EPA-600/2-76-282
December 1976
Environmental Protection Technology Series
NATIONAL DUST COLLECTOR MODEL 850
VARIABLE ROD MODULE VENTURI
SCRUBBER EVALUATION
industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
Tho five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
trejitment of pollution sources to meet environmental quality standards.
EPA RE VIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
doos 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.
-------
EPA-600/2-76-282
December 1976
NATIONAL DUST COLLECTOR MODEL 850
VARIABLE ROD MODULE
VENTURISCRUBBER EVALUATION
by
Seymour Calvert, Harry F. Barbarika, and Charles F. Lake
Air Pollution Technology, Inc.
4901 Morena Boulevard, Suite 402
San Diego, California 92117
Contract No. 68-02-1869
ROAP No. 21ADM-029
Program Element No. 1AB012
EPA Project Officer: Dale L. Harmon
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
-------
ABSTRACT
The performance of a National Dust Collector Model 850
variable rod module venturi scrubber was measured at an in-
dustrial installation. Fine particle collection efficiency
as a function of particle size was computed from the data
taken.
The scrubber tower was operated at 1,010 Am3/min at
35°C with a total pressure drop of 224 cm W.C. (88 in W.C.)
with a pressure drop across the venturi module of 178 cm
W.C. (70 in W.C.). The emission source was an iron cupola
which processes ductile iron and gray iron, with the later
producing a higher grain loading than the former.
The ductile iron source particulates had a mass mean
diameter range of 0.25 to 0.84 ymA with a standard deviation
range of 1.5 to 2.0. The gray iron source particulates had
a mass mean diameter range of 0.54 to 1.9 ymA with a standard
deviation range of 1.5 to 1.8.
The overall average collection efficiency for ductile
iron melting was 98.7% and for the gray iron melting the
average collection efficiency was also 98.7% even though
the cupola emission is lower for ductile iron than for gray
iron melting.
111
-------
TABLE OF CONTENTS
Abstract iii
List of Figures v
List: of Tables vii
List, of Abbreviations and Symbols ix
Sect ions
Introduction 1
Conclusions ..... 2
Source and Control System 3
Test Method 7
Conditions for Runs 10
Operating Conditions 12
Cascade Impactor Particle Data 13
Diffusion Battery Data 16
Particle Penetration 17
Opacity 22
Economics 23
Operating Problems 25
Mathematical Model 26
References 32
Appendix A 33
Appendix B 48
IV
-------
LIST OF FIGURES
No.
1 Schematic Flow Diagram of Scrubbing
System 4
2 Schematic of Scrubber Tower 5
3 Modified E.P.A. Sampling Train with
In-Stack Cascade Impactor 8
4 Penetration versus Aerodynamic Particle
Diameter for Ductile Operation 19
5 Penetration versus Aerodynamic Particle
Diameter for Gray Operation 20
6 Actual and Predicted Particle Penetration
versus Aerodynamic Particle Diameter for
Ductile Operation 28
7 Actual and Predicted Particle Penetration
versus Aerodynamic Particle Diameter for
Gray Operation 29
A-l Inlet and Outlet Size Distribution
for Run 2 39
A-2 Inlet and Outlet Size Distribution
for Run 3. . . . 39
A-3 Inlet and Outlet Size Distribution
for Run 4 (heated inlet cascade impactor) ... 40
A-4 Inlet and Outlet Size Distribution
for Run 5 40
A-5 Inlet and' Outlet Size Distribution
for Run 6 (heated inlet cascade impactor) ... 41
A-6 Inlet and Outlet Size Distribution
for Run 7 41
A-7 Inlet and Outlet Size Distribution
for Run 8 42
A-8 Inlet and Outlet Size Distribution
for Run 9 42
A-9 Inlet and Outlet Size Distribution
for Run 10 (heated inlet cascade impactor) . . 43
A-10 Inlet and Outlet Size Distribution
for Run 11 (heated inlet cascade impactor) . . 43
v
-------
No. Page
A-ll Inlet and Outlet Size Distribution
for Run 12(heated inlet cascade impactor). . . 44
A-12 Inlet and Outlet Size Distribution
for Run 13 44
A-13 Inlet and Outlet Size Distribution
for Run 14 45
A-14 Inlet and Outlet Size Distribution
for Run 15 45
A-15 Inlet and Outlet Size Distribution
for Run 16 and 16P
A-16 Inlet and Outlet Size Distribution
for Run 16 and 16P 46
for Run 17 (heated inlet cascade impactor)
46
A-17 Diffusion Battery Data for Ductile
Operation
A-18 Diffusion Battery Data for Gray
Operation
VI
-------
LIST OF TABLES
No.
1 Test Run Summary . . . .x 11
2 Operating Conditions 12
3 Inlet and Outlet Size Distribution Summary . . 14
4 Overall Penetration Summary 21
5 Opacity Summary 22
A-l Inlet and Outlet Size Distribution Data
for Run 1 34
A-2 Inlet and Outlet Size Distribution Data
for Run 2 34
A-3 Inlet and Outlet Size Distribution Data
for Run 3 34
A-4 Inlet and Outlet Size Distribution Data
for Run 4 34
A-5 Inlet and Outlet Size Distribution Data
for Run 5 35
A-6 Inlet and Outlet Size Distribution Data
for Run 6 35
A-7 Inlet and Outlet Size Distribution Data
for Run 7 35
A-8 Inlet and Outlet Size Distribution Data
for Run 8 35
A-9 Inlet and Outlet Size Distribution Data
for Run 9 36
A-10 Inlet and Outlet Size Distribution Data
for Run 10 36
A-ll Inlet and Outlet Size Distribution Data
for Run 11 36
A-12 Inlet and Outlet Size Distribution Data
for Run 12 36
VII
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No. Page
A-13 Inlet and Outlet Size Distribution Data
for Run 13 37
A-14 Inlet and Outlet Size Distribution Data
for Run 14 37
A-15 Inlet and Outlet Size Distribution Data
for Run 15 37
A-16 Inlet and Outlet Size Distribution Data
for Run 16 37
A-17 Inlet and Outlet Size Distribution Data
for Run 16P 38
A-18 Inlet and Outlet Size Distribution Data
for Run 17 38
Vlll
-------
LIST OF ABBREVIATIONS AND SYMBOLS
Latin
C1 - Cunningham slip correction factor
d, - drop diameter, cm
d - particle diameter, ym
d - aerodynamic particle diameter, ymA
pa
d - geometric mass mean particle diameter, ym or ymA
IT O
Fj - correction factor, dimensionless
£ - throat length, cm
AP - pressure, cm W.C.
QG - gas flow rate, cm3/sec
QL - liquid flow rate, cm3/sec
r - rod radius, cm
T - temperature, °C
UG - gas velocity in the throat, cm/sec
Greek
, 1/2
ymA - aerodynamic particle diameter, ym (g/cm )
p - particle density, g/cm3
a - geometric standard deviation of particle size distribution
6
IX
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INTRODUCTION
Air Pollution Technology, Inc. (A.P.T.) conducted
a performance evaluation of a National Dust Collector
Model 850 variable rod module venturi scrubber in accor-
dance with E.P.A. Contract No. 68-02-1869, "Fine Particle
Scrubber Evaluations."
