United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S9-82-005c July 1983
Project Summary
Third Symposium on the
Transfer and Utilization of
Particulate Control Technology:
Volume III. Particulate
Control Devices
F. P. Venditti, J. A. Armstrong, and M. Durham
Summarized herein is Volume III of
the four volumes of proceedings of the
Third Symposium on the Transfer and
Utilization of Paniculate Control Tech-
nology held in Orlando, FL, March 9-12,
1981. Volume III papers discuss partic-
ulate control devices other than elec-
trostatic precipitators, and describe
applications and types of scrubbers.
Volumes I, II, and IV are described in
three separate project summaries.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory. Research Triangle
Park. NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
The papers in these four volumes of
proceedings were presented at the Third
Symposium on the Transfer and Utiliza-
tion of Particulate Control Technology in
Orlando, FL, March 9-12, 1981, spon-
sored by the Particulate Technology
Branch of EPA's Industrial Environmental
Research Laboratory at Research Triangle
Park, NC.
The symposium brought together re-
searchers, manufacturers, users, govern-
ment agencies, educators, and students
to discuss new technology and provided
an effective means for the transfer of this
technology out of the laboratories and
into the hands of the users.
The three major categories of control
technologies—electrostatic precipitators
(ESPs), scrubbers, and fabric filters—were
the major concern of the symposium.
These technologies were discussed from
the perspectives of economics, new tech-
nical advancements in science and engi-
neering, and applications. Several papers
dealt with combinations of devices and
technologies, leading to a concept of
using a systems approach to particulate
control, rather than device control. Addi-
tional topic areas included novel control
devices, high-temperature/high-pres-
sure applications, fugitive emissions, and
measurement techniques.
The symposium was conducted as a
series of parallel sessions, each contain-
ing four to six related papers. The sessions
were scheduled to avoid conflict due to
simultaneous sessions dealing with the
same topic. Each series of related ses-
sions represented a thread of technology.
These parallel threads, extending over
the total period of the symposium, pro-
vided a highly integrated approach to the
total subject of particulate control tech-
nology, with strands of specialized tech-
nologies. These strands of specialized
technologies, or perspectives, provided
the basis for the division of the papers
into four volumes, each volume contain-
ing a set of related session topics so as to
provide easy access to a unified technol-
ogy area.
Volume III Papers
Volume III, summarized here, is a
collection of papers describing particulate
control devices other than ESPs. The
largest section in Volume III deals with
fabric filters. Several papers dealt with
the electrostatic enhancement of fabric
filters both from a theoretical and practical
operating perspective. Measurement and
diagnostics of filter capabilities with
regard to flyash size distribution were
widely treated, as were the more conven-
tional problems dealing with pressure
drop and cleaning of filters. Several
papers were devoted to granular beds
with emphasis on moving beds. Collection
efficiencies and electrostatic augmenta-
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tion of mechanical collectors were inter-
spersed with troubleshooting and design
and fabrication of these devices. A session
on novel devices treated magnetic separa-
tion phenomena, electrostatically en-
hanced wet scrubber applications, sin-
tered metal filters, fiber bed filters, and a
wet-wall ESP.
Another small section deals with me-
chanical collectors (including electrosta-
tically augmented devices). Several novel
devices are described in yet another
section of Volume III. These devices
include magnetic separators for use in
the iron and steel industry, electrostati-
cally augmented filter devices, sintered
metal filters, special Venturis, and fiber
bed devices.
Section A—Scrubbers
The Calvert Scrubber
S. Calvert, Air Pollution Technology, Inc.
The Calvert Scrubber is a very energy-
efficient fine-particle scrubber and is
especially well suited to utilities applica-
tions because it can meet both particulate
and SOz removal requirements in a
single-control device. Other potential
applications include metallurgical indus-
tries, chemical industries, and any other
industry where fine-particle scrubbers
are used.
Pilot scrubbers of up to 3,000 cfm
capacity have been built and tested. Exper-
imental data for fine-particle collection
and SO2 removal are presented. Collection
efficiency data are presented as a function
of particle aerodynamic diameter. The
50% cut diameter is presented as a
function of pressure drop and energy
input to the scrubber. Performance is
compared to conventional venturi scrub-
bers and other fine particle scrubbers.
Flux Force/Condensation
Scrubber System for
Collection of Fine Particulate
Emissions from an Iron
Melting Cupola
S. Calvert, Air Pollution Technology. Inc.
Aflux force/condensation (F/C) scrub-
ber was designed, built, and operated by
Air Pollution Technology, Inc., to control
particulate emissions from an iron and
steel melting cupola. The cupola melt rate
was approximately 14,000 kg/hr (15
tons/hr), with an exhaust gas flow rate of
8.5 kg/s (14,000 dscfm). The major
scrubber system components included an
afterburner, spray saturator, condenser,
and scrubber. A cooling tower rejected
heat from the scrubber system.
Performance data were obtained by
sampling for particle size distribution and
concentration at several locations. Experi-
mental performance data were compared
with theoretical predictions of particle
collection as a function of particle size.
The F/C scrubber system was capable of
meeting the emission limit with a power
input of only 65% of the power consump-
tion required for a conventional high
energy scrubber.
