TABLE B-3. (continued)
qg
in
m3/m2hr
150
Size of ducts/
canals
a x b
in
Mm
80x150
10x140
30x130
50*70
40X160
100X170
20X140
70X170
60X160
30X180
40X140
20X150
50X200
30X130
30X200
20X150
50X170
70X150
30X200
70X170
60X90
40X250
100X120
40X140
20X120
60x260
50X250
70X150
50X160
50X250
50X200
70X220
60X230
50X170
80X150
40X210
40X110
90X270
30x130
60x180
90x240
60X80
70x250
Equivalent
diameter
d = 4ab / a + b
e in
Mm
104.35
18.67
48.00
58.33
64.00
125.93
35.00
99.17
87.27
51.43
62.22
35.29
80.00
48.75
52.17
35.29
77.27
95.45
52.17
99.17
72.00
68.97
109.09
62.22
34.29
97.50
83.33
95.45
76.19
83.33
80.00
106.21
95.17
77.27
104.35
67.20
58.67
135.00
48.75
90.00
187.83
68.57
159.09
218
(continued)
-------
TABLE B-3. (continued)
"a
in
m3/m2hr
200
Size of ducts/
canals
a x b
in
Mm
80x220
60x260
90x140
100x150
80x200
50x160
20x130
50x120
30x160
20x160
60x120
100x150
20x70
40x150
100x150
20x250
90x210
90x290
40x140
40x120
20x140
30x120
80x100
20x70
30x50
60x150
50x170
40x200
50x100
60x150
60x160
30x70
60x120
70x130
30x60
40x80
30x120
70x90
40x140
50x110
100x200
30x100
Equivalent
diameter
d = 4ab / a + b
in
Mm
117.33
97.50
109.56
120.00
114.29
76.19
34.67
70.59
50.53
35.56
80.00
120.00
31.11
63.16
120.00
37.04
126.00
137.37
62.22
60.00
35.00
48.00
88.89
31.11
37.50
85.71
77.27
66.67
66.67
85.71
87.27
42.00
80.00
91.00
40.00
53.33
48.00
78.75
62.22
68.75
133.33
46.15
219
(continued)
-------
TABLE B-3. (continued)
qg
in
m3/m2hr
80
Size of ducts/
canals
a x b
in
Mm
60x100
60x120
50x260
50x90
60x250
20x100
100x200
60x160
50x120
60x200
40x90
80x220
Series 2 experiment 2
100x150
60x130
40x130
30x120
30x150
40x150
40x170
20x240
60x140
20x180
90x140
70x210
10x120
50x160
20x180
50x150
100x130
80x90
40x170
10x130
40x130
50x100
20x250
20x200
70x290
80x210
70x70
120x130
30x130
Equivalent
diameter
d = 4ab / a + b
e in
urn
75.00
80.00
83.87
64.29
96.77
33.33
133.33
87.27
70.59
92.31
55.38
117.33
120.00
82.10
61.18
48.00
50.00
63.16
64.76
36.92
84.00
36.00
109.56
105.00
18.46
76.19
36.00
75.00
113.04
84.71
64.76
18.57
61.18
66.67
37.04
36.36
112.78
115.86
70.00
124.80
48.75
(continued)
220
-------
FABLE B-3. (continued)
qa
in
m3/m2hr
100
120
Size of ducts/
canals
a x b
in
(jm
50x110
30x100
60x190
20x180
80x150
60x170
70x160
50x140
130x130
60x130
60x150
10x200
40x200
90x250
30x120
60x210
130x230
90x220
100x140
60x150
70x180
100x200
70><250
70x230
20x200
30x150
50x200
70x220
70x130
40x120
60x200
100x150
40x140
70x190
50x200
60x240
80x160
30x100
120x200
50x200
40x180
50x50
Equivalent
diameter
d = 4ab / a + b
in
Mm
68.75
46.15
91.20
36.00
104.35
88.70
97.39
73.68
130.00
82.10
85.71
19.05
66.67
187.50
48.00
93.33
166.11
127.74
116.67
85.71
100.80
133.33
109.37
107.33
33.33
50.00
80.00
106.21
91.00
60.00
92.31
120.00
62.22
102.31
80.00
96.00
106.67
46.15
150.00
80.00
65.45
50.00
221
(continued)
-------
TABLE B-3. (continued)
qg
in
m3/m2hr
150
Size of ducts/
canals
a x b
in
urn
70x140
60x150
50x80
30x130
40x150
70x200
100x140
70x220
40x100
30x200
50x200
100x130
20x200
40x80
10x120
30x150
140x200
60x120
40x120
90x220
40x150
50x130
40x120
30x170
80x220
40x180
50x150
70x270
40x100
60x170
40x80
70x180
50x150
70x120
60x120
70x170
90x170
100x250
80x220
80x150
50x200
40x120
Equivalent
diameter
d = 4ab / a + b
e in
urn
93.33
85.71
61.54
48.75
63.16
103.70