The objective of the performance test was to deter-
mine fine particle penetration as a function of particle
size and scrubber parameters.
Simultaneous inlet and outlet particle sampling
measurements were taken on the scrubber during a test
period from August 19, 1975 to August 28, 1975.
In-stack cascade impactors, total filters using
impactor blank runs, condensation nuclei counters and
a portable diffusion battery were used to obtain mass
loadings and size distribution data. The results of
these series of tests on the National Dust Collector
Model 850 variable rod module venturi scrubber are pre-
sented in the text.
-------
CONCLUSIONS
Experimental test results are presented for a National
Dust Collector Model 850 variable rod module venturi scrubber
treating emissions from a cupola melting ductile iron and
gray iron. The scrubber tower operated at a total system
pre.ssure drop of 224 cm W.C. while the venturi module sec-
tion pressure drop was 178 cm W.C. Overall particle pene-
tration ranged from 1.0% to 2.0% for ductile operation and
1.0',; to 1.6% for gray operation. Average overall particle
penetration was 1.3% for both the gray and ductile iron
melting.
The particle penetrations for both ductile and gray
operations at various particle diameters were compared to
predicted results. Agreement was reasonable for particles
with a diameter greater than 0.8 umA. The actual particle
penetration for particles smaller than 0.8 ymA was less than
tha-; predicted, based on inertial impaction alone.
Some particle growth prior to the venturi rod module
could have occurred to account for the increase in actual
efficiency at the smaller sizes. Particle collection due
to flux/condensation effects in the cooling section of the
tower could also have contributed to the collection effi-
ciency of the fine particles.
Economic data were supplied by the user for 1967 in-
stallation and operation. Total initial costs \vere $556,000
while the total annual costs were $96,000.
-------
SOURCE AND CONTROL SYSTEM
The emission source was an iron cupola which operated
for ten hours per day. The cupola melted both the relatively
clean ductile iron and the dirtier gray iron.
The primary component of the scrubbing system was a
National Dust Collector Model 850 variable rod module ven-
turi scrubber. The nominal capacity was 623 m3/min at 21°C
(22,000 CFM at 70°F). The variable rod module could be
operated at pressure drops from 100 to 230 cm W.C. (40 to
90 inches W.C.). The venturi module consisted primarily of
several parallel rods positioned normal to the gas flow. The
gas was moved through the scrubber by two induced draft Buf-
falo 91 blowers used in series. Each blower, run by a 261
kW (350 HP) motor, was capable of drawing 114 cm W.C. (45
inches W.C.).
The overall scrubbing system is shown in Figure 1. Gas
flow from the cupola is controlled by adjusting the combus-
tion air flow. The charge door is usually open so air con-
tinually leaks into the cupola tower. The temperature at
the top of the cupola tower is only about 175-205°C instead
of the usual 870°C temperature encountered with most cupolas.
A series of quench sprays are introduced at the entrance
of the connecting duct between the cupola tower and the scrub-
ber. About 350 £/min of fresh water is used in the quench
section. The temperature of the gas is reduced to about 35°C
by the quench sprays. The gas is saturated when it reaches
the scrubber.
As shown in Figure 2, the scrubber consists of the fol-
lowing sections:
1. A pre-spray section which sprays scrubbing liquor
into the gas stream at the rate of 470 5,/min. This pre-
spray has slight cooling effect, which may cause some con-
-------
To
Atmosphere
GO
C
•H
C W
0) C
X rt
rt
^
•i->
CO
c
•rt
£
E C
-------
Gas Outlet
18-21°C
Cooling
Decks
Separator Deck
Collector Deck
Variable Rod
Module
15°C
r T
0Q0Q0Q0000°0Q
11 i_
1,700 £/min
35°C
U
470 £/min
35°C
Cooling Water
Sprays
Cooling Water
Return
Scrubber Liquor
Return
.Scrubber Liquor
Spray
Pre-Scrubber
/Liquor Spray
»—- Gas Inlet
1,010 AmVmin
35°C
Quench/Scrubber Liquor
Return
Figure 2. Schematic of scrubber tower
-------
densation growth of the particles, and it may collect some
particles as it settles out onto the bottom of the scrubber
tower. The drops from these sprays are not carried through
to the variable rod module. The liquor returned from this
section is sent to the sludge tank.
2. The high energy section, which consists of a scrub-
ber liquor spray of 1,700 5,/min and the variable rod module
is next. The pressure drop across the variable rod module
is about 178 cm W.C. when the total pressure drop across
the whole tower is 224 cm W.C. The temperature of the scrub-
ber liquor is about 35°C and the ratio of liquid to gas vo-
lume flow rates in this section is about 1.68 £/m .
3. The collector deck, consisting of 7.6 cm of loose
2.5 cm diameter marbles, separates out the entrained liquid
from the high energy section. The returned scrubbing liquor
is split into two streams, with 80 percent going to the
recycle tank and 20 percent going to the sludge tank.
4. Above the collector deck is a plate which collects
the water from the cooling section.
5. The gas is cooled prior to leaving the scrubber
tower in a cooling section consisting of sprays and two
decks of single layer 2.5 cm diameter marbles. The cooling
water is supplied at about 15°C at the rate of 6,740 £/min
to cool the gas to about 18-21°C. There is no carryover of
entrainment from the cooling section.
-------
TEST METHOD
The performance characteristic of the National Dust
Collector Model 850 variable rod module venturi scrubber
was determined by measuring the particle size distribution
and mass loading of the inlet and outlet gas sample simul-
taneously.
For the tests performed in August 1975, modified
E.P.A. type sampling trains with in-stack University of
Washington Mark III (U.W.) cascade impactors were used
for particle measurements above 0.3 ymA. Figure 3 shows
a schematic diagram of the modified sample train. Greased
aluminum substrates were used in the impactors to prevent
particle bounce and minimize wall losses. Low velocity
impactor jet stages were used for the majority of test
runs on the inlet sampling to increase the sampling time.
The Air Pollution Technology portable screen diffu-
sion battery (A.P.T.-S.D.B.) was used for particle mea-
surements from 0.1 ym to 0.01 ym (actual).
The A.P.T.-S.D.B. uses Brownian diffusion to accom-
plish the size fractionation of particles smaller than
~0.1 ym. Because smaller particles diffuse more readily
than larger ones, successively larger particles are cap-
tured as they proceed through the battery.
Using a condensation nuclei counter (CNC) to deter-
mine the total number of particles at various points in
the battery, one can obtain data which will correspond to
a unique size distribution. The size distribution compu-
tation was based on calibration of the S.D.B. in the A.P.T,
laboratory.
Computation of size distributions from the data on
penetration was accomplished through the use of measure-
ments of density, pressure, temperature, flow rate, and
moisture, in addition to the CNC calibration factors.
-------
oo
a
THERMOMETER
CASCADE
IMPACTOR
STACK
WALL
w?
r
IMPINGER TRAIN
~\
I ICE_BA.TH |
THERMOMETERS
r~ 1 JROTOMETER
VACUUM
GAUGE
ORIFICE METER
DRY GAS METER VACUUM
PUMP
SILICA
GEL
DRYER
Figure 3. Modified EPA sampling train with in-stack cascade impactor.
