PB   248  220


PARTICULATE COLLECTION EFFICIENCY  MEASUREMENTS  ON
THREE  ELECTROSTATIC  PRECIP ITATORS

Grady  B.  Nichols,  et  al

Southern Research  Institute
P re pared for :


Environmental Protection Agency


October  1975
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                               TECHNICAL REPORT DATA
                         fFleaif read Instructions on the revche before eomplttingj
1. REPORT NO.
 EPA-600/2-7
 4. TITLE AND SUBTITL
                056
 Particulate Collection Efficiency Measurements on
    Three Electrostatic Precipitators
   UTHOR*. Grady B  Nichols and Joseph D. McCain
 Southern Research Institute, Birmingham, AL 35205
 The M.W. Kellogg Company
 1300 Three Greenway Plaza
 Houston, Texas 77046
 12. SPONSORING AGENCY NAME AND ADDRESS
 EPA. Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC  27711
                                                    3. RECIPIENT'S ACCESSION-NO.
                                                    5. REPORT DATE
                                                    October J975
                                                   ,6. PERFORMING ORGANIZATION CODE
                                                    SORI-EAS-75-428 (3296-H)
                                                    0. PROGRAM ELEMENT NO.	
                                                    1AB012; ROAP 21ADL-004
                                                    68-02-1308, Task 21
                                                    13. TYPE Or REPORT AND PERIOD COVERED
                                                    Final Task: 7/73-7/75	
                                                    14. SPONSORING AGENCY CODE
 IS. SUPPLEMENTARY NOTES
      " ,-• The report gives results of a determination of the operating characteristics
 of three full-scale electrostatic precipitators (ESP's), made to provide definitive
 data on their performance.  The measured performance of these ESP's was compared
 with the theoretically predicted efficiencies computed by an ESP mathematical model.
 Field measurements of total inlet and outlet mass concentrations, particle size
 distributions, and electrical data were used for these comparisons.  Descriptions of
 the  measurement procedures and the mathematical model are included.  Two of the
 ESP's were at  electric power generating stations; the third, at a cement kiln.
                                            TOG&S
                            KEY WORDS AND DOCUMENT ANALYSIS
                DESCRIPTORS
                                        b.lOENTIFIERS/OPEN ENDED TERMS
 Air Pollution     Efficiency
 Dust             Electric Power
 Measurement       Generation
 Electrostatic     Cements
    Precipitators  . Kilns
 Collection
 S DISTRIBUTION STATEMENT

 Unlimited
                                                                c. COSATI Field/Group
                                         Air Pollution Control
                                         Stationary Sources
                                         Particulate
13B
11G
14B    10A
       11B.13C
       13A
                                        20. SECURITY CLASS (Ttii*pagtl
EPA Form 2220-1 (9-73)
                                NATIONAL TECHNICAL
                                INFORMATION SERVICE
                                              *
                                                                                                            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.  The five series are:

                                   1.  Environmental Health Effects Research
                                   2.  Environmental Protection  Technology                     o
                                   3.  Ecological Research
                                   4.  Environmental Monitoring
                                   5.  Socioeconomic Environmental Studies

                           This report has been assigned to the ENVIRONMENTAL PROTECTION
                           TECHNOLOGY series.  Thas series describes research performed
                           to develop and dmonstrate 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 treatment
                           of pollution sources to meet environmental quality standards.

                                             EPA REVIEW NOTICE

                           This report has been reviewed by the U. S. Environmental Protection
                           Agency, and approved for publication.   Approval does not signify that
                           the contents necessarily reflect the views and policies of the Agency, nor
                           does mention of trade names or commercial products constitute  endorse-
                           ment  or recommendation for use.
                                                                                           This document is avialable to the public through the National
                                                                                           Technical Information Service, Springfield, Virginia  22161.

-------
                                           EPA-600/2-75-056




           PARTICULATE  COLLECTION  EFFICIENCY

                   MEASUREMENTS ON THREE

                ELECTROSTATIC PRECIPITATORS


                                   by

                  Grady B.  Nichols and Joseph D. McCain
                       Southern Research Institute
                        2000 Ninth Avenue, South
                       Birmingham, Alabama 35205

                                  for

                       The M.W. Kellogg Company
                       1300 Three Greenway Plaza
                          Houston, Texas 77046
in
-o
 i


Contract No. 68-02-1308, Task 21
     ROAPNo.  21ADL-004
  Program Element No. 1AB012
                   EPA Task Officer: Leslie E. Sparks

                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

                             October 1975
                                   II
                                                                                            ABSTRACT


                                                                   The operating  characteristics of three full scale electro-
                                                                   static precipitators  were  determined to provide definitive
                                                                   data  on  their  performance.  The measured performance of
                                                                   these precipitators was compared with the theoretically
                                                                   predicted efficiencies computed by an electrostatic precipi-
                                                                   tator mathematical model.   Field measurements of total
                                                                   inlet and outlet mass concentrations, particle size
                                                                   distributions, and electrical data were used for these
                                                                   comparisons.   Descriptions of the measurement procedures and
                                                                   the mathematical model are included.
                                                                                                  iii

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                      CONTENTS
.Abstract

List'Of Figures

List'of Tables
                                      Page

                                       iii

                                        v

                                      viii
 Sections

   I

   II

   III


   IV


   V

   VI




   VII




   VIII

   IX
 Introduction                            1

 Measurement Techniques                  2

 Gorgas  Power  Station —-Alabama"Power
 Company                                9

 Performance Tests  at  a-Hot'Side
'Electric Utility Burning Western  Coal   23

 Citadel Cement,- Birmingham, -Alabama     44

 Comparison of Measured  and Theo-
 retically-Predicted Collection
 Efficiencies                           -57

 Impactor Substrate and  Filter Media
 Interference-in a  Flue  Gas Environ-
 ment                                   65

 References                             '74

 Conversion Factors                     75
                           iv
                                                                                                       FIGURES
No.                                                   .Page

'2-1    Comparison.of sedimentation and equivalent
       optical diameters                                 5

2-2  '  Optical and diffusional sizing'system            6

3^1    ' Precipitator layout-at Gorgas Unit 10          -10

3^2    Velocity traverse -at inlet                   .   11

3-3    Velocity.traverse at outlet                     12

3-4    .Inlet 'size distribution obtained from modified
       Brink irapactor                                  .15

3-5    .Outlet size distribution obtained from
       Andersen impactor                                16

3-6    Measured and computed efficiency as a 'function
       of particle size for precipitator installlation
       -at the Gorgas plant of Alabama Power Company     17

3-7    Voltage-current relationships obtained on
       precipitator »B"                                 22

4-1    Cumulative particle size distribution of the
       inlet particulate at a hot.side precipitator
       installation                                     28
                       o
4-2    Cumulative outlet particle size distribution
       hot  side precipitator                           29

4-3    Cumulative particle number concentration at
       the  hot side precipitator installation          31

4-4    Measured fractional efficiencies for the
       hot  side electrostatic precipitator             32

4-5    Laboratory resistivity as a function of
       temperature for fly ash from the hot side
       precipitator.                                    35

4-6    ,Precipitator information and layout for the
       collector                                        37

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No.

5-1




5-2




5-3




5-4




5-5

6-1


6-2




6-3


6-4




6-5


6-6




7-1




7-2
                           FIGURES
                          (continued)
Cumulative inlet mass concentration as a
function of particle size for the Citadel
Cement installation
                                                      Page
                                                48
Cumulative mass as a function of particle size
from the outlet of the Citadel Cement installa-
tion, runs 3-6                                  49

Cumulative mass as a function of particle size
from the outlet of the Citadel Cement installa-
tion, runs 7-9                                  51

Minimum collection efficiency as a function of
particle size, Citadel Cement electrostatic
precipitator                                    52

Precipitator layout. Citadel Cement             56

Mass efficiency as a function of specific
collection area at the Gorgas Power Station     58

Comparison of the average and computed fractional
collection efficiencies at the Gorgas Power
Station                                         60
Mass efficiency as a function of specific
collection area for the hot side precipitator
                                                61
Comparison of the average and computed fractional
collection efficiencies for the hot side pre-
cipitator                                       62

Mass efficiency as a function of specific
collection area at the Citadel Cement Plant     63

Comparison of the average and computed frac-
tional collection efficiencies at the Citadel
Cement Plant                 .                   64

Comparison of weight and sulfate on blank
Andersen impactor substates and observed
anomalous weight increases                      68

Anomalous weight increases of Andersen glass
fiber impaction substrates at different flue
gas temperatures                                69
                            vi
No.

7-3


7-4


7-5
                                                                                                    FIGURES
                                                                                                  (continued)
Anomalous weight gains of various 47 mm dia.
glass fiber filters at different temperatures

Anomalous weight gain of 64 mm diameter Reeve
Angel 900 AF glass fiber filters

Anomalous weight gains of Andersen impactor
glass fiber impaction substrates
                                                                                                                                 Page
                                                                                                                                  70
                                                                                                                                  71
                                                                                                                                  72

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                     TABLES
                                                  Page
No.                                               	

3-1   Dust loading measurements at inlet and outlet  14
      of precipitator "A"

3-2   Summary of data from Gorgas plant. Unit 10,
      Precipitator A                                18

3-3   pH and soluble sulfate of ash obtained from
      an exit hopper and an inlet traverse          20

3-4   Overall composition of ash samples obtained
      from inlet traverse                           21

4-1A  EPA Method 5 inlet mass concentration tests,
      hot side precipitator installation            25

4-1B  EPA Method 5 outlet mass concentration tests  26

4-2   Mass concentrations at inlet and outlet of a
      hot side precipitator as measured by two
      methods                                       27

4-3   Proximate coal analysis                       30

4-4   Chemical analysis for fly ash                 33

4-5   Power supply readings, hot side tests         36

4-6   Power station test data                       39

4-7   Summary, hot side test                        40

4-8   Impactor stage weights                        41

4-9   Operating and generating station test data    42

5-1   Citadel Cement outlet mass test results       45

5-2   Schedule of sampling runs                     47

5-3   Outlet impactor/mass train comparisons.
      Citadel Cement                                50

5-4   Optical-diffusional data                      53

5-5   Power supply readings. Citadel Cement Company  55

7-1   Soluble sulfate analyses of hot side test
      filters                                       66
                        SECTION  I
                      INTRODUCTION
This report describes  the  results  of tests  conducted on three
full scale electrostatic precipitators  installed in commercial
operations for  the  control of  particulate emissions. 'These
installations selected are considered to be representative of
•operating field precipitators  in the U.  S.   The plants  selected
for tests are a station with a precipitator located prior to
the air preheater;  Gorgas  Power Station, Alabama Power  Company,
Birmingham, Alabama; and the Citadel Cement Plant,  Birmingham,
Alabama.

