United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-91-009
April 1991
Air
&EPA Evaluation of Air Toxic Emissions
at Minnesota's Reconstituted
Panelboard Plants
control
technology center
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EPA-450/3-91-009
April 1991
EVALUATION OF AIR TOXIC EMISSIONS AT
MINNESOTA'S RECONSTITUTED
PANELBOARD PLANTS
PREPARED BY:
Charles C. Vaught
Midwest Research Institute
Suite 350
401 Harrison Oaks Boulevard
Gary, NC 27513
Prepared for:
Minnesota Pollution Control Agency
520 Lafayette Road
St. Paul, Minnesota 55155
Control Technology Center
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
Bob.Blaszczak
Work Assignment Manager
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
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DISCLAIMER
This document presents an air toxics emissions evaluation of
reconstituted panelboard plants in Minnesota. Specifically, the
document evaluates process and emission sources of the subject
plants. A summary of the available literature on air toxics
emissions from the reconstituted panelboard industry is
presented. Furthermore, a general air toxics test plan is
presented to characterize in detail the air toxics emissions from
these mills. Midwest Research Institute does not represent that
this document comprehensively sets forth all of the procedures
for measuring air toxics emissions.
Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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ACKNOWLEDGMENT
This report was prepared for the Minnesota Pollution Control
Agency and EPA's Control Technology Center by Mr. C.C. Vaught of
Midwest Research Institute. Ms. Fardin Oliaei of MPCA and
Mr. Bob Blaszczak of the CTC were the Work Assignment Managers.
111
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PREFACE
The project to evaluate air toxics emissions and develop a
test plan for reconstituted panelboard mills in Minnesota was
jointly sponsored by the Minnesota Pollution Control Agency and
EPA's Control Technology Center (CTC). The CTC was established
by EPA's Office of Research and Development and the Office of Air
Quality Planning and Standards to provide technical assistance to
State and local air pollution control agencies. Engineering
assistance projects, such as this one, focus"on topics of
national or regional interest that are identified through
contacts with State and local agencies. In this case, the CTC
was contacted by the MPCA to help develop a test plan for
measuring air toxics emissions from reconstituted panelboard
mills. As a result, EPA's Air Quality Management Division
contracted with Midwest Research Institute to prepare the air
toxics test strategy. This report presents the results of the
air toxics study. The report discusses the reconstituted
panelboard industry in Minnesota, the processes used, available
literature on air toxics emissions from these mills, and the
proposed air toxics test strategy.
IV
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TABLE OP CONTENTS
Pac
1.0 INTRODUCTION 1
1.1 BACKGROUND 1
1. 2 OBJECTIVES OF THE STUDY 1
2.0 EVALUATION OF RECONSTITUTED PANELBOARD PLANTS IN
MINNESOTA 1
2.1 GENERAL PROCESS DESCRIPTIONS 2
2.1.1 Hardboard Manufacturing Proces 5
2.1.1.1 Dry Process 5
2.1.1.2 Wet Proces 5
2.1.2 Oriented Strandboard Manufacturing Process.... 6
2.1.3 Aligned Fiberboard Manufacturing Process 7
2.2 EVALUATION OF EMISSION SOURCES 8
2.2.1 Hardboad Manufacturing Plants 8
2.2.2 OSB Manufacturing Plants 9
2.2.2.1 Wood Flake Dryers ". 10
2.2.2.2 Press Vents 12
2.2.2.3 Steam- or Hot Oil-Generating Units... 13
2.2.3 Aligned Fiberboard Manufacturing Plant 14
3.0 PRELIMINARY AIR TOXICS EMISSIONS ASSESSMENT 14
3.1 PRODUCTS OF THERMAL COMPOSITION 21
3.2 SUMMARY OF AVAILABLE AIR TOXICS TEST DATA 24
3.2.1 Wood Flake Dryers 24
3.2.2 Press Vents 29
3.2.3 Combustion Units 31
4.0 AIR TOXICS TESTING STRATEGY 31
4.1 SCREENING ANALYSIS 32
4.1.1 Recommended Screening Test Methods 35
4.1.2 Plants and Sources Recommended for Screening.. 35
4.1.2.1 Hardboard Mills 35
4.1.2.2 OSB Mills .' 36
4.1.2.3 Aligned Fiberboard Mill 36
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TABLE OF CONTENTS (continued)
Paqe
4.2 SPECIFIC ANALYSIS 37
4.2.1 Recommended Specific Test Methods 37
4.2.2 Plants and Sources Recommended for Testing.... 38
5.0 REFERENCES 39
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LIST OF TABLES
Page
TABLE 1. SUMMARY OF OPERATING CHARACTERISTICS FOR
RECONSTITUTED PANELBOARD PLANTS IN
MINNESOTA 3
TABLE 2. MINNESOTA1 S AIR TOXIC LIST 15
TABLE 3 PRODUCTS RELEASED FROM THERMAL DECOMPOSITION
OF WOOD 22
TABLE 4. DESCRIPTION CHARACTERISTICS AND FORMALDEHYDE
EMISSION RATES FROM DRYERS-SURVEYED
BY NCASI 25
TABLE 5. SUMMARY OF FORMALDEHYDE TESTS ON WAFERBOARD
DRYERS CONDUCTED AT PLANTS IN COLORADO
AND MICHIGAN . . . 27
TABLE 6. SUMMARY OF PHENOL TEST RESULTS AT WAFERBOARD
PLANTS 28
TABLE 7. SUMMARY OF THE FORMALDEHYDE TESTING ON PRESS
VENTS AT WAFERBOARD PLANTS 30
TABLE 8. SUMMARY OF PLANTS AND SOURCES RECOMMENDED FOR
AIR TOXICS SCREENING AND SPECIFIC ANALYSIS 33
TABLE 9. AIR TOXICS POTENTIALLY EMITTED FROM MINNESOTA
RECONSTITUTED PANELBOARD PLANTS 34
Vll
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1.0 INTRODUCTION
1.1 BACKGROUND
Given the increased level of construction of new and
expanded reconstituted building board manufacturing plants, there
has been a heightened demand for reliable emissions information
needed to prepare air quality permit applications. Emissions
information is also needed to respond to a growing number of
State agencies concerned with air toxics from both new and
existing plants. In the State of Minnesota, five waferboard
facilities are currently operating. One of the existing plants
is undergoing an expansion to significantly increase its
production capacity. An aligned fiberboard plant is also under
construction. In addition, two hardboard production plants also
operate in the State. The Minnesota Pollution Control Agency
(MPCA) has received numerous citizen complaints of odors and
nasal irritation near these facilities. The potential for
emissions of formaldehyde and other toxic pollutants that may
present a significant health risk has led the MPCA to investigate
the toxic air emissions being emitted from pressed wood
manufacturing facilities in the State. The information to follow
is the result of a preliminary emissions assessment for pressed
wood manufacturing facilities and an investigation of the effect
of operational parameters on the emission rates of selected air
toxic pollutants.
1.2 OBJECTIVES OF THE STUDY
The three primary objectives of the study are as follows:
(1) to characterize the operation of the pressed wood plants and
identify their air emission sources, (2) to assess, to the extent
possible, the probable species and quantities of air toxics
submitted, and (3) to develop a test plan capable of supplying
the necessary information to complete the air toxics emissions
inventory for pressed wood facilities.
2.0 EVALUATION OF RECONSTITUTED PANELBOARD PLANTS IN MINNESOTA
In the first week of November, Midwest Research Institute
(MRI), accompanied by MPCA personnel, visited the following
reconstituted wood panelboard plants in Minnesota:
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Superwood, Duluth
Superwood, Bemidji
Louisiana-Pacific/ Two Harbors
Potlatch, Bemidji
Potlatch, Grand Rapids
Northwood Panelboard, Bemidji
The only other panelboard facilities present in Minnesota that
were not visited are Potlatch in Cook and MacMillan-Bloedel in
Deerwood. The Potlatch facility in Cook was not visited because
it is identical to the company's facility in Bemidji. The
MacMillan-Bloedel plant was still under construction and not yet
operational. The purpose of these visits was to gather the
necessary information from each plant to compare and contrast the
manufacturing operation at the plants/ with an emphasis placed on
identifying the key manufacturing variables that will have a
significant impact on emissions. Table 1 presents a summary of
the information gathered from our visits that is pertinent to
this evaluation.
2.1 GENERAL PROCESS DESCRIPTIONS
It became obvious from our visits that the same technology
and processes are used to manufacture waferboard at each plant.
However, observations made during our visits to the subject
plants clearly indicated that significant differences exist
between the technology and processes used to produce hardboard
and that used to produce waferboard. Also, information obtained
from MPCA supports that the aligned fiberboard plant under
construction, although similar to waferboard, does have unique
process characteristics. Consequently, the manufacturing
processes of these three products and their effect on air
emissions will be evaluated independently. The following is a
general description of the processes used in manufacturing
hardboard, oriented strandboard (OSB), and aligned fiberboard
products in Minnesota mills.
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Table 1. Summary of operating characterics for reconstituted panelboard plants in Minnesota.
