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PUBLICATIONS

NISTIR 88-3822

Environment Effects

of Oil Spill Combustion

D. Evans, G. Mulholland, D. Gross, H. Baum, and K. Saito

U.S. DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

(Formerly National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

September 1987

Issued September 1988

Sponsored by

Minerals Management Service

Department of the Interior

Reston, VA 22091

75 YMnStimulating America s Ptogrew 1913-m*

NISTIR 88-3822

. ux

Environment Effects of

Oil Spill Combustion

D. Evans, G. Mulholland, D. Gross, and H. Baum

U.S. DEPARTMENT OF COMMERCE

National Institute of Standards and Technology

(Formerly National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

K. Saito

Department of Mechanical Engineering

University of Kentucky

Lexington, KY 40506

September 1987

Issued September 1988

National Bureau of Standards became the

National Institute of Standards and Technology

on August 23, 1988, when the Omnibus Trade and

Competitiveness Act was signed. NIST retains

all NBS functions. Its new programs will encourage

improved use of technology by U.S. industry.

Sponsored by

Minerals Management Service

Department of the Interior

Reston, VA 22091

U.S. DEPARTMENT OF COMMERCE

C. William Verity, Secretary

NATIONAL INSTITUTE OF STANDARDS

AND TECHNOLOGY

Ernest Ambler, Director

Table of Contents

Page

List of Tables iv

List of Figures v

Abstract 1

1 . 0 Background 1

2.0 Experimental Facilities 2

3.0 Crude Oil Materials 3

4.0 Burning Characteristics 3

5.0 Smoke Characteristics 6

5.1 Smoke Emission Measurements 7

5.2 Gas Emission Measurements 8

5.3 Elemental and Organic Carbon Analysis 8

5.4 Analysis of Polynuclear Aromatic Hydrocarbons 8

5.5 Sample Preparation 9

5.6 Gas Chromatographic Quantification 9

5.7 Results and Discussion 10

6.0 Plume Dispersal Analysis 11

7.0 Summary * 16

8.0 Acknowledgement 18

9.0 References 18

iii
List of Tables

Page

Table 1. Properties of Oils (Typical Data) 20

Table 2. Summary of Burning Data in 1.2 dia Pan 21

Table 3. Summary of Smoke Emission Data for 60 CM Diameter

Alberta Sweet Crude Oil Pool Fires 22

Table 4. Gaseous Emission From Alberta Sweet Crude Oil 23

Table 5. Organic/Elemental Analysis of Smoke From

Burning of Alberta Sweet Crude Oil 24

Table 6. Mean PAH Concentration for Alberta Sweet Crude

Oil Smoke Samples Collected at 100 °C 25

Table 7 . Mean Pah Concentration for Alberta Sweet Crude

Oil Smoke Samples Collected at Ambient Temperature ....... 26

Table 8 . Comparison of PAH Content of Alberta Sweet Crude

Oil and Smoke from Burned Oil 27

IV
List of Figures

Page

Figure 1. Schematic of Smoke Dilution System 28

Figure 2. Diagrammatic Sketch of Experimental Arrangement ’. . . 29

Figure 3. Thermocouple Rake for Measurement of Oil -Water

Layer Temperature 30

Figure 4. Thermal Conductivity of Crude Oils 31

Figure 5. Burn Sequence for 10 mm Thick Layer

of La Rosa Crude Oil 32

Figure 6. Flame Plume Temperature for Murban Crude

at Different Layer Thickness 33

Figure 7. Energy Release Rate for Murban Crude at

Different Layer Thickness 34

Figure 8. Recorded Radiation Feedback to Center of

Pan for Murban Crude at Different Layer

Thickness 35

Figure 9. Gas Chromatogram of Typical Blank Sample

with I.S. Indicating Internal Standard

and IMP Indicating an Impurity 36

Figure 10. Gas Chromatogram of the First Smoke Sample

Collected at 100°C (H-2, #1). The PAHS

Associated with the Peaks are Identified

in Table 6 37

Figure 11. Gas Chromatogram of the Second Smoke Sample

Collected at 100°C (H-2, #2) 38

Figure 12 . Gas Chromatogram of Smoke Sample Collected

at Ambient Temperature (C-5, #1) 39

Figure 13. Gas Chromatogram of Second Smoke Sample

Collected at Ambient Temperature (C-5, #2) 40

Figure 14. Temperature Contours at Front of Wind Blown

Plume Using Transient Enclosure Flow Analogy 41

Figure 15. Temperature Contours Just Downwind of Fire

Using Transient Enclosure Flow Analogy 42

Figure 16. Temperature Contours at Point of Vortex Pair

Formation Using Transient Enclosure Flow Analogy 43

v
List of Figures (continued)

Figure 17. Far Downwind Temperature Contours Using Transient

Enclosure Flow Analogy

Page

44

vi
ENVIRONMENTAL EFFECTS OF OIL SPILL COMBUSTION

D. Evans, G Mulholland, D. Gross, H. Baum and K. Saito

ABSTRACT

Experimentation and analysis have been performed to quantify the combustion of

crude oil on water. The burning behavior of three crude oils --Alberta Sweet,

La Rosa, and Murban, were studied using 1.2 m diameter pool burns. In smaller

0.6 m diameter pool fires using Alberta Sweet, combustion products were

collected for extensive chemical analysis. This analysis showed that about

10% of the crude oil was converted to smoke in the combustion process. The CO

concentration was a factor of 25 lower than the primary gaseous product C02

, and the emission of NO and N0X were less than one thousandth the concentration

of C02

. The PAH content of the smoke was enriched in the larger molecular

weight species in comparison with the original fuel. A methodology was

developed with which the down wind dispersal of smoke generated by one or more

oil spill fires in close proximity may be predicted. Initial results that

demonstrate the capability of the analysis are presented.

1 . 0 BACKGROUND

In 1985, the Center for Fire Research (CFR) at the U.S. National Bureau of

Standards (NBS) began studies of oil spill combustion under support from the

Minerals Management Service (MMS) of the U.S. Department of the Interior.

This work seeks to quantify the processes involved in oil spill combustion on

open waters and in water filled channels formed in broken ice including

measurements of smoke production and prediction of smoke dispersal. Added

support from the U.S. Coast Guard and Environment Canada has allowed the study

to be broadened in scope and increased in detail.

The long range goal of the research program is to provide measurements and

means to make quantitative predictions of (a) the fraction of oil in a spill

that can be consumed by an in-situ combustion process, (b) the characteristics

of the residual oil, and (c) the characteristics of the combustion product

flow from the burning oil. It is hoped that this information may be cast into

a form that is usable by local officials and oil spill response professionals

as part of the decision making process in the event of an oil spill.

Last year's study included results from experiments to quantify the burning of

0.60 m diameter oil pool fires. Measurements of burning rate, thermal

radiation emission, smoke production and the chemical composition of both the

oil and the burn residue were reported [1]. Calculations were performed to

estimate the surface wind velocities that could be generated by multiple fires

distributed over a large area as might be expected during the burning of an

oil pool confined by broken ice in the arctic. This year's effort is the

first in a two year program to quantify (a) the thermal properties and burning

characteristics of the crude oil, (b) the physical and chemical properties of

the smoke generated in the combustion process, and (c) the expected dispersal

of the soot through the atmosphere and deposition down wind of the oil fires.

1
This report summarizes results from these three main research thrusts all of

which are at the mid-point of the two year effort.

2.0 EXPERIMENTAL FACILITIES

Crude oil burn tests were conducted in the CFR large-scale test building using

both the large and small calorimeter hoods. The small hood facility could

accommodate oil pool fires up to 0.6 m in diameter. This hood was used to

collect all smoke and gas samples for quantitative analysis. Details of this

experimental gas and soot sampling installation were reported previously [1]

A new controlled dilution probe, shown in Figure 1, was added to the exhaust

stack of the small calorimeter hood for the present studies. This probe is

used to cool and dilute the gas sampled from the stack by adding a mass flow

of chilled air approximately twice the mass flow of the combustion products

sampled. With the addition of this probe to the existing system two sampling

conditions for the soot could be examined. The previous system maintained the

gas sample at the nominal 100 °C from the stack to the filters where soot

samples were deposited. The new system cools and dilutes the sample such that

at the filters the temperature is within 2 °C of ambient temperature.

