vvEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/8-78-005c
June 1978
Research and Development
Particulate Control
Highlights:
Flux Force/
Condensation Wet
Scrubbing
F/C SCRUBBER
DEMONSTRATION
PLANT
AJ>T - E.PA.
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The 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 SPECIAL REPORTS series. This series is
reserved for reports which are intended to meet the technical information needs
of specifically targeted user groups. Reports in this series include Problem Orient-
ed Reports, Research Application Reports, and Executive Summary Documents.
Typical of these reports include state-of-the-art analyses, technology assess-
ments, reports on the results of major research and development efforts, design
manuals, and user manuals.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/8-78-005C
June 1978
Particulate Control Highlights:
Flux Force/Condensation
Wet Scrubbing
by
S. Calvert and R. Parker
Air Pollution Technology, Inc.
4901 Morena Boulevard, Suite 402
San Diego, California 92117
Contract No. 68-02-2190
Program Element No. EHE624
EPA Project Officer: Dennis C. Drehmel
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
Flux force/condensation (F/C) scrubbing involves the use of
water vapor condensation effects to enhance fine particle collec-
tion. F/C scrubbing offers significant cost advantages over con-
ventional control equipment for a large number of industrial
sources. Generally it is attractive when high removal efficien-
cies are required for fine particles; and the flue gas enthalpy
is sufficiently high or spent steam is available.
The EPA fine particle scrubber program has been instrumental
in identifying, understanding, and quantifying flux force and
condensation effects in wet scrubbers. EPA also has taken a
leading role in developing and demonstrating F/C scrubbers for
industrial applications.
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CONTENTS
Abstract ii
Figures iv
Tables iv
Introduction 1
F/C Scrubber Development. . 1
Early Development 2
Demonstration Plants 3
Design Considerations 3
Particle Size Distribution 4
Particle Number Concentration 4
Particle Condensation Ratio 4
Particle Properties 5
Contribution of Flux Forces 5
Practical Applications 6
General Features 6
Steam Introduction 7
Economic Feasibility 8
Conclusions 8
Bibliography 15
ill
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FIGURES
Number Page
1 Simplified F/C Scrubber System 12
2 Particle Size Distribution Before and After
Condensation for 109 Particles/DNcm3 13
3 Generalized Process Design for F/C Scrubber System. 14
4 Predicted Performance for F/C Venturi Scrubber. . . 15
TABLES
Number Page
1 Major Industrial Particulate Sources for Which
F/C Scrubbing is Attractive 9
2 Cost Comparison of Cupola Emission Control System . 10
3 Cost Comparison for Premium Wire Recovery 11
iv
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ABBREVIATIONS AND SYMBOLS
CFM - cubic feet per minute
DNm3/min - dry normal m3/min (at 1 atm, 20°C)
F/C - flux force and condensation
n - particle number concentration, cm
psig - pounds per square inch gage
ymA - aerodynamic micrometers, urn yg/cnr
PG - air density, g/cm3
p - particle density, g/cm3
v
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FLUX FORCE/CONDENSATION WET SCRUBBING
INTRODUCTION
In 1970, the EPA fine particle scrubber program was ini-
tiated with the Wet Scrubber Systems Study. The principal result
was the publication of the Scrubber Handbook (Calvert, et al.,
1972), reviewing the state-of-the-art and pointing out several
paths which might lead to improvements in scrubber technology.
Since 1972, the broad objective of the EPA program has been to
develop and demonstrate low pressure drop (30-50 cm water column)
scrubber systems capable of collecting at least 90% by mass of
particles smaller than 3 ym in diameter.
A major drawback with conventional wet scrubbers is the large
energy expenditure required to achieve high removal efficiencies
for particle diameters smaller than 2 to 3 ym. Primarily this is
a result of the decreased effectiveness of inertial mechanisms
for separating very small particles from a gas stream.
The Wet Scrubber Systems Study recommended investigating
phenomena which can exert forces other than inertial forces on
particles and where warranted, developing equipment to use these
forces for particle collection. Along this line, a major thrust
has been aimed at developing and demonstrating flux force/conden-
sation (F/C) scrubbers.
