PARTICULATE EMISSION FACTORS AND
FEASIBILITY OF EMISSION CONTROLS FOR
SHIPLOADING OPERATIONS AT
PORTLAND, OREGON GRAIN TERMINALS
VOLUME I
Final Report
GCA/TECHNOLOGY DIVISION
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GCA-TR-7 ww—w v -*- /
GRAIN TERMINAL CONTROL STUDY
Contract No. 68-01-4143
Technical Service Area 1
Task Order Nos. 24 and 47
EPA Project Officer
Mr. John R. Busik
Division of Stationary Source
Enforcement
401 M Street, S.W.
Washington, D.C. 20460
EPA Task Officer
Mr. Norman Edmisten
U.S. EPA,
Oregon Operations Office
522 S.W. Fifth St.
Portland, Oregon 97204
PARTICULATE EMISSION FACTORS AND
FEASIBILITY OF EMISSION CONTROLS FOR
SHIPLOADING OPERATIONS AT
PORTLAND, OREGON GRAIN TERMINALS
VOLUME I
Final Report
by
William Battye
Robert R. Hall
GCA CORPORATION
GCA/TECHNOLOGY DIVISION
Bedford, Massachusetts
June 1979
U.S. ENVIRONMENTAL PROTECTION AGENCY
Division of Stationary Source Enforcement
Washington, D.C. 20460
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DISCLAIMER
This Final Report was prepared for the U.S. Environmental Protection
Agency by CCA Corporation, GCA/Technology Division, Burlington Road, Bedford,
Massachusetts 01730 in fulfillment of Contract No. 68-01-4143, Technical Ser-
vice Area 1, Task Order Nos. 24 and 27. The opinions, findings, and conclu-
sions expressed are those of the authors and not necessarily those of the
Environmental Protection Agency. Mention of company or product names is not
to be considered as an endorsement by the Environmental Protection Agency.
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ABSTRACT
Observations of shiploading operations at nine grain terminals in Portland,
Oregon; Seattle and Tacoma, Washington; and Duluth, Minnesota are discussed.
Also, a preliminary evaluation of the compliance status and/or feasibility of
compliance of shiploading operations at the Portland, Oregon elevators with
State visible emissions regulations is presented. Estimates of particulate
emission factors for shiploading operations at the Portland elevators have been
developed through a measurement program.
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iv
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CONTENTS
Abstract iii
Figures vi
Tables vii
Acknowledgment viii
1. Summary and Conclusions 1
Summary 1
Conclusions 3
2. Background 5
Loading Operations 5
Visible Emissions Regulations 7
Emission Control Technology 7
3. Site Inspections and Measurements 14
Introduction 14
Site Descriptions and Visual Observations 16
Emission Measurements 25
Emission Factors 38
4. Technical Feasibility of Meeting Opacity Regulations at Portland
Grain Terminals 42
Cargill 42
Columbia 42
Bunge and Louis Dreyfus 43
References t 46
Appendices
A. Conversion Factors for Selected Metric and British Units 48
v
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FIGURES
Number Page
1 Schematic of bulk carrier, tanker and 'tween-decker
grain loading 6
2 Tent and suction dust control system 8
3 Dead-box in use at Cargill in Portland 10
4 Submerged loader in use at Cargill in Seattle 11
5 Grain loading operations at the Louis Dreyfus elevator 18
6 Grain-loading operations at the Cargill elevator 20
7 Uncontrolled shiploading operations at the Columbia elevator. . 21
8 Bullet or dead-box control system at Continental grain in
Tacoma 22
9 Cargill submerged loading facility in Seattle 2b
10 Size distribution of particulate emissions from shiploading,
primarily topping-off 29
11 Placement of measuring equipment at the Bunge and Dreyfus grain
loading terminals 31
12 Placement of measuring equipment at the Cargill grain-loading
terminal 34
13 Measurements made at the Columbia elevator 36
vi
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TABLES
Number Page
1 Background Information on Shiploading Operations 15
2 Results of Andersen Impactor Measurements in Plumes Generated
by Grain Loading 28
3 Particulate Concentrations in Selected Size Ranges 30
h Measured Emission Rates for Grain Loading 33
5 Respirable Dust Concentrations Measured at the Columbia
Elevator 37
6 Emission Factors for Shiploading 39
7 Average Particulate Emission Factors 41
vii
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ACKNOWLEDGEMENT
The authors wish Co sincerely acknowledge the assistance and advice of
Mr. Norman Edmisten, EPA Task Officer for this project. Also the assistance
received from Mr. Jim Close and Mr. Thomas Bispham of the Oregon Department
of Environmental Quality was appreciated. The cooperation of the stevedores
and the grain terminal operators was most important to this program and
their efforts are acknowledged.
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SECTION 1
SUMMARY AND CONCLUSIONS
SUMMARY
There are four terminal grain elevators in Portland, Oregon operated by
the Bunge, Louis Dreyfus, Cargill and Columbia Grain companies.* Shiploading
operations at these four terminals were observed in order to evaluate the
compliance status and/or feasibility of compliance of the operations with
Oregon state visible emission regulations. Dust concentration measurements
were made at these facilities so that estimates of the particulate emission
factors from shiploading operations could be made.
In addition to the four Portland terminals, shiploading operations were
observed at the Cargill terminal in Seattle, Washington; the Continental
Grain and United Grain terminals in Tacoma, Washington; and the International
Multifoods and General Mills terminals in Duluth, Minnesota. The Cargill-Seattle
and Continental Grain - Tacoma terminals were visited as examples of terminals
with well-controlled shiploading operations. They use submerged loading and
dead-box control systems, respectively. The United Grain Terminal in Tacoma
uses a tent control system. Measurements of dust concentrations under the
tents at United Grain, Bunge and Dreyfus were made in order to determine
whether the use of aspirated tents to contain and collect dust would pose an
explosion hazard (see reference 1 for a discussion of this work). Finally,
the Duluth terminals were visited prior to the Portland observations in order
to determine what type of measurements could be made- to estimate particulate
emission factors from shiploading.
The Cargill terminal in Portland uses a dead box system to control partic-
ulate emissions from bulk carrier loading. When the dead boxes were well-
operated, emissions were limited to 10 percent opacity and estimated emission
factors for total particulates and suspendable particulates (< 30 pm aerodynamic
diameter) were 0.3 g/1 (0.0006 lb/ton)"'" and 0.2 g/t (0.0004 lb/ton). When the
dead boxes were not properly operated, that is when they were held too high
above grain level or allowed to swing excessively, visible emissions with an
The Columbia Grain terminal was operated by Cook Industries during the sampling
activities discussed in this report.
Conversion factors for the metric and British units used in this report are
presented In Appendix A.
1
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average opacity of 40 percent were observed and the estimated emission factors
weri; 2.8 g/t (0.0056 lb/ton) and 2.4 g/t (0.0048 lb/ton) for total and suspen-
dable particulates respectively. The Oregon state visible emissions regulations
for the Portland area state that there should be no visible emissions with
opacities greater than 20 percent. It appears, that it is possible for the
state opacity regulations to be met at the Cargill terminal during bulk-carrier
loading if the control systems are properly operated. In the near future,
Cargill may be modifying a trimming machine for use during tween-decker loading.
This Ls expected to allow compliance with the standard during tween-decker
loading ae well as bulk-carrier loading.
The Columbia terminal in Portland, at the time of this study had no partic-
ulate emission control system for shiploading and was, therefore, not capable
of complying with the Oregon state visible emissions standards. Columbia
Grain is continuing installation of a dead-box system begun by Cook. This
system should enable the Columbia terminal to comply with the regulations during
bulk-carrier loading. Columbia is also considering altering a trimming machine
so that emissions can be controlled during tween-decker loading. Whether this
is done will depend on the number of tween-deckers loaded by Columbia in the
near future.
Both the Bunge and Louis Dreyfus terminals at Portland have available
tents with aspiration systems to control dust emissions from shiploading.
These systems are not presently in use because stevedores, concerned about
grain elevator explosions, have refused to use tent control systems. Measure-
ments made at the United Grain, Bunge and Louis Dreyfus terminals, indicate
that the concentrations of dust under tents during shiploading are well below
minimum explosive limits for grain dust cited in literature.1
DurLng shiploading observations at Bunge and Louis Dreyfus, the tent
control systems were in use. Such systems are generally used during bulk-
loading of bulk-carriers, but not during topping-off of bulk-carriers, or during
loading of tween-deckers. During bulk-loading when the tents were in use, at
Bunge and Louis Dreyfus, there were no visible emissions. During topping-off,
emissions with opacities in excess of 50 percent were observed. Measurements
made at the Bunge, Louis Dreyfus and Columbia terminals were used to estimate
emission factors for uncontrolled shiploading or topping-off. The average
estimated emission factors are 55 g/t (0.11 lb/ton) for total particulate and
40 g/t (0.08 lb/ton) for suspendable particulates.
Use of the existing tent control systems at the Bunge and Louis Dreyfus
terminals during bulk-loading of bulk-carriers would reduce emission factors
for total particulates from 55 g/t (0.11 lb/ton) to 14 g/t (0.026 lb/ton) if
topping-off were started when the top of the pile of grain was within 4 feet
of the top of the hold and to 8 g/t (0.016 lb/ton) if topping-off were delayed,
as it should be, until the grain reached the top of the hold. Suspendable dust
emissions comprise about 70 percent of the total particulate emissions. The
terminals would still be in violation of the state visible emission standards
during topping-off and tween-decker loading because tents cannot be used in
these operations. Although emissions from topping-off could be reduced by
holding the loading spouts closer to the grain level, opacity would probably
still exceed 20 percent.