For larger test burns, a steel pan measuring 1.20 m in diameter and 0.30 m in

height was installed under the large calorimeter hood, as shown in Figure 2.

The pan was elevated 0.6 m above the platform floor by means of blocks to

allow for the introduction of instrumentation and for supply and drainage of

water through the bottom of the pan. A predetermined quantity of oil was

floated on the water surface the level of which could be controlled to

maintain a burning surface 10 mm to 12 mm below the pan rim. Perforated steel

plates were arranged to form an artificial "floor" at the level of the pan

rim. This was intended to limit, but not to completely exclude, air supply

from below the pan rim, and also to allow for liquid spillover during test

periods where energetic water boiling was expected to occur based on results

of previous smaller scale burns [1] . An annular trough containing a layer of

moist sand was located around the pan below the perforated plates to contain

any spillover or splattered droplets of burning oil. Sorbent pads of

oleophilic polypropylene fiber were used to adsorb the oil remaining on the

water surface after each test in order to determine the weight of the residue.

Instrumentation was provided for the measurement of flame temperature; oil and

water temperature; energy release rate; radiation feedback from the flames to

the liquid surface; and radiation from the flames to the surrounding.

Placement of this instrumentation is shown in Figure 2. All thermocouples

were of the metallic -sheathed, mineral- insulated type. Two specially-designed

thermocouple rakes were commercially fabricated and were mounted to provide

temperature measurement along two vertical axes which included the entire oil

layer depth plus positions in the fuel -rich air above the oil and in the

water. As shown in Figure 3, each thermocouple rake consisted of 13

thermocouples the top seven of which were spaced at 1.5 mm separation. At the

lower positions that extended to 76.2 mm below the top thermocouple, spacing

was gradually increased to 3.1 mm, 6.3 mm, 12.7 mm, and 25.4 mm. The in-pool

radiometers were commercially fabricated instruments of the Schmidt-Boelter

type, provided with Irtran windows and nitrogen gas purging as well as water

2
cooling. They were positioned approximately 25 mm above the oil surface

facing up at the center, at a quarter-point, and near the rim of the pan.

The energy release rate of the fires burned under this hood are determined

using the oxygen consumption calorimeter technique. The energy release rate is

calculated from measured decreases in oxygen concentration in the total flow

of gases through the stack [2].

3.0 CRUDE OIL MATERIALS

The burning characteristics of three types of crude oils were investigated in

the large calorimeter -- Alberta Sweet, La Rosa and Murban. These oils were

obtained from supplies at the EPA-OHMSETT facility in New Jersey. According

to available oil property information [3], reproduced in Table 1, these oils

differ in composition, notably in the percent of the heavier wax plus

asphaltene fractions, with Alberta Sweet crude being the lowest and La Rosa

crude being the highest.

Important thermal characteristics of the crude oils used in this study are

being measured. The thermal conductivity of each oil was measured using the

transient hot-wire method [4]

In this method the thermal conductivity of the

liquid is determined by comparing the measured time dependent temperature

change of a wire submerged in the liquid reservoir at known initial

temperature with the known analytic solution. The measured results for the

three oils over the temperature range 0 °C to 50 °C are shown in Figure 4.

4.0 BURNING CHARACTERISTICS

The burning characteristics of the three crude oils were measured in burns

under the large calorimeter hood. The use of a 1.2 m diameter pan permitted

controlled burning experiments to be conducted under conditions representative

of the radiation- dominated, turbulent flow regime of larger pool fires. Each

oil was studied at four initial layer thicknesses -- 2 mm, 5 mm, 10 mm, and

25 mm. In each test a pre-weighed sample of oil, corresponding to the desired

oil layer thickness, was floated on the water surface. The oil level control

device was operated in most tests to maintain the oil surface nominally 12 mm

below the top of the pan rim. At this depth, the two top thermocouples on the

rakes were above the oil surface at the start of each test. As soon as the

surface was calm and stabilized and all instrumentation was in operating

condition (usually within 2 minutes) , an ignition flame was applied to the oil

surface. All temperatures, radiation levels, heat release rate and exhaust

gas measurements were scanned automatically at 5 second intervals and recorded

on magnetic tape. After burning ceased, a pre-weighed sorbent pad was placed

on the surface to adsorb the residual oil and then the oil soaked pad was

reweighed. No attempt was made to capture oil which had splattered over the

pan rim or to account for water picked up by the sorbent pad. Oil which

remained on the radiometers, thermocouples, and pan surfaces was removed with

solvent-moistened napkins, prior to the next test. Photographs showing the

typical sequence in a burn are reproduced in Figure 5.

3
To date, 12 tests have been completed. Although the data have not been

completely analyzed and evaluated, a summary of selected data is given in

Table 2. Principal emphasis in this report will be on discussion of

temperatures measured in the flame -plume temperature, energy release rate, and

radiation feedback to the oil surface.

For a given crude oil, the maximum recorded flame -plume temperature increased

slightly with oil layer thickness. As shown in Figure 6 for the Murban crude,

the flame temperature did not reach a steady state condition for oil layer

thicknesses of 2 mm and 5 mm, but approached a steady- state value (before

reaching a peak) for the larger thicknesses. The peak temperature

corresponding to the vigorous burning period prior to the end of burning was

approximately 100 °C to 150 °C above the "steady- state" temperature.

The maximum recorded energy release rate also increased with oil layer

thickness, but then decreased for the 25 mm layer. The energy release rate

for the Murban crude exhibited an approach to steady- state for the 10 mm and

25 mm layer thicknesses prior to reaching a peak value during the vigorous

burning period (see Figure 7) . The quasi-steady-state energy release rate for

the Murban crude was approximately 0.95 MW (840 kW/m2

) , actually decreasing

noticeably prior to the rapid increase in burning corresponding to a peak

level of 2.1 MW (1860 kW/m2

) prior to burnout. The decrease in energy release

rate during the steady burning phase (100 to 500) seconds appears to be

associated with the changing composition of the crude oil towards the heavier

fractions and the concurrent decreased combustion efficiency leading to the

apparent generation of more smoke. The corresponding values of steady- state

and peak energy release rates for the Alberta Sweet crude were 1.15 MW

(1000 kW/m2

) and 2.7 MW (2400 kW/m2

) . These values are significantly greater

than the area specific energy release rate for Murban crude measured in the

0.6 m diameter pan (720 kW/m2

) . The peak energy release rate for the La Rosa

crude was approximately 50% greater than for the Murban crude.

There was a similar increase in the recorded peak levels of radiant heat

feedback to the Murban crude oil surface as a function of oil layer thickness

(see Figure 8). However, for the Alberta Sweet and La Rosa crudes, the peak

levels of feedback radiation at the center appeared to be lower for the 25 mm

layer than for the 10 mm layer. Also, the recorded level of feedback radiation

did not follow the same temporal pattern of the peaks of the flame temperature

and the energy release rate, particularly for the 10 mm and 25 mm layer

depths. Several problems with the present radiation measurement system must be

overcome to obtain more reliable data. One problem is with the splattering of

oil from the pool up onto the radiometers during the vigorous burning period

near the end of the test. The other is the nitrogen purging of the

radiometers interfering with the normal burning. Intense burning due to fire

whirls induced by the nitrogen flow immediately above the radiometers may

significantly influence the readings.

4
The following observations were noted during this series of tests:

1 . Ignition

With the Alberta Sweet crude oil, ignition was immediate with active and

rapid flaming involving the entire oil layer. With the La Rosa crude,

there was a delay of approximately 60 to 90 seconds before the flaming

spread to involve the entire surface. The response of the Murban crude

was intermediate

2 . Fire whirls

Local intense burning, usually with strong vortex motion, was observed

in the vicinity of the gas -purged radiometers. This appeared to be the

result of the air-aspirating effect of the nitrogen jet used to minimize

oil condensation on the radiometer window. This may be noted in the

photographic sequence of the 10 mm La Rosa burn test shown in Figure 5.

Although this activity was very localized and did not appear to affect

the overall measurements of external radiation, some in-pool radiation

feedback measurements may be affected. Knowledge of this effect may be

of interest where methods for increasing local rates of burning are

being considered.

3 . Oil splatter

During the vigorous burning period, boiling water and oil droplets

splattered up and out of the pan. The La Rosa and the Murban crudes

caused extensive splattering, with flaming droplets from the former

approaching 1 m in height. The splattering occurred at the end of the

test when the remaining thin layer of oil contained a greater percentage

of higher boiling point fractions. The increased surface temperature

and thin oil thickness caused boiling in the water sublayer.

