II .DRAFT
{€**<¦'
Wc'V>.
EMISSION CONTROL OPTIONS FOR THE
SYNTHETIC ORGANIC CHEMICALS MANUFACTURING INDUSTRY
Prepared for
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
ENVIRONMENTAL PROTECTION AGENCY
Research Triangle Park, North Carolina
HYDROSCIENCE. INC.»9CM| EXECUTIVE PARK DRIVE • K NOX VIL LE. TENNESSEE 3 7919 • (615) 6 90-32H
EMERSON NJ •WESTWOOO N J • WALNUT CREEK. C A * ARllNGTON. TX
EPA Contract No. 68-02-2577
Storage and Handling Report
D. G. Erikson
October 1978
-------
iii
CONTENTS
I. PREFATORY AND INTRODUCTORY MATERIAL I-I
II. CHARACTERIZATION AND DESCRIPTION II-l
A. Introduction II-l
B. Storage Tanks 11-2
C. Loading and Handling 11-10
D. References 11-12
III. EMISSIONS III-l
A. Sources III-2
B. Calculations III-3
C. Industry Emissions III-7
D. References 111-16
IV. CONTROL TECHNOLOGY IV-1
A. Storage Tanks IV-1
B. Loading and Handling IV-9
C. References IV-11
V. IMPACT ANALYSIS V-l
A. Environmental and Energy Impacts V-l
B. Control Cost Impact V-12
C. References V-28
VI. ASSESSMENT VI-1
A. Summary VI-1
B. Supplemental Information VI-2
C. Reference VI-4
APPENDIX A - EMISSION CALCULATION SUPPLEMENTS A-l
APPENDIX B - COST ESTIMATE DETAILS AND CALCULATIONS B-l
-------
V
FIGURES
Number Page
II-l Number of Tanks and Storage Volume vs Tank Size H-4
II-2 Number of Tanks and Storage Volume vs Tank Type and Use II-5
II-3 Average Number of Turnovers of VOC Storage Tanks vs
Tank Size II-8
IV-1 Typical Flotation Devices and Seals for Internal Floating
Roof IV-2
IV-2 Floating-Roof Tank Primary and Secondary Closure Seals IV-3
IV-3 Fluidic-Type Tube Seal with Secondary Seal IV-4
V-l Cost Effectiveness of Controlling Emissions by Retrofitting
Existing Fixed-Roof Tanks with Floating Roofs V-16
V-2 Cost Effectiveness of Installing New Tanks (Floating Roof
vs Fixed Roof) for Controlling Emissions V-17
V-3 Cost Effectiveness of Controlling Emissions by Refrigerated
Vent Condenser Added on to Fixed-Roof Tank V-19
V-4 Cost Effectiveness of Controlling Emissions (98%) by
Installing New Pressure Vessel vs New Floating-Roof Tank V-23
V-5 Cost Effectiveness of Controlling Emissions (100%) by
Installing New Pressure Vessel vs New Floating-Roof Tank V-24
B-l Precision of Capital.Cost Estimate B-3
B-2 Installed Capital Costs for Tanks B-4
B-3 Installed Capital Costs for Small Tanks B-5
B-4 Installed Capital Costs for Refrigerated Vent Condensers B-6
-------
vii
TABLES.
Number Page
II-l Number of Tanks and Storage Volume by Tank Size II-3
II-2 Number of Tanks and Storage Volume by VOC Vapor Pressure II-6
II-3 Vapor Pressure and Volume of Synthetic Organic Chemicals
Shipped
II-4 Time Required for Shipments
III-l Uncontrolled 1977 Storage Tank VOC Emissions by Tank Size
and Type
XII-2 Uncontrolled 1977 Storage Tank VOC Emissions by Material
Vapor Pressure and Tank Type
III-3 Uncontrolled 1977 Loading and Transportation VOC Emissions
by Material Vapor Pressure
III-4 Current Storage VOC Emissions by Tank Size and Type
1-11
I-11
II-8
II-9
11-11
11-12.
III-5 Current 1977 Storage VOC Emissions: by Vapor Pressure and
Tank Type 111-13
III-6 Current 1977 Loading and Transportation VOC Emissions
by Material Vapor Pressure 111-15
V-l Model Parameters Used for Assessing Impacts of Industry
Storage Tanks V-2
V-2 Uncontrolled VOC Emissions from Model Fixed-Roof Tanks V-2
V-3 VOC Emission Reduction from Fixed-Roof Tanks by Installing
Internal Floating Roofs V-3
V-4 Model Parameters for Assessing Impacts of Refrigerated Vent
Condensers V-5
V-S VOC Emission Reduction from Fixed-Roof Tanks Before and After
Refrigerated Condenser Add-on V-5
V-6 Energy Impact from Refrigerated Vent Condenser V-5
V-7 VOC Emissions from Model Floating-Roof Tanks V-6
V-8 VOC Emission Reduction from Floating-Roof Tanks by Installing
New Pressure Vessels V-8
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viii
TABLES (continued)
Number Page
V-9 Model Parameters for Assessing Impacts from Secondary Seals on
Open-Top Floating-Roof Tanks V-9
V-10 VOC Emissions from Open-Top Floating-Roof Tanks V-9
V-ll VOC Emission Reduction from Secondary Seal Installation on
Open-Top Floating-Roof Tanks V-9
V-12 Control Parameters for Model Loading-Terminal Refrigeration
System V-ll
V-13 VOC Emissions from Model Loading-Terminal Before and After
Addition of Controls V-ll
V-14 Cost Factors Used to Compute Annual Costs V-13
V-15 Installed Capital and Operating Costs for Internal-Floating-
Roof Tanks V-13
V-16 Cost Effectiveness for Internal Floating-Roof on Fixed-Roof
Tank (New and Retrofitted) V-15
V-17 Cost Effectiveness for Refrigerated Vent Condenser on Model
Fixed-Roof Tanks V-18
V-18 Installed Capital and Operating Costs for Pressure Vessels V-21
V-19 Cost Effectiveness for New Pressure Vessel Versus New
Floating-Roof Tank V-22
V-20 Installed Capital and Operating Costs for Secondary Seals
(New and Retrofitted) V-25
V-21 Cost Effectiveness of Secondary Seals V-25
V-22 Installed Capital and Operating Costs for Model Loading-
Terminal Control Systems V-27
V-23 Cost Effectiveness of Loading-Terminal Control Systems V-27
A-l Paint Factors for Fixed-Roof Tanks A-2
A-2 "K" Factors for Floating-Roof Tanks A-3
A-3 "S" Factors for Loading Loss Calculations A-4
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ix
ABBREVIATIONS AND CONVERSION FACTORS
EPA policy is to express all measurements in agency documents in metric units.
Listed below are the International System of Units (SI) abbreviations and con-
version factors for this report.
To Convert From
Pascal (Pa)
Joule (J)
Degree Celsius (°C)
Meter (m)
Cubic meter (m3)
To
Atmosphere (760 mm Hg)
British thermal unit (Btu)
Degree Fahrenheit (°F)
Feet (ft)
Cubic feet (ft )
Multiply By
9.870 X 10"6
9.480 X 10~4
(°C X 9/5) + 32
3.28
3.531 X 101
Cubic meter (m )
Barrel (oil) (bbl)
6.290
Cubic meter (m3)
Gallon (U.S. liquid) (gal)
2.643
X
102
Cubic meter/second
Gallon (U.S. liquid/min)
1.585
X
104
(m3/s)
(gpm)
Watt (W)
Horsepower (electric) (hp)
1.340
X
io"3
Meter (m)
Inch (in.)
3.937
X
101
Pascal (Pa)
Pound-force/inch (psi)
1.450
X
10"4
Kilogram (kg)
Pound-mass (lb)
2.205
Joule (J)
Watt-hour (W*h)
2.778
X
io"4
Standard Conditions
68°F = 20°C
1 atmosphere (Torr) - 101,325 Pascals
PREFIXES
Prefix
T
G
M
k
m
M
Symbol
tera
giga
mega
kilo
mi Hi
micro
Multiplication
Factor
12
10
109
106
103
10-3
10-6
Example
1 Tg = 1 X 1012 grams
9
1 Gg = 1 X 10 grams
1 MW = 1 X 106 grams
1 km = 1 X 103 meters
' 1 mV = 1 X 10~3 volt
1 jjg = 1 X 10"6 gram
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1-1
I. PREFATORY AND INTRODUCTORY MATERIAL
(This section to be supplied by EPA.)
-------
II-l
II. CHARACTERIZATION AND DESCRIPTION
A. INTRODUCTION
The synthetic organic chemical manufacturing industry (SOCHI) is a segment of
the domestic chemical industry that produces the 350 to 400 basic and intermed-
iate organic chemicals used to produce other, finished chemicals and products.
Organic chemicals not included in the SOCMI are refinery by-products, coal tar
and other "naturally" derived organic chemicals, polymers, and end-use (finished)
organic chemicals.
The data base for the synthetic organic chemicals manufacturing industry (SOCHI)
for this report was compiled from state emissions inventory questionnaires (EIQ)
and information obtained from plant site visits.1
Texas and Louisiana state EIQs supplied the bulk of the data base, which cov-
1 2
ered approximately 4000 tanks used for the storage of organic chemicals. '
The use of only two state EIQs to supply 80% of the storage tank- data base was
reasonable since production in these states is approximately 65% of the total
SOCHI production.3
The data collected included various tank characteristics, type, use, and con-
tents. This information was assembled on forms and stored in a computer data
base developed by Hitre Corp., Hetrek Division, HcClean, VA, whoused the MRI
system 2000 to manage the data base. The program has the capability of computing
emissions from each tank and of characterizing the data base in terms of various
4
input parameters, such as tank size, vapor pressure, tank type, and emissions.
Extrapolation of the data base to the SOCHI was done on a weight basis. It was
estimated that the 4000 tanks represented approximately 20% of the total SOCHI
production. Individual tanks in the data base were assigned to a specific
process at a given site. The production from each process was summed to yield
a total production for the data base. A comparison of the reported SOCHI produc-
tion^ with the industrial production derived, from the data base indicated that
a scaleup factor of 5.0 was required for completion of the SOCHI storage charac-
terization projection for 1977.
-------
II- 2
B. STORAGE TANKS
There are three basic designs for tanks storing volatile organic compounds
(VOC) in the SOCMI: fixed roof, floating roof [open or covered (internal)],
and pressure (low or high) vessel. These tanks are usually loaded by submerged
or bottom filling and are unloaded into marine vessels, tank cars, tank trucks,
or pipe lines. It is estimated that 20,300 VOC storage tanks, each with a
capacity of 3.8 m3 or greater, are located throughout the United States and
3 3
Puerto Rico. The total VOC storage volume is estimated to be 11,650 X 10 m
(see Table II-l and Fig; II-l). Approximately 14,800 fixed-roof tanks make up
3 3
61% (7100 X 10 m ) of the total storage volume, 700 floating-roof tanks make
3 3
up 20% (2340 X 10 m ), and 4800 pressure tanks make up the remaining 19% (2210
X 103 m3).
The tanks are used for storing a variety of materials: raw materials, inter-
mediates, final product, and/or usable by-products, as well as waste tars,
residues, and nonusable by-products. It is. estimated (see Fig. II-2) that of
the total number of tanks the feed storage tanks comprise 23%, or 27% of the
total storage volume; product storage tanks comprise 45%, or 53% of the total
storage volume.,- intermediate tanks comprise 29%, or 17% of the storage volume;
and waste storage tanks comprise 3% of both the total number of tanks and the
total storage volume.
The vapor pressure of the material stored is a major factor in the choice of
tank type used. Table II-2 gives the number of tanks and the total volume by
vapor pressure of the chemicals stored in each of the three basic tank types.
Fixed-roof tanks are normally used for storing materials with vapor pressures
up to 34.5 kPa, floating-roof tanks when vapor pressures are in the range of
6.9 to 34.5 kPa, and pressure tanks when vapor pressures are greater than 51.7
kPa. Other factors, e.g., material stability, safety hazards, health hazards,
and multiple use, can also affect the choice of tank type for a particular
organic chemical.
Small tanks are commonly used for high-turnover service, such as intermediate
storage. Very large tanks are used for low-turnover service, such as terminal
product storage. A correlation has been found between tank turnovers and tank
size. In general, as the tank size increases, the turnovers decrease. For
very small tanks (less than 35 m3) turnovers can approach 700 per year. Very
-------
Table II-l. Number of Tanks and Storage Volume by Tank Size*
Fixed Roof Floating Roof Pressure Vessel Total
Tank ,
(m3
Size
)
No. of
Tanks
Storage Volume
(m )
No.of
Tanks
Storage Volume
(to )
No.of
Tanks
Storage Volume
No.of
Tanks
Storage Volu
(m )
4 to
45
5,105
124,000
0
0
1, 370
34,000
6,475
158,000
45 to
91
3,010
205,000
10
600
785
54,000
3,805
259,600
91 to
189
1,980
282,000
40
6,000
1,190
153,000
3,210
441,000
189 to
379
1,375
396,000
85
26,000
450
119,000
1,910
541,000
379 to
946
1,560
968,000
140
86,000
330
209,000
2,030
1,263,000
946 to
1893
975
1,416,000
95
140,000
410
473,000
1,480
2,029,000
1893 to
3785
520
1,428,000
125
331,000
125
283,000
770
2,042,000
3785+
290
2,278,000
175
1,752,000
125
887,000
590
4,917,000
Total
14,815
7,097,000
670
2,341,600
4,785
2,212,000
20,270
11,650,600
3 n
*See ref. 1 (includes only tanks with capacity greater than 3.8 m ). h
u»
-------
I
o
>
4>
©>
2
3
n
5200
4800
4400
4000
3000
3200
2800
2400
2000
1600
1200
800
400
~
23
~ Q 0
6500
6000
5500
5000
4500
4000
3500 °
3000 |
2500
2000
1S00
1000
500
M
I
68 140 284 662 1419 2839 B327
3
Hid-Kange Tank Size (m )
23 68 140 284 662 1419 2839 8327
Mid-Range Tank Size (m^)
B Pressure Vessel
floatiny Hoof
~ Fixed Hoof
Fig. Il-l. Number of Tanks and Storage Volume vs Tank Size (ref. 1)
t
-------
e
n
o
13,000
12,000
11,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
I
fixed
Roof
Floating
Roof
0
i
21,000
19,500
18,000
16,500
15,000
13,500
12,000
10,500
9,00
7,500
6,000
4,500
3,000
1,500
Pressure
Vessel
All
Tanks
Fixi?d
Roof
Floating
Roof
Pressure
Vessel
All
Tanks
m Feed
Intermediate
~ Product
\/\ Waste
Fig. II-2. Number of Tanks and Storage Volume vs Tank Type and Use
-------
Table II-2. Number of Tanks and Storage Volume by VOC Vapor Pressure*
Fixed Roof Floating Roof Pressure Vessel Total
Vapor
Pressure
(kPa)
No.of
Tanks
Storage-Volume
(m )
No. of
Tanks
Storage-Volume
(m-)
No. of
Tanks
S torage Volume
(m )
No. of
Tanks
S torag e_Volume
(m )
0.0001 to
1.4
7,400
2,718,000
55
134,000
330
25,000
7,785
2,877,000
1.4
to
3.5
2,070
1,035,000
55
71,000
180
20,000
2,305
1,126,000
3.5
to
6.9
1,955
951,000
45
144,000
140
59,000
2,140
1,154,000
6.9
to
10.3
980
653,000
35
319,600
140
45,000
1,155
1,017,600
10. 3
to
20.7
1,475
1,188,000
305
1,009,000
405
43,000
2,185
2,240,000
20.7
to
34.5
600
344,000
140
602,000
225
49,000
965
995,000 H
34.5
to
51.7
165
102,000
20
41,000
190
31,000
375
174,000 ^
51.7
to
69.0
90
47,000
0
0
155
108,000
245
155,000
69.0
to
103.4
80
59,000
15
21,000
230
63,000
325
143,000
103.4
to
172.3
0
0
0
0
390
390,000
390
390,000
172. 3
to
344.7
0
0
0
0
945
501,000
945
501,000
344. 7
to
517.0
0
0
0
0
600
682,000
600
682,000
517.0+
0
0
0
0
855
196,000
855
196,000
Total
14,815
7,097,000
670
2,341,000
4,785
2,212,000
20,270
11,650,600
*See ref. 1 (includes only tanks with capacity greater than 3.8 m"^) .
