PB87-231254
Prevention Reference Manual: Chemical Specific
Volume 4. Control of Accidental Releases of
Ammonia (SCAQMD (South Coast Air Quality
Management District))
Radian Corp., Austin, TX
Prepared for
Environmental Protection Agency
Research Triangle Park, NC
Aug 87
Zj
U.S. Dspstnsart of Ccmmsrce
Tecfecal btfermafea
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PB87-2312S1*
EPA/600/8-87/034d
August 1987
PREVENTION REFERENCE MANUAL:
CHEMICAL SPECIFIC
VOLUME 4: CONTROL OF ACCIDENTAL
RELEASES OF AMMONIA (SCAQMD)
by
D.S. Davis
G.B. DeWolf
J.D. Quass
M. Stohs
Radian Corporation
Austin, Texas 78766
Contract No. 68-02-3889
Work Assignment 98
EPA Project Officer
T. Kelly Janes
Air and Energy Engineering Research Laboratory
Research Triangle Park., North Carolina 2771 1
AIR AND ENERGY ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
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TECHNICAL REPORT DATA
(Please read Instructions on ihe reitnc before completing)
1 REPORT NO 2
EPA/600/8-87/034d
3 RECIPIENT'S ACCeSSlOr»NO
PB87-23125U
4 TITLE 4N'J SUBTITLE
Prevention Reference Manual: Chemical Specific,
Volume 4: Control of Accidental Releases of
Ammonia (SCAQMD)
5 REPORT DATE
August 1987
6 PERFORMING ORGANISATION CODE
7 AUTHORISI ^
D. S. Davis, G. B. DeUolf, J.D. Quass, and M. Stohs
PERFORMING ORGANIZATION REPORT NO
DCN 87-203-024-98-23
9 PERFORMING OROANIZATION NAME AND ADDRESS
Radian Corporation
8501 Mo-Pac Boulevard
Austin, Texas 78766
10 PROGRAM ELEMENT NO
11. CONTRACT/GRANT NO
68-02-3889. Task 98
12 SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
TYPE OF REPOR" AND PERIOD COVE RED
Task Final; 8/86 - 2/87
14 SPONSORING AGENCY CODE
EPA/600/13
15 supplementary notes project officer is T. Kelly Janes, Mail Drop 62B, 919/
541-2852.
is. abstract Tiie manual summarizes technical information that will assist in identify-
ing and (therefore) controlling ammoria-associated release hazards specific to the
South Coast Air Quality Management District (SCAQMD), which has considered
strategies for reducing the risk of a major accidental air release of toxic chemi-
cals. The strategy includes monitoring the storage, handling, and use of certain
chemicals and providing guidance to industry and communities. Ammonia gas has
an immediately dangerous to life and health (IDLH) concentration of 500 ppm, which
makes it an acute toxic hazard. To reduce the risk associated with an accidental
release of ammonia, some of the potential causes of accidental releases that apply
to processes using ammonia in the SCAQMD must be identified. Examples of such
potential causes are identified, as are measures that may be taken to reduce the
accidental release risk. These measures include recommendations on: plant design
practices; prevention, protection, and mitigation technolgies; and operation and
maintenance practices. Conceptual costs of possible prevention, protection, and
mitigation measures are estimated.
t7 KEY WORDS AND DOCUME1>iT ANALYSIS
1 descriptors
b IDENTIFIEHS/OPEN ended terms
c cosati Field/Gioup
Pollution Design
Ammonia Maintenance
Emission
Accidents
Toxicity
Storage
Pollution Control
Stationary Sources
Accidental Releases
13 B
07 B
14G
13 L
06T
15E
13 DISTRIBUTION STATEMENT
Release to Public
19 SECURITY CLASS (Thu Report)
Unclassified
21 NO OF PAGES
12?
20 SECURITY CLASS fThnpaget
Unclassified
71 PRICE
CPA Form 2220 1 (9-79)
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
11
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ABSTRACT
The South Coast Air Quality Management District (SCAQMD) of southern
California has developed a strategy for reducing the risk of a major acci-
dental air release of toxic chemicals. The strategy includes monitoring the
storage, handling, and use of certain chemicals and providing guidance to
industry and communities• This manual summarizes technical information that
will assist in identifying and therefore controlling release hazards specific
to the SCAQMD associated with ammonia.
Ammonia gas has an IDLH (Immediately Dangerous to Life and Health) con-
centration of 500 ppm. which makes it an acute toxic hazard. To reduce the
risk associated with an accidental release of ammonia, some of the potential
causes of accidental releases that apply to processes using ammonia in the
SCAQMD must be identified. Examples of such potential causes are identified,
as are specific measures that may be taken to reduce the accidentaj release
risk. These measures include recommendations on plant design practices, pre-
vention, protection and mitigation technologies, and operation and maintenance
practicer. Conceptual cost estimates of possible prevention, protection, and
mitigation measures are provided.
11 ^
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ACKNOWLEDGEMENTS
This manual was prepared under the overall guidance and direction of T.
K'ilLy Janes. Project Officer, with Che active participation of Robert
F. Hangebrauck, William J. Rhodes, and Jane M. Crum, all of U.S. EPA. In
addition, other EPA personnel served as reviewers. Sponsorship and technical
support was alco provided by Robert Antonopolis of the South Coast Air Quality
Management District of Southern California, and Michael Stenberg of the U.S.
EPA, ^rgion 9. Radian Corporation principal contributors involved in
preparing the nanual were Graham E. Harris (Program Manager), Glenn B. DeWolf
(Project Director), Daniel S. Davis, Nancy S. Gates, Jeffrey D, Quass, Miriam
Stohs, and Sharon L. Wevill. Contributions were also provided by other staff
members. Secretarial support was provided by Roberta J. Brouwer and others.
Special thanks are given to the many other people, both in government and
industry, who served on the Technical Advisory Group and as peer reviewers.
IV
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TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS
FIGURES . . . .
1 INTRODUCTION !
1.1 Background j
1.2 Purpose of This Manual 1
1.3 Uses ot Anhydrous Ammonia 2
1.4 Organization of the Manual 3
2 CHEMICAL CHARACTERISTICS 4
2.1 Physical Properties 4
2.2 Chemical Properties and Reactivity 7
2.3 Toxicological and Health Effects 8
3 FACILITY DESCRIPTIONS AMD PROCESS HAZARDS n
3.1 Processing 1 j
3.1.1 Recovery of Ammonia from Waste Water Treatment 11
3.1.2 The Use of Ammonia in the Production of Resins 14
3.1.3 The Use of Ammonia as a Refrigerant 16
3.1.4 Neutralization of Aciiic Waste Streams with
Ammonia jg
3.1.5 The Preparation of Ammonium Thiosulfate ... 20
3.1.6 The Reduction of NO Emissions with Ammonia . 22
3.2 Repackaging ? 24
3.3 Storage and Transfer 26
3.3.1 Storage 26
3.3.2 Transfer from Tank Cars and Trucks 28
3.3.3 Transfer from Storage Vessels 30
3.3.4 Transporting Axmonia Storage Containers ... 3)
3.4 Potential Causes of Releases ji
3.4.1 Process Causes 32
3.4.2 Equipment Causes 32
3.4.3 Operational Causes 34
4 HAZARDS PREVENTION AND CONTROL 35
4.1 General Considerations 35
4.2 Process. Design 35
4.3 Physical Plant Design 36
4.3.1 Equipment 38
4.3.2 Plant Siting and Layout 53
4.3.3 Transfer and Transport Facilities sf
4.4 Protection Technologies 55
4.4.1 Enclosures 55
4. \.2 Scrubbers
4.4.3 Flares 53
Section
ABSTRACT
V
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Section
TABLr: OF CONTENTS (Continued)
4.5
4.6
4.7
4.8
Mitigation Technologies
4.5.1 Secondary Containment Systems
4.5.2 Flotation Devices and Foams
4.5.3 Mitigation Techniques for Ammonia Vapor . ,
Operation and Maintenance Practices
Control Effectiveness
Illustrative Cost Estimates For Controls
4.8.1 Prevention and Protection Measures
4.8.2 Levels of Control
4.8.3 Cost Summaries
4.8.4 Equipment Specifications and Detailed Costs
4.8.5 Methodology
REFERENCES
APPENDIX A - GLOSSARY
APPENDIX B - METRIC (SI) CONVERSION FACTORS
FIGURES
NiEkH Page
3-1 Conceptual diagram of the "WWT" waste water treatment process . 13
3-2 Conceptual diagram of typical acrylomtrile process 15
3-3 Basic vapor compression refrigeration cycle 17
3-4 Conceptual diagram of typical ammonium thiosulfate process . . 21
3-5 Schematic of selective catalytic reduction (SCR) process ... 23
VI
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TABLES
Number
Page
2-1 Physical Properties of Anhydrous Aamonit; 5
2-2 Exposure Limits For Anhydrous Ammonia 9
2-3 Predicted Human Health Effects of Exposure to Various
Concentrations of Anhydrous Ammonia ...
A 2 Maximum Safe Volume of Liquid Ammonia in Nonrefrigerated
Storage Containers at Various Temperatures
4-4 Examples of Major Prevention and Protection Measures for Ammonia
Releases
10
4-1 Some Process Design Considerations for Processing Involving
Anhydrous Ammonia 37
44
4-3 Important Considerations for Using Flares to Prevent Accidental
Chemical Releases
72
A-5 Estimated Typical Costs of Major Prevention and Protection
Measures for Ammonia Releases 73
4-6 Summary Cost Estimates of Potential Levels of Controls for
Ammonia Storage Tank and Stripper 76
4-7 Example of Levels of Control for Ammonia Storage Tank 77
Example of Levels of Control for Ammonia Stripper 79
A—9 Estimated Typical Capital and Annual Costs Associated With
Baseline Ammonia Storage System 81
4-10 Estimated Typical Capital qnd Annual Costs Associated With
Level 1 Ammonia Storage System 82
4-11 Estimated Typical Capital and Annual Costs Associated With
Level 2 Ammonia Storage System 84
4-12 Estimated Typical Capital and Anr.ual Costs Associated With
Baseline Waste Viater Treatment Ammonia Stripper 86
4-13 Estimated Typical Capital arid Annual Costs Associated With Level
1 Waste Water Treatment Ammonia Stripper 87
4-14 Estimated Typical Capital and Annual Costs Associated With
Level 2 Waste Water Treatment Ammonia Stripper 88
vi 1
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TABLES (Continued)
Section Page
4-15 Equipment Specifications Associated With Ammonia Storage
S/srem 89
4-16 Material and Labor Costs Associated With Baseline Ammonia
Storage System 91
4-17 Material and Labor Costs Associated With Level 1 Ammonia Storage
System 92
4-18 Material and Labor Costs Associated With Level 2 Ammonia Storage
System 93
4-19 Equipment Specifications Associated With Waste Water Treatment
Ammonia Stripping Process 94
4-20 Material and Labor Costs Associated With Baseline Waste Water
Treatment Ammonia Stripper 95
4-21 Material and Labor Costs Associated With Level 1 Waste Water
Treatment Ammonia Stripper 96
4-22 Material and Labor Costs Associated With Level 2 Waste Water
Treatment Ammonia Strippei . 98
4-23 Format For Total Fixed Capital Cost 101
4-24 Format For Total Annual Cost 103
4-25 Format For Installation Costs 108
vin
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SECTION 1
INTRODUCTION
1.1 BACKGROUND
Recognizing the risk associated with accidental releases of air toxics in
southern California, the South Coast Air Quality Management District (SCAQMD)
conducted a study in 1985 to determine the presence, quantities, and uses of
dangerous chemicals in the SCAQMD, which comprises Los Angeles, Orange, San
Bernadino, and Riverside Counties. This study resulted in a report entitled
"South Coast Air Basin Accidental Toxic Air Emissions Study," which outlined
an overall strategy for reducing .he potential for a major toxic chemical
release incident.
The Gtrategy includes: monitoring industry activities that require the
storage, handling, and use of certain chemicals; using the best technical
information available; guiding industry and conmunities in minimizing the
potential for accidental releases and the consequences of any releases that
might occur.
Historically, there do not appear to have been any significant releases
of ammonia in the SCAQMD. Major releases of ammonia have occurred elsewhere
in the past fifteen years, however, involving numerous injuries and a signifi-
cant number of fatalities. Primary sources of these releases include pressur-
ized pipeline ruptures, failed storage tanks, and road tanker accidents.
1.2 PURPOSE OF THIS MANUAL
This manual compiles technical information on ammonia that emphasizes the
prevention of accidental releases of this chemical. Thf manual summarizes
issues relating to release prevention associated with the storage and handling
1
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of ammonia and with process operations involving anhydrous ammonia as it is
used an the SCAQMD. (Note: Throughout this manual, "ammonia" refers only to
anhydrous ammonia and not to aoueous or "aqua" ammonia.)
This manual is not intended to be a specification manual; it often refers
the reader to technical manuals and other sources for more information on the
topics discussed. Other sources incluae manufacturers and distributors of
ammonia and technical literature on design, operation, and loss prevention in
facilities that handle toxic chemicals.
1.3 USES OF ANHYDROUS AMMONIA
Anhydrous ammonia (NH^) is a significant commodity chemical, produced by
the reaction of hydrogen and nitrogen over a catalyst. The dominant use of
this chenical is in the fertilizer industry, which accounts for nearly 80Z of
all ammonie produced (1). The primary industrial uses of ammonia are ac a raw
material in the manufacture of nitric acid, as a reactant with nitric acid in
the production of explosives, and in the fibers and plastics industry in the
production of a number of commercially important synthetic materials. Ammonia
has other uses in a wide variety of industries, including neutralization
(especially the treatment of acidic wastes), extractior processes, refrigera-
tion, and flue gas scrubbing.
Numerous references in the technical literature offer information on the
nanufacture and uses of anhydrous ammonia. In the SCAQMD* anhydrous ammonia
does not seem to be nam'iactured by conventional processes for commercial
sale. However, it is produced in one specialty process developed for the
treatment of contaminated water in a petroleum refinery. Limited survey data
indicate that anhydrous ammonia is used or produced in the following processes
in the SCAQKD (2):
• A patented process actually called the "waste water
treatment" or "WWT" process;
2
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Manufacture of resins;
• Refrigeration;
• Neutralization of acidic waste streams;
• Preparation of ammonium thiosulfate;
• Reduction of NO^ emissions; and
• Repackaging.
There nay be other uses for anhydrous ammonia that were not identified in the
available survey data.
1.4 ORGANIZATION OF THE MANUAL
The five sections of this manual discuss the relevant issues associated
with the prevention of an accidental release of anhydrous ammonia to the
armosphere. Section 2 discusses the physical, chemical, and toxicological
properties of anaonia. Section 3 describes the types of facilities that use
ammonia in the SCAQMD. and process hazards arsociated with these facilities.
Hazard prevention and control are discussed -.n Section 4, ac are the costs of
example storage and process facilities that reflect different levels of
control. Section 5 contains references. Appendix A io a glossary of key
technical teras that nig'-jt not be familiar to all users of the manial, and
Appendix B presents selected conversion factors between metric (SI) and
English aeasurement units.
3
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SECTION 2
CHEMICAL CHARACTERISTICS
This section describes the physical, chemical and toxicological proper-
ties of anhydrous ammonia ac they relate to accidental release hazards.
2.1 PHYSICAL PROPERTIES
At atmospheric temperatures and pressures, anhydrous ammonia is a pur-
gent, colorless gas that may easily be compressed or cooled to a colorless
liquid. Table 2-1 shows the more important physical and chemical properties
of ammonia.
Pure liquid ammonia is lighter than water, and pure gaseous ammonia is
lighter thar air. A cloud of pure ammonia gas will be buoyant and rise into
the atmosphere; however, depending on the pressure and temperature, air-ammo-
nia mixtures denser than air may also be formed. This can occur when
evaporating ammonia cools itself and the surrounding air. For example, air
that is adiabatically saturated ' ith ammonia (6.1 wt%) has a density 1.35
times that of air at ambient conditions (3). A saturated air-ammonia mixture,
therefore, may remain close to the ground and not disperse very readily.
Water vapor may also condense out of an air-ammonia mixture from the cooling
effect of evaporating ammonia, causing fog. Because of the higher specific
gravity of the cooled air. this fog could spread laterally over the ground
(3). Regardless of the temperature and pressure, all air-ammonia mixtures
containing more than 45 wtS ammonia are lighter than air (3).
Since liquid anhydrous ammonia has a large coefficient of expansion, an
overpressunzation hazard exists if storage vessels have insufficient expan-
sion space or if pipelines full of liquid amironia are 6ealed on both ends. In
these situations, thermal expansion of the liquid with an increase in tempera-
ture can result in containment failure from the hydrostatic pressure exerted
by the liquid.
4
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TABLE 2-1. PHYSICAL PROPERTIES OF ANHYDROUS AMMONIA
Reference
CAS Registry Number
Chemical Formula
Molecular Weight
Normal Boiling Point
Melting Point
Liquid Specific Gravity (1^0=1)
Vapor Specific Gravity (air=l)
Vapor Pressure
Vapor Pressure Equation
07664-41-7
nh3
17.03
-28.17 °F ® 14.7 psia
-107.93 °F
0.6815 @ -27.7 °F
0.5970 @ 32 °F
128.8 psia & 70 °F
1
1
1
1
1
4
log
where:
Pv = A -
T+C
Liquid Viscosity
Solubility in Water at
1 ato, wt. 2
Specific Heat at Constant
Volune (vapor)
Pv = vapor pressure, mm Hg
T = teaperature, °C
A = 7.36050, a constant
B = 926.132, a constant
C = 240.17, a constant
0.255 cp 9 -33.5 °C
32 °F 42.8
50 °F 33.1
68 °F 23.4
86 °F 14.1
0.38 Btu/(lb-°F) 9 32 °F
(Continued)
5
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Specific Heat at Constant
Pressure (vapor)
Specific Heat at Constant
Pressure (liquid)
Latent Heot of Vaporization
Liquid Surface Tension
Average coefficient of
Thermal Expansion at
Constant Volume, 0-60°F
TABLE 2-1 (Continued)
Reference
0.5 Btu/(lb-°F) @ 32 °F 6
1.10 Btu/(lb-°F) ® 32 °F 6
588.2 Btu/lb @ -27.7 °F 1
23.4 dynes/cn Q 52 °F 7
0.00377/°F 6
Additional properties useful in dete
pioperty correlations:
Criticjl Teniperdture
Criticjl Pressure
Critical Density
rininy other properties fro:i physical
270.32 °F 1
1639.1 pcia 1
14.66 lb/ft3 6
6
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The flammability of ammonia in air at atmospheric pressure ranges from
16% to 252 ammonia by volume, while in oxygen the range is from 15% to 79% by
volume (A). Increasing the temperature and pressure of the ammonia increases
the flammability range. Although -the minimum ignition temperature for a
mixture within the flammability limits is relatively high at 1562°F (8),
ammonia can burn or explode under some conditions, such as a large and intense
source of ignition combined with a high concentration of ammonia gas (9). If
oil is present, or xf ammonia is mixed with other flammable substances, the
fire hazard will also increass. It has been reported that che presence of
iron appreciably decreases the ignition temperature (9).
Water readily absorbs ammonia to make ammonia liquor (ammonium hydroxide
or aqua ammonia). The dissolution of ammonia in water is accompanied by
relatively large heats of solution. Approximately 933 Btu of heat is evolved
when 2.2 lb of ammoria gas is dissolved in water (5). The solubility of
ammonia in water at various temperatures is given in Table 2-1.
2.2 CHEMICAL PROPERTIES A>® REACTIVITY
Pure ammonia is a very stable compound under normal conditions; even
slight dissociation to hydrogen and nitrogen does not occur at atmospheric
pressure until temperatures of 840-930°F are reached (8). The products of
complete combustion of ammonia (nitrogen and water) are neither toxic nor
hazardous.
Ammonia is a highly reactive chemical, forming ammoniu^ salts with
inorganic and organic acids. Three major fertilizers are ammonium nitrate,
ammonium sulfate, and amnoniun phosphate. Ammonia reacts with chlorine m
dilute solution to give chloramines, an important reaction in water purifica-
tion (5). Another important industrial reaction is the preparation of
ammonium carbamate from anconia and carbon dioxide, which decomposes tc. £ive
urea and water (5). The alkaline characteristics of ammonia make it useful
for neutralizing acidic waste streams in a number of industries.
7
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It has been reported that gold, silver, and mercury arc capable of
reacting with ammonia to form explosive compounds CD. Other explosive
materials that can be formed include metal hydrazides, which are produced from
the reaction of alkali metals and liquid ammonia. Acetylides, which are
highly explosive in the dry state, are formed in the presence of ammonia
solutions of copper, mercury or silver salts (1).
Most common metals do not react witu dry ammonia. However, when mixed
with small amounts water or water vapor, ammonia will vigorously attack
copper, silver, zinc, and many alloys, especially those containing copper
(10).
2.3 TOXICOLOGICAL AND HEALTH EFFECTS
Depending on the concentration, the effects of exposure to ammonia gas
rangf from mild irritation to severe corrosion of sensitive membranes of the
eyes, nose, throat, and lungs (5). Because of the high solubility of airjaonia
in water, it is particularly irritating to moist skin surfaces. A concentra-
tion of 500 ppm has been designated as the IDLH concentration {immediately
Dangerous to Life and Health), which is based on a 30-cinute exposure. Table
2-2 summarizes some of the relevant exposure limits for aQcoma gas (11).
Table 2-3 summarizes the predicted human health effects from increasing
concentrations of ammonia gas. Because the pungent odor of ammonia is immedi-
ately recognizable at low concentrations, it is unlikely that any individual
would become overexposed unknowingly. Ammonia in not a cumulative metabolic
poison: ammonium ions are actually important constituents of living systems.
However, inhalation of high levels of ammonia gas may have fatal consequences
becouse of the spasm, inflammation and edema of fhe larynx and bronchi,
chemical pnejmonitis and pulmonary edema (12.). Exposure of the eyes to high
concentrations may result in ulceration of the conjunctiva and correa and
destruction of all ocular tissues (12).
8
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Contact of the skin with liquid ammonia may cause freezing of the tissue,
since liquid ammonia vaporizes rapidly when released to the atmosphere and
will absorb heat from any substance it contacts. If the skin is moist, it may
also cause severe burns from the caustic action of the ammonium hydroxiae
produced.
TABLE 2-2. EXPOSURE LIMITS FOR ANHYDROUS AMMONIA
Exposure Concentration
Limit (ppm) Description Reference
IDLH
500
The concentration defined as posing an
immediate danger to life and health (i.e.,
causes irreversible toxic effects for a 30-
minute exposure).
11
PEL
50
A tine-weighted 8-hour exposure to this
concentration as set by the Occupational
Safety and Health Administration (OSHA),
should result in no adverse effects for
the average worker.
U
LO
30,000
This concentration is the lowest published
lethal concentration for a human over a 5-
ninute exposure.
11
TC, „
LO
20
This concentration is the lowest published
concentration causing toxic effects
(irritation).
11
9
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TABLE 2-3. PREDICTED HUMAN HEALTH EFFECTS OF EXPOSURE TO VARIOUS
CONCENTRATIONS OF ANHYDROUS AMMONIA
EE®
5
Effect
Least perceptible odor
20-50
Readily detectable odor
AO
A few individuals may suffer slight eye irritation
100
Noticeable irritation of eyes and nasal passages after a
few minutes exposure
150-200 General discomfort and eye tearing: no lasting effect fron
short exposure
400
Severe irritation of the throat, nasal passages, find upper
respiratory tract
700
Severe eye irritation; no permanent effect if the exposure
is limited to less than 1/2 hour
1700
Serious coughing, bronchial spasms, burning and blistering
of the skin; les6 than 1/2 hour of exposure may be fatal
5000-10000 Serious edema, strangulation, asphyxia, rapidly fatal
10000
Immediately fatal
Source: Adapted from referencef 1 ar.d 5
10
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SECTION 3
FACILITY DESCRIPTIONS AND PROCESS HAZARDS
This section briefly describes the uses of anhydrous ammonia in the
SCAQMD and highlights major process hazards related to accidental releases.
The discussion addresses processing, repackaging, and storage and transfer as
separate topics. Preventive measures associated with these hazards are
discussed in Section 4,
3.1 PROCESSING
Limited survey data show that anhydrous ammonia is used for a variety of
purposes in the SCAQMD. In the petroleum industry it may be used au a sol-
vent, a refrigerant, a corrosion inhibitor, and as a neutralizer ol the acidic
constituents of oil. In at least one refinery it is recovered as a salable
product Iron sour vater. In the paint and plastic industries, arimonia is a
raw material in the production of various resino used in the manufacture of
many important synthetic materials. Ammonia has many applications in the
SCAQMD as a refrigerant and as a neutralizing agent of acidic waste streams,
as found in lead-acid battery manufacturing installations. Ammonia may also
be uspd ac a reducing Agent in the removal of NO^ compounds from flue gas, in
the production of ammonium thiosulfate, and in tbe preparation of ammonium
hydroxide, which is itself a raw material in the manufacture of many speciali-
ty chemicals, including nitrogen-containing surface active agents.
3.1.1 Recovery of Ammonia from Waste Water Treatment (13,14)
Waste waters from several petroleum refining piocecses cont^ii. apprecia-
ble quantities of ammonia: typical concentrations reported in 11,»? literature
range from 3% to 10% by weight. The "VWT" Proce66, a patented process for
treating these refinery wastes, recovers high-purity ammonia and hydrogen
11
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sulfide and clean water suitable for reuse or for discbarge. The larger WWT
units produce more than 50 tons of anhydrous ammonia a day (13).
A typical WWT process arrangement is shown in Figure 3-1. The feed
consists of sour water from a degassing unit in which dissolved hydrogen,
methane, and other light hydrocarbons are removed. The feed is pumped through
a feed heater into a reboiler stripper column from which the hydrogen sulfide
is stripped overhead while the- ammonia and water are removed as the bottoms
product. The overhead product is high purity hydrogen sulfide that contains
negligible ammonia. The bottoms product goes directly to a second reboiler
stripper column. The bottoms from this column is "clean" water (typically <50
ppm animotira and <5 ppm l^S) suitable for many in-plant reuse needs, while the
overhead product is ammonia with small amounts of hydrogen sulfide and water.
These constituents are removed in the ammonia purificatior section, which
consists of one or more scrubbing stages, depending on the desired purity.
The ammonia product is then compressed and condensed to salable anhydrcus
liquid ammonia. Alternatively, the ammonia product can be produced as
high-purity aqueous ammonia solution, eliminating the reed for an ammonia
coirpressor. Because the ammonia is handled in solution, the production of
aqueous ammonia may be less hazardous than the production of anhydrous ammo-
nia. If there is no immediate use for the ammonia recovered from the second
stripper, it can be incinerated in a process furnace or special incinerator.
The hazards that may lead to a large release of ammonia liquid or gas
involve the latter portion of the process, where ammonia is present in
relatively pure form. This section of the process begins with the overhead
product from the second stripper and ends with the final ammonia product
storage. Included are the ammonia stripper and condenser; one or more H^S
scrubbers; pioduct compressors, condensers and storage facilities; and
associated piping and instrumentation. Process upsets specific to the WWT
Process that may lead to a large release of anhydrous ammonia include:
12
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Hydrogen
Sulfide
By Product
De aerated
Condonsale
Recycle }¦
Anhydrous
Arr.monla to
By Product
Storage
Recycle
to food
Partial
Condenser
Amnionic
Purification
Section
Ammonia
Slripper
Hoat
Eichnngot
Stnppod
Waler
Figure 3-1. Conceptual diagram of "WWT" waste water treatment process.
-------
• Overheating of the anununia stripper from excess heat to
the ammonia stripper reboiler or a sudden decrease in
ammonia feed; and
• Overheating of the ammonia condensers from a loss of
cooling water.
These process upsets could result in equipment failure from overpressuriza-
tion The other high hazard area in the VUT process is the ammonia compressor
after the ammonia purification section. Additional hazards associated with
the storage and transfer of anhydrous ammonia are discussed in Section 3.3;
general causes of equipment failure are discussed in Section 3.4.
3.1.? The Use of Ammonia in the Production of ReGins (15,16,17)
In the SCAQMD. anhydrous ammonia is used indirectly as a raw material in
the production of a variety of resins, which have numerous uses in the
textile, coating, and plastics industries. Large quantities of ammonia,
generally in the form of ammonia derivatives, are consumed in their
manufacture. The greatest amounts go to the production of amino, acrylic, and
polyamide (nylon) resins, polyurethanes, and linear polyesters (15).
Anhydrous ammonia is used directly as a reactant to produce acrylo-
nitrile, which is a raw material for acrylic resins. The process, shown
schematically in Figure 3-2, involves rearting a gaseous mixture of propylene,
ammonia, and air in & ratio of 1.4:1.&:10 in the presence of a catalyst. The
three reactants are fed to a fluidized bed reactor operating at a temperature
of 750-950°F and 5-30 psig pressure. The leactor effluent is scrubbed in a
countercurrent absorber, and the organic materials are recovered from the
absorber water by distillation. Hydrogen cyanide, water, light ends, and high
boiling impuritiec are removed from the crude acrylonitnle by fractionation
to pioducc specification acrylonitrile product. Because the conversion
obtained on a once-through basis is high, no separation or recycling cf
unreacted raw materials is necessary. However, in another commercial process
14
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Crude Product
Water Otf Gas Water HCN Acrytonilrile
Air
Ammonia
(Recycle)
Heavy
Impurities
Boiler High
Feed Pressure
Wator Steam
Rea.~tor
Absorber
Product
Column
Acrylomtrite
Recovery
Column
Figure 3-2. Conceptual diagram of typical acrylonitrile process.
-------
that does not have a high conversion, the unreacted ammonia is absorbed by a
countercurrent flow of aqueoud sulfuric acid to produce ammonium sulfate
solution (16).
Hazards that may lead to a large release of anhydrous ammonia in tna
acrylonitrile production process involve the portions of the process where
ammonia is present in relatively pure form. Because no ammonia recovery is
required, this only includes tne section between the storage (feed) tank and
the catalytic reactor. This section contains the storage tank, the atiDonia
vaporizer, feed preheater, piping to the reactor, a flow controller,' and
various other instrumentation. Possible causes of a hazardous '-elease from
any of thi-e components are discussed in Sections 3.3 and 3.4. Process
upsets, e.g. overheating frOD a loss of cooling water, are unlikely to lead to
a large release of ammonia unless coupled with another event such as the loss
of ammonia feed control. In the event of s reactor failure, this situation
would allow excess ammonia to vent to the atmosphere.
3.1.3 The Use of Ammonia as a Refrigerant (6,18)
One of the predominant uses of ammonia in the SCAQMD is as a refrigerant.
Because of its toxic properties, ammonia is primarily used for lndt-strial
applications where other systems are not technically or economically feasible.
There are two basic types of refrigerati"" systems: absorption and vapor
compression. While some absorption systems employ ammonia-water solutions ac
the refrigerant, pure, anhydrous ammonia is only uced in vapor compression
systemu. These systems vary from simple single-stage refrigeration cycles to
conplex multistage compound or cascade cycles, depending on the application.
Figure 3-3 shows the basic vapor compression refrigeration cycle for a
single-stage system. The four basic components are the compressor, condenser,
expansion valve, and evaporator. High pressure liquid ammonia flows from the
16
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Cooling
Medium
Evaporator
Compressor
Product
Cooled
Figure 3-3. Bnnic v.«i>or codjji ccoion rcf r i go rn t ion cycle.
-------
condenser receiver through an expansion valve to :he evaporator. Here, heat
is absorbed from the fluid to be cooled, and the ammonia boils. The gaseous
ammonia is then compressed to a temperature and pressure at which the
superheated vapor can be condensed by the cooling media available for use in
the condenser. The refrigeration cycle thus involves two pressures, high and
low, to enable a continuous process that produces the desired cooling effect.
Possible causes of a hazardous release from an ammonia refrigeration
systesi include the following:
• Overpressurization, and
• Equipment failure.
Failure of the refrigeration compressor stops circulation of the refrig-
erant through the evaporator. If the flow of the fluid being cooled is not
stopped, the pressure in the evaporator will rapidly rise and cause the relief
valves to open. If these valves are not venttd to a closed system. ammonia
will be released to the atmosphere. A tuoe failure in a refrigerant heat
exchanger would also cause a repid pressure rise in the refrigeration system
A
and opening of the relief valves.
Catastrophic equipment failure could result in a large release of ammonia
liquid and/or gas. Because refrigeration systems operate at greater than
atmospheric pressure, ammonia will quickly escape from the source of a re-
lease.
*
A similar situation can occur if cooling water to the condenser is lost.
Relief valves on the condenser would open, it the cooling is not restored in
time to prevent a significant rise in pressure.
IB
-------
The primary cause of refrigeration equipment problems is lack of adequate
precautions taken during the design, construction and installation of the
system (18). The components of a refrigeration system that are especially
vulnerable to damage from 6tart-up procedures and process upsets include
machinery with moving part6 such as pumps and compressors. Abnormally high
protess temperatures nay occur either during startup or process upsets.
P:ovision oust be made for this possibility, for it can cause damaging thermal
stresses on refrigeration components and excessive boiling rateG in evapora-
tors, causing liquid to carry over and damage the compressor.
Tb«i system must be kept internally clean during installation because
ammonia is a powerful solvent, and dirt. scalc( sand, or moisture remaining in
the pipes, valves and fittings will be swept along with the ruction gas to the
compressor, where it is potentially harmful to the bearings, pistons, cylinder
walls, valves and lubricating oil. When a compressor is run for the first
time, moving parts are often scratched (18). Although damage is only minor in
the beginning, scratches may progresc until they seriously affect the opera-
tion of the compressor or render it inoperative (18).
3.1.4 Neutralization of Acidic Waste Streams with Acmonia (19)
Several companiss in the SCAQMD generate waste streams that are acidic in
nature. For excsple, the sulfuric acid used in lead-acid battery manufac-
turing processes results in waste streams w?th a pH of around 2 (19). Regard-
less of the source, acidic wastes must usually be neutralized before further
treatment or discharge, and. because of its alkaline properties, anhydrous
ammonia is often used as the ".eutrallzing agent for these wpstes.
The neutralization process itseLf is relatively simple. In most process-
es, anhydrous ammonia is vaporized through a solenoid valve as it leaves a
pressurized storage tank. The gaseous ammonia flows through carbon steel
piping to u neutralization drv.m, pit, or tank, where it is sparged ir.to the
waste solution. The ammonia may be piped directly into the bottoo of the tank
19
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or cent through a vertical feed pipe that ie immersed in the solution. The
quantity of ammonia fed is automatically controlled by either wastewater
flowrate or pH.
Hazards associated with the neutralizatiri process primarily involve the
ammonia storage system. The only other part of the process where ammonia is
present in nearly pure form is the feed system. However, if a failure i*- 'his
system raused too much or too little ammonia to be fed. it would pr^oably not
result in a large release of anhydrous ammonia. A slight cveipressurization
potential would exist if the neutralization tank weri a closed system without
a pressure relief device or if it had insufficient relief piping volume to
handle any excess gac not absorbed in solution. However, because ammonia is
so soluble in water, it would take a rather large quantity to saturate an
aqueous waste &tream.
For neutralization systems, suitable mateiialo of construction must be
used for the tank and for any ammonia piping that comes into contact with the
wa&te solution. Improper construction materials may lead to corrosion and
possible equipment failuie. The type of container used, as well as the
materials of construction, will depend on the characteristics of the waste. A
corrosion hazard also exists if precautions are not taken to prevent backflow
of the waste into the carbon steel ammonia piping.
3.1.5 The Preparation of Ammonium Thiosulfate (20,21)
Ammonium thiosulfate is used as a photographic fixing solution and in
some agricultural applications. Although this chemical is manufactured in
several different ways, the raw materials required for its preparation are the
same: ammonia, sulfur dioxide, water, and elemental sulfur.
Figure 3-4 is a block diagram of a typical ammonium thiosulfate process.
Ammonia, SC>2, and sulfur are fed to the reaction vessel with a recycle stream
containing ammoniua bisulfite, sulfur, and water. The fresh ammonia and S02
20
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Sulfur
Ammonia
Wash Solvent
SO.
Air
Ammonia
Condenser
Ammonia
Condenser
Air Separator
Scrubber
Sulfur
Burner
Recycle
Mixer
Reaction
Vessel
Sullur Waste
Figure 2-U. Conceptual diagram of typical ammonium thioculfate process.
-------
combine to form ammonium bisulfite, arid this reacts with excess ammonia and
sulfur to form primarily ammoniuD thiosulfate and lesser aaounts of amnoniun
sulfite and ammonium sulfate. The reaction products are not soluble and
precipitate out, settling in the bottom of the veGsel. From there they may be
removed continuously or by periodic scraping. Ammonia and water are removed
from the ammonium thiosulfate by drying; the vapors are condensed and recycled
back to the system if desired. Sulfur can be removed by washing with ammonia
or carbon bisulfide or be left in for fertilizer applications. Ammonia vspor&
from the vaporization of excess ammonia in the reaction vessel may be taken
overhead, condensed, and recycled to rhe reactor. Water and sulfur dioxide
are added to the effluent before it is recycled to the reactor. Ammonia may
also be recovered from the vapor leaving the Tecycie mixing tank. Figure 3-4
shows sulfur dioxide being prepared by combusting sulfur with oxygen, but in
practice this chemical can be supplied from any convenient source.
The process just described is only one of several possible oethods for
producing ammonium thiosulfate. However, the potential hazards arising from
the use of ammonia as a reactant will be general to most of the processes for
the manufacture of this chemical. Ammonia nay also be present in pure or
nearly pure form in overhead vapor recovery operations, which involve the
compression and condensation of ammonia. Potential causes of failure of these
components that may lead to a large release of anhydrous ammonia are not
unique to this process and aie discussed in Section 3,&.
3.1.6 The Reduction of UO Emissions with Ammonia (22)
c—
Ammonia is used in tne Selective Catalytic Reduction (SCR) process to
reduce nitrogen oxide compounds contained in flue gas. Figure 3-5 shows a
schematic of the SCR process, in which gaseous ammonia diluted with either air
or steam is injected through a grid system into the flue gas stream upstream
of the SCR catalyst. The ammonia/flue gas mixture then enters the catalyst
bed, where the ammonia reduces to in the presenre of oxygen.
22
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SCR
Catalyst
Fuel/Flue Gas
Waste
Heat
Boilof
Paniculate Removal.
FGD. and/or Slack
Fuel/Flue Gas
Ammonia
Figure 3-5. Schematic o£ selective catalytic reduction (SCR) process.
-------
The primary process hazards that may lead to the release of a significant
quantity of pure ammonia involve the ammonia storage and feed systems.
Hazards associated with the bulk storage of ammonia are discussed in Section
3.3. Potential hazards associated with the feed system are not unique to this
process and are discussed in Section 3.4. The only other possible hazard
involves a damaged or poisoned catalyst, in which case the unreacted ammonia
would presumably pass through the system to discharge. Potential poisons
include ammonium sulfates and bisulfates. which may be formed if the operating
temperature falls below the optimum range of 590°F to 750°F.
SCR systems generate essentially no liquid or solid wastes rhar may be
considered hazardous. Under normal operation, the ammonia fed to the catalyt-
ic converter is destroyed in the reduction process. The concentration of
residual ammonia is only 10—15 ppm, which does not exceed the federal stan-
dards for ammonia vapor. However, if nil excess amount of ammonia were inject-
ed into the flue gas, a breakthrough of emmoma into the equipment downstream
would result, which could lead to a greater concentration of residual ammonia
in th'; discharge gas.
3.2 REPACKAGING (23)
Anhydrous ammonia is repackaged in the SCAQMD for resale and further use.
Repackaging involves a number of procedures which vary, depending on whether
liquid ammonia is being transferred from tank cars into tank trucks, or from
tank cars, trucks, or bulk storage into cylinders or other portable contain-
ers .
Filling operations nay be carried out by transferring ammonia directly
from the tank car or truck to the receiving container. However, since
demurrage begins to accrue after a short period of time, most repackagers
first transfer the ammonia to bulk (pressurized) storage before filling the
smaller containers. Filling can be accomplished with a compressor or vapor
pump by reducing the pressure within the container being filled and at the
2b
-------
same time increasing the pressure witbin the storage tank being emptied.
Filling can also be accomplished by means of a liquid pump. Coopreosed air
lihould never be used to cause a flow of liquid ammonia, because oxygen contam-
ination in a storage vessel causes stress corrosion cracking in certain carbon
steels. During the filling operation the receiving vessels are mounted on
scales to determine when they have been filled with the correct amount of
ammonia. Some repackages reveigh the vessels on a second scale to verify
chat the measurements made with the first scale were accurate.
Potential hazards in repackaging operations include the following:
« Contamination, such as with oxygen (latent hazard);
• Overpressunzation of the storage vessel; and
• Overfilling of the receiving vessel.
Stress corrosion cracking of certain carbon steels is caused by oxygen
contamination, a hazard discussed in more detail in Section 3.3. Contamina-
tion with other materials could result in potentially violent reactions.
Accidental overpressure of the storage tank could result in a release of
ammonia from the pressure relief valve if it is not vented to a closed system.
Overfilling could cause a release from a rupture in the piping or the
receiving vessel from a pressure buildup. A latent hazard also exists in an
overfilled vessel that goes undetected and leaves the repackaging facility.
Equipment used in repackaging operations should be constructed from
materials compatible with ammonia. Suitable materials of construction for
ammonia service are discussed in Section 4. Other potential causes of a
release include leaks in the connecting piping as a result of corrosion or
loose joint-pipe connections, clogging of vapor or liquid pipes leading to
overpressure, and human error.
25
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3.D STORAGE AND TRANSFER
All industries that use oc han-'le ammonia in bulk quantities must have
appropriate facilities and procedures for its safe storage and transfer. This
section identifier potential hazards common to all installations associated
with the storage and transfer of anhydrous ammonia. Proper procedures and
safety precautions for the control of these hazards for release prevention are
discussed in Section 4.
3.3,1 Storage
Liquid anaonia is stored in either refrigerated vessels at atmospheric
pressure or in pressure vessels at ambient temperatures. The type of vessel
used at a particular installation generally depends on the relative coots of
the two systems. However, materials and fabrication constraints place an
upper limit on the size of pressure vessels, so that no more than 50.000
gallons of ammonia should be stored in an unrefrigerated tank (5).
Pressurized storage tanks are generally constructed of carbon s»teel
according to the American Society of Mechanical Engineers (ASHE) Code for
Unfired Pressure Vessels, Section VIII, Division X, and according to the
American National Standards Institute (ANSI) Standards for Piping and Fittings
(24,25,26,27). Refrigerated storage tlinks with a design pressure of less than
15 psig are constructed in accordance with the American Petroleum Institute
(API) Standard 620 (28). The maximum amount of ammonia that may be stored,
the "filling density", depends on the type of container and ranges from .56 to
-58 times the water weight capacity of the container at 60°F (8).
The predominant use of ammonia in the fertilizer industry has made
refrigerated storage economically attractive to producers because the fertil-
izer season is relatively short, and large single-train plants which produce
ammonia year-round require large storage terminals during the off season. The
quantities of aancnia involved make pressurized storage prohibitively
26
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expensive. In general, pressurized BtorBge containers are used in conjunction
with processes that require relatively small quantities of ammonia (les6 than
40,000 gallons stored). In the SCAQMD, ther* are no ammonia plants, and
therefore no large capacity refrigerated storage terminals. (The ammonia
produced by the largest WJT unit is less than one percent of the output of a
large ammonia plant.) In addition, survey date indicate that no facilities in
the SCAQMD that store anhydrous ammonia use refrigerated storage. For this
reason, only the hazards of pressurized storage systems used for liquid
anhydrous acmonia are discussed.
The primary hazard associated with the storage of liquid ammonia is
failure of a pressurized storage vessel or of its associated piping. The
failure may be a result of cracks or defects in the walls of the vessel at
normal operating conditions or could result from a buildup of hydrot-tatic
pressure greater than the design pressure. Possible causes of vessel failure
include:
• Corrosion;
• Overheating;
• Overfilling; and
• Failure of safety relief devices.
A predominant internal corrosion hazard of ammonia storage tanks is
stress corrosion cracking (SCO, which occurs in certain carbon steels and
which has been the subject of extenbive research over t -e last thirty years.
The effects of SCC are several hundred or more fine cracks invisible to the
naked eye which vary in depth from less than a millimeter to the full thick-
ness of the plate (35). It is generally agreed that the primary cause of SCC
is oxygen contamination; cracking may be induced m some vessels with an
oxygen concentration as low as 1 ppm (29). The cracks always occur in zones
27
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of high stress, uuually the weld deposit. Cracking susceptibility increases
with the strength of the steel and with temperature. (No SCC has been report-
ed in refrigerated storage vessels; the reason for this seems to be because
eny oxygen present is removed in the recompression cycle, and not because of
low temperature and pressure (29).) Furthermore, while the addition of 0.1 to
0.2 wtX of water has been found to inhibit cracking in the liquid phase,
cracking in the va;>or phase still may occur (30). If SCC is not detected
promptly, a serious corrosion hazard exists that may ultimately lead to
complete failure of the vessel. In addition to SCC, an external corrosion
hazard exists where storage vessels are in constant contact with dampness or
standing water.
An uninsulated storage vessel filled with ammonia at the maximum filling
density will become liquid full at a temperature of 130°F (8). Thu^-, an
overheating hazard exists if ammonia is stored in an area located near flamma-
ble or incompatible materials, especially if the area is not well ventilated
or heavily trafficked. Cylinders or other storage vessels exposed to direct
sunlight also pose an overheating hazard.
Storage vecselc may be overfilled because of a malfunctioning scale or
level-gaging device, or operator error. An overfilled pressurized ammonia
storage tank presents a hazard, because the temperature at which the vessel
will become liquid full is lowered, creating the possibility of a liquid-full
container with an otherwise insignificant increase in temperature. The
resulting hydrostatic pressure would cause the pressure relief device to vent
ammonia to the atmosphere; if the pressure relief device failed to activate, a
catastrophic release could result from vessel rupture.
3.3.2 Transfer from Tsnk Cars and Trucks
To reduce the risk of a hazardous cheuical release, appropriate proce-
dures must be followed when transferring ammonia from tank cars and trucks to
storage vessels. Tank cars are generally unloaded by mean? of a gas
28
-------
compressor or transfer unit that creates a pressure differential between the
storage vessel and the tank car. Tank cars may also be unloaded with a liquid
piunp. Examples of potential hazards associated with the unloading of tank
care and trucks include the following:
• The pressure in the tank car or truck attains the pressure
setting of its relief valve and ammonia vapor is vented to
the atmosphere;
• The pressure in the tank car is lowered so ouch that the
tank is subjected to an internal vacuum condition, possi-
bly caused by a subsequent reduction of ambient tempera-
ture;
• The vapor or liquid transfer line becomes clogged or the
conttol valve fails clossd, resulting in overpressure of
the storage vessel;
• Leakage resulting from pipe corrosion or untigntness of
joint-pipe connections;
• Incompatible contamination in the receiving vessel that
could lead to an uncontrolled reaction and overpressure or
corrosion of th«> receiving vessel;
• A malfunctioning level-indicating device on the '¦eceiving
vasoel results in an overflow of the receiving vessel; and
o Human error.
29
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3.3.3 Transfer from Storafce Vessels
Another important aspect of the transfer of Liquid or vapor ammonia is
the discharge of ammonia frcm a storage container for its designated use in
the plant, which is generally accomplished by means of the pressure differen-
tial between the container and the receiving vessel or process to which it is
flowing.
The practice of manifolding tc withdraw liquid amaon->q from two or more
cylinders simultaneously is hazardous, because under ce;t<*in temperature
conditions the liquid tan i/ov from one cylinder in*"o an^'her cylinder until
it is completely f;lled (1). If the valve of this completely filled cylinder
were subsequently closed, any rise in temperature wouiJ result in a build-up
of hydrostatic pressure that could rupture th* rylinder. because it is
possible that the evaporation of ammonia in a cylinder will cause the ammonia
to be refrigerated to the point where there is little or no flow of gBS,
cylinders are also manifolded together to increase total vapor withdrawal
rate. Gaseous transfer between cylinders at different tetperatures in such an
arrangement is likewise hazardous if there is subsequent rellquefaction and
isolation of the overfilled container.
Nitrogen or air padding should not be u6ed to promote the flow of ammonia
from cylinders or other storage vessels. Vi?zart's include dangerous high
pressures because of an increase in the ambient temperature, and oxygen
contamination that causes stress corrosion cracking. Furthermore, cylinders
should never be warmed with a flame to increase the discharge rates because of
possible pressure buiidjp sufficient to rupture the container. Other methods,
such as a wane water t .th, should be used with caution to prevent accidental
overpressure of the :y^inder.
Other porential hazards include.
30
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• Hazardous bockflov into the cylinder or into the upper
valve chasbcrs of tho feed storage vessel;
• Isolation of liquid oaaonia in piping between closed
valves that could lead to tho lino but sting froa a
build-u^ in hydrostatic pressure and a tenperature in-
crease; and
• Failure of piping connections froa corrosion, icproper
naterinls of construction, or work hardening, or fatigue.
3.3.4 Transporting Asaonia Storage Containers
Another aspect of storage nnd transfer is the unloading of containers of
aoaonia froa the delivery vehicle or sovmg tho# within the plant. In
general, potential hazards Associated with the transport of aosonia within a
closed vessel arise froa failure to safely follow proper transfer procedures.
Prevention of a hazaidous release lesultirg froa huoan error is diGcv.ssed in
Sect ion 4.5.
3.4 POTENTIAL CAUSES OF RELEASES
The potential for a hazardous release of liquid or gasecus anoonii exists
in any type of facility that handles this eaterial. The possible sources of
such a release are nuaerouo. Large-scale releoced any be caused by leaks or
ruptures of large storage vessels (including on-site tank cars) or by failure
c! process sachinery (e.g.. pumps or cocprescors) that maintain a large
throughput of aamonia gas or liquid. Soulier releases day occur as a result
of ruptured lines, broken gauge glasses, or leaking valves, fittings, flanges,
valve packing, or gaskets.
Failures leading to occidental releases say be broadly classified as due
to process, equipoent, or operational probleas. fauces discussed belcw are
31
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intended to be illustrative, not exhaustive. More detailed discussion of
possible causes of accidental releases are planned for other parts of the
prevention reference manual series.
3.4.1 Process Causes
Process causes are related to the fundasentals of process chemistry,
control, and general operation. Possible process causes of an ammonia release
include:
• Loss of ammonie feed control resulting in the formation of
ammonia-air mixtures within the flammability range;
• Back flow of process reactants to an axmonia feed tank;
• Excess feeds in any part of a process leading to overfill-
ing or overpressuring equipment or excess feed to a
reactor;
• Loss of condenser cooling to distillation units;
• Overheating of reaction vessels and distillation columns;
and
9 Overpressure in a&aoma storage vessels from overheating
(fire exposure) or from unrelieved overfilling.
3.4.2 Equipment Causes
Equipment causes of accidental releases result from hardware failures,
including:
32
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Failure of feed control systems from a loss of power,
clogged lines, jammed valves, or instrument failure;
Excessive stress cn materials of construction because of
improper fabrication, construction, or installation;
Failure of pressure-relief systems;
Mechanical fatigue and shock in any equipment (mechanical
fatigue could be caused by age, vibration, excessive
external loadings, or stresc cycling; shock could occur
from collisions with moving equipment, such as cranes or
other equipment in process or storage areas);
Thermal fatigue and shock in reaction vessels, heat
exchangers, and distillation columns;
Equipment constructed of high alloys, especially high
strength alloys selected to reduce the weight of major
process equipment that might be especially sensitive to
corrosion or severe operating conditions;
Brittle fracture in low-temperature equipment ejected to
large temperature cwinge, or creep failure that might
occur in equipment previously subjected to a fire; and
All forms of corrosion, including ctress corrosion crack-
ing from oxygen contamination; pipe connections that have
slowly corroded because of contaminants entering the
system when cylinders are switched, and external corrosion
from exposure to precipitation or constant dampness.
33
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3.4.3 Operational Causes
Operational causes of accidental releases result from the use of incor-
rect procedures or huaan error, including:
• Overfilled storage vessels;
• Improper process control system operation;
• Errors in loading and unloading procedures;
• Poor quality control; replacement parts that do not seet
system specifications;
• Inadequate maintenance in general, but especially on
pressure relief systems and other preventive and protec-
tive devices; and
• Lack of inspection and non-destructive testing of vessels
and piping to detect corrosion veakering.
34
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SECTION U
HAZARDS PREVENTION AND CONTROL
4.1 GENtRAL CONSIDERATIONS
¦ffhc prevention of accidental releases relies on a combination of techno-
logical, administrative, and operational practices that apply to the design,
construction, and operation of facilities where ammonia is stored and used.
When developing a thorough release prevention and control plan, the following
areas must be considered:
• Process design;
• Physical plant design;
o Operating and maintenance practices; and
• Protective systems.
In each of these areas, specific factors oust be considered that could
lead to a process upset or equipment failure that could directly or indirectly
cause a release of ammonia to the environment. At a ninimum, equipment and
procedures should be in accordance with applicable codes, standards, and
regulations. Stricter equipment and procedural specifications should be
adhered to if extra protection against a release is considered appropriate.
The follovirg subsections discuss specific aspects of release prevention;
Dore detailed discussions will be found in the manual on control technologies,
a coopanion manual in this series.
35
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4.2 PROCESS DESIGN
Process design involves the fundamental characteristics of the processes
that use ammonia, including an evaluation of how deviations froo expected
process conditions might initiate a series of events that lead to an acciden-
tal release. The primary focus i6 on the basic process chemistry, the
variables of flow, pressure, temperature, composition, and quantity. Addi-
tional factors may include mixing systems, fire piotection, and process
control instrumentation. Modifications that enhance process integrity would
involve changes in quantities of materials, in process pressure and tempera-
ture conditions, in the unit operations and sequence of operations, in process
control strategies, and in the instrumentation uced.
Table 4-1 shows the relationship between cercain specific process design
considerations and individual processes descriDed in Section 3 of this manual.
This does not mefn that other factors should be ignored, nor that pro|>er
attention to only those factors in the table will ensure a safe system.
However, the considerations listed, and perhaps ethers, must be properly
addressed if a system is to be safe.
The most significant considerations are aimed at preventing overheating
and/or overprcssurizing systems coniaining ammonia. Overheating is hazardous
because it may lead to overpressure which weakens process equipment and
increases the probability of leaks at joints and valves. Wide temperature
fluctuations also significantly decrease the lifespan of many construction
materials. Overpressure may occur without overheating if flowratc control of
both gas and liquid streams is not maintained.
4.3 PHYSICAL PLANT DESIGN
Physical plant design considerations concern equipment, siting end
layout, and transfer/transport facilities. Vessels, piping and valves,
process machinery, instrumentation, and factors such as location of systems
36
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TABLE 4-1. SOKE PROCESS DESIGN CONSIDERATIONS FOR PROCESSES INVOLVING
AKHYBRCUS AMMONIA
Process Design Consideration Process or Unit Operation
Cjntaaination (with air
especially)
Flow control of assonia feed
Tenperature sensing and beating
media flow control
Tenperature ser.si.ifc and cooling
mediua flow control
Feed tystems, storage tanks,
SCR catalyst
All
Distillation and stripping coluon
reboilers
Distillation and stripping column
condensers
Adequate pressure relief
Storage tanks, reactors, refrigera-
tion condensers, distillation and
stripping columns, heat exchangers
Corrosion monitoring
Large inventory equipoent such as
storage tanks, neutralization
equipment
Tenperature conitoring
Distillation and stripping column
reboilers
Level sensing and control Storage tanks, reboilers and
condensers
37
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and equipment must all be considered. The following subsections cover various
aspects of physical plant design, beginning with a discussion of materials of
construction.
4.3.1 Equipment
Materials of Construction—
Dry ammonia is noncorrosive to most common metals. However, moist
ammonia corrodes copper, tin, zinc, and many alloys, particularly copper
alloys. Therefore, only iron or steel, although they decrease the minimum
ignition temperature, or other nonreactive material should be used in contact
vith ammonia {9}.
Carbon and carbon-manganese steels are commonly used for varjous types of
equipment in ammonia service. hs discussed in Section 3.4.1, one of the
primary concerns with ammonia storage is the susceptibility of certain carbon
steels to stress corrosion cracking in the presence of small amounts of
oxygen. Although it is not possible to specify a particular type of carbon or
carbon-manganese steel that will definitely not succumb to stress corrosion
cracking, it has been found that low-strength steels tyield less thfln 50,000
pounds per square inch) are less susceptible to cracking than high-strength
steels, and thermal stress relief seems to completely eliminate the mechanism
(153.
Piping for ammonia service should be constructed of rigid steel (12).
Copper, brass or galvanized fittings should not be used. Unions, valves,
gauges, pressure regulators and relief devices having copper, brass or bronze
parts are not suitable for ammonia service. Certain aluminum alloys may be
used for various components of amnonia systems. Mercury thermometers in
amaoma service should be avoided (5).
Metallic and nonmetallic gasket materials, such as compressed asbestos,
graphited asbestos, caroon steel or seamless steel spiral-wound asbestos
38
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filled, and aluminum are suitable for ammonia service. Perfluoririated plastic
materials and neoprene have also been found suitable if they are fully con-
fined so as to prevent creep or blow out in the event, of elevated temperatures
(1).
Storage Vessels—
The fact that a large inventory of ammonia contained in storage vessels
on site represents one of the most hazardous aspects of .1 facility that uses
or produces this material has been shown by 0 nuabcr of accidental r^leesec
from storage tanks over the years. In this section, the different types of
ammonia storage vessels and the associated protection devices and safety
procedu-es designed for the prevention of a hazardous release of this cacerial
are briefly discussed.
Anhydrous liquid anconia is stored commercially at full pressure, par-
tially refrigerated, and fully refrigerated in vessels ranging fros two-pcund
cylinders to multi-ton tanks. In general, the quantity of ammonia determines
the choice of container, which in turn influences the maximum storage pres-
sure. Storage at anbient temperature (full pressure) is restricted to rela-
tively small vessels, usually uninsulated and cylindrical in shape with
rounded ends. The nost frequent sizes range from 500 to 45,000 gallons (1).
These containers cust be designed for pressures of at least 250 psig and
constructed in accordance with the American Society of Mechanical Engineers
(ASHE), Boiler and Pressure Vessel Code, Section VIII, Division 1 (24). If
the pressure is only partially reduced, the vessel is usually spherical in
shape and insulated. The storage pressure is splected to suit the individual
requiresnents of the site process. This type of storcge is not as prevalent
today as m the past because of the increasing amount of amtonia being stored
and transported m the fully refrigerated state.
Full refrigeration of the liquified gas at -27.4'F reduces the pressure
essentially to atmospheric. However, a slight positive pressure is necessary
to accommodate minor pressure fluctuations and to avoid negative pressure on
39
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the tank, since air must be excluded. Normally, refrigerated vessels are
flat-bottomed, insulated, cylindrical tankc that are mounted vertically.
Tanks with a design pressure of 15 psig and less must be constructed in
accordance with American Petroleum Institute (API) Standard 620 (28), while
those with a greater design pressure suet be constructed according to the ASME
Code cited above.
The most probable causes of failure of an ammonia storage vessel were
discussed in Section 3.3; they include corrosion and the buildup of
hydrostatic pressure in a liquid-full container caused by overfilling or
overheating. Other possible causes of storage tank failure include brittle
fracture from overst ressing and the use of improper construction oarenals.
This section discusses the safety devices and precautions designed to minimize
the chances of an accidental release resulting fron one of these causes.
Eecausc there is no refrigerated storage of acnonia in the SCAQKD, this
discussion will be limited to pressurized storage vessels cnly.
Precautions should be taken to prevent both internal and extcrnci corro-
sion of ammonia storage vessels. Stress corrosion cracking in amaonic storc^e
vessels is caused by air (oxygen) contamination of the ammonia. The main way
of preventing this type of corrosion is by adding at least 0.2% water. This
is not an absolute safeguard, however, because cracking can still occur in the
areas of the vessel exposed to the vapor phase. Preventive treasures that may
be taken to reduce the risk of stress corrosion cracking include the following
(29):
• Reduce the tensile stress by thermal stress relief of the
entire vessel;
• Decrease the residual welding stresses by shotpeening or
stress relieving crown plates, leg coluan plates, and
botton plates ir. a furnace before cordissioning;
40
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• Careful purging when commissioning; and
• Regularly purge the vapor space with an oxygen-free inert
gas.
Preventing external c-orrosior involves good housekeeping and maintenance
practices that assure that containers are never in contact with standing water
or exposed to continual daspness.
Pressure relief valves and rupture discs are designed to allow a con-
trolled release of oveipressurized contents. According to American national
Standard (ANSI) K61.1, pressurized anmort a stor,ii;o containers (with the
exception of small cylinders) should be p'ovided wirh one or more pressure
relief valves of the spring-loaded type that are set to discharge at a pres-
sure not exceeding the design pressure of the container. The Compressed Gas
Association (CGA) specifies that the maximum discharge rale of the valve
should u™ such that the pressure t.n the container will not exceed 12C5 of the
design pressure '1). Further provisions reco=crded by the CGA and AIJGI X61.1
irciude the following (3,8):
• The discharge from pressure relief valves should be
directed away froa the container upward and unobstructed
to the open air.
• Vt»nt pipes should be neither restrictive nor scalier in
size than the pressure relief valve outlet connection.
• Vent pipes should have looce-f it ting csps to exclude water
and debris but oust not restrict free discharge of vapor.
Suitable prevision should also be sade for draining
condensate that aay accuculatc.
41
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• Shut-off valves should not be installei between the
pressure relief valves and the container unless the
arrangement is such that full flow is possible through at
least one nonisolated pressure reliaf valve at the re-
quired capacity. (Dual relief valves are usually fitted
that can be isolated individually and that are interlocked
so that a relief valve can be removed for servicing
without losing protection of thr; vessel (15).)
A cylinder containing less than 165 pounds of ammonia is not required to
have a pressure relief device (1). Instead, cylinders are designed *o with-
stand very high pressures, since these containers are generally used indoors
where product containment is paramount. Regardless of the higher design
pressure, these containers should be protected froa fire and direct exposure
to the sun, because they are still susceptible to becoming liquid full fron an
increase in teaperature. Without a pressure relief device, overpressure would
result in a sudden rupture and cooplete discharge of the cylinder contents.
In addition to venting provisions, storage vessels should have vaJvc
arrangements that allow the vessel to be isolated fron the process tj which
the ammonia is being fed. Sackflow of material into the upper valve chambers,
when the feed valve is shut off at the storage tank must be prevented because
of the possibility of corrosion in the feed pipe. Other valve specifications
found in ANSI K61.1 require storage tank filling connections to be provided
with an approved conbination back-pressure check valve and excess flow valve;
one double or two single back-pressure check valves; or a positive shut-off
valve, in conjunction with either an internal back-pressure valve or an
internal excess flow valve (8). Each container should also be equipped with a
vapor return valve.
To reduce the risk of overfilling during transfer to a cylinder or bulk
storage tank, the vessel 13 often mounted on d scale that will indicate the
v-eight of fluid in the container at all times. All bulk storage vessels
1*2
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should al6o be equipped with a reliable liquid level gauge that allows for
quick and accurate readings. The design and installation of an ar.monia liquid
level gauge should adhere to the requireaenta given in ANSI K61.1 (8). Most
ammonia storage tanks have float-type gauges whereby a float mechanism is
magnetically coupled to a pointer that indicates percent of capacity by volume
(1). Although this is an accurate aethod of measuring the level, the equip-
ment is vulnerable to mechanical damage and is often supplemented with an
additional measuring device. A differential pressure gauge that measures the
6tatic bead of the liquid is one possible back-up (15). Each storage contain-
er nameplate should include markings indicating the maximum level to ^hich the
container may be filled with liquid ammonia between 20°F and 100°F. The
percent of the maximum volume of the container that may be filled with liquid
ammonia for various temperatures is given in Table 4-2.
Since an overfilled storage vessel is a serious hazard, it 16 normal for
level indicators to be fitted with high-level alarms to warn the operator when
the maximum filling level has been reached (15). As a further precaution, a
short, vented dip pipe can provide protection from overfilling io the event of
failure of the volume or weight oeocuring device. However, this device will
not prevent an overflow of ammonia liquid. Furthermore, it vill only work it
there is no other outlet from the vapoi space and if the line to the vent
system has enough capacity. An extra level of protection would be to fit the
vessel with a relief device that discharges to an overflow tank or other
suitable receiver.
Process and Reaction Vessels-
General hazard control considerations for storage vessslo also apply to
the design and use of process and reection vetsels. In the latter type of
vessels, however, there is a greater degree of hazard, since these containers
are often exposed to more severe conditions of temperature and/or pressure
than is a regular storage vessel.
Primary considerations for process and reaction vessels include:
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TABLE 4-2. MAX I HIM SAFF. VOLUME OF LIQUID AMMONIA IN NONREFMGERATED
STORAGE CONTAINERS AT VARIOUS TEMPERATURES
Temperature of Liquid Maximum Safe Volume
Ammonia in Tank LiquiJ Ammonia as a % of
°F Container Water Volume
30 87.3
<»0 88.3
50 89.5
60 90.7
70 91.8
80 93.0
90 96.6
100 95.7
Source: Reference 1
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* Materials of construction;
• Pressure relief device*;
• Tenperature control.;
• Overflow protection; and
• Foundations and supports.
The foundations end supports fjr vessels arc important design considera-
tions, especially for large storage vessels and tall equipment such as distil-
lation coiunnc. The choice of construction materials ic also an important
considuration, particularly where lov-teoporature conditions are encountered.
Expert advice should olweyo be sought in the design and procureoent of equip-
ment for liquid asconia duty.
If cooling to a condenser is lost, overpressure nay occur: therefore, it
is necessary to use pressure relief valves to protect ap.ninot lcakt and
ruptures that con result froo overpressure. Pressure relief protection is
alno necessary in the event of • firo.
Distillation and stripping coluans present significant release hazards
because thoy any contain large aoounts of aneonia in pure for© and have a heat
input. Since they are often located outdoors, external fnctorc such as
aobient teoperature fluctuations and wind loadings Bust be properly crcounted
for in tlieir design and construction, especially for the support structure.
Piping--
Ml acujonia piping should be extra heavy (Schedule SO) steel when thread-
ed joints are used (1). However, schedule ^0 piping cay be used when joints
are cither welded or joined by flanges. All refrigeration systes piping
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should confora to ANSI B31.5 - American National Standard for Refrigeration
Piping (31). Iron and steel pipirg, fittings, and valves are 6uitable for
aemonia gas and liquid. Nonmalleable metals, such as cast iron, must not be
used for fittings (I). Because low temperature embrittlement i6 a concern in
osaonia nystecs. material selection oust take this into account.
Because liquid ammonia expands with temperature, hydrostatic
pressure-bursting of lines r.ust be prevented. This nay be accomplished with
expansion chambers, which should be located at the highest point of each
section that say be clcsed, trapping liquid ammonia. Construction of these
chambers should be in accordance with the ASME Code for Unfired Pressure
Vessels, Taction VIII (24). An expansion chamber device typically consists of
a rupture disc and a receiver chamber that can hold 20-302 of the protected
line*s capacity. The chaster is equipped with a pressure indicator or alarm
switch set to function on disk rupture. Alternatively, a hydrostatic relief
valve may be installed in each section of piping in which liquid aemonia can
be isolated between shut-off valves.
Following is a list of general guidelines for the safe transport of
liquid aemonia in piping systems (8,18):
• Piping systems should have as simple a design cs possible
and a minimum number of joints and connections; flow
should not be restricted by an excessive number of elbows
and bends.
• Piping shoi Id be at least 7.5 feet above the floor if
possible; prevision should be made to protect all exposed
p\pirg from physrcol damage that might result from coving
machinery, the presence of automobiles or trucks, or any
other undue s'Tain.
46
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• In addition to being securely supported, pipes should be
sloped with drainage provision et the low points.
• Clips or hangars should not fit too tightly, to allow for
thermal expansion of the pipe.
• Piping should be protected froa exposure to fire and high
temperatures.
• A pressure-reducing regulator should be installed vhen
connecting to lower pressure piping or systems froa
storage vessels.
• Pipelines should alvays be emptied when ecconia fJov is
not required to prevent the possible isolation of liquid
ammonia between closed valves.
Valves—
Valves in ammonia service are discussed in a runber of references
(1,8,18). Several typos of valves, including gate, globe, ball, and check
configurations, are used in ammonia systems. Construction cay be of iron or
steel. Copper and copper-bearing sarenals must not be used for the valve or
trim perts, because these materials are attacked by aca~onia (vhon moisture is
present.)
It is good practice to locate stop valves in the inlet and outlet lines
to all condensers, vessels, evaporators, and long lengths of pipe so they can
be isolated in case of leaks and to facilitate puaping out. If globe-type
valves are used, they should be installed with the valve stem horizontal to
reduce the chance for dirt or scale to ledge on the valve seat or disk (18).
Pressure regulators, solenoid valves, and thermal expansion valves should
be flanged for easy assembly and removal. A strainer should be used in front
47
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of self-contained control valves to protect them from pipe construction
material and dirt (18). Solenoid valves should be located upright and pro-
tected fron moisture. A manual opening steD is useful for emergencies.
When amaonia flov is shut off ot the feed tank, the piping system between
that point and the point of application is filled with vapor. Gradual absorp-
tion of the vapor in the process fluid leaves a vacuus that draws ammoniated
fluid back into the piping system. This may cause serious problems, especial-
ly if the s'nut-off point is upstream from instruments and other items of
equipment. A diaphragm-operated check valve held in o clos'd position by
amaonia pressure may be used to prevent undesired back or re>erse flows. If
the ammonia pressure fall6 and pressure on the diaphragm becomes
subatmospheric, the valve opens and ellows air to flow into the piping system,
thus breaking the vacuum that would otherwise cause backtlow of the process
fluid.
Excess flow valves should be considered for ammonia in vessels, tank
cars, and other places vhere unintentional high liquid dibcharge ratec need to
be prevented. If a liquid discharge line is broken, the reculting high flow
rate would cause the valve to close off, restricting the eccope of ecjuonia.
The pressure of amtsonio gaa can be controlled by a pre66ure reducing and
regulating valve of steel construction. The valve should be designed for the
range of conditions under which it will be required to operate, taking into
account the maximum and minimum flow of ammonia gas, itB average temperature,
ond the average upstream and downstream pressures (1).
Process Mai. linery—
Proce-. machinery refers to rotating or reciprocating equipment that may
be used in the transfer or processing of ammonia. Included in this classifi-
cation are puaps and compressors that may be used to neve liquid or gaseous
ammonia where gas pressure padding is insufficient or inappropriate.
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Pump—
Any pump used in ammonia service oust conform to ANSI/UL 51 - American
National Standard for Power-Operated Puape for Anhydrous Ammonia and LP Gas
(32). To ensure that a given pump is suitable for an ammonia service applica-
tion, the design engineer should obtain information from the pump manufacturer
certifying that the pump will perform properly in this application.
Centrifugal pumps are normally used for pumping liquefied ammonia in a
fully refrigerated condition (15). Glandless, canned-type or conventional
pumps fitted with e.ther a single mechanical seal together with a soft packed
auxiliary gland or a double mechanical seal may be used. Canned pumps are
generally used indoors or in congested areas. When a glanded pump is used, a
mechanical seal is advisable, followed by a soft packed gland (15). The seal
precsure should not exceed the manuf--cturer's recommendations, and the inter-
space should be vented in a safe manner.
Pumps should be constructed of materials resistant to ammonia at operat-
ing temperatures and pressures. Lubricating oil should be resistant to
breakdown after contact with ammonia. In some races, the potential for seal
leakage may rule out the use of rotating shaft seals. Some pump types that,
either isolate the seals from the process stream or eliminate them altogether
include canned motor, vertical extended spindle submersible, magnetically-
coupled, and diaphragm (6).
Net positive suction head (NPSH) considerations are especially important
for ammonia. sin*.e the liquid may be pumped near its boiling point. bong
suction lines reduce the effective NPSH available, and if the suction lines
are very long in rt^ation to the NPSH available, a vapor release vocsel should
be fitted in the sue-.on line as close to the pump os pocsible (15). The pump
supply tank should have high and low level alarms, and the pump should be
interlocked to shut off at low supply level or low discharge pressure.
49
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Centrifugal pumps often have a recycle loop back to the feed container
that prevents overheating if the pump is deadheaded (i.e., the discharge
valves close.) Positive displacement pumps can be equipped with a constant
differential relief valve capable of discharging the entire capacity of the
pump into the suction port of the pump to prevent rupture if deadheading
occurs. When a positive displacement pump is used to reduce the chance of
backflov, such a relief valve could defeat this purpose if the back pressure
were high enough. In f.uch a case, the relief valve discharge should be routed
somewhere other than to the suction part of the pump. Pumps can also be
protected by a differential pressure switch fitted across the pump to trip the
motor should a low-pressure condition arise. This could be caused by inade-
quate priming, by vaporizing in the uunp, or by too low a suction head.
Compressors—
Ammonia compressors include reciprocating, centrifugal, liquid-ring
rotary, and non-lubticated screw compressors. Usually two-stage reciprocating
compressors are used for ammonia service, although rotary compressors are also
common and may be preferable if it is necessary to avoid oil contamination
(15). Detailed descriptions of the different types of compressors may be
found in the technical literature (6).
Ac with pumps, construction materials must be selected that are compati-
ble with ammonia at the operating conditions. Copper and copper-bearing
alloys must be avoided and particular attention paid to the gland arrangement
(15). Any ammonia compressor must be decigned for at least 250 psig working
pressure, except those used for refrigeration service.
A pressure relief valve large enough to discharge the full capacity of
the compressor should be installed between the discharge of the compressor and
the high pressure shut-off valve. If the crank case is not designed to
withstand system pressure, Jt should also be protected with a suitable pres-
sure relief valve. In addition, a liquid trap should be installed before the
coopreesor suction to prevent entry of liquid into the compressor*
50
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Miscellaneous Equipment—
Pressure Relief Devices Pressure relief devices for ammonia service
should be constructed in accordance with CGA S-1.3 - "Pressure Relief Device
Standards - Part 3 - Compressed Gas Storage Containers" (33). All vetted
parts of relief valves and rupture disks should be constructed from materials
compatible with ammonia at the operating temperature and pressure. For
balanced relief valves, the balance seals must also be made of appropriate
materials.
Measures should be taken to ensure that process equipment is not isolated
from its relief system. To provide continuous pressure relief protection when
a device requires maintenance, equipment may be provided with dual relief
systems, each sized to provide the total required flow capacity. Stop valves
installed between a vessel and its relief device should have a full port area
at least equal to that of the pressure relief device inlet. These valves
should be locked open or have handles removed when the protected vessel is in
use. If the discharge is to be piped to a closed disposal system, the pres-
sure drop caused by the additional piping muct be considered and the relief
device sized accordingly.
Some aspects of the proper placement and use of pressure relief valves
have been discussed earlier in this section in conjunction with storage
vessels. Additional guidelines for the correct use of pressure relief valves
include the following (8):
• Arrangement should minimize the possibility of tampering
with the pressure setting adjustment;
« They should have direct communication with the vapor space
of the container:
51
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• The flow capacity should not be restricted by any connec-
tion to it on either the upstream or downstream side; ord
• Discharge from pressure relief valves should not terminate
in or beneath any buildin°.
Rupture dicks may be used to protect pressure relief valves irom constant
contact with the contents of the storage vessel. Rupture disks should not be
used in ammonia service, however, where the ruptured disk discharges directly
into the atmosphere. If the disk relieves the contents of the container
through a spring-loaded pressure relief valve, a small vent should be provided
in the chamber between the disk and the valve to prevent any back pressure on
the rupture disk. Because operating pressures exceeding 70% of a disk burst-
ing pressure may induce premature failure, a considerable margin should be
allowed when sizing rupture disks.
Instrumentation— For normal applications, all steel pressure gauges
graduated from O-'tOO psig are recommended for ammonia service (1). For low
pressure work, the range for the gauge should be one and one-balf times the
maximum service pressure.
The most commonly used flowmeter for ammonia gas is the tapered tube,
float type (1). For high pressure work the glass tube should be enclosed in a
vented shield or, preferably, a oteel-armored type. Orifice meters with
differential pressure cells may also be used. Mercury manometers chould not
be used in ammonia service. The quantity of liquid ammonia transferred from
one system to another may be measured with positive displacement or turbine
meters.
Magnetic or rotary gauges are preferred to gauge glasses (5). Ammonia
should never be closed into a gauge glass, since an increase in pressure may
break the glass. Glasses should be equipped with excess flow valves to stop
52
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the flow of ammonia if breakage occurs, and they should have automatic
self-closing chut off valves that must be held open to take a reading (5}.
A,3.2 Plant Siting and Layout
The siting and layout of a particular ammonia facility is a complex issue
that requires careful consideration of numerous factors, including the other
processes in the area, the proximity of population centers, prevailing winds,
local terrain, and potential natural external effects, such as flooding.
The siting of facilities or individual equipment items should reduce
personnel exposure, both plant and public, in the event of a release. Since
there are also other siting considerations, there may be trade-offs Detveen
this requirement and others in a process, some directly safety related.
Siting chouJd allow ready inRress or egress in the event of an emergency ard
yet also take advantage of barriers, either man-made or natural that could
reduce the hazards of releases. Large distances between large inventories and
sensitive receptors is desirable.
Various techniques available for fornally assessing a plant layout
should be considered when planning high hazard facilities (3b).
The siting and layout of any facility handling ammonia should adhere to
the following general guidelines:
• Areas where ammonia hazards exist bhould hove an adequate
number of well-marked exits through which personnel can
escape quickly if necessary; doorr. should open outward ard
lead to unobstructed passageways;
• The plant should be laid out so that there are no confined
spaces between equipment; large distances between large
inventories and sensitive receptors is desirable;
53
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0 Access to platforms above ground level should be by
stairway instead of cat ladders, and work areas above
giound level should have alternative means of escape;
o The ground under process equipment and storage vessels
should be sloped so that fire water and liquid spillages
flow away from equipment and into drains;
0 Storage facilities should be located in cool. dry. well-
ventilated areas, away from heavily trafficked ereas and
emergency exits; and
o Tank car, tank truck and storage facilities should be
located away from sources of heat, fire and explosion.
Because heat couses thermal expansion of liquid asnonia, measures should
be taken to situate piping, storage vessels, and other 2=20:113 equipment :c
that they arc not located adjacent to pipirg containing flasrablc materials,
hot process piping, equipment, steam lines, and other sources of direct or
radiant heat. Special consideration should be given to the location of
furnaceB and other permanent sources of ignicion in the plant. Storage should
also be situated away from control rocas, offices, utilities, and laboratory
areas.
In the event ot an emergency, there should be more than one entrance to
the facility which is accessible to emergency vehicles ar.d crews. Storage
vessel 6hut-off valves should be readily accessible. Containment for liquid
storage tanks can be provided by daking, wnich reduces evaporation rates while
containing the liquid. It is also possible to equip a diked area with drain-
age to an underground containment sump. This sump would be vented to either a
recovery or scrubber system for safe removal. A full cor.iairacru systez ir. a
specially constructed building is another possible option. This type cf
54
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secondary containment could be considered for large volume, liquid amaonia
storage tanks.
4.3.3 Trensfer and Transport Facilities
Transfer and transport facilities where both road vehicles and rail
tankers are loaded or unloaded are likely accident areas because of vehicle
movement and the intermittent nature of the operations; therefore, special
attention should be given to the design of these facilities.
Before unloading, tank vehicles should be securely aoorcl; an interlocked
barrier system is commonly used. Tank cars must also be protected on both
ends by derailers or on the switch end if located on a dead end siding.
Sufficient space should be available to avoid congestion of vehicles or
personnel during loading ard unloading operations. Vehicles, especially
trucks, should be able to cove into and out of the area without reversing.
High curbs around transfer areas and barriers around equipment should be
provided to protect equipment from vehicLe collisions.
Correct procedures oust bo followed when unloading and handling annll
ammonia storage vessels. Dragging, sliding, or rolling cylinders, even for
short distances, is not acceptable. Lifting magnets, slings of rope or chain,
or any other device in which the cylinders themselves fora a part of the
carrier should never be used for transporting cylinders.
4.4 PROTECTION TECHNOLOGIES
This subsection describes two types of protection technologies for
containment and neutralization:
• Enclosurps,
• Scrubbers, and
0 Flares.
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4.4.1 Enclosures
Enclosures refer to containment structures that capture any ammonia
spilled or vented from storage or process equipment, thereby preventing
immediate discharge of the chemical to the environment. The enclosures
contain the spilled liquid or gas until it can be transferred to other con-
tairuaent and discharged ct a controlled rate that would not be injurious to
people or to the environment, or transferred at a controlled rate to water
scrubbers for absorption.
Specially designed enclosures for ammonia storage or process equipment do
not appear to be in widespread use, since some sources suggest that it is
preferable to locate toxic operations in the open air (34). The desirability
of enclosure depends partly on the frequency with which personnel nust be
involved with the equipment. A common design rationale for not having an
enclosure where toxic materials are used is to prevent the accumulation of
tc-ic concentrations within enclosed areas. However, if the issue is to
provide secondary containment, total enclosure coy be appropriate, enclosures
should be equipped with continuous monitoring equipment and alarm, which
should sound whenever lethal or flammable concentrations are detected.
Care must be taken when an enclosure is built around pressurized equip-
ment. It would not be practical to design an enclosure to withstand the
pressures associated with the sudden release of a pressurized vi ssel because
the pressure created from such a release could cause an enclosure to fail and
create an additional hazard. If an enclosure is built around pressurized
equipment, it cho
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storage do not normally lend themselves easily to effective liquid contain-
ment. However, containment can be accomplished if the floor of the enclosure
building is excavated several feet below the track level while the tracks are
supported at grade in the center.
While the use of enclosures for secondary containment of ammonia spills
or releases is not widely used, it might bo considered for areas near sensi-
tive receptors.
4.4.2 Scrubbers
Scrubbers are a traditional method for absorbing toxic gases from process
streams. These devices can be used for the control of ammonia releases from
vents and pressure relief discharges, from process equipment, or from secon-
dary containment enclosur's.
Because of its high solubilicy. ammonia discharges coulil be absorbed in
water in any of several types of scrubbing devices. Types cf scrubbers that
might be appropriate include spray towers, packed bed scrubbers, and venturiu.
Other types of special designs might be suitable, but complex internal.-;
subject to corrosion do not seen to be advirable.
For any type scrubber selected, a complete system would include the
scrubber itself, a liquid feed system, and water makeup equipment. If such a
system is used as protection against emergency releases, consideration must be
given to how it would be activated in time to respond to an emergency load.
One approac'i used in some process facilities is to maintain a continuous
circulation of scrubbing liquor through the system. For many facilities this
would not be practical, and the scrubber system might be tied into a trip
system to turn it on when needed.
Ventun scrubbers have an advantage where the scrubbing system must be
activated by a trip system. Since a ventun scrubber can create its own draw
57
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of vapor by the flow of the scrubbing medium, a trip system need only turn on
the flow of liquid :c the scrubber rather than turn on the flow of liquid and
start up a blower, as would be required in other types of scrubbing systems.
Another approach is the drowning tower, where the ammonia vent is routed
to the bottom Kit o large tank of uncixculating water. The drowning tower does
not have the hi£h contact efficiency of the other scrubber types; however, it
can provide substantial capacity on demand as long as the back pressure of the
hydrostatic heaJ does not create a secondary hazard, by impeding an
overpressure relief discharge.
A.4.3 Flarec
Flares are devices routinely used in the chemical process industries to
bum intenr'tt'nt or emergency emissions of ammonia wa6te gases (35). A flare
is a section of vertical piping with a specially designed cocbustion tip. The
flare burns the ammonia, forming carbon dioxide and nitrogen oxide. Although
ammonia is not usually thought of ac a flammable gas it con burn if ignited at
a high enough temperature (1,200 °F). Its flamoability limits in air are 15.0
to 25.0 2 (5). Flarys ore distinguished from other ptoceGs cccbuotion devices
such as incinerators by their design to handle extreme flow rate variations
and their unenclosed combustion zone.
A total flare system consists of collection piping, a seal pot, a liquid
knock-out vessel, and the flore itself. Two basic types of flares are
elevated flares and enclosed ground flares. The elevated flare is usually
designed to handle larger flowc than the ground flare, and is bore likely to
be used for high volume upset or emergency flaring situations. The ground
flare is nore likely to be used for smaller volume, routine process venting.
Basic design requirements for flares burning ammonia are:
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• The ability to opera;e safely ov«r a wide range of flow rates and
varying compositions,
• Have acceptable enissions of radiant heat and noise, and
• Achieve acceptable deetruction efficiency for aanonia.
The ability of flares to accossodate large variations in flow rate ia an
important consideration in using them for protection against accidental
aoconia releases. Depending on the size of a flare relative to a potential
release, the accidental releace flow rare any constitute a large or seall
fraction cf the total flare flow rate and correspondingly could have a
significant or relatively minor effect on the instantaneous total flow rate
and flare perforsince.
There ar® two possible ways a flare oystes con be uccd to protect againut
accidental omaonia releases. The first io to use an existing flare cyaten.
The oecond is to uae a dedicated "ucergency" bysreo. Whether a dedicated
flare or chared flare is used depends on eite specific considerations. A
shared flare oay be advantageous tor sevcial reasons. A dedicated flare
aystea (or infrequent ecergency ute cay bo difficult to safely caintain in
full working condition. A shared flar" cay allow connection to an existing
aystoc. With a shared flare, however, design for energency corditions oust
ensur* that s large release of acsonia does not overwhelm the flare and lead
to flaoe blowout, or that the pressure froa the toxic eccrgency release does
not cause a backflow into other process unite tied into the flare collection
piping.
The prieary cotpositloital requireeent of flares is that the vented gases
are easily ignitable and have adequate heating value to ninisise supplesentary
fuel requiresents. Aeaonia hac a net heating volue of 365 3tu/ft^. which 16
greater than the «uni=ua requited (35). However, without assist gas,
approximately 8 percent of the acxonia is released unburned (35). The
59
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fundamental flare design variable ic exit velocity. At maximum flow, the
flame should not leave the burner tip or be blown out. This is achieved by
limiting tho exit volccity. Criterion has been recommended by the EPA to
enaure 98 percent destruction efficiency of flared chemicals using a
steam-assisted flare (36).
Flares can be useful protection against accidental releasee of ammonia.
However, because of potentially dangerous secondary hazards, their use
required e thorough analysis for eecn specific application. In essence, e
flare system is a pipe transporting flammable gases to a flotne at the exit.
As long as the flam? rccaino at the end of the pipe, the system operates
safely. The flame can enter the pipe if oxygen is present above a certain
concent rot ion in the fuel. In o deJicated flare system, the entire collection
network would have to be continually purged to prevent the risk of an
explosion when a accidental release occurred.
Backpressure in the discharge line for an emergency ammonia release is a
concern in discharging to a flare system. Since the flore collection system
operated under a positive pressure (above atmospheric), release rates from an
emergency relief volve will be less than discharge tot he otsospliere. In Home
instances, it is conceivob!
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TABLE 4-3. IMPORTANT CONSIDERATIONS FOR USING FLARES TO PREVENT
ACCIDENTAL CHEMICAL RELEASES
• Maximum flow rate - will it cause a flame blowout?
• Pc66ibility of air, oxygen, or other oxidant entering eysten?
• Is gas combustible - will it soother the flare?
• Will any reactions occur in collection system?
• Can liquids enter the collection system?
• Will liquids flash and freeze, overload knockout drua or cause rain
f i re?
• Is back pressure of collection systea dangerous to releasing vecGel?
• Is releasing vessel goo pressure or teaperature dangerous to
collection oystes?
• Will acids or Gaits enter collection syeteo?
• Uill release go to an enclosed ground or elevated flare?
• If toxic is rot destroyed, what are the impacts on surrounding
conynunity?
¦ , ,i.. . n . .1-1 i ¦¦ 1 i i 1.1 i ¦ i - , ¦ ¦ i ¦ , i , :'ur»u
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release should be determined, and the leak should be plugged to stop the flow
if this is possible. This post release mitigation effort requires that the
source of the release be accessible* to trained plant porcornol. and that
adequate personnel protection be readily available. Personnel protection
includes such ittoo as portable breathing air and chemically resistant protec-
tive clothing.
The next primary concern becomes reducing the consequences of the re-
leased chemical to the plant and the surrounding community. Feducing the
consequences of an accidental release of a hazardous chemical is referred to
ao mitigation. Mitigation techniques include such measures as physical
barriers, water sprays and fogs, and foams. The purpose of a mitigation
technique is to divert, limit, or disperse the chenical that has been released
to the atmosphere. The mitigation method chosen for a particular chemicol
will Jepcnd on the specific properties of the chemical, including its flemma-
bility, toxicity, reactivity, and those properties that determine ire disper-
sion characteristics in the atmosphere.
If a releoce occurs froo a pressurized ammonia storage tank, e quantity
ol liquid will immediately flash to its atmospheric boiling point and produce
a vapor/oerocol cloud of ecuaonia. The remaining liquid will cool to the
normal boiling point of -28°F. Heat transfer froo the oir and ground will
result in further vaporization of tho released liquid. Since the asuac.nia
accidentally released from a refrigerated storage tank is alreody at or below
its normal hoiling point, a comparable quantity of vapor will not flash off,
os with a pressurised releoce, but heat transfer from the environment will
still quickly cause the formation of o vapor 'loud. It is therefore decirablc
to decrease the areo available for best tronofer to a liquid spill, which in
turn will minimize the rate of evaporation. Mitigation technologies used to
reduce the rate of evaporation of a released liquified gan include secondary
containment systems such as impourding basins, dikes, end enclosures.
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A,5.1 Secondary Containment Systems (8.37.38)
Specific types of containment systems include excavated basins, natural
basins, earth, steel, or concrete dikes, and high impounding walls. The type
of containment system best suited for a particular facility will depend on the
rick associated with an accidental release froo that location. Tho inventory
of ammonia and its proximity to other portions of the plant and to the commu-
nity are primary considerations in the selection. The secondary containment
system should be able to contain spills, minimizing damage to the facility and
its surroundings and reducing the potential for escalation of the event.
While it is comcon practice to provide ammonia storage tank installations
with an earth or concrete dike to contain the liquid into o manageable pool
should a total failure of the main tank occur, the efficacy of a dike in the
event of a release from pressurized storage has been questioned, because o
sudden loss of pressurized containment tends to result in ejection of all the
contents in the form of vapor, or 6pray, leaving no residual liquid (15).
There may, however, be situations where a dike would be appropriate for a
pressurized ammonia storage vessel.
A conventional dike is useful when refrigerated storage is involved
because the liquid is already at atmospheric pressure and it is assumed that
moat of tho contents of the tank will be contained within tho confines of tho
dike in the event of a release from the tank. ANSI K61.1 requires that one of
the following should be provided with any primary refrigcrared storoge system;
it includes no similar provisions for pressurised storage (8):
• An adequate drainage system underlying the storage vessels
that terminates in an impounding basin whose capacity is
as large as that of the largest tonk served; or
• A diked areo whose capacity is as large as that of largest
tank served.
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These measured are designed to prevent accidental discharge of liquid ammonia
frsu spreading to uncontrolled areas.
The oost cotaaon type of containaent 6ystem is a low wall earth dike
surrounding one or store storage tanks. Generally, no eore than three tanks
are enclosed within one diked area. Piping should be routed over dike walls,
and penetrations through the walls should b» avoided if possible. Vapor
fences cay be situated on top of the dikes tc provide additional vapor storage
capacity. If there is sore than one tank in the diked area, the tanks should
be situated on berms above the oaximum liquic level attainable in the impound-
ment .
To achieve the required voluoetric capacity, dike heights usually range
froe 3 to 12 f#>et, depending on the area available. The dike walls should be
liquid tight and able to withstand the hydro,itatic pressure and tenperature of
a spill. It say be necessary to construct low wall dikes of low temperature
steel or concrete because of adverse soil conditions or other cpecific re-
quiresents. In addition, coae experiments have shown that earth dikes should
be covered wi*h a layer of clay, asphalt, olootic filei, or a similar notorial
itcpcncesble to liquid osteoma (39). Otherwise, the sancnia will percolate
into the ground, and the loss of anaonis by evaporation will be greater in the
absence of on mperceable layer over the dice.
A low wall dike can effectively contain the liquid portion of an acciden-
tal release; however, since a dike also liaits access to the tank during a
spill, a reoote lxpounding basin Day be considered if a relatively large site
is available within a reasonable distance of the storage systea. With such a
systea. the flow is directed to the basin by dikes ond channels under the
storage tanks; these are designed to Bin.mize c-xpoouie of the liquid to other
tanks and surrounding facilities. The acvantages of this type of systea are:
• The spilled liquid is removed froa the icaediate tank
area;
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• The probability of the spilled liquid cauBinfc further
damage to the tank, piping, electrical facilities, puope,
and other equipment is reduced;
• Tho tank area is accccsible during the »»'ll; and
• Accesa to the tank pusps or related piping for regular
operation, inspection, or eaintenance 16 not rectricted by
the impoundment.
The impounding basin may be located to take advantage of the natural topogra-
phy of the area, thus minimizing additional excavation and diking. A suop can
also be provided within the Dim impounding basin to lioir the liquid surface
and ground contact areas. Furthermore, the depth of the baein can be in-
creased to provide vapor containoent.
Although few authorities for amaiania facilities require thesi, high wall
inpound:r«nts may be the best secondary containnent choice for eelected sys-
tems. Cirruaatances that may warrant their use include lioited storige site
area, the need to ninittize vapor generation rates, and/or the need for the
tank to be protected Iron external hoiardo. Paxi&ua jcpor generation rotec
will generally be lower for a high wall icpoundcent than for low wall dikec ot
reaote impoundmente because of the reduced ourfacc contact area. Theoe reteo
can bo further reduced with insulation on the wall and floor in the annular
space. High impounding walls Day be constructed of low-tecperature ateel.
reinforced concrete, or preetreseed concrete. A weather shield aay be provid-
ed between the tank and wall with the annular space reoaining open to the
atooophere. The available area surrounding the storage tar.k will dictate the
minitnun height of the wall. The walls oay be designed with a voluaetric
copacity greater than that of the tank to provide vapor containaent. Increas-
ing the height of the wall also raises the elevation of any released vapor.
f> 5
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One disadvantage of rhese dikes is that high vails around a tank cay
hinder routine external observation. Furthermore, the closer the wall is to
the tank, the eore difficult it becomes to reach the tank for inspection and
maintenance. As with low vail dikes, piping should be routed over the wall if
possible. The closeness of the vail to the tank may necessitate placement of
the puap outside of the vail, in vhich case the tank outlet (suction) line
will have to paea through the wall. In ouch a situation, t low dike encom-
passing the pipe penetration and puap nay be provided, or a low dike eay be
placed around the entire wall.
A further type nf secondary containment system is one structurally
integrated with the primary system and forming a vapor-tight enclosure around
the primary container. Such a system may be considered when protection of the
primary container and containment of vapor for events not involving foundation
or wall penetration failure are of greatest concern. The drawbacks of an
integrated aysteo are the greater complexity of the structure, the difficulty
of access to certain components, and the fact that complete vapor contairaent
cannot be guaranteed for all potential cventG.
Provision should be cade for draining of rainwater froci both ltrpounding
basins and diked areas. This will involve sumps and separate drainage pumps,
since direct drainage to stonswater severs would presumably allow any spilled
onmonia to follow the aaoe route. Alternately, o sloped rain hold aay be used
over the diked orea. vhich could also serve to direct the rising vapors to a
oingle release point (38). The ground within the enclosure should be graded
so that the spilled liquid will accumulate at one side or in one coir.er, which
will help decrease the area of ground to which the liquid is exposed and froa
which it may gain heat. In areas where it is critical to minimize vapor
generation, surface insulation cay be used in the diked area or impoundment to
further reduce heat transfer froa the environment to the spilled liquid. The
floor o: an impoundment should be cealed with a clay blanket to prevent the
atsaonia from seeping into the ground; percolation into the ground causes the
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ground to cool more quickly, increasing the vapor generation rate. Absorption
of the ammonia into water in the soil would also release additional heat.
A.5. 2 Flotation Devices o.id Foams (39, AO.41,62)
Other possible Deans of reducing the surface area of spilled liquid
ammonia include placing impermeable flotation devicec on the curface, dilution
with water, and applying water-baced foams.
Placing a lid over a spilled chemical ib a direct way of containing the
toxic vapors, with nearly 100 percent efficiency. The floating cover say be
continuous or a distribution of light particulates. However, thio technique
requires that a cover be acquired before the spill occurs and stored until
needed, and in all but small spills deployment may be difficult. Furthermore,
although particulate covers are potentially effective, cost io a deterrent to
their uoo. Determining what materials are appropriate for an ammonia spill
has been the subject of some research (37), but the use of mechanical barriers
on an actual spill has not been rt-j-orted in the literature.
One approach to an nmmonia spill is dilution with water, but, because of
the high heot of solution, adding pure water would couoe a violent boil-off of
ammonia. A water-based foam cover ie one way of diluting the oemonia with a
mirinurt heat of tolution becouoe water is added slowly. While the use of
foams for vapor hazard control has been demonstrated for a broad range of
volatile chemicals, it io difficult to accurately quantify the benefitu of
foaj> systems, because the effects will vary as o function of the chemical
spilled, foam type, spill a'zc, end atmospheric conditions. With regard to
liquified goceo, it hoa been found that with some materials, foomc have a net
positive effect, bur with others, foams may exaggerate the hazard.
When a foam cover ia first applied, an increase in the boil-off rate is
usually observed that couoee a short-term increase in the downwind ammonia
concentration. The initial foam cover moy be destroyed by violent boiling, in
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which case a second p-pLication is necessary. Once a continuous layer is
foraed, a net positive effect will be achieved in the downwind area (40). The
reduction in downwind concentration ib a result of both increased dilution
with air. because of a reduced vaporization rate, and the increased buoyancy
of tne vaoor cloud. This latter effect is caused by the vapor being warned as
it rises through tho blanket by heat transfer froa the foaa and by the heat of
solution of ammonia in water; the warned vapor cloud will have greater buoyan-
cy and will disperse in ar. u|.jard direction more rapidly.
Tne extent of the downwind reduction in v_oncentracior will depend on tho
type of foam used. Research in this area has indicated that foams with a
medium to high expansion ratio (75 to 350:1) give cignificantly better results
than do foaas with low expansion ratios (6 to 8:1) (40,41). The expansion
ratio is the ratio of the volume of foaa produced to the voluae of solution
fed to the foaa-generating device. Furthermore, a high expansion foaa will
cause a smaller initial increase in boil off than a low expansion foaa.
Regardless of the type of foaa used, the slower the Jramage rate of the
foaa, the better its performance) will be. A slow-draining foaa will spread
more evenly, ahow aoro resistance to teaperature and pH effects, and collapse
aorc slowly. The initial cost of a slowly draining foaa may be higher than
that of other foaas, but a cost-effective system will be realized in superior
performance.
4.5.3 Mitigation Techniques for Ammonia Vapor (AT.44)
The extent to which the escaped ammonia vapor can be removed or dispersed
in a timely manner will be a function of the quantity of vapor released, the
ambient conditions, and the physical characteristics of the vapor cloud. The
behavior and characteristics of the ammonia cloud will be dependent on a
number of factors. These include the physical state of the ammonia before its
release, the location of the release, and the atmospheric and environmental
conditions; a number of predictive dispersion models have been developed. In
spite of the lower specific gravity of pure amaonia vapor, large accidental
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releases of ammonia have often resulted in the formation of ammonia-air
mixtures that are denser than the sunounding atmosphere. This typo of vapor
cloud is especially hazardous, because it will spread laterally and remain
close to the ground.
Tho primary means of dispersing as well as removing ammonia vapor from
the air is by using water sprays or fogs. The water is applied to the vapor
cloud with hand-held hoses and/or stationary water-spray barriers. For
effective absorption, it is important to direct waterfog or spray nozzles from
a downwind direction to avoid driving the vapors downwind more quickly. Other
important factors relating to the effectiveness of water sprays are the
distance of the nozzles from the point of release, the fog pattern, nozzle
flow rate, pressure, and nozzle rotation. If the right strategy is followed,
a "capture ione" can be created downwind of the release into which tho ammonia
vapor will drift and be absorbed. In low wind conditions, two fog nozzles
should be placed upwind of the release to ensure that the asmonia cloud keeps
moving downwind against the water fog nozzle procures. If water fog is used
to absorb ammonia vapors from a diked area containing spilled liquid ammonia,
great care must be taken not to direct water into the liquid ammonia uself.
Water-spray barriers consist of a series of spray nozzles tnuc can be
directed either up or down. If placed 30-40 feet from the point of aaaonia
release, theso barriers are very effective in absorbing the anaonia vapors
passing through without distorting the ammonia cloud (A3). Several fog
nozzles may be situated farther downwind to absorb the remainder of the vapors
getting through.
In general, techniques used to disperse or control vapor eaissions should
be simple and reliable. In addition to tho mitigation tecnniques discussed
aoove, physical barriers such as buildings and rows of trees will help to
contain the vapor cloud ana control its movement. Hence, reaucing the conse-
quences of a hazardous vapor cloud can actually begin with a carefully planned
layout of the facilities.
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4.6 OPERATION AND HAINTfMANCE PRACTICES
Accidental releases of toxic materials result not only from deficiencies
of design but also from deficiencies of operation. Thus safe operation of
plants using ammonia requires competent and experienced managers and staff, in
addition to a well-considered and full/ understood system of work.
Employees should be trained about the important aspects of handling
ammonia, including: the proper aeana of handling and storing, hazards
resulting from improper use and handling, prevention of spills, cleanup
procedures, maintenance procedure*, and emergency procedures. Well- defined
and planned practices and procedures can reduce the possibility of an
accidental release and the magnitude of an accidental release, if it should
occur.
To reduce the chances for an accidental release, proper maintenance and
modification programs should be a normal part of plant operation and design
procedures. Maintenance should be based on a priority system to ensure that
the aor.t critical equipment is taken care of first. Strict procedures should
apply to process modifications to ensure that modifications do not create
unintended hasarde. Inspections and nondestructivi testing of vessels,
piping, and machinezy should be conducted periodically to detect small flaws
thar could eventually result in a major release.
4.7 CONTROL EFFECTIVENESS
It is difficult to quantify the control effectiveness of preventive and
protective measures to reduce the probability and magnitude of accidental
releases. Preventive measures, which may involve numerous combinations of
process design, equipment design, and operational measures, are especially
difficult to quantify because rhey reduce a probability rather than a physical
quantity of a chemical release. Since protective measures are more analogous
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to traditional pollution control technologies they nay be easier to quantify
in terms of their efficiency in minimizing the adverse effects of a chemical.
Preventive neasures reduce the probability of an accidental release by
increasing the reliability of both process systems operation? and equipment.
Conrrol effectiveness can thus be expressed for both the qualitative improve-
ments and the quantitative improvements through probabilities. Table 4-4
summarizes whet appear to be some of the major design, equipment, and opera-
tional measures applicable to the primjry hazards identified for the ammonia
applications in the SCAQMD. The items listed in this table are for illustra-
tion only and do not necessarily represent a satisfactory control option for
all cases. These control options appear to reduce the risk associated with an
accidental release when viewed from a broad perspective; however, there are
undoubtedly specific cases where these control options will not be appropri-
ate. Each case mu6t therefore be evaluated irdividuolly.
4.e ILLUSTRATIVE COST ESTIMATES FOR CONTROLS
This section presents cost estimates for different levels of control and
for specific release prevention and protection meosures that might be found in
the SCAQMD for ammonia storage and process facilities. The estimates are
presented first, followed by a discussion of the bases for the estimates.
4.8.1 Prevention and Protection Measures
Preventive measures reduce the probability of an accidental release from
a process or storage facility by increasing the reliability of both process
systems operations and equipment. AlonR with an increase in the reliability
of a system is en increase in the capital and annual costs associated with
incorporating prevention and protection measures into *> system. Table 4-5
presents costs for some of the major design, equipment, and operational
measures applicable to the primary hazards identified in Table 4-4 for the
ammonia applications in the SCAQKD.
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TABLE 4-4. EXAMPLES OF MAJOR PREVENTION AND PROTECTION MEASURES
FOR AMMONIA RELEASES
Hazard Area
Prevent ion/Protect ion
Ammonia flow
control
Temperature sensing
and cooling medium
flow control
Temperature sensing
and heating iceJi.ua
flow control
Overpressure
Reuundant flow control locps;
Minimal overdesign of feed systems
Redundant temperature sensors;
Interlock flow switch to shut off
ammonia feed on loss of cooling, with
relief venting to emergency scrubber
system
Redanda.it teaperature sensors;
Interlock flow switch to shut off
ammoria feed on loss of heating, with
relief venting to energency scrubber
system
Redundant pressure relief; not
isolatable; adequate size; discharge
not restricted
Corrosion
Reactor and reboiler
temperatures
Overfilling
Atmospheric -eleases
from relief discharges
Storage tank or line
rupture
Increased monitoring with more
frequent inspections; ii3e of corrosion
coupons; visual inspections;
non-destructive testing
Redundant temperature sensing and
alarms
Redundant level sensing, alarms
and interlocKs; training of
operators
Emergency vent scrubber system
Diking; foams; dilution;
neutralization; water sprays;
enclosure vented to emergency
scrubber system
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TABLE 4-5. ESTIMATES TYPICAL COSTS OP MAJOR PRSVEtTIOM AJO
PROTECTION MEASURES FOR AMMONIA RFLEASt"
Proven tiort/Protect ion Measure
Capital Coat
(1986 S)
Annuil Cost
(1986 S/yr)
Picw control loop
4.000-6,COO
500-750
Tcaper&ture oenaoc
250-400
30-50
Projflure rcliof
- relief vaivo
1.000-2.000
120-250
- rupture disk
1.000-1,200
120-150
Interlock systce for flow chut-oft
1.500-2,000
175-250
Alara eyotea
250-500
30-75
Lovol sensor
- liquid level gaugo
1,500-2,000
175-250
- Load cell
10.000-15. M0
1.303-1,900
Phynrnl barriers
curbing
750-1.000
in-150
- 3 ft. retaining wall
1.500-2,000
» 4
1
©
Di«iinj (baced on a 10,000 gal. tank)
- 3 ft. high
1,200-1.500
150-175
- too of tanit height, 10 ft.
7,000-7.500
««,<}- 903
r ..
Increased corronon inflection
:»-4oo
a3«sed on a 10,000 gallon fixed asaonin
xsconit stripper eyszea.
bailed on 10-20 hours 9 S20/hr.
storage tarn gystca and a
10 tons/day
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4.8.2 Levels of Control
The prevention of accidental releases relies or o coabination of techno-
logies!, sdninistrotive, and operotionol procticeo ae rhey apply to the
design, conotruction, and operation of facilities where hasordouo chreicolc
arc uoed and atored. At e oiricua, equipoent and procedures should be in
accordance with applicable codes, standards, ond regulations; however, addi-
tional measures can be token to provide extra protection against an accidental
release.
The levels of control concept provides a teens of assigning coots to
increased levels of prevention and protection. The oinintci level is referred
to as the "Baielinu" eysteo, vhich consists of the eleoente requited for
noreal safe operation and basic prevention of an accidental release of harard-
oua tectorial.
The second level of control to "Level I," which ir.cli.deo the baseline
syaten with added nodiiications, such as icprcved oaterialo of construction,
additional controls, ond generally core extensive release prevention ceaaures.
The costs associated with this level tre higher than the baseline oystec
cost A.
The third level of control is "Level 2". Thia syateo incorporates both
tho "Baseline" and "Level I" syetees with additional notifications designed
specifically for the prevention of an occidental release, such as olaro and
interlock systems. The e*tra accidental release prevention censures incorpo-
rated into "Level 2" are reflected in ire cost, which ic ouch higher than that
of the baseline sycteo.
When coopering the costs of the various levels of control, it ia ltpor-
tait to realise that higher costs do not necessarily mply icprcved safety.
The eeaeuies applied auet be applied correctly. Inappropriate ecdificariens
or add-on6 Bay not cak«r a systea refer. Each added control option increases
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the coeplexity of a cyatea. In soae coses the hazards associated vith the
Increased cosplexity say outweigh the benefits derived froa the particular
control option. Proper design and construction along with proper operational
practices ore needed to ssoure safe operation.
The:.? estioates ore for illustrative purposes only. It is doubtful that
any specific installation would find all of the control optima listed in
these trbles appropriate. An actual systes is likely to incorporate some
itess frots each af the levels of control and also soae control options rot
listed here. The purpose of these estimates is to illustrate the relationship
between cost and control, not to provide /in e<;uipeent check list.
Levels of ccntiol cost estisatea were prepared for o 25-ton fixed aeoonia
atorege tonk systee with a 10.000 gal capacity and a waste water tr»-otnent
aaaonia stripper systect vith a 10 tans/day aa&onis recovery rate. Th»ce
eysteoic are representative of storage and process facilities that eight be
found in (he SCAQfO.
4.8.3 Cogt Sugaanm
Table 4-6 eiuneoriiec tho total capital and annual cocrs for each of the
three levels of controls for the docoma storage cyotec and the acjsonia
stripper cysteo. The coots prescr:ed correspond to iSe sysrc&s described in
Tableo 4-7 end 4-8. Each of the level cotio includo the coat of the basic
systes plus any added control*. Specific cost inforuation ortd breakdown for
eoch level of control for both tlie storage and process facilities are present-
ed in Tablea 4-9 through 4-14.
4.0.4 Equiiognt ?ppc) Ileal icna jnd Di'tailtn) Costa
Equipoont specifications and details ot the copital cost estimates for
the sEcumi storage and the asaonia stripper systecs are presented in Tsbles
4-1S through 4-22.
-------
TABLE 4-6. SUMMARY COST ESTIMATES OF POTENTIAL LEVELS OP CONTROLS
FOR AMMONIA STORAGE TAtK AND STRIPPER
Total
Total
Level of
Capital Cost
Annual Cos:
Systea
Control
(1936 S)
(1986 S/yr)
Annonia Storage Tank;
Baooline
215.000
26.000
25 ton Fixed Aaaonia
Tank with 10.000 gal.
Level #1
553.000
65.000
Capacity
Level 02
1.254,000
146.000
Waste Water Treatment Aaeonia
Baselino
430.000
5 r<.000
Stripper with 10 tona/day
Aaaonia Recovery
Level 91
943.000
120.000
Level #2
1.760.000
197.000
76
-------
TABLE 4-7. EXAMPLE OF LEVELS OF CONTROL FOR AKHONIA STORAGE TANK
Proceco: 23 ton fixed aamcnia otorsge conk
10,000 gal
Cont rols
Baeeline
Level No. 1
Level No. 2
Proceoc:
Flov:
Teoperoture:
None
None
Single check- Add oecond check
valve on tank- valve,
process feed line.
None
None
None
Add a reduced-presGure
device8 with internal
sir gap ond relief
vent to containaent
tank or scrubber.
Add teoperoture
indicator.
Preocure:
Quantlty:
Single pressure
relief valve,
vent to atnoe-
phere. Provide
1ocal preocure
indicator.
Local level
indicator.
Add oecond relief
valve, secure
non-iuolatable.
Vent to lieited
ccrubber.
Add remote level
indicator.
Add rupture dicks
under relief velvet.
Provide local preoeure
indication on space
between ditik and
valve.
Add level olara. Add
high-low level inter-
lock ohul-off for both
inlet and outlet
1 ines.
locotion:
Kotetiols of
Construct ion:
Veeeel:
Away f roa
r rof f ic .
Carbon steel
Tank preocure
opeci£icetion:
250 psi£.
Away froo ttaffic
and flasnabiea.
Carbon oteel with
increased corrosion
allowances. (1/3
inch)
Tank pressure
6pecif tcat 1 on:
3G0 peig.
Away froo traffic,
flaxmableo. and other
haierdoua processes.
Type 316 SS.
Tank preacure
specif ication:
375 P«ig-
(Cont mued)
A reduced preoeure device is a codified double check valve.
77
-------
TABLE 4-7 (Continued}
Process; 25 ton fixed ecusonia storage tank
10.000 6al
Controls Baseline Level No. 1 Level No. 2
Pipirg:
Freceec
Machinery:
fnclccuret:
Diking:
Scrubbers:
Kit i&aticn:
Schedule 40
ceibon eteel.
Schedule 60
carbon eteel.
Centrifugal puop. Centrifugal puap,
carbon creel. 316 SS coMtruc-
oruf I ing box
oenl.
None
None
More
Kcrc
tion, double cap-
acity Bfcharscol
eeol •
Steel building.
3 ft, high.
Water ecrubber.
Water sprayu.
Schedule 60 Type 316
eteinless eteei.
Magnet ical)y-coupled
centrifugal ps-ep.
316 SS, construction.
Conciete tuiidirg.
Top of tark height.
10 ft.
Saoe
?ace
78
-------
TABLE 4-8. EXAMPLE OP LEVELS OF CONTROL FOR AMMONIA STRIPPER
Process: Waste Water Treatment
Baeio: 10 tono/doy a-ssorio recovery plant
Controle
Bacelino
Level No. 1
Level No. 2
Process:
Tenperature:
Adequate temp-
erature and
flow control.
Provide loct'l
temperature
cont rol.
Enhanced tespera-
ture and flov
control.
Coeputer control of
process. Use of
interlock eysteoe.
Arid redundant Add coeputer control,
tensperature censors Add teeipererure switch
Add
ord olflrroo
remote teopera-
ture indicator.
end Lack-up cooling
eyet en.
Pressure:
Provide locol
preseuro control.
Single pressure
relief valve.
Vent to atmos-
phere.
Add redundant
pressure sensors.
Add second relief
valve. Vent to
limited ocrubber.
Add coeputer control.
Add rupture dickB
under relief valves
and provide local and
reoote preeeure indi-
cator on space betwfen
d:sk and valve.
Plow:
Provide local
flov control on
stripper feed
and hearing
mediuo to re-
bo i ler.
Add redundant flow
control loops.
Add cooputer control.
Add interlock flow
cvitch to chut off
feed on loco of cool-
ing cedius.
Quantity: None Norte
Mixing: None None
Corrooion: Visual inopec- Sane
t ions.
None
None
Sane
Cospooit i on:
Knrerials of
Const ruction:
None
Carbon steel.
None
Catbor. steel wiih
added corrosion
allowance.
None
T;'pe 316 stainless
et "el.
(Continued)
79
-------
TABLE 4-8 (Continued)
?rococo: Waste Water Treatment
Baois: 10 tona/day aeusonia Recovery Plant
Controls
Baselino
Level No. 1
Level No. 2
Vessel:
Piping:
Procecs
Machinery:
Protective
Bart ier6:
Scrubbers:
Hitigat icn:
Pressure speci-
fication:
250 psig.
Schedule 40
carbon cteel.
Centrifugal
pump, carbon
Bteel conatruc-
tion, stuffing
box.
Hone
None
Hone
Pressure opecifi-
cation: 200 paig.
Schedule 80 car-
bon bteel.
Centrifugal pump.
Type 316 ctainleso
Pressure specifica-
tion: 375 psig.
Schedule 80 Type
316 atainlecc
steel.
Magnet ically-coupl ed
centrifugal punp.
steel constructicn. Type 316 atainleoo
double capacity steel conatruction,
eechanical seal.
Curbing around
stripper.
Water cciubber.
Water cproyu.
3 ft. high retaining
ual 1.
Face
Same
80
-------
TABLE 4-9. ESTIMATED TYPICAL CAPITAL AHJ ANNUAL COSTS ASSOCIATED
WITH BASELINE AMMONIA STORAGE SYSTEM
Capital Coot
(1986 $)
Annual Cost
(1986 S/yr/
Vessels:
Storage Tank 166.000
Piping and Valves:
Pipework 4,500
Check Valve 5 20
Ball Valves (5) 3,200
Excess Flow Valves (2) 950
Angle Valves (2) 3,600
Relief Valve 2.000
ProceGB Machinery:
Ctrr.t rifugal Pump 10.000
Instrumentation:
PreoBire Cauges (4) 1,500
Liquid Level Cauge 1,500
Procedures ond Trocticos:
Visual Tank Inspection (external)
Visual Tank Inspection (internal)
Relief Volve Inspection
Piping Inspection
Piping Maintenance
Valve Inspection
Valve Maintenance
22,000
520
60
370
110
•'.20
230
1,200
170
170
15
60
15
30C
120
30
350
"otal Costs
215.000
26,000
81
-------
TABLE 4-10. ESTIMATED TYPICAL CAPITAL. AND ANNUAL COSTS ASSOCIATED
WITH LEVEL 1 AMMONIA STORAGE SYSTEM
Capital Cost
(1986 $)
Annual Cost
(1986 S/yr)
Vessels:
Storage Tank
Piping and Valves:
Pipework
Check Valve
Ball Valves (5)
Excess Flow Valves (2)
Angle Valves (2)
Reli*f Valves (2)
Process Machinery:
Centrifugal Pimp
Inst nimenta r ion:
Pressure Gauges (4)
Flow Indicator
Load 1
Reaote Level Tndicator
Enclosures:
Steel Building
Scrubbers:
Hater Scrubber
Diking:
3 ft
220.000
12.000
1,100
3.200
950
3.600
4.000
20.000
t.500
"*.700
1.500
l.?90
10.000
268.000
1,300
26.000
1,300
120
370
110
420
460
2.300
170
4in
I'O
220
1,200
31,000
160
(Continued)
82
-------
TABLE 4-10 (Continued)
Capital Cost Annual Cost
(1986 $) (1986 S/yr)
Procedures and Practices:
Visual Tank Inspection (external) 15
Visual Tank Inspection (internal) 60
Relief Valve Inspection 20
Piping Inspection 300
Piping Maintenance 120
Valve Inspection 35
Valve Maintenance 400
Total Costs 553.000 65.000
83
-------
TABLE 4-11. ESTIMATED TYPICAL CAPITAL AND ANNUAL COSTS ASSOCIATED
WITH LEVEL 2 AMMONIA STORAGE SYSTEM
-1 1
Capital Cost Ar.nual Cost
(1986 S) (1986 $/yr)
Vessels:
Storage Tank
Piping and Valves:
Pipework
Reduced Pressure Device
Ball Valves (5)
Excess Flow Valves (2)
Angle Valves (2)
Relief Valves (2)
Rupture Disks (2)
Process Machinery:
Centrifugal Pump
Instrumentation:
Temperature Indicator
Pressure Cauges (6}
Flow Indicator
Load Cell
Remote Level Indicator
Level Alarm
High-Low Level Shutoff
Enclosures:
Concrete Building
Scrubbers:
Alkaline Scrubber
Diking:
10 ft High Conc~ete Dike
87/,000
6.000
2.700
3,200
950
3.600
4.000
1.100
32.000
2.200
2.200
3.700
16,000
1. 900
740
1.900
19.000
268.000
7,600
102.000
680
310
370
110
420
460
130
3,700
260
260
430
1.800
220
90
220
2,200
31,000
870
(Continued)
84
-------
TABLE 4-11 (Continued)
Capital Cost Annual Cost
(1986 $) (1986 $/yr)
Procedures end Practices:
Visual Tank. Inspection (external) 15
Visual Tank Inspection (internal) 60
Relief Valve Inspection 50
Piping Inspection 300
Piping Maintenance 120
Valve Infection 35
Valve Maintenance ^00
Total Coots 1,254,000 146,000
85
-------
TABLE 4-12. ESTIMATED TYPICAL CAPITAL AJ® ANNUAL COSTS ASSOCIATED WITH
BASELINE WAST^ WATER TREATMENT AMMONIA STRIPPER
Capital Cost Annual Cone
(1996 SJ (1936 S/yr)
Equipaenc:
Veaselc and Machinery:
Stripping Column
Reboiler and Condenser
Centrifugal Pumps (3)
Total Vessels and Machiner,* 260,000 31,000
Piping and Valvos: 117,000 14,000
Inatruoentation:3 53,000 6,000
Maintenance and Inspectiona:a 3,000
Total Costs 430,000 59,000
3
Coats are based on using c factors froa Petcra and Tismcrhaus (45) and a
total fixed capital *^ct oi $1.8 aillion (1°86 bacia) (13) for a 10 cons/day
amaonia recovery plant.
P6
-------
TABLE 4-13. ESTIMATED TYPICAL CAPITAL AND ANNUAL COSTS ASSOCIATED WITH
LEVEL 1 WASTE WATER TREATMENT AMMONIA STRIPPER
Capital Cost Annual Cost
(1986 $) (1986 $/yr)
Equipment:
Vessels and Machinery;
Stripping Column
Reboiler and Condenser
Centrifugal Pumps (3)
Total Vessels ar.J Machinery3 470,000 56.000
Piping and Valves:3 147,000 17,000
Relief Valve 2,000 240
Instrumentation:3 53,000 6,000
Temperature Sensor 360 45
Temperature Alarm 360 45
Remote Temperature Indicator 1,800 220
Remote Pressure Indicator 1,800 220
Flow Control Loops (2) 11,000 1,300
Diking:
Curbing Around Reactor 1,200 150
Scrubber:
Water Scrubber 260,000 31,000
Maintenance and Inspections:3 8.000
Relief Valve Inspection 15
Total Costs 948,000 120,000
aCos;s are based on using cost factors from Peters and Timaierhaus (45) and a
total fixed capital cost of $1.8 million (1986 basis) (13) for a 10 tons/day
ammonia recovery plant.
87
-------
Table 4-14. ESTIMATED TYPICAL CAPITAL AND ANNUAL COSTS ASSOCIATED WITH
LEVEL 2 WASTE WATER TREATMENT AMMONIA STRIPPER
Capital Cost Annual Cost
(1986 $) (1986 $/yr)
Equipment:
Vessels and Machinery:
Stripping Column
Reboiler and Condenser
Centrifugal Pumps (3)
Total Vessels and Machinerya 1,049,000 126.00C
Piping and Valves3: 167,000 20,000
Relief Valve (2) 7,400 880
Rupture Disk (2) 2,300 280
Instrumentation3: 53,000 6,400
Temperature Sensor 360 45
Temperature Alarm 360 45
Temperature Switch 540 65
Remote Temperature Indicator 1,800 220
Remote Pressure Indicator 1,800 220
Flow Control Loops (2) 11,000 1,300
Flow Interlock System 1,800 220
All Loops on Computer Control 201,000 2,400
Diking:
3 ft. High Retaining Wall 3,000 360
Scrubber:
Water Scrubber 260,000 31,000
Maintenance and Inspections : 8,000
Relief Valve Inspection 25
Total Costs 1.760.0C0 197,000
a
b
Costs are based on using cost factors from Peters and Timmerhaus (45) and a
total fixed capital cost of $1.8 million (1986 basis) (13) for a 10 tons/day
ammonia recovery plant.
Computer control costs are determined using cost estimating factors from
Valle-Riestra (46).
88
-------
TAjLE 4-15. EQUIPMENT SPECIFICATIONS ASSOCIATED WITH AMMONIA STORAGE SYSTEM
Equipment Item
Equipment Specifications
Reference
VESSELS:
Storage Tank
PIPING AND VALVES:
Pipework
Check Valve
Ball Valve
Excess Flow
Angle Valve
Relief Valve
Reduced Pres-
cure Valve
Rapture Disk
Baseline: 10,000 gal Carbon Steel
Storage Tank. 250 psig
rating
Level #1: 10,000 gal Carbon Steel with
1/8 in. Corrosion Protection,
300 psig
Level 02: 10,000 gal Type 316 Stainless
Steel, 375 psig rating
Baseline: 4 in. Schedule AO Carbon Steel
Level #1: 4 in. Schedule 80 Carbon Steel
Level {2: 4 in. Schedule 80 Type 316
Stainless Steel, 100 ft. in
Length
4 in. Vertical Lift Check Valve, Carbon
Steel Construction
4 In. Class 300, Carbon Steel Body,
Monel® Ball and Trim
4 in. Standard Valve
4 in. Carbon Steel Construction
2 in. x 3 in. Class 300 Inlet and
Outlet Flange, Angle Body, Closed
Bonnet with Screwed Cap, Carbon Steel
Body
Double Check Valve Type Service with
Internal Air Gap and Relief Valve
2 in. Monel® Disk and Carbon Steel
Holder
45,47,48.49
50
47.51
45.47.51
47
52
47
45
48,53,54
PROCESS MACHINERY:
Centrifugal Pump
Baseline: Single Stage, Carbon Steel
Construction, Stuffing Box 47,55
Level 1: Single Stage, '-Type 316 Stainless
Steel Construction, Double
Mechanical Seal 47.55
Level 2: Type 316 Stainless Steel Con-
struction, Magnetically-
coupled 47,55
(Continued)
89
-------
TABLE 4-15 (Continued)
Equipment Item
Equipment Specifications
Reference
INSTRUMENTATION:
Pressure Gauge
Liquid Level
Cauge
Temperature
Indicator
Flow Indicator
Level Indicator
Load Cell
High-lov Level
Shutoff
Diaphragm Sealed, Hastelloy C Diaphragm.
0-1.000 psi
Differential Pressure Type
Thermocouple, Thermovell, Electronic
Indicator
Differential Pressure Cell and Transmitter
and Associated Flowmeter
Differer*-.ie1 Pressure Type Indicator
Electronic Load Cell
Solenoid Valve, Switch, and Relay System
45,56
45,47,56
45,47
45.47.56
45.56.57
45.47.56
ENCLOSURE:
Building
SCRUBBER:
DIKING:
Level fll: 26-Gauge Steel Walls and Roof.
Door, Vent illation System 52
Level 02: 10 in. Concrete VCalls,
26-Gauge Steel Roof 59
Level fll and 2: Spray Tower, Monel® Con-
struction. 4 ft. x 12 ft.,
Water Sprays
Level fll: 6 in. Concrete Kails,
3 ft. high 5 2
Level 92: 10 in. Concrete Walls, Top of
Tank Height
90
-------
TABLE 4-16. MATERIAL AND LABOR COSTS ASSOCIATED WITH BASELINE AMMONIA STORAGE SYSTEM
Materials Labor Direct Indirect Capital
Cost Cost Costs Costs Cost
(1986 $)
VeeGels:
Storage Tank 86,000 39,000 125,000 44,000 166,000
Piping and Valves:
Pipework 90u 2,100 3.000 1.100 4,500
Check Valves 320 30 350 120 520
Ball Valves (5) 2,000 150 2,150 750 3,200
Excess Flow Valves (2) 600 40 640 220 950
Angle Valves (2) 2,400 40 2,440 860 3,600
Relief Valve 1,300 50 1,330 460 2,000
Proceus Machinery:
Centrifugal Pump 4,900 2,100 7,000 2,500 11,000
Inst rumentat ion :
Pressure Gauges (4) BOO 200 1,000 350 1,500
Liquid Level Gauge 800 200 1.000 350 1,500
Total Costs 100,000 44,000 144,000 50,000 215,000
-------
TABLE 4-17. MATERIAL AND LABOR COSTS ASSOCIATED WITH LEVEL 1 AMMONIA STORAGE SYSTEM
Materials Labor Direct Indirect Capital
Cost Cos t Costs Costs Cost
(1986 $)
Vessels:
Storage Tank 102,000
Piping and Valves:
Pipework 5,300
Check Valves 640
Ball Valves (5) 2,000
Excess Flow Valves (2) 600
Angle Valves (2) 2.400
Relief Valve (2) 2,600
Process Machinery:
Centrifugal Pump 9,300
Instrumentation:
Pressure Gauges (4) 800
Flow Indicator 2,000
Liquid Level Gauge 800
Remote Level Indicator 1,000
46,000
2,500
60
150
40
40
100
4,000
200
500
200
250
143,000
7,800
700
2,150
640
2,400
2,660
13,300
1,000
2.500
1,000
1.250
5 2,000
2,700
250
750
220
860
920
4,700
350
880
350
440
220.000
12,000
1.100
3.200
950
3.600
4.000
20,000
1.500
3.700
1.500
1. 900
Enclosures:
Steel Building 4,600
Scrubbers:
Water Scrubber 125,000
Diking;
3 ft. High Concrete
Diking 3 90
2,300
5 20
6, 900
56,000 181,000
910
2.400
63.000
320
10.000
268,000
1.300
Total Costs
25 9,000
113.000
372.000
130,000
553.000
-------
TABLE A-18. MATERIAL AND LABOR COSTS ASSOCIATED WITH LEVEL 2 AMMONIA STORAGE SYSTEM
Materials Labor Direct Indirect Capital
Cost Cost Costs Costs Cost
CI 986 $)
Vessels:
Storage Tank 407,000 183.000 590.000 207,000
Piping and Valves:
Pipework 1,400 2.600 4,000 1,400
Reduced Pres. Device 1,600 200 1.800 630
Ball Valves (5) 2,000 150 2,150 750
Excess Flow Valves (2) 600 40 640 220
Angle Valves (2) 2,400 40 2.440 860
Relief Valve (2) 2.600 100 2.660 920
Rupture Disks (2) 650 75 725 250
Process Machinery:
Centrifugal Pump 15.000 6.400 21.400 7,500
Instrumentat ion;
Temperature Indicacoi 1,200 300 1,500 530
Pressure Gauges (6) 1,200 300 1,500 530
Flow Indicsior 2,000 500 2.500 880
Load Cell 8,400 2.100 10.500 3.700
Remote Level Indicator 1,000 250 1,250 440
Level Alarm 400 100 500 180
High-Low Level Shutoff 1,000 250 1.250 440
Enclosures;
Concrete Building 6,100 6,600 12,700 4,500
Scrubbers:
Water Scrubber 125,000 56.000 181.000 63.000
Diking:
13 ft. High Concrete
Dike 2.200 2.850 5.000 1.800
877.000
6.000
2.700
3.200
950
3.600
4.000
1.100
32.000
2.200
2,200
3.700
16.000
1. 900
740
I, 900
19.000
268,000
7.400
Total Costs
582,000
262,000
844,000
295,000
1,254.000
-------
TABLE 4-19. EQUIPMENT 5PECIFICATIONS ASSOCIATED WITH WASTE WATER
TREATMENT AMMONIA STRIPPING PROCESS
Equipment Item
Equipment Specification
Reference
VESS7LS AND MACHINERY:
PIPING AND VALVES:
Pipework
Relief Valve
Rupture Disk
Ammonia Stripper and Associated Re-
boiler and Condenser as Defined in
Reference
13
Baseline: 4 in. Schedule AO Carbon
Steel. 360 ft. 50
Level 01: Schedule 80 Carbon Steel
Level 0 2: Schedule 80 Type 316
Stainless Steel
2 in. x 3 in. Class 300 Inlet and
Outlet Flanges, Angle Body. Closed
Bonnet with Screwed Cap, Carbon
Steel Body 47
2 in. Monel® Disk and Carbon Steel
Holder 48,53,54
INSTRUMENTATION:
Temp. Sensor
Thermocouple and Associated Thermowell
45,47,56
Temp. Alarm
Indicating and Audible Alaro
47.52,58
Temp. Switch
Two-Stage Swiroh with Independently
Set Actuation
45,56
Remote Temp.
Transmitter and Associated Electronic
Indicator
Indicator
45.56
Remote Press.
Transducer, Transmitter and Electronic
Indicat or
Indicator
45,56
Flow Control Loop
4 in. Globe ControJ Valve, Flowmeter
and PID Controller
45.56
Flow Interlock
Solenoid Valve, Switch, and Relay
System
System
45.47,52.56
DIKING:
SCRUBBER:
Level 31: 6 in. High Concrete
Curbing 52
Level £12: 3 ft. High Concrete
Retaining Wall
Level tfl and 0 2: Spray Tower, Monel*
Construction 4 ft. x 12 ft..
Water Sprays 59
94
-------
TABLE 4-20. MATERIAL AND LABOR COSTS ASSOCIATED WITH BASELINE WASTE WATER
TREATMENT AMMONIA STRIPPER
Materials Labor Direct Indirect Capital
Cost Cost Costa Costs Cost
(1986 $)
Equipment:
Vessels and Machinery:
Stripping column
Reboiler and Condenser
Centrifugal Pumps (3)
Total Vessels and Mach.a 125.000 56,000 181.000 45,000 260.000
Piping and Valves:8 45.000 37.000 82.000 20,000 117.000
Instrumentation:41 28,000 9.000 37.000 9,000 53.000
Total Costs 198,000 102.000 300.000 74.000 430,000
Costs are based on using cost factors from Peters and Timmerhaus (45) and a total fixed
capital cost of $1.8 million (19S6 basis) (13) for a 10 tons/day ammonia recovery plant.
-------
TABLE 4-21. MATERIAL AND LABOR COSTS ASSOCIATED WITH LEVEL 1 WASTE WATER
TREATMENT AMMONIA STRIPPER
Materials Labor Direct Indirect Capital
Cost Cost Costs Costs Cost
(1986 $)
Equipment:
Vessels and Machinery:
Stripping column
Reboiler and Condenser
Centrifugal Pump3 (3)
Total Vessels and Mach.a 226.000
101.000
327.000
82.000
470.000
Piping and Valves:0 77,000
25,000
102.000
25.000
147,000
Relief Valve 1,300
50
1.350
340
2.000
Instrumentation:3 28.000
9.000
37.000
9.000
53.000
Temperature Sensor 200
50
250
p0
360
Temperature Alans 200
50
250
60
160
Remote Temperature Indicator 1,000
250
1.250
310
1,800
(Continued)
0
Costs are based on using cost factors from
capital cost of $1.8 million (1986 basis)
Peters and
(13) for a
Titnmerhaus
10 tons/day
(45) and a total
ammonia recovery
fixed
plant.
-------
TABLF 4-21 (Continued)
Remote Press. Indicator
Flou Control Loops (2)
Diking:
Curbing Around Reactor
Scrubber:
Water Scrubber
Materials Labor Direct Indirect Capital
Cost Cost Costs Costs Cost
(1986 $)
1,000 250 1.250 310 1.800
6.000 1.500 7.500 1.900 11.000
500 350 850 210 1.200
125,000 56.000 181.000 45.000 260.000
Total Costs
466,000 194.000 660.000
164.000
948.000
-------
TABLE 4-22. MATERIAL AJ.T) LABOR COSTS ASSOCIATED WITH LEVEL 2 WASTE WATER
TREATMENT AMMONIA STRIPPER
Materials Labor Direct Indirect Capital
Cost Cor.c Costs Costs Cost
(1986 $)
Equipment:
Vessels and M^chinety:
Stripping coluan
Reboiier and Condenser
Centrifugal Pumps (J)
Total Vessels and Hach.
504.000
226,000
730.000
182.000
1,049.000
Piping and Valves:3
87.000
2 9.000
116.000
29.000
167.000
Roliof Valvo (2)
5.000
100
5.100
1.300
7.400
Huptu¦o Otuk (2)
1. 500
100
1,600
400
2,300
Inst rumentacion:a
28.000
9.000
37.000
9.000
53.000
Temperature Sensor
200
50
250
60
360
Temperature A!ana
200
50
250
60
360
(Continued)
aCosto are based on using cost factors fioa Peters and Timn«»rhaU3 (45) and a total fixed
capital cost of $1.8 million (1936 bagii>) (13) for a 10 tons/day aamonia recovery plant.
-------
TABLE 4-22 (Continued)
Materials
Cos t
Labor
Cost
Direct
Costs
Indirect
Costs
Japital
Cost
(1986 $)
Temperature Switch
300
75
375
95
540
Remoto Temperature Indicator
1.000
250
1.250
310
1,800
Remote Pressure Indicator
1,000
250
1.250
310
1.800
Flow control Loops (2)
6,000
1.500
7.500
1. 900
11.000
Flow Interlock System
1,000
250
1.250
310
1,800
All Loops^on Computer
Control
105,000
35.000
140.000
35,000
201,000
Diking:
3ft. high retaining
wall
900
1.200
2.100
530
3,000
Scrubber:
Water Scrubber
125.000
56.000
181.000
45,000
260.000
Total Costs
866,000
35 9,000
1.225.000
305,000
1,760,000
^Computer control costs are determined using cost estimating factors from Valle-Riestra.
(46).
-------
A.8.5 Methodology
Format for Presenting Cost Estimates—
Tables are provided for control schemes associated with storage and pro-
cess facilities for ammonia shoving capital, operating, and total annual
costs. Th«» tables are broken down into subsections comprising vessels, piping
and valves, process machinery, instrumentation, and procedures and practice.
Presenting the co6ts in this manner allows for easy comparison of costs for
specific items, different levels, and different systems.
Capital Cost—All capital costs presented in this report are shown as
total fixed capital costs. Table 4-23 defines the cost elements comprising
total fixed capital as it is used here.
The computation of total fixed capital, as shown in Table 4-23, begins
with the total direct cost for the system under consideration. This total
direct cost is the total direct installed cost of all capital equipment
comprising the system. Depending on the specific equipment item involved, the
direct capital cost was available or was derived from uninstalled equipment
costs by computing costs of installation separately. To obtain the total
fixed capital cost, other costs obtained by using factors are added to the
total direct costs.
The first group of other cost elements is indirect costs. These include
engineering and supervision, construction expenses, and various other expenses
such as administration expenses. These co6ts are computed by multiplying
total direct costs by a factor shown in Table 4-23. The factor is approxi-
mate, is obtained from the cost literature, and is based on previous experi-
ence with capital projects of a similar nature. Factors can have a range cf
values and vary according to technology area and for individual technologies
within an area. Appropriate factors based on judgement and experience were
selected for this report.
100
-------
TABLE 4-23. FORMAT FOR TOTAL FIXED CAPITAL
COST
Item No.
Item
Cost
1
Total Material Cost
-
2
Total Labor Cost
-
3
Total Direct Cost
Iteas 1+2
A
Indirect Cost Items (Engineering
& Construction Expenses)
0.35 x Item 3°
5
Total Bare Module Co6t
Iteas (3 + 4)
b
Contingency
(0.05 x Item 5)^
7
Contractor's Fee
0.05 x Item 5
8
Total Fixed Capital Cost
Items (5+6+7)
3
For storage facilities, the indirect cost factor is 0.35. For process
facilities, the indirect cost factor is 0.25.
^For storage facilities, the contingency cost factor is 0.05. For process
facilities, the contingency cost facte- is 0.10.
101
-------
When the indirect costs are added to the total direct costs, total bare
module cost is obtained. Some additional cost elements, such as contractor's
fee and contingency, are calculated by applying and adding appropriate factors
to the total bare module cost, as shown in Table 4-23, to obtain the total
fixed capital cost.
Annual Cost—Annual costs are obtained for each equipment item by apply-
ing a factor for both capital recovery and for maintenance expenses to the
direct cost of each equipment item. Table 4-24 defines the cost elements and
the appropriate facto-s cooprising these costs. Additional annual costs are
incurred for procedural items such ae valve and vessel inspections, for
example. The sun of these individual costs equals the total annual cost.
Sources of Information—
Costs presented in this report are derived from cost information in
existing published sources and also from recent vendor information. The
objective of this effort vas to present cost levels for ammonia process and
storage facilities using the best costs for available sources. The primary
sources of cost information are Peters and Timmerhaus (45), Chemical Engineer-
ing (60), and Valle-Riestra (46) supplemented by other sources and references
where necessary. Adjustments were made to update all costs to a June 1986
dollar basis. For some equipment items, vell-docucented costs were not
available and they had to be developed from component costs.
Costs in this document reflect the "typical" or "average" representation
for specific equipment iteas. This restricts the use of data in this report
to:
• Preliminary estimates used for policy planning;
• Comparison of relative costs of different levels or systems;
and
102
-------
TABLE 4-24. FORMAT FOR TOTAL ANNUAL
COST
Item No.
Item
Cost
1
Total Direct Cost
-
2
Capital Recovery on Equipment
Items
0.163 x Item 1
3
Maintenance Expense on Equipment
Items
0.01 x Item 1
4
Total Procedural Items
-
5
Total Annual Cost
Items (2+3+4)
103
-------
• Approximations of costs that might be incurred for a specific
application.
The costs in this report are considered to be "order of magnitude" with a
+50 percent margin. This is because costs are based on preliminary estimates
and many are updated from literature sources. Large departures from the
design basis of a particular system presented in this manual or the advent of
a different technology might cause the system cost co vary more than this. If
used as intended, however, this document will provide a reasonable source of
preliminary cost information for the facilities covered.
When comparing costs in this manual to those from other references, the
user should be sure the design bases are comparable and that the capital and
annual costs as defined here are the same.
Cost Updating—
All costs in this report are expressed in June 1986 dollars. Costs
reported in the literature were updated using cost indices for materials and
labor.
Costs expressed in base-year dollars may be adjusted to dollars for
another year by applying co6t indices as shown in the following equation:
. , . . _ new base year index
new base-year cost = old base-year cost x . . . 1 r.—
1 3 old base year index
The Chemical Engineering (CE) Plant Cost Index was used to update costs for
this report. For June 1986, the index is 316.3.
Equipment Costs—
Most of the equipment costs presented in this manual were obtained
directly from literature sources of vendor information enr*. correspond to a
specific design standard. Special cost estimating techniques, however, were
104
-------
used in determining the costs associated with vessels, piping systems, scrub-
bers, diking, and enclosures. The techniques used are presented in the
following subsections of this manual.
Vessels—The total purchased co6t for a vessel, as dollars per pound of
weight of fabricated unit free on board (f.o.b.). with carbon steel as the
basis (January 1979 dollars) were determined using the following equation from
Peters and Timmerhaus (45):
Cost = [50(Weight of Vessel in Pounds)-0,34][Weight of Vessel in Pounds]
The vessel weight is determired using appropriate design equations, as given
by Peters and Timmerhaus (45) that allow for wall thickness adjustments for
corrosion allowances, for example. The vessel weight is increased by a factor
of 0.15 for horizontal vessels end 0.20 for vertical vessels to account for
the added weight of nozzles, manholes, and skirts or saddles. Appropriate
factors are applied for different materials of construction, as given in
Peters and Timmerhaus (45). Vessel costs are updated using cost factors.
Finally, a shi-.ping cost amounting to 10 percent of the purchased cost is
added to obtain the delivered equipment cost.
Pipi"R—Piping costs were obtained froo cost information and data pre-
sented by Yamartino (50). A simplified approach is used in which it is
assumed that a certain length of piping containing a given number of valves,
flanges, and fittings is contained in the storage or process facility. The
data presented by Yamartino (50) permit cost determinations for various
lengths, sizes, and types of piping systems. Using these factors, a represen-
tative estimate can be obtained for ?ach ot the storage and process facili-
ties.
Diking—Diking costs were estimated using Mean's Manual (52) for rein-
forced concrete walls. The following assumptions were made to determine the
costs. The dike contains toe entire contents of .1 tank in the event of a leak
105
-------
or release. Two dike sizes are possible; a three-foot high dike, six-inches
thick and a top-of-tank height dike ten inches thick. The tanks are reieed
off the ground and are not volumetrically included in the volume enclosed by
the diking. These assumptions facilitate cost determination for any size
diking system.
Enclosures—Enclosure costs were estimated using Mean's Manual (5 2) for
both reinforced concrete and steel-walled buildings. The buildings are
assumed to enclose the same area end volume as the top-of-tank height dikes.
The concrete building is ten-inches thick with a 26-gauge steel roof and e
metal door. The steel building has 26 gaup,e roofing and siding and Betel
door. The cost of a ventilation system was ojtennined using a typical 1,000
scfm unit and doubling the cost to account for duct work and r^quirenents for
the safe enclosure of hazardous chemicals.
Scrubbers—Scrubber costs were estimated using the following equation
from the Gard (59) manual for spray towers based on the actual cubic feet per
minute of flow at a chamber velocity of 600 feet/minute.
Costs = 0.235 x (ACFM + 43.000)
A release rate of 10,000 ft^/minute was assumed for the storage vessel systems
and an appropriate rate was determined for process system based on the quanti-
ty of hazardous chemicals present in the system at any ore time. For the
3
ammonia stripper system, a release rate of 10,000 ft /minute was assumed. In
addition to the spray tower, the costs also include pumps and a storage tank
for the scrubbing medium. The costs presented aie updated to June 1986
dollars.
Installation Factors—
Installation costs were developed for all equipment items included in
both the process and storage systems. The costs include bcth the material and
labor costs for installation of a particular piece of equipment. The cost6
106
-------
were obtained directly from literature sources end vendor information or
indirectly by assuming e certain percentage of the purchased equipment cost
through the use of estimating factors obtained from Peters and Timmerhaus (45)
and Valle-Riestra (46). Table 4-25 lists the cost factors used or the refer-
ence from which the cost was obtained directly. Many of the costs obtained
from the literature were updated to June 1986 dollars using a 10 percent per
year rate of increase for labor and co6t indices ! >r materials associated with
installation.
107
-------
TABLE A-25. FORMAT FOR INSTALLATION COSTS
Equipment Item Factor or Reference
Vessels:
Storage Tank 0.45
Expansion Tank 0.25
Piping and Valves:
Pipework Ref. 50
Expansion Loop Ref. 47
Reduced Pressure Device Ref. 47
Check Valves Ref. 47
Gates Valves Ref. 47
Ball Valves Ref, 47
Excess Flow Valves Ref. 47
Angle Valves Ref. 52
Relief Valves Ref. 47
Rupture Disks Ref. 47
Process Machinery:
Centrifugal Putnp 0.43
Gear Ptuap 0.43
Inst runentation:
All Instrumentation Items 0.25
Enclosures: Ref. 52
Diking: Ref. 52
Scrubbers: 0.45
108
-------
SECTION 5
REFERENCES
1. Anhydrous Ammonia. Pamphlet G-2, 7th ed., Compressed Gas Association,
Inc., Arlington, VA, 198A.
2. South Coast Air Quality Management District, File of Questionnaires from
Toxic Chemical Industry Survey, 1985.
3. Blanken, J.M. Behavior of Ammonia in the Event of a Spill3ge. CEP
Technical Manual, Ammonia Plant Safety and Related Facilities. Volume 22.
AIChE. 1980.
A. Dean, J.A. (ed.). Lange's Handbook of Chemistry, 12th ed., McGraw-Hill
Book Co., 197 9.
5. Mark., H.F.; Othmer, D.F.j Overberger, C.G.; and Seaborg, G.T.,
Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., Volