United States Office of Air Quality EPA-450 '2-78-029
Environmental Protection Planning and Standards OAQPS No 1.2-105
^gencv Research Triangle Park NC 27711 December 1978
OAQPS Guideline
Series
Control of Volatile
Organic Emissions
from Manufacture
of Synthesized
Pharmaceutical Products
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TECHNICAL REPORT DATA
(Phase read Instructions on the reverse before completing1
1. RE»ORT *0. 2.
EPA-450/2-7S-029
3. RE
4. TiTuE and Subtitle
Control of Volatile Organic Emissions from
Manufacture of Synthesized Pharmaceutical Products
5. REPORT DATE
December 1978
6. PERFORMING ORGANIZATION CODE
7 AUTHORiSi
David A. Beck, ESED Karl Zobel, ESED
Leslie B. Evans, ESED PEDCo Environmental, Inc.
B. PERFORMING ORGANIZATION REPORT NO.
OAQPS No. 1.2-105
9 PERFORMING ORGANIZATION name and address
U.S. Environmental Protection Agency
Office of Air, Noise and Radiation
' Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above.
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report provides the necessary guidance for development of regulations
to limit emissions of volatile organic compounds (VOC) from manufacture of
synthesized pharmaceutical products. The report includes a characterization
of manufacturing operations, emissions from these operations, applicable controls
and costs of controls. General emission control guidelines are provided which
represent application of reasonably available control technology (RACT).
17. KEY WORDS AND DOCUMENT ANALYSIS
i. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. cosati Field/Group
Air Pollution
Volatile Organic Compounds
Pharmaceutical Manufacturing
Air Pollution Control
Stationary Sources
Volatile Organic Emission
5
18. DISTRIBUTION STATEMENT
Unlimited
IS SECURITY CLASS (Thii Report)
Unclassified
21. • - r.r rA'. EG
; \iU
30. SECURITY CLASS (Thisprngr)
Unclassified
22. PRICE pc fill
mP
EPa 2320*1 (R*«. 4*77) pwcv>ou* coition is oiioleti
I
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EPA-450/2-78-029
OAQPS No. 1.2-105
Control of Volatile Organic Emissions
from Manufacture of Synthesized
Pharmaceutical Products
Emission Standards and Engineering Division
Chemical and Petroleum Branch
U S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1978
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6
OAQPS GUIDELINE SERIES
The guideline series of reports is being issued by the Office of Air Quality Planning and Standards (OAQPS) to
provide information to state and local air pollution control agencies; for example, to provide guidance on the
acquisition and processing of air quality data and on the planning and analysis requisite for the maintenance of air
quality. Reports published in this series will be available - as supplies permit - from the Library Services Office
(MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, or, for a nominal
fee, from the National Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22161.
Publication No. EPA-450/2-78-029
(OAQPS Guideline No. 1.2-105)
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PREFACE
This is one in a series of reports which provide guidance on air pollution
control techniques for limiting emissions of volatile organic compounds (VOC) from
existing sources in specific industries. These reports are designed to assist
States in the development of air pollution control regulations for VOC wnich
contribute to the formation of photochemical oxidants. This report deals with
volatile organic emissions from the production of synthesized pharmaceutical
products.
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ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements in agency documents in metric
units. Listed below are abbreviations and conversion factors for British
equivalents of metric units for the use of engineers and scientists accustomed
to using the British system.
Abbreviations
Mg - Megagrams
kg - kilograms
- cubic meters
Conversion Factors
liters X .264 = gallons
gallon X 3.785 = liters
gram X 1 X 10® = 1 Megagram = 1 metric ton
1 pound = 0.454 kilograms
°C = .5555 (°F - 32)
Mg/yr X 0.907 = tons/yr
1 psi = 6,895 pascals (Pa)
ii
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TABLE OF CONTENTS
PREFACE
ABBREVIATIONS AND CONVERSION FACTORS
1.1 INTRODUCTION AND SUMMARY. . .
1.1 INDUSTRY CHARACTERIZAT10h
1.2 NEED TO REGULATE . . .
1.3 SOURCES AND CONTROL OF VOLATILE ORGANIC COMPOUNDS
FROM MANUFACTURE OF SYNTHESIZED PHARMACEUTICAL °ROD'JCTS .
2.0 PLANT CHARACTERIZATION AND REGULATORY APPROACH . . .
2.1 SYNTHESIZED PHARMACEUTICAL MANUFACTURING PLANTS
2.2 REGULATORY APPROACH ....
3.0 EMISSION SOURCES AND APPLICABLE SYSTEMS
REDUCTION . . .
3.1 REACTORS
3.1.1 Reactor Description and
3.1.2 Reactor Emissions
3.1.3 Control Technology .
3.2 DISTILLATION UNITS ....
3.2.1 Distillation Operations
3.2.2 Distillation Emissions
3.2.3 Control Technology .
3.3 SEPARATION OPERATIONS . . .
3.3.1 Extraction ....
3.3.2 Extraction Emissions
3.3.3 Centrifugation Description
3.3.4 Centrifuge Emissions . .
OF EMISSION
Operation
m
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Page
3.3.5 Filter Descriptions 3-10
3.3.6 Filter Emissions 3-10
3.3.7 Crystallization Operations .... 3-11
3.3.8 Crystallization Emissions 3-11
3.3.9 Separation Operations Control
Technology .......... . ~. . 3-12
3.4 DRYERS ....... i ! i | . . ! . ! | . 3-13
3.4.1 Dryer Description and Operation 3-13
3.4.2 Dryer Emissions 3-14
3.4.3 Control Technology 3-14
3.5 STORAGE AND TRANSFER 3-16
3.5.1 Storage and Transfer Description 3-16
3.5.2 Storage and Transfer Emissions 3-16
3.5.3 Control Technology 3-21
3.6 REFERENCES . . . 3-25
4.0 PERFORMANCE OF CONTROL SYSTEMS 4-1
4.1 CONDENSATION 4-1
4.1.1 Condenser Performance 4-2
4.1.2 Applicability. 4-6
4.2 SCRUBBERS OR ABSORBERS 4-7
4.2.1 Control Performance 4-7
4.2.2 Applicability 4-8
4.3 CARBON ADSORPTION • ••~••»•••••••••••••• 4—9
4.3.1 Control Performance 4-9
4.3.2 Applicability 4-11
4.4 INCINERATION. 4-11
4.4.1 Control Performance 4-12
iv
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Page
4.4.2 Applicability 4-14
4.5 REFERENCES 4~16
5.0 COST ANALYSIS 5-1
5.1 INTRODUCTION 5-1
5.1.1 Purpose 5-1
5.1.2 Scope 5-1
5.1.3 Bases for Capital Cost Estimates 5-3
5.1.4 Bases for Annualized Costs 5-3
5.2 VOC EMISSION CONTROL IN PHARMACEUTICAL OPERATIONS .... 5-6
5.2.1 Plant Parameters 5-6
5.2.2 Capital Costs for VOC Emission Controls ...... 5-6
5.2.3 Annualized Costs of VOC Emission Controls 5-9
5.3 COST-EFFECTIVENESS 5-12
6.0 ADVERSE EFFECTS OF APPLYING THE CONTROL TECHNOLOGY 6-1
6.1 CONDENSATION . 6-1
6.2 SCRUBBING 6-1
6.3 ADSORPTION 6-2
6.4 INCINERATION 6-4
6.5 REFERENCES 6-6
7.0 COMPLIANCE TESTING METHODS AND MONITORING
TECHNIQUES. 7-1
7.1 OBSERVATION OF CONTROL EQUIPMENT AND
OPERATING PRACTICES 7-1
7.1.1 Adsorption 7-1
7.1.2 Condensation 7-1
7.1.3 Incineration 7-2
7.1.4 Scrubbing 7-2
7.2 EMISSION TESTS 7-2
v
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APPENDIX A - TABULAR PRESENTATION OF SOLVENT DISPOSITION
DATA SUBMITTED BY THE PHARMACEUTICAL MANUFACTURERS
ASSOCIATION . A-l
APPENDIX 8 - EQUATIONS FOR ESTIMATING EMISSION RATES FROM PROCESS
EQUIPMENT B-l
APPENDIX C - AIDS TO CALCULATING STORAGE TANK EMISSIONS C-l
vi
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1.0 INTRODUCTION AND SUMMARY
This report is intended to assist State and local air pollution control
agencies develop regulations to reduce emissions of volatile organic compounds
(VOC) from existing sources within the pharmaceutical industry. Methodology
described in this document represents the presumptive norm or reasonably availabl
control technology (RACT) that can be applied to existing plants synthesizing
pharmaceutical products. RACT is defined as the lowest emission limit that a
particular source is capable of meeting by the application of control technology
that is reasonably available considering technological and economic feasibility.
It may require technology that has been applied to similar, but not necessarily
identical, source categories. It is not intended that extensive research and
development be conducted before a given control technology can be applied to the
source. This does not, however, preclude requiring a short-term evaluation progr
to permit the application of a given technology to a particular source. This
latter effort is an appropriate technology-forcing aspect of RACT.
1.1 INDUSTRY CHARACTERIZATION
Production activities of the pharmaceutical industry can be divided into
the following categories:
1. Chemical Synthesis - The manufacture of pharmaceutical products
by chemical synthesis.
2. Fermentation - The production and separation of medicinal chemicals
such as antibiotics and vitamins from microorganisms.
1-1
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3, Extraction - The manufacture of botanical and biological products
by the extraction of organic chemicals from vegetative materials or animal
tissues.
4. Formulation and Packaging - The formulation of bulk pharmaceuticals
into various dosage forms such as tablets, capsules, injectable solutions,
ointments, etc, that can be taken by the patient immediately and in
accurate amount.
There are approximately 800 pharmaceutical plants producing drugs
in the United States and its territories. Five States have nearly 50 perceni
of all plants: New York, 12 percent; California, 12; New Jersey, 10;
Illinois, 5; and Pennsylvania, 6. These States also contain the largest
plants in the industry. Puerto Rico has had the greatest growth in the
past 15 years, during which 40 plants have located there; it now contains
90 plants or about 7.5 percent of the total. Most pharmaceutical plants
are small and have less than 25 employees. EPA's Region II (New Jersey,
New York, Puerto Rico, Virgin Islands) has 340 plants (28 percent of the
total); Region V (Illinois, Minnesota, Michigan, Ohio, Indiana, Wisconsin)
215 plants (20 percent); and Region IX (Arizona, California, Hawaii, Guam,
American Samoa) 143 plants (13 percent).
1-2
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1.2 NEED TO REGULATE
The pharmaceutical industry uses many volatile organic compounds either
as raw materials or as solvents. The Pharmaceutical Manufacturers Association
(PMA) obtained estimates from 26 member companies of the ten largest volume
volatile organic compounds that each company purchased and the mechanism by
which they leave the plant, i.e., sold as product, sent to the sewer, or
emitted as an air pollutant. Twenty-five of the 26 reporting companies indicat
that their ten largest volume solvents accounted for 80 to 100 percent of their
VOC purchases. (The other company said only 50 percent of their purchases
were represented by their ten high VOC.) Overall, PMA estimates that these
26 reporting companies identified 85-90 percent of the total VOC's they used.
These companies represented 53 percent of the domestic sales of ethical
pharmaceuticals in 1975.* The results of the industry's estimates (which
were developed by material balance and are not measured values) are presented
in Appendix A, Table A-l.
According to the data submitted by pharmaceutical manufacturers, about
73 percent of all emissions reported by the industry are from the division
referred to as "Synthesized Pharmaceutical Products" and only it is covered
in this guideline.
1.3 SOURCES AND CONTROL OF VOLATILE ORGANIC COMPOUNDS FROM MANUFACTURE OF
SYNTHESIZED PHARMACEUTICAL PRODUCTS
Synthesized pharmaceuticals are normally manufactured in a series of
batch operations according to the following sequence: (a) reaction (sometimes
more than one), (b) product separation, (c) purification, and (d) drying.
*Drugs are marketed in two categories, ethical and proprietary. Ethical drugs
can be purchased only by prescription whereas proprietary drugs can be purchase
"over the counter."
1-3
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Each operation of the series may be a source of VOC emissions. The magnitude
of emissions varies widely within and among operation categories and depends
on the amount and type of VOC used, the type of equipment performing the
operation, and the frequency of performing the operation. The wide variation
prevents calculating typical emission rates for each operation; however, an
approximate ranking of emission sources has been established and is presented
below in order of decreasing emission significance. The first four sources
generally will account for the majority of emissions from a plant.
1. Dryers
2. Reactors
3. Distillation units
4. Storage and transfer
5. Filters
6. Extractors
7. Centrifuges
8. Crystallizers
Applicable controls for all the above emission sources except storage
and transfer are: condensers, scrubbers, and carbon adsorbers. Incinerators
are expected to have limited application but may be useful for certain
situations. Storage and transfer emissions can be controlled by vapor return
lines, vent condensers, conservation vents, vent scrubbers, pressure tanks,
and carbon adsorbers. Floating roofs may be feasible controls for large,
vertical storage tanks. Emission reduction efficiencies for these controls
are discussed in Chapter 4.
Since many of these individual vents are likely to be small in any given
plant, it may often be reasonable to regulate on a plant by plant basis.
1-4
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This approach involves determining which synthesized pharmaceutical
manufacturing facilities emit large amounts of VOC and within such plants
which operations are significant sources. Control requirements would then
be imposed after considering local air quality, the mass rate of emissions,
control cost estimates, and plant safety effects. Further information is
given in Chapter 2 and Appendix B for determining emissions from various
operations and equipment.
Where this approach is not practical, the following guidelines will
serve as a generalized control program:
1. (a) For each vent from reactors, distillation operations, crystallizers,
centrifuges, and vacuum dryers that emit 6.8 kg/day (15 lb/day) or more of
VOC, require surface condensers or equivalent controls.
(b) If surface condensers are used, the condenser outlet gas temperature
should not exceed:
(i) -25°C when condensing VOC of vapor pressure greater than
40 kPa (5.8 psi),*
(ii) -15°C when condensing VOC of vapor pressure greater than
20 kPa (2.9 psi),*
(iii) 0°C when condensing VOC of vapor pressure greater than
10 kPa (1.5 psi),*
(iv) 10°C when condensing VOC of vapor pressure greater than
7 kPa (1.0 psi),* and
(v) 25°C when condensing VOC of vapor pressure greater than
3.5 kPa (0.5 psi).*
(c) Equivalent control results when emissions are reduced at least
as much as they would have been by using a surface condenser according to
Kb).
*vapor pressures as measured at 20°C
1-5
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2. (a) For air dryers and production equipment exhaust systems that emit
150 kg/day (330 lbs/day) or more of VOC, require 90 percent emission reduction.
(b) For air dryers and production equipment exhaust systems that emit
less than 150 kg/day (330 lbs/day), require emission reduction to 15 kg/day
(33 lbs/day).
3. (a) For storage tanks storing VOC with a vapor pressure greater than
28 kPa (4.1 psi) at 20°C, allow one liter of displaced vapor to be released to
the atmosphere for every ten liters transferred (i.e., a 90 percent effective
vapor balance or equivalent), on truck/rail car delivery, to all tanks greater
than 7,500 liters (2000 gallons) capacity except where tanks are equipped with
floating roofs, vapor recovery, or equivalent. This guideline does not apply
to transfer of VOC from one in-plant location to another.
(b) For tanks storing VOC with a vapor pressure greater than 10 kPa
(1.5 psi) at 20°C, require pressure/vacuum conservation vents set at +_ 0.2 kPa,
except where more effective air pollution control is used.
4. Enclose all centrifuges containing VOC, rotary vacuum filters
processing liquid containing VOC; and any other filters having an exposed
liquid surface where the liquid contains VOC. This applies to liquids
exerting a total VOC vapor pressure of 3.5 kPa (0.5 psi) or more at 20°C.
5. All in-process tanks shall have covers. Covers should be closed
when possible.
6. For liquids containing VOC, all leaks in which liquid can be
observed to be running or dripping from vessels and equipment (for example:
pumps, valves, flanges) should be repaired as soon as is practical.
1-6
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2.0 PLANT CHARACTERIZATION AND
REGULATORY APPROACH
2.1 SYNTHESIZED PHARMACEUTICAL MANUFACTURING PLANTS
The synthesis of medicinal chemicals may be done in a very small facility
producing only one chemical or in a large integrated facility producing nany
chemicals by various processes. Most of the estimated 1200 plants are relatively
small. Organic chemicals are used as raw materials and as solvents, and solvents
constitute the predominant VOC emission from production. Plants differ in the
amount of organics used; this results in widely varying VOC emission rates.
Therefore, some plants may be negligible VOC sources while others are highly
significant.
Nearly all products are made using batch operations. In addition, several
different products or intermediates are likely to be made in the same equipment
at different times during the year; these products, then, are made in
"campaigned" equipment. Equipment dedicated to the manufacture of a single product
is rare, unless the product is made in large volume.
Basically, production of a synthesized drug consists of one or more chemical
reactions followed by a series of purifying operations. Production lines may
contain reactors, filters, centrifuges, stills, dryers, process tanks, and
crystallizers piped together in a specific arrangement. Arrangements can be
varied in some instances to accommodate production of several compounds. A
very small plant may have only a few pieces of process equipment but a large
plant can contain literally hundreds of pieces, many of which are potential VOC
emission sources.
2-1
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Figure 2-1 shows a typical flow diagram for a batch synthesis operation.
To begin a production cycle, the reactor may be water washed and perhaps
dried with a solvent. Air or nitrogen is usually used to purge the tank
after it is cleaned. In this example, solid reactants and solvent are
charged to a 3,785 liter glass batch reactor equipped with a condenser
(which is usually water-cooled). Still other volatile compounds may be
produced as product or by-products. Any remaining unreacted VOC is
distilled off. After the reaction and solvent removal are complete,
the pharmaceutical product is transferred to a holding tank. After each
batch is placed in the holding tank, three to four washes of water or
solvent may be used to remove any remaining reactants and by-products.
The solvent used to wash may also be evaporated from the reaction product.
The crude product may then be dissolved in another solvent and transferred
to a crystallizer for purification. After crystallization, the solid
material is separated from the remaining solvent by centrifugation.
While in the centrifuge, the product cake may be washed several times
with water or solvent. Tray, rotary, or fluid-bed dryers may then be
employed for final product finishing.
2.2 REGULATORY APPROACH
The plant characterization in the preceding section reveals the complexities
of synthesized pharmaceutical manufacture. Each plant is unique, differing
from other plants in size, types of products manufactured, amounts and types
of VOC used, and air pollution control problems encountered. The dissimilarities
make it impossible to define typical emission levels or emission factors for an
average plant. This in turn prevents identifying in this document which sources
definitely need to be controlled and how much overall emission reduction can be
effected.
2-2
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ro
i
UJ
Solids
Solvent
Vent
1
V,ent
Vent
4
Solvent Solvent
H2°
Solvent Vent
Reactw1
Holding
Tank^
Solvent i
Distil lot|op|
Crystallize}
Typical Cycle 1 / 24 hours
Batch
Centrifuge
h2o
Solvent
Product
Figure 2-1 Typical Synthetic Organic Medicinal Chemical Process
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With this in mind, it appears that a reasonable approach to regulation is to
investigate emission levels and control options for a given plant on a plant by
plant basis. The individual investigations would be begun by first determining
which plants are significant VOC emitters and within such plants which process
emission points are largest.
