?,EPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC
EMB Report 8C-BYC-2
March 1981
Air
Benzene
Coke Oven By-Product
Plants
Emission Test Report
United States Steel
Corporation
Clairton, Pennsylvania
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SET 1957 06 0181
BENZENE SAMPLING PROGRAM
AT COKE BY-PRODUCT RECOVERY PLANTS:
UNITED STATES STEEL CORPORATION,
CLAIRTON, PENNSYLVANIA
EPA Contract 68-02-2813
Work Assignment 48
ESED Project No. 74/4j
Prepared For:
Mr. Daniel Bivins
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Emission Measurement Branch, ESED, MD-13
Research Triangle Park, North Carolina 27711
March 1981
SCOTT ENVIRONMENTAL SERVICES
A Division Of
SCOTT ENVIRONMENTAL TECHNOLOGY, INC.
Plumsteadville, Pennsylvania 18949
Scott Environmental Technology Inc.
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TABLE OF CONTENTS
. Page
1.0 INTRODUCTION 1-1
2.0 SUMMARY OF RESULTS 2-1
3.0 RESULTS AND DISCUSSION 3-1
3.1 PITCH PRILLING 3-1
3.2 PITCH STORAGE TANK 3-3
3.3 LIGHT OIL CONTAMINATED SUMP 3-6
4.0 PROCESS DESCRIPTIONS 4-1
5.0 FIELD SAMPLING AND ANALYSIS METHODOLOGY 5-1
5.1 DETERMINATION OF BENZO-'a-P^RENE FROM STATIONARY SOURCES . 5-1
5.2 SAMPLING FUGITIVE BENZENE SOURCES: TRACER GAS METHOD . . 5-1
5.3 SAMPLE HANDLING 5-3
5.4 FIELD ANALYSIS ..... 5-4
6.0 FIELD SAMPLING PROCEDURES 6-1
6.1 PITCH STORAGE TANK - BEFORE SCRUBBER . 6-1
6.2 PITCH STORAGE TANK - SCRUBBER OUTLET 6-1
6.3 PITCH PRILLING ...... 6-3
6.4 LIGHT OIL CONTAMINATED SUMP 6-6
7.0 LABORATORY SAMPLE ANALYSIS 7-1
7.1 LIQUID SAMPLE PREPARATION 7-1
7.2 PURGE AND TRAP PROCEDURE FOR EXTRACTION OF BENZENE FROM
LIQUID PHASE TO GASEOUS PHASE ... 7-2
7.3 SAMPLE ANALYSIS , 7-4
7.4 ANALYSIS OF BENZO-a-PYRENE SAMPLES 7-5
8.0 QUALITY CONTROL AND QUALITY ASSURANCE 8-1
8.1 FIELD ANALYSIS PROCEDURES 8-1
8.2 PROCEDURES FOR ANALYSIS OF PROCESS LIQUIDS . 8-2
8.3 PROCEDURES FOR BaP ANALYSIS . . . 8-3
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SET 1957 06 0181 ^ page i_i -
1.0 INTRODUCTION
Scott Environmental Services, a division of Scott Environmental
Technology, Inc., conducted a testing program at United States Steel
Corporation, Clairton, Pennsylvania to determine benzene and benzo-a-pyrene
.emissions from three sources in the coke by-product recovery plant. The
work was performed for the United States Environmental Protection Agency,
Emissions Measurement Branch, under Contract Number 68-02-2813, Work
Assignment 48. Clairton was one of seven plants visited to collect data
for a possible National Emission Standard for Hazardous Air Pollutants for
benzene.
Sampling was conducted at the Clairton Works from July 28 to
August 8, 1980. Sampling for benzo-a-pyrene was conducted at the pitch
prilling tank and at the pitch storage tank before and after the venturi
scrubber. Integrated air samples for benzene were collected at the light
oil contaminated sump.
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SET 1957 06 0181
Page 2-1
2.0 SUMMARY OF RESULTS
BaP Emission Rate
Process
Pitch prilling tank
Pitch Storage - scrubber inlet
Pitch storage - scrubber outlet
Ib/hr
4.13 x 10
-4
6.24 x 10
-4
<4.6 x 10
-6
kg/hr
1.87 x 10
,-4
2.83 x 10
-4
<2.1 x 10
-6
Light oil contaminated sump
Benzene Emission Rate
3.80
1.72
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SET 1957 06 0181 Page 3~1
3.0 RESULTS AND DISCUSSION
3.1 PITCH PRILLING
Pitch is the heavy fraction of tar, and is obtained by scraping
the bottom of the tar decanter for the heavy deposits. The pitch is
processed for ease in handling by a priller, in which hot pitch is passed
through a perforated plate and immediately quenched with water to form
small pellets of hard pitch. Tests for benzo-a-pyrene (BaP) were conducted
at the vent of the tank in which the pitch is melted prior to prilling.
The results of the benzo-a-pyrene tests performed at the pitch
prilling tank are presented in Table 3-1. The results of Run 1 are believed
to be the best estimate of the emissions. Run 2 was voided due to failure
to pass a post-test leak check, but the results of Run 2 are within 30%
of Run 1 and are probably fairly accurate. The results of Run 3 were
very low (less than the lowest detectable limit of the analytical instruments),
probably due to a process change. Table 3-1 shows that the flow rate was
considerably lower during Test 3, although stack temperature was consistent
with Runs 1 and 2.
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SET 1957 06 0,181
Page 3-2
TABLE 3-1
PITCH PRILLING DATA 'SUMMARY
Run No.
Date
Test Period
Volume of Gas Sampled (DSCF)
Test Time (minutes)
Stack Area (sq. ft.)
Stack Gas Velocity (fpm)
Stack Gas Temperature (°F)
Stack Gas Moisture (%)
Stack Gas Mol. Wt. (Ib/mole)
Stack Gas Flow Rate (DSCFM)
Nozzle Diameter (inches)
Isokinetic Variation (%)
Particulates - Total
mg
gr/DSCF
Ib/hr
1
8/5/80
0956-1056
24.712
60
0.137
1608.6
187.7
5.15
28.28
167.26
0.247
101.38
2
8/5/80
1350-1450
26.604
60
0.137
1555.3
198.5
5.19
28.28
158.91
0.247
114.80
3
8/6/80
1005-1105
24.896
60
0.137
1091.0
190.2
5.73
28.22
112.909
0.302
101.21
0.4625 0.3548 <0..024
2.88 x 10~4 2.05 x 10"4 <1.48xlO~5
4.13 x 10~4 2.84 x 10~4 <1.44 x 10~5
Standard Conditions: 70°F, 29.92 inches Hg
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SET 1957 06 0181 Page 3-3
3.2 PITCH STORAGE TANK
Prior to the prilling operation, the pitch is kept in heated
storage tanks, which are equipped with methyl naphthalene venturi scrubbers
on the vents to control emissions. Sampling for BaP was conducted at ports
before ;and after the scrubber to determine controlled and uncontrolled
emissions from this source.
