C.I
Do not WEED. This document
should be retained in the EPA
Region 5 Library Collection.
Evaluation of Continuous Monitoring
Systems for Pressurized Baghouses
March 1981
Submitted to:
U.S. Environmental Protection Agency
Air Enforcement Branch
230 South Dearborn Street
Chicago, Illinois 60604
ENGINEERING-SCIENCE
DESIGN RESEARCH PLANNING
501 WILLARD STREET DURHAM, NORTH CAROLINA 27701 9191682-9611
OFFICE IN PRINCIPAL CITIES
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EVALUATION OF
CONTINUOUS MONITORING SYSTEMS FOR
PRESSURIZED BAGHOUSES
March 1981
Theodore B. Michael is
Project Manager
Engineering-Science
501 Willard Street
Durham, North Carolina 27701
EPA 905/2-81-001
Task Managers
Robert L. King George Hurt
Region V Air Enforcement Branch
U.S. Environmental Protection Agency
Chicago, Illinois 60604
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NOTICE
This is not an official policy and standards document. The opinions,
findings, and conclusions expressed herein are those of the authors and
not necessarily those of the United States Environmental Protection
Agency.
Any mention of trade names, products, or organizations does not consti-
tute endorsement by the United States Environmental Protection Agency.
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CONTENTS
FIGURES iv
INTRODUCTION 1
BAGHOUSE CYCLES 4
CONTINUOUS OPACITY MONITOR INSTALLATIONS 4
Recorder Output 5
Calibration 6
Equivalent Path Length 6
Baghouse Design 7
Location of Monitor 8
Gas Flow 8
SUMMARY OF PROBLEMS 8
SUMMARY 21
APPENDIX A: INSPECTIONS OF PRESSURIZED BAGHOUSES
m
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FIGURES
1. Negative Pressure Baghouse 2
2. Positive Pressure Baghouse 3
3. Multistack Baghouse with Top-Center Discharge 9
4. Multistack Baghouse with Verticle Side-Discharge 10
5. Baghouse with Horizontal Side-Discharge 11
6. Multistack Baghouse with a Peak Discharge 12
7. COM Installation at a Multiple Discharge Baghouse 13
8. COM Installation in an Eaves-Discharge Baghouse 14
9. Horizontal Side-Discharge Baghouse with Smoke
Originating Near the Discharge 15
10. Horizontal Side-Discharge Baghouse with Smoke at
the Center of the Cel 1 16
11. Horizontal Side-Discharge Baghouse with Smoke
Away from the Discharge 17
12. Smoke Exiting from Discharge Plenum 18
13, 14. Cell discharges face each other across a common plenum 20
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EVALUATION OF CONTINUOUS MONITORING SYSTEMS FOR PRESSURIZED BAGHOUSES
INTRODUCTION
This study, initiated in response to Task Order 62 of Contract
68-01-4146, is intended to determine the conditions which must be met to
ensure successful installation of a continuous opacity monitor (COM) at
a pressurized baghouse (PB).
Baghouses are efficient devices for removing particulate matter from
discharge gas streams. Gas is drawn or blown through the bags which are
usually contained in individual cells. Figure 1 diagrams a negative pres-
sure baghouse; Figure 2 diagrams a pressurized baghouse. The PB does not
require dampers on the discharge side of each cell to isolate the cells
for cleaning, and it does not require ductwork at the discharge side to
connect to the blower. For large installations, the cost differential
can be considerable. Commonly, PB installations are used in the ferrous
and nonferrous industries, and are almost universally used as a method
of particulate control for emissions from electric arc furnaces.
Properly designed, well-maintained baghouses can maintain low discharge
particulate levels with gas opacities approaching zero. Sudden bag failure
can occur for a number of reasons:
0 Hot particles can burn holes in one or several bags,
0 Hot gas can cause failure of many or all bags,
0 Sharp-edged material may tear the bags,
0 Normal operation may wear the bags, causing tears or holes,
0 Improper installation may allow gas to bypass the bags, or may
permit a bag to come loose, and
0 Corrosion or erosion may cause structural failure, permitting gas
to bypass the bags.
Many of these failures were observed during plant visits (Appendix A).