116.67
106.21
57.14
52.17
80.00
113.04
36.36
53.33
18.46
50.00
164.71
80.00
60.00
127.74
63.16
72.22
60.00
51.00
117.33
65.45
75.00
111.18
57.14
88.70
53.33
100.80
75.00
88.42
80.00
99.17
117.69
142.86
117.33
104.35
80.00
60.00
222
(continued)
-------
TABLE B-3. (continued)
qg
in
m3/m2hr
200
Size of ducts/
canals
a x b
in
Mm
100x130
50x90
40x150
70x200
70x250
30x250
60x220
30x130
100x150
50x250
40x150
80x180
30x120
50x120
50x120
40x170
30x120
30x150
40x200
30x70
50x220
70x70
80X110
70x170
90x220
50x180
20x200
30X200
70X120
100x220
100x100
60x70
60X160
100X240
90^190
Equivalent
diameter
d = 4ab / a + b
in
(jm
113.04
64.29
63.16
103.70
109.37
53.57
94.29
48.75
120.00
83.33
63.16
110.77
48.00
70.59
70.59
64.76
48.00
50.00
66.67
42.00
81.48
70.00
92.63
99.17
127.74
78.26
36.36
52.17
88.42
137.50
100.00
64.61
-87.27
141.18
122.14
223
-------
TABLE B-4. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated cement, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
25.5
21.9
23.0
24.3
27.1
36.2
33.2
19.6
18.7
12.7
38.9
18.5
37.0
44.72
33.14
AP
0
3.6
0.5
0.8
1.4
1.0
1.6
2.1
0.5
0.8
1.6
4.7
1.0
0.6
1.9
0.6
APNK
14.3
5.1
6.7
10.3
8.7
5.2
4.9
6.4
8.3
4.7
11.6
7.6
4.7
12.8
6.0
TABLE B-5. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
MECHANICAL REGENERATION
(Dust: separated cement, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
15.2
4.3
7.7
9.9
6.5
4.3
4.4
6.6
9.8
5.5
7.4
7.3
4.6
18.2
5.4
APRM2
15.2
3.5
6.8
9.3
6.3
4.7
4.4
6.6
9.6
5.5
6.8
7.3
4.1
15.5
4.7
APRM3
15.6
2.8
6.2
9.2
6.0
4.6
4.6
6.2
9.5
5.5
6.8
7.3
3.8
15.8
4.7
224
-------
TABLE B-6. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated cement, q=80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
30.6
34.2
32.1
32.5
47.5
64.8
65.9
26.3
26.6
17.9
56.2
29.5
56.2
61.7
47.3
APo
7.4
0.8
1.1
2.1
1.6
3.5
3.6
0.8
2.4
2.2
1.9
1.9
0.9
3.0
1.1
APNK
16.7
5.5
8.5
14.5
8.6
11.6
12.3
7.8
11.5
4.9
14.4
8.8
8.6
19.8
6.4
TABLE B-7. CHARACTERISTIC PRESSURE DROP (in rnnH20) FOR
MECHANICAL REGENERATION
(Dust: separated cement, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
053-870
Q53-878
APRM1
18.8
4.3
9.2
14.2
16.4
15.3
18.5
9.0
12.6
5.1
16.3
11.1
7.3
24.2
7.9
APRM2
19.4
3.6
8.4
13.9
12.0
10.9
12.8
8.8
12.3
5.5
11.5
10.6
3.5
17.4
5.2
APRM3
19.4
3.0
7.6
13.7
10.4
10.4
12.8
7.9
12.3
5.5
11.4
10.6
3.3
18.6
5.2
225
-------
TABLE B-8. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: unseparated coal, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802 B
Q53-875
Q53-870
Q53-878
APK
28.6
28.9
22.7
28.3
26.9
35.5
51.5
25.4
22.0
17.6
41.0
20.2
51.1
58.0
42.4
APo
3.5
0.9
1.1
1.9
1.6
1.4
3.3
0.8
1.4
1.6
1.4
1.6
0.8
2.8
0.9
APNK
14.0
5.4
5.5
7.6
6.1
7.1
10.1
6.9
7.4
4.9
10.4
5.8
6.3
15.7
5.5
TABLE B-9. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
MECHANICAL REGENERATION
(Dust: unseparated coal, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
14.7
5.4
5.7
7.7
7.7
7.1
10.3
7.4
7.9
5.2
11.7
6.2
8.7
19.8
6.8
APRM2
14.7
5.2
5.4
7.9
7.4
8.4
10.7
7.6
7.7
5.2
12.6
6.3
8.4
21.2
7.1
APRM3
14.7
5.1
5.1
7.9
7.1
8.7
10.7
7.4
7.7
5.2
13.3
6.2
8.1
22.3
7.1
226
-------
TABLE B-10. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: unseparated coal, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
38.9
29.5
31.2
29.3
42.1
65.6
53.9
28.3
26.4
20.9
54.4
26.2