The "hot side"precipitator represents an installation utilizing
low -sulfur western  coal with the electrostatic precipitator
installed between the  air  preheater  and the economizer  sections
of the plant  (hot side location).  The  Gorgas  Power Station
was selected as a representative power  station for  eastern
coal with the electrostatic precipitator located downstream
from the air preheater (cold side).   The Citadel Cement
Installation represents a  reasonably modern installation on
a cement kiln.
                       viii

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                       SECTION II
                 MEASUREMENT TECHNIQUES
The measurement techniques utilized  for providing the  required
field data are discussed individually below.  The methods
utilized follow standard techniques  for the mass train measure-
ments.  Special measurement techniques were utilized in  the
measurement of particle size, gas analysis, and resistivity.

MASS CONCENTRATION MEASUREMENTS

The inlet and outlet particle mass loadings were measured with
the EPA Method 5 technique.  The sampling procedure followed
was that described in the Federal Register, Vol. 36, No. 247,
December 23, 1971.  The probe cleaning and sample extraction
procedure is described in detail below since it deviates from
the recommended procedure.

EPA Mass Train Cleaning Procedure

Cleaning of the "front half" of the  EPA Method 5 Mass  Train is
extremely important in determining the particulate concentra-
tion of gas streams.  Frequently the majority of the particulate
sampled from the gas stream will be  collected in the probe
and associated glassware and never reach the filtration media.

The following cleaning procedure has been demonstrated to be
very effective in removing particulate captured in the mass
train hardware and was the technique used during this  test.

Probe Cleaning -

Immediately after removing the probe assembly from the gas
stream both the tip and ball are taped to prevent gain or loss
of particulate.  The area where the  tip if screwed to  the probe
body is washed to prevent outside contamination when the tip
is removed.  The tip is removed and  rinsed with the wash
bottle.  After the initial wash the  tip is brushed from both
ends with a tube brush ,of correct size to remove "stuck"
particles.  The brush is washed to remove particles which
become entangled in the brush fiber.
The probe body is held at a slight angle with the "front" end
down and is washed from the ball end.   This usually required two
people (one to hold the collection container and one to actually
wash the probe).   After washing with rotation to assure wetting
all walls of the liner, the probe is brushed with a steel or
brass brush assembly similar to that used for cleaning guns.
The brush is attached to a rigid assembly and forced from the ball
to the "front".  Care is exercised to allow the brush to exit
the front slowly and thus reduce "splatter".  With the brush
extending through the probe, the brush is carefully rinsed to
remove particulate from the bristles.   After complete rinsing of
the brush it is withdrawn from the probe.  The probe is again
rinsed and rotated to remove the last traces of particulate from
the liner.  The interior surface of the probe should have a bright
metal sheen at all points after an effective cleaning.


Glassware Cleaning -

All glassware connecting the probe to the filter is carefully
brushed and washed with distilled water with quantitative
techniques to remove all particulate and transfer this material
to the collected washings from the probe and probe tip.


PARTICLE SIZE MEASUREMENTS

The particle size distribution measurements were made by the
use of both in-stack inertial impactors and optical counters
for particle diameters greater than about 0.3 ym and by diffusion^
techniques with condensation nuclei counters in conjunction with
diffusion batteries.  The inertial impactors provide information
on a mass  per unit volume basis for particles with diameters of
approximately 0.25 vim and larger.  The optical technique provides
information on the number per unit volume basis rather than a
mass basis.  The mass equivalent can be determined when the partic
density is considered and a simple computation performed.  A
detailed description of the particle size distribution measurement
equipment is described by Smith et.al.1  Therefore, only a brief
discussion of the technique is given in this report.
OPTICAL AND .DIFFUSIONAL MEASUREMENTS

The optical and diffusional measurements utilize a dark field
photometer to detect the number of particles per unit volume in
the view field.  Extensive dilution of the gas stream being samplt
is usually required because of the limitations imposed by the
useful range of both the optical counter and condensation nuclei
counter.  Dilution ratios are selected to provide number

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concentrations that fall within the dynamic  range of the measure-
ment equipment.  As a general practice, checks of the  linearity
of particle count .with dilution changes are  performed  to determine
whether any anomalies .resulting from condensation or other
phenomena are occurring within the measurement system.

Due to limitations imposed by equipment availability,  it is not
possible to obtain simultaneous measurements at  the precipitator
inlet and outlet with the optical and diffusional measurements.
However, the stability of the particulate concentration is in
general sufficient to enable meaningful fractional efficiency
data to .be derived by first obtaining inlet  data, and  subsequently
moving the equipment to the outlet to obtain the necessary data
at that location.

The optical particle counter is calibrated with  polystyrene
latex spheres.  The indicated diameter of the particulate in the
stack gas can differ from the true diameter  because of the
difference in the refractive index of the material from that of
polystyrene latex.  In order to check the diameter obtained for
the effluent, the diffusion batteries are used as sedimentation
chambers, and the particle diameters obtained from the calcu-
lated sedimentation rates are compared with  the  indicated
optical particle diameters.  Figure 2-1 shows a  sample com-
parison using values for particle density of 1.0 and 2.0 grams/
cm3 in the sedimentation calculations.  Partxcle densities are
estimated to range from about 1 to 4 grams/cm3 in most field
installations..  The comparison indicates fair agreement between
the sedimentation diameters, which are independent of  refractive
index, and the equivalent optical diameters.  Figure 2-2 shows
the optical and diffusional sizing system.   The  sampling probe
is typically heated to avoid condensation.

Inertial Impactor Sizing Techniques

The inlet size distribution measurements were made with modified
Brink impactors while the outlet measurements were made with
modified Andersen Mark III impactors.  The Brink impactor -is .a
low volume flow device and the Andersen impactor operates at a
relatively high volume flow.  The selection  of the low flow
instrument for the inlet and a high flow instrument for the
outlet allows near simultaneous testing at both  locations.  This
difference in sampling rates is required because of the great
difference in mass concentrations across a high  efficiency
collection device, typically on the order of a factor of 100.

The impactors are operated in the gas stream with the  flow rates
and sampling nozzles selected to provide near isokinetic sampling
rates for both the inlet and outlet measurements.  Thus, simultaneous
inlet and outlet measurements are made with  the  impactors operating
at approximately the same size distribution  cut  points to
facilitate the interpretation of the data for evaluating the
performance of the control device.
   1.4
 e

  •• i.o
 IE
 UJ
  0.8
O
tu
S 0.6
o
JH
  0.4
  O.2
                                 LINE INDICATING
                                 PERFECT AGREEMENT
                               O SP GH = 2.0IN SED CAUC

                               A SP GR = 1.0 IN SED CALC
        02      0.4      0.6      0.8       1.0       |.2

                     EQUIVALENT OPTICAL DIAMETER , ym

  Figure 2-1.   Comparison of sedimentation and
                equivalent optical diameters

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                                                              Flowmeters
      Cyclone Pump
  Process
  Exhaust
  Line
Neutralizer
Flowmeter
                                        CN Counters

p

Aerosol
Photometer


                                    Diffusional Dryer
                                       (Optional)
                                                       Balancing
                                                       Line
 Recirculated
 Clean Dilution
 Air
         Filter
                                   Bleed


         Figure  2-2.   Optical  and  diffusional  sizing  system
Both types of impactors are operated with a back-up  filter to
collect the fraction of particles smaller than the last stage
of collection.  The Brink inlet impactor is equipped with a
precollector cyclone that removes the large particle size
fraction of the material before it reaches the actual impaction
stages.

The operation of the impactors requires extreme care to assure
that meaningful  data are collected.  The impactor substrates must
be selected to minimize any reentrainment of previously collected
particulate.  Reentrained material would be transported by the
gas stream to the next sequential collection stage.  This
phenomenon would cause errors in the measured size distribution.

The substrate.material has the potential for chemical reaction
with gas phase constituents.  The material must be tested for
gas phase reactions prior to their utilization in tests. The
substrate material must be evaluated for gas phase reactions
prior to use.  This is described in more detail.

RESISTIVITY MEASUREMENTS

In-situ resistivity measurements are made with a point-to-plane
electrostatic collection instrument.  The device is  inserted
into the flue gas environment and allowed to reach near thermal
equilibrium with the gas stream.  The dust thickness gage is
reset to zero and the measurement cell positioned for collection.
A clean electrode voltage vs current characteristic  is recorded.
The current density for collection is selected and a dust layer
is precipitated electrostatically.  After collection, a second
voltage vs current characteristic is recorded.  This provides one
measure of resistivity.  The measurement electrode is then lowered
to contact the dust layer and the layer thickness determined.
The resistance cf this known geometrical configuration  (right
cylinder) is measured.  The resistivity is then determined from
the measured resistance.

For the special case where the flue gas temperature  exceeds
200°C, the resistivity is determined in the laboratory.  A dust
sample is collected in the field and the resistivity is measured
according to the method described in the A.S.M.E. Power Test Code
Number 28.
GAS ANALYSIS

The exit flue gas composition is determined by standard chemical
techniques.  The carbon dioxide and oxygen content are deter-
mined by standard Orsat techniques.  The oxides of sulfur are
determined by chemical techniques utilizing a conversion of
sulfur dioxide to sulfur trioxide in a hydrogen perioxide solu-
tion and a condensation of the sulfur trioxide on the walls of a
condenser.  The concentrations of dilute sulfuric acid are deter-
mined by an acid titration utilizing a thorin indicator for
the final determination.  These measurements are conducted at
intervals during the testing period.

-------
The flue gas .chemistry measurements .are omitted in-the power
stations .where:the control device operates,at .temperatures in
excess of 200°C.  The sulfur trioxide does not materially influ-
ence the particulate characteristics at these relatively high
temperatures.