-------
During an impactor run, inlet or outlet fine particle
size measurements were taken with the portable diffusion
battery. Since the system remained fairly constant during
the test period, inlet and outlet S.D.B. measurements on
different days were considered to approximate simultaneous
sampling.
Impactor blank runs on the outlet were performed
periodically to insure that the greased aluminum substrates
did not react with the stack gases. A blank impactor run
consisted of an impactor preceded by two glass fiber filters
run at identical sample conditions as the actual sampling
runs.
Gas flow rates for all tests were determined by means
of a calibrated standard-type pitot tube along with in-
stack taps for continuous wet and dry bulb temperature
measurements. Velocity traverses of the inlet and outlet
were performed according to the E.P.A. standards and
average velocity points selected for one-point sampling.
Sample flow rates were measured with the usual E.P.A.
train instruments so as to obtain isokinetic sampling.
The inlet sample port was located five duct diameters
downstream from the connecting duct entrance and one diameter
upstream of the scrubber inlet. The outlet port was located in
the outlet stack one duct diameter after a section of straight-
ening vanes. Straightening vanes were installed to counteract
the tangential spin of the gas caused by the tangential inlet
port to the stack. Sampling of the outlet could not be done
directly after the scrubber (before the fans) because of the
high negative pressure which the sampling train pump could
not handle. Velocity traverses of the inlet revealed fully
developed flow while the outlet traverse indicated that the
gas still had some tangential velocity component. Therefore,
inlet flow rate measurement should be more reliable than
outlet flow rate measurement.
-------
CONDITIONS FOR RUNS
A total of seventeen simultaneous inlet and outlet
impactor sample runs was performed on the venturi scrubber.
Also, three blank impactor runs were performed and indicated
no reaction of the greased aluminum substrates with the
filtered gases. All runs were made in-stack. Runs 1-3,
16P, and 17 were performed with high velocity jet impactor
stages while runs 4-16 were performed with low velocity
jet impactor stages to increase the sampling time on the
inlet sample. Runs 16 and 16P were performed on the same
day to compare low velocity jet impactor stages with high
velocity jet impactor stages.
During ductile iron operation, the inlet cascade impac-
tors for runs 5, 15 and 16P were heated enough to remain at
stack gas temperature. The inlet cascade impactors for runs
4, 16 and 17 during ductile operation were heated somewhat
above the stack gas temperature. For gray operation the in-
let cascade impactors for runs 7, 8, 9, 13, and 14 were
maintained at the stack temperature, while those for runs
6, 10, 11, and 12 were heated. These two types of cascade
impactor samples were taken at the inlet to measure the
actual diameter of the particles in the system due to the
water quench sprays prior to the inlet sampling port ver-
sus the dry particle diameter that would be measured with
a heated impactor (above source gas conditions).
The venturi was operated at 178 cm of w.C. pressure
drop for all the runs while the total system pressure
drop was 224 cm of W.C. As shown in Table 1, which sum-
marizes the test runs made, runs 1-5 and 15-17 were per-
formed on the ductile iron operation while runs 6-14 were
performed on the gray iron operation.
10
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Table 1. TEST RUN SUMMARY
DATE
8/19/75
8/19/75
8/20/75
8/21/75
8/21/75
8/22/75
8/22/75
8/25/75
8/25/75
8/25/75
8/25/75
8/26/75
8/26/75
8/26/75
8/27/75
8/27/75
8/27/75
8/27/75
8/28/75
8/28/75
8/28/75
8/28/75
RUN
NO.
IB
1
2
3
4*
5
6*
7
8
2B
9
10*
11*
12*
13
3B
14
15
16*
16P
17*
OPERATION
Ductile
Ductile
Gray
Ductile
Ductile
Ductile
Ductile
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Ductile
Ductile
Ductile
Ductile
SAMPLE DEVICE
Blank
C.I.
D.B.I. (IX)
C.I.
C.I.
D.B.I.(3X)
C.I.j
r T (D.B.O.(2X)
L* • i • )
C.I. }
C.I.
C.I.
Blank
C.I.
C.I.
C.I.
D.B.O.(2X)
D.B.O.(2X)
D.B.I. (IX)
C.I. '
C.I.
Blank
C.I.
C.IJ
C.I.
C.I.
C.I.
D.B.I.(SX)
D.B.I.(3X)
i
MASS LOADING
(mg/DNm3)
INLET
2,050
2,103
1,429
1,811
2,058
1,912
2,227
2,313
1,877
2,106
2,287
2,264
2,316
1,964
1,789
2,253
1,392
OUTLET
25.7
23.6
20.9
24.5
28.0
27.0
32.0
30.7
35.8
38.2
58.5
39.3
52.9
27.9
24.0
26.5
23.0
21.2
24.8
24.8
21.2
NOTES: 1. C.I. = Cascade Impactor Run
2. D.B.I.(nX) = Diffusion Battery Run on Inlet
3. D.B.O.(nX) = Diffusion Battery Run on Outlet
4. n = Number of Runs
5. B = Blank Impactor Run
6. * = Heated Cascade Impactor Above Source Gas
Temperature (Inlet)
11
-------
OPERATING CONDITIONS
The operating conditions of the variable rod venturi
scrubber for the period of sampling are shown below:
Table 2. OPERATING CONDITIONS
CONDITION
INLET SAMPLE PORT
OUTLET SAMPLE PORT'
Temperature
Velocity
Am3/inin
ACFM
DNmVmin @ 0°C
DSCFM @ 21°C
Vol !; H20 Vapor
Stat:.c Pressure
32-35°C
9.2 m/sec(30.3fps)
1,010
35,700
772
27,300
6.6
-1.1 cm W.C.
57-66°C
25.3 m/sec(83.1fps)
1,230
43,500
871
30,800
3.3
+0.38 cm W.C.
Pressure Drop Across Tower
Pressure Drop Across Venturi Module
Superficial Velocity Through
Scrubber Tower (Diameter 3.12m)
based on inlet ACFM
224 cm W.C.
178 cm W.C.
2.19 m/sec
"Outlet sample port located in exit stack after straight-
ening vane section used to reduce tangential spin of ga.s
caused by inlet (tangential) to stack. For this reason
outlet flow rates may not be as reliable as inlet flow rates
12
-------
CASCADE IMPACTOR PARTICLE DATA
Sets of data were obtained from the variable rod
module venturi scrubber as described in the Test Method
section. Fully developed flow enabled representative
one-point sampling. Identical one-point sample locations
were used for all the data points.
Particle concentration, particle size and sampled
volumes for cascade impactor runs are tabulated in the
Appendix in Tables A-l through A-18. Size distribu-
tions for the impactor runs are given in Figure A-l
through A-16 located in the Appendix.
A summary of the inlet and outlet size distribution
tests is given in Table 3.
In this report, the symbol "d " refers to aero-
dynamic diameter, which is equal to the particle dia-
meter (d ) in microns (ym) times the square root of the
particle density (p ) in grams per cubic centimeter
(g/cm3) times the square root of the Cunningham slip
correction factor (C1). The symbol "jjmA" represents
the units of aerodynamic size.
V
The symbol "d " refers to the geometric mass mean
tr o
aerodynamic particle diameter for a given size distribution
Average sample times for the inlet were three to
four minutes depending on the mass loading, while the
outlet sample times averaged approximately forty-five
minutes to one hour.