Before the scrubber, emissions of BaP were measured to be
6.24 x 10 Ib/hr and after the scrubber, emissions were less than
4.6 x 10~6 Ib/hr (less than the lowest detectable limit on the GC). Results
of the tests are given in Tables 3-2 and 3-3. The sample for Run 1 before
the scrubber was damaged in transporting it from the plant to Scott's
laboratory.
The liquid samples taken from a valve at the base of the storage
tank contained 0.88 percent benzene by weight.
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SET 1957 06 0181
Page 3-4
TABLE 3-2
PITCH STORAGE SCRUBBER INLET - U.S. STEEL, CLAIRTON, PA
Run No.
Date
Test Period
Volume of Gas Sampled (DSCF)
Test Time (minutes)
Stack Area (sq. ft.)
Stack Gas Velocity (fpm)
Stack Gas Temperature (°F)
Stack Gas Moisture (%)
Stack Gas Mol. Wt. (Ib/mole)
Stack Gas Flow Rate (DSCFM)
Nozzle Diameter (inches)
Isokinetic Variation (%)
Particulates - Front Half
mg
gr/DSCF
Ib/hr
1
8/1/80
1040-1112
16.641
32
0.196
262.33
278.3
7.97
27.97
33.065
0.777
93.41
N.A.
2
8/1/80
1510-1610
30.676
60
0.196
261.27
283.2
4.30
28.37
34.042
0.777
89.20
4.259
2.14 x 10
-3
6.238 x 10
-4
Standard Conditions: 70°F, 29.92 inches Hg
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SET 1957 06 0181
Page 3-5
TABLE 3-3
PITCH STORAGE SCRUBBER OUTLET - U.S. STEEL CLAIRTON, PA
Run No.
Date
Test Period
Volume of Gas Sampled (DSCF)
Test Time (minutes)
Stack Area (sq. ft.)
Stack Gas Velocity (fpm)
Stack Gas Temperature (°F)
Stack Gas Moisture (%)
Stack Gas Mol. Wt. (Ib/mole)
Stack Gas Flow Rate (DSCFM)
Nozzle Diameter (inches)
Isokinetic Variation (%)
Particulates - Front Half
mg
gr/DSCF
Ib/hr
1
8/6/80
1543-1643
25.644
60
0.349
166.00
143.8
4.95
28.30
47.47
0.777
95.41
2
8/7/80
1044-1144
24.743
60
0.349
166.85
151.6
4.04
28.40
47.56
0.777
91.70
< 0.02 < 0.02
< 1.20 x 10~5 < 1.24 x 10~5
< 4.89 x 10~6 * 4.31 x 10~6
Standard Conditions: 70°F, 29.92 inches Hg
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SET 1957 06 Q18L Page 3~6
3.3 LIGHT OIL CONTAMINATED SUMP
The "slop sump" receives waste water from the naphthalene
desulfurization unit, the tar distillation plant, and underdrains from
tar operations. "Light oil contaminated sump" is prohahly a misnomer, as
the sump is in the tar plant. The sump is about 8 feet below grade and
open to the atmosphere, with a diameter of 18 feet. This is a potential
fugitive benzene emission source, and was sampled using the tracer gas
method. (See section 5.2).
The average emission rate measured was 3.80 Ib/hr benzene.
Liquid samples were collected on the east side of the inlet, directly in
front of the inlet, and on the west side of the inlet. Benzene concen-
trations were 16.4 ppm, 1274.4 ppm and 575.1 ppm respectively, as shown
in Table 3-4.
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SET 1957 06 0181
Page 3-7
TABLE 3-4
TRACER DATA
LIGHT OIL CONTAMINATED SUMP
U.S. STEEL CLAIRTON, PA
Date: 8/1/80
Start Time: 1140
Test #1, Run #1
Isobutane release rate:
Cone . of
Sample Benzene
Loc. (ppm)
West 1 2.75
West 2 2.22
East 1 9.18
East 2 3.26
Upwind N.D.
Test #1, Run #2
Isobutane release rate:
West 1 3.98
West 2 2.32
East 1 7.24
East 2 2.04
Upwind N.D.
Average Emission Rate:
1.31 Ib/hr
Cone . of
Isobutane Mass to Mass Ib/hr
(ppm) Ratio /ic. Benzene
0.92 4.00 5.24
0.84 3.56 4.66
4.40 2.81 3.68
1.89 2.32 3.04
N.D.
Avg . 4.16
1.30 Ib/hr
1.06 5.06 6.59
1.03 3.03 3.94
4.80 2.03 2.64
1.58 1.74 2.26
N.D.
Avg. 3.86
4.01 Ib/hr, 1.82 kg/hr
•
kg/hr
Benzene
2.38
2.12
1.67
1.38
1.89
.3.00
1.79
1.20
1.03
1.75
(T) Scott Environmental Technology Inc
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SET 1957 06 0181
Table 3-4
(Continued)
TRACER DATA
LIGHT OIL CONTAMINATED SUMP
U.S. STEEL CLAIRTON, PA
Page 3-8
Date: 8/4/80
Start Time: 1000
Test #2, Run #1
Isobutane release rate:
0.951 Ib/hr
CD
Cone, of Cone, of
Sample Benzene Isobutane Mass to Mass Ib/hr
Loc. (ppm) (ppm) Ratio <(>/ic, Benzene
West 1 6.62 1.93 4.60 4.37
West 2 5.57 1.91 3.92 3.73
East 1 3.75 1.38 3.66 3.48
East 2 0.95 0.38 3.38 3.21
Upwind 0.10 N.D.
Avg. 3.70
Test #2, Run #2
Isobutane release rate: 0.940 Ib/hr
West 1 4.94 1.38 4.81 4.52
West 2 2.31 1.22 2.56 2.41
East 1 4.19 1.96 2.88 2.71
East 2 1.43 0.58 3.35 3.15
Upwind 0.10 N.D.
Avg. 3.20
Average Emission Rate: 3.45 Ib/hr, 1.57 kg/hr
Scott Environmental Technolosy Inc
kg/hr
. Benzene
1.99
1.70
1.58
1.46
1.68
2.05
1.10
1.23
1.43
1.45
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SET 1957 06 0181
Table 3-4
(Continued)
TRACER DATA
LIGHT OIL CONTAMINATED SUMP
U.S. STEEL CLAIRTON, PA
Page 3-9
Date: 8/5/80
Start Time: 0925
Test #3, Run //I
Isobutane release rate:
0.935 Ib/hr
Sample
Loc.