4 . Smoke

The quantity of smoke observed within the flame mass appeared to be

greater as the oil layer thickness was increased and smoke appeared to

be generated at a greater rate and closer to the oil surface late in the

test. The La Rosa and Murban had noticeably more smoke than Alberta

Sweet

5 . Boilover

With the Murban and La Rosa crudes at an oil layer thickness of 25 mm,

boilover occurred at the end the test. In the test with 25 mm initial

layer depth of La Rosa, the boilover was relatively intense and

considerable oil spilled or splattered out over the rim of the pan. The

Alberta Sweet crude exhibited only a minor tendency to boilover.

6 . Residue

The oil residue remaining following burnout varied with the type of oil

and the layer thickness. With one exception, more oil remained from the

thickest (25 mm) layer of each oil and slightly more residue remained

with the La Rosa crude than with the other oils. The measured residue

5
for all tests ranged from 0.6 kg to 1.2 kg corresponding to a layer

depth of approximately 0.6 mm to 1.2 mm.

The effectiveness of combustion as an oil spill mitigation tool depends

critically upon the feedback of radiation from the flames to the burning oil

surface. This project is attempting to emphasize this measurement,

particularly since prior investigations reported in the literature [5,6] have

experienced experimental difficulties and analytical models have never been

fully validated. This study has not been completely immune to similar

experimental problems, but significant progress is being made. Initial

indications are that radiation feedback to the surface may range from less

than 2 percent to more than 5 percent of the total energy release rate

depending upon the type of oil and its layer thickness. Based on initial

estimates of the temperature gradients at the oil surface (22°C/mm to

50°C/mm), and the measured thermal conductivity of the crudes (0.12 W/mK to

0.13 W/mK), the rate of heat conduction into the oil is approximately 2 kW/m2 to 6 kW/m2 or less than 20 percent of the radiant energy approaching the

surface in these tests. A better estimation will be available with additional

tests, improved instrumentation, completion of energy balances, and comparison

with a flame radiation model which accounts for radiant energy blockage by the

cool fuel vapor-rich zone above the oil surface [7]. Examination of the

effects of water temperature, oil spill weathering, and wind on the combustion

process will require additional experimentation and calculations.

5.0 SMOKE CHARACTERISTICS

The focus of this part of the project is the chemical characterization of the

smoke produced by burning crude oil. The measurements include the organic

versus elemental carbon in the smoke, the quantity of selected polynuclear

aromatic (PAH) compounds in the smoke, and the amount of C02 , CO, NO, and N0X

emitted. Much of the analysis effort was concentrated on the PAH analysis.

These materials are of environmental concern, because some have been reported

to be carcinogenic to animals [8]

Thd results of the PAH analysis are

compared with the PAH component of the fuel itself.

In all tests in this series, Alberta Sweet crude oil was burned in a 0.6 m

diameter pool. Approximately 9 liters of crude oil were burned in each test,

which corresponded to a fuel depth of about 30 mm. The sample burning time

was found to be about fifteen minutes. Smoke samples were collected on

filters heated to match the stack temperature, about 100° C, using a heated

transfer line described in last year's report [1]. The first smoke sample was

collected from the time of visually steady burning, typically one minute into

the burn, for about six minutes. The collection of a second sample began

immediately thereafter and lasted for about another six minutes. Smoke

samples were also diluted before collection with air cooled to about 10°C to

simulate the cooling that would naturally occur in a rising smoke plume. In

this case, both filter samples were collected in parallel over about thirteen

minutes of the burn. The filter collections in all the tests were completed

before the rapid burning at the end of the test.

6
5 . 1 Smoke Emission Measurements

The results of the smoke emission measurements are contained in Table 3. The

smoke yield, e, which is defined as the mass of smoke aerosol generated per

mass of fuel consumed, is found to have a value of about 0.10. This is

similar to the value found in previous test with PRUDHOE BAY crude oil [1],

the value of e increases in going from sample 1 to sample 2 indicating that

the smoke emission increases as the fuel presumably distills leaving the

sootier component for the later stage of burning.

One important parameter in regard to visibility effects of the smoke is the

specific extinction coefficient relative to the fuel, Kf

Kf = K/(mf /V) , (1)

where K is the extinction coefficient per meter, mf is the fuel mass loss

rate, and V is the volumetric flow rate through the duct. As a heuristic

example, a Kf value of 1 m

2 /g means that if the smoke produced by one gram of

material were collected over aim2 area, the light incident on this area

would be blocked by the smoke (I/I Q = e" 1

) . The value of Kf increases from

about 0.7 to 1.1 m

2 /g for the second collection period for both H-l and H-4

indicating again that the fire becomes sootier as the burning proceeds. The

average value of Kf

, 0.87 m

2 /g, is close to the value obtained with Prudhoe

Bay crude oil, 0.96 m

2 /g.

A second optical property of interest is the extinction coefficient per mass

concentration of the smoke, K£

, defined by

Ks = K/ms , (2)

where ms is the mass concentration of smoke. The quantity Ks is an intrinsic

property of the smoke depending on (a) the optical properties of the smoke,

(b) the size distribution of the smoke, and (c) the wavelength of light. The

average value of 9.4 m

2 /g obtained from the first two tests is in good

agreement with the value obtained for PRUDHOE BAY crude oil, 9.1 m

2 /g.

The smoke collected in tests C-5 and C-7 was first diluted and thus cooled by

the probe illustrated in Figure 1. The mass flow of ice cooled dilution air

is approximately twice the mass flow of the air sampled from the stack. The

manifold temperature just prior to the filter is observed to be within two °C

of the ambient temperature. The value of e obtained under these conditions is

15% to 20% less than the value obtained for the heated, undiluted sample.

Normally, one would expect an increase in e with dilution by cool air

resulting from the condensation of organic vapors. The PAH analysis discussed

below clearly shows that the higher vapor pressure PAH's are greatly enriched

in the diluted sample compared to the high temperature sample. The observed

decrease in these tests may be the result of smoke deposition by

thermophoresis in the entrance portion of the diluter and by turbulent flow in

the mixing region of the diluter.

7
5 .

Gas Emission Measurements

The emission of CO, C02 , NO, and N0X was monitored during selected tests. The

concentrations of CO and C02 were measured by standard gas analysis

instrumentation based on nondispersive infrared spectroscopy. The smoke

aerosol was filtered and the moisture condensed out with a dry ice trap before

the sampled gas entered the CO and C02 analyzers. The analysis of the

nitrogen oxides is based on the reaction of ozone with the oxides and

detection of the resulting chemiluminescence with a photocell. The C02 accounts for over 95% of the gaseous products measured as indicated in

Table 4. The other principal product of combustion, H2 0, was not measured.

The volume fraction of CO, NO, and N0X relative to C02 were found to be about

0.038, 1 . 5x10“ A

, and 4xl0~\ respectively. The concentrations of NO and N0x were just above the detection threshold.

5 .

Elemental and Organic Carbon Analysis

Smoke aerosol produced by flaming combustion is composed of a graphitic or so

called elemental carbon fraction and an organic carbon fraction. Smoke

samples were collected on quartz fiber filters and sent to a contract

laboratory for thermal -optical analysis for organic/elemental carbon [9]

Standard precautions were taken to avoid sample contamination before sample

collection by heating the filter for several hours at 700 °C and also heating

the aluminum foil used to line the sample containers (petri dishes) to 500 °C

for several hours . The organic fraction of the sample is determined by

heating the sample in pure helium in four temperature steps up to 770 °C. The

pyrolysis products flow through a heated catalyst and are converted to C02

, which is detected by nondispersive infrared spectroscopy. The second stage of

the analysis consists of reducing the temperature to 525 °C and introducing

02 (2%) . The temperature is increased in two steps to 770 °C and the

elemental carbon is oxidized to CO and C02

. Ultimately all of the carbon is

converted to C02 by the catalyst.

The optical absorbance of the sample is used to determine whether elemental

carbon is being produced by pyrolytic conversion of the organic carbon and

also to correct for this effect. The maximum deposit of elemental carbon that

allows light to be transmitted through the sample is about 15 /ig/cm2

. As

indicated in Table 5, the elemental carbon content of the smoke is over 90%.