-------
II-7
large tanks (greater than 7000 m"*) normally have 12 turnovers or less per year.
All the data collected and the smooth curve fitting the correlation appear in
Fig. II-3.1
1. Fixed-Roof Tanks
Fixed-roof tanks consist of a steel cylindrical shell with a stationary roof.
The design may vary from cone-shaped roofs to flat roofs. The tank is designed
to operate at only slight internal pressure or vacuum and thus is highly sus-
ceptible to emissions from breathing, filling, and emptying. The fixed-roof
tank is the least expensive to construct and of all the tank designs now in use
is generally considered to be the minimum acceptable standard for storage of
volatile organic liquids. Some fixed-roof tanks are equipped with a conserva-
tion vent, which is a type of a pressure- and vacuum-relief valve designed to
contain minor vapor volume changes. The conservation vent reduces the amount
of breathing loss by not venting unless the design pressure differential is
exceeded. However, since the fixed-roof tank can be operated only within very
small pressure differentials (±0.2 kPa), the emission reduction may be as low
6 7
as 5%, depending on the vapor pressure of the stored material. ' Generally,
7
conservation vents are used for low-vapor-pressure VOC storage (<10.5 kPa).
3
Host fixed-roof tanks are small; 55% are smaller than 91 m and contain only 5%
of the total volume of liquid stored. Large tanks, 946 m3 or greater, which
comprise only 12% of the existing fixed-roof tanks, contain 72% of the total
volume of VOC stored (see Tables II-l and II-2). It is estimated that 36% of
the fixed-roof tanks (5345 tanks) contain liquids with vapor pressures in
excess of 3.5 kPa. These tanks comprise 47% (3344 X 103 m3) of the total VOC
fixed-roof tank storage volume.
2. Floating-Roof Tanks
The open-top floating-roof tank consists of a welded cylindrical steel wall
equipped with a metal deck or roof that is free to float on the surface of the
stored liquid, rising and falling with the liquid level in the tank. This
feature reduces evaporation losses by minimizing the vapor space. The liquid
surface is completely covered by the floating roof except for a small annular
space between the roof and the shell. & sliding seal attached to the floating
-------
II-8
10,000
N
•w
01
c
19
20 30 40 50 100 200 300 -100 500 1000
Number of Tank Turnovers Per Year
Fig. II-3. Average Number of Turnovers of VOC Storage Tanks vs Tank Size (ref. 1)
-------
II-9
roof fits against the tank wall and covers the remaining area. The primary
source of VOC emissions is through gaps in this seal.
Host emissions through the seal are attributable to wind effect. Wind blowing
across the tank creates pressure differentials around the edges of the floating
roof so that air flows into the seal on the leeward side, and air saturated
with VOC flows out on the windward side. Improper or loose fit of the seal
Q
significantly increases the emission rate.
The internal-floating-roof tank is a fixed-roof tank that has an internal roof
or deck floating on the liquid surface. If the internal roof is made of steel,
the tank is referred to as a "covered-floating-roof" tank. If the roof is made
of a material other than steel, the tank is referred to as an "internal-floating-
cover" tank.
Like the open-top floating roof, the internal floating roof has an attached
sliding seal that fits against the tank wall. Antirotational guides are provided
to maintain proper roof alignment. Special vents are installed on the fixed
roof or on the walls at the top of the shell to minimize the flammable vapor
concentrations in the vapor space. The fixed roof protects the floating roof
or deck and the seal from deterioration due to meterological effects, eliminates
the possibility of the roof sinking because of excess rain or snow loads, and
decreases the wind-induced pressure differential around the roof.
Floating-roof tanks comprise only 3.0% of the total number of storage tanks in
the industry. . They generally have very large capacities, with 30% of the total
3 3
having capacities in excess of 379 m and 26% in excess of 3785 m . The major-
ity (72%) are used for storing VOC with vapor pressures of 6.9 to 34.5 kPa.
This comprises 82% (1930 X 10^ m^) of the total floating-roof tank storage
volume.1
3. Pressure Tanks
Pressure tanks are designed to withstand relatively large internal pressures.
They are generally used for storing highly volatile and/or toxic materials and
are constructed in various sizes and shapes, depending on the operating pres-
sure range. Noded spheroid and hemispheroid shapes are generally used for
-------
11-10
low-pressure tanks (117 to 207 kPa); horizontal cylinder and spheroid designs
are generally used for high-pressure tanks (up to 1827 kPa). Because pressure
tanks are generally operated in a closed system at the pressure of the stored
material, losses are not generally incurred. Pressure tanks with inert gas
blanketing are a minor exception and are discussed in Sect. IV.
C. LOADING AND HANDLING
Loading and transportation operations of the SOCHI are very similar to those of
the petroleum liquids (refinery) industry except that they are on a relatively
smaller bulk scale. Synthetic organic chemicals are transported from the initial
producing sites to consumers. The consumers in most cases are other industrial
organic chemical producers, who use the basic and intermediate organic chemi-
cals as raw materials to manufacture additional intermediates or finished products.
An estimated 3,393,100 Kg (35,390 X 103 m3) of synthetic organic chemicals was
shipped in 1976 Water transportation was the type of shipment most often
used, accounting for 50% (17,695 X 103 m3) of the total volume; tank-car rail
shipments accounted for 30% (10,617 X 103 ra3) of the total, and truck shipments
3 3 2
for the remaining 20% (7078 X 10 m ). The quantities of chemicals at specific
ranges of vapor pressure that were shipped were estimated on the basis of propor-
tional volume and vapor pressure ranges of the chemicals stored. Shipment volumes
based on the percentages given in Table II-2 are shown in Table II-3.
An estimated 81% of all VOC shipped have a vapor pressure of less than 34.5 kPa.
Approximately 14.8% (5246 X 103 m3) have a vapor pressure of greater than
2
103.4 kPa and are assumed to be stored and loaded in closed systems with negli-
gible VOC loss.
Transit losses were calculated, by computing a breakdown of the time required
o
for each shipment based on the 1972 Census of Transportation. The time required
for most shipments (45 wt %) (see Table II-4) is only one day.
-------
11-11
Table II-3. Vapor Pressure and Volume of Synthetic Organic
Chemicals Shipped*
Vapor Pressure
(kPa)
Percentage of
Volume Stored
Volume
Shipped
(X 10-3 m35
0.001 to 1.4
24.7
8/743
1.4 to 3.5
9.7
3,429
3.5 ta 6.9
10.0
3,543
6.9 to 10.3
8.8
3,111
10.3 to 20.7
19.4
6,866
20.7 to 34.5
3.6
3,043
34.5 to 51.7
1.5
530
51.7 to 69.0
1. 3
454
69.0 to 103.4
1.2
424
>103.4
14.8
5,246
Total
100.0
35,389
*Refs. 1 and 5.
Table II-4.
Time Required for Shipments1
Fraction*3
of a Week
Percentage"3 of
Material Shipped
Volume ^hipped
(X 10 m3)
1/7
45.0
15,925
2/7
24.0
8,493
3/7
14.0
4,955
7/7
17.0
6,016
Total
100.0
35,389
aRefs. 1, 5, and 8.
bRef. 8.
CRef. 1.
-------
11-12
D. REFERENCES*
1. SOCHI storage-tank data base compiled by Hydroscience, Inc., Knoxville, TN,
using a computer program developed by Mitre Corporation, McLean, VA, April 1978
(on file at EPA, ESED, Research Triangle Park, NC; compiled from State EIQ
files, Site Visit Trip Report, and USITC Report on 1976 SOC Production and
Sales).
2. Texas/Louisiana State Emission Inventory Questionnaires (1975) (on file at EPA,
ESED, Research Triangle Park, NC).
3. 1976 Directory of Chemical Producers, United States of America, Stanford Research
Institute, Menlo Park, CA (1977).
4. E. G. Webster, Description of the Chemical Storage Tank Emissions (Tankemis)
Data Base, Working Paper No. 12993, Mitre Corp., Metrek Division, Mclean, VA
(May 1978).
5. Synthetic Organic Chemicals, 1976 United States Production and Sales, United
States International Trade Commission, GPO, Washington (1977).
6. C. C. Masser, "Storage of Petroleum Liquids," p. 4.3-1 in Supplement No. 7 to
Compilation of Air Pollutant Emission Factors, AP-42, 2d ed., EPA, Research
Triangle Park, NC (April 1977).
7. Control of Volatile Organic Compounds from Storage of Petroleum Liguids (draft
copy) (prepared by EPA, ESED, Research Triangle Park, NC) (November 1977).
8. C. C. Masser, "Storage of Petroleum Liquids," pp. 4.3-5 in Supplement No. 7 to
Compilation of Air Pollutant Emission Factors, AP-42, 2d ed., EPA, Research
Triangle Park, NC (April 1977).
9. Cited in Kline Guide to the Chemical Industry, 3d ed., p. 58, edited by M. K.
Meegen, Charles H. Kline and Co., Inc., Fairfield, NJ, 1977.
*A reference located at the end of a paragraph usually refers to the entire
paragraph. If another reference relates to certain portions of the paragraph,
that reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
III-l
III. EMISSIONS
A. SOURCES
1. Storage Tanks^
There are five emission sources that need to be considered in organic chemical
storage: fixed-roof breathing losses, fixed-roof working losses, floating-roof
standing-storage losses, floating-roof withdrawal losses, and pressure-tank
losses.
Fixed-roof breathing losses occur when VOC is expelled from a tank because
vapors expand and contract as a result of a diurnal temperature change or
barometric pressure changes and additional VOC vaporization.
Fixed-roof working losses result from VOC being expelled from a tank during
filling and emptying operations. During the filling operation vapor is displaced
by the incoming liquid, and during the emptying, operation air is drawn into the
tank and becomes saturated with organic vapor and is discharged during the next
filling.
Floating-roof standing storage losses occur when VOC is expelled from the tank.
The primary source of this loss is a defective fit of the seal and shoe to the
tank wall, which exposes some liquid surface to the atmosphere.
Floating-roof withdrawal losses occur when VOC is evaporated from the liquid
film that wets the tank wall while the roof descends during emptying operations.
This loss will be small compared to the other types of losses if the number of
tank turnovers is low.
No VOC losses will be experienced from pressure-tank operation under normal
conditions. Losses may occur if an inert-gas pad is used for safety or oper-
ating reasons or if the pressure inside the tank exceeds the relief (safety)
operating pressure.
The following main-storage operating factors affect VOC loss: vapor pressure
of the liquid stored, temperature changes in the tank, tank vapor space (tank
-------
III-2
outage), tank diameter, frequency of turnovers, mechanical condition of tank
and seals, tank type, tank color, and weather conditions.
2
2. Loading and Handling
There are three emission sources from the transportation of volatile synthetic
organic chemicals: loading losses, transit losses, and ballasting losses.
Both loading and transit losses occur when VOC is transported by marine ves-
sels, tank cars, or tank trucks. With marine vessels there can also be bal-
lasting losses. VOC losses from pipe lines are negligible under normal oper-
ating conditions.
Loading losses are the primary source of emissions from marine vessel, tank-
car, and tank-truck operations and occur when vapors residing in empty cargo
tanks are displaced to the atmosphere by the liquid being loaded. These vapors
are a mixture of the vapors formed in the empty tank, by evaporation of residual
product from a previous load and those generated in the tank as a new product
is being loaded.
The total evaporative.loss from loading operations is a function of the physi-
cal and chemical properties of the previous and new cargos, the method used for
loading or unloading the cargos, and the service history of the cargo carrier
("clean tank; normal, dedicated service; or dedicated, vapor balance service").
Transit losses will occur if vapor is expelled because of temperature and
barometric pressure changes while the cargo tank is en route. These transit
losses are eliminated if closed pressure carriers are used.
An additional practice, specific to marine vessels, that increases shipping
losses is ballasting. After a cargo is unloaded, the empty tanker will nor-
mally carry several cargo tanks filled with water to improve stability during
the return voyage. VOC vapors remaining in the empty tanks are expelled when
the ballast water is added.
-------
Ill-3
B. CALCULATIONS
1. Storage Tanks
Emissions from organic chemicals stored in fixed-roof and floating-roof tanks
were calculated with use of the following empirical equations.
a. Fixed-Roof Tanks — Breathing losses and working losses occur from storage of
chemicals in fixed-roof tanks.