2
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CONCLUSIONS
Properly operated dead-box control systems used to load bulk-carriers
can achieve compliance with Oregon's 20 percent opacity regulation during all
phases of bulk-carrier loading. Proper operation requires that the stevedores
maintain a distance of less than 15 to 30 cm (6 to 12 in.) between the grain
spout and the surface of the pile. The above specification can be achieved by
reasonable attention to the loading generation. Cargill and Columbia can
therefore comply with Oregons opacity regulation during bulk-loading.
Most ships used to handle grain are bulk-carriers. Discussions during
this study indicated that Cargill did not load any tween-deckers or tankers
during the past year (1977). Columbia does not normally load tankers but does
ship 2 to 4 percent of its grain in tween-deckers. The loading of tween-
deckers was not addressed in depth in this study. It appears that dead-box
control systems can only be used to control .emissions during loading of
bulk-carriers. Discussions with Cargill indicated that it may be possible
to modify trimming machines to reduce emissions during the loading of
twecn-deckers.
Tent control systems, as used at Bunge and Louis Dreyfus eliminate visible
emissions during the bulk loading share of loading a bulk-carrier. Bunge and
Louis Dreyfus can therefore comply with Oregon opacity regulation during the
bulk-loading phase. During topping-off, the loading spout must be moved and
the pattern of filling in the hold must be observed. Tent systems can not
be used during this final phase of loading a bulk-carrier. The amount of
grain loaded during the topping-off phase should be minimized in order to
reduce emissions at minimal costs. A pile of grain in a hold typically assumes
a cone shape as it is loaded. Topping-off is sometimes defined as the last
A feet of loading. However, this definition is not precise as it ignores
the shape of the grain pile. It is reasonable to maintain the tent control
system until the top of the cone of grain reaches the top of the hold.
Adoption of this procedure will reduce emissions with minimal, if any,
cost impact. During topping-off emissions can be minimized by holding the
spout as close to the grain as feasible.
Burge and Louis Dreyfus can not control emissions from loading tween-
deckers with the current control systems. However, these facilities only ship
about 2 to 3 percent of their grain in tween-deckers, tankers are not used
to any significant extent.
The only methods which presently enable terminals to reduce visible
emissions to less than 20 percent opacity during all phases of bulk-carrier
shipload Ing are dead-box systems and submerged loading systems. Retrofitting
of dead-box systems to the Bunge and Louis Dreyfus terminals would require
major modifications to the shdploading galleries at the terminals at costs on
the order of $5,000,000. Amortized over 15 years at 10 percent interest, these
costs would amount to about $700,000 per year, which would be about $0.70 per
metric ton of grain loaded, or 1.9 cents per bushel. The cost of emission
~
Assuming that 1 million tons of grain are loaded per year.
3
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control appears high relative to the profit of terminal grain elevators which
is only about 2.1 cents per bushel. It should also be noted that control costs
of 1.9 cents a bushel are small compared to the selling price of grain which is
$3 to $4 per bushel. However, the ability of terminal owners to raise prices
to cover increased costs and maintain profit margins has not been evaluated in
thiB study.
If a submerged loading system could be retrofitted to Bunge and Louis
Dreyfus wLthout major gallery modifications, the cost would be on the order
of $100,000, which, amortized over 15 years amounts to about $14,000 per
year. This is about 0.14 cents per ton loaded or 0.038 cents per bushel.
If, on the other hand, major gallery modifications are necessary as they
probably would be, the cost could be similar to retrofitting dead-box control
systems.
4
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-GRAIN
-GRAIN
HATCH
r
,421
u"i
-;r
. - -V ;
BULK CARRIER
HAROHAT —i
BUTTERWORTH
7
u!Vl_ 3 c.-i-l
TANKER
r
GRAIN
tr-x-
t-r
'TWEEN-DECKER
(NOT DRAWN TO SCALE)
Figure 1. Schematic of bulk carrier, tanker and 'tween-decker grain loading.
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The holds of a tween-decker contain horizontal intermediate decks (see
Figure 1). In the loading of a tween-decker, special care must.be taken to
fill beneath these decks to prevent listing of the ship at sea. Devices
(commonly called conveyors, slingers, trimmers, slides and other terms) to
throw the grain into the corners of the hold are necessary. In addition,
men must get into the hold to operate the trimming device. More dust is re-
ported to be generated in the loading of tween-deckers than in the loading
of bulk carriers, because of the use of conveyors and slides.
Tankers are designed to carry liquid, but are sometimes used for grain.
The holds may contain vertical bulkheads, and generally have small hold
openings. These often necessitate the use of funnels to load the holds.^
The Use of Tween-Deckers
Tween-deckers are older ships which are no longer built, having been
replaced by more modern bulk carriers. Recent figures show that tween-deckers
account for approximately 8 percent of the total number of ships loaded at
Portland facilities.3>11 On the average, tween-decker cargo capacity is approxi-
mately 50 percent less than that of a bulk carrier. Thus, approximately 4 per-
cent of the grain shipped from Portland terminals is shipped aboard tween-
deckers. However, this figure is an average and varies depending on the nature
of export trading. Public Law 664 "The Cargo Preference Act" states that when
exporting to foreign nations without provisions for reimbursement 50 percent
of the gross tonnage of equipment, materials or commodities shall be shipped
on United States-flag commercial vessels. (See Appendix B). As a result,
during export programs affected by this law, many tween-deckers are put into
service to meet the 50 percent requirement. In recent years tween-decker load-
ing at Portland terminals has accounted for as high as 18 percent of the total
number of ships loaded over a 6-month period.
Eventually the older tween-decker fleet will be diminished as each ship
Is permanently taken out of service. However, the number of tween-deckers
loaded at Portland facilities is not expected to change in the immediate
future. Grain terminal operators who were interviewed felt that the use of
tween-deckers will remain at its current level for several years.
VISIBLE EMISSIONS REGULATIONS
Visible emissions regulations vary from state to state. The general
Oregon State regulation for visible emissions states that the opacity of
emission must not exceed 40 percent for more than 3 minutes of any hour. A
much more stringent state regulation applies to "special control areas" in
the state, such as the City of Portland and the Northwest Regional Area of
Oregon. Thds regulation states that the opacity of visible emissions must
not exceed 20 percent for more than 30 seconds in any hour (Oregon Adminis-
trative Rule 340-28-070).5 The grain terminals in the Portland area are
subject to this latter regulation.
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EMISSION CONTROL TECHNOLOGY
Uncontrolled particulate emissions from shiploading at grain terminals
generally have opacities which average over 30 percent with short-term
(6 minute averages) often exceeding 40 percent. Control of these emissions
1b complicated by the fact that the deck level of a ship will vary with the
tide or river stage, the type of ship, and the trim of the ship. Three types
of control systems are presently used to control shiploading emissions:
aspirated tent systems, "dead-box" systems, and submerged loading systems.
Aspirated Tent Systems
In tent control, the emission of dust generated by grain falling into
a hold is prevented by covering the top of the hold with one or several tar-
paulin^) or tent(s) (Figure 2). Grain is poured through a small hole in the
tent at a rate of about 1,000 t/hr. Dust laden air is drawn from under the
tent to a control device, usually a fabric filter, through one or more as-
piration hoses. These can be attached to the side of the loading spout, or
inserted under the side of the tent. The total aspiration rate from a hold
ranges up to 280 m3/min (10,000 cfra). Tent systems can be used with either
vertical, or slanted loading spouts, but the spouts must be capable of tele-
scoping by about 6 meters (20 feet) in length so that they can reach the hold
opening level regardless of the tide stage, or the trim of the ship.
Tent control systems, when properly used, completely eliminate visible
emissions during the bulk loading phase, however, they are not used in all
circumatances. During topping-off, the tents are removed so that the loading
spouts can be moved, and so that the operators of the loading spouts can make
sure that the grain is properly distributed and the hold is completely filled.
Also, tents apparently cannot be used when tween-deckers are being loaded, as
men must remain inside the hold.6*8
In early 1978, the use of tents generated concern among Portland area
stevedores, as they suggested that an explosion hazard could be caused by the
dust concentrations in tent controlled ship holds. .GCA conducted tests to
determine whether dust concentrations approached or exceeded the lower explo-
sive limit.9 It was determined that the dust levels are well below the lower
explosive limit of 40 g/m3 for wheat dust. Average dust concentrations over
5 to 20 minute sampling intervals were 0.40 g/m3 with a maximum value of
1.1 g/m3. Graphical plots on log-probability paper of the distribution mea-
sured and estimated dust concentrations indicated an insignificant (less than
1 chance in 10,000) chance of exceeding about 5 g/m as either a 1- or 10-
minute average. Tents are currently being used by Portland area shiploading
facilities after resolving the question of an explosive hazard.
The major capital cost of retrofitting tent control to an existing facil-
ity would be the cost of the aspiration and fabric filtration systems. This
cost would be about $30,000 dollars/loading leg.10
7
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oj
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Dead-Box
A more versatile method of controlling shiploading emissions is the use
of a "dead-box" (Figure 3). Grain is dropped through a vertical chute into a
dead-box, from which it is allowed to fall a short distance into the hold.
Typical grain flow rates for dead-box systems range from 1,000 to 2,000 t/hr.
The dead-box greatly reduces the velocity of grain which falls into it, and
thus reduces the amount of dust generated at the impact site of the grain in
the hold. Dust generated as the grain drops through the chute, and upon im-
pact of the grain with the baffles in the dead-box is drawn from the top of
the box to a fabric filtration system.
A dead-box should be suspended 15 to 30 cm (6 to 12 in.) above.the grain
level in the hold, because dead-box performance deteriorates rapidly as height
increases. The distance to the grain level varies with the depth of the ship,
water level around the ship and the amount of grain in the hold. In order to
hold the dead-box near the grain during all phases of loading, the telescoping
range of the loading chute must be about 12 meters (40 feet). >12 Dead-box
control can be used to reduce emissions during topping-off as well as during
bulk-loading. It is also expected to reduce emissions from tween-decker
loading. Some dust emission would, however, be expected from the conveyors
or slides used to throw grain to the sides of the holds.
The cost of retrofitting a dead-box control system to an existing facility
would be much higher than that of retrofitting a tent system. A dead-box sys-
tem would generally require major modifications to the loading equipment. A
new gallery would almost certainly be needed to support the additional weight
of the dead-boxes. Major modifications to the dock which supports the gallery
might also be necessary. The total cost would vary from elevator to elevator,
depending on the gallery and dock in use at the elevator in question. The
consensus of opinion of grain elevator owners and operators and equipment sup-
pliers is that a cost estimate of $1 million per loading leg would not be
unreasonable.
Submerged Loading
A submerged loading technique for controlling dust emissions from ship-
loading was developed at the Cargill terminal in Seattle, Washington. The
bottom of the loading spout is actually buried below the grain level in the
hold (Figure 4). Grain falling down the chute has sufficient kinetic energy
to push its way out of the bottom of the chute. Dust generated as the grain
falls down the spout and when it hits the grain in the hold is removed through
a port about 3 meters (10 feet) from the bottom of the spout. Dust laden air
is drawn through a pipe attached to the loading spout to a fabric filtration
system.
The grain loading rate used with this system is generally 1,500 tons/hr,
and the aspiration rate is about 325 m3/min (12,000 cfm). The grain spouts are
about 30 meters (90 feet) long, and can telescope by about 12 meters (40 feet) ,
so that the top of the spout can almost always reach the grain level in the
hold. The tip is generally kept buried 15 to 30 cm (6 to 12 in.) under the
grain level. All of the movement of the grain spout is controlled by motors
9
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GRAIN
(NOT DRAWN TO SCALE)
FLgure 3. Dead-box in use at Cargill in Portland.
10
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Figure 4. Submerged loader in use at Cargill in Seattle.
11
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ft
whicli can move the spout even when it is submerged. A Roto-Bin-Dicator
sensor is located near the bottom of the leg, and shuts off the grain conveyors
to the leg when the leg becomes clogged. This instrument is an electro-
mechanical device consisting of a pressure sensitive diaphragm that actuates
an electrical circuit when the pressure created by the grain exceeds a pre-
set level.
The Cargill-Seattle control system can be used either with the grain spout
tip slightly submerged, or with the tip slightly above grain level. If the
tip is kept within 15 to 30 cm (6 to 12 in.) above the grain level, the visible
emissions should remain below the 20 percent opacity level. If the spout is
kept buried by 15 to 3$ cm, visible emissions are completely eliminated.13
The grain spout should*be kept buried, but should not be allowed to clog. When
the spout clogs, it must be lifted out of the grain, causing visible emissions.
During topping-off, the spout must be moved slowly, to prevent the tip from
surfacing. The submerged loading system is effective both during bulk-loading
and topping-off of bulk carriers. For tween-decker loading, the Cargill-Seattle
terminal has a trimmer which can be attached to the aspiration tube on the
grain spout, so that trimmer dust emissions during tween-decker loading can
also be reduced. 1
The capital cost of retrofitting a submerged loading system to an existing
facility would depend on the loading spouts, gallery, dock and aspiration sys-
tem in use at the facility In question. Such a retrofit would necessitate the
attachment of telescoping aspiration tubes to the loading spouts, and would
probably require additional telescoping capabilities for the spouts. Submerged
loading would require a spout telescoping capability of 12 meters (40 feet),
whereas spouts at most terminals can only be extended by about 6 meters (20
feet). From conversations with elevator operators and manufacturers of air
pollution control equipment for grain elevators,*4a rough estimate of the
cost of such additions has been obtained. The cost would be on the order of
$20,000 per leg. If there is no existing aspiration system at the facility
in question, or if the existing system is not capable of handling the extra
load of a submerged loading system, the cost would be much higher. Also, gal-
leries at most terminals were not designed to handle the additional weight and
torque of aspiration tubes and additional telescoping sections. Thus, instal-
lation of a control system similar to that at Cargill-Seattle may require re-
furbishing of the gallery, and perhaps even the loading dock. The cost of
such work would probably approach the cost of retrofitting dead-box control,
about $1 million loading spout.
Comparison of Tents, Dead-Boxes and Submerged Loading Systems
Tents with aspiration are inexpensive to retrofit relative to the other
two control technologies. They are very effective during bulk loading; com-
pletely eliminating visible emissions with practically no operator attention.
However, tents do not control emissions during topping-off or tween-decker
loadings. Also tents do require additional work and time to set up before
Binidicator - 800-521-6361, P.O. Box 9, 1915 Dove St., Port Huron, Michigan
48060
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loading can be started. Setup time can be expected to decrease significantly
as stevedores gain experience in use of the tent. High winds can also cause
problems with tent control systems but this is a very infrequent problem in
the Portland area.
Dead-box control systems require special galleries with sufficient height
and strength to handle the loading spouts and provide adequate manueverability.
These systems operate in a vertical loading mode and the heavy spouts must be
moved over the ship. Telescoping capability to reach nearly to the bottom of
the ship hold is required. Dead-boxes, as a retrofit control system, are
much more expensive than tents with aspiration. From an environmental view-
point the advantage is that dead-boxes can control emissions during all phases
of bulk carrier loading. They require careful operator attention to keep the
spout near the grain level and thus reduce emissions to below 20 percent
opacity. No special setup time or effort is required to initiate loading.
Typically, during bulk loading, some visible emissions may be present. Dead-
box systems do not control emissions from tween-deckers unless the trimming
device is modified so it can be connected to the aspiration system.
The costs of retrofit submerged loading systems are similar to dead-box
systems when major gallery modifications are required. These slanted spout
systems do not impose as great a demand on the gallery as a dead-box. There
may be cases where submerged loading retrofit costs could be much less than
dead-box costs. In fact, the submerged loading system in Seattle was orig-
inally designed to operate close to the grain pile, not submerged. No modi-
fications were required to use submerged loading at the Seattle terminal.
Other advantages and disadvantages of submerged loading are similar to dead-
box systems.
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SECTION 3
SITE INSPECTIONS AND MEASUREMENTS
INTRODUCTION
The objectives of this project were to measure the particulate emission
factors for shiploading operations at the four Portland, Oregon grain terminals
and to determine the feasibility of controlling these emissions to meet the
Oregon state visible emissions limit of 20 percent opacity. All four Portland
terminals frequently have particulate emissions whose opacities exceed 20
percent. The Portland terminals are run by the Bunge, Louis Dreyfus, Cargill
and Columbia Grain companies. Bunge and Louis Dreyfus have tents with aspira-
tion systems to control shiploading emissions, while Cargill has a dead-box
control system, and Columbia is in the process of installing a dead-box. The
Bunge and Louis Dreyfus terminals are located on the Willamette River in down-
town Portland, while the Cargill and Columbia terminals are located 9 to 12
miles north of the city center.
In November 1977 the General Mills and International Multifoods grain
elevators in Duluth, Minnesota were visited in order to obtain background
information on shiploading operations at grain elevators, and to determine what
measurements could be made to estimate dust emission factors. The four Port-
land terminals were visited in January 1978. The opacities of visible dust
emissions were observed, and measurements of dust levels downwind of ship-
loading equipment were made. Results of these measurements have been used to
estimate emission factors for the elevators. Two elevators in the State of
Washington - Cargill in Seattle, and Continental in Tacoma - were also visited
in January 1978 as examples of well-controlled shiploading facilities.
Background information on shiploading and on particulate emission control
equLpment for shiploading was provided by representatives of each of the nine
grain elevators visited by GCA personnel. This information is summarized in
Table 1. The total amount of grain loaded at the four Portland sites is about
4 million tons (long tons or metric tons)/year. The average ship loaded has
a graLn capacity of about 18,000 metric tons. About 5 percent of the ships
loaded are tween-deckers but, because of their small capacity, they only account
for about 2 percent of the grain loaded. Few, if any, tankers are used to
carry grain in Portland.
The Portland grain elevators load wheat almost exclusively. The grain is
generally transported to the elevators by train from eastern Washington or
Idaho. The wheat shipping business depends on export demand but the January
to April period usually represents 50 percent of the annual shipments.
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TABLE 1. BACKGROUND INFORMATION ON SHIP LOADING OPERATIONS
Co zp2r.v
Location
Average
sni: size
C10CG :}
Percent of
tveer-
deckers
Percent of
cankers
Grain
loacinc
rate
(r -'hr)
Tcooinc
or: race
(c/hr)
Tveen-
cecke r
_oacinz
race fc'hr)
Tveen-
dec.
