EPA PROJECT REPORT NO. 74-LIM-6
AIR POLLUTION
EMISSION TEST
OOW CHEMICAL
freeport, Texas
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Emission Measurement Branch
, Research Triangle Park. North Carolina
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A STUDY OF GASEOUS AND PARTICULATE
EMISSIONS FROM LIME KILNS AT
DOW CHEMICAL CORPORATIONS'S PLANT B
FREEPORT, TEXAS
May, 1974
environmental science and engineering, inc. ,'
EPA-RTF LIBRARY
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A STUDY OF GASEOUS AND PARTICULATE
EMISSIONS FROM LIME KILNS AT
DOW CHEMICAL CORPORATION
PLANT B
FREEPORT, TEXAS
May, 1974
PREPARED AND SUBMITTED BY:
ENVIRONMENTAL SCIENCE AND ENGINEERING, INC.
POST OFFICE BOX 13454
GAINESVILLE, FLORIDA 32604
PN 73 Oil 042
PREPARED FOR:
U.S. ENVIRONMENTAL PROTECTION AGENCY
EMISSIONS MEASUREMENT BRANCH
RESEARCH TRIANGLE PARK, NORTH CAROLINA
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TABLE OF CONTENTS
Page Number
List of Tables ii
List of Figures iii
1.0 Introduction . 1
2.0 Summary and Discussion of Results 3
3.0 Process Description and Operation 9
4.0 Location of Sampling Points 15
5.0 Sampling and Analytical Procedures 15
Appendices
A - Calculated Emissions Data
B - Field Data
C - Analytical Procedures and Sample Calculations
D - Lab Report
E - Test Log
F - Notes on Plant Operation
G - Project Participants
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LIST OF TABLES
Page Number
Table 2.1 Participate Data Summary - English 4
Table 2.2 Particulate Data Summary - Metric 5
Table 2.3 Gas Data Summary 6
Table 3.1 Summary of Operating Variables 14
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LIST OF FIGURES
Page Number
Figure 3.1 Precipitator Plan and Elevation 11
Figure 3.2 Stack Elevations 12
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1.0 INTRODUCTION
A part of the Environmental Protection Agency's ongoing work in pollu-
tion abatement is concerned with setting performance standards for new
and substantially modified stationary sources. One source under con-
sideration at present is rotary kilns used to calcine lime. Dow Chemical
Corporation operates a large chemical complex in Freeport, Texas which
uses slaked lime in recovering magnesium from seawater and various
other operations.
There are three rotary kilns used to calcine dolomite (CaCO^ • MgCO ).
The plant is capable of operating one, two or all three kilns simultan-
eously. The kilns are serviced by electrostatic precipitators (ESP's)
for the control of particulate emissions. The gas stream from the
operating kilns i s combined prior to the ESP's and then split and ducted
through two ESP's and vented to the atmosphere through two stacks,
one for each ESP.
During the week of April 29, 1974, Environmental Science and Engineering,
Inc. (ESE) conducted three series of tests on the two outlet stacks
under contract for the EPA. During the testing period two of the kilns
were operating simultaneously. Each stack was monitored for particulate
matter, using EPA method 5; opacity, using a modified version of EPA
method 9; C02 and Og, using a modified version of EPA method 3; and CO,
using EPA method 10. In addition, S02 concentrations were measured on
the north stack using EPA method 6 and NOX concentrations were measured
on the south stack using EPA method 7.
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Another provision of the tests was to conduct comparison tests for
participate matter at a single location in the stack using an in-stack
filter and an EPA-5 train. No valid comparison data were obtained due
to equinment difficulties.
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2.0 SUMMARY AND DISCUSSION OF RESULTS
2.1 Participate matter, Orsat, CO, S0_, NOV and opacity data are summarized
£. A
in Tables 2.1 - 2.3.
The total average particulate emission rate was 4.9kg/hr. (10.8
Ibs/hr.) for the two stacks combined. However, this value is probably
somewhat high as the first test on the north stack indicated 5.7 kg/hr.
(12.6 Ibs/hr.) alone. The average for runs 2 and 3 was 3.6 kg/hr.
(7.9 Ibs/hr.) for the two stacks combined, which is substantially lower.
It is not known why the first run on the north stack indicated such a
high emission rate. Some error may have been introduced because the
person manipulating the probe misunderstood where the probe markings
were to be located; instead of locating the marking at the outside of
the pipe nipple, he positioned it at the inside stack wall on the first
run only. This means that each point sampled was displaced from the
equal area center by approximately 4 inches. It seems unlikely that
this would introduce a very large error, however., it is possible that
the probe tip came so close to the far stack wall that it contaminated
the sample with particulate off the stack wall.