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OUT
BAS IN
DAMPER
Figure 1. Negative pressure baghouse.
rv
O
ENGINEERING-SCIENCE
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DISCHARGE
A A
DISCHARGE
A
GAS IN
DAMPER
Figure 2. Positive pressure baghouse.
01
6
ENGINEERING-SCIENCE
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Federal regulations frequently require that baghouses be equipped with
COM's to monitor opacity of the discharge gas stream. For example, 40 CFR
60, subpart AA (par. 60.270 et seq) requires installation of a COM, and
defines excess emissions as "all six minute periods during which the average
opacity is 3 percent or greater."
This report reviews problems connected with the capabilities of exist-
ing COM equipment to reliably indicate discharge opacity from PB systems.
Contacts were initiated, and visits were made to a trade association, to
PB manufacturers, to COM manufacturers, and to plant sites.
BAGHOUSE CYCLES
Large PB installations usually consist of several cells arranged in one
or several rows. A cell may be onstream for 1 or more hours before cleaning.
Each cell is cleaned in sequence, usually on a fixed time cycle. Occasion-
ally, a high pressure drop across the bags is used to initiate the cleaning
cycle. Cleaning cycles vary, but usually last for 1 to 2 minutes, during
which the bags are either shaken or subjected to pulses of reverse air.
The dust from the bags settles into the bottom hoppers, and the cell is
returned to service.
During the cleaning cycle, some dust may be emitted. When a cell is
first returned to service, opacities of 20% to 50% may be observed for 15
to 20 seconds. Many COM systems include means to average discharge opacity
during 6-minute periods, in accordance with regulations. One system was
set to alarm only if 3% opacity was exceeded continuously for 6 minutes.
Although this system avoided alarms arising from cleaning cycles, it also
avoided many alarms which could arise from equipment failure.
CONTINUOUS OPACITY MONITOR INSTALLATIONS
Continuous opacity monitors were originally developed for control of
emissions from stacks. Opacity was controlled at 20%, and path length
rarely exceeded 35 feet. The light frequency range of the COM was set in
the "photopic" range to correlate monitor readings with visible readings by
a trained observer. Performance specifications for these systems are
contained in 40 CRF 60, Appendix B.
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The path lengths of existing COM systems are limited by three inter-
related phenomena:
0 Light from the transmitter is emitted in the form of a cone. In-
crease in path length increases the base of the cone, so light
energy incident on the photocell is inversely related to the
square of the path length.
0 Each electronic system has some internal noise. As light energy
on the photocell decreases, capability to differentiate incident
light levels decreases because output signals fall into the system
noise range.
0 Photopic light sources originate from incandescent lamps. Higher
output lamps have shorter life and less stable light output.
Only four of the nine COM manufacturers contacted by ES offered equipment
which might be suitable for the long-path requirements of PB systems:
0 Dynatron,
0 Contraves,
0 Lear Siegler, and
0 Datatest.
All of the manufacturers contacted who were interested in supplying long-path
COM equipment expressed the belief that the maximum path length will be about
100 feet for photopic systems. The longest path COM system which ES could
locate was 65 feet.
Only one supplier produces a nonphotopic (laser-based) COM, but this
system does not meet the requirements of 40 CFR 60, Appendix B. All manu-
facturers agree that a laser system, combining high-energy output with a
narrow-angle light beam, should be a satisfactory long-path COM (although
some questioned the reliability of laser systems). It would detect changes
in opacity, but it might not relate to visible opacity measurements.
If currently available COM equipment is used, more than one unit will
be needed to cover paths longer than 75 to 100 feet. These units may be
placed in series or back to back.
Recorder Output
The 40 CFR 60, Appendix B (par. 4.3) specifies that the system output
shall permit expanded display of the span opacity on a 0% to 100% scale.
Since the prime COM market is for stack installations, standard units are
equipped with 0% to 100% charts. It is impossible to differentiate low-level
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opacities (0% to 5%) on these charts. If the charts are to be used as an
enforcement tool, a different scale, perhaps 0% to 20%, should be required.
In addition, the source should be required to relate periods of excess emis-
sions with steps taken to prevent such emissions.
