PROTOTYPE CONSTRUCTION AND
            FIELD DEMONSTRATION





                 OF THE




      PARALLEL CYCLONE SAMPLING TRAIN



       FINAL REPORT  Contract 68-02-0258
waiter c. me crone associates, inc.

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                              Report to
                     Environmental Protection Agency
                       Durham Contract Operations
                         Research Triangle Park
                          North Carolina 27711
                   PROTOTYPE CONSTRUCTION AND

                        FIELD DEMONSTRATION

                               OF THE

                 PARALLEL CYCLONE SAMPLING TRAIN

                  FINAL REPORT   Contract 68-02-0258
Date:   15 December 1972

MA Number:         2425

Copy      of
        waiter c. me crone associates, inc.
         2820 SOUTH MICHIGAN AVENUE • CHICAGO, ILLINOIS 60616

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              FINAL REPORT FOR CONTRACT 68-02-0258 (MA 2425)
 INTRODUCTION

                  This final report is submitted in fulfillment of our contrac-
 tual agreement under contract 68-02-0258, and summarizes the detailed infor-
 mation included in our four monthly status reports submitted throughout the
 contract period.  The purpose of the contract was to construct and test a pro-
 totype parallel-cyclone particle sampler which we had designed under contract
 EHSD-71-25.

 PROTOTYPE CONSTRUCTION
                  During the first two months of the contract the design of the
 parallel cyclone sampling train was reviewed, the necessary components to be
 purchased were ordered and the construction of the cyclones and by-pass filter
 was completed.  Layout and assembly of the final prototype system was some-
 what modified from the initial designs; assembly was initiated in June and com-
 pleted in September.  Although the design  details of the unit have been detailed
      i
 in our monthly reports, some of the important features are summarized here.
                  The parallel multicyclone sampling train consists of five
 main units: the  sampling box,  two heat exchangers and two air flow control
 boxes.  Figure  1 shows how the cyclones and by-pass filter are combined with
 the gas pumping and  control systems.  The system components are all  con-
 structed from corrosion-resistant  materials.  For example,  the cyclones and
by-pass filter are nickel-plated brass, the condenser-evaporater-chiller sec-
 tions of the heat exchangers are type 304 stainless steel,  the  gas pumps are
 Teflon coated; sour gas meters are used in place of regular gas meters, and
 stainless steel and Teflon tubing are used  in the gas control systems.
                  The physical appearance of the sampler  is illustrated in
 Figures 2, 3, 4 and 5.  Figure 2 shows the relative  size and shape of the by-
pass filter holder and the three types of cyclones.  Figures 3 and 4 show the.
assembled sampler unit and Figure 5 shows the assembled sampling train as
                                          waiter c. me crone associates, inc.

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 set up for laboratory testing.
                   Our initial design for the system included the construction of
 a 6-cfm gas pumping and metering system to be utilized in conjunction with the
 parallel cyclone samplers.  It was originally thought that the pump, gas meter
 and the other associated accessories (i. e.,  pyrometer, manometer, orifice
 meter etc.) could be housed in the same container.  However,  the control box
 was estimated to weigh over 90  pounds, too heavy for field use.  The initial con-
 figuration was somewhat modified and the final configuration is shown in Figures
 1 and 5.  The 6-cfm pump and gas meter were housed in the  cyclone air-flow
 control box and the other accessories were housed in the filter air-flow control
 box.
 PROTOTYPE TESTING
                   Prototype testing was actually divided into five separate tasks.
 First, the theoretical and experimental operational characteristics of the three
 cyclone types (T-1B, T-2A and  T-3B) were compared.  Second, the manifold
 functioning was experimentally verified. Third, so that any  necessary design
 modifications could easily be made before final assembly, operational tests were
 made on the individual cyclones  prior to assembly into the sampling train.
 Fourth, the assembled sampling train was  tested using the wind tunnel under
 simulated wet scrubber conditions.  And fifth, the sampling train was field
 tested at the TVA  Wet Limestone Scrubbing Facility,  Paducah, Kentucky.
   Operational Characteristics Comparison
                  The variations of pressure drop (AP) and particle cut-off
 size were first calculated for different flow rates and then the cyclones were
 tested to determine the actual values under operation.  The pressure drop across
 each cyclone was measured with a manometer and the instantaneous flow rates
were measured with a calibrated orifice meter at various flow rates (Q) ranging
from 0.2 to 4.5 cfm under room  conditions of 72 °F and a relative humidity of 60%.
                  In order to compare the actual pressure drops with the
theoretically predicted values for the cyclones, the Q vs.  AP curves for each
have been plotted on Figures 6,  7 and 8. Figures 6 and 7 show that the actual
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                                                                            - 2

