United States '; Office of Air duality
Environmental Protection Planning and Standards
Agency ; Research Triangle Park, NC 27711
EPA-453/R-01-004
September 2000
Air
EPA Background information Document
for Proposed Plywood and
Composite Wood Products NESHAP
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Background Information Document for Proposed
Plywood and Composite Wood Products NESHAP
For U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
EPA-453/R-01-004
September 2000
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TABLE OF CONTENTS
1.0 INTRODUCTION !_!
1.1 PURPOSE OF THE BID .. I '.'.'.'.'.'.'.".'.'.'.'. 1-1
1.2 INFORMATION USED TO DEVELOP THE BID ...?....'!.'.'! 1-2
1.3 ORGANIZATION OF THE BID ..J.......... 1-3
1.4 ACRONYMS, ABBREVIATIONS, AND OTHER TERMINOLOGY 1-4
1.5 REFERENCES FOR CHAPTER 1 '. i_7
2.0 INDUSTRY PROFILE 2-1
2.1 INDUSTRY OVERVIEW '.'.'.'.'.'.'.'. 2-1
2.2 PARTICLEBOARD , ' ' '" '' " "............ 2-4
2.2.1 Particleboard Process;Description 2-4
2.2.1.1 ConventionalParticleboard Process Description 2-4
2.2.1.2 Agriboard Process Description 2-9
2.2.1.3 Molded and Extruded Particleboard Process Description 2-10
2.2.2 Emission Sources and Controls at Particleboard Plants 2-11
2.2.3 Nationwide HAP Emissions from Particleboard Plants . . 2-15
2.3 ORIENTED STRANDBOARTJ :..'.'.'.'.'.'.'.'.'.'. 2-16
2.3.1 OSB Process Description 2-16
2.3.2 Emission Sources and Controls at OSB Plants 2-19
2.3.3 Nationwide HAP Emissions from OSB Plants . . . .. 2-20
2.4 MEDIUM DENSITY FEBERBOARD '.'.'.'.'.'. 2-21
2.4.1 MDF Process Description 2-21
2.4.2 Emission Sources and Controls at MDF Plants 2-25
2.4.3 Nationwide HAP Emijssions from MDF Plants ........ ' 2-27
2.5 FIBERBOARD/HARDBOARD ''.'.'.'.'.'. 2-28
2.5.1 Fiberboard/Hardboard Process Description 2-30
2.5.1.1 Dry Process Hardboard 2-30
2.5.1.2 Wet Process Fiberboard 2-31
2.5.1.3 Wet Process Hardboard '.[ 2-32
2.5.1.4 Wet/Dry Process Hardboard 2-33
2.5.2 Emission Sources and'Controls at Fiberboard/Hardboard Plants 2-34
2.5.3 Nationwide HAP Emissions from Fiberboard/Hardboard Plants 2-36
2.6 SOFTWOOD PLYWOOD .; '''' 2-37
2.6.1 Softwood Plywood and Veneer Process Description 2-38
2.6.2 Emission Sources and Controls at Softwood Plywood and
Veneer Plants 2-41
2.6.3 Nationwide HAP Emissions from Softwood Plywood and
Veneer Plants : : . . 2-42
2.7 HARDWOOD PLYWOOD .' 2-43
2.7.1 Hardwood Plywood and Veneer Process Description 2-44
2.7.1.1 Hardwood Veneer Process Description 2-45
2.7.1.2 Hardwood Plywood Process Description 2-46
111
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TABLE OF CONTENTS (Continued)
2.7.2 Emission Sburces'and Controls at Hardwood Plywood and
Veneer Plants j. -- ; 2"47
2.7.3 Nationwide HAP Emissions from Hardwood Plywood and
Veneer Plants !
2.8 LAMINATED VENEERLUMBER
2.8.1 LVL Process Description
2.8.2 Emission Sources and Controls at LVL Plants ; 2-50
2.8.3 Nationwide HAP Emissions from LVL Plants 2-50
2.9 LAMINATED STRAND LUMBER 2-51
2.9.1 LSL Process Description 2"51
2.9.2 Emission Sources and Controls at LSL Plants . 2-53
2.9.3 Nationwide HAP Emissions from LSL Plants 2-53
2.10 PARALLEL STRAND LUMBER - 2-54
2.10.1 PSL Process Description 2~^
2.10.2 Emission Sources and Controls at PSL Plants 1 2-55
2.10.3 Nationwide HAP Emissions from PSL Plants : 2-55
2.11 I-JOISTS j l *~55
2.11.1 I-Joist Process Description ~~^
2.11.2 Emission Sources and Controls at I-Joist Plants 2-58 i
2.11.3 Nationwide HAP Emissions from I-Joist Plants 2-58
2.12 GLUE-LAMINATED BEAMS | 2-59
2.12.1 Glulam Process Despription ; 2-59
2.12.2 Emission Sources ai)d Controls at Glulam Plants ; 2-60
2123 Nationwide HAP Erhissions from Glulam Plants i 2-60
2.13 MISCELLANEOUS ENGlJvfEERED WOOD PRODUCTS . .] 2-60
2.13.1 Miscellaneous Engineered Wood Products Process Description 2-61
2.13.2 Emission Sources at Miscellaneous Engineered Wood Plants 2-61
2.13.3 Nationwide HAP Ernissions from Miscellaneous Engineered
Wood Plants "".'. .... ."".'.i". ...:.- .".':.. '.":..[ - 2-62
2.14 KILN-DRIED LUMBER | ;
2.14.1 Co-Located Lumber Kilns 2-62
2.14.2 Emission Sources and Controls for Lumber Kilns 2-63
2.14.3 Nationwide HAP Ernissions from Co-Located Lumber Kilns 2-63
2.15 REFERENCES FOR CHAPTER 2 2~63
3.0 EMISSION CONTROL TECHNIQUES i 3A
3.1 INCINERATION-BASED [CONTROLS f 3'2
3.1.1 Thermal Oxidization 3"2
3.1.1.1 Thermal Oxidizers > 3"3
3.1.1.2 Process Incineration ! 3"^
3.1.1.3 Regeneratiye Thermal Oxidizers :.'.'. 3-5
3.1.2 Catalytic Oxidization ; 3"8
IV
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TABLE OF CONTENTS (Continued)
3.1.3 Performance of Incineration-Based Controls 3-10
3.1.4 Monitoring of Incineration-Based Controls 3-12
3.2 BIOHLTRATION .- 3-13
3.2.1 Description of Biofiltration 3-13
3.2.2 Performance of Biofilters 3-16
3.2.3 Monitoring of Biofilters 3-17
3.3 CAPTURE DEVICES 3-18
3.4 WET ELECTROSTATIC PRECIPrrATORS 3-19
3.5 OTHER CONTROL TECHNIQUES 3-21
3.6 REFERENCES FOR CHAPTER 3 3-22
4.0 CONTROL AND TESTINGMONTTORING COSTS 4-1
4.1 BASIS FOR CONTROL COSTS 4-1
4.1.1 RTO Costs 4-2
4.1.1.1 RTO Total Capital Investment 4-2
4.1.1.2 RTO Total Annualized Cost 4-4
4.1.1.3 Application of the RTO Cost Algorithm to Estimate Capital
and Annualized Costs 4-5
4.1.2 WES? Costs 4-5
4.1.2.1 WESP Total Capital Investment 4-7
4.1.2.2 WESP Total Annualized Cost 4-7
4.1.3 Permanent Total Enclosure (PTE) Costs .4-8
4.1.4 Plant-by-Plant Costing Approach 4-10
4.1.4.1 Application of Control Costs to Process Units : 4-10
4.1.4.2 Exhaust Flow Rate to Be Controlled , 4-11
4.1.4.3 Calculation of Nationwide Control Costs 4-13
4.1.5 Summary of Nationwide Control Costs 4-13
4.3 REFERENCES FOR CHAPTER 4 4-15
5.0 ENVIRONMENTAL AND ENERGY IMPACTS .5-1
5.1 AIR IMPACTS 5-2
5.1.1 Reduction in Total HAP and THC 5-2
5.1.2 Effect of Standards on Criteria Pollutants ,. 5-3
5.1.2.1 PM-10 Emissions 5-3
5.1.2.2 NOX Emissions 5-7
5.1.2.3 CO Emissions .5-8
5.1.3 Secondary Air Impacts 5-10
5.2 WASTEWATER IMPACTS 5-11
5.3 SOLID WASTE IMPACTS , .' 5-13
5.4 ENERGY IMPACTS ; 5-14
5.5 SUMMARY OF NATIONWIDE ENVIRONMENTAL AND
ENERGY IMPACTS' 5-15
5.6 REFERENCES FOR CHAPTER 5 5-19
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Figure 2-1.
Figure 2-2.
Figure 2-3.
Figure 2-4.
Figure 2-5.
Figure 2-6a.
Figure 2-6b.
Figure 2-7.
Figure 2-8.
Figure 2-9.
Figure 2-10.
Figure 2-11.
Figure 2-12.
Figure 2-13.
Figure 2-14b.
Figure 2-14a.
Figure 3-1.
Figure 3-2.
Figure 3-3.
'Figure 4-1.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5.
LIST OF FIGURES
Locations of U.S. PCWP facilities I 2-2
Process flow diagram for particleboard manufacturing : 2-5
Multi.-opening batch press ! 2-8
Typical process flow diagram for an oriented strandboard plant 2-17
Typical process flow diagram for a medium density fiberboard (MDF) plant. 2-22
Single-stage tube dryer .., 2-24
Double-stage tube dryer . |. 2-24
Fiberboard products manufacturing processes ; 2-29
Generic process flow diagram for a plywood mill ; 2-39
General steps in hardwood veneer and plywood manufacturing 2-44
Laminated veneer lumber manufacturing process 2-48
Laminated strand lumber manufacturing process 2-52
Parallel strand lumber manufacturing process 2-54
View of an I-joist made from an OSB web and LVL flanges 2-56
I
Basic I-joist assembly ..'. { 2-57
I-joist manufacturing process 2-57
Schematic of a thermal oxidizer i 3-3
Regenerative heat recover)' process i 3-6
Schematic of a biofiltratidn system ." i 3-13
Variation in RTO purchased equipment cost with flow rate ; 4-3
'Relationship between RTO electricity consumption and flow rate 4-4
[
Relationship between RTp natural gas consumption and flow rate 4-5
Variation in RTO total capital investment' with flow ( 4-6
Variation in RTO total annualized cost with flow i. 4-6
VI
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LIST OF TABLES
TABLE 1-1. ACRONYMS AND ABBREVIATIONS 1-5
TABLE 1-2. TERMINOLOGY WTTH A PARTICULAR MEANING USED IN THIS
DOCUMENT ; j_7
TABLE 2-1. NUMBER OF U.S. PLANTS MANUFACTURING PCWP 2-3
TABLE 2-2. NUMBER OF PARTICLEBOARD DRYERS AND APCD IN THE
UNITED STATES ; 2-12
TABLE 2-3. NUMBER OF PARTICLEBOARD ROTARY DRYERS BY FURNISH
TYPE AND APCD IN THE UNITED STATES 2-13
TABLE 2-4. NUMBER OF PARTICLEBOARD PRESSES AND APCD IN THE
UNITED STATES , 2-14
TABLE 2-5. NUMBER OF PARTICLEBOARD BOARD COOLERS AND APCD IN
THE UNITED STATES .;. 2-14
TABLE 2-6. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR
PARTICLEBOARD PROCESS UNITS 2-15
TABLE 2-7. NUMBER OF OSB DRYERS AND APCD IN THE UNITED STATES . . . 2-19
TABLE 2-8. NUMBER OF OSB PRESSES AND BOARD COOLERS AND APCD IN
THE UNITED STATES 2-20
TABLE 2-9. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR OSB
PROCESS UNITS 2_2i
TABLE 2-10. NUMBER OF MDF DRYERS AND APCD IN THE UNITED STATES . . . 2-26
TABLE 2-11. NUMBER OF MDF PRESSES AND BOARD COOLERS AND APCD IN
THE UNITED STATES .| 2-26
TABLE 2-12. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR MDF
PROCESS UNITS 2-28
TABLE 2-13. NUMBER OF FIBERBOARD/HARDBOARD DRYERS AND APCD IN
THE UNITED STATES 2-35
TABLE 2-14. NUMBER OF FIBERBOARD/HARDBOARD MAT DRYERS, OVENS,
AND HUMIDIFIERS AND APCD IN THE UNITED STATES 2-35
TABLE 2-15. NUMBER OF HARDBOARD PRESSES AND APCD IN THE UNITED
STATES 2-35
TABLE 2-16. AVERAGE BASELINE TOTAL HAP EMISSIONS FOR FIBERBOARD/
HARDBOARD PROCESS UNITS 2-37
vn
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LIST OF TABLES (Continued)
'age
TABLE 2-17.
TABLE 2-18.
TABLE 2-19.
TABLE 2-20.
TABLE 2-21.
TABLE 2-22.
TABLE 2-23.
TABLE 2-24.
TABLE 2-25.
TABLE 3-1.
TABLE 3-2.
TABLE 3-3.
TABLE 4-1.
TABLE 4-2.
TABLE 4-3.
TABLE 4-4.
TABLE 5-1.
TABLE 5-2.
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR
FEBERBOARD/HARDBpARD PROCESS UNITS _., : 2-38
NUMBER OF VENEER pRYERS AND APCD AT SOFTWOOD
PLYWOOD PLANTS IN THE UNITED STATES J
2-42
2-47
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR
SOFTWOOD PLYWOOD AND VENEER PROCESS UNITS 2-43
NUMBER OF VENEER [DRYERS AND APCD AT HARDWOOD
PLYWOOD PLANTS IN THE UNITED STATES
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR
HARDWOOD PLYWOOD AND VENEER PROCESS UNITS . .; 2-48
NUMBER OF VENEER-DRYERS AND APCD AT LVLIJLANTS IN
THE UNITED STATES 1 \
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR LVL
PROCESS UNITS -
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR LSL
PROCESS UNITS \
AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS FOR PSL
PROCESS UNITS .. . J.
SUMMARY OF RTO PERFORMANCE FOR FORMALDEHYDE, '
METHANOL, AND THC j
SUMMARY OF RCO PERFORMANCE FOR FORMALDEHYDE,
METHANOL, AND THC . '-\ 3~n
SUMMARY OF BIOFlLTER PERFORMANCE FOR FORMALDEHYDE,
METHANOL, AND THC \ 3"17
PRESS ENCLOSURE EXHAUST FLOW RATES AND CAPITAL COSTS . 4-9
CONTROL EQUIPMENT COSTED FOR PROCESS-UNITS WITH
CONTROLLED MACTJ FLOOR 4'n
DEFAULTFLOW RATES 4'12
ESTIMATED NATIONWIDE CONTROL COSTS FOR THE PCWP
INDUSTRY [ |- 4"14
PERCENT REDUCTION IN TOTAL PMIO ACROSS COMBINED
PREFILTER AND RTCp CONTROL SYSTEMS ; 5-4
TOTAL PM,0 REDUCTION ACROSS RTO .., 5'5
2-50
2-51
2-53
2-5
3-11
Vlll
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LIST OF TABLES (Continued)
TABLE 5-3. CALCULATION OF'PMjo REDUCTION ASSOCIATED WITH THE
PCWP STANDARDS FOR VARIOUS PROCESS UNITS 5-6
TABLE 5-4. CO INCREASES ACROSS RTO 5_g
TABLE 5-5. PERCENT REDUCTION IN CO EMISSIONS ACROSS DIRECT-FIRED
DRYER RTO 5.9
TABLE 5-6. CALCULATION OF CO REDUCTION ASSOCIATED WITH THE
PCWP STANDARDS FOR VARIOUS PROCESS UNITS 5-10
TABLE 5-7. ANNUAL WASTEWATER GENERATION RATES FOR RTO
WASHOUTS 5_12
TABLE 5-8. ESTIMATED NATIONWIDE REDUCTION IN TOTAL HAP AND THC . 5-16
TABLE 5-9. ESTIMATED NATIONWIDE CHANGE IN NOX, CO, AND PM10
EMISSIONS AND ESTIMATED NATIONWIDE SECONDARY AIR
IMPACTS : 5_17
TABLE 5-10. ESTIMATED NATIOmyiDE SOLID WASTE AND WASTEWATER
IMPACTS 5_lg
TABLE 5-11. ESTIMATED NATIONWIDE ENERGY IMPACTS 5-18
IX
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1.0 INTRODUCTION
1.1 PURPOSE OF THE BE)
This report was prepared to support development of national emission standards for
hazardous air pollutants (NESHAP) for the plywood and composite wood products (PCWP)
manufacturing industry. Plywood and composite wood products include the following:
particleboard
oriented strandboard (OSB)
medium density fiberboard (MDF)
i
fiberboard ;
1 . i
hardboard
softwood plywood
softwood veneer
hardwood veneer
laminated veneer lumber (LVL)
laminated strand lumber (LSL)
parallel strand lumber (PSL)
wood I-joists
glue1laminated beam's
other engineered wood products
hardwood plywood
These PCWP are generally manufactured by adhering wood pieces (e.g., particles, fibers, flakes,
veneers, or lumber) with glue or other binder and pressing into a consolidated product.
The purpose of this document is to present information on PCWP manufacturing related
to the hazardous air pollutants (HAP) emitted from PCWP processes and HAP control strategies.
This document contains the following:
description of PCWP manufacturing processes and process units,
description of the air pollution control devices (APCD) used to reduce HAP
emissions, ;
summary of nationwide counts of process units and APCD,
summary of nationwide and per-process-unit average HAP emission estimates,
1-1
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[
summary of the HAP reduction capabilities of APCD, ;
I
nationwide costs associated with the PCWP rulemaking, and
nationwide environmental ami energy impacts associated with the PCWP rulemaking.
Much of the information presented in this document is based on detailed information
documented in supporting memoranda. Section 1.2 describes the information sources used to
develop this background information document (BID) and introduces the additional supporting
memoranda. j
1.2 INFORMATION USED TO DEVELOP THE BID
The data and analyses presented in this document are based on information gathered by or
submitted to the U.S. Environmental Protection Agency (EPA) prior to proposal of the PCWP
NESHAP. The EPA conducted a survey' (information collection request) of the industry in 1998
to collect 1997 base year information from PCWP facilities related to their;manufacturing
operations and air pollution controls. Different surveys were sent to companies according to the
products manufactured. Manufacturers of particleboard, OSB, MDF, hardboard, fiberboard, and
softwood plywood or veneer completed |the "general" survey; manufacturers of hardwood
plywood or veneer that operate either hot presses or veneer dryers completed the "hardwood
plywood" survey; and manufacturers of LVL, LSL, PSL, laminated beamS| and I-joists completed
the "engineered wood products" surveyj The overall response rate for the surveys was greater
than 90 percent. The survey responses were incorporated into three separate databases
(according to the type of survey) and were summarized in three separate memoranda.1A3 Much
of the information presented in this BID is based on the three survey response summary
memoranda. j j
The process unit and control counts presented in this document are based on the survey
response summary memoranda, the survey databases, and updated information received
following the survey.1-2-3-8 In some cases, the equipment counts were developed using the survey
databases directly or process flow diagrams submitted with the surveys because the distinctions
made between the types of process uni^s presented in this document were not readily apparent
from the survey response summary memoranda. :
Emissions test data vere obtained from three resources: (1) an extensive HAP emission
testing program conducted by the National Council of the Paper Industry for Air and Stream
1-2
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Improvement (NCASI), (2) numerous emission test reports (dated 1995 or later) collected
through EPA's survey of the industry, and (3) EPA's Compilation of Air Pollutant Emission
Factors, Volume I: Stationary Point and Area Sources (commonly referred to as AP-42). The
emissions test data were used to develop emission factors (i.e., mass- of pollutant emitted per unit
production factors) for PCWP process units and to evaluate the ability of various control
technologies to reduce HAP. The PCWP emission factors are summarized in a separate
memorandum.4 The HAP reduction efficiency of various control technologies is also
documented in a separate memorandum and is summarized in Chapter 3 of this document.5 The
PCWP emission factors and control efficiency information was coupled with the plant-specific
information from the survey responses to develop uncontrolled and baseline emission estimates
and to predict which facilities may be major sources of HAP emissions. A major source is
defined as any stationary source or group of stationary sources within a contiguous area and
under common control that emits or has the potential to emit, considering controls, in the
aggregate, 10 tons/yr or more of any single HAP or 25 tons/yr of any combination of HAP. The
plant-specific emission estimates are documented in a separate memorandum and are
summarized in Chapter 2 of this document.6
In addition to the EPA's survey data and the emission test data, information was collected
through site visits to PCWP facilities; communication with representatives from the PCWP
industry, State and Federal agencies, and emission control device vendors; and operating permits.
All of these resources were used to identify the maximum achievable control technology
(MACT) level of HAP emission control for the PCWP NESHAP. A separate memorandum
documents the selection of MACT.7 The aforementioned resources were also used to estimate
the cost, environmental, and energy impacts associated with the MACT level of control. The
cost, environmental, and energy impacts are summarized in this document.
1.3 ORGANIZATION OF THE BID .
This BID is divided into five chapters. Chapter 1 is the introduction. Chapter 1 provides
orientation for the reader; explains the information upon which the PCWP NESHAP is based;
and provides a list of acronyms, abbreviations, and special terms used in this document.
Chapter 2 is divided into separate sections for each PCWP. Each section of Chapter 2
describes the processes used to manufacture PCWP, provides nationwide counts of process units
! 1-3
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and APCD, and summarizes the nationwide and per-process-unit average uncontrolled and
baseline emission estimates. In addition* Chapter 2 presents the Standard Industrial
Classification (SIC) and North American Industrial Classification System (NAICS) codes for
PCWP, summarizes the number of plants that manufacture PCWP, describes where the PCWP
plants are located, and provides projections of the number of new PCWP facilities.
i i
Chapter 3 discusses the control techniques that may be applied to reduce HAP emissions
from PCWP process units. Chapter 3 discusses the operation and performance of incineiration-
based controls, biofiltration, permanent total enclosures (PTE), wet electrostatic precipitators
(WESP); and other control techniques, i
I : i
Chapter 4 describes the methodology used to develop the cost estimates associated with
the MACT level of control for the PCWP NESHAP. The cost estimates are based on the use of
regenerative thermal oxidizers (RTO) fof all process units; a WESP followed by an RTO for
rotary strand dryers; and a PTE and RTQ for reconstituted'wood product presses. Chapter 4 and
Appendix A present the cost models usek for RTO, WESP, and PTE. These cost models were
coupled with the facility-specific information from the survey responses to develop facility
i
specific'cost estimates. Chapter 4 presents the number of facilities impacted and the nationwide
[
costs. In addition to the control costs, CJiapter 4 summarizes the testing, monitoring, reporting,
and recordkeeping costs associated with ithe PCWP rulemaking.
i i
Chapter 5 describes the methodology used to develop the environmental and energy
impact estimates associated with the MACT level of control for the PCWP: NESHAP and
| ! -
presents the nationwide impacts. As for|the cost impact estimates, the environmental and energy
impact estimates are facility-specific and are based on the use of RTO, WESP and PTE.
Environmental impacts include HAP emission reductions, changes in criteria pollutant
emissions, secondary air impacts, waste-\|vater impacts, and solid waste impacts. Energy impacts
are associated with electricity and fuel consumption by control devices.
1.4 ACRONYMS, ABBREVIATIONS,1 AND OTHER TERMINOLOGY
I :
Numerous acronyms and abbreviations are used throughout this document. Most of the
acronyms and abbreviations are defined [the first time they appear in the te>j.t. Table 1-1 also
defines the acronyms and abbreviations and can be used as a cross reference. In addition to the
acronyms and abbreviations, some other terms that have special meaning are used in this
1-4
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document. The meaning of the terms is provided in the text and is also provided in Table 1-2 for
convenience.
TABLE 1-1. ACRONYMS AND ABBREVIATIONS
Acronym or
abbreviation
APCD
BID
CO
C02
CPA
dscfm
EFB
EPA
ESP
glulam
gpm
HAP
lb/ft3
If/min
LSL
LVL
MACT
MDF
MDI
MF
mi
min
MUF
N2
NAICS
NESHAP
Meaning
air pollution control device(s)
background information document
carbon monoxide
carbon dioxide
Composite Panel Association
dry standard cubic feet per minute
electrified filter bed
U.S. Environmental Protection Agency
electrostatic precipitator
glue-laminated beams
gallons per minute
hazardous air pollutant(s)
pounds per cubic foot
linear feet per minute
laminated strand lumber
laminated veneer lumber
maximum achievable control technology
medium density fiberboard
methylene diphenyl diisocyanate 1
melamine-formaldehyde
mile 1
minutes ;
melamine-urea-forrnaldehyde
nitrogen : .
North American Industrial Classification System
national emission standards for hazardous air pollutants ||
1-5
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TABLE 1-1. (Continued)
Acronym or
abbreviation
NGI
NO2
NOX
NSPS
02
OAQPS
OSB
Pb
PCWP
PEC
PF
PLV
PM
PM10
PRF
PSL
PTE
PVA
RCO
RF
RTO
RVRS
SIC
SO2
TAG
TCI
TCO
THC
'.
natural gas injectioi
Meaning
1 ;
nitrogen dioxide
nitrogen oxides
new source perfornlance standards \
oxygen
Office of Air Quality Planning and Standards !
oriented strandboard : .
lead . . ,
plywood and composite wood product(s) \
purchased equipment cost ;
phenol-formaldehyde
parallel laminated \|eneer ,
particulate matter
parti culate matter less than 10 micrometers in aerodynamic diameter
phenol-resorcinol-formaldehyde
parallel strand lumber
permanent total enclosure(s) i
polyvinyl acetate ;
regenerative catalytic oxidizer(s)
radio-frequency ;
regenerative thermal oxidizer(s)
regenerative vapor recovery system i
Standard Industrial
Classification
sulfur dioxide
total annualized cost
total capital investrhent
thermal catalytic ojiidizer(s)
total hydrocarbon
1-6
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TABLE 1-1. (Continued)
Acronym or
abbreviation
tpy
TTE
UF
VAPCCI
VOC
WESP
Yd3
I
' 1 Meaning
tons per year
temporary total enclosure(s)
urea-formaldehyde
Vatavuk air pollution control cost index
volatile organic conipound(s)
wet electrostatic precipitator(s)
cubic yard
TABLE 1-2. TERMINOLOGY WITH A PARTICULAR MEANING
USED IN THIS DOCUMENT
Term. :
Agriboard
Incineration-based
control (s)
S emi -incinerati on
Permanent total enclosure
(PTE)
Process incineration
' Meaning as used in this document
Particleboard made from agricultural fiber
Air pollution control devices or methods that rely on
incineration (oxidation) such as RTO, RCO, TO, TCO or
process incineration
Incineration of a portion (i.e., less than 75 volume percent) of
the exhaust from a process unit in an onsite combustion unit
such as a Boiler or process heater
An enclosure that meets the criteria for a permanent total
enclosure in Appendix M of 40 CFR part 51
Incineration of all of the exhaust from a process unit
1.5 REFERENCES FOR CHAPTER 1
1. Memorandum from D. Bullock, K.:Hanks, and B. Nicholson, MRJ, to M. Kissell,
EPA/ESD. April 28, 2000. Summary of Responses to the 1998 EPA Information
Collection Request (MACT Survey) ~ General Survey.
2. Memorandum from K. Hanks, B. Threatt, and B. Nicholson, MRI, to M. Kissell, EPA/ESD.
May 19, 1999. Summary of Responses to the 1998 EPA Information Collection Request
(MACT Survey) - Hardwood Plywood and Veneer.
1-7
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3. Memorandum from K. Hanks and B. Threatt, MRI, to M. Kissell, EPA/ESD. January 20,
2000. Summary of Responses to the 1998 EPA Information Collection Request (MACT
Survey) Engineered Wood Products.
4. Memorandum from D. Bullock and K. Hanks, MRI, to M. Kissell, EPA/ESD. April 27,
2000. Documentation of Emission Factor Development for the Plywood and Composite
Wood Products Manufacturing NESHAP. ;
[
i j
5. Memorandum from R.Nicholson, MRI, to M. Kissell, EPA/ESD. May 26, 2000. Control
Device Efficiency Data for Add-on Control Devices at PCWP Plants.1
6. Memorandum from K. Hanks and D. Bullock, MRI, to M. Kissell, EPA/ESD. June 9,
2000. Baseline Emission Estimates for the Plywood and Composite Wood Products
Industry.
7. Memorandum from B. Nicholson and K. Hanks, MRI, to M. Kissell, EPA/ESD. July 13,
2000. Determination of MACT floors and MACT for the Plywood and Composite: Wood
Products Industry. j ;
i
8. Memorandum from K. Hanks, MRI, to Project Files. April 18, 2000; Changes in the
population of existing plywood and composite wood products plants and equipment
following the information collection request.
1-8
-------
2.0 INDUSTRY PROFILE
This chapter provides process descriptions, information on emissions sources and
controls,-and nationwide emission estimates for the PCWP industry. Section 2.1 presents an
overview of the PCWP industry. Sections 2.2 through 2.5 discuss manufacturing of composite
wood products; .Sections 2.6 and 2.7 discuss softwood'and hardwood plywood and veneer
manufacturing; Sections 2.8 through 2.13 discuss manufacturing of engineered wood products;
and Section 2.14 discusses kiln-dried lumber manufacturing. The sections in this chapter are
organized by product for convenience. |
2.1 INDUSTRY OVERVIEW
Plywood and composite wood products include reconstituted or composite wood
products, plywood, veneer, and engineered wood products. Composite wood products, including
particleboard, hardboard, fiberboard, MpF, and OSB, are categorized under Standard Industrial
Classification (SIC) code 2493 for "Reconstituted Wood Products" (North American Industrial
Classification System (NAICS) code 321219). Composite wood products are manufactured by
combining dry wood particles, fibers, or flakes with resin and pressing the wood and resin
mixture into a panel. . ' :
There are two types of plywood: softwood plywood and hardwood plywood. The
majority of the U.S. plywood plants make either softwood plywood or hardwood plywood. Only
a few plants produce both hardwood and softwood plywood. Softwood plywood is manufactured
by gluing several layers of dry softwood veneers (thin wood layers or plies) together with an
adhesive. Softwood plywood is classified under SIC code 2436, for "Softwood Plywood and
Veneer," (NAICS code 321212). Hardwood plywood is made of hardwood veneers bonded with
i
an adhesive. The outer layers (face and back) surround a core which is usually lumber, veneer,
particleboard, or MDF. Hardwood plywood may be pressed into panels or plywood components
(e.g., curved hardwood plywood, seat backs, chair arms, etc.). Hardwood plywood is classified
under SIC code 2435, for "Hardwood Plywood and Veneer" (NAICS code 321211).
2-1
-------
Engineered wood products are classified under SIC code 2439, for ''Structural Wood
Members Not Elsewhere Classified" (NAICS code 321213). Engineered wood products are
made from lumber, veneers; strands of Wood, or from other small wood elements that are bound
together with structural adhesives to form lumber-like structural products. They are designed for
use in the same structural applications as sawn lumber (e.g., girders, beams, headers, joists, studs,
and columns). These products allow production of large-lumber substitutes from small lower-
grade logs.1 The engineered wood products discussed in this document include LVL, LSL, PSL,
and other engineered wood products such as comply, I-joists, and glue-laminated beams
(glulam). Several facilities manufacture more than one engineered wood product at the same
plant site.