PRECIPITATOR .ELECTRICAL CHARACTERISTICS

The power supply secondary voltage and-current-values are
recorded at intervals during the test program.  If the pre-
cipitator is, equipped with indicating meters, the values are
recorded from these meters.  If not, selected .power -sets are
equipped with voltage dividers such that the secondary voltages
will be known throughout the tests.
BOILER OPERATING DATA

The control room operating characteristics are noted at inter-
vals during .the ..test. period.  .Such items as steam generation
rates, electrical generation rates, fuel feed rates,'etc. -are
recorded.
                           SECTION III
           GORGAS  POWER STATION -  ALABAMA - POWER COMPANY
 INTRODUCTION

 A test  program,was  conducted at the Gorgas Power Station,  Alabama
 Power Company, .to evaluate-the performance of the electrostatic
 precipitator installed on unit 110.   This installation was selected
 as being -representative of a well-designed conventional (cold side)
 precipitator collecting fly ash from 'an',eastern coal.   The primary
.objectives  of this  test program were to determine the  overall
 collection  efficiency of the unit,  to evaluate the collection
 efficiency  .as a  function of particle 'size and to analyze the per-
 formance of 'the .unit by the use of-the precipitator mathematical
 model.
ELECTROSTATIC PRECIPITATOR DESCRIPTION

Figure  3-1 illustrates  the gas  flow  and  precipitator  arrangement.
Some of the electrical  sets were not operating on  the B  side
precipitator, apparently  due  to broken corona  wires;  therefore,
tests were conducted on the A side only.   Each precipitator
consists of .two  series  section, each of  which  has  144 gas passages,
with 0.229 m plate  to plate spacing  (9 in.).   Each precipitator
consists of 144  gas passages  9.14 m  high (30 ft),  10.97  m long
 (36 ft), for .a total collecting area of  28877  m2  (311,000 ft2
per precipitator.   The  precipitators each  have twelve electrical
sections arranged .in series with the gas flow, such that the
.individual sections power 1/12  of the plate area and  1/12 of the
length.  Gas flow at full load  (^700 MW) for each  precipitator is
about 520 m3/sec (l.lxlO6 cfm)  at 149°C  (300°F).   The specific
collecting area  at  these  conditions  would  be 55 mV(mVsec) or
283 ft2/1000 cfm.
                                                                                RESULTS

                                                                                The results from field measurements on this unit are given
                                                                                below..
                                                                                Mass Loadings

                                                                                The overall mass efficiency measurements were conducted by
                                                                                Scientific South, Inc., under contract with SRI.  Figures 3-2
                                                                                and 3-3 illustrate the velocity profiles obtained at the inlet
                                                                                and outlet sampling locations with preliminary pitot tube trav-
                                                                                erses performed on July 9, 1973.  Inlet and outlet dust loading

-------
Figure 3-1.  Precipitator Layout at Gorgas Unit 10.
                                                                                              "**
                      10
Figure 3-2.  Velocity Traverse at Inlet.





                  11

-------
Figure 3-3.  Velocity Traverse at Outlet.
                                                                     measurements were  conducted  on  July  10  and 11.   The  results  of
                                                                     this work  are  given  in  Table 3-1".  During  the time period that
                                                                     the measurements were conducted,  the generation rate was  constant
                                                                     at 710 MW.  Sampling, was  performed- with an EPA approved sampling
                                                                     train manufactured by Research  Appliance Corporation.


                                                                      Fractional Efficiency Measurements

                                                                      Tests  using cascade  irapactors for particulate mass efficiencies as
                                                                      a function of particle  diameter were conducted on July 10, 11, 12,
                                                                      13,  and 16.  Inlet data were obtained with modified Brink impactors
                                                                      on the first  four days  of testing and outlet data were obtained with
                                                                      an Andersen impactor on all  five days.   Diffusional sizings with a
                                                                      series of- diffusion  batteries and two condensation nuclei counters
                                                                      were used to  provide concentration and size distributions by number
                                                                      over the size range  from abo.ut 0.005 yra to 0.3 vim.  Relative con-
                                                                      centrations on a number basis were measured- using a Climet particle
                                                                      size analyzer, equipped  with  a scanning pulse height analyzer and
                                                                      digital rate  meter.  Because of the high number concentration of
                                                                      small  particles in the  stack, dilution of the sampled gas stream
                                                                      by factors ranging from about 50:1 to about 1000:1 was necessary in
                                                                      order to obtain data with both the condensation nuclei counters
                                                                      and  the optical particle counter.  These data are given in Figures
                                                                      3-4,  3-5,  and 3-6.


                                                                      Resistivity

                                                                     The  resistivity of the  fly ash  obtained in a previous test at a
                                                                     temperature of 165°C (330°F)  is approximately 2x1010 ohm-cm.


                                                                      Gas  Analysis,  Chemical  Analysis and Coal Analysis

                                                                      The  results of the gas  and coal sulfur content analyses are
                                                                      given below in Table 3-2.

                                                                      Sulfur oxide  analyses performed on July 10, 11, and 13 indicate
                                                                      that the SO2  concentration dropped significantly, apparently as
                                                                      a result of decreasing  sulfur content of the coal.  There is some
                                                                      disagreement between the coal sulfur contents obtained from the plant
                                                                      records with those obtained by SRI.   The samples which were analyzed
                                                                      by SRI were obtained after the coal was pulverized prior to injec-
                                                                      tion into the furnace.   Results from these analyses show proportion-
                                                                      ate agreement with the  measured variation in SO2 concentration.
                                                                      The current density  of  the precipitator also dropped significantly
                                                                      during the same time period, possibly as a result of the response
                                                                      of the power supplies  to an increased tendency to spark arising
                                                                                                       13

-------
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                                     Diameter< urn
                                                                                 10
          Figure 3-6.  Measured and Computed Efficiency as a Function of  Particle Size
                       for  Precipitator Installation at the Gorgas Plant  of Alabama
                       Power  Company.

-------
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                                                             TABLE 3-2

                          SUMMARY  OF  DATA FSOM GORGAS PLANT,  UNIT  10,  PREdlPITATOR A
Overall
Date
7/9/73
7/10/73
7/11/73
7/12/73
7/13/73
7/16/73
Flue GOB Composition
	 SCT, 	 W7 	 	 .fi!?, . .6, ..
! t
'1433 ' '3.8 '10.5 3.1
3.3
'1153 '6.0 '11.4
» 885 '2.4 '10. 5*.
•'
Overall
Eft;, %

99.59
99.69



Current
Density
nA/cro'

25;
20.
15.
16.
29.

«
1
e
9
0
Coal Sulfur
Content ,%
(dry DBBIBJ
1.
1,
1,
1
1
1
.19
.59
.84
.54
.10
.44

1.40
1.20
1.20
1.05
1.40
Load .
Heqawatti

710
710
710
720
720
   1.   Measured at precipitator outlet!


   2.   Measured at precipitator inlet.

-------
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                                         TABLE 3-3
                 pH  and Soluble Sulfate of Ash Obtained From an Exit Hopper

                                    and an Inlet Traverse
                                  Hopper Sample
                                                              3 Traverse Sample
Date
7/10/73
7/10/73
7/10/73
7/11/73
7/11/73
7/11/73
7/12/73
7/12/73
7/13/73
Time
1315
1830

1130
1815

1040
1815
1615
1 PH
4.63
4.90

4.35
4.85

4.37
5.10
4.55
Soluble SO;2 % ' pH Soluble SOl2 %
1.1
1.1
8.0 0.4
1.0
0.94
8.5 0.5
0.92
0.87
1.1
   1.  Measurement  taken after stirring for one  hour a slurry of 30 ml distilled

       HtO and  0.1000 g ash.


   2.  Obtained from a hopper near the outlet.


   3.  Obtained at  inlet from traverse with sampling train.

-------
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1.2
1.1
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0.9
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                 18   20   22  24   26   28  30   32   34

                        Voltage,  kv
                                                         36
 Figure 3-7.  Voltage-Current Relationships Obtained on
             Precipitator "B".
                          22
                                                                                                   SECTION IV
                                                                                PERFORMANCE TESTS AT A HOT SIDE ELECTRIC UTILITY
                                                                                              BURNING WESTERN COAL
INTRODUCTION

The performance of an electrostatic precipitator was  evaluated
during April and May 1974.  This  test  is  the  first detailed
analysis of the performance of  a  precipitator located on  the
hot gas side of the air preheater (hot side)  that  Southern
Research has conducted.  This installation was selected as  being
representative of a reasonably  well designed  hot side precipitator
collecting fly ash that resulted  from  the combustion  of the class
of coals designated as low sulfur western coals.

In .general, the testing procedures -described  in  Section II  of
this report were followed.  However, some discrepancies in  the
test results were observed.  The  first discrepancy that was
noted .was the difference in the volume flow rates  as  measured at
the inlet and outlet sampling points of the electrostatic pre-
cipitator.  There was a consistent reduction  in -the gas volume
sampled at the outlet of the device as compared  to the inlet by
approximately twenty percent.   At the  time of testing these
differences were noted and 'the  measurement equipment  checked.
No obvious problems were noted  in the  test equipment  or procedures.

At the conclusion of the tests, this problem  was discussed  with
a power company engineer..  He pointed  out that a fire in  the
air preheater required a modification  to  the  air preheater  such
that the pressure drop downstream from the test precipitator was
significantly greater than that in the adjacent unit.   Since the
two units were not physically separated by a  partition, the
excess gas in the inlet was traversing the demarcation line
between the units and passing through  the adjacent air heater.
This fact was not known during  the test program.

The total mass loadings as determined  by  the  mass  trains  differ
from that determined by the impactors  for -the  initial tests.
The inlet mass loadings differed by as  much as a factor of
six.  An attempted analysis of this discrepancy led to a  retest
to evaluate the causes of this variation.  Southern Research
funded a second trip to the power station to  investigate  these
interferences.   The results of these tests are discussed  later
in the section describing substrate interference.
                                                                                                        23

-------
                                                          TABLE  4-1A
                                  EPA METHOD  5  INLET  MASS CONCENTRATION TESTS.
                                                       APRIL-MAY  1974
    Run No.