West 1
West 2
East 1
East 2
Upwind
Cone . of
Benzene
(ppm)
5.36
5.78
3.78
1.68
0.16
Cone, of
Isobutane
(ppm)
1.80
2.44
' 0.99
0.75
N.D.
Mass to Mass
Ratio /ic,
3.99
3.19
5.14
3.01
Ib/hr
Benzene
3.73
2.98
4.81
2.81
kg/hr
Benzene
1.70
1.35
2.19
l.]8
Avg. 3.59
1.63
Test #3, Run #2
Isobutane release rate: 1.04 Ib/hr
West 1*
West 2*
East 1
East 2
Upwind
32.55
16.70
3.52
2.09
0.16
2.32
2.39
1.17
0.67
ND
18.44
9.39
4.03
4.20
4.19 1.90
4.37 1.99
Avg.
4.28
1.95
Average Emission Rate: 3.94 Ib/hr, 1.79 kg/hr
*Data rejected, interference from an outside source due to wind shift,
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SET 1957 06 0181 Page 4-1
4.0 PROCESS DESCRIPTION
The Clairton Works operated by U.S. Steel corporation is the largest
coking facility in the United States of America producing approximately
15,695 metric tons (17,300 tons) of coke per day from 1,227 coke ovens.
Clairton's nonconventional operations are the production of synthetic anhy-
drous ammonia, cryogenic light oil recovery, and recovery of elemental sul-
fur. The conventional operations are tar recovery, tar refining and light
oil refining. The conventional operations were the emphasis of the tests.
The operations used at the Clairton Works for recovery of the coke
oven gas and by-products are flushing liquor spraying, flushing liquor de-
canting, primary cooling, primary cooler tar decanting, tar refining, final
cooling, Phosam ammonia refining, cryogenic regeneration, synthetic anhy-
drous ammonia synthesis, light oil regeneration, light oil decanting, light
oil refining, HCN recovery, Glaus sulfur recovery, and wastewater pretreat-
ment and treatment.
The raw coke oven gas leaving the batteries is sprayed with flushing
liquor for initial cooling to approximately 77°C. The gas and flushing
liquor separate in a pitch trap where the heavy tar, pitch and flushing
liquor are dischargedrto the flushing liquor!decanters and the gas continues
to the primary coolers.
The flushing liquor decanters separate the dirty liquor into
heavy tar and flushing liquor. The flushing liquor decanters receive
additional inputs from the pretreatment settling tanks and a separator after
the light oil decanter. The clean flushing liquor is returned to the batteries
for reuse. The heavy tar layer is pumped to heavy tar storage tanks before
refining. The tar refining operations will be discussed in detail after
the general process description.
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SET 1957 06 0181 -.-- Page 4-2
The excess flushing liquor is pumped to the pretreatment settling
tanks. The settling tanks receive additional inputs from the primary cooler
decanters, decanters in the light oil refining, contaminated water sump
decanter, final cooler sump bleedstream, and miscellaneous wastewater
streams. A mixed polymer is added to the combined wastewater stream before
entering the settling tanks to aid flocculation. In the settling tank the
combined wastewater separates into light oil,; water, and heavies. The
light oil is drained to a surge tank and then pumped to light oil storage.
The water layer flows to a holding tank equipped with a floating roof be-
fore discharge to wastewater treatment. The heavies are returned to the .
flushing liquor decanter because this layer contains tar, nephthalene and
solid inpurities. The settling tank and the surge tank are vented together
in a vapor balance system.
The coke oven gas, after the pitch trap, enters the primary
coolers. There are three combination primary coolers (indirect/direct) and
thirty-two indirect primary coolers. Additional tar is removed from the gas
in the primary coolers and is drained to the primary cooler tar decanters.
The tar from the primary coolers is light tar (P.C. Tar) and is decanted and
stored separately before refining. Some P.C. Tar is pumped to the final
coolers to increase removal of naphthalene and other impurities that
could cause plugging of the final cooler and other refining operations.
The gas stream leaving the primary coolers is supplied with the
prime motive power by the compressors. The gas leaves the compressors at
approximately 88°C and enters the final coolers. The final coolers are
equipped with three different sets of sprays. The top spray uses re-
circulating water and a demister with a light oil flush to dissolve any tar
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SET 1957 06 0181 Page 4-3
or naphthalene carry over. The middle spray is a water spray for cooling
and the bottom spray circulates the P.C. Tar. The P.C. Tar and water
from the middle sprays are drained to the final cooler sump where they are
separated. The light oil is pumped to a light oil storage tank that is vented
to the final cooler at 45 psig. The light oil from the storage tank is
either pumped to light oil refining or returned to the spray system on
the final cooler. The water layer is cooled in an indirect heat exchanger
to approximately 30°C and returned to the final cooler for reuse. A bleed-
stream of the water layer is pumped to the settling tank of the pretreatment
system. The PC Tar is pumped to storage tanks for additional separation.
The final cooler sump is vented to the atmosphere, but the sump is covered
and sealed with a liquid channel.
The gas leaves the final coolers at approximately 38°C and is con-
tacted with a mono-ammonium phosphate solution in the Phosam absorber. The
Phosam solution absorbs ammonia from the gas stream and is then stripped of
the ammonia in the Phosam refining which produces anhydrous ammonia. The
Phosam solution can absorb tar/naphthalene which is removed from the solution
by dissolved air flotation in a depurator. The flotation cell is covered and
is vented to the atmosphere. The tar/naphthalene layer is pumped to the
light tar storage tank.
The gas from the Phosam absorber enters the main cryogenic re-
generators at approximately 38°C and with a concentration of benzene of
approximately 1%. The four-phase system has 24 regenerators that are at
different stages continuously throughout the cycle. The four stages are
loading, sublimation, underfiring and downriver which are automatically
controlled. During -the loading phase condensation of water, light oil,
hydrogen sulfide and carbon dioxide occurs when the gas is cooled by contact
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SET 1957 06 0181 Page 4-4
with the stone packing in the regenerators. In the sublimation phase a
vacuum is drawn on the stone packing which causes evaporation of the con-
densate. The concentrated gas is then further cooled and fed to the light
oil regenerators and sulfur recovery. In the underfiring phase the gas is
expanded through a turbine and the gas is then1 used to partially cool the
regenerator stones before it is burned at the coke oven batteries. During
the downriver phase the regenerators are fed cold purified gas for final
cooling. The gas then enters the hydrogen .plant and the regenerator re-
turns to the loading phase.
The light oil recovery system uses four regenerators and two
multi-stage cooling and separation systems. The concentrated gas from the
sublimation phase of the main cryogenic regenerators enters a compressor at
3 psia where water is injected and the gas exists at approximately 25 psig.
