&EPA
United States Industrial Environmental Research
Environmental Protection Laboratory
Agency Research Triangle Park NC 27711
EPA-600/8-78-005b
June 1978
Research and Development
Participate Control
Highlights:
Performance and
Design Model
for Scrubbers
BY-PRODUCTS
OR
RECYCLE STREAMS
PUMP SOLID LIQUID
WASTE WASTE
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EPA-600/8-78-005b
June 1978
Participate Control Highlights:
Performance and Design Model
for Scrubbers
by
S. Yung and S. Calvert
A.P.T., 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
When EPA initiated the Wet Scrubber Systems Study in 1970
the state-of-the-art was largely empirical. Each application
was considered to be a special case which could only be dealt
with on the basis of long and specific experience. Engineering
design was based on a primitive, cut-and-try approach and often
resulted in an expensive overdesign to cover the wide range of
uncertainty. There was also very little scrubber performance
information available.
In the Wet Scrubber Systems Study all available information
concerning wet scrubber theory and practice was reviewed and
evaluated. The best available engineering design methods were
evaluated and where necessary new or revised methods were developed
to provide as sound a basis as possible for predicting performance.
The result of this study was the publication in 1972 of the
"Scrubber Handbook."
This capsule report summarizes the best available design
models for wet scrubbers. Details of the models are reported
in the Scrubber Handbook and other EPA publications listed in
the bibliography.
ii
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CONTENTS
Abstract ii
Figures iv
Tables iv
Abbreviations and Symbols . v
Introduction 1
Collection Mechanisms 1
Design Equations 2
Unit Mechanism Approach 2
Deposition Velocity Approach 3
Pressure Drop -.4
Performance Prediction and Scrubber Design 4
Cut Diameter Method for Performance Prediction and Scrubber
Design 5
Cut Diameter 5
Integrated Penetration 6
Cut/Power Relation 7
Power and Cost 8
Bibliography 19
iii
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FIGURES
Number Page
1 Relation Between Physical and Aerodynamic Particle
Diameter 14
2 Experimental and Calculated Collection Efficiencies
for Sphere and Cylinder 15
3 Predicted Particle Diameter, Penetration Relation-
ship for Inertial Impaction 16
4 Integrated (Overall) Penetration as a Function of
Cut Diameter and Particle Parameters 17
5 A.P.T. Cut/Power Plot 18
TABLES
Number
1 Scrubber Classifications 9
2 Design Equations for Various Scrubber Types 10
3 Single Drop and Single Cylinder Collection Efficiency
Due to Various Collection Phenomena 11
4 Particle Deposition Velocity 12
5 Pressure Drop 13
iv
-------
A -
A •
A_ •
t
B -
C •
C •
C' -
CD-
Ci '
Co-
D. •
d -
pa
4PI
E •
P
F •
f -
f(dp)
g
H
h
Pt
kc
I •
LIST OF ABBREVATIONS AND SYMBOLS
cyclone inlet area, m'
dinensionless constant in equation (6)
cross-sectional area of the collector normal to gas flow
direction, •*
deposition area, a*
projected area of baffles, m1
cross-sectional area of duct, m*
dinensionless constant in equation (6)
cyclone geometry parameter, dimensionless
particle concentration, g/a1
Cunningham slip correction factor, dimensionless
drag coefficient, dimensionless
particle concentration at the scrubber inlet, g/m1
particle concentration at the scrubber outlet, g/m1
cyclone diameter, n
particle diffusivity, »2/s
molecular diffusivity, ml/s
collector diameter, m
drop diameter, n
cyclone exit diameter, m
fiber diameter, m
sieve plate perforation diameter, m
particle diameter, n or ura
aerodynamic particle diameter, lunA
mass median diameter, n or UraA
required cut diameter, umA
collection efficiency, fraction
charging electric field strength, v/m
effective precipitating electric field strength, v/m
foam density, dimensionless
empirical constant • O.S
drag coefficient, dimensionless
fraction of hole area, fraction
frequency distribution of particles
acceleration of gravity, m/s1
magnetic field strength, A/m
distance of drops traveled, m
inertial inpaction parameter, dimensionless
inertial parameter at the throat, dimensionless
gas thermal conductivity, J/a-s-'K
particle thermal conductivity, J/m-s-'K
thickness of fibrous packing, a