-------
SITE DESCRIPTIONS AND VISUAL OBSERVATIONS
Portland Facilities
Bunge—
The Bunge terminal was inspected 7 January 1978, in September 1978 and
again in March 1979. During the first inspection, a 15,000 metric ton capacity
bulk-carrier was being filled with wheat. Messrs. J.' Faherty and R. Palmquist
described shiploading operations and particulate emission control equipment.
The Bunge facility handles wheat exclusively and loads about 98 percent of
this wheat to bulk-carriers. The remainder is loaded to tween-deckers.
The loading chutes at Bunge are slanted and are about 15 m (50 ft) long
with the capacity to telescope in length about 6 m (20 ft). They can generally
reach below the hold cover level during bulk-loading but sometimes cannot reach
the grain level during topping-off, because at this time the ship is low in
the water. Although there are several chutes at the facility, only one is
usually used at a time. The loading rate is about 1,200 t (long tons or
metric tons)/hr during bulk-loading, 600 t/hr for topping-off, and 120 t/hr
for tween-decker loading.
A tent made of light weight plastic is available to control particulate
emissions from bulk-loading at the Bunge terminal, but it is presently not
in use for reasons mentioned earlier. The tent has a collar in its center
through which the loading spout can be inserted. It is generally tied down
at the edges of the hold. The associated aspiration system draws air from
under the tent through flexible hoses to a manifold system connected to a fan
and a fabric filter. The fan-fabric filter system were designed to handle
880 m3/min (31,000 acfm) but the flexible hoses apparently limit the amount
of air that can be withdrawn from a single hold. Only two hoses are capable
of reaching any single hold and reportedly about five hoses must be left open
to prevent collapse of the hoses in use. The actual ventilation rate applied
to a hold varies depending on the number of hours in the hold, the number of
hoses left open and the position of the hoses relative to the fan. With one
hose in the hold, the aspiration rate is typically 110 - 140 m3/min (4,000 -
5,000 acfm).
During bulk-loading the tent aspiration system completely eliminated
visible emissions. Without aspiration the tent tended to inflate and some
visible emissions were evident at the sides of the tent. These visible
emissions are minor and variable; they may or may not exceed the 20 percent
opacity limit. The ventilation rate of 110 - 140 m3/min (4,000 - 5,000 acfm)
was adequate to eliminate visible emissions during bulk-loading.
During uncontrolled loading and topping-off opacities up to 60 percent
were observed. A formal visible emissions evaluations (EPA Method 9) was
conducted by CCA on September 18, 1978.Nine sets of 6 minute readings at
Bunge indicated an average opacity of 48 percent with individual 6 minute
readings ranging from 30 to 60 percent. A tween-decker was being loaded
during the above observations but informal observations of bulk-carrier
loading indicated similarily high opacities.
16
-------
Louis Dreyfus—
The Louis Dreyfus facility in Portland was visited 9 January 1978, in
September 1978 and in March 1979, and Messrs. L. Harper and D. Guthrie described
shiploading operations. Like the Bunge terminal, the Dreyfus elevator handles
mostly wheat and loads mostly bulk-carriers. About 2 percent of the grain
handled i8 loaded to tween-deckers, and an insignificant amount is loaded to
tankers. During the January visit, a 35,000 metric ton bulk-carrier was being
loaded with wheat.
The facility has several slanted loading spouts of which one is used at
a time. The chutes are about 15 meters (50 feet) long and can telescope about
6 meters (20 feet). The loading rate is 1,000 t/hr during bulk loading, and
250 to 500 t/hr during topping-off or tween-decker loading.
At the time of the first inspection, construction of the aspiration system
had not been completed at Dreyfus, however a tent was available to reduce dust
emissions. The tent aspiration system has since been completed and was in
operation during the March 1979 visit. There are three sets of two aspiration
hoBes, about 50 cm (18 in.) in diameter, connected by duct work to a fan and
a fabric filter. The total capacity of the filter is 878 m3/min (31,000 acfm),
however some of the air is drawn from transfer points. In addition, the full
capacity of the system is not applied to the hold in which grain is being
loaded. At least two hoses are typically left open outside the hold while
two are placed in the hold. GCA's measurements showed an aspiration rate of
(.160 m3/min) 5,600 acfm when two hoses were in the hold and several hoses were
open between the active hoses and the fan. In a second case one hose exhausted
air from beneath a tent at 120 m3/min (A,300 acfm). This latter hose was
connected to the manifold near the fan and only two hoses, both farther away from
the fan, were open. Some visible emissions seeping from the tent were evident
when the aspiration rate was 80 md/min (2,800 acfm) but all visible emissions
were eliminated at the higher aspiration rates.
Seven sets of formal (EPA Method 9) observations of opacity, during
uncontrolled loading, were conducted at Louis Dreyfus Corporation on September
18, 1979.14 Average opacity was 38 percent with a maximum 6-minute reading
of 52 percent and a minimum'of 32 percent. Similar informal data were obtained
during the January 1978 inspection.
Photographs of shiploading operations at the Louis Dreyfus terminal are
presented in Figure 5.
Cargil]—
The Cargill terminal in Portland was inspected 10 January 1978. The
elevator superintendant, Mr. H. Johnson, provided background information on
elevator operations. The Cargill elevator only handles wheat, and
loadK bulk-carriers almost exclusively. For example, during the latter half
of 1977 no tankers were loaded and only one tween-decker was loaded. During
the visit, a 35,000 metric ton bulk-carrier was being loaded with wheat.
Cargill uses dead-boxes to control particulate emissions from shiploading.
There are several vertical spouts equipped with dead-boxes, but only one is
used at a time. Grain flows through the dead-box at a rate of 2,000 to 2,500
t/hr during bulk-loading and 700 to 800 t/hr during topping-off. Air is drawn
from the box to a fabric filter.
17
-------
Tent eontvoI system Topping-off operation
Figure 5. Grain loading operations at the Louis Dreyfus elevator.
-------
The dead-boxes worked well when they were properly operated. During the
morning of January 10, an entire hold was filled and topped-off with visible
emissions limited to 10 percent opacity. During the afternoon, another hold
was loaded by a different group of longshoremen, who did not operate the
dead-box properly. The opacity above the hold averaged over 40 percent and
was at times 100 percent.
Figure 6 shows grain loading operations at the Cargill elevator.
Columbia Grain—
On 11 January 1978, the Columbia Grain terminal, then the Cook terminal,
was inspected. The plant superintenant, Mr. J. Beach, and the plant foreman
Mr. Henning, described loading operations at the terminal. Like the other
Portland elevators, this terminal handles mostly wheat and bulk-carriers,
although about 2 to 4 percent of the grain handled is loaded to tween-deckers.
During the visit, Cook was loading a bulk-carrier with wheat.
The terminal uses vertical loading chutes and loading rates of 1,000 t/hr
for bulk-loading, and 150 to 200 t/hr for topping-off. Particulate emissions
during shiploading are presently uncontrolled, however installation of a dead-
box type control system is underway. The air aspiration rate from the top of
the dead-box will be 340 m3/min (12,000 acfm).
During the January 11 visit, the grain-loading spout was held 3 to 9 m
(10 to 30 ft) above the grain level in the hold. Large visible clouds with
opacities approaching 100 percent were produced. The clouds were visible
100 (330 ft) downwind of the dock. Figure 7 shows grain-loading operations
at the Columbia elevator during the January visit.
Other Facilities
Continental Grain - Tacoma, Washington—
The Continental Grain terminal in Tacoma, Washington was visited 14
January 1978 as an example of a well-controlled facility. Mr. D. Davis described
shiploading operations at the facility. Most of the ships loaded are bulk-
carriers, with about four tankers being filled per year. Very few tween-deckers
are filled. The terminal handles mostly wheat but also ships some feed barley,
corn, sorghum and pellets. During the visit, a 14,000 metric ton bulk-carrier
was being filled with beet pulp feed pellets.
The Continental Grain terminal uses dead-boxes to control particulate
emissions from shiploading. Grain flows through the dead-box, which is called
a "bullet" at Continental, at 1,000 t/hr during bulk-loading and 300 t/hr during
topping-off. Air is drawn from the top of the box to a fabric filter at a rate
of 710 m3/min (25,000 acfm).
The performance of Continental's "bullet" system depended, as did the
performance of the Cargill-Portland dead-box system, on how it was operated.
During the January 14 visit, the bullets were held much too far above the
pellet levels in the holds. Because of this, and because pellets are dustier
than grain, the dust emissions were sometimes substantial. Opacities above
the hold ranged from 0 percent to as much as 50 percent. Figure 8 shows the
bullet control system in use.
19
-------
Dead-box control system operated incorrectly
Figure 6. Grain-loading operations at the Cargill elevator.
20
-------
-------
Figure 8. Bullet or dead-box control system at Continental
grain in Tacoma.
22
-------
Cargill-Seattle, Washington—
The Carglll terminal in Seattle, Washington was visited 16 January 1978,
in order to observe an operating submerged loading system. Messrs. J. Downes
and M. Rudolph described shiploading operations at this facility. Cargill
handles mostly wheat and some corn and barley. About 90 percent of the ships
loaded are bulk-carriers, while some 8 percent are tween-deckers, and 2 per-
cent are tankers. During the inspection, a bulk-carrier was being filled
with wheat.