Calibration
Available COM systems periodically check themselves for zero setting and
100% span. Existing performance specifications permit zero drift of 2% opa-
city in 24 hours. This is not significant when high opacity levels are being
considered, but it is critical when 3% opacity is the control level. Provi-
sion should be made for periodically verifying that the COM system is accu-
rate at the alarm level; this would also permit verification that installed
system alarms are activated when the equivalent average 6-minute opacity is
3% or greater.
Equivalent Path Length
Gases from PB systems are frequently discharged from multiple openings or
from significantly nonround openings; two such systems are discussed. In a
system with eleven 3' x 2' stacks, the total area is
3' x 2' x 11 = 66 ft2.
If the optical path is across the 3-foot stack dimension, the total path length
would be
31 x 11 = 33 ft.
A 9-foot diameter duct has a similar cross section (64 ft2).
Appendix B of 40 CFR 60 (par. 4.3) gives a path-length correction:
log(l - 0]) = Li/L2log(l - 02)
where 0] = opacity of effluent based on L],
03 = opacity of effluent based on l_2,
L] = the emission outlet path length, and
l_2 = the monitor path length.
Substituting in this equation
log(l -.03) = 9/33 log(l - 02),
1 - 02 = 0.894
02 = 0.105 = 11%
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If the COM is set to indicate opacity of the multiple discharges corrected
to a single equivalent duct, opacity of gas in the COM light beam would
have to be almost 11% to register 3% opacity at the COM output.
Failure in one cell of an installation would cause high-opacity condi-
tions only in the discharge from that cell. If the COM is set to average
all stack discharges, the correction would be
log(l - 0.3) = 1/11 log(l - 02)
1 - 02 = 0.715
02 = 0.284 = 28%
Thus, opacity in a single cell would have to reach 28% before the COM would
indicate 3% opacity.
Path-length corrections were included in the electronics of all of the
COM systems which were inspected, but it was not possible by inspection to
determine the specific correction for any given system.
Baghouse Design
Of the various PB designs which have been produced, many of them are one
of a kind, and many are of limited production. It was not possible to inspect
all designs in the limited time available, but it was possible to broadly cate-
gorize PB's by bag-cleaning mechanism and by discharge arrangement.
The two main bag-cleaning mechanisms are mechanical shakers and reverse
air. Shakers or rappers are connected to the top of the bags. When the clean-
ing cycle is initiated, flow of air to a cell is interrupted by the damper at
the inlet duct (Figure 2), and the tops of the bags are vibrated for about a
minute by a mechanical system. Dust falls into the hoppers under each cell;
then the damper is opened to return the cell to service.
Reverse-air systems have a similar cycle, but each bag is internally
supported by a steel helix. When the inlet damper closes, a damper in an
auxiliary duct opens and connects the cell to a blower which sucks reverse
air through the bags. The dust cake pulled from the inner bag walls falls
into the hopper from which it is removed mechanically.
Neither of these cleaning methods significantly affects gas monitoring,
but both cell and discharge arrangements directly affect COM measurements.
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Generally cells are arranged in rows. Whether one or several rows of cells
are used is determined by cell size, gas flow, and space availability.
A design consisting of multiple cells with top-center discharge (Figure 3)
is frequently seen, but many other designs are in use. Figure 4 shows a ver-
tical side-discharge. Figure 5 is a horizontal side-discharge. Figure 6
is a peak discharge.
Location of Monitor
It is current practice to install one COM for each row of cells if the
light path is not too long, but this practice may permit discharge of
particulate-laden gas which does not cross the COM path.
The COM's installed in a row of stacks, as shown in Figure 7, are sub-
ject to atmospheric effects such as fog, heavy rain, and fugitive dust. An
installation of the type shown in Figure 8 might not be affected by particu-
lates originating from a failure near either sidewall.
Gas Flow
Common to all baghouses which were inspected was the fact that gas was
not mixed in the baghouse. This fact was verified by visual inspections of
bag failures (Appendix A) and by photographs of discharges from smoke candles
released from various locations in several baghouses. The photographs (Fig-
ures 9 to 12) clearly demonstrate that smoke travels in distinct striae from
smoke candles to the baghouse discharge. There is no location where a COM
light beam can be certain to intersect all high opacity events. Addition of
more COM's would enhance the probability of "seeing" all events, but it would
be difficult to be certain that all high opacity events would be registered
without installing several COM systems at each row of cells.