The large blank reading for the high temperature filter sample may result from

the diffusion of condensible organic vapors from the filter manifold onto the

filter. No sample is drawn through the blank filter, but there is an open

path between the manifold and the filter. The fact that the high temperature

collection yields a slightly lower elemental carbon content may be an artifact

resulting from vapor diffusion.

5 .

Analysis of Polynuclear Aromatic Hydrocarbons

Eight smoke samples weighing 10 mg to 15 mg each were deposited on teflon

filters and were analyzed for 15 polynuclear aromatic hydrocarbons (PAH's)

using combined liquid and gas chromatographic techniques. Wise and Benner

from the Center for Analytical Chemistry (NBS) performed the analysis on four

8
of the samples by a method previously used by them in quantifying the PAH

content of two standard reference air particulate samples [10]. The PAH

concentration in the smoke for samples similar to those analyzed at NBS were

analyzed at the laboratories of Environment Canada in Ottawa. A preliminary

analysis of heteroatomic PAHs was also made by Environment Canada.

5 . 5 Sample Preparation

At NBS the samples were spiked with internal standards (phenanthrene-d^^ 0 and

1-n-butylpyrene) and Soxhlet extracted with dichloromethane (DCM) for

approximately 20 hours. The extracts were concentrated by rotary evaporation

to less than 5 ml and further concentrated under nitrogen to dryness. The

residues were dissolved in 1 mL of DCM and approximately half of each extract

was pipetted onto a silica cartridge (Sep-Pak, Waters, Assoc., Milford, MA) 1 and eluted with 15 mL of a solution of 10% DCM in pentane. This

chromatography is performed to isolate an enriched PAH fraction. The eluates

were concentrated to dryness under nitrogen and were dissolved in 1 mL of a

solution of 5% DCM in pentane. The samples were separated into subfractions

by normal-phase LC on a semi-preparative amino-silane liquid chromatographic

column (yuBondapak NH2

, Waters Assoc., Milford, MA) using 5% DCM in pentane as

the mobile phase operated at a flow rate of 5 mL/min. Collection of an

aromatic fraction was begun just before the elution of phenanthrene (30 mL)

and was continued until well after the elution of coronene (200 mL total

collected) . Elution volumes of these two PAHs were determined prior to sample

injection. The fractionated samples were concentrated by rotary evaporation,

transferred to 100 /iL vials, further concentrated to dryness under nitrogen

and the residues dissolved in DCM.

5 . 6 Gas Chromatographic Quantification

Capillary gas chromatography with flame ionization detection (GC-FID) was used

at NBS for the measurement of 15 PAHs in the four filter extracts. Each of

the four extracts was chromatographed in duplicate injecting approximately

1 onto a 30 m x 0.25 mm i.d. fused silica capillary column (DB-5, 0.25 ^urn phase thickness, J&W Scientific, Inc.) using helium as the carrier gas

(20 psi)

The injector and detector temperatures were 300 °C and 320 °C,

respectively, and the split flow was set at 30 mL/min. The temperature

program used in the study was the following: 150 °C (hold for 2 min) ramp at

4 °C/min to 280 °C (hold for 15 min) . The PAHs were determined by comparison

of peak areas of the analytes with those of the internal standards. Typical

GC-FID chromatograms for the four samples and a blank are shown in Figures 9-

13. The blank (Figure 9) had been spiked with the same amount of internal

standards as the samples and proved to be virtually free of any impurity

except for a compound that eluted at approximately 14 minutes. Fortunately,

'•Certain commercial equipment, instruments, and materials are identified

in this paper to specify adequately the experimental procedure. In no case

does such identification imply recommendation or endorsement by the National

Bureau of Standards, nor does it imply that the material or equipment

identified is necessarily the best available for the purpose.

9
this artifact did not cause any difficulty in the quantification of the

fifteen PAHs . The names and structures of PAHs for selected peaks in the

chromatogram are given in Figure 12. It is also seen in Figure 12 that the

smaller PAHs are eluted from the column first.

Environment Canada has made a preliminary analysis for nitrogen containing

PAHs by GC analysis with a phosphorous detector. In sample 7, #2, the

following results were obtained: nitro- fluorene (15 /ig/g) » nitro- anthracene

(5 Mg/g) . nitro- fluoranthene (14 ng/g) , and nitro-benzo [a] pyrene (7 Mg/g)

Nitrogen containing PAHs were not detected in the other samples, presumably,

because the concentrations were below the 4 ng/g detection limit of the

analysis technique. No evidence of nitrogen containing PAHs was found in the

crude oil itself at a detection limit of about 0.2 /ig/g.

5 . 7 Results and Discussion

Concentrations of 18 PAHs are shown in Tables 6 and 7 based on results from

both NBS and Environment Canada (EC) . The NBS results for the samples

collected at the higher temperature (H-2, #1 and #2) suggest some preferential

losses of the more volatile PAH during sample work-up since the concentrations

calculated versus phenanthrene - d-L 0 were a factor of two greater than those

calculated versus 1-n-butylpyrene . One has difficulty explaining these

apparent losses, since the samples were prepared in the same manner as the

ambient temperature samples, which showed good agreement between

concentrations calculated using the two internal standards. Reported

concentrations of phenanthrene for H-2 were calculated using phenanthrened1

as the internal standard, since its volatility is similar to that of

phenanthrene. In all other cases, 1-n-butylpyrene was used.

The analysis performed by EC involved spiking the samples -with 5 internal

standards: anthracene -

x

, pyrene -d10 , benz [a] anthracene -d12 , perylene-d12 , and fluoranthene -

x

. The recovery percent used in the analysis was the

average of the first four internal standards given above and corresponded to a

value of 60 to 70%. The recovery percent of fluoranthene -d10 was 20% to 60%

larger than the other standards and was not included. Generally speaking,

there was more variability in the recovery percent for these smoke samples

than is typically observed by EC for other samples.

Two diluted samples were collected simultaneously throughout most of the 900

second test in order to obtain enough sample for analysis. This is the reason

for the good agreement between C-5,#l and C-5,#2 and between C-7,#l and C-7,#2

in Table 7. The high temperature samples were obtained sequentially. It

appears from Table 6 that the sample H-2, #2 and sample H-4,#2, which are

collected in the latter part of the burn, are enriched in the larger, lower

vapor pressure PAHs.

It is apparent from both the Figures 10-13 and Tables 6 and 7 that the samples

collected at the lower temperature are enriched in PAH content. The sum of

selected PAH concentrations for 12 species listed in Table 7 is 4200 to

4800 /zg/g smoke for the diluted sample and 900 to 2700 (j, g/g smoke for the high

temperature collection. For the three and four ring PAHs, the enrichment for

the lower temperature sample is at least a factor of 15 greater than the high

10
temperature samples based on the NBS analysis and a factor of 3-20 enrichment

base on EC. The enrichment in anthracene and fluoranthene observed in these

tests is at least a factor of 2 greater than observed for PAH collected as a

function of filter temperature in the laminar premixed sooting combustion of

benzene [11].

The agreement between the NBS and EC results for the diluted samples is

typically 10-20% with Indeno [ 1 , 2 , 3-cd]pyrene as the one exception. There is

also a significant difference between laboratories for this species for the

high temperature collection. Overall the EC results for the high temperature

collection are about twice the NBS results with the largest differences

observed for the smaller PAHs

It is expected that the diluted samples better represent the chemistry of

smoke collected downwind of a crude oil burn given the cooling the smoke would

naturally experience as the smoke plume rises up and entrains air. The

combustion conditions including flame size, availability of 02

, and the degree

of mixing together with the fuel chemistry have been shown to affect the PAH

emission [ 11]

It is known that the crude oil fuels themselves have a PAH component. It is

of interest to compare the amount of selected PAHs per gram of fuel versus the

amounts of PAHs collected in the smoke per gram of fuel consumed. As seen in

Table 8, the relative concentration of the individual PAHs compounds is

different in the fuel compared to the smoke. Overall, for the compounds

measured, the total PAH content of the smoke and the original oil burned are

nearly equal. For example, the concentration of phenanthrene plus anthracene

in the fuel (296 /i g/g) is about 2 times greater than for the smoke (133 /ig/g

fuel burned), while the concentration of benzo [a] pyrene (BaP) is a factor of

three lower for the fuel (5 fj. g/g) compared to the smoke (18 Mg/g) . This

indicates that the combustion process itself is generating specific PAHs and

that the PAH content of the fuel will not represent the distribution of PAHs

emitted. There is about a four- fold enrichment of the four- six ring PAHs in

the smoke compared to the crude oil.