"Pe
»Re
P
PT
R •
PG
T
"Gt
uh
UPD
ut
W
A •
Greek
cylinder
drop
'pot
nvis
a
Pw
&P
aolecular weight of gas, g/g-aol
aolecular weight of vapor, g/g-nol
Peclet number, diaensionless
Reynolds nuaber, dioensionless
absolute pressure, Pa
overall particle penetration
penetration for particles with diameter d , fraction
radius, a
gas volumetric flow rate, m'/s
liquid volumetric flow rate, m'/s
collector charge, C
particle charge, C
gas partial pressure, Pa
gas temperature, *K
gas velocity passing the collector, m/s
gas velocity, m/s
gas velocity at the throat, m/s
gas velocity through perforation, m/s
particle deposition velocity, m/s
terminal settling velocity, m/s
mass of particles, g
weir length, m
depth of packing, m
fiber fraction, fraction
dielectric constant, dimensionless
porosity, fraction
permitivity constant (8.8S4 x 10" coulomb'/nt-n'J
overall collection efficiency of a unit mechanism, dimensionless
single cylinder collection efficiency, fraction
particle collection due to diffusion, fraction
single drop collection efficiency, fraction
particle collection due to electric precipitation, fraction
particle collection due to gravity, fraction
particle collection efficiency due to impaction, fraction
potential flow drop collection efficiency, fraction
viscous flow drop collection efficiency, fraction
angle of attack, degree
penetration time, s
geometric standard deviation, dimensionless
gas absolute viscosity, kg/a-s
particle density, kg/m1
density of water, kg/m1
pressure drop, cm W.C.
dry pressure drop, ca W.C,
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PERFORMANCE AND DESIGN MODELS FOR SCRUBBERS
INTRODUCTION
Scrubbers are devices which utilize a liquid in the separa-
tion of particulate or gaseous contaminants from a gas stream.
The liquid may be used to contact the gas and particles directly,
or may be used to clean solid surfaces on which the particles
or gases have been collected.
Scrubbers are used extensively for the control of air pollu-
tion emissions. There are so many different scrubber systems
offered by manufacturers that it is often difficult to choose
the right scrubber for a particular job.
The optimum scrubber system for a particular job will not
depend only on the system costs. The major consideration should
be whether the scrubber is capable of removing the pollutants
to the degree required. An inexpensive, simple scrubber which
does not meet the efficiency requirements is not only useless,
but a waste of money and time. It is, therefore, of primary im-
portance to provide as sound a basis as possible for predicting
performance.
Design models based on fundamental engineering concepts
provide the best approach for evaluating the performance and
cost of scrubber systems. This report summarizes the best available
engineering models for particulate scrubbers.
COLLECTION MECHANISMS
Currently available scrubbers can be grouped into a number of
categories: plate, massive packing, fibrous packing, preformed
spray, gas-atomized spray, centrifugal, baffle, impingement and
entrainment, mechanically aided, moving bed, and various combina-
tions (Calvert, et al. 1972 and Calvert, 1977). No matter what
-------
type of scrubber is being evaluated, it is convenient to consider
dust particles to be separated from the gas by one or more unit
mechanisms, the basic particle collection elements which
account for the scrubber performance. For example, in a venturi
scrubber, particle collection is achieved by contacting the par-
ticles with the atomized liquid drops. Thus, collection by drops
is a unit mechanism. Other unit mechanisms for particle collec-
tion include collection by cylinders, sheets, bubbles, and jet
impingement. Table 1 summarizes the scrubber groups and the impor-
tant unit mechanisms for each group.
For each of the unit mechanisms, the particles are separated
from the gas by one or more of the following particle collection
mechanisms: gravitational sedimentation, centrifugal deposition,
inertial impact ion, interception, Brownian diffusion, thermophore-
sis, dif fusiophoresis and electrostatic precipitation. Particle
collection also may be enhanced by increasing the particle size
through agglomeration, condensation, or other particle growth
mechanisms.