Laboratory analysis of the particulate samples showed a large amount
of variability in the weight fraction caught in the various parts of
the sampling train (probe, filter, etc.). The average for all of the
runs was as follows: Probe - 20.5%, Filter - 32%, Back Half Water -
29.5%, Back Half Acetone - 18%. This means that only 53% of the total
catch was caught in the probe and filter (front half), the remaining
portion being in the impingers.
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Table 2.1 Particulate Data Summary (English)
RUN NUMBER
DATE
STACK DESIGNATION
Volume of Gas Sampled, DSCF^
Percent Moisture By Volume
Average Stack Temperature, °F
Stack Volumetric Flow Rate, DSCFM
Stack Volumetric Flow Rate, ACFM '
Percent Isokinetlc ,_.
Process Weight Rate, Ton/Hr ^'
1
1
April 30, 1974
NORTH SOUTH
43.39
18.5
373
49.144
93.559
128
20.3
99.62
17.1
449
47,834
97,870
119
20.3
2
May 2
NORTH
131.33
17.6
361
45.911
85,521
103
20.0
, 1974
SOUTH
131.66
17.9
412
42,945
85,190
110
20.0
May 3
NORTH
133.72
18.2
366
46,318
87,951
104
20.3
3
, 1974
SOUTH
136.15
18.6
406
45,693
91,500
no
20.3
Averages
NORTH SOUTH
102.81
18.1
367
47,124
89,010
111
20.2
122.48
17.9
422
45,490
91 ,520
113
20.2
PARTICIPATES - PROBE AND FILTER
Gr/DSCF <3)
Gr/ACF
Lb/Hr
Lb/Ton Feed
46.7
0.0166
0.0087
7.00
0.344
39.5
0.0061
0.0029
2.51
0.124
30.6
0.0036
0.0019
1.42
0.071
21.9
0.0025
0.0013
0.95
0.048
51.2
0.0059
0.0031
2.35
0.116
49.5
0.0056
0.0028
2.20
0.108
42.8
0.0087
0.0046
3.59
0.177
37.0
0.0047
0.0023
1.89
0.093
PARTICULATES. TOTAL
Mg
Gr/DSCF
Gr/ACF
Lb/Hr
Lb/Ton Feed
Percent Implnger Catch
84.2
0.0299
0.0157
12.62
0.62
44.5
63.9
0.0099
0.0047
4.06
0.20
38.2
49.4
0.0058
0.0031
2.28
0.114
38.1
126.4
0.0147
0.0074
5.45
0.272
82.7
71.2
0.0082
0.0043
3.26
0.161
28.1
106.7
0.012
0.006
4.74
0.233
53.6
68.3
0.0146
0.0077
6.05
0.298
36.9
99.0
0.0122
0.0060
4.75
0.235
58.2
Dry standard cubic feet at 70°F and 29.92 Inches Hg.
These values are averages for the kilns (see Table 3.1) I.e. total feed rate for run #1 was 40.6 ton per hour.
Grains per DSCF.
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Table 2.2 Particulate Data Summary (Metric)
RUN NUMBER
DATE
STACK DESIGNATION
Volume of Gas Sampled, DSCM^'
Percent Moisture by Volume
Average Stack Temperature, °C
Stack Volumetric Flow Rate, DSCMM
Stack Volumetric Flow Rate. ACMM
Percent Isokinetic /?\
Feed Rate, M-Ton/Hrv ;
1
April 30,
NORTH
1.23
18.5
189
1392
2650
128
18.4
1975
SOUTH
2.82
17.1
232
1355
2772
119
18.4
2
May 2,
NORTH
3.72
17.6
183
1300
2422
103
18.2
1974
SOUTH
3.73
17.9
211
1216
2413
110
18.2
3
May 3.