•UPEHWOOD
OULUTH
PRODUCT HAROBOARO
ANNUAL PRODUCTION (TONS/DAY) 980
BOARD THICKNESS (IN) I/* W \H
WOOD TYPE (SPECIES) ASPEN i
NUMBER or omtM o
DRYER MANUFACTURER NA
DRYER DIAMETER (FT) ' NA •
DRYER LENGTH |rr) NA
DRYER INLET TEMP. (DEO. F) NA
DRYER OUTLET TEMP. (DEfl. F| " NA
N.ET WOOD MOISTURE NA
OUTLET WOOD MOISTURE NA
MflFLOWRATI IN DRYER |ACFM) NA
TYPl OF DRYER NA
DRYER MEAT SOURCE NA
FUEL FOR DRYER HEAT NA
RATED INLET ITU/HR NA
DRY FURMSH PRODUCTION RATE (LB/HR) NA
PRIMARY CONTROL DEVICE NA
SECONDARY CONTROL DEVICE NA
TYPC OF BINDER LIQUID Ft
PERCENT RESIN IN PANEL (W/W) 16*
1UPEHWOOO
BEMIDJI
HARDBOARD
110
IK TO 1/4
: SOMA8PEN
am PINE
1
RADER
200-400
1*0
40-86*
t-M4
M.OOO
FLASH TUBE
FURNACE
NATURAL QAS
10.200
MULTKXONES
NONE
LIQUID PF
2-ttt
L-f
TWO HARBORS
ORIENTED
OTRANOIOARO
100
1(4
ASPEN
1
MECI2M
12
to
t»o»
230
«-«%
Mt
w.ooo
•*-MSa:
•UaPENWQN
BURNER
SAW TRIM
FINE*,
40MUBTWHR
24.020
UULTKXONES
:EFB
MM
»•*»•'
POTLATCH
COOK
ORIENTED
8TRANDBOARO
920
1/4-1 1/4
ASPEN
4
HEL8OI06-M
105
at
1200-IMO
225
4i-fiMt
Mt
2I.OOVDRYER
a-PASI
SUSPENSION
BURNER
8AWTRMI
FINES
20MMBTU/HREACH
*.SOOLBmRn>RYER
MULTKLONES
4 EFB'S
LIQUID PF
3M
POTLATCH. BEMIOJI
EX1STINQ EXPANSION
ORIENTED
STRANOBOAflO
320
1/4-) 1/4
ASPEN
4
HELSDIce-31
10
M
1200.1300
225
4»-«6% '
4-«H
M.OOWOHYER
3-PAS9
SUSPENSION
BURNER
SAWTRIU
FINED
20MUBTWHREACHi
».MWLB/HHIDRYER
MULTICLONE«
4 EFB'8
LIQUID PF
3H
ORIENTED
STRANDBOARD
400
1/4-1 1/4
ASPEN
3
MECI360
13
(0
MO
UNKNOWN
45-56%
4-SH
U.OOOWRYER
3-PAS8
WEU.ON8
SAWTRIU
BARK
IMMUBTUmR
15.000 LB/HR
UULTKXONES
3 EFB'S
LIQUID PF
3H
POTLATCH
8RANO RAPIDS
ORIENTED :
8THANO9OABP
210:
1/4-11/4
ASPEN:
4
HM.8D1S9-42
u
4J
1300
2BO-MO
4S-5M*
3%
30.PQO/DRYER '
:»4>ABa:
•USPENSIQN
BURNER
SAW TRIM
FINES
UULTKLPNEa
ECONOMKER
POWDER PF
J-3H
NORTHWOOD
BEUIDJI
ORIENTED
STHANDBOARD
420
•1/4-1 1/4
ASPEN
2
UEC I24OT
12
4B
1700-1800
280
4S-«ew
3H
47.500/DRYER
3-PASS
2 LAMB BURNERS
HOaOED FUEL
40 MM BTU/HR EACH
22.000 LB/HR/DRYER
UULTICLONES
2 EFB'S
LIQUID PF
3*
UlcUlLIAN-
BLOEDEL
ALUQNEO
FIBERBOARD
430
AfifCN
2
RADERBELCHT
14
M
4S-SC*
MM
SMBLE-fASS
WEUOW
BARK
WOQO WASTE
1 23 MU BTU/HR EACH
M.OOO LB/HR/DRYER
UULTICLONES
2EFB'8
MOI
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Table 1. Summary of operating characterics for reconstituted panelboard plants in Minnesota.
PRESS PLATEN DIMENSIONS
AND NUMBER Of OPENINGS
PRESS TEMPERATURE
PRESS CYCLE TIME (MIN)
HEAT SOURCE FOR PRESS
FUEL
RATED INPUT BTU/HR
CONTROL DEVICE
•UPERWOOO
DULUTH
4X1(20)
4XMO2)
»tnx»t«»
• i/axi«oo)
m •
4
iwwaw
OL. HOMED FUEL
ESP
•UPERWOOO
•EMIOJI
4XB|20|
400
4
•OUR .
•ARK
•OUU BTU/HR
NONE
L-P
TWO HARBORS
IXt«|l)
4W
4
KONUS
i WOOD WASTE:
SI MM BTU/HR
BAOHOUSE
POTLATCH
COOK
4 124 (22)
400
**
2 KEELER BOLER8
WOOD WASTE
72 MM BTU/HR EACH
VENTURI SCRUBBER
POTLATCH. BEMIDJI
EXISTINa EXPANSION
4X24(22) 1X24 (10)
400 400
M 2-B
2KEELSHKH.ER* WELLON8
WOOO WASTE WOOD WASTE
T2MUBTUHHEACH t» MM BTU/HR
VENTURI SCRUBBER : EFB
POTLATCH
« HAND RAPIDS
1X21(12)
400
M
2 BOMR8
NATURAL OAS
SOMMBTUnWEACH
NONE
NORTHWOOO
BEMIOJI
1X24(14)
400
2-1
2 KONUS BURNERS
WOOO WASTE
20 MU BTU/HR
EFB
MarMI 1 IAN-
BLOEDEL
299
M
WEU.QNS
WOOD WASTE
tOOMUeTWHR
EFB
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2.1.1 Hardboard Manufacturing Process
Two of the plants visited, Superwood in Duluth and Bemidji,
manufacture hardboard. The processes used by each plant are
entirely different. The Bemidji plant produces hardboard using a
dry process to produce and bind wood fibers into a reconstituted
panel. The plant in Duluth, on the other hand, uses a wet
pulping process to produce an aqueous slurry containing wood
fibers that, with the addition of a binder and dewatering,.are
pressed into hardboard. The following is a general discussion of
each plant's process.
2.1.1.1 Dry Process. The Superwood plant in Bemidji uses a
dry process in which the wood is chipped, conditioned in a steam
cooker at 200°F, ground into fibers, and mixed with
phenol/formaldehyde (PF) resin at 2 percent by weight. The
resinated wood fibers are dried in a single-pass, gas-fired,
flash tube dryer to between 8 to 9 percent moisture. The dried,
resinated fibers are then formed into a mat and pressed at 400°F
for 2 to 4 minutes (min) to form 1/8- to 1/4-inch (in.)
hardboard. Approximately 25 percent of the hardboard
manufactured is further processed by tempering with linseed oil
to create a hard, smooth surface. The linseed oil is applied to
all outer surfaces of the hardboard and cured in a 310°F oven for
approximately 3 hours (hr). Exhaust from the tempering oven is
controlled by a venturi scrubber and a packed-bed scrubber.
Caustic is added at the venturi to raise the pH to about 10. The
gas then passes through an aqueous, packed-tower scrubber, where
approximately 1 pound per hour (Ib/hr) of potassium permanganate
is added to oxidize odor-causing compounds exiting the tempering
oven. The spent scrubber water containing magnesium oxide is
then sent to the municipal sewer system.
2.1.1.2 Wet Process. The plant in Duluth uses a wet
process similar in some ways to that used in paper manufacture.
The plant receives wood chips from which, through a pulping
process, it creates an aqueous fiber slurry. Approximately
1.5 percent PF resin is added to the slurry. The slurry
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composition is controlled to maintain 2 percent solids, after
which it is applied to a screen on which it forms a mat. The
screen and mat are sent to a 3S5°F press that compresses and
binds the fibers and squeezes out the water to form hardboard.
The water squeezed from the mat is captured in a basin below the
press and sent to an evaporator. Here the water is distilled off
in a closed-loop system, leaving behind a viscous, molasses-like
solution containing the water-soluble wood resins, wood sugars,
and other extractable wood components. This material is
presently sold to livestock feed producers for incorporation into
their feed mixture. The entire heat requirement for the plant is
supplied by five boilers. Three of the boilers are wood fired
and are controlled by an electrostatic precipitator. The other
two boilers are fossil fuel fired and are not controlled.
2.1.2 Oriented Strandboard Manufacturing Process
The remainder of the plants in Minnesota manufacture a
waferboard product known as OSB. The overall process for
manufacturing OSB is generally the same for all of the plants,
although some differences in equipment and processing the final
product exist. The fundamental processing steps involved in
producing OSB are as follows. Logs fed to the process are cut to
100 inches in length by a slasher saw and put in a hot pond. The
hot pond, maintained at a temperature between 80° and 120°F (27°
to 49°C), pretreats the logs for waferizing by thawing them
during winter operations. The logs are debarked and carried to
stationary slasher saws where they are cut into 33-in. lengths in
preparation for the waferizer. The waferizer slices the logs
into wafers about 0.028 in thick. The wafers are then conveyed
to the wet wafer storage bin to await processing through the
dryers.