    Date


    Time


    Duration  (minutes)


    Moisture  content  %


    Gas Temperature °C


    Gas Velocity ft/min


    Gas Velocity  m/sec

    Sample Vol.  DSCF


    Sample Vol.  DSCM

    Mass  Concentr.  Gr/ACP


    Mass  Concentr Gm/AM9
1
4/29
15:45
90
6.0
309
2431
12.4 .
33.51
.95
3.69
8.44
2
4/30
15:00
150
9.8
314
925*
4.7*
21.14 .
0.6
8.15
18.65
3
4/30
20:00
90
5.0*
311
4353*
22.1*
53.87
1.53
2.10
4.80
4
5/1
10:25
258
8.5
320
2489
12.6*
100.91
2.86
3.85
8.81
5
5/2
10:00
108
7.9
284
2241
11.4
36.42
1.03
3.94
9.01
6
5/2
13:33
96
8.7
305
2547
13.0
37.87
1.07
3.02
6.91
7
5/3
08:00
240
8.1
305
1796
9.1
68.33
1.93
1.91
4.37
    •Suspect test  error
                 g-p
                . 11 m
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                                                      TABLE 4-IB

                                     EPA METHOD  5 OUTLET MASS EMISSION TESTS

                                                   APRIL  - MAY  1974
      Run No.


      Date


      Time


      Duration  (minutes)


      Moisture  Content %


      Avg.  Temp.  °C


      Gas Velocity FPM


      Gas Velocity M/sec.


s>    Sample Vol.  DSCF
0V




      Mass Cone.  Gr/ACF


                   Go/AM*


      Vol Flo.  ACFM


                 M^Sec


      Specific  Collection Area

          '   ft'/KCFM
               rtftnVfec


      Generation  Rate  Mw


      Efficiency  »
1
V29
16:10
150
5.$
30«
1618
8.22
34.14
.97
.05S
.13
318095
150
460
•94.5
220
98.5
2
4/30
15:04
123
8.4
305
1516
7.7
93.01
2.63
.022
.05
297960*
141
490
'96.4.
220
99.73
3
4/30
20:03
120
9.2
311
1627
8.3
96.01
2.72
.0244
.06
319700
151
457
89.9
220
98.84
4
5/1
10:19
300
8.7
290
1530
7.8
229.21
6.49
.0115
.03
300710
142
486.5
95.8
220
99.70
5
5/2
10:00
108
9.0
283
1698
8.6
87.50
2.48
.0167
.04
333728
158
438
86.2
260
99.58
6
5/2
13:40
108
8.4
302
1809
9.2
92.05
2.61
.017
.04
355544
168
411
80.9
260
99.44
7
5/3
08:07
240
8.3
291
1450
7.4
176.03
4.98
.0127
.03
285000
135
513
101
260
99.11
      "V6T.  tio' corrected irori» inlet

-------
       10
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      1.0
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O
-J
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      O.I
     0.05
     0.02
     0.01
        O.I   0.2
                     "I     I     I
                                          I      I      I
                      0.5    1.0    2.0      5.0    10    20
                           MAX PARTICLE DIAMETER, (xm
11.44




4.58



2.288



1.144  n£
      ^
       w

       2

0.458



0.229



0.114




O.O46
                                                              50   100
Figure 4-1.   Cumulative Particle Size Distribution  of the
               Inlet  Particulate.
                                                                                                        O.I
                                                                                                g  0.051—
                                                                                                      0.02
3   0.01
o
                                                                                                     0.005
                                                                                                   3 0.002
                                                                                                      0.001
                                                                                                         O.I
                                                                                                                                  i       I          i       r

                                                                                                                            O AVERAGE MASS TRAIN ME AS.
                                                                                                                                                         0.012
                                                                                                                                                         0.007
                                                                                                                                  I	I
                                                                                                                                                                  0.114
                                                                                                                                                                  0.046
                                                                                                                                                                    10
                                                                                                                                                                     E
                                                                                                                                                                 0.023
                                                                                                                                                                  0.01 1
                                                                                                                                                                 0.0046
                                                                                                              0.2       0.5      I.O     2         5      10

                                                                                                                        MAX PARTICLE DIAMETER, («n
                             Figure 4-2.   Cumulative Outlet  Particle  Size Distribution-
                                                                                                                                29
                                    28

-------
to correlate the optical diameter with the  inertial behavior of
the particles  (i.e., Stoke's diameters).  The optical and diffusional
data represent single point samples at both the inlet and outlet
of the precipitator.  Extractive sampling and extensive dilution
at the sample gas stream was required in obtaining the optical
and diffusional data.  Figure 4-3 shows the results of the measure-
ments.  The data in Figure 4-3 are presented in terms of cumulative
concentration by number density  (t/cra3) of  particles having
diameters larger than or equal to the indicated'diameters.

Figure 4-4 shows the fractional efficiencies of the precipitator
as calculated from these data.

Laboratory Particulate Resistivity

The laboratory resistivity was determined for samples one and two
that represented the extremes in sodium oxide concentration.  The
results of these tests are shown in Figure  4-5.  The difference
in resistivity at temperatures greater than 300°F are as expected
for.the observed variation in_chemical composition.
                              '                      "-»-*-
Coal Analyses and Chemical Analyses

Coal sables were analyzed for each test during the series.  The
proximate analysis for each sample is given in Table 4-3.

                           TABLE 4-3
                    PROXIMATE COAL ANALYSIS
                                                                     108
      Item

   Moisture %

   Ash »

   Sulfur t

   Beating value
   (thou BtU/lb)
Test 1

  4.8

 22.4

  0.85


  9.9
  2

 4.3

24.7

 1.07


10.1
  3

 4.3

24.5

 1.02


 9.8
  4      5

 4.1    3.9

24.36  23.3

 0.87   1.13


 9.7   10.0
  6

 4.2

23.45




 9.98
The coal was considered to be essentially constant during  this
test program.  The coal samples were taken  downstream from the
pulverizer.  Thus the moisture content may  be  low and the  other
values correspondingly high in comparison to raw coal samples.

Fly Ash Chemical Analysis

Fly ash samples were collected during the test program for
laboratory analysis.  The results of these  determinations  are
given in Table 4-4.
                                                                     10'
                                                                   z  I06
                                                                      I05
                                                                   (E
                                                                   S
                                                                                        .0
3
(J
                                                                     10*
                                                                                                    DIFFUSIONAL DATA
                                                                               I	I
                                                                                                                                 OPTICAL DATA
                                                                                                                                 SEDIMENTATION SIZES
                                                                             o.oi     o.oa       0.05    o.i    °-2
                                                                                       MINIMUM PARTICLE DIAMETER, fi
                                                                                                             0.5
                                                                                                                     1.0
                                                                      Figure 4-3.  Cumulative Particle Number Concentration
                                 30
                                                                                                                    31

-------
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-------
Electrical Conditions
The precipitator power supply secondary voltage and current were
monitored during the test program.  The readings are given in
Table 4-5.  The power supply readings were reasonably consistent
during the test period.  The precipitator layout and pertinent
information are shown in Figure 4-6.  The current density was
consistently lower on the left side inlet (section A) for each
test.  This could in part_be due to some electrode misalignment
for this field.

SRI-Sponsored Mass Train and Impactor Measurements

Background -

A discrepancy was noted between the mass loadings as given by
the EPA Method 5 technique and the impactors.  The data obtained
from the mass tests at this plant indicated'that the Andersen
impactorsrfroa a single point sampling location gave only about
20% of the total outlet grain loading as obtained with' an EPA
Method 5 sampling train.  During December 1974, similar tests
(also reported in this document) were conducted at Citadel
Cement Co. in North Birmingham, also considered to be a hot
precipitator 260°C(500°F).  Again a significant discrepancy
between loadings were shown.  While at Citadel a comparison of
the mass train measurements and Andersen measurements was planned.
A Gelman 47 mm filter was run ahead of an Andersen impactor and
one Andersen impactor was run ahead of a mass train.  The Andersen
impactor was run ahead of the mass train in an attempt to
determine if there were appreciable differences between a tra-
verse and a single point measurement; due to the size of the
Andersen impactor, a traverse of only one-half the area of the
stack was possible.  The cause of the discrepancies between the
loadings as indicated by the two instruments required further
investigation.

Test Plan -

A test program was devised with the objective of determining
the cause or causes for the anomalies between the two systems
with respect to mass train grain loading vs impactor grain
loading measurements.
                                34
  10'
   ,12
   10"
E
o

-------
                                                                        TABLE 4-5
                                                                   Power Supply Readings
Average

Average Current
Density, nA/on1
                    Voltage Current  Voltage Current  Voltage Current  Voltage Current  Voltage Current  Voltage Current  Voltage Current  Voltage Current
                      (kV)     (ma)      (kV)     (ma)      (kv)     (ma)      (kv)     (ma)      (kV)     (ma)      (kv)     (ma)      (kV)     (ma)      (kV)     (ma)





u>
en
April 29, 1974
April 30, 1974
May 1, 1974
May 2, 1974
May 3. 1974

36
. 37
37
36
36

.3
.5
.4
.3
.2

485
- 523
634
550
550

29
31
32
32
31

.2
.9
.2
.6
.4

700
650
684
635
680

22.0
24.3
25.4
24.9
24.2

675
686
702
688
702

20
21
22
20
21

.0
.0
.8
.5
.8

755
737
706
708
722

21
20
21
23
22

.5
.4
.0
.0
.0

900
936
940
915
920

19.
17.
19.
20.
19.

0
4
0
0
2

925
936
936
940
910

16.3
16.4
17.0
17.7
16.7

995
989
994
948
994

15.5
16.3
17.0
16.7
16.8

922.5
927
932
910
920

36.8    548.4    31.5


         32
670.0   24.2     690.6   21.2    725.6    21.6    922.2    18.9     929.4   16.8     984.0     16.5    922.3


 39.4             40              42.7             54.2              54.7            57.9             54.3
      Note:   Each power set is  connected to 1.7xlO'cm*  (18270 ft1)

-------
      I
      I



   •   I  /-s.
^^^D   i  ©
                               T
                                  1C]
                                                i     i
                                               T     I
Inlet Duct:-24!-11" x 5'-3"~     Outlet Duct 29'  x 5-'-3"


Total Area  '146,160 ft2 = 13,579 m2


Plate Spacing 9" = 23 cm


Corona Wire Di-a. 0.1055 - .27 cm.