3
Breathing losses — The following equation can be applied to all fixed-roof
tanks and includes the assumption that no conservation vent is installed on the
tank:
h •2-21 x 10'4«(irf^-p)0 68 d1'73 h°'51 4T°'5 v*e M
where
Lg = fixed roof breathing loss (Mg/yr) ,
M = molecular weight of vapor in storage tank (lb/Ih mole),
P 3 true vapor pressure at bulk liquid conditions (psia),
D = tank, diameter (ft),
H = average vapor space height (ft; used 1/2 tank height),
AT = average diurnal temperature change (°F; used 20°F),
Fp = paint factor (dimensionless, assuming a white tank in good
condition; factor = 1),
C = adjustment factor (dimensionless) for large-diameter tanks (D>30 ft),
c = 1; for small-diameter tanks (less than 30 ft) =
0.0771 (D) - 0.0013 (D2) - 0.1334 (ref 4),
Kc = crude oil factor (dimensionless; used 1.0).
The average diurnal (day/night) temperature change is variable and can be
determined from National Weather Service data for a plant at a specific geographic
location.
The paint factor (F^) for fixed-roof tanks can be obtained for a specific example
from Table A-l (Appendix A) taken from AP-42, Supplement No. 7.
-------
III-4
Working losses3 — The following equation can be applied to all fixed-roof
tanks with or without conservation vents:
L.
w
where
Lw = fixed-roof working loss (Mg/yr)
Kn = turnover factor (dimensionless)
= (180 + N)/6N for N > 36 and = 1 for N < 36,
V - tank volume (gal),
N = turnovers per year,
M, P, and Kc = same as for fixed-roof breathing losses.
Tank turnovers per year, if not stated, can be obtained by dividing the annual
throughput through the tank by the tank's capacity.
b. Floating-Roof Tanks — Standing-storage losses and withdrawal losses were
calculated for floating-roof tanks as follows.
Standing storage losses5 — The following equation can be applied to both
open-top and internal-floating-roof tanks with single primary seals:
= floating-roof standing-storage loss (Mg/yr),
v^ = average wind velocity (miles/hr,- used 9.0),
= tank type factor (dimensionless; used 0.045
based on welded tank),
Ks = seal factor (dimensionless; used 1.0),
K = paint factor (dimensionless; used 0.9 based on white
P
paint),
M, P, D, and Kc = same as for fixed-roof breathing losses.
An average wind speed (vtf) should be used for determining losses from open-top
floating-roof tanks. A wind speed of 4 mph should be used for calculating
losses from internal-floating-roof tanks.
Ls = 0.00921 M(nr?*rT)0-7D1-5v,
where
-------
III-5
The factors K , K , and K depend on the type of tank construction, tank seal,
w S J)
and paint used, respectively. Table A-2 gives the values for these factors,
taken from AP-42, Supplement No. 7.
6 7
Withdrawal losses — The following equation ' can be applied to both internal-
and open-top floating-roof tanks that are equipped with either a primary seal
or a primary and a secondary seal:
Lwd = 0.000198 DTHd ^
where
Lw
-------
III-6
where
= loading loss (Mg/yr),
S = saturation factor (dimensionless; used 1.0 for tank truck and tank
car and 0.2 for marine vessels),
P = true vapor pressure of the liquid loaded (psia),
M = molecular weight of vapors (lb/lb mole),
T = bulk temperature of liquid loading [°R; used 540°R (80°F)],
V = volume loaded (gal/yr).
The saturation (S) factor represents the expelled vapor's fractional approach
to saturation and accounts for the variations observed in emission rates from
the different unloading and loading methods. An S factor of 1.0 for tank cars
and tank trucks and an S factor of 0.2 for marine vessels give an average
estimate of emissions for the industry, which uses a variety of loading methods,
with no add-on emission control devices assumed to be in use. Table A-3 gives
the S values to be used for specific loading methods, taken from AP-42, Supplement
Mo. 7.
g
b. Transit Losses — The following equation can be applied to tank-car, tank-truck,
and marine-vessel transport and assumes that the carrier is not a pressure vessel:
Lfc = 0.1 PW T
where
Lfc = transit loss (Mg/yr),
P = true vapor pressure of the liquid loaded (psia),
W => density of condensed vapor (lb/gal,- used 8.0),
V = volume transported per year (gal/yr),
T = fraction of a week required for transport.
Ballasting losses could not be estimated because data were not available on
chemical transport by ships that are ballasted. This is not expected to be a
major emission for organic chemical transportation.
-------
III-7
INDUSTRY EMISSIONS
SOCHI VOC emissions from both storage and loading are presented in two ways:
(1) Uncontrolled VOC emissions are calculated with the equations described in
Sect. B. Uncontrolled VOC emissions are defined as those emissions that would
occur as a result of no add-on controls being used on storage tanks or during
loading operations. (2) Current or present VOC emissions from storage and
loading are calculated by estimating the number and operating efficiency of
add-on controls currently in use and applying them to the uncontrolled emis-
sions. Because floating-roof tanks are VOC emission control devices, current
and uncontrolled VOC emission quantities from floating-roof tanks are the same.
Pressure tanks are considered to be closed systems with no estimated VOC emis-
sions.
Uncontrolled Emissions (1977)
Storage Tanks — Uncontrolled VOC emissions from existing fixed-roof tanks are
calculated to be 66,601 Mg/yr and for floating-roof tanks to be 1351 Mg/yr, for
a projected total of 68,452 Mg/yr. Tables- III-l and III-2 show the distribution
of the calculated emissions by tank capacity and vapor pressure, respectively.
Large fixed-roof storage tanks — more than 1890 m3 — are the source of an
estimated 44% (29,000 Mg/yr) of the total uncontrolled fixed-roof-storage VOC
emissions, although they comprise only 5.5% of the total number of tanks.
Although smaller fixed-roof storage tanks — less than 76 m3 — constitute 49%
of the total industry tankage, they contribute only 11% (7244 Mg/yr) of the
emissions (see Table III-l).
Approximately 60% of the total VOC emissions is from the storage of materials
having vapor pressures between 3.5 and 34.5 kPa. Materials stored in fixed-
roof tanks and having vapor pressures higher than 34.5 kPa contribute 30% of
the total estimated uncontrolled VOC emissions, and materials with vapor pres-
sures of less than 3.5 kPa, although comprising 53% of the total volume stored,
contribute only 10% of the total estimated VOC emissions from fixed-roof stor-
age (see Table III-2).
-------
Table III-l. 1977 Storage-Tank VOC Emissions by Tank Size and Typea (Assuming No Controls)
Fixed-Roof
Tanks
Floating-
-Roof Tanks^
Total6
Tank
« • LI
Size
No. of
Q
Emissions
No. of
Q
Emissions
No. of
Emissions0
(m )
Tanks
(Mg/yr)
Tanks
(Mg/yr)
Tanks
(Mg/yr)
4
to
38
4,495
3,366
0
0
4,495
3,366
38
to
76
2,825
3,878
10
7
2,750
3,885
76
to
114
1,425
2,114
0
0
1,360
2,114
114
to
151
550
2,263
15
7
625
2,270
151
to
189
800
1,397
25
15
915
1,412
189
to
379
1,375
5,457
85
209
1,460
5,666
379
to
946
1,560
7,743
140
157
1,700
7,900
946
to
1893
975
11,435
95
131
1,070
11,566
1893
to
3785
520
15,245
125
417
645
15,662
>3785
290
13,703
175
908
465
14,611
Total
14,815
66,601
670
1,851
15,485
68,452
a 3
Includes only tanks with capacity greater than 3.8 m .
b
See ref. 10.
Q
Calculated from equations detailed in this section (III.B).
d
Floating-roof tanks are actually control devices and therefore have no uncontrolled VOC emissions.
e
Emissions from pressure vessels assumed to be negligible.
-------
Table III-2. 1977 Storage-Tank VOC Emissions by Material Vapor Pressure and Tank Type (Assuming no Controls)
Fixed-
Roof Tanks
Floating-
d
Roof Tanks
e
Total
b
Vapor Pressure
No. of
Emissions0
No. of
Emissions
No. of
Emissions0
(kPa)
Tanks
(Mg/yr)
Tanks
(Mg/yr)
Tanks
(Mg/yr)
0.001 to 1.4
7,400
3,678
55
36
7,455
3,714
1.4 to 3.5
2,070
3,927
55
52
2,125
3,979
3.5 to 6.9
1,955
6,377
45
69
2,000
6,446
6.9 to 10.3
980
6,063
35
194
1,015
6,257
10.3 to 20.7
1,475
15,954
305
702
1,780
16,656
20.7 to 34.5
600
10,592
140
578
740
11,170
34.5 to 51.7
165
5,590
20
73
185
5.663
51.7 to 69.0
90
4,505
0
0
90
4,505
69.0 to 103.4
80
9,915
15
147
95
10,062
Total
14,815
66,601
670
1,851
15,485
68,452
d
Includes only tanks with capacity greater than 3.8 m .
^See ref. 10.
Calculated from equations detailed in this section (III.B).
^Floating-roof tanks are actually control devices and therefore have no uncontrolled VOC emissions.
Emissions from pressure vessels assumed to be negligible.
-------
111-10
Pressure tanks are not a significant source of VOC emissions under normal
operating conditions.
Loading and Handling^-0
Uncontrolled VOC emissions from loading are calculated to be 5848 Mg/yr and
from transit to be 1727 Mg/yr, for a total of 7575 Mg/yr (see Table III-3).
Rail and truck shipments account for 83% (4874 Mg/yr) of the uncontrolled
loading VOC emissions. Shipments of materials whose vapor pressures range from
6.9 to 34.5 kPa contribute 66% of the total uncontrolled VOC emissions for the
industry.
Approximately 15% (5250 X 103 m3) of the VOC shipments listed in Table II-3
(above 103.4 kPa vapor pressure) are considered to be stored and loaded in
closed systems with negligible loss of VOC.
Present Industry Emissions (1977)11
Storage Tanks — Current emissions from fixed-roof tanks for the SOCMI are
estimated to be 43,408 Mg/yr and for floating-roof tanks to be 1851 Mg/yr, for
a projected total of 45,259 Mg/yr. This is approximately 34% less than the
calculated uncontrolled emission levels. Tables III-4 and III-5 show the
distribution of the estimated emissions by tank capacity and vapor pressure,
respectively.
An estimated 2148 fixed-roof tanks have add-on controls. This represents about
15% of the total number of fixed-roof tanks in the industry.
3
Large tanks, above 946 m , account for about 41% of the total number of fixed-
roof tanks with add-on controls.
Approximately 40% of the fixed-roof tanks containing material with a vapor
pressure of 10.3 kPa or greater have add-on control devices.
Approximately 80% of the emissions from floating-roof tanks are from materials
having a vapor pressure of between 6.9 and 34.5 kPa. These materials are
-------
Table III-3. 1977 Loading and Transportation VOC Emissions by Material Vapor Pressure9
(Assuming No Control)
Annual Volume Loading Transportation Total VOC
Vapor Pressure Shipped Loss Loss Emissions
(kPa)
(103 m3/yr)
(Mg/yr)b
-------
*1
Table III-4. Current 1977 Storage-Tank VOC Emissions by Tank Size and Type (with Controls)
Fixed-Roof
Tanks
Floating-Roof
d
Tanks
Total®
Tank Size*3
No. of
No.
Q
Emissions
c
No. of Emissions
No. of
No.
c
Emissions
(m )
Tanks
Controlled
(Mg/yr)
Tanks (Mg/yr)
Tanks
Controlled
(Mg/yr)
4
to
38
4,495
339
2,346
0
0
4,495
339
2,346
38
to
76
2,825
310
2,696
10
7
2,750
320
2,703
76
to
114
1,425
154
1,534
0
0
1,360
154
1,534
114
to
151
550
53
1,683
15
7
625
68
1,690
151
to
189
800
39
977
25
15
915
64
992
189
to
379
1,375
161
3,718
85
209
1,460
246
3,927
379
to
946
1,560
215
5,424
140
157
1,700
355
5,581
946
to
1893
975
382
7,307
95
131
1,070
477
7,438
1893
to
3785
520
300
8,867
125
417
645
425
9,284
>3785
290
195
8,856
175
908
465
370
9,764
Total
14,815
2,148
43,408
670 1
,851
15,485
2,818
45,259
a 3
Includes only tanks with capacity greater than 3.8 m .
^See ref. 10.
Q
Determined by estimating the add-on controls in use and applying to the uncontrolled emissions at 80% control
efficiency.
d
Floating-roof tanks are actually control devices and therefore have no uncontrolled VOC emissions.
0
Emissions from pressure vessels assumed to be negligible.
-------
Table III-5. Current 1977 Storage-Tank VOC Emissions by Material Vapor Pressure and Tank Type3 (with Controls)
Fixed-Roof
Tanks
Floating-Roof
d
Tanks
Total6
Vapor
b
Pressure
(kPa)
No. of
Tanks
No.
Controlled
Q
Emissions
(Mg/yr)
No. of Emissions0
Tanks (Mg/yr)
No. of
Tanks
No.
Controlled
Q
Emissions
(Mg/yr)
0.001 to
1.4
7,400
370
3,531
55
36
7,455
425
3,567
1.4
to
3.5
2,070
207
3,613
55
52
2,125
262
3,665
3.5
to
6.9
1,955
391
5,357
45
69
2,000
436
5,426
6.9
to
10.3
980
245
4,850
35
194
1,015
280
5,044
10. 3
to
20.7
1,475
443
12,125
305
702
1,780
748
12,827
20.7
to
34.5
600
240
7,203
140
578
740
380
7,781
34.5
to
51.7
165
99
2,907
20
73
185
119
2,980
51.7
to
69.0
90
77
1,442
0
0
90
77
1,442
69.0
to
103.4
80
76
2,380
15
147
95
91
2,527
Total
14,815
2,148
43,408
670 1
,851
15,485
2,818
45,259
a 3
Includes only tanks with capacity greater than 3.8 m .
^See ref. 10.
c
Determined by estimating the add-on controls in use and applying to the uncontrolled emissions at 80% control
efficiency.
d
Floating-roof tanks are actually control devices and therefore have no uncontrolled VOC emissions.
£
Emissions from pressure vessels assumed to be negligible.