The submerged loading system in use at Cargill in Seattle was described
earlier (see the BACKGROUND section). The system eliminated visible emissions
when the loader was kept buried. It was effective both during bulk-loading and
during topping-off of the bulk-carrier. Occasionally, the loader would become
buried too deep due to inattention on the part of the operator, and it would
become clogged. When this occurred, the loader had to be lifted out of the
grain and visible emissions in excess of 20 percent opacity were produced.
The submerged loading system worked well during loading and topping-off
There were usually no visible emissions (see Figure 9). When loading of a
hold was begun, some dust was formed in the hold because the spout did not
reach the bottom of the ship, and because there was not enough grain for the
spout to be buried. This dust generally settled back into the hold and no
clouds were formed above the hold. Occasionally, during bulk-loading, the
spout was moved to keep the grain level. If the spout was moved too quickly,
some dust was formed. Also, the spout would sometimes become clogged and it
was necessary to raise the spout above grain level to let the grain flow out.
This created clouds with opacities of up to 10 to 30 percent for about
1 minute. Usually, however, the submerged loader was properly used and there
was no visible emissions.
United Grain - Tacoma, Washington—
The United Grain terminal in Tacoma was visited 15 to 18 November 1978
in order to determine whether tent control of particulate emissions from
shiploading could pose an explosion hazard at the Bunge and Louis Dreyfus
terminals in Portland. During the visit, a bulk-carrier was being loaded with
wheat. Dust concentrations and other parameters related to dust explosibility
were measured at various locations inside the holds of the ship during both
tent controlled loading and uncontrolled loading or topping-off. The tent
eliminated visible emissions during bulk-loading of wheat.
Du.luth Facilities
The International Multifoods and General Mills terminal grain elevators
in Duluth, Minnesota were visited 16 and 17 November 1977. Shiploading opera-
tions were observed in order to determine what type of measurements could be
made to estimate particulate emissions from shiploading.
Mr. H. Graves of International Multifoods provided background information
on loading operations at Duluth. The International Multifoods terminal handles
about 85 percent wheat and 15 percent barley, and does most of its business
in the spring and fall.
23
-------
Vieu
Figure 9.
of the loading system and conveyor gallery
Cargill submerged loading facility in Seattle.
24
-------
Both of the terminals have several loading spouts which are attached to
the elevators themselves, rather than galleries on the docks. The spouts must
be moved by hand, and are capable of pouring grain at only 400 metric tons
(long tons)/hr. Neither of the terminals use control systems to reduce
particulate emissions from shiploading.
Summary of Visual Observations
Observations were made of the performance of all three types of particu-
late emission control systems presently in use: tents with aspiration, dead-
box systems, and submerged loading systems. Uncontrolled loading operations
were also observed; opacity during uncontrolled loading was usually 30 to 50
percent.
Tent systems with aspiration eliminated visible emissions during bulk-
loading of bulk-carriers, however these cannot be used for topping-off of bulk-
carriers or for tween-decker loading. Opacity during topping-off and tween-
decker loadings is typically 30 to 50 percent with both higher and lower
opacities possible. However, emissions from uncontrolled topping-off and tween-
decker loading are clearly greater than 20 percent opacity.
Dead-box control systems were capable of greatly reducing visible emissions
during both bulk-loading and topping-off of bulk-carriers under typical condi-
tions. During observations made by GCA, when the boxes were held less than
about 60 cm (2 ft) above the grain level, and moved about slowly, there were
virtually no visible emissions. When, however, dead-boxes were held high above
grain level or were allowed to swing visible emissions easily exceeded 20 per-
cent opacity. Also, when pellets were loaded rather than wheat, as was the
case during observations of loading operations at the Continental Grain terminal
in Tacoma, Washington particulate emissions with opacities greater than 20 per-
cent were generally visible.
The submerged loading system in use at the Cargill elevator in Seattle
reduced particulate emissions to an even greater extent than did the dead-box
control systems. The system was effective during both bulk-loading and topping-
off of a bulk-carrier. As with dead-box systems though the performance of the
system depended on how well it was operated. When the loader was kept sub-
merged, visible emissions were eliminated. When it was allowed to clog,
it was necessary to raise it above grain level, causing visible emissions in
excess of 20 percent opacity.
Performance of dead-box and submerged loading systems is very dependent
on the performance of the operator. Tents do not require operator attention
after they are properly attached to the hold.
EMISSION MEASUREMENTS
At the four Portland grain elevators, total and respirable particulate
concentrations were measured in the dust clouds generated during shiploading.
Particle size distributions were also determined. The concentrations, along
25
-------
with estimates of cloud cross-sectional areas and wind velocities, were used
to estimate particulate emission rates of shiploading operations. Size distribu-
tions were used to determine what fraction of the particles emitted will tend
to remain suspended over long distances.
*
A probe consisting of an Andersen cascade impactor, a cyclonic preseparator
also made by Andersen, and a glass fiber back-up filter was used to measure total
particulate concentrations and to determine particle size distributions. Air
was drawn through the probe by a vacuum pump and the flow rate was maintained at
about 9.1 liters/min (0.32 acfm) by critical orifices. Any particles entrained
in the sample air were collected by inertial impaction or filtration either in
the cyclonic precollector, on one of seven preweighed substrated in the Andersen
impactor, or on the preweighed back-up filter. At the 9.1 liters/min flow rate,
the impactor and associated collectors classified particles into the following
size ranges:
«
< 0.71 um (micrometers),
•
0.71 to 1.04 um,
©
1.04 to 1.57 ym,
©
1.67 to 3.3 ym,
•
3.3 to 5.2 ym,
©
5.2 to 7.7 ym,
0
7.7 to 11.2 um,
©
11.2 to 13.5 um,
> 13.5 ym.
Average concentrations and size distributions of particulate matter in air
sampled during a run were determined using the weight of particles collected
in the cyclone, the weights of the back-up filter and impaction substrates
before and after the run, the sample air flow rate, and the run duration.
Durations of the Andersen impactor runs ranged from 25 to 62 minutes.
An RDM-101 respirable dust monitor produced by GCA Corporation's Precision
Scientific Group'' was also used occasionally to measure respirable dust con-
centrators. The RDM-101 collects particles smaller than 3 to 6 Pin and larger
than about 0.4 urn by impaction onto a greased substrate. Beta ray attenuation
is used to determine the amount of particulate matter collected on the substrate,
and the RDM automatically calculates the average respirable dust concentration
in the sampled air and displays the concentration as a digital readout. The
RDM was used to make short-term measurements (1 to 5 minutes).
Andersen 2000, Inc., P.O. Box 20679, Atlanta, Georgia 30320, see Reference 12
for a description of the Andersen impactor.
t
GCA Corporation, Precision Scientific Group, Burlington Road, Bedford, Mass. 01730
26
-------
Particulate Concentrations and Size Distributions
The results of Andersen impactor measurements are presented in Table 2
and in Figure 10. The measurements were made at the edges of the holds being
loaded at the four terminals, generally downwind of the emission sources. One
run was made at each of the Bunge and Louis Dreyfus terminals during topping-
off operations. Two runs were made at each of the other two terminals, Columbia
and Cargill. The two runs made at the Columbia terminal were both made downwind
of the loading spout during uncontrolled bulk-loading and yielded similar
results.
At Cargill, the first run was made while the dead-box was being operated
properly, with no visible emissions. The second run was made while the dead-
box was held far above grain level and was being moved much too quickly. The
probe was located in the same place relative to the dead-box and loading spout
during the two runs. It is interesting to note that the average concentration
measured in the first run while the dead-box was operated properly, is a
factor of 10 below that measured in the second run.
Particles smaller than 30 pn (suspendable dust particles) have been
estimated using total concentrations and size distribution data extrapolated
to 30 um as shown in Figure 10. These estimates are presented in Table 3,
with results for total particulates and the less than 3 ym fractions (respirable
particulates). Particles longer than 30 ym will settle out of the atmosphere
near the grain terminal facilities possibly causing complaints as a result of
nuisance dust. Particles smaller than 30 ym will remain suspended in the
atmosphere and contribute to ambient air quality degradation. Respirable
particles if inhalded tend to deposit in lungs possibly contributing to health
effect problems.
Respirable particles were also measured with the respirable dust monitor.
Results were typically one-third to one-half the results for the similar size
fraction measured by the Andersen impactor. These results were used primarily
to define the plume and for short-term (1 to 5 minutes) indications of dust
concentration. Differences in sampling configuration and sampling intervals
may be responsible for the differences in results. The Andersen impactor
measurements are used in this report because they represent longer sampling
intervals (25 to 60 minutes).
Emission Rates
One method of estimating particulate emission rates from a source producing
visible dust emissions involves studying a cross-section of the cloud in a
plane perpendicular to the wind direction. The emission rate is equal to the
product of the average dust concentration in the cross-section, the area of
the cross-section, and the average windspeed.
In the test made at the Bunge terminal, the Andersen impactor was placed
at the edge of the hold approximately 30 degrees removed from directly down-
wind of the emission source (see Figure 11). Because of the configuration
of the ship, the equipment could not be placed directly downwind of the source.