The dryers are usually fired by wood wastes from the plant
but sometimes by oil or natural gas. When meth'ylene diphenyl
diisocyanate (MDI) resin is used in the blending process, the
wafers are dried until their moisture content is 8 to
10 percent. When phenolic resin is used in the blending process,
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the wafers are dried to 4 to 5 percent moisture. The dried
wafers are pneumatically conveyed from the dryer, separated from
the gas stream at the primary cyclone, and transferred onto a
rotary screen. The gas stream continues through a multiclone,
I.D. fan, and sometimes a tertiary pollution control device
(i.e., electrified filter bed [EFB], wet electrostatic
precipitator [ESP]) and then is discharged through a stack into
the atmosphere. A rotary screen further classifies the wafers by
removing the fines. The undesirable fine material is sent to a
fuel preparation system for the dryer burner, and the screened
wafers are stored in dry bins. The wafers are then conveyed to
the blender, where they are blended with the resin. The
resinated wafers then go to formers, where they are metered out
on a continuously moving screen system. The continuous formed
mat is then separated into desired lengths by a traveling saw,
passed to the accumulating loader, and sent to the press. The
press applies heat and pressure to activate the resin and bond
the wafers into a solid sheet of waferboard. The bonded sheet is
then trimmed to final dimensions, sprayed on the edges with a
protective coating, and packaged for shipping.
2.1.3 Aligned Fiberboard Manufacturing Process
The MacMillian-Bloedel plant under construction in Deerwood,
Minnesota, will produce aligned fiberboard. The processes used
in the production of aligned fiberboard are very similar to those
used to produce OSB.. However, some differences do exist between
the aligned fiberboard plant under construction and the existing
OSB facilities in Minnesota. One difference is that the aligned
fiberboard-plant will produce wood strands 12-in. long and
0.030-in. thick as opposed to OSB flakes that generally do not
exceed 3.5-in. in length and are about 0.028-in. thick. In
addition, the strands at the aligned fiberboard plant will be
dried in one of two single-pass rotary drum dryers as opposed to
the triple pass dryers used at OSB plants. The MacMillian-
Blaedel plant will also recycle a portion of the dryer exhaust
gases and mix them with the incoming hot gases from the dryer
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heat source. In theory, this recycle stream should minimize the
dryer inlet temperature, thus decreasing the amount of VOC's
generated. The recycling of dryer exhausts was not observed at
any of the OSB mills in Minnesota.
Another unique process to be used at the macMillian-Blaedel
plant is the direction injection of steam into the mat as it is
being pressed to aid the polymerization of the MDI resin. The
use of direct steam injection will theoretically result in lower
press temperatures, thus, lower VOC emissions. In addition,
steam and other gases released from the press will be sent to a
condenser before exiting to the atmosphere.
2.2 EVALUATION OF EMISSION SOURCES
The evaluation of air toxics emission sources in Minnesota's
reconstituted panelboard industry focuses on identifying the
similarities and differences among the process variables known or
suspected to have a significant impact on air toxics emissions.
The plants are compared to identify those of similar design and
operation and then group them together in a test plan to minimize
the amount of testing required to characterize air toxics
emissions from all of the plants. In addition, testing plants
that differ in design and operation separately may shed some
light on the relationship between key process variables and air
toxics emissions.
As mentioned in the previous section, because of the
differences in the processes used in producing hardboard, OSB,
and aligned fiberboard the air toxics emissions evaluation of the
plants producing these three products will be separated. The
information that follows presents the rational' by which sources
within each plant were grouped for the purposes of evaluation and
testing.
2.2.1 Hardboard Manufacturing Plants
As mentioned earlier, the manufacturing processes and
technology used to process hardboard at the two Superwood plants
in Minnesota differ greatly. The dry process employed by the
Superwood plant in Bemidji has the following four sources of
8
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potential air toxic emissions: (1) wood fiber dryer, (2) press
vent, (3) tempering oven, and (4) boiler.
The primary emission points of concern in this process are
the flash tube dryer stack, the press vent exhaust, and the
tempering oven exhaust. The flash tube dryer is of particular
concern because the wood fibers are coated with PF resin before
they are dried. Thus, resinated fibers enter the 200° to 400°F
dryer, suggesting that free formaldehyde and phenol may be
volatilizing and exiting the dryer exhaust. Also, the tempering
oven exhaust may be releasing compounds present in the linseed
oil as well as free formaldehyde, phenol, and other organic
components of the composite panelboard.
The Superwood plant in Duluth uses a wet process and
therefore does not dry its wood fibers. The sources potentially
contributing to air toxics loading from Superwood's plant in
Duluth are press vents and boilers.
With the exception of the boilers, which are considered to
be similar, these sources should be evaluated independently for
air toxics emissions. The presses operate in a similar fashion
at both plants, except the press at the Ouluth plant squeezes
large quantities of water from the wet mat. It is uncertain what
effect the presence of large quantities of water in the mat has
on air toxics emissions from the press vents. Consequently,
press vents from both hardboard mills should be tested to
determine if significant differences exist in the air toxics
emissions from press vents in wet versus dry-process hardboard
mills.
2.2.2 OSB Manufacturing Plants
As mentioned previously, all of the OSB manufacturing plants
visited used similar technology and processes to manufacture
their product. Within each plant are three primary sources of
potential air toxic emissions: (1) wood flake dryers, (2) press
vents, and (3) steam or hot oil generators (boilers, Konus, and
Wellons combustion units). The following is a summary of the
information obtained on these sources from available literature
and plant visits.
q
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2.2.2.1 Wood Flake Dryers. Dryer configurations and
operations vary from plant to plant. The typical dryer, however,
accomplishes a tremendous amount of work in a relatively short
time, in a relatively small space, and within rather demanding
limits. At the same time, unacceptable emissions can be
generated that are to a large degree a function of the wood
species being dried. In addition, dryer temperatures, dryer
loading rates, and dryer design also affect pollutant emission
rates. The OSB plants in Minnesota are similar in that they all
process aspen as their primary raw material. Each OSB plant also
uses triple-pass, rotary drum dryers to dry its wood flakes.
However, the dryer inlet temperature in which the flakes become
exposed varies between 860° and 1800°F, resulting in what is
expected to be significant variations in the organic species
emitted, particularly in the condensable fraction. The
quantitive relationship between inlet dryer temperature and total
gaseous nonmethane organic emissions (TGNMO) is not well
defined. Nonetheless, some of the data currently available
suggests that TGNMO emissions rise steeply as dryer inlet
temperatures exceed 900°F.1 It is also possible that some
variation in TGNMO emissions may be the result of differences
inherent to the drying equipment used. Similar triple-pass
dryers manufactured by different vendors may exhibit different
emission characteristics. At this time, little data exists that
is suitable for providing this type of a detailed comparison..
All of the OSB plants, with the exception of Potlatch's mill
in Grand Rapids, use EFB's to control particulate emissions from
the dryer exhaust. The EFB is a dry type of collection device
and is not expected to significantly reduce TGNMO emissions from
the dryers.2 The Potlatch mill in Grand Rapids, in contrast,
controls emissions from the dryer exhaust with an economizer.
The economizer is a device whose primary function is to recover
heat from the dryer exhaust and use it to heat the work space and
thaw ponds. The heat transfer in the economizer is accomplished
in two stages. The first stage is a glycol heat exchanger that
-------
recovers heat from the hot dryer exhaust and distributes it
throughout the plant to heat the work space. The second stage is
a spray chamber where thaw-pond water is brought into direct
contact with the warm dryer exhaust, which heats the water and
returns it to the thaw pond. The cooling of the dryer exhaust
gases from 280°F to approximately 130°F allows more organic
material to condense and be scrubbed out in the spray chamber.
For the purpose of evaluating emissions from wood flake
dryers, MR I has segregated the plants in Minnesota based on the
similarities and differences noted in Table 1 and the effect
these factors are expected to have on air emissions. One group
consists of the Potlatch plants in Cook and Grand Rapids and the
existing plant in Bemidji (i.e., exclusive of the expansion).
All three of these plants use similar triple-pass dryers that are
heated by suspension burners. Their inlet dryer temperatures are
similar, ranging between 1200° and 1300°F. Also, each plant
dries aspen wood flakes down to a moisture content of between 3
'and 5 percent.
The remaining three plants (i.e., Louisiana-Pacific,
Northwood Panelboard, and the Potlatch expansion in Bemidji) have
significantly different dryer inlet temperatures that suggest
they should each be evaluated separately. Louisiana-Pacific's
plant operates its dryer at an inlet temperature of approximately
1000°F and dries its aspen flakes down to only 9 percent
moisture. As mentioned previously, the higher moisture content
of Louisiana Pacific's wood flakes can be tolerated in its
product because it uses MOI resins to bind the wood flakes. When
operating, Potlatch's expansion in Bemidji will dry wood chips at
the considerably lower temperature of 860°F. Finally, Northwood
Panelboard dries its aspen flakes at an uncharacteristically high
temperature of between 1700° to 1800°F at the inlet to the
dryer. It is anticipated that variations in dryer inlet
temperature and final moisture content of the dried flakes will
have a significant impact upon the air toxics emitted from the
dryer exhaust.