It would be necessary to blend the gas stream to be sure that some par-
ticulates from a baghouse failure pass the COM beam. Even if this were done,
visual inspection indicates that significant failures can exist with discharge
opacity below 3%.
SUMMARY OF PROBLEMS
The essential problem of effective COM installations on PBs is the possi-
bility that striae of gas containing heavy loadings of particulates will not
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Figure 3. Multistack baghouse with top-center discharge.
ENGINEERING-SCIENCE
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Figure 4. Multistack baqhouse with vertical side-discharqe.
10
ENGINEERING-SCIENCE
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Figure 5. Baghouse with horizontal side-discharge.
11
ENGINEERING-SCIENCE
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r
Figure 6. Multistack baghouse with a peak discharge.
12
ENGINEERING-SCIENCE
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GAS DISCHARGE
LIGHT PATH
Figure 7. COM installation of multiple discharge baghouse.
13
ENGINEERING-SCIENCE:
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Figure 8. COM installation in an eaves-discharge baghouse.
14
ENGINEERING-SCIENCE
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Figure 9. Horizontal side-discharge baghouse with
smoke originating near the discharge.
15
ENGINEERING-SCIENCE
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Figure 10. Horizontal side-discharge baghouse with smoke
at the center of the cell.
16
ENGINEERING-SCIENCE
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Figure 11. Horizontal side-discharge baghouse with smoke
away from the discharge.
17
ENGINEERING-SCIENCE
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Figure 12. Smoke exiting from discharge plenum.
ENGINEERING-SCIENCE
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interrupt the COM light beam. In general, no provision is made to blend the
gas stream before it reaches the COM beam, but such blending would reduce
opacity of the gas stream to a level where significant failure of portions
of the PB could be below the sensitivity of the COM.
Secondary problems arise from multi-stack installations, where the COM
beam travels thru the atmosphere between the stacks. Here, the COM is subject
to false readings due to fog, rain, and fugitive dust.
In one PB arrangement, the cell discharges face each other in a discharge
plenum. This is intended to provide blending of the gas stream, but Figures
13 and 14 show that striae of gas exist for significant distances in the
discharge plenum. It is not known whether the gas stream is blended by the
time it reaches the discharge point. However, most baghouse designs make no
provision for blending the gas stream. Although it appears possible to retro-
fit existing PBs' to blend the gas stream, no such device has been developed
at this time.
After the gas stream has been blended, consideration might be given to
monitoring techniques which are more sensitive than COM systems. One such
system, which uses forward scatter of a light beam, is a photometer (nephelo-
meter) manufactured by Sigrist Photometer A.G. of Zurich, Switzerland. This
system could extract a sample of blended gas, and detect changes in particu-
late loading far below the 3% opacity level, thus permitting early detection
and correction of PB failure.
Additional study is required, first to develop simple, inexpensive
blending techniques for each type of PB, and then to demonstrate that relia-
ble techniques are available to detect changes in particulate loading which
result from reasonable baghouse failure. The first portion of the suggested
study would divide existing PB installations into broad categories, and
design a simple blending device for each category. Each design would be
tested in the field by retrofitting an existing installation to demonstrate
technical and economic feasibility of the design.
During the field tests, bag breaks could be created to compare the
sensitivity of COM devices and other devices such as the photometer (nephelo-
meter) mentioned above.