NORTH
3.79
18.2
186
1312
2491
104
18.4
1974
SOUTH
3.86
18.6
208
1294
2591
no
18.4
Averages
NORTH SOUTH
2.91 3.47
18.1 17.9
186 217
1334 1288
2521 2592
111 113
18.3 18.3
PARTICULATES - PROBE AND FILTER
Mg
Mg/DSCM
Mg/ACM
Kg/Hr
Kg/M-Ton Feed
46.7
38.01
19.96
15.4
0.84
39.5
14.00
6.84
5.52
0.30
30.6
8.23
4.42
3.12
0.17
21.9
5.87
2.96
2.09
0.11
51.2
13.52
7.11
5.17
0.28
49.5
12.84
6.41
4.84
0.26
42.8
19.92
10.50
7.90
0.43
37.0
10.90
5.40
4.15
0.23
PARTICULATES - TOTAL
Mg
Mg/DSCM
Mg/ACM
Kg/Hr
Kg/M-Ton Feed
Percent Impinger Catch
84.2
68.53
35.99
27.76
1.51
44.5
63.9
22.65
11.07
8.93
0.48
38.2
49.4
13.28
7.13
5.02
0.28
38.1
126.4
33.90
17.08
11.99
0.66
82.7
71.2
18.80
9.90
7.17
0.39
28.1
106.7
27.67
13.81
10.43
0.57
58.2
68.3
33.54
17.67
13.32
0.73
36.9
99.0
28.07
13.99
10.45
0.57
58.2
(1) Dry standard cubic meter at 21°C and 29.92 Inches Hg
(2) Metric tons per hour (2200 Ibs - 1 M-Ton)
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Table 2.3 Gas Data Summary
CT>
Run
1
2
3
Location
North
South
North
South
North
South
Flow
SCMMD
1392
1355
1300
1216
1312
1294
Orsat CO Visible
Data PPMD Opacity
% C02 % 02 PPMD NOX PPM S02 1234
8.7 12.2 63 0 00
10.0 11.1 20 129 00
9.7 11.3 27 00 <5^'
10.4 9.7 34 96 00
8.1 10.8 250 0- O^2^ <5^
10.0 9.8 260 96 0(2* <5(
Several readings of 5 and 10
Several readings of 5
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After the first run, the Orsat was found to be in error when checked
against ambient air. Since it rained all day Wednesday, time was spent
calibrating a portable gas chromatograph to measure CO and 0 . When
the integrated gas samples from the first day's testing were analyzed
Wednesday afternoon, it appeared that the results were in error, i.e., the
percent CO seemed low and the percent 0_ high. However, when comparable
results were obtained from test 2 on Thursday, it seemed to indicate
that there was possibly a leak, either in the integrated sampler or in
the duct work.
To find out where the leak was, a direct sample was taken from the stacks
on Thursday evening; the results were the same as those obtained from
the bag sample. On close examination it was discovered that ambient
air was drawn into the system prior to the ESP's. The major places where
this occurred were at the kiln bearing seals and the openings (approxi-
mately 20 x 40 inches) where the feed rock is dropped from conveyor belts
into the kiln. These locations are on the negative side of the fan and,
o
hence,draw ambient air into the system.
The concentration of CO as measured by NDIR from injections taken from
the integrated bag samples varied more than one would expect since the
gases in the ductwork should have been thoroughly mixed. The average
concentration for"all six runs was 109 ppmd.2 However, analysis of the
gases from the last day's runs indicated 250 and 260 ppmd as compared
to 63 and 20, 27 and 34 ppmd from the first two days.
' Non-dispersive infrared
Parts per million dry gas volume
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Concentrations of NO were 129, 96, and 96 ppmd for the three runs.
/\
Each run consisted of four grab samples, the results of which are
included in Appendix A.
At no time was any SC^ present in detectable amounts. This was expected
since the kilns were fired with natural gas and the processed dolomite
probably contained little, if any, sulfur inclusions.
Visible opacity was in general 0% with a few exceptions. One observer
(No. 4) indicated quite a few as less than 5% on the second and third
tests.
2.2 COMPARATIVE TESTING
Difficulties were experienced in getting a good comparative sample.
No valid comparative data were obtained due to equipment malfunctions.
EPA supplied some of the equipment to avoid potential problems in inter-
facing the special probe assembly with other parts of the sampling train.
The difficulties were caused primarily by a leak in the EPA's meter
box. Once this was fixed it was found that the meter was still mal-
functioning. Finally, the meter stopped working during the second
comparative test. Since the meter was not operating properly, it would
be meaningless to calculate a grain loading based on the indicated
gas volume. "However, a copy of the comparative data can "be found in
the appendices.
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3.0 PROCESS DESCRIPTION AND OPERATION
Limestone consists primarily of calcium carbonate or combinations of
calcium and magnesium carbonate with varying amounts of impurities.
Lime is a calcined or burned form of limestone, commonly divided into
two basic products—quicklime and hydrated lime. Calcination expels carbon
dioxide from the raw limestone, leaving calcium oxide (quicklime). With
the addition of water (slaking), calcium hydroxide (hydrated lime) is forme'd.