4 Pptrs Total Installed


Area for each power supply   1.7x10' m2=  18,270  ft2


Guar. 99.5- ?' 35'0 MW


Test 1.  Vol flow - 24 11/12' x  5.'25'.' x  24-31 ft/min- =

         318,005 = 8600 mVmin


SCA = 146,160 * 318,005 = 459 ft2/kcfm = 90.35  ma-sec/m3


Current Density = 42 yA/ft2  = 43 nA/cm2


Avg. Eff.  7 tests  3.085 inlet,  .0228 outlet =  99.26
Figure 4-6.  Precipitator  Information  and Layout for the
             Col-lector.
                             37

-------
The test as conducted consisted of:  Andersen impactors run
as they have been in the past, single point.  These tests are
labeled as A-0, 1, 2, or 3.  -0 indicates the blank run which
consisted of a Gelman 47mm filter preceding the impactor.
-1, 2 or 3 indicate run number.  The Andersen impactor was run
at a single point in front of a mass train.  These tests are
labeled MT+A-0, 1, 2 or 3; -0 again indicating a blank run,
where a Gelman filter preceded the impactor which in turn pre-
ceded the mass train.  Tests were also conducted using a Gelman 47mm
filter as an in-stack filter ahead of the mass train.  These
tests are labeled MT+G-1, 2, or 3 depending upon the run.  There
were also single point Brink impactor runs labeled as B-l.  All
tests were run at single points, but not for the same duration
due to boiler problems.


Results -

The results obtained from these tests are tabulated in Tables
4-6, 4-7, and 4-8.  Table 4-6 consists of operating conditions
from day to day plus weight catches obtained for each test.
Table 4-7 consists of a summary of the data in gm/m"(dry) for
each filtering device.  Table 4-8 tabulates the stage weights
for each impactor run and Table 4-9  is a table for the previous
data obtained in the Spring of 1974..


Conclusions -

The data from Table 4-6 indicates that the impactors on the blank
runs, when preceded by a Gelman filter, gained 56 rag each,
although sampled volumes differed from 1.065 to 0.215 m3.  This
resulted in O.Q53 and 0.260 grams/m3 due to apparent gas phase
interferences.  If this interference were consistent from run to
run the stage weight gains could be subtracted from the weight
gains during normal runs and a particle size distribution could
be plotted.  But run 4A-3 shows that the weight gain of the
impactor is less than that of the blank runs.  Note that A-3 has
a sampled volume of 0.435 m3 and a weight gain of only 50.52 mg
(0.116  gram/m3).  This test indicates non-reproducible inter-
ference in the Andersen impactors.


Test MT+A-0 and MT-1, where both tests were run at the same point
on the same day, show identical grain loadings when comparing
the Gelman prefilter to the mass train, 0.023 and 0.022 grams/m3.
However, due to operator error, the isokinetic variation was
high on run MT+A-0.  Also for test MT+G-2 and MT-2, the Gelman
prefilter shows fair agreement with the mass train, 0.014 vs
0.021 grams/m3.  Probe washes for tests MT+A-1 and MT+G-1 appeared
to be contaminated with some type of hydrocarbon, even though they
were downstream from the impactor and Gelman filter.  Test MT-3

                               38

-------
                                                                                             POHERTSTATIOM TEST DATA
                                                                                              1/20-75 to 1/24/75.
VO
o»te-
i/zi
1/21
1/M
,M?l
-1/21
1/21
1/22
1/22
1/22
1/22
1/22
1/23
1/23
1/23
l/,23
•Test Bo.
-.MT*A-0
A^O
.A-l
-.MT+K-1
MT+C-1.
.MT-1
• B^l
>-2-
KT+A-2
•MT+G-2
HT-2
A- 3
Hr+A-3
HT+C-3
. MT-3
Point- Probe-
lac. length
6rl 3'
Sr3 -'*• •
5-1-
7-1 31
9-1 '10 '
6-1 old 5',
3-3-
4-3
5^3 new -S1
7r2. 3'
9-3 old 5'
4-2
9-3 new 5'
5-2 3'
7-3 old 51
Mega.
Hatts
331
331
331
331
331
331
213
213'
213
213
213
263
263.
263
263
Baro-
metric
.Pressure
in.:Ha
24.4.
«S4-
24.4
24.4
24.4
.24. -4
24.9-
24.9
24.9
24:9
24.9-
24.7
24.7
24.7
24.7
Stack
.Pressure
in. Ha '
24;9
24 £9 -c
24.9
24:9
24.9.
24:9
25.3
25.3
25.3
25.3
25.3
25.0
25.0
25.0
25.0
Stack
Teap.'C
330
330'
344
344
344
344
300
300
300
300
300
315-
315
315
315
Meter
•Temp'C
IS
-€
-4
10- •
10
10-
-2
-2
19
17
. IB.
-8
19
16
14
Volume Velocity
Sanpled Volume at
by Saapled' Point
«t' dscf . res
45.025
8c413
21.435
.891112
98.153
94.255
10.31
10.466
38.567
47.631
27.694
16.739
36.240
40.361
34.588
37,.«74
' B7.-S7«>-
19:098
75.776
83.267
-80.008
9.336
9.477
32.412
40.231
.23.305
15.351
30. -209
33.957
29.32
40
40'
40
-40
42
40


26
23
26
33
35
36
36
Time
Sampled
-.Bin
90
90 .
240
240
,240
240
119
112
157
136.48
105
70
100
106
95'
Sample.
.nozzle
4SB.
«-• -
.400.
.«•
.25"
.25"
3m>-
:4>»
.25"
.25"
.25"
.25"
.25"
.25"
.25"
%
-Moist.
7.3


8V4
8.4-
8.4
.4.8 .
3.8
8.1
8.1
8.2
7.2:
4.4
6.9
2.9
Height .-Gains, BO
Probe
. Qelaan ispaetor Hash
24.42 56.34 5:4
.. 8.22 56.66
108.64 '
115 ;16 113.9
12.72 184.1
33.5
33.76
72.02
67.66 4.7
15.76 15.9
4.1
•50.52
62.68: 3.9
13.2 31.0
79.4

MT
Filter
-1.55


2.22
214.5'
15.32


2.19
1.66
9.89

-0-
4.6
1.0
Total
Height
:Gain
^84.61
64.88.
108.64
231.28
411.32
48.82
33.76
72.02
74.'SS
33.32
13.99

66.58
48.8.
80.4
. % '
i so-
kinetic
463
100.
83
120
126
1J7
120
117
108
178
118
•8
120
127
117

-------
Table 4-7
Summary,
Test Data
gm/M3 (dry)
Date
1/21
1/21
1/21
1/21
1/21
1/21
1/22
1/22
1/22
1/22
1/22
1/23
1/23
1/23
1/23
Test No.
MT+A-0
A-0
A-l
MT+A-1
MT+G-1
MT-1
B-l
A- 2
MT+A-2
MT+G-2
MT-2
A-3 .
MT+A-3
MT+G-3
MT-3
Port-Point
Location
6-1
5-3
5-1
7-1
9-1
6-1
3-3
4-3
5-3
7-2
9-3
4-2
9-3
5-2
7-3
Impactor
Load MW Gelman pref liter Impactor
331 .023 .008 .039
331 .038 .022 .212
331 .182
331 .049
331 .005
331
213 .097
213 .241
213 .066
213 .014
213
263 .103
263 .066
263 .014
263
Impactor
Back Filter Mass Train Total
.006 .004 .0791
.030 .302
.019 .201
.005 .054 .1083
.169 .174*
.022 .022
.031 .128
.027 .268
.008 .008 .081
.015 .029
.021 .021
.013 .116
.007 .005 .078
.037 .0513
.097 .0973'"
'Impactor loose after test,  nozzle was not pointed into gas stream when removed from port.
 May have happened when removing probe from port.

2May have had leak in probe, probe heater failure — 8' of 10'  probe at subfreezing temperature.
 Probe wash discolored, appeared to contain oil.

1Probe wash appeared to contain oil.

""Possible contaminant, from varnish or top of sample container, in probe wash.

-------
     TABLE 4^8

IMPACTOR STAGE WEIGHTS
    (milligrams,)
Gelman
SO
SI
.§2:
S3
S4
S5
S6
S7
S8
SF
£ Impactor
Mass
A-0
1/21/75
8.22
4.72
4.98
4.96
5.58
5.76
6.06
6.10
5.94
6.04
6.52
56.66
Impactor Loadings
gm/m3 -2647
Sample Time
(rain)
Vol Sampled
dscf
Vol Sampled
m3
90
7.574
.214
MT+A-0
1/21/75
24.42
8.34
5.10
5.22
5.40
4.80
5.44
5.24
5.50
4.86
6.24
56.34
.0528
90
37.674
1.067
A-l
1/21/75

29.
12.
10.
9.
9.
8.
9.
9.
"10.
108.
. 9
240
19.
•

9.2
42
12
54
26
78
40
02
18
64
2008

098
541
MT+A^l B-l
1/21/75 1/22/7.5

24
13
13
11
12
12
10
8
10
115

240
75
2
6,58
.00 7.80
•52 9.10
.06 2.06
.,28
.06
.86
.00
.32
.06 8.22
.16 33.76
.0537 .1279
119
.776 9.336
.1416 .264
A-.2
1/J2/75

5. .80
2.5,3,8
5.60
4,96
5.58
5,6,4
6,34
5.52
7.20
72.02
.2687
112
9.477
.268
MT+Ar2-
1/22/75

7
6
6
7
8
9
8
6
7
67

157
32


..80
.,72
.68
.18
.16
.24
.14
•42
.3?
,66
.0737

.412 .
.918
A- 3
1/23/75

6.60
5.5.0
5.58
5.08
5.52
6.08
5t?2
4.80
5.44
50.52
.1161
70
15.351
.435
MT+A-3
1/2,3/75

6.78
6.42
6.12
6.38
8.38
10.02
7-32
5.18
6.08
62.68
.0733
100
30.209
.855

-------
                                                                      TABLE 4-9
                                                                OPERATING AND TEST DATA
                                                                  GENERATING STATION
                                                                  4/29/74 to 5/3/74
M