J..L
-------
2.2.2.2 Press Vents. The hot press is the manufacturing
step that cures the resin, bonding the wood flakes into a
reconstituted panel. Formaldehyde emissions from the press
depend on the type of bonding resin, the press temperature, and
the press cycle time.3 Maximum emissions during the board-
pressing operation occur at the end of the press cycle, when the
press is opened slightly to release steam and trapped vapors. As
the press opens further, the entire hot surface of the newly
pressed hot boards is exposed, releasing more vapors that are
then drawn up through the press vents by high-volume exhaust
fans.
Most of the OSB plants in Minnesota use a liquid PF resin.
One plant uses a powdered PF resin, and another is using MDI to
bind the wood flakes. Liquid PF resins generally have from 0.1
to 0.3 percent free formaldehyde, while powdered PF resins have
from 1 to 3 percent free formaldehyde. One study has shown that
between 5 and 15 percent of the free formaldehyde in the PF resin
is emitted"during the pressing and board-cooling operation. It
should be noted, however, that a plant using liquid PF resin
normally uses about twice as much resin per ton of product as a
plant using powdered PF resin. As a result, one may conclude
that about five times less formaldehyde may be emitted when
liquid PF resin is used to bind wood flakes.
All of the OSB presses operate at a temperature between 380°
and 400°F. The press cycle time is primarily a function of the
thickness of the panel being produced. Thicker panels require
longer press times to completely cure the resins in the core of
the panel.- The presses at these mills are capable of producing
panel boards of various thickness ranging between 1/8 to
1 1/4 in.
For the purpose of evaluating emissions from press vents,
the subject plants can be classified into three groups. One
group will consist of all of the OSB plants that use liquid PF •
resins to bind the wood flakes together. This group includes all
of the OSB plants in Minnesota, except Potlatch's plant in Grand
-------
Rapids and Louisiana-Pacific's plant in Two Harbours. These
plants all use liquid PF resins in similar quantities and at
similar press temperatures. Potlatch's plant in Grand Rapids
V
uses powdered PF resin to bind the wood flakes and should be
evaluated separately for reasons indicated above. Louisiana-
Pacific's plant uses MDI resin as a binder. In addition, the
plant covers one side of the mat to be pressed with a PF resin-
impregnated paper, which gives their final product, architectural
siding, better weather resistance. Consequently, press vent
emissions from the Louisiana-Pacific plant should be evaluated
independently.
2.2.2.3 Steam- or Hot Oil-Generating Units. All of the OSB
plants in Minnesota require steam or hot oil to heat the presses,
hot ponds, and buildings. The hot oil or steam is produced in
boilers and specialized combustion units equipped with heat
exchangers designed to maximize the heat transfer efficiency
between the hot combustion gases on the shell side and the water
or oil on the tube side. For the most part, these mills use wood
waste generated in the process as fuel to the combustion units.
Occasionally, for short periods of time, plants may revert to
natural gas as fuel to heat the combustors. In a very few
instances, a plant may rely completely on fossil fuel such as
fuel oil to fire boilers or other combustion equipment. Of the
OSB mills in Minnesota, three use boilers and three use or are
installing Konus or Wellons wet-cell burners.
With the possible exception of particulates, carbon
monoxide, and nitrogen oxides, these combustion units have not
received much attention as air pollution sources. These units
have not been the subject of VOC controls, although some of these
combustion units, as indicated in Table 1, have controls on
them. However, the controls are in place to remove solid
particulate and are not expected to have any significant impact
on the removal of air toxics compounds.
13
-------
2.2.3 Aligned Fiberboard Manufacturing Plant
As mentioned previously, MacMillian-Bloedel's aligned
fiberboard plant under construction in Deerwood will be very
similar in design to the OSB plants. The three air emission
sources discussed in the previous section for OSB plants will
also exist at the aligned fiberboard plant when completed.
However, significant differences will exist in-the design of the
dryers and the processes at the aligned fiberboard plant. The
single-pass dryers with exhaust recycle and the steam injection
press are atypical of equipment used at OSB mills in Minnesota.
Therefore, these sources will be evaluated independently.
3.0 PRELIMINARY AIR TOXICS EMISSIONS ASSESSMENT
Table 2 presents the list of 239 compounds currently being
regulated or being considered for regulation under Minnesota's
Air Toxic's Program. The compounds that are currently being
regulated are a composite of the 190 air toxics listed in the
Clean Air Act Amendments of 1990 and an additional 50 compounds
subject to the Superfund Amendments and Reauthorization Act
(SARA) Title III reporting requirements. In addition, 43 other
compounds are under consideration for inclusion on Minnesota's
air toxics list. Performing an accurate and reliable assessment
of air toxics emissions from reconstituted panelboard plants is
at this time a difficult task. The plants that manufacture OSB,
hardboard, and other reconstituted wood panelboards often exhibit
variations in their day-to-day operations that may dramatically
affect the amount of air toxic pollutants emitted to the
atmosphere. Even within a single plant, much of the data that
exists on the amount of air toxics and criteria pollutants
•
emitted, as observed by several compliance tests, is widely
scattered. In some cases these variations in emissions cannot be
accounted for; however, some experts have concluded that
inaccuracies in the various test methods and complex variations
in thermal decomposition products account for much of the scatter
in the present body of test data.
14
-------
TABLE 2. MINNESOTA'S AIR TOXIC LIST
Substance
CAS No.
AcetaIdehyde
Acetam i de
Acetone
Aceton i tr iIo
Acetophenone
2-AcetyI am i nofIuorene
Aero lain
Aery I am i de
Aery IIc acid
Aery I on i tr iIe
Allyl chloride
Aluminum (fume or dust)
Aluminum oxide
4-Aminobiphenyl
Ammonia
AniIine
An i s i d i ne
Antimony
Antimony Compounds
Arsenic and certain arsenic compounds
Asbestos (d)
Araosite
AnthophyI Ii te
Chrysotil
Crocidolite
Bar i urn
Barium Compounds
Benzene
Benz i d i ne
Benzotr i chI or i de
Benzoyl chloride
BenzoyI perox i de
Benzyl chloride
BeryI Ii urn
Beryl Iium compounds
Biphenyl
Bis(2-ethylhexyl)phthalate (OEHP)
B i s(chIorometh yI)ether
BIS(2-chioro-1-methyIethy I)
Bromoform
1,3-8utadiene
n-8utyl alcohol-
sec-Butyl alcohol
tert-SutyI a IcohoI
1,2 Butylene oxide
Cadm i urn
Cadmium compounds
Calcium cyanamide
Caprolactam
Captan
75-07-0
60-35-5
67-64-1
76-06-8
98-86-2
53-96-3
107-02-8
78-06-1
78-10-7
107-13-1
107-05-1
1344-28-1
92-67-1
7664-41-7
62-53-3
29191-52-4
7440-36-0
12172-73-5
17068-78-9
12001-29-5
1200^-28-4
7440-39-3
71-43-2
92-87-5
98-07-7
98-88-4
94-36-0
100-44-7
7440-41-7
92-52-4
117-81-7
542-88-1
108-60-1
75-25-2
106-99-0
71-36-3
78-92-2
75-65-0
106-88-7
7440-43-9
156-62-7
105-60-2
133-06-2
(continued)
15
-------
TABLE 2. (continued)
Substance
CAS No.
Carbaryl
Carbon d i suIf i de
Carbon tetrachloride
Carbonyl sulfide
Catechol
ChIoramben
Chlordane
Chlorinatee fluorocarbon
Chlorine
Chlorine dioxide
Chloroacetic acid
ChIoroacetophenone
ChIorobenzene
ChIorobenz iI ate
Chloroform
Chloromethyl methyl ether
B-Chloroprene
Chromium
Chromium Compounds
Cobalt
Cobalt compounds
Coke oven emissions
Copper
Cresol-cresylic acid
CresoI-cresyIi c ac i d
Cresol-cresylic acid
Cresol-cresylic acid
Cumene
Cyanides
Cyclohexane
2,4-0
DOE
Oiazomethane
Dibenzofurans
1,2-Oibroroo-3-chloropropane
Dibutyl phthalate
OichIorobenzene
m-0i chIorobenzene
o-OIchIorobenzene
p-0 i chIorobenzena
3,3' -Oichlorobenzidine
1,1-01 chIoroethane
Dichloroethyl ether
Oichloropropene
Oichlorvos
Oiethanofamine
Oiethyl phthalate
Oiethyl sulfate
3,3-0imethoxybenzidine
0 i methyI am i nobenzene
0imethyl aniIine (N,N-OimethyIaniIine)-
63-25-2
75-15-0
56-23-5
463-58-1
120-80-9
133-90-4
57-74-9
76-13-1
7782-50-5
10049-04-4
79-11-8
532-27-4
108-90-7
510-15-6
67-66-3
107-30-2
126-99-8
7440-47-3
7440-48-4
7440-50-8
1319-77-3
95-48-7
108-39-4
106-45-5
08-82-8
151-50-8;
110-82-7
94-75-7
3547-04-4
334-88-3
132-64-9
96-12-8
84-74-2
25321-22-6
541-73-1
95-50-1
106-46-7
91-94-1
75-34-3
111-44-4
542-75-6
62-73-7
111-42-2
84-66-2
64-67-5
119-90-4
60-11-7
121-69-7
143-33-9
(continued)
16
-------
TABLE 2. (continued)
Substance
CAS No.