In standard chemical notation, the reations are:
Calcination CaC03 Heat - CaO-+ C021
Hydration CaO + H20 =>• Ca(OH)2
The basic processes in production are: 1) quarrying the limestone raw
material, 2) preparing the limestone for kilns by crushing and sizing,
3) calcining the limestone, and 4) optionally processing the quicklime
further by additional crushing and sizing and then hydration. The
majority of lime is produced in rotary kilns which can be fired by
coal, oil, or gas. Rotary kilns have the advantages of high production
per man-hour and a uniform product, but require higher capital invest-
ment and have higher unit fuel costs than most vertical kilns.
The Dow Chemical plant has three rotary lime kilns operating on Texas
dolomitic limestone. The product quicklime is slaked to the hydrate
(milk of lime) and used to precipitate magnesium hydroxide from seawater.
Most of the purified magnesium hydroxide is reacted with hydrogen chlor-
ide to make magnesium chloride which is converted to magnesium metal
in electrolytic cells.
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There are three straight bore kilns, each 9 feet 6 inches by 265 feet,
with a design capacity of 250 tons per day each. They "very seldom"
run all three kilns, usually two are on line. The dolomite feed stone
is brought into the plant sized one half to three quarters inch or
three quartersto one and one half inches top size. There is no stone
preheater. The kilns are fired with natural gas and the product quicklime
is cooled to 200-300°F with satellite coolers. There is no quicklime
storage, as all the product is fed into three rotating drum slakers where
the milk of lime is produced.
The three kilns are provided with an electrostatic precipitator manu-
factured by the Western Precipitation Division of the Joy Manufacturing
Company. The exit gas from the three kilns is cooled to 500°F by water
sprays and enters a common plenum. From this plenum the gas is dis-
tributed to the two chambers of the precipitator by manually operated
guillotine dampers. Each chamber has three fields, thirty-five gas
passages, and a plate area of 35,280 square feet. From data which Dow
supplied, it can be calculated (if only two kilns are in operation) that
the design velocity is 2.0 feet per second and the design residence time
is 10.5 seconds. Following the precipitatbrs, the stack gases are
vented to the atmosphere through 80 foot high stacks, one servicing
each precipator. The complete layout -is illustrated in Figures
3.1 and 3.2.
The dust collected from the precipitators is presently wasted. In
the future this dust may be granulated and returned to the kiln.
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North
Chambers
Sample Pt. "A"
ELEVATION
Figure 3.1. Precipitator Plan and Elevation.
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8'
-*!
80'
10'
E
26'
Ground //////
Sample
Ports
90° apart
•o
ELECTROSTATIC PRECIPITATOR
Figure 3.2 Stack Elevations
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Each chamber of the precipitator has nineteen rappers, and there is
one for each distribution plate. The rappers operate in sequence, one
complete cycle requiring about twenty minutes.
The operation of the kilns and the electrostatic precipitator was moni-
tored during the tests; process data are summarized in Table 3.1.
It appears that the kilns operated normally throughout the test. On
May 1 there was heavy rain all day and no sampling was possible. During
the 3 to 11 shift on that day, the A field in the south precipitator
chamber'began arcing badly and was therefore removed from service and
grounded. Plant personnel thought that rain may have leaked into the
insulator on the top of the precipitators. On the morning of May 2,
the south A field was put back on line and, although there was still
some arcing, it was not serious enough to significantly affect the
efficiency of the precipitator.
On May 3, the south A field was arcing and the voltage on the field was
down from 275 V (on May 2) to 250-255 V. The south A field was there-
fore removed from service and grounded before testing began. The south
chamber, during the last day of testing, was therefore operating with
57% of its normal plate area. Even with this reduced collecting surface,
there were no significant visible emissions.
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Table 3.1 Summary of Operating Variables.
Test No. and (Date)
Kiln No.
1 (4/30)
2 3
2 (5/2)
2 3
3 (5/3)
Stone Feed Rate (tons/hr)
Ray 0 Tube Temp. (°F)
Slip Ring Temp. (°F)
Feed End Temp. (°F)
Fan Temp. ("F)
Electrostatic Precipitator
A Field
Primary Current (amps)
Primary Voltage (volts)
B Field
Primary Current (amps)
Primary. Voltage (volts)
C Field
Primary Current (amps)
Primary Voltage (volts)
19.4 21.2
2174-2192 2192-2246
1472-1490 1418-1436
1156-1166 1256
500 536
Data
'136-140
260-275
185
230
152-155
205-210
19.0 21.0
2156-2210 2156-2174
1436-1460 1400-1436
1184-1202 1220-1229
500-518 527-536
135-137
250-283
183-184
232-235
151-153
200-204
18.9 21.7
2174-2210 2156-2210
1454-1490 1382-1400
1184-1202 1238-1256
518-536 536
135-137*
290-300*
182-185
235-240
151-153
202-205
*The south A field was grounded and not operating during the test.