Emission data for pharmaceutical plants are scarce. Therefore, emission
estimates will have to be obtained through other means. One way is to have
plants submit solvent purchase and use information similar to that tabulated in
Appendix A. The information in the Appendix resulted from a survey of
26 pharmaceutical manufacturers concerning amounts and types of VOC used and the
ultimate disposition for each. As shown in the tables, estimates for air emissions
were provided. It is acknowledged that these are only material balance estimates;
nonetheless, they should be of sufficient accuracy to answer the question of
whether or not the plant is a significant source.
Plants concluded to be significant VOC emitters would be candidates for a control
program. The next step is to account for the bulk of total plant emissions by
determining emissions from individual pieces of process equipment. Common methods
are sampling and analysis of vent streams, material balance, and theoretical
calculation. Many vents are neither easily nor inexpensively sampled, and
in some instances material balances will not be satisfactory. Therefore, theoretical
evaluations may have to be conducted. Equations are presented in Appendix B that
will aid in calculating potential emissions from process operations. Because
of the assumptions underlying the equations, calculated values will tend to
represent maximum possible emissions from an operation.
Especially in larger plants, attempts to sample, perform material balances,
or calculate emissions from all plant vents would be an expensive and time
consuming task. It would be better to concentrate on the larger vents, which are
2-4
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the most likely to be controlled anyway. Plant personnel may be able to indicate
the major emission points. By using the limited emission data accumulated for
this document, a ranking has been established to illustrate relative expected
VOC emissions from process sources. The ranking is presented below in order of
decreasing relative emissions.
1. Dryers
2. Reactors
3. Distillation systems
4. Storage tanks and transfer operations
5. Filters
6. Extractors
7. Centrifuges
8. Crystallizers
The list is not intended to represent every plant; a single list could not
possibly fit all situations. It is intended to convey that for many plants, emissions
from dryers will be the largest source of VOC emissions, reactors the second
largest, and so on. For most plants, the first four listed process sources will
account for the great majority of total plant VOC emissions. However, this does
not preclude the last four from being significant emitters.
Once the emission profile for a plant is established, this document can be
used to select control measures or emission limits for the major emission points.
Information is provided in Chapters 3-5 concerning control system application,
performance, and costs. The decision to require control of specific exhaust streams
will be determined based on local air quality, the mass emission rate of volatile
organics, and the cost to the operator to control the streams.
2-5
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3.0 EMISSION SOURCES AND APPLICABLE
SYSTEMS OF EMISSION REDUCTION
Compounds typically emitted during pharmaceutical manufacture are listed
in the tables in Appendix A. The list is not exhaustive but does account for
the great majority of VOC emissions from plants reporting. These compounds
are commonly used as solvents, although at times they may be used as raw
materials. Emissions of VOC's formed during reaction are estimated
to contribute only a small fraction to total emissions.
Volatile organic compounds may be emitted from a variety of sources within
plants synthesizing pharmaceutical products. Because of the number of sources,
the discussion of emissions and applicable controls is organized by process component
The following process components have been identified as VOC sources and are
discussed in this chapter: reactors, distillation units, dryers, crystallizers,
filters, centrifuges, extractors, and tanks.
3.1 REACTORS
3.1.1 Reactor Description and Operation
The typical batch reactor is glass lined or stainless steel and has a capacity
of 2,000 to 11,000 liters (500-3000 gallons). For maximum flexibility, the tanks
are usually jacketed to permit temperature control of reactions. Generally,
each is equipped with a vent which may discharge through a condenser. They can
be operated at atmospheric pressure, elevated pressure, or under vacuum. Because
of their flexibility, reactors may be used in a variety of ways. Besides hosting
chemical reactions, they can act as mixers, heaters, holding tanks, crystallizers,
and evaporators.
3-1
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Like almost all equipment in the pharmaceutical industry, reactors are
used on a batch basis and may be used to produce several different products
during a year. When changing from one product to another, special care must be
taken in cleaning the equipment. Cleaning procedures vary. Sometimes a
detergent and water wash is followed by a solvent wash (to aid in drying).
Often, a solvent wash alone is sufficient. One procedure is to add the
cleaning solution, raise the reactor temperature (to improve the cleaning
efficiency), and then agitate or circulate the mixture. The vessel is then
drained, flushed with solvent (or water), and dried by raising the temperature
again.
A typical reaction cycle takes place as follows. After the reactor is
clean and dry, the appropriate raw materials, usually including some solvent(s),
are charged for the next product run. Liquids are normally added first, then
solid reactants are charged through the manhole. After charging is complete,
the vessel is closed and the temperature raised if necessary via reactor jacket
heating. The purpose of heating may be to increase the speed of reaction or to
reflux the contents for a period which may vary from 15 minutes to 24 hours.
During refluxing, the liquid phase may be "blanketed" by an inert gas, such as
nitrogen, to prevent oxidation or other undesirable side reactions. Upon
completion of the reaction, the vessel may be used as a distillation pot to
vaporize the liquid phase (solvent), or the reaction products may be pumped out
so the vessel can be cooled to begin the next cycle.
3.1.2 Reactor Emissions
Reactor emissions stem from the following causes: (a) displacement of
air containing VOC during reactor charging, (b) solvent evaporation during
the reaction cycle (often VOC's are emitted along with reaction by-product
gases which act as carriers), (c) overhead condenser venting uncondensed
VOC during refluxing, (d) purging vaporized VOC remaining from a solvent
wash, and (e) opening reactors during a reaction cycle to take samples,
determine reaction end-points, etc.
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Emissions may be greater when a reactor is operated under pressure because
the pressure must be relieved between cycles. This may be done by venting
directly to the atmosphere or through a condenser. When the reactor is
vented through an overhead condenser, care must be taken not to overload the
condenser by relieving reactor pressure too rapidly.
As with all VOC sources in pharmaceutical plants, reactor emissions vary
tremendously. One would expect the greatest emissions from uncontrolled vessels
reacting chemicals at elevated temperatures in the presence of
volatile solvents. On the other hand, few emissions will result from low
temperature and pressure, or water based reactions. Emissions also depend on
the number of batches or annual throughput for a reactor. Below are reactor
emission estimates from four companies.
Table 3-1. REACTOR EMISSION ESTIMATES1»2'3'4
Number of Emissions (per reactor) Mg/yr
Company Reactors Uncontrolled Controlled Emission Control
1 4 - 5.0-5.4 vent condensers
2 18 0.2-9.5 - none
3 8 0.6-8.7 0.06-1.3 vent condensers
4 4 2.2* 0.043* carbon adsorber
1 0.001 - none
1 - 0.05 vent condenser
1 - 0.13 vent condenser
*Total emissions for all four reactors
3.1.3 Control Technology
Equipment options available to control emissions from reactors are condensers,
adsorbers, and liquid scrubbers. Condensers are often included on reactor systems
as normal process control equipment.
3-3
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Surface condensers are the most prevalent form of control for reactor
emissions. Water is the usual cooling medium. Barometric condensers are
seldom used since they contaminate and dilute condensed VOC. Refrigerated
cooling systems also are widely used to control lower boiling VOC's. Some-
times two condensers in series are used to effect greater VOC removal. One
C
plant has installed a double condenser system to a batch reactor operation
where an inert gas is sparged into the reaction vessel at 0.057m3 (2 cubic
ft) per minute to prevent decomposition of the reaction product. Previously,
this inert gas was vented to a water cooled condenser to remove VOC and dis-
charged to the atmosphere at a temperature of 30-35°C. Toluene is one of the
materials being removed. If assumed to be in equilibrium with the inert gas,
toluene was being emitted at a rate of about 0.9 kg (2 lbs) per hour. A
brine-cooled condenser was installed in series to further reduce the exit
gas temperature to 2-3°C and toluene emissions to 0.09 kg (0.2 lbs) per hour.
An additional emission reduction was achieved by putting a conservation vent
on the brine condenser vent and by regulating nitrogen pad pressure
(maintained at 3-5 in. HgO).
As is seen from Table 3.1, carbon adsorbers can be used to treat reactor
offgases; although in some cases, safety factors or Food and Drug Administration
requirements may preclude their use. Normally, the emissions from a single reactor
would not be large enough to warrant installing an adsorber; rather, the emissions
from several reactors or several VOC sources within the plant would be ducted together
and treated by a common control system. Manifolding sources to a common control
device is most easily done on process equipment dedicated to the production of a
single product.
Liquid scrubbers are used to treat a variety of pharmaceutical plant
c 7
emission sources, including reactor emissions. ' Most are low pressure
drop scrubbers which handle several sources, although special purpose units
such as venturi scrubbers may control a single vent. A high degree of
control can be obtained for water soluble VOC with smaller reductions
3-4
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for slightly soluble or insoluble compounds. In two plants visited, emissions from
o q
reactor opening and charging were ducted through hoses to scrubber systems. ' This
control was installed principally to protect the workers.
Vapor incinerators will be feasible control options in certain instances.
They are sometimes used in the industry to control odors from fermentation
operations. Incineration technology has'also been applied to VOC emissions from
reactors. In one plant, VOC emissions from reactors, storage tanks, evaporators,
and distillation apparatus are collected in a single ventilation header and fed
to an incinerator.^
Emissions which result from solvents used to clean and dry reactors may
be reduced by good housekeeping practices such as sealing reactors during the
cleaning operation and purging cleaned reactors to a control device.
3.2 DISTILLATION UNITS
3.2.1 Distillation Operations
Distillation may be performed by either of two principal methods. The
first method is based on the production of a vapor by boiling the liquid,
mixture to be separated and condensing the vapors without allowing any liquid
to return to the still. The second method is based on the return of part of
the condensate to the still so that the returning liquid is brought into
intimate contact with the vapors on the way to the condenser. Either of these
methods may be conducted as a batch or continuous operation.
Distillation may be performed in batch reactors, in small stills attendant
to reactors, or in larger distillation columns such as may be used for waste
solvent recovery operations. Most distillation equipment is small compared
to that used in refineries and petrochemical plants. The largest distillation
columns in pharmaceutical plants process around 3200 kg/hr (7000 lbs/hr) of
feed materi al.^
3-5
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3.2.2 Distillation Emissions
Volatile organic compounds may be emitted from the distillation condensers
used to recover evaporated solvents. The magnitude of amissions depends on the
operating parameters of the condenser, the type and quantity of organic being
condensed, and the quantity of inerts entrained in the organic. Table 3-2
lists reported emission estimates for several distillation operations; VOC
losses range from less than one to more than 23 Mg/yr. Since emissions
vary widely among different distillation units, no typical emission factors
can be established.
3.2.3 Control Technology
Emissions from distillation condensers can be controlled through use of
aftercondensers, scrubbers, and carbon adsorbers.
The main condenser efficiency can be increased by lowering the coolant
temperature or can be augmented by installing another condenser in series. The
second condenser would utilize a circulating fluid cooler than that for the main
condenser. The improvement in control can be estimated using the information
in Section 4.1 of this document.
In existing plants, there are examples of distillation condenser emissions
being ducted to carbon adsorbers and liquid scrubbers.No examples of
the use of incinerators were found, although incineration may be feasible in
some instances. Refer to Sections 4.2, 4.3, and 4.4 for more information on the
performance of liquid scrubbers, carbon adsorbers, and incinerators, respectively.
3.3 SEPARATION OPERATIONS
Several separation mechanisms are employed by the industry including
extraction, centrifugation, filtration, and crystallization. These are discussed
in the same section because of similarities in emissions and applicable controls.
Distillation and drying are discussed in separate sections.
3-6
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Table 3-2. EMISSION ESTIMATES
FOR DISTILLATION OPERATIONS12'13'14'15'16'17
Unit Distilled Throughput Emissions Control (other
Number Material (s) Mq/yr tons/yr Mg/yr tons/yr than main condenser
1
Acetone
392.6
432.9
5.9
6.5
Chloroform
37.6
41.5
1.1
1.2
Ethyl Acetate
223.8
246.8
6.7
7.4
Methanol
906
999.0
14.4
15.9
Xylene
450.3
496.5
3.4
3.7
2
Isopropanol
212
234.0
16.0
17.6
Methylene Chloride
176
194.2
6.6
7.3
Ethylene Dichloride
68.8
75.8
1.0
1.1
3
Benzene
368.4
406.2
7.3
8.1
Dimethylformamide
452.2
498.6
7.9
8.7
Heptane
274.9
303.1
4.1
4.5
Isopropyl Ether
70.0
77.2
1.7
1.9
MIBK
14.3
15.8
0.36
0.4
Toluene
7.4
8.2
0.09
0.1
4
Methanol
2352
2593
23.6
26
5
Isopropanol
4671
5150
3.4
3.8
Mineral Oil
1166
1286
-
6
Toluene
15.0
16.6
0.80
0.88
aftercondenser
(brine), after-
condenser ventei
to liquid ring
vacuum pump
7
Isopropanol
0.12
0.13
0.05
0.06
Methanol
0.12
0.13
0.05
0.06
Toluene
0.12
0.13
0.05
0.06
Ethanol
0.12
0.13
0.05
0.06
Methyl amine
0.01
0.01
0.01
0.01
8
Acetone
590 kg/hr
1300 lbs/hr
2.3 kg/hr
5 lbs/hr
aftercondensers
9
Acetone
90
99
0.80
0.88
aftercondensers
10 Benzene 4.4 4.8 0.44
Methylene Chloride 1.5 1.7 0.15
0.48
0.17
aftercondensers
-------
3.3.1 Extraction
Extraction is used to separate components of liquid mixtures or solutions.
This process utilizes differences in solubilities of the components rather than
differences in volatilities (as in distillation), i.e., solvent is used that will
preferentially combine with one of the components. The resulting mixture to be
separated is made up of the extract which contains the preferentially dissolved
material and the raffinate which is the residual phase.
The pharmaceutical industry generally utilizes two kinds of solvent extraction.
In the first, the extraction takes place within the reactor itself. Solvent
is introduced into the vessel and agitated until the material to be extracted is
dissolved. The two phases are then allowed to separate and the lower, denser
layer is drawn off and transferred to a second vessel.
The second type of extraction takes place in a vertical cylinder. A solvent
is made to flow upward or downward through the liquid mixture. Either the solvent
or the mixture is dispersed before entering the column; this increases contact
and promotes the extraction process. Further extraction efficiency may be
gained by using a packed column. The packing enhances contact between liquids.
Extraction columns are normally run continuously for extended periods of time.
Surge tanks or receivers may be used to collect extract and raffinate.
3.3.2 Extraction Emissions
Emissions from batch extraction stem mainly from displacement of vapor while
pumping solvent into the extractor and while purging or cleaning the vessel after
extraction. Some VOC also may be emitted while the liquids are being agitated.
Column extractors may emit VOC while the column is being filled, during extraction,
or when it is emptied after extraction. Emissions not only occur at the extractor
itself, but also through associated surge tanks. These tanks may emit significant
amounts of solvent due to working losses as the tank is repeatedly filled and
emptied during the extraction process.
3-8
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20
Emission estimates were available from only one plant. One extraction
column emitted 2.86 Mg/yr before control, and 0.29 Mg/yr after a condenser was
installed. The other extractor had uncontrolled emissions of 10.8 Mg/yr and
controlled emissions of 1.6 Mg/yr. Again, the control was provided by a condenser.
3.3.3 Centrifugation Description
Centrifuges are used to remove intermediate or product solids from a
liquid stream. Center-slung, stainless steel, basket centrifuges are most commonly
used in the industry. To begin the process, the centrifuge is started and the
liquid slurry is pumped into it. An inert gas, such as nitrogen, is sometimes
introduced into the centrifuge to avoid the buildup of an explosive atmosphere.
The spinning centrifuge strains the liquid through small basket perforations.
Solids retained in the basket are then scraped from the sides of the basket and
unloaded by scooping them out from a hatch on the top of the centrifuge or by
dropping them through the centrifuge bottom into receiving carts.
3.3.4 Centrifuge Emissions
A large potential source is open type centrifuges which permit large quantities
of air to contact and evaporate solvents. The industry trend is toward completely
enclosed centrifuges and, in fact, many plants have no open type centrifuges.
If an inert gas blanket is used, it will be a transport vehicle for solvent vapor.
This vapor may be vented directly from the centrifuge or from a process tank
receiving the mother 1iquor. However, this emission source is likely to be
small because the inert gas flow is only a few cfm.
The solids removed from the basket are still "wet" with solvent and will be
a source of emissions while being unloaded and transported to the next process
step. Bottom unloaders can minimize this problem if the solids are transferred
to a receiving cart through a closed chute and the receiving cart is covered while
3-9
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transporting solids. It could be difficult to replace an existing top unloading
centrifuge with a bottom unloading type because many centrifuges are on the
ground floor and there is little room for raising or lowering.
Few data were found on centrifuge emissions. Emissions from two enclosed
pi
centrifuges averaged less than a megagram per year (<1.1 tons/yr) at one plant.
Although emissions from an open-type centrifuge could be significantly greater,
no estimates were available.
3.3.5 Filter Descriptions
Generally, filtration is used to remove solids from a liquid, whether these
solids be product, process intermediates, catalysts, or carbon particles (e.g., from
a decoloring step). Pressure filters, such as shell and leaf filters, cartridge
filters, and plate and frame filters are usually used. Atmospheric and vacuum
filters have their applications, too.
The normal filtration procedure is simply to force or draw the mother
liquor through a filtering medium. Following filtration, the retained solids
are removed from the filter medium for further processing.
3.3.6 Filter Emissions
Enclosed pressure filters normally do not emit VOC during a filtering
operation. The filtered liquid is sent to a receiving tank. Emissions can
occur, however, when a filter is opened to remove collected solids. Emissions
can also occur if the filter is purged (possibly with nitrogen or steam) before
cleaning. The purge gas will entrain evaporated solvent and probably be vented
through the receiving tank. Emissions from filter steam purging at one plant were
estimated about 5 Mg/yr before control. After a condenser was put in, controlled
22
emissions were about 0.55 Mg/yr.
3-10
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Largest VOC emissions are from vacuum drum filters which are operated by
pulling solvent through a precoated filter drum. Potential emissions are significant
both at or near the surface of the drum and from the ensuing waste stream.
These filters can be shrouded or enclosed for control purposes.
3.3.7 Crystallization Operations
Crystallization is a means of separating an intermediate or final product
from a liquid solution. This is done by creating a supersaturated solution, one
in which the desired compound will form crystals. If performed properly and in
the absence of competing crystals, crystallization can produce a highly pure
product.
Supersaturation may be achieved in one or more of three ways. If solubility
of the solute increases strongly with temperature, a saturated solution becomes
supersaturated by simple cooling. If solubility is relatively independent of
temperature, supersaturation may be generated by evaporating a portion of the solvent.
If neither cooling nor evaporation is desirable, supersaturation may be induced
by adding a third component. The third component forms a mix with the original
solvent in which the solute is considerably less soluble.
3.3.8 Crystallization Emissions
If crystallization is done mainly through cooling of a solution, there will
be little VOC emission. In fact the equipment may be completely enclosed.
However, when the crystallization is done by solvent evaporation, there is greater
potential for emissions. Emissions will be significant if evaporated solvent
is vented directly to the atmosphere. More likely the solvent will be passed
through a condenser or from a vacuum jet (if the crystallization is done under
vacuum).