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pressure drops across the T-1B and T-2A cyclones agree very well with the pre-
dicted values.   In fact, the best fit curve of experimental data for T-1B  very
nearly coincides with the predicted curve.  The actual pressure drop curve for
T-2A parallels  the theoretical one and differs by about 35% for flow rates rang-
ing from 0.4 to  1.0 cfm.  Although the actual pressure drops across the  T-1B
and T-2A agree with the predicted values, the actual and theoretical pressure
drops across T-3B do not agree well; the actual pressure drops are about 15
times greater than the predicted values (Figure 8).  The differences are attri-
buted to the pressure drop across the manifold atop the T-3B cyclone, since this
pressure drop was not considered during the calculations.
   Manifold Testing
                   The manifold was designed to split the intake air into four
controlled volumes; one into each of the three cyclones and  one into the by-pass
filter (see Figure 3). It must split the  gas stream into four  volumes in propor-
tion to the required quantit3' of air flow for each cyclone. By varying the filter
flow,  isokinetic sampling can be achieved.  The manifold was designed so that
the particle loading and size distribution would be unchanged in each of the four
gas streams. Two experiments were performed to test this requirement.
                   The tests were made  at room conditions with various flow
rates: one test  with equal air flow through each of the four units (three T-1B and
one T-2A  cyclone) and another test with different flow rates.  For equal  rates,
a flow of 0.75 cfm was chosen; and for the second set of conditions,  the flow rates
were set at 0.3, 0.6, 0.9 and 1.2  cfm so that the proportion  of air volume was 1,
2, 3 and 4, respectively. Air flows through the four units were properly ad-
justed prior to  the tests by using manometers and the actual pressure drop  curves
presented in Figures 6 and 7.  Since only  three manometers were available, the
flow rates through only two units and the total flow rate through the whole system
were continuously monitored.
                   In these tests, the flyash and limestone mixture of particles
was generated by an acoustic dust feeder  and then passed through the precollec-
tor, the manifold, the cyclones, and the by-pass filter.  At the end of each test,
the weight of particles  collected by  the precollector, the cyclones  and by-pass
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                                                                           - 3