13
-------
Table 3. INLET AND OUTLET SIZE DISTRIBUTION SUMMARY
OPERATION INLET OUTLET
ag V ymA
1
2
3
4(1)
5
6(2)
7(3)
8C4)
g(5)
10
11
12
13(6)
14
15^
16
16P
17
Ductile
Ductile
Ductile
Ductile
Ductile
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Gray
Ductile
Ductile
Ductile
Ductile
0.69
0.76
0.25
0.27
1.10
1.51
0.56
0.54
0.62
1.90
0.62
0.59
0.72
0.84
0.58
0.71
0.49
. 2.0
2.0
1.6
1.5
1.7
1.8
1.6
1.5
1.6
1.6
1.6
1.6
1.6
1.6
1.5
1.7
1.8
0.48
0.52
0.52
- 0.52
0.56
0.58
0.56
0.52
0.63
0.63
0.81
0.51
0.51
0.52
0.50
0.48
0.48
0.49
1.7
1.8
1.9
1.8
1.8
1.7
1.8
1.6
.1.6
1.7
1.7
1.6
1.6
1.5
1.7
1.7
1.7
1.7
(1) Run 4 had 40% of the 5th stage holes plugged on the
inlet sample.
(2) Run 6 had 301 of the 3rd stage holes plugged on the
inlet sample.
(3) Run 7 had 30% of the 6th stage holes plugged on the
inlet sample.
(4) Run 8 had 20% of the holes plugged on stage 6 of the
inlet sample.
(5) Run 9 had 30% of the holes plugged on the inlet 6th stage.
(6) Run 13 had four holes plugged on both the inlet 5th and
6th stages.
(7) Run 15 had 50% of the holes plugged on the inlet 4th stage,
14
-------
Isokinetic sampling was undertaken for all the test
runs; however, isokinetic conditions are not that crucial
for sampling fine particles. For example, the error
caused by sampling 4 ymA particles at a velocity 501
higher or lower than the gas stream velocity would only
be about 2 or 3% of the concentration.
Single point sampling is also generally sufficient
when measuring fine particle size and concentration. The
fine particles will be distributed well in the gas stream,
except in cases where streams with different particle
concentrations have not had sufficient time to mix. To
illustrate that one-point sampling is sufficient for fine
particles, we may note that Stokes stopping distance of
a 3 ymA particle with an initial velocity of 15 m/sec
(50 ft/sec) is about 0.04 cm (0.016 inches) and for a
1 ymA diameter particle is one-ninth of that. Since the
stopping distance is the maximum that a particle can be
displaced from a gas streamline by going around a right
angle bend, it becomes apparent that fine particle dis-
tribution in the gas stream will be negligibly affected
by flow direction changes.
No inlet data were obtained for run 1 due to the ex-
cessive vacuum pulled at the start of the run which over-
loaded the impactor.
Runs 9, 10, and 11 were not used as part of the data
set because two of the five spray nozzles in the scrubber
liquor spray section were disconnected while these runs were
being made.
Analysis of the data from the inlet cascade impactor
runs was made to determine the effect heating the impac-
tors above the stack temperature had on the size distri-
butions. No definite trend of the heated impactor runs
toward smaller size distributions than the unheated im-
pactor runs could be seen.
15
-------
DIFFUSION BATTERY DATA
Diffusion battery data were taken during August 20 to
August 28, 1975. The runs were made alternately on inlet
and outlet sample locations as shown in Table 1, while
impnctor runs were being performed.
Since operation of the scrubber was fairly constant
over the testing period the inlet and outlet samples were
averaged resulting in one set of data each for the ductile
and gray operations.
Figures A-17 and A-18 in the Appendix contain the inlet
and outlet size distributions for the various tests made.
Diffusion battery penetration data are discussed in the
particle penetration section.
16
-------
Isokinetic sampling was undertaken for all the test
runs; however, isokinetic conditions are not that crucial
for sampling fine particles. For example, the error
caused by sampling 4 ymA particles at a velocity 501
higher or lower than the gas stream velocity would only
be about 2 or 3% of the concentration.
Single point sampling is also generally sufficient
when measuring fine particle size and concentration. The
fine particles will be distributed well in the gas stream,
except in cases where streams with different particle
concentrations have not had sufficient time to mix. To
illustrate that one-point sampling is sufficient for fine
particles, we may note that Stokes stopping distance of
a 3 ymA particle with an initial velocity of 15 m/sec
(50 ft/sec) is about 0.04 cm (0.016 inches) and for a
1 ymA diameter particle is one-ninth of that. Since the
stopping distance is the maximum that a particle can be
displaced from a gas streamline by going around a right
angle bend, it becomes apparent that fine particle dis-
tribution in the gas stream will be negligibly affected
by flow direction changes.
No inlet data were obtained for run 1 due to the ex-
cessive vacuum pulled at the start of the run which over-
loaded the impactor.
Runs 9, 10, and 11 were not used as part of the data
set because two of the five spray nozzles in the scrubber
liquor spray section were disconnected while these runs were
being made.
Analysis of the data from the inlet cascade impactor
runs was made to determine the effect heating the impac-
tors above the stack temperature had on the size distri-
butions. No definite trend of the heated impactor runs
toward smaller size distributions than the unheated im-
pactor runs could be seen.
15
-------
DIFFUSION BATTERY DATA
Diffusion battery data were taken during August 20 to
August 28, 1975. The runs were made alternately on inlet
and outlet sample locations as shown in Table 1, while
impactor runs were being performed.
Since operation of the scrubber was fairly constant
ove.r the testing period the inlet and outlet samples were
averaged resulting in one set of data each for the ductile
and gray operations.
Figures A-17 and A-18' in the Appendix contain the inlet
and outlet size distributions for the various tests made.
Diffusion battery penetration data are discussed in the
particle penetration section.
16
-------
PARTICLE PENETRATION
Particle penetration versus particle aerodynamic
diameter was computed and is shown in Figures 4 and 5
for ductile and gray iron operations respectively.
Penetrations for a few of the runs are not shown because
either their size distributions or their total loadings
were outside a standard deviation from the mean of the
set of data within which the run belonged.
The penetrations were calculated by a computer pro-
gram which uses a mathematical formula based on the log-
normality of the inlet and outlet size distributions.
Previous calculations of penetrations have been done by
manually and visually determining the ratio of the slopes
of the outlet and inlet cumulative mass versus particle
size curves at different particle sizes. Within the li-
mits of the particle sizes measured, the accuracy of the
log-normal penetration equation depends only on how well
the data fit log-normal distributions. Since the particle
size data have many other inaccuracies because of the dif-
ficulties of measurement, the log-normal penetration is
accurate enough, considering the ease with which it can
be used. It is also most advantageous to eliminate the
subjective errors possible with the visual method. How-
ever, when the data are not log-normal the manual method
of determining penetration must be used.
Diffusion battery data yield penetration related to
physical size while cascade impactor data are in terms of
aerodynamic size. In order to put the results on the same
basis, it is necessary to know the particle density so
that one can convert physical size to aerodynamic size
17
-------
(or vice versa). In Figures 4 and 5 a value of 3 g/cm3 for
density has been used to convert the physical diameter based
on calculated diffusion battery penetrations to penetrations
based on aerodynamic particle diameter.