51.9
66.7
52.4
AP
0
5.8
1.1
1.6
1.9
1.7
3.8
4.1
1.7
1.9
2.1
2.7
1.9
0.9
3.4
1.3
APNK
18.1
5.5
6.6
7.2
7.1
12.5
12.5
5.9
7.7
5.1
14.4
7.8
6.8
13.0
5.3
TABLE B-ll. CHARACTERISTIC PRESSURE DROP (in mmH20). FOR
MECHANICAL REGENERATION
(Dust: unseparated coal, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
19.8
6.2
7.1
7.7
7.0
18.2
15.3
5.8
9.3
6.0
22.9
8.1
10.9
16.0
5.2
APRM2
20.2
6.0
7.1
7.3
7.4
19.0
17.1
6.3
9.6
5.7
21.0
8.1
10.9
16.0
5.5
APRM3
20.7
5.7
6.8
7.1
7.4
19.6
15.6
6.0
9.8
5.5
19.6
8.1
10.1
16.0
5.5
227
-------
TABLE B-12. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated talc, q = 60 m3/m2nr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
26.8
20.2
22.2
22.0
34.4
49.1
38.1
19.6
14.7
14.1
36.6
23.6
50.6
41.4
38.3
AP
0
4.0
0.6
0.8
1.4
1.3
2.8
2.1
0.6
1.1
1.4
1.4
2.7
0.8
2.5
1.1
APNK
11.5
4.3
5.7
7.8
8.2
16.6
10.7
3.2
8.8
3.6
14.0
8.9
12.0
15.3
10.8
TABLE B-13. CHARACTERISTIC PRESSURE DROP (in mrnH20) FOR
MECHANICAL REGENERATION
(Dust: separated talc, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-370
Q53-878
APRM1
12.3
4.3
5.5
7.4
8.1
17.1
12.3
5.1
9.2
4.0
13.6
10.3
14.4
12.0
16.9
APRM2
12.8
4.0
6.2
7.7
8.1
16.1
11.2
5.5
9.5
4.1
13.7
10.4
11.2
12.0
16.9
APRM3
12.8
3.8
6.2
7.6
7.9
15.6
10.9
5.4
9.5
4.1
13.9
10.4
10.3
11.7
17.1
228
-------
TABLE B-14. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated talc, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
37.5
34.2
33.0
28.6
40.8
60.5
45.6
22.4
22.5
16.8
63.9
23.8
54.5
80.6
51.9
AP
0
5.7
0.8
1.1
2.4
2.1
4.3
2.9
1.1
1.9
1.9
2.5
1.9
1.1
3.4
1.1
APNK
17.4
5.5
8.1
10.6
8.5
15.5
9.5
6.5
10.6
4.8
19.0
8.7
8.5
22.7
12.6
TABLE B-15. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
MECHANICAL REGENERATION
(Dust: separated talc, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
18.0
6.2
9.6
12.3
10.7
20.2
8.8
9.6
10.9
5.1
21.2
9.6
11.4
25.4
14.2
APRM2
18.2
6.0
9.0
12.2
10.6
20.5
6.6
9.8
10.7
5.2
21.8
9.8
12.2
26.7
14.4
APRM3
18.2
5.8
8.4
11.4
10.4
20.1
6.0
9.5
10.7
5.1
21.6
9.6
11.7
26.5
14.2
229
-------
TABLE B-16. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated fly ash, q = 60 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
23.1
15.2
14.9
16.6
22.3
29.2
31.9
15.7
--
8.9
26.8
16.4
26.4
37.7
15.6
AP
0
4.7
1.3
0.8
1.1
2.1
1.3
2.4
0.6
—
1.3
2.4
1.0
1.3
1.9
0.6
APNK
15.1
5.7
8.3
7.6
8.2
8.7
11.3
5.7
--
4.6
10.8
6.8
11.4
17.8
6.0
TABLE B-17. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
MECHANICAL REGENERATION
(Dust: separated fly ash, q = 60 m3/tn2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
19.1
4.7
10.3
7.7
8.8
11.7
10.6
4.7
—
4.6
12.5
11.9
11.5
16.0
6.0
APRM2
18.8
4.4
9.5
7.6
7.6
9.6
14.5
4.6
__
4.4
11.4
10.6
12.3
17.1
5.8
APRM3
17.7
4.1
9.2
7.3
7.1
8.2
4.9
4.1
_ _
4.4
11.4
9.9
13.1
19.1
6.0
230
-------
TABLE B-18. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
REVERSE AIR FLOW REGENERATION
(Dust: separated fly ash, qQ = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APK
27.2
18.1
22.9
21.2
34.6
44.4
44.9
21.4
—
11.3
44.4
19.6
45.4
46.2
28.8
AP
0
3.8
3.0
1.3
1.7
1.9
2.8
3.2
0.8
—
1.7
1.4
1.9
0.8
3.4
0.8
APNK
15.6
8.0
9.9
8.7
13.7
11.3
12.4
9.4
__
4.5
17.7
10.4
9.8
14.3
8.3
TABLE B-19. CHARACTERISTIC PRESSURE DROP (in mmH20) FOR
MECHANICAL REGENERATION
(Dust: separated fly ash, q = 80 m3/m2hr)