DESIGN EQUATIONS
There are two basic approaches for developing design equations
for scrubbers. One approach is to consider the collection effi-
ciency of individual unit .mechanisms , such as collection by single
drops, and derive a relationship for the overall collection
efficiency based on the unit mechanisms. The second approach
is to determine the deposition velocity of a particle experiencing
a specific deposition force, such as electrical attraction.
These two approaches are discussed below.
Unit Mechanism Approach
The general design equation which describes particle collec-
tion by any control device in which the gas and dust are well
mixed is:
dc u
r
dA (1)
c
-------
"n" is the overall collection efficiency of a unit mechanism.
Inertial impaction is the collection of moving particles by
impingement on some target. The relative effect of inertial
impaction for different particles and flow conditions is charac-
terized by the inertial impaction parameter, K , defined as:
Cf p dfur
K = P-P-G (2)
P 9 *G dc
Figure 1 shows the theoretical and experimental target effi-
ciencies for a single sphere and a single cylinder as related
to tLe inertial impaction parameter.
Equation (1) has been solved for various scrubber systems
which involve collection by inertial impaction. The results are
tabulated in Table 2.
Equation (1) also may be applied to other collection mechan-
isms if an expression for "n" is known. Table 3 presents expres-
sions for the single drop and single cylinder collection efficien-
cies resulting from various collection mechanisms.
Deposition Velocity Approach
The particle deposition velocity is the component of its
velocity in the direction towards the collecting surface. If the
particle deposition velocity is constant and the gas and par-
ticles are well mixed everywhere in the scrubber, the particle
collection can be predicted from the following equation:
c
o
Pt, = 1-E = — = exp
ci
UPD AD
(3)
"u D" is the net particle deposition velocity caused by the col-
lection mechanism(s). The deposition velocity for any collection
mechanism depends on the force balance between the driving force
(deposition force) and the resistance force of the gas. Table 4
-------
is a list of theoretical equations predicting the deposition
velocity for each collection mechanism. The scrubber collection
efficiency can be calculated by using equation (3) coupled with
the appropriate deposition velocity and the total deposition
area of the scrubber.
Pressure Drop
Along with particle collection efficiency, the scrubber
power requirement is also an important consideration in designing
the optimum pollution control system. The power requirement for
particle scrubbing is mainly a function of the gas pressure drop.
Preformed sprays and mechanically aided scrubbers have signifi-
cant power inputs to pumps and other devices. Equations for
predicting the gas phase pressure drop for various types of
scrubbers are summarized in Table 5.
PERFORMANCE PREDICTION AND SCRUBBER DESIGN
Air pollution control regulations generally specify a maxi-
mum mass rate of emissions and often set a concentration limit
as well. By knowing the particulate concentration and mass rate
at the scrubber inlet, one can specify the minimum collection
efficiency or the maximum allowable penetration through the
scrubber being designed or selected.
When a range of particle sizes is involved, as generally is
the case, the overall particle penetration will depend on the size
distribution and on the penetration for each size. The overall
penetration, Ft, of any device collecting a dust with any size
distribution will be:
-w Pt, dW
f Ptd dW _ f
J W /
Ft =
W J a " P
The right-hand side of the above equation is the integral
of the product of each weight fraction of dust times the penetra-
tion of that fraction.
-------
In designing a scrubber, the maximum allowable penetration,
Ft, and size distribution, f (d ) , in the process stream must be
known. The only variable in equation (4) is "Ptd" which is a
function of scrubber geometry and scrubber operating conditions.
One must first choose the scrubber geometry and operation condi-
tion, then evaluate "Pt^" by means of the design equations presen-
ted in Table 2 and integrate equation (4) to obtain the overall
penetration, Ft. If the calculated "Ft" is greater than the
allowable maximum, new scrubber geometry and operating conditions
are chosen and the calculations are repeated.
These trial and error procedures are continued until one
arrives at a scrubber design which gives an overall penetration
smaller than or equal to the maximum allowable "Ft." Generally,
more than one scrubber geometry and set of operating conditions
give satisfactory performance. The final selection will be based
on cost, experience and other factors.