The penetration plots indicate an increase in effi-
ciency for particles smaller than 0.2 ymA. From these re-
sults and published literature, it is evident that smaller,
more highly diffused particles experience increased col-
lection efficiency.
An overall penetration summary for runs 1 through 17
is presented in Table 4. Total inlet and outlet mass
loadings were taken by cascade impactors.
Although Figures 4 and 5 show penetrations for ductile
and gray iron operations separately, there was no signi-
ficant difference in the penetrations between the two oper-
ations. Likewise, the average overall penetration for both
the ductile operations and the gray operation was 1.31.
18
-------
Diffusion
Battery
0.001
0.1 0.2 0.5 1.0 2.0 5.0
PARTICLE AERODYNAMIC DIAMETER, ymA
Figure 4. Penetration versus aerodynamic particle
diameter for ductile operation.
19
-------
1.0
0.5
0.1
c>
oi 0.05
ul
o
m
2;
m
P.
0.01
0.005
Diffusion
Battery
0.001
0.1 0.2 0.5 1.0 2.0 5.0
PARTICLE AERODYNAMIC DIAMETER, ymA
:igure 5. Penetration versus aerodynamic particle
diameter for gray operation.
20
-------
Table 4. OVERALL PENETRATION SUMMARY
RUN
NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
16P
17
MASS LOADING
mg/DNm3
INLET
2,050
2,100
1,430
1,8.10
2,060
1,910
2,230
2,310
1,880
2,100
2,290
2,260
2,320
1,960
1,790
2,250
1 ,390
OUTLET
23.6
20.9
24.5
28.0
27.0
32.0
30.7
35.8
58.5
39.3
52.9
27.9
24.0
23.0
21.2
24.8
24.8
21.2
OVERALL, Pt
1
1.02
1.17
1.96
1.49
1.55
1.61
1.61
2.53
2.09
2.51
1.22
1.06
0.99
1.08
1.39
1.10
1.52
21
-------
OPACITY
Opacity for the outlet stack of the National Dust
Collector Model 850 variable rod module venturi scrubber
were taken by employees trained and certified by the State
Air Quality Control Sections. Readings were made five
times a day from 8:00 a.m. to 4:00 p.m. every two hours.
A summary of the daily average reading is presented
below in Table 5:
Table 5. OPACITY SUMMARY
DATE
8/19/75
8/20/75
8/21/75
8/22/75
8/25/75
8/26/75
8/27/75
8/28/75
Average
for Test
AVERAGE OPACITY, %
13
11
8
11
25
33
2
13
15
22
-------
ECONOMICS
The cost of installing and operating air pollution
equipment is a function of many direct and indirect cost
factors. These factors can be grouped into two cost cate-
gories initial costs and annual operating costs.
Cost data for the initial and annual cost was supplied
by the user. The unit was originally built in 1967 as a
fixed hole orifice venturi and in early 1975 was modified
to a variable rod module type to alleviate plugging prob-
lems. Shown below are the cost factors for the unit.
F.O.B. shipping and delivery charges were not available,
but should be about $15,000.
Scrubber § Auxiliaries
a. Fans, motors and motor starters $136,200
b. Ducting 88,000
c. Liquid and solid handling and treatment 45,000
d. Instrumentation 7,800
e. Electrical material 55 ,000
Total $332,000
Scrubber Installation Cost
a. Erection $120,600
b. Plumbing 61,900
c. Electrical 36,000
d. Engineering 15,500
Total $234,000
Total Initial Cost (1967 prices) $566,000
23
-------
Annual Costs include the following factors:
Operating Costs
a, Utilities $ 37,000
b. Labor 20,000
c. Supplies and materials 12,000
d. Treatment and disposal 4,000
Total $ 73,000
Maintenance Costs
a. Labor $ 10,000
b. Materials 6,000
Total $ 16,000
Plant Overhead, Space, Heat,
Light, Insurance $ 7,000
Total Annual Costs $ 96,000
24
-------
OPERATING PROBLEMS
The primary operating problems of the scrubber were
alleviated when a fixed orifice venturi high energy
section was replaced with the present variable rod module
section. Impurities in the scrap iron had caused plug-
ging of the fixed orifices.
25
-------
MATHEMATICAL MODEL
The venturi rod scrubber is essentially several Ven-
turis or orifices connected in parallel. The performance
of venturi-type scrubbers has been modeled extensively.
The most recent survey and model are by Calvert, et al
1976, which will be used here, (see Appendix B).
The pressure drop is,
AP = 1.03 x 10"3 FX Ugt (—] (2)
G
where:
AP = pressure, cm W.C.
u.p = gas velocity in the throat, cm/sec
k
Q = liquid flow rate, cm3/sec
Qp = gas flow rate, cm3/sec
F = correction factor, dimensionless
The correction factor, "Fj" is the ratio of the drop ve-
locity at the end of the throat to the throat gas velo-
city. This ratio is a function of the throat length,
drop size, and the throat gas velocity. Since a geo-
metric description of the throat region is not available,
throat length, drop size, and throat gas velocity must
be estimated. The pressure drop across the venturi is
known (178 cm W.C.), as is the liquid to gas flow rate
ratio (0.00168).
The approach taken was to assume certain values of
"F " (which is equivalent to assuming certain throat
lengths) in order to calculate the theoretical penetra-
tions and then relating these throat lengths to a pro-
bable geometry of the venturi rod module. The assumed
26
-------
values and the resultant values of other parameters,
using equation (2) and Appendix B are as follows:
F
0.5
0.75
1.0
*t
cm
5.5
24
oo
uGt
m/s
143
117
101
dd
cm
0.0088
0.0096
0.0103
Using the above table and the theoretical equation
for penetration presented in Appendix B, three penetra-
tion curves were generated. These curves are shown as
the dashed lines in Figures 6 and 7. The solid lines
are the penetrations calculated from the inlet and out-
let cascade impactor data previously presented in Fi-
gures 4 and 5. It is obvious from the figures that
the correction factor, "F!", is probably around 0.75.
This value of "F " and the corresponding throat length
(24 cm) can be related to the venturi rod geometry in
the following manner:
1. Assume spacing between the parallel rods is
equal to the rod radius.
2. Assume the angle of divergence of the jets be-
tween the rods is 20 degrees, as given in Perry,
1963 for two dimensional turbulent free jet.
3. Assume the throat begins one radius upstream
of the plane of the rod centerline.
4. Assume the throat ends where adjacent jets
intersect, based on the 20 degree jet diver-
gence angle.
The formula for the radius of a rod would then be,
r = £/ (1 + cot 10°) (3)
27
-------
1.0
0.5
o
IH
Ir-i
U
li,
o
tz;
0.1
0.05
0.01
0.005
0.001
0.2 0.5 1.0 2.0 5.0
PARTICLE AERODYNAMIC DIAMETER, ymA
Figure 6. Actual and predicted particle penetration
versus aerodynamic particle diameter for
ductile operation.
28
-------
0.001
Figure 7.