Date
4/29
4/30
4/30
5/1
5/2
5/2
Test
No.
1
2
3
4
5 .
6
Load
MW
220
220
220
220
260
260
SCA
ft2
1000 cfm
460
490
457
486
438
411
rrff
98.5
99.7
99.8
99.7
99.6
99.4
Stack
305
306
311
291
283
303
Vol. at
Meter Cond.
m3
1.20
3.27
3.29
8.31
3.24
3.39
Meter
32
30
22
38
28
41
Meter
Pressure
in Hg
24.98
24.8
24.76
24.68
24.68
24.51
Stack
Pressure
in Hg
25.26
25.26
25.26
25.16
25.16
25.05
Weight Gains, mq
Probe . Wash
287.6
307.8
366.6
353.6
201.6
230.9
Filter
11.6
27.3
26.4
71.4
31.5
31.0
Total
229.2
335.1
393.0
425.0
233.1
261.9
gm/m1 dry
dscf
.249
.103
.119
.050
.071
.076
       5/3

-------
 nay.'-have .had-the  probe-.wash.contaminated .from the varnish'on
 the lid of the-sample container-since virtually all of  the mass
 •was-obtained 'from ..the. probe wash.   '.Test MT+G-1 mayrhave .a  low
 Gelman ;f ilter-weight ..due -to a probable leak .in ,the sampling  probe.
 .Such a.'leak,.could also  have contributed, to -the/anomalously -high
 mass found .in ,the probe and filter. .Another consideration is ..the
.probable failure  of the probe heater during:this.run.   The.probe
 was. exposed -,to  sub-freezing temperatures over a.-length  of .approx-
 imately ,2 .-5.-meters.  Such exposure without proper ..heating  could
 have caused condensation .of what appeared to.fee,high molecular
 weight hydrocarbons found in the.probe-wash.

 Previous mass train traverses from.last Spring's -(1975) test, gave
 about 0.096,-gm/m*  at a  pressure of 1 -atmosphere .and a temperature
 .of 20"C.  Single-point  impactor data,  which apparently -.were
.obtained in the .absence ,of  significant weight gains .from gas
 •phase interference, gave about ,20% .of-the-particulate rmass
 :(0.019 gm/m*)-j«bbtained .with-.the .mass'train traverse.  The previous
-Andersen .single point, measurements .are in-.qualitative agreement
-.with ..the ss.in.gle '.point..measurements.'obtained -with the .Gelman _
-------
                           SECTION V
              CITADEL' CEMENT, BIRMINGHAM, ALABAMA
INTRODUCTION

A test program was conducted at the Citadel Cement Company in
Birmingham, Alabama, to evaluate an electrostatic precipitator
collecting the particulate emissions from a wet process cement
kiln.  This installation represents a well designed electro-
static precipitator for the cement industry.

The cement kiln generates particulate in two ways:   (1) com-
bustion products and (2) the abrasive action of the rotating
kiln.  A mixture of lime, sand, rock wool with about 25% by
weight of water are introduced into the three rotary kilns.
The heated process air and combustion products flow, counter-
current to the process materials into the electrostatic pre-
cipitator.


ELECTROSTATIC PRECIPITATOR DESCRIPTION

The precipitator installed at Citadel Cement Company consists
of two separate units, each unit consists of 4 fields in series
with the gas flow and 32 gas passages which are 22.86 cm  (9 in.)
wide.  Each field is 2.7813 m  O'-IV) deep and 10.9728 m
(36') high.'  The combined units have an effective plate area
of 15,625 raz (168,192 ft2) and handle about 130.04 m3/sec
(275,500 cfm) at 
-------
Particle Size Measurements

The test program at Citadel was designed  to  evaluate a potential
interference in the mass and size measurements with regard to
either a weight gain or loss with the substrate materials.  A
variety of sampling procedures, were selected and: a schedule of the
runs, are shown in Table 5-2.

The inlet size distribution data were obtained with a modified
Brink impactor preceded by a precoXlector. cyclone.  The average
cumulative mass vs. the- average particle diameter data from the
inlet are shown.in Figure 5-1.  Andersen  impactors were run
at the outlet, of the precipitator in-the  stacX.  Figures  5-2 and
5-3. are average cumulative mass ve average particle diameter plots
for the outlet impactor data.  Figure. 5-2 includes the data ob-
tained on 12/18 and 12/19:whereas the data for Figure 5-3 was
obtained on 12/20/74.  There was a decrease  in the outlet grain
loading on 12/20/74 which was reflected; in the mass train and
impactor measurements.  There is no explanation for the decreased
outlet loading on 12/20/74/.  The plant personnel reported that
on that particular day,, the kilns were more  efficient than normal. .

Table 5-3 is a.comparison of the outlet impactor data and mass
train;data.  Data from run number CC07, where, an impactor was. run
ahead of a.mass train, suggests.that the  substrates were reacting
with the gas phase, constitutents.  This- conclusion is based on
the results from a.chemical analysis of the  material found in
the probe.  The analysis indicated the particulate was similar
in composition to the  kiln affluent.

Figure 5-4, is.a plot of minimum fractional efficiency vs particle
diameter.  The data, used to calculate' the fractional efficiencies
in Figure 5-4%were not corrected for possible weight gains in the
substrate materials, since the-weight gain on run number CC09 was
less than, the weight gain of the impactor in run number CC02: which
was preceded by a- filter.  This indicates- that it is not feasible
to correct for the substrate interferences with, the-available-
data .

Optical and diffusional data were taken at the outlet on the
17th, 18th, and 19th.  Only diffusional. data were obtained at
the inlet on the 20th.  No inlet optical  data were obtained
due to a failure in the Royco optical particle sizing instrument
Table 5-4 gives the optical and diffusional  data in number/cm
for the size, indicated.
Mass Trains
   tRuns-
    1

    1

    1
                              TABEE  5-2

                      Schedule- of-- Sampling; Runs
Impactors fRuns
Inlet   Outlet
  0

  2

  4
2»

2**

2

3***
Date


12/17

12/18

12/19

12/20
*-    Blank Runs
**   Andersen with Gelman Postfilter on one run
     Andersen preceding mass train  on one run
                                                                                                                     47
                                 4.6

-------
                                                                                                Average Cumulative Mass  in  Particles
                                                                                                at Size < Indicated  (mg/dscm)
"g 105
4J
U
•a
c
M
V|
to
tt)
N
•H
M '
4J
n 10*
o
t-i
u
tj
o.
58
to
in -a
IS D<
s B
§; 10 3
4J
a
|
CJ
0)
§"

-• 0
01 fll
rt
p- tn
O H-
3 N
(B
1
H
o
3

H*












J~*
0

ft)
K
rt
O
(D

O
H-
(D
rt
1C
H
? 1-
H- 0
O
H
O
3
to
•*— f











e~\
\ i i | i i i i i i i | i i i i





_
_
Q _

~_ O I

3 I
	 	
a




-
D
_ —

D
_
a

-
I 0 I
- ' —~—

o









^ _

— . —
__ _

~ I
1 1 I 1 1 1 i 1 1 I i 1 »n' 1 T
                            48

-------
                                                                            TABLE 'S-,3
                                                              •OOTLBT  IKPACTOR/KASS :TRAIN  COMPARISONS
                                                                          CITADEL .CEMEBT
..Point (H ; Stack
Run No. -.Date .Location -.Tenp(c)
CC01
CC02
,Mrl
.CC03
CC04
KM
Ul CCOS
O CC06
:«3
CC07
CCO 8
CC09
•HT4
(1)
(2)
J12/17/74 . :S
;12/17/74
il2/JL7/.74
,12/18/74
12/18/7.4
:«/18/,74
•14/19/74
12/19/74
,12/19/74
42/20/74
,12/20/74
.•12/20/74
.12/20/.74
x.2
•8
,T
-S
-,T
'.T
•T
.8
it
,—" ™.u»»
Inpactor Postfilter : Probe .filter lOSCH
.27.7
,28. -7

-40.:36 ;!.::
-26/44

25.04
21.52

.53.64
41. -82
.24.74

..'6312
.-•S157
27.7 >3-5 Jl.4068
12 ;6663
..'4902
30.4 4.1 .1J4243
.3783
..-3061
.33.8 -6.0 .1.3286
•26.2 1-4 .2.0813
1.S158
.-7949
35.5 6.5 -3.0226
-.Total (2)
• Apparent
: Loading
:nS/DSCM
.67.^17
•69.23
22.18
65.56
64.14
.,24:22
78.61
'72.59
29.96
39.56
.28:97
32.38
.13.895
Standard (3)
'Loading
•mg/DSCM
23:29
a3.'S7
.22.18
63.88
•64.14
24.22
•78:61
72 .'59
29.96
26.30
J28.97
32.36
13.895
S - Single Point, T - Traverse
Total Apparent.
Loading
- Iota]
1 Catch of all Devices




(3)   Standard Loading
(4)
(S)
(6)
                                    Gas Volm
                   -  Total Catch by First Device
                      Sanpled Gas voluBe
 Secondary Collector Loading  -  Total Catch by Secondary Device
                                 atsflea-OtB Volume
 Traverse .over only SO* of stack area
ylnpactor  anead of -mass train
                                                                                                                                                  -.Secondary <4)
                                                                                                                                                  •Collector
                                                                                                                                                   Loading        "Run'-Tioe
                                                                                                                                                   mg/DSCM         Mrs '.'(App)

                                                                                                                                                    (43.88             .2

                                                                                                                                                    .-55.65             :2

                                                                                                                                                                      2
                                                                                                                                                     ,1.68
                                                                                                                                                    13:26
                                                                                                                                                                          2

                                                                                                                                                                          2

                                                                                                                                                                          2



                                                                                                                                                                          2

                                                                                                                                                                          2

                                                                                                                                                                          -.2



                                                                                                                                                                          •4

                                                                                                                                                                          4

                                                                                                                                                                          4

                                                                                                                                                                          4

-------
      100
n)
m
14
2
e~-
83
18X
4) 0)
18 4J
•H 18
3 O
U C
M 4)
Q) N
*^ *^

-------
                                       TABLE 5-4



                                OPTICAL-DIFFUSIONAL DATA
«!
•H
U.
»l
O
CO1
» c
55
e a
U i.
Size
pm

.3
.5 •

.7
1.3,
. Diffusion.
Battery.