Kind of fabric
960
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
APRM1
16.1
6.3
13.6
9.2
14.1
12.2
13.7
20.1
--
9.8
16.3
11.2
12.6
9.5
10.3
APRM2
16.6
5.8
12.8
9.2
11.9
11.5
12.0
19.6
--
9.8
16.8
11.1
11.1
9.2
9.6
APRM3
16.6
5.4
12.2
9.0
11.1
11.5
12.5
19.1
--
9.6
16.9
11.1
10.7
8.5
9.6
231
-------
TABLE B-20. TABULATION OF Lo, LW, AND L
EXPERIMENTS IN LARGE SCALE I
CALCULATED FROM DUST BALANCE FOR
Kind Kind
of of
fabric dust
960 Sep.
Cement
862B
C866B
C868B
865B
C890B
C892B
852
853
190R
850B
802 B
Q53-875
Q53-870
Q53-878
960 Unsep.
Coal
862B
C866B
m3/fl2h
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
L°o
g/mz
403.6
396.6
400.6
398.0
398.3
395.5
398.8
396.4
400.9
400.5
391.8
399.0
400.7
394.6
401.1
394.8
400.5
399.5
402.8
399.7
403.8
396.1
404.4
401.7
403.0
405.7
400.4
400.6
403.5
393.2
400.5
402.7
401.3
397.4
397.9
403.2
LW
g/m2
159.2
139.8
173.4
220.1
221.5
199.2
201.9
171.4
225.9
336.3
375.6
387.0
384.6
374.7
129.4
131.0
100.0
100.5
98.8
109.1
375.0
374.0
137.9
171.0
338.1
355.4
349.6
341.8
312.0
299.7
210.9
219.7
258.4
224.2
256.9
261.9
g»*
244.4
256.8
227.2
177.9
176.8
196.3
196.9
225.0
175.0
64.2
16.2
12.0
16.1
19.9
271.7
263.8
300.5
299.0
304.0
290.6
28.8
22.1
266.5
230.7
64.9
50.3
50.8
58.8
91.5
93.5
189.6
183.0
142.9
173.2
141.0
141.2
Filtration
time
(minutes)
78
36.4
89
54
115
51
109
35
108
95
241
112
240
134
53
27
55
22
34
25
243
108
68
41
195
104
255
103
181
95
78
50.6
90
67
101
68
232
(continued)
-------
TABLE B-20. (continued)
Kind Kind
of of
fabric dust
C868B
865B
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
960 Sep.
Talc
862 B
C866B
C868B
865B
qg
m3/m2h
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
g/m2
385.5
400.3
398.4
397.5
403.9
401.1
405.2
395.1
391.3
402.7
397.9
401.8
396.1
413.6
396.3
394.3
411.4
403.7
397.8
401.4
398.3
394.6
401.7
401.5
391.8
397.4
406.1
398.4
386.4
383.0
382.7
358.9
400.9
379.3
LW
g/m2
258.1
267.2
335.8
325.0
382.4
380.4
381.6
377.1
193.1
229.0
179.4
200.3
228.1
192.3
369.3
371.8
214.2
205.6
339.9
342.3
343.9
340.3
330.7
328.6
240.8
208.0
286.3
264.2
252.4
237.1
236.1
214.3
319.1
317.4
LNK
g/nr
127.4
133.1
62.6
72.5
21.5
20.7
23.6
18.0
198.2
173.7
218.5
201.5
168.0
221.3
27.0
22.5
197.2
198.1
57.9
59.1
54.4
54.3
71.0
72.9
151.0
189.4
119.8
134.2
134.0
145.9
146.6
144.6
82.8
61.9
Filtration
time
(minute?)