1 0.2 0.5 1.0 2.0
PARTICLE AERODYNAMIC DIAMETER, ymA
5.0
Actual and predicted particle penetration versus
aerodynamic particle diameter for gray operation,
29
-------
So, for £ = 24 cm, the rod radius would be 3.6 cm and
the rod diameter would be 7.2 cm (2.8 inches). This rod
diameter is within reason, but it should be noted that
it i:> only a very rough estimate, based on the fit between
penetration data and theory and the four assumptions
listed above. The fourth assumption probably overesti-
mates the throat length.
The model used here assumes that collection is by
inertial impaction on drops, occurring only in the throat
region of the venturi. The data agree with the model in
the range of 0.8 to 2.0 ymA diameters but show greater
efficiency below 0.8 ymA. Thus, the model is fairly
close for the larger particles of interest. However,
the particles smaller than 0.8 ymA diameter are less af-
fected by inertia than by other forces, such as diffu-
siophoresis, thermophoresis and Brown i.an motion. Diffu-
siophoresis, and thermophoresis, two of the flux/conden-
sation (F/C) mechanisms are effective in regions where
the liquid spray drops are cooler than the gas and the
gas is saturated. Some condensation may have caused
particle growth between the inlet sampling port and the
variable rod module. Here the pre-scrubber sprays may
have been a few degrees cooler than the gas, so that
enough particle growth could have occurred prior to the
venturi rod module to increase the collection efficiency
of the smaller particles.
In the cooling section of the tower F/C effects could
have caused the cooling spray drops to collect fine parti-
cles, The cool ing'spray water temperature was about 20°C
lower than the gas temperature. Collection by Brownian
diffusion is less efficient on a mass basis than the
other types and would not be important in the size regime
that was measured in these tests.
30
-------
Another section of the system where small particle
collection could have occurred was the section containing
the two blowers in series. The high velocity and extreme
turbulence in the blowers may have been effective in cau-
sing particle collection.
31
-------
REFERENCES
Calvert, S., S. Yung, and H.F. Barbarika, "Venturi
Scrubber Performance Model," A.P.T., Inc., San
Diego, California. EPA Contract No. 68-02-1328,
Task No. 13, July 1976.
Perry, J.H., Chemical Engineer's Handbook, 4th Ed.,
1963.
32
-------
APPENDIX A
Size Distribution Data
33
-------
Table A-l. INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN »1
TMHArr™
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
. . _
...
dpc
(ymA)
---
...
OUTLET
Mcum
(mg/DNm3)
23.6
23.5
23.5
23.5
23.1
22.6
22.6
13.8
4.9
dpc
(pmA)
19.8
8.7
3.4
1.7
0.97
0.54
0.31
...
. 0.810
Table A-2.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN 92
IMFACTOR
STAGE
NUMBER
Precutter
5 Nozzle
1
2
3
4
S
6
7
Filter
Sample
Volume
INLET
Mcum
(mg/DNm3)
2,050
2,050
2,030
2,030
2,000
1,910
1,690
1,140
435
Pc
(umA)
26.1
11.4
4.4
2.2
1.3
0.71
0.43
---
0.039
OUTLET
Mcum
(mg/DNm3)
20.9
20.9
19.7
19.3
18.8
18.8
18.2
11.3
3.9
dPc
(umA)
20.1
8.8
3.4
1.7
0.99
0.54
0.31
...
1.036
Table A-3. INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN *3
IMF/ '"TOP,
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNn3)
INLET
M
cum
(mg/DNm3)
2,100
2,100
2,080
2,080
2,060
1,910
1,760
1,280
169
d
Pc
(ymA)
26.6
11.6
5.5
2.3
1.3
0.72
0.43
0.019
OUTLET
M
cum
(mg/DNm3)
24.5
24.5
23.1
23.0
22.6
22.1
21.2
11.8
5.8
d
PC
(umA)
19.8
8.7
3.4
1.7
0.97
0.54
0.31
0.796
Table A-4. INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #4
IMPACTOR
STAGE
NUMBER
Precutter
5 Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,430
1,430
1,420
1,410
1,370
1,310
1,290
1,250
517
d
pc
(umA)
38.7
3.3
1.9
1.05
0.63
0.35
0.20
0.018
OUTLET
M
"cum
(mg/DNm3)
28.0
28.0
27.0
26.8
26.5
25.7
24.5
14.4
5.5
d
pc
(ymA)
---
20.4
9.0
3.5
1.8
1.0
0.55
0.32
1.005
-------
Table A-5.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #5
Table A-7. INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #7
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,810
1,810
1,760
1,720
1,710
1,690
1,690
1,590
420
d
pc
(ymA)
38.7
3.3
1.9
1.1
0.63
0.35
0.20
0.009
OUTLET
M
cum
(mg/DNm3)
27.0
27.0
24.9
24.9
24.2
23.6
23.2
16.6
6.8
d
pc
(umA)
24.2
10.6
4.1
2.1
1.2
0.65
0.38
0.711
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,910
1,910
1,840
1,820
1,810
1,740
1,620
436
268
d
PC
(umA)
44.8
19.6
7.6
3.8
2.2
1.2
0.73
0.010
OUTLET
M
cum
(mg/DNm3)
30.7
30.7
28.5
28.1
27.5
27.1
26.9
19.5
8.0
d
PC
(wmA)
24.2
10.6
4.1
2.1
1.2
0.65
0.38
0.713
en
Table A-6.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #6
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
2,060
2,060
2,050
2,050
1,980
1,090
556
132
24.0
,
pc
(umA)
46.6
4.0
2.3
1.3
0.76
0.42
0.24
---
0.025
OUTLET
M
"cum
(mg/DNm3)
32.0
32.0
30.4
30.2
29.8
29.2
28.2
21.3
6.9
H
PC
(ymA)
24.7
10.8
4.2
2.1
1.2
0.7
0.4
0.691
Table A-8.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #8
IMPACTOR
STAGE
NUMBER
Precutter
5 Nozzle
1
2
3
4
5
6
7
Filter
Sample
Vo 1 ume
(DNm3)
INLET
M
cum
(mg/DNm3)
2,230
2,230
2,220
2,190
2,140
2,080
1,470
485
78.6
V
(umA)
42.0
3.6
2.1
1.1
0.69
0.38
0.22
0.015
OUTLET
Mcum
(mg/DNm3)
35.8
35.8
32.9
32.3
32.0
32.0
31.4
25.0
9.2
dPc
(vimA)
24.4
10.7
4.1
2.1
1.2
0.66
0.38
0.520
-------
Table A-9.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #9
IMP AC TOR
o i/\uc
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
2,310
2,310
2,310
2,290
2,240
2,210
1,810
393
36.6
d
PC
(umA)
42.7
3.7
2.1
1.2
• 0.70
0.38
0.22
---
0.011
OUTLET
M
cum
(mg/DNm3)
58.5
58.5
56.5
56.5
56.3
56.0
54.5
35.5
10.9
d
PC
(ymA)
26.4
11.6
4.S
2.3
1.3
0.72
0.41
0 .595
Table A-10. INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #10
IMPACTOR
STAGE
NUMBER
Precutter
5 Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,880
1,880
1,860
1,850
1,830
1,730
1,220
286
47.6
H
PC
(umA)
43.8
3.8
2.2
1.2
0.71
0.39
0.23
...