Demonstration of High-Intensity
Ionizer-Enhanced Venturi
Scrubber on a Magnesium
Recovery Furnace Fume
Emissions
A. Prem, Pollution Systems
A 33,960 mVhr (20,000 acfm) perma-
nent demonstration system, consisting of
the Air Pollution System's High Intensity
Ionizer (HII) and a variable-throat venturi
scrubber, has been installed on a magne-
sium recovery furnace at Teledyne Wah
Chang Albany, Albany, OR. The particu-
late emission from this source is predomi-
nantly submicron in nature. Fairly high
stable electric fields of 10-12 kV/cm have
been successfully maintained in the HII.
Comparing the measured charge/mass,
and the calculated charge/mass based
on the measured particulate size distribu-
tion at the outlet of the scrubber, the HII
appears to be imparting fairly high charge
to the incoming particulate. Preliminary
performance test results indicate higher
performance of the venturi scrubber when
the HII is energized for all the venturi
pressure drops tested. The penetration
reduction due to HII increased as the
venturi pressure drop was increased, and
as the particle size decreased.
A New Entry in the High
Efficiency Scrubber Field
L. C. Hard/son, Air Resources, Inc.
The use of venturi flooded-disk, and
various orifice-type scrubbers for wet
collection of fine particles at high energy
levels and high levels of particulate
collection efficiency is well known. In
general, these scrubbers may be charac-
terized as roughly equivalent in perform-
ance level, and various models are com-
petitive only with respect to price and
mechanical considerations and ease of
maintenance or operation.
The MVS (Modular Venturi Scrubbe
the latest entry into this competitive fie
has several advantages in size, cost, a
simplicity over more conventional d
signs. This paper describes the desii
and operation of the MVS units.
Performance of Particulate
Scrubbers as Influenced by
Gas/Liquid Contactor
Design and by Dust Flocculatio
K. T. Semrau, SRI International
Comparative performance studies
gas/liquid contactors, using standardizi
test dusts, included several venturi a
rangements, orifices, a sparger tub
sparger nozzles, and fiber packs. Over
range of operating variables, the colle
tion efficiencies of the units were cor
pared as functions of the effective f rictk
loss. Test dust was used in both flocc
lated and deflocculated states. With
given dust, the different contactors gene
ally gave about the same efficiency at
given effective friction loss, but signif ica
differences in performance in sorr
ranges of operating variables appear*
with certain contactors, the fiber-packe
contactors consistently giving highi
efficiencies. Flocculated dust gave highi
collection efficiencies than did deflocci
lated dust unless the contactor desic
permitted redispersal of the dust befoi
contact with the liquid.
Investigation of Venturi
Scrubber Efficiency and
Pressure Drop
R. Parker, Air Pollution Technology, Inc
The venturi scrubber performanc
model (EPA-600/2-77-172; NTIS P
271515) gives good results when used
predict the performance of industri
scrubbers. However, no detailed pan
metric evaluation of this model has bee
conducted to properly predict ventu
scrubber performance in non-conver
tional environments, such as high pros
sure gas streams. Pilot plant data on a 7.
cm (3 in.) throat diameter venturi scrubbc
are presented. Flow rates from 10-2
mVmin and liquid-to-gas ratios from 11
3 l/m3 were used. Throat and diffuse
lengths were also varied. Throat velocitie
from 40 to 70 m/s and pressure drop
from 1 to 5 kPa were measured. Exper
mental data generally showed highe
penetrations than predicted, especial!
for particles larger than 1 or 2 fjr
aerodynamic diameter.
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Scrubber Technology and the
Interaction of a Unique
Structure as Mist Eliminator
G. C. Pedersen, KIMRE, Inc.
The role of this unique patented struc-
ture as a mist eliminator for other scrub-
bing devices is considered. The range of
physical properties yields new capabil-
ities in system. This approach is being
used with good success on four continents
and is a standard for many U.S. scrubber
manufacturers.
No vel A nnular Venturi Scrubber
Design Reduces Waste
Discharge Problems
H. P. Beutner, Interel Corp.
Characteristics of a new type annular
venturi scrubber system, which was
developed by L. Leisegang of West
Germany, are presented.
The scrubber has internal circulation of
the scrubbing liquid and allows solids
buildup in the liquid to 20% or more. The
liquid spray is generated without use of
nozzles by contact of the gas with the
liquid surface. Solids are discharged
either as concentrated slurry or as sludge
by means of a scraper.
The annular venturi scrubber achieves
highest energy efficiency at any pressure
drop from 1 to 80 in. WG. It can be
operated as variable venturi by regulating
the water level. Fractional particle re-
moval efficiencies as a function of pres-
sure drop are shown. Examples of installa-
tions on product dryers, incinerators,
foundry, and steel mill operations are
presented.
Consideration of the Pertinent
Design and Operating
Characteristics Essential for
Optimization of Venturi
Scrubber Performance
H. S. Oglesby. NCASI
The use of medium- to high-energy
venturi scrubbers in the pulp and paper
industry has increased substantially over
the past 8 to 10 years. Accompanying this
increased use is a wider spectrum of
applications and a demand for a sustained
higher level of performance to meet the
current and emerging regulatory require-
ments. Accordingly, there is a need to
review the critical factors affecting per-
formance relative to optimization, process
compatibility, and minimizing the energy
requirements. In this respect, it is essen-
tial that considerations be given to the
pertinent design and operation param-
eters in assessing performance. This
paper addresses these issues and a
methodology for troubleshooting scrubber
performance.