The gas then enters a separator at approximately 94°C where some injection
water is removed from the gas stream. Next, the gas is indirectly cooled
with water to approximately 37°C and enters another separator. The gas is
then further cooled indirectly with ammonia to approximately 10°C before
entering another separator. After the third separator the gas stream is
cooled to approximately -68°C in the light oil regenerators. The subgas
from the regenerator in loading phase is used to cool another regenerator
before entering the sulfur recovery process. A vacuum is then drawn on the
loading phase condensate which evaporates during the sublimation phase. The
concentrated gas is then passed through a similar cooling and separating
system as described for the gas from the sublimation phase^ of the main cryo-
genic regenerators. The gas after the second cooling/separating system is
taken to HCN recovery. All condensates from the separators of both systems
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SET 1957 06 0181 Page 4-5
are combined and pumped to the light oil decanter.
The light oil decanter is a center, underfed decanter with automatic
level control. The decanter separates the feed into water and light oil.
The light oil is pumped to light oil storage and the water layer is pumped
to the contaminated water system where it is treated with a, polymer to re-
move residual light oil and tar. The light oil is pumped to light oil stor-
age. The light oil decanter is vented to the inlet of the light oil com-
pressor for the cooling/separating system at a slight negative pressure.
Crude tar at approximately 11 1/s (250,000 gpd) is fed from tar
distillation storage to the dehydrator. The tar is storage is heated to
approximately 82°C for viscosity control and the tar storage tank vapors are
scrubbed by a Venturi scrubber. The tar before entering the dehydrator is
indirectly heated with steam and heated topped tar is added to further raise
the temperature to approximately 120°C. In the dehydrator, water and some
light oil are removed from the crude tar at 120°C arid flow to a decanter
that is vented to the atmosphere. Before the decanter there is an inter-
mediate decanter that supplies surge capacity to the system. In the de-
canter the light oil and water are separated from each other. The light
oil is pumped to storage and the water is pumped to the wastewater pre-
treatment settling tanks.
The dry tar in the bottom of the dehydrator is pumped to a gas
fired heater where the temperature of the tar is raised to approximately
205°C. The tar from the heater is either added to the dehydrator feed or
to the primary flash vessel. The primary flash vessel is operated at 150
mmHg absolute which facilitates removal of theMight ends from the tar.
The light ends are cooled in an indirect heat exchanger and become the #1
and #2-carbolic oil feeds to the distillation columns. The bottom tar from
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SET 1957 06 0181 Pa§e 4~6
the primary flash vessel is pumped to another gas fired heater where the
temperature is raised to approximately 315°C before the tar is added to the
secondary flash vessel. The secondary flash vessel is operated at 100 mmHg
absolute which separates the creosotes from the tar pitch. The cresotes
are indirectly cooled by a spiral condenser and become the #3 feedstream to
the distillation columns. The pitch storage tank is equipped with a venturi
scrubber that used methyl naphthalene as the scrubbing medium to control
emissions. From pitch storage the pitch is prilled by passing the pitch
through a 1/8" manifold plate and immediately quenching with water. After
cooling, the prilled pitch is dryed in a rotary dryer fchat is vented to the
battery stack where the temperature is 318°C. The prilling operation at
present is open to the surrounding area. The #2 priller is equipped with a
scrubber.
The #1, #2, and #3 streams are combined and fed to the continous
distillation columns. All columns are continous feed and take-off with vary-
ing temperature, pressure and flow. The first column is operated at 210°C
and is equipped with a double stage steam ejector on the top of the column.
The light ends are condensed to comprise the //I carbolic oil which is
washed with caustic to remove carbolic acids. The carbolic acids are further
processed. The #1 carbolic oil is pumped to storage before further refining.
The bo.ttoms from the first column are returned to the distillation column
or pumped to the second distillation column. The second distillation column
is operated at 235°C and 150 mmHg absolute and is equipped with a single
stage steam ejector. The light ends are condensed to comprise the #2 car-
bolic oil and are washed with caustic in a conventional phenolic system. The
carbolic acids are further processed and the #2 carbolic oil is pumped to
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SET 1957 06 0181 Page 4-7
storage that is vented to the atmosphere before refining. The bottoms from
the second column are either heated in a gas fired heater and returned to
the column or pumped to the third distillation column. The third distillation
column is operated at 270°C and 150 mmHg absolute and is equipped_with
a single stage steam ejector. The light ends are condensed to become the
light creosote stream and pumped to product storage which has a venturi
scrubber using methyl naphthalene to control emissions. The bottoms from
the third distillation column are either heated in a gas fired heater and
returned to the column or pumped to the fourth distillation column. The
fourth distillation column is operated at 315°C and 200 mmHg absolute and is
equipped with a single stage steam ejector. The light ends are condensed to
become the middle creosote stream and pumped to product storage which is vented
to the gas main. The bottoms from the fourth column are either heated in a
gas fired heater and returned to the column or pumped to heavy creosote
product storage that has a venturi scrubber using methyl naphthalene to con-
trol emission.
The approximate fractional composition of the crude tar is as
follows:
-50% pitch
- 3% water
- 5% 91 carbolic oil
-12% #2 carbolic oil
-10% light creosote
-10% middle creosote
-10% heavy creosote
The creosotes are blended together after'storage in a mixing tank to achieve
buyer specifications. The mixing tank is equipped with a venturi scrubber
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SET 1957 06 0181 Page 4-8
using methyl naphthalene to control emissions. Water is drained from all
storage tanks as needed and pumped to the slop tank sump. The slop tank
sump receives all wastewater streams and water runoffs from the tar refining
area and pumps the effluent to wastewater pretreatment. The slop tank sump
is open to the atmosphere and a heavy organic vapor odor was noticeable within
the immediate vicinity.
The naphthalene refining operations are two separate operations for
//I carbolic oil and #2 carbolic oil. The #2 carbolic oil from storage is
pumped to a distillation column that has a top temperature of 250°C and no
steam ejector. The light ends are condensed and can be mixed with other
products or burned as fuel. The bottoms are rich in naphthalene and are
either heated in a gas fired heater and returned to the column or pumped to
the second distillation column. The second distillation has a bottom operating
temperature of 246°C and no steam ejector on the top. The bottoms are com^
prised of the heavy ends that are either heated and returned to the column
or pumped to final product storage where they can be mixed with other products
or burned as fuel. The light ends are rich in naphthalene and are injected
with tetroline to control the amount of hydrogenation. The naphthalene stream
is then heated to approximately 360°C at 250 psig in a gas fired heater be-
fore a catalyst reactor vessel. In the catalyst reactor vessel the organic.?
sulfur is hydrogenated to hydrogen sulfide by the catalyst. After the reactor
vessel the naphthalene stream is indirectly cooled by water before entering
the flash tank. The flash tank is operated at 94°C and 10-15 psig. Im-
purities are evaporated in the flash tank and vented to the coke oven gas
suction main and hydrogen is recycled to the flash tank. The naphthalene
is then fed to a distillation column that produces ethyl benzene, tetroline
Scott Environmental Technolosy Inc
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SET 1957 06 0181 Page 4-9
and desulfurized naptha. The ethyl benzene is pumped to storage that is
vented to the coke oven gas suction main before being used as a fuel source.