F/C SCRUBBER DEVELOPMENT
Essentially an F/C scrubber is any wet scrubber which is
designed to take advantage of water vapor condensation effects
to enhance particle collection. A simplified F/C scrubber system
is illustrated schematically in Figure 1. Some of the water vapor
condenses on the particles causing their mass and diameter to
increase and thereby making them easier to collect. The rest of
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the condensing vapor sweeps particles with it as it moves toward
the cold surface and condenses. To a lesser extent particle
collection is also enhanced by thermal forces resulting from the
temperature gradient between the gas and the cold surface. The
diffusion and thermal forces are termed "flux" forces.
Investigators had realized for years that anomalously high
collection efficiencies could be obtained at relatively low pres-
sure drops when water vapor condensation occurred ahead of the
scrubber. However, no systematic investigation had been conduc-
ted which could be used to design and optimize scrubbers to take
advantage of flux force and condensation effects. Since 1972 the
EPA has taken a leading role in this area, developing F/C scrub-
bing through theoretical, laboratory, pilot plant and full scale
industrial demonstration plant projects.
Early Development
The feasibility of F/C scrubbing for fine particulate control
was investigated and reported by Calvert, et al. (1973) and
Calvert and Jhaveri (1974). The work involved extensive theo-
retical studies and exploratory experiments on a bench scale.
Preliminary engineering and cost analyses were conducted and it
was recommended that pilot scale F/C scrubbers be built and tested,
Two pilot scale F/C scrubbers were built to handle from 14
to 28 m3/min (500-1,000 CFM) actual gas flow rate. Based on the
results of the bench scale work, multiple sieve plate and hori-
zontal spray scrubber configurations were selected for the pilot
study. The results were very promising both from a technological
and from an economic point of view. Depending on the process
characteristics, the operating costs for an F/C scrubber were
predicted to be as low as 1/3 or less of the operating cost for
an equivalent high energy scrubber. Details of the pilot plant
studies were reported by Calvert, et al. (1975) and Calvert and
Yung (1976).
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Demonstration Plants
EPA has funded two full-scale industrial F/C scrubber demon-
stration plants. The first demonstration plant was a multiplate
F/C scrubber used to control fine particle emissions from a
secondary metal recovery furnace. Control of the entire source
effluent (200 m 3/min or 7,000 ACFM) at temperatures up to 800°C
required both particle collection and acid gas absorption. The
demonstration plant performance was consistent with the earlier
bench-scale and pilot-scale studies.
The system was generally capable of about 901 to 95% effi-
ciency on particles with a mass median aerodynamic diameter of
0.7 to 0.8 ymA (about 0.3 ym physical diameter for particles
with a density of 4.0 g/cm3). This efficiency was achieved with
a 68 cm (27 in) W.C. gas phase pressure drop. A conventional
high energy scrubber without F/C effects would have required
pressure drops of roughly 250 cm (98 in) W.C. for 901 and 535 cm
(210 in) W.C. for 95% particle collection efficiency.
Detailed results and economic analyses for the demonstration
plant have been reported by Calvert, et al. (1977) and Calvert
and Gandhi (1977).
The second F/C scrubber demonstration currently is underway.
A gas-atomized spray F/C scrubber will be used to control fine
particle emissions from a gray iron foundry cupola. Plant startup
is scheduled for late fall, 1978.
DESIGN CONSIDERATIONS
One of the major goals of the EPA F/C scrubbing development
program has been to quantify the important F/C effects by identi-
fying key process parameters and developing useful engineering
models for design and performance prediction purposes. This goal
has been achieved through the systematic development and demon-
stration program described above, resulting in a simplified and
improved design method for F/C scrubbing as reported by Calvert
and Gandhi (1977) . The most important parameters and design
concepts are discussed briefly on the following pages.
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Particle Size Distribution
One of the most important design parameters for any particu-
late control device is the particle size distribution. In an F/C
scrubber there are two size distributions which must be considered.