There are approximately 454 PC[WP manufacturing facilities in the: United States as of
April 2000. Most of the facilities are concentrated in the Northwest, Southeast, and Midwestern
States, where timber supplies are abundant. Figure 2-1 shows the locations of PCWP facilities in
the United States.
Figure 2-1. Locations of U.S. PCWP facilities. .
2-2 i
-------
While most facilities produce only one product, some PCWP facilities have multiple
plants at one location and manufacture more than one product. Table 2-1 presents the number of
plants that manufacture each product.
TABLE 2-1. NUMBER OF U.S. PLANTS MANUFACTURING PCWP
Product ;
Fiberboard
Hardboard
MDF
OSB
Particleboard
Molded particleboard
Particleboard from agricultural fiber
Softwood plywood and/or veneer
Hardwood plywood and/or veneer
Engineered wood products
Number of plants manufacturing product3
7
18
24
37
45
6
5
105
166
41
Some plants also make more than one product (e.g., a plant making hardboard, particleboard, and
softwood plywood). These plants are counted once for each product made in the above table.
b Plant counts based on information available as of April 2000.
! . .
Over the past decade., production of OSB, MDF, particleboard, hardwood plywood, LVL,
glulam, and I-joists has increased. However, production of fiberboard, softwood plywood, and
i
hardboard has decreased. As a result, it is expected that the number of PCWP plants producing
products other than fiberboard, softwood plywood, and hardboard will increase in the next
5 years. Based on U.S. production tren4s, it is estimated that six new OSB plants, five new MDF
plants, and four new particleboard plants will startup in the 5 years following 2000 and will be'
subject to the PCWP NESHAP. It is estimated that approximately seven new LVL facilities will
begin operation in the next 5 years. Whether or not the seven LVL facilities will be subject to the
PCWP NESHAP will depend on the emissions sources at each facility and whether the facility is
a major source of HAP emissions. While there are estimated to be several new hardwood
plywood and I-joist plants, these plants are not expected to be impacted by the PCWP NESHAP
2-3
-------
because these plants typically are not major sources of HAP emissions (as indicated by
emission estimates provided in Sections £.7.3 and 2.11.3 below).2
2.2 PARTICLEBOARD ' ; ;
Particleboard is defined as a panel product manufactured from lignocellulosic materials,
primarily in the form of discrete particles, combined with a synthetic resin or other suitable
binder and bonded together under heat and pressure.3 The major types of particles used to
manufacture particleboard include wood shavings, flakes, wafers, chips, sawdust, strands,, slivers,
and wood wool. Particleboard is typically formed into panels which are useji in manufacturing of
furniture, cabinets, doors, counter tops, arid other products. However, there are some plants in
the United States that manufacture molded or extruded particleboard products. Molded
particleboard products include molded pallets, containers, doorskins, and furniture parts. Plants
that manufacture extruded particleboard in the United States are captive plants which produce the
particleboard for use in another part of thpir business (e.g., furniture manufacture).3 The
extruded boards are typically overlaid with veneer or a laminate. Particleboard may also be
manufactured from agricultural fiber such as wheat straw or bagasse. Particleboard
manufactured from agricultural fiber (agriboard) is used in some of the same applications as
conventional particleboard panels. Applications for agriboard include shelving, furniture,
cabinets, containers, doors, and store fixtures. ;
I- '
2.2.1 Particleboard Process Description ;
The particleboard manufacturing process is described in the following three subsections.
Conventional particleboard manufacturing is described in Section 2.2.1.1; agriboard
manufacturing is described in Section 2.2.1.2; and molded and extruded particleboard
.manufacturing is described in Section 2.2.1.3.
2.2.1.1 Conventional Particleboard Process Description. The general steps used to
i i
produce particleboard panels include ravj' material procurement or generation, milling,
classifying, drying, blending, mat forming, pressing, and finishing. Figure 2-2 presents a process
flow diagram for a typical particleboard plant.4 i
Although some single-layer particleboard is produced, particleboard generally is
manufactured in three or five layers.' Th|e outer layers are referred to as the surface or face layers,
and the inner layers are called core layer|s. Face layer material is usually finer than core material.
By altering the relative properties of the
of the board can be increased.
face and core layers, the bending strength and stiffness
2-4
-------
Offstte particle generation
Onsite particle generation
f""
Resm, wax, _
otfier additives
Resin, wax
other additives
Steam/hot oil/hot watei
Heat, pressure
Cooling
Sanding
Trimming
Finishing
fc PROCESS FLOW
*- OPTIONAL PROCESS
Figure 2-2. Process flow .diagram for particleboard manufacturing.
2-5
-------
The furnish or raw material for particleboard normally consists of wood particles,
primarily wood chips, sawdust, and planer shavings. Most particleboard furnish is derived from
softwood species; however, a mixture of hardwood and softwood furnish may also be used.
Furnish may be shipped to the facility or generated onsite and stored until needed. The furnish
may be further reduced in size by means of attrition mills such as hammermills, flakers, or
refiners. After milling, the furnish is either screened using vibrating or gyratory screens, or the
particles are air-classified. The purpose of this step is to remove the fines and to separate the
core material from the face material. The1 screened or classified material then is transported to
storage bins. ;
From the storage bins, the core and face material is conveyed to dryers. Rotary dryers are
the most commonly used dryer type in the particleboard industry. Both single and triple-pass
dryers are used, although triple-pass rotary dryers are the most common. Some facilities use tube
dryers or other types of dryers. Direct wood-fired dryers, in which hot exhaust gases from a
combustion unit (e.g., a wpod waste burner) are routed directly through the jdiyer, are used at
most facilities. However, indirect-heated dryers also are used. Steam coils are located within the
path of the circulating air stream in indirjjct-heated dryers. Dryer inlet temperatures may be as
high as 1500° to 1600°F if the furnish is Wet (or green); for dry furnish, inlet temperatures are
reduced to about 500° to 600°F.3 Mixtures of dry and green material, particularly if unmanaged,
can cause problems if introduced into the same dryer at the same time. For example, dryer fires
can occur if relatively dry wood is exposed to temperatures that are too high. If wet furnish is not
dried enough then the boards may blow in the press.3 As a result, most paijicleboard dryers are
dedicated to drying either relatively dry furnish or relatively green furnish.; Core dryers often
operate at higher temperatures than face Jdryers because a lower moisture content is more
desirable for core material. The desired furnish moisture content at the dryer outlet determines
the dryer inlet temperature. Dryer inlet temperatures are routinely adjusted based on furnish
moisture measurements. i - ;
The moisture content of the partjcles entering the dryers may be as high as 50 percent'on
a wet basis (100 percent on a dry basis)] Planer shavings are a predominant material used in'the
manufacture of particleboard.3 The inlet moisture content associated with |green planer shavings
in the Northwest is about 30 percent (dry basis).5 The moisture content of green pines is higher
2-6
-------
(80 to 200 percent, dry basis) than the moisture content of green Douglas fir (40 percent), a
common wood source in the Northwest.3 Dry planer shavings have a moisture content of about
15 percent. Urban wood (another source of pre-dried wood) has a moisture content of 15 to
25 percent.5 Drying reduces the moisture content to 2 to 8 percent, wet basis (2 to 9 percent, dry
basis).4
After drying, the particles pass through a primary cyclone for product recovery and then
are transferred to holding bins. Face material sometimes is screened to remove the fines, which
tend to absorb much of the resin, prior to storage in the holding bins. From the holding bins, the
core and face material is transferred to blenders, in which the particles are mixed with resin, wax,
and other additives by means of spray nozzles; tubes, or atomizers. Urea-formaldehyde (UF)
resin is the most commonly used resin type in particleboard manufacture. 'However, some plants
use phenol-formaldehyde (PF) or melamlne-urea-formaldehyde (MUF) resins.6 Phenol-
formaldehyde resins are water-proof and are used in particleboard manufactured for outdoor
applications. '
Waxes are added to impart water resistance, increase the stability of the finished product
under wet conditions, and to reduce the tendency for equipment plugging. For furnishes that are
low in acidity, catalysts also may be blended with the particles to accelerate the resin cure and to
reduce the press time. Formaldehyde, scavengers also may be added in the blending step to
reduce formaldehyde emissions from the process.4
Blenders generally are designed to discharge the resinated particles into a plenum over a
belt conveyor that feeds the blended material to a forming machine. The forming machine
deposits the resinated material onto the conveyor in the form of a continuous mat. To produce
multilayer particleboard, several forming heads can be used in series, or air currents can produce
a gradation of particle sizes from face to core.
The particleboard mat may be prepressed at room temperature with a roller as it leaves
the former. The mat is then cut into desired lengths and conveyed to the hot press. The hot press
applies heat and pressure to activate the resin and bond the wood particles into a solid(panel.
I
Most plants operate multi-opening batch presses, although a few single-opening batch presses
exist.6 Figure 2-3 depicts a multi-opening batch press.4 A few plants operate continuous presses
which press the continuous particleboard mat as it exits the former. Most batch particleboard
I ' 2-7
-------
presses are steam-heated using steam generated by a boiler that burns wood: residue. However,
hot oil and hot water also are used to heat batch presses. Continuous presses are typically heated
f i
with hot oil. Total press time is around 6 minutes (min) for particleboard presses. The operating
temperatures for particleboard presses generally range from 260° to "450°F and average around
330°F. The finished particleboard density ranges from 29 to 72 pounds percubic foot (lb/ft3).6
After pressing, the boards are passed through a board cooler prior to, stacking. Cooling of
urea-bonded boards is necessary because the board will not reach its maximum properties until it
has cooled, and some urea resins may break down if the boards are hot stacked. Star or wicket
type board coolers are commonly used in particleboard manufacture. Newer types of coolers are
enclosed chambers where the boards are ^transported on edge through the cooler.3 .
SIMULTANEOUS
CLOSING
DEVICE
COLUMNS
TOP PLATEN
OR CROWN
PLATENS
OR PLATES
MOVING
TABLE OR
PLATEN
RAMS
Figure 2-3. Multi-opening batch press.
2-8
-------
Once cooled, the particleboard panels are sanded and trimmed to final dimensions. Edge
seals, grade stamps and trademarks, company logo information, nail lines, or shelving edge fillers
may be applied to the particleboard as part of the finishing process before the particleboard is
bundled for shipment. Some facilities use the finished particleboard for onsite furniture
manufacture or in production of laminated panels.
2.2.1.2 Agriboard Process Description. Particleboard manufactured from agricultural
fiber, or agriboard, is used in some of the same applications as conventional particleboard panels.
The primary difference in agriboard and conventional particleboard is the raw materials. The
general steps used to produce agriboard panels include raw material procurement, milling,
classifying, drying (if necessary), blending, mat forming, pressing, and finishing.
Agriboard is produced from wheat straw, soy stalks, grass straw, or sugar cane bagasse.
Large quantities of agricultural fiber, such as wheat or soy, are grown in certain regions of the
United States. Once the wheat grain or soy beans are harvested, the plant stalk remains. In the
past, farmers have eliminated the plant stalks by tilling them into the ground or burning them in
t [
the field. However, this agricultural fiber may be baled and sold for production of agriboard.
Procurement of agricultural fiber for agriboard occurs once per year just after the annual harvest.
The agricultural fiber is stored for the year by the agriboard plant or its suppliers.7
The bales of agricultural fiber are broken and the fiber is reduced in size to one-half inch
or shorter pieces by hammermills, grinders, or refiners (attrition mills). The moisture content of
sugar cane bagasse used by one plant is approximately 100 percent (dry basis). The bagasse is
stored until the moisture content is reduced to approximately 33 percent (dry basis).8'9 For the
i
plant using a mixture of soy and wheat straw, the fiber moisture content ranges from 11 to
82 percent (dry basis). The moisture content of grass straw used by one plant and of wheat straw
used by another plant ranges from 11 to 14 percent (dry basis).8 Another plant uses wheat straw
with a moisture content ranging from 5 to 50 percent (dry basis).6
Of the five agriboard plants operating in the United States, three operate rotary dryers to
remove excess moisture from the agricultural fiber. The plant that processes sugar cane bagasse
uses a gas-fired, single-pass rotary dryer to reduce the moisture content of the bagasse from
approximately 33 to 11 percent (dry basfs) with a dryer inlet temperature of approximately
650°F.10 The plant that processes a mixture of soy stalks and wheat straw, uses a gas-fired, triple
2-9
-------
pass rotary dryer. In this dryer the agricultural fiber moisture content is reduced to about
2 percent (dry basis) with a dryer inlet temperature of approximately 490°F.8'9 Another plant
reduces the moisture content of wheat straw from about 50 to 15 percent (dry basis) in an
indirect-heated, single pass rotary dryer with an inlet temperature of~about 400°F or less."
Following sizing and/or drying, the agricultural fiber is mixed with methylene diphenyl
diisocyanate (MDI) resin in blenders. Resinated material is formed into mats, cut to length, and
pressed. Multi-opening batch presses ar£ typically used in the manufacture^ agriboard.
! ' I
Continuous presses may also be employed, although no continuous presses are currently used at
operating U.S. agriboard plants. All five of the U.S. agriboard plants operate presses with fewer
than 10 openings. Agriboard presses are| typically steam heated, although one press is heated by
hot oil.6'8 The steam-heated press at one(plant for which industry survey data are available
operates at a temperature of around 170°;F and has a 4-minute press cycle. The press heaited by
hot oil operates at around 350°F and hasja press cycle that varies from 2 to 20 min.6 Following
pressing, agriboard panels are cooled in a board cooler, cut to size, inspected, sanded, finished,
and shipped. The density of pressed agriboard panels ranges from 37 to 45; lb/ft3.6
2.2.1.3 Molded and Extruded Particleboard Process Description. The milling,
classifying, blending, and drying processes used in molded or extruded particleboard
i ' i
manufacture are generally the same as for plants that manufacture conventional particleboard.
The forming, pressing, and finishing operations at molded or extruded particleboard plants differ
from similar operations in conventional particleboard manufacture.
In molded particleboard manufacturing, dry wood particles blended with UF resin are
' routed into several presses. The presses!are not platen presses as in conventional particleboard
manufacture, but are heated molds that shape the wood particles into the finished product. Based
on the results of EPA's industry survey, [molded particleboard plants typically operate several
(e.g., 10 or more) single-opening press molds. The presses are heated by hot water to around
365°F. The density of molded particlebbard products ranges from 45 to 62 lb/ft3.6 The press
time and temperature, as well as the finished product density, vary depending on the molded
product produced. Once the molded parts exit the hot press, they are finished and stored for
!
shipment. i ;
2-10
-------
Like conventional particleboard, extruded particleboard is made from dry wood particles
blended with UF resin. Resinated particles from the blender enter an extrusion press, which is a
heated die that is either vertically or-horizontally oriented. The particles are continuously spread
over the cross-section of the heated die, while a reciprocating hydraulic ram forces the particles
through the die. The extruders cure particleboard at around 375°F.3'6
2.2.2 Emission Sources and'Controls at Particleboard Plants
The primary sources of HAP emissions at conventional particleboard plants include wood
dryers, blenders, formers, presses, and board coolers. Wood dryers are also present at molded
and extruded particleboard plants. Extruders, molded particleboard presses, and agriboard
presses are also sources of HAP emissions.
There are a total of 144 particleboard dryers and three agriboard dryers in the United
States. Table 2-2 summarizes the types of dryers and APCD used to control emissions from the
dryers. Table 2-3 presents-the number of conventional and molded particleboard rotary dryers
and APCD according to furnish type (i.e., green versus dry furnish).11
1
There are typically two to three blenders at conventional particleboard plants. The actual
numbej of blenders depends on the amount of board produced at the plant. In addition, there is
i
usually one former for each press at conventional particleboard and agriboard plants. Molded
particleboard plants with press molds or extruders do not operate formers! Although a specific
t
count of the number of blenders and formers and control devices is not attainable, no known
blenders or formers operate with HAP control devices. Most vent through baghouses.
Tables 2-4 and 2-5 summarize the APCD used to control emissions from the
particleboard presses and board coolers used in the United States. The tables also summarize
which control systems include PTE to capture and route exhaust to the APCD.12 There are a total
of 57 conventional particleboard presses. In addition, there are 41 uncontrolled press molds,
t
seven extruders, and eight agriboard presses. There are a total of 53 board coolers in use at
domestic particleboard plants. '
2-11
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TABLE 2-2. NUMBER OF PARTICLEBOARD DRYERS AND APCD
JN THP T TNTTRD STATES
APCD type
Incineration-based controls:
WESP and RTO
Multiclone, WESP, RTO
Multiclone and RTO
Semi-incineration
WESPs and wet scrubbers:
Wet scrubber
WESP
Scrubber and WESP
Multiclone and WESP
I Dry scrubbers and other controls:
Baghouse
Cyclone
Multiclone
Sand filter
EFB
Cyclone and EFB
Multiclone, EFB, and baghouse
I Uncontrolled
1 Total
=5^ i
Conventional and molded
particleboard dryers !
Rotary
2
3
4
1
'21
15
8
' 3
6
7
i 24
2
4
; i
3
34
138
Tube
3
1
4
j =
Other
__ '^^
2
2
:=:! .1 ' "M==s
Agriboard
dryer
Rotary
\
.
3
3
2-12
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TABLE 2-3. NUMBER OF PARTICLEBOARD ROTARY DRYERS
BY FURNISH TYPE AND APCD IN THE UNITED STATES
APCD type ;
Incineration-based controls:
WESP and RTO
Multiclone, WESP, and RTO
Multiclone and RTO
Semi-incineration
WESPs and wet scrubbers:
Wet scrubber ',
WESP ;
Scrubber and WESP
Multiclone and WESP ,
Dry scrubbers and other controls:
Baghouse :
Cyclone
Multiclone
Sand filter
EFB
Cyclone and EFB
Multiclone, EFB, and baghouse
Uncontrolled \
Total i
Green furnish3
2
3
4
1
8
15
8
3
1
3
3
2
2
1
3
21
80
Dry furnish3
13
5
4
21
2
13
58
Green furnish rotary dryers operate with an inlet furnish moisture content of greater than 30 percent (by weight,
dry basis) or operate with an inlet temperature of greater than 600°F. Dry furnish rotary dryers operate with an
inlet moisture content of less than or equal to'30 percent and an inlet temperature of less than or equal to 600°F.
2-13
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TABLE 2-4. NUMBER OF PARTICLEBOARD PRESSES
AND APCD! IN THE UNTIED STATES3
APCD type
Incineration-based controls:
RTO
Semi-incineration and
scrubber
WESPs and wet scrubbers:
Wet scrubber
WESP
Dry scrubbers and other controls:
Baghouse
Biofilter
Uncontrolled
Total
Conventional
parjicleboard
presses
3(3)
2(0)
2(0)
1(0)
2(2)
1(0)
146(2)
57(7)
Molded
particleboard
press molds
41(0)
41(0)
" Extruders
7(0)
7(0)
Agriboard
presses
8(0)
8 (0)
* The numbers outside of the parentheses represent the number of presses with each control device. The numbers in
parentheses indicate the number of fully enclosed presses with each control device. !
TABLE 2-5. NUMBER OJF PARTICLEBOARD BOARD COOLERS
AND APCEi IN THE UNITED STATESa l
APCD type
Incineration-based control
RTO
Semi-incineration ai
s:,
id scrubber
Dry scrubbers and other controls:
Baghouse
Biofilter
Uncontrolled [
Total
Conventional particleboard
board coolers
2(0)
' 1(0)
50(12) ;
53(12)
a The numbers outside of the parentheses represent the number of board; coolers
with each control device. The numbers in parentheses indicate the number of.
fully enclosed board coolers [with each control device.
2-14
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2.2.3 Nationwide HAP Emissions from Particleboard Plants
Nationwide baseline total HAP emissions for conventional and molded particleboard
plants are estimated to be 5,400 tons per year (tpy). The average total uncontrolled HAP
emissions per plant is 127 tpy for conventional particleboard plants'and 9 tpy for molded
particleboard plants. The average baseline HAP emissions per plant is 121 tpy for conventional
particleboard plants and 9 tpy for molded particleboard plants. Table 2-6 presents the average
uncontrolled emissions per particleboard process unit. The average emissions per plant and per
process unit were calculated as the average of the total emissions estimated for each plant and for
each process unit using the methodology documented in the baseline emissions memo.13
Nationwide baseline emissions are not estimated for agriboard plants due to lack of
available information. However, review of air permits for agriboard plants suggests that
individual agriboard plants are likely to emit far less than 25 tpy of total HAP.9'10'14
TABLE 2-6. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
" FOR PARTICLEBOARD PROCESS UNITS
Process unit
Green furnish rotary dryer
Dry furnish rotary dryer .
Tube dryer
Paddle-type dryer
Press
Board cooler
Blender/former
Refiner/hammermill
Sanders
Saws
; Average uncontrolled total HAP emissions (tpy)
Conventional particleboard
11
; 3
: . 7
-------
2.3 ORIENTED STRANDBOARD |
I :
Oriented strandboard is a structural panel produced from thin wood strands cut from
I : !
whole logs, bonded together with resin, and hot pressed. The chief markets for OSB include
sheathing, single-layer flooring, underlayment in light-frame construction, and I-joist web.
2.3.1 OSB Process Description
Figure 2-4 presents a typical process flow diagram for an OSB plant:15 Oriented
strandboard manufacturing begins with softwood or hardwood (e.g., aspen, yellow poplar) whole
logs. In northern plants, these logs are pitt in hot ponds for thawing prior to;flaking during winter
months. The logs are then debarked and Jed into the flakers. Flakers slice the logs into strands
[ i
approximately 1.5 inches wide, 4.5 to 6 inches long, and 0.025 inches thick.:1'15 The strands then
are conveyed to wet strand storage bins to await processing through the dryers.
Most OSB plants in the United States use triple-pass rotary drum dryers. Rotary dryers
are normally direct-fired with wood residue from the plant, but occasionally oil or natural gas
i I
also are used as fuels. The wood strands jare generally dried from around 60 percent moisture
(dry basis) to around 5 percent (dry basis).6 Most rotary dryers are dedicated to drying either core
or surface material to allow independent Adjustment of moisture content. T|iis independent
i ,
adjustment is particularly important where different resins are used in core and surface materials.
Rotary strand dryers operate with an inlet dryer temperature of around 1,000°F. The inlet dryer
temperature can range up to 1,600°F.6
Two plants in the United States use three-section conveyor dryers to dry OSB strands.
These dryers operate at lower-temperatures than do OSB rotary dryers. Conveyor dryers have
inlet temperatures of around 320°F. Conveyor dryers are typically indirect-heated. As for rotary
dryers, the strands in conveyor dryers are; generally dried from around 60 percent moisture (dry
basis) to around 5 percent (dry basis).6
!
After drying, the strands are conveyed pneumatically from the rotary dryer and separated
from the gas stream at the primary cyclone. Strands exiting conveyor dryers are transported on a
I !
conveyor rather than pneumatically. Dryj strands are screened to remove firies (which could
absorb excessive amounts of resin) and to separate the strands by surface area and weight.
Undesired material is sent to a fuel preparation system for the dryer burner or boiler. The
i
screened strands are stored in dry bins. } ;
2-16
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HEATING
IN HOT
POND
\RK~
BARK^O
BOILER
PRODUCT
RECOVERY
(CYCLONE)
WOOD
RECYCLE
WOOD
RECYCLE
Figure 2-4. Typical process flow diagram for an oriented strandboard plant.
2-17
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The strands are conveyed from thie dry bins to a blender, where theyiare blended with
resin, wax, and other additives. Oriented strandboard plants typically operate two or more
? I '.
blenders, one for core material and one for face material. Different resin types or formulations
!
are used in the face and core material. Face resins are typically liquid or powdered PF resins,
while core resins are PF or MDI. A few J>lants use MDI in both the face and core of the OSB
panel. The use of MDI resins for core strands is growing because MDI cures at lower
[
temperatures (and therefore faster) than PF resins.
From the blender the resinated strands are conveyed to the former, where they are
metered out on a continuously moving screen system. Screenless systems in which the OSB mat
lies directly on the conveyor belt may also be used. The strands are mechanically oriented in one
direction as they fall to the screen below.! Subsequent forming heads form distinct layers in
which the strands are oriented perpendicular to those in the previous layer. The alternating
oriented layers result in a structurally superior panel.
In the mat trimming section, the continuous formed mat is cut into desired lengths by a
traveling saw. The trimmed mat then is passed to the accumulating press loader and sent to the
hot press. Presses used in OSB manufacture are multi-opening batch presses similar to those
used in particleboard manufacture. One plant recently installed a continuous OSB press. The
batch or continuous press applies heat ai}d pressure to activate the resin and bond the strands into
I i
a solid reconstituted panel. Board densities reported in responses to the EPA's industry survey
I
ranged from 33 to 51 lb/ft3. Hot oil supplied by a thermal oil heater is used to heat most hot
i
presses. Steam generated by a boiler that burns plant residuals may also be. used to heat the
press. Presses are operated at temperatures of around 400°F with cycle times averaging around
Smin.6 j ; '.
I
Some plants cool boards following pressing. However, operation of board coolers at
I . \'
OSB plants is uncommon because hot stacking of boards made using PF resin can strengthen the
resin bond. Next, panels are trimmed to final dimensions, finished (if necessary), and the product
is packaged for shipment. Finishing may include face sanding and profiling tongue and groove
edges as well as application of edge coatings, nail lines, and trademarks or grade stamps.
2-18
-------
2.3.2 Emission Sources and Controls at OSB Plants
The primary sources of HAP emissions at OSB plants include wood dryers, blenders,
formers, presses, and board coolers. In addition to emissions from dryers and presses, HAP
emissions may also be released from some finishing operations at OSB plants. Emissions from
finishing operations are dependent on the type of products being finished. For most OSB
products, finishing involves trimming to size and possibly painting or coating the edges.
Generally, water-based coatings are used to paint OSB edges, and the resultant HAP emissions
are relatively.small. :
There are a total of 125 OSB dryers in the United States. Table 2-7 summarizes the types
of dryers and APCD used to control emissions from the dryers. Table 2-8 summarizes the
capture and control devices used to control emissions from 39 presses and two board coolers
used in the United States to manufacture OSB.12
TABLE 2-7. NUMBER OF OSB DRYERS AND APCD IN THE UNITED STATES
APCD type
Incineration-based controls:
WESP and RTO
WESP and RCO !'
Cyclone, WESP and RTO I
Multiclone, WESP, and RTO !
Multiclone and RTO ;
Rotary bed protector and RTO
Process incineration and 'baghouse ;
Process incineration and dry ESP [
Process incineration, multiclone, and dry ESP
WESPs and wet scrubbers:
WESP
Multiclone, scrubber, and WESP
Multiclone and WESP
Dry scrubbers and other controls:
Cyclone or multiclone ;
Multiclone and EFB
Uncontrolled
Total '
OSB dryers
Rotary
30
4
12
9
14
10
2
6
19
2
4
4 multiclone
5
121
Conveyor
3
1 cyclone
4
2-19
-------
TABLE 2-8. NUMBER OF OSB PRESSES AND BOARD COOLERS
AND APCD IN THE UNITED STATES
. . -' 1
APCD type
Incineration-based controls:
RTO i
RCO !
TCO
WESP and RTO !
Semi-incineration j
Other controls: |
Biofilter i
i
Uncontrolled . |
Total
OSB presses
14(13)
KD
KD
1(0)
1(0)
2(0)
19(0)
39 (15)
OSB board
coolers
2(0)
2(0)
The numbers outside of the parentheses represent the number of presses ior board
coolers with each control device. The numbers in parentheses indicate the number of
fully enclosed presses and board coolers with each control device. |
There are typically two to three blenders at OSB plants. The actual number of blenders
depends on the amount of board producjed at each plant. There is usually bne former for each
OSB press. Although a specific count f the number of blenders and formers and control devices
is not attainable, there are no known blunders or formers that operate with HAP control devices.
Most vent through baghouses.
2.3.3 Nationwide HAP Emissions from OSB Plants
Nationwide baseline total HAP'emissions from OSB plants are estimated to be 3,500 tpy.
The average total uncontrolled and baseline HAP emissions per plant'are 194 tpy and 90 tpy,
respectively. Table 2-9 presents the average uncontrolled emissions per OSB process unit. The
average emissions per plant and per process unit were calculated as the average of the total
emissions estimated for each plant and1 for each process unit using the methodology dpcumented
13 ! , ,
in the baseline emissions memo.0 ;
2-20
-------
TABLE 2-9. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR OSB PROCESS UNITS
Process unit
Rotary dryer '
Conveyor dryer :
Press
Blender/former
Average uncontrolled total
HAP emissions (tpy)
32
5a
76
11
Emissions were estimated based on rotary dryer emission factors that were scaled
down using ratios of rotary dryer and conveyor dryer formaldehyde and total
hydrocarbon. See the baseline emissions memo for details.13
2.4 MEDIUM DENSITY FIBERBOARD
The Composite Panel Association (CPA) defines MDF as a dry-formed panel product
manufactured from lignocellulosic fibers combined with a synthetic resin or other suitable
binder. Medium density^iberboard can be finished to a smooth surface and grain printed,
eliminating the need for veneers and laminates. Most of the thicker MDF panels (0.5 to
0.75 inches) are used'as core material in furniture panels. Medium density fiberboard panels
thinner than one-half inch typically are used for siding.16 Major markets for MDF include
furniture, cabinets, moulding, store fixtures, and shelving.6
2.4.1 MDF Process Description [
The general steps used to produce MDF include mechanical pulping of wood chips to
fibers (refining), drying, blending fibers with resin and sometimes wax, forming the resinated
material into a mat, and hot pressing. Figure 2-5 presents a process flow diagram for a typical
MDF plant. . '.
The furnish for MDF normally consists of hardwood or softwood chips. Wood chips
typically are delivered by truck or rail from off-site locations such as sawmills, plywood plants,
furniture manufacturing facilities, satellite chip mills, and whole tree chipping operations. If
wood chips are prepared onsite, logs are debarked, cut to more manageable lengths, and then sent
to chippers. If necessary, the chips are washed to remove dirt and other debris.
2-21
-------
FIBER
RECOVERY
CYCLONE
DRYING AND BLENDING AREA
l»
FORMING
PREPRESSING
I
MAT
TRIMMING
HOT
PRESSING 1
1
WOOD RECYCLE
PACKAGING'
SHIRRING
PAINTING/
LAMINATING
(OPTIONAL)
t
TRIMMING, '
~rt QAMniMf}
SAWING
^
BOARD
COOLING
WOOD RECYCLE
Figure 2-5. Typical process flow diagram for a medium density fiberbqard (MDF) plant.
2-22
-------
Clean chips are softened by steam and rubbed apart or ground into fibers in pressurized
refiners. Pressurized refiners consist of :a steaming vessel (digester) and of single or double
revolving disks to mechanically pulp-(refine) the chips into fibers suitable for making the board.
The wood chips are discharged under pressure from the digester section of the pressurized refiner
into the refiner section. The steam pressure is maintained throughout the entire refining process.
i i -
From the pressurized refiners, the fibers move to the drying and blending area of the
MDF plant. The sequence of the drying and blending operations depends on the method by
which resins and other additives are blended with the fibers. Most plants inject resin into a
blowline system, although some plants inject resins into a short-retention blender. If a blowline
system is used, the fibers leaving the pressurized refiners are blended with resin, wax, and other
additives in a blowpipe which discharged the resinated fibers to the dryer. After drying, the
resinated fibers are conveyed to a dry fiber storage bin. If resin is added in a blender, the fibers
are first dried and then conveyed to the blender. The fibers are blended with resin, wax, and any
other a.dditives and conveyed to a dry fiber storage bin. Urea-formaldehyde resins are the most
common resins used in the manufacture bf MDF. Melamine urea formaldehyde, PF, or MDI
resins are also used.