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 filter were weighed and their size distributions were measured.  Although the
 experimental data did not agree perfectly with the theoretical requirement, the
 manifold worked reasonably well.  The deviation of experimental and theoretical
 results was believed due  to the slight variation of flow rates  during the test.
 The flow rates through two of the units might have been slightly reduced during
 the test due to the pressure drop developed by the increasing dust loading of the
 filters.
                   The manifold functioning was also evaluated from the unifor-
 mity of particle size distribution passing through the four manifold outlets. The
 actual size distributions at the four manifold outlets  agree very well under both
 sets of flow rates.   Slight variations in the size distributions are believed due to
 errors in particle sizing  and flow control variations.
                   In short, the results obtained from the manifold tests indicate
 that the  manifold is capable of splitting dust-laden air into the four outlets with-
 out changing the  size distribution and mass loading of particles significantly.
 The manifold was therefore considered well designed and no  modifications  were
 necessary.
   Component Testing
                   In order to simulate stack conditions with a wind tunnel and
 to measure particle size  distribution with a Climet particle counter, it was im-
 portant to obtain  information on the  function of these two pieces of equipment
 under such conditions.
                   The tests indicated that the Climet and wind tunnel func-
 tioned properly.  However, when we attempted to simulate the stack conditions
 at the inlet and outlet of the wet scrubber with the wind tunnel and obtain a  cali-
bration curve for each cyclone, the  attempt was unsuccessful due to the follow-
 ing difficulties:
         1)   In simulating the outlet stack condition of 90.5% relative
             humidity,  the probe was plugged with condensate and the
             optical sensing chamber in the Climet particle counter was
             flooded with water when the wind tunnel air was  driven
             through the system.  This caused the particle counter to
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              fail.
          2)  In simulating the inlet condition, 1.7% relative humidity,
              in which flyash and limestone particles were added to the
              wind tunnel, the sensing chamber of the Climet particle
              counter was overloaded with particles,  and hence the
              counter also failed.
                    Due to these difficulties, particle size distribution measure-
  ment was shifted from the Climet particle counter to the Millipore TrMC particle
  counter.
                    Wind tunnel conditions during component testing closely si-
  mulated the inlet condition of a wet scrubber: 300 °F and 112 °F of dry and wet
 temperatures,  with 147 grams of particles added to the wind tunnel and circu-
 lating at 3000 fpm.  The dust-laden air of  the wind tunnel was  drawn through the
 probe,  passed through the cyclone and filter and then measured with an orifice
 meter.  A i/8-in. probe was used for the T-1B and T-2A cyclones, whereas
 a 3/8-in. probe was used for the T-3B cyclone.  Various flow  rates ranging
 from 0.3 to 3 cfm were used for the three cyclone models.  Only one test was
 made under each condition with a sampling time of 30 minutes  in each case.  In
 order to compensate for the loss due to particle decay in the wind tunnel, about
 3 grams of particles (flyash and  limestone mixture) were added to the wind
 tunnel prior to each test. At the end of each test,  the particles collected by  the
 cyclone and the absolute filter were respectively weighed and their size distri-
 butions determined with the TT MC counter.
                   Knowing the quantity and size distribution of those particles
 collected and of those  that passed through the cyclone, the collection efficiency
 of each cyclone  was determined.   These results are plotted in Figures9,  10 and
 11.
                  The cut-off size of each cyclone —the particle size with 50%
 collection efficiency —was then easily obtained from these collection efficiency
 curves.  The cut-off sizes for each of the cyclones at various sampling flow
 rates are presented  in Table land are plotted in Figures 12, 13 and 14. In
order to compare the experimental and theoretical cut-off sizes of each cyclone,
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the AP vs. X   curves in figures 6, 7 and 8 were transformed into Q vs. X
            J"                                                         50
curves and superimposed on Figures 12,  13 and 14.  The theoretical cut-off
sizes of these cyclones corresponding to the flow rates used in the tests are
also presented in Table 1.
                  Since Die 50% efficiency sizes (d  ) obtained from laboratory
                                                 oU
tests do not agree well with the design values, we were somewhat disappointed
with the results obtained in this preliminary calibration test.  Theoretically
the d  should decrease progressively as flow rate  increases,  as  shown by the
solid curves on these figures.  However,  this was not consistently observed in
our tests.  Also,  the cross-overs of collection efficiency curves for a given
cyclone under various test flow rates as appeared on Figures,  10  and 11 were
not expected.
                  The differences  between the theoretical and experimental
d,_0 value obtained are believed attributable to the following factors:
        1)  Cyclone construction:  Cyclone dimensions  calculated
            by optimization procedures  in cyclone design do not
            always  give round numbers  for machining.  Therefore
            slight modifications were made during machining, par-
            ticularly for the cyclone inlet and outlet dimensions.
            Since the inlet and outlet dimensions affect  the collec-
            tion  efficiency of a cyclone, these design modification
            variances would cause the collection efficiency to vary
            somewhat.
        2)   Variation in particle density used in the cyclone design
            and experiment:  A density of 2.4 gm/cc for the glass
            beads was assumed in  the cyclone design, whereas the
            density  of the flyash and limestone  particles used in the
            experiments ranged from 1 gm/cc to over 6 gm/cc.
            Since d   is a function of particle density,  particle den-
                  ou
            sity variations would effect the resultant d  . value.
                                                    50
        3)   Variation in particle concentration  and size distribution
            in the wind tunnel:  Testing of the wind tunnel has shown
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              that the particle concentration and size distribution vary
              from time to time during experiments.  Therefore, since
              the collection efficiency of a cyclone is related to mass
              loading and particle size,  variations in particle concentra-
              tion and size distribution in the wind tunnel would also vary
              the collection efficiencies.
         4)   Particle sizing and counting:  Since the ^MC particle counter
              is accurate only for particles greater than 1 /im in size,
              particles smaller than 1 jLtm were manually counted by com-
              paring their images with images of larger known particles.
              Therefore,  an error could have possibly been  introduced
              during particle counting and sizing.
         5)   Random error in experiment: Since only one test run was
              performed under each experimental condition and since a
              number of variables are involved in the determination of
              cyclone collection efficiency,  the results  obtained from each
              single test would not likely represent the  true value.  Addi-
              tional testing would be required to obtain  a statistically
              meaningful result.
                   Although the preliminary cyclone calibration data do not agree
well with the  theoretical predictions,  the cyclones were capable of separating
particles below 10 ^m.  We fell that whether the experimental data agree with the
theoretical prediction is immaterial as long as the actual cyclone cut-off sizes
are known. The data obtained in this preliminary calibration served as a guide
in determining the approximate flow rates for the desired  cut-offs in our labo-
ratory prototype test.
   Assembled Prototype Testing
                  The main purpose of  the assembled  sampling train laboratory
test was to establish the actual cut-off values  for the three cyclones at flow rates:
1.2 cfm for cyclone No. 1 T-1B; 0.5 cfm for No.  2 T-1B; 0.5 cfm for T-2A;
2.7 cfm for cyclone T-3B; and 0.5 cfm for the by-pass filter. The approximate
size cut-off for each cyclone  corresponding to these flow rates is 0.5, 1.4 and
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6 p.m, respectively.  In addition,  the laboratory prototype test was also intended