The initial size distribution is that leaving the source and enter-
ing the saturator and condenser. This size distribution is used
to predict the collection efficiency in the saturator and initial
stages of the condenser before condensation occurs. It also is
important in determining the final size distribution after conden-
sation.
The final or "grown" particle size distribution is that
which results from water vapor condensation on the particles.
Typical initial and grown particle size distribution curves are
shown in Figure 2. A convenient design assumption is that each
particle receives the same mass of condensing vapor, independent
of the particle diameter. This explains the observation that
small particles grow much more than large particles. Although
this assumption is not strictly valid, it agrees well with experi-
mental observation for particle diameters of interest (larger
than about 0.1 ym).
Particle Number Concentration
Because all particles receive an approximately equal mass of
condensate, the number concentration of particles is very impor-
tant in determining the final grown particle size. Particle num-
ber concentration is not generally an important parameter for other
particulate control techniques and therefore it often is difficult
to find adequate data. However, these data are essential for pro-
per design of F/C scrubbing systems. Representative number con-
centrations for industrial sources can range from about 107 to 109
particles/DNcm3.
Particle Condensation Ratio
Most of the water vapor will condense on the cold, solid or
liquid surfaces of the condenser. Only a fraction of the vapor
will condense on the particles. This fraction is called the
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particle condensation ratio. It is affected by many parameters
including: inlet gas temperature, bulk liquid temperature, particle
number concentration, particle diameter, liquid phase heat transfer
coefficient, and condenser geometry. Particle condensation ratios
ranging from 15% to 40% have been predicted for several combinations
of parameters in a sieve plate condenser. For a combination of
parameters such as might be encountered in a practical situation
a value of 0.25 appears to be reasonable for a plate type condenser.
This is equivalent to saying that 25% of the condensing vapor goes
to the particles and 75% goes to the cold surfaces.
Particle Properties
In the design model, particles are assumed to be wettable,
but insoluble. If the emitted particles were soluble in water,
the expected performance for the system would be better. The
solubility of the particles in water would depress the vapor pres-
sure at the particle-gas interface, resulting in nucleation at
a lower saturation ratio and more growth at a given saturation ratio.
Particle density also is important. This usually is accounted
for by using the particle aerodynamic diameter for all particle
collection calculations. The difference in particle and liquid
densities must be considered when predicting grown aerodynamic dia-
meters .
Contribution of Flux Forces
Particle collection by thermal gradient forces (thermophoresis)
is only of minor importance and usually is neglected when predicting
the performance of an F/C scrubber.
Diffusion flux forces (diffusiophoresis) however, are sig-
nificant and must be considered. Detailed mathematical models
exist for predicting diffusiophoretic deposition velocities and
particle collection efficiencies. These models are complicated
and cumbersome to use, requiring a step-by-step numerical integra-
tion over the period of condensation.
Whitmore (1976) discovered that the fraction of particles
removed by diffusion of the condensing vapor is approximately equal
to the fraction of the gas which condenses. In other words, if
some fraction of the gas is transferred to the liquid phase it
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will carry along its load of suspended particles. It turns out
that this simplifying assumption is extremely useful for design pur-
poses if modified to account for the molecular weight gradient
and the fraction of condensate which condenses on particles.
PRACTICAL APPLICATIONS
In general, F/C scrubbing is attractive economically when
high removal efficiencies are required for fine particle emissions;
and the flue gas enthalpy is higher than 100 kcal/kg or spent
steam is available in the plant. These conditions are common
for industrial combustion processes, which include several major
stationary pollution sources in the United States. Table 1 lists
some of the major industrial particulate pollutant sources for
which F/C scrubbing is attractive. It is clear that F/C scrubbing
is a feasible and attractive particulate control method for
several major industrial sources.
General Features
Although the details of F/C scrubbing system designs will
be different for each source, the overall process designs will be
similar to that shown in Figure 3. Some general economic features
of F/C scrubbing are discussed below.