Emission estimates were available from only one plant. These are presented
in the table below. They are not intended to establish an emission factor
for crystallization but only to give an idea of the range and variability of
emissions to be expected.
3-11
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Table 3-3. EMISSION ESTIMATES FOR
CRYSTALLIZATION OPERATIONS AT ONE PLANT23
Number of
Crystal 1izers
Solvent
Emitted
Solvent
Throughput
Emissions**
Control
Equipment
4
MIBK*
32,578 Mg/yr
1.6 Mg/yr
none
2
MIBK
22,500 Mg/yr
0.68 Mg/yr
none
1
n-butanol
429 Mg/yr
0.018 Mg/yr
none
acetone
90 Mg/yr
0.072 Mg/yr
1
MIBK
215 Mg/yr
<0.01 Mg/yr
none
acetone
18 Mg/yr
<0.01 Mg/yr
*Methyl isobutyl ketone
**A11 emissions estimated by vapor pressure calculation.
3.3.9 Separation Operations Control Technology
The most direct method of control for separation operations is to contain
VOC vapors and minimize their opportunity to escape. Some equipment designs
are inherently lower emitters than others. For example, it will be much easier
to control vapors in a closed-feed centrifuge than one that is manually loaded
or open faced. Operators should be encouraged to use equipment in which VOC
vapors can be contained and required to maintain good operating practices; this
will help minimize the capital and operating cost of any control system selected
to capture or destroy the VOC.
Several add-on control technologies may be used on the separation equipment
described in this section. Condensers certainly would be applicable and may be
the least costly option. They can be applied to individual systems. Water
scrubbers also have found wide usage in the industry.24*25 are versatiie and
capable of handling a variety of VOC having an appreciable water solubility.
Scrubbers can be either small or quite large; thus, they can be designed to handle
emissions from a single source or from many sources (via a manifold system).
3-12
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2fi
Carbon adsorbers can be and have been employed on vents from separation operations. 9
Several vents may be ducted to an adsorber because it is likely that
emissions from a single source would not warrant the expense of a carbon adsorption
unit. Recently, small carbon canisters have been used to handle a single,
relatively small, emission source; however, this is usually done to alleviate an
odor problem. Finally, in some instances, incinerators may be applicable. They
will not always be a good choice because the expected variability from these emission
sources might make continuous incinerator operation difficult.
3.4 DRYERS
3.4.1 Dryer Description and Operation
Dryers are used to remove most of the remaining solvent in a centrifuged
or filtered product. This is done by evaporating solvent until an acceptable
level of "dryness" is reached. Evaporation is accelerated by applying heat and/or
vacuum to the solvent laden product or by blowing warm air around or through it.
Because a product may degrade under severe drying conditions, the amount of heat,
vacuum, or warm air flow is carefully controlled.
Several types of dryers are used in synthetic drug manufacture. Some of
the most widely used are: tray dryers, rotary dryers, and fluid bed dryers.
A typical batch tray dryer consists of a rectangular chamber containing two
carts which support racks. Each rack carries a number of shallow trays that are
loaded with the product to be dried. Heated air is circulated within the chamber.
A rotary dryer or tumbler dryer consists of a revolving cylindrical or conical
shell supported in a horizontal or slightly inclined position. Rotary dryers
may be vacuum type or hot air circulation type. The rotation of the dryer
tumbles the product to enhance solvent evaporation and may also perform a blending
function.
3-13
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Fluid bed dryers evaporate solvent by forcing heated air through
the wet material. Typically, a large pan loaded with product is placed inside
the dryer where air is blown through the bottom of the pan. The air agitates or
fluidizes the product. Some product particles may be entrained in the gas stream.
They are captured by a fabric filter and returned to the dryer.
3.4.2 Dryer Emissions
Dryers are potentially large emission sources. Emission rates vary during
a drying cycle and are greatest at the beginning of the cycle and least
at the end of the cycle. Drying cycle times can range from several hours
to several days.
Table 3-4 shows reported emissions for drying operations at several
manufacturing facilities. In most cases the estimates are based on theoretical
calculations or equipment vendor efficiency claims.
*
As the data in the table indicate, emissions vary considerably. The
variations arise from differences in: dryer sizes, number of drying cycles per
year, and amount and type of solvent evaporated per cycle. Emissions from
air dryers are normally greater than those from vacuum dryers, mainly because
air dryer emissions are dilute and more difficult to control.
3.4.3 Control Technology
Table 3-4 contains some of the control devices currently used on dryers.
Control options include condensation, wet scrubbing, adsorption, and incineration.
Condensers are often the first devices selected when dealing with air
pollution from vacuum dryers. They can be used by themselves or in series with
another device. The first two examples in Table 3-4 indicate use of a
condenser followed by a carbon adsorber. In these specific instances, total rer.iova
efficiency is estimated at greater than 99 percent. Condensers are not typically
used on air dryers because the emissions are dilute. For information on
condenser performance see Section 4.1.
3-14
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Table 3-4. EMISSION ESTIMATES FOR DRYING
OPERATIONS^® > 32,33
# of Dryers
Solvents
Emitted
Uncontrolled
Emissions
Controlled
Emissions
Control
Equipment
Remarks
1
1
1
1
1
2
1
MIBK*
Isopropanol
MIBK
Isopropanol
Isopropanol
Methanol
Ethanol
Ethanol
Acetone
Ethyl
acetate
Acetone
Methanol
Unknown
1295 Mg/yr
1295 Mg/yr
(per dryer)
52.6 Mg/yr
77 Mg/yr
2.7 Mg/yr
1.2 Mg/yr
46 Mg/yr
3.2 kg/hr
3.2 kg/hr
6.5 kg/hr
(per dryer)
0.8 Mg/yr
5.2 Mg/yr
(per dryer)
52.6 Mg/yr
negligible
2.7 Mg/yr
1.2 Mg/yr
0.93 Mg/yr
negligible
negligible
6.5 kg/hr
(per dryer)
condenser &
carbon
adsorber
condenser &
carbon
adsorber
none
wet
scrubber
none
none
carbon
adsorber
vacuum
pump
vacuum
pump
none
operates
continuously
operates
continuously
blender-dryer
52.2 Mg/yr 52.2 Mg/yr
(total three dryers)
none
tray dryer
pump acts as a
contact condenser
pump acts as a
contact condenser
air transport
type dryers,
maximum emission
rate
tray dryer
*MIBK - methyl isobutyl ketone
3-15
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Wet scrubbers have also been used to control many plant sources, including
dryers. They can also remove particulates generated during drying. The scrubber
cited in Table 3-4 removes both methanol and particulates. For water soluble
compounds, VOC absorption efficiencies can be quite high (i.e. 98-99 percent).
See Section 4.2 for a discussion of the performance of scrubbers.
Several examples of the use of carbon adsorption are in the table. As was
noted above, an adsorber can be used following a condenser. Not only will overall
efficiency increase but a longer regeneration cycle can be used in the adsorber.
Carbon adsorbers are discussed more fully in Section 4.3.
Vapor incinerators may be viable controls although no installations were found
during our investigations. Varying VOC flows to the incinerator may present
operating problems.
3.5 STORAGE AND TRANSFER
3.5.1 Storage and Transfer Description
Volatile organic compounds are stored in tank farms, 55 gallon drums, and
sometimes in process holding tanks. Storage tanks in tank farms range in size
from about 20,000-110,000 liters (5,000-30,000 gallons). Most are horizontal
tanks, although vertical tanks also are used. Process holding tanks are smaller
and range in size from 2,000-20,000 liters (500-5,000 gallons).
In plant transfer of VOC is done mainly by pipeline, but also may be done
manually (e.g., loading or unloading 55 gallon drums). Raw materials are
delivered to the plant by tank truck, rail car, or in 55 gallon drums.
3.5.2 Storage and Transfer Emissions
The vapor space in a tank will in time become saturated with the stored
organics. During tank filling, vapors are displaced causing an emission or a
"working loss." Some vapors also are displaced as the temperature of the stored
3-16
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VOC rises, such as from solar radiation, or as atmospheric pressure drops; these
are "breathing losses." The amount of loss depends on several factors: type
of VOC stored, size of tank, type of tank, diurnal temperature changes, and
tank throughput. Working and breathing losses can be estimated from equations
found in an EPA publication entitled "Compilation of Air Pollutant Emission Factors,
Supplement No. 7" printed in April, 1977. Although technically the equations
are for vertical tanks storing petroleum liquids, they will provide reasonable
approximations for horizontal tanks and pure chemicals. The equations are reproduced
below:
Fixed Roof Breathing Losses
Lb = 2.21 x 10"4M T37TT°'68 Dl*73H°*51AT°-50FpCKc
where Lg = Fixed roof breathing loss (lb/day)
M = Molecular weight of vapor in storage tank (lb/lb mole)
P = True vapor pressure at bulk liquid conditions (psia)
D = Tank diameter (ft)
H = Average vapor space height, including roof volume correction (ft)
AT = Average ambient temperature change from day to night (°F)
Fp = Paint factor (dimensionless)
C = Adjustment factor for small diameter tanks (dimensionless)
Kc = Crude oil factor (dimensionless)
Fixed Roof Working Losses
Lw = 2.40 x 10"2MPKnKc
where: L^ = Fixed roof working loss (lb/10 gal throughput)
M = Molecular weight of vapor in storage tank (lb/lb mole)
P = True vapor pressure at bulk liquid conditions (psia)
Kn = Turnover factor (dimensionless)
Kc = Crude oil factor (dimensionless)
3-17
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To illustrate the magnitude of storage emissions from tanks typical of the
industry, several calculated emission rates are presented in Table 3-5. Four
sizes of tanks are represented (4,000 liters; 20,000 liters; 50,000 liters; and
100,000 liters). The three largest tanks were assumed to be filled once
per month. The smallest tank, representing a process tank, was assumed to be
filled 200 times per year. Three organic chemicals have also been selected
to represent compounds of lower volatility (toluene), medium volatility (acetone),
and high volatility (methylene chloride). The following values were used for
equation variables:
M = 58 lb/lb-mole (acetone)
= 92 lb/lb-mole (toluene)
= 85 lb/lb-mole (methylene chloride)
P = 2.9 psia (acetone)
= 0.3 psia (toluene)
= 5.4 psia (methylene chloride)
D = 4.9 ft. (4,000 liter tank)
= 8.5 ft. (20,000 liter tank)
= 11.5 ft. (50,000 liter tank)
= 14.4 ft. (100,000 liter tank)
H = 3.6 ft. (4,000 liter tank)
= 6.3 ft. (20,000 liter tank)
= 8.6 ft. (50,000 liter tank)
= 10.8 ft. (100,000 liter tank)
AT = 20°F
Kc= 1.0
C = 0.25 (4,000 liter tank)
=0.45 (20,000 liter tank)
= 0.60 (50,000 liter tank)
= 0.70 (100,000 liter tank)
Kn = 0.32 for 4,000 liter tank (200 turnovers/year) see Appendix C for values
= 1.0 all other tanks (12 turnovers/year) for other tank turnover
numbers
As can be seen from the table, yearly emission rates for individual storage
or process tanks are not great. However, a manufacturing facility may have ten
assuming an average ambient temperature
of 60°F
assuming tank height equals ^1.5 times
diameter
assuming H equals 1/2 tank height
assumes tank painted white
different from 1.0 only when storing crude
see Appendix C for values for other
tank sizes
3-18
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Table 3-5. CALCULATED STORAGE TANK LOSSES*
Iank Chemical Breathing Losses Working Losses Total Losses
Size Stored lbs/day Mg/yr lbs/103 gal Mg/yr Mg/yr
4,000 liters
(1060 gal)
20,000 liters
(5,280 gal)
50,000 liters
(13,200 gal)
(26,400 gal)
toluene
0.049
0.008
0.212
0.02
0.028
acetone
0.166
0.03
1.29
0.12
0.15
methylene
chloride
0.436
0.07
3.53
0.34
0.41
toluene
0.305
0,05
0.662
0.02
0.07
acetone
1.03
0.17
4.04
0.12
0.29
methylene
chloride
2.71
0.45
11.0
0.32
0.77
toluene
0.804
0.13
0.662
0.048
0.18
acetone
2.71
0.45
4.04
0.29
0.74
methylene
chloride
7.14
1.2
11.0
0.79
2.0
toluene
1.55
0.26
0.662
0.095
0.35
acetone
5.25
0.87
4.04
0.58
1.4
methylene
13.8
2.3
11.0
1.6
3.9
chloride
*For horizontal and vertical tanks with no control
3-19
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or more large tanks and several smaller tanks. Therfore, aggregate storage emissions
from such a facility would be significant.
Chemical transfer operations also contribute to plant VOC emissions. Common
sources of transfer emissions and other "fugitive" emissions are:
a) manual transfer of chemicals from 55 gallon drums to receiving vessels;
b) pump seals, flanges, valve seals, agitator seals;
c) hose connections or couplings;
d) head gaskets and seals on filters;
e) pressure relief devices;
f) and opening reactors for charging or cleaning.
Some chemicals are stored in 55 gallon drums. Transfer of chemicals from
drums to process vessels is occasionally done through permanent piping; however,
more commonly it is done by opening the drum and manually pouring the contents.
The manual pouring is a source of emissions, although a relatively small one on
a "per drum" basis.
Pump seals, valves, flanges, and agitator seals may begin to leak VOC during
the course of normal use. Some leaks may be the result of poor or infrequent
maintenance. Pressure relief devices do not normally leak. Liquid losses can
usually be detected by sight and vapor leaks can be detected reliably by hydrocarbon
detectors.
There are no known studies of the magnitude of fugitive emissions within
pharmaceutical plants, although studies have been completed for petroleum refineries
and petrochemical plants. Although these industries use similar processing equipment,
there are significant differences. Pharmaceutical plant process equipment is
much smaller and, for the most part, is not subjected to the elevated temperatures
and pressures often used in refineries and chemical plants. High temperatures
and pressures contribute to higher leak rates. In addition, the batch process
3-20
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nature of pharmaceuticals leads to intermittent use of equipment and corresponding
intermittent leaks. Refinery and chemical plant processes are continuous. Finally,
pharmaceutical plant process equipment is usually enclosed in buildings. Inside
the buildings, leaks are repaired quickly to protect workers from toxic chemical
exposure. For the above reasons, pharmaceutical plant fugitive emissions are
thought to be lower than those for refineries and petrochemical plants.
3.5.3 Control Technology
Emissions from storage or process holding vessels may be_reduced with
varying efficiency through use of vapor balance systems, conservation
vents, vent condensers, pressurized tanks, and carbon adsorption.
Good housekeeping practices can also assist in reducing emissions. For example,
operating procedures should require that covers and ports be closed when a tank
contains solvents or is being cleaned and dried with solvents. Covers should be
open for only short periods when solid materials are charged or samples taken out.
When storage tanks are being filled, displaced vapors can be ducted to the
delivery tank truck or rail car. Such vapor return lines are in conmion use in
the pharmaceutical industry.^ Emissions from filling are essentially eliminated;
however, to complete the cycle, vapor recovery should be practiced when the tank
truck or rail car is refilled or cleaned at the terminal.
Conservation vents are devices that seal a tank vent against small
pressure changes. During the day, a conservation vent prevents tank emissions
due to vapor warming and expansion until the internal tank pressure exceeds the
vent set pressure. Similarly, at night the vapor inside a tank cools causing
a decrease in internal tank pressure. Outside air is prevented from entering
the tank until the vacuum setting of the vent is exceeded. Conservation vents
will provide small reductions in breathing losses. Increasing the pressure/vacuum
3-21
-------
setting will increase the amount of breathing loss control; however, the settings
cannot be increased indiscriminately or the internal pressure/vacuum developed
may damage the tank. Conservation vents may begin to reseat improperly
through mechanical malfunction, freezing rain, corrosion, etc., thereby
reducing effectiveness. A regular inspection and maintenance program can
ensure that they remain in good operating condition. Working losses are not
affected by conservation vents.
Fixed roof tank emissions may be controlled by use of refrigerated vent
condensers. Condensers should be sized to handle the maximum vapor rate expected
at any given time, which normally occurs during tank filling. Condensers also
may have to be designed to handle freezing of moisture. The moisture gets
into the tank along with ambient air during breathing. This problem can be
solved by defrosting the condenser and separating the recovered water-VOC mixture.
Vent condenser removal efficiency depends on the vapor concentration of VOC in
the vapor space and on the refrigeration temperature. See Section 4.1 for a discussion
of condenser efficiencies.
Internal floating roofs have been retrofitted on storage tanks to achieve
80-97 percent control of VOC emissions. The floating roof is an internal cover
using a closure device to seal the gap between tank wall and the floating roof
around the roof internal perimeter. To retrofit an existing tank, an opening
has to be made through which components of "the floating roof are introduced.
Other tank modifications may be needed. For example, the tank shell may require
corrections for deformation and obstruction or special modifications for bracing,
reinforcing, and vertical plumbing. Because of these retrofit problems, installa-
tion can be relatively expensive. This expense is justified for large storage
tanks because of the amount of VOC kept from evaporating.
Floating roofs are widely used in refineries and petrochemical plants;
however, their applicability to pharmaceutical plant storage tanks is less certain.
This control option is usually reasonable only for vertical tanks of at least
76,000 liter capacity (20,000 gallons). Final guidance on the feasibility of
3--W- applying a floating roof to this size range tank is forthcoming from EPA.
-------
Another alternative for reducing storage losses is utilizing pressurized
storage tanks. Pressure tanks are designed to withstand the internal pressure
built up through rising stored VOC temperatures during the daytime, thereby
eliminating breathing losses. A practical pressure tank system would use
an inert gas to occupy the vapor space during emptying; this gas, containing
VOC, would have to be purged during refilling operations. Thus, working
losses will not be eliminated. Because of their high cost, pressure tanks are
feasible only for storage of highly volatile VOC.
Carbon adsorbers have been used to control many different process emission
Or
sources, including process tanks in pharmaceutical plants. Control of similar
37
emission sources also has been achieved through scrubbing. In each of these
systems, one control device can handle the manifolded emissions from many sources.
Control efficiencies claimed are 98+ percent. These technologies are also feasible
for. coritrolling emissions from larger tanks in the tank farm. One problem is that
the systems handle all input VOC and the recovered mixed solvents have little value;
therefore, recovery would be difficult. Scrubber effluent and adsorber regeneration
condensate will (or generally will) have to be sent to the sewer or the plant's
wastewater treatment system.
Breathing losses can be substantially reduced through use of underground
storage tanks. Underground tanks are insulated from daily temperature fluctuations
and, therefore, do not undergo the vapor space expansion/contraction cycles
characteristic of above ground tanks. This control option is suggested mainly
for new tank installations since in most cases it will be impractical to convert
existing tanks to underground tanks.
3-23
-------
Plant fugitive emissions are best dealt with through an active inspection and
maintenance program. Leaking components should be replaced or repaired as soon as
is practical.
Emissions from reactor or other vessel opening are controlled in some plants
38 39
by drawtos vapors through flexible hoses to scrubbing systems. ' This control
was installed principally to protect workers from VOC exposure rather than to
reduce plant emissions.
3-24
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3.6 REFERENCES
1. Process Equipment Registration submitted to Connecticut Department of
Environmental Protection by Pfizer, Inc., September 26, 1972.
2. Data submitted to New Jersey Department of Environmental Protection by
Schering Corporation, December 22, 1976.