0.010
OUTLET
M
cum
(mg/DNm3)
39.3
39.3
35. 7
35.7
35.4
35.2
34.6
22.5
5.9
,
pc
(vmA)
---
24.2
10.6
4.1
2.1
1.2
0.65
0.38
0.529
Table A-ll,
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN 011
IMPACTOR
SlAGt
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DMm3)
INLET
M
cum
(mg/DNm3)
2,110
2,110
" 2,090
2,070
2,030
1,900
1,380
298
18.6
d
PC
(umA)
43.4
19.0
7.4
3.7
2 .1
1.2
0.71
0.011
OUTLET
M
cum
(mg/DNm3)
52.9
52.9
51.3
50.9
50.9
50.8
50.4
31.3
10.7
d
pc
(umA)
24.2
10.6
4.1
2.1
1.2
0.65
0.38
0.524
Table A-12.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #12
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
S
6
7
Filter
Sample
Volume
(DNm3)
INLET
Mcun,
(mg/DNm3)
2,290
2,290
2,270
2,260
2,230
2,150
1,420
378
29.8
V
(unA)
45.0
3.8
2.2
1.2
0.73
0.40
0.23
0.010
OUTLET
Mcum
(mg/DNm3)
27.9
27.9
26.1
26.1
25.9
25.7
25.5
20.8
6.9
V
(VimA)
- - -
24.7
10.8
4.2
2.1
1.2
0.67
0.39
0.506
-------
Table A-13.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #13
Table A-15.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #15
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
2,260
2,260
2,250
2,230
2,190
2,110
1,500
388
37.9
d
pc
(ymA)
43.5
3.7
2.1
1.2
0.71
0.39
0.23
---
0.011
OUTLET
M
cum
C mg/DNm3)
24.0
24.0
23.0
23.0
23.0
23.0
23.0
18.1
7.3
d
PC
(ymA)
24.7
10.8
4.2
2.1
1.2
0.67
0.39
---
0.508
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,960
1,960
1,950
1,930
1,880
1,580
645
154
0.0
d
pc
(ymA)
7.4
3.8
2.2
1.2
0.71
0.39
0.23
0.010
OUTLET
M
cum
(mg/DNm3)
21.2
21.2
20.7
20.5
20.4
20.2
19.8
15.2
6.5
d
PC
(ymA)
24.3
10.6
4.1
2.1
1.2
0.66
0.38
0.692
CM
Table A-14.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #14
IMPACTOR
STAGE
NUMBER
Precutter
5 Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
Mcum
(mg/DNm3)
2,320
2,320
2,320
2,320
2,240
2,150
1,440
325
52.0
.
pc
(ymA)
10.6
4.4
2.5
1.4
0.83
0.46
0.26
...
0.008
OUTLET
Mcum
(mg/DNm3)
23.0
23.0
22.0
22.0
22.0
22.0
22.0
17.9
5.4
dpc
(ymA)
---
24.7
10.8
4.2
2.1
1.2
0.67
0.39
---
0.408
Table A-16.
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #16
IMPACTOR
STAGE
NUMBER
Precutter
fj Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
Mcum
(mg/DNm3)
1,790
1,790
1,790
1,780
1,760
1,700
1,234
316
28.7
dpc
(ymA)
---
43.7
3.7
2.1
1.2
0.71
0.39
0.23
0.010
OUTLET
Mcum
(mg/DNm3)
24.8
24.8
23.5
23.3
23.0
22.5
22.2
18.4
8.2
dpc
(ymA)
...
24.6
10.8
4.2
2.1
1.2
0.66
0.38
0.854
-------
Table A-17,
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #16P
IMP AC TOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
2,250
2,250
2,210
2,210
2,200
2,170
2,080
1,390
186
d
pc
(ymA)
—
25.6
11.2
4.4
2.2
1.3
0.69
0.42
0.020
OUTLET
M
cum
(mg/DNm3)
24.8
24.8
23.5
23.3
23.0
22.5
22.2
18.4
8.2
d
pc
(ymA)
24.6
10.8
4.2
2.1
1.2
0.66
0.38
0.854
Table A-18
INLET AND OUTLET SIZE DISTRIBUTION DATA
FOR RUN #17
IMPACTOR
STAGE
NUMBER
Precutter
§ Nozzle
1
2
3
4
5
6
7
Filter
Sample
Volume
(DNm3)
INLET
M
cum
(mg/DNm3)
1,390
1,390
1,380
1,380
1,370
1,330
1,230
757
224
C1
pc
(•ymA)
17.6
7.7
3.6
1.5
0.86
0.48
0.29
0.043
OUTLET
M
cum
(ng/DNm3)
21.2
21.2
20.5
20.5
20.3
20.2
20.2
15.1
6.0
,
pc
(ymA)
—
24.3
10.6
4.1
2.1
1.2
0.66
0.38
0.863
38
-------
<*D
I
as
OJ
1
3.0
2.0
1.0
0.5
0.2
=p O.INLET
AoUTLET
a.
m
E-
I
o
a:
3.0
2.0
1.0
0.5
5 10 20 30 40 SO 60 70 80 90 95 98
0.2
/\ OUTLET
2 5
0 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
MASS PERCENT UNDERSIZE
Figure A-l Inlet and outlet size distribution
for Run »2
Figure A-2 Inlet and outlet size distribution
for Hun *3
-------
a
P.
as,
m
f-c
ta
I
O!
3.0
2.0'
1.0
O.SO
0.20
0.15
)INLET
SOUTLET
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-3 Inlet and outlet size distribution
foi Run »4 (Heated inlet cascade
inpactor) .
3.0
2.0
1.0
CO
P-
oi
10
f-
ta
1
o
O!
0.50
0.20
0.15
OINLET
AOUTLET
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-4 Inlet and outlet size distribution
for Run »5
-------
rt
D.
•o
oT
I
3.0
2.0
1.0
0.50
0.20
S 10 20 30 40 SO 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-5 Inlet and outlet size distribution
for Run *6 (Heated inlet cascade
impactor).
09
D.
ctf
la
E-
ta
g
§
5.0
4.0
3.0
2.0
1.0
0.5
0.2-
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-6 Inlet and outlet size distribution
for Run f7
-------
IS
a.
as.
ta
a
u
I
§
3.0
2.0
1.0
0.5
0.2
OINLET
AOUTLET
CD
a.
a:
ta
f-
la
a
o
an
la
3.0
2.0
1.0
0.5
0.2
OINLET
AOUTLET
25 10 20 30 40 50 60 70 80 90 95 98
12 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERS1ZE
MASS PERCENT UNDERSIZE
Figure A-7 Inlet and outlet size distribution
for Run #8
Figure A-8 Inlet and outlet size distribution
for Run #9
-------
a
P.
a
o
B!
3.0
2.0
1.0
0.5
0.2
OlNLET
Z^OUTLET
5 10 20 30 40 50 60 70 80 90 95 98
a.
ta
5.0
4.0
3.0
2.0
1.0
0.5
Q
O
o:
0.2
0.5 125 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
MASS PERCENT UNDERSIZE
Figure A-9 Inlet and outlet size distribution
for Run #10 (Heated inlet cascade
impactor).
Figure A-10 Inlet and .outlet size distribution
for Run #11 (Heated inlet cascade
impactor).
-------
CO
O.