Application of Scrubbers for
Particulate Control of
Industrial Boilers
M. Borenstein, Neptune Airpol
Cyclone dust collectors, formerly used
to control dust on bark boilers, are no
longer adequate. More stringent require-
ments call for higher efficiency collection,
and scrubbers have been successful in
meeting the codes. This paper explores
the operation parameters, operating ex-
perience, and test results of scrubbers on
coal-, oil-, and wood-fired boilers, particu-
larly in the pulp and paper industry. It also
reviews the power requirements, main-
tenance schedules, and instrumentation
required for successful operation of the
scrubber.
Application of High Energy
Venturi Scrubbers to
Sewage Incineration
F. X. Reardon, Metcalf & Eddy. Inc.
The most critical components required
for the upgrading of the four, flash drying,
sludge incinerators in 1968 during the
formulation of EPA's New Source Per-
formance Standards, and the Allegheny
County Health Department, Rules and
Regulations, Article XVII, Smoke and Air,
were the incinerator scrubbers.
Responding to contract requirements
for venturi scrubbers operating with a
pressure drop of 20 to 25 in. WG, flooded
disk scrubbers were installed. The engi-
neering application of the scrubbers to
the furnaces, problems encountered and
resolved during the break-in period, the
test results, and the continuing operating
history are presented.
An Incinerator Scrubber That
Works: A Case Study
C. Menoher. ZURN Industries
A midwestern chemical company has
recently started up a medium energy
scrubber on an industrial trash burning
incinerator. Compliance testing verified
an outlet particulate loading of less than
the guaranteed 0.15 lb/1.000 Ib of dry
gas. This level of performance was
achieved with 30 in. .W.C. of venturi
pressure drop, with final subcooling to
remove volatiles and condensibles. This
system was purchased because of the
horsepower savings when compared to
the "conventional" venturi scrubber that
asks for 60 in. W.C. or more of pressure
drop. The savings will pay for the scrubber
system in 4 years.
Evaluation of Entrained Liquor
Contribution to Total Mass
Emissions Downstream of a
Wet Scrubber
W. D. Balfour, Radian Corp.
As flue gas passes through a wet
scrubber, both SOzand particulate matter
can be removed. The scrubber can, how-
ever, contribute mass through entrain-
ment of scrubber liquor high in suspended
and/or dissolved solids. The contribution
of mass by a variety of scrubbing systems
has been calculated using the concept of
a chemical element balance.
Particulate compositions into and out
of the scrubber were obtained from
chemical analyses (ion chromatography
and inductively coupled argon plasma
emission spectroscopy) of total particulate
catches. Scrubber liquor composition was
obtained by similar analyses of liquor
samples collected during the particulate
sampling. A multiple variable regression
analysis was performed on the set of
equations (for each chemical species).
Results for a limestone tandem venturi
scrubber indicate that primary particle
penetration is very small (approximately
0.10%). The scrubber liquor, however,
contributes 40% of the total mass emis-
sions. Additionally, 90% of the sulfate
aerosol emissions are generated by the
scrubber.
Section B—Fabric Filters
A Dual-Beam Backscatter
Beta-Particle Gauge for
Measuring the Dust Cake
Thickness on Operating Bag
Filters Independent of Position
R. P. Gardner.
North Carolina State University
A dual-beam backscatter beta-particle
gauge for measuring the filter cake
thickness on operating bag filters has
been designed, and a prototype device
has been constructed and tested. The
device uses two beta-particle sources
(Kr-85 and Sr-90) with an end-windowGM
counter so that the measurement of filter
cake thickness is essentially independent
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of the position of the bag in relation to the
gauge. A plastic rotating shutter shield
operated by a small electric motor pro-
vides signals alternately from each
source. The shutter position is sensed by
an infrared detector, and the response to
each source is appropriately routed to
separate counters. The low-energy Kr-85
source provides a backscatter response
that depends only on filter position, while
the high-energy Sr-90 source provides a
backscatter response that depends on
both filter position and filter cake thick-
ness. The real-time simultaneous solution
of appropriate models for the two re-
sponses with a microcomputer gives the
filter cake thickness, an estimate of the
standard error of filter cakethicknessdueto
statistical counting rate fluctuations, and
the filter position for each set of re-
sponses. Laboratory and pilot plant results
indicate that the gauge is accurate and
will be useful for control purposes.
Diagnosing Filter Fabric
Capabilities with Light
Scattering and Nuclei
Detecting Instrumentation
R. Dennis, GCA/Technology Division
Fabric penetration characteristics
based on long-term averaging periods (on
the order of hours) reveal neither the
probable range of outlet concentrations
and size properties, nor short-term ef-
fects, that can play important roles in the
selection of fabric and collector design
and operating parameters. Laboratory
tests at ambient temperatures using a
single-particle light-scattering device and
a condensation nuclei counter to augment
mass and size determinations by filter
and cascade impactor measurements,
respectively, permitted short-term resolu-
tion (on the order of seconds) of changes
in effluent properties. Data are presented
relating particulate emission measure-
ments to variations in inlet concentration,
fabric structure, frequency and method of
cleaning, and filtration velocity. The pres-
ence of fabric defects or the impact of
dust cake disturbance is traced over
typical filtration cycles for various aero-
sols with woven glass, cotton, and Dacron
fabrics.