to test the mechanical performance of the sampling train components: gas flow

control and metering system, heating controls, temperature monitoring system

etc.

                  The prototype tests were performed using the wind tunnel at

the same conditions as in the individual component tests.  The wind tunnel at-

mosphere closely simulated the inlet condition of a wet scrubber: 300 °F and

112°F of dry and wet temperatures with 147 grams of flyash and limestone par-

ticles added to the wind  tunnel and circulating at about 3000 fpm.  A 1/2-in.

heated probe with a  1/2-in. button hook sampling nozzle was used in the test.

The operation procedure for the sampling train is briefly described as follows:

        1.  Weigh  four 47 mm filters with a microbalance;

        2.  Mount  the filters on the by-pass filter holder and the filter
            holders attached to each cyclone;

        3.  Assemble the  sampling cyclones in the sampling box and
            connect the gas transport system;

        4.  Heat the sampling probe and sampling box to 250 °F;

        5.  Adjust the flow rate  through each sampling cyclone by
            referring to the pressure vs. flow rate curve for each
            cyclone as  presented in Figures 6-8.  To obtain 1.2 and
            0.5 cfm air flow through cyclone T-1B and 0.5 through
            cyclone T-2A, a corresponding pressure drop of 26,
            4.5 and 0.13 inches  of water is required.  Since the
            three cyclones draw air from the same inlet, flow rate
            adjustment in one cyclone would slightly vary the  flow
            rate  of others.  Careful re-adjustment of the three flow
            rates through the three cyclones is therefore required.
            This can be achieved by nearly simultaneously adjusting
            the three flow  control valves located on the top of the
            sampling box;

        6.   Record the initial readings of the two  gas meters  and then
            start the two pumps simultaneously;
        7.   Adjust  the by-pass filter air flow to obtain isokinetic sam-
            pling conditions.  This can be achieved by adjusting the
            pressure drop across the orifice meter to the correspond-
            ing pitometer reading.