19
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ENGINEERING-SCIENCE
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SUMMARY
Pressurized baghouses are frequently used in large systems controlling
particulate discharges because they are less expensive. Preliminary tests
indicate that th-ere is striation of the gas streams in baghouse cells, so
some PB equipment failures may occur which will not be registered by COM
equipment. Reliable monitoring depends on a representative gas stream
passing the COM beam. But significant equipment failure can exist with
indicated discharge opacity less than 3%. Many existing systems could be
modified to provide gas blending. Equipment exists which can detect particu-
late loadings far below the 3% opacity level, but this equipment does not
relate directly to opacity-
Parameters which must be met for a successful COM installation in a PB
are:
0 The gas stream must be blended.
0 The COM beam must not exceed 100 feet,
0 The COM output must be expanded so that 3% opacity covers a reasonable
portion of the scale,
0 Path-length corrections should be permitted only where there is a
difference in measured path-length and discharge path-length, and
0 The COM beam should not be affected by external climatic effects.
21
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APPENDIX A
INSPECTIONS OF PRESSURIZED BAGHOUSES
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ES
ENGINEERING-SCIENCE
7903 VVESTPARK DRIVE McLEAN. VIRGINIA 22102 703/790-9300
CABLE ADDRESS ENGINSCI
TELEX 89 5401
September 14, 1979
3122
Mr. Robert L. King
(EN-341)
U. S. Environmental Protection Agency
401 M Street, S. W.
Room 3202
Washington, D. C. 20460
Subject: Inspection of Baghouse
Dear Mr. King:
On September 6, 1979 I inspected a recently-constructed pressurized
bagbouse which removes particulates from air exhausted from electric arc
furnaces. The site is located in Pittsburgh, Pa.
The installation, consisting of two rows of cells (six cells in one
row, and five cells in the other), has been in operation for about two
months. The system follows normal Wheelabrator-Frye design practice:
there are large gratingcovered areas on the floor which admit secondary
air. The secondary air, rising by convection, may mix with gas from the
bags and lower the opacity by diluting the particulate-laden gas.
Four Dynatron continuous opacity monitors are used. The light sources
are mounted at the ends of the baghouses, and a pair of reflectors are
mounted back-to-back at the center of each row. The output from both
monitors on a baghouse row is fed into an electronic averaging device
(6-minute), and the output of each averaging device is displayed on a
continuous recorder. Each light path is about 85 ft. long. The top
of the openings immediately above the bags is about 5 ft. wide. The
'monitors are mounted about a foot off the centerline. Considering the
width of the opening, and the fact that the monitors are off center, it
is possible that high dust loads might not be recorded by the monitor.
OFFICES IN PRINCIPAL CITIES
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Mr. Robert L. King
Septc-ber 14, 1979
Page 2
In summary, this recently-completed installation has two significant
deficiencies:
o Exhaust gas is diluted upstream of the monitors.
o The monitor light path is so located that it may not see dust
originating from many points in the haghouse.
Yours very truly,
ENGIKEEP
Theodore B. Michaelis
Air Engineering & Monitoring
TBM/rb
cc: G. Hurt
R. Neulicht
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:ESj
ENGINE ERING-SCIENCE
7903 WESTPARK DRIVE Mel EAN, VIRGINIA 22102 703/790 9300
CA3LE ADDRESS EN'
TELEX 39 3401
December 31, 1979
3122.00/7
Mr. Robert L. King
U. S. Environmental Protection Agency
401 M Street, S. W.
Washington, D. C. 20460
Re: T. 0. 62, Contract No. 68-01-4146
Trip Report
Dear Mr. King:
On November 7, 1979 the pressurized baghouse at a non-ferrous metal
plant, located in central Pennsylvania, was inspected. This is a "side-
discharge" baghouse, the gas exiting through louvres in one side of a cell.
Figure 1 is a plan of the baghouse, showing the two rows of four cells,
each. There are no internal dividing walls in the rows of four cells, but
a walkway, with walls, separates the two rows. Figure 2 is a section of the
baghouse, taken at the walkway between cells. Figure 3 is an end view,
showing the bag arrangement on one side. Figure 4 is a photograph of the
system.
There are 20 bags to a row, 8 rows to a set, two sets in each cell.
Counting the bag furthest from the gas discharge as Number 1, smoke was
released adjacent to bags 2, 6, 10, 14, and 18. The stnoke candle was held
between rows of bags. Traverses were made releasing smoke near the floor,
and about 3 feet from the top of the bags.
In all cases, it was observed that the smoke rose in distinct laminae.
Sraoke originating near the discharge exited at the bottom of the discharge,
and smoke originating away from the discharge exited at the top. It was
apparent that a beam from a continuous opacity monitor would not be affect-
ed by participates originating from at least half the bags.