Medium density fiberboard plants use tube dryers. Tube dryers are either single-stage or
multiple-stage drying systems. Most of the multiple-staged tube drying systems incorporate two
stages. One plant uses a three-stage tube drying system, but the third stage at this plant does not
remove moisture from the wood material.17 In multiple-stage tube dryers, there is a primary tube
dryer and a secondary tube dryer in series separated by an emission point (e.g., a cyclonic
collector). Tube dryers (either single-stage or multiple-stage) are typically used to reduce the
moisture content of the fibers from around 47 percent to 9 percent (dry basis).6 Single-stage and
double-stage tube dryers are shown in Figures 2-6a and 2-6b. Heat is provided to tube dryers by
either indirect heating or direct firing with wood residuals, gas, or oil. Primary dryer inlet
temperatures average around 270°F and secondary dryer inlet temperatures average around
130°F.6 Wood fiber is pneumatically drawn though the tube dryers and is separated from the
dryer exhaust in a cyclonic collector. The dried wood fibers are discharged from the cyclonic
collectors into dry storage bins. Rotary dryers may also be used for pre-drying of wood material
prior to refining, but are not common.
2-23
-------
Dryer
exhaust
Figure 2-6a. Single-stage tube dryer.
First-stage
exhaust
Second-stage
exhaust
Figure; 2-6b. Double-stage tube dryer. :
2-24
-------
I
Air conveys the resinated fibers from the dry storage bin to the forming machine, where
they are deposited on a continuously moving screen system. The continuously formed mat must
be prepressed before being loaded into the hot press. After prepressing, some pretrimmmg is
done. The trimmed material is collected and recycled to the forming machine.
The prepressed and trimmed mats| then are transferred to the hot press which applies heat
and pressure to activate the resin and bond the fibers into a solid panel. Press temperatures range
from 240° to 450°F (averaging around 33JO°F), for an average press cycle of about 7 min.
Typically, the mat is cut by a flying cutoff saw into individual mats that are then loaded into a
multi-opening, batch hot press. Continuous presses may also be used for MDF manufacture.
Steam or hot oil heating of the press is common for MDF plants.6
After pressing, the boards are cooled in a board cooler. The cooled boards are sanded and
trimmed to final dimensions. Other finishing operations such as application of trademarks, grade
stamps, and fire retardants are done, and the finished product is packaged for shipment.
2-4.2 Emission Sources and Controls at MDF Plants
i
The primary sources of HAP emissions at MDF plants include emissions from
pressurized refiners, wood dryers, blenders, formers, presses, and board coolers. Finishing
operations at MDF plants may also be a source of HAP emissions. Table 2-10 summarizes the
types of MDF dryers and APCD used to control emissions from the dryers.18 Table 2-11
summarizes the capture and control systems used to control emissions from MDF presses and
board coolers used in the United States.12;
As shown in Table 2-10, there is one rotary dryer used at an MDF plant. This dryer is
used to predry green furnish before it is drjed in a tube dryer.19 There are 32 single-stage tube
dryers and 11 multiple-stage tube dryers, for a total of 43 tube drying systems at MDF plants.18
Several of the multiple-stage tube dryers have separate control devices for the first and second
i ' '
stage emission points. However, there are;some multiple-stage tube dryers where the exhaust
from the second stage is routed back through the first stage and is exhausted through the first
stage control device. There are no multiple-stage tube dryers with the second stage exhaust
routed directly to the same control device as the first stage without first passing through the first
stage. All but one of the multiple-stage tube dryers have two stages. One multiple-stage tube
dryer incorporates a tertiary stage that humidifies rather than dries the wood material processed.17
2-25
-------
APCDtype
^
[ncineration-based controls:
RTO
TO
Baghouse, WESP, and RTO
WESP and TCO
Process incineration and baghouse
Semi-incineration and WESP
WESPs and wet scrubbers:
Wet scrubbers
WESP
. "
Dry scrubbers and other controls:
Baghouse
Rotary bed protector
.... ,
Uncontrolled
======
ry tube
ersa
9
1
3
1
2
1
2
5
2
1
16
43
Secondary
tube dryersa
"- 1
1 ;
2 ,
i
7'
11 -
1 Olal _j___^^-___---=======================
' Primary tube dryers are single-stage tube dryers and the first stage of staged tube drying systems. Secondary tube
dryers are the second stage of staged tube drying systems
TABLE 2-11. NUMBER OF MDF PRESSES AND BOARD COOLERS
AND APCP IN THE UNITED STATES
Incineration-based controls:
RTO
WESP and TCO
Baghouse, WESP, and RTO
Scrubber, baghouse, WESP, and RTO
Process incineration |
Process incineration and baghouse
I.1 " ""
Other controls:
Wet scrubber
Baghouse
._. -
Uncontrolled
i Olal i 1- ^^^= -_^__^_
The numbers outside of the parentheses represent the number of presses or board coolers with each control device
ine numoers UUIMU *:,.___ if__ J. I , , , , _I^H ,»«:«.« anH hoard coolers with each control
6(5)
1(0)'
1(0)
1(0)
1(0),
2(2)
=====
;sses
)'
)
)
):
),
)
0)
8) _
MDF board
coolers
6(4)
Id)
24(4)
.31(9)
device.
b This enclosure is not a PTE, but was tested and achieved 99.8% capture efficiency.6
2-26
-------
Because the tertiary stage does not function as a dryer, it was not included in Table 2-10. The
tertiary stage is routed to the RTO usedto control the first and second stages of the multiple-
stage tube dryer.
Process flow diagrams and other information submitted with" the industry survey
responses were reviewed to approximate the number of pressurized refiners used by MDF plants.
Given the varying level of detail on the flow diagrams, obtaining an exact count of pressurized
refiners was not possible. The flow diagrams show that there are approximately 30 pressurized
refiner systems at MDF plants. At least seven (and possibly as many as 14) of these pressurized
refiners vent directly into tube dryers that are controlled with incineration-based controls. Thus,
the emissions from the pressurized refiriers are also controlled by incineration. In addition to the
pressurized refiners, there appear to be two stand-alone digesters and 12 atmospheric refiners at
MDF plants. Emissions from the stand-alone digesters and atmospheric refiners are not
controlled.20 !
Blenders are operated by MDF plants that do not perform blowline blending. Thus, most
MDF plants do not operate blenders. Formers are used by all MDF plants. There is one former
per MDF press. Although a specific count of the number of blenders and formers and control
devices is not attainable, there are no known blenders or formers that operate with HAP control
devices. Most vent through baghouses.:
2.4.3 Nationwide HAP Emissions from MDF Plants
Nationwide baseline.total HAP emissions for MDF plants are estimated to be 2,500 tpy.
The average uncontrolled and baseline total HAP emissions per plant are 168 tpy and 103 tpy,
respectively. Table 2-12 presents the average uncontrolled emissions per MDF process unit. The
i
average emissions per plant and per process unit were calculated as the average of the total
emissions estimated for each plant and for each process unit using the methodology documented
in the baseline emissions memo.13
2-27
-------
TABLE 2-12. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR MDF PROCESS UNITS '
Process unit ;
i
Primary tube dryer i
Secondary tube dryer j
Green furnish rotary dryer j
Blender/former (non-blowline blend plants)
Former (blowline blend plants)
\
Press i
Board cooler i
i
Sanders i
Saws '
Average uncontrolled total
HAP emissions (tpy)
65
2
<1
8
2
38
3;
<1.
<1
2.5 FJBERBOARD/HARDBOARD j
Fiberboard products include: (l)llow-density insulation board or ce.llulosic fiberboard
(called "fiberboard" in this document), (J2) MDF (discussed in Section 2.4 above), and
i i
(3) hardboard. The most frequently used raw material for production of fiberboard products is
wood chips which are first softened in a[ pressurized steam vessel (digester) and then refined or
t r
pulped into wood fibers. The fibers may be mixed with resin, formed into mats, and pressed
and/or dried to form panel products.
l
Fiberboard products are manufactured through dry processing, wet;processing, or wet/dry
processing. Dry processing involves dry mat forming and pressing, while wet processing
involves wet forming and wet pressing.
Wet/dry processing involves wet forming followed by
dry pressing. Fiberboard is manufactured by wet processing. Dry processing is used to
manufacture MDF. Hardboard may be manufactured by wet processing, dry processing, or
wet/dry processing. Figure 2-7 summarizes the processes used to manufacture fiberboard
products. Resin is used in wet hardboarcl and dry hardboard processing, but not in wet/dry
hardboard or fiberboard processing.
2-28-
-------
Wood chips and raw materials
WOOD REDUCTION AND ADDITIVE ADDITION
>-. o
* J
TUBE DRYER
WET FORMING
DRY FORMING
CONVEYOR DRYER
PRESSING
BAKE OVEN
HUMIDIFICATION
FINISHING
Fiberboard products
Figure 2-7. Fiberboard products manufacturing processes.
2-29
-------
Major markets for fiberboard include housing, roofing, and office furnishings. Hordboard
markets include, among others, housing (e.g., exterior siding, garage doors, and interior door
facings), furniture, store fixtures, automotive interiors, and toys.6
2.5.1 Fiberboard/Hardboard Process Description
2.5.1.1 Drv Process Hardboard. Dry processing of hardboard is similar to MDF
manufacturing. As in MDF manufacture, the general steps used to produce dry process
hardboard include mechanical pulping of hardwood or softwood chips to fibers (digesting and
refining), blending of fibers with resin an;d wax, drying, forming the resinated material into a
i ;
mat, and hot pressing. Heat treatment and humidification of the pressed boards is an additional
step in the hardboard manufacturing procpss that is usually not necessary for MDF manufacture.
The primary raw material used in jhardboard is wood chips. In addition to wood chips,
some plants use shavings or sawdust as a raw material. If wood chips are prepared onsite, logs
are debarked, cut to more manageable lengths, and then sent to chippers. If necessary, the chips
are washed to remove dirt and other debris.
Clean chips are either processed in pressurized refiners, as used in MDF manufacture, or
are softened by steam in a digester and sent to atmospheric refiners. Atmospheric refiners use
single or double revolving disks to mechanically pulp the chips into fibers suitable for making
hardboard. Wax may be added to the wojod chips in the digester. The PF resin and other
additives (if used) are added to the wood'fiber immediately following refining. Most hardboard
plants inject PF resin into a blowpipe that discharges the resinated fibers to a tube dryer.
However, there is one hardboard plant that operates rotary dryers to dry resinated furnish. The
resin is added to the rotary dryer furnish jas it is refined prior to drying.11 After drying, the
resinated fibers are conveyed to a dry fiber storage bin where they await forming.
Single- or multiple-stage tube dryers are most commonly used in dry process hardboard
manufacture. Hardboard primary tube dryers dry wood fibers from about 51 percent moisture
(dry basis) to around 20 percent moisturi (dry basis) with dryer inlet temperatures ranging from
145° to 475°F (averaging around 280°F)'. Secondary tube dryers further dry the wood furnish to
around 6 percent moisture (dry basis).6 Heat is provided to the hardboard tube dryers by either
direct-firing with wood residuals, gas, of oil or by indirect-heating. One plant uses indirect-
heated, triple-pass rotary dryers to dry the wood fiber. The inlet temperature of the rotary dryers
2-30
-------
is about 550°F and the wood fiber is dried from roughly 45 to 9 percent moisture (dry basis).6
Wood fiber is pneumatically drawn though the hardboard dryers and is separated from the dryer
exhaust in a cyclonic collector.
Dried, resinated fibers next enter .a forming machine where they are deposited on a
continuously moving conveyor. The mat is prepressed and trimmed before being loaded into the
hot press. The press applies heat and pressure to activate the PF resin and bond the fibers into a
solid board. Dry process hardboard plants use a multi-opening batch press. The typical press
cycle is about 4 min. The hardboard presses are heated by steam to an average temperature of
around 410°F.6 Following pressing, boards are routed through a board cooler at some plants.
However, most plants do not operate board coolers.6
Hardboard plants typically heat treat the pressed hardboard in a bake or tempering oven.
The purpose of heat treatment is to lower the moisture content of pressed hardboard to bone dry
levels to improve dimensional stability and enhance board mechanical properties. Linseed oil is
sometimes applied to the hardboard prior to heat treatment. Hardboard ovens are either indirect-
heated or direct-fired and operate at temperatures up to 340°F.6 Humidification of boards is done
immediately following heat treatment to bring the board moisture content back into equilibrium
with ambient air conditions.21 Humidifiers are often integrated with hardboard ovens (i.e., the
boards coming out of the hardboard oven go straight into the humidifier). Following
humidification, the hardboard is finished: and packaged for shipment. Dry process hardboard
densities range from 39 to 69 Ib/ft3.6 , ,
2.5.1.2 Wet Process Fiberboard. The general steps in production of fiberboard
manufacture include pulping of hardwood or softwood wood chips, wet forming, drying, and
finishing. The wood chips for fiberboard may either be steamed in digesters or soaked in hot
process water before being ground into fiber in atmospheric refiners. .From the refiners, fibers
are sometimes washed to remove wood sugars that might reduce the quality of the finished
product. The refined and/or washed fibers are sent to stock chests to await further processing.
The fibers from the stock chests are mixed with water and additives such as alum, starch, asphalt,
and wax. Resins are hot used in fiberboard production. The wood fibers are bonded together by
additives and substances naturally contained in the wood. Alum aids in the precipitation of wax,
2-31
-------
asphalt, and rosin onto wood fibers. Bonds between these substances and the wood fibers assist
in holding the fiber mat together.21 [
Once mixed with additives, the fiber slurry is sent to the forming machine. In the wet
forming process, the water-fiber mixture is metered onto a wire screen. Water is drained away
by gravity and with the aid of suction applied to the underside of the wire. The fiber mat along
with the supporting wire is moved to a rpom-temperature pre-press where excess water is
squeezed out. Once pre-pressed, the fiber mat is cut to length and trimmed on the edges with
i
high-pressure water jets.
The fiber mats, which are around 60 percent moisture (dry basis), are passed through a
i i
conveyor-type mat dryer where their moisture content is reduced to about 4 percent. Fiberboard
mat dryers operate with inlet temperatures of around 450°F and outlet temperatures of around
320°F. Finished fiberboard density ranges from 12 to 24 lb/ft3.6 Once dried the fiberboard is
trimmed and may be coated with asphalt. Next, the fiberboard is packaged for shipment.
2.5.1.3 Wet Process Hardboard. Production of wet process hardboard includes pulping
of wood chips, wet forming, pressing, heat treatment, humidification, and finishing. Phenol-
formaldehyde resin, wax, and alum are used in wet process hardboard manufacturing.
Hardwood or softwood chips may either be purchased from outside or generated onsite
from logs. The chips are washed to remove dirt and debris. The chips are then steam cooked
underpressure in digesters to soften the; chips and liberate the wood sugars. After cooking, the
softened chips are refined in a single- or double-disc atmospheric refiner (referred to as the
primary refiner), which grinds the chips' into fiber form. The fibers from the primary refiner are
subsequently fed into stock washers, wh" ich use water and pressure to wash out the wood sugars.
After washing, the wood material is further refined in a secondary refiner.?2 Some plants may
omit secondary refining.
Once refined the wood fiber is mixed with water; -alum, PF resin, and wax in stock or mix
[ !
chests. The alum is added to the fiber slurry to control pH and help precipitate the resin and wax
onto the fibers. The dilute slurry of fiber, additives, and water is routed to a wet forming
i
machine. At some plants, the forming machine may have separate header boxes where separate
slurries may be used to make layers in the hardboard mat. The top layer of the fiber mat is called
an "overlay" and the bottom layer is called a "substrate." The wood fiber used to make; the
2-32
-------
overlay undergoes additional refining prior to chemical addition and dilution so that the top layer
of the hardboard will have a smoother finish. The fiber slurry from the substrate head box and
the overlay head box are fed onto a moving wire screen (forming machine) where they
immediately begin to form a continuous fiber mat. Water drains through the wire screen first by
gravity and then by suction. The fiber mat is compressed with press rolls and further dewatered.
i j _ . ...
The edges of the fiber mat may be trimmed with water jets prior to hot pressing.21*22
The carrying wire takes the fiber mats to a preloader to await pressing. The fiber mats are
loaded into the press so that each mat is paired with a patterned caul plate which imparts the
pattern onto the top of the mat during pressing. The bottom side of the hardboard bears the
pattern of the carrying wire. Water released from the mats during pressing cascades down the
sides of the press and is recycled. The fiber mats enter the press at a moisture content of about
120 percent (dry basis).6 Wet process hardboard presses are typically multi-opening, steam-
heated, batch presses. The hardboard mats are pressed for roughly 8 min at,around 390°F.6
As with dry process hardboard, the wet process hardboard mats may be transported to the
hardboard ovens where the mats are dried to "bone-dry" levels following pressing. Further
drying of the mats increases bonding and makes the hardboard more resistant to water. Once
dried, the boards may be cooled and are then rehumidified to prevent buckling and to improve
the overall dimensional stability of the boards. Final wet process hardboard densities range from
50 to 70 lb/ft3.6 ' :
2.5.1.4 Wet/Dry Process Hardboard. Production of wet/dry process hardbpard includes
pulping of softwood or hardwood chips, iwet forming, drying, pressing, heat treatment,
humidification, and finishing. Wet/dry process hardboard production is similar to fiberboard
production until the pressing step of the process is reached. The pressing, heat treatment, and
humidification steps in wet/dry hardboard production are similar to the same steps in wet
hardboard production. Raw materials used in the production of wet/dry hardboard include wood
chips and additives such as linseed oil, asphalt, and wax. No resin is used in the production of
wet/dry hardboard.6-23 ;
Wood chips may either be purchased from offsite or generated onsite from logs. The
chips are washed to remove dirt and debiris. The chips are then steam cooked under pressure in
digesters. After cooking, the chips are refined in primary and/or secondary refiners. Some plants
2-33
-------
may omit secondary refining. Some plants may use pressurized refiners (like those used in MDF
and dry process hardboard manufacture) in lieu of stand-alone digesters and atmospheric refiners.
Once refined the wood fiber is mixed with water and wax in stock or mix chests. The
i i
dilute slurry of fiber, additives, and water is routed to a wet forming-machine. As with wet
processing of hardboard, some plants may use separate substrate (bottom layer) and overlay (top
layer) forming header boxes to make a layered hardboard mat. The fiber slurry from the substrate
head box and the overlay head box are fed Onto a moving wire screen (forming machine) where
i ;
they immediately begin to form a continuous fiber mat. Water drains through the wire screen
first by gravity and then by suction. The fiber mat is compressed with press rolls which assist in
further dewatering the mat. The edges of the fiber mat may be trimmed with water jets prior to
drying.
The fiber mats, which are around'60 percent moisture (dry basis), are passed through a
i . i
conveyor-type mat dryer where their moisture content is reduced to around 4 percent. Mat dryers
operate with inlet temperatures of around 450°F and outlet temperatures of; around 320°F.6 From
the dryer, the fiber mats pass through a p|ress predryer or preheat oven. The purpose of the
predryer is to reduce the mat moisture content in order to minimize the hoipress cycle.17 Steam-
heated batch presses are used in wet/dry hardboard manufacturing. Press temperatures average
around 470°F for press cycle times of nearly 4 min.6 As for dry and wet process hardboard, the
wet/dry process hardboard mats are heat'treated in hardboard ovens following pressing. Wet/dry
process hardboard densities range from 45 to 72 lb/ft3.6
2.5.2 Emission Sources and Controls atlFiberboard/Hardboard Plants ;
The primary sources of HAP emissions at fiberboard/hardboard plants are mat conveyor
dryers, tube dryers, hardboard ovens, press preheat ovens, and hot presses.; Board coolers and
humidifiers may also be sources of HAP emissions at hardboard plants. Tables 2-13 and 2-14
summarize the number of each type of dryer, oven, or humidifier used to manufacture
fiberboard/hardboard and the APCD usejd to control emissions from these sources.18 Table 2-15
summarizes the number of hardboard presses and board coolers and the capture and control
systems used to control emissions from the presses and coolers.12
2-34
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TABLE 2-13. NUMBER OF FffiERBOARD/HARDBOARD DRYERS
AND APCD IN THE UNITED STATES
APCD type "
WESPs and wet scrubbers:
Wet scrubber only ;
Dry scrubbers and other controls:
Baghouse
Cyclone
Uncontrolled
Total , '
Primary tube
dryers
8
3
3
10
24
Secondary tube
dryers
8
3
11
Rotary dryers
3
3
TABLE 2-14. NUMBER OF FIBERBOARD/HARDBOARD MAT DRYERS, OVENS,
AND HUMIDIFIERS AND APCD IN THE UNITED STATES
APCD type
Incineration-based controls:
RTO
RCO
Semi-incineration
Semi-incineration and scrubber
WESPs. and wet scrubbers:
Wet scrubber only
Uncontrolled
Total
Press preheat
i ovens
1
1
: 3
i 5
Hardboard/
fiberboard mat
conveyor dryers
1
1
la
1
- 7
11
Hardboard
ovens
2
1
2
.15
20
Hardboard
humidifiers
23
23
This dryer is used to dry a bagaSse fiber mat. All of the other dryers dry wood fiber mats.
TABLE 2-15. NUMBER OF HARDBOARD PRESSES AND
APCD IN THE UNITED STATES3
APCD type !
Incineration-based controls:
RTO
WESPs and wet scrubbers:
Wet scrubber only
Dry scrubbers and other controls:
Biofilter ;
Multiclone : i
Cyclone
Uncontrolled
Total
Hardboard presses
KD
8(3)
2(1)
1(0)
1(0)
27(0)
40(5)
Board coolers
2(1)
17 (2)
19 (3)
The numbers outside of the parentheses represent the number of presses or board coolers with each control device.
The numbers in parentheses indicate the number of fully enclosed presses and board coolers with each control
device. i
2-35
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As shown in Table 2-13, there are three rotary dryers that are used at one dry process
hardboard plant to dry green, resinated furnish. There is no subsequent drying of the furnish
once it leaves the rotary dryers.13 There are 13 single-stage tube dryers and 11 multiple-stage
tube dryers, for a total of 24 tube drying systems at dry process hardboard plants.18 All of the
controlled multiple-stage tube dryers havje separate control devices for the first and second stage
emission points. ; ;
Digesters and refiners (including pressurized refiners, stand-alone digesters, and
atmospheric refiners) are also sources of jHAP emissions at fiberboard and hardboard plants.
Process flow diagrams and other information submitted with the industry survey responses was
reviewed to approximate the number of digesters and refiners used by fiberboard/hardboard
plants. Given the varying level of detail bn the flow diagrams, obtaining an exact count of these
equipment was not possible. However, from the flow diagrams there appear to be at least 13
pressurized refiner systems at fiberboard/hardboard plants. Most of these pressurized refiners
vent directly through tube dryers. There!also appear to be 24 stand-alone digesters at fiberboard
i I
and hardboard plants. None of these digesters appears to be controlled. In Addition, the flow
diagrams show approximately 61 atmospheric refiners, all of which are uncontrolled.20
Wet process hardboard and fiberboard plants use wet formers. There is typically one
former per press at hardboard plants and one former per process line for fiberboard plants. Most
wet formers are uncontrolled; however, One wet/dry hardboard plant operates a scrubber on a wet
former. Dry formers are used by all dryjprocess hardboard plants. There is typically one former
per dry hardboard press. No dry hardboard formers are known to be controlled.
Additional HAP emissions may be associated with finishing operations at hardboard and
fiberboard plants. Emissions from finishing operations are dependent on the type of products
being finished. Edge seals, anti-skid coatings, or primers may be added toifiberboard or
hardboard products. Some fiberboard products are coated with asphalt. In addition, company
logos, trademarks, or grade stamps may be applied.
2.5.3 Nationwide HAP Emissions from Fiberboard/Hardboard Plants
The estimated nationwide and plant average baseline total HAP emissions for hardboard
and fiberboard plants are presented in Table 2-16. Table 2-17 presents the average uncontrolled
emissions per hardboard and fiberboard process unit. The average emissions per plant and per
2-36
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process unit were calculated as the average of the total emissions estimated for each plant and for
each process unit using the methodology documented in the baseline emissions memo.13 Only
those process units for which emission factors are available are included in Table 2-17.
Emissions from blenders, board coolers, Sanders, and saws, were not estimated. However, it is
expected that the magnitude of the emissions from these process units would be similar to the
emissions from similar process units at plants making other PCWP.
TABLE 2-16. AVERAGE BASELINE TOTAL HAP EMISSIONS FOR
FBERBOARD/HARDBOARD PROCESS UNITS
Hardboard/fiberboard
process
Fiberboard
Wet process
hardboard
Wet/dry process
hardboard
Dry process hardboard
Total3
Nationwide baseline
total HAP emissions
(tpy) '
78
1,000 ;
. 340 !
1,900
3,300 !
Average total HAP emissions per plant (tpy)
Uncontrolled
11
128
125
245
Baseline
11
128
86
240
Total may not sum exactly due .to rounding.
2.6 SOFTWOOD PLYWOOD :
I
Softwood plywood is a building material consisting of veneers (thin wood layers or plies)
bonded with an adhesive. Softwood plywood is generally made by gluing several layers of
softwood veneer together. Softwood plywood is used for exterior applications such as sheathing,
roof decking, concrete formboards, floors, and containers.
2-37
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TABLE 2-17. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR HBERBOARD/HARDBOARD PROCESS UNITS
', \
Process unit \
Log chipper
Fiberboard mat dryer
Fiber washer :
Atmospheric refiners
Wet former
Hardboard oven
Digester/refiners j
1
Humidifier [
Press ;
i
Press predryer '
Primary tube dryer :
Secondary tube dryer
Green furnish rotary dryer i
Average uncontrolled total
HAP emissions (tpy)
«1
9
6a
-------
VENEER
LAYUP AND
GLUE SPREADING
LOG DEBARKING
' AND BUCKING
VENEER DRYER
LOG STEAMING/
SOAKING
VENEER CUTTING
PLYWOOD
FINISHING
FINISHED
PRODUCT
Figure 2-8. Generic process flow diagram for a plywood mill.
are heated in a roughly 200°F medium such as hot water baths, steam heat, hot water spray, or a
combination of the three until the core temperature has reached around 105°F.24'25
After heating, the logs are processed to generate veneer. For most applications, a veneer
lathe is used, but some veneer is generated with a veneer slicer. The slicer and veneer lathe both
work on the same principle; the wood is compressed while the veneer knife cuts the blocks into
veneers that are typically 0.125 inches thick. These pieces are then clipped to a usable width,
typically 54 inches, to allow for shrinkage and trim.24
Veneers are taken from the clippe'r to a veneer dryer where they are dried to moisture
contents that range from 1.5 to 25 percent and average around 9 percent (dry basis). Target
moisture contents depend on the type of resin used in subsequent gluing steps. The typical
drying temperature is around 360°F.6 The veneer dryer may be a longitudinal dryer, which
circulates air parallel to the veneer, or a jet dryer. Jet dryers have jet tubes to direct hot air onto
the surface of the veneers. Veneer dryers may be either direct-fired or indirect-heated. In
direct-fired dryers, the combustion gases are blended with recirculated exhaust from the dryer to
reduce the combustion gas temperature. Air is warmed over steam coils and circulated over the
1 -
veneer in indirect-heated veneer dryers. Veneer dryers are divided into separate air circulation
zones, with each zone having a hot air soprce, fans to move the warm air, and an exhaust vent or
2-39
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stack. Veneer dryers typically have one^o three heated zones followed by a cooling zone or
section. The cooling section circulates ambient air over the veneer to reduce the veneer
temperature just before it exits the dryer1. The veneers must be cooled to prevent glue from
curing on the veneers before they reach the plywood press. A few plants in the United SJtates dry
veneer in kilns. Kiln drying is a batch pperation where the veneers are stacked with stickers
i
(narrow wood strips) and dried in the kiln. \
Veneer moisture is checked against the target moisture level as the veneer exits tihe dryer.
Some plants operate veneer redryers to redry veneer that did not reach the target moisture
content.' The veneer that must be redried is called "redry." Most plants operate in order to
minimize the amount of redry, and often attempt to limit the amount of redry to five percent of
the veneer produced.26 Veneer redryers are typically heated by radio frequency (RF) and are
designed to handle only a fraction of the throughput from full-scale veneer dryers.
When the veneers have been dried to their specified moisture content^ they are glued
together. Most softwood plywood plants use PF resin. However, one plant that manufactures
plywood from mixed hardwood and softwood species uses UF resin.6 Resin is applied to the
veneers by glue spreaders, curtain coaters, or spray systems. Generally, resin is spread on two
sides of one ply of veneer, which is then placed between two plies of unresinated veneer. Curtain
coaters or spray systems are used on automated plywood layup lines. With these systems, veneer
passes under the coater or spray, an unresinated veneer is placed on top of the resinated veneer,
the two stacked veneers pass under a second coater, another unresinated veneer is added to the
stack, and so on, until the plywood panel is formed.
Assembly of the plywood panels must be symmetrical on either side of a neutral center in
order to avoid excessive warpage. For example, a five-ply panel would be laid up in the
following manner. A back, with the grain direction parallel to the long axis of the panel, is
placed on the assembly table1. The next; veneer has a grain direction perpendicular to that of the
back, and is spread with resin on both sides. Then, the center is placed, with no resin, and with
the grain perpendicular to the previous veneer (parallel with the back). The fourth veneer has a
[
grain perpendicular to the previous veneer (parallel with the short axis of the panel) and is spread
f : , | ,
with resin on both sides. The final, face, veneer with no resin is placed like the back with the
i
grain parallel to the long axis of the plywood panel.
2-40
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The laid-up assembly of veneers then is sent to a hot press in which it is consolidated
under heat and pressure. Hot pressing has two main objectives: (1) to press the glue into a thin
layer over each sheet of veneer; and (2) to activate the thermosetting resins. Typical press
temperatures range from 200° to 380°F (averaging around 310°F), while press times average
around 7 min. The time and temperature vary depending on the wood species used, the resin
used, and the press design. Plywood presses are most often steam heated, although some are
heated by hot oil.6
The plywood then is taken to a finishing process where edges are trimmed. Wood putty
or synthetic patches may be applied to defects in plywood faces prior to sanding. The face and
back of the plywood panel may or may not be sanded smooth. Concrete forming oil may be
applied to plywood destined for use as concrete forms. Overlays may be applied to some
plywood panels. The type of finishing depends on the end product desired. Edge sealers, logos,
trademarks, and grade stamps are routinely applied to stacks of plywood panels.
2.6.2 Emission Sources and Controls at Softwood Plywood and Veneer Plants
j
The primary sources of HAP emissions at plywood plants are veneer dryers and plywood
presses. There are a total of 280 veneer dryers at softwood plywood plants in the United States.
Table 2-18 summarizes APCD used to control emissions from the veneer dryers.27 In addition,
there are two softwood veneer kilns and nine uncontrolled RF veneer dryers (primarily used as
re-dryers) in the United States.6 None of the 226 softwood plywood presses used in the United
States are operated with an APCD. However, three presses were reported to be enclosed.12
There are a total of eight board coolers in use at softwood plywood plants in the United States.
None of the board coolers exhaust through a control device, although one cooler was reported to
be fully enclosed.12 In addition to dryers and presses, miscellaneous finishing operations at
plywood plants may also be sources of HAP emissions.