-------
111-14
usually stored in large tanks, with 72% of the floating-roof tank emissions
coming from tanks larger than 1890 ra^.
As stated in Sect. III-C-1, pressure tanks are not a significant source of VOC
emissions under normal operating conditions.
Loading and Handling — Current VOC emissions from loading are estimated to be
4830 Mg/yr and from transit to be 86 Mg/yr, for a total of 4917 Mg/yr (see
Table III-6). This is a 35% reduction from the uncontrolled-emission levels.
The major cause for reduction is the use of pressurized cargo carriers, esti-
mated to be used at least 95% of the time, that have no VOC emissions during
transport.
As stated in Sect. C-l, approximately 15% of the VOC shipments are considered
to be stored and loaded in closed systems with negligible loss of VOC since the
materials have vapor pressures equal to or greater than atmospheric pressure.
Miscellaneous — It is recognized that there are other sources of VOC emissions
related to storage and handling of SOCHI materials. They include tank and
cargo carrier clean-outs, spills from both loading and unloading operations,
losses from breaking of hose and coupling connections, purging of tanks and
cargo carriers to eliminate explosive mixtures, etc. These emissions are not
controlled and are believed to be small compared to the total VOC emissions
lost from storage tanks and loading and have not been estimated.
-------
Table III-6. Current 1977 Loading and Transportation VOC Emissions by Material Vapor Pressure3 (with Controls)
Vapor Pressure
(kPa)
Annual Volume
Shipped
(X 103 m3/yr)
Loading
Loss
(Mg/yr)
Transportation
Loss
(Mg/yr)c
Total VOC
Emissions
(Mg/yr)b
0.001 to 1.4
8,743
174
1
175
1.4 to 3.5
3,429
230
2
232
3.5 to 6.9
3,543
405
5
410
6.9 to 10.3
3,111
525
7
532
10.3 to 20.7
6,866
1,806
28
1,834
20.7 to 34.5
3,043
1,019
22
1,041
34.5 to 51.7
530
264
6
270
51.7 to 69.0
454
238
7
245
69.0 to 103.4
424
169
8
177
Total
30,143
4,830
86
4,917
3See refs. 10 and 11.
b
Determined by estimating the add-on controls used and applying them to the uncontrolled emissions at 80% control
efficiency.
c
Transportation loss estimated to be 5% or less of uncontrolled loss due to use of pressurized cargo carriers.
-------
111-16
D. REFERENCES*
1. C. C. Masser, "Storage of Petroleum Liquids," pp. 4.3-5 and 4.3-6 in Supplement
No. 7 to Compilation of Air Pollutant Emission Factors, AP-42, 2d ed., EPA,
Research Triangle Park, NC (April 1977).
2. C. C. Masser, "Transportation and Marketing of Petroleum Liquids," pp. 4.4-1 to
4.4-6 in Supplement No. 7 to Compilation of Air Pollutant Emission Factors,
AP-42, 2d ed., EPA, Research Triangle Park, NC (April 1977).
3. C. C. Masser, "Storage of Petroleum Liquids," pp. 4.3-6, 4.3-10, and 4.3-11 in
Supplement No. 7 to Compilation of Air Pollutant Emission Factors, AP-42, 2d
ed., EPA, Research Triangle Park, NC (April 1977).
4. A. Goldfarb, Small Diameter Factor for Floating Roof Breathing Loss Equation,
Mitre Corp., Metrek Division, McLean, VA (data on file by D. Erikson, Hydroscience,
Inc., Knoxville, TN) (Apr. 4, 1978).
5. C. C. Masser, "Storage of Petroleum Liquids," pp. 4.3-12 and 4.3-13 in
Supplement No. 7 to Compilation of Air Pollutant Emission Factors, AP-42, 2d
ed., EPA, Research Triangle Park, NC (April 1977).
-6. Chicago Bridge and Iron Co., S0HI0/CBI Floating Roof Emission Testing Program,
Supplemental Report (Feb. 15, 1977).
7. Equation for floating-roof withdrawal loss derived by R. Burr, EPA, ESED,
Research Triangle Park, NC (May 1978).
8. American Petroleum Institute, Evaporation Loss Committee, Evaporation Loss
from Fixed-Roof Tanks, Bulletin 2518, Washington (1962).
9. C. C. Masser, "Transportion and Marketing of Petroleum Liquids," pp. 4.4-5 and
4.4-7 in Supplement No. 7 to Compilation of Air Pollutant Emission Factors,
AP-42, 2d ed., EPA, Research Triangle Park, NC (April 1977).
10. SOCMI storage tank data base compiled by Hydroscience, Inc., Knoxville, TN,
using computer program developed by Mitre Corp., McLean, VA, April 1978 (on
file at ESED, EPA, Research Triangle Park, NC) (compiled from State EIQ files,
Site Visit Trip Reports, and USITC Report on 1976 SOC Production and Sales).
11. Texas/Louisiana State Emission Inventory Questionnaires (1975) (on file at EPA,
ESED, Research Triangle Park, NC).
*A reference located at the end of a paragraph usually refers to the entire
paragraph. If another reference relates to certain portions of the paragraph,
that reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
IV-1
IV. CONTROL TECHNOLOGY
There are several different methods, with varying ranges of efficiency, for the
control of emissions from the storage and handling of organic chemicals.
A. STORAGE TANKS
1. Fixed-Roof Tanks
Fixed-roof tanks represent minimal control technology. They are inadequate for
storing the more volatile organic compounds, as is demonstrated by the high
emission levels presented in Sect. III. Emissions are significant even with
vapor pressures as low as 3.4 kPa. The following control systems are applic-
able to fixed-roof tanks.
a. Internal-Floatinq-Roof Retrofit — Fixed-roof tanks can be retrofitted with
internal-floating roofs to achieve 80 to 97% reductions in VOC emissions. As
is mentioned in Sect. II, internal floating roofs or covers can be constructed
of ferrous or nonferrous material.1
Regardless of the floating-roof design, a closure device must be used to seal
the gap between the tank wall and the floating roof around the roof perimeter.
Various designs are available for the closure device (seal), which can be made
of a range of materials suitable for organic liquids. Figure IV-I illustrates
several typical flotation designs and primary closure seals for internal float-
2
ing covers and covered floating roofs. The two primary closure seals used most
frequently are the metallic shoe seal and the tube seal (see Figs. IV-23 and
IV-31).
The metallic shoe seal consists of a 30- to 36-in.-long metal sheet (the "shoe")
hung vertically against the tank wall. The shoe is connected by braces to the
floating roof and is held against the tank wall by springs or weighted levers.
A flexible, impermeable fabric (the "envelope") is suspended from the top of
the shoe seal to the roof to seal the annular space between the roof and the
seal. Thus evaporation from the annular liquid surface is limited by the small
vapor space between the liquid surface and the envelope. Ideally, the envelope
is vapor-tight, and the only emissions that occur are from the liquid surface
between the shoe and tank wall. Such losses will be very high if the envelope
is in poor condition (if there are holes, tears, seam gaps).
-------
1. Aluminum deck supported above
liquid by tubular aluminum pontoons
A-2. Aluminum panel deck supported above
liquid by aluminum floats with polyurethane foam
Elastomer wiper seal
_V -Mote; V . r Vdpi
I = liqi
Deck
Pontoon
Hetal seal ring
Tank shell
X
1
Pontoon
Elastomer wiper seal
I
A-3. Aluminum sandwich panels' with honeycombed
aluminum core floating on surface
^aridwich Panels l| |l
V L
Foam-filled coated fabric
B. Covered Floating Roof
Foam-filled
' coated fabric
/
Mfcl
Steel pan
L /
Fig. IV-1. Typical Flotation Devices and Perimeter Seals of Internal Floating Covers
and Covered Floating Roof (ref. 2)
-------
IV- 3
SEAL FAORIC
TANK SHELL
CURTAIN SEAL
COUNTERWEIGHT
TANK SHELL —
SEAL ENVELOPE
RESILIENT
URETHANE
FOAM
Primary natal11c shoe seal
BUMPER
LIQUIO LEVEL
Primary nonmetalUc resilient seal
TM>
««W '
amutcsrat ncoso/mrsiM.
nunwc
Hatall1c-«!io*-tyo« seal with secondary seal
Fig. IV-2. Floating Roof Tank Primary and secondary Closure Seals
(ref. 3)
-------
IV-4
Tank wall
Scrub band
Seal fabric
Secondary seal
Product liquid ^
Liquid filled tube
c
J
Fig. IV-3. Fluidic-Type Tube Seal with Secondary Seal
-------
IV-5
The nonmetallic resilient tube seal is usually an 8- to lO-in.-diam flexible
polymeric tube filled with either a noncontaminant liquid or a solid resilient
foam. This tube is attached to the edge (along the circumference) of the
floating roof and covers the annular space between the roof and shell. As is
illustrated in Fig. IV-2, the resilient foam-filled tube seal allows a vapor
space analogous to that provided by mechanical seals. Unlike the shoe seal,
however, a gap in a resilient tube seal results in direct communication between
the vapor space and the atmosphere, causing higher emissions. A well-designed
and maintained liquid-filled tube seal (Fig. IV-3) has no vapor space, since it
floats on top of the liquid stored, and therefore virtually eliminates the
liquid surface in direct communication with the atmosphere.*
Other modifications to the fixed-roof tank may also be required to equip it as
an internal-floating-roof tank. The tank shell may require corrections for
deformation and obstruction or special structural modifications such as bracing,
reinforcing, and vertical plumbing. Antirotation guides should be installed to
maintain cover openings in alignment with roof openings. Additional vents are
normally installed on the fixed roof or on the tank walls at the top of the
shell to minimize the flammable-vapor concentrations in the vapor space.
Retrofitted internal floating roofs are considered to be equivalent in control
technology to the double seals used on open-top floating-roof tanks.* Calcula-
tions indicate that, over a wide range of storage conditions, emission reduc-
tions of 80 to 97% can be achieved by retrofitting fixed-roof tanks with inter-
nal floating roofs. The actual amount of emission reduction depends primarily
on the size of the tank and the vapor pressure of the VOC.
b. Refrigerated Vent Condensers — Refrigerated vent condensers for controlling
fixed-roof storage tank VOC emissions are one of the most common types of
4
emission reduction equipment found in the industry.
Condensers are sized to handle the maximum vapor rate expected at any given
time, which normally occurs during the tank filling operation. In actual
service one condenser can be used to collect the vapors from a manifold system
of tanks containing the same material.
-------
IV-6
The refrigerated condenser must be properly designed to handle freezing of
moisture or VOC. This is accomplished by a system that routinely defrosts the
condenser and then separates the recovered water-VOC mixture. Package units
are available in a range of sizes for various applications.^
The efficiency of vent condensers depends on the vapor concentration of the VOC
in the vent gas and on the condensing temperature. Normally the VOC partial
pressure in the effluent gas streams can be reduced to 3.4 to 0.7 kPa.^ Theo-
retical recovery efficiencies can be in excess of 90% for VOC whose vapor
pressures are over 34.5 kPa, and 60 to 90% for materials with vapor pressures
in the range of 3.4 to 34.5 kPa.
c. Activated-Carbon Adsorbers — Activated carbon is used widely as an adsorbent
for removal of organic vapors. Other adsorbents used in special applications
are silica gel, bauxite, and alumina. Activated-carbon control systems usually
consist of at least two adsorbent beds; one bed adsorbs organics from the vent
stream while the other bed is being regenerated.
The activated carbon is usually regenerated by the bed being purged with steam
countercurrent to the flow of. gas during adsorption. The amount of steam
necessary for regeneration depends on the adsorption parameters of the VOC
contaminant being removed. Industrial applications normally require 10 to
20 kg of steam per kg of VOC adsorbed. The steam containing the recovered VOC
is condensed, and the water-VOC mixture is decanted for recovery of the VOC.
The size of the carbon adsorption units depends on the type and concentrations
of the VOC components in the vent gas, on the gas flow rate, and on the time
required for regeneration.
The control effectiveness of the unit depends largely on the nature of the VOC
being controlled and must be evaluated for adsorption potential. Generally,
VOC with molecular weights greater than 45 are considered to have adequate
adsorption priorities. High-molecular-weight compounds usually have superior
adsorption properties. Reduction efficiencies in excess of 99% can be obtained
with properly designed and operated units.®
-------
rv-7
d. Oxidation Units — Oxidation of VOC is also used to eliminate storage tank
emissions. This can be done by the use of flares, thermal oxidizers, or catal-
ytic oxidizers. All three methods are very effective in reducing VOC emis-
sions, and properly designed and operated units can have greater than 99%
7 8
efficiency. ' The flare and the thermal oxidizer require supplemental fuel,
whereas the catalytic oxidizer operates at lower temperatures and may not need
additional fuel.
Normally, oxidation as a control for storage-tank VOC emissions cannot be
justified economically unless it is combined with a more significant process-
vent emission control system.
e. Absorbers — Absorption involves dissolving a soluble gas component into a
nonvolatile liquid. Absorbing mediums that have been used for VOC emission
4
control are water, solvents, caustic, and acid solutions.
Use of aqueous scrubbing mediums, can pose wastewater disposal or secondary-
emission problems. Absorption can be an effective control option when the
absorption medium can be recycled back to the production process. Absorption
A
efficiencies are- usually in excess of 90%, depending on operating conditions,
VOC properties, and solvent properties.
f. Pressure Vessels — Pressure vessels as described in Sect. II can be considered
as a control alternative for small fixed-roof tanks (under 15 m^). Under
normal conditions no VOC losses will be experienced from pressure vessels. If
an inert-gas pad is used for safety or operating reasons, losses will be simi-
lar to those experienced from variable vapor-space tanks (i.e., reductions of
Q
98% in VOC emissions- from a fixed-roof tank).
g. Conservation Vents — A conservation vent is a pressure and vacuum vent that
provides a large gas flow area with a small differential pressure setting of
%
±0.2 kPa. The seal is provided by gasketed plates held in place over an open-
ing by a system of levers and adjustable weights. The use of a conservation
vent reduces the amount of breathing losses from fixed-roof tanks by venting
only when the design pressure differential is exceeded. Estimated emission
control efficiencies of tank breathing losses range from 5 to 25-*-% depending on
the vapor pressure of the material stored.1
-------
IV-3
Conservation vents will achieve low-cast VOC emission control for fixed-roof
tanks that do not warrant the floating-roof or other types of control options
covered above. Exceptions would be their application on fixed-roof tanks
containing chemicals that could partially or completely plug the vents in a
short period of time (i.e., shorter than the biannual inspection period) and
result in structural damage to the tank.