CA
ia
n
u
z
§
O
oi
w
2.0
1.0
0.5
0.2
1 2
10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-ll Inlet and outlet size distribution
for Run #12 (Heated inlet cascade
iropactor).
2.0
1.0
0.5
n
u
z
g 0.2
a. i
w A
OINLET (
Z\ OUTLET
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-12 Inlet and outlet size distribution
for Run #13
-------
CD
P.
Z
Q
O
oi
la
2.0
1.0
0.5
0.2
OINLET
Z\ OUTLET
12 S 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
ca
o,
a.
tu
E-
Q
O
3.0
2.0
1.0
0.5
0.2
OlNLET
Z\ OUTLET
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-13 Inlet and outlet size distribution
for Run #14
Figure A-14 Inlet and outlet size distribution
for Run #15
-------
(9
CX
3.0
2.0
1.0
0.5
a
u
§
PS
9.2
(J INLET
INLET HEATED
A OUTLET
12 5 10 ^20 301
MASS PERCENT UNDERSIZE
Figure A-15 Inlet and Outlet size distribution
for Run 016
2.0
0)
P.
at
ta
H
I
§
ra
1.0
0.5
0.2
=^o
INLET
2 5 10 20 30 40 50 60 70 80 90 95 98
MASS PERCENT UNDERSIZE
Figure A-16 Inlet and outlet size distribution
for Run #17 (Heated inlet cascade
impactor).
-------
0.3
0.2
S 10 20 30 40 50 60 70 80 90 95 98
NUMBER UNDERSIZE
Figure A-17 Diffusion battery data for ductile operation
0.02
2 5 10 20 30 40 50 60 70 80 90 95 98
NUMBER UNDERSIZE
Figure A-18 Diffusion battery data for gray operation
-------
APPENDIX B
Venturi Scrubber Performance Model
48
-------
VENTURI SCRUBBER PERFORMANCE MODEL
Calvert, et al., 1976 have performed a literature
review and evaluation of all available venturi scrubber
performance models. Their conclusions and recommended
performance model are presented below.
(1) Even though each investigator presented a dif-
ferent equation for the prediction of particle collection
in a venturi scrubber, most of these equations can be
reduced to the same basic model, i.e.,
where Pt(d ) = penetration for particles with diameter d ,
fraction
u = relative velocity between dust and drop,
cm/sec
Up = gas velocity, cm/sec
d, = drop diameter, cm
n = single drop collection efficiency, fraction
1JUC L.1.LI. JL -L UW 1 O. L.^ , U'l' ' '
z = length, cm
Q = liquid volumetric flow rate, cm3/sec
W
(2) A generalized method for applying equation B-l to
predict particle collection in a venturi was developed.
(3) Particle collection predicted by equation B-l
agrees satisfactorily with performance data.
(4) Most of the particle collection occurs in
the venturi throat. The solution to equation B-l for the
venturi throat, using the inertial collection efficiency
correlation, and assuming a zero initial drop velocity, is
49
-------
In Pt(dp)_
B
K/l-u*\+ 0.7
P°\
- 5 02 K°'5 1-u*
b.oz K i ud
po
(B-2)
where u5
a
= 21-
Pt (d ) = penetration for particles with diameter d ,
P P
fraction
u
u
'Do
* =
volumetric liquid flow rate, cm3/sec
liquid density, g/cm3
gas density, g/cm3
drag coefficient obtained from the "standard curve'
dimensionless drop velocity
u,
u
Gt
u
K
Gt
-po
= drop velocity, cm/sec
= gas velocity in the throat, cm/sec
= inertial parameter based on throat velocity
C' dp
d
50
-------
C' = Cunningham slip factor
d = particle diameter, ym
p = particle density, g/cm3
yG = gas viscosity, poise
d, = drop diameter, cm
L = dimensionless throat length
L =
2 dd PL
Equation B-2 slightly under estimates the particle
collection occurring in a venturi scrubber. For most
industrial venturi scrubbers, particle collection can be
predicted closely by neglecting the first term in the
right hand side of equation B-2.
(5) Pressure drop predictions by the modified Calvert's
equation and by Boll's equation agree with experimental data.
The modified Calvert's equation has the following form,
AP = 1.03 x 10"3 F! u 2( L J (B_3)
where AP = pressure, cm W.C.
uGt = &as velocity in the throat, cm/sec
'L
QT = liquid flow rate, cm3/sec
Qr = gas-flow rate, cm3/sec
F! = correction factor, dimensionless
2 4- 20'5
Fl = = 2 l - X2+ (X4- X)
UGt I
3 ttCDQ PG .
16 d P
51
-------
u, = drop velocity at the exit of the throat, cm/sec
H = throat length or distance between liquid
injection point and the exit of throat, cm
d, = drop diameter, cm
PG = gas density, g/cm3
p. = liquid density, g/cm3
Cp = drag coefficient at the liquid injection point.
(6) The use of a drag coefficient from the "Standard
curve" gives a better fit between model and experimental
data than does Ingebo's correlation.
(7) The drop diameter can be assumed to be the Sauter
mean diameter calculated from the Nukiyama-Tanasawa relation,
52
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-6QO/2-76-282
3. RECIPIENT'S ACCESSION'NO.
4. TITLE AND SUBTITLE
National Dust Collector Model 850 Variable Rod
Module Venturi Scrubber Evaluation
5. REPORT DATE
December 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Seymour Calvert, Harry F. Barbarika, and
Charles F. Lake
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Air Pollution Technology, Inc.
4901 Morena Boulevard, Suite 402
San Diego, California 92117
10. PROGRAM ELEMENT NO.
1AB012; ROAP 21ADM-029
11. CONTRACT/GRANT NO.
68-02-1869
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 ANC
Final; 8/75-8/76
ND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES j£RL-RTP project officer for this report is D. L. Harmon,
919/549-8411 Ext 2925, Mail Drop 61.
is. ABSTRACT The reporj. gives results of 3i measurement of the performance of a National
Dust Collector Model 850 variable rod module venturi scrubber at an industrial instal-
lation. Fine particle collection efficiency as a function of particle size was computed
from the data collected. The scrubber tower was operated at 1010 std cu meters/min
at 35 C with a total pressure drop of 224 cm (88 in.) W. C. with a pressure drop
across the venturi module of 178 cm (70 in.) W. C. The emission source was an iron
cupola which processes both ductile and gray iron, with the latter producing a higher
grain loading. The ductile iron source particulates had a mass mean diameter range
of 0.25-0. 84 micrometers A (aerodynamic particle diameter) with a standard devia-
tion range of 1. 5-2.0. The gray iron source particulates had a mass mean diameter
range of 0. 54-1. 9 micrometers A with a standard deviation range of 1. 5-1. 8. The
overall average collection efficiency for ductile iron melting was 98. 7%. For gray
iron melting, the average collection efficiency was also 98. 7% even though the cu-
pola emission was lower for ductile iron.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. CCSATI Field/Group
Air Pollution
Dust Collectors
Scrubbers
Evaluation
Iron and Steel Industry
Furnace Cupolas
Nodular Iron
Gray Iron
Air Pollution Control
Stationary Sources
National Dust Collector
(Model 850)
13B
13A
07A
11F
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
63
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
53
------- |