Acid Dewpoint Corrosion in
Particulate Control Equipment
T. E. Mappes. PEDCo Environmental, Inc.
This paper described the impact of
corrosion on particulate control device
performance and reliability. Many of the
corrosion problems observed during this
study were the result of flue gas tempera-
tures falling below the sulfuric acid
dewpoint. During the study, 11 fabric
filters and 1 ESP that suffered from acid
dewpoint corrosion were investigated.
The study also includes comments on
acid dewpoint corrosion made by design
engineers at 5 fabric filter manufacturers
and 2 ESP manufacturers. Results of this
study indicate that acid dewpoint corro-
sion is a serious problem in many particu-
late control devices and can destroy
expensive particulate control equipment
after only a few years of service. This
paper discusses how many corrosion
problems can be prevented or amelior-
ated.
Second Generation of
Emissions Control System for
Coke Ovens
J. D. Patton, MikroPul Corp. USF
The information presented in this paper
is directed to top management, environ-
mental directors, and technical personnel
interested in the latest technology for
controlling hot gases and more positive
capture of particulate during the operation
of pushing hot coke on coke ovens.
There are 6 points of interest: (1) more
positive capture of emissions, (2) simple
modular design, (3) erection during opera-
tions, (4) reliability close to 100%, (5)
unique baghouse filter system incorpo-
rated inside coke side shed emissions
control structure, and (6) residue recycling
(optional).
In the past 5 years, the coke side sheds
have been set aside in favor of other
control systems. Some of these systems,
such as traveling hoods and hot cars,
have not worked out as expected. Some
properly built coke side sheds have ac-
cumulated a number of successful years
of operation with a minimum of mainte-
nance.
The intent of this paper is to inform
interested parties of the latest in capture
control of emissions, and a unique in-
house bag type filter system.
Effects of Flyash Size
Distribution on the
Performance of a Fiberglass
Filter
W. T. Frazier, University of Tennessee
The purpose of this study was to inves-
tigate the performance of a fabric filter
under various operating conditions at a
low filtration velocity. The detailed proje
objectives were: (1) evaluate the perforn
ance of a fabric filter when exposed •
f lyash with mass mean diameters (MMD
of 3.5-13 yum (performance—evaluate
on fully conditioned fiberglass fabrics-
was measured by comparing fabric filti
pressure drop (delta P) and filter efficieni
as a function of fabric loading); (2) mea:
ure the effects of reverse air ratio (cleai
ing intensity) and inlet dust loading c
filter performance; and (3) incorpora
the collected data into a format compatib
with the EPA's Filtration Model for Co
Fly Ash with Glass Fabrics (EPA-600/:
77-084, NTIS PB 276489).
Predictive equations have been deve
oped to allow the user to incorporate si;
distribution effects into the EPAfiltratic
model. Graphs are also included showir
the experimentally measured relatioi
ships between particle penetration, n
sidual pressure drop, and coefficient
resistivity for the 5 flyash size distribi
tions that were tested.
Fundamental Study of a Fabric
Filter with a Corona Precharge
K. linoya, Kyoto University
The effects of a corona precharger o
the performance of a fabric filter hav
been studied experimentally in air wil
controlled humidity. Test dusts, fine ca
cium carbonate, and flyash, are pr<
charged and then ducted to a test fabri
Charged dust often reduces the pressur
loss across the filter at low filtratio
velocity and low relative humidity. On th
other hand, the collection efficiency of
fabric filter can usually be improved t
using a corona precharger.
Economic Evaluation Factors it
Bid Evaluations—A Sensitivity
Analysis
J. G. Musgrove, Bechtel Power Corp.
The trend to evaluate major utilii
equipment bids on life cycle costs rath<
than just on capital costs has increase
due to an awareness of the costs i
equipment maintenance and of borrowir
money. The rapidly changing econom
climate and changes in interest rate
affect the utility's economic evaluatic
factors.
An analysis has been conducted 1
determine the extent to which changes
the basic economic factors (interest rat
rate of return on investment, and plai
life) alter the economic evaluation facto
(fuel charge, demand charge, and dra
4
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loss penalty) used in competitive bid
evaluations. This analysis determines to
what extent these changes alter the
outcome of recent budgetary studies
comparing baghouses and cold-side
ESPs. They have been analyzed to deter-
mine the sensitivity of the equipment
selection to the economic factors em-
ployed.
Flyash Re-Entrainment in a
Baghouse— What Does It Cost?
J. Musgrove, Bechtel Power Corp.
The re-entrainment of flyash from the
hoppers of utility baghouses is considered
by baghouse suppliers to be inconsequen-
tial. A concern about the cost of re-
entrainment in a baghouse designed for a
550 MW utility generating station led to
an analysis of its costs. The analysis
hypothesizes the impact on baghouse
operation that would be caused by re-
entrainment and estimates its present
worth cost as a function of draft loss
across the baghouse. An estimate is also
made for the cost of conducting a scale-
model test program to determine the
actual degree of re-entrainment. The
analysis then suggests a method of deter-
mining the component costs of imple-
menting corrections to reduce re-entrain-
ment. From the costs of correcting re-
entrainment, curves of equal cost are
presented to suggest when re-entrain-
ment should be determined and corrected
and when it should be ignored.
Why Perform Model Study of
Fabric Filter Collector?