Experimental pilot plant results indicate that it should
require from 0.1 to about 0.3 g water vapor condensed/g dry
gas in a F/C scrubber to attain high collection efficiency for
fine particles. Such a condensation ratio generally requires
preconditioning of the scrubber inlet gas to increase its moisture
content.
Gas preconditioning could be done either by direct intro-
duction of spent steam if the gas is dry and has low enthalpy,
or by evaporation of sprayed water when enough enthalpy is avail-
able in the gas. Direct injection of steam is beneficial because
it can increase the local saturation ratio appreciably higher than
1.0, which is necessary to initiate the growth of hydrophobic
particles.
Cooling water is needed to condense the desired amount of
vapor in the scrubber. In an industrial system the water is
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cooled in an evaporative cooling tower using ambient air, and
then recirculated to the F/C scrubber. In cooling towers of
conventional design, the change in water temperature is kept below
about 17°C (30°F). A larger water temperature differential can
be achieved in cooling towers of special design but the costs
will be higher than usual, and there may be undesirable features
such as fog formation. If the water temperature increase in the
scrubber is 17°C (30°F), about 32 g of cooling water will be
required to condense 1 g of water vapor.
Steam Introduction
While the performance of an F/C scrubber at a given conden-
sation ratio is better if part or all of the water vapor is intro-
duced as steam (i.e, 100% HaO), the cost of purchased steam will
generally be prohibitively high. However, under the right cir-
cumstances the use of some steam introduction could be economical.
The steam required for injection could be low pressure,
less than 2 atm gage (30 psig) spent steam. It may be obtained
from the feed line to the boiler condenser in a process plant or
generated in a low pressure waste boiler in a metallurgical
operation. In this case, the steam cost would be significantly
lower and will depend on the specific manufacturing process.
Figure 4 shows the predicted penetration for an F/C venturi
scrubber as a function of condensation ratio and gas phase pres-
sure drop. These predictions are conservative in that they
assumed the initial particle nuclei had negligible mass and dia-
meter. The amount of steam required to achieve a given penetra-
tion at a specified pressure drop is equivalent to "q1". The
economics of steam generation will depend on the required pene-
tration and the savings in power usage associated with the lower
pressure drop required for F/C scrubbers.
In general, a F/C scrubber using some purchased steam would
have lower operating costs compared to a venturi scrubber. Also,
the most important mechanisms in F/C scrubbing (diffusiophoresis
and particle growth by condensation) are practically insensitive
to particle size. Thus, F/C scrubbing would become economically
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more attractive as the size of the particles to be controlled
becomes smaller.
Economic Feasibility
The economic feasibility of an F/C scrubber system used to
control emissions from a gray-iron foundry cupola was reported
by Calvert, et al. (1975). A comparison between the estimated
costs of the F/C scrubber system and a conventional high energy
scrubber system are presented in Table 2. Both capital and
operating costs are cheaper with the F/C scrubber system. The
largest difference is in the power costs where the lower pressure
drop required for F/C scrubbing results in substantial savings.
Based on the results of the first demonstration plant, an
optimum design for an F/C scrubber was obtained for controlling
emissions from a premium wire recovery furnace. The costs are
compared with a conventional high energy scrubber in Table 3.
CONCLUSIONS
The EPA fine particle scrubber program has been instrumental
in identifying, understanding, and quantifying flux force and
condensation effects in wet scrubbers. As a result, it is now
possible to use a proven engineering design model to design F/C
scrubbers for new sources, or to modify existing scrubbers to
take better advantage of F/C effects.
EPA has demonstrated on laboratory, pilot and industrial
scales, that F/C scrubbing is technologically feasible and
attractive. Furthermore, F/C scrubbing offers very significant
cost savings over conventional control equipment for a large
number of industrial sources. EPA involvement in F/C scrubbing
is continuing with further industrial demonstration projects.