        8.   Record temperature readings on the two gas meters;

        9.   Maintain a constant flow rate through each cyclone during
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              the sampling period;
         10.  At the end of each sampling period, reweigh all filters and
              all samples collected by each cyclone.
                   Particle size distributions of the cyclone and filter samples
 were determined by optical microscopy.  The collection efficiency of each cyclone
 at the test flow rate was established based on the quantity and size distribution
 of particles collected by each cyclone and filter.  Results of the collection effi-
 ciency calculations are plotted in Figures 15, 16, 17 and 18.
                   It is seen from these  figures that the particle collection effi-
 ciency data obtained from the three runs  for a given cyclone at a given flow rate
 fall short of a smooth curve, especially those for cyclones T-2A and T-3B. It
 is, in fact, difficult to fit a curve to the experimental data for these two cyclones.
 Despite these scattered experimental data,  these figures indicate that the cut-
 off sizes of cyclones  T-1B and T-2A are  very close to the expected values. How-
 ever,  the cut-off size of cyclone T-3B, about 3.5 Mm, was considerably smaller
 than the expected value of 6 jum.   This is probably due to the fact that more air
 flow than the preset flow of 2.7 cfm  was drawn through cyclone T-3B during the
 test.   The  observed actual flow rate through this cyclone was 2.93  cfm.
                  In summary,  the results  of the laboratory prototype  tests
 show  that the  parallel multicyclone particle sampler is capable of separating par-
 ticles  in the desired size ranges  provided the flow rate through each cyclone is
 well controlled.
   Field Demonstration of the Parallel  Multicyclone Particle Sampler
                  The field demonstration of the parallel multicyclone particle
 sampler was performed on October  16 and 17 at the TVA power station in Paducah,
 Kentucky.  The sampling procedures in the field test were essentially identical
to the laboratory prototype test.  Three samples were taken, both from the inlet
and outlet of the wet scrubber.
                  Knowing the weight of  the particles collected by each cyclone
and filter,  the cumulative particle size  distribution (by mass) of the aerosol
drawn  through the probe was calculated.
                  The results of the sampling train field test were very satis-
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 factory.  According to the design criteria of the wet scrubber, 50 cumulative
 weight percent of the particles at the scrubber inlet should be smaller than 11 pun
 and all particles in the outlet should be less than 5 ^m.  This means that at the
 flow rate set in the field test a substantial fraction of particles would be collected
 by the precollector at the inlet.  It also implies that practically no particles would
 be collected by the precollector and  only a very small fraction of particles would
 be collected by cyclone T-2A at the outlet.  These were verified by the field test
 data.
                   The anticipated performance of the parallel multicyclone par-
 ticle sampler was also indicated by the distinct color of the particles collected by
 cyclone T-1B and its back-up filter.  While  the particles collected by the cyclone
 appeared gray, those collected by the back-up filter were black, indicating flyash
 and a fine oil mist, respectively.
                   Determination of particle size distribution by use of this
 sampler was also found to be very promising.  The data indicate that the parallel
 multicyclone particle sampler is capable of  providing sufficient data for the es-
 tablishment of cumulative mass curves.  The outlet size data obtained in Paducah
 fits very well to a straight line when plotted on arithmetic probability paper.
 This indicates the particle mass size distribution is "normal".  Since a straight
 line can be both fairly well fitted to  the inlet data plotted on an arithmetic proba-
 bility and a log probability paper, the actual pattern of particle size distribution
 at the inlet was inconclusive.

 SUMMARY
                   Although  the parallel multicyclone particle sampler was found
 capable of providing sufficient data to establish particle size distribution of an
 aerosol,  the application of the sampler was limited by sampling time.  We found
 in the laboratory prototype tests  and the field demonstration that the pressure
 drop across the back-up and  by-pass filters  developed quickly and a constant flow
 rate through each cyclone was maintained only in the first few minutes.  This
 means that, if gravimetric analyses are desired, extended sampling times might
be necessary and the sampler would therefore lose  its accuracy in such instances.
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                  To help correct this dcficiencj', modification of the sampling
train is recommended.  Although a pump of larger capacity would extend the sam-
pling time, the increased volume and weight make this modification undesirable.
The best way to extend the  sampling  time is to enlarge the filter holders from the
present 47 mm to 3 inches.
                  Another important consideration in the performance of this
sampler is an accurately known cut-off size for each cyclone at operational flow
rates.   In the laboratory prototype test, reproducibility of cyclone collection effi-
ciency data was not very good due to the limitation of three test runs.  Since the
establishment of particle size distribution by the use of this equipment depends
very much on the actual cut-off size  of each cyclone, we recommend a more com-
plete set of calibration experiments to  measure the collection efficiency of each
cyclone.
                  We  acknowledge that the successful development of the pro-
totype parallel multicyclone sampling train was through the direct efforts of
Drs. Walter C. McCrone and Hsing C.  Chang.
                                             Respectfully submitted,
                                             Donald A.  Brooks
                                             Executive Vice President
                                          waiter c. me crone associates, inc.
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TABLE 1
Type of
Cyclone
T-1B



T-2A



T-3B

Comparison of experimental cut-off
theoretical cut-off sizes of cyclones
sampling flow rates.
Flow Rate
(cfm)
0.3
0.5
0.8
1.0
0.4
0.6
0.8
1.0
2.0
2.5
3.0
sizes with
at various
Cut-off size (^m)
Experimental
2.1
1.3
1.8
1.0
6.5
2.6
2.3
2.6
8.5
4.7
5
Theoretical
1.7
1.05
0.65
0.51
6.0
3.6
2.7
2.2
9
7.5
6.4

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              Sampling box
3re-collector
    and
  manifold
                                               Heat
                                             exchanger
                                               Heat
                                             exchanger
Cyclone air
flow control
    box
 Filter air
flow control
    box
FIGURE 1.   Block diagram of the McCrone parallel multicyclone sampling train.