W. Langan, Buell Envirotech Corp.
The industry historically has modeled
ESPs to achieve good gas flow distribution
in the field unit. Standards for ESPs are
well developed and field experience has
proven such modeling is important to
achieve high collection efficiency for this
paniculate collection equipment.
This paper presents results of the
impact of a model study for several major
utility fabric filter facilities. These include:
TVA's Shawnee Units 1-10, Arizona
Public Service's Four Corners Units,
Plains Electric, and Baltimore Gas and
Electric's Crane Units.
Based on these model study experi-
ences, this paper presents data on: (1)
what hardware design parameters the
model study should impact, and (2) how
model study standards should ensure
successful operation of the field unit.
Experiences of a Small
Insulation Manufacturer in
Maintaining Compliance with
Air Pollution Control Regulations
R. L Hawk. PEDCo Environmental. Inc.
This paper describes the experiences of
a typical rockwool insulation manufac-
turer in the operation and maintenance of
air pollution abatement equipment re-
quired to comply with state and local air
pollution regulations. The paper discusses
in detail the effect of process variables,
equipment design deficiencies, and oper-
ation and maintenance problems on
achieving continuous compliance. It also
describes the special problems that the
small industrial source encounters in the
permitting process as a result of the
interaction required with regulatory
agencies and the manufacturing of air
pollution control equipment.
Advanced Fabric Filter
Technology for Difficult
Particulate Emissions
H. P. Beutner, Interel Corp.
The paper discusses fabric filter tech-
nology developed by H. Luhr of West
Germany specifically for control of diffi-
cult submicronemissionsfrom metallurg-
ical furnaces, arc furnaces, and glass and
brick kilns.
The baghouse uses a dust conditioning
drum, located in the hopper in place of a
screw conveyor, to pretreat the gas enter-
ing the baghouse with dust returned from
the bags. This approach reduces the bag-
house pressure drop and required fre-
quency of bag cleaning. The drum also
can hold additives in the baghouse for
removal of gaseous components, such as
HCI, HF, and S03. The baghouse utilizes
horizontally mounted, flat Twin-Bags and
either low pressure reverse-air or pulse-
jet cleaning.
Another element of the Luhr technology
is an air-to-gas heat exchanger that cools
high temperature exhaust gases to the
temperature acceptable in the baghouse.
The gas cooler, equipped with an auto-
matic cleaning mechanism, can be de-
signed as an integral part of the baghouse
and dust conditioning system.
Development of Guidelines for
Optimum Baghouse Fluid
Dynamic System Design
D. Eskinazi, Dynatech R&D Co.
One aspect of baghouse technology
which is of major importance in mini-
mizing the size, cost, and operating
pressure drop is ductwork designs which
achieve uniform gas and dust distribution.
A recently completed modeling program
focuses on developing design guidelines
concerning the optimization of fluid me-
chanic performance of baghouses. Tasks
include evaluation of current technology
regarding baghouse systems, formulation
of the appropriate modeling techniques
for analysis of flow of dust-laden gas
through the collector system, and exten-
sive experimental analysis of fabric filter
duct system designs. A matrix of geo-
metric configurations and operating con-
ditions was experimentally investigated
to establish the characteristics of an
optimum system, to identify the fluid
mechanic integrity of current designs,
and to validate the development of new
ideas and designs. This analysis shows
that the fluid mechanic design of fabric
filter systems can be improved signifi-
cantly.
Theoretical Aspects of Pressure
Drop Reduction in a Fabric
Filter with Charged Particles
T. Chiang. Buell Envirotech Corp.
Various and frequently disputed me-
chanisms have been presented in the
past to explain the reduced pressure drop
observed in a conventional fabric filter
augmented with particle precharging.
Such mechanisms involve dendrite for-
mations, polarizations, surface collec-
tions, and electric contact potentials. This
paper presents yet another mechanism
due to asymmetrical dust distribution.
Artificial step and bell-shape distributions
are modeled to show the reduction of pres-
sure drop without the assumption of a
more porous cake. Laboratory experi-
ments with metallic screens are used to
verify the proposed mechanism. Funda-
mental behavior of charged aerosols,
either in a self space-charge field or an
externally applied field, is discussed to
further support the theory.
Experimental Correlation of
Dust Cake Porosity, Air-to-Cloth
Ratio, and Particle-Size
Distributions
T. Chiang, Buell Envirotech Corp.
Experimental values of the mean spe-
cific resistanee coefficients obtained from
a full-scale utility baghouse and a slip-
stream 16-bag (30 x 1 ft dia) R&D pilot
baghouse were used to obtain the cake
porosities using the Carman-Kozeny
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equation. Functional relationships be-
tween the calculated porosity and the
volume-to-surface mean diameter of the
particles could not be found. However, a
log-log plot of the porosity vs. the particle
Reynolds number indicated a functional
dependence of minus two-thirds power to
exist. Utilization of this experimental
functional dependence provides us more
confidence to design baghouses for new
applications.
Model for Dust Penetration
Through a Pulse-Jet Fabric Filter
D. Leith. Harvard University
No comprehensive model is available to
interpret or predict dust penetration
through a pulse-jet cleaned fabric filter.