3. Data submitted to New Jersey Department of Environmental Protection by
Hoffmann-LaRoche, Inc., December 13, 1976.
4. Letter with attachments from Nancy Diaz, Eli Lilly and Company, Mayaguez,
Puerto Rico, to Michael R. Clowers, EPA, August 11, 1978.
5. David A. Beck, EPA, "Trip to Merck Sharp and Dohme Quimica de Puerto Rico
Pharmaceutical Plant in Barceloneta, Puerto Rico," memo to David R. Patrick,
EPA, November 6, 1978.
6. Reference 5.
7. David A. Beck, EPA, "Trip to the Roche Pharmaceutical Plant in Manati,
Puerto Rico," memo to David R. Patrick, EPA, October, 1978.
8. David A. Beck, EPA, "Trip to Winthrop Laboratories Pharmaceutical Plant in
Barceloneta, Puerto Rico," memo to David R. Patrick, EPA, November 6, 1978.
9. David A. Beck, EPA, "Trip to the Eli Lilly Pharmaceutical Plant in
Mayaguez, Puerto Rico," memo to David R. Patrick, EPA, November 6, 1978.
10. Letter with attachments from William E. McDowell, Merck Sharp and Dohme
Quimica de Puerto Rico, Inc., to Maria M. Irizarry, EPA (San Juan),
February 23, 1977.
11. Letter with comments from Dorothy Bowers for the Pharmaceutical Manufacturers
Association to Robert T. Walsh, EPA, May 15, 1978.
12. Reference 1, December 14-17, 1973.
13. Permit Application to New Jersey Department of Environmental Protection by
Hoffman-LaRoche, Inc., January 30, 1978.
3-25
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14. Certificate to Operate Control Apparatus or Equipment from New Jersey
Department of Environmental Protection to Ciba-Geigy Corporation,
June 10, 1977,
15. Permit Application to New Jersey Department of Environmental Protection fay
Merck and Company, Inc., August 7, 1973,
16. New Jersey Department of Environmental Protection Permit Review Form for
Hoffman-LaRoche, Inc., March 15, 1978.
17. Permit Application to New Jersey Department of Environmental Protection by
Merck and Company, Inc., March 15, 1978.
18. Reference 9.
19. Reference 1, January 28, 1975.
20. Reference 3.
21. Reference 1, December 13, 1973.
22. Certificate to Operate Control Apparatus or Equipment from New Jersey
Department of Environmental Protection to Sandoz, Inc., April 19, 1977.
23. Reference 1, submitted at different times, December 14, 1973;
February 4, 1975; and January 28, 1975.
24. Reference 7.
25. Reference 8.
26. Letter with attachments from Gilbert C. Wagner, Pfizer, Inc. to
Don R. Goodwin, EPA, September 22, 1978.
27. Reference 9.
28. Process Equipment Registrations submitted to Connecticut Department of
Environmental Protection by Pfizer, Inc., September 29, 1972,
February 27, 1975, March 31, 1975, February 19, 1975, and July 16, 1975.
29. Information submitted to New Jersey Department of Environmental Protection
by Ciba-Geigy Corporation, February 2, 1977.
3-26
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30. Reference 4.
31. Letter with attachments from Felipe Belgodere, Eli Lilly and Company, Inc.
(Mayaguez, Puerto Rico) to Maria M. Irizarry, EPA (San Juan}, December 20, 1976.
32. Reference 5.
33. Letter from Michael J. Burke, Winthrop Laboratories, to David R. Patrick,
EPA, September 14, 1978.
34. Reference 11.
35. Erikson, D. 6., Hydroscience, Inc., Draft Storage and Handling Report, EPA
Contract No. 68-02-2577, October, 1978.
36. Reference 31.
37. Reference 7.
38. Reference 9.
39. Reference 7.
3-27
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4.0 PERFORMANCE OF CONTROL SYSTEMS
This chapter contains information on expected control efficiencies for
four major control techniques: condensation, scrubbing, carbon adsorption, and
incineration. The information can be used to estimate potential emission reductii
for significant VOC sources within pharmaceutical plants.
4.1 CONDENSATION
Condensers are widely used in the pharmaceutical industry to recover
evaporated solvent from process operations and as air pollution control devices
to remove VOC contaminants from vented gases. Most operate by extracting enough
heat from the VOC vapor to cause condensation. In the most common type, surface
condensers, the coolant does not directly contact condensable vapors, rather heat
is transferred across a surface (usually a tube wall) separating vapor and cool an
In this way the coolant is not contaminated with condensed VOC and may be directi,
reused.
The type of coolant used depends on the degree of cooling needed for a
particular situation. Coolants in common use are water, chilled water, and brine
The circulating temperature of these three coolants varies from plant to plant
but typically will be around 17°C for water (yearly average), 5°C for chilled
water^, and -5°C for brine.^ Freon coolant may be used when lower cooling
temperatures are required; freon can be circulated at -40°C.^
Since most pharmaceutical process equipment is used for manufacturing severa
different products during the year, it is possible that varying VOC loads will be
4-1
-------
put on a condenser. To handle this situation most modern reactors or distillation
units have condenser/receiver systems which are manifolded to permit using alternate
coolants.^
4.1.1 Condenser Performance
Any component of any vapor mixture can be condensed if brought to
equilibrium at a low enough temperature. The temperature necessary to achieve
a given solvent vapor concentration is dependent on the vapor pressure of the
compound.
When cooling a two-component vapor where one component can be considered
noncondensable, for example, a solvent-air mixture, condensation will begin
when the temperature is reached where the vapor pressure of the volatile
component is equal to its partial pressure. The point where condensation first
occurs is called the dew point. As the vapor is cooled further, condensation
continues and the partial pressure stays equal to the vapor pressure. The less
volatile a compound, that is, the higher the normal boiling point, the lower
will be the amount that can remain vapor at a given temperature.
In cases where the solvent vapor concentration is high, for example,
from the desorption cycle of a carbon adsorber, condensation is relatively easy.
However, for sources where concentrations are typically below 25 percent of the
lower explosive limit (LEL), condensation is economically infeasible.
If the relationship between VOC vapor pressure and temperature is known, the
removal efficiency of a condenser can be estimated. The following method may
be used to estimate removal efficiency. This method is applicable to gas streams
containing a single condensable VOC component.
Emission Reduction Calculation Method
1. Make up a Cox chart for the VOC using vapor pressure and temperature data
5
from a suitable reference book and specially designed graph paper. An example
4-2
-------
of a Cox chart made up for four solvents widely used in the pharmaceutical
industry is shown in Figure 4-1.
2. Determine the amount of VOC (mole fraction) in the condenser inlet
stream, if unknown. This can be done by chemical analysis or by dew point.
To use the dew point method, direct a sample of the condenser inlet stream into
a dew point device and cool the cup till condensation occurs. The intersection
of the dew point temperature line and the vapor pressure line for the VOC will
give the partial pressure of the VOC in the stream in mmHg. The VOC mole fraction
can be determined by dividing the partial pressure of the VOC by the condenser
operating pressure (usually 760 mmHg). The volume percent of VOC is equal to the
mole fraction solvent times 100.
3. If a number of different inlet compositions and condenser exit temperatures
are to be evaluated, it is convenient to plot a second graph showing temperature
vs. the mole fraction of VOC in the vapor. This is simply done by plotting
temperature versus the VOC vapor pressure divided by the system pressure
(usually 760 mmHg) on semi-logarithmic paper. An example of this type of graph
is shown in Figure 4-2 for the same four solvents shown on the Cox chart.
4. Determine the mole fraction of VOC in the condenser outlet stream.
To do this select a temperature for the outlet gas stream and from the intersection
of this temperature and the vapor pressure line for the VOC read the final
partial pressure of the VOC. Calculate the mole fraction as before.
5. The percent VOC condensed can then be calculated:
MFS-i - ' MFS2)
PC MFS1 x 100
where PC = percent of VOC condensed;
MFS-j= mole fraction VOC into condenser;
MFSg3 mole fraction VOC out of condenser.
4-3
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I
9
8
7
6
5
4
3
2
I
9
a
7
6
S
4
3
2
I
Tj
j..
t9C
ft WH
7j
-10
10*
20*
60* 70* 80* 90* 100*
30*
40* 50*
140*
160* 180* 2<
TEMPERATURE (°C)
Figure 4-1.
-------
M r StMI-LOOARITHMIC ' CYCLES X 70 DIVISIONS (
O n t KF *1 A ESSE*? CO >J«r( ^ .
in wig
MOLE FRACTION IN VAPOR
h U 0> N <9 <0
! t JMi ;
I!
IP
f
II! HI
I
il
Figure 4
-------
It is sometimes simpler to calculate the vapor pressure of a VOC at one
temperature, rather than plotting a Cox chart. This can be done by the use of
Antoine's equation:
L°910 Pi ¦ a -
where Pi = vapor pressure of the VOC;
Ti = temperature of the system, °C;
a,b,c = Antoine equation constant from Lange's Handbook of Chemistry.
The calculation methods for gases containing more than one condensable component
are complex, particularly if there are significant departures from ideal behavior
of the gases and liquids. As a simplification, the temperature necessary for
control by condensation can be roughly approximated by the weighted average of
the temperatures necessary for condensation of each VOC considered separately but
at concentrations equal to the total organic concentration.
4.1.2 Applicability
Condensers work best on gas streams that are or nearly are saturated with
the condensable VOC. Many streams in synthesized pharmaceutical manufacturing
facilities fit this description. Condensers are less attractive control options
when the gas stream is dilute or far from saturation. In this case considerable
cooling would be required just to bring the stream to the saturation point,
and. additional cooling would be required to actually condense the VOC. In these
situations, other control techniques may be better choices.
Sometimes condenser performance may be limited by characteristics of
condensable components. For example, the lower temperature limit for condenser
operation will be the point where one of the condensables first freezes.
Operating below that point would result in freezing water or VOC (as the case
may be) to condenser tubes or walls rendering them ineffective as heat transfer
surfaces.
4-6
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4.2 SCRUBBERS OR ABSORBERS
Absorption is a gas-liquid contacting process for gas separation which
utilizes the preferential solubility of the pollutant gas or gases in the liquid.
It is one of the major chemical engineering unit operations and is treated
extensively in the chemical engineering literature. Absorption is important in
the pharmaceutical industry because many VOC's and other chemicals being used
are soluble in water or aqueous solutions. Therefore, water, caustic, or
acidic scrubbers can be applied to a variety of air pollution problems. In
recognition of this fact, many examples of scrubbing are found in the industry
today.
The main types of scrubbers are the venturi, packed tower, plate or tray
tower, and spray tower. Each is designed for the same purpose - to provide
intimate contact between the scrubbing liquid and the gaseous pollutant so that
mass transfer between phases is promoted. Each type has advantages and
disadvantages and may be best suited to a particular emission problem.
4.2.1 Control Performance
Theoretically, the lowest possible concentration of VOC pollutant(s) in a
scrubber exhaust is equal to the equilibrium partial pressure of the pollutant(s)
above the scrubbing medium at scrubber exit conditions. Absorption systems do not
operate exactly at equilibrium conditons but do approach this state. For a
given unit, overall scrubber efficiencies are influenced by a number
of factors, including intimacy of contact developed between gas and liquid, operating
temperature of the unit, concentration of pollutant in gas stream, concentration
of pollutant in the liquid scrubbing medium, and flow rates of gas and liquid.
4-7
-------
At one manufacturing facility two sets of scrubbers were employed. The
first set (two scrubbers) handled acid and VOC emissions from various process
sources in two main production lines. The scrubbing medium is a circulating 20 percent
caustic solution and design efficiency is 99 percent. The other two scrubbers
remove acids and organics ducted to them from storage vessels, hoods, centrifuges,
filters, etc. Again design efficiency is 99 percent.7
In a second plant, emissions from dimethyl amine storage tanks are scrubbed with
a 10 percent sulfuric acid solution. Estimated removal efficiency is in excess of
8
99 percent. A third plant uses wet scrubbers to control emissions from a reactor
and a dryer. The reactor offgas contains 15-20 volume percent of organics at
113 scfm. The company estimates negligible amounts of organic are emitted from
the scrubber exit. The dryer exhaust contains 0.37-0.72 volume percent of organic
and again scrubbing results in negligible emissions.9
As a final example, a manufacturer directs benzene and isopropy1 alcohol emissions
from a distillation column to a water scrubber. Essentially 100 percent of the alcohb.
is scrubbed out but only about 85 percent of the benzene.10 The variance can be
attributed to differences in water solubility; isopropyl alcohol is infinitely soluble
in water while benzene is only slightly soluble.
The above examples indicate very high removal efficiencies can be attained
through use of scrubbing. In some situations, system characteristics may be
such that somewhat lower performance is realized. Nonetheless, efficiencies in
excess of 90 percent should be expected.
4.2.2 Applicability
Scrubbers are widely used emission control devices at pharmaceutical
plants. They can be successfully applied to VOC emissions soluble in water or whatever
scrubbing medium is used. Compounds of medium to low solubility can also be
treated, but scrubber sizes and liquid flow rates would have to be correspondingly
4-8
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larger to attain removal efficiencies comparable to those attained when scrubbing
soluble compounds.
Examples of emission control by scrubbing have been found for all sources
within plants synthesizing pharmaceuticals; these include emissions from reactors,
distillation equipment, process tanks, centrifuges, filters, crystallizers,
storage tanks, dryers, and fugitive sources. Most often the emissions from more
than one source are ducted together and treated in a common control system.
4.3 CARBON ADSORPTION
Adsorption is the phenomenon in which molecules of a fluid contact and
adhere to the surface of a solid. Adsorption is important in controlling
VOC emissions because many organics are easily adsorbed onto activated
carbon. Because the adsorbed compounds have practically no vapor pressure
at ambient temperatures, a carbon adsorption system is particularly suited
to recovering VOC in small concentrations.^
In operation, a carbon adsorption system initially removes a VOC
contaminant; however, a stage is reached in which the carbon continues
to adsorb but at a decreasing rate. At this stage, VOC will begin to
appear in the system exhaust; this is breakthrough. At or before breakthrough,
the carbon is regenerated through desorption of collected VOC and another
adsorption cycle is then begun. _ _
4.3.1 Control Performance
The amount of material adsorbed on a carbon bed depends on the type of
activated carbon used, the characteristics of the VOC, the VOC concentration
and the system temperature, pressure, and humidity. Overall VOC removal
efficiencies depend on the adsorption cycle time (i.e., how soon after
breakthrough the carbon is regenerated), the completeness of regeneration, carbon
bed depth, contact time, and the effectiveness of recovery of desorbed organics.
4-9
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One pharmaceutical manufacturer uses two carbon adsorbers to control VOC
emissions. One adsorber handles emissions from various reactor and condenser
] 9
vents and the other unit cleans vented gases from centrifuges and dryers.
Both of the units are designed to remove 98 percent of the VOC emissions.
Another manufacturer employs carbon adsorption to control emissions from
rotary vacuum filters. The organics removed are methyl isobutyl ketone
13
and isopropanol; reported removal is in excess of 99 percent. At the
same plant, emissions from several dryers are sent to a condenser followed
by an adsorber. Overall control again is over 99 percent.^
Two adsorbers are also in use at another pharmaceutical plant. The
first adsorber works in series with a scrubber and a condenser. The system
is designed to remove ammonia, methanol, and methylene chloride vapors from
15
amination reactions. Overall system efficiency is designed at 99.9 percent.
The second adsorber is a small unit controlling methyl bromide emissions from
several sources in a minor production operation. Control efficiency is designed
at 99.9 percent J6
These examples serve to illustrate that carbon adsorbers can be very
effective VOC control devices. Units can be designed and operated at removal
efficiencies well above 90 percent.
As with all adsorption equipment, careful attention has to be paid to
regeneration timing. Instrumentation is needed to assure that breakthrough
1s detected. A common arrangement is two or more carbon beds 1n parallel.
During regeneration VOC's are desorbed with steam, warm air or inert gas, or
sometimes vacuum. Stripped vapors are usually condensed or absorbed and
residual gases vented through one of the working carbon beds. Possible points
of VOC re-emission are condensate receivers, water (condensed steam) drains,
and wastewater treatment basins.
4-10
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4.3.2 Applicability
While there will be exceptions, applicability of carbon control systems
can be summarized as follows:17 (a) controls organics with boiling points up
to 250°C and 1 ppm to 40 volume percent, (b) handles air flow rates of 10 cfm
to 200,000 cfm, and (c) adsorbs at temperatures up to 140°C. It is stressed
that these limits of applicability represent extremes and operation near the
the extremes may not be practical in some cases. For example, the Pharmaceutical
Manufacturers Association estimates that V0C concentrations above 5 volume
percent preclude normal use of carbon adsorption because of safety considerations.
At high V0C concentrations, the carbon bed temperature may rise to the
ignition point of the vapor stream unless an adequate cooling system is
employed. Also, a few compounds present special hazards which make adsorption
difficult or infeasible.
4.4 INCINERATION "" ~ -
Vapor incinerators, or afterburners, combust V0C in waste gases to carbon
dioxide and water. The two types of vapor incinerators in use are (1) direct-
fired, or thermal, and (2) catalytic.
Thermal incinerators depend upon flame contact and relatively high temperatures
to burn the combustible materials. Since most waste streams contain dilute
V0C concentrations, supplemental fuel is required to maintain the necessary
combustion temperatures. In general, factors which influence the efficiency
of combustion are: (1) temperature, (2) degree of mixing, (3) residence time
in the combustion chamber, and (4) type of V0C combusted.
Catalytic incinerators operate by preheating a contaminated gas stream to
a predetermined temperature (usually lower than in thermal incineration) and
then promoting further oxidation by bringing contaminants into contact with
a catalyst. The efficiency of catalytic incineration is a function of many
variables. These include surface area of the catalyst, catalyst type,
4-11
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uniformity of gas flow through the catalyst bed, type of VOC oxidized, oxygen
concentration, volume of gases per unit of catalyst, and operating temperature
of the unit. Efficiency decreases as the unit is used, and periodic catalyst
replacement is required. Some compounds, such as chlorides and silicones, also
may "poison" the catalyst and render it ineffective. At lower VOC concentrations,
the catalytic incinerator efficiency decreases markedly even at relatively high
discharge temperatures, such as 580°C (1100°F).18
4.4.1 Control Performance
The South Coast Air Quality Management District (formerly Los Angeles
County Air Pollution Control District) provided to EPA data from their compliance
testing program covering a period of several years. These data are shown in
Figure 4.3 as a plot of incinerator efficiency versus inlet organic concentration.
Most of the data are from incinerators on paint baking operations, although many
other industries are represented. Only those units operating at or above 90 percent
VOC destruction (on a mass basis) have been used in the graph. The cross hatched
band is meant to show the upward trend in efficiency as concentration is increased.
A general conclusion drawn from the plot is that control efficiencies greater than
90 percent can be and have been achieved on gas streams containing VOC concentrations
of 200-20,000 ppm.19
The data were also plotted for incinerator efficiency as a function of
operating temperature. In this instance, the data points were scattered and no
trend was obvious. However, nearly all operating temperatures were between 690°C
(1300°F) and 830°C (1550°F). At 690°C the average mass efficiency was 96 percent
and at 775°C (1450°F) it was 98 percent.^
Case studies identified by four thermal incinerator manufacturers indicate
that efficiencies of less than 95 percent were achieved, except in one case,
at temperatures of 730°C or lower. Conversely, efficiencies of 99 plus percent
2i
were achieved at temperatures of 760°C or greater.