3,3-0imethyl benzidine
Dimethyl carbamoyl chloride
OimethyIformamide
1,2-OimethyIhydrazine
2,4-0imethyl phenol
OimethyIphthalate
Dimethyl sulfate
Dinitro-o-cresol
2,4-Oinitrbtoluene
1,4-Oioxane
1,2-0 i phenyIhydraz i ne
Di-sec-octyl phthalate
Epichlorohydrin
1,2-Epoxybutane
2-Ethoxyethanol
Ethyl aery I ate
Ethyl benzene
Ethyl carbamae (Urethane)
Ethyl chloride
Ethylene
Ethylene dibromide
Ethylene dichloride
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Ethylenimine
Forma Idehyde
Glycol ethers
Heptachlor
HexachIorobenzene
HexachIorobutad i ene
HexachIorocycIopentad i ene
HexachIorethane
HexamethyIene dilsocyanate
Hexamethyl phosphoramide
Hexane (n-Hexane)
Hy.draz i ne
Hydrochloric Acid
Hydrogen chloride
Hydrogen cyanide
Hydrogen fIuor i de
Hydrogen suIfIde
Hydroquinone
Isophorone
Isopropyl alcohol
4,4-lsopropyIidenediphenol
Lead
Lead compounds, Inorganic
Lindane
Maloic anhydride
119-93-7
79-44-7
68-12-2
57-14-7
105-67-9
131-11-3
77-78-1
534-52-1
121-14-2
123-91-1
122-66-7
117-81-7
106-89-8
106-88-7
110-80-5
140-88-5
100-41-4
51-79-6
75-00-3
74-85-1
106-93-4
107-06-2
107-21-1
75-21-8
96-45-7 .
151-56-4
50-00-0
76-44-8
118-74-1
87-68-3
77-47-4
67-72-1
822-06-0
680-31-9
110-54-3
302-01-2
7647-01-0
7647-01-0
74-90-8
7664-39-3
7783-06-4
123-31-9
78-59-1
67-63-0
80-06-7
7439-92-1
58-89-9
108-31-6
(continued)
17
-------
TABLE 2. (continued)
Substance
CAS No.
Manganese
Manganese compounds
Mercury
Mercury compounds
Methoxychlor
2-MethoxyethanoI
MethyI aery I ate
Methyl alcohol
Methyl bromide
Methyl tert-butyl ether
Methyl chloride
Methyl chloroform
Methylene bisphenyl isocyanate (MOI)
Methylene chloride (dichloromethane)
4,4'-MethyIene bis(2-chloroaniIine)
4,4*-MethyIened i an iIi ne
Methylene diphenyI diIsocyanate (MOD
Methyl ethyl ketone (MEK)
MethyI i sobutyI ketone
Methyl isocyanate
MethyI methacryI ate
Naphthalene
Nickel
Nickel compounds
Nitric acid
Nitrobenzene
4-NitrodiphenyI
4-N i trod i pheny I
2-Nitrophenol
N-N i trosod i MethyI am i ne
N,N Oimethylaniline
N-N i troso-N-methyI urea
N-Nitrosomorpholine
Parathlon
PentachIoron i trobenzene
(Quintobenzene)
PentachIorophenoI
Peracetic Acid
Perch IoroethyIene
Phenol
p-Phenylene diamine
Phosgene
Phosphide
Phosphoric acid
Phosphorus
Phthalic anhydride
Polychlorinated bipheyls (Aroclors)
1,3 Propane sultone
Prop Iolactons
Proplonaldehyde
Proplonic acid
7439-96-5
7439-97-6
72-43-5
10-98-6
96-33-3
67-56-1
74-83-9
1634-04-4
74-87-3
71-55-6
101-68-8
75-09-2
1011-14-4
101-77-9
101-68-8
78-93-3
108-10-1
624-83-9
80-62-6
91-20-3
7440-02-0
7697-37-2
98-95-3
92-93-3
100-02-7
79-46-9
62-75-9
121-69-7
684-93-5
59-89-2
56-38-2
82-68-8
87-86-5
79-21-0
127-18-4
108-95-2
106-50-3
76-44-5
7803-51-2
7664-38-2
7723-14-0
85-44-9
1336-36-3
1120-71-4
57-57-8
123-28-6
79-09-4
(continued)
18
-------
TABLE 2. (continued)
Substance
CAS No.
Propoxur
Propylene
Propylene dichloride
Propylene oxide
1,2-Propylenimine (2-Methyl aziridine)
Pyr i d i ne
Ouinoline
-------
TABLE 2. (continued)
Substance
CAS No.
0 i cIorobromomethane
Oichlorodi fIuoromethane
Dichlorotetrafluoroethane
Ethyl alcohol
Fluorotrichloromethane, (see TrichIorofIuoromethane)
Methane
Petroleum distillates,
Mineral Spirits, Stoddard solvent,
VM&P naphtha
Platinum
VM&P Naptha
Acetic acid
n-Amyl acetate
n-8utyl acetate
2-9utoxyethanol
2-Butoxyethanol acetate
Carbitol
Carb i to I acetate
Butyl carbitoI
Butyl carbitol acetate
2-Ethoxyethanol acetate
Ethanolamina
Heptane Isomers
Hexane Isomers
Hydrogen peroxide
Isobutanol
I sopropyI acetate
2-Methoxyethanol acetate
MethyI n-amyI ketone
Methyl n-butyl ketone
MethyI IsoamyI ketone
Methyl propyl ketone
n-Propanol
Pentane
n-Propyl benzene
Propylene glycol
Potassium hydroxide
Other dioxins
Aliphatic naphtha
1,2 Oichoroethane
75-27-4
75-71-8
76-14-2
64-17-5
75-69-4
74-82-8
8002-05-9
7440-06-4
8032-32-4
64-19-7
628-63-7
123-86-4
111-76-2
111-15-9
141-43-5
7722-84-1
78-83-1
67-63-0
109-86-4
110-43-0
591-78-6
110-12-3
107-87-9
71-23-8
109-66-0
1310-58-3
107-06-2
20
-------
As a preliminary assessment of air toxics emissions, this
study will identify a variety of air toxics compounds suspected
to be released from the reconstituted panelboard plants in
Minnesota and the source(s) from which they are emitted. In
addition, a summary of the available test data validating and
quantifying the presence of these air toxics is presented.
3.1 PRODUCTS OF THERMAL DECOMPOSITION
For many years, the thermal decomposition of wood has been
recognized to release numerous organic compounds into the air.
Processes associated with manufacturing reconstituted panelboard
suggest that these mechanisms are likely to be major contributors
to air toxics loading from these mills. Table 3 presents a list
of identified prdducts from the thermal decomposition of Table 3
nonresinous woods at atmospheric pressure. These products
belong mostly to a few groups of related compounds as follows:
1. Acids (mostly of the acetic acid series);
2. Aliphatic alcohols;
3. Ketones (mostly of the acetone series);
4. Aldehydes;
5. Phenols and phenyl methyl ethers;
6. Ammonia derivatives; and
7. Hydrocarbons of the benzene, furan, and aliphatic
series.
Although the origin of all the products of thermal
decomposition cannot be assigned to individual components of the
original wood, each of the major components yields characteristic
decomposition products. For example, furans result from
pyrolysis of pentoses, and an assortment of aromatic substances
result from pyrolysis of ligin. The origin of much of the acetic
acid is attributed to the thermal decomposition of acetyl groups
in wood. Formaldehyde is thought to form as wood strands become
charred and release unoxidized carbon that combines with water.