BaP has been used as a surrogate for the overall carcinogenic effect of PAHs.

The higher BaP concentration in the smoke relative to the fuel is of

environmental concern; however, several key issues must be addressed before a full assessment of PAH emission can be made. The effect of burning rate on

PAH emission should be analyzed. Smoke was not collected during the very

rapid burning stage near the end of a test, but this burning phase may be

dominant in a large fire with a thin oil layer. Preliminary data indicate for

the first time the existence of nitrogen-containing PAHs in smoke from burning

crude oil. The concentration is apparently low being at the lower limit of

the present analysis, so that additional analysis at great resolution is need

to clearly evaluate the present findings. An analysis of the vapor phase PAHs

should be made to complete the present analysis that has concentrated on

condensed phase products.

6.0 PLUME DISPERSAL ANALYSIS

The object of this analysis is to develop a methodology which will permit the

prediction of smoke dispersal generated by one or more oil spill fires in

11
close proximity. In order to allow for the possibility of large composite

fires, there are three main ingredients that must be taken into account in the

analysis. They are the stratification of the atmosphere, ambient winds, and

the properties of the initial fire plume. The scale of the phenomena to be

considered is roughly 1-3 kilometers in the vertical (the plume rise height)

a comparable spread laterally in a direction perpendicular to the ambient

wind, and anywhere from 20 to 200 kilometers in the downwind direction.

Given the scale of these plumes, the Reynolds or Grashof numbers of the

associated flow patterns are enormous, so a description which omits molecular

diffusion of mass, momentum and energy is reasonable. The transport of smoke

aerosol, the object of primary interest, is dominated by large scale

advection. We are not concerned with the initial establishment of the plumes,

so that a steady state picture of the dispersal process is appropriate. Under

these circumstances the equations expressing the conservation of mass,

momentum, and energy in the flow take the form:

(U • V) p + pV • U =0

(U-V) U + VP - pg = 0 (3)

pC

p

(U-V) T - (U • V) P = 0

Here p , U, P, and T are respectively the density, velocity, pressure and

temperature in the atmosphere. The quantity g is the gravitational

acceleration and C

p

the specific heat of the gas. The conservation laws are

supplemented by an equation of state

P = pRT (4)

This system of equations must be solved subject to boundary conditions which

introduce the three ingredients which characterize the flow of interest. The

ambient atmosphere is stratified with a scale height H given by:

H - P0 /P0 g (5)

Here, the subscript indicates reference sea level values. The ambient

atmosphere is assumed to vary on a larger scale in the horizontal directions

than any length scale of interest in this study. The atmosphere then will

depend only upon the vertical variable in the form y/H. Thus, far from any

fire plume:

P - Po Pa(y)

p = Pc p a

( y)

Ay = y/H

12
The ambient wind is assumed to vary with height but flow in a constant

direction. The windward direction is the x-direction, the vertical coordinate

is y, and the lateral direction perpendicular to x and y is z. The

corresponding velocity components are u, v, w. Thus:

x = (x,y,z)

(u,v,w)

The boundary condition far from any plume can then be expressed in the form:

u = Uo u0 (y)

v = w = 0

(7)

Finally, the input from the fire plumes must be prescribed. It is not

possible to calculate anything in or near the combustion zone based on

equations (3) and (4), since the small scale physical and chemical processes

are not described by these equations. There is no point appending the

additional terms required, since we cannot even solve the above equations

without further approximation. Instead, the vertical velocities and

temperatures characteristic of a fire of prescribed strength are used as input

variables. McCaffrey [12] has developed a set of correlations for fire plume

velocities and temperatures which are ideal for this purpose. These

correlations have been used to calculate inflow velocities into oil spill

fires by the authors [1]. The time average vertical velocity and temperature

distributions have the form:

v = (gD) 1

2 V (y/D) exp [-(r/R) 2

]

(T - T0 )/T0 = 0 (y/D) exp [-o(r/R) 2

]

( 8 ) D = (Q/4 G C

p Jg) 2/5

r

2 = (x - xc

) 2 + (z - z

c

) 2

Here Q is the total rate of heat release from the fire centered at (xc *z c

)

The plume centerline velocity V (y/D)

temperature 6 (y/D)

and width R(y/D)

together with the ratio of velocity to thermal profile with a are given by

McCaffrey [12].

Note that there is no need to use these plume input functions at ground level

In practice, it would be desirable to select an attitude yo where the excess

temperature is sufficiently small and the plume sufficiently broad that

equations (3) can be adequately solved in the presence of the wind that

disperses the plume. As yo increases, this condition becomes easier to meet

for a given fire (or fires)

On the other hand, we wish to begin the

calculation at an altitude sufficiently low so that the wind has not yet had

much of an effect on the plume, and distinct fire plumes have not yet merged.

13
For individual fires in the range 102 - 103 MW, this altitude should typically

be in the range 50 - 150 M.

As mentioned above, it is necessary to simplify equations (3) if reasonably

accurate numerical solutions are to be obtained without prodigious

computational efforts. As a practical matter, it is much easier to solve

these equations if the numerical method can march in the direction of the wind

and solve a two-dimensional problem in each cross flow plane. Moreover, we

would like to reduce the equations to an equivalent incompressible form

previously used to study flows generated by enclosure fires [13,14]. To this

end, it is more convenient to work with the potential temperature 6, rather

than the temperature itself. By definition we have:

T = T0 (P/PQ

)

( 7 - i ) / 7 e (9)

The energy equation and equation of state now take the following form:

(U-V) 6=0

<P/po)

i/i _ (P/Pc) e

( 10 )

In order to simplify the equations to the form desired, we introduce

dimensionless dependent variables and a small parameter 6 as follows:

A A AAA

6 = 1 + 6 6 A (y) + 8 6 (x,y , z) +

p/p0 = pa (y) + p ( x >y> z ) + •••

A A A AAA

P/P0 = PA (y) + 6 P (x,y , z) + • •

A A A A A A A A

( v , w) = Vo (v[x ,y , z ] + •••, w[x,y,z] + •••)

u U < 1 + 6

2 ua (y) + <$ 2 u(x,y,z) +

The parameter 6 is defined by the relations:

S - Q/p0 CPT0 H

2 V0

H = P0 /P0 g

Vc - (Qg2 /P0 CpT0

) 1/3

14

(ID

( 12 )
Finally, the independent variables are defined in terms of the scale height

and 8 :

x = (H/6 ) x,

AAA

y

= Hy, z = Hz

We also assume that the ambient wind U0 is much larger than Vo by a factor of

order of magnitude 6 . Thus we can introduce a parameter K of order unity in 8

such that

VD = SKUo (14)

The scaling laws implied by the expansion defined in equations (11) -(14) are

consistent with the following physical picture. The atmospheric motion is

nearly but not quite adiabatic. The small excess temperature remaining in the

plume and departures in the ambient atmosphere from neutral stability

(adiabaticity) are responsible. Similarly, the atmospheric winds are nearly

uniform and much larger than the vertical buoyancy induced velocity. However,

since we are interested in downwind dispersal over distances much larger than

the plume rises, the buoyancy effects cannot be neglected. When all these

relations are substituted into the first two of equations (3) and equations

(10), the following dimensionless system results:

<9v dw d logp t v

dy

+

dz

+

dy

dv

dt

-f - dv

+ w

dz

0

dv - dv -

y~ + v-t-- d t dy

+ w

dv

dz

d£_

dt

+ v

86

dy

~d6 WTdz

+

- 86 . V

3y

0

0

(15)

Two new variables have been introduced into equations (15). They are:

t = Kx

y

pA ( y) (y) dy + P ” / Pa

( 16 )

15
Those final substitutions have generated a system of equations very close to

those solved by Baum et.al. [13]. The system is now explicitly two

dimensional and time dependent with suitably scaled distance downwind playing

the role of time. There are two significant differences, which will require

modifications to earlier calculations before quantitative predictions can be

made. First, the ambient stratification as by ©A and pA appear in the

equations in a fundamental way. Second, the enclosure walls built into the

calculations in Ref. [13] must be removed. Still, the equations are close

enough that it is worthwhile to see the kind of results which emerge from a

related enclosure fire computation.