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TABLE 1. MAJOR INDUSTRIAL PARTICIPATE SOURCES FOR WHICH
F/C SCRUBBING IS ATTRACTIVE
INDUSTRY
Iron § Steel
;orest Products
.ime
Primary Non ferrous
Aluminum
Copper
Zinc
Lead
Asphalt
Ferroalloys
Iron Foundry
Secondary Nonferrous Metals
Copper
Aluminum
Lead
Zinc
SOURCE
Sinter Plants
Coke Manufacture
Blast Furnaces
Steel Furnaces
Scarfing
Wigwam Burners
Pulp Mills
Rotary Kilns
Vertical Kilns
Calcining
Reduction Cells
Roasting
Reverberatory Furnaces
Converters
Roasting
Sintering
Distillation
Sintering
Blast Furances
Dross Reverberatory Furances
Paving Materials
Roofing Materials
Blast Furnaces
Electric Furnaces
Furnaces
Material Preparation
Smelting and Refining
Sweating Furnaces
Refining Furnaces
Chlorine Fluxing
Pot Furnaces
Blast Furnaces
Reverberatory Furances
Sweating Furnaces
Distillation Furnaces
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TABLE 2. COST COMPARISON OF CUPOLA EMISSION CONTROL SYSTEMS
COST ITEMS HIGH ENERGY F/C SCRUBBER
SCRUBBER SYSTEM SYSTEM
($3 CD ($)
A. Capital Costs
1. F.O.B. quencher with
internals, flange to
flange. (4) 16,050
2. F.O.B. scrubber with
internals, flange to
flange including
entrainment separator 24,590 42,910
3. F.O.B. cooling tower -- 46,200
4. Fans, motors and motor
starter 206,690 46,260
5. Liquid treatment and
solid handling equip-
ment, including pumps 66,130 105,740
6. Piping and ducting (2) 159,370 135,580
7. Instrumentation and
electrical material (3) 30,270 20,670
TOTAL EQUIPMENT COST - 487,050 413,410
B. Annual Operating Costs
1. Electrical power for
fans and pumps 159,170 60,370-
2. Annualized capital
charges and depreciation
(20% of capital costs) 97,410 82,680
TOTAL $256,580 $143,050
Notes
1. Actual costs obtained from the user, converted to 1978
2. Due to equivalent complexity, the costs were assumed
same for both systems.
3. Taken as 51 of equipment costs for the F/C system.
4. Quench spray costs for both the systems are included
in the ducting costs.
10
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TABLE 3. COST COMPARISON FOR PREMIUM WIRE RECOVERY
COST ITEM
Venturi
Cooling Tower
Condenser
Saturator
Blower § Motor
Total Equipment
Total Capital
Investment
Depreciation
Maintenance
Water
Raw Materials
Power
Total Annual Cost
COST
FOR F/C
$ 1,700
8,900
4,040
5,060
3,790
23,490
$103,121
$10,310
6,185
180
1,650
2,370
$20,695
COST FOR
CONVENTIONAL
$ 1,700
0
4,040
5,060
14,450
25,340
$111,242
$ 11,125
6,675
180
1,650
11,530
$31,160
11
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CLEAN GAS
i
WATER —£>• SCRUBBER
SATURATED
GAS
WATER —M
CONDENSER
^SATURATED
GAS
WATER U>|PRECONDITIONER|
HOT GAS
Figure 1. Simplified F/C scrubber system.
12
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3.0
I I
1.0
W
H
W
o
w
u
I—I
OS
GROWN
0.5
0.1
Figure 2.
INITIAL
I
I I i
I
I
10
30 50 70
DRY MASS % UNDERSIZE
90 95
98
Particle size distribution before and after condensation
for 109 particles/DNcm3.
13
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TO STACK
AIR
FROM
SOURCE
I
UJ
Cf
CITY.
WATER
AIR
TO DRAIN OR
LIQUID TREATMENT
Figure 3. Generalized process design for F/C scrubber system.
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i.o.
PI
o
o
rt
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
I i
VENTURI
AP = 50 cm W.C,
PREDICTED Pt VERSUS
q' FOR F/C VENTURI
SCRUBBER
I i I I I
0.01
0.05 0.1 0.5
q', g H20 CONDENSED/g DRY AIR
1.0
Figure 4. Predicted performance for F/C venturi scrubber.