2-41
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TABLE 2-18. NUMBER OF VENEER DRYERS AND APCD AT
SOFTWOOD PLYWOOD PLANTS IN THE UNITED STATES
APCD type
Incineration-based controls: I
RTO
RCO
TO !
Process incineration
Process incineration and scrubber
Semi-incineration and scrubber
Semi-incineration and multiclone
WESPs and wet scrubbers:
Wet scrubbers
WESP
Scrubber and WESP
Dry scrubbers and'other controls:
EFB
Uncontrolled
Total
Softwood veneer
dryers3
44
7
3
5
5
8
2
47
36
4
. 8
105
274
Hardwood veneer
; dryers3
6
6
a Softwood veneer dryers dry 30 perpent or more (on a volume basis) softwood species.
Hardwood veneer dryers dry less than 30 percent softwood species. '
Nationwide HAP Emissions from Softwood Plywood and Veneer Plants
Nationwide baseline total HAP emissions from softwood plywood and veneer plants are
estimated to be 3,700 tpy. The average total uncontrolled HAP emissions per plant is 38 tpy.
The average total baseline HAP emissions per plant is 36 tpy. Table 2-19 presents the average
uncontrolled emissions per softwood plywood and veneer process unit. The average emissions
f
per plant and per process unit were calculated as the average of the total emissions estimated for
each plant and for each process unit using the methodology documented in the baseline
emissions memo.
13
2-42
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TABLE 2-19. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR SOFTWOOD PLYWOOD AND VENEER PROCESS UNITS
Process unit
Softwood veneer dryer j
Hardwood veneer dryer :
Softwood veneer kiln
RF veneer redryer
Log vats
Veneer and panel chippers
Press ;
Sanders
Saws ' '
Average uncontrolled total
HAP emissions (tpy)
5""
8
<1
<1
1
2
7
2'
1
2.7 HARDWOOD PLYWOOD ,
. Unlike softwood plywood plants which typically produce softwood veneers and softwood
plywood on the same plant site, the majority of the plants in the hardwood plywood and veneer
industry typically produce either hardwood plywood or hardwood veneer. Hardwood veneer
plants cut and dry hardwood veneers. Hardwood plywood plants typically purchase hardwood
veneers and press the veneers onto a purchased core material. Only around 15 percent of
hardwood plywood plants cut and dry veneer onsite. As a result, hardwood plywood and
hardwood veneer plants are generally smaller than softwood plywood plants in terms of number
of employees and production.6'26 ;
Hardwood plywood is made of hardwood veneers bonded with an adhesive. The outer
layers surround a lumber, veneer, particleboard, or MDF core. Hardwood plywood may be
pressed into panels or plywood components (e.g., curved hardwood plywood, seat backs, chair
arms, etc.). Hardwood plywood is used for furniture, cabinets, architectural millwork, paneling
for commercial buildings, flooring, store; fixtures, and doors.26 Hardwood veneer is used for
i
hardwood plywood, furniture, doors, flooring, and produce containers.
2-43
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2.7.1 Hardwood Plywood and Veneer Process Description
The manufacture of hardwood veneer and plywood consists of the following processes:
I i
log debarking and bucking, "heating the logs, cutting the logs into veneers, drying the veneers,
gluing the veneers together, pressing the veneers in a hot press, andTmishing. Figure 2-9
provides a generic process flow diagram jfor hardwood veneer and plywood manufacturing. As
mentioned earlier, cutting and drying of veneers typically occurs at a hardwood veneer plant
while layup and pressing of the plywood occurs at a separate hardwood plywood plant. A few
plants produce both hardwood veneer anil plywood on the same plant site. The veneer and
plywood manufacturing process is essentially the same, regardless of whether the veneers are
produced at the same site where the plywood is produced, or at an offsite location.
i
~-T~ "1
,
eneer pla
wood plywood a
Ha
Blocking/
Debarking
Log steaming
or soaking
Veneer
cutting
Veneer drying
O
n
3
Cl>
Glue spreading and;
veneerlayup [
esin
Core material
Hardwood
plywood
Hardwood veneer plan
ood plan
Hardwood p
Figure 2-9. General steps in hardwood veneer and plywood manufacturing.
2-44
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2.7.1.1 Hardwood Veneer Process Description. The initial step of log debarking is
accomplished by feeding logs through one of several types of debarking machines. The purpose
of this operation is to remove the outer bark of the tree without substantially damaging the wood.
After the bark is removed, the logs are cut to veneer lengths in a step known as bucking.
The logs (now referred to as blocks or flitches) then are heated to improve the cutting
action of the veneer lathe or slicer, thereby generating a veneer with better surface finish. Blocks
are heated using hot water baths, steam heat, or hot water sprays.24
After heating, the logs are processed to generate veneer. A veneer lathe may be used for
rotary cutting or a veneer slicer may be used to slice veneers. Depending on the way the veneer
is cut, different visual effects may be achieved/with the wood grain. Lumber may also be sliced
into veneer. The slicer and veneer lathe both work on the same principle; the wood is
compressed while the veneer knife cuts the flitches or blocks into veneers ranging in thickness
from around 0.024 to 0.125 inches thick.26 Rotary peeled veneers are clipped to appropriate
widths before further processing. :
Veneers are taken'from the slicer pr clipper and dried in a veneer dryer. Typical drying
temperatures are around 250° to 300°F; however, drying temperatures as low as 110°F and as
high as 450°F have been reported. Veneer dryers may be described by heating method and air
flow pattern. Most hardwood veneer dryers are indirect-heated (or steam heated), but some are
direct-fired. The air flow patterns for hardwood veneer dryers may be either longitudinal or jet.
Veneer kilns are also used in hardwood veneer manufacturing.26 For kiln drying, the veneers are
piled and stickered (separated by wood sticks) and placed in the veneer kiln where they are
dried.Kiln drying is a batch process. Most kilns used for hardwood veneer manufacturing are
indirect-heated. .
Once the veneers have been dried; they may be glued together on the edges with glue
thread to form larger sheets of veneer. This process is called composing. Narrow veneer slices
must be composed before they are used in plywood panels or other products requiring wider
veneer sheets. Composing may be performed at the veneer plant or by the plant which purchases
the veneers. Some facilities purchase narrow veneers only to compose them and resell larger
sheets of veneer. Once composed (if necessary), the' veneers are shipped or used onsite to
manufacture plywood or other products (e.g., furniture, doors, flooring, etc.).
2-45
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2.7.1.2 Hardwood Plvwood Process Description. At the hardwood plywood plant, dried
I :
veneers are glued together with a thermbsetting resin and hot pressed. Urea-formaldehyde resin
is the most commonly used resin for hardwood plywood manufacturing. However, some plants
use polyvinyl acetate (PVA), melamine--formaldehyde (MF), MUF, or PF resins as dictated by
the end use for the plywood product.26 The UF, MF, MUF, and PVA resins are colorless or light
in color, making them suitable for use v/ith thin hardwood face veneers. These resins offer water
resistance appropriate for indoor applications. The PF resin is a dark-colored, water-proof resin
used for structural grade plywood panels (e.g., a product similar to softwopd plywood made from
poplar or gum veneers).28 ; :
The resins are typically applied to the core panels or veneers by glue spreaders. Spreaders
have a series of application rolls that apply the resin to both sides of a sheet of core veneer or
core panel such as MDF or particleboard. The hardwood veneer back and face is applied to
either side of the resinated core material. For example, a sheet of hardwood.veneer is laid down
for the panel back, resinated core material is placed on the hardwood veneer, and a sheet of
hardwood veneer is placed on top of the resinated core to form the panel face. If veneer cores are
used to construct the plywood panel, then the grain of each veneer is laid perpendicular to
adjacent veneers in the panel. .
The laid-up assembly of veneers is then taken to a cold press for prepressing. Next the
panels are placed in a hot press which applies heat and pressure to cure the resin in the panels.
Typical press temperatures range from 210° to 260°F for hardwood plywood, while press times
range from less than 1 to 45 min. The average press cycle time is around 6 min for hardwood
plywood.26 Press time and temperature vary depending on the wood species used, the resin used,
and the press design. Both single-open'ing and multi-opening presses are used for hardwood
plywood. Single-opening presses may be heated by conventional methods (i.e., hot oil, hot
water, or steam), RF, or electricity. Multi-opening presses used for hardwood plywood
i
manufacturing are heated by conventional means. A few presses with two to four openings are
1 u
heated by RF. Radio-frequency presses are frequently used for manufacture of plywood
components or curved plywood produces that cannot be placed in platen presses..
2-46
-------
Once pressed, the hardwood plywood then is taken to a finishing process where edges are
trimmed and the face and back may or rriay not be sanded smooth. The type of finishing depends
on the end product desired.
2.7.2 Emission Sources and Controls at Hardwood Plywood and Veneer Plants
The primary sources of HAP emissions at hardwood plywood plants are veneer dryers
and presses. Table 2-20 summarizes APCD used to control emissions from the veneer dryers at
hardwood plywood plants.27 In addition to the veneer dryers listed in Table 2-20, eight
uncontrolled hardwood veneer kilns are operated at hardwood veneer plants in the United States.
None of the 321 hardwood plywood presses used in the United States are operated with an
APCD.26 Composing and finishing operations at hardwood plywood plants may also be a source
of HAP emissions. ;
TABLE 2-20. NUMBER OF VENEER DRYERS AND APCD AT
HARDWOOD PLYWOOD PLANTS IN THE UNITED STATES
t
APCD type
Incineration-based controls:
Semi-incineration ;
Semi-incineration and scrubber
WESPs and wet scrubbers:
« Wet scrubbers
Dry scrubbers and other controls: ;
EFB
Uncontrolled
Total
Softwood veneer
dryers
2
6
3
12
23
Hardwood veneer
dryers
1
'
166
167
Softwood veneer dryers dry 30 percent or more (on a volume basis) softwood species. Hardwood
veneer dryers dry less than 30 percent softwood species.
2.7.3 Nationwide HAP Emissions from Hardwood Plywood and Veneer Plants
Nationwide baseline total HAP emissions from hardwood plywood and veneer plants are
estimated to be 161 tpy. The average total uncontrolled and baseline HAP emissions per plant
are 1 tpy. Table 2-21 presents the average uncontrolled emissions per hardwood plywood and
2-47
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veneer process unit. The average emissions per plant and per process unit were calculated as the
average of the total emissions estimated for each plant and for each process unit using the
methodology documented in the baseline emissions memo.13
i
TABLE 2-21. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR HARDWOOD PLYWOOD AND VENEER PROCESS UNITS
Process unit
Softwood veneer dryer
Hardwood veneer dryer
Hardwood veneer kiln
Press i
Average uncontrolled total
HAP emissions (tpy)
1
<1
<1
<1
2.8 LAMINATED VENEER LUMBER ;
i
2.8.1 LVL Process Description
t '
Laminated veneer lumber consists of layers of wood veneers laminated together with the
i
grain of each veneer aligned primarily along the length of the finished product. The veneers used
to manufacture LVL are about 0.125 inches thick and are made from rotary-peeled hardwood
(e.g., yellow poplar) or softwood species.1'29 Laminated veneer lumber is used for headers,
i ,
beams, rafters, and I-joist flanges. Figure 2-10 is a diagram of the LVL manufacturing process.
The start of the LVL manufacturing process depends on how the plant obtains veneers.
Plants either purchase pre-dried veneers, purchase green veneers and dry them onsite, or peel and
dry veneers onsite. Unless the plant purchases pre-dried veneers, the LVL manufacturing process
begins with veneer drying. Of the 15 LVL plants listed in the EPA's engineered wood products '
survey response data base, 10 purchase I veneers from offsite, three peel veneers on-site, and two
purchase a combination of green and dry veneers.29 Thus, five (one-third) of the LVL plants dry
veneer onsite in veneer dryers.
2-48
-------
Green
k
veneer *
LVL
product "*
'
Veneer
dryer ;
Trimming
and ;
sawing
h
^
Dry
veneer
1
Grading
Press
PFr
^
esin
r
Adhesive
application
^
r
Billet
layup
Figure 2-10. Laminated veneer lumber manufacturing process.
The veneer dryers used at LVL plants are the same types of dryers in use at plywood
plants.. Veneer dryers used at LVL plants are used to dry either 100 percent hardwood or
100 percent softwood species.29 The typical veneer drying temperature is around 350°F. The
veneer .dryer may be a longitudinal dryer, which circulates air parallel to the veneer, or a jet dryer.
Jet dryers direct hot, high velocity air at the surface of the veneers through jet tubes. Veneer
dryers may be either direct-fired or indirect-heated. The hardwood veneer dryers used at LVL
plants .are indirect-heated, while the softwood dryers are direct-fired by gas burners.29
Once the veneers are dried, they are graded ultrasonically for stiffness and strength. The
lower grade veneers are used for the LVL core and the higher grade veneers are used in the LVL
face. Once graded, the veneers are passed under a curtain or roll coater where PF resin is
applied. Plants that manufacture LVL from hardwood species may use UF resin rather than PF
resin.
29
Once resinated, the veneers are manually laid up into a long thick stack. The veneer stack
is fed to a hot press where the veneers are pressed into a solid billet under heat and pressure. In
the United States, LVL is manufactured tp either a fixed length using a batch press, or to an
indefinite length using a continuous press. The LVL presses are heated by electricity,
i
microwaves, hot oil, steam, or RF waves.; Press temperatures range from about 250° to 450°F,
averaging around 350°F. Batch presses may have one or more openings: A few plants produce
2-49
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I
short-length LVL using multi-opening platen presses similar to the hot presses used in plywood
manufacturing.29'30 However, most plants employ continuous pressing systems.
Billets exiting the press may be up to 3.5 inches thick, and may be made even thicker in a
secondary gluing operation. The moisture content of the billets exiting the press is about
10 percent.1 Billets are produced in widths of up to 6 feet.29 The billets are typically ripped into
numerous strips based on customer specifications. The LVL is produced in lengths up to the
maximum shipping length of 80 feet.1 Trademarks or grade stamps may be applied in ink to the
LVL before it is shipped from the plant. (
2.8.2 Emission Sources and Controls atjLVL Plants
The primary sources of HAP emissions at LVL plants include veneer dryers and presses.
j i i
Table 2-22 summarizes APCD used to control emissions from the veneer dryers at LVL
i ;
plants.27'31 There are 43 uncontrolled presses in use at LVL plants in the United States. In
addition to drying and pressing, glue application and application of trademarks or grade stamps
may also be a source of HAP emissions :at LVL plants.
TABLE 2-22. NUMBER OF VENEER DRYERS AND APCD AT
LVL PLANTS IN THE UNITED STATES
i
APCD type j
Incineration-based controls:
RTO
Uncontrolled
Softwood veneer
dryers3
4
4
Hardwood veneer
dryers3
,5b
5b
a Softwood veneer dryers dry 30 percent or more (on a volume basis) softwood
species. Hardwood veneer dryers dry less than 30 percent softwood species.
b Two of these dryers are shared for LVL and PSL production at the same plant.
2.8.3 Nationwide HAP Emissions froni LVL Plants
Nationwide baseline total HAP emissions from LVL plants are estimated to be 94 tpy.
i .
The average uncontrolled HAP emissions per LVL plant is 8 tpy. The average baseline HAP
emissions per plant is 7 tpy. Table 2-23 presents the average uncontrolled emissions per LVL
process unit. The average emissions per plant and per process unit were calculated as the
2-50
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average of the total emissions estimated for each plant and for each process unit using the
methodology documented in the baseline emissions memo.13
^ . *
TABLE 2-23. AVERAGE UNCONTROLLED TOTAL
HAP EMISSIONS FOR LVL PROCESS UNITS
Process unit ;
Softwood veneer dryef
Hardwood veneer dryer
Press
Average uncontrolled total
HAP emissions (tpy)
5
4
2
2.9.LAMINATED STRAND LUMBER!
2.9.1 LSL Process Description ;
Laminated strand lumber is a product manufactured by Trus-Joist MacMillan at two
facilities in the United States. Laminated strand lumber is made up of wood strands glued
together with the grain of each strand oriented parallel to the length of the finished product.
Yellow poplar, aspen, and other hardwood species are used in the manufacture of LSL.
Figure 2-11 is a diagram of the LSL manufacturing process. Whole logs are received at
the plant, debarked, cut to length, and conditioned in heated log vats. The conditioned logs are
cut into approximately 12-inch strands. The strands are screened to remove short strands and are
stored in green bins before they are dried! These short strands may be used as fuel for the
production process.1
The acceptable-sized strands are dried in either a conveyor or rotary drum dryer and
stored in a dry bin where they await further processing. One of the two LSL plants in the United
States operates four triple-tier conveyor cjryers. The other LSL plant operates two single-pass
rotary dryers. The LSL strands are dried to four to seven percent moisture (dry basis) in either
type of dryer. The rotary strand dryers are direct-fired by wood burners. The rotary dryer inlet
temperature is approximately 900°F. Th6 LSL conveyor dryers are indirect-heated, and operate
at 320° to 400°F.29 !'
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Logs
1
Log
pond
Screening
" and
classifying
i
f
Blending
i
r
Forming
Debarring
t
1 :
Dry
bins
[
|
Flaking/
stranding
Drying
h
Screening
and
classifying
[ i
f
Green
bins
* MDI resin
<- Wax
|
Pressing
Sanding
> Sawing
LSL product
Figure 2-11. Laminated strand lumber manufacturing process.
Following drying, strands from the dry bin are re-screened to remo've short strands and
are conveyed to blenders for resin and wax application. Methylene dipheriyl diisocyanate resin is
sprayed onto the strands as they tumble! in a rotating blender. :
From the blender, the resinated strands are discharged through forming heads which layup
a continuous mat of aligned strands. The mats are cut to lengths appropriate for pressing and are
i ,
conveyed into a single-opening, batch, jsteam-injection press. The press compacts the loose mat
of strands into a billet within 6 min at a temperature of 310°F. Billets may be up to 8 ft wide,
5.5 inches thick, and 48 ft long. The average press throughput for the two LSL plants is 5.2
million ft3/yr. Once the billets leave the press, they are sanded, cut to specific dimensions, and
packaged for shipment.29
i
Laminated strand lumber manufacturing is similar to OSB manufacturing in some
regards. The equipment and processes!for LSL and OSB manufacturing are similar, with the
exception of the press. Oriented strandboard is usually formed into panels used for sheathing in a
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multi-opening platen press, while LSL is made into a billet (which will be cut-to-size and used
for structural framing) in a steam-injection press. As with OSB, the raw material for LSL
production is whole debarked logs cut into strands. In the case of LSL, however, .the nearly
12-inch strands are significantly longer than the 3- to 6-inch strandsnised for OSB.1 The LSL
strands are about the same thickness (0.03 to 0.05 inches) as OSB strands. Laminated strand
lumber is manufactured from only hardwood species, while OSB is made from a mixture of
hardwoods and softwoods.6'29 The LSL strands are oriented parallel to the length of the finished
product (rather than in perpendicular layers as in OSB).
2.9.2 Emission Sources and Controls at LSL Plants
Sources of HAP emissions at LSL plants include strand dryers, blenders, the steam-
injection press, and application of edge seals. All of the LSL strand dryers (four conveyor dryers
and two rotary dryers) are vented through an EFB. Emissions from the blenders at the two LSL
plants are ducted through a baghouse. The two presses are enclosed and ducted through a stack.
The edge seal operationsi are fugitive emission sources.
2.9.3 Nationwide HAP Emissions from LSL Plants
Nationwide baseline total HAP emissions from LSL plants are estimated to be 64 tpy.
The average total uncontrolled and baseline HAP emissions per plant is 32 tpy. Table 2-24
presents the average uncontrolled emissions per LSL process unit. The average emissions per
plant and per process unit were calculated as the average of the total emissions estimated for each
plant and for each process unit using the methodology documented in the baseline emissions
memo.
13
TABLE 2-24. AVERAGE UNCONTROLLED TOTAL HAP EMISSIONS
FOR LSL PROCESS UNITS
Process unit
Rotary strand dyers ;
Conveyor strand dryers
Press
Average uncontrolled total
emissions (tpy)
HAP
27
2a
<1
a Emissions were estimated basedrotary dryer emission factors that were scaled down
using ratios of rotary dryer and conveyor dryer formaldehyde and total hydrocarbon.
See the baseline emissions memO for details.
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2.10 PARALLEL STRAND LUMBER
2.10.1 PSL Process Description
Like LSL, PSL is a product manufactured by Trus-Joist MacMillan at two facilities in the
United States. Figure 2-12 is a diagram of the PSL manufacturing process. Both hardwood (e.g.,
yellow poplar) and softwood (e.g., Douglas-fir, western hemlock, and southern pine) species may
be used to manufacture PSL. !
; PF resin
1
f^rnpn *-
veneer
PSL
. . -4
product
Veneer
dryer
. Sanding
. P
4 1
Trimming
and
sawing
b
Defect
removal
Press
^
Adhesive
application
i
r
Billet
assembly
Figure 2-12. Parallel strand lumber manufacturing process.
The manufacturing process begins with rotary-peeling logs into veneer about 0'.125 inches
thick.1 The green veneer is clipped into sheets, sorted, and dried in a veneer dryer. The two PSL
plants in the United States each have two indirect-heated veneer dryers. One of the plaints uses
the same veneer dryers for both LVL and PSL production. The veneers are typically dried at
around 400°F.29 !
The dried veneer is clipped into strands approximately 0.75 inches wide. One advantage.
[ !
of PSL is that pieces and scraps of venber smaller than full size sheets may be used for its
production. The veneer strands are coated with PF resin, aligned, and fed into a continuous
press. The press uses microwaves to cure the PF resin.1 A variety of billet dimensions may be
I !
produced in the continuous press. Following pressing, the billets are processed into smaller
members according to customer specifications and packaged for shipment.
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2.10.2 Emission Sources and Controls at PSL Plants
i
The HAP emission sources at PSL plants include veneer dryers and presses. There are
two uncontrolled softwood veneer dryers in operation at PSL plants. (Note that there are two
additional uncontrolled hardwood veneer dryers that are shared between LVL and PSL
production lines at one plant. These hardwood veneer dryers were included in Table 2-22.)27*31
There are two uncontrolled presses in use at PSL plants. In addition to drying and pressing, glue
application and application of trademarks or grade stamps may also be a source of HAP
emissions at PSL plants. :
2.10.3 Nationwide HAP Emissions from PSL Plants
Nationwide baseline total HAP emissions from PSL plants are estimated to be 30 tpy.
The average total .uncontrolled and baseline HAP emissions per plant is 15 tpy. Table 2-25
presents the average uncontrolled emissions per PSL process unit. The average emissions per
plant and per process unit were calculated as the average 'of the total emissions estimated for each
plant and for each process unit using the methodology documented in the baseline emissions
memo.
13
TABLE 2-25. AVERAGE UNCONTROLLED TOTAL HAP
EMISSIONS FOR PSL PROCESS UNITS
Process unit
Softwood veneer dyers1
Press . ;
Average uncontrolled total HAP
emissions (tpy)
7
. 5
2.11 I-JOISTS ;
! -
2.11.1 I-Joist Process Description !
~ * I
Wood I-joists are a family of engineered wood products consisting of a web made from a
structural panel such as plywood or OSB which is glued between two flanges made from sawn
lumber or LVL. Figure 2-13 shows the web and flange of a typical I-joist made with OSB and
LVL.32 I-joists are available in many sizes and depths. They are used in residential and
commercial buildings as floor joists, roof joists, headers, and for other structural applications.
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Flanges
Web
Figure 2-13. View of an I-joist made from an OSB web and LVL flanges.
The processes for manufacturing wood I-joists vary throughout the industry. There are
high-volume automated production lines that operate continuously and produce more than
350 linear feet per minute (If/min).1 There are also custom hand lay-up processes that are used
for heavier commercial grade I-joists. Regardless of the process, the general steps used to
fabricate I-joists are the same and include: flange preparation, web preparation, I-joist assembly,
I-joist curing, cutting, and packaging for shipment. Figures 2-14a and 2-14b show a typical
automated I-joist fabrication process, j
In the automated fabrication process, web preparation includes ripping of the web into
sections of desired length and machining (tapering) the edges of the web.. Knockouts (thin
i
circular areas in the web that may be "knocked out" during construction for installation of
electrical wiring) may be machined into the web prior to or after I-joist assembly.
Flanges are prepared by ripping of sawn lumber, LVL, or other engineered wood material
to the desired width. If required, the flanges may be finger-jointed end-to-end. During the
f «" ;
finger-jointing process, grooves are cu,t into the end of each flange, a phenol-resorcinol-
2-56
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Web
material ^
Ripping and
machining of
edges and
knockouts
.:*'
>
r
,
; Assembly of { . fe
Ganges and web ^. Hoist
j to form l-joist " "*" " 'a " product
" 1 (see Figure _)
Flange ^
material
Ripping and
machining of
edges
i -i
\
\.
Figure 2-14a. I-joist manufacturing process.
Flange-to-web joint
Figure 2-14b. Basic I-joist assembly.
2-57
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formaldehyde (PRF) finger-jointing resiii is applied in the grooves, the flanges are fitted together
end-to-end, and the finger-jointing resin is cured. Finger-jointing resins are typically cured in an
RF tunnel. The result is a continuous flange which can be cut to the desired length before or
after I-joist assembly. Before the flanges enter the I-joist assembly machine, a profiled groove is
routed into one face of the flange along its length.
Immediately prior to entering the'I-joist assembler, PRF or MDI adhesive is applied in the
I I I
flange groove for formation of the flange-to-web joints.29 The adhesive is also applied to the
short edges of the web material for formation of the web-to-web joints. Shortly after resin
application, the webs are mechanically fitted into the resinated grooves between two flanges in
the assembler. The assembler presses the flanges and webs together into an I-joist.
After exiting the assembler, the I-joists are cut to length and passed through an oven or
curing chamber to cure the adhesive. Resin curing chambers may be rooms surrounded by a
solid wall or heavy plastic flaps. Curing rooms are typically heated to aroujid 120° to 225°F by a
gas-fired heater. However, some I-joist curing ovens operate near room temperature by
employing infrared or RF curing techniques.29 Once cured, the finished I-joists are inspected and
bundled for shipment.
2.11.2 Emission Sources and Controls at I-Joist Plants
i
Sources of HAP emissions at I-joist plants include resin application, I-joist assembly, and
I-joist curing. Additional sources of H/P emissions may include application of grade stamps or
trademarks. Most of the operations at I-joist plants are fugitive sources of HAP emissions. No
add-on APCD are used on sources of HAP emissions at I-joist plants. If not vented inside the
building, emissions from I-joist curing ovens may be vented through exhaust fans, roof vents, or
hoods. There are 17 uncontrolled I-joist curing ovens in use at I-joist plants in the United States.
2.11.3 Nationwide HAP Emissions froin I-Joist Plants
i
Nationwide baseline total HAP emissions from I-joist plants are estimated to be 8 tpy.
The average total uncontrolled and baseline.HAP emissions per plant is <1 tpy. Because the
average emissions per plant are <1 tpy, it follows that the average emissions per I-joisjt process
unit (e.g., curing oven, RF fingerjoint curing tunnel, and cutting operation) are <1 tpy.1-'1
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2.12 GLUE-LAMINATED BEAMS j
2.12.1 Glulam Process Description j
I
Glue-laminated beams are manufactured by gluing lumber together to form larger
structural members for applications such !as ridge beams, garage door headers, floor beams, and
arches. The glulam manufacturing process consists of four phases: (1) drying and grading the
lumber; (2) end-jointing the lumber into longer laminations; (3) face gluing the laminations; and
(4) finishing and fabrication. !
Lumber used to manufacture glulam may be dried onsite at the glulam plant or purchased
pre-dried from suppliers. Nearly half of the glulam plants responding to the EPA's engineered
i
wood products survey dry lumber in onsijte lumber kilns. The remaining plants purchase dry
lumber. The moisture content of the lumber entering the glulam manufacturing process can be
determined by sampling from the lumber supply with a hand-held moisture meter or with a
continuous in-line meter that checks the moisture of each board. Those boards with a moisture
content-greater than a given threshold are removed from the process and re-dried. Re-drying may
be accomplished through air drying or kiln drying. Once the lumber is checked for moisture,
knots appearing on the ends of the lumber may be trimmed off and the lumber is graded. The
I
lumber is sorted into stacks based on the grade it receives.33
To manufacture glulam in lengths beyond those commonly available for sawri lumber, the
lumber must be end-jointed. The most common end joint is a finger joint about 1.1 inches long.
The finger joints are machined on both ends of the lumber with special cutter heads. A structural
adhesive, such as an RF-curing MF or PF adhesive, is applied and the joints in successive boards
are mated. The adhesive is cured with thje joint under end pressure. Most manufacturers use a
continuous RF-curing system to cure end, joints.29
Just before the face gluing procesjs, the end-jointed lumber is planed on both sides to
ensure clean, parallel surfaces for gluing.; The adhesive is spread onto the lumber with a glue
extruder. Phenol-resorcinol-formaldehyde is the most commonly used adhesive for face gluing.
Other adhesives used for face gluing include PF resin or MUF resin.29
The resinated lumber is assembled into a specified lay-up pattern. Straight beams are
i . . '
clamped in a clamping bed where a mechanical or hydraulic system brings the lumber into close
contact. Curved beams are clamped in a;curved form. With the batch-type clamping process,
j , - ,
: 2-59
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glulam beams are allowed to cure at room temperature for 5 to 16 hours before the pressure is
released.29 Some of the newer clamping systems combine continuous hydraulic presses and RF
curing to accelerate the face gluing process.
After the glulam beams are removed from the clamping system, the wide faces (sides) are
planed or sanded to remove beads of adhesive that have squeezed out between the boards. The
narrow faces (top and bottom) of the beam may be lightly planed or sanded depending on
appearance requirements. Edges (comers) are often eased (rounded) as well. The specified
appearance of the member dictates whether additional finishing is required at this point in the
manufacturing process. Knot holes may be filled with putty patches and the beams may be
further sanded. End sealers, surface sealers, finishes, or primer coats may also be applied.33
2.12.2 Emission Sources and Controls at Glulam Plants
Sources of HAP emissions at glulam plants include lumber drying, RF curing of finger
joints, glue application, and pressing. <31ue application, RF curing of finger joints, and pressing
are fugitive emission sources. Lumber kilns are not fugitive emissions sources. However,
lumber kilns have several emission points. Lumber kilns are discussed in Section 2.14 below.
There are 22 glulam presses in use at 0.S. glulam plants. No add-on controls are used on sources
of HAP emissions at glulam plants.
2.12.3 Nationwide HAP Emissions from Glulam Plants
Nationwide baseline total HAP emissions from glulam plants are estimated to be 84 tpy.
The average total uncontrolled and baseline HAP emissions per plant is 5 tpy. The average total
HAP emissions per glulam press is 4 tpy, based on the resin mass balance calculations described
in the baseline emissions memo.13 Average total HAP emissions for lumber kilns are
summarized in Section 2.14.3.
2.13 MISCELLANEOUS ENGINEERED WOOD PRODUCTS
In addition to the engineered wood products discussed in Sections 2.8 to 2.12 above,
I
other miscellaneous engineered wood products are manufactured by individual plants in the
United States. These miscellaneous products are manufactured through operations similar to
other engineered wood products.