This paper presents a model which con-
siders penetration straight through the
filter and penetration by seepage. Many
studies have been devoted to penetration
by the straight-through process; however,
a comparison of data from the literature
with the present model indicates that
seepage and not straight-through pene-
tration accounts for virtually all penetra-
ting dust. Although insufficient informa-
tion is available to use the model to
predict penetration, the model does show
trends that should occur with changes in
filter operating variables such as filtration
velocity and pulse pressure, and suggests
areas in which further research is nec-
essary.
Performances of Dust
Loaded Air Filters
C. Kanaoka, Kanazawa University
Dust loading in an air filter enhances
both particle collection and pressure drop
across the filter. However, it was almost
impossible to predict its effects on both
properties properly. In this study, growing
processes of particle dendrites on a fiber
were simulated. Then, they were com-
pared with experimental observations of
collection efficiency, pressure drop, and
particle agglomerates on a fiber for
various filtration conditions and times.
Finally, enhancements of filter perform-
ances were discussed.
Electrostatically Enhanced
Fabric Filtration of Particulates
T. Ariman, University of Tulsa
Recent experimental and analytical
investigations have shown that the elec-
trostatic charge on fibers and/or particles
effectively assist filtration by attracting
particles from a greater distance, and
influencing particle agglomeration and
thus collection efficiency and service life.
The first part of the paper reviews some of
the recent developments in the analytical
investigations of electrostatically en-
hanced fibrous filters. Recently, an ex-
ternal electric field has also been con-
sidered in fabric filtration of industrial
dust with promising results. An increase
in the collection efficiency, especially for
fine particulates, and a decrease in
pressure drop were observed. The second
part of the paper discusses recent devel-
opments in electrostatic fabric filtration
of industrial dust and its possible exten-
sion to the control of diesel emissions.
A Staggered Array Model of a
Fibrous Filter with Electrical
Enhancement
F. Henry, Brunei University
The staggered array of parallel circular
cylinders (fibers) is proposed as a model
for a fibrous filter. The electrical enhance-
ment of the model is accounted for by the
method of images. Stokes' approximation
is utilized in the analysis of viscous flow
around fibers. The predicted pressure
drops and collection efficiencies are
compared to experimental data. The
model is shown to overpredict the pres-
sure drop, but gives reasonable predic-
tions of collection efficiencies in certain
cases.
Section C—Granular Beds
Aerosol Filtration by a Cocurrent
Moving Granular Bed:
Penetration Theory
T. W. Kalinowski, Harvard University
A penetration model for aerosol filtra-
tion by a cocurrent moving bed of granules
has been developed. The model incorpo-
rates straight-through penetration and
reentrainment of previously collected dust
due to granule motion, both mechanisms
having been found significant in experi-
ments. The model is an extension of
classical clean-granular-bed theory, uti-
lizes the familiar concept of a single
granular coefficient for collection, and
proposes a similar coefficient for reen-
trainment.
Experiments have confirmed the ability
of the cocurrent moving granular bed
filter to operate in a continuous mode and
to enhance submicron particle filtration
by the controlled formation of an inter-
granular dust deposit. Reentrainment was
found to be a function of particle size and
other factors, such as gas velocity, gran-
ule velocity, and the extent of intergranu-
lar dust deposit. The single granule
reentrainment coefficient, PR, was found
to depend on the product of intergranular
dust deposit and the square root of particle
diameter (K V3p) for particle diameters
between 0.16 and 5.5 fjm.
Fundamental Experiments on a
Granular Bed Filter
K. linoya, Kyoto University
The filtration performance of a granular
packed bed has been studied experimen-
tally. The filter media are silica sand and
glass beads of various sizes ranging from
1 to 5 mm. The test dust is calcium
carbonate, and the filtration velocities are
20, 30, and 40 cm/s.
The additional pressure loss due to the
collected dust load does not depend on
the filtration velocity because of pinhole
formation at higher velocities. The collec-
tion efficiency is improved at higher
velocities and for heavier dust loads
collected in the filter. The dust distribu-
tions in the filter media are also measured
by chemical analysis.
Dry Dust Collection of Blast
Furnace Exhaust Gas by Moving
Granular Bed Filter
A. Wakabayashi, Kobe Steel Ltd.
In succession to the small-scale pilot
plant test reported at the second sympo-
sium in Denver, an actual sized plant of
one module having the throughput capac-
ity of 80,000 NmVh was installed to
ensure performance and reliability in field
operation, where it proved to have suf-
ficient applicability in various operating
conditions.
Two-staged filtering by moving granular
beds, located in equicentrally circular
double rows, proved to have the exit gas
dust content of 5 mg/Nm3 for the inlet
gas of 2 to approximately 5 g/Nm3.
A more efficient way of energy recovery
from the top gas of blast furnaces is now
accessed to open by utilizing the dry dust
collection in front of turbines rather than
wet scrubbing by venturi scrubbers.
Section D—Novel Devices
Iron and Steel Air Pollution
Control Using Magnetic
Separation
D. C. Drehmel, USEPA
A relocatable pilot plant was built and
tested at a Pennsylvania sintering plant to
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determine the effectiveness and econom-
ics of magnetic filtration. The pilot plant
consisted of two magnetic systems so
that media could be regenerated in one
while the other treated the total flow of
3,000 cfm. The pilot plant collected 90%
of the iron bearing particles, but overall
efficiency was lower because of fine
alkali-chloride aerosol in windbox gas. In
addition to parametric tests, the pilot
plant was operated over 450 hours with
no significant problems. Analysis of the
results indicates that high efficiency
collection can be achieved economically
if magnetic filtration is applied to dusts
that are more homogeneous and more
strongly magnetic than the sinter dust
tested.