Choosing a scrubber is simpler than designing one. The
scrubber manufacturer's proposed geometry and operating condi-
tion may be used to calculate "Ptj" from the appropriate design
equations. Then "Ft" may be calculated from equation (4) to
check whether it is acceptable.
This design method is precise but time-consuming. A much
simpler method, called the "cut diameter" method, has been
developed to provide quick designs when precision is not required.
The "cut diameter" method has been described in the "Scrubber
Handbook" and other publications.
CUT DIAMETER METHOD FOR PERFORMANCE PREDICTION AND SCRUBBER DESIGN
Cut Diameter
A very convenient parameter for describing the capability
of a particle scrubber is the diameter of the particle for which
the scrubber is 501 efficient. This diameter is referred to as
the cut diameter, generally given in aerodynamic units. Thus,
a scrubber with a cut diameter of 1.0 ymA would collect particles
of 1 ymA size at 501 efficiency.
-------
The great utility of cut diameter stems from the fact that a
curve of collection efficiency versus particle diameter for col-
lection by inertial impaction is fairly steep. Several important
types of scrubbers have performance characteristics such that a
particle whose aerodynamic diameter is half the cut diameter would
be collected at about 10% efficiency, whereas a particle with an
aerodynamic diameter twice the cut diameter would be collected
at about 90% efficiency.
Because the cut is fairly sharp, one can use as a rough
approximation the concept that the scrubber collects everything
larger than the cut diameter and passes everything smaller.
Integrated Penetration
Most scrubbers that collect particles by inertial impaction
perform in accordance with the following relationship:
/ B \ c
Ptd = exp -A d )= - (5)
"B" is an empirical constant. Packed-bed and plate type
scrubber performance are described by a value of "B = 2.0"
whereas for centrifugal scrubbers of the cyclone type, B = 0.7.
Gas-atomizing scrubber performance fits a value of "B = 2.0"
over a large portion of the usual operating range. Therefore, we
use a value of "B = 2.0" as representative of most scrubbers
operating in the inertial impaction regime. Figure 2 plots
collection efficiency against the ratio of aerodynamic particle
diameter to performance cut-diameter, showing one line based on
equation (5) and another for a venturi scrubber under typical
operating conditions.
Most industrial particulates have approximately a log-normal
size distribution. Hence, the two basic parameters of the log-
normal distribution adequately describe the size distributions
of particulate matter. These parameters are the mass median
diameter, d , and the geometric standard deviation, o . If the
Jr & **
size distribution is log-normal, a plot of the percent of particles
-------
less or greater than a stated diameter versus the diameter, on
logarithmic probability graph paper, will yield a straight line.
The 50% value of "dpa" equals "dpg" and the ratio of the particle
diameter at about 84.1% undersize to "d " is equal to "a ."
One can integrate equation (4) with "Ptd" given by equation
(5) and "f(dp)M by log-normal distribution. The results are
presented in graphical form in Figure 3. The overall penetration
(FT) for the entire size distribution is plotted against the
ratio of required cut diameter to mass median diameter, with geo-
metric standard deviation as the parameter.
Figure 3 can be used to determine what "dRC," the required
cut diameter, must be in order to get a specific "PT" for a given
size distribution. For example, suppose the size distribution has
"dpg = 10 ymA" and "ag = 3-°>" and one needs 99% collection
efficiency. The penetration is 1001 minus the percent collection
efficiency, or 1%, which corresponds to "Ft = 0.01" in fractional
units .
The diameter ratio corresponding to "Pt = 0.01" and "a =
3.0" is "dRC/dpg = 0.063." Since "dpg = 10 ymA, dRC = 0.63SymA."
This means that one will need a scrubber with a cut diameter of
0.63 ymA or less to achieve 99% collection of the particles in
question.
Cut/Power Relation
Mathematical models for scrubber performance and the cut-
diameter approach developed in the "Scrubber Handbook" led to the
concept that performance cut diameter could be related to gas-
phase pressure drop, or power input to the scrubber. The results
of subsequent performance tests on a variety of scrubbers in
industrial installations, combined with mathematical modeling,
enabled the refinement of the cut/power relationship shown in
Figure 4. The curves give the cut diameter (ymA) as a function
of either power input (W/m3/min) or gas-phase pressure drop (cm
W.C.) for a number of typical installations such as sieve-plate
column, packed column, fibrous packed bed, gas-atomized spray,
and mobile fluidized bed.