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^^^^ ^Br
   FIGURE 2   Shape and relative size of by-pass filter
                 holder and sampling cyclones
        FIGURE 3   Assembly of sampling cyclones
                                                                 - 14

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  FIGURE 4   Assembled sampling box
FIGURE 5  Complete train of parallel multicyclone
                     participate sampler
                                                            - 15

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      -p-;-:
      te
                                   :::::.-._.vi':i:: Best fil curve of  .--_!..:".:.": :

                          •;...:.	frrzr:";:~~:i~ experimental data;.-";-.
                          "                            i       i      :
                                 • ••'• •-'•  :   ' -   i••' •• " ;
                                                           Theoretical precHction
0.1
                                 8      10     12 """   14     1G     18


                                    Pressure Drop (in. of water)


                  FIGURE 6      Comparison o! actual pi'cssure drop  with
                                 theoretical pressure drop across cyclone

                                 T-1B
24     2G
                                                                                          - 1G

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3  .... n
                                            J'cst lit curvd of  -
                                                  i mental data .

0.1
                                   Pressure Drop (in. of water)

              FIGUUK 7       Comparison of actual pressure drop with
                             theoretical pressure drop across cyclone
                             T-2A
                                                                                   - 17

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3
rt
                                           Theoretical prediction
   0.01     0.02      0.04  O.OG  0.080.1
            0.2
0.-
                                     Pressure Drop (in. of water)
                FIGt'RE 8
Comparison of actual pressure drop with theoretical

pressure drop across cyclone T-3B and manifold

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FIGURE 9       Particle collection efficiency of cyclone T-1B

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FIGURE 10
Particle collection efficiency of Cyclone T-2A

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                                         . .  . . . .
                       ,
                            Particle Size; I (inri)'. • \

FIGURE 11     Particle collection efficiency of cyclone T-3B

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     0.2
FIGURE 12
0.4
   O.G
Flow Kate, (efm)
Comparison of oqioinmonta] cut-off si/-e \vith tlieorotic
cut-off size of cyclone T-1B.
                                          il
                                                                             - 22

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    9—


    8_


    7~



    6_.




    5_.
    4
O
O
o
N
^H
w

0)
I—(


!
rt   ,
ft   1-
0 2
FIGURE 13
                                            D7G          0.8

                                            Flow Rale, (cfm)
                                                    1.0
                                  Comparison of experimental cut-off size with theoretical

                                  cut-off size of cyclone T-2A.

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FIGURE  14      Comparison of experimental cut-off size with theoretical
                cut-off size of cyclone T-3B.
                                                                           - 24

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           lOOi
            80-
                  iJV-l-
                                                                             : 1.:: :
        o
        o
_0
• *
o
o
            CO-
            40
                                                              -?-
                                                                   tSe
                                                                             •!,:  :
                                                                             donc
            20-
                                                                                                   —j—-'
                                                                                       •I-: !::
             o-w
                                               6            8

                                                  Particle Size
                                                                                 10
12
14
16
tc
in
                             FIGURE 15    Particle collection efficiency of cyclone T-1B
                                                 operated at a flow rate of 1. 2 cfm

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               100
           w
           CH
           O
                          i   . ;..::.:: !..::
                         •J,  [:.!':.. I- :::!•:::!::::;•:::
                                                                Particle Size
i
to
FIGURE 16    Particle collection efficiency of cyclone T-1B
                  operated at a flow rate of 0.5 cfm

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              100
           o
           U
               80 i
                                                      •  . ' 1 . t • 1 • • - . I - i .  . -    .:...-(
to
-o
                                           468


                                                 Particle Size (Mm)
                                    FIGURE 17   Particle collection efficiency of cyclone T-2A

                                                    operated at a flow rate of 0.5 cfm

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           100
            80
        o
        c
        o

        'o
        o
        o
        I—*
        I—I
        o
        u
                                                       Particle Size
t-o
cc
                                    FIGURE 18   Particle collector efficiency of cyclone T-3B

                                                     operated at a flow rate of 2.7 cfm

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