The tetroline is returned to the hydrogen injection point and the desulfurized
naptha is sold to a refiner.
The light oil from storage is pumped to the crude stills. In the
first crude still the light forerunnings are condensed and decanted. In the
decanter the oil and waiter are separated and the oil is returned to the crude
still and the water is pumped to the vaporizer. The decanter is vented to
the suction line of a compressor for the Downriver valley fuel system. The
bottoms from the first crude still are either reheated and returned to the
still or pumped to the second crude still. The light ends from the second
crude still are indirectly cooled with water and pumped to crude BTX inter-
mediate storage tank that has a floating roof to control emissions. The
bottoms from the second crude still are rich in naphthalene and heavy solids
and are pumped to the naphthalene stream in #2 carbolic oil refining before
the hydrogen injection point.
The crude BTX from storage is processed in a hydrogenation system
where it is heated and injected with hydrogen before entering a vaporizer.
After the vaporizer the crude BTX passes through a catalyst reactor vessel
and polymerizer before entering the cold catch pot. The cold catch pot is
operated at 350 psig and vented to the Valley fuel system. Hydrogen is
recovered from the cold catch pot and returned to theainjection point before
the vaporizer. The condensed BTX is then fed to a distillation column to re-
move hydrogen sulfide and hydrogen cyanide impurities that are conveyed to
the Valley fuel system. The bottoms from the distillation column are pumped
to the hydrogenated BTX storage tank that is equipped with a floating roof
Scott Environmental Technology Inc.
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SET 1957 06 0181 page 4-10
to control emissions.
The hydrogenated BTX from storage is processed in anllDEX system
that is licensed by. the Union Oil Company. The hydrogenated BTX is pumped
to an extractor where diethylene g^cycol (DEC) is contacted with the BTX to
remove paraffinic impurities. The BTX and the major portion of the DEC exit
the top of the extractor and enter the stripper. The raffinate stream and
the minor portion of the DEC from the extractor are drained to a water wash
column to remove the DEC from the raffinate. The raffinate is then cooled
and used as a fuel source. The water and DEC from the water wash column
are either pumped to wastewater pretreatment or returned to the water wash
column.
The BTX and DEC in the stripper column are separated by steam
stripping. The DEC leaves the bottom of the stripper and is either heated
and returned to the stripper or pumped to a water wash, after which it is
returned to the extractor. The BTX from the stripper is cooled indirectly
with water and passed through a clay column to remove olefinic impurities
before pumping to pure BTX storage.
The pure BTX is fed to the BTX distillation columns at 6.9 1/s
(110 gpm). The first distillation column removes residual benzene im-
purities and feeds them to the UDEX system at 0.13 1/s (2 gpm). The first
column is equipped with a vacuum pump. The condensate from the after con-
denser is separated in a decanter into light oil and water. The light oil
is pumped to a decanter that feeds the light oil storage and the water is
pumped to wastewater pretreatment. The bottoms from the first column are
either pumped to the second distillation column or heated and returned to
the first distillation column. The light ends of the second distillation
Scott Environmental Technology Inc.
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SET 1957 06 0181 Page 4-11
are cooled and become the final purified benzene which is pumped to storage
before sale. The bottoms from the second column are either pumped to the
third distillation column or heated and returned to the second column. The
third distillation fractionates the feedstream into toluene, xylene and
heavy naptha streams that are pumped to final product storage. Entrained
water is drawn off the bottom of the tanks and pumped to the contaminated
water sump. The water from the sump is pumped to a decanter to reclaim any
light oil to storage and the water is pumped to wastewater pretreatment.
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Page 5-1
SET 1957 06 0181
5.0 FIELD SAMPLING AND ANALYSIS METHODOLOGY
5.1 .DETERMINATION OF BENZO-a-PYRENE FROM STATIONARY SOURCES
An EPA draft method was used for sampling BaP. The method
basically consists of an EPA Method 5 sampling train, modified to include
an adsorbent sample tube packed with XAD resin located between the heated
filter ,and the first impinger. The purpose of the resin was to absorb
any BaP that might pass through the filter. Figure 5-1 gives a schematic
of the sampling train.
The tests were run according to the EPA method, which is included
in Appendix G, except the: high pressure drop across the packed column
necessitated running the meter box at a low AH (between 0.6 and 1.0 inches
of water). The sample time was one hour and sample volumes were approximately
25 cubic feet.
The solvent used for washing the impingers and sample train
glassware was tetrahydrofuran (THF). THF was also used in the laboratory
for the extraction of BaP from the filter and resin. All BaP samples and
THF washings were returned to Scott's Plumsteadville laboratory for analysis.
5.2 SAMPLING FUGITIVE BENZENE SOURCES: TRACER GAS METHOD
The tracer gas method is a practical procedure for quantifying
mass emissions of volatile organics from sources which are essentially
open to the atmosphere without disturbing flow, dispersion patterns or
the source operation. This method utilizes the release of a tracer gas
directly over the source of interest; the tracer gas will then follow the
same dispersion patterns as the emissions from the source. The mass of
Scott Environmental Technology Inc.
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SET 1957 06 0181 Page 5-3
tracer released over the sampling period is known and the mass to mass
ratio of the benzene to the tracer gas in the sample is determined by
gas chromatography. The emission rate of the benzene can be calculated
with this information.
This method is based on the principle that the chosen tracer gas
will model the dispersion of benzene from the source. The tracer gas
chosen for this project was isobutane because it was not present in the
sources to be tested and it could readily be separated from other source
trace components by the same column used for benzene. In addition, iso-
butane is a non-toxic gas that can readily be dispensed from a pressurized
cylinder at a uniform measured rate.
When this method was used triplicate tests were performed. Each
test consisted of two 1/2 hour runs. For each run clean and backgrounded
ten-liter-Tedla#. bags were used. Integrated samples were collected using
Emission Measurements, Inc. Air Quality Sampler II*systems. The AQS II*
samplers are self-contained units capable of collecting one or more inte-
grated samples at a preset rate. For tracer tests the sampling rate used
was ten liters per hour.
The development of the tracer gas method is discussed in Appendix D.
5.3 SAMPLE HANDLING
After being collected the tracer gas samples were immediately
transported to the gas chromatograph and analyzed. The elapsed time between
sample collection and analysis never exceeded one hour. To verify that
there was no sample degradation in samples of this type some of the samples
were retained for 24 hours and reanalyzed. The loss of benzene and
isobutane observed was typically less than 5%.
* Mention of trade names or specific products does not constitute endorsement
by the U.S. Environmental Protection Agency.