Other mechanisms may exist for the formation of formaldehyde, but
this is thought to be the major pathway. At elevated
temperatures, secondary reactions of many types take place. Not
only do final products represent a wide variety of substances,
21
-------
TABLE 3. PRODUCTS RELEASED FROM THERMAL DECOMPOSITION OF WOOD
Carbon monoxide
Carbon dioxide
Hydrogen
Water
T^glic acid
A -Pentenoic acid
y-valerolactone
n-Valeric acid
Methylethylacetic acid
n-Caproic acid
Isocaproic acid
n-Heptoic acid
Lignoceric acid
Furoic acid
Methyl alcohol*
Ethyl alcohol*
Allyl alcohol
Propyl alcohol*
Methyl vinylcarbinol
Isobutyl alcohol*
Isoamyl alcohol
Formaldehyde*
Acetaldehyde*
Propionaldehyde*
Valeraldehyde
Isovaleraldehyde
Trimethylacetaldehyde
Furfural
5-Methylfurfural
Hydroxymethylfurfural
Methylal
Dimethylacetal
Acetone*
Methyl ethyl ketone*
Diacetyl
Methyl propyl ketone*
Methyl isopropyl ketone
Diethyl ketone
Ethyl propyl ketone
Formic acid
Acetic acid*
Propionic acid*
Crotonic acid
iso-Crotonic acid
A -Hexenone-2
Methyl n-butyl ketone
3,6-Octanedione
2-Acetylfurane
Cyclopentapone
2-Methyl-A -cyclopentenone
Methylcyclopentenolone
Cyclohexanone
Methylcyclohexenone
DimethyIcyclohexenone
Phenol*
o-, m-, and p-Cresol*
o-Ethylphenol
2,4-DimethyIphenol*
3,5-Dimethylphenol
Catechol*
Guaiacol
2-Methoxy-4-methyIphenol
2-Methoxy-4-vinylphenol
2-Methoxy-4-ethylphenol
2-Methoxy-4-propyIphenol
1,2-Dimethoxy-4-methylbenzene
2,6-Dimethoxyphenol
2,6-Diraethoxy-4-methyIphenol
2,6-Diraethoxy-4-propylphenol
Propylpyrogallol mono-methyl
ether
Coerolignol
Eupittonic acid (or eupitton)
Methacrylic acid
Y-Butyrolactone
n-Butyric acid
iso-Butyric acid
Angelic acid
2-Methylfurane
3-Methylfurane
Dimethylfurane
2,5-Dimethyltetrahydrofurane
(continued)
22
-------
TABLE 3. (continued)
Trimethylfurane
5-Ethyl-2-methyl-4,5- 1,2,4,5-Tetramethylbenzene
dihydrofurane Chrysene
Coumarone Ammonia
Pyroxanthone Methylaraine
Benzene* Dimethylamine
Trimethylamine
Toluene* Pyridine*
Isopropylbenzene 3-Methylpyridine
m-Xylene* Dimethylpyridine
Cymene
Naphthalene*
Methane*
Heptadecane
Octadecane
Eicosane
Heneicosane
Docosane
Tricosane
Furane
*Compounds that are also on Minnesota's air toxics lists.
23
-------
but also the varying proportions of these substances depend upon
the conditions during the decomposition reactions.
Of the compounds listed in Table 3, an asterisk denotes
those that are included on Minnesota's current listing of toxic
air pollutants. It is these compounds that our preliminary
emissions assessment will focus on. However, it must be kept in
mind that Table 3 lists the compounds released from the thermal
decomposition of nonresinous species. Consequently, compounds
belonging to the family of terpenes, known to be present in
appreciable amounts in conifers and other resinous species, are
conspicuously missing from this list. Their omission may be of
no real consequence, since terpenes do not appear on Minnesota's
list of toxic air pollutants and plants in Minnesota primarily
process aspen, a nonresinous hardwood.
3.2 SUMMARY OF AVAILABLE AIR TOXICS TEST DATA
To date, relatively little air toxics testing has been done
at reconstituted panelboard plants. No comprehensive test
programs have been undertaken to identify and quantify all of the
air toxics pollutants emitted from these facilities. However, a
limited number of tests have been conducted that measured
formaldehyde and phenol emissions from wood flake dryer stacks
and press vents. Emissions of MDI from press vents have also
been tested at a few plants that use MDI resins as a binder. The
information that follows is a summary of the available literature
on air toxics emissions from each source.
3.2.1 Wood Flake Dryers
The National Council for the Paper Industry for Air and
Stream Improvement (NCASI) has recently released a summary
document of gaseous emission measurement data for reconstituted
building board plants. The NCASI is a trade association that
represents, along with those of the pulp and paper industry, the
interests of the reconstituted wood products industry. The data
summary was prepared by obtaining air toxics test data from 16 of
its member plants. Table 4 lists the dryer design charac-
teristics reported by the participating plants and their measured
24
-------
Table 4. Design Characteristics and Formaldehyde Emission Rates From Dryers Surveyed By NCASI
Product
OSB
OSB
Waferboard
Waferboard
Waferboard
Particleboard
Particleboard
Particleboard
Particleboard
Waferboard
Waferboard
OSB
OSB
Waferboard
Particleboard
Particleboard
Flakeboard
Particleboard
OSB
OSB
Wood
Species
Aspen
Aspen
Poplar
Poplar
Poplar
D. Fir
D.Fir
D. Fir
D.Fir
Pine/Poplar
Poplar
S. Pine
S. Pine
Aspen
Aspen/Pine
Aspen/Pine
L Pine/Cttnwd
L. Pine
S. Pine/HW
S. Pine/HW
Dryer
Mfg
Hell
Heil
MEC
MEC
Heil
MEC
MEC
MEC
MEC
MEC
MEC
unk.
unk.
MEC
Hell
MEC
MEC
Rader-Th.
Aeroglide
Aeroglide
Dryer
Type
Triple-pass
Triple-pass
Triple-pass
Triple-pass
Triple-pass
Triple-pass
Triple-pass
Triple-pass
TripJe-pass
Triple-pass
Triple-pass
unk.
unk.
Triple-pass
Triple-pass
Triple-pass
Triple-pass
Single-pass
Triple-pass
Triple-pass
t
Fuel
Wood dust/propane
Wood dust/propane
Wood fines
Wood fines
Wood fines/IP gas
Sander dust
Sander dust
Sander dust
•Sander dust
Wood fines
Wood fines
Wood dust
Gas
Hogged bark
Sander dust/gaa
Sander dust/gas
Wood dust
Wood dust
Wood dust
Wood dust
Design
Heat
Input
MMBtu/hr
40
40
*4.5
44.5
43
unk.
unk,
unk.
unk.
44.5
44.5
unk.
unk.
45
:'<: 20..".
10
50
20
37
unk.
Dryer,
Inlet Average
Temp Form. Emissions
Deg. F. ppm Ib/ton OF
NR
1260
1000
1100
900
300
365
637
620
1270
1240
1120
990
1650
803
365
1200
713
816
960
238
66
100
98
26
0.3
3.8
0.5
0.3
73
44
7.6
5.2
82
9.1
0.7
83
6.6
3.5
1.9
0.6
1.6
1.2
0.58
0.004
0.029
0.006
0.004
1
0.67
0.13
0.11
0.65
0.05
0.02
0.81
0.03
0.07
0.027
-------
formaldehyde emissions rates as reported by NCASI. Formaldehyde
concentrations in the stack ranged between 0.3 and 238 parts per
million (ppm). Formaldehyde emissions ranged between 0.004 and
1.9 Ib/ton dry wood flakes. There is a considerable amount of
scatter in the data, but some general trends were observed. The
NCASI report noted that formaldehyde emission rates increased
with dryer inlet temperature. Dryers processing hardwood or a
mixture of hardwood and softwood species had a moderate-to-
dramatic increase in formaldehyde emissions at dryer inlet gas
temperatures greater than 800°F, but dryers processing softwood
species had only a slight increase in formaldehyde emissions with
increasing temperatures.
Some additional data obtained from Interpol Laboratories on
tests run on three mills processing aspen to produce OSB are
presented in Table 5. '' Two of the plants, Louisiana-Pacific's
plants in Kremmling and Montrose, Colorado, have dryer inlet
temperatures between 1500° and 1800°F. The average formaldehyde
emission factor calculated from these plants is 0.95 Ib/ton
finished product. The remaining test result obtained from
Interpol was for a test run on a wood flake dryer in Sagola,
Michigan. The dryer at this plant operated with an inlet
temperature of 900°F resulting in an average calculated emission
factor of 0.48 Ib/ton finished product. The data obtained from
Interpol supports the notion that increasing the dryer inlet
temperature results in an increase in formaldehyde emissions.
Table 6 presents a summary of three tests conducted to
measure the amount of phenol released from wood flake dryer
exhausts at waferboard plants.6'7 The phenol emission rates
ranged between 0.043 to 0.072 Ib/hr. Phenol emission factors
from these three tests ranged between 0.0078 to 0.0103 Ib/ton of
finished product. One of the mills tested was the Potlatch
facility in Cook, Minnesota. The phenol emission factor
calculated from testing at this plant is 0.0078 Ib/ton finished
product. This emissions factor can be applied to Potlatch's
plant in Bemidji (exclusive of the expansion) and Potlatch's
26
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TABLE 5. SUMMARY OF FORMALDEHYDE TESTS ON WAFERBOARD DRYERS
CONDUCTED AT PLANTS IN COLORADO AND MICHIGAN6'7
Plant
Location
Formaldehyde
emissions rate,
Ib/hr
Process
rate/
ton FP/hr
Formaldehyde
emissions
factor,
Ib/ton FP
Kremmling, Colorado
Montrose, Colorado
Montrose, Colorado
Montrose, Colorado
Average
Sagola, Michigan
Run 1
Run 2
Run 3
Average
7.25
4.37
9.61
9.58
3.7
4.4
4.3
7.5
7.0
7.9
8.8
8.6
8.6
8.6
0.97
0.63
1.21
0.98
0.95
0.48
27
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TABLE 6. SUMMARY OF PHENOL TEST RESULTS AT WAFERBOARD PLANTS
6,7
v Phenol Process Emissions
Plant emissions rate, factor,
location rate, Ib/hr tons FP/hr Ib/ton FP
Cook, Minnesota 0.043 5.5 0.0078
Montrose, Colorado 0.071 7.0 0.0103
Kremmling, Colorado 0.072 7.5 0.0096
Average 0.0092
28
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plant in Grand Rapids because of the similarity in dryer inlet
temperatures.