2-60
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2.13.1 Miscellaneous Engineered Wood Products Process Description
One engineered wood product called "comply" is a composite of a panel (e.g., OSB or
particleboard) core overlaid with veneer on its edges or faces. Comply is manufactured as a
sheathing panel with veneer faces.1-34 Coiinply panels are made in a three- or five-layer
arrangement. A three-layer panel has a wood core and a veneer face and back. A five-layer
panel also has a veneer crossband in the center. When manufactured in a one-step pressing
operation, voids in the veneers are filled automatically by the particles or strands as the panels are
pressed.35 '
One I-joist plant manufactures custom I-joist flanges by gluing several 0.75-inch strips of
wood together. Pre-dried lumber is purchased and ripped, and scarf joints are cut into the lumber
strips. Phenol-resorcinol-formaldehyde npsin is applied to the wood strips, and the custom
flanges are pressed at room temperature overnight.36
Another facility manufactures billets similar to LVL billets for onsite use in I-joist flanges
and a product called "glue-laminated veneer beams." The glue-laminated veneer beam billets are
manufactured from parallel laminated veneer (PLV) panels of varying thicknesses (5 to 11 ply)
obtained from outside facilities. The PLAf panels are similar to plywood panels except that the
grains of the veneers in the panels are aligned parallel to.one another. To manufacture billets, the
PLV panels are conditioned to achieve a panel temperature of 100° to 110°F. The ends of the
PLV panels are fingerjointed and PRF resin is applied to the jointed edges. The end joints are
mechanically forced together and are hot pressed. Following pressing the panels are cut to length
and moved to billet layup where MDI resin is applied to the panel faces. The panels are stacked
into billets of varying thicknesses and pressed in a room temperature batch press. Glue-
laminated veneer beams are made by ripping the pressed billets to customer specifications.
I-joist flanges are made from the billets as they would be prepared from LVL billets.37
2.13.2 Emission Sources at Miscellaneous Engineered Wood Plants
Sources of HAP emissions at the comply plant include particle drying and panel
pressing.34 Emission sources related to custom flange preparation include glue application and
pressing, both of which are fugitive HAP jsources. Finger joint hot pressing and billet pressing
are fugitive HAP emission sources related to production of billets for glue-laminated veneer and
I-joist flange manufacturing. I '
2-61
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2.13.3 Nationwide HAP Emissions from Miscellaneous Engineered Wood Plants
Nationwide uncontrolled and baseline total HAP emissions from miscellaneous
engineered wood products plants are estimated to be 18 tpy. The total baseline HAP emissions
per plant range from less than 1 tpy to 13 tpy depending on the miscellaneous engineered wood
product manufactured. The baseline emission estimates were developed using the methodology
1 13
described in the baseline emissions memo.
2.14 KILN-DRIED LUMBER j
Several PCWP plants are co-located with sawmills. Sawmills can process peeler cores
from plywood plants into lumber. Lumber is also produced from logs at some glulam plants for
use in glulam production. Lumber may be sold green, or it may be air dried or dried in a lumber
kiln. This section discusses drying of lumber in lumber kilns. Lumber kilns are emission
sources that contribute to the facility-wide HAP emissions when co-located at PCWP plants.
2.14.1 Co-Located Lumber'Kilns i
i :
Green lumber is sawed from debarked logs or from plywood peeler; cores. Freshly sawn
lumber has a high moisture content that must be reduced for many lumber end uses. Prior to kiln
drying, green lumber is stacked with stickers (thin strips of wood) in between each layer of the
stack. The stickers allow space between the layers of lumber for air flow. The lumber stacks are
loaded into the kiln, the kiln runs through the drying cycle, and the dried lumber is removed from
I '
the kiln when the drying cycle is complete. After completion of the lumber drying cycle;, the
dried lumber is removed from the kiln, unstacked (i.e., the stickers are removed), and stored for
shipment.
Lumber kilns are batch units. Softwood lumber kiln drying cycles typically last around
24 hours, while hardwood kiln drying cycles can last from several days to weeks. Lumber kilns
may be direct-fired or indirect-heated (e.g., steam-heated). Lumber kiln operating temperatures
vary during the drying cycle as the humidity in the lumber kiln and lumber moisture content
change. Lumber drying temperatures rainge from around 95° to 260°F and increase as the lumber
becomes increasingly dry.38 The lumber is dried slowly while at a higher moisture content and
more severely as the moisture content decreases in order to maintain an adequate drying rate.
Green southern yellow pine is dried from about 40 to 100 percent moisture (dry basis) down to
below 20 percent moisture (dry basis).38 The amount and direction of air that is vented from the
2-62
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kiln changes with the relative humidity, dry bulb temperature, and wet bulb temperature inside
the kiln. Lumber kilns have multiple venls, which alternate in function. During any given time,
one set of vents allows moisture to exhaust from the kiln while the other set of vents brings in
: I : . .
dry air. After some time, the direction of air circulation within the kiln is changed, and the kiln
vents exchange functions. Because of theise changes in air flow patterns, lumber kiln emission
streams vary in flow rate, concentration, and mass emission rate throughout the kiln drying cycle.
In addition to emissions from lumber kiln:vents, considerable amounts of fugitive emissions may
be emitted from lumber kilns through crevices in the kiln wall and around doors.
2.14.2 Emission Sources and Controls for Lumber Kilns
Lumber kilns are emission sources. There are a total of 356 uncontrolled lumber kilns
co-located at plants in the PCWP industry! Of the 356 kilns, roughly two-thirds are co-located at
softwood or hardwood plywood and veneer plants while the remaining kilns are co-located at
glulam, OSB, conventional or molded particleboard, and hardboard plants.6>.26>29
2.14.3 Nationwide HAP Emissions from Co-Located Lumber Kilns
!
The nationwide baseline total HAP emissions from co-located lumber kilns are included
with the nationwide totals presented in the sections on nationwide emissions above for each
product. The average total HAP emissions per lumber kiln is 1 tpy, based on the emission
estimation methodology documented in the baseline emissions memo.13
2.15 REFERENCES FOR CHAPTER 2 i
1. Smulski, S., et al., Engineered Wood Products - A Guide for Specifiers, Designers, and
Users. Madison, WI, PFS Research Foundation. 1997.
2. Memorandum from M. Icenhour, MRI, to Project file. February 28, 2000. Growth
projections for the Plywood and Composite Wood Products Industry - Plywood and
Composite Wood Products Manufacturing NESHAP.
3. Maloney, T.M. Modern Particleboard and Dry-Process Fiberboard Manufacturing. San
Francisco, Miller Freeman, Inc. 1993. pp. 26, 49, 64, 105-107, 284-285, 294, and 573. '
4. Emission Factor Documentation for AP-42 Section 10.6.2, Particleboard Manufacturing.
Prepared for the U. S. Environmental Protection Agency, OAQPS/EFIG, by Midwest
Research Institute. Gary, NC. September 1998.
2-63
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5. Memorandum from R. Nicholson and K. Hanks, MRI, to P. Lassiter, EPA/ESD.
October 28, 1998. Trip report for visit to Roseburg Forest Products plant in Dillard,
Oregon. !
6. Memorandum from D. Bullock, K. Hanks, and B. Nicholson, MRI to:M. Kissell,
EPA/ESD. April 28, 2000. Summary of Responses to the 1998 EPA Information
Collection Request (MACT Survey) - General Survey.
i
7. Douglass, Todd. Prairie Forest Products Appears To Have Turned the Wheat Straw
Corner. Panel World. November 1998.
8. Memorandum from J. Bradfield, Composite Panel Association, to R. Nicholson and K.
Hanks, MRI. March 21, 2000. New Plant Update.
9. Louisiana Department of Environmental Quality. Small Source Permit for Acadia Board
Company, Inc., New Iberia, LA facility. Undated:
10. Application for a Registration Permit Option D. Prepared for Phenix Biocomposites,
Mankato, MN facility, by Braun Intertec Corporation. Project Number CMXX-96-0840.
November 14,1996.
11. Memorandum from K. Hanks, MRI, to Project File 4803-48: Plywood and Composite
Wood Products NESHAP. August 24, 2000. Identifying Green and Dry Rotary Dryers
Used in The Plywood and Composite Wood Products Industry.
12. Memorandum from K. Hanks, MRI, to CBI Project File. September 21, 2000. Presses and
board coolers with permanent total enclosures.
13. Memorandum from K. Hanks and D. Bullock, MRI, to M. Kissell, EPA/ESD. June 9,
2000. Baseline Emission Estimates for the Plywood and Composite Wood Products
Industry. '
14. North Dakota State Department of Health and Consolidated Laboratories, Environmental
Health Section. Air Pollution Control Permit to Construct. Prime Board, Inc., Wahpethon,
ND. Undated.
15. Emission Factor Documentation for AP-42 Section 10.6.1, Waferboard/Oriented
Strandboard Manufacturing. Prepared for the U. S. Environmental Protection Agency,
OAQPS/EFIG, by Midwest Research Institute. Gary, NC. December 1998.
16. Emission Factor Documentation for AP-42 Section 10.6.3, Medium Density FiBerboard
Manufacturing. Prepared for the;U. S. Environmental Protection Agency, OAQPS/EFIG,
by Midwest Research Institute. Gary, NC. September 1998.
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17. Letter from T. Peters, MacMillan Bloedel (Temple-Inland Forest Products Corporation), to
P. Lassiter, EPA/ESD. Response to information request for Clarion, PA facility.
18. Memorandum from K. Hanks, MRl, to Project File 4803-48: Plywood and Composite
Wood Products NESHAP. Augus^ 24, 2000. Identifying Primary And Secondary Tube
Dryers Used in The Plywood and Composite Wood Products Industry.
19. Memorandum from B..Nicholson, and K. Hanks, MRI, to P. Lassiter, EPA/ESD. May 27,
1998. Site Visit - Medite Division^ of Sierra Pine Medium Density Fiberboard Plant in
Medford, Oregon.
20. Memorandum from K. Hanks, MRI, to CBI Project File. September 25, 2000. Digesters
and Refiners at Plywood and Composite Wood Products Plants.
21. Suchsland, O., and G.E. Woodson. Fiberboard Manufacturing Practices in the United
States. Forest Products Research Society. 1990. pp. 24-25, 72-80, 131, 151,168, and 176.
22. Memorandum from R. Nicholson, MRI, to M. Kissell, EPA/ESD. February 24,1998. Site
Visit - ABTco, Inc., Roaring Rivef;, NC.
I
23. Memorandum froni D. Bullock and K. Hanks, MRI, to P. Lassiter, EPA/ESD. October 29,
1997. Sits Visit - Temple-Inland Forest Products Corporation, Diboll, TX Complex.
24. Emission Factor Documentation fo;r AP-42 Section 10.5, Plywood Manufacturing.
Prepared for the U. S. Environmental Protection Agency, OAQPS/EFIG, by Midwest
Research Institute. Gary, NC. September 1997.
25. Memorandum from K. Hanks and D. Bullock, to P. Lassiter, EPA/ESD. December 1,
1997. Site Visit - Champion International Corporation Camden Plywood and Stud
Operations, Camden, TX.
26. Memorandum from K." Hanks, B. Threat!, and B. Nicholson, MRI to M. Kissell, EPA/ESD.
May 19, 1999. Summary of Responses to the 1998 EPA Information Collection Request
(MACT Survey) - Hardwood Plywood and Veneer.
27. Memorandum from K. Hanks, MRl, to CBI Project File. September 21, 2000. Distinctions
between hardwood and softwood veneer dryers, veneer kilns, and radio-frequency (RF)
veneer dryers. ;
28. Baldwin, R.F. Plywood and Veneer Based Products - Manufacturing Processes. San
Francisco, Miller Freeman, Inc. 1995. pp. 258-259.
29. Memorandum from K. Hanks and B. Threatt, MRI, to M. Kissell, EPA/ESD. January 20,
2000. Summary of Responses to the 1998 EPA Information Collection Request (MACT
Survey) - Engineered Wood Products.
! 2-65
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30. Bowering, C., Raute Wood Ltd. Processing Options for Laminated Veneer Lumber.
Presented at The Sixth International Panel and Engineered Wood Technology Conference
and Exposition (PETE), Georgia International Convention Center. Atlanta, GA.
October 19-22,1998.
31. Memorandum from K. Hanks, MRI, to Project Files. April 18,2000. Changes in the
population of existing plywood and composite wood products plants and equipment
following the information collection request.
32. Memorandum from K. Hanks and B. Nicholson, MRI, to P. Lassiter, EPA/ESD. March 17,
1998. Site Visit - Willamette Industries, Incorporated I-joist Plant in Woodburn, OR.
33. Memorandum from K. Hanks and D. Bullock, MRI, to P. Lassiter, EPA/ESD. December 1,
1997. Site Visit - Willamette Industries, Simsboro Laminated Beam Plant, Simsboro, LA.
34. Oregon Department of Environmental Quality. Air Contaminant Discharge Permit
Application Review Report. Permit Number 22-1037, Application Number 14726.
April 26,1995. j
i
35. APA - The Engineered Wood Association, "http://209.20.164.209/products/osb.html,"
July 12,1999. ;
36. C. Wozney, Starwood Rafters, Incorporated, to P. Lassiter, EPA/ESD. Response to
information request for Independence, WI facility. :
37. R. Strader, Boise Cascade Corporation, to P. Lassiter, EPA/ESD. Response to information
request for White City LVL facility in White City, OR.
38. Thompson, A.L. Volatile Organic Compounds Emitted During The Drying of Southern
Pine Lumber. A Thesis Submitted to the faculty of Mississippi State University in Partial
Fulfillment of the Requirements for the Degree of Master of Science'in Forest Products in
the Department of Forest Products. Mississippi State University. December 1996.
2-66
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3.0 EMISSION CONTROL TECHNIQUES
This chapter discusses emission control techniques for reducing HAP emissions from
process units, primarily dryers and presses, at PCWP facilities. Emission control techniques
include add-on APCD, emission capture systems, and other control techniques (e.g., process
modifications). This chapter summarizes the performance of HAP control techniques and
discusses the operating parameters that can be monitored to assure proper operation of these
control systems. !
Add-on control devices traditionally have been applied to process units at PCWP
facilities to reduce paiticulate matter (PM) emissions. Examples of APCD used to control PM
emissions from PCWP facilities include'multi-cyclones (multiclones), baghouses, electrified
filter beds (EFB), wet scrubbers, and WESP. Available control device performance data for
multi-cyclones, baghouses (or fabric filters), and EFB show that these control devices have no
effect on gaseous HAP or VOCa emissions. The performance data for WESP and wet scrubbers
installed for PM control also showed no effect on HAP and VOC emissions. These wet systems
may achieve short-term reductions in VOC or gaseous HAP emissions, however, the HAP and
VOC control efficiency data,, which range from slightly positive to negative values, indicate that
the ability of these wet systems to absorb water-soluble compounds (such as formaldehyde)
diminishes as the recirculating scrubbing liquid becomes saturated with these compounds.1
Beginning in the 1990s, incineration-based controls and biofilters also were installed at some
PCWP facilities to reduce VOC emissions, primarily from dryers and presses. These VOC
controls are also effective in reducing gaseous HAP emissions.
aVolatile organic compound (VOC) emissions are often based on total hydrocarbon
(THC) measurements. This chapter refers to VOC in discussions of control system design and
operation. However, performance data specific to PCWP control systems are presented in terms
of THC. The factors that affect control system performance for VOC are the same for THC.
3-1
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This chapter focuses on those control systems that reduce gaseous HAP emissions.
Incineration-based controls are discussed in Section 3.1 and biofiltration is discussed in
Section 3.2. Capture devices designed to capture and deliver gaseous HAP emissions from
PCWP process units to an APCD are discussed in Section 3.3. Although WESP do not
consistently and reliably reduce gaseous HAP emissions, a discussion of WESP is included in
Section 3.4 because WESP are often used in conjunction with RTO to protect the media from
particulates that would otherwise enter the RTO. Additional control techniques are discussed in
Section 3.5. Section 3.6 contains the references cited in this chapter.
3.1 INCINERATION-BASED CONTROLS ;
Incineration is a highly effective;method for destroying hydrocarbon and other organic
vapors, gaseous pollutants, and combustible paniculate. Incineration-based controls oxidize
organic vapors in the process exhaust stream to carbon dioxide (CO2) and water (H2O) through
combustion reactions. Incineration-based controls used in the PCWP industry include add-on
controls such as thermal oxidizers, regenerative catalytic oxidizers (RCO), and thermal catalytic
oxidizers (TCO). In addition to add-on jincineration-based controls, some PCWP facilities
perform "process incineration." Procesk incineration involves routing 100 percent of the
emissions from a process unit to an onsite combustion unit such as a boiler or process heater
(e.g., dryer burner). Section 3.1.1 discusses thermal oxidization (i.e., thermal oxidizers, process
incineration, and RTO) and Section 3.1;.2 discusses catalytic oxidation (i.e., RCO and TCO).
The performance of incineration-based controls is discussed in Section 3.1.3. Parameters
monitored during operation of incineration-based controls are discussed in Section 3.1.4.
i ' :
3.1.1 Thermal Oxidization
The vast majority of incineration-based systems used in the PCWP industry are thermal
oxidization systems and nearly all of these systems have waste heat recovery to reduce operating
costs related to fuel consumption. Thermal oxidation systems include thermal oxidizers (which
do not have heat recovery) and recuperative or regenerative thermal oxidizers. Recuperative
thermal oxidizers incorporate a heat exchanger at the combustion chamber outlet to recover up to
I ;
70 percent of the heat energy in the combustion chamber exhaust. Regenerative thermal
oxidizers incorporate ceramic beds at the inlet and outlet of the combustion chamber for up to
95 percent energy recover,'.2 Based on available information, either no heat recovery or only the
3-2
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regenerative heat recovery systems are m<>st commonly used with thermal oxidizers at PCWP
facilities.3 Therefore, this section focuses on describing operation of thermal oxidizers and RTO.
Recuperative thermal oxidizers are nt>t dijscussed.
3.1.1.1 Thermal Oxidizers. Thermal oxidizers are one of the best known methods for
I
industrial waste gas disposal in which the combustible compounds in the waste gas stream are
completely destroyed rather than collected. Thermal oxidizers are refractory-lined combustion
chambers containing a burner (or set of burners). Figure 3-1 is a schematic of a thermal oxidizer.
The burner provides the heat necessary for combustion. Natural gas or propane are typically used
I
as burner auxiliary fuels. The heat from the burner ignites and begins to oxidize the gaseous
HAP and/or VOC pollutants in the exhaust once they enter the mixing chamber. Oxidation of
the pollutants to combustion products (i.el, CO2 and H2O) is completed in the reaction chamber.
i
Heat from combustion of the pollutants iri the exhaust gas serves to reduce auxiliary fuel usage.
...... , .-. i -.,..-.
An efficient thermal oxidizer provides: (li) a combustion chamber temperature high enough to
completely oxidize the gaseous HAP or VOC; (2) sufficient residence time in the combustion
chamber to allow for complete oxidation jjf gaseous HAP or VOC; and (3) sufficient mixing of
combustion products, air, and the process'vent streams.4
Polluted
exhaust
(Burner
Burner fuel
\
Burner air-
\
Exhaust
gases
Fl^me mixing
crjamber
Reaction chamber
Figure 3-1. Schematic of a thermal oxidizer.
by the
Combustion is greatly affected
theoretical temperature required for therm
involved. Some chemicals can be oxidized
operating temperature of the incinerator. The
al oxidation depends on the structure of the chemical
at a temperature much lower than others. However, a
3-3
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temperature can be identified that will result in the efficient destruction of most exhaust gas
streams containing gaseous HAP or VOC. To be efficiently incinerated, exhaust gas streams
must be heated to their ignition temperature. If the ignition temperature is not met, then
incomplete combustion will occur. Therefore, most thermal oxidizers operate above exhaust gas
ignition temperatures. Thermal destruction of most compounds occurs between 1,110° land
1,200°F, while most incinerators operate between 1,300° and 1,500°F.
Thermal oxidizer residence time is the time from when the exhaust gas stream reaches the
combustion temperature until the exhaust gas stream leaves the combustion chamber. Therefore,
the residence time is determined by the size of the combustion chamber and the flow rate of the
exhaust gas stream through the chamber.5 The incinerator operating temperature directly affects
the residence time, and vice versa. If the operating temperature is increased, then the gaseous
pollutants can be oxidized more rapidly, therefore, reducing the necessary residence time. Also,
if the operating temperature is decreased, then the gaseous pollutants will be oxidized in a longer
period of time, requiring a longer residence time.5
Turbulence is necessary to achieve the proper amount of mixing, which is important for
two reasons. First, every gaseous pollutant molecule must come into contact with an oxygen (O2)
molecule to ensure complete combustion. If gaseous pollutant molecules do not contact O2
molecules, then the gaseous pollutants may be exhausted from the combustion unit before being
oxidized. Secondly, the entire exhaust ;gas stream must be mixed with the heat source in order to
reach the necessary operating temperature.5
Relatively few thermal oxidizers without heat recovery are used in the PCWP industry.
' Nevertheless, the principles of thermal oxidation described above apply to all types of thermal
oxidization systems (including process; incineration systems and RTO) used at PCWP facilities.
3.1.1.2 Process Incineration. In addition to add-on thermal oxidizers, exhaust gases from
PCWP process units may be-routed to the combustion chamber of an onsite boiler or process
heater. The boiler or process heater operates much like a thermal oxidizer. The organic
emissions in the process exhaust are incinerated in the combustion chamber. Hence, this control
technique is referred to as "process incineration." As for a thermal oxidizer, the process
incineration system must be designed to allow for proper mixing of the pollutants with O2, have a
temperature high enough to ignite the pollutants, and provide adequate residence time.
3-4
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Some OSB facilities use a heat/energy system for process incineration. This technology
uses an oversized combustion unit that accommodates recirculation of 100 percent of the
volumetric flow of dryer exhaust gases. The recirculated dryer exhaust is mixed with
combustion air and exposed directly to the burner flame. The gaseous HAP/VOC emissions are
incinerated at the high temperatures inside the combustion unit. A urea solution may be injected
near the outlet of the combustion chamber to help lower NOX emissions (i.e., by chemically
reducing a portion of the NOX to nitrogen ;[N2]). High temperature exhaust from the combustion
unit passes through a heat exchanger, which provides heat for dryer inlet air, and then through an
add-on device for PM emission control. Plants that use exhaust gas recycle to control dryer
emissions are generally designed from the ground up (i.e., exhaust gas recycle systems cannot be
easily retrofitted).6
3.1.1.3 Regenerative Thermal Oxidizers. The type of thermal oxidization system most
commonly used in the PCWP industry is the RTO. Regenerative heat recovery systems use
direct contact with a heat-tolerant ceramic material. The inlet gas first passes through a hot bed
f .
or "canister" of ceramic media which heats the gas stream to or above its ignition temperature
typically, 1,400° to 1,800°F. If the desired temperature is not attainable, then a small amount of
auxiliary fuel is added in the combustion chamber. The hot gases react (i.e., oxidize to CO2 and
H2O) in the combustion chamber, and then pass through a second canister of ceramic media,
heating the media to the combustion chamber outlet temperature. Thus, while one canister
absorbs heat from the hot (cleaned) gas stream, another canister transfers its stored heat to the
incoming (polluted) gas stream. When the heat absorbing canister reaches its heat storage
capacity, and the other canister becomes heat depleted, a series of valves redirects the gas flow so
the roles of the two canisters reverse.7 This cyclic process allows exhaust gas streams to be
nearly self-sustaining.2 Figure 3-2 shows |this regenerative heat recovery process.
The RTO used in the PCWP industry incorporate two to eight canisters.3 The number of
heat recovery canisters is dictated by the flow rate to be controlled. Some RTO with odd
numbers of canisters incorporate a purge canister to ensure that untreated exhaust in the plenum
beneath the RTO is not exhausted to the atmosphere (resulting in reduced control efficiency) as
the flow is reversed from canister to canister. For example, in a five-canister system, at any
3-5
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Burner
Combustion
chamber
Ceramic
packing
Process
exhaust
Figure 3-2. Regenerative heat recovery process.
given point in system operation, two canisters will be functioning as inlet beds and two are
functioning as outlet beds, while the remaining regenerator bed is being purged.8
The ceramic bedding'of an RTO: typically consists of either structured packing in the form
of a honeycomb ceramic monolith or random packing consisting of 1 inch porcelain "saddles."
Porcelain saddles are much cheaper to manufacture and therefore cost less than the structured
packing. However, structured packing has advantages including lower pressure drop and laminar
flow characteristics.9 |
The preheat temperatures achieved in the inlet canister are generally higher than the
ignition temperatures for most gaseous HAP or VOC. Thus, some oxidation of pollutants will
begin to occur in the ceramic packed beds before the preheated gases are discharged from the
inlet bed to the combustion chamber. A burner system fires into the combustion chamber
between the ceramic beds to automatically maintain a preset oxidation temperature.8 Most RTO
3-6
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are operated with combustion chamber temperatures of around 1,500°F.3 The combustion
chamber is sized for a pre-determined retention time with the oxidizer operating at normal design
temperature and handling the maximum flow rate of process exhausts. The canister and
combustion chamber designs are such that relatively high linear velocities of the oxidizing gases
are typical. These velocities and the vertical gas flow patterns in the combustion chamber are
sufficient to provide satisfactory gas phase mixing (turbulence).8
Natural gas injection (NGI) is a technique used with RTO to boost the hydrocarbon
concentration in the incoming air stream ;to a level necessary for self-sustaining combustion.
Typically, a natural gas burner system is Used to make up the heat energy that is not recovered by
the RTO. If the incoming air stream is highly concentrated, the hydrocarbons will ignite and the
process will become self-sustaining (i.e.,require no auxiliary fuel usage). However, emission
streams at PCWP plants typically are high volume, low concentration streams. Natural gas
injection is performed when the heat exchange media is saturated and hot enough to bring the gas
stream above ignition levels. At that point, the burner and combustion blower are turned off, and
natural gas or methane is injected into th6 incoming gas stream, enriching it to the concentration
level necessary for self-sustaining combustion. The NGI reportedly improves the RTO thermal
efficiency by 1 percent or more, overall.7;
As mentioned above, the exhaust'streams from PCWP process units are relatively dilute
(i.e., contain air which is comprised primarily of N2 and O2). Thermal NOX is formed when N2 is
I -
exposed to high temperatures in the presence of O2. In addition, fuel NOX is formed when N, in
the fuel is oxidized to NOX. .As temperatjure increases, the kinetics of NOX formation accelerate,
and more NOX is formed. Thus, NOX formation must be considered in the design of incineration
systems. Low NOX burners and NGI canlbe used to reduce formation of NOX in combustion
units such as RTO. Low NOX burners inhibit NOX formation by controlling the mixing of fuel
and air.4 Use of NGI results in a decrease in NOX emissions because it reduces the need for
burner operation. The burner is the major contributor to NOX emissions from the RTO due to the
high flame temperatures.7'10 i .
Several facilities in the wood products industry have noted trouble with buildup of
particulates or salts in the heat recovery beds of RTO. The salts include submicron particles of
sodium and potassium oxides which originate from wood ash that passes through direct wood-
3-7
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fired dryers. The salts can penetrate deep into the RTO media, where they melt and fuse to the
media. In the liquid state, these salts react with the ceramic media causing;the media to weaken
and crumble, which eventually leads to restriction of air flow and unacceptable pressure drop
through the RTO system.11'12 When air flow through the RTO packing is restricted, the iiir flow
through the dryers is also restricted resulting in dryer plugging and the potential for dryer fires.
"Bakeouts" and "washouts" are two methods used to combat the buildup of particulates and salts
in the RTO media. Glazing of the RTO media by salts occurs most rapidly at the top of the RTO
media bed where temperatures are the hottest.13 A paniculate prefilter, such as a WESP, may be
used upstream of an RTO to remove some of the particulates or salts before they enter the RTO.
During a bakeout, the RTO temperature is increased to bum the residue off of the media.
Online bakeout features have been incorporated into the design of some RTO to allow bakeouts
without shutdown of the RTO or production line. Once bakeouts are no longer effective in
removing buildup on the RTO media, washouts may be performed. During a washout, residue is
rinsed from the media beds by manually spraying water over the media. The RTO must be shut
down and cooled prior to washout. Most facilities must perform bakeouts from time to time.
However, there are some facilities that perform washouts rather than bakeouts. In addition, there
are some facilities that perform bakeouts but do not perform washouts. The frequency at which
bakeouts and/or washouts must be performed depends on the source controlled and site-specific
conditions but generally ranges from monthly to annually. Frequent bakeouts and washouts of
the RTO can be costly due to lost production.3
3.1.2 Catalytic Oxidization ;
A number of catalytic oxidation systems, including RCO and TCO, are used to control
PCWP process unit emissions. All of these systems have regenerative heat recovery to reduce
operating costs related to fuel consumption. The primary difference between catalytic oxidation
systems and thermal oxidation systems is that catalytic systems employ a catalyst to increase the
rate of the combustion reaction by allowing oxidation to occur at lower operating temperatures.
The use of lower reaction temperatures results in substantial auxiliary fuel savings and, therefore,
reduced operating costs.
An RCO is designed much like an RTO, except that a layer of precious metal catalyst is
impregnated on the ceramic media. Typical operating temperatures for RCO are around 800°F.3
3-8
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I
Another type of catalytic oxidizer, the TJCO, is a combination between an RTO and a RCO. The
TCO runs at a temperature of around 90p°F and contains catalytic media. However, the canisters
and fans on the TCO are sized large enough so that the TCO can be operated like an RTO if
catalyst replacement costs become overly expensive. Natural gas can be injected into the TCO to
reduce NOX emissions.6
A catalyst is a substance that causes or speeds up a chemical reaction without undergoing
any change itself.5 In catalytic ozidizers^ the active catalyst is impregnated on the surface of
temperature-resistant substrate such as ceramic pellets, cylinders, or a monolithic honeycomb.8
Even when using a catalyst, the incoming exhaust gas must be preheated to a temperature
sufficiently high (usually from 300° to 900°F) to initiate the oxidation reactions in the catalytic
oxidizer.2 The specific reaction initiation temperature depends on the type of catalyst and the
specific pollutants in the exhaust gas. The reaction between the O2 in the gas stream and the
gaseous pollutants takes place at the catalyst surface. As the polluted process exhaust passes
though the catalyst bed and is oxidized, tjhere is an increase in temperature proportional to the
amount of organics contained in the exhaust.8
Catalysts have a finite life in terms of catalytic activity. "Catalytic activity" refers to the
degree to which a chemical reaction rate 'is increased compared with the same reaction without
the catalyst.4 Catalyst replacement is necessary when loss of catalytic activity causes the
oxidizer's HAP/VOC reduction efficiendy to fall to unacceptable levels. The basic factors
affecting catalyst life are temperature and deactivation (e.g., poisoning, masking, or fouling).