Open-Top Floating-Roof Tank
Open-top floating-roof tanks represent good control technology for storing the
more volatile organic chemicals, as reflected by the data in Sect. III.11
Recent industrial tests with an experimental tank have shown that wind has an
important effect on emission losses and that significant reductions can be
achieved by using double-seal technology.10 This method consists of installing
an impermeable secondary seal over the primary tube or mechanical seal from the
floating-roof to the tank wall. The secondary seal forms an additional barrier
that VOC emissions must penetrate before they can reach the atmosphere (see
Fig. IV-2). Data from the test tank simulating actual field conditions indi-
cate that losses with secondary seals are 50 to 75% lower than those from a
primary seal alone. Gaps in the secondary seal between the seal and tank wall
should not be allowed to exceed 0.32 cm in width for a cumulative length of 95%
of the tank circumference. Gaps around the remaining 5% should not exceed
1.3 cm in width.11
The use of double-seal technology does not eliminate the need for frequent
maintenance and inspection programs.
Internal-Floating-Roof Tank
As was discussed previously, retrofitting an internal-floating-roof tank to a
fixed-roof tank is considered to be equivalent to the double-seal control used
on open-top floating-roof tanks.
The effectiveness of any of the control devices noted above will be reduced
significantly if a proper maintenance and inspection program is not followed.
A biannual inspection program with followup repairs is suggested for all con-
trol devices, including seals on floating roofs, to ensure maximum control of
VOC emissions from storage tanks, regardless of the type.
-------
IV-9
B. LOADING AND HANDLING
Loading emissions can be controlled by any of the methods described below.
1. Submerged Loading
The principal methods of loading cargo carriers are splash loading and sub-
merged loading. The two types of submerged loading are the submerged-fillpipe
and the bottom-loading methods. In the submerged-fillpipe method the fillpipe
descends almost to the- bottom of the cargo tank. In the bottom-loading method
the material enters the cargo tank from the bottom. Submerged loading signifi-
cantly reduces liquid turbulence and vapor-liquid contact and results in much
lower VOC losses than are experienced with splash loading. Emission reductions
12
can range from 0 to 65%, depending on the method used by the cargo carrier.
2. Vapor Recovery
Vapor recovery equipment recovers the VOC vapors displaced during loading and
ballasting operations by use of refrigeration, adsorption, and/or absorption,
as described above for fixed-roof tanks. Control efficiencies range from 90 to
95%, depending on the nature of the VOC emissions and the type of recovery
, 12
equipment used.
3. Vapor Oxidation
Vapor oxidation with thermal oxidation devices, can give greater than 99% VOC
emissions control. As an example, in the petroleum industry gasoline vapors
from a terminal are displaced to a vapor holder as they are generated. When
the gasoline vapors reach the capacity of the holder, they are released to the
oxidizer, after being mixed with a properly metered air stream, and are then
combusted. The thermal oxidizer is not a true afterburner; rather, it operates
in the manner of an. enclosed flare.13
Twelve to fifteen thermal oxidizers have reportedly been installed by gasoline
terminal operators. Later models of this type of control equipment do not
require vapor holders; vapors from the tank trucks created during loading
operations are vented directly to the thermal oxidizer.
-------
IV-10
4. Vapor Balance
Another method of loading that can be used to reduce VOC emissions is called
dedicated balance service. Cargo carriers in dedicated balance service pick up
vapors displaced from the receiving tank during unloading operations and trans-
12
port them in the empty cargo tanks back to the loading terminal. These
vapors can then be displaced, during subsequent refilling of the cargo carrier,
to an emission control device installed at the loading terminal.
-------
rv-ii
C. REFERENCES*
1. Control of Volatile Organic Compounds from the Storage of Petroleum Liquids
(draft copy) (data on file at EPA, ESED, Research Triangle Park, NC)
(November 1977).
2. Control Volatile Organic Emissions from Storage of Petroleum Liquids in
Fixed-Roof Tanks, EPA-450/2-77-036 (OAQPS No. 1.2-089), Research Triangle Park,
NC (December 1977).
3. Federal Register 43(97), 21618 (May 18, 1978).
4. Booz, Allen & Hamilton Inc., Final Report. Volume I of II. Cost of
Hydrocarbon Emissions Control to the U.S. Chemical Industry (SIC 28);
Florham Park, NJ (December 1977).
5. Information from technical bulletin, Hydrocarbon Vapor Recovery Unit, Form
8-VRC-16, by Edwards Engineering Corp., Pompton Plains, NJ (Hay 1, 1976).
6. C. S. Parmele, Hydroscience, Inc., letter to L. Evans, EPA, Research
Triangle Park, NC, May 4, 1978.
7. W. R. Seeman, Hydroscience, Inc., Thermal Oxidation Operating Conditions,
(data on file at EPA, ESED, Research Triangle Park, NC) (August 1978).
8. W. R. Seeman, Hydroscience, Inc., Flare Efficiency, in memorandum dated
May 19, 1978 (data on file at EPA, ESED, Research Triangle Park, NC:
transmitted by R. E. White, Hydroscience-, Inc., Aug. 4, 1978).
9. C. C. Mosser, "Storage of Petroleum Liquids," pp. 4.3-13 and 4.3-14 in
Supplement No. 7 for Compilation of Air Pollutant Emission Factors, AP-42, 2d
ed., EPA, Research Triangle Park, NC (April 1977).
10. Chicago Bridge and Iron Co., SOHIO/CB1 Floating Roof Emissions Program. Interim
Report (Oct. 7, 1976); SOHIO/CB1 Floating Roof Emissions Program. Final Report
(November 1976).
11. Federal Register 43(97), 21616 (May 18, 1978).
12. C. C. Mosser, "Transportation and Marketing of Petroleum Liquids," pp. 4.4-4 to
4.4-7 in Supplement No. 7 for Compilation of Air Pollutant Emission Factors,
AP-42, 2d ed., EPA, OAQPS, Research Triangle Park, NC (April 1977).
13. Control of Hydrocarbons from Tank Truck Gasoline Loading Terminals, Guideline
Series, EPA-450/2-77-026 (OAQPS No. 1.2-082), Research Triangle Park, NC
(October 1977).
*A reference located at the end of a paragraph usually refers to the entire
paragraph. If another reference relates to certain portions of the paragraph,
that reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
V. IMPACT ANALYSIS
ENVIRONMENTAL AND ENERGY IMPACT
Storage Tanks
To assess the impacts of the various control options, models that are represen-
tative of the industry storage tanks were devised; see Table V-l for the param-
eters used in the evaluation.
Fixed-Roof Tank Emissions — The quantity of VOC emitted from a fixed-roof tank
is primarily a function of the capacity of the tank itself and the vapor pres-
sure of the chemical stored in the tank. Table 7-2 shows the VOC emissions in
Mg/yr that would be expected for the nine selected model tank sizes at seven
selected vapor pressures.
3 3
The smallest tank selected was 38 m and the largest was 8327 m . The vapor
pressures selected ranged from 1.0 kPa to 51.7 kPa. VOC emissions increase
with increasing tank size and increasing vapor pressure.
Emissions were calculated based on the fixed-roof breathing- and working-loss
equations discussed in: Sect. Ill of this report.
Internal floating roofs used on fixed-roof tanks (new and retrofit) sources —
Table V-3 shows the VOC emission reduction that can be achieved by retrofitting
an internal floating roof to an existing fixed-roof tank.
Reduction efficiencies ranged from 76.3% for the smallest model tank (38 m3)
and lowest vapor pressure (1.0 kPa) to 97.4% for the 1419-m3 capacity tank at
34.5 kPa vapor pressure. Generally, the highest reduction efficiencies are
obtained with the larger model tanks (above 662 m3) containing chemicals at
high vapor pressures (above-6.9 kPa). The emissions calculated were based on
%
the floating-roof standing-storage and withdrawal-loss equations discussed in
Sect. Ill of this report.
In operation, floating-roof storage tanks do not consume any raw materials or
utilities and have no adverse environmental or energy impacts.
-------
V-2
Table V-l. Model Parameters Used for Assessing Impacts of
Industry Storage Tanks*
Model
Tank Capacity
(m3)
Dimensions
(m)
Turnovers
Per Year
Diameter
Height
38
4.5
2.4
200
76
4.5
4.9
200
114
4.5
7.3
200
151
5.1
7.3
200
284
7.0
7.3
100
662
8.3
12.2
50
1419
12.2
12.2
36
2839
17.2
12.2
24
8327
29.5
12.2
12
* 3
Average liquid density of materials controlled = 792 kg/m -
Table V-2. Uncontrolled VOC Emissions vs Absolute Vapor Pressures of
Material Stored for Model Fixed-Roof Tanks*
Tank
VOC
Emissions
(Mg/yr) for
Vapor Pressures of
Capacity
1.0
1.4
3.4
6.9
10.3
34.5
51.7
(m3)
kPa
kPa
k£>a
kPa
kPa
kPa
kPa
38
0:26
0.33
.60
1.00
1.45
3.03
4.66
76
0.44
0.56
1.06
1.78
2.60
5.52
8.43
114
0.61
0.77
1.49
2.53
3.70
7.91
12.05
151
0.83
1.07
2.02
3.43
5.01
10.69
16.29
284
1.36
1.74
3.21
5. ^6
7.74
16.28
24.96
662
2.53
3.24
5.99
10.03
14.53
30.62
46.92
1419
5.03
6.43
11.92
19.99
28.97
61.11
93.60
2839
7.86
9.98
18.11
29.93
42.60
89.73
138.09
8327
16.16
20.29
35.48
57.06
80.95
164.78
256.05
*
Calculated with equations discussed in Sect. Ill,
-------
Table V-3. VOC Emission Reduction from Replacing Fixed-Roof Tanks with Internal-Floating'
Roof Tanks vs Absolute Vapor Pressures of Materials
.. , , m , VOC Emission Reductions (Mg/yr and *) for Vapor Pressures
Model Tank a—* ^
size 1.0 kPa 1.4 KPa 3.4 kPa 6.9 kPa 10.3 kPa 34.5 kPa 51.7 kPa
(m3) (Mg/yr) (ft) (Mg/yr) (ft) (Mg/yr) (t) (Mg/yr) (%) (Mg/yr) <%) (Mg/yr) (ft) (Mg/yr) (%)
38 0.20 76.3 0.26 78.1 0.50 62.7 0.85 85.2 1.25 86.5 2.67 88.1 4.08 87.6
76 0.36 82.3 0.47 84.4 0.94 88.6 J..62 90.8 2.39 91.8 5.14 93.2 7.83 92.9
114 0.5 1 84.3 0.66 86.3 1.35 90.7 2.35 92.8 3.57 93.8 7.52 95.0 11.44 94.9
151 0.71 86.0 0.94 88.2 1.85 92.0 3.21 93.6 4.73 94.4 10.20 95.5 15.54 95.4
284 1.22 89.6 1.59 91.5 2.99 93.3 5.06 94.4 7.35 94.9 15.56 95.6 23.81 95.4
662 2.36 93.3 3.06 94.5 5.73 95.6 9.66 96.3 14.04 96.6 29.71 97.0 45.44 96.8
1419 4.76 94.6 6.14 95.5 11.48 96.3 19.35 96.8 28.12 97.1 59.52 97.4 91.01 97.2
2839 7.43 94.9 9.53 95.5 17.41 96.1 28.89 96.5 41.66 96.8 87.08 97.0 133.78 96.9
8327 15.26 94.4 19.33 95.3 33.96 95.7 54.79 96.0 77.87 96.2 158.89 96.4 246.44 96.2
-------
V-4
Refrigerated vent condenser (new and retrofit sources) -- Table V-4 shows the
model parameters used for assessing the impacts from addition of a refrigerated
vent condenser to a fixed-roof tank. Three model tank sizes (151, 662, and
2839 m ), representing a small, medium, and large SOCMI storage tank, respec-
tively, were selected for evaluation.
Three different cases representing three commmon conditions of condenser opera-
tion were selected for each of the model tanks and are also shown in Table V-4.
For case I it was assumed that the chemical stored has a low vapor pressure,
3.5 kPa, and that the vapor pressure of the exit gas stream leaving the con-
denser has been reduced to 1.4 kPa. Case II is an evaluation of the storage of
an average-vapor-pressure (10.3 kPa) chemical with a final (exit) vapor pres-
sure of 1.4 kPa. For case III it was assumed that the chemical stored, has a
high vapor pressure, 51.7 kPa, and that the exit stream vapor pressure has been
reduced to 3.5 kPa.
The physical properties of three different chemicals with vapor pressures nearly
equal to the initial vapor pressures described for cases 1, 2, and 3 were averaged.
These averages were used to calculate the size of each condenser and its accom-
panying refrigeration system. Sizing details are shown in Appendix B.
Table V-5 shows the VOC emissions expected from the three model fixed-roof tanks
before and after a refrigerated vent condenser was added. Quantities are shown
for all three cases of operation selected.
Refrigerated vent condensers do not consume any raw materials, but do require
electricity. The electrical requirements for each of the model tanks selected
is shown in Table V-6 as Joules per gram of VOC recovered. Values range from
239 to 1425 J/g.
b. Floatinq-Roof-Tank Emissions — The quantity of VOC emitted from a floating-
roof tank is primarily a function of the capacity (size) of the tank itself and
the vapor pressure of the chemical stored in the tank. Table V-7 shows the VOC
emissions in Mg/yr that would be expected for the nine selected model tank sizes
at five selected vapor pressures.
-------
V-5
Table V-4. Model Parameters and Operating Conditions for Assessing
Impacts from Refrigerated Vent Condensers
Fixed-Roof
Tank Capacity
Turnovers Vapor Pressure (kPa)
Per Year Initial Final
Final
Temp.
Emission
Reduction
<*>
1S1
662
2839
151
662
2839
151
662
2839
200
50
24
200
50
24
2001
50 *
24!