89
67
146
88
161
104
137
100
75
59
61
56
62
47
150
98
98
52
124
102
130
92
129
90
69.6
41.4
86
46
75
40
73
41
87
57
(continued)
233
-------
TABLE B-20, (continued)
Kind Kind
of of
fabric dust
C890B
C892B
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
960 Sep.
Fly Ash
862B
C866B
C868B
865B
C890B
C892B
qg
m3/m2h
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
60
80
g/m2
376.9
375.8
382.3
351.0
409.4
363.1
379.2
385.5
370.3
393.0
372.1
394.2
402.9
372.1
402.2
387.3
378.3
385.2
384.1
372.9
403.0
400.0
399.9
392.6
411.0
397.9
403.3
400.1
397.2
397.5
396.4
394.8
391.2
399.2
LW
g/m2
365.7
352.6
362.1
330.2
244.5
148.6
93.6
119.8
179.6
142.4
356.9
379.7
182.3
178.7
353.4
322.4
333.6
335.7
309.5
279.9
106.7
86.6
153.8
129.1
86.0
121.8
113.8
147.4
205.4
206.4
347.0
377.0
358.4
377.0
LNK2
g/m2
11.2
23.2
20.2
20.8
164.9
214.5
285.6
265.7
190.7
250.6
15.2
14.5
220.6
193.4
48.8
64.9
44.7
49.5
74.6
93.0
296.3
313.4
246.1
263.5
325.0
276.1
289.5
252.7
191.8
191.1
49.4
17.8
32.8
22.2
Filtration
time
(minutes)
112
70
126
67.6
66
28
18.4
19
43.6
25
127.5
80
49
30
107
62
95
68
80
54
39.2
11
28
15
18,8
14.4
24
20
31
25
65
60
90
64
(continued)
234
-------
TABLE B-20. (continued)
Kind Kind
of of
fabric dust
852
853
190R
850B
802B
Q53-875
Q53-870
Q53-878
m3/m2h
60
80
60
80
60
80
60
80
60
80
60
80
60-
80
60
80
/°2
g/m2
408.8
409.6
—
404.3
412.6
401.2
412.0
403.5
397.5
398.4
400.5
394.0
399.0
401.6
404.4
LW
g/m2
116.4
64.0
--
78.3
146.8
374.4
394.4
98.2
91.2
301.3
327.7
302.7
330.0
119.0
132.0
LNK
g/m2
292.4
345.6
— — ,
326.0
265.8
26.8
17.6
305.3
306.3
97.1
72.8
91.3
69.0
282.6
272.4
Filtration
time
(minutes)
37
10.5
--
15
11
82
63
25
13
99
53
79
55
25
17
Note: All values are means from five measurement cycles.
235
-------
TABLE B-21. PARAMETERS OF POLISH FABRICS
Parameter Unit
Kind of
fiber
Fabric
weight g/m2
Thread
count in
10 cm: warp
fill
Tensile
strength:
warp kg/5cm
f i 1 1 kg/5cm
rv>
a? Elongation
during ten-
sion: warp %
fill %
Permeability
at P = 20 mm m3/m2.
minute
Weave
Finishing
BT-57
Cotton
429
122
118
121
110
25
20
13
2
7
—
ET-3
Poly-
ester
510±36
204±6
124±5
270
220
70
55
15-22
I
3~
One
side
scrap-
ing
Ef-4
Poly-
ester
450±31
180±5
126±5
240
370
75
56
12-18
j
3Z
—
Kind of fabric
ET-30
Poly-
ester
365±25
477±10
276±6
250
130
60
50
12-18
2
7
r
Stabi-
lizing,
washing
F-tor5
Poly-
ester
271±13
540±12
376±12
346
276
30
20
13
2
• " x L.
—
PT-15
Poly-
amide
272±14
564±12
360±11
300
200
60
40
5
3
\J *7
Stabi-
lizing
ST-7
Glass
307±16
215
215
250
250
6
6
14
3
7
T
Silicon
izing
or
graph-
iting
-------
APPENDIX C
237
-------
APPENDIX C-l
APPARATUS FOR AIR PERMEABILITY TESTING
Type ATL-2 /FF-12/
Producer: METEFEM - Budapest - Hungary
TECHNICAL DATA
Testing area
Measurement range of manometer
Measurement range of rotameter
(tolerance ±5 percent according
to extreme swing)
Max. capacity of fan
20,50, and 100 cmd
0 - 30 mm of water
30 - 100 mm of water
100 - 200 mm of water
10 - 50 liter/hr
40 - 200 liter/hr
150 - 750 liter/hr
600 - 3,000 liter/hr
2,500 - 15,000 liter/hr
8,000 liter/hr
238
-------
OPERATIONAL PRINCIPLE
The fabric sample is placed on two rings and after stretching is
fastened. The rings can be regulated and enable regulation of the fabric
2
sample size to 20, 50, and 100 cm . The ambient air is sucked through the
fabric by a suction nozzle. The air volume is measured by rotameters
supplied with individual needle valves. The pressure difference before and
behind the fabric sample, during the flow of a definite volume of air, is
measured by a manometer. The air permeability is defined as the volume of
air flowing through unit area of acclimatized flat textile material during
time unit, at a constant difference of pressure before and behind the sample,
32 32
(expressed as cm /m s or m /m min). For technical materials, the pressure
difference is assumed to be 20 mmH?0.