4-12
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•••
fe
LU
a
—
<
a
CC
o
84
82
80
100
200
S00 1000 2000
INLET CONCENTRATION, ppm AS C02
• THERMAL AFTERBURNERS -
~ CATALYTIC AFTERBURNERS
LL
5000
10,000
20,000
Figure 1. Afterburner efficiency as a function of inlet concentration. From compliance test data
of southern California AQMD.
Figure 4-3.
-------
Although destruction efficiencies in thermal incinerators are influenced
by a number of variables, a review of literature and actual case studies mentioned
above allow the following generalizations to be made:
(1) 90 + percent VOC destruction can be achieved at an operating temperature
of 745°C (1400°F) and residence time of 0.5 seconds,
(2) 98 percent efficiency can be achieved at 800°C (1500°F) and 0.5 seconds, am
(3) 99 percent can be achieved at 860°C (1500°F) and 0.5 seconds residence
time.22
Concerning performance of catalytic incinerators, the fractional reduction
in pollutant concentration depends strongly on the amount of catalyst in a unit.
This dependence is such that conversions up to 90-95 percent can be attained
3 3
with reasonable catalyst volumes (i.e. 0.5-2.0 m catalyst per 1000 m of waste
gases). However, the catalyst volume required for very high conversion
(e.g. > 98 percent) generally makes catalytic incineration uneconomical.23
4.4.2 Applicability
Incinerators are not currently widely used to control vapor phase organic
emissions from synthesized drug production facilities. Part of the lack of
use may be due to the variability of waste gases that would be ducted to an
incinerator and the batch nature of the processes. Fluctuating flows and
pollutant concentrations may hamper safe and efficient operation. Therefore,
incinerators would most likely find application where relatively stable waste
gas flows can be established. Stability may be enhanced by ducting emissions from
several sources to a common control device.
Another potential disadvantage with incinerators is that heat recovery is
likely to be uneconomical because at pharmaceutical plants incinerators will be
relatively small and the. potential energy recovery correspondingly small,
especially when viewed in light of the costs for installing heat recovery
4-14
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equipment. In addition, the incinerator would generally run less than 24 hours
a day. In this case, heat recovery would be intermittent, thus decreasing its
utility.
A final consideration is that some compounds such as chlorinated organics,
amines, and sulfinated organics can cause corrosion in incinerators. Because
of this, these compounds are neither easily nor inexpensively incinerated.
To summarize, application of incineration is likely to be limited to
those situations which a number of different vents can be controlled or plant
operation is more or less continuous.
4-15
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4.5 REFERENCES
1. David A. Beck, EPA, "Trip to the Roche Pharmaceutical Plant in Manati, Puerto Rico,
memo to David R. Patrick, EPA, October 11, 1978.
2. David A. Beck, EPA, "Trip Report for a Plant Visit to Merck and Company's
Pharmaceutical Plant in Rahway, New Jersey," memo to David R. Patrick, EPA,
November 6, 1978.
3. Reference 2.
4. Letter from Dorothy Bowers, Pharmaceutical Manufacturers Association, to
Robert T. Walsh, EPA, May 15, 1978.
5. Stull, D. R., Physical Research Laboratory, Vapor Pressure Cox Chart No. 2.
6. Lange's Handbook of Chemistry, John A. Dean, Editor, 11th edition,
McGraw-Hill Book Company, New York, New York, 1973, pp. 10-31 to 10-45.
7. David A. Beck, EPA, "Trip to the Roche Pharmaceutical Plant in Manati, Puerto Rico,
memo to David R. Patrick, EPA, October 11, 1978.
8. Letter with attachments from Nancy Diaz, Eli Lilly and Company, Inc.
(Mayaguez, Puerto Rico), to Michael R. Clowers, EPA, August 11, 1978.
9. Letter with attachments from Gilbert C. Wagner, Pfizer, Inc., to
Don R. Goodwin, EPA, September 22, 1978.
10. Process Equipment Registration submitted by Pfizer, Inc., to the Connecticut
Department of Environmental Protection, January 28, 1975.
11. LeDuc, Marc F., Air Pollution Engineering Manual, second edition, for EPA,
May, 1973, p. 191.
12. David A. Beck, EPA, "Trip to the Eli Lilly Pharmaceutical Plant in Mayaguez,
Puerto Rico," memo to David R. Patrick, EPA, November 6, 1978.
13. Process Equipment Registrations submitted by Pfizer, Inc., to the Connecticut
Department of Environmental Protection, February 19, 1975, and March 31, 1975.
14. Reference 13.
4-16
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15. David A. Beck, EPA, "Trip to the Roche Pharmaceutical Plant in Manati,
Puerto Rico," memo to David R. Patrick, EPA, October 11, 1978.
16. Reference 15.
17. Wagner, N. J., Calgon Corporation, Introduction to Vapor Phase Adsorption
Using Granulated Activated Carbon, 1978.
18. Air Pollution Engineering Manual, U. S. Environmental Protection Agency,
Research Triangle Park, N. C„, May, 1973.
19. Vincent, Edward J., "Are Afterburners Obsolete?", paper presented to
National Association of Corrosion Engineers, January 19, 1978,
Atlanta, Georgia.
20. Reference 19.
21. Reference 19.
22. Novak, R., Hydroscience, Inc., Personal communication with R. E. White,
Hydroscience, May 4, 1978.
23. Rolke, R. W., et. al., Afterburner Systems Study, Shell Development Company,
EPA-R2-72-062, for the U. S. EPA, Office of Air Programs, August, 1972
4-17
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Section 5
COST ANALYSIS
5.1 INTRODUCTION
5.1.1 Purpose
This chapter presents capital and annualized cost estimates for equipment
to control VOC emissions from plants manufacturing synthesized pharmaceutical
products. Because the amount and type of emissions vary widely from plant to
plant, each control application will be unique. Therefore, in some situations,
control system construction materials, operating conditions, installation expenses
etc. will be different from those assumed in calculating costs for this chapter.
In instances where regulatory decisions hinge on the cost of control, it would
be proper to consider additional information that may more accurately reflect
control costs for the plant in question.
5.1.2. Scope
The preceding section described systems for controlling emissions from
the following sources in this industry: storage and transfer operations,
reactors, crystal1izers, centrifuges, filters, dryers, and distillation con-
densers. Table 5-1 lists the 14 techniques for controlling these sources that
are analyzed in terms of capital and operating costs in this section. The
table presents the emission sources and appropriate control techniques and their
expected VOC control efficiencies.
The control costs are developed for typical pharmaceutical operations
within typical size ranges. In practice, however, it may be possible for
one device to control more than one emission source.
Annualized emissions and their reductions cannot presently be quantified
because of the variety of pharmaceutical manufacturing operations, the many
kinds and concentrations of organic compounds, and the frequent use of batch
5-1
-------
TABLE 5-1. VOC EMISSION CONTROL OPTIONS IN THE PHARMACEUTICAL INDUSTRY,
PERCENTAGE OF EFFICIENCY
Emission source
Control technique
Storage
and
transfer
Reactors
Separation
operations
Dryers
Distillers
Conservation vent
5 - 20
N.A.
N.A.
N.A.
N.A.
Pressure tank vessel
50-95
N.A.
N.A.
N.A.
N.A.
Floating roof
90
N.A.
N.A.
N.A.
N.A.
Carbon adsorption
95
95
95
95
95
Thermal Incinerator
90 - 99
90 - 99
90 - 99
1
o
90 - 99
Thermal Incinerator
with heat recovery
90 - 99
90 - 99
90 - 99
a*
a*
i
o
90 - 99
Catalytic Incinerator
90 - 95
90 - 95
90 - 95
90 - 95
90 - 95
Catalytic Incinerator
with heat recovery
90 - 95
90 - 95
90 - 95
90 - 95
90 - 95
Hater-cooled condenser
30 - 70
70 - 90
70 - 90
70 - 90
70 - 90
Chi 11ed-wa ter-cooled
condenser
50 - 90
70 - 99
70 - 99
70 - 99
70 - 99
Chilled-brine-cooled
condenser
70 - 99
90 - 99
90 - 99
90 - 99
90 - 99
Freon-cooled condenser
70 - 99
95 - 99
95-99
95 - 99
95 - 99
Packed-bed scrubber
90 - 99
90 - 99
90 - 99
90-99
90 - 99
Venturl scrubber
90 - 99
90 - 99
90 - 99
90 - 99
90 - 99
a Includes crystalllzers, filters, and centrifuges.
N.A. - Not applicable.
-------
processing. As a consequence, cost-effectiveness ratios have not been devel-
oped. These limitations do not preclude the costing of control options based
upon their size and operating capabilities. The estimates are given for
retrofit installations, and all cost figures reflect mid-1978 dollars.
5.1.3 Bases for Capital Cost Estimates
Capital costs represent the initial investment required for retrofitting
a control system: equipment; materials and labor for installation, including
foundations, structural steel, instruments, piping, ducting, insulation, and
painting; and associated costs. Indirect expenses, such as contingencies,
contractor's fees, and tax allowances, are also included. The bases for
capital cost estimates are presented in Table 5-2. Additionally, capital cost
factors are presented in Table 5-4. Actual cost information has beer, derived
from sources in the literature;^"^ and from equipment vendors. ^ ^
5.1.4 Bases for Annualized Costs
Annualized costs represent the cost of operating and maintaining the
emission control system, including materials, utilities, and normal main-
tenance; as well as costs associated with capital recovery over the depreciable
life of the system. Table 5-3 presents the cost factors and methods that have
been used to estimate annualized costs for each control system. In general,
credits for VOC recovery have not been included for each control because they
cannot be defined on an annualized basis. The amounts of these credits depend
upon the value of the specific organic compound in use. However, in some
instances it was necessary in developing the annualized costs to quantify and
qualify the emissions.
5-3
-------
TABLE 5-2. BASES FOR CAPITAL COST ESTIMATES
All costs are expressed in mid-1978 dollars.
All costs include:
Basic control equipment
Auxiliaries, such as hoods and ducts
Installation and other labor
Contingencies
Contractor1s fee
General tax allowance
Other indirect costs.
Carbon adsorption systems have two carbon beds to
allow for continuous operation. One bed operates while
the other is regenerated. The initial carbon bedding
is included as a capital cost.
Initial catalyst is included in the capital cost of
catalytic incineration equipment.
The materials of construction for equipment, ducts,
piping, etc. are carbon steels, except for the packed bed
and venturi scrubbers which are fiberglass reinforced
plastic and cast iron, respectively.
5-4
-------
TABLE 5-3. BASES FOR ANNUALIZED COST ESTIMATES
Description
Unit cost
Basis for costs and other comments
Annualized costs
One-year period commencing mid-1978
Installation type
Retrofit
Yearly operating times
8 h/day, 5 days/wk, 50 wk/yr
16 h/day, 7 days/wk, 48 wk/yr
24 h/day, 7 days/wk, 48 wk/yr
Utilities:
No. 2 fuel oil8
$0.105/liter
{$0.396/gal}
Based on transport lots of
27,250 liters (7200 gal) de-
livered from Midwest terminal
Electricity
$0.0266/kWh
EPA-230/3-77-015b report cost
for iron and steel industry
Ha ter
$8.50/1000 it.3 , '
($0.24/1000 ft3
For municipal water plus an equal
amount for standard sewage. Where
applicable, a BODt surcharge of
$0.02/kg ($0 . 045/lb)
Steam
$B.99/Mg ,
($4.07/10 lb)
Based on 80S efficiency; includes
16% for facilities, maintenance,
depreciation, etc.
Operating labor
$8.66/h
Includes 20% for fringes
Maintenance:
Labor
$S.53/h
At 10% premium over operating labor
Material
$9. S3/h
Average (over life of equipment)
material costs equal to labor costs
Wise, maint., parts,
and material
10% of capital
cost for carbon
bed; 10% of capital
cost for catalyst;
351 of capital
cost for floating-
cover seal
Based on 5-year life
Capital recovery
factor
16.275% of
capital cost
10% interest rate and 10 years
equipment life
Taxes and insurance
2% of capital cost
Administration and
permits
2% of capital cost
Adjustment
credi tb
$0,105/1 iter
($0.396/gal)
Reclaimed solvent for use of diesel
or fuel oil; value of V0C saved due
to preventive measures on the basis
of ethanol $0.29/1 iter ($1.12/gal)
8 Assumed to be the only fuel used by all systems.
Where applicable.
5-5
-------
5.2 VOC EMISSION CONTROL IN PHARMACEUTICAL OPERATIONS
5.2.1 Plant Parameters
The control efficiencies of the add-on systems analyzed range from 5 to
99 percent, and each control device may show different efficiencies with
different applications. This variation is minor for carbon adsorption and
incineration, but is significant for control by pressure, cooling/condensing,
and scrubbing. The ability of carbon to adsorb various VOC is generally
between 6 to 8 kg (13 to 18 lb) of VOC per 100 kg (221 lb) of carbon; as a
result, carbon adsorption systems have a fairly uniform control efficiency of
95 percent. On the other hand, a brine-cooled cooler/condenser having brine
at -10°C (14°F) can control 99 percent of an ethanol VOC, but less than 25
percent of a methyl chloride VOC.
5.2.2 Capital Costs for VOC Emission Controls
Capital costs of various sizes of the 14 types of control systems are
presented graphically. These figures, which appear after the text, are ref-
erenced by number in the discussion that follows.
Capital costs of conservation vents with flame arresters are depicted in
Figure 5-1. The analysis is based upon 6.9 kPa (1.0 psi) pressure, 3.45 kPa
(0.5 psi) vacuum, typical tank dimensions, and a pumping rate of 6.3 liter/s
(100 gal/min). The vent, with the flame arrester, is the equipment item.
The costs of floating roofs for storage tanks, as shown in Figure 5-3,
are based upon the tank diameter. The floating roof with its seals is the
equipment item.
The costs of pressure vessels vary with the diameter and height of the
tank, as well as the wall thickness. Figure 5-5 presents the cost of pressure
vessels, based on tank size. For this analysis, it was assumed that average
5-6
-------
tank height equals two diameters, and that the shell and heads are 1.27 cm
(0.5 inch) thick. The vessel is the equipment item.
Carbon adsorption systems are sized according to volumetric gas flow
rate. Significant dilution is sometimes necessary for adequate recovery of
specific solvents.^ To allow for these large dilution requirements and for
the widely varying VOC concentrations considered in this study, costs
of carbon adsorption systems are presented for a large range of sizes. Figure
5-7 presents costs of carbon adsorption units having the capacity to treat VOC
rates from 40 to 1500 kg/h (88 to 3300 lb/h).
All of the systems are standard packages and are fully automatic, with twin
carbon beds. They will cycle through adsorption and desorption, and will
reclaim solvent from the desorbing steam by condensation followed by water
separation. The regenerative mode (desorption) takes less time than the
adsorption mode* to provide for continuous operation.. „-
Incinerators are sized according to the volume of emissions controlled in
units of Nm /h (scfm). Both thermal (Figure 5-9) and catalytic incinerators
(Figure 5-11) are analyzed on the basis of No. 2 oil being the only fuel.
Thermal incinerators are designed for 816°C (1500°F) operation. Catalytic
incinerators are designed for gas streams at 316°C (600°F) into the catalyst and
704°C (1300°F) out of the catalyst. Thermal incinerators are sized for 65 percent
primary heat recovery and catalytic incinerators for 38 percent primary heat
recovery, to minimize the fuel requirements for emissions at 25 percent of
22
lower explosive limit (LEL). The equipment is a package unit complete with
burner, controls, stack, and (where applicable) modular gas heat exchangers.
Cooling/condensing systems are sized for tons of cooling.
Ethanol was assumed as the VOC for purposes of heat exchanger sizing. Costs
-------
of water-cooled condensers are depicted in Figure 5-13. Their sizes range
from 1 to 30 tons of cooling at the condenser. A cooling tower, not
included in the capital cost, provides the water coolant. The condenser,
which is of carbon steel construction, is the only equipment item.
Systems that include air-cooled refrigeration units are represented in
Figures 5-15, 5-17, and 5-19. The three variations are chilled-water-cooled
condensers, chilled-brine condensers, and Freon-cooled condensers. As with
water-cooled condensers, the sizing basis for costing is 1 to 30 tons; but in
these cases, the tonnage of cooling is the nominal rating of the refrigerant
system (10°C (50°F) chilled water leaving the VOC condenser and 27°C (80°F)
air entering the refrigerant condenser). For the chilled-water-cooled condenser,
the coolant temperature is limited to 4.4°C (40°F) to prevent freezing. The
equipment items are a package refrigeration system (using a Freon refrigerant),
a VOC cooler/condenser, and an emissions precooler. The cost of the VOC heat
exchangers is small compared to the cost of refrigeration machinery.
Scrubber system capital costs are presented in Figures 5-21 and 5-23.
Packed-bed scrubbers are sized from the emission rate and the degree of control.
Ethanol VOC and 95 percent control were assumed. The liquid-to-gas ratio of 45
liters/28 Nm3 (12 gal/1000 ft3) required a 3.7 m (12 ft) bed depth. The
scrubbing liquor containing ethanol is recirculated. The system includes a
fiberglass scrubber, polypropylene packing, demister, fiberglass ducting,
blower, and recirculating pump. No water treating equipment is included.
Venturi scrubbers were sized on the same basis as packed-bed scrubbers.
Two scrubbers in series are required to achieve 95 percent control. The
liquid-to-gas ratio for each stage is 284 liters/28 Nm3 (75 gal/I000 ft3).
5-8
-------
The equipment includes two jet venturi scrubbers with separators and recircu-
lating pumps.
5,2.3 Annualized Costs of VOC Emission Controls
Annualized costs of the 14 control systems are presented graphically.
The costs are correlated with operating time and control system size. Credits
for VOC recovery have not been included in the annualized costs (except for
carbon adsorption systems), because they are not presently definable. How-
ever, the credits are significant for those controls—pressure systems, carbon
adsorption, cooling/condensing systems—that recover VOC of a quality com-
parable to the organic liquid. Neither the scrubbing nor the incinerating
systems recover VOC for reuse, because they destroy it by oxidation (com-
bustion in incinerators, or water treatment of scrubber effluent for removal
of organics). Figure 5-25 provides a guide for estimating VOC recovery
credits where they apply.
The annualized cost of conservations vents, as depicted in Figure 5-2, is
limited to maintenance and capital charges. As a consequence, annualized
costs are constant for the tank sizes analyzed. "If ethanol is assumed as the
VOC stored, and if the conservation vent is set for 6.9 kPa (1.0 psi) pressure
and 3.45 kPa (0.5 psi) vacuum, the standing losses at 27°C (80°F) are almost
eliminated. Credits for the VOC not emitted are dependent upon tank diameter,
but the credits may be significant enough to reduce the total annualized
cost to a credit.
The annualized cost of pressure vessels, shown in Figure 5-6, increases
with the size of the vessel. If recovery credits are considered, the annualized
costs will be reduced by an amount determined by the type of VOC being stored.
5-9
-------
The annualized cost of internal floating roofs increases with tank dia-
meter (Figure 5-4). These control devices are usually applied to larger tanks
where a pressure vessel would be too expensive. Although floating roofs do
not eliminate VOC emissions, the recovery credits for a VOC (ethanol) could
negate annualized costs.