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Page 5-4
SET 1957 06 0181
5.4 FIELD ANALYSIS
All gas samples collected were analyzed using a Shimadzu GC Mini 1
gas chromatograph equipped with dual flame inoization detectors, dual
electrometers, heated sample loop and a backflush system. Figure 5-2 shows
a schematic of the backflush apparatus. The backflush system is composed
of ten port sequence reversal valve and two columns, a scrubber column for
retaining high molecular weight compounds and an analytical column. When
the system is in the inject mode the scrubber column and the analytical
column are connected in series allowing sample components to move from the
precolumn to the analytical column. In the backflush mode the columns are
disconnected from each other and become two separate systems each with its
own carrier gas source. This arrangement allows the separation and
measurement of low molecular weight compounds while the scrubber column
is being backflushed of heavier sample components. Backflush times for
different mixtures of sample components must be predetermined to insure that
the compound(s) of interest are transferred to the analytical column before
backflushing is started.
Samples for chromatographic analysis were drawn into a 20 cc glass
syringe then introduced to the sample loop inlet. The samples once in the
sample loop were allowed to come to atmospheric pressure by waiting 15
seconds prior to the injection. When only benzene was of interest the
following chromatographic conditions were maintained:
Column Temperature (isothermal) - 100°C
Injector and Detector Temperature - 200°C
5 ml Sample Loop, Temperature - 50°C
Carrier Gas Flow Rate - 32 cc/min
Hydrogen Flow Rate - 40 cc/min.
Air Flow Rate - 240 cc/min.
Analysis Time - 5 min.
Detector - Flame lonization
Scott Environmental Techndosy ^
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B, C CLOSED
BACKFLUSH
A, E CLOSED
B, C, D OPEN
GC COLUMN CONFIGURATION WITH BACKFLUSH
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Page 5-6
SET 1957 06 0181
The columns used for field analysis were:
A - Scrubber Column
10% FFAP on Supelcoport 80/100
1/8" x 1 m Stainless Steel
B - Analytical column
20% SP-2100, 0.1% Carbowax 1500
100/120 Supelcoport
1/8" x 10' Stainless Steel
When samples from tracer tests were analyzed the chromatographic
conditions were changed to provide adequate separation of the isobutane
tracer from the other light components of the sample. The temperature
program used for this analysis was:
1) Start at room temperature with external cooling fan
on and oven door open.
2) Inject @ 0.0 min.
3) Turn external cooling fan off @ 1.0 min.
4) Backflush @ 1.8 min.
5) Isobutane elutes @ 2.3 min.
6) Close oven door @ 3.0 min. with oven temperature
set at 100°C.
7) Benzene elutes @ 7.0 min.
8) After the elution of benzene, open the oven door and
turn on the cooling fan. The next injection can be
made after 2 minutes of cooling.
9) When the tracer gas is used analysis time will be
approximately 10 minutes.
The columns and flow rates were the same as for- isothermal.
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SET 1957 06 0181 Page 6-1
6.0 FIELD SAMPLING PROCEDURES
6.1 PITCH STORAGE TANK - BEFORE SCRUBBER
There are six pitch storage tanks. The one that was sampled is
known as V121, and was used as a holding tank during sampling on August 1,
1980.
The maintenance crew of U.S. Steel provided .a three-inch test
port with cap in the vertical section of pipe immediately preceeding the
scrubber (See Figure 6-1). The flow rate was very low and was measured
with a hook gauge accurate to a AP of 0.001 inches Hg. Initially there
were problems with maintaining isokinetic conditions due to the high
pressure drop across the packed absorber column. Thereafter the meter
box was run at a AH of about 1 inch of water and the pump vacuum was
about 17 inches Hg.
The first test was run for only 32 minutes, at which point
isokinetic conditions could no longer be held. The second test was run
for a full hour.
6.2 PITCH STORAGE TANK - SCRUBBER OUTLET
A stack extension with a port cut in was installed by the Scott
sampling crew on the scrubber outlet for sampling emissions from the pitch
storage tank after control. Two BaP tests were conducted at this location
on August 6th and 7th, 1980. On August 6th the tank was still being used
as a holding tank, but the operator began emptying it on the 7th because
he thought that sampling had been completed. He stopped draining the tank
at Scott's request, but the level had dropped from 18' 9" (68000 gallons)
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SET 1957 06 0181
Page 6-2
6* PIPES
TE5T
po/ A/r-
SCRUBBER
EXTOJSIDW
Z5' DIAMETER
7EST R2/RT-
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IMUET
IOQOOO GAL. S7CWGE
Inc.
FIGURE 6-1
PITCH STORAGE TANK SCRUBBER INLET AND OUTLET TEST POINTS
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SET 1957 06 0131 Page 6-3
to 12' 11 1/2" (47000 gallons). The second scrubber outlet test was
therefore run with the tank emptier than the first run and the scrubber
inlet runs.
The measured velocity head (AP) was 0.002 inches H20, and
the meter box was run at a AH of 0.7 inches H^O.
The BaP sampling method was modified at EPA's suggestion by
filling the first impinger with 100 ml tetrahydrofuran instead of
distilled water. The other three impingers contained distilled water,
nothing, and silica gel respectively, as in the test method.
The tetrahydrofuran was used to scrub out any methyl
naphthalene from the scrubber that may have passed through the sampling
train.
6.3 PITCH PRILLING
A three-inch test port was provided by U.S. Steel in the
horizontal section of pipe that vented the prilling tank (Figure 6-2). The
pipe had a diameter of 5 1/2 inches and had pitch in the bottom to a depth of
1 1/4 inches measured in the center. The stack area was corrected for
the volume occupied by the pitch (See example calculations in Appendix A).
Three BaP tests were conducted on the prilling tank on August 5th
and 6th, but the second test was rejected because the post-test leak check
failed to meet the acceptable limit. This was found to be caused by a
cracked probe liner. The data is included solely for purposes of comparison;
the test was rejected.
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SET 1957 06 0181
Page 6-4
STANDARD 6* PIPES
.\
PITCH PRILLING TANK
P/ RF LEAD59 TO
OUTSIDEVENn
I
3"TEST PORT
VALVF
70 \LID
Inc.
FIGURE 6-2
PITCH PRILLING TANK
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SET 1957 06 0181 PaSe 6~5
However, the results are believed to be accurate because the
probe liner was most likely broken when removing the probe from the stack
after the test. The pre-test leak check was good, so the liner could
only have cracked when inserting or removing the probe from the stack.
If the liner had been cracked when inserting the probe at the beginning
of the test, it is not likely that any sample would have been collected,
and the vacuum pressure would probably not have been high. For these
reasons it is believed that the liner cracked at the end of the test and
the results are good.