0
4.4

5.. 4
2 x 5.4
' • v

Channel
Number


1
2

3
4
Particle Concentration
1 "Cumulative
Inlet
N/cc
1.6 x 3,0s


1.07 x 10s
.911 x 10«


Outlet
N/cc
<1.2 x 10"


<1.2 x 10"
<1.2 x 10*


Particle Concentration
Cumulative
Inlet
N/cc
-
—

-
-
Outlet
N/cc
4.38 x 10*
1.27 x 10s

2.35 x 10'
7.14 x 10°
Penetration
%

< .75


<1.1
<1.3


....








Efficiency
. %

>99.2


>98.9
>98.7











X
§
e
o
•H

0.05
0.1
0.2

0.5
1
2

5
10
20
30
40
50
60
70
80
90
95
98
0
1 • ll| III II 1 1 1 | 'I 1 1 1 )• 	 1 1 1 1 | I 1 I
_ 1 1 • ' _
— • —
_ • 	
§ A A
'
_ • _ • -
f p I • 4
4
_ ** —
_ . _
_ ' —
_ —
_ \ —
— ' _
~~ i*i* Runs 3,4,5,6 -~
__ • Runs 7,8,9 '_
Data Onoorr.ecte4 for Blanks
— 1 1 ~
1 1 1 1 1 | J .1 1 J 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 • • . '- ' *^* ' • l.fl • ^^ • • ' • • ' 10 i
77.7

99.9
99.8


99
98

95
90
80
70
60
50
40
3.0
20
10
5
2
00
                                     Eartj.de pianieter,  vm


         Figure 5-4.  Minimum Collection •Efficiency as  a Function of Particle

                  '    ,SJ.ze," Cit'aflel Cemenjt"Electrostatic Precipitatbr.
                                                                                          0
                                                                                          3

-------
Electrical Conditions

The secondary current and primary voltage readings were recorded
for the precipitator power supplies during the test program.  The
power supply readings are shown in Table 5-5.  The power supplies
remained reasonably constant during the test.  Figure 5-5 gives
a layout of the precipitator and location of the power supplies.
                               54

-------
                                                                                               TABLE 5-5
                                                                                         POWER.SUPPLY READINGS
                                                                                         CITADEL CEMENT COMPANY




                      1A                 IB                  1C                  ID                  .     2A             .    2B                   2C                  2D
               Primary  Secondary  Primary secondary  Priaary  Secondary  Primary  Secondary       Primary Secondary  Primary Secondary   Primary  Secondary  Primary  Secondary
               Voltage  .Current   Voltage  Current   Voltage   Current   Voltage   Current        Voltage   Current   Voltage  Current    Voltage   Current   -Voltage  -Current
                 (V)       (MA)      -(V)      ;
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                         9S
                                                                                                        SECTION VI
                                                                                                COMPARISON OF MEASURED AND
                                                                                      THEORETICALLY-PREDICTED COLLECTION EFFICIENCIES
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COMPUTER MODEL DESCRIPTION

Southern Research Institute has developed, under EPA sponsorship,
a theoretically-based computer model of the electrostatic pre-
cipitation process.  The model uses the Deutsch equation to pre-
dict the collection efficiency of a given size particle in a
given electric field at the collecting electrode with a known
value of charge in an incremental length section of collection
area.  Particle charge values as a function of electrical condi-
tions, particle size, and residence time are computed from a
theory developed by Smith and McDonald.   The electric field at
the collecting electrode is computed from voltage-current data
using a numerical technique described by Leutert and Bohlen.2
The collection efficiency of a given size particle over the total
precipitator area is determined by summing the collection obtained
in each length increment.  Polydisperse aerosols are represented
by a histogram and overall mass efficiency is obtained by numerical
integration over the size distribution.

The following graphs of computed overall mass efficiency as a
function of specific collecting area were obtained by using the
precipitator geometry, electrical conditions, and the measured
inlet size distributions as input data to the computer program
for each installation.  In addition to the theoretical projec-
tions , computed performance relationships are shown for assumed
values of gas velocity standard deviation and efficiency losses
caused by reentrainment and gas by-passage of the electrified
sections.  The computer program includes calculation procedures
for estimating losses in collection efficiency caused by these
non-idealities.  The symbol Og on the graphs refers to the assumed
value of the gas velocity standard deviation, expressed as a
fraction of the average velocity.  The symbol S refers to the
fraction  of material assumed to be uncollected per stage due to by-
passage (sneakage) and reentrainment, and N designates the number of
stages over which the efficiency losses are assumed to occur.  A
detailed description of the computer model is given elsewhere.3


EFFICIENCY COMPARISONS

Figure 6-1 gives the overall mass efficiency obtained at the
Gorgas Steam Plant along with the computed performance as a func-
tion of specific collecting area.  The precipitator was performing
reasonably close to the theoretically predicted overall mass
efficiency.  A oq .value of 0.25 is considered to represent a
                                                                                                             57

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99.99
  figure  6-1.   Mass Efficiency as a Function of Specific
                Collection Area at the Gorgas Power Station.
                               58
 good;'gas velocity distribution for a full-scale'unit.   Figure 6-2
 shows  the average measured and the computed efficiencies as a
•function of particle size.  The line designated S=0, £>„. = 0.-25
 indicates the-functional form of the correction to'the theoretical
 fractional efficiency predictions which-result's from using the
 computer model's procedure for estimating-'the effects of gas
 velocity non-uniformity.  Note that-the computer modelfappears
 to underpredict the collection efficiencies-of 'particle's smaller
 than 2.0 urn diameter, .and over-predict the collect-ion of larger
 particles.  In view, of-the difficulties involved in making .-frac-
 tional, efficiency-measurements and-the-uncertainties-in the
 theoretical.calculations, the-agreement between'measured-and
 computed'results.-indicated in.'Figures 6-1. and 6-2 is considered
 to be  reasonable.

 Figures- 6-3 and 6-4 compare measured and -computed -performance
 for the'.hot side.-installation.    In-contrast to'the-results dis-
•cussed above,  the overall mass efficiency measurements are-con-
 siderably lower than the theoretical predictions.  Possible causes"
 are poor electrode alignment,-poor gas velocity distribution,.and
 losses due to  sneakage and reentrainment.   if a gas velocity
 standard deviation of 0.25 is assumed, sneakage and reentrainment
 losses of 10 to 20% over 3 stages are required to reconcile the
 computed and measured mass efficiency.  Whether sneakage and
 reentrainment.are the-actual mechanisms by which the-losses
 occurred was not determined.  However, the comparatively low
 slope-of-the measured efficiency vs particle size data suggests
 that a-major portion of the disagreement is due to poorer-than-
 predicted large particle -collection efficiencies.  Reentrainment
 of particle agglomerates due to rapping would be indicated by this
 type of disagreement.  Note that since the total mass obtained
 by the outlet  impactors was much less than that obtained from'the
 EPA Method 5 train (presumably due to the lack of a complete traverse
 with the impactors), the true large particle penetrations are
 probably greater than indicated in 'Figure 6-4.

 Figure 6-5 compares-the-computed and measured mass efficiencies
 for the Citadel Cement Kiln.  As discussed previously, the  .
 "measured" mass efficiencies are-based on inlet mass train measure-
 ments  performed prior to the test series conducted by Southern
 Research Institute, but the outlet measurements were conducted
 simultaneously with the impactor measurements.  The overall mass
 efficiency shows reasonable - agreement with the theoretical pre-•
 dictions.   At  the high values-of specific collection area encountered
 during this test series, relatively minor correction factors are
 required to reduce the computed efficiencies to the measured values.
 Figure- 6-6 compares the theoretical fractional efficiencies'
 with the minimum fractional collection efficiencies obtained
 from the impactor measurements.  As discussed earlier, absolute-
 values of fractional collection efficiency could not be obtained
 due to. substrate interference problems.

                                59

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                                                                                   10.0
                Figure  6-2.  Comparison  of the Average and Computed Fractional
                              Collection  Efficiencies at  the Gorgas  Power Station.
                                                                                         t
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1 1 -
                          (D<0
COLLECTION EFFICIENCY (MINIMUM)
                                                                                    SECTION VII
                                                                         IMP ACTOR SUBSTRATE AND FILTER MEDIA
                                                                        INTERFERENCE IN A FLUE GAS ENVIRONMENT
During the course of the tests described in this report studies
were conducted to evaluate the interference in the determination
of particle size distributions by impactors and the mass loadings
caused by reactions between the filter media and the flue gas
constituents.  A variety of substrate and filter media have been
tested, both under preconditioned and as delivered conditions.
The primary interference phenomenon appeared to be associated
with the reaction between the filter media and the sulfur oxides
in the flue gas.  In each case tested, the filter media contained
significant sulfate after exposure to the flue gas environment.

During the time interval between the testing at Gorgas, the hot
side installation, and Citadel Cement, other tests were conducted.
The filter material was chemically analyzed to evaluate the cause
of the weight changes noted.

The results of these studies showed filter substrate gains of
as much as 4-5 milligrams when sampling flue gas.  These weight
gains attributed to gas phase reactions between the sulfur dioxide
in the flue gas and sites of high basicity on the filter media,
seem to occur at all installations to some degree.

The interferences encountered are illustrated by the results
of analyses of the substrate media for the hot side electrostatic
precipitator on a coal fired power station, hot side
electrostatic precipitator on a cement kiln, and a cold side
electrostatic precipitator on a coal fired power station  (Bull
Run Steam Plant T.V.A. system).

Two series of tests were run at the hot side unit, one in June 1974
and the second during January 1975.  In the first series of tests no
anomalous weight gains were observed, while blank runs during
the second tests showed large weight gains.  (It was subsequently
learned that Gelman Type A filter material had been changed after
the first test series).  Filter samples from the second hot side
test and the Citadel tests were subjected to several types of
analyses, including carbon-hydrogen and soluble sulfate determina-
tions, weight loss at 110° and 600°C, and carbon disulfide extrac-
tion followed by gas chromatographic analysis of the extract.

Preliminary data from the hot side filters showed that soluble
sulfate levels were significantly higher than obtained from
unused filters from the same batch.  Soluble sulfate determinations
were then made on all of the filters from the two sets showing
weight gains.  The data in Table 7-1 clearly indicate that
sulfate is responsible for the majority of the observed weight
gain of each filter.