The annualized cost of carbon adsorption systems is presented in Figures
5-8a and 5-8b. Values are based on the VOC emission rate, because adsorption
rate determines carbon-bed regeneration frequency and associated operations.
Adsorption of VOC to 8 weight percent of the carbon was assumed. It was further
assumed that the VOC was not water soluble, and that it could be recovered from the
desorbent steam by using process water. This recovered VOC may be realized as a fu ;1
valued at $0.11/kg ($0-05/1b). Annualized costs increase with plant operating
time. The value of reclaimed solvents cause annualized costs to decrease
rapidly as emission rates increase, resulting in negative operating costs. If
the VOC were not reclaimed but were discharged to an in-plant treating system,
operating at a BODg removal cost of less than the municipal rate of $0.027/kg
($0.06/1b) VOC, the cost would increase dramatically.
The annualized costs of incinerators with or without heat recovery, as
depicted in Figures 5-10 and 5-12, increase with size and hours of operation. To
determine the annualized costs, it was necessary to assume a VOC (ethanol) at
the specified 25 percent LEL.^ The fuel requirements are about equal for
catalytic and thermal incinerators with 38 percent and 65 percent (respectively)
primary heat recovery. The burner fuel requirements are also minimal. Fuel
savings are insufficient to offset the additional cost of heat recovery on the
following systems: thermal incinerators with 65 percent primary heat recovery
5-10
-------
3
operating at less than 6800 Nm /h (4000 scfm) for fewer than 6000 h/yr; and
catalytic incinerators with 38 percent primary heat recovery operating at more
than 1500 Nm /h (885 scfm) for more than 3000 h/yr. When incineration systems
without heat recovery are compared, the annualized costs of the catalytic
system are slightly greater. As the LEL is lowered, however, this advantage
declines.
Water-cooled condenser annualized costs are presented in Figure 5-14. The
curves show that costs increase as capacity and annual operating hours increase;
the increase mainly reflects the requirement for cooling water.
The annualized cost curves in Figure 5-16 for chilled-water-cooled con-
densers show a normal rise with increases in capacity and operating hours. If
the V0C is ethanol, its recovery could more than offset the annual cost of
operation.
Figures 5-18 and.5-20 present annualized costs of brine-cooled and Freon-
cooled condensers. Both have a normal increase in annualized operating costs
with increases in capacity and operating hours. Operating labor increases
with hours, and utilities increase with hours and capacity. As with the
chilled-water-cooled condenser, recovery credits from ethanol V0C could more
than offset the annual cost of operation.
The annualized costs of packed-bed scrubbers (Figure 5-22) increase
substantially with increases in operating hours and capacity; this is largely
caused by the costs of wastewater treatment from the discharge of BOD.
Venturi scrubber costs also increase substantially with increases
in operating hours and capacity. Compared with packed-bed scrubbers, the
annualized costs are higher: much higher for the larger capacities, because
5-11
-------
of larger volume costs for water and sewage. This larger volume is required
because jet venturi scrubbers are, in effect, single-stage units; whereas
packed-bed scrubbers use the more effective countercurrent contact.
5.3 COST-EFFECTIVENESS
The cost relationships developed in this section represent a wide range
of emission rates and pollutants. Emissions from pharmaceutical manufacture
vary significantly by operating time and by the size and number of process
operations. Because quantities of annual emissions cannot be estimated in a
manner consistent with the costing techniques used in this analysis, cost-
effectiveness was not measured for this industry.
5-12
-------
500r
400-
~ 300
O ¦ TURNKEY
~ • MAJOR EQUIPMENT
V)
©
u
200-
100-
19 38 57 76 95
(5) (10) (15) (20) (25)
TANK SIZE. »3 (103 gal)
NOTES:
114
(30)
133
(35)
.3 m3/s
1. BASED ON 6.
(100 gal/mln) pump-
ing rate.
2. BASED ON 6.9 kPa
(16 or) PRESSURE
AND 3.45 kPa (8 oz)
VACUUM.
Figure 5-1. Capital cost of conservation vents on storage tanks.
5-13
-------
125
1 1
1 1
1 " i
n
u
m
o
¦ry
00
fN.
100
—
o*
LARGE PLANT
(5376 h/yr)
AND 3 TANK
TURNOVER PER
H0HTH.
—
1
E
ft
O
o
75
~-
SHALL PLANT
(2000 h/yr)
AND 1 TANK
TURNOVER
PER MONTH.
o
Ul
p«g
50
—
—
<
z
<
25
n
—
1 1
1 1
i i
—-
19 38 57 76 95 114 133
(5) (10) (15) (20) (25) (30) (35)
TANK SIZE, w3(103 gal)
NOTES: 1. SEE FIGURE 5-25
FOR VOC RECOVERY
CREDITS.
Figure 5-2. Annualized cost of conservation
vents on storage tanks.
5-14
-------
O - TWNKEY
O - MAJOR EQUIPMENT
— ¦ EXTRAPOLATION
TANK DIAMETER, m (ft)
Figure 5-3. Capital cost of floating roof.
-------
O- LARGE PLANT (5376 h/yr)
~ ¦ SHALL PLANT (2000 h/yr)
— EXTRAPOLATION
CD
fc 10
"VI
O
u
D
(58)
(19)
<«)
(32)
TANK DIAMETER. » (ft)
Figure 5-4. Annualized cost of floating roof.
5-16
-------
O - TURNKEY
~ -MAJOR EQUIPMENT
k.
m
40-
3
O
I
X5
E
•J
»-
a
«c
(6.3) (8.5)
TANK SIZE, «i3 (103 gal)
(12.7)
(2.4)
(4.2)
(14.8)'
NOTES: 1. CARBON STEEL VESSEL
1.27 an (1/2 Inch)
SHELL AND HEMISPHERICAL
HEADS, NOZZLES, AND
SADOLES.
Figure 5-5. Capital cost of pressure vessels.
5-17
-------
O- LARGE PLANT (5376 h/yr)
~ • SHALL PLANT (2000 h/yr)
S 6
u
IW .
•si 5
3
I 4
«c
3-
2-
1-
0
8
(2.4)
16
(4.2)
24
(6.3)
32 ,
(8.5)
40
(10.6)
48
(12.7)
56
(14.8)
TANK SIZE, m3 (103 gal)
Figure 5-6. Annualized cost of pressure vessels.
5-18
-------
O • TURNKEY
~ - MAJOR EQUIPMENT
1100
1000
900
800
700
600
400
300
200
100
1250
(2750)
1500
(1300)
500
(1100)
1000
(2200)
250
(550)
750
(1650)
1750
(3350)
CAPACITY, kg/h (Ib/h) VOC
NOTE: 1. BASED ON GAS FLOM RATES OF
1.12 Nm^/mln per kg (18
scfm/lb).
Figure 5-7a. Capital cost of carbon adsorption systems
(large, fully automatic system for continuous operation).
-------
200
«s
o
¦o
"O
c
-------
CP
I
ro
o 100
¦o
75 100 125 150 175 200 225 250 275 300 325 350 375 400
(165) (220) (275) (330) (385) (440) (495) (550) (605) (660) (715) (770) (825) (880)
VOC EMISSIONS, kg/h (lb/h)
NOTES:
O- OPERATES 24 h/day- 2,
7 days/wk-48 wk/yr,
OR 8064 h/yr
~ = OPERATES 8 h/day-
5 days/wk- 50 wk/yr,
OR 2000 h/yr 3.
O- OPERATES 16 h/day-
7 days/wk-48 wk/yr,
OR 5376 h/yr
BASED ON 425 Nm7m1n
(15,000 scfm) FOR ALL
VOC CONCENTRATIONS.
COST INCLUDES VOC RECOVERY CREDIT.
IF NOT RECLAIMED ADD $0.023/kg
($0.01/Ib) VOC FOR LOST CREDIT
AND $0.027/kg ($0,012/16) VOC FOR
WASTEWATER TREATMENT.
EXAMPLE: 300 kg/h x
5376 h/yr x $0.05/kg
- $80,600 ~ $37,500
(FROM CHART).
Figure 5-8a. Annualized cost of carbon adsorption systems (medium).
-------
35
£ 30
0
25
c
§ 20
oo
£ 15
1
E
-5
-10
1
1
1
0» OPERATES 24 h/day-
7 days/wk-48 wk/yr;
OR 8064 h/yr
~» OPERATES 8 h/day--
5 days/wk-50 wk/yr,
3 OR 2000 h/yr
—
\
CL <3
\ X
\ N. £
0- OPERATES 16 h/day-
7 days/wk-48 wk/yr,
_ OR 5376 h/yr —
t=
\ \ ec
\ \ UJ
c
a.
UJ
\ \ a.
K \p
c
<->
z
UJ
UJ
%S\
\
1
.
1
10-
25 50 75 100
(35) (110) (165) (220)
VOC EMISSIONS, kg/h (Ib/h)
NOTES: 1. BASED ON 85 NnT/m1n
(3000 scfm) FOR ALL
VOC CONCENTRATIONS.
i. COST INCLUOES COST
OF VOC RECLAIMED AT
$0.023/kg ($0.01 lb)
AND COST OF WASTEWATER
TREATMENT AT $0.027/kg
($0.012/1b) OF VOC.
3. EXAMPLE: 30 kg/h *
5376 h/yr x $0.05/kg
- $8060~ $19,000
(FROM CHART) .
Figure 5-8b. Annualized costs of carbon
adsorption systems (small).
5-22
-------
t
« 351
5
0-
5 250
15
0»
7 2«»
•9
tS ISO
I
si ioo
t—
+-*
O* 1UMIKEV
~ • MAJOR EQUIPMENT
VJlTH 65*
-o-
WITH 65* PRIMARY HEW RECOVERY g
WITHOUT HEAT RECOVERY
-a
(1.2)
6 10
(3.5) (5.9)
CAPACITY, Nm3/h (scfmj
14
(8.2)
18
(10.6)
NOTE: 1. 0IL-MRED FOR
OPERATION AT
25 * IEI,
Figure 5-9a. Capital cost of thermal incineration systems (large).
-------
1 r
O* TURNKEY
O- MAJOR EQUIPMENT
— - EXTRAPOLATION
UTTH 651 PRIMARY HEM RECOVERS
. —o
0 WITHOUT HEAT RECOVERY
g WITH 65% PRIMARY HEAT RECOVERY
utthoiiT HEAT RECOVERY
--o
_J I I | L_
,???> .600. 100C 1400
.www I4W
018) (353) (558) (8Z4)
CAPACITY, Nm3/h (TO3 scfm)
NOTES: 1. OIL-FIRED FOR
OPERATION AT
25X LEL.
Figure 5-9b. Capital cost of thermal incineration
systems (small).
5-24
-------
T
0« OPERATES 24 h/day-
7 days/wk-48 wk/yr,
OR 8064 h/yr.
~- OPERATES 8 h/day-
5 days/wk-50 wk/yr,
OR 2000 h/yr.
OPERATES 16 h/day-
7 days/wk-48 wk/yr,
OR 5376 h/yr.
10
WITHOUT HEAT
RECOVERY
. WITH 651 PRIMARY
HEAT RECOVERY
2
(1.2)
4
(2.4)
6
(3.5)
8
(4.7)
10
(5.9)
CAPACITY, 103 Nm3/h (103 scfm)
NOTES: 1. OIL-FIRED FOR
OPERATION AT
251 LEL.
Figure 5-10. Annualized cost of thermal incineration systems.
5-25
-------
300
TURNKEY
MAJOR EQUIPMENT
250
200
WITH 381 PRIMARY
HEAT RECOVERY
WITHOUT -
HEAT RECOVERY
ISO
£ 100
50-
2 6 10 14 IB
11.IB) (3.5) (5.9) (8.2) , (10.6)
CAPACITY, 103 Nm'/h (103 scfm)
NOTE; 1. OIL-FIRED
Figure 5-lla. Capital cost of catalytic incineration systems (large).
-------
150
—<0"-"
-o-
O- TURNKEY
O- WWQR EQUIPMENT
—» EXTRAPOLATION
£ 100
WITH 385 PRIMARY
HEAT RECOVERY
WITHOUT HEAT
RECOVERY
50 -
"Tooo"
(588)
600
(353)
1400
(824)
CAPACITY, Ntn /h (scfii)
NOTE: 1, SEE FIGURE 5-1 It
FOR LARGER SUES,
2. OIL-FIRED.
Figure 5-11b. Capital cost of catalytic
incineration systems (small).
5-27
-------
10
00-
SO-
SO-
70-
60-
50 "
40-
~
3D*
20-
10-
I
OPERATES 24 h/day-
7 days/*k-48 *k/yr,
OR 8064 h/yr
OPERATES 8 h/day-
5 tfays/wk-50 wk/yr,
OR 2000 h/yr
OPERATES 16 h/day-
7 days/*k-48 wk/yr,
OR 5376 h/yr
,-o
.-a
WITHOUT HEAT
RECOVERY
•WITH 38X
PRIMARY HEAT
RECOVERY
2 4 6 8 10
(1.18) (2.35) (3.53) <4.7) (5.88)
CAPACITY, 103 Hn3/h (103 $cf»)
NOTES: 1. OIL-FIRED FOR
OPERATION AT
251 LEL.
Figure 5-12. Annualized cost of catalytic
incineration systems.
5-28
-------
1100
VI
i
r\>
to
O- TURNKEY
D ¦ MAJOR EQUIPMENT
£ 700
10
15
ZO
?5
30
CAPACITY, tons cooling (at condenser)
NOTES:
1.
2.
Figure 5-13. Capital cost of water-cooled condensers
BASED ON 1?.6 RJ/h
(12,000 8tu/h) per ton.
BASED ON CONDENSING
ETHANOL VAPOR AT 78'C
(172*F), WITH 2rC
(75"F) HATER FROM A
COOLING TOMER.
-------
Z200r
2000-
1800-
u 1600
m
o
"O
GO
N
Oh
1400
1200
I 1000
8 800
a
600
400
200
OPERATES 24 h/day-
7 days/wk-48 wk/yr,
OR 8064 h/yr
OPERATES 16 h/day-
7 dSys/wk-48 wk/yr.
5376 h/yr,
OPERATES 8 h/day-
5 days/wk-50 wk/yr,
2000 h/yr.
» To 15 20"
CAPACITY, tons cooling (at condenser)
NOTES: 1. BASED ON 12.6 KJ/h
(12,000 Btu/h) per ton.
2. BASED ON CONDENSING
ETHANOI VAPOR AT 7B*C
(172'F), WITH 24*C
(75*F) MATER FROM A
COOLING TOMER.
3. SEE FIGURE 5-25 FOR
c- c ^ ^ ^ , VOC RECOVERY CREDITS.
Figure 5-14. Annualized cost of water-cooled
condensers
5-30
-------
I
170
5
M 50-
O « TURNKEY
~ - MAJOR EQUIPMENT
T
CONDENSER ONI*
TO W
CAPACITY,tons cooling (nominal)
Ratio of net tons available for cooling/nominal tons
refrigeration for 27°C (80°F) air to refrigerant
condenser and various brine (or chl1 led water)
temperatures from the VOC condenser.
Ratio
Tons Cooling
Net/Nominal
Temperature from
VOC condenser
oF oc
1.00
0.80
0.50
0.25
50
40
10
-10
10
4.4
-12.2
-23
NOTES: 1. BASED ON 12,6 HJ/h
(12,000 Btu/h) per ton.
2. Nominal tons of cooling
is machine rating for
10°C (50°F) water leaving
the VOC condenser and
270C (80°F) air into the
refrigerant condenser.
Figure 5-15. Capital cost of chilled-water-cooled
VOC condensers and water chiller
-------
- m
5
I 50
40
00
7 30
k!0
10
1 I 1
o- OPERATES 24 h/d»y-
1 I !
— 7 days/wk-48 wk/yr.
_
OR 8760 h/yr
— O• OPERATES 8 h/day-
5 d«ys/wk-50 wk/yr,
or 2000 h/yr.
0- OPERATES 16 h/day- —
7 days/wk-48 wk/yr, — —
— OR 5376 h/yr—
— — O —
°^l i i
I i 1
10 15
CAPACITY, tons cooling (nominal)
20
25
30
Ratio of net tons available for cooling/nominal tons
refrigeration for 27°C (80°F) air to refrigerant
condenser and various brine (or chilled water)
temperatures from the VOC condenser.
NOTES: 1.
2.
Ratio
Temperature from
VOC condenser
BASEO OH 12.6 NJ/h
(12,000 Btu/h) per ton.
See Figure 5-25.for
VOC recovery credits.
Met/Nominal
°c
1.00
SO
10
0.80
40
4.4
O.SO
10
-12.2
0.25
-10
-23
Figure 5-16.
Annualized cost of chilled-water-cooled
VOC condensers and water chiller
-------
O - TURNKEY
~ • MAJOR EQUIPMENT
TJ
C
*
a
o
5
¦
a.
5
CONDENSER ONLY
Ratio of net tons available for cooling/nominal tons
refrigeration for 27°C (80°F) air to refrigerant
condenser and various brine (or chilled water)
temperatures from the VOC condenser.
10 15 20
CAPACITY, tons cooling (nominal)
25
30
Ratio
Tons Cooling
Net/Nominal
Temperature from
VOC condenser
°F °C
1.00
0.80
0.50
0.25
50 10
40 4.4
10 -12.2
-10 -23
Figure 5-17. Capital cost of cKilled-brine-cooled
VOC condenser and brine chiller
NOTES: 1. BASEO ON 12.6 MJ/h
(12,000 Btu/h) per ton.
2. Nominal tons of cooling
is machine rating for
10°C (50°F) water leaving
the VOC condenser and
27°C (80°F) air into the
refrigerant condenser.
-------
O « OPERATES 24 h/day-
1 days/Mk 48 wk/yr,
OR 8760 h/yr
O - OPERATES 8h/day-
5 daysM-50 wk/yr,
OR 2000 h/yr
O" OPERATES 16 h/day-
7 days/wk-48 wk/yr,
OR 5376 h/yr
10 15 20
CAPACITY, tons cooling (nominal)
25
30
NOTES: 1. BASED ON 12.6 MJ/h
(12,000 Btu/h) ptr ton.
2. See Figure 5-25 for
VQC recovery credits.
Ratio of net tons avallable for cooling/nominal t
refrigeration for 27°C (80°F) air to refrigerant
condenser and various brine (or chilled water)
temperatures from the VOC condenser.
Figure 5-18. Annualized cost of chilled brine-cooled
VOC condenser and brine chiller
Ratio
Tons Coolfng
Net/Nominal
Temperature from
VOC condenser
OF <>C
1.00
0.80
0.S0
0.25
50
10
10
-10
10
4.4
-12.2
-23
-------
O • TURNKEY
~ - MAJOR EQUIPMENT
CONDENSER ONLY
10 15 20
CAPACITY, tons cooling (nominal)
Ratio of net tons available for cooling/nominal tons
refrigeration for 27°C (80°F) air to refrigerant condenser
and various Freon temperatures to VOC condenser.
Ratio
Tons Cooling
Net/Nominal
Temperature to
VOC condenser
°f oc
.40
.25
-10
-22
-23
-30
NOTES: 1. BASED ON 12.6 MJ/h
(12,000 Btu/h) per ton.
2. Nominal tons of cooling
is machine rating for
chiller service with
10°C (50°F) water leaving
the VOC condenser and 29°C
(80°F) air into refrigerant
condenser.