At the point where the measurements were made, the cross-section of the cloud
27
-------
TABLE 2. RESULTS OF ANDERSEN IMPACTOR MEASUREMENTS IN
PLUMES GENERATED BY GRAIN LOADING
Test
Test
durac ion
(min)
Total
measured
concentration
(mg/m3)
Size
distribution
(concentration in
size range,
mg/m3)
> 13.5
um
11.2-13.
um
,5 7.7-11.2
ma
5.2-7.7
'jm
3.3-5.2
um
1.67-3.3 1
um
.04-1.67
um
0.71-1.04
um
< 0.71
Um
Bunge
37
89
54.8
4.8
7.4
7.1
7.1
5.0
1.5
0.0
0.6
Dreyfus
32
200
142
18.6
15.8
10.0
10.4
4.8
3.4
1.0
3.2
Cargill-1
62
9.3
5.9
0.18
1.1
0.19
0.53
0.35
0.53
0.36
0.18
Cargill-2
62
95
33.8
9.7
12.1
8.6
25.4
3.7
1.1
0.38
1.9
Columbia-1
25.4
104
39.3
14.4
10.4
15.6
11.8
9.6
2.6
0.42
0.0
Columbia-2
34
135
60.5
10.0
20.9
13.5
12.0
9.0
5.8
2.6
0.68
-------
0 01 0 1 0^1 2 5 10 20 30 40 30 60 70 80 90 95 98 99
WEIGHT PCRCENT OF PARTICLES LESS THAN THE STATED SIZE
99 9 99 9*
Figure 10. Size distribution of particulate emissions from shiploading,
primarily topping-off.
29
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TABLE 3. PARTICULATE CONCENTRATIONS IN SELECTED SIZE RANGES
Total
Test concentration
mg/m3
Bunge
89
59
5
Dreyfus
200
100
10
Cargill-1
9.3
6.1
1.4
Cargill-2
95
81
4.6
Columbia-1
104
92
12
Columbia-2
135
110
13
Suspendab e Respirable particles
particles (smaller than
(smaller than _ .
or. •> 3 wn)
30 ym) , 3
, 3 mg/m0
mg/m0
30
-------
WIND
23 m/min
HOLD
OPENING
MEASURING
EQUIPMENT
yWIND
45 m/min
DUST CLOUD
loading
SPOUT
HOLD OPENING
DUST
CLOUD
I meter
(O ) BUNGE TERMINAL
( b ) DREYFUS TERMINAL
Figure 11. Placement of measuring equipment at the Bunge and Dreyfus grain loading terminals.
-------
was roughJy half elliptical, 12 meters (AO ft) high and 6 meters (20 ft) wide
with nn area of 56.5 (608 ft^). The wind velocity was 23 m/min (75 ft/min)
whicli Lndicates a volumetric flow rate of 1,300 m3/min (46,000 acfm). Average
particulate concentrations were 89 mg/m3 total, 59 mg/m3 suspendable and
5 mg/m3 respirable indicating emission rates of 6.9 kg/hr (15 lb/hr) for total
particulates, 4.6 kg/hr (10 lb/hr) for suspendable particulate and 0.39 kg/hr
(0.86 lb/hr) for respirable particulates. Emission rates for Bunge and the
other facilities are presented in Table 4.
At the Louis Dreyfus terminal, the Andersen impactor was placed directly
downwind of the emission source (Figure 11). The average total, suspendable
and respirable particulate concentrations were 200 mg/m3, 100 mg/m3 and
10 mg/m3. At the point where these measurements were made, the cross-section
of the cloud was roughly a half ellipse about 4.5 m (15 ft) high and 9 m
(30 ft) wide, and the windspeed was 45 m/min (150 ft/min). The emission rates
derived from the above data are 24 kg/hr (53 lb/hr), 12 kg/hr (26 lb/hr)
suspendable dust, and 1.2 kg/hr (2.6 lb/hr) respirable dust.
During the first test at the Cargill terminal, the Andersen impactor and
the RDM-101 were placed at the edge of the hold being loaded, about 45 degrees
removed from the average downwind direction from the dead-box (see Figure 12).
The windspeed was 30 meters/minute (100 ft/min) and the wind direction varied
through at least 90 degrees. The average total suspendable, and respirable
dust concentrations measured by the Andersen impactor were, respectively,
9.3 mg/m3, 6.1 mg/m3 and 1.4 mg/m3. As was mentioned earlier there was no
visible emission cloud during this test. It is therefore, impossible to
estimate the dust emission rate by taking the product of the plume area, the
windspeed, and the average concentration in the plume. However, based on the
measured dust concentrations and observations at other facilities, emissions
at Cargill appeared to be an order of magnitude lower than at Bunge and
Louis Dreyfus.
During the second Cargill test, the dead-box system was not operated
properly, and there were visible emissions. The Andersen impactor was located
in the same spot as during the first test, but RDM-101 measurements were made
in several different locations (see Figure 12). The wind was steady with a
speed of 75 m/min (250 ft/min), but the top of the hold was sheltered from
the wind on two sides by the hold covers which had been lifted to a vertical
attitude. The average total, suspendable and respirable dust concentrations
at the edge of the hold measured by Andersen impactor results were 95 mg/m3,
81 mg/m3 and 4.6 mg/m3, respectively.
A slight upward airflow of 15 m/min (50 ft/min) could be detected at
this site. This was presumably the result of turbulence caused by the
raised hold covers. If one assumes that air was entering one side of the
hold and leaving the other side at 15 m/min, emission rates were 6.1 kg/hr
(13.5 lb/hr), 5.2 kg/hr (11.5) and 0.30 kg/hr (0.66) for total, suspendable
and respirable particulates. RDM-101 readings were also taken some 12 m
(40 ft) downwind of the dead-box, both behind the hold cover and on a small
platform slightly higher than the hold cover level. At this point, the dust
32
-------
TABLE 4. JGEASURED EMISSION RATES FOR GRAIN LOADING
Loading
rate
(t/hr)
Emission rate
(kg/hr)*
Total
particulates
Suspendable
particulates
Respirable
particulates
GCA Observations and Tests
Uncontrolled Loading
Bunge (topping-off)
Louis Dreyfus (topping-off)
Columbia-1
Columbia-2
600
400
1,000
1,000
6.9f
24
47
58
4.6 +
12
42
47
0.39+
2.6
5.5
5.5
Tent Controlled Loading
Bunged
Louis Dreyfus'
1,200
1,000
o o
o o
o o
o o
o o
o o
Dead-Box Controlled Loading
Cargill-1 (properly
operated)
Cargill-2 (poorly
operated)
2,200
2,200
0.6
6.1
0.4
5.2
0.09
0.30
§
Monsanto Test
Uncontrolled loading
630
—
-
0.42
*1 kg/hr = 2.205 lb/hr.
^These values may be low because of restrictions on the location of measuring equipment.
^Estimates of 0 are based on the lack of visible emissions.
§
Reference 13.
-------
WIND
75 m/mio
¦ LOADING SPOUT and
DEAD BOX
HOLD
OPENING
-HOLD
COVER
'—ANDERSEN
IMPACTOR
MEASURING
EQUIPMENT
WIND LIGHT on
-------
cloud cross-section was roughly circular, about 6 meters in diameter (see
Figure 12). The average respirable dust levels at the deck level and on the
platform were 0.23 mg/m3 and 0.74 mg/m^. The respirable dust emission rate
given by the product of the average of these levels, the plume area, and the
windspeed is 0.062 kg/hr (0.14 lb/hr), which is less than the 0.30 kg/hr
(0.66 lb/hr) measured above the hold and the difference may be attributable to
the different sampling locations and methods.
Very rough estimates of the emission rates during loading of the first
hold at Cargill can be obtained by multiplying the emission rates for the second
hold by the ratios of the concentrations detected at the edge of the hold open-
ing during loading of the first hold to those detected during loading of the
second hold. The emission rates 0.6 kg/hr (1.3 lb/hr), obtained by this method
are 0.4 kg/hr (0.9 lb/hr) and 0.09 kg/hr (0.2 lb/hr) for total, suspendable
and respirable dust, respectively. These represent estimates of emissions
from well-run dead-box loading of wheat to bulk-carriers.
During emission testing at the Columbia terminal, the grain spout tips
were kept at approximately the level of the hold covers, thus allowing grain
to fall some 6 to 12 meters (20 to 40 ft) into the holds. Dust emissions
were substantial. The Andersen impactor was placed at the edge of the hold,
directly downwind of the loading spout, the emission source. RDM-101 readings
were taken at approximately 1.5 meter intervals along the hold edge. The
placement of measuring equipment is illustrated in Figure 13, and respirable
dust concentrations measured during the two tests with the RDM-101 are presented
in Table 5. During the first test the emission cloud being studied was half-
elliptical in cross-section, and was 9 meters (30 ft) high and 10 meters (33 ft)
wide in the plan where the measurements were made. The emission cloud studied
in the second test was also half-elliptical 12 meters (40 ft) high and 14
meters (46 ft) wide. The windspeed during the tests was about 90 meters/min
(300 ft/min).
Since dust concentrations were measured at several locations along the
side of the holds during the two Cook tests, it is possible to calculate the
average dust concentrations in the plumes at the hold edges, rather than
merely calculating the time average concentrations for single spots as was
done for the Bunge, Louis Dreyfus, and Cargill tests. The approximate
average respLrable dust concentrations for the plume passing through the
instrument locations can be found by taking the averages of the sets of
RDM-101 readings presented in Table 5 weighted by the squares of distances
of the measuring equipment locations from the cloud center. This method
assumes that variations of dust concentration with height were proportional
to variations with horizontal distance perpendicular to the wind direction.
The average concentrations of respirable dust given by this method are 2.6 mg/
m3 or 60 percent of the center point concentration for the first Cook test
and 1.2 mg/m3 on 31 percent of the center point concentration for the second
test.