CALCULATION OF RESULTS
The air permeability measured by the ATL-2 apparatus is calculated from
the following formula:
Q = q/6f (m3/m2min)
where q = air volume measured by rotameter in 1/hr, and
2
f = examined area of sample in cm .
The measurement is made at various points of the examined fabric
(depending upon its uniformity). The number of measurements must obey the
condition that the relative random error does not exceed 5 percent. Permea-
bility of the testing fabric is the arithmetic mean of the measured perme-
abilities of the individual points. The relative random error of air
permeability should be calculated according to the equation:
ta
xn
where a = mean quadratic deviation of air flow velocity,
x = mean air flow velocity,
n = number of measurements, and
t = confidence coefficient at 95 percent probability and n-1
number of degrees of freedom read from the Student
t-distribution table.
239
-------
APPENDIX C-2
CENTRIFUGAL DUST CLASSIFIER - BAHCO
Producer: ETABLISSEMENTS NEU, Lille - France
PRINCIPLE OF OPERATION
The determination of dust grain size using the Bahco centrifugal dust
classifier is based on the following principle.
The dust is introduced into a spiral-shaped air current flowing towards
the center with suitable values of the tangential and radial velocity. It
is divided into two parts so a certain quantity of dust is accelerated by
the centrifugal force against the periphery of the whirl while the other
part of the dust is carried by the air current towards the center of the
whirl by means of the friction between the ai.r and the dust particles. The
Stokes' and Archimedes' laws can be applied.
240
-------
The sifting chamber, in which the separation takes place, is driven by an
electric motor operating at stable peripheral speed. Air is sucked into the
sifting space by the fan and goes through the slots. Due to the slots, the
air has rotational motion determined by the motion of the apparatus, so the
relative peripheral speed of the air amounts to zero. Thus, in the sifting
chamber there is only the radial velocity. The centrifugal force and the
friction between the air and the dust particles result in grains larger than
the limit being thrown out and collected on the ring. Smaller grains are
taken by the air stream.
The grain sizes are determined from the loss of dust mass after each
separation, with the mass being the residue collected after each previous
separation. The known different air flow velocities in the sifting space
determine, according to Stokes1 law, the limiting dynamic dust grain sizes
of the successive ranges.
PREPARATION OF THE SAMPLE
The sample has to be dried at a temperature below 105° C, but above the
temperature of ambient air, for 1 hr. Then it should be cooled in an exsic-
cator and left in contact with air for at least 24 hr. The sample will
reach thermodynamic equilibrium with the ambient air. The laboratory temper-
ature should not be lower than 10° C and not higher than 35° C, and the
relative air humdity should not be higher than 60 percent.
CALCULATION OF THE WEIGHT-PERCENTAGE OF PARTICLES IN INDIVIDUAL RANGES
The percentage, by particle weight, can be determined using the follow-
ing formula:
ki =
m
100
where m
mi
m.
= the weight of dust introduced each time to the
feeder, in grams,
= the weight of dust collected after each separation,
in grams, and
= the weight of the analytical sample, in grams.
241
-------
Dynamic dust particle sizes a., which are the upper grain size limits
in individual ranges "i", correspond to the k.. The dynamic grain sizes of
dust a., expressed in m, are determined from the following equation:
ai = aoi
'Vr"
where a . = dynamic dust particle size, in pm, corresponding to
particle density p = 1 g/cm , and
3
P = density of tested dust, in g/cm .
242
-------
APPENDIX C-3
ALPINE MULTI - PLEX
FABOR - ZICKZACKSICHTER 100 MZR
Producer: ALPINE Aktiengesellschaft Maschinenfabrik und Eisengiesserei,
Augsburg - West Germany
TECHNICAL DATA
Separator: Rotation
Air flow
Blower: Static negative pressure
Air flow
Alpine Filter: Filtration area
Feeder: Maximum capacity (ground limestone)
2,400 - 20,000 rpm
15 - 53 Sm3/hr
1,500 - 1,600 mmH20
100 m3/hr
1 m
10 kg/hr
243
-------
APPLICATION
Determination of particle size distribution of samples above 50
grams,
Laboratory separation for individual grain fractions, capacity of
a few kilograms,
Industrial separation into two fractions, with a capacity of a few
kg/hour, depending upon the kind of material.
Concerning ground limestone, the range of separation is 1-75 microns.
The range of separation can be regulated steplessly.
PRINCIPLE OF OPERATION
The operation of Alpine is based on the centrifugal force principle.
The material is fed into a separating zone by a screw feeder. The rotor
blades, placed radially on the rotor surface, increase the velocity of the
material up to the circumferential velocity of the rotor. Thus the material
is being suspended in the air stream entering the separating zone from two
sides. Then the dust-air mixture is introduced under negative pressure to
zigzag passages where it is separated. The separating air and the fines
enter the rotor center, travel through the outlet duct, and are delivered to
the cyclone. Here the fines are separated from the air and they are collected
in the fines' glass hopper. Under the centrifugal force the tailings are
thrown from zigzag blade passages to the outside circumference of the separat-
ing zone and they leave the separating zone through the slot on the separat-
ing zone circumference, entering the tailings glass hopper.