3.2.2 Press Vents
Air toxics are released from press vents as compounds
present in the resin binder volatilize upon heating and are swept
out through the press vent exhaust. With the exception of one
plant that uses MDI resins, all of the plants in Minnesota use PF
resins as a binder. Of these, only one uses PF resins in the
powder form; the others use the liquid form. The NCASI has
published a summary of data obtained from seven mills on the
emission rate of formaldehyde from press vents at plants using PF
resins.** The formaldehyde emission rates reported at seven mills
ranged from between 0.033 and 0.58 pounds per 1,000 square feet
(Ib/MSF) adjusted to a 3/4 in. thickness basis. It is not
possible to determine from the information supplied in the NCASI
study whether the mills used liquid or powder PF resins. Also,
no information was supplied on the formaldehyde content of the
resin's. Nonetheless, NCASI reported that no relationships were
evident that linked the formaldehyde content of the resins or the
form of the resin (liquid or powder) to the formaldehyde
emissions reported by the mills.
Table 7 summarizes formaldehyde test data from four
waferboard plant press vents using PF resins to bind the wood
flakes as reported by Interpol Laboratories.6'7 It is uncertain
from the information provided what form of PF resin was used by
the plants or what the formaldehyde content of the resins was at
the time of the tests. The average emission factor for
formaldehyde in these tests is 0.28 Ib/ton of finished product.
Formaldehyde and MDI emission rates were reported to NCASI by
three mills -that use MDI resins. The formaldehyde emission rates
reported from these mills ranged between 0.01 to 0.07 Ib/MSF on a
3/4-in. thickness basis. The MDI emissions reported by these
mills ranged between 0.0 and 0.01 Ib/MSP on a 3/4-in. thickness
basis.
29
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TABLE 7. SUMMARY OF THE FORMALDEHYDE TESTING
ON PRESS VENTS AT WAFERBOARD PLANTS
Plant
location
Formaldehyde
emissions
rate, Ib/hr
Process
rate,
ton FP/hr
Formaldehyde
emissions
factor,
Ib/ton FP
Kremmling, Colorado
Montrose, Colorado
Dungannon, Virginia
Dungannon, Virginia
Hayward, Wisconsin
Hayward, Wisconsin
Average
2
2
1,
,40
,59
,83
2.27
3.32
1.99
7.5
7.2
6.8
8.3
11.7
10.4
0.32
0.36
0.27
0.27
0.28
0.19
0.28
30
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3.2.3 Combustion Units
Very little if any data are available on the release of air
toxics from boilers, Konus, Welons, or similar wood-fired
combustion systems used to generate steam or hot oil at
waferboard or other reconstituted panelboard plants. Two studies
prepared by Interpol Laboratories attempt to quantify the
potential emissions of a few selected air toxics compounds from
these sources. ''• In these studies, air toxics emissions factors
were applied using data obtained from emissions tests on wood
flake dryers and boiler exhausts. The factors used to estimate
the potential to emit air toxics in the study are not considered
to be representative of the sources to which they were applied.
The release of extractable material from drying wood flakes
results in an emission factor that overestimates air toxics when
applied to heat sources alone. As a result, emissions from wood
flake dryer exhausts do not accurately reflect emissions from
heat sources in these plants. Also, emission factors derived
from tests conducted at wood-fired boiler are questionable
because fuel fed to the boiler consisted of approximately
50 percent shredded railroad ties. There is reason to believe
that the presence of creosote in the shredded railroad ties may
significantly affect the results of air toxics measurements made
during these tests. None of the above emission factors used in
Interpol's air toxics study are likely to be good indicators of
actual air toxics emissions from the heat sources in waferboard
plants. Interpol's use of this data in their air toxics
emissions evaluation further suggests that a lack of suitable air
toxics emissions data is available for these sources.
4.0 AIR TOXICS TESTING STRATEGY
To date, there has been no comprehensive air toxics testing
done on reconstituted panelboard plant emissions. The emissions
tests that have been done focus on quantifying the emissions of
only a few known compounds, mainly formaldehyde, phenol, and
MOI. As a result, no data are available that quantify the full
spectrum of possible air toxics emissions from sources in
reconstituted panelboard plants.
31
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The following test strategy has been developed to obtain a
more comprehensive understanding of the multitude of compounds
that are emitted from reconstituted panelboard plants and how
their emissions relate to Minnesota's list of air toxics
compounds. The test strategy is founded on a phased approach
that is designed to provide for a preliminary screening analysis
to identify and roughly quantify the various air toxics emitted
from the sources discussed earlier. Following the screening
analysis, EPA-approved sampling and analysis methods will be
recommended to obtain detailed characterization of specific air
toxics found to be present in the screening analysis. Table 8
presents a summary of the plants and sources recommended for air
toxics screening and specific analysis.
An adaptation of EPA Method 18 has been suggested as a
"screening" sampling/analysis method for the targeted air
toxics. These screening procedures can be done in the field. In
addition, "specific" methods are also suggested. These methods
generally require offsite laboratory preparation but are
sensitive methods for a short list of target analytes. The
screening methods generally produce a faster result and are
cheaper but do not have particularly low detection limits.
Established methods have been referenced so the results could be
used for compliance monitoring.
4.1 SCREENING ANALYSIS
Table 9 lists the air toxics compounds that are suspected to
be released from reconstituted panelboard manufacturing plants.
The list was prepared from literature on compounds released from
the thermal decomposition of wood (see Table 3) and compounds
known to be present in the resins used to bind the wood flakes.
This information from the literature was compared to Minnesota's
current list of air toxics compounds as well as to their list of
compounds being considered for inclusion as air toxics. The list
of compounds presented in Table 9 represents the intersection of
those two lists of compounds and serves as a starting point to
identify the types of compounds suspected of being released from
32
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Table 8. Summary of plants and sources recommended for air toxics screening and specific analysis.
PLANT
HARDBOARD
SUPERWOOD, DULUTH
SUPERWOOD, BEMIDJI
OSB
L-P, TWO HARBORS
POTLATCH, COOK
POTLATCH, BEMIDJI
EXISTING
EXPANSION
POTLATCH, GRAND RAPIDS
NORTHWOOD, BEMIDJI
ALLIGNED RBERBOARD
MacMILLIAN-BLOEDEL
SCREENING ANALYSIS
PRESS HEAT TEMPERING
DRYER VENT SUPPLY OVEN
XX X
XXX
X X
SPECIFIC ANALYSIS
PRESS HEAT TEMPERING
DRYER VENT SUPPLY OVEN f
X
XX X
X
X
X
XXX
X X
CO
CO
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Table 9. Air toxics potentially emitted from Minnesota reconstituted panelboard plants.
EPA Air Toxics
Acetaldehyde
Acrolein
Benzene
Catechol
o-Cresol
m-Cresol
p-Cresol
Formaldehyde
Methanol
Methyl ethyl ketone
Naphthalene
Phenol
Propionaldehyde
Toluene
m-Xylene
MN SARA
Acetone
2,4-Dimethylphenol
Methylene diphenyl
diisocyanate (MOI)
Propionic acid
Pyridine
Possible Additions
Acetic acid
Benzo(a)pyrene
Ethanol
Isobutanol
Methane
Methyl propyl ketone
Propanol
34
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these plants and the sampling and analysis methods currently
available to measure them.
4.1.1 Recommended Screening Test Methods
Method 18 is an EPA-approved method for sampling and
performing field analyses of volatile organics. The procedures
describe using glass or Tedlar samplers, using heated sampling
loops for direct interface sampling and analysis, and using
charcoal or charcoal/silica sorption tubes. For this application,
the preferred procedure is analysis by direct injection through a
heated gas-sampling valve into a gas chromatograph. This should
extend the usefulness of the method to those targeted compounds
such as the cresols and naphthalene, which are generally
considered "semivolatile" organics. For the screening analysis,
a 30 m x 5.0 urn DB-1 Megabore column with a long, wide-range
temperature program on the gas chromatograph would be a logical
choice for all analytes except formaldehyde, MOI, acetic acid,
and propionic acid. This temperature program may require
subambient capabilities to cover the range of volatilities for
these analytes. If this column does not produce the desired
separation and sensitivity, a 30 m x 1.5 urn DB-5 capillary column
can be used. Analysis of formaldehyde and the organic acids may
require the use of a polar column such as a Carbowax
(polyethylene phase). Using this screening method, the target
analytes should be detectable at 10 parts per billion (ppb) to
1 parts per million (ppm).
No validated EPA methods have been found for MOI. However
for screening purposes, it should be possible to adapt a NIOSH or
OSHA method and collect this analyte in an impinger followed by
colorimetric titration.
4.1.2 Plants and Sources Recommended for Screening
The following are recommendations on which plants and
sources should be subjected to the air toxics screening
analysis. Table 8 summarizes the recommendations made below.
4.1.2.1 Hardboard Mills. The screening analysis for air
toxics released from hardboard mills need only be conducted at
35
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Superwood's dry-process mill in Bemidji. The dryer, tempering
oven, and press-vent exhaust should each be tested using the
screening methods discussed above. Superwood's wet-process
hardboard mill in Duluth need not be screened because the press
vents at this facility are likely to emit the same air toxics
compounds found in the dry-process press vents. It is uncertain,
however, what effect the presence of water in the press has on
emissions from the wet-process press.