With the above data it is not necessary to assume that the Andersen
impactor data at the plume center represents the full plume. Instead, one
35
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Figure 13. Measurements made at the Columbia elevator.
36
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TABLE 5. RESPIRABLE DUST CONCENTRATIONS MEASURED
AT THE COLUMBIA ELEVATOR
Distance and direction
Average concentration (mg/m^)
plume center
(meters)
Test 1
Test 2
-7.5
0.0
0.0
-6
2.2
0.4
-4.5
3.1
1.4
-3
5.5
1.2
-1.5
4.6
2.8 .
0
4.4
3.9
+1.5
3.6
3.1
+3
3.7
3.1
+4.5
2.3
3.1
+6
0.0
2.0
+7.5
0.0
1.2
+9
-
0.8
37
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can assume that the plume average concentration is 60 percent and 30 percent
of the Andersen impactor results represented in Table 3. The average
Buspendable dust concentrations by this method are 55 mg/m3 for the first
run and 33 mg/m^ for the second test. Estimated emission rates are
42 kg/hr (93 lb/hr) and 47 kg/hr (104 lb/hr) suspendable dust for the first
and second tests, respectively.
EMISSION FACTORS
Emission factors for various phases and types of shiploading at the four
Portland grain terminals have been calculated using the emission rates esti-
mated above and the loading rates used at the facilities. These are presented
in Table 6. Estimates have been made in the past of emission factors for ship-
loading, however, these are not generally based on emission measurements, but
on the amount of grain lost during shiploading, which is about 500 g/t (1 lb/
ton) . ^ This is a questionable method of estimating emissions, since some
grain is spilled. Our measurement for total particulate emissions indicate
an emission factor about one order of magnitude lower. Monsanto Research
Corporation has also measured an emission factor for respirable dust from
uncontrolled shiploading as shown in Table 6.
Visual observations indicate that emission factors for uncontrolled
bulk-loading and topping-off operations should be similar. Emission factors
estimated for uncontrolled bulk-loading at the Columbia terminal and for
uncontrolled topping-off at the Louis Dreyfus facility are similar. The
emission factors estimated for topping-off at the Bunge terminal should
probably be disregarded because of the fact that measurement equipment was
located at the fringe of the plume. The average estimated emission factors
for uncontrolled loadi'ng (disregarding the Bunge tests) are 55 g/t (0.11 lb/
ton) for total particulates, 40 g/t (0.08 lb/ton) for suspendable dust, and
5.8 g/t (0.012 lb/ton) for respirable dust. The Monsanto estimate of the
respirable dust emission factor for uncontrolled loading, 0.67 g/t (0.0013
lb/ton) falls below the range of the GCA estimates of respirable dust emission
factors for uncontrolled loading of wheat.
Estimated emission factors for dead-box controlled shiploading at the
Cargill terminal are lower than those for uncontrolled loading, as would be
expected. Also, the emission factor for the test where the dead-box was
poorly operated (Cargill-2) are much higher than that for the test where
the dead-box was well operated (Cargill-1).
The overall emission factors for shiploading with tent control can be
estimated by taking the averages of the emission factors for uncontrolled
loading and those for controlled loading, weighted by the percentage of time
spent bulk-filling and topping-off for a typical hold. Grain elevator operators
indicate that when tents are used to control dust emissions 10 to 30 percent
of the hold must be filled without the tents (topping-off). Also, one can
calculate the percentage of a hold which would normally be filled without
the use of a tent. Normally in tent-controlled loading, the tent is used
until, the top of the pile of grain in the hold is within about 4 ft of the
top of the hold. At this point the average distance between the top of
the hold and the grain level in the hold will, of course, be greater than
38
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TABLE 6. EMISSION FACTORS FOR SHIPLOADING
Emission factor*
Loading (g/t)
rate
(t/hr)
Total
particulates
Suspendable
particulates
Respirable
particulates
GCA Observations and Tests
Uncontrolled Loading
Bunge (topping-off)
600
11.5f
7.7 +
0. 65+
Louis Dreyfus (topping-off)
400
60
30
6.5
Columbia-1
1,000
47
42
5.5
Columbia-2
1,000
58
47
5.5
Tent Controlled Loading
Bunget
1,200
0
0
0
Louis Dreyfus^
1,000
0
0
0
Dead-Box Controlled Loading
Cargill-1 (properly
operated)
2,200
0.3
0.2
O
o
Cargill-2 (poorly
operated)
2,200
2.8
2.4
0.14
§
Monsanto Test
Uncontrolled loading
630
-
-
0.67
*
1 gram/metric ton (1 g/t) = 0.002 pound/short ton (0.002 lb/ton).
^These values may be low because of restrictions on the location of measuring equipment.
^Estimates of 0 are based on the lack of visible emissions.
§
Reference 13.
-------
4 ft, and will be determined by the shape of the hold, and the angle of repose
of wheat, which is about 23 degrees. The volume of the unfilled portion of
the hold would also be determined by these parameters. This unfilled portion
is filled by topping-off. The percentage of a hold which would be filled by
topping-off has been calculated for various loading conditions.
o For a hold 40 ft deep, AO ft wide, and 40 ft long, which during
bulk-loading, is filled so that the top of the grain pile is
at the level of the top of the hold, the portion of the hold
filled by topping-off would be about 15 percent.
® For a hold of the same dimensions which is filled so that the
top of the grain pile is 4 ft below the top of the hold, the
portion to be filled by topping-off would be about 25 percent.
® For a hold 60 ft deep, 60 ft wide, and 60 ft long filled so
that the top of the grain pile is 4 ft below the top of the
hold, about 22 percent would be filled by topping-off.
These volume percentages are in agreement with the estimates made by the
elevator operators. ^
If, in tent-controlled loading, the portion of a hold filled by topping-
off is assumed to be about "25 percent, the combined emission factors for the
loading bulk-filling and topping-off will be roughly 25 percent of the emission
factors for uncontrolled loading. Thus, the total emission factors for tent-
controlled loading are about 14 g/t (0.028 lb/ton) for total particulates,
10 g/t (0.02 lb/ton) for suspendable dust, and 0.003 lb/ton for respirable
dust.
Average emission factors for tent controlled loading are compared with
emission factors for dead-box controlled loading and uncontrolled loading
in Table 7. The table shows that average emission factors for tent controlled
loading are 50 times higher than those for dead-box control when the dead-box
is well operated; they are about 5 times higher than those for dead-box control
when the dead-box is poorly operated.
40
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TABLE 1. AVERAGE PARTICULATE EMISSION FACTORS
Emission factors (g/t)
Process
Total Suspended Respirable
Uncontrolled loading
55
40
5.8
Tent controlled loading
Bulk-loading
0
0
0
Topping-of f
55
40
5.8
Average
14
10
1.5
Dead-box controlled loading
Well operated
0.3
1.2
0.04
Poorly operated
2.8
2.4
0.14
Note that only about 25 percent of the total grain loaded
is loaded during the topping-off phase.
41
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SECTION 4
TECHNICAL FEASIBILITY OF MEETING OPACITY REGULATIONS
AT PORTLAND GRAIN TERMINALS
Observations of shiploading operations at the Portland grain terminals
indicated that all four of the terminals were occasionally or frequently in
violation of the State of Oregon visible emissions standard for the Portland
area. This standard states that the opacity of visible emissions should not
exceed 20 percent for more than 30 seconds of a given hour.
CARGILL
The dead-box control system now in use at the Cargill terminal at Port-
land ls capable of satisfying the Oregon visible emissions standards during
the loading of bulk carriers if it is properly used. If the box is kept
within 6 to 18 inches of the grain level and is moved about slowly the
opacity of visible emissions created by grain dropping from the box will be
less than 20 percent. On the other hand, if the device is not used correctly,
visible emissions with opacities in excess of 50 percent can result.
The Cargill terminal is also planning to modify a trimming machine so
that emissions from the loading of tween-deckers can be controlled by ducting
air from the machine to the fabric filter control system used for the dead-
boxes. Such a system would be similar to the system for use during tween-
decker loading at Cargill in Seattle, and is expected to reduce visible emis-
sions to under 20 percent opacity.
Thus, in the near future, the Cargill terminal should be capable of
meeting the present Oregon visible emissions standards except in severe
weather or under other upset conditions.
COLUMBIA
The Columbia terminal in Portland is not presently capable of meeting
the Oregon state visible emissions standard during any phase of shiploading.
Columbia Grain is continuing the construction of a dead-box control system.
When this control system is installed, the Columbia terminal will be able
to meet the standard while loading bulk-carriers both during bulk-loading and
during topping-off. The Columbia Company is also considering altering a
trimming machine so that emissions can be controlled during the loading of
tween-deckers. Whether an altered trimming machine is obtained will depend
on how muny tween-deckers are handled at the Columbia terminal in the near
future.
42
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BUNGE AND LOUIS DREYFUS
Both the Bunge and Louis Dreyfus terminals have tent control systems
which arc capable of eliminating visible emissions during most phases of ship-
loading. These systems are not presently used, because of concern generated
by explosLons at grain elevators in late 1977 and early 1978. Stevedores at
Portland feel that containment of dust in the hold by tent control
systems poses an explosion hazard. Measurements of dust concentrations under
tents used to control emissions were made by GCA at the United Grain facility
in Tacoma, Washington and at Bunge and at Louis Dreyfus. Results of these
tests showed that dust concentrations found under the tents were well below
minimum explosive limits for grain dust cited in literature.1
The tent control systems available at Bunge and Louis Dreyfus could be
used for bulk-loading operations, but would not generally be used during
topping-off or during the loading of tween-deckers. Emissions from these
shiploading operations can technically be controlled by systems such as those
in use nt the Cargill terminal in Portland and the Cargill terminal in
Seattle although the cost may be very high.