In order to make the calculations equivalent, we consider the problem of a

"thermal" generated in the enclosure. To see why this is necessary consider

the "floor" boundary conditions represented by equations (8) . Since x is now

the time like variable, the Gaussian forms used to represent the velocity and

temperature profiles imply that the vertical velocity and temperature

introduced at the floor of the two dimensional enclosure must be turned on and

off rapidly. Figure 14 shows (potential) temperature contours shortly after

the pulse is turned on. Recalling that the frame of reference is now a plane

sweeping downstream with the ambient wind velocity, Figure 15 shows the plume

just downwind of the fire. It is now bent over and barely connected to the

"ground". Figure 16 shows the initial development of the typical counterrotating vortex pair in the plume as it rises above the datum level much

further downstream. Finally, in Figure 17 the vortex structure is quite

pronounced. The plume structure this distance downstream would probably be

strongly modified by stratification and the presence of plumes generated by

other fires. Some indication of the latter effect might be inferred by

considering this sequence to represent an infinite periodic array of plumes

aligned perpendicular to the wind. However, definitive answers can only come

from calculations based exactly on equations (15) with appropriate boundary

conditions. Future work will focus on this problem.

7 . 0 SUMMARY

An experimental facility was completed to examine the burning conditions of

crude oil in a 1.2 m diameter pool fire configuration. This facility

permitted controlled burning experiments to be conducted under conditions

representative of the radiation- dominated, turbulent flow regime of larger

pool fires that might occur on the open ocean or in pools confined by broken

ice. Tests with three different crude oils, Alberta Sweet, La Rosa, and

Murban were conducted using initial oil depths of 2 mm, 4 mm, 10 mm and 25 mm

floated on a deep water layer.

At oil depths of 10 mm and 25 mm each oil exhibited two distinct burning

stages. The first was associated with a progressive vaporization of the

burning oil layer and the other with more intense, short duration burning in

which the oil surface was churned and splattered by boiling water under the

thin oil layer. For Murban crude oil, the steady burning resulted in energy

release rates of 840 kW/m2 which increased to 1860 kW/m2 during the vigorous

burning before extinction. Residual oil left on the water surface at the end

of natural burning corresponded to a uniform layer depth of 0.6 mm to 1.2 mm.

16
The rate of heat conduction into the oil during burning was estimated to be

less than 20 percent of the incident radiant energy directed at the surface.

Additional tests are planned to characterize the radiation to the oil surface.

Several instrumentation problems must be overcome in order to obtain more

reliable data. This new data will be used in an analysis of the surface

energy balance for the burning crude oil.

The burning of Alberta Sweet crude oil results in a high smoke emission with e about 0.10 (10% conversion to smoke). The smoke has a high elemental carbon

component in excess of 90% resulting in a highly absorbing soot with a

specific extinction coefficient, K£

, of 9.4 m

2 /g. These values are similar to

the values reported last year for Prudhoe Bay crude oil. Over the 900 second

period of burning, the values of both e and Kf

, the specific extinction

coefficient relative to the fuel, increase and also the PAH emission shifts

from smaller to larger structures as the fuel burns. Perhaps all of these

effects are a result of a fractionation of the fuel with the sootier component

burning last.

The primary gaseous product of combustion is C02 with the CO concentration

about a factor of 25 lower than C02

. The emission of NO and N0X are less than

one thousandth the concentration of C02.

Independent analyses of the PAH content of the smoke by the National Bureau of

Standards and Environment Canada showed the same trends and had good overall

agreement for 12 individual PAHs . The PAH content of the smoke was nearly

equal to that in the original oil burned. The PAH content of the smoke was

enriched in the larger species in comparison with the fuel. The concentration

of benzo [ a] pyrene , which is often used as a surrogate for the carcinogenic

effect of PAH, was found to be three times greater in the crude oil smoke per'

gram of fuel consumed compared to the crude oil itself. The concentrations of

the three ring PAHs were found to be very sensitive to the filter collection

temperature. Thus, it is important to use a diluter when sampling the PAHs to

simulate the conditions existing in a rising smoke plume.

Nitrogen containing PAHs have been observed in one of four crude oil smoke

samples at concentrations near the lower limit of detection for the present

analysis. This is a preliminary result obtained by Environment Canada and

additional higher resolution analysis is needed.

An analysis of the dispersal of fire plumes by atmospheric winds was

presented. It was demonstrated that as the plume buoyancy weakens with

altitude and the plume gets bent over by ambient winds, the equations

describing the dispersal process are greatly simplified. Physically, they are

equivalent to studying the two-dimensional but time dependent process by which

a buoyant thermal equilibrates with a stratified atmosphere at rest. Sample

results of a similar process occurring inside an enclosure have been shown.

This approximate model can be used to calculate realistic dispersion of oil

spill combustion generated smoke with moderate sized computing resources.

17
8 . 0 ACKNOWLEDGEMENT

This work was supported under the joint sponsorship of the Minerals Management

Service, U.S. Department of the Interior, Environmental Protection Service,

Environment Canada, and the Office of Research and Development, U.S. Coast

Guard

Special thanks is extended to Mr. Edward Tennyson who was instrumental in

organizing this program of research. Dr. M. F. Fingas was especially helpful

in consultations about the chemistry and analysis of crude oils. The

assistance of Mr. B. Benner and Dr. S. Wise was indispensible in the analysis

for PAH compounds in the crude oil and soot.

The authors also wish to thank the many individuals on the CFR staff involved

with the large scale testing effort among them were Dr. K. M. Tu, Mr. N.

Bryner, Mr. J. S. Steel, and Mr. R. Zile.

9 . 0 REFERENCES

1. Evans, D. , Baum, H. , McCaffrey, B., Mulholland, G., Harkleroad, M. , and

Manders , W. , "Combustion of Oil on Water", NBSIR 86-3420, National

Bureau of Standards, Center for Fire Research, Gaithersburg, MD 20899,

(1986).

2. Huggett, C., Fire and Materials 4, 61 (1980).

3. Bobra, M. A. and Chung, P.T., "A Catalogue of Oil Properties,"

Environment Canada Report No. EE-77, March 1986.

4. Healy, J. J., de Groot, J. J., and Kestin, J., Physica 82C, 392 (1982)

5. Yumoto, T, "Heat Transfer from Flame to Fuel Surface in Large Pool

Fires," Combustion and Flame, 17, 108-110 (1970).

6. Petty, S. E. "Combustion of Crude Oil on Water," Fire Safety Journal, 5,

123-134 (1983).

7. Brosmer, M. A. and Tien, C. L. "Radiative Energy Blockage in Large Pool

Fires," Combustion Science and Technology, 51 . 21-37, 1987.

8. Boyland, E., The Toxicology of Soot, Soot in Combustion Systems and its

Toxic Properties . ed. by J . Lahaye and G. Prado, Plenum Press, New York,

13, 1981.

9. Johnson, R. L. , Shah, J. J., Cary, R. A., and Huntzicker, J. J., An

Automated Thermal -Optical Method for the Analysis of Carbonaceous

Aerosol, in ACS Symposium Series, No. 167, Atmospheric Aerosol:

Source/Air Quality Relationships , ed. by E. S. Macias and P. K. Hopke

1981.

18
10. Wise, S. A., Benner, B. A., Chesler, S. N., Hilpert, L. R. , Vogt, C. R.

and May W. E., Characterization of the Polycyclic Aromatic Hydrocarbons

from Two Standard Reference Material Air Particulate Samples, Anal

Chem. . 58, 3068, (1986).

11. Longwell, J. P., Polycyclic Aromatic Hydrocarbons and Soot from

Practical Combustion Systems, Soot in Combustion Systems and its Toxic

Properties . ed. by J . Lahaye and G. Prado, Plenum Press, New York, 37,

1981.

12. McCaffrey, B.J., "Momentum Implications for Buoyant Diffusion Flames",

Combustion and Flame 52., 149 (1983) .

13. Baum, H.R.

Rehm, R.G., and Mulhplland, G.W., "Computation of Fire

Induced Flow and Smoke Coagulation", Nineteenth Symposium

(International) on Combustion, The Combustion Institute, Pittsburgh, 921

(1982) .

14. Baum, H.R.

and Rehm, R.G., "Calculations of Three Dimensional Buoyant

Plumes in Enclosure", Combustion Science and Tech. 40, 55, (1984).