Figure 5-19. Capital cost of VOC condenser chilled with Freon and Freon
refrigeration system
-------
i.n
i
CO
o>
t-
m
VI
8
40
35
30
25-
20-
15-
10-
O ¦ OPERATES 24 h/dav-
7 days/wk-48 wk/yr,
OR 8760 h/yr
~ - OPERATES 8 h/day-
5 d«ys/wk-50 wk/yr,
OR 2000 h/yr
O - OPERATES 16 h/day -
7 days/wk - 48 wk/yr
or 5376 h/yr
10 15 20
CAPACITY, tons cooling (nominal)
Ratio of net tons available for coolirtg/nontlnil tons
refrigeration for 27°C (8Q°F) air to refrigerant condenser
and various Freon temperatures to V0C condenser.
NOTES: 1. BASED 0*1?.6 NJ/h
(12,000 Btu/lb) per ton.
2. SEE FIGURE 5-25 FOR VOC
RECOVERY CREDITS.
Ratio
Tons Cooling
Net/Nominal
.40
.25
Temperature to
VOC condenser
°F °C
-10
•ZZ
-23
-30
Figure 5-20. Annualized cost of VOC condenser cooled
with Freon and freon"refrigeration system
-------
O » TURNKEY
~ - MAJOR EQUIPMENT
TJ
» 30
CO
o>
s/y
i_>
(10.6)
(1.18)
(3.53)
(5.88)
(2.35)
(4.7)
(8.2)
(7.06)
CAPACITY, 103 Nm3/h (103 scfm)
Figure 5-21. Capital cost of packed bed scrubbers.
-------
i 1 1 1 1 r
O- OPERATES 24 h/day-7 days/wk-
48 wk/yr, OR 8064 h/yr.
O- OPERATES 8 h/day-5 days/wk-
50 wk/yr. OR 2000 h/yr.
O- OPERATES 16 h/day-7 days/wk-
48 wk/yr, OR 5376 h/yr.
i—r
i—I—r
2
(1.18)
4
(2.35)
6
(3.53)
8
(4.7)
10
(5.88)
12
(7.06)
CAPACITY, 103 Nm3/h (103 scfm)
14
(8.2)
16
(9.4)
18
(10.6)
NOTES: 1. BASEO UPON GAS STREAM
EMISSIONS AT 21*C (70"F)
AND SATURATED WITH
VOC (ETHANOl).
2. ANNUALIZED COSTS INCLUDE
WASTEWATER TREATMENT OF
800'S AT $0.027/kg ($0.06/1b)
VOC.
Figure 5-22. Annualized costs of packed bed scrubbers.
4
-------
O- TURNKEY
O- major tquiwrettT
"O
O
(5.88)
(7.06)
(4.7)
(10,6)
CAPACITY, <103 Nnt3/h {TO3 scfm)
Figure 5-23. Capital cost of venturi scrubbers.
-------
700
O • OPERATES 24h/day-7days/wk-48 wfc/yr, OR 8064 h/yr. '
O- OPERATES 8 h/day-5 days/wk-50 wk/yr, OR 2000 h/yr,
O • OPERATES 16 h/day-7 days/wk-48 wk/yr, OR 5376 h/yr.
600
400
100
(5.88)
(3.53)
(7.06)
(8.2)
(2.35)
(9.4)
(1.18)
(4.7)
CAPACITY, )03 Nm3/h (103 scfm)
Figure 5-24. Annualized cost of venturi scrubbers.
-------
160
y>
L
tO
m 140
o
¦o
-o
c
(O
in
3
O
CO
r>.
cr>
r—
I
X)
u
lO
01
>>
ac
o
120
100
80
60
40
20
1 1 1
o = OPERATES 24 h/day -
1
_ 7 days/wk - 48 wk/yr,
OR 8064 hr/yr.
~ = OPERATES 8 h/day -
5 days/wk - 50 wk/yr,
OR 2000 h/yr
0= OPERATES 16 h/day -
n ~
7 days/wk - 48 wk/yr, .
— OR 5376 h/yr.
—
T~ I I
1
(0)
10
(22)
20
(44)
30
(66)
40
(88)
50
(110)
UNCONTROLLED V0C EMISSIONS, kg/h (lb/h)
NOTE: CHART BASED ON 95%
RECOVERY OF $0.37/kg
($0.17/1b) ETHAN0L
V0C.
Figure 5-25. Credits to annualized cost from condensation
and pressure control systems.
-------
Table 5-4. Capital Cost Factors*
Cost Items
Conservation Pressure Floating Carbon
Vents Tanks Roofs Adsorbers Incinerators Condensers
Scrubbers
Direct Costs
Equipment
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Instrumentation
0.10
0.05
0.05
0.05
0.05
Piping
0.39
0.30
0.16
0.05
0.10
0.15
Electrical
0.04
0.05
0.05
0.05
0.05
Foundations
0.20
0.07
0.02
0.05
0.05
Structural
0.10
1.10
0.07
0.10
0.05
0.05
Sitework
0.04
0.04
0.01
0.01
0.01
Insulation
0.03
0.05
Painting
0.03
0.09
0.01
0.01
0.01
0.01
Ducts
0.10
0.20
0.10
Offsite Oil Storage
0.18
DIRECT COST SUBTOTAL
i n
1.39
1.81
2.19
1.58
1.67
1.47
1.47
I
•I*
Indirect Costs
For all control systems,
indirect.costs include the
following items (listed as a
percentage of Direct Cost
Subtotal):
0.97
1.27
1.53
1.11
1.17
1.03
1.03
Field Overhead 15
Contractor's Fee 10
Engineering
Freight
Taxes
Allowance for'
shake-down
Spares
Testing
Contingency
Interest during
construction
10
2
3.5
2
2.5
2.5
20
percent
percent
percent
percent
percent
percent
percent
percent
percent
As a fraction of equipment costs
2.5 percent
Tn<:tallprl Cn<:t Fart.nr
?.3fi
3.08
3.72
2.69
2.84
2.50
2.50
-------
REFERENCES FOR SECTION 5
1. Reference Deleted.
2. Boland, R.F., T.E. Ctvrtnicek, J.L. Delaney, D.E. Earley, and Z.S. Kahn.
Screening Study for Miscellaneous Sources of Hydrocarbon Emissions in
Petroleum Refineries. EPA-450/3-76-041. 1976. 91 pp.
3. GARD, Inc. Capital and Operating Costs of Selected Air Pollution Control
Systems. EPA Contract No. 68-02-2072. Niles, Illinois, May 1976.
4. Control of Hydrocarbons from Miscellaneous Refinery Sources. Draft
Document. U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina, May 27, 1977.
5. Control of Volatile Organic Emissions from Existing Stationary Sources.
Volume 1: Control Methods for Surface-Coating Operations. EPA-450/2-76-
028, (OAQPS No. 1.2-067). November 1976.
6. Control of Volatile Organic Emissions from Existing Stationary Sources.
Volume II: Surface Coating of Cans, Coils, Paper, Fabrics, Automobiles,
and Light-Duty Trucks. EPA-450/2-77-008, (OAQPS No. 1.2-073). May 1977.
7. Doll, C.K. Contact Report on Project No. 3925-L (8): Eli Lilly, Mayaguez,
Puerto Rico. Midwest Research Institute, Kansas City, Missouri.
8. Personal Communications between Dr. R. Quaney, U.S. Environmental Pro-
tection Agency/SASD, Research Triangle Park, North Carolina, and J.M.
Bruck, PEDCo Environmental, Inc., Cincinnati. February and March 1978.
9. Industrial Gas Cleaning Institute. Report of Fuel Requirements, Capital
Cost and Operating Expense for Catalytic and Thermal Afterburners. EPA-
450/3-76-031. Stamford, Connecticut, September 1976.
10. Industrial Gas Cleaning Institute. Study of Systems for Heat Recovery
from Afterburners. EPA Contract No. 68-02-1473, Task No. 23. Stamford,
Connecticut, October 1977.
11. Manzone, R.E., and D.W. Oakes. Profitably Recycling Solvents from Process
Systems. Hoyt Manufacturing Corp., Westport, Massachusetts, October
1973.
5-43
-------
12. Personal Communication between D. Oakes, Hoyt Manufacturing Corp., West-
port, Massachusetts, and A.C. Knox, PEDCo Environmental, Inc., Cincinnati.
February 1978.
13. Personal Communication between K.A. Napier, Oxy-Catalyst, Inc., Research-
Cottrell, Inc., West Chester, Pennsylvania, and A.C. Knox, PEDCo Environ-
mental, Inc., Cincinnati. February 1978.
14. Personal Communication between L. Taborsi, Varec Equipment Co., Cleve-
land, and J.M. Bruck, PEDCo Environmental, Inc., Cincinnati. March 1978.
15. Personal Communication between H. Douglas, Chicago Bridge and Iron Co.,
Cleveland, and J.M. Bruck, PEDCo Environmental, Inc., Cincinnati. March
1978.
16. Pilulik, A., and H.E. Diaz. Cost Estimating for Major Process Equipment.
Chemical Engineering 84 (21):107-122, 1977.
17. Personal Communication between Mrs. Farley and N. Chapman, Edwards
Engineering, Pompton Plains, New Jersey, and A.C. Knox of PEDCo Environ-
mental, Inc., Cincinnati. November 1978.
18. Personal Communication between C. Pauletta of C. E. Air Preheater Co.,
Wellsville, New York, and A.C. Knox of PEDCo Environmental, Inc.,
Cincinnati. August 1978.
19. Personal Communication between B. Connery of Doyle & Roth, Inc., New
York City, and A.C. Knox of PEDCo Environmental, Inc., Cincinnati.
November 1978.
20. Personal Communication between L. Maglietto of Basco, Inc., Buffalo,
and A.C. Knox of PEDCo Environmental, Inc., Cincinnati. November 1978.
21. Personal Communication between B. Chirona of Croll-Reynolds, Inc., Westfield,
New Jersey, and A.C. Knox of PEDCo Environmental, Inc., Cincinnati.
November 1978.
22. National Fire Protection Association. National Fire Codes: Volume 1,
Flammable Liquids. Boiler-Furnances, Ovens, Appendix Section 86A-92.
1970-71.
5-44
-------
6.0 ADVERSE EFFECTS OF APPLYING THE
CONTROL TECHNOLOGY
This chapter addresses energy and environmental effects resulting from
application of four major control techniques discussed in chapters 3 and 4.
6.1 CONDENSATION
The amount and type of energy required for a condenser will depend
primarily on the type of system employed. In general, energy is required
for powering the coolant refrigeration system, for transporting the gas stream,
and for circulating the coolant. Energy for refrigeration depends on the type
and operating temperature of coolant used which in turn is determined by the
characteristics of waste gases condensed. Chapter 5 contains more information
on energy use and costs for condensers.
A condenser will create few secondary environmental problems. Since the
condensers use energy, there will be air pollutants emitted during energy
generation. Use of contact condensers will increase plant water requirements
and create an additional load on a wastewater treatment plant. Most condensers
installed as retrofit control will be surface type rather than contact type.
6.2 SCRUBBING
Energy is needed to power scrubber pumps, cooling water system, and blower.
Amounts of energy needed vary widely and depend on the following variables:
waste gas VOC concentration, absorbent flow rate, gas flow rate, and type of
scrubber used. Venturi scrubbers normally use more energy than tray tower or
6-1
-------
packed bed scrubbers of comparable size.
Adverse environmental effects from operation of scrubbers include secondary
air pollutants from electricity generation, increased water usage and increased
VOC laden wastewater load to sewer or treatment plant.
6.3 ADSORPTION
The energy required for an adsorption system includes a supply of steam,
eir, or inert gas and sometimes a vacuum pump for carbon regeneration and
electricity to pump cooling water and to power a gas blower. Adsorber
energy requirements are dependent on waste gas flow rate, temperature of
the waste gas to the adsorber, the type of VOC(s) treated, and VOC concentration.
Figure 6-1 shows a plot of adsorber energy use versus waste gas flow rateJ
The graph represents systems with the following characteristics:
1. dual fixed bed adsorber operating at 38°C,
2. steam regeneration and solvent recovery with condenser and decanter,
3. and VOC concentration at 25 percent LEL (lower explosive limit)
or 15 percent LEL (for a 50/50 benzene-hexane mixture) and 77°C.
When steam is used to desorb the organic vapors from the adsorption
bed, the majority of the total energy required is for the production of this
steam. The amount of steam needed is approximately 3-6 lb steam/lb
(3-6 kg/kg) organic vapor adsorbed. Steam regeneration has the advantage
of leaving the bed wet, providing a heat sink for the heat of adsorption
on the next cycle. Alternatives to steam regeneration are non-condensable
gas regeneration and vacuum stripping. Energy requirements for this system
are for heating and transporting the non-condensable gas, usually air.
Waste gases exiting the process are usually hotter than the optimum
adsorption temperature. Energy in the form of a cooling water system is
needed to cool this waste gas stream. For Figure 6-1 cooling water requirements
"5
were approximately 3 gallons per hour/SCFM (400 liters per hour/Nm- per
2
minute).
6-2
-------
3.5.
a.
r
m
o
cc
Ui
z
Ui
2.5
1.5
0.5
_l_
X
10 15 20
GAS FLOW TO ADSORBER. 103 SCFM
25
30
Figure 6-1.
Energy Requirements for Adsorption-Solvent
Recovery System
6-3
-------
A blower is used to overcome the pressure drop encountered by the gas
moving through the adsorption bed. The only requirement for the blower is electrical
power. The amount of electricity consumed depends upon the type and configuration
of the packing.
There will be some secondary impacts from use of an adsorption unit. If
a steam desorption cycle is used and the recoverable VOC are soluble in water, then
the condensate from desorption will contain VOC. This is an additional
wastewater stream that increases treatment plant or sewer load.
Secondary air pollutants will result from generation of electricity and
steam used to power an adsorber. The amount of air pollutants created depends
on the type of fuel used in the power plant.
If carbon is not regenerated, spent carbon must be disposed of and will add
to the amount of solid waste produced by the plant.
6.4 INCINERATION
Energy requirements for a typical incinerator system includes supplemental
fuel and a gas blower to convey the waste gases. The amount of supplemental
fuel needed depends on waste gas temperature, VOC concentration in the gas,
incineration temperature, and type of heat recovery employed. Table 6-1 lists
3
fuel requirements for several different incineration situations.
Possible adverse environmental effects from incineration include generation
of sulfur oxides, nitrogen oxides, and carbon monoxide during combustion of the
waste gas. In catalytic systems, the catalyst must be replaced periodically as
performance decreases over a period of time. This creates an additional solid
waste problem for the plant.
6-4
-------
Table 6-1. BURNER REQUIREMENTS FOR
INCINERATORS IN 10° BTU/HR3
THERMAL INCINERATORS 0 percent LEL 5 percent LEL 15 percent LEL 25 percent LEL
No Heat Recovery
5,000 scfm 8.00 7.10 5.32 3.56
15,000 scfm 24.00 21.31 15.98 10.66
Primary Heat Recovery
(35 percent efficient)
5,000 scfm 5.07 4.19 2.42 0.68
15,000 scfm 15.40 12.71 7.34 1.96
CATALYTIC INCINERATORS
;« No Heat Recovery
i
5,000 scfm 2.95 2.95 2.95 2.53
15,000 scfm 8.85 8.85 8.85 7.12
, Drimary Heat Recovery
£ (35 percent efficient)
i 5,000 scfm 1.91 1.63 1.11 0.19
« 15,000 scfm 5.73 4.89 3.32 0.57
aBased on 70°F waste gas temperature; 1400°F outlet temperature for thermal
incinerator; 1200°F outlet temperature for catalytic incinerator. Waste gas is toluene.
6-5
-------
6.5 REFERENCES
1. MSA Research Corporation, Hydrocarbon Pollutant Systems Study, for EPA,
January, 1973, Appendix C.
2. Reference 1.
3. CE Air Preheater, Industrial Gas Cleaning Institute, Report of Fuel
Requirements, Capital Cost and Operating Expense for Catalytic and Thermal
Afterburners, EPA-450/3-76-031, September, 1976.
6-6
-------
7.0 COMPLIANCE TESTING METHODS AND
MONITORING TECHNIQUES
A realistic regulatory approach is a combination of operating and
equipment standards for significant VOC sources within this industry.
Compliance methods and monitoring techniques then, will simply assure that the
operating and equipment standards are being maintained.
7.1 OBSERVATION OF CONTROL EQUIPMENT AND OPERATING PRACTICES
Regulations expressed as equipment and operating standards can be enforced
by verifying that the equipment has been designed and installed properly and that
it is being operated properly.
7.1.1 Adsorption
Most carbon adsorption instrumentation has been used to program the
regeneration cycles. The cycle is usually adjusted so that regeneration is
started before breakthrough occurs in the carbon bed. A sensing device should be
used, to assure that breakthrough does not go undetected. The monitor
should be connected to an alarm bell, light, or device to alert operating
personnel immediately that breakthrough has occurred.
7.1.2 Condensation
Temperature sensors can be placed in the exit gas stream from a condenser
as an indicator of how well the condenser is operating. Indicated temperature
ran be checked against design temperature and conditions observed during tests.
7-1
-------
7.1.3 Incineration
All incinerators should be equipped with temperature indicators. Records
may be required in the range of 490°-820°C (1200-1800°F) for thermal
incinerators, 204°-426°C (400-800°F) for catalytic units. Residence time and
turbulence are fixed by incinerator design and should be checked before a
unit is built. Aging, masking, or poisoning of catalyst in catalytic units
would be reflected in a decreased temperature downstream of the bed.
7.1.4 Scrubbing
Scrubbers should be equipped with flow meters to measure the flow rate of
the scrubbing medium. The pressure drop across the scrubber may also be a useful
parameter to measure, especially for venturi scrubbers. Pressure drops
deviating from design conditions can indicate plugging problems, channeling of
packing, and other abnormal situations that may reduce VOC removal efficiency.
As an alternate to using flow meters on systems recirculating the scrubbing
medium, the back pressure may be measured. This coupled with the pressure
drop across the scrubber will provide suitable indication of flow.
7.2 EMISSION TESTS
Emission measurement tests of off-gas streams from carbon adsorbers,
scrubbers, or condensers may occasionally be necessary to evaluate the control
efficiency of a system. Measurements of velocity and flow rates may be
determined for larger stacks using EPA Tests Methods 1 and 2. For stacks
less than 0.3 meter (12 inches) diameter, other flow determining methods
may have to be used to provide reasonable accuracy. Gas chromatographic
techniques for organic solvents are discussed in EPA 450/2-76-028, "Control
of Volatile Organic Emissions from Existing Stationary Sources, Volume I:
Control Methods for Surface Coating Operations," November, 1976.