There is no location where a single continuous opacity monitor (COM)
could be installed in this type of baghouse to assure accurate opacity
measurement. If the particulate-bearing lamina misses the COM beam, the
monitor will not register the discharge. If the particulate-bearing lamina
crosses the COM beam, the monitor will register an opacity higher than the
average opacity of the gas stream.
IN P.RINClFAL CITIES
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Mr. Robert L. King
D,jce.-ber 31, 19/9
Page 2
The photographs, Figures 5 to 10, show the gas larainae in an operating
baghouse. Figure 5 shows the s.-joke originating near the top of bag 18. The
s-noke remains highly concentrated, and exits at the bottom of the discharge.
Figures 6, 7, and 8 show gas originating near the top of bag 10. The
distinct lamina of gas exits at the middle of the discharge louvres.
Figures 9 and 10 show gas originating at the bottom of bag 2, and
Figure 9 shows the saiTie gas exiting at the top of the discharge.
Smoke was released from many points in addition to those shown in
the photographs. In every case, it was evident that flow in the baghouse
was not turbulent. Gas originating furthest from the discharge rises to
the top of the baghouse, and exits at the top of the louvres. Gas origi-
nating at the discharge side of the baghouse exits at the bottom of the
louvers. There is no location where an opacity raonitor beam could be
expected to reliably measure actual gas opacity.
A monitor beam would miss high-opacity gas in most cases, and would give
readings higher than the average gas opacity when the particulate-laden lamina
intercepted the light beam.
Inspections of other baghouses will be made to determine if significant
differences in flow pattern can be found for different baghouse designs.
Sincerely,
ENGINEERTNG-SCIENCI
eodore B. Michaelis
Air Engineering & Monitoring
TBM/rb
Encs.
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until mil!
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FIGURE 4
Side Discharge Baghous?
-------
FIGURE 5
Smoke originating adjacent to bags near
exit passes through bottom of louvre.
-------
FIGURE 6
FIGURE 8
Smoke originating adjacent
to bags at the center of the
baghouse exits at the center
of the louvres.
FIGURE 7
-------
FIGURE 9
FIGURE 10
N.*
Smoke originating adjacent to bags farthest from
discharge exits near top of louvres. Diamond-shaped
objects on Figure 10 are due to dust on camera lens.
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X I - 1 . ; ; '., - /- > I - / > ;
' i t i. i . A i _ \ (:, -. __ *, i i ..
^cto', .?r 16, 1979
3130.00 -;>12
Mr. Robert L. King
Stationary Source Knforce icnt Oivision
/N 341
A01 M S_.--oi , S.W.
Washington, D,C. 20460
Re: T.O. 62, Contract 63-01-4136
D.-.ar Mr. King:
Cn October 3 and 4, 1979, an orar at 1 ;;g "- J'-.OUSG v.-.s visited at a south-
ern iaini--stc-el plant. 'Hie b igho^.se co^^'f stf=-d of 11 colls, e.sch r cntaii"' i ag
about 300 bags (6000 square feet in each cell). With no_ ;;al gas flow in the
baghouse, S^'joke was relppsed from several locations inside the baghouse, and
the direction of the gas flow was norad. In ,'11 cases, there was severe
lamination of the s"ioke in the gas atr'ea.n.
The general arrange nent of a single cell (without the discharge cowl) is
chown in Figure 1. Figure 2 shows a plan, the bag supports, and the location
smoke was released.
Smoke released at Location 1 is shown on Figures 3 and 4. It can be seen
from the photographs that the smoke is not mixed with the general gas stream.
Visual observation disclosed that the snoke is confined to one corner of the
discharge opening, and that this lamination continues up through the discharge.
Figures 5 shows smoke released at Location 4 about five feet above location
1. Here it is apparent that the s ~'cke r<-.?ains in one corner of the discharge.
Figure 6 shows snoke orgi:;atlng from Location 5, a few feet -"way from lo-
cation 1. Note that this snake Is slightly e. -,ay from the corner of the dis-
charge.
Figure 7 shows S',;oke from Location 2. This snoke touches none of the
vails of the discharge cowling, vut regains in a tight bundle until it is re-
leased to the atv.osphere.
Figure 8 shews the s:r.oke candle being put at Location 3. Figure 9 shows
the r:u,ke rising from the corner of the bags"use cell (L-cation 3), and Figure
10 shea's that the pr-.oke continues to be ,-jfgr-g'ted as it passes through the
discharge.
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October '6, 1979
It is "1-.i i..Mit that participate ./.iiiter released from carry places in the
cell, as frou a torn or rapi'ored b^g, could pass up the discharge without
being "seen" by a sl.'gle be i;n of an opacity uonitor. Even if .nnltiple ben-ns
were used, it is probable that so ie pi'S-s^ble particulate paths would be missed.
Although only one pressuri/ed ba-hwuse conf orr.a tion has been tasted, there
is reason to be concerned that all pr .--ss or /.led baghouses will be s\;bject to
stratification of the gas streams. We plan to test other pressurized baghouse
designs, .ind will issue a report covering gas flow in a variety of Vighoi.^e de
signs.
Y.-.urs truly,
TheoaoitJ B. Michael is
Air Engineering and Monitoring
THM/ch
cc:
R. Keulicht
T. _Ward
Hurt"
RTF
RTF
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10' 8"
(4) 2" HOLES
FOR LIFTING
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SMOKE RELEASE POINTS
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DISCHARGE OPENING
BAG
SUPPORTS
FIGURE 3: SMOKE FROM LOCATION
DISCHARGE OPENING
FIGURE 4: SMOKE FROM LOCATION (T
BAG
SUPPORTS
ENGINEERING-SCIENCE
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BAG
SUPPORTS
DISCHARGE OPENING
FIGURE 5: SMOKE FROM LOCATION (4j
DISCHARGE OPENING
FIGURE 6: SMOKE FROM LOCATION
BAG SUPPORTS
ENGINEERING-SCIENCE
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DISCHARGE OPENING
BAG
SUPPORTS
FIGURE 7: SMOKE FROM LOCATION (?]
FIGURE 8: SMOKE CANDLE BEING PLACED AT LOCATION (3
ENGINEERING-SCIENCE
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BAG
SUPPORTS
FIGURE 9: SMOKE FROM LOCATION Q)
DISCHARGE OPENING NOT VISIBLE
DISCHARGE OPENING
BAG
SUPPORTS
FIGURE 10: SMOKE FROM LOCATION
ENGINEERING-SCIENCE
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TECHNICAL REPORT DATA
(Please read Instruction*; on the reverse before completing)
1 REPORT NO.
EPA 905/2-81-001
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
EVALUATION OF CONTINUOUS
PRESSURIZED BAGHOUSES
ITORING SYSTEMS FOR
6. PERFORMING ORGANIZATION CODE
3/81
7. AUTHOR(S)
Theodore B. Michael is
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Engineering-Science
501 Willard Street
Durham, North Carolina 27701
10. PROGRAM ELEMENT NO.
Task Order 62
11. CONTRACT/GRANT NO.
Contract 68-01-4146
12. SPONSORING AGENCY NAME AND ADDRESS
Air Enforcement Branch, Region V
U.S. Environmental Protection Agency
Chicago, Illinois 60604
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Pressurized baghouses (PB) are frequently used in large systems for controlling
particulate discharges. Preliminary tests indicate that there is striation of the
gas streams in baghouse cells, so some equipment failures may not be registered by
continuous opacity monitoring (COM) equipment. Reliable monitoring depends on a
representative gas stream passing the COM beam, but significant equipment failure
can exist with discharge opacity less than 3%. Many existing systems could be modi-
fied to provide gas blending. Equipment exists which can detect particulate loading
far below the 3% opacity level, but this equipment does not relate directly to opac-
ity. Parameters necessary for a successful COM installation in a PB are: the gas
stream must be blended; the COM beam must not exceed 100 feet; the COM output must
be expanded so that 3% opacity covers a reasonable portion of the scale; path-length
corrections should be permitted only where there is a difference in measured path
length and discharge path length; and the COM beam should not be affected by external
climatic effects.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Opacity monitoring
Continuous opacity monitors
Nephelometers
Pressurized baghouses
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19 SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
42
20 SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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