Technical and Economic
Evaluation of Two Novel
Paniculate Control Devices
R. R. Boericke. General Electric Co.
A system-level comparison study is
made for two novel particulate removal
devices, based on technical and economic
considerations. The two novel devices are
an Acoustic Agglomerator and an Electro-
cyclone. These devices are considered in
combination with conventional cyclones,
ESPs, and a baghouse.
To investigate high temperature and
high pressure applications, paniculate-
control systems are designed for a 626
MWe Pressurized Fluidized Bed (PFB)
coal-burning electric power plant. For
atmospheric pressure and low tempera-
ure applications, the systems were de-
signed for a new 400 MWe conventional
pulverized coal-burning plant. The results
of the technical and economic feasibility
evaluation are analyzed to develop con-
clusions regarding potential applications
or the two novel cleanup devices. Both
he Electro-cyclone and the Acoustic
Agglomerator appear economically attrac-
ive for PFB power plants, but are not
competitive with ESPs for conventional
pulverized coal-burning plants.
The Electroscrubber Filter-
Applications and Particulate
Collection Performance
D. Parquet. Combustion Power Co.
The Electroscrubber is an electrostatic
granular filter used to remove particulate
n a dry form from gas streams. Achieving
"the best of both worlds" of the dry
icrubber granular filter and electrostatic
collection, the Electroscrubber utilizes a
moving bed of filtering media, and is self-
cleaning while operating on a continuous
basis. The concept, development, and
principle of operation are discussed, along
with a description of tests results from
several Electroscrubber installations.
High Efficiency Particulate
Removal with Sintered
Metal Filters
B. E. Kirstein. Science Applications. Inc.
From October 1978 through February
1980, a laboratory test program was
conducted to verify the particulate re-
moval performance and collection effici-
ency of sintered metal filters (SMFs). A
test apparatus with a capacity of 170
mVh was designed and built. Using flyash
(particle size range of less than 1 yum to 30
jjrn) at a concentration of 6 to 10 g/m3,
the particulate removal efficiencies of
several types of SMFs were measured
over a range of operating conditions.
Over 4,900 hours of SMF operations
were completed with no significant opera-
tional failures. In no case was the SMF
efficiency measured less than 99.999%.
No evidence of filter plugging or failure
was observed. The operating condition
variables included superficial velocities,
SMF blowback methods, temperature,
and humidity. The effects of these
variables on the system pressure drop
and particulate removal efficiencies are
discussed.
Application of Electrostatic
Techniques to the Removal of
Dust and Fume from the
Industrial Environment
S. A. Hoenig. University of Arizona
In earlier reports, we discussed the use
of fog to control fugitive dust. Fogging
units are now sold commercially, but in
many areas it is impractical to use any
water.
For one application of this type, we
have designed and tested an electrostatic
dust rejector that removes dust from the
airbeing drawn into the turret of a military
vehicle. Another system of this type is
used to clean air before it is drawn
through the air filter of an internal
combustion engine. In both situations,
the dust is not "collected," but rather
simply rejected to the environment, there-
by simplifying the overall system.
Oust rejection can also be used to
collect dust from air that is to be passed
from a source to a cyclone or baghouse.
This reduces the load on the regular
control facilities while at the same time
improving the overall system operation by
taking out the small (under 10 Aim)
particulates.
The Dry Venturi
R. J. Roy,
Teller Environmental Systems, Inc.
The major problem in particulate emis-
sion recovery is the reliability of collecting
submicron particles. The use of ESPs has
often resulted in time degradation of
performance and that of baghouses in
blinding or low bag life. A dust agglom-
eration and capture process (dry venturi)
with a pressure drop of 0.2 kPa, providing
removal of the submicron particulate in
the duct prior to the final collector,
increases effectiveness and reliability in
the operation of the final collector. The
system has been successfully operated in
the fiberglass, municipal incineration,
combustion, secondary aluminum, and
fertilizer industries.
Fiber Bed Filter System
Control of Welding Particulates
J. A. Bamberger,
Battelle Pacific Northwest Laboratories
The welding industry is a major source
of emissions of highly resistive particles
with submicron- to micron-size distribu-
tion. The Electrostatic Fiber Bed Filter
(EFBF) developed at the Pacific Northwest
Laboratories of Battelle Memorial Insti-
tute is a highly effective method for
removal of particles with a high electrical
resistivity in the submicron size range.
The system incorporates a particle-
charging section with a highly porous
fiber filter mat to produce a highly efficient
particle collection system with a very low
pressure drop through the system.
This paper discusses the concept of the
EFBF system, its application to the re-
moval of welding particulates, and the
results of a parametric study conducted
under laboratory conditions to evaluate
the EFBF's ability to effectively control
particulates generated during routine
welding. The results of the parametric
analysis include the dependency of the
collection efficiency on electric field
strength, face velocity, and fiber bed void
fraction.
The Use of Glass Capillary
Filters to Classify
Actinolite Fibers
J. W. Gentry, University of Maryland
This paper describes the use of filters
consisting of glass capillary arrays for the
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separation of fibers from the .more abun-
dant isometric particles. A six stage
impactor was designed and calibrated
with PSL aerosols with sizes between 0.5
and 0.8 yum at Stk approximately 0.04.