Problems associated with installing a submerged loading system such as
that in use at the Cargill facility in Seattle are discussed in the BACKGROUND
Section of this report (Section 2). Some changes would certainly be necessary
in order for the Bunge and Louis Dreyfus terminals to use such a system. First,
it would be necessary to increase the telescoping capabilities of the loading
spouts from about 6 meters (20 ft) to about 12 meters (40 ft). Second, it would
be necessary to attach telescoping aspiration pipes to the outside of the
loading spouts, and to merge the pipes and the spouts in a manner similar
to that illustrated in Figure A, Third, a system would be needed whereby
the conveyors feeding the loading spouts would be automatically shutdown when
the spouts become clogged. Such a system is described in the BACKGROUND
Section of this report (Section 2). The aspiration systems which were in-
stalled at the terminals for use with the tent systems are capable of
meeting the aspiration needs of submerged loading systems; however, it would
be necessary to install ductwork to connect the system to the loading spout
aspiration pipes. The consensus of opionin of grain elevator operators in
Portland and Seattle and manufacturers of pollution control equipment for
grain elevators11 is that the cost of these changes would be on the order of
$100,000 to refit about five loading spouts. Some other changes may also
be necessary. Both terminals use motors which are required to move loading
spouts during submerged loading; however, it may be necessary to use more
powerful, motors. The cost of this change would be minor. The factor which
will determine whether submerged loading would be feasible for the Bunge and
Dreyfus terminal will be whether or not the shiploading galleries would have
to be refurbished to handle the additional weight and torque which would result
from attaching additional telescoping sections and aspiration tubes to the
loading spouts. If such work is necessary (and it probably is needed), the
cost of installing submerged loading would be as high as 5 million dollars
for five loading spouts.
The designers of the shiploading galleries would be in the best position
to determine whether the galleries would have to be altered to support the
A3
-------
weLght of attachments to the loading spout. Both the Bunge and Louis Dreyfus
elevators have experimented with attaching an aspiration tube to a loading
spout; however, they have not tried to add additional sections.
Because of the nature of the galleries and the loading chutes at the
Bunge and Loui9 Dreyfus terminals in Portland it would not be possible to
install a dead-box control system such as that in use at Cargill in Portland
without making major modifications. The consensus of opinion of grain ele-
vator operators in Portland and Seattle and manufacturers of pollution control
systems for grain elevators is that the cost of such modifications would be on
the order of $1,000,000 per loading spout (see Section 2). Thus, depending
on the number of loading spouts to be converted, the cost of installing dead-
boxes at Bunge or Louis Dreyfus could approach $5,000,000.
A cost of 5 million dollars for refurbishing a gallery to allow the use
of dead-boxes or submerged loading, if amortized over a period of 15 years
at 10 percent interest, would amount to about 700,000 dollars per year. The
grain throughputs of Portland terminals vary from year to year, and from
terminal to terminal, but are typically about 1,000,000 metric tons per year.
Thus, the cost of major refurbishments amortized over 15 years would amount to
about 0.70 dollars per metric ton of grain shipped, or 1.9 cents per bushel.
The average profit for grain terminals is only 2.1 cents per bushel. The
ability of grain elevator owners to increase grain prices, currently $3-4
per bushel, to maintain profit margins has not be assessed in this study.
If submerged loading could be retrofitted to the Bunge and Louis Dreyfus
terminals without major modifications to the galleries and docks the cost would
be substantially less. The estimated cost of 100,000 dollars for adapting five
loading spouts, if amortized over a period of 15 years at 10 percent interest
would amount to about 14,000 dollars per year, which is about 1.4 cents per
metric ton, or about 0.038 cents per bushel. This cost is about 2 percent of
the average profit per bushel.
Again, this latter cost would apply only if it is possible to make additions
to the loading spouts without making major changes to the loading gallery. Major
modification would probably be required, greatly increasing the costs.
The first step to reduce emissions should be full use of the tent control
systems at the Bunge and Louis Dreyfus terminals. The estimated average
uncontrolled emission factors were 40 g/t (0.08 lb/ton) of suspendable dust,
while the estimated average emission^ factor for bulk-carrier loading with
tent control would be 11 g/t (0.022 lb/ton). This value is arrived at assuming
that toppJ.ng-off begins when the top of the pile of grain in the hold is 1.3
meters (4 ft) below the tent. Emissions should be further reduced by minimizing
the amount of grain loaded in the topping-off phase, by filling the hold until
the grain In the center of the hold reaches the level of the tent. By this
method the amount of grain loaded in the topping-off mode could be reduced
from about 25 percent to 15 percent. Emissions would be reduced 40 percent from
10 g/t (0.02 lb/ton) to 6 g/t (0.12 lb/ton). If the grain spout is moved
during bulk-loading so that some of the space near the edges of the hold
Ls filled before the tent is removed, then the average emission factor for
bulk-carrier loading with tent control will be even lower. Also, topping-off
emissions could be reduced by holding the grain spout closer to the grain during
topping-off.
-------
Emissions from tween-decker loading amount to a small increase in the
average emission factor, since only about 2 percent of the grain shipped from
Portland is loaded to tween-deckers.
Emissions from a dead-box control system are 0;2 to 2.4 g/t (0.004 to
0.048 lb/ton) depending on whether the system is well operated or poorly
operated. Emissions from a submerged loading would also vary with the mode
of operation, but would be somewhat less than from dead-box control systems.
Thus, the use of the existing tents would result in an 85 percent reduction
of the average emission rate of suspendable, while the use of dead-boxes or
submerged loading would result in an 87 to 99 percent reduction of the
average emission rate. In the former case visible emissions in excess of the
20 percent limit would occur at least once every 2 days, while in the latter
case, such emissions would be generated only as a result of improper operation
of the control equipment, or in adverse weather conditions.
45
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1
2
3
4
5
6
7
8
9
10
11
12
REFERENCES
Battye, W., R.R. Hall, and P. Lilienfeld. Grain Terminal Control Study,
Volume II, Crain Dust Levels Caused by Tent Control of Shiploading Com-
pared to Minimum Explosive Limits. GCA/Technology Division. GCA-TR-79-
06 (G2). EPA Contract No. 68-01-4143, Task Order Nos. 24 and 47. Draft
Report. May 1978.
Standards Support and Environmental Impact Statement, Volume 1: Proposed
Standards of Performance for the Grain Elevator Industry. U.S. Environ-
mental Protection Agency. EPA-450/2-77-001a. February 1977.
Oregon Administrative Rules, Chapter 340, Division 21, Department of
Environmental Quality, Air Pollution Control.
Inspection of the Bunge Terminal Grain Elevator in Portland, Oregon.
January 1978.
Inspection of the Louis Dreyfus Terminal Grain Elevator in Portland,
Oregon. January 1978.
Inspection of the United Grain Terminal in Tacoma, Washington.
November 1978.
Conversation with Mr. J. Close, Oregon Department of Environmental
Quality. January 1978.
Inspection of the Cargill Terminal Grain Elevator in Portland, Oregon.
January 1978.
Inspection of the Continental Grain Terminal in Tacoma, Washington.
January 1978.
Inspection of the Cargill Grain Elevator in Seattle, Washington.
January 1978.
Telephone Conversation between Mr. D. McLaine of Archer Blower Co.
(designers of the particulate emission control system in use at Cargill
in Seattle) and W. Battye (GCA/Technology Division). 10 January 1978.
Operating Manual for Andersen 2000 Inc., Mark II and Mark III Particle
Sizing Stack Complex. Review A, TR-76-00023. August 1, 1977.
46
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13. Blackwood, T.R., R.A. Wachter, and J.A. Peters. Source Assessment:
Handling, Transport, and Storage of Grain, State-of-the-Art. Monsanto
Research Corporation. EPA Contract No, 68-02-1874, P,E, No. 1AB604,
EPA Project Officer: D.A. Denny. August 1977.
14. Spawn, P. Trip Report - Visible Emission Observations of Grain Loading
at Louis Dreyfus Corporation and Bunge Corporation. GCA/Technology
Division. EPA Contract No. 68-01-4143, Task Order No. 47. September 1978.
15. Compilation of Air Pollutant Emission Factors. Third Edition.
U.S. Environmental Protection Agency. Publication No. AP-42, August 1977.
47
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APPENDIX A
CONVERSION FACTORS FOR SELECTED
METRIC AND BRITISH UNITS
48
-------
TABLE A-l. CONVERSION FACTORS FOR SELECTED
METRIC AND BRITISH UNITS
To convert from
To
Multiply by
g (grams)
gr (grain)
15.432
8
lb (pound)
0.0022
Vim (micrometer)
in. (inch)
0.000254
cm (centimeter)
in.
2.54
m (meter)
ft (foot)
3.281
m2
ft2
10.76
m3
ft3
35.32
g/m3
gr/ft3
0.437
g/m3
lb/ft3
0.000062
m/min
ft/min
3.281
m3/min
ft3/min
35.32
g/t (metric ton)
lb/ton (British)
0.002
49
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