-------
The A.P.T. cut/power relationship has been devised and
tested on the basis of all the published data available. It appears
to be an accurate and reliable criterion for scrubber selection.
One can see from Figure 4 that the only "unaided" scrubbers
capable of giving a 0.6 umA cut diameter are the gas-atomized
and fibrous-packed-bed types. A gas-phase pressure drop of
about 33 cm W.C. would be required for the gas-atomized scrubber.
The fibrous packing would need 56 cm W.C. for 100 ym fiber diameter
and about 15 cm W.C. for 50 pm fibers.
It would take about 75 ym fiber diameter to achieve a "dDP -
KL
0.6 ymA" at slightly less pressure drop than for the gas-atomized
scrubber. This is quite fine fiber or wire, and serious questions
would arise regarding its structural stability, and susceptibility
to corrosion and plugging. The safe approach would be to choose
the gas-atomized scrubber unless extensive pilot tests could be
done with fine fiber beds.
Other types of scrubbers could achieve the required per-
formance if augmented by F/C effects or by electrostatic charging.
Each system would have to be examined to determine whether it
would be economically attractive.
Power and Cost
The equivalent power axis plotted on the top of the cut/
power plot is based on 501 efficiency for a fan and motor combination.
The theoretical power requirement is approximately 1.63 W/m'/min
for each centimeter of water pressure drop. Power costs can be
approximated as twice the theoretical power required for 50%
efficiency.
Equipment costs are best estimated from vendor's quotations.
As usual, one must be sure that all prices for competing units
are on the same basis. Materials, ducting, electrical work,
foundations, supporting structure, etc., must be specified as
included or not.
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TABLE 1. SCRUBBER CLASSIFICATIONS
Geometric Type
Unit Mechanism for Particle
Collection
Plate
Massive packing
Fibrous packing
Pre-formed spray
Gas-atomized spray
Centrifugal
Baffle and secondary flow
Impingement and entrainment
Mechanically aided
Moving bed
Combinations
Jet impingement, bubbles
Sheets (curved or plane),
jet impingement
Cylinders
Drops
Drops, cylinders, sheets
Sheets
Sheets
Sheets, drops; cylinders,
jets
Drops, cylinders, sheets
Bubbles, sheets
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TABLE 2. DESIGN EQUATIONS I-OK VAH10US SCRUBBED TVI'tS
SCRUBBER TYPE
DESIGN EQUATIONS
Sieve Plate
Pt - exp [-40 F'K ]. K
. O.J8 < F < 0.65
Massive Packing
Pt
Fibrous Packing
Pt , - exp - ^— an
• Id cylinder
"cylinder ' f(V' fr°m fifa* *
Venturi and
Cas-Atonized Spray
Gc
F(Vf).^^l,tn(!H^)._P^_
- (Kpt f « 0.7)
Preformed Spray
r 3 QL ut z
d" "p * •>n A ,—; ndr°p
L 2 QC d d (ut-U(.) "P
f 3 QL h -1
Ptd * "P ' TTT" "drop • ««>SS-flOV
L 2 QG dd J
. vertical
countercurrent
flow
drop
' fr°m Fi«u« 2
Impingement and
Entrainment
Pl , cxp
) d ]
- i F {r f)
C^G ' J
0.7
- (Kpt,f « 0.7)
0.7 * Kpt.f
Centrifugal
(cyclone)
Ptd - exp
[.2(C ,,
(it + D
[(0.00394 D ) ~\ i - \
1 TT^-Jfe
Centrifugal
(cyclone with
spray)
ptj
"drop P f(V' fr°B FigU"
and n saae as Thmt for the cyclone
Baffle Type
Collector
••t) "I
"'drop " *'"»'• *ro* F1*ure '
10
-------
TABLE 3. SINGLE DROP AND SINGLE CYLINDER COLLECTION EFFICIENCY DUE TO VARIOUS COLLECTION PHENOMENA
COLLECTION
PHENOMENA
DROP
CYLINDER
Interception
= 0.0518
, laminar flow
I. d
f P
, turbulant flow
Diffusion
D U_,-u, 1 d, 2+0.552
|U_,-u, 1 ,
| G d| d
0.5 /VG\I
NRedVV
/3
-0.6
Gravity
Settling
n .