Initial particle diameter=0, n =10B particles/cm3,
20% condensate on particles, pA = 0.0011 g/cm3,
Pp = 1.0 g/cm3.
15
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BIBLIOGRAPHY
Calvert, S., et al., "Scrubber Handbook," EPA-R2-72-118a,
NTIS PB 213-016, July 1972.
Calvert, S., et al., "Feasibility of Flux Force/Condensation
Scrubbing for Fine Particulate Collection," EPA-650/2-
73-036, NTIS PB 227-307, October 1973.
Calvert, S., and N.C. Jhaveri, "Flux Force/Condensation Scrubbing,"
Proceedings of the EPA Fine Particle Scrubber Symposium,
San Diego, CA, May 1974, EPA-650/2-74-112, NTIS PB 239-335,
1974.
Calvert, S., et al., "Study of Flux Force/Condensation Scrubbing
of Fine Particles," EPA-600/2-75-018, NTIS PB 249-297,
August 1975.
Calvert, S., and S.C. Yung., "Study of Horizontal Spray Flux
Force/Condensation Scrubber," EPA-600/2-76-200, NTIS
PB 262-669, July 1976.
Calvert, S., and S. Gandhi, "Improved Design Method for F/C Scrub-
bing," Proceedings of Second EPA Fine Particle Scrubber
Symposium, New Orleans, LA, May 1977, EPA-600/2-77-193,
NTIS PB 272-828, September 1977.
Calvert, S., et al., "F/C Scrubber Demonstration on a Secondary
Metals Recovery Furnace," Pro'ceedings of Se_eond EPA Fine
Particle Scrubber Symposium, New Orleans, LA, May 1977,
EPA-600/2-77-193, NTIS PB 273-828, September 1977.
Calvert, S., and S. Gandhi, "Fine Particle Collection by a Flux
Force/Condensation Scrubber: Pilot Demonstration,"
EPA-600/2-77-238, NTIS PB 277-075, December 1977.
Whitmore, P.J., "Diffusiophoretic Particle Collection Under
Turbulent Conditions," Ph.D. Thesis, University of British
Columbia, Canada, 1976.
16
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/8-78-005c
3. RECIPIENT'S ACCESSION NO.
. TITLE ANDSUBTITLE
Particulate Control Highlights: Flux Force/Conden-
sation Wet Scrubbing
REPORT DATE
June 1978
. PERFORMING ORGANIZATION CODE
. AUTHOH(S)
8. PERFORMING ORGANIZATION REPORT NO.
. Calvert and R. Parker
. PERFORMING ORGANIZATION NAME AND ADDRESS
Air Pollution Technology, Inc.
4901 Morena Boulevard, Suite 402
San Diego, California 92117
10. PROGRAM ELEMENT NO.
EHE624
11. CONTRACT/GRANT NO.
68-02-2190
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
Task Final; 10/77-4/78
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES jjERL-RTP project officer is Dennis C. Drehmel, Mail Drop 61,
919/541-2925.
16. ABSTRACT The report gives highlights of EPA's flux force/condensation (FF/C)
program, a system that involves the use of water vapor condensation effects to
enhance fine particle collection. FF/C scrubbing offers significant cost advantages
over conventional control equipment for a large number of industrial sources.
Generally, it is attractive when high removal efficiencies are required for fine
particles, when flue gas enthalpy is sufficiently high, or when spent steam is avail-
able. EPA's fine particle scrubber program has been instrumental in identifying,
understanding, and quantifying flux force and condensation effects in wet scrubbers.
EPA also has taken a leading role in developing and demonstrating FF/C scrubbers
for industrial applications.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Air Pollution
Dust
Flux Density
Condensating
Gas Scrubbing
Air Pollution Control
Stationary Sources
Particulates
Flux Force/Condensa-
tion Scrubbing
13 B
11G
07D
07A,13H
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
22
20. SECURITY CLASS (Thispage/
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
17
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