19
TABLE 1

PROPERTIES OF OILS (TYPICAL DATA)

CRUDE OIL DENSITY

kg/m3 PARAFFINS

PERCENTAGE

AROMATICS

BY WEIGHT

WAX ASPHALTENES

ALBERTA SWEET * 839 84 .12.8 1.8

LA ROSA 911 66.1 23.2 9.9 6.2

MURBAN 824 81.4 16.6 5.7 0.8

Composition analysis provided by Environment Canada

20
Table

2.

Summary

of

Burning

Data

in

1.2m

dia

Pan

0)3

•rHto uo

<d

X

X

vo co i—i ov N CO CO H

CM <J- r- VON

H O'

VO VO Ov CM OO ON

OOO i—o o o o r—I OO o

cdCP

a) pK

Co

•rH '—' CS]

W P E E

Ctf CM \ E •rH W ^ E X X

cti 2

cm o oo in r- i—i i—i vocm i—i Mj- co

idp <fn

O <t CO 4 cm n

XO

cfl X

T3

CD

a> PmCO e e X X

<t- 1—

VO

O CO o in 00 00 co

CO Mi- iP Mi- CO Mj- i m o o CM

CO CO CO Mt Mj- CO CO co CO CO

X *lH Cl) CM

Cfl P P E VO o 00 O' CO CM VO CO CM in OO 2 tfl c \ • . . • • • • • • • • •lH a) !3 l—l <r 00 Ov co CM O n- Ov in O'

T)

O

X CM VD VO VO

m VO 00 Mf CM CO CO

cti X P <D

Cti P E O o O

O o O o o o O o

<D ctf VO r-- VD CO VD Ov Ip VO CO in O' X X & o p" CO 00 CO OO m CM in ip CO X Ip ip i—

1—

rP CM CM CM CM E CD 3 CO E Cti S

•rH a) § o o rP r-. r-- Mt Mi- in

O CO r^-

X l—l CM o rP o ov tP ce in VO CM

cti a) • • • . . . • . • . S cX rP CM CM CM o CM CM CM o CM CO

CDE 0) 2 p

r-H 3

Pm

p

cfl E P 2 CD E X •rH E

x: CD

Cti

H 2

co oo <t

m

nnn

m

ID CO

O (O'

M <t toN

O ID co ID P' CO OO O'

<t

O CM

oo O' ro

<f CO (O

px

OO 00 mJ- VO CM r-. O0 vO OO o •rH X ov co n- CO oo VD CO Mt o CM mJCD • • • • . . . . • • P E: ip 'Cl- CTv Mt iP Mi- Ov CO CM m o

CD CM CM iP

fn CO

Ctf co X CDe E

rH

X E CM inO

m

•rH o iP CM CM in

O

m CM in o o •H iP CM rP XH < < H CO

<3

XH o p cq W X X co rr^ Mf iP CM CO CQ X rP CM CO <1- iP CM

CD

B

OO

O

OX

O o o o < o O o

E-h § 2 2 2 2 < CO < < < < X

XXX L03

25

26.0

931

2.85

2520

32.4

42.2

15.0

0.66
TABLE 3. SUMMARY OF SMOKE EMISSION DATA FOR 60 CM DIAMETER

ALBERTA SWEET CRUDE OIL POOL FIRES

Property

Test H-l

s amp 1 e 1

Test H-l

sample 2

Test H-4

s amp 1 e 1

Test H-4

sample 2 average

dQ/dt, kW 217 172 234 191 204

dm/dt, g/s 5.27 4.40 5.63 4.93 5.06

H, KJ/g 37.4 39.8 41.7 38.8 39.4

€

1 0.076 0.119 0.100 0.110 0.101

£ 2 0.070 0.110 0.089 0.101 0.093

Ks , m

2 /g 9.2 9.3 (6.4) 9.8 9.4

Kf , m

2 /g 0.70 1.10 0.64 1.08 0.88

Property Test C-5 Test C-7 average

dQ/dt, kW 205 203 204

dm/dt, g/s 4.98 5.57 5.28

HKJ/g 41.1 36.3 38.7

e

i 0.087 0.079 0.083

£ 2 0.080 0.079 0.080

Ks , m

2 /g 10.2 10.9 10.6

Kf , m

2 /g 0.88 0.86 0.87

H-l

Legend:

and H-4 refer to identical crude oil burns in which the filter

collection system was heated to about 100 °C.

C-5 and C-7 refer to identical crude oil burns in which the smoke is

cooled to ambient temperature in a sampling dilution system.

dQ/dt - heat release rate of the fuel,

dm/dt - burning rate of the fuel.

H - heat of combustion.

e

1 and e 2 refer to the smoke yield based on a flux method and a carbon

balance method [1], respectively.

Kf and Ks are defined in the section entitled Smoke Emission

Measurements

22
TABLE 4. GASEOUS EMISSION FROM ALBERTA SWEET CRUDE OIL

C-6 C-7 C-6 C-7

Species sm fract

a fracta

co2

• 4604 4906

CO 174 187 0.038 0.038

NO 0.7 0.7 1.6x10" 4 1 . 5x" A

NOx

CM co 1.7 5. 0x10" A 4 . Ox’

a Volume fraction of gas species relative to C02

.

23
TABLE 5. ORGANIC/ELEMENTAL ANALYSIS OF SMOKE FROM

BURNING OF ALBERTA SWEET CRUDE OIL

Sample No.

org. carbon

/xe/ cm2 elem. carbon

ug/cm2 % elem. carbon'

H

b

, blank 3 . 80±0 . 46 0.4110.22

H- 3 , #1 6 . 18±0 . 51 29.2911.66 92

H-3, #2 5.1810.46 17.7111.09 93

H-3, #2 repeat 5.2910.46 19.8611.19 93

C-5, blank 0.7810.24 0.2210.21

C-5, #1 0.9710.25 12.9510.85 99

C-5, #1 repeat 0.8010.24 13.3710.87 100

C-5, #2 2.7610.24 43.0212.35 96

The blank values are subtracted from the sample values in determining

the percent elemental carbon.

H refers to filter heated to about 100 °C and C to filter at near

ambient conditions.

24
TABLE 6 . MEAN PAH CONCENTRATION FOR ALBERTA SWEET CRUDE OIL SMOKE SAMPLES

COLLECTED AT 100°

a

H-2 ,#1 H-2, #2 H-4 , #1 H-4, #2

No

b PAH 4g/gc M&Zg gg/g Mg/g

Acenaphthylene 3 2

Acenaphthene N.D. N.D.

Fluorene 4 3

1 . Phenanthrene 31d 21d

946 58 s 2 . Anthracene N.D. e N.D.

3. Fluoranthene 47 37 213 126

4. Acephenanthrylene 22 22

5. Pyrene 65 49 259 152

6 . Benzo [ ghi

69 65

fluoranthene

7. Cyclopenta [ cd] 24 108

pyrene

8 . Benz [ a ] anthracene 63 87 88 176

9. Chrysene/ 71 87 95 186

Triphenylene

10. Benzo [b , j

, k] 187 351 491 515 ‘ fluoranthene

11 . Benzo [ e ] pyrene 66 106 92 224

12. Benzo [ a] pyrene 113 204 73 189

13. Perylene 19 38 18 52

14. Indeno [ 1 , 2 , 3-cd] 112 219 251 752

pyrene

15. Benzo [ ghi ] perylene 127 235 87 240

Total PAH Conc. f 901 1434 1761 2670

a The samples H-2 analyzed at NBS and H-4 were analyzed by EC.

b Peak identification numbers for Figures 10-13.

c /ig of PAH/g of smoke; uncertainty estimated to be ±10 % of the reported

concentration for samples H-2.

d Concentration calculated using phenanthr ene-d10 as the internal

standard; all other concentrations computed based on 1 -n-butylpyrene as

the internal standard for samples H-2.

Not detected.

Only PAHs common to both analyzes (NBS and EC) are included in the sum.

This number represents the sum of penanthrene and anthracene.