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4.0 LOCATION OF SAMPLING POINTS
As the sampling ports were located only 26 feet downstream from the pre-
cipitator exit and 10 feet from the top of the stack, it was necessary
to sample 22 points on each of two diameters through two ports 90° apart
in each stack (total of 44 points in each). These points were selected
according to method 1 of the Federal Register which locates each point
at the center of equal area zones. The exact location of these points
is included in Appendix B. As mentioned previously, for the first run
on the north stack, each point was inadvertently shifted 4 inches too
far into the stack. Due to the length of probe in the stack, the strain
on the union of probe and heated box prevented several points near the
far wall of both stacks from being sampled.
5.0 SAMPLING AND ANALYTICAL PROCEDURES
5.1 PARTICULATE SAMPLING
Particulate samples were obtained using the standard EPA method 5 train
without a cyclone, following the procedures specified in the December
21, 1971 Federal Register. In addition, .the impinger contents were
obtained and analyzed according to the appropriate procedures specified
in the proposed Method 5 in the August 17, 1971 Federal Register; except
that,the organic extraction was not performed.
Prior to the first run, a preliminary moisture run was made in order
to obtain a moisture fraction for setting the nomograph. Subsequently,
for purposes of setting the nomograph, the moisture fraction was assumed
to be 18-19 percent as found from the first particulate runs.
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Gas temperatures were measured before and during each test with bimetallic
dial thermometers accurate to ± 5°F. These measurements were made at
a single point in the stack instead of at each sampling point. There
appeared to be very little temperature gradient across the stack,making
a one point temperature sample sufficient.
In addition, before each run except the third run, a preliminary
velocity traverse was made on one diameter of each stack for the pur-
pose of balancing the flow rates. If necessary, damper, adjustments
were made under the direction of the EPA project engineer.
At the end of each run, the particulate sampling trains were moved to
a nearby room for clean-up. The samples obtained were transferred to
D
acid-washed glass storage containers with Teflon seals for subsequent
laboratory analysis. A description of the analysis procedures is
included in Appendix C.
5.2 S02 SAMPLING METHODS
Since it was requested by the EPA project officer that SO sampling
extend the full period during which particulate samples were obtained,
it was necessary to add a dry impinger between the isopropanol bubbler
and first peroxide impinger to trap any diluted isopropanol carryover
to prevent sample contamination. This was the only deviation from
method 6, as specified in the December 21, 1971 Federal Register.
5.3 N0v SAMPLING METHODS
A
Four NOX grab samples were taken,foil owing Method 7 as specified in the
December 21, 1971 Federal Register during each particulate run on the
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south stack; the arithmetic mean of these four samples is reported as the
result for that run. These samples were approximately equally spaced in time
during the run in order to obtain a representative average.
5.4 INTEGRATED BAG SAMPLES
An integrated bag sample was obtained from each stack during the period
of the particul ate runs,foil owing Method 3 as specified in the December
21, 1971 Federal Register.
At the end of each run the bag's contents were analyzed by NDIR for CO,
and for COg and 0~ by gas chromatography utilizing a thermal detector.
A copy of the analytical procedures is included in Appendix C along
with the calibration procedure for the GC and sample calculations show-
ing corrections for CO? in the CO concentrations, according to Method
10 as specified in the March 8, 1974 Federal Register.
5.5 VISUAL SMOKE OBSERVATIONS
During the first particulate tests, two visual observers were assigned
to read each stack. Due to manpower requirements, this number was re-
duced to three observers on the second particulate test and two observers
on the third. Since the opacity did not differ much from 0 at any time,
it was possible to have the observers double up and read both stacks
simultaneously for the last two tests. The observers followed the
guidelines set forth in Method 9}as specified in the December 21, 1971
Federal Register.
5.6 COMPARATIVE TESTING
Two probes were attached to a common pi tot tube which allowed isokinetic
sampling at approximately the same point in the stack. The in-stack
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filter train differed from the method 5 train in that an additional
in-stack filter holder was placed directly behind the nozzle. The re-
mainder of the sampling equipment remained unchanged. Equipment diffi-
culties prevented obtaining valid results.
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