The necessary air volume is supplied by a high-pressure blower and is
indicated by a rotameter.
The range of separation is regulated by two independent factors: the
number of revolutions and the volume of air. The range of separation can be
adjusted to 1-70 urn. The calibration curve for limestone of specific gravity
2.6 - 2.7 g/cm was presented in the servicing instructions. The range of
separation dy in urn for a definite number of revolutions can be read out
from the diagram. The range of separation is obtained for the volume of air
calculated from the following formula:
244
-------
V = 55 -
1,000
where n = number of revolutions of the separator.
For the materials that have specific gravity different than standard
limestone, the range of separation can be calculated based on the following
formula:
d-, = d
1 *yl
where d, = the range of separation of material, in urn,
d = the range of separation of limestone, in urn,
3
yn = specific gravity of testing material, in g/cm , and
3
Y = specific gravity of limestone, in g/cm .
For the calculated range of separation of testing material, the number
of revolutions is read out from the calibrating curve and then the volume of
air V is calculated.
245
-------
APPENDIX C-4
TENSILE TESTING MACHINE TYPE FMGw 500
Producer: VEB Thuringer Industriewerk, Ranenstein - DDR
TECHNICAL DATA
20 - 250 mm/min
200,300,360,400,500 mm
0 - 200 mm
500 kPa
0 - 100 kPa
0 - 250 kPa
0 - 500 kPa
The apparatus is equipped with a recorder.
Velocity of strokes
Active length of sample
Elongation
Maximum force
Measurement ranges
246
-------
APPLICATION
The testing of tension and elongation of fabrics—sailcloth, transmis-
sion belts, board, etc.
PRINCIPLE OF OPERATION
The testing of tensile strength is carried out in the following manner.
The fabric sample is stretched between two alligator clips. The clips are
placed in parallel one over the other. Then the sample is extended by
continuous forces until rupture. Simultaneously the elongation, i.e. the
increase of length between clips during the sample extension, is determined.
According to Polish standards the testing is accomplished with the fabric
samples cut out along the fill and warp. Sample sizes: width greater than
about 50 ±5 mm; length greater by about 150 mm than the attached clip spacing.
The clip spacing of the tensile testing machine should be 200 mm for fabrics
with elongation at rupture below 150 percent and 100 mm for fabrics with
elongation of rupture greater than 150 percent. The frequency of strokes of
the lower clip is determined by the time between starting the testing to the
moment of rupture which should be 30 ±10 seconds.
The tensile strength criterion is the maximum force at which the rupture
appears, with the exact elongation read out from the elongation scale (or
j
from the recorder).
247
-------
APPENDIX D
248
-------
APPENDIX D
GLOSSARY OF TERMS
Because of the different terms used in the literature concerning dust
filtration through filtration media and because of the many parameters,
stages, etc. that are characteristic of dust filtration processes, we list
the terms and their definitions as used in this project. The proposed terms
have physical meaning according to the processes and phenomena occurring
during the dust filtration process, which is quite different from other
filtration processes.
Aerosol - A 2-phase system, composed of a gas dispersion phase and a
solid dispersed phase, which under certain conditions can be
treated as stable or quasi-stable (dry filtration).
Filtration - Removal of solid particles from an aerosol stream by depo-
sition in or on the structure of a porous medium.
Air Filtration - Filtration of atmospheric aerosols.
Dust Filtration - Filtration of industrial aerosols.
Dust Filtration Type I - The initial phase of the complete dust filtration
process when the fabric first begins operation as a filter
medium. This phase ends when the pressure drop reaches a
predetermi ned 1 eve 1.
Dust Filtration Type II - The second phase continues until the fabric is
fully filled with dust. This phase ends when the structure
reaches a steady state.
Dust Filtration Type III - This phase occurs when a stable level of filling
of the fabric, by dust, has been reached and when the pres-
sure drop returns to a constant level after regeneration.
This is a typical process for industrial dust collectors.
Gas Loading of Filtration Area - Mean calculated value of gas quantity, in
cubic meters, passing through a square meter of filtration
medium per hour (air-to-cloth [A/C] ratio).
Dust Loading of Filtration Area - Mean calculated value of dust quantity, in
grams, deposited on a square meter of filtration medium per hour,
249
-------
Filtration Velocity - The actual local velocity of an aerosol, in meters per
second, passing through a filter medium (measured in true
conditions).
Filled With Dust Structure - The areal mass density of the dirty filter
including all dust retained after regeneration but without
dust cake in (g/m ).
Fully Filled With Dust Structure - Filled with dust structure after reaching
steady-state operation.