25
TABLE 7. MEAN PAH CONCENTRATION FOR ALBERTA SWEET CRUDE OIL SMOKE SAMPLES

COLLECTED AT AMBIENT TEMPERATURE3

C-5 ,#1 C-5, #2 C-7 ,#1 C-7, #2

No

b PAH mlz UZ/.Z Ag/g

Acenaphthylene 35 59

Acenaphthene N.D. 1.2

Fluorene 126 140

1. Phenanthrene 905 1040

1217® 1223®

2. Anthracene 257 291

3. Fluoranthene 695 725 738 721

4. Acephenanthrylene 384 397

5. Pyrene 903 839 795 779

6. Benzo [ ghi

243 220

fluoranthene

7. Cyclopenta [ cd] 535 538

pyrene

8. Benz [ a] anthracene 217 222 237 223

9. Chrysene/ 215 226 219 217

Triphenyl ene

10. Benzo [b , j ,k] 384 394 421 410

fluoranthene

11. Benzo [ e ] pyrene 122 121 179 173

12. Benzo [ a] pyrene 238 184 206 196

13. Perylene 42 41 45 47

14. Indeno [ 1 , 2 , 3 -cd] 185 188 535 532

pyrene

15. Benzo [ ghi ] perylene 209 206 176 175

Total PAH Conc. d 4372 4186 4768 4696

The samples C-5 were analyzed at the National Bureau of Standards and

the samples C-7 were analyzed by Environment Canada.

Peak identification numbers for Figures 10-13.

/ig of PAH/g of smoke; uncertainty estimated to be ±10% of the reported

concentration for samples C-5.

Only PAHs common to both analyzes (NBS and EC) are included in the Siam.

This number represents the sum of phenanthrene and anthracene.

26
TABLE 8. COMPARISON OF PAH CONTENT OF ALBERTA SWEET

CRUDE OIL AND SMOKE FROM BURNED OIL

No . a PAH

Crude Oil

i±g£g

h

Acenaphthylene 61

Ac enaphthene N.D.

Fluorene 188

1. Phenanthrene

. 296 d

2. Anthracene

3. Fluoranthene 22

4. Acephenanthrylene

5. Pyrene 21

6. Benzo [ ghi

7.

fluoranthene

Cyclopenta [ cd]

8.

pyrene

Benz [ a ] anthracene N.D.

9. Chrysene/ 30

10.

Triphenylene

Benzo [b , j , k] N.D.

11.

fluoranthene

Benzo [ e ] pyrene 21

12. Benzo [ a ] pyrene 5

13. Perylene N.D.

14. Indeno [ 1 , 2 , 3 -cd] N.D.

15.

pyrene

Benzo [ ghi ] perylene N.D.

Smoke

4g/gc

104

29

73

40

84

22

54

22

23

39

12

18

4

19

21

Total Cone, of PAHs 395 448

Peak identification numbers for Figures 10-13.

fig PAH/g crude oil. Analysis performed by Environment Canada.

fig PAH/g of crude oil burned assuming smoke emission factor, e, of 0.10

and PAH emission data from C-5, #2. Analysis performed by NBS

This number represents the sum of penanthrene and anthracene.

27
COLLECTION

FILTERS

6/3 00 X Ul

< in

x < X o

Ui

28

FIGURE

1.

SCHEMATIC

OF

SMOKE

DILUTION

SYSTEM.
External

radiometer

&

29

FIGURE

2.

DIAGRAMMATIC

SKETCH

OF

EXPERIMENTAL

ARRANGEMENT
30
0.14

o

to

o

o

o

to

o

CO

o

o

OJ— O CO <D O — O O O o o 6

Oiw/M) **! A !Pnpuoo |dujj9M!

31

FIGURE

4.

THERMAL

CONDUCTIVITY

OF

CRUDE

OILS
T = 3.0 MIN. NEAR END OF STEADY-STATE BURNING PERIOD

T = 4.0 MIN. VIGOROUS BURNING PERIOD

FIGURE 5. BURN SEQUENCE FOR 10 MM THICK LAYER OF LA ROSA. CRUDE OIL

32
1000

t

I

I

I E E E

E E E O fcO

01

m CM

Oc ’3*innf«3dR31

FIGURE

6.

FLAME

PLUME

TEMPERATURE

FOR

MURBAN

CRUDE

AT

DIFFERENT

LAYER

THICKNESSES.
10mm 25mm

34

FIGURE

7.

ENERGY

RELEASE

RATE

FOR

MURBAN

CRUDE

AT

DIFFERENT

LAYER

THICKNESS
tOmm EE

u->

w

PSUz<se

PSoz<

&-

u.ogHZwu*u<ec

u:

u:zo

t—

t-<e

u:c

csou

u:

es

fcJ PSOu 2 /p ’3DHyiorsa

35

AT

DIFFERENT

LAYER

THICKNESSES
36

FIGURE

9.

GAS

CHROMATOGRAM

OF

TYPICAL

BLANK

SAMPLE

WITH

I.S.

INDICATING

INTERNAL

STANDARD

AND

IMP

INDICATING

AN

IMPURITY.
FID

- O

in

tu

2

37

FIGURE

1ft.

GAS

CHROMATOGRAM

OF

THE

FIRST

SMOKE

SAMPLE

COLLECTED

AT

100*C

(II2,#1).

THE

l-AIIS

ASSOCIATED

WITH

THE

PEAKS

ARE

IDENTIFIED

IN

TABLE

f,
FID

FIGURE

11*

GAS

CHROMATOGRAM

OF

THE

SECOND

SMOKE

SAMPLE

COLLECTED

AT

100* C

(H^

.. av '
Phananrhran#

o

in

39

A

FIGURE

12.

GAS

CHROMATOGRAM

OF

SMOKE

SAMPLE

COLLECTED

AT

AMBIENT

TEMPERATURE
e /. n

FIGURE

13

.

GAS

CHROMATOGRAM

OF

SECOND

SMOKE

SAMPLE

COLLECTED

AT

AMBIENT

TEMPERATURE

(C-5,#2).
TEMPERATURE

C0NT0URS

ATT=

2.000

41

FIGURE

14.

TFJMFERATURE

CONTOURS

AT

FRONT

OF

WIND

BLOWN

PLUME

USING

TRANSIENT

ENCLOSURE

FLOW

ANALOGY.
TEMPERATURE

C0NT0URS

ATT=

3.950

42

FIGURE

15.

TEMPERATURE

CONTOURS

JUST

DOWNWIND

OF

FIRE

USINC

TRANSIENT

ENCLOSURE

FLOW

ANALOGY.
TEMPERATURE

C0NT0URS

ATT=

4.950

43

FIGURE

16.

TEMPERATURE

CONTOURS

AT

POINT

OF

VORTEX

PAIR

FORMATION

USING

TRANSIENT

ENCLOSURE

FLOW

ANALOGY.
TEMPERRTURE

C0NT0URS

fil T=

5.950

44

FIGURE

17.

FAR

DOWNWIND

TEMPERATURE

CONTOURS

USING

TRANSIENT

ENCLOSURE

FLOW

ANALOCY.
U.S. DEPT. OP COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date

BIBLIOGRAPHIC DATA

SHEET (See instructions)

REPORT NO.

NBS IR- 88/ 3 82

September 1988

4. TITLE AND SUBTITLE

Environmental Effects of Oil Spill Combustion

5. AUTHOR(S)

f)_ G. Mill Holland, T). Cross, and Baum

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

8 . Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Minerals Management Service

Department of the Interior

Reston, VA 22091

10. SUPPLEMENTARY NOTES

~~1 Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bl iography or literature survey, mention it here)

Experimentation and analysis have been performed to quantify the combustion of crude

oil on water. The burning behavior of three crude oils — ALBERTA SWEET, LA ROSE,

and LTURBAN, were studied using 1.2 m diameter pool burns. In smaller 0.6 m diameter

pool fires using ALBERTA SWEET, combustion products were collected for extensive

chemical analysis. This analysis showed that about ]0% of the crude oil was converted

to smoke in the combustion process. The CO concentration was a factor of 25 lower

than the primary' gaseous product CO^, and the emission of NO and NO were less than

one thousandth the concentration of CO^. The PAH content of the smoke was enriched

in the larger molecular weight species in comparison with the original fuel. A

methodology was developed with which the down wind dispersal of smoke generated by one

or more oil spill fires in close proximity may be predicted. Initial results that

demonstrate the capability of the analysis are presented.

12. KEY WORDS (Six to twelve entries ; alphabetical order; capitalize only proper names; and separate key words by semicolon s) crude oil; oilspills; PAH; pool fires; smoke; fire plumes

13. AVAILABILITY

jv j Unlimited

|

i For Official Distribution. Do Not Release to NTIS

| | Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

fy 1 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

51

15. Price

$13.95

USCOMM-DC 6043-P80
'

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'

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