A preliminary velocity traverse was performed to determine
isokinetics, and a preliminary moisture determination was made using the
wet bulb-dry bulb technique. A nozzle diameter of 0.247 inches was chosen
for the first two tests and 0.302 inches for the third test due to a
decreased flow rate. On all three tests the meter box was run at a AH
of about 0.6 due to the high pressure drop across the packed absorber
column.
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SET 1957 06 «181 . Page 6-6
6.4 LIGHT OIL CONTAMINATED SUMP
Tests were performed on the light oil contaminated sump on
August 1, 4 & 5, 1980. The sump had an 18' diameter, and the liquid surface
of the sump was 8 1/2' below ground level with a liquid depth of approximately
5 feet. There was one major inlet which was located in the sump's north
wall approximately 4 feet above the surface liquid. The make up liquid •-.•••
temperature was 110°F. Due to the inlet position and feed rate approximately
one-half of the sump's surface was turbulant while the other half was
almost static. The static half of the sump was approximately 20°F cooler
than the turbulant side. Observation of the steam plume rise from the
inlet and the turbulant side of the sump revealed that the dispersion
pattern from the source was in a clockwise swirling motion. The wind speed
during testing varied from 0-10 mph and the wind direction was steady from
the south aided by a tunneling effect produced by the large storage tanks
and various buildings which lined the road on which the sump was located.
Generally the steam plume reached ground level approximately 9' from the
inlet and was then carried by the wind out of the sump in a mostly northerly
direction.
The sampling strategy was to bracket the emission source by
placing samplers as symetrically as possible about that portion of the
circumference of the sump from which the steam plume emanated (See Figure 6-3).
While the exact emission point varied with small changes in wind speed or
direction, this did not effect the total average emission during the
sampling period. Four samplers were used to bracket the sump on the east
Scott Environmental Technology Inc.
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SET 1957 06 0181 Ps8e 6~7
and west sides. These samplers were placed in pairs one foot away from the
sump and 4' from each other. This sampler position was determined by con-
sidering the following conditions:
1. Plume rise speed
2. Proximity to another sump.
3. Proximity to the inlet trough which leaked slightly
4. Physical obstacles to other symmetrical configurations
The dispersion bar was 16' in length and spanned the sump at
the liquid level perpendicular to the inlet. With the tracer bar in this
position the average emission from the entire tank was determined. An
alternate strategy could have been to disperse the tracer gas immediately
below the inlet and measure that emission since it represents the bulk of
the sump emissions, as determined by collecting grab samples around the
sump's perimeter. TJ|« grab sample^, showed concentrations of 1-6 ppm at
ground level on the south side of the sump; therefore spanning the samp
was the method of choice.
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SET 1957 01 0181
Page 6-8
SAMPLERS
TAR.. DISTILLATION PIPE
MAJOR SOURCE OF BEN'ZEi
SU&SUR&&.
RUPTURE.
TOACER
BAR-/6'
.EAST. SAMPLERS
N
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1\
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FIGURE 6-3
LIGHT OIL CONTAMINATED SUMP
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SET 1957 06 0181 . Page 7-1""
7.0 LABORATORY SAMPLE ANALYSIS
Samples returned to Scott's Plumsteadville laboratory-for
analysis included the BaP samples and the liquid samples taken from the
sump.
7.1 LIQUID SAMPLE PREPARATION
Depending upon the complexity of the sample, one of the following
sample preparation procedures was followed prior to the "purge and trap"
procedure and analysis.
Samples Containing Immiscible Liquid Phases
Using a clinical centrifuge (International Equipment .Company,
Massachusetts) immiscible liquid phases were separated and each phase was
analyzed separately for benzene.
Samples Containing Solid and Immiscible Liquid Phases
Samples containing solids of higher density than the liquid phase
were separated by .centrifuge.:or by simple decantation of the liquid. The
different phases in the liquid fraction were then further separated by
centrifuging. Solid and liquid phases were analyzed separately.
. Samples Containing Finely Crystalline Solid Suspension
In analyzing these samples the stoppered sample jars were shaken
for at least half an hour for homogenizing the solution. The uniform
distribution of suspended fine crystalline solid particles was- tested by
determining the percentag« of dry solid in several aliquots of the homoge-
nized mixture.. .A weighed amount of the mixture was analyzed for benzene.
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Page 7-2
SET 1957 06 0181
7.2 PURGE AND TRAP PROCEDURE FOR EXTRACTION OF BENZENE FROM LIQUID PHASE
TO GASEOUS PHASE
An accurately weighed quantity of the sample to be analyzed was
diluted with 20-25 ml of propylene carbonate in a specially designed glass
purging apparatus which was kept immersed in a thermostatted water bath
maintained at 78°C. Benzene free nitrogen gas was bubbled through the
propylene carbonate solution in the purging apparatus at the rate of
0.2 - 0.3 liters/minute, and collected in leak free Tedlar bags. Under
these experimental conditions, 1 1/2 - 2 hours were sufficient to purge
off all the benzene from .the liquid phase to the gaseous phase. The total
volume of nitrogen gas used to purge the sample was accurately.measured
by a calibrated dry gas meter. A diagram of the purge and trap set-up is
shown in Figure 7-1.
Propylene carbonate was found to be an ideal diluting solvent
for the extraction of benzene from all types of liquid samples containing
viscous tar, pitch, light and heavy oil and insoluble particulates. It
was chosen for its high boiling point, low density, and good solvating
capacity.
Scott Environmental Techndosy '
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GAUGE.
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FIGURE 7-1 PURGE AND TRAP METHOD EQUIPMENT SET-UP
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SET 1957 06 0181
Page 7-4
7.3 SAMPLE ANALYSIS • ..
A Perkin-Elraer 900 gas chromatograph was used for the analysis
of the purge bags. A 10 ft. by 1/8 inch stainless steel column packed with
20% SP-2100/0.1% Carbowax 1500 on 80/120 mesh Supelcoport was used for the
analysis. This column gave complete resolution of the benzene peak from
other components present in the purge bags. The 'peak height1 method was
utilized to calculate the concentration of benzene in the purge bags
analyzed. The Parkin-Elmer 900 used for analysis was not equipped with
a backflushing unit. Gas chromatograph conditions were as follows:
GC column temperature: 70°C isothermal
Detector temperature: 190°C
5 ml loop at a temperature of 120°C
Carrier gas flow rate: 30 cc/min He
Hydrogen flow rate: 45 cc/min
Oxygen flow rate: 400 cc/min
Detector: Flame lonization Detector (FID)
,In addition to benzene, the purge bags contained other volatile
hydrocarbons present in the liquid samples such as toluene and naphthalene.
Because this chromatograph was not equipped with a backflush, it was
necessary to elute all heavy organics from the column by heating the column
to 150°C after every two injections for one hour with the carrier gas on.