Covered With Dust Structure - The areal mass density of dust accumulated on
the filter including the dust cake prior to regeneration
(g/nT).
Dust Cake - The porous dust layer built up on the fabric surface during dust
filtration. Its characteristics depend on the kind of fabric,
the kind of dust, and the parameters of the process.
Free Area Effect - Decrease of dust filtration efficiency caused by inter-
yarn free area viewed in plane of fabric.
Basket Effect - Decrease of dust filtration efficiency caused by interyarn
free area viewed askew to plane of fabric.
250
-------
APPENDIX E
251
-------
APPENDIX E
NOMENCLATURE
b = 1.) thickness of the porous layer; 2.)a coefficient
c. = initial concentration
c = outlet concentration
o
d = diameter of the warp yarn
d = diameter of the fill yarn
W
dcn = HMD (mass median diameter)
B = ambient pressure
E = efficiency
ED = bag efficiency
D
Er-n = fractional efficiency
rK
Eu = hopper efficiency
n
Ey = total efficiency
EM = emission
FA = free area
GB = weight of dust from bag after regeneration
G = weight of dust fed into the testing chamber or into the hopper of
testing chamber
GH = weight of dust in hopper before regeneration cycle
GN = dust filling of bag
G = weight of dust collected on the control filter or weight of dust
in cleaned gases
Gn = weight of dust removed during regeneration from hopper
G = weight of dust collected on the fabric
K1'K1 = resistance coefficient of Darcy equation for pure fabric
K,, = specific dust-fabric resistance
L = quantity of dust per unit area of filtration fabric
LN = dust filling of structure
L = full dust filling of structure
252
-------
L = dust covering of structure
L = area! mass density of the dust cake
LW = quantity of dust on square unit of dust cake
m.j = weight of dust on i-th impactor stage
mQ = weight percent of definite dust fraction leaving the measurement
chamber
mw = weight percent of definite dust fraction introduced to measurement
chamber
nQ = number of warp threads in 10 cm
n = number of fill threads in 10 cm
W
AP = pressure drop
AP. = specific hydraulic resistance of porous layer
APK = covered with dust fabric resistance (the before regeneration pressure
drop)
AP.. = filled with dust fabric resistance
N
APMi/ = fully filled with dust fabric resistance
NN
AP = clean fabric resistance
o
APW = dust cake resistance
Q = gas flow intensity through impactor
q = gas loading of filtration area (A/C ratio)
q = dust loading of filtration area
SE = effective drag
SD = susceptibility for regeneration
K
t = time
tr = filtration time
tD = regeneration time
K
V.n = rate of increase of filtration resistance
AP
e = porosity
(l-e)/e = porosity function
a = standard deviation
a, b,
b .b-, = coefficients
'
253
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-79-087
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Test of Fabric Filtration Materials
5. REPORT DATE
March 1979
6. PERFORMING ORGANIZATION CODE
7 AUTHORIS) Jan R Koscianowski, Lidia Koscianowska,
and Maria Szablewicz
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Institute of Industry of Cement Building Materials
45-641 Opole
21 Oswiecimska Str. , POLAND
10. PROGRAM ELEMENT NO.
EHE624; ROAP 21ADJ-094
11. CONTRACT/GRANT NO.
Public Law 480
Project P-5-533-4
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
Project Final; 6/73 - 12/78
15. SUPPLEMENTARY NOTES IERL-RTP project officer is James
2925.EPA-600/7-78-056 is an earlier related report.
14. SPONSORING AGENCY CODE
EPA/600/13
H. Turner, MD-61, 919/541-
16. ABSTRACT-
The report describes pilot scale and laboratory tests of U.S. and Polish
woven baghouse fabrics. Cotton, polyester, aramid, and glass fabrics were tested
using cement, flyash, coal, and talc dusts at loadings of about 10 g/cu m, filtration
velocities of 60 and 80 cu m/sq m, and ambient temperature and humidity. General
conclusions reached were: (1) air permeability is a poor predictor of fabric perfor-
mance, (2) fabric construction parameters do not correlate well with the resistance
coefficient for fabrics Kl, (3) a critical value of pressure drop exists above which
fissures are formed in the dust cake, (4), there is a maximum in the efficiency
versus air-to-cloth-ratio curve which is related to fissure formation, and (5) clean-
ing properties of the fabric depend primarily on its chemical C9mposition, the dust
being filtered, and the superficial structure of the dust cake and fabric (they do not
depend on air-to-cloth ratio).
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Pollution
Air Filters
Woven Fabrics
Caking
Cotton Fabrics
Polyester Fibers
Glass Fibers
Cements
Fly Ash
Coal Dust
Talc
Pollution Control
Stationary Sources
Baghouses
Fabric Filters
Poland
Aramid
13B
13K
HE
07A,13H
11B
13C
2 IB
21D
08G
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
254
------- |