                               65

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                           TABLE  7-1

             SOLUBLE SULFATE .ANALYSES OF FILTERS-
             FROM THE HOT SIDE PRECIPITATOR TESTS
 Unuse'd' samples from batch of-first' test  (6/74).  No
 samples from" actual blank run (where no weight gains were
 observed)  are available.
        Sample Mo.
             11
             18
             IF
pHa

6.6
6.8
6.9;
Total mg°
SO;=/filter

   •v.0.2
   M).2
 Reported
wt gain,'mq
        SetV'from second test  (1/75)'

Unused.f perforated;,unbaked'   9.4'           M)'.2
Unusedr perforatedv'b'aked---'  - 9-i4~--   -"_-  M).2
             Sll              7.6            4'.4
             S12              7.7            4.2
             S13              7.4            5.1
             S14<              7.0-           5.0
             515              7.1            5.6
             S16              7.1            5.6
             S17              7.0            6.0
             518              6.8            5.6
                             4.98
                             4.96
                             5.58
                             5.56
                             6.06
                             6.10
                             5.94:
                             6.04
        Set 2 from second test  (1/75)'

Unused, perforated, baked     9.3
Unused, solid, baked'          9.7
             S20              6.8
             S21              6.7
             S22              7.1
             S23              7.4
             S24              7.2
             S25              7.3
             S26              7.2
             S27              7.1
             S28              7.0
             S2F              8.2
              M)
                 3
               7.3
               5.1
               4.6-'
               5.2
               4.5
               5.0
               4.6
               4.9
               4.6
               5.5
                  8; 34:'
                  5.30>
                  5:: 22
                  5.40
                  4.80
                  5.44
                  5.24
                  5.50
                  4.86
                  6.24
a pH determined after the filter sample was' in contact with 10 ml
  of distilled water  (pH 5.6) for 1 hr.

b The total soluble sulfate was determined by a Ba(ClO») 2. titration
  following a water'extraction of the sample.

                                66
The formation of sulfate is presumed  to be  due  to reaction of.
SO2 on basic sites, of the  filters.  Although  no filters  from the
blank run of-the initial test were, available, unused-filters.
from the same original, batch'were-considerably  less-: basic
than unused-filters from-.the second test  and, therefore,  less
likely to cause; sulfate formation.

Figure 7-1 shows in graphical  form the results  from.the, hot^-side'
installation presented in  the previous table  as well, as.-data-
from tests at-Bull-Run Steam Plant.   The  filter substrate material
was the-same but the flue  gas temperature, was quite (different.
(600"F at- the.hot  side-unit and 300°F at  Bull Run).  The solid
line indicates  a one to one correspondence.   No correlation was
found-between.SO2  content  of the gas  and  weight gains.
                                       Figure 7-2. shows the weight' gains
                                       substrates- versus the  temperature
                                       exception  of • the'Pre 6/74  point,  .
                                       to hold.   The Pre 6/74,represents
                                       Steam. Plant'teat shown in  Table 7
                                       was quite  neutral compared to the
                                       test.
                                                                                     of• Blank Andersen Impactor
                                                                                    .of; the. flue gas.  ' With the,"
                                                                                    a linear relationship seems
                                                                                     data from the first hot side
                                                                                    -1.  In.this case  the substrate
                                                                                     basic substrates  in the second
                         Figure  7-3  shows  the results of tests of several type_s of. 47 mm
                         filter, substrate  media at different flue gas conditions.  The
                         weight  gains seem-to depend more on the temperature than on the
                         concentration of  S02 present.

                         Figure  7-4  shows  the results of preconditioning glass fiber
                         substrates.   Also even without preconditioning there appears
                         to  be.-a saturation limit at which the weight increases stop.

                         Figure  7-5  shows  the weight gains of Andersen Impactor substrates
                         versus  exposure time for preconditioned-and unconditioned sub-
                         strates.  The dates at the top of the figure indicate the time
                         at  which these substrates were,acquired from Andersen 2000, Inc.
                         The 6/74 Normal Substrates, show an-increase and leveling off
                         with exposure time while the 6/74 Preconditioned Substrates
                         show somewhat smaller weight gain.  The "HOT" 6/74 Preconditioned
                         Substrates  would  seem abnormal compared to Figure 7-2 but apparently
                         the conditioning  with hot flue gas reduced the weight gains for
                         this filter set-.   The 1/75 Normal Substrates show a possible
                         linear, relationship, although.certainly not conclusively.  The
                         Preconditioned 1/75 Substrates' indicate a satisfactorily low
                         weight  gain versus exposure time.

                         The general procedure used to obtain samples- and. investigate.
                         this problem in more detail was to pump filtered flue gas through
                         a number of stainless steel 47 mm Gelman filter holders arranged
                         in  series-.   The first filter served to remove the particulate,
                         and the remaining five filters were .then only exposed to the gas.
                                                                                  67

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    6  -
                  -  COAL FIRED POWER  BOILERS
               0    PORTLAND CEMENT  KILN
                                         400               500

                                      GAS TEMPERATURE,  °F
Figure  7-2.   Anomalous Weight  Increases of Andersen  Glass Fiber Impaction  Substrates
              at Different Flue Gas'Temperatures.
                                                                                B -P
                                                                                0) C.
                                                                                in tr>
                                                                                M -H
                                                                                0) <1)
                                                                                •o »
                                                                               X O
                                                                               iH If)
                                                                                9 A
                                                                               w o
                                                                               £ O
                                                                                tr> a)
                                                                               •H 4J
                                                                                IM ui
                                                                                O £>

                                                                                c w •
                                                                                o   o)
                                                                                01 ^ 0)
                                                                                •HOW
                                                                                M U id
                                                                                ID O O
                                                                                a fl n
                                                                                           00
                                                                                           vo
                                            9W ' ''OS

-------
   1.5
    1.0
=
     .5
       200'
         [                r
•  GELMAN TYPE A (OLD)
O  GELHAN- SPECTRa GRADE TYPE A'
J" MSA 1106:BH
V  REEVE ANGEL 900 AF
COAL FIRED POWER BOILER
550 PPM SO?
                                                      CEMErtT
                                                      PLANT
                                                      50 PPM-
                                                      SO,
    300              400-

      TEMPERATURE, °F-
                                         500
    Figure. 7-3.  Anomalous-Weight Gains of Various 47 ram-Dia. Glass
                 Fiber Filters at Different Temperatures. (60 minute
                 samples at flowrates of 0;25 .acfm).
                                  70'
                                                                                  O - NORMAL'
                                                                                     - PRECONDITIONED
                                                                                                              A
                                                                                                              A-
                                                                                                               2-         3

                                                                                                                EXPOSURE, HOURS
                                                                    Figure  7-4.   Anomalous Weight Gain of 64 mm Diameter Reeve Angel
                                                                                 900 AF Glass Fiber Filters.
                                                                                                                      71

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   1.5
                      SUBSTRATES6/74
           D  PRECONDITIONED SUBSTRATES     6/74
           A  NORMAL SUBSTRATES             1/75   ~r
        _  A  PRECONDITIONED SUBSTRATES     1/75
 Ten different types of filter media were tested at 2 industrial
 sites; the outlet of a hotside electrostatic precipitator on
 a cement kiln (Citadel), and the outlet of a coldside electro-
 static precipitator on a coal fired boiler (Bull Run).  The
 results of these tests are summarized as follows:

        The pH of the filters varied widely from batch to
        batch before testing.

        There was a definite correlation between high initial.
        pH and weight gains upon testing.

        The pH decreased during testing.

        A large fraction of the weight gain in every case
        was found to be the result of sulfate formation on
        the filter media.

        For a given temperature, the filters seem to "saturate"
        and not gain additional weight after a period of time
        (2-6 hours).

 It is presumed the sulfate was formed by the reaction of sulfur
.dioxide with basic sites on the surface of the glass fibers.  This
 is a phenomenon which was known to occur in ambient sampling,*
 but which had been neglected or ignored in stack sampling.

 Two approaches were attempted to avoid the problems of substrate
 weight gains.   Substrates were preconditioned by long exposure
 to the flue gas  so that most of the basic sites were neutralized
 before using them,  and a search was made for substrate materials
 which do not react with the flue gas.   Preliminary results  indicate
 that preconditioning overnight reduces the magnitude of the
 anomalous weight gains by approximately a factor of ten. Also,
 in the tests to date.  Teflon, Whatman GF/D and GF/A, improved
 quartz, and Reeve Angel 934 AH, are filter media which show little
 weight change when exposed to flue gas.

 The detailed results of this work are reported in the Reports
 to Contract 68-02-0273.   Work continued in an effort to reduce
 the interference to a  more nearly tolerable level.
                  1           2          3

                       EXPOSURE,  HOURS
Figure 7-5.   Anomalous Weight Gains of Andersen Impactor Glass
             Fiber Impaction Substrates.
                                                                                                                73
                                72

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                      SECTION VIII
                       REFERENCES
1.  Smith, W. B. and Jack R. McDonald.  Calculation of
    Charging. Rate of Fine Particles by Unipolar Ions.
    APCA Journal.  25(2), February 1975.

2.  Leutert, G. and B. Bohlen.  The Spatial Trend of Electric
    Field Strength and Space Charge Density in Plate Type
    Electrostatic Precipitators.  Staub.  32(7), July  1972.

3.  Gooch, J. P., Jack R. McDonald, and Sabert Oglesby,  Jr.
    A Mathematical Model of' Electrostatic Precipitation.
    EPA Report No. EPA-650/2-75-037, prepared under Contract
    No. 68-02-0265 by Southern Research Institute, Birmingham,
    Alabama.  April 1975.

4.  Forrest, J. and L. Newman.  Sampling and Analyses of
    Atmospheric Sulfur Compounds for Isotope Ratio Studies.
    Atmospheric Environment. 7, 1973.
                       SECTION  IX
                  CONVERSION FACTORS
               (English to  Metric Cnits)
Multiply


  ft3

grains/ft3

 feet

 inches
  By               To Obtain


0.0252                 ms

2.288              grams/m3

0.304                meters

0.254'              millimeters
                            74
                                                                                                          75

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