Case 1
3.5
Case 2
10.3
Case 3
51.7
1.4 10
1.4
-9.6
3.5 -20.3
60
86.7
93.3
Table V-5. VCC Emissions from Fixed-Roof Tanks
Before and After Refrigerated Condenser Add-On
VOC Emissions (Mq/yr)
Model Tank^ Before Add-On After Add-On
Capacity (m ) Case I Case II Case III Case I Case II Case III
151 2.02 5.01 16.29 0.81 0.69 1.09
662 5.99 14.53 46.92 2.40 1.99 3.14
2839 18.11 42.6 133.09 7.24 5.84 9.25
Table V-6. Energy Impact from .Refrigerated
Vent Condenser
Capacity (ra3)
Electrical Requirements (J/q)
Case- I
Case II
Case III
151
1425
562
423
662
626
348
362
2839
307
239
338
-------
7-6
Table V-7. VOC Emissions from Model Floating-Roof Tank
vs Absolute Vapor Pressures of Material Stored
VOC Emissions (Mq/yr) for Vapor Pressures of
Model Tank.
51.7
69.0
76.6
86.2
100.7
Capacity (m )
kPa
kPa
kPa
kPa
kPa
38
0.58
0.94
1.22
1.86
17.88
76
0.60
0.96
1.23
1.87
17.90
114
0.61
0.98
1.25
1.89
17.92
151
0.75
1.20
1.54
2.33
22.11
284
1.16
1.88
2.43
3.70
35.59
662
1.47
2.40
3.10
4.74
45.66
1419
2.59
4.23
5.48
8.38
80.96
2339
4.31
7.08
9.17
14.05
135.96
8327
9.62
15.83
20.51
31.45
304.88
-------
V- 7
Emissions were calculated based on the standing-storage- and withdrawal-loss
equations discussed in Sect. Ill of this report for an internal floating-roof
tank.
Pressure vessels used in place of internal-floating-roof tanks or open-top
floating roof tanks with primary and secondary seals (new sources) — Two pres-
sure vessel conditions are evaluated: No VOC loss (100% emission control), and
98%-controlled VOC emissions. The later condition would apply to pressure ves-
sels with an inert-gas pad used for safety or operating reasons that would there-
fore require periodic relief venting. Table V-8 shows the VOC emission reduc-
tion that can be achieved by installation of a new pressure vessel instead of a
new floating-roof tank. Both the 98% and 100% control conditions are shown.
In operation, pressure vessels used as emission controls do not consume any raw
materials or utilities* and have no adverse environmental or energy impacts.
Secondary seals used on open-top floating-roof tanks (new and retrofitted sources) —
Unless the open-top floating-roof tank is equipped with a modern secondary seal,
it is subject to a larger standing-loss emission due to wind effect.
Table V-9 shows the model parameters used for assessing the impact of adding a
secondary seal to an existing or new open-top floating-roof tank. Three model
tank si2es (1419, 2839, and 8327 m^) representing those sizes of open-top
floating-roof storage tanks most commonly used were selected for evaluation.
Table V-10 shows the VOC emissions expected from the three model open-top
floating-roof tanks before a secondary seal was installed. The emissions,
shown for five selected vapor pressures of chemicals stored, were calculated
from the standing-storage-loss and withdrawal-loss equations discussed in
Sect. III. & wind speed (v^) value of 9 mph was used.
Table V-ll shows the VOC emission reduction (Mg/yr) that can be achieved by a
new or retrofitted secondary seal installation on a open-top floating-roof tank.
A value of 75% for the control efficiency of the secondary seal was used based
on industrial test results.1
-------
Size
/ 3v
36
76
114
151
284
662
1419
2839
8327
VOC Emission Reduction from Installation of New Pressure Vessels Instead of New
Floating-Roof Tanks as a Function of Stored-Material Vapor Pressures
VOC Emission Reductions (Hq/yr)
51.7 kPa 69.0 kPa 76.6 kPa 86.2 kPa 100.7 kPa
(96%) (100%) (98%) (100%) (98%) (100%) (98%) (100%) (98%) (100%)
0.57
0.58
0.92
0.94
1.19
1.22
1.82
1.86
17.53
17.88
0.58
0.60
0.94
0.96
1.21
1.23
1.84
1.88
17.54
17.90
0.60
0.61
0.96
0.98
1.23
1.25
1.85
1.89
17.56
17.92
0.74
0.75
1.18
1.20
1.51
1.54
2.28
2.33
21.66
22.11
1.13
1.16
1.84
1.88
2.38
2.43
3.63
3.70
34.86
35.59
1.44
1.47
2.36
2.40
3.04
3.10
4.65
4.74
44.75
45.66
2.53
2.59
4.15
4-24
5.37
5.48
8.21
8.38
79.34
80.96
4.23
4.31
6.94
7.08
8.99
9.17
13.77
14.05
133.24
135.96
9.42
9.62
15.51
15.83
20.10
20.51
30.82
31.45
298.79
304.88
<
i
00
-------
V-9
Table V-9. Model Parameters for Assessing
Impacts from Secondary Seals on
Open-Top Floating-Roof Tanks*
Tank ,
Capacity (m )
Dimensions
Diameter
(m)
Heiqht
Turnovers
Per Year
1419
12.2
12.2
36
2839
17.2
12.2
24
8327
29.S
12.2
12
~Average liquid density of chemicals stored = 792 kg/m^.
Table V-10. VOC Emissions from Open-Top Floating-Roof Tanks
Before Addition of Secondary Seal*
VOC Emissions (Mq/yr) for Vapor Pressures of
Model Tank-
Capacity (m )
3.4
10.3
34.5
51.7
69.0
kPa
kPa
kPa
kPa
kPa
1419
0.74
1.47
2.78
4.53
7.44
2839
1.21
2.44
4.64
7.58
12.46
8327
2.66
5.41
10.36
17.84
27.90
*Average wind. speed = 9 raph (v^; see Sect. III).
Table V-ll. VOC Emission Reduction from Installation of
Secondary Seals on Open-Top Floating-Roof Tanks
vs Absolute Vapor Pressures of Material Stored
VOC Emissions (Mq/yr) for Vapor Pressures of
Model Tank^
3.4.
10.3
34.5
51.7
69.0
Capacity (m )
kPa
kPa
kPa
kPa
kPa
1419
0.55
1.10
2.09
3.40
5.58
2839
0.91
1.83
3.48
5.68
9.35
8327
2.00
4.06
7.77
13.38
20.93
-------
V-10
In operation, secondary seals do not consume any raw materials or utilities and
have no adverse environmental or energy impacts.
2. Loading and Handling
A model loading terminal sized for handling 950 m3 of organics per day was selected
for evaluation of the cost effectiveness of two control methods. The model was
selected from the EPA Guideline Series document Control of Hydrocarbons from Tank
2
Truck Gasoline Loading Terminals. The use of this model was considered to be
acceptable because petroleum loading operations compare reasonably well with
those of the SOCMI.
Two controls taken from the document are evaluated: a refrigerated condenser
system that condenses VOC vapors at atmospheric pressure and -73°C temperature,
and an oxidation system based on a thermal oxidizer.
Table V-12 shows the theoretical control efficiencies of the condenser for the
four vapor pressures selected. The control efficiency of the thermal oxidizer
was estimated to be 99%.
Table V-13 gives the VOC emissions expected from the model terminal before
controls and after either the refrigeration or oxidizer system was installed.
Emissions were calculated with the equations discussed in Sect. Ill and averaged
from the vapor pressures given in Table III-3.
The energy effect of vapor recovery systems at terminals is considered to be
minimal. Although energy is required to drive compressors, pumps, and other
equipment, in most systems a valuable product is recovered that would otherwise
be lost to the atmosphere. In thermal oxidizer systems additional energy will
be required in the form of gaseous fuel to convert the VOC vapor to carbon dioxide
and water. An estimated 85 liters of propane per Mg of product per year is
2
required by the oxidizer.
-------
V-ll
Table V-12. Control Parameters of Model
Loading Terminal for Refrigeration System
Theoretical
Control Vapor Pressure (kPa)
Efficiency (%) Initial Final
60 3.5 1.4
86.7 10.3 1.4
93.3 34.5 3.5
94.9 69.0 3.5
Table V-13. VOC Emissions from Model Loading Terminal
Before and After Addition of Controls
VOC Emission (Mg/yr)
Vapor Pressure
(kPa)
Before Controls Added
After Controls Added
Refrigeration Oxidizer System
3.5a
15.8
6.3
0.2
10.3b
76.3
10.5
o
•
CD
34.5C
123.8
8.3
1.2
69.0d
267.8
13.7
2.7
Uncontrolled emission rate, 55 mg per liter loaded (derived from Table III-3).
b
Uncontrolled emission rate, 265 og per liter loaded (derived from Table III-3).
Uncontrolled emission rate, 430 mg per liter loaded (derived from Table III-3).
d-
Uncontrolled emission rate, 930 mg per liter loaded (derived from Table III-3).
-------
V-12
CONTROL COST IMPACT
This section presents estimated costs and cost-effectiveness ratios for the
additional control of VOC emissions from the storage and loading of organic
chemicals in the synthetic organic chemicals industry. Present emission sources
and emission quantities are discussed in Sect. III.
The capital cost estimates represent the total investment involved in purchasing
and installing all equipment and material necessary for a complete control sys-
tem that will perform as defined for a new or retrofitted installation at a
typical location. These estimates do not include such highly variable costs as
loss of production during installation or startup, research and development,
land acquisition, and preparation and cleaning of the tanks for retrofitting.
Cost estimate calculations are included in Appendix B.
Cost factors for calculation of annual operating costs are shown in Table V-14.
The capital recovery factor of 0.147 is based on a 12-year depreciable life and
a 10% annual interest rate. Emission recovery credit is based on the average
market value of all synthetic organic chemicals that have potential recovery.
Annual costs are for a 1-year period beginning in mid-1978.
Storage Tanks
Fixed-Roof-Tank Emission Controls — The capital cost and the cost effectiveness
of controlling VOC emission losses with two new and two retrofitted sources are
evaluated:
Internal-floating roof used on fixed-roof tanks (new and retrofit) — For new
internal floating-roof tank installation, the annual operating cost is calculated
from the incremental capital cost difference between a new internal floating-roof
tank and a new fixed-roof tank.
Table V-15 shows the installed capital cost and the annual operating cost for
both installation conditions (new and retrofit). The annual operating cost is
the cost of the internal floating roof before recovery credit is taken for emis-
sion reductions. The installed capital costs for new fixed-roof and new internal
and retrofit floating roofs were taken from the curve shown in Appendix B
(Fig. B-2).
-------
V-13
Table V-14. Cost Factors for Computing Annual Costs
Item
Factor
Electrical power
8.33 5/GJ
Operating time
8760 hr/yr
Operating labor
Minor; not considered
Maintenance material and labor
$0.05 X capital cost
Capital charges
Capital recovery
$0,147 X capital cost
Miscellaneous (taxes, insurance.
$0.04 X capital cost
and administration)
Liquid-waste disposal
Minor; not considered
Recovery credit
$330.8/Mg
Table V-15. Installed Capital and Operating Costs for
Internal-Floating-Roof Tanks {New and .Retrofitted Sources)
Model
Tank Size
(m3)
Installed Capital Cost (X 103)
Annual Operating Costa
(X 103)
Ab
Bb
A
B
38
$21.0
$11.0
$ 5.0
$ 2.6
76
22.0
13.0
5.2
3.1
114
23.0
13.0
5.5
3.1
151
24.0
13.0
5.7
3.1
284
27.0
14.0
6.4
3.3
662
39.0
14.0
9.2
3.3
1419
47.0
23.0
11.1
5.5
2839
66.0
46.0
15.6
10.9
8327
118.0
108.0
28.0
25.6
£
Before credit.
b
A = Fixed-roof tank retrofitted with floating roof.
B = Incremental cost of new internal-floating-roof vs new fixed-roof tank.
-------
V-14
The installed capital costs for tanks shown in Fig. B-2 was prepared pri-
marily from data presented in the EPA, OAQPS report Evaluation of Hydrocarbon
Emissions from Petroleum Liquid Storage,^ which was prepared by Pacific Environ-
mental Services under Contract 68-02-2606. The curves plotted are judgmental
averages of the data presented. Additional retrofit cost information was obtained
4 5 6
by telephone from Chicago Bridge and Iron, Ultraflote, General American, and
7
Graver Tank Co. The highest retrofit cost quoted by these companies was used
as a base. The retrofit curve was then increased to compensate for freight,
taxes, engineering, and estimated allowances.
In all capital calculations, allowances of 12 to 28% were added for magnitude,
hazard, and definition contingencies.
Table V-16 gives the cost effectiveness for two tank options: Retrofitting a
floating roof to an existing fixed-roof tank or installing a new tank with a
floating roof istead of installing a new tank with a fixed roof. In each case
the cost is affected by the vapor pressure of the material stored in the model
tank. The cost effectiveness versus tank size is plotted in Fig. V-l for a
retrofitted fixed-roof tank and is plotted in Fig. V-2 for a new tank with
internal floating-roof rather than one with a fixed-roof.
Refrigerated vent condensers (new and retrofit sources) — To evaluate the con-
trol cost effectiveness of adding a refrigerated vent condenser to a new or
existing fixed-roof tank, the models and conditions discussed in the environ-
mental and energy impact portion of this section are used. See Tables V-4—V-6.
Table V-17 gives the cost effectiveness for adding-on refrigerated vent con-
densers to the fixed-roof model tanks for all three cases. Cost estimation
details are given in Appendix B. Figure 7-3 is a plot of the cost effective-
ness for the three model conditions.
The cost effectiveness for multiple storage tanks containing the same material
and using a common add-on refrigeration unit should be more favorable than the
cost effectiveness for equivalent storage using individual controls. These
highly variable situations were not modeled.