After cooling the column to 70°C the absence of any organic in the column
which might overlap the benzene peak in the next analysis was checked. When
the column was found to be satisfactorily clean, the next analysis was
continued under the conditions previously described.
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SET 1957 06 0181 Page 7-5
7.4 ANALYSIS OF BENZO-a-PYRENE SAMPLES
BaP samples were of two types: solid pitch, and filter and
resin samples from the air sampling method. Preparation of each of these
types for analysis was as follows:
Solid Pitch - A portion of the pitch was powdered and accurately
weighed, and added to 20 ml of tetrahydrofuran in a round bottom flask. The
mixture was refluxed for 10-12 hours at 66-67°C using a water jacketed
Allihn-type condenser. The mixture was then cooled and filtered to remove
any solid residue insoluble in tetrahydrofuran. The final volume of the
sample solution was made to a definite volume in a calibrated volumetric
flask by the addition of fresh tetrahydrofuran, and the sample was analyzed
within .four hours after the final volume was made up.
Filter and XAD Resin - The desorption of BaP from the filter and
resin was accomplished by extracting with tetrahydrofuran in a soxhlet
extractor for 12 hours. The filter and resin were extracted separately.
Glassware washes with tetrahydrofuran were added to the filter extract and
analyzed jointly. All solutions were concentrated.before analysis to a
volume of 3 ml or less by evaporating the solvent at room temperature by
blowing nitrogen on the liquid surface of the sample solution.
A Hewlett-Packard 5700A temperature programmable gas chromatograph
equipped with dual flame ionization detectors and dual liquid injectors was
used for the BaP analysis. Each liquid injector is connected to a separate
column, and the columns are connected to separate FID's and recorder outputs.
The column used is 6 ft. by 2 mm ID glass column packed with 1.5% SP 301 on
100/120 Supelcoport. Chromatograph conditions were as follows:
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SET 1957 06 0181 Page ?_6
Column temperature: 270°C (isothermal)
Injector temperature.: 250°C
Detector temperature: 250°C
Carrier gas rate: N2 - 20 ml/min. (02 free dry N2 is used)
Detector: Flame lonization Detector (FID)
Sample size per injection: 1 yl
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SET 1957 06'0181: Page 8-1
8.0 QUALITY CONTROL AND QUALITY ASSURANCE
The following sections will address quality control and quality
assurance procedures for th«; field analysis of benzene in air samples and
the laboratory analysis of process liquids and BaP samples.
8.1 FIELD ANALYSIS PROCEDURES
All samples were analyzed in duplicate and as a rule peak heights
were reproduced to within,5%. For some very high concentration samples
(percent range) it was necessary to make dilutions for analysis. When this
was done a fresh dilution was prepared for each injection and peak heights
were reproduced to within 10%. To verify that the system was retaining no
benzene, frequent injections of the standard and nitrogen were made. In all
cases the result was satisfactory.
The Tedlar bags that were reused for sampling were flushed three
times with nitrogen arid allowed to sit overnight after being filled to
approximately three quarters of their capacity. They were analyzed for
benzene content the following day. The background concentrations of the
bags were recorded and varied from 0 to 10 ppra benzene. Care was taken to
use sample bags whose background concentration was very low compared to the
expected concentration of the source.
The accuracy and linearity of the gas chromatographic techniques
used in this program were tested through the use of EPA Audit Samples. Two
standards, a 122.5 ppm and 6.11 ppm benzene were used to analyze the audit
cylinders.
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SET 1957 06 0181. Page 8-2
8.2 PROCEDURES FOR ANALYSIS OF PROCESS LIQUIDS
Scott's .benzene standards, checked against EPA Audit Standards,
were used as reference standards throughout this program. The accuracy and
linearity of the gas chromatographic technique for benzene analysis was
tested through the use of EPA Audit Standards which were available to Scott.
Gas chromatographic analysis of the samples and standard were performed
under identical conditions to assure the accuracy of the analytical data
generated.
Each batch of propylene carbonate which was used as the diluting
solvent in the purge and trap technique was analyzed for benzene content by
subjecting 25 ml of propylene carbonate to the purge and trap procedure
followed by gas chromatographic analysis of the trapped gas under identical
conditions as described in Section 5.2. All batches of analytical grade
propylene carbonate were found to be free from benzene.
Every day before the analysis of samples the purging apparatus and
trapping bags were tested for absence of benzene. Whenever the whole system
was found to be free from benzene to the lowest detectable limit of the
instrument, the samples were analyzed using the purging apparatus and the
trapping gas sampling bags.
Generally an accurately weighed mass of each sample was subjected
to purge and trap procedure only once and the trapped gas sample was repeat-
edly analyzed- by GC until the analytical data of consecutive GC analyses varied
by ±0.5% or less.
Scott EnvfrontDentcinedTncJogy Inc
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SET 1957 06 0181 Page 8-3
For randomly selected samples, the whole analytical procedure was
repeated with a different weighed mass of the source sample to check the
validity and accuracy of the analytical methodology. The analytical data
for different runs were found not to vary by more than 5%.
By purging the sample with nitrogen under the experimental con-
ditions as utilized by Scott, the recovery of benzene from the sample 'was
quantitative and this has been verified by analyzing a standard benzene
solution in propylene carbonate containing tar and pitch.
8.3 PROCEDURES FOR BaP ANALYSIS
For the purpose of generating reliable experimental data the
following procedure was carried out.
Before actual analysis of a sample, 1 pi of pure tetrahydrofuran
which is used for extracting PNA's including BaP from pitch, is injected
into the column under the identical conditions as outlined in Section 7.4,
and the chromatograph is recorded. From the analysis of the chromatogram
the background concentration of any compound present in the solvent is
recorded. In our work we find that the solvent we used for extracting
PNA's from pitch is completely free from any PNA background including BaP-
This also indicates that the syringe, needle, and all lines from the
injection port to the FID are free from contaminant.
A standard toluene solution of a mixture of ten polynuclear
aromatic hydrocarbons including BaP is used as a calibration standard
The standard solution contains phenanthrene, fluoranthene, triphenylene,
chrysene, perylene, anthracene, pyrene, benz(a)anthracene, benzo(e)pyrene
and benzo(a)pyrene, and the concentration of each compound in the solution
is 0.5 mg per milliliter of the standard solution.
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SET 1957 06 0181 Page 8-4
One pi of the standard solution is injected under identical con-
ditions as previously outlined and the chromatogram is recorded. Each
compound is identified by comparing the sample chromatogram with a standard
chromatogram under similar GC experimental conditions. Several injections
are made until all the peak areas of benzo(a)pyrene in different individual
chromatograms are within ±2% variation. Standard peak area of Benzo(a)-
pyrene is then calculated by averaging these individual peak areas (at least
three). Any individual peak area will vary not more than ±2% from this
average value.
Scott Environmental Technolosylnc
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