Each type of catalyst-has a required minimum activation temperature and a maximum
operating temperature above which catalyst performance is impaired or destroyed. Thus, each
catalyst type therefore has a "temperature window" for satisfactory operation. Because the
temperature increase across the catalyst bed is proportional to the organic concentration in the
process exhaust, there is a maximum organic loading that corresponds with the maximum
catalyst operating temperature. Generally, the "temperature window" is greater for precious -
metal catalysts than for base metal catalysts.8
Exposure of catalysts to certain chemical compounds can result in deactivation (i.e., a
loss of efficiency for destruction of hydrocarbons). Deactivation can be caused by poisoning of
the catalyst by compounds containing hedvy metals, sulfur, or phosphorous. Deactivation can
3-9
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also result from masking or fouling of the catalyst by silicon compounds (which convert to silica
on the catalyst surface), PM, or resinous material which may coat the catalyst surface. The loss
of catalyst activity is irreversible when poisoning occurs. Catalyst activity can often be restored
following masking or fouling by techniques such as washing of the catalyst.8
Precious metal (e.g., platinum and platinum group metals) and base metal (e.g.,
manganese dioxide and related oxides) catalysts are commonly used in catalytic oxidizers.8
Precious metal catalysts are more resistant to poisoning and fouling than base metal catalysts.7
Dryers with high moisture and paniculate content in the dryer exhaust could potentially foul
catalytic media. Thus, RTO are most commonly used to control emissions from wood strand and
particle rotary dryers and tube dryers. However, RCO or TCO, as well as RTO, are used to
control emissions from presses or veneer dryers.6'8
Tradeoffs exist between thermal and catalytic oxidizers. Thermal oxidizers generally
require more auxiliary fuel than catalytic oxidizers and operate at temperatures that are several
hundred degrees higher than in catalytic oxidizers. However, deactivation jof the catalyst and
catalytic system is a possibility. Catalytic media is much more expensive than ceramic media (if
ceramic media is used in a thermal oxidizer to recover heat). Thus, catalytic oxidizers have
higher capital and media replacement costs than do thermal oxidizers. However, thermal
oxidizers have higher operating costs than do catalytic oxidizers.
3.1.3 Performance of Incineration-Based Controls
Incineration-based controls are an applicable control technology for a wide range of
exhaust streams containing gaseous organic compounds. Thermal oxidizers generally can be
designed to achieve 95 to 99 percent reduction for most VOC and an outlet concentration of
20 ppmv.8>w Catalytic oxidizers are also frequently designed to achieve 95 to 99 percent
reduction.8 The control efficiency of process incineration systems is expected to be equivalent to
that of a thermal oxidizer. The inlet concentration of combustible organic compounds affects the
achievable percent reduction. For example, a 98 percent reduction is more easily achieved when
there is a high concentration (e.g., 1,000-ppm) of organics. However, a 98 percent reduction may
be more difficult to achieve for low inlet concentrations (e.g., < 100 ppm).
Tables 3-1 and 3-2 summarize the range and average of the inlet and outlet concentrations
and achievable percent reductions for formaldehyde, methanol, and THC for RTO and RCO.
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The performance data for individual control systems summarized in Tables 3-1 and 3-2 are
presented in a separate memorandum on control efficiency.1 Examination of the performance
data for individual control systems shows that RTO and RCO used in the PCWP industry can
reduce methanol and formaldehyde emissions by at least 90 percenfcjexcept when the pollutant
loadings of the emission stream entering the control devices are very low. Examination of the
performance data for THC reveals that RTO and RCO can reduce THC emissions by at least
90 percent. As shown in Tables 3-1 and'3-2, low concentrations (generally less than 100 ppmdv)
' i
of methanol and formaldehyde are present at the inlet of PCWP RTO and RCO. Thus, it is
reasonable that the average pollutant reduction efficiency for these compounds is less than the
typical design VOC destruction efficiency for RTO and RCO (i.e., 95 to 99 percent).
TABLE 3-1. SUMMARY OF RTO PERFORMANCE FOR
FORMALDEHYDE, METHANQL, AND THCa
Pollutant
Formaldehyde
Methanol
THC (as carbon, minus methane)0
No; of
tests
17
15
25
Minimum-maximum (average)
concentration, ppmvd
RTO Inlet
1.0-45 (13)
4.0-109 (25)
51-5,090(613)
RTO Outlet
0.067-13 (1.4)
0.25-4.6 (0.75)
0.5-130 (17)
Control
efficiency, %b
51-99.8 (89)
78-99.7 (94)
90-99.9 (97)
a This table presents the range and average of the available inlet and outlet concentration and control efficiency data
for RTO used in the PCWP industry. Lower control efficiencies generally correspond with lower inlet
concentrations and higher control efficiencies generally correspond with higher inlet concentrations.
b Control efficiencies are calculated based on mass rates (inlet vs. outlet) which are not shown in the table.
c Excludes one data set not corrected for metharje and one data set measured during process upsets.
TABLE 3-2. SUMMARY OF RCO PERFORMANCE FOR
FORMALDEHYDE, METHANOL, AND THCa
Pollutant
Formaldehyde
Methanol
THC (as carbon, minus methane)
No. of
tests
2
2
3
Minimum-maximum (average)
concentration, ppmvd
RCO Inlet
3.5-21
9.3-13
44-1,831 (674)
RCO Outlet
2.6-7.9
0.94-3.9
15-153 (64)
Control
efficiency, %b
18-51
67-87
89-99 (94C)
a This table presents the range and average of trie available inlet and outlet concentration and control efficiency data
for RCO used in the PCWP industry. Lower control efficiencies generally correspond with lower inlet
concentrations and higher control efficiencies (generally correspond with higher inlet concentrations.
b Control efficiencies are calculated based on ir&ss rates (inlet vs. outlet) which are not shown in the table.
c Excludes one control efficiency not corrected for methane.
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No specific inlet and outlet test data are available to determine the control efficiency
achieved by thermal oxidizers (witirout heat recovery) and TCO used in the PCWP industry.
However, it is expected that thermal oxidizers and TCO can achieve the same level of control as
RTO and RCO, respectively. Furthermore, no inlet and outlet test data are available for process
incineration systems. However, test data for one process incineration system (a heat/energy
exhaust gas recirculation system at an OSB plant used to control emissions from rotary strand
dryers) shows that THC and formaldehyde emissions from the system on a pounds per oven dried
ton (Ib/ODT) basis are comparable to or lower than emissions at the outlet1 of an RTO used to
control similar dryers.15'16
Incineration-based controls currently used in the PCWP industry include 2 thermal
oxidizers, 82 RTO, 8 RCO, 8 TCO, and 9 process incineration systems. The thermal oxidizers
are used to control tube dryers and veneer dryers. The RTO, which by far are the most
commonly used incineration-based control systems in the PCWP industry, are used to control
various types of dryers, presses, board coolers, and hardboard process units. The RCO control
OSB presses and dryers, veneer dryers, land hardboard process units. One of the TCO controls an
OSB press and the other TCO is used to control the combined exhaust from an MDF press and
tube dryers. The process incineration systems are used to control OSB rotary and conveyor
dryers, MDF dryers and an MDF press, and veneer dryers. Although a variety of process units
are controlled with incineration-based control systems, the performance data for incineration-
based controls show that the same level of control (e.g., outlet concentration and/or control
efficiency) can be achieved regardless of the type of process unit controlled.1
3.1.4 Monitoring of Incineration-Based Controls
Operating parameters monitored for incineration-based controls may include temperature,
flow rate, system pressure, catalyst activity for catalytic systems, and valve timing for
regenerative systems. Monitoring of these operating parameters is discussed below. In addition
to operating parameters, some facilities may continuously monitor VOC (or THC), CO, or stack
opacity, depending on the process units controlled by the control system and the applicable
regulatory requirements.3
Combustion chamber (or "firebox") temperature is a key operating parameter monitored
for thermal oxidizers. Monitoring and controlling firebox temperature is, a good method for
3-12
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ensuring that the oxidizer achieves the necessary ignition temperature required for pollutant
I '* --1-~
destruction. In catalytic oxidizers, temperatures at the inlet and/or outlet of the catalyst bed may
be monitored to indicate catalyst activity (shown by a temperature increase across the catalyst
bed) or to control operation of the oxidizer.
Exhaust gas flow rates may be monitored directly with a flow meter or through use of a
flow indicator such as fan power or static pressure. Pressure drop varies as gas flow rate through
the control system varies. An increase in pressure drop or change in static pressure can indicate
problems with plugging of the heat recovery media.
As discussed in Section 3.1.2, catalyst material life is impacted by poisons, masking
agents, and thermal or physical degradation. Annual sampling and testing of the catalyst in a
catalytic oxidizer can be performed to determine catalyst activity.
Operation and maintenance of the; valve system for switching between heat recovery
canisters can affect the performance of regenerative systems (i.e., RTO, RCO, or TCO). Leaking
valves or valve timing that is off could allow a small portion of untreated exhaust gases to bypass
the oxidation chamber. Periodic inspection of the valves and verification of the valve timing
could be done periodically to guard against reduced system performance.
3.2 BIOFILTRATION i .
3.2.1 Description of Biofiltration .!....
Biofiltration system's are currently used to control emissions of HAP and VOC from
PCWP presses and board coolers in the United States. Biofiltration systems consist of a vacuum
system, a humidification system, and the biofilter. Figure 3-3 presents a schematic of a
biofiltration system. The vacuum system: moves process unit exhaust through the humidification
system and biofilter. The humidification'system uses water sprays to cool and saturate the air
entering the biofilter. The humidification system also removes excess particulates from the air
stream. Pre-humidification of the gas stream entering the biofilter also helps to prevent the
constant flow of gas from drying the biofilter media. Humidification may be accomplished with
water spray nozzles in the biofilter inlet duct, with spray chambers in enlarged sections of the
inlet duct, or through use of a wet scrubber or packed bed upstream of the biofilter.17'18
3-13
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[
Humidified process exhaust
Process
exhaust
Water i
w
1
A A
Humidification
systerp
:^i«l**l*
^^^^^^^^
C /-v w
rl ^
I
H
; Treated air
' t
AA Ai A i A » A.
H, \ f f i t
Packing :-!
media
A A A A ^
_
"""
Drain
water
Figure 3-3. .Schematic of a biofiltration system.
The biofilter contains porous packing such as bark; wood chips, peat, or synthetic media.
The media provides a large surface area tor the absorption and adsorption of contaminants. The
life span of bark varies from 6 months to 2 years depending on the properties of the gases being
treated. 'Composted wood chips may last up to 7 years.19'20 A structural component may be
added to the media to prevent compaction which would result in excessive pressure drop across
the filter bed." The filter media naturally contains some microorganisms and is inoculated with
additional microorganisms that are well suited for the environment in the biofilter and the
exhaust gas to be treated. Acclimation of the microorganisms to the biofilter environment and
gases to be treated may take weeks or months.20 The microorganisms are immobilized in an
aqueous layer or "biofilm" on the packing material. Typical biofilter design consists of a 3- to
6-foot-deep bed of media suspended over an air distribution plenum.
The vacuum system draws the humidified gases into the plenum under the biofilter where
the gases are evenly distributed under the media. The exhaust gases are forced upward through
the moist biofilter media. As the contaminated exhaust stream passes through the biofilter
media, pollutants are transferred from the vapor phase to the biofilm. Once in the biofilm, the
pollutants are oxidized by microbiological activity to CO2, water, and mineral salts. The
biological oxidation process can de described as follows:
organic pollutants + O2 -> CO, + H2O + heat + biomass
3-14
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Microorganisms require a carbon source, water, and nutrients (e.g., N2 and phosphorous)
to carry out metabolic processes necessary for the microorganisms' growth, reproduction, and
survival. In biofiltration systems, the carbon source is the hydrocarbon pollutants from the
exhaust gas. The biofilter media is also a source of carbon and nutrients for the microorganisms.
Water and nutrients are added to the biofiltration system through water sprays over the biofilter
media and by humidification of the incoming exhaust gases. A media moisture of 30 to
60 percent is generally maintained.17'20 Water and condensate flowing through the biofilter media
is collected in the plenum underneath the biofilter which slopes so the water drains away to the
wastewater handling system.
Microorganisms also thrive within specific temperature and pH ranges. Outside of those
ranges, the microorganisms become less active; therefore, the pollutant reduction efficiency of
the biofilter can decrease if appropriate temperature and pH conditions are not maintained in the
media bed. The optimal temperature range for the types of microorganisms used in biofilters
(i.e., mesophilic microorganisms) is around 70° and 95°F.n The upper limit of temperature for
activity of mesophilic microorganisms isiabout 105°F.19'21 Most microorganisms grow best in a
relatively neutral pH range (i.e., pH 6 to 8).20'22
There are two main biofilter designs used, including the completely open system and the
totally enclosed system. Completely open systems are less expensive than totally enclosed
systems, however, the performance of an,open system can be affected significantly by outside
influences (e.g., rain, wind, and sun). Completely open systems are used primarily for odor
control of dilute and cool exhaust streams. A totally enclosed system is necessary for exhaust
streams with higher concentrations of organic compounds and increased monitoring requirements
(e.g., systems used to comply with emission limits rather than for odor control).17 All of the
biofilters currently used to control emissions from presses and board coolers in the PCWP
industry are fully enclosed. '.
There are three general types of totally enclosed systems, including: building enclosures,
cellular systems, and modular units. Building enclosures are simple to construct and can include
multiple chambers. The spray nozzles can be attached to the roof in order to thoroughly irrigate
the media. Because the roof is an integral part of the building enclosure design, the only way to
enter the biofilter and remove the media s through small doors and hatches (i.e., confined
3-15
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spaces). Cellular systems are subterranean compartments that can be designed and constructed
prior to delivery and assembled on-site. With the cellular design, the roof is easily removed,
which makes access for media replacement more convenient. Modular units are similar to
cellular systems, except that the modules include self-contained gratings, media, and irrigation
systems. The entire module can easily be removed and replaced with an entirely new module
without interrupting the whole biofiltration system. The modular design is accommodating to
facilities with future expansion plans.
Onsite pilot-scale tests using a slip-stream of the actual gas stream targeted for control are
often conducted prior to design of a full-scale biofiltration system. Such tests reveal fluctuations
in off-gas conditions, such as pollutant concentration and temperature, and the presence of
contaminants or particulates. Pilot tests are valuable for tailoring the biofflter media, microbes,
and operating parameters to site-specific conditions.17 :
3.2.2 Performance of Biofilters
Biofiltration systems are effective for treating low concentrations (e.g., <1,000 ppm) of
organic compounds with organic loading rates between 300 to 500 ft3/ft2-hr.20 Biofilters perform
best when a steady flow of gaseous HAP or VOC must be treated, because fluctuations in
emissions make the biological reactions more difficult to control.23 The size of the biofilter
increases as the flow rate and organic concentration increases in order to provide sufficient
residence time for treatment of the organic loading. Biofiltration is most effective on water
soluble and biodegradable organic contaminants. Formaldehyde, phenol, and methanol meet
these criteria.17 However, some VOC compounds emitted from PCWP process units (such as
' pinenes) are less water soluble. Biofiltration cannot successfully treat some organic compounds,
such as chlorinated VOC, which have low adsorption or degradation rates.20
Five biofilters are being used to reduce emissions from presses or board coolers at four
wood products plants. Table. 3-3 summarizes the inlet and outlet concentrations of
formaldehyde, methanol, and THC in the PCWP exhaust streams treated using biofilters.1
Table 3-3 also summarizes the control efficiency achieved by biofilters for these pollutants.
o
3-16
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TABLE 3-3. SUMMARY OF BIOHLTER PERFORMANCE FOR
FORMALDEHYDE, METHANOL, AND THCa
Pollutant
Formaldehyde
Methanol
THC (as C, minus methane)
No. of
tests
3 ;
2
3 ;
Minimum-maximum (average)
concentration, ppmvd
Biofilter Inlet
2.9-13 (8.1)
19-90
84-130(110)
Biofilter Outlet
0.07-0.22(0.15)
0.32-18
7.1-27(19.2)
Control
efficiency, %b
97-98 (98)
79-98
73-90(81)
3 This table presents the range and average of the available inlet and outlet concentration and control efficiency data
for biofilters used in the PCWP industry.
b Control efficiencies are calculated based on mass rates (inlet vs. outlet) which are not shown in the table.
3.2.3 Monitoring of Biofilters
The health of the microorganism population and the ability of the biofilter to destroy
pollutants depends on the amount of moisture in the biofilter, pH of the biofilter media, bed
temperature, and nutrienjt levels. Adequate moisture is needed to ensure survival of the
i
microorganisms, to ensure that pollutants are transferred to the biofilm, and to prevent drying and
channeling of the biofilter media. Over-watered and/or poorly drained media may also cause
problems such as development of wet spots and anaerobic zones, and reduction in the active
surface contributing to pollutant transfer; Over-watered media is also prone to channeling.18 The
microorganisms become acclimated to certain pH, temperature, and nutrient level ranges, and
large swings in these ranges can slow uptake and degradation of pollutants by the
microorganisms. Severe changes in pH or temperature could destroy the microorganisms.
Particulate buildup in the system, which is indicated by increased system pressure, also affects
the performance of the biofilter. A reduction in the activity of the microorganism population can
be indicated through routine or continuous monitoring of VOC (e.g., with the THC analyzer).
Alternatively, bacteria counts could be monitored by collecting samples of the biofilter media or
effluent and analyzing the samples in a laboratory. Nutrient levels and pH could be checked by
monitoring the effluent from the biofilter. Pressure drop and bed temperature (or gas stream
temperature) are biofilter parameters that are routinely monitored.3'24'25
3-17
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3.3 CAPTURE DEVICES
Sections 3.1 and 3.2 discussed two types of control devices (incineration-based controls
and biofilters) used for destruction of gaseous HAP emissions. The reduction in gaseous HAP
emissions from a process unit depends not only on the destruction efficiency of the control
device, but also on the percentage of the process unit exhaust routed to the control device.
Therefore, this section discusses capture devices used to capture and route process unit exhaust
to a control device. "Capture efficiency" refers to the fraction of emissions from a process unit
that is captured and routed to the control device. The total HAP reduction efficiency of a control
system (i.e., capture device and control device) is the product of the capture efficiency and
control device destruction efficiency.
Most process units at PCWP plants exhaust through stacks or duct work; therefore,
100 percent of the exhaust from the process unit is routed to the control device. However,
emissions from PCWP presses and board coolers do not exhaust directly through stacks.
Gaseous HAP emissions are released directly into the press or cooling area. These emissions
i
typically are drawn through the roof vents above the press or cooler. The emissions that are not
drawn through the roof vents dissipate inside the building (and are eventually emitted through the
building ventilation system). Several PCWP plants have hoods or other partial capture (devices
above the press area to aid in collection of the press and board cooler emissions. The capture
efficiency achieved by such devices is not known and is difficult to measure.
Permanent total enclosures, as defined by EPA in Method 204 (40 CFR 51, Appendix M),
are presumed to achieve 100 percent capture. Thus, the capture efficiency of PTEs does not
require measurement. To be considered a PTE (and qualify for the presumption of 100 percent
capture), a total enclosure must meet the five design criteria summarized below:26-27
1. All emission points inside the enclosure must be at least 4 equivalent diameters from
any openings;
2. The total area of all openings (doors, windows, etc.) must not exceed 5 percent of the
enclosure's surface area (walls, floor, and ceiling);
3. Air must flow into the enclosure at all openings with an average face velocity of at
least 200 ft/min (which is equivalent to approximately 0.007 inches of water column);
3-18
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4. All windows and doors not counted in the 5-percent of area rule must be closed
during normal operation; and
5. All exhaust streams must'be discharged through a control device.
Capture devices (e.g., hoods or partial enclosures) that do not meet the PTE design
criteria are not considered to be total enclosures and the capture efficiency of such devices must
be measured. To measure the capture efficiency for an unenclosed or partially enclosed process
unit, a temporary total enclosure (TTE) must be constructed and EPA Methods 204 and 204A
through 204F in 40 CFR 51, Appendix M must be used to measure the capture efficiency of the
TTE. An existing building can be used jas either a PTE or TTE, provided it meets the applicable
criteria in EPA Method 204. ;
Some PCWP facilities have constructed PTE around presses and/or board coolers. The
PTEs are usually made of corrugated sheet metal extending from the roof of the press area to the
floor. -Existing walls of the press building may be used as part of the enclosure. The press
unloader is generally included inside the enclosure with the press; however, the press loader may
or may not also be included within the enclosure. The openings in the enclosure walls for the
unpressed mats to enter and for the pressed boards to exit may have heavy plastic flaps to
minimize in-leakage of ambient air. At some plants, the board cooler exhaust is ducted into the
press enclosure.3 i
The key to maintaining PTE performance is maintaining the integrity of the enclosure and
the airflow through the system. Techniques for ensuring the integrity of the enclosure may
include periodic inspections (e.g., to ensure plastic strips have not been knocked off) and use of
self-closing mechanisms on doors. An indicator such as duct static pressure or fan amperage can
be monitored to ensure that the system airflow from the enclosure to the control device is
maintained. i
3.4 WET ELECTROSTATIC PRECIPITATORS
Wet electrostatic precipitators are commonly used in the PCWP industry ta reduce PM
(including PM10 and PM2 5) from dryer exhausts. Wet electrostatic precipitators are often used
upstream of RTO in the PCWP industry to protect the RTO from long-term media degradation
caused by fine particulates and salts. As discussed in Section 3.1.1.3, the salts originate from
\ 3-19
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wood ash that passes through direct wood-fired dryers. Bakeouts and washouts of the RTO
media can combat this buildup to some degree; however, the RTO media may require frequent
replacement.11'12 Thus, many PCWP" plants choose to install a WESP to reduce the effects of
buildup and the frequency of RTO maintenance. However, depending on company philosophy,
some plants may elect not to install a WESP or to use a less efficient PM control device (e.g., a
multiclone) upstream of the RTO to avoid the operating costs associated with WESP although
more frequent replacement of RTO media may be necessary. i
According to industry survey data, over two-thirds of OSB rotary dryers with
incineration-based controls (including RTO, RCO, or TCO) have a WESP as a prefilter prior to
the incineration-based device. Five of the nine (just over half) of the particleboard rotary dryers
with RTO have WESP. One third of the tube dryers with incineration-based controls (RTO or
TCO) have WESP. However, no WESP dedicated to press emissions are operated upstream of
press controls and no WESP are operated upstream of incineration-based controls (RTO or RCO)
on veneer dryers.3 Based on the survey data, it appears that exhaust streams from rotary particle
dryers, tube dryers, veneer dryers, and presses generally do not have the high fine particulate or
salt loadings that can necessitate use of a WESP. Prefiltering of exhaust from particle and tube
dryers can be accomplished using lower-cost PM control devices. Prefiltering of exhaust from
veneer dryers and presses is usually not necessary.28'29 ;
Wet electrostatic precipitators are effective on effluent gas streams when there is a
potential for explosion, when the particulates are sticky or are liquid droplets, or when the dry
dust has an extremely high resistivity. Thus, WESP are well suited for PCWP dryer exhausts
because these exhausts are quite humid,and contain wood particles and sticky organic
compounds. Particulate removal efficiency for WESP varies from about 90 to 99.9 percent,
depending on the system design. New WESP are commonly designed to achieve 99 percent or
greater PM removal.30
A low energy wet scrubber (or prequench) is used upstream of the WESP to cool and
saturate gases before they enter the precipitator. The prequench sprays water into the incoming
gas stream. The amount of cooling required depends on the characteristics of the exhaust air
stream exiting the dryer. The prequench water, which flows at around 275 gallons per minute
(gpm), is typically recirculated for conservation. Caustic may be added to the prequench water
3-20
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for pH control.3 The prequench removes relatively large particles (>2 um) from the incoming gas
stream to reduce the load on the WESP.f Some of the hydrocarbon vapors produced by the
drying process are condensed in the prequench and enter the precipitator as droplets.31 In
addition, some fraction of the highly water-soluble compounds, such as formaldehyde and
methanol, may be scrubbed by the prequench. However, as discussed above, the ability of the
prequench water to absorb water-soluble compounds diminishes as the water becomes saturated.
The WESP uses electrical forces £o move particles or droplets entrained in the exhaust
stream onto collection surfaces. The entrained particles are given an electrical charge when they
pass through a corona, a region where gaseous ions flow. Electrodes in the center of the flow
lane are maintained at high voltage and generate the electrical field that forces the particles to the
!
collector walls. In WESP, the collectors1 are either intermittently or continuously washed by a
water spray.30 ', . .
In a wire-pipe WESP, also called a tubular WESP, the exhaust gas flows vertically
through parallel conductive tubes. The high voltage electrodes are long wires or rigid "masts"
t
that run through the axis of each tube. The electrodes are generally supported by both an upper
and lower frame of the WESP. Sharp points may be added to the electrodes, either at the
entrance to a tube or along the entire length in the form of stars, to provide additional ionization
sites.30 ^ i . ,
Wet electrostatic pre'cipitators require a source of wash water to be injected or sprayed
near the top of the collector pipes either continuously or at timed intervals. The water flows with
the collected particles into a. sump from ^jvhich the fluid is pumped or drained. A portion of the
fluid may be recycled through the prequdnch to reduce the total amount of water required. The
remainder is usually pumped into a settling pond.30
Parameters typically monitored for WESP include amperage, voltage, or current; inlet or
outlet exhaust temperature; spark rate; arjd washing frequency.3
3.5 OTHER CONTROL TECHNIQUES
This chapter has focused on APCD that are already commonly used in the PCWP
industry. However, any pollution control technique that achieves the emission limits requited by
the PCWP standards can be used to comply with the standards. New APCD and lower-emitting
process equipment are continually under.development. For example, one engineering firm has
j
I 3-21
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developed a regenerative vapor recovery system (RVRS) applicable to low concentration, high
flow, and high humidity exhausts. The RVRS adsorbs VOC onto polymeric adsorbents and uses
a microwave desorption system followed by condensation of the desorbed VOC.32
Catalytic infrared drying of wood strands is an example of a'Bew drying technology under
development. With catalytic infrared drying, an energy source such as natural gas or propane is
oxidized in the presence of a catalyst to produce infrared energy, CO2, and water. The wood
strands absorb the infrared energy which heats the strands to around 250°F and dries them.
Because of the lower drying temperature and absence of combustion in the catalytic infrared
drying system, emissions of NOX, CO, and VOC from catalytic infrared drying are lower than
from rotary wood strand dryers.33
Low temperature conveyor drying is a drying technology that has already been employed
to dry wood strands at PCWP plants. Emissions of HAP, VOC, PM, and NOX are lower with the
conveyor dryer than with rotary strand dryers because drying occurs at lower temperatures and
conveyors (as opposed to pneumatic conveyance) are used to move the wood strands through the
dryer.16'34
\ i
Another technology under development is a rotary concentrator that could be used to
concentrate dilute press exhaust streams. The rotary concentrator is applicable for press exhaust
streams because the inlet temperature of the gas stream entering the concentrator must be less
than 120°F. The pollutant-laden press exhaust gas is drawn through a rotary adsorber where the
pollutants are adsorbed onto the adsorbent media affixed to the rotor. The purified air flowing
from the adsorber is directed to the atfnosphere. The pollutants adsorbed on the rotor are
' continuously desorbed by a high temperature, low-volume desorption air stream. The desorption
air stream exits the rotor containing the pollutants and may be directed to a thermal oxidizer or
other control device. Test results reportedly show rotary concentrator efficiencies of up to
98 percent.35 '
3.6 REFERENCES FOR CHAPTER 3
1. Memorandum from R. Nicholson, MRI, to M. Kissell, EPA/ESD. May 26, 2000. Control
Device Efficiency Data for Add-on Control Devices at PCWP Plants.
3-22
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2. OAQPS Control Cost Manual (Fifth Edition), Chapter 3 - Thermal and Catalytic
Incinerators. U. S. Environmental Protection Agency, Office of Air Quality Planning and
Standards. Publication No. EPA 45J3/B-96-001. February 1996.
. I
*" I
3. Memorandum from D. Bullock, K. Hanks, and B. Nicholson, MRI, to M. Kissell,
EPA/ESD. April 28,2000. Summsjry of Responses to the 1998 EPA Information
Collection Request (MACT Survey) - General Survey.
i . -
4. Cooper C.D. and F.C. Alley. Air Pollution Control: A Design Approach. 2nd edition.
Prospect Heights, IL, Waveland Press, Inc. 1994. pp. 354, 360,488-504.
5. Beachler, D., Jahnke, J., Joseph, G. jand M. Peterson. APTI Course SI: 431, Air Pollution
Control Systems for Selected Industries - Self Instructional Guidebook. U. S.
Environmental Protection Agency. Publication No. EPA 450/2-82-006. June 1983.
i . .
6. Memorandum from Hanks, K. and Bullock, D., MRI, to Lassiter, P., EPA/ESD. May 27,
1998 (Finalized March 1,1999). Site Visit - Georgia-Pacific Oriented Strandboard Plant in
Brookneal, VA. EPA. !
7. McMahon, A., Durr Environmental Incorporated. Minimizing RTO Operating Costs in
OSB Mills. Panel World. September 1998. pp. 52-54.
8. Seiwert, J., Smith Engineering Company. Untitled paper presented at the American
Institute of Chemical Engineers (AlChE) Meeting in Denver, CO. August, 1994. Printed
from www.smitheng.com/techaich/techaich.htm on September 1, 2000.
I
9. Cloud, R., Huntington Environmental Systems. Thermal Treatment Systems for Volatile
Organic Control. Printed from wwvj'.huntingtonl.com/hes_cas3.html on June 4, 1999.
10. Kirkland, J., Smith Environmental Corporation. VOC Control for the Panel Industry.
Panel World. September 1998. pp.|56-57.
i
11. Jaasund, S., Geoenergy International Corporation. Proper Care Saves Money In Dryer
Emission Control Systems. Panel World. September 1999. p. 13.
12. Jaasund, S., Geoenergy International Corporation. Upstream Particulate Removal for
RTOs on Direct-Fired Dryers: How Much Is Enough? Panel World. September 2000. pp.
50-51. i
13. Memorandum from K. Hanks and D. Bullock, MRI, to P. Lassiter, EPA/ESD. December 1,
1997. Site Visit - Willamette Industries, Arcadia Oriented Strandboard (OSB) Plant,
Arcadia, LA. : ,
14. Memorandum and attachments from J. Farmer, EPA, to distribution. August 22, 1980.
Thermal Incinerators and Flares. !
i 3-23
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15 Stationary Source Sampling Report for Georgia Pacific Corporation, Mt. Hope, WV,
Wellons Energy Unit, Press Vent, test Dates August 7-8, 1996. Prepared for Georgia
Pacific Corporation, by Trigon Engineering Consultants, Inc. Project No. 047-96-004.
August 1996.
16. Memorandum from D. Bullock and K. Hanks, MRI, to M. Kissell, EPA/ESD. April 27,
2000. Documentation of Emission Factor Development for the Plywood and Composite
Wood Products Manufacturing NEJSHAP.
17. Pond, R.L. Biofiltration to reduce VOC and HAP emissions in the board industry. TAPPI
Journal. Volume 82, No. 8. August 1999.
18. Standefer, S. and R. Willingham, PPC Biofilter. Experience with Pilot-and Full-scale
Biofilter Operations. Printed from www.ppcbio.com/biopr4.html on August 28, 2000.
19. AirScience Technologies Technological Fact Sheet - Biofiltration of gaseous effluents (F2-
04-96B). Printed from www.enviroaccess.ca/fiches_2/F2-04-96ba.html on June 21,1999.
20. Anit, S. and R. Artuz. Biofiltration of Air. Printed from www.rpi.edu/dept/chem-
eng/Biotech-Environ/.../biofiltration.html on June 21,1999.
21. Mohseni, M. and D! Allen, Biofiltration of a-Pinene and Its Application to the Treatment of
Pulp and Paper Air Emissions. 1997 Environmental Conference & Exhibit.
22. LaGrega, M., P. Buckingham, and J. Evans. Hazardous Waste Management. New York,
McGraw-Hill, Inc. 1994. pp. 562-569.
23. Biedell,E. Pollution Engineering. VOCs Pose a Sticky Situation for Industry. Autumn
1997 Pollution Engineering International. Printed from Pollution Engineering Online
(http://www.pollutionengineering.com) on June 21, 1999.