The major collection occurred at the
interstitial area between pores. A signif-
icant amount of reentrainment was ob-
served. Comparison of these measure-
ments with the theory of Manton and Rich
is discussed.
Actinolite fibers—non-asbestos min-
eral fibers with similar morphology to
amosite—are produced using a vibrating
bed generator. The paper describes the
generator, the analysis of the fractional
penetration, and preliminary measure-
ments.
Finally, an extension of the method
developed by Manton to account for
collection in the interstitial area between
pores is described. Numerical simulations
are compared with scanning electron
micrographs.
Ultra-High Efficiency Filtration
Systems (Air Recirculation)
/?. Potakar,
General Motors Technology Center
The metal casting industry is becoming
increasingly aware of the role energy
availability and its efficient use has on
productivity and profitability. A major use
of energy in a foundry is for heating and
distributing makeup air. Efficientfiltration
and recirculation of presently exhausted
air could be a viable technique for energy
conservation in some cases. This paper
reviews new hardware and test data from
pilot testing sponsored by the American
Foundrymen's Society (AFS) which indi-
cates that paniculate removal efficiencies
in excess of 99.96% are feasible from
casting cleaning.
In addition, guidelines for a complete
system design are presented.
The Wet Wall Electrostatic
Precipitator
J. Starke,
Bischoff Environmental Systems
The incentive to develop a new variation
of the wet ESP—the wet wall electro-
filter—derived from investigations on
removal of particulates from waste gas
from a plant designed to incinerate organ-
ically loaded wastewaters having a high
salt content.
The most efficient and economical
solution proved to be a wet ESP of new
design with vertical, water-cooled ground
electrodes. The water film resulting from
vapor condensation on the cool electrodes
instantaneously dissolves the soluble
particulates and suspends the insoluble
dusts, flushing both from the discharge
zone. Thus, the efficiency of such an ESP
remains constant since it is free of dust
deposits and uninterrupted by flushing
cycles. Of several different applications
tested in the field, the most promising
were those dealing with submicron par-
ticulates and aggressive gases.
Section E—Mechanical
Collectors
Troubleshooting Multiple
Cyclones on Fuel-Oil-Fired
Boilers
F. Crowson,
Naval Surface Weapons Center
The body of information presented in
this paper is directed to the particulate
control of boi lers fired with No. 6 fuel oil, a
problem when stringent standards must
be met. The success of meeting regulatory
standards is highly dependent on the
availability of data for emission character-
ization, as well as the availability of space
and funds for control equipment. Early
efforts toward controlling emissions from
boilers fired by No. 6 fuel oil at two Navy
shore facilities resulted in the selection of
multiple cyclone collectors. Since their
installation, both facilities have failed to
meet compliance with local standards. A
study was made to troubleshoot the
boilers and their associated pollution
control equipment. The problems associ-
ated with the multiple cyclone collector
design, installation, and operation are
examined.
Collection Efficiencies of
Cyclone Separators
P. W. Dietz. General Electric Co.
An improved model for particle collec-
tion in cyclone separators is presented.
The model is predicated on the identifica-
tion of three regions: the inlet, the down-
flow, and the core.
In each region, turbulent mixing is
assumed to result in a uniform radial
concentration profile. The effects of cy-
clone geometry on the gas flow pattern
are included so that the model incorpo-
rates the distribution of gas residence
times.
Experimental results from several
sources are compared to the model pre-
dictions, and favorable agreement
obtained.
Electrostatically Augmented
Collection in Vortical Flows
P. W. Dietz, General Electric Co.
Electrostatic forces have been demo
strated to provide significant enhanc
ment in the efficiency of cyclone sep
rators. To study these effects, expe
ments have been performed in a tw
dimensional vortical flow. In these expe
ments, the effect of an applied electi
field on collection efficiencies has bei
measured for a range of flow rates f
2.02 /urn particles. These measured ef
ciencies are compared with an analyi
model and excellent agreement is demo
strated.
High Performance
Cyclone Development
W. B. Giles, General Electric Co.
The results of ongoing cyclone develo
ments at atmospheric conditions a
reported using the air shield concept wi
and without electrostatic augmentatio
and are contrasted with convention
cyclone art.
The conventional high flow cycloi
configuration appears significantly undc
rated in the literature, and very super!
performance is obtained with the ;
shield design, even without the use
clean air. It is theorized that these gaii
are due principally to improved inlet sw
flow uniformity, a vortex shield to mir
mize dust reentrainment, and increasi
exit swirl to produce a high capaci
cleanup device of high performance.
Test results of electrostatic enhanc
ment are also reported where it is foui
that both internal corona and voltai
fields are required to im'prove perforr
ance. These improvements are found
principally enhance small particle colle
tion and to mitigate loss in performan
at lower flow velocities.
8
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F. P. Venditti, J. A. Armstrong, and M. Durham are with the Denver Research
Institute, Denver, CO 80208.
Dale L. Harmon is the EPA Project Officer (see below).
The complete report, entitled "Third Symposium on the Transfer and Utilization of
Paniculate Control Technology: Volume III. Paniculate Control Devices," (Order
No. PB 83-149 609; Cost: $37.00, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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