-------
Tabl£ V-16. Cost Effectiveness for Two Fixed-Roof-Tank Control Options as a
Function of Material Vapor Pressures
Cost Effectiveness (per Kg)
Model Tank
Size
Retrofitted Fixed-Roof Tanks with
Floating Roofs at Vapor Pressures of
New Floating-Roof Tanks®
wlf-h Unnor Pross.irna nf
(m3)
1.0 kPa
1.4 kPa
3.4 kPa
6.9 kPa
10.3 kPa
34.5
kPa
51.7 kPa
1.0 kPa
1.4 kPa
3.4 kPa
&.9 kPa
10.3 kPa
34.5 kPa
51.6 kPa
38
$24,680
$19,141
$9,672
$5,510
$3,669
$1
.542
$895
$12,680
$9,766
$4,872
$2,696
$1,749
$644
$307
76
14.111
10,548
5,203
2,901
1,845
681
333
8,250
6,118
2,969
1,605
969
272
65
114
10.453
8,006
3,744
1,999
1,254
401
150
5,747
4.381
1,966
978
563
82
(60)
151
7.696
5,745
2,750
1,433
874
228
36
4,034
2,979
1,344
623
325
(27)
(131)
284
4.915
3,704
1.809
930
540
ax
(62)
2,374
1.756
773
317
118
(119)
(192)
662
3,567
2,680
1*275
621
325
<211b
(128)
,1,067
752
245
10
(96)
(220)
(258)
1.419
2,001
1,482
636
243
64
(144)
(209)
825
570
148
(47)
(135)
(238)
(270)
2,819
1,769
1,302
565
208
44
(152)
(214)
1,136
808
, 295
45
(69)
(206)
(249)
8,327
1,504
1.117
494
181
29
(155)
(217)
1,347
993
423
137
(2)
(170)
(227)
flBased on incremental cost difference between the cost of a new floating-roof tank minus the cost of new fixed-roof tanks.
^Values in parentheses represent credits.
-------
6000
cn
\
v>
•a
o
o
4J
C
o
u
w
c
0
¦H
ID
01
•H
E
W
0
•P
•o
0)
o
+J
w
o
u
5000
4000
3000
2000
-500
1000
i • i
2,000 3,000
f
i-1
cn
10,000
Tank size (m )
Fig. V-l. Cost Effectiveness of Controlling Emissions by Retrofitting Existing Fixed-Roof
Tanks with Floating Roofs
-------
6250
u>
u
o
4J
•H
'O
a>
n
u
u
(n
o
o
5000 =
4000 "
3000 i
2000 '
I
1000
f
Tank size (m )
2,000 3,000 5,000
10,000
Fig. V-2. Cost Effectiveness of Installing New Floating-Roof Tanks vs New Fixed-Roof Tanks
for Controlling Emissions
-------
V-18
Table V-17. Cost Effectiveness for Add-On Refrigerated Vent
Condenser to Fixed-Roof Tank (New and Retrofitted Sources)
Model Tank
Size
(m3)
Cost Effectiveness*
(per Ilq)
Case 1
Case 2
Case 3
151
$14,000
$4,300
$1,300
662
5,850
2,200
1,000
2839
3,400
1,400
700
~Case conditions described in Table V-4.
-------
14,000
12,000 j-
tn
s:
•o
4>
O
v,
¦p
c
0
u
in
c
o
in
in
¦d
8
>
u
o
+J
in
o
u
10,000 r I
8,000 j"
f
VO
Tank size (m )
10,000
Fig. V-3. Cost Effectiveness of Controlling Emissions by Refrigerated Vent Condenser Added On to Fixed-Roof Tank
-------
V-20
b. Floating-Roof-Tank Emission Controls — The capital cost and the cost effective-
ness of controlling VOC emission losses with two sources are evaluated:
Pressure vessels used in place of internal-floating-roof tanks or open-top
floating-roof tanks with primary and secondary seals (new sources) — To evalu-
ate the control cost effectiveness of installing new, low-pressure service
(172 kPa maximum) vessels instead of new floating-roof tanks, the models and
emisson reductions discussed in Sect V-A are used. The annual operating cost
is calculated from the incremental capital cost difference between a new,
internal-floating-roof tank and a new pressure vessel.
Table V-13 shows the installed capital cost and the annual operating cost,
before credit is taken for emission recovery, for each of the model tank sizes.
Installed capital costs are based on the cost data for fixed-roof tanks
factored by engineering estimates to represent current low-pressure service
vessel costs and adding 12 to 26% for allowances. Cost estimation details are
given in Appendix B.
Table V-19 gives the cost effectiveness for installing new pressure vessels at
the 98 and 100% control conditions. Figures V-4 and V-5 are plots of the cost
effectiveness for the new-pressure-vessel installation at 98% and 100% control
efficiency conditions, respectively.
Secondary seals used on open-top floating-roof tanks (new and retrofitted
sources) — To evaluate the cost of installing a secondary seal on an existing
or new, open-top floating-roof tank, the models and emission reductions dis-
cussed in Sect. V-A are used. The capital and operating costs for a modern
secondary seal installed above the primary seal for the model conditions are
shown in Table V-20 for both new and retrofitted sources. The capital cost for
g
installing the secondary seed is based on $85/linear meter for a new tank and
$138/linear meter^ for retrofitting an existing tank.
Table V-21 gives the cost effectiveness of the secondary seal for both new and
retrofitted installations.
-------
V-21
Table V-18. Installed Capital and Operating Costs for
Pressure Vessels
Model Tank
Capacity (m3)
Installed Capital
Cost (X 103)a
Annual Operating
Cost (X 103)b
38
$ 7.8
$ 1.9
76
5.8
1.4
114
4.2
1.0
151
6.8
1.6
284
14.0
3.3
662
34.5
8.2
1419
64.6
15.3
2839
102.9
24.4
8327
242.7
57.5
£
Incremental cost difference between new pressure vessel and new
floating-roof tank.
^23.7% of capital cost before recovery credit.
-------
Table V-19. Cost Effectiveness for Installing a New Pressure Vessel Instead of a New Floating-Roof Tank
(Incremental Cost Difference) as a Function of Stored-Material Vapor Pressures
Cost Effectiveness (per Mq)
nuucj. laiift
Size
/ 3\
(m )
98% Control Efficiency at
Vapor Pressures of
100% Control Efficiency at
Vapor Pressures of
51.7
kPa
69.0
kPa
76.6
kPa
86.2
kPa
100.7
kPa
51.7
kPa
69.0
kPa
76.6
kPa
86.2
kPa
100.7
kPa
38
$3015
$1722
$1257
$ 714
($223)*
$2952
$1688
$1233
$ 688
($225)
76
2075
1160
827
430
(251)
2017
1126
801
416
(253)
114
1333
711
481
210
(274)
1307
697
472
196
(275)
151
1848
1029
729
368
(257)
1798
1000
708
356
(258)
283
2574
1459
1055
579
(236)
2524
1424
1029
559
(237)
662
5346
3151
2364
1433
(147)
5234
3079
2310
1398
(151)
1419
5709
3357
2519
1532
(138)
5586
3282
2464
1495
(142)
2839
5444
3184
2384
1442
(148)
5328
3115
2330
1406
(151)
8327
5771
3376
2529
1535
(138)
5647
3301
2472
1498
(142)
*Values in parentheses represent credits.
-------
6000
\
to
•a
o
o
u
q
c
u
in
C
0
•n
(ft
(ft
¦ri
£
8
>
>-l
C
+J
(A
O
5000
4000
3000
1000
-500
2000 !
Model tank size (m )
Fig. V-4. Cost Effectiveness of Controlling Emissions (100%) by
Installinq New Pressure Vessel vs New Floating-Roof Tank
-------
6000
5000
4000
3000
2000
1000
-500
I M'P"—p
i
'i :!" 1;1 r\j_j'l' i'i ij :¦ 1~;
1 , I I I | ,|—¦;;-H'j I I I I||I|!IM';|I!|<;|-|"-'I- • • I • -i- .-|-l j -• • • I • : 111 ¦¦ ,
• ¦ • ¦ ¦ i • t' * 11 •: *i ¦: !:r "i: • i i "';!l|i! i"!!":;1!1:! "• i i ! I' i ; i M !: - lii'-i;.i'
; ' ] -¦ i~i ¦¦ 11 hn '1111il11i:ii)j ;'11111M i!!ii!i!!!:!!i|_"_"]. j_!j„'..LLL!J.i !i:L:l!J!liL'"!!-!JILi:! 1.1 Mli;.'!.'!
<
i
to
30
100
1000
10,000
Model tank size (m )
Fig. V-5. Cost Effectiveness of Controlling Emissions (98*) by
Installing New Pressure Vessel vs New Floating-Roof Tank
-------
V-25
Table V-20. Installed Capital and Operating Costs for Secondary Seals on
Open-Top Floating-Roof Tanks (New and Retrofit Sources)
Model Tank- Installed Capital Cost (X 103) Annual Operating Cost (X 10^)a'^
Capacity (m ) Hew Retrofit New Retrofit
1419 $3258 $ 5,289 $ 772 $1253
2839 4593 7,456 1089 1767
8327 7878 12,789 1867 3031
a23.7% of capital cost installed.
bBefore recovery credit.
Table V-21. Cost Effectiveness of Installing Secondary Seals on
Open-Top Floating-Roof Tanks for Both New and Retrofitted Sources
Tank Cost Effectiveness (per Mq)
Vapor Pressure (kPa) New Source Retrofitted Source
1419-ra?
Tank Capacity
3.4
$1063
$1931
10.3
369
806
34.5
39
269
51.7
(104)*
38
69.0
(192)
(106)
2839-m3
Tank Capacity
3.4
$867
$1612
10.3
275
637
34.5
(18)
177
51.7
(139)
(20)
69.0
(214)
(142)
8327-ra3
Tank Capacity
3.4
$600
$1182
10.3
129
416
34.5
(90)
59
51.7
(191)
(104)
69.0
(242)
(186)
*Values in parentheses represent credits.
-------
V-26
2. Loading and Handling
To evaluate the control cost effectiveness of installing either the refrigera-
tion or oxidizer system for loading terminals, the model and emission reductions
described in Sect. V-A are used.
All installed capital cost and operating cost data shown in Table V-22 were
taken from the EPA Guideline series document Control of Hydrocarbons from Tank
2
Truck Gasoline Unloading Terminals and adjusted to reflect mid-1978 dollars.
Table V-23 gives the cost effectiveness for installing either the refrigeration
or oxidizer system at the model terminal for loading chemicals with four selected
vapor pressures.
-------
V-27
Table V-22. Installed Capital and Operating Cost for Model-
Loading-Terminal3 Control Systems (950 m3/day)
Control System
Installed Capital Cost (X 103)
^ H
Annual Operating Cost (X 10 )
Refrigeration
$186.6
$43.8
Oxidizer
148.4
31.6
?Top-submerged or bottom-filled.
Based on 23.7% of capital before recovery credit.
Table 7-23. Cost Effectiveness for Loading-Terminal
(950 m3/day) Control Systems vs Material Vapor Pressures
Vapor Pressure
(kPa)
Cost Effectiveness
(per Mq)
Refrigeration
System
Oxidizer
System
3.5
$4284
$2026
10.3
334
419
34.5
48
258
69.0
(158)*
119
*Values in parentheses represent credits.
-------
V-28
C. REFERENCES
1. Chicago Bridge and Iron Co., SOHIO/CBI Floating Roof Emissions Program. Interim
Report (Oct. 7, 1976); Final Report (November 1976).
2. Control of Hydrocarbons from Tank Truck Gasoline Loading Terminals, Guideline
Series, EPA-450/2-77-026 (OAQPS No. 1.2-082), Research Triangle Park, NC
(October 1977).
3. Evaluation of Hydrocarbon Emissions from Petroleum Liquid Storage, Pacific
Environmental Services, Inc., Santa Monica, CA (data on file at EPA, ESED,
Research Triangle Park, NC) (October 1977).
4. N. Acosta, Chicago Bridge and Iron Co., telephone conversation conveying fixed
roof and internal floating-cover data, to J. R. Fordyce, Hydroscience, Inc.,
Feb. 24, 1978 (memo on file at Hydroscience).
5. Information ocnveyed by Roy Seal and R. Kern, Ultraflote Corporation, concern-
ing retrofitted storage tanks with floating roofs, to J. R. Fordyce, Hydroscience,
Inc., Feb. 24—28, 1978.
6. Information conveyed by M. Heisterberg, General American Transportation,
concerning retrofitted floating roof, to J. R. Fordyce, Hydroscience, Inc.,
Feb. 24, 1978.
7. Information conveyed by J. M. Asurdi concerning Graver Tank API-650 storage
tanks, cone roof and internal floater, to J. R. Fordyce, Hydroscience, Inc.,
Feb. 28, 1978.
8. Personal phone communication between J. Shumaker, EPA, ESED, Research Triangle
Park, NC, and D. Erikson, Hydroscience, Inc., Knoxville, TN, Aug. 10, 1978.
*A reference located at the end of a paragraph usually refers to the entire para-
graph. If another reference relates to certain portions of the paragraph, the
reference number is indicated on the material involved. When the reference
appears on a heading, it refers to all the text covered by that heading.
-------
VI-1
VI. ASSESSMENT
A. SUMMARY
1. Storage
The synthetic organic chemicals industry currently uses a total of 20,270 fixed-
roof tanks, floating-roof tanks and pressure vessels for VOC storage. The primary
type of storage vessel utilized by the industry is the fixed-roof tank. It
comprises 73% of the total number of storage vessels and contributes 61% of the
total storage volume. Its primary drawback is its high susceptibility to breath-
ing and working losses. The emission sources and control levels for industry
storage are shown in Tables III-4- and III-5. Current emissions for all industrial
storage are estimated to be 45,259 Mg/yr. Fixed-roof tanks account for an esti-
mated 96% of the total storage VOC losses.
Pressure vessels are the most efficient storage tanks, and have negligible emis-
sions during normal operation. The use of floating-roof tanks is a significant
control measure, with internal floating roofs being 50 to 75% more effective
than open-top floating-roof tanks without secondary seals and being 95% more
effective than fixed-roof tanks. Refrigerated vent condensers are one of the
most common types of control devices now in use on fixed-roof tanks with con-
trol.
Fixed-roof-tank emissions can be controlled by means of internal floating-roof
tanks and refrigerated vent condensers- in a new plant or by retrofitting float-
ing roofs or refrigerated, vent condensers on existing fixed-roof tanks. The
emission reduction would be 76% to 97+% for floating roofs and 60% to 95+% for
refrigerated vent condensers. The cost effectiveness for retrofitting floating
roofs is not as good as that of new installations but both can yield credits
($200+/Mg) at high vapor pressures. Refrigerated vent condensers on individual
fixed-roof tanks are not as cost effective as floating-roof tanks.
Floating-roof-tank emissions can be eliminated by installation of pressure ves-
sels in new plants. Cost effectiveness for pressure vessels is most favorable
at high vapor pressures and small tank sizes. The use of secondary seals on
open-top floating roofs can reduce emissions 75%, resulting, in very favorable
cost effectiveness (credits).