24. Proposed Monitoring Protocol for Biofiltration Systems From the Forest Products Industry,
report by G. McGinnis, M. Connell, and A. Nadeau, submitted to the U. S. Environmental
Protection Agency. May 5, 2000.
I '_
25. Memorandum from T. Holloway, MRI, to W. Schrock, EPA/ESD. October 14, 1998.
Minutes of the August 5,1998 meeting with Envirogen, Inc.
26. Method 204 - Criteria for Verification of a Permanent or Temporary Total Enclosure.
40 CFR 51, Appendix M.
27. Bemi, D., Permanent Total Enclosures Used to Capture VOCs in Process Air Streams.'
EM. April 1999. ; .
3-24
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28. Telecon. R. Nicholson, MRI, with R. Grzanka, Smith Engineering. March 23, 2000.
Discussion of use of RTOs in the vfood products industry.
29. Donnel, R. (editor). Geoenergy Principles Have Been Pushing the Right Buttons. Panel
World. September 1999. pp. 10-12.
i
30. Fact Sheet: U. S. Environmental Protection Agency, EPA-CICA Air Pollution Technology
Fact Sheet for Wire-Pipe Type Wet Electrostatic Precipitators.
I
31. Raemhild, G., Geoenergy International Corporation. Balancing Wet ESP, RTO
Application. Panel World. September 1998. p. 51.
i
32. Product literature from American Purification, Inc. Presented to the U. S. Environmental
Protection Agency. June 30, 2000.| -
! - ' '
33. Macaluso, V., Catalytic Industrial Group (Independence, KS), and R. Davis, Cat-Tec
Industries, Inc. (Eden Prairie, MN).; Preliminary Report and Findings on the Drying of
OSB Flakes and Fines Through thejuse of Catalytic Infrared Energy. Funding provided by:
U.S. Department of Energy, Catalytic Industrial Group, Cat-Tec Industries, Inc., Potlatch
Corporation, and The Institute of Paper Science and Technology. February 1999.
i
34. Dexter, J. Low Temp, Conveyoriz^d Strand Drying Recognized By State and B.A.C.T.
Panel World. March 1998. p. 34. ;
35. Blocki, S., Durr Industries, Inc. Roltary Concentrator for Controlling VOC Emissions from
Press Exhaust. Abstract for presentation at the Washington State University Particleboard
and Composite Materials Symposium. 1995.
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. 4.0 CONTROL AND TESTING/MONTTORDsTG COSTS
This chapter presents the estimated nationwide capital and annualized costs for
compliance with the PCWP rule. Compliance costs include the costs of installing and operating
air pollution control equipment and the costs associated with demonstrating ongoing compliance
(i.e., emissions testing, monitoring, reporting, and recordkeeping costs). Section 4.1 discusses
the estimated air pollution control costs. ^Cost estimates associated with testing, monitoring,
reporting, and recordkeeping are discussed in the Paperwork Reduction Act submission for the
proposed PCWP standards and are summarized in Section 4.2.
4.1 BASIS FOR CONTROL COSTS
As discussed in Section 3.1, add-on APCD most likely to be used to comply with the
PCWP rule include incineration-based controls (e.g., RTO, RCO, and process incineration) or
biofilters. The control device most comnjtonly used to control emissions from PCWP plants is
the RTO. Therefore, for costing purposes, it was assumed that most plants would install RTO to
i ,
comply with the rule. ;A number of RCOJand biofilters are also presently used by PCWP plants.
In addition, several plants with large capacity heat energy systems currently use process
incineration. However, the applicability of process incineration is limited to those plants that
have, or may later install, large onsite heat energy systems. There may be cost advantages to
using RCO, biofilters, process incineration, other add-on control devices, or pollution prevention
measures instead of RTO for some plants. Plants may elect to use any of these technologies to
comply with the rule, provided the techncjlogy limits HAP emissions to the levels specified in the
rule. However, the cost analyses described in this chapter focus on use of RTO due to their
prevalence in the industry, to minimize thje number of cost algorithms developed, and to avoid
judgments regarding which plants may chjoose a particular technology.
4-1
-------
Oriented strandboard plants typically install WESP upstream of rotary dryer RTO to
protect the RTO media from plugging. Thus, the capital and annualized costs associated with
WESP were modeled for rotary strand idryers. As discussed in Chapter 3, available information
indicates that WESP are not necessary for protecting RTO installed on other types of dryers (e.g.,
tube dryers) or on presses.1 Therefore, with the noted exception of OSB dryers without WESP,
the existing particulate abatement equipment on process units was assumed to be sufficient for
protecting the RTO media.2
Enclosures must be installed around presses to ensure complete capture of the press
emissions before routing these emissions to a control device. Thus, the capital costs of
permanent total enclosures (PTE) were included in the costing analyses. Annualized costs
associated with PTE were assumed to be minimal and were not included in the cost analyses.
The following sections (4.1.1 through 4.1.3) discuss the RTO, WESP, and PTE costs.
Section 4.1.4 describes how plant-by-plant control costs were estimated, and Section 4.1.5
summarizes the nationwide control costs.
4.1.1 RTO Costs
An RTO cost algorithm was developed based on: (1) information from an RTO vendor
with numerous RTO installations at PCWP. plants, and (2) the costing methodology described in
the Office of Air Quality Planning and Standards (OAQPS) Control Cost Manual.3'4 The RTO
cost algorithm was used to determine RTO total capital investment (TCI) and total annualized
cost (TAG) based on the exhaust flow to be controlled and annual operating hours. The RTO
cost algorithm is presented in Appendix A. Development of the algorithm is discussed in
Sections 4.1.1.1 and 4.1.1.2.
4.1.1.1 RTO Total Capital Investment.3-4 Equipment costs (including equipment,
installation, and freight) were provided by the RTO vendor for four sizes of RTO. The 1997
equipment costs were not escalated because the Vatavuk Air Pollution Control Cost Index
(VAPCCI) for 1997 (107.9) was slightly greater than the preliminary VAPCCI for RTO in fourth
quarter 1999 (107.8).5 According to the OAQPS Control Cost Manual, instrumentation is
typically 10 percent of equipment cost (RTO and auxiliary equipment); sales tax is typically
3 percent of the equipment cost; and freight is typically 5 percent of the equipment cost.
Figure 4-1 presents the purchased equipment costs (PEC) supplied by the RTO vendor (minus
4-2
-------
freight), and shows that the equipment costs vary linearly with gas flow rate. The regression
equation presented in Figure 4-1 was included in the RTO cost algorithm to calculate the
i
equipment cost for the oxidizer and auxiliary equipment for various gas flow rates.
Instrumentation, sales tax, and freight we're added to the calculated equipment costs to obtain the
total PEC. i
2,500,000
2,000,000
0)
5
o>
a.
s
1,500,000
a
1,000,000
500,000
y = 8.5101x +499194!
R2 = 0.991 !
I *
50,000
I ' !
! 100,000 150,000
Flow rate, dscfm
I
200,000
250,000
Figure 4-1. Variation in RTiO purchased equipment cost with flow rate.
i
Direct installation costs for handljing and erection, electrical, and piping were included in
i '
the equipment cost provided by the RTO vendor! Start-up costs were also included in the
equipment cost provided by the RTO vendor. These costs are typically 22 percent of the PEC.
j I " - ,
Thus, these costs were subtracted from this PEC before further calculations based on the PEC
were performed. Direct installation costs;including foundation and support, insulation for
i . . .
ductwork, and painting were estimated according to the procedures in the OAQPS Control Cost
Manual. Because PTE were costed separately, no enclosure building was costed in the RTO
algorithm. Site preparation costs and indirect installation costs (e.g., engineering, field expense,
4-3
-------
contractor fees, performance tests, and contingencies) were estimated according to the procedures
in the OAQPS Control Cost Manual. The TCI was calculated by summing the PEC, direct and
indirect installation costs, and site preparation cost.
4,1.1.2 RTO Total Annualized Cost. Total annualized costs consist of operating and
maintenance labor and material costs, utility costs, and indirect operating costs (including capital
recovery). Operating and maintenance labor and material costs were estimated based on the RTO
vendor information because the RTO vendor assumptions led to higher costs than the OAQPS
Control Cost Manual and were assumed to be more representative of the PCWP industry. The
operator labor rate supplied by the RTO vendor was $19.50 per hour.
The RTO electricity use and natural gas use was provided by the RTO vendor for the four
RTO sizes. Figures 4-2 and 4-3 present the relationships between flow rate and electricity and
flow rate and natural gas use, respectively. As shown in the figures, there is a linear relationship
between RTO electricity consumption and flow rate, and an exponential relationship between
t
RTO fuel consumption and flow rate.
Electricity costs were estimated by the RTO vendor at $0.045 per kilowatt-hour (kWh).
The RTO vendor estimated natural gas costs at $3 per million British thermal units (MMBtu).
Both of these energy prices match closely with currently published nationwide average prices.6'7
Thus, the electricity and natural gas prices supplied by the RTO vendor were used in the cost
algorithm. '.
1 ,500 -i
> 1,000 -
AX
500 -
y - 0.0052X + 3.283 ,
R = 1 _ ~ ~"
"""'
* » ~ :
j
_ , . i
0 50,000 100,000 150,000 200,000 250,000
Flow rate, dscfm
Figure 4-2. Relationship between RTO electricity consumption and flow rate.
4-4
-------
8-
h. C -
1
* A
ffl 4
SO -
C.
y = 0.1479e2E-°5x"' ! S
R2= 0.9981
/
^^
* ^
\ : \ 1 1
0 50,000 100,000 150,000 200,000 250,000
Flow rate, dscfm
Figure 4-3. Relationship between RTO natural gas consumption and flow rate.
I
Indirect operating costs were estimated using the methodology described in the OAQPS
Control Cost Manual. The capital recovery cost was estimated assuming an RTO equipment life
of 15 years (based on the RTO vendor information) and a 7-percent interest rate. The TAG was
calculated by summing the direct and indirect annual operating costs.
4.1.1.3 Application of the RTO Cost Algorithm to Estimate Capital and Annualized
i
Costs.'The complete RTO cost algorithm, which predicts RTO capital and annualized costs as a
function of operating hours and flow ratel was run several times assuming 8,000 operating hours
per year and various flow rates. The 8,OQO-hr operating time was selected based on the results of
the EPA's MACT survey, which show industry average operating hours of slightly less than
I
8,000 hr/yr.1 Although several plants operate process lines more than 8,000 hr/yr, their
i
equipment and control devices may or inky not be operated for more than 8,000 hr/yr. Thus,
8,000 hr/yr was selected as the control deivice operating time for purposes of costing.
The TCI and TAG values generated for each flow rate using the RTO cost algorithm are
presented in Appendix A. A regression equation was developed based on the calculated TCI and
TAG for each flow rate. Figures 4-4 and 4-5 present the relationships between flow rate and
RTO capital costs and flow rate and annualized costs, respectively, and the associated regression
equations.
4.1.2 WESP Costs
A WESP cost model was developed based on: (1) information from a WESP vendor with
many WESP installations at wood products plants, and (2) the costing methodology described in
4-5
-------
6,000,000
5,000,000
4,000,000
v>
^ 3,000,000
H 2,000,000
1,000,000
y = 13.797X + 809310
R2=1
50,000 100,000 150,000 200,000 250,000 300,000 350,000
Flow rate, dscfm
Figure 4-4. Variation in RTO total capital investment with flow.
3t, 500, 000 -
3,000,000 -
2,500,000 -
zf. 2,000,000
< 1,500,000 -
,000,000 -
500,000 -
-
y = 317394e8E-°6x
R2 = 0.9887 S
^^
^^"
s*****
,>^J~*'*J**^^
*-^*^^
j r r-j; . , , ' t '
50,000 100,000 150,000 200,000 250,000 300,000 350
Flow rate, dscfm
000
Figure 4-5. Variation in RTO total annualized cost with flow.
the OAQPS Control Cost Manual for electrostatic precipitators (ESP).4'8 the cost model was
used to determine TCI and TAG for WESP used to control paniculate emissions from OSB
rotary dryers. The WESP vendor provided cost information for a WESP sized to treat 27,650 dry
standard cubic feet per minute (dscfm) of OSB rotary dryer exhaust. This flow rate matches
closely with the flow rates for uncontrolled OSB. Thus, the model TCI and TAG could be
4-6
-------
I
applied for each dryer to be controlled (i.k, the model need not calculate different costs for
varying flow rates). The WESP cost model is presented in Appendix A. Development of the
model is discussed in Sections 4.1.23. and 4.1.2.2.
4.1.2.1 WESP Total Capital Investment. The WESP and auxiliary equipment costs
(which makeup the PEC) were provided by the WESP vendor. These PEC include the cost of the
WESP; pumps, piping, and tanks; ducting (including the quench); fans; and a 1-gpm blowdown
solids removal system. Instrumentation cjosts were also provided by the WESP vendor. Sales tax
and freight were added into the total PEC based on the methodology described in the OAQPS
Control Cost Manual. !
The direct installation costs such as foundation and support, handling and erection,
electrical, piping, insulation for ductwork,' and painting were included in the PEC provided by the
WESP vendor. It was assumed that no building would be necessary for the WESP and that there
would be no additional site preparation costs. Several indirect costs were also included in the
equipment cost supplied by the WESP vendor, including engineering, construction and field
expense, start-up, and contingencies. Becjause WESP are already widely used at OSB plants, it
was assumed that no model study would be necessary for the WESP although the OAQPS
Control Cost Manual mentions model-stujdy costs for ESP.
The cost of a performance test was included in the WESP cost model. According to the
OAQPS Control Cost Manual, the performance test is typically 1 percent of the PEC. Thus,
1 percent of the model PEC (minus the direct and indirect installation costs included in the PEC)
was used as the cost of the performance test. The direct and indirect costs were summed to arrive
at the WESP TCI. j
i
4.1.2.2 WESP Total Annualized Cost. The direct annualized costs include operating and
maintenance labor and materials, utilities,: and waste disposal. The operating labor cost was
based on 1,146 hr/yr (provided by the WESP vendor) at $19.50/hr (the labor rate used in the
RTO cost algorithm). The annual cost of .operating materials, including caustic and defoamer,
was provided by the WESP vendor. The maintenance labor rate was estimated as 110 percent of
the operating labor rate. The maintenanc^ hours per year were estimated based on information
supplied by the WESP vendor. The cost of maintenance materials (including replacement of one
4-7
-------
pump seal per year, and one voltage controller every 4 years, and miscellaneous materials) was
supplied by the WESP vendor.
The electricity necessary to power the WESP components (approximately
2,076,000 kWh/yr for all WESP components) was based on information provided by the WESP
vendor. An electricity cost of $0.045/kWh was used (the same as used in the RTO cost
algorithm). A $0.20/gal cost for makeup water was used based on the OAQPS Control Cost
Manual. The WESP water recirculation rate, makeup water addition rate, and blowdown
generation rates were provided by the WESP vendor. The OAQPS Control Cost Manual
indicated that wastewater treatment costs may range from $1.30 to $2.15 71,000 gallons.
Methods of WESP wastewater treatment and disposal could include evaporation from settling
ponds, discharge to a municipal water treatment facility, or spray irrigation. The wastewater
treatment and disposal cost for the blowdown was assumed to be $2.15 per gallon. The
wastewater percent solids of 7.6 percent was based on the average from the MACT survey
responses.1 It was assumed that the solids would ultimately be disposed in a landfill (although
they could be burned onsite or used for soil amendment). The trucking cost for hauling sludge to
a landfill was estimated to be $0.20 per cubic yard per mile ($/yd3-mi).9 The landfill was
assumed to be 20 miles away, and a $2Q/ton landfill tipping fee was used.4 The density of the
solids was assumed to be 0.5 ton/yd3 for wet wood paniculate (given that'the density of water is
0.84 ton/yd3 and the density of wood is from 30 to 50 percent of the density of water).
The indirect operating costs were estimated based on the methodology described in the
OAQPS Control Cost Manual, The capital recovery cost was estimated assuming a WESP
equipment life of 20 years (based on the OAQPS Control Cost Manual and WESP vendor
information) and a 7-percent interest rate. The TAG was calculated by summing the direct and
indirect annual operating costs.
4.1.3 Permanent Total Enclosure (PTE) Costs
The capital costs associated with installation of a PTE were based on available
information in the project files on the capital cost of PTE for particleboafd, MDF, and OSB
presses.10 These costs included the following elements:
installed cost of the PTE (including fan system)
ductwork
4-8
-------
instrumentation and wiring
fire suppression (in some cases)
site supervision
start-up and testing
Based on the available cost information, Ithe following algorithm was developed to estimate the
PTE costs for various exhaust flowrates:
TOW = jl.2031 x Q^ + 425,760
where: I
I
= the total capital cost of the permanent total enclosure, $
= design exhaust flow] rate from PTE, dry standard cubic feet per minute
Available information on actual exhaust flow rates from PTE installed around reconstituted
wood product presses was used to develop model flow rates for the various press applications.1'11
Information on press vent flow rates from unenclosed presses was available, but not used,
because unenclosed press flow rates are altered when a PTE is installed around a press.12 The
cost algorithm was then applied to the mbdel flow rates to estimate the capital costs of the model
PTE as- shown in Table 4-1. The costs were rounded to the nearest $ 1,000. In the case of the
i
particleboard press PTE, the cost was set at $485,000 (instead of $481,000, which is the value
i
derived from the cost algorithm) becausej the PTE model flow rate was similar to those for the
MDF and hardboard presses, and applying the same cost to all three types of press PTE
simplified the costing analyses. Annualiked costs were not developed for PTE because the
annualized cost of the fans is already accounted for in the estimated costs of the RTO.
TABLE 4-1. PRESS ENCLOSURE EXHAUST FLOW RATES AND CAPITAL COSTS
Equipment type
Particleboard press
OSB press
MDF or dry/dry hardboard press
Wet/dry or wet/wet hardboard press
Flow rate, dscfm
1 45,524
j 97,509
' 49,413
1 . 49,209 -
PTE capital cost
$485,000
$543,000
$485,000
$485,000
4-9
-------
4.1.4 Plant-bv-Plant Costing Approach
The control costs associated with the PCWP standards were estimated for each plant and
were summed to arrive at a nationwide estimate of control costs. The PCWP standards apply
only to major sources of HAP emissions. Therefore, cost estimates were developed for only
those plants that were estimated to be major sources.13 Sections 4.1.4.1 and 4.1.4.2 describe the
information used to estimate the plant-by-plant control costs. Section 4.1.4.3 describes how the
nationwide control cost estimates were developed from the plant-by-plant estimates.
4.1.4.1 Application of Control Costs to Process Units. The cost models discussed in
Sections 4.1.1 through 4.1.3 were applied to each plant that would likely need to install air
pollution controls in order to meet the PCWP standards. Plant-specific information on process
units (e.g., dryers, presses) and controls was taken from the MACT survey responses.1'14'15 In
addition, information about the presence of PTE on presses was taken from the MACT survey
responses.1 If information about press enclosures was not provided in the MACT survey
responses, or was claimed confidential, the press was assumed to be unenclosed if it was
i
uncontrolled or enclosed if it was controlled for purposes of costing.
Some plants have begun operation and other plants have added equipment or controls
since EPA conducted the MACT survey. Such changes were accounted for in the nationwide
cost estimates. A separate memorandum summarizes the changes to plants that have occurred
following the EPA's MACTsurvey. The nationwide cost estimates reflect the equipment and
controls in place as of April 2000.16
The process units and controls present at each plant were reviewed to determine what
control equipment (i.e., RTO, WESP, or PTE) the plant would need to install to meet the PCWP
standards based on the MACT floor control levels. The MACT floor control levels are based on-
the information presented in Chapters 2 and 3 of this document and are documented in a separate
memorandum.17 Table 4-2 summarizes the process units for which control equipment would be
required to meet the MACT floor and the control equipment costed for these process units. At
each plant, the exhaust gas flow rates from the applicable uncontrolled process units listed in
Table 4-2 were summed to yield a plant-wide uncontrolled exhaust gas flow rate. Process units
already equipped with controls to. meet the MACT floor were not included in the plant-wide
uncontrolled gas flow rate estimates. The procedures for estimating the uncontrolled gas flow
4-10
-------
rates from process units and the application of the cost algorithms is discussed in the following
section.
TABLE 4-2. CONTROL EQUIPls!lENT COSTED FOR PROCESS UNITS WITH
CONTROLLED MACT FLOOR :
Existing process units with
control requirements
Tube dryers (primary and
secondary)
Rotary strand dryers
Conveyor-type strand dryers
Rotary green particle dryers
Hardboard ovens
Softwood veneer dryers
Pressurized refiners
Reconstituted wood
products presses ;
Control i
equipment costed
RTO |
WESP and RTO |
RTO
1
RTO
RTO
RTO
I
None
i
PTE and RTO
Notes
Tube dryers are located at particleboard, MDF, and
hardboard plants
Rotary strand dryers are located at OSB and LSL plants.
Assumed that the WESP is not needed for plants that already
have an RTO without a WESP. Assumed that plants that
currently operate an EFB or multiclone alone (i.e., with no
RTO) would install a WESP with the RTO.
Conveyor strand dryers are located at OSB and LSL plants.
Rotary green particle dryers are located at particleboard,
MDF, or hardboard plants and process furnish with >30%
(dry basis) inlet moisture content at djyer inlet temperature
of>600°F
Includes bake and tempering ovens
Softwood veneer dryers are located at softwood plywood,
hardwood plywood, LVL, and PSL plants and dry ^30% (by
volume, annually) softwood veneer
The exhaust from pressurized refiners typically passes
through a tube dryer and exits through the tube dryer control
device. Therefore, it was not necessary to cost separate
control equipment for pressurized refiners. Pressurized
refiners are located at MDF and hardboard plants.
Reconstituted wood products presses are located at
hardboard, MDF, OSB, and particleboard plants
4.1.4.2 Exhaust Flow Rate to Be Controlled. If provided in the non-confidential MACT
I
survey responses, process-unit specific exhaust flow rate, temperature, and percent moisture were
used to determine the dry standard flow rate for each process unit. If sufficient information was
not provided in the MACT survey response to determine dry standard flow rates (or the
information was claimed confidential), then default values were used for the flow rate. The
default values were based on the average value for other similar process units at plants that
provided enough non-confidential information to calculate the dry standard flow rate. Table 4-3
4-11
-------
summarizes the default flow rates used in the costing analyses. The average flow rates from
press enclosures are described in Section 4.1.3 and were used for all presses.
TABLE 4-3. DEFAULT FLOW RATES
Process line
Particleboard
OSB
MDF
Plywood
Hardboard
Equipment type
Rotary green particle dryer
Tube dryer
Rotary strand dryer
Conveyor-type strand dryer
Primary tube dryer (single-stage or first
stage of staged dryer)
Secondary tube dryer (second stage of
staged dryer)
Softwood veneer dryer
Bake oven
Tempering oven
Primary tube dryer (single-stage or first
stage of staged dryer)
Secondary tube dryer (second stage of
staged dryer)
Flow rate (dscfm)
35,731
14,955
32,478
37,810
79,173
18,195
12,062
4,742
4,055
37,436
31,728
Several plants have multiple process units requiring controls. The flow rates for these
process units were summed and divided across control equipment as necessary. In most cases,
the total dryer flow was assumed to be routed to one or more RTO dedicated to controlling dryer
exhaust, and the total press flow was assumed to be routed to one or more RTO dedicated to
controlling press exhaust. Because RTO fuel costs increase exponentially with gas flow rate,
RTO sizes were assumed to remain less than about 150,000 dscfm. (The largest RTO mentioned
in the MACT survey responses was around 150,000 dscfm.)
In some cases, dryers and presses were assumed to be routed to the same RTO, provided
that the total dryer and press flow remained under 150,000 dscfm. For example, two RTO
(103,500 dscfm each) would be costed for a MDF plant with 2 dryers (79,000 dscfm each) and
4-12
-------
1 press (49,000 dscfm) assuming that the! flow for both dryers and the press could be combined
I , - .. .
and split equally across the two RTO. This approach seems reasonable given that several MDF
plants currently route dryer and press exriaust to the same RTO.
4.1.4.3 Calculation of Nationwide Control Costs. The total plant-by-plant control cost
was calculated by summing the control cost associated with each RTO, WESP, and PTE costed
for each plant. The number of control dejvices at each plant depended on the number of process
units and the exhaust flow to be controlled at the plant. In some cases, only one control device
, i
was costed, while in other cases, multiple control devices were costed for a plant.
Some plants claimed all relevant portions of their MACT survey responses confidential.
In addition, a MACT survey response was not available for a few plants likely to be impacted by
the PCWP standards. Without a non-conlfidential MACT survey response, information was not
available to develop plant-specific cost estimates. Therefore, the average cost for all other plants
manufacturing the same product was usecl to approximate the costs for plants for which there was
no non-confidential plant-specific inform'ation.
t ;
The nationwide capital and annua^ized control costs were determined by summing the
total plant-specific costs. j
4.1.5 Summary of Nationwide Control Costs. Table 4-4 summarizes the nationwide control
r
costs for different product types. The nationwide total capital cost for control equipment is
estimated to be $473 million and the nationwide total annual cost for control equipment is
estimated as $136 million. :
4-13
-------
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g
$
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4-14
-------
4.2 TESTING, MONITORING, REPORTING, AND RECORDKEEPING COSTS
Compliance with the PCWP standards must be demonstrated through performance
testing, ongoing monitoring of process or control device operating parameters or emissions,
periodic reporting to the government age-ncy that implements the PCWP rule, and recordkeeping.
There are capital and annualized costs associated with these testing, monitoring, reporting, and
recordkeeping activities. These costs, which are estimated and documented in the supporting'
statement for the Paperwork Reduction Act submission, are summarized in this section.18
The annual costs associated with [testing, monitoring, reporting, and recordkeeping
activities include reporting and recordkeeping labor; annualized capital for monitoring
equipment, file cabinets, and performance tests; and the operation and maintenance costs
i
associated with monitoring equipment. The capital costs include capital for monitoring
equipment, file cabinets and performance tests. Performance tests are considered to be capital
! '.."'". ; '
costs because plants will typically hire a testing contractor to conduct the performance tests.
The total nationwide capital cost associated with testing, monitoring, reporting, and
record keeping is estimated to be $5.8 million and the total nationwide annualized cost is ;
estimated to be $5.6 million. These costs were developed based on the information presented in
the Paperwork Reduction Act submissioiji for the first 3 years following the effective date of the
PCWP rule. The costs apply for the 223 JPCWP plants that are expected to be major sources.
4.3 REFERENCES FOR CHAPTER 4
I
1. Memorandum from D. Bullock, K.[Hanks, and B. Nicholson, MRI to M. Kissell,
EPA/ESD. April 28, 2000. Summary of Responses to the 1998 EPA Information
Collection Request (MACT Survey]) - General Survey.
2. Telecon. R. Nicholson, MRI, with JR. Grzanka, Smith Engineering. March 23, 2000.
Discussion of control equipment used in the plywood and composite wood products
industry. i
3. Facsimile from 1 Seiwert, Smith Environmental Corporation, to L. Kesari, EPA/OECA.
October 31, 1997. Revised emissions abatement systems RTO pricing (Smith Proposal
BO7-95-156-1, Trinity Consultants!).
4. OAQPS Control Cost Manual (Fifth Edition), U. S. Environmental Protection Agency,
Office of Air Quality Planning and Standards. EPA Publication No. 453/B-96-001.
February 1996. i ;
4-15
-------
5. Vatavuk Air Pollution Control Cost Indexes (VAPCCI). Chemical Engineering. March
2000. p. 150.
6. Energy Information Administration, Form EIA-826. Monthly Electric Utility Sales and
Revenue Report with State Distributions.
7. Energy Information Administration. Natural Gas Monthly. February 2000. p. 60.
8. Letter and attachments from S. Jaasund, Geoenergy International Corporation, to
B. Nicholson, MRI. March 28, 2000. Geoenergy WESP Capital and Operating Costs.
9. Vatavuk, W.M. Estimating Costs of Air Pollution Control. Chelsea, MI, Lewis Publishers.
1991. p. 139.
10. Memorandum from B. Nicholson, MRI, to Plywood and Composite Wood Products Project
File. July 31, 2000. Cost of Permanent Total Enclosures. (Confidential Business
Information)
11. Memorandum from B. Nicholson, MRI, to Plywood and Composite Wood Products Project
File. July 31, 2000. Exhaust Gas Flowrate Information for Enclosed Presses.
(Confidential Business Information)
12. Memorandum froraD. Bullock and K. Hanks, MRI, to P. Lassiter, EPA/ESD. October 27,
1998. Trip report for visit to Temple-Inland Forest Products plant in Diboll, TX.
13. Memorandum from K. Hanks and D. Bullock, MRI, to M. Kissell, EPA/ESD. June 9,
2000. Baseline Emission Estimates for the Plywood and Composite Wood Products
Industry.
14. K. Hanks, B. Threatt, and B. Nicholson, MRI, to M. Kissell, EPA/ESD. May 19, 1999.
Summary of Responses to the 1998 EPA Information Collection Request (MACT Survey)
- Hardwood Plywood and Veneer.
15. K. Hanks, B. Threatt, and B. Nicholson, MRI, to M. Kissell, EPA/ESD. January 20, 2000.
Summary of Responses to the 1998 EPA Information Collection Request (MACT Survey)
Engineered Wood Products.
16. Memorandum from K. Hanks, MRI, to Project Files. April 18, 2000. Changes in the
population of existing plywood and composite wood products plants and equipment
following the information collection request.
17. Memorandum from B. Nicholson and K. Hanks, MRI, to M. Kissell, EPA/ESD. July 13,
2000. Determination of MACT floors and MACT for the Plywood and Composite Wood
Products Industry.
18. Paperwork Reduction Act Submission, Supporting Statement. Plywood and Composite
Wood Products. 2000.
4-16
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I
. 5.0 ENVIRONMENTAL AND ENERGY IMPACTS
i
i
This chapter presents the nationwide environmental and energy impacts estimated to
result from compliance with the PCWP standards. Environmental impacts include air impacts,
wastewater impacts, and solid waste impacts. Energy impacts include the increased consumption
of fuel and electricity to power air pollution control equipment. Section 5.1 discusses the
methodology used to calculate the air imjpacts. Section 5.2 discusses the wastewater impact
estimates, Section 5.3 discusses the solid waste impact estimates, and Section 5.4 discusses the
energy impact estimates. The nationwidje environmental and energy impacts are summarized in
Section 5.5 and the references used are presented in Section 5.6.
. The environmental and energy impacts were estimated using the same plant-by-plant
approach that was employed to estimate ithe nationwide cost impacts in Chapter 4. This plant-by-
plant approach to estimating nationwidelimpacts is described in detail in Section 4.1.4 of this
i
document. The impacts associated with |the PCWP standards were estimated for each plant and
I ' .
were summed to arrive at nationwide impacts estimates. Impact estimates were developed only
for those plants that were determined to be major sources.1 The impact estimates were developed
I
based on the control equipment (e.g., RTO or WESP/RTO) that plants would likely install to
comply with the PCWP standards at thelMACT floor control level. Impact estimates were not
i
developed for process units that already have the necessary control equipment. The impact
estimates represent a worst-case estimate of impacts because the use of RTO results in greater
energy usage and secondary air impacts relative to other control technologies such as RCO and
biofilters.