I) _
NRed
60
C' dp pp
18 y U
Electrostatic
Precipitation
4 C' q q
n M
-, charged particle
3 IT p d u e charged drop
p o o
nc = i.s
q
24
, uncharged
particle
charged drop
12 ir2e dr2yr d u
o f G p o _
0,5
-------
TABLE 4. PARTICLE DEPOSITION VELOCITY
Collection Phenomena
Gravitational
Sedimentation
Centrifugal
Deposition
Brownian
Diffusion
Thermophoresis
n~i ~ff 11 dp CPp-PG)g
PD
18 . yn
u
! C- dj (pp-PG) ut«
PU 18 MG R
-pD-^»ftr
3 C' yr / kr \
u „ _ G / G 1 VT
PD 2 pG T \2 kG.kpj
u - M^°'5 P DVG »p
PU PvV'PGV PG V
u . e C'EoEcEp dp
PD
e + 2 4 TT ?G
C1 y H q yf .
PD , ,
3 TT y.-, d^
u P
12
-------
TABLE 5. PRESSURE DROP
Scrubber Type
Sieve Plate
Massive
Packing
Fibrous
Packing
Venturi and Gas
Atomized Spray
Centrifugal
(cyclone)
Baffle
Pressure Drop
iP • hw + how + hdp * hr
h = weir height z 5 cm
W
Q,
how ' O-157 5Jf
2 Pr U?
h = 1 14 TO 4 fl 25-f "1 + fl £11
dp L lJ..*.a rjjJ*U ijjj J p
hr • °'13 j%
Generalized pressure drop correlation for
bed (Perry, 1973).
o ri-p^ p c u 2
!* X/^J. tj (i ^i-> Up
AP - 6 5 x 10" b D b
df
packed
•
, /QL\
AP = 8.24 x 10 uGt2(o^)
AP — n nnfl^l1? r> 1 vall/.O A! vritVi in1f»1" v
(j \ A/I Q /
/O V/16 A\
i "n 1 1 ./_ I i«ri tVirmt1 -irtl^t1
= 0.000513 PG U£H d2y» without inlet
* A/ 6
n 3 f n G P
AP = Z 1.02 x 10 D MG 2 COS2Q A
anes
vanes
13
-------
50
£ 10
Di
2 5
I—I
Q
w
u
a,
u
>—i
£
c
o
a;
(14
< 0.5
0.1
I III'
I I I 1 I I
0.1
Pp - 4.
g/cnr
I I l i I 1 i I I
J |_ I I t I I I I
0.5 1.0 S
PARTICLE DIAMETER, ym
10
20
Figure 1. Relation between physical and aerodynamic particle
diameter.
14
-------
1.0
.9
u-
P*
.7
.6
.5
§
i—i
I -4
i—3
8
.3
.2
.1
0
I I I I I I l |
i I
0.1
0.2 0.3 0.5
1.0
10
Figure 2. Experimental and calculated collection efficiencies for
sphere and cylinder.
-------
3.0
2.0
i i.o
e
n.
o
03
0.5
0.1
I I I 1111 I I I I I I I 11 I
I I
Pt = exp - (A cTa)
TYPICAL
PREDICTION FOR
\ VENTURI
SCRUBBER
\
\
N
i i linn i i i i 11111
i i i i i
in 11i i i
0.1 0.51 2
10 SO
PENETRATION FOR d , I
pa
90 95 98 99
Figure 3. Predicted particle diameter, penetration relationship for
inertial impaction (Calvert , 19741.
-------
1.0
EX
#s
2:
o
KH
E-
E^
2;
< 0.01
o.i r
0.001
Pt = exp (-A d2 )
^ j
0.001
0. 001
0.1
1.0
Figure 4. Integrated (overall) penetration as a function
of cut diameter and particle parameters.