4.1.2.2 OSB Mills. The screening analysis for air toxics
released from wood flake dryers at OSB plants need only be
conducted at one mill. This analysis should be conducted at the
Northwood Panelboard plant in Bemidji because the high inlet
temperature in their dryers suggests that this plant probably
represents the worst case for air toxics emissions from the dryer
exhaust. In addition, only one air toxics screening analysis may
be necessary for the press vents as well. All of the plants
operate their presses similarly except Louisiana-Pacific's plant
in Two Harbors. As mentioned earlier, Louisiana-Pacific uses MDI
resin to bind the flakes instead of PF resins that are used by
all the other plants. In the summary of air toxics data
presented in the previous section, all of the tests conducted on
presses at plants using MDI resins indicated that MDI emissions
are less than 0.01 Ib/MSF on a 3/4-in. thickness basis.
Therefore, since these emissions have been confirmed as being
minimal, it is not necessary to expend the effort to perform a
separate screening analysis for MOI emissions at this plant.
4.1.2.3 Aligned Fiberboard Mill. The dryer, and press vent
exhausts should be screened for air toxics at the MacMillian-
Blaedel plant when completed. These sources are atypical of
other dryers and presses in Minnesota's reconstituted panelboard
industry.
36
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4.2 SPECIFIC ANALYSIS
4.2.1 Recommended Specific Test Methods
Specific test methods can be generally divided into methods
for volatile organics and for semivolatiles. The EPA
Method TO-14 is one possibility for analyzing volatile
organics. This technique would apply only to the nonpolar
volatile organics on the target list (benzene, toluene,
xylene). For a broader list of volatile organics, different
sorbent materials could be used to collect samples in an
adaptation of EPA Method TO-1. The EPA Method TO-1 has not been
validated for all of the target analytes, but the Tenax and
charcoal sorbents recommended in the method can be expected to
produce accurate, sensitive results for most of the volatile
organics on the target list. The EPA Method TO-1 can be used as
either a screening or specific method, depending on whether the
analyses used gas chromatographs with specific detectors in the
field or gas chromatographs with mass spectrometry detection at
an offsite laboratory. Retention volumes will have to be
established for those target analytes (acetaldehyde, acetic acid,
propionic acid, ethanol, isobutanol) for which the current EPA
Methods are not validated. Methane would not have any
appreciable retention.
Separate sampling and analysis will be required for the
semivolatile organics. EPA Method TO-4 or SW-846 Method 0010 are
suitable for most of the semivolatile organics on the target
list. Method TO-14 uses polyurethane foam plugs as sampling
sorbent, and Method 0010 uses XAD resin. Following extraction,
the samples would be analyzed by GC/MS.
Using sorbent materials in specific sampling and analysis
methods may increase the achievable detection limits by a factor
of 100 to 1,000.
A specific detection method for MDI could be developed using
a NIOSH or OSHA method using an impinger for collection followed
by HPLC analysis. A number of other techniques may be useful,
but as yet are not established, validated EPA test methods.
37
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A real-time analysis capability exists through using
infrared (IR) analyzers. A few commercial analyzers could be
adapted for this application by scanning in open-cell mode,
aiming across the stack. Detection limits of as low as 1 ppm
could be achieved, providing the moisture in the stack effluent
doesn't interfere. Several journal articles relating to IR
analysis of air toxics have recently been published. Spectral
libraries are available that allow identification of
acetaldehyde, benzene, formaldehyde, methanol, propionaldehyde,
toluene, m-xylene, acetone, propionic acid, acetic acid, ethanol,
isobutanol, methane, methyl ethyl ketone and propanol.
Commercial IR instruments can detect only gases. Therefore, only
the volatile organics can be measured in real time.
The semivolatile organics are expected to be present in the
emissions in a condensed phase or associated with particulate
matter; therefore, the suggested semivolatile methods use a
sorbent media. Recent journal articles describe techniques that
use supercritical fluids to extract target analytes from
sorbents. Work has been published that suggests that analysis of
foam plugs using supercritical fluid extraction/supercritical
fluid chromatography is a fast, sensitive procedure that could be
done in the field or in an offsite laboratory.
4.2.2 Plants and Sources Recommended for Testing
The same plants and sources selected for air toxics
screening should also be subjected to the specific-analysis with
some additions as summarized in Table 8. The press vent exhaust
at the wet process hardboard plant in Diluth should be
characterized to determine if any significant differences exist
between air toxics emissions at wet and dry process hardboard
mill press vents. Also, at OSB plants testing should be
performed on the dryer exhausts at several of the plants because
of the variation in dryer inlet temperatures, a known factor
influencing VOC emissions. The high dryer inlet temperatures
(1700° to 1800°P) at the Northwood Panelboard plant in Bemidji
should represent the worst case conditions for air toxics
38
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emissions (see Table 1). The Potlatch plants in Cook, Bemidji
(existing plant), and Grand Rapids all have dryers that operate
in the 1200° to 1300°F range. Primary consideration should be
given to testing the Potlatch plant in Grand Rapids. This plant
is equipped with an economizer to recover heat from the dryer
exhaust. The ability of this control device to reduce the
temperature of the dryer exhaust and scrub contaminants from it
suggests that it may result in some reduction in air toxics
emissions. The other OSB plants in Minnesota control emissions
with an EFB, a dry, particulate-collection device. Because the
EFB is a dry collection device and operates at a temperature of
approximately 230° to 250°F, it is not likely that significant
quantities of air toxics compounds will be condensed and
collected by this device. Therefore, sampling should be
conducted at the Grand Rapids mill both at the inlet and outlet
of the economizer. Air toxics measured at the inlet to the
economizer should be representative of the air toxics emissions
at the other mills that are controlled with EFB's. Measuring air
toxics emissions at the outlet of the economizer will allow the
quantification of air toxics emissions reductions achievable by
the economizer.
Finally, the Louisiana-Pacific plant in Two Harbors and the
Potlatch expansion in Bemidji should each be tested to represent
dryers operating at temperatures of 1000° and 860°F,
respectively.
5.0 REFERENCES
1. A Survey of Emissions From Dryer Exhausts in the Wood
Panelboard Industry, NCASI Technical Bulletin No. 504.
September 1986.
2. Vaught, C. C. Evaluation of Emission Control Devices at
Waferboard Plants, EPA-450/3-90-002, U. S. Environmental
Protection Agency, Control Technology Center, Research
Triangle Park, NC, 1989.
3. A Survey of Formaldehyde and Total Gaseous Nonmethane Organic
Compound Emissions From Particle Board Press Vents. NCASI
Technical Bulletin No. 483. June 1986.
39
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4. Wise/ L. E. Wood Chemistry. American Chemical Society
Monograph Series, Reinhold Publishing Corporation. 1952.
5. A Summary of Gaseous Emission Measurement Data for
Reconstituted Building Board Plants, NCASI Special Report
No. 89-05. September 1989.
6. Rosvold, R. A., and J. N. Friedman. Toxic Air Quality
Analysis for the Potlatch OSB Plant in Bemidji, Minnesota.
Interpol Laboratories, Inc. February 24, 1989.
7. Rosvold , R. A., and J. N. Friedman. Toxic Air Quality
Analysis for the Proposed MacMillian-Bloedel Waferboard Plant
Near Dearwood, Minnesota. Interpol Laboratories, Inc.
July 12, 1989.
8. Formaldehyde, Phenol, and Total Gaseous Non-Methane Organic
Compound Emissions From Flakeboard and Oriented Strandboard
Press Vents, NCASI Technical Bulletin No. 503.
September 1986.
f0101-2/IND
40
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TECHNICAL REPORT DATA
'Please read instructions on the reverse oetore camoierimi
1. REPORT NO.
EPA-450/3-91-009
.3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Evaluation of Air Toxic Emissions of
Minnesota's Reconstituted Panelboard Plants
;5. REPORT DATE
I April'1991
16. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Charles C. Vaught
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
401 Harrison Oaks Boulevard
Suite 350
Gary, North Carolina 27513
10. PROGRAM ELEMENT NO.
05
11. CONTRACT/GRANT NO.
68-DO-0123
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. Environmental Protection Agency
Control Technology Center
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The project to evaluate air toxics emissions and develop a test plan for
reconstituted panelboard mills in Minnesota was jointly sponsored by the
Minnesota Pollution Control Agency and EPA's Control Technology Center
(CTC), part of the Air Quality Management Division. As a result, EPA's
Air Quality Management Division contracted with Midwest Research
Institute to prepare the air toxics test strategy. This report presents
the results of the air toxics study. The report discusses the
reconstituted panelboard industry in Minnesota, the processes used,
available literature on air toxics emissions from these mills, and the
proposed air toxics test strategy.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b-IDENTIFlERS/OPEN ENDED TERMS C. COSATI Held/Group
Air toxics emissions
Panelboard plants
Reconstituted panelboard
M8. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report! \ 21. NO. OF PAGES
: 20. SECURITY CLASS (This page/
122. PRICE
I
SPA Form 2220-1 (Rev. 4-77) =aevious EDITION i s OBSOLETE
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