Table 4-2 in Chapter 4 summarises the control equipment assumed to be installed in
order to meet the MACT floor control levels for various process units.2 Section 4.1.4.2 of
i
Chapter 4 describes how the exhaust flo>v rate to be treated by each control device was
5-1
-------
approximated. An 8,000 hr/yr operating time (the same time used for the cost estimates in
Chapter 4) was assumed for calculation of the environmental and energy impact estimates.
5.1 AIR IMPACTS
The air impacts associated with the PCWP standards included reduction in nationwide
HAP emissions, reduction in THC emissions, changes in emissions of primary criteria air
pollutants, and secondary air impacts associated with increased electricity generation at power
plants. The reduction in HAP and THC emissions is discussed in Section 5.1.1. Section 5.1.2
discusses the changes in emissions of criteria air pollutants and Section 5.1.3 discusses the
I
secondary air impacts.
5.1.1 Reduction in Total HAP and THC
The reduction in emissions of total HAP and THC is the difference between baseline
emissions and the emissions expected to remain following implementation of the MACT floor
level of control identified for the PCWP standards. Baseline emissions reflect the level of air
pollution control that is currently used at PCWP plants. The MACT floor control level reflects
the level of control that will be used following implementation of the PCWP standards. Baseline
emissions are presented in Chapter 2 for each PCWP.
The same plant-by-plant approach used to estimate baseline emissions was used to
estimate the emissions at the MACT floor control level. This approach incorporates specific
information on process units (e.g., throughput, emission controls) from the MACT survey
responses and the emission factors developed for those process units. This approach is
documented in detail in a separate memorandum on baseline emissions.1
As for all of the environmental and energy impacts presented in this chapter, the
following assumptions were used when estimating emissions at the MACT floor control level:
(1) plants will install RTO on all process units that require controls to meet the MACT floor; (2)
presses at conventional particleboard, MDF, OSB, and hardboard plants will be fully enclosed by
a PTE that captures and routes 100 percent of the emissions from the press area to an RTO; and
(3) WESP will be installed upstream of RTO for new RTO installations on rotary strand dryers.
Following the procedure outlined in the baseline emissions memorandum, the HAP and
THC reduction associated with RTO was taken to be 95 percent.1 Thus, for each process unit
that would likely need an RTO to meet the MACT floor control level, uncontrolled HAP and
THC emissions from the process unit were reduced by 95 percent to approximate the average
5-2
-------
emissions remaining following installation of an RTO. No HAP or THC reduction was
associated with WESP. j _
The emission estimates at theM^CT floor control level were summed for each plant.
The plant totals were summed to arrive i
following implementation of the MACT
t a nationwide estimate of-the emissions remaining
floor control level. The nationwide HAP and THC
emission reduction was calculated by subtracting the emissions remaining at the MACT floor
control level from the baseline emissions. Section 5.5 summarizes the nationwide HAP and
THC emission reductions. \
5.1.2 Effect of Standards on Criteria Pollutants
Li addition to reducing HAP and
EHC, the PCWP standards will affect emissions of
primary criteria pollutants (i.e., criteria pollutants emitted directly from an emission source). The
primary criteria pollutants are PM less thjan 10 micrometers in aerodynamic diameter (PM10),
sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and lead (Pb). Of these
pollutants, PM10, CO, and nitrogen oxidds (NOX) are the most prevalent pollutants emitted from
PCWP processes. Emissions of SO2 are not prevalent and are not expected to change greatly due
not destroy or alter SO2 emitted from PCWP process
rating appreciable amounts of SO2 (because there is
to the PC.WP standards because RTO do
units, and RTO are riot suspected of gene:
little, if any, sulfur in the process exhaust-or in the natural gas burned by the RTO). No
i
information is available for use in evaluating emissions of Pb from PCWP processes. Lead is not
expected to be a pollutant of concern for JPCWP processes, and emissions of Pb (if any) are not
expected to change as a result of the PCWP rulemaking. The changes in PM10, NOX (as NO2),
and CO emissions expected to result froip the PCWP standards were estimated using the
i
methodology described in the following $ubsections.
j . ' ...
5.1.2.1 PM-10 Emissions. Plywood and composite wood products process unit exhausts
include solid PM (including PM less than 10 micrometers) and condensible PM. The
I . .
condensible PM leaves the process unit as vapor but may condense at normal atmospheric
temperatures to form liquid particles or aerosols. Condensible PM consists primarily of
compounds evaporated from the wood, fabric filters, cyclones, multicyclones, electrified filter
beds, and other dry paniculate control devices are commonly used to reduce solid PM, but these
control devices are often not as effective jfor controlling condensible PM. Wet electrostatic
precipitators are often used on effluent gas streams containing sticky, condensible organics. The
5-3
-------
WESP collects only particles and droplets that can be electrostatically changed; vaporous
components of the gas stream that do not condense are not collected by the device. Thermal
oxidizers destroy condensible organics by burning them at high temperatures.3
Information needed to estimate the reduction in PMi0 associated with the PCWP
standards includes the RTO inlet PMJO loading and PM10 percent reduction achievable with an
RTO. The RTO inlet PM10 loading depends on whether there is a particulate control device or
"prefilter" upstream of the RTO. Many plants already operate paniculate controls on process
units that will be subject to the PCWP standards. Thus, the additional particulate reduction
achieved by the standards will be only the PM reduction across the RTO (regardless of whether
the particulate control device already in place continues to be used upstream of the RTO installed
to meet the standards).
Emission factors are available for uncontrolled filterable PM, filterable PMj0, and
condensible PM for many PCWP process units.4 These emission factors were used to
approximate the inlet PM loading for RTO on different types of process units. The EPA test
methods 201 and 201A suggest adding filterable PM10 and total condensible PM together to get
total PM,0. Thus, total PMio was calculated as the sum of filterable PM10 and total condensible
PM.
Table 5-1 presents available information on the percent reduction in total PM10 achieved
across combined prefilter and RTO systems. Using the information in Table 5-1, it was
determined that a combined prefilter and RTO control system can achieve about a 90 percent
reduction in PM10.
TABLE 5-1. PERCENT REDUCTION IN TOTAL PM10 ACROSS COMBINED
PREFILTER AND RTO CONTROL SYSTEMS
Process unit and control system description
Multiple MDF process units with WESP and RTO
Particleboard process units with unspecified prefilter and
control
OSB rotary dryer with multiclone and RTO
MDF tube dryer with WESP and RTO
Average
PM10 reduction, %
86
95
90.4
90
90
Reference3
5
6
. 7
8
a See Section 5.6 for a list of references.
5-4
-------
Table 5-2 presents several reported total PM10 reductions across RTO without a prefilter
or following a prefilter (i.e., PM reduction across the RTO only). Using the information in
Table 5-2, it was determined that an RTO alone can achieve approximately an 80 percent
reduction in PMi0.
TABLE 5-2. TOTAL PM,n REDUCTION ACROSS RTO
Process unit
MDF dryer with knockout
MDF dryer with cyclone
OSB dryer with WESP
OSB dryer with multiclone
OSB press
MDF press
Multiple MDF process units with baghouse
Average
PM10 reduction, %
81.5
81.4
72.7
89
75
87.4
60
Approx. 80
Reference3
9
9
9
9
7
9
5
a See Section 5.6 for a list of references.
Given that the approximate PM]0 reduction across a combined prefilter and RTO system
is about 90 percent, and the reduction in PM10 across the RTO alone is about 80 percent, it was
determined that the typical percent reduction in PM10 across a prefilter alone is about 70 percent.
The actual percent reduction in PM10 achieved by a prefilter depends on the type of prefilter and
the inlet PM loading into the prefilter (e.g., amount and fraction of filterable PMIO and
condensible PM). However, for purposes of this analysis, specific PM,0 reductions achieved by
various types of particulate controls were not determined.
The annual PM10 reductions were calculated for process units that would likely need
controls to meet the PCWP standards using the available emission factors and the percent
reductions presented above. Table 5-3 shows the calculated PM,0 reductions. A PMj0 reduction
was not estimated for hardboard ovens or secondary tube dryers because no information was
available for estimating uncontrolled PM10 emissions from these sources.
5-5
-------
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5-6
-------
As mentioned earlier, a plant-by-planjapproach was used to estimate environmental
i '' «:
impacts. The PM10 reductions presented in Table 5-3 were applied to each process unit that
would likely need controls to meet the PCWP standards based on the MACT floor control level.
The PM10 reduction for process units with paniculate controls already in place was applied for
i
process units with controls such as baghouses, sand filters, scrubbers, EFB, wet or dry ESP,
multiclones, or semi-incineration. The PM10 reduction for units without paniculate controls was
applied to units with no paniculate controls or cyclones only. The PM10 reduction associated
with two veneer dryers was assumed for the plywood plants that claimed the number of process
units confidential. The plant-specific PM10 reduction associated with the PCWP standards was
calculated by summing the PM10 reductions for all process units. The nationwide PM10 reduction
was calculated by summing the reductions for each plant. Section 5.5 summarizes the estimated
nationwide PMj0 reduction.
5.1.2.2 NOX Emissions. As discussed in Chapter'3, NOX is formed when nitrogen (from
ambient air or fuel) is exposed the high temperatures in the presence of oxygen (i.e., through
combustion processes). Nitrogen oxides are present in the exhaust streams from PCWP process
units that incorporate combustion units (e.g., direct-fired dyers). Because RTO use combustion
to destroy pollutants, they may also generate some NOX.. The total amount of NOX emitted
includes the NOX emissions from the PCWP process unit plus the NOX generated in the RTO.
The NOX air impacts associated with the PCWP standards result from the increase in NOX
emissions across the RTO. Vendor literature indicates that the typical NOX increase across an
RTO can range up to 10 ppmv.7'9'10 The following equation was used to estimate the annual
increase in NOX (as NO2) for RTO:
NOX increase (ton/yr) = (8,000 hr/yr) x (10 ppm) x (ID"6) x (46.01 Ib NO2/lbmole) x
(dscfm) x (60 min/hr) / (385.3 ft3/lbmole ideal gas at 528°R) / (2000 Ib/ton)
The above equation was applied to estimate the NOX increase for each RTO expected to be
installed as a result of the PCWP standards. The plant-specific NOX increase was calculated by
summing the NOX increase for each RTO, and the nationwide NOX increase was calculated by
summing the plant-specific NOX increases. Section 5.5 summarizes the estimated nationwide
NOX increase associated with the use of RTO. The NOX emission estimates presented in Section
5.5 do not account for the baseline NOX emissions generated by PCWP process units.
: 5-7
-------
5.1.2.3 CO Emissions. By combusting process exhaust, RTO can either generate or
destroy emissions of CO depending on the process unit controlled. Whether there is a net
increase or decrease in CO across an RTO depends on the amount of CO entering the RTO.
Carbon monoxide is a product of incomplete combustion formed when there is not sufficient
time at high enough temperature to allow for complete oxidation of the CO to carbon dioxide
(CO2). Although combustion systems are designed to minimize formation of CO, a small
amount of CO will always be formed. Carbon monoxide is present in the exhaust from direct-
fired PCWP process units. As the exhausts from direct-fired process units enter an RTO, most of
the CO in the process exhaust is easily oxidized to CO2 under the RTO combustion temperatures.
For direct-fired process units, much more CO is destroyed than is formed in an RTO, resulting in
a net decrease in CO emissions. There is much less CO in the exhausts from indirect-heated
PCWP process units (e.g., veneer dryers, presses) than there is in the exhausts from direct-fired
process units. For indirect-heated PCWP process units, it appears that an RTO can form more
CO than it destroys, resulting in a net increase in CO emissions. Table 5-4 presents increases in
CO across RTO documented in vendor literature for veneer dryers and presses.
TABLE 5-4. CO INCREASES ACROSS RTO
Process unit
Veneer dryer
MDF press
OSB press
Increase in CO across RTO,
ppmv
30
3
11
Reference3
9
8
6
a See Section 5.6 for a list of references.
The following equation was used to estimate the annual increase in CO for RTO used to control
the sources listed in Table 5-4:
CO increase (ton/yr) = (8,000 hr/yr) x (ppm increase from Table 5-4) x (W6) x
(28 Ib CO/lbmole) x (dscfm) x (60 min/hr) / (385.3 ftVlbmole ideal gas at 528°R)
/ (2000 Ib/ton)
The CO concentration increase for MDF presses was also applied for particleboard presses
because particleboard presses operate at temperatures similar to those for MDF presses.
-------
Likewise, the OSB press CO concentration increase was also applied to hardboard presses
because hardboard presses operate at temperatures similar to OSB presses.
Table 5-5 presents several reported percent reductions in CO across RTO. Using the
information in Table 5-5, it was determined that RTO reduce CO emissions from direct-fired
dryers by 80 percent on average.
TABLE 5-5. PERCENT REDUCTION IN CO EMISSIONS
ACROSS DIRECT-FIRED DRYER RTO
Dryer type
OSB
OSB
OSB
OSB
OSB
OSB
' OSB
OSB
OSB
MDF
MDF
OSB
OSB
Average
% reduction
31
95
88
80
; 78
83
91
90
58
:' 88.3
80
95
88
80
Reference3
3
3
3
3
3
3
3
3
7
9
9
9
9
3 See Section 5.6 for a list of references.
Table 5-6 shows the calculated CO reductions for various types of process units. A CO
reduction was not estimated for conveyor-type strand dryers, hardboard ovens, or secondary tube
dryers because no information was available for estimating uncontrolled CO emissions from
these sources. For RTO that are shared by dryers and presses, the increase in CO associated with
the press exhaust was summed with the decrease in CO associated with the dryer exhaust.
Using a plant-by plant approach, the CO increases described above and the reductions
presented in Table 5-6 were applied to each process unit that would likely install an RTO to meet
5-9
-------
the PCWP standards. The nationwide change in CO emissions associated with the PCWP
standards was calculated as the total of the CO increases and reductions for all process units.
Section 5.5 summarizes the estimated nationwide change (net reduction) in CO emissions.
TABLE 5-6. CALCULATION OF CO REDUCTION ASSOCIATED WITH THE
PCWP STANDARDS FOR VARIOUS PROCESS UNITS
Process unit
MDF tube dryer
Hardboard tube dryer
OSB rotary dryers
Green particle rotary
dryer
Average
throughput*
87,000
58,000
65,000
70,000
Throughput
units
ODT/yr
ODT/yr
ODT/yr
ODT/yr
CO emission
factorb
0.11
0.067
5.4
3.5
Emission
factor units
Ib/ODT
Ib/ODT
Ib/ODT
Ib/ODT
Uncontrolled
CO(tpy)'
5
2
176
123
CO reduction
(tpy)d
3.8
1.6
140
98
" Average throughputs are documented in reference 1.
b Emission factors were selected for the types of units most commonly used for which emission factors were
available in reference 4.
c The uncontrolled CO emissions were calculated as follows: Uncontrolled CO = (average throughput) x (CO
emission factor) / 2000.
d The CO reduction was calculated as follows: CO reduction = uncontrolled CO x 0.8.
5.1.3 Secondary Air Impacts
Emissions of criteria air pollutants are produced from generation of the electricity
necessary to power control devices. The secondary air impacts associated with increased
electricity consumption were estimated. Energy Information Administration statistics indicate
that most of the existing U.S. electric utility capacity uses coal as the energy source.11 Therefore,
electricity was assumed to be generated at coal-fired utility plants built since 1978. Utility plants
built since 1978 are subject to'the new source performance standards (NSPS) in 40 CFR part 60,
subpart Da.12 The NSPS were used to estimate the SO2, PM10, and NOX (as NO2) emissions
from coal combustion. The CO emissions were estimated using an AP-42 emission factor
because CO emissions are not covered by the NSPS.13 The power plant thermal efficiency (i.e.,
the efficiency with which coal is converted into electricity) was taken to be one-third, based on a
typical value for fossil fuel power plants reported in literature.14 The heating value for
bituminous coal (the type of coal most commonly used for electricity generation) was"taken to be
12,750 Btu/lb coal, as fired.13-15
5-10
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The NSPS emission limits for coal-fired utilities for SO2, PM, and NOX (as NO2) are,
respectively, 1.20, 0.03, and 0.60 Ib pollutant per MMBtu heat input. (Note: Use of the NSPS
emission limit for PM overstates the secondary air pollutant emissions for PMJ0. According to
AP-42, PM10 is about 37 percent of the total PM.13) The following equation was used to
calculate the annual secondary air emissions of SO2, PM, and NOX:
EM = EL x 10-6 x E / TE x (3,415 Btu/kWh) / (2,000 Ib/ton)
where:
EM = emissions, tons per year
EL = NSPS emission limit, Ib pollutant per million Btu heat input (1.20 for SO2,0.03 for
PM, and 0.60 for NOX as NO2)
TE = thermal efficiency of power plant (33 percent)
E = plant-specific RTO and/or WESP electricity consumption calculated as described in
Section 5.4, kWh/yr
i
The following equation was used to calculate the annual secondary CO emissions:
EM = EF x E7 TE / (12,750 Btu/lb coal fired) x (3415 Btu/kWh) / (2,000 Ib/ton)2
where:
EM
EF
E
emissions, tons per year
0.5 Ib CO per ton coal fired
plant-specific RTO and/or WESP electricity consumption calculated as described in
Section 5.4, kWh/yr
The plant-specific secondary air impacts associated with the PCWP standards were
calculated by summing the impacts estimated for each RTO and/or WESP expected to be
installed at each plant. The nationwide secondary air impacts were calculated by summing the
plant-specific impacts. Section 5.5 summarizes the estimated nationwide secondary air impacts.
5.2 WASTEWATER IMPACTS
Potential wastewater impacts associated with the use of RTO and WESP include disposal
of the washwater generated during RTO washouts and disposal of WESP blowdown. The WESP
5-11
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blowdown is the fraction of the recirculated WESP water that is purged from the WESP system.
Wastewater impacts were based on use of RTO, although other control devices, such as
biofilters, are also sources of wastewater. The wastewater impacts for RTO and WESP were
estimated using information from the MACT survey responses and WESP vendor information.
Some facilities wash out RTO media beds to prevent buildup of particulates in the RTO.
Other facilities can remove the particulates with routine bakeouts of the RTO beds without
having to perform periodic washouts. The amount of wastewater generated during washout of an
RTO depends on the size of the RTO and the extent of the paniculate buildup. The MACT
survey responses contain information on the frequency of RTO washouts and the amount of
wastewater generated during the washouts. This information was used to determine the annual
wastewater used by plants that perform washouts. Table 5-7 summarizes the annual wastewater
generation rates for different process units.16
TABLE 5-7. ANNUAL WASTEWATER GENERATION RATES
FOR RTO WASHOUTS16
Process unit
Rotary dryers (particle or strand)
Particleboard and OSB presses
Multiple hardboard process units
Average from all MACT survey responses that
included information for RTQ washwater volume
Annual RTO washwater
generated, gal/yr
39,000
15,000
21,000
32,000
To approximate the annual amount of wastewater generated during washing out of RTO,
it was assumed that washouts would be performed on all RTO. The average annual wastewater
generation rates were applied according to the process units controlled by each RTO. If the RTO
would control emissions from both a rotary dryer and a press, then the rotary dryer washwater
amount (39,000 gpy) was applied. For RTO on sources for which no average waste water
generation rate was available (e.g., veneer dryers or MDF process units), the industry average
(32,000 gal/yr) was applied.
The annual amount of WESP blowdown was determined based on the 1-gpm blowdown
system described by the WESP vendor that supplied inputs for the cost algorithm described in
5-12
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Chapter 4, Section 4.1.2.1. Using 8,000 hr/yr, a 1-gpm blowdown system would produce
480,000 gal/yr wastewater. This wastewater is typically routed to a settling pond for solids
removal and is disposed of by evaporation or spray irrigation or is sent to a municipal wastewater
treatment plant. Because OSB mills are generally designated as zero discharge facilities, they
must treat their own spray water and/or consume it internally. Mills that operate boilers or other
wet cell burners can apply some of the spent spray water to the fuel. Some or all of the
remaining spray water may be used as makeup water in hot ponds or in debarkers for dust
control.3
The total amount of wastewater expected to be generated by each plant as a result of the
PCWP standards was calculated as the sum of the wastewater generated from each control
device. The nationwide wastewater impacts were calculated by summing the wastewater impacts
for each plant. Section 5.5 summarizes the nationwide wastewater impacts.
5.3 SOLED WASTE IMPACTS . ' .
Potential solid waste impacts associated with the use of RTO and WESP include disposal
of the RTO packing media and disposal of WESP wastewater solids or sludge. The solid waste
impacts were estimated for RTO and WESP using information from the MACT survey responses
and State permits.
The responses to EPA's MACT survey from plants operating RTO indicate that RTO
packing media is typically replaced after j to 4 years of use. The packing media is generally
disposed of in a landfill or is reused on the plant site (e.g., as aggregate in roadbeds).16 For
purposes of estimating RTQ solid waste impacts, it was assumed that the RTO packing media
would be replaced every 2 years. No information on the volume or mass of RTO packing media
was requested in the EPA's MACT survey. Therefore, the mass of RTO media to be replaced
was approximated based on drawings of an RTO in a State permit. The RTO described in the
permit has 47,322 scfm cylindrical towers that are 12-ft high with an 11-ft inside diameter. Thus,
the volume of each tower is 1,140 ft3.17 Ceramic saddles are commonly used as RTO packing
media. The weight of 1 to 1-1/2-inch ceramic saddles is about 40 lb/ft3.18 Thus, a factor relating
mass of RTO media to RTO flow was developed as follows:
(1,140 ft3/47,322 scfm) x (40 lb/ft3) x (ton/2,000 Ib) = 4.82E-04 tons packing media/scfm
5-13
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This factor was divided by 2 (because media replacement was assumed to occur every 2 years)
and applied to each RTO to approximate the annual mass of RTO media to be disposed.
The mass of WESP solids to be disposed was estimated as described in Chapter 4,
Section 4.1.2.2. As described in Section 4.1.2.2, the wastewater percent solids was assumed to
be 7.6 percent (by volume) based on the average from the MACT survey responses. The density
of the solids was assumed to be 0.5 ton/yd3. For a 1-gpm blowdown system, the mass of WESP
solids generated was estimated as follows:
(1 gal/min) x (60 min/hr) x (8,000 hr/yr) x (0.076 volume % solids) /
(7.481 gatfft3) / (27 ft3/yd3) x (0.5 ton/yd3) = 90 tons solids/year
Thus, for each WESP likely to be installed on a rotary strand dryer as a result of the PCWP
standards, it was assumed that 90 tons;of solids per year would require disposal. It was assumed
that the solids would ultimately be disposed of in a landfill (although they could be burned onsite
or used for soil amendment).
The plant-specific amount of solid waste expected to be generated as a result of the
PCWP standards was calculated as the sum of the solid waste generated from each RTO or
WESP/ The nationwide solid waste impacts were calculated by summing the solid waste impacts
for each plant. Section 5.5 summarizes the nationwide solid waste impacts.
5.4 ENERGY IMPACTS '
Energy impacts associated with the PCWP rulemaking include fuel and electricity use by
control devices such as RTO or WESP. Natural gas is the most common fuel used in RTO. The
RTO natural gas and electricity consumption was determined using the relationships presented in
Figures 4-3 and 4-4 in Chapter 4, Section 4.1.1.2 and assuming 8,000 hr/yr of operation. The
relationships were applied to each of the RTO likely to be installed as a result of the PCWP
standards. The annual WESP electricity consumption (2,076,000 kWh/yr) presented in
Section 4.1.2.2 was used for each WESP to be installed. The control .device energy consumption
was totaled for each plant, and the plant totals were summed to calculate the nationwide energy
impacts associated with the PCWP standards. Section 5.5 summarizes the nationwide energy
impacts.
5-14
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5.5 SUMMARY OF NATIONWIDE ENVIRONMENTAL AND ENERGY IMPACTS
Table 5-8 summarizes the nationwide reduction in total HAP and THC estimated to result
from the PCWP standards at the MACT floor control level. Table 5-9 summarizes the
nationwide change in emissions of primary criteria air pollutants and the secondary air impacts
associated with the MACT floor control level. Table 5-10 summarizes the nationwide
wastewater and solid waste impacts, and Table 5-11 summarizes the nationwide energy impacts.
Each of the tables present the nationwide environmental and energy impacts by product type.
See Table 4-4 in Chapter 4, Section 4.1.5 for a summary of the number of plants, number of
plants impacted, and process units controlled for each product type.
5-15
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TABLE 5-10. ESTIMATED NATIONWIDE SOLID WASTE
AND WASTEWATER IMPACTS
Product type
Softwood plywood/veneer
Bardwood plywood/veneer
Medium density fiberboard
Oriented strandboard
Particleboard
(molded and conventional)
Particleboard (agriboard)
Hardboard
Fiberboard
Engineered wood products
TOTAL
Solid Waste Impacts (ton/yr)
RTO media
589
0"
719
740
1,096
Ob
779
0"
72
3,995
WESP wastewater
solids"
NA
Ob
NA
810
NA
Ob
NA
Ob
180
990
Wastewater Impacts (1,000 gal/yr)
RT<) washwater
2,112
Ob
832
768
1,677
Ob
630
Ob
156
6,175
WESP blowdown"
NA
Ob
NA
4,320
NA
Ob
NA
Ob
960
5,280
" WESP wastewater solids and blowdown are only estimated for plants with rotary strand dryers (i.e., OSB and
engineered wood products plants)
b There is no impact because no plants are impacted by the PCWP standards at the MACT floor control level.
TABLE 5-11. ESTIMATED NATIONWIDE ENERGY IMPACTS
'roduct type
Softwood plywood/veneer
Hardwood plywood/veneer
Medium density fiberboard
Oriented strandboard
Particleboard
(molded and conventional)
Particleboard (agriboard)
Hardboard
Fiberboard
Engineered wood products
TOTAL"
RTO natural gas
comsumption
(Billion Btu/yr)
; 175
i oc
1 346
269
434
oc
385
Oc
29
1,638
RTO electricity
consumption
(GWh/yr)
103
Oc
125
129
191
Oc
135
Oc
13
695
WESP electricity '
consumption
(GWh/yr)b
NA
Oc
NA
19
NA
Oc
NA
Oc
4
23
Totals may not sum exactly due to rounding.
WESP electricity consumption is only estimated for plants with rotary strand dryers (i.e., OSB and engineered
wood products plants).
There is no impact because no plants are impacted by the PCWP standards at the MACT floor control level.
.5-18
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5.6 REFERENCES FOR CHAPTER 5
1. Memorandum from K. Hanks and D. Bullock, MRI, to M. Kissell, EPA/ESD. June 9,
2000. Baseline Emission Estiniates for the Plywood and Composite Wood Products
Industry. '.
2. Memorandum from B. Nicholson arid K. Hanks, MRI, to M. Kissell, EPA/ESD. July 13,
2000. Determination of MACT floors and MACT for the Plywood and Composite Wood
Products Industry.
3. Emission Factor Documentation for.AP-42 Section 10.6.1, Waferboard/Oriented
Straridboard Manufacturing. Prepared for the U. S. Environmental Protection Agency,
OAQPS/EFIG, by Midwest Research Institute. Gary, NC. December 1998.
4. Memorandum from D. Bullock and K. Hanks, MRI, to M. Kissell, EPA/ESD. April 27,
2000. Documentation of Emission Factor Development for the Plywood and Composite
Wood Products Manufacturing NESHAP.
5. Report for 1996 PM10 Emission Measurements for Emission Reduction Credits, SierraPine,
Ltd., Rocklin, CA, Test Dates November 19-26, 1996. Prepared for SterraPine, Ltd., by
Carnot. April 1997.
6. Emission Factor Documentation for AP-42 Section 10.6.2, Particleboard Manufacturing.
Prepared for the U. S. Environmental Protection Agency, OAQPS/EFIG, by Midwest
Research Institute. Gary, NC. September 1998.
7. Smith Environmental Corporation. Environmental Newsletter for the Wood Industry.
August 1994.
8. Air Permit Application Review/Preliminary Determination for Hominant USA,
Incorporated thin high density fiberboard (THDF) greenfield facility in Mount Gilead, NC.
Application No. 6200061.99A. March'6, 2000.
9. Smith Engineering Corporation. Wood Industry Environmental Newsletter. March 1994.
10. R. Grzanka, REECO. An Engineered Solution for Fugitive Emissions Control from Three
Veneer Dryers at a Plywood Plant. Undated.
11. Energy Information Administration, Form EIA-860A. Annual Electric Generator Report -
Utility.
12. 40CFRPart60. SubpartDa.
5-19
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13. Compilation of Air Pollutant Emission Factors, AP-42, 5th Edition, Supplement E. U. S.
Environmental Protection Agency. Research Triangle Park, NC. Volume I: Stationary
Point and Area Sources. Section 1.1: Bituminous and Subbituminous Coal Combustion.
September 1998.
14. Carbon Dioxide Emissions from the Generation of Electric Power in the United States.
Washington, DC, U.S. Department of Energy and U. S. Environmental Protection Agency,
Washington, D.C. October 15,1999.
15. R.H. Perry and D.W. Green, Eds. Perry's Chemical Engineers' Handbook. 6th Edition.
New York, McGraw-Hill. 1984. pp. 9-18.
16. Memorandum from D. Bullock, K. Hanks, and B. Nicholson, MRI, to M. Kissell,
EPA/ESD. April 28, 2000. Summary of Responses to the 1998 EPA Information
Collection Request (MACT Survey) - General Survey.
17. Letter from C. Parham, J.M. Huber Corporation, to E. Cornwell, Georgia Department of
Natural Resources, Environmental Protection Division, Air Protection Branch.
February 23,1996. Permit Application for the RTO on the Board Press Exhaust - Permit
No. 2493-078-10583. I
18. Rauschert Process Technologies. Webpage for ceramic tower packing:
http://208.24.91.247/process_technologies/stpk.html, May 15, 2000.
5-20
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TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing
1. REPORT NO.
EPA-453/R-01-004
__i_.
41 TITLE AND SUBTITLE
Background Information Document for Proposed Plywood and
Composite Wood Products NESHAP
7. AUTHOR(S)
Mary Tom Kissell (EPA), Katie Hanks (MRI), Becky Nicholson
(MRI), David Bullock (MRI) , _
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. EPA/OAQPS/ESD
Research Triangle Park, NC 27711
I i 12 SPONSORING AGENCY NAME AND ADDRESS
I;1*.-!
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
3. RECIPIENT'S ACCESSION NO.
. REPORT DATE
September 2000
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-D6-0012
13. TYPE OF REPORT AND PERIOD COVERED
14 SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
r
sup^tog memZT Section 12 describes the information sources used to develop ttas document and
introduces the additional supporting memoranda. - -
KEY WORDS AND DOCUMENT ANALYSIS
h. IDENTIFIP-RS/OPEN ENDED TERMS
c. COSATI Field/Group
-------
Proposed Rule - Clean Air
Plywood and Composite Wood Products
IS, DISTRIBUTION STATEMENT
Release Unlimited
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
Air Pollution control,
particleboard, oriented strandboard
(OSB), medium density fiberboard
(MDF), fiberboard, hardboard,
softwood plywood, softwood
veneer, hardwood plywood,
hardwood veneer, laminated veneer
lumber (LVL), laminated strand
lumber (LSL), parallel strand
lumber (PSL), wood I-joists, glue-
laminated beams, engineered wood
iroducts, hazardous air pollutants
19. SECURITY CLASS (Report)
Unclassified
20. SECURITY CLASS (Page)
Unclassified
21. NO. OF PAGES
74 pages
22. PRICE
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