-------
VI-2
2. Loading
An estimated 3,393,100 Mg of synthetic organic material is shipped by the industry.
Cargo carriers include tank cars, tank trucks, and marine vessels, with water
transportation accounting for 50% of the total volume of chemicals shipped. An
estimated 81% of all chemicals shipped have vapor pressures of less than 34.5 kPa.
The emission sources and control levels for the industry loading are shown in
Fig. III-6. Current emissions for all chemical loading and transport are esti-
mated to be 4917 Mg/yr.
The industry currently uses both splash filling and submerged- or bottom-filling
methods for loading all types of carriers with a wide vapor pressure range of
chemicals. The use of refrigerated condensers or a vapor oxidizer is a signifi-
cant control measure when applied to chemicals with vapor pressures in excess
of 3.5 kPa. VOC emission reductions of 70 to 90% are possible. The use of
pressurized carriers eliminates transit losses.
Refrigerated condensers systems can have favorable cost effectiveness if used
on high-vapor-pressure materials, yielding credits as high as $200 per Mg of
voc controlled.
B. SUPPLEMENTAL INFORMATION
The primary basis for characterization of the storage and handling segment of
the SOCMI was the State Emissions Inventory files obtained from Texas and Louisiana.
It would be appropriate to update the present data base when supplemental tank
data from additional site visits resulting from new product study assignments
and other State Emissions Inventory files become available. This task should
be initiated within the next year.
Emission calculations are based primarily on AP-42 equations, as noted in Sect. III.
These relationships are not reliable when the equations are applied outside the
range of parameters of the petroleum industry for which they were intended.
Continuing industrial pilot studies on both fixed-roof and floating-roof tanks
should aid in revision of the estimation methods for computing VOC emission
levels for various storage situations.
-------
VI-3
Two segments of the petroleum industry — one represented by the consortium of
Chicago Bridge and Iron Co. and Standard Oil of Ohio and the other by Western
Oil and Gas Association (WOGA) — have been conducting programs to better define
the characteristics and magnitudes of emissions from petroleum storage tanks.
WOGA's investigation* has showed that the standing-storage losses for crude
oils with true vapor pressures of 2.1 to 36.2 kPa and for distillates with true
vapor pressures of 0.07 to 2.4 kPa averaged 58% of the emissions calculated
based on the API correlations discussed in Sect. III.
Completion of these programs should provide a sound basis for quantification of
storage emissions and an assessment of VOC emission control approaches and their
effectiveness.
-------
VI-4
REFERENCE*
Hydrocarbon Emissions from Fixed-Roof Petroleum Tanks, Engineering-Science
Inc., Arcadia, CA (July 1977) (prepared for The Western Oil and Gas Association,
Los Angeles, CA).
*A reference located at the end of a paragraph usually refers to the entire paragraph.
If another reference relates to certain portions of the paragraph, the reference
number is indicated on the material involved. When the reference appears on a
heading, it refers to all the text covered by that heading.
-------
APPENDIX A
EMISSION CALCULATION SUPPLEMENTS
-------
A-2
Table A-l. Paint Factors for Fixed-Roof Tanks
Faint Factors (Fp)
Tank Color
Paint
Condition
Roof
Shell
Good
Poor
White
White
1.00
1.15
Aluminum (specular)
White
1.04
1.18
White
Aluminum (specular)
1.16
1.24
Aluminum (specular)
Aluminum (specular)
1.20
1.29
White
Aluminum (diffuse)
1.30
1.38
Aluminum (diffuse)
Aluminum (diffuse)
1.39
1.46
White
Gray
1.30
1.38
Light gray
Light gray
1.33
1.44*
Medium gray
Medium gray
1.40
1.58*
^Estimated from the ratios of the seven preceding paint factors.
-------
Table h-2. Tank, Type, Seal, and Faint Factors for Floating-Roof Tanks
Tank Type
V
Seal Type
Ks*
Painted Color of
Shell and Roof
Melded tank with pan or pontoon 0.0045
roof, single or double seal
Riveted tank with pontoon roof, 0.11
double seal
Riveted tank with pontoon roof, 0.13
single seal
Riveted tank with pan roof, 0.13
double seal
Riveted tank with pan roof, 0.14
single seal
Tight fitting (typical of modern 1.00
metallic and non-metallic seals)
Loose fitting (typical of seals 1.33
built prior to 1942)
Light gray or
aluminum
White
1.0
0.9
*See "Calculations" in Sect. III.
-------
A-4
Table A-3. S Factors for Calculating Petroleum Loading Losses
Cargo Carrier Mode of Operation S Factor
Tank trucks and tank cars Submerged loading of a clean 0.50
cargo tank
Splash loading of a clean 1.45
cargo tank
Submerged loading: normal 0.60
dedicated service
Splash loading: normal 1.45
dedicated service
Submerged loading: 1.00
dedicated, vapor balance
service
Splash loading: dedicated 1.00
vapor balance service
Marine vessels Submerged loading: ships 0.2
Submerged loading: barges- 0.5
*Saturation factor; see "Calculations" in Sect. III.
-------
APPENDIX B
COST ESTIMATE DETAILS AND CALCULATIONS
FLOATING ROOF - REFRIGERATED VENT CONDENSER - PRESSURE VESSEL
-------
B-2
COST ESTIMATE DETAILS
This appendix contains the details of the estimated costs presented in this
report.
The accuracy of an estimate is a function of the degree of data available when
the estimate was made. Figure B-l illustrates this relationship. A contin-
gency allowance as indicated on this chart has been included in the estimated
costs to cover the undefined scope of the project.
Capital costs given in this report are based on a screening study, as indicated
by Fig. B-l, based on general design criteria, block flowsheets, approximate
material balances, and data on general equipment requirements. These costs
have an accuracy range of +40% to -30%, depending on the reliability of the
data, and provide an acceptable basis to determine the most cost-effective
alternate within the limits of accuracy indicated.
Figure B-2 shows the installed capital costs for tanks and was prepared primar-
ily from data presented in the EPA, OAQPS, report Evaluation of Hydrocarbon
Emissions from Petroleum Liquid Storage, which was prepared by Pacific
Environmental Services under Contract 68-02-2606. The curves plotted are
judgmental averages of the data presented. Additional retrofit cost informa-
tion was obtained by telephone from Chicago Bridge and Iron, Ultraflote, and
Grover Tank Co. The highest retrofit cost quoted by these companies was used
as a base. The retrofit curve was then increased to compensate for freight,
taxes, engineering, and estimated allowances.
In all capital calculations, allowances of 12 to 28% were added for magnitude,
hazard, and definition contingencies.
-------
II
I
\\
V
\
\
W
APPRO)*. Co-bT
EN^R. 4 E.«oT.
(*/. OP TOTAL
Probable
CAP. COST)
PR OB.
CO*>T
ESTIMATED COST
WITH ALLOWAUCE.
, MAX- PRoft.
COST
0)
l
\
\\
/
//
f
1
_J
/
!f)
/
/
\>
\\
\
\
{>
1V
11
1
/.
//
i
V
t
k
111
/
1
1
11
1
1
1
i
I
i
-fco -4o -Z0
2o 4o fco
rawcjG. - probable
ACTUAL PROJECT
COST (%)
IO ZQ to 4(
"7" AlXOWAKiCE.
TO INCLUDE,
Fig. B-l. Precision of capital Cost Estimates
LAcrew Re.Vis.iou - 6/fc/n
-------
Tank Capacity (1000 bbl)
Fig. B-2. Installed Capital Costs for Tanks
-------
Tank Capacity (bbl)
Fig. B-3. Installed Capital Costs for Small Tanks
-------
~f C<»«Ni«CfTV QMOOCAI 1
Fig. B-4. Installed Capital Costs for Fixed-Roof Tank Refrigerated Vent Condensers
-------
STOKt T* Slit
I I
A. lOiv^^jl.. . £38 bbl... 14 i 4 J( &
'3 . iDM -jal. . *t 7 4» bbl 14ii^l x 16 - .
11 4 bbl . .
-to =J&£bbl..
L". I ' j M I net bbl . _
P. Iff. M j j| . . l\ |f."/ bbL .
¦ aoE^bbl
II. 11 1 f.'. . il 17357 bbl
L -ucoM^jjI .. Cwiiaibbl
Retrofit
Cap.
Subtotal Lap." 16 M
Alloiuonu 30ll " 3 -
Cap>tai ° £. I "
1
• nM
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* 31 M
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; 4PCi a • *"<> »
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(mA!NT= 5^) + (cap. BECOVr.K t- |4.1^)t(/iAl5C.
Capital Couts • > fcj.l'. * Caht«i. lit Olff
Retrofit Int Fu>-Fix.Rp.
t.ONA
s.e m
2 .fc AA
3.1 **
m
. I AA
£>.7 NA
<0.4 M
M
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STOW16E IK. CAPITAL i
¦; 1C 1
-------
B-0YDROSCIENCE
SUBJECT
^TOHAftg
^ Handling
PppRISgRATgO CaMr>PM3)MS
JOB NO.
SHEET ,FILE
BY
DATE
3IQI
' OF i
J . P . F.
AAAV 13 ^-73
:
: : i 1 l : ' 1 j
i
i
53 ^ ¦ : —J-/I ; i ;
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i i i
: i i 1 . 1 .1
i
i
; : 1 ! i L • 1 i
i
10 U 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
-------
Tank *Sixs
IO* Gal
•4©
ns
"160
CASE- I "
lao* e , O.s |VRp 3.1PVP tPSIA")
k2i.7l.Tomp, lOF.Temp t* C )
13.4 Sjtuntion.
O.I I Ton Refrigerator
fe.o Ft® Condenser
igpm, e HP. PoiT.p
-»P
• 13M'
o.loTon Refrigerator
iittO Ft* Condon a<3r
I SPM , 8 MP Pump
Cap • loeM
t.i Ton |?ef rigarj-tor
I lao Ft-' Candcnaer
I <5PM , Q HP Pomp
Cap.» IIOM*
CASE. ~ 2 -
jafe.T. t, l.s |VP,0.£FVP (P3tA)l
126.7 IT«mp.,-9.fe FTomp.(\:)
ItO*. Saturation
O. 38 Ton Ro-fri^erator
"3"} Ft* Condenser
I &PM i B HP Pump
¦r*
65M
&
».9 Ton Ralrig^ratar
503 Ft* Condenser
16PM, k HP Pomp
Cap « I3e
7.1 Ton Relriqeralor
|6E>1 F-f Condenser
i spm. a HP .
C.j, • *
ItlO M
CASE -a -
IVP,0.5 FVP (pSIa)
\zb.T lT«mp.,-2B.lFTenip('cJ
1 SI V. Sihirdtion
1.6 Ton Refrigerator
ion Ft1 Condenser
» &PM . g HP Potnp
Cap * iOA M
a.E Ton R«4rigera+or
io63 Ft* Condenser
I 6PM ,a HP Pump
Cop« as^M
31.7 "Ton Rel riqerotor
335& Ft* Condenser
a fePM, 4" HP Pomp. ^
Cap s a-ibm
NOTES
I• y.E kTPV [ mifiLigi-.i) : HC i,; <
£ . Pi» n .p III I. i ^ .1 . >y ji . o >(• . i I :
Sjjccif IC c^r \ 11 >| ¦ I, £ L irwi 11,
inter mil. (-* i »11 •">< •
3. Iriw i < ~i| ,i w.l ¦ . (I '• r irt
E^cIl iol* I jll > i ..)i. i^-j•».
Itsted i.<.lit ii er.-iB .lm t It
piping , in £ol.< t ion , 4 intti
en»6 + illoui^n':o
£.225 TPY WC Emission*
Hrj^r Op« rating
I.5»S rPV HC Recovered
4.fiLb/Hr "
a.iOg "TPY. HC ferniasionb
236 Hr/Vr Op«ratir»«j
3.94.a TPY HC Recpvsred
26.9 LbjHr " "
19 368 Tpy HC Emissions
B 63 Hr /Yr Operating
II.981 TPY HC Recovered
32.S Lb /Hr ' H
5.SB4TPV HC Emissions
SOI Hr/Yr Operating
4.-J69TPY HC Recovered
IS.S V-fc/Hr -
16.023 TPY HC tmi&signt
2SB Hr/Yr Operating
13.832 TPY Recovered
9fe.
-------
B-10droSCIENCE
SUBJECT
"Tank Pe-fn^erA-tor ^Vjg-Kam«
i J+-i1i-H_a ^ R?su*=>r Usa
no! >Ji sheet Tile
JOB NO.
9)Ol
OF
BY
U.R.P.
DATE
5-1 I-7S
iCeaE lL
|4qm1 Gal
Pnrnpft»-Ugr
JAI I RsiQYgar-/
! i !
R,g£. iPatngr -
5^b^jt_4^a^ihJ_5 56-k^tiL
O.G1' x 0 J I Ton X !l>
'V-ird * ) n^i-rtjmwn+s a. LJ«C£*ji_&I60 >c50*»_on__
Ii i '~:VJ I I i ; i i ¦ fa \
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4: f Kwh_
4 3 a ! -v
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34
35
36:
If, (o ?7 V
d.J3J_
1234S67S9 10
_! • e. - (t soWl^o 3-Q Km.fcl
11 12 13 14 IS 16 17 18 19 20T 21 22 23 24 2S 26 27 28
29 3C
-------
B—11
^i4 = ST CA>Sg NO. I
/-O/»-
4o v\ G-siTk
Par-
l"75 M Gal Tk.
H3R.
733Gal Tk.*
VVMSTC 3. RATE. OP WDLG.
i
*
MID I3"7B INSTRLLEO
capitai rnfiT ««Bes=«r
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1 "7n orv-i
!
UTILITIES :
i
Pi'.ifip wv
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1 3.
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B-12
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srOl«9f.rsr-. \.
Vrv—vis\M(S SNra-rr£- ««CnvJAa.P
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B-13
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^vAmfrmM Sur.ST CA3g NO. 3
rOH.
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Far*
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MR.
7306^1 Tk.
VsWsTC a. RATE. OP HDLG.
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1 1
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PRELIMINARY CAPITAL
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B-18
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NAME OF FACILITY DESCRIPTION OUAMf.
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NAME OF F ACILITY 0 g SCR 1 P T 1 0 N CUAMT. 1
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