-------
20
os
w
E-
W
Q
E-
1.0
0.2
SCRUBBER POWER, W/.m3/min
50 100 200
I I I I
500
0.5
50 100
GAS PHASE PRESSURE DROP, cm W.C.
Figure 5. A.P.T. cut/power plot
200
la. Sieve-plate column with foam density of 0.4 g/on3 and 0.5 mm hole dia The
number of plates does not affect the relationship much (Experimental data and
mathematical model.)
Ib. Same as la except 3.2 mm hole dia.
2. Packed column with 1-in. rings or saddles. Packing depth does not affect the
relationship much.(Experimental data and mathematical model.)
3a. Fibrous packed bed with 0.3 mm dia. fiber, any depth. (Experimental data and
mathematical model.)
3b. Same as 3a except 0.1 mm dia. fibers.
3c. Same as 3a except 0.05 mm dia. fibers.
4. Gas-atomized spray.(Experimental data from large Venturis, orifices, and rod-
type units, plus mathemtical model.)
5. Mobile bed with 1 to 3 stages of fluidized hollow plastic spheres. (Experimental
data from pilot plant and large-scale power plant scrubbers.)
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BIBLIOGRAPHY
Calvert, S., "Engineering Design of Fine Particle Scrubbers,"
APCA Journal, 24.: 929-934, 1974.
Calvert, S., "How to Choose a Particulate Scrubber," Chemical
Engineering, August 29, 1977.
Calvert, S., "Scrubbing," Chapter 6 in "Air Pollution," 3rd ed.,
Volume IV, Arthur Stern, editor, 1977.
Calvert, S., J. Goldshmid, D. Leith, and D. Metha, "Scrubber
Handbook," NTIS PB 213-016, August 1972.
Calvert, S. and S. Gandhi, "Improved Design Method for F/C
Scrubbing," paper presented at the Second EPA Fine Particle
Scrubber Symposium, May 2-3, 1977, New Orleans, NTIS
PB 273-828.
Calvert, S., S. Yung, H. Barbarika, G. Monahan, L. Sparks, and
D. Harmon, "A.P.T. Field Evaluation of Fine Particle Scrub-
ber," paper presented at the Second EPA Fine Particle
Scrubber Symposium, May 2-3, 1977, New Orleans, NTIS
PB 273-828.
Yung, S., H. Barbarika, and S. Calvert, "Pressure Loss in
Venturi Scrubbers," APCA Journal, 27_: 348-351, 1977.
Yung, S., S. Calvert, and H. Barbarika, "Venturi Scrubber Per-
formance Model," NTIS PB 271-515, August 1977.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/8-78-005b
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE ANDSUBTITLE
Particulate Control Highlights: Performance and
Design Model for Scrubbers
5. REPORT DATE
June 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHORIS)
8. PERFORMING ORGANIZATION REPORT NO.
S. Yung and S. Calvert
9. PERFORMING ORGANIZATION NAME AND ADDRESS
A. P.T., 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
Task Final: 9/77-4/78
COVERED
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTESTjjjRL-RTP project officer is Dennis C. Drehmel, Mail Drop 61,
919/541-2925. EPA-600/8-77-020a, -020b, and -020c are earlier reports in this
series.
is. ABSTRACT The report gives a capsule summary of the best available design models
for wet scrubbers and their application to fine particulate control. Details of the
models are reported in the Scrubber Handbook and other EPA publications listed in
the bibliography. When EPA initiated its Wet Scrubber Systems Study in 1970, the
state-of-the-art was largely empirical. Each application was considered to be a
special case which could only be dealt with on the basis of long and specific exper-
ience. Engineering design was based on a primative, cut-and-try approach and
often resulted in an expensive overdesign to cover the wide range of uncertainty.
There was also very little scrubber performance information available. In the Wet
Scrubber Systems Study all available information concerning wet scrubber theory and
practice was reviewed and evaluated. The best available engineering design methods
were evaluated and, where necessary, new or revised methods were developed to
provide as sound a basis as possible for predicting performance. The Scrubber
Handbook, published in 1972, resulted from this study.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Dust
Scrubbers
Gas Scrubbing
Mathematical Models
Pollution Control
Stationary Sources
Particulate
13B
11G
07A
13H
12A
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
25
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
20
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