7-2
-------
APPENDIX A
TABULAR PRESENTATION OF SOLVENT
DISPOSITION DATA SUBMITTED BY THE
PHARMACEUTICAL MANUFACTURERS ASSOCIATION
-------
TABLE A-l„ COMPILATION OF DATA SUBMITTED BY THE PMA FROM
26 MANUFACTURERS OF ETHICAL DRUGS1
(metric tons)
Pi spositiori
ijrpc vt
Volatile Organic
Compound
Annual
Purchase
Air
Emissions
Sewer
Incineration
Contract
Haul
Disposal*
Product
Total
Solvent Recovery
Methylene Chloride
10,000
5,310
455
2,060
2,180
-
5
82,320
73,400
Skelly Solvent B
(hexanes)
1,410
410
23
980
-
-
-
1,500
90
Methanol
7,960
2,480
3,550
1,120
410
30
340
1,117,600
-
Toluene"1"
6,010
1,910
885
1,590
1,800
_
-
30,040
23,850
+
Acetone
12,040
1,560
2,580
4,300
770
-
2,210
52,100
40,760
Dimethyl Formamide^
1,630
1,350
60
380
120
-
-
7,000
5,100
Ethanol
3>
13,230
1,250
785
915
200
-
10,000
20,740
7,570
L, +
Isopropanol
3,850
1,000
1,130
1,150
470
25
3,090
10,770
3,880
Amy! Alcohol1"
1,430
775
-
-
0
.
9
77,700
76,900
Ethyl Acetate
2,380
710
1,110
480
80
-
-
3,110
715
Chloroform
500
280
23
-
175
17
-
1,710
1,210
X
Benzene
1,010 •
270
350
150
80
-
90
21,440
20,500
Ethyl Ether
280
240
12
-
30
-
-
111,100
110,800
*f"
Methyl Isobutyl
Ketone
260
260
-
-
-
_
65
6,470
6,160
Carbon
Tetrachloride
1,850
210
120
1,510
-
-
-
1,850
-
X
Xylene
3,090
170
510
1,910
140
3
12,140
9,400
-------
9 TUV
,670
,510
,840
360
,040
145
125
12
,040
300
,760
TABLE A-l„ COMPILATION OF DATA SUBMITTED BY THE PMA FROM
26 MANUFACTURERS OF ETHICAL DRUGS
(metric tons)
Disposition __
Annual Air Contract
Purchase Emissions Sewer Incineration Haul Disposal* Product Total
260 170 30 60 ... 6,720
135 135 - - ... 135
530 120 - 100 475 - - 26,370
285 120 165 - ... 3,800
480 105 45 230 ... 2,230
195 90 100 - - - - 550
320 85 30 5 130 - 110 1,390
85 40 40 - - - 225
35 30 6 - - - 165
4 4 ... 4
25 12 12 - - 37
930' 12 770 - - 160 1,980
1,265 8 550 - - 410 1 ,265
95 7 - 90 95
30 5 20 - 1 25
750 4 210 535 ... 5,510
43 2 - - 41 - - .43
-------
I HDL L rt-I . uunr 1LH I 1UI1 Ur L/M I M iUUI'l 1 I I r. U DI I ML n*IH rKUII
FROM 26 MANUFACTURERS OF ETHICAL DRUGS
(metric tons)
ijryc ui
Volatile Organic
Compound
Annual
Purchase
Air
Emissions
Sewer
Incineration
Contract
Haul Disposal*
Product
Total
Solvent Recovery
o-Dichlorobenzene
60
1
60
-
-
-
7,120
7,060
Diethyl Carbonate
30
1
20
-
-
7
30
-
Blendan (Amoco)
530
-
-
-
-
530
530
-
Ethyl Bromide
45
-
45
-
-
-
7,215
7,170
Cyclohexylamine
3,930
-
-
-
-
3,930
3,930
-
Methyl Formate
415
-
310
-
50
60
1,550
1,130
Formamide
440
-
290
-
110
30
440
-
"^Ethylene Glycol
60
-
60
-
-
-
120
60
Diethyl amine
50
50
3
-
-
-
350
300
Freons
7,150
6
-
-
-
7,145
7,150
-
Diethyl-ortho
Formate
54
-
21
-
-
33
54
-
Pyridine
3 •
-
3
-
-
-
3
-
Polyethylene
Glycol 600
3
-
-
-
-
3
3
-
TOTALS
85,170
19,190
14,380
* 17,480
7,350 72
27,700
1,636,100
441,320
Source - 26 member companies of the Pharmaceutical Manufacturers Association (PMA) reported these drita whic.li Hioy
feel represent 85 percent of the volatile organic compounds used in their operations; these repurUnq
companies account for approximately 53 percent of the 1975 domestic sales of ethical pharmaceuticals.
*Deepwell or landfill.
•|«
Annual disposition does not closely approximate annual purchase.
-------
APPENDIX B
EQUATIONS FOR ESTIMATING
EMISSION RATES FROM
PROCESS EQUIPMENT
-------
APPENDIX B
VOC EMISSION CALCULATIONS
B.I INTRODUCTION
The following methods have been developed to calculate the uncontrolled
emissions from the following pharmaceutical process operations. These process
operations are:
I.
Charging
II.
Evacuation (Depressuring)
III.
Nitrogen or Air Sweep
IV.
Heating
V.
Gas Evolution
VI.
Vacuum Distillation
VII.
Drying
Some simplifying assumptions have been made; the general assumption for
of the following calculations is that the Ideal Gas Law applies. In applying
these equations, it is important to use the correct number of operating hours
for calculating daily or annual emission estimates.
No- 1: n =RT
where: n = # of pound moles;
P = absolute pressure, iri inn lly;
V = volume, in ft.3;
T = temperature, in °K; (°K = °C + 273)
R = gas law constant, 999
i ft 3 mm Hq x
lb moles}
The Ideal Gas Law is used to calculate the lbs/hr of VOC emitted, as follows:
Equation No. 2: Se = ^
where: Se = lbs/hr of VOC emitted;
Pi = vapor pressure of VOC at T, in mm Hg;
Xi = mole fraction of VOC in liquid mix;
Vr = rate of displacement, in ft3/hr;
B-l
-------
mm Hq ft
R = 999 lb mole UK
T = temperature in °K;
MWi = molecular weight of VOC, in lbs/lb mole.
The mole fraction, Xi, above must be included in the case of a liquid mix.
Mole fraction is calculated as follows:
Equation No. 3:
Xi = m°1es of i in liquid mix
~ total moles of liquid mix
where: Xi = mole fraction of i;
i = denotes the VOC in question
For one component systems, Xi = 1.
The vapor pressure, Pi, is calculated using Antoine's equation or taken
from tables of vapor pressure.
Equation No. 4: L°910Pi = a ~ ^cTTT^
where: Pi = vapor pressure of the VOC (mm Hg);
Ti = temperature of the air containing the VOC
vapor (°C);
a,b,c = Antoine's equation constants.. See Lange's
Handbook of Chemistry
Vapor Pressure Tables
2
Vapor pressures from Perry's are interpolated or extrapolated using
a Cox chart. An example is included as Figure 4-1.
B.2 METHODS AND CALCULATIONS
I. Charging
This method can be used to calculate emissions from a vessel containing
a liquid VOC when a liquid is charged into the vessel.
Assumptions - The volume of gas displaced from the vessel is equal to the
volume of liquid charged into the vessel. The air displaced
from the vessel is saturated with the VOC vapor at the exit
temperature. (Note: if data are available to calculate
concentration, then this can be used in place of
saturation.)
B-2
-------
Calculations -
¦3
1. Calculate the rate of air displacement in ft /hr:
Equation No. 5: Vr = Lr (0.134 ft3/gal) (60^?-)
where: Vr = the rate of air displacement, in ft /hr;
Lr = liquid pumping rate, in gpm.
2. Determine the mole fraction of each VOC in the vessel during the
pumping, Xi, using Equation No. 3.
3. Calculate the vapor pressure of each pure VOC, Pi, using
Equation No. 4.
4. Calculate the lbs/hr of each VOC emitted, Se, using Equation No. 2.
II. Evacuation (Depressuring)
This method is used to calculate emissions from the evacuation (or
depressuring) of any vessel containing a VOC and a "noncondensable." Usually
the vessel will be a still and the "noncondensable" will be air or nitrogen.
Assumptions - The absolute pressure in the vessel decreases linearly
with time. There is no air leakage into the vessel.
The composition of the VOC mix does not change during
the evacuation (or depressuring) and there is no
temperature change. . The air displaced is saturated
with the VOC vapor at the vessel temperature.
Calculations -
1. Calculate the mole fraction,Xi, for each VOC in solution using
Equation No. 3.
2. Calculate the vapor pressure,Pi , of each VOC at the vessel
temperature using Equation No. 4.
3. Calculate the initial volume of the air in the vessel:
B-3
-------
where: Vi = the initial air volume in the vessel,
ft3 (standard);
Z (PiXi) = the sum of the products of the vapor pressures
and the mole fractions of each VOC in the
solution;
Pa-j = initial pressure, in mrnHg,
760 = atmospheric pressure, in mmHg.
3
F$ = free space in the still, in ft.
4. Calculate the final air volume in the vessel:
w _rPa„ - Z (PiXiflt
vf —Ifs
= the final air volume in vessel, in ft (standard);
where: Pa£ = final air pressure in the vessel, mmHg.
5. Calculate the rate of air removal from the vessel:
Vr = yj - yf
t
where: Vr = the rate of air removal from the vessel,
in ft^/hr;
t = time of evacuation of vessel, in hrs.
6. Calculate initial ratio of air to total VOC vapor:
n_. _ 760 - Z (PiXi)
I(PIXI)
where: Ri = moles air
moles VOC
7. Calculate final ratio of moles air to moles total VOC vapor:
R
_ Pa0 - Z (PiXi)
f , Z. (PiXi)
moles air
where: Rf = moles VOC
8. Calculate the average ratio of moles air to moles total VOC
VaP°r: Ra = Ri + Rf
2
3
9. Calculate volume of total VOC vapor discharged, ft /hr:
VRS = -RI
3
where: VRS = VOC emission from the system, ft /hr.
10. Calculate the emission rate, Se, for each VOC in lbs/hr using
Equation No. 2 substituting VRS for Vr and use pressure of one
atmosphere.
B-4
-------
III. Nitrogen or Air Sweep
This method is used to calculate emissions when nitrogen, air, or
Dther "noncondensable" is used to purge or sweep a vessel or other device.
Assumptions - The nitrogen gas exiting the vessel is saturated with
VOC vapor at the exit temperature.
Calculations -
3
1. Calculate the rate of nitrogen sweep in ft /hr:
Equation No. 6: Vr-j = Ns x 60 min/hr
3
where: Vr-j = the rate of nitrogen sweep in ft /hr,standard;
3
Ns = the rate of nitrogen sweep in ft /min,standard.
2. Calculate the mole fraction, Xi, for each VOC using Equation No. 3.
3. Calculate the vapor pressure, Pi, for each VOC at the exit
temperature using Equation No. 4.
3
4. Calculate the rate of total gas displaced from the vessel, ft /hr.
Equation No. 7:
Vr2 = Vr-j
^—I
L760 - £(PiXi )J
3
where: Vr9 = rate of gas displaced from vessel, in ft /hr, standard;
3
Vr-j = rate of nitrogen sweep, in ft /hr;
I(PiXi) = the sum of the products of the vapor pressures and
mole fractions for each VOC;
760 = vapor pressure of nitrogen sweep , in mmHg.
5. Calculate the rate of VOC emission in lbs/hr, Se, for each VOC
using Equation No. 2 substituting Vr2 for Vr.
IV. Heating
This method is used to calculate the emissions from the heating of a
still containing a VOC and a "noncondensable." usually air.
B-5
-------
Assumptions - The moles of air displaced from the still are a result
of (1) the expansion of air upon heating and (2) an
increase in VOC vapor pressure. The moles of air displaced
from the receiver are equal to the moles of air displaced
from the still. The air displaced from the receiver is
saturated with VOC vapor in equilibrium with the VOC
mixture in the receiver at the temperature of the
receiver.
Calculations -
1. Calculate the mole fraction, Xi, for each VOC in the still using
Equation No. 3.
2. Calculate the vapor pressure, Pi, of each pure VOC at the initial
temperature (T-|) using Equation No. 4.
3. Calculate the initial pressure of the air in the still:
Equation No. 8: Pa-j = 760 - Z(PiXi)y^
where: Pa-| = the initial air pressure in the still in mmHg ;
Z(PiXi)T = the sum of the products of the vapor pressures
1 and the mole fractions of each VOC at the initial
temperature;
760 = atmospheric pressure,in mmHg.
4. Calculate the vapor pressure, Pi, of each pure VOC at the final
temperature (T2) using Equation No. 4.
5. Calculate the final pressure of air in the still:
Equation No. 9: Pa£ = 760 - Z(PiXi)T^
where: Pa2 = final air pressure in the still, in mmHg.s;
Z(PiXi)T = sum of the products of the vapor pressures
2 and the mole fractions for each VOC at the final
temperature;
760 = atmospheric pressure, in mmHg.
B-6
-------
6. Calculate the moles of air displaced to the receiver (and to
the environment):
Equation No. 10:
where:
V
" if
Pa, Pag
(_I _ _1)
1 2
(n-,-n2) = number of lb moles of air displaced
to the receiver;
o
V - volume of free space in still, in ft. ;
gas law constant, 999 ^ ^ ^
R
Pa-j = initial air pressure in still, in. tnmHg;
Pag = final air pressure in still, in, mmHg;
T-j = initial temperature in still, in. °K;
T2 = final temperature in still, in. ok.
7. Calculate the number of lb moles of VOC vapor displaced:
2(PiXi)TR
ns
760 - S(PiXi)TR
(n] - n2)
where:
ns = pound moles of VOC vapor displaced from
the receiver;
I(PiXi)jn = sum of products of vapor pressures and mole
fractions for each VOC at the temperature
of the receiver.
8. Calculate the lbs of each VOC vapor emitted, Se:
Equation No. 11:
(Se}. - (n£) MWs. (X.)
where: (Se).. = lbs of VOC (i) vapor emitted;
n = number of lb moles of all VOC vapor
emitted;
= molecular weight of VOC (i);
Xi = mole fraction of VOC (i) in the vapor.
V. Gas Evolution
This method is used to calculate emissions when a gas is generated as
the result of a chemical reaction. The gas comes into contact with one or more
VOC, usually solvents, and is saturated.
B-7
-------
- The gas is saturated with VOC vapor at the exit
temperature.
Calculations -
1. Determine the rate of gas evolution, Wg, in Ibs/hr, from the
stoichiometry of the chemical reaction, and the reaction time.
3
2. Calculate the rate of gas evolution in ft /hr:
Equation No, 12:
where:
= Ws-
3
Vr-j = the rate of gas evolution, in ft /hr;
R = the gas law constant, 1.314 f^moTe °k
T = the temperature at the exit, in °K (°C + 273);
Wg = the rate of gas evolution,in Ibs/hr;
P = the pressure in the vessel, in. atm.;
MWg = the molecular weight of the gas, in lb/lb mole.
3. Calculate the mole fractions, Xi, of the VOC in solution using
Equation No. 3.
4. Calculate the vapor pressures, Pi, of the pure VOC at the exit
temperature using Equation No. 4.
3
5. Calculate the rate of gas displacement in ft /hr:
Equation No. 13:
Vr2 = Vr]
760
,760 x J(PiXi),
where: Vr9 = rate of gas displacement, in ft /hr;
3
Vr-j = rate of gas evolution, in ft /hr;
760 = atmospheric pressure, in mmHg;
E(PiXi) = the sum of the products of the vapor
pressure and the mole fraction of each
VOC at the exit temperature.
6. Calculate the VOC emission rate, Se, in Ibs/hr using Equation No. 2.
B-8
-------
VI. Vacuum Operations
This method is used to calculate emissions from vacuum operations.
Air leaks into the system and becomes saturated with the VOC vapor at the
receiver temperature and is subsequently discharged by the jet to the
atmosphere.
The air leak rate is best determined by closing off the jet from the
still, condenser, and receiver and noting the rise in absolute pressure
over a short period of time. The air leak rate can then be calculated
using Equation No. 14 below. Maximum air leakage has also been estimated
3
for "commercially tight systems" for various system volumes and pressures.
Assumptions - The air that leaves the system is saturated with solvent
vapor at the receiver temperature.
Calculations -
1. Calculate the air leak rate into the system:
Equation No. 14: vr1 = Fs ^p2^~qP1^
Vr, = air leak rate, in ft^/hr (standard);
where: 1
Fs = total free space under vacuum, in ft.^;
Pi = absolute pressure at start of test, in mmHg;
?2 = absolute pressure at end of test, in mmHg;
t = time of test, in hrs;
T = temperature of still, in °K;
273 = temperature at standard conditions, in ok.
2. Calculate the rate of VOC emissions, Ibs/hr:
Equation No. 15:
Se ¦ MMs Vrl / * s?$tCT - A
V P system - Ps X
where: Se = rate of VOC emission, in lbs/hr;
P system = absolute pressure of receiver, 1n mmHg;
Ps c vapor pressure of the VOC at the receiver
temperature, in mmHg;
MWs = molecular weight of VOC, in lb/lb mole;
359 = the volume that 1 lb mole of gas occupies
at standard conditions, 1n ft.3.
B-9
-------
3. If leak rate is obtained in Ibs/hr from reference 3, calculate
VOC emission Ibs/hr:
Nation 16: Se ° (j ggg . „s " 1)
where; La = leak of air into the systems, in Ib/hr;
29 = molecular weight of air, in lb/lb mole.
VII. Prying
This method is used to calculate VOC emissions from either batch or
continuous drying operations. Although it is possible to determine emissions
from an analysis of the dryer off-gas, it is usually simpler and more
accurate to use a material balance.
Assumptions - Samples of the product before and after the dryer
are analyzed for VOC content.
Calculations -
1. Calculate the rate of VOC emissions, Ibs/hr:
Equation No. 17:
«. _ B^PS1 - fS2 ^
Se T^TtTS1 Wmr$zJ
where: Se * rate of VOC emission, Ibs/hr;
B = weight of batch (dry), lbs;
t * time of drying operation, hrs;
PSj » percent of VOC in wet material into dryer;
P$2 ¦ percent of VOC in less wet material from dryer.
B-10
-------
B.3 REFERENCES
1. Lange's Handbook of Chemistry, John A. Dean, Editor, 11th Edition,
1973, McGraw-Hill Book Company, New York, New York, pp. 10-31 to 10-45.
2. Chemical Engineers Handbook, Perry and Chilton, Editors, Fifth Edition,
1973, McGraw-Hill Book Company, New York, New York, p. 3-54.
3. Power, R. B., 'Steam-Jet Air Ejector," Hydrocarbon Processing and
Petroleum Refiner, March, 1964, Vol. 43, No. 3., p. 59.
B-ll
-------
APPENDIX C
Aids to Calculating Storage
Tank Emissions
-------
APPENDIX C
Below are graphs depicting variation in adjustment factor (C) and
turnover factor (KN) for a range of situations. These graphs are presented
to aid the reader in making emission calculations for various storage situations.
The graphs are taken from the EPA publication entitled "Supplement No. 7
for Compilation of Air Pollutant Emission Factors, Second Edition" printed
in April 1977.
1.00
o
£ -80
0
< .80
1 -40
0
Figure 4.3-10. Adjustment factor (C) for
small diameter tanks.
/
/
/
/
/
~
4
<-
10 20 30
TANK DIAMETER M FEET
C-l
-------
1.0
0.8
0.6
a4
0.2
30
WOTfc ro
Tt
A M TU*NO>
AN on LESS.
reus m
kn -i.o
0 100 200 300 400
ANNUAL THROUGHPUT
TURNOVERS PER YEAR ¦ —
TANK CAPACTTY
Turnover factor (K|sj) for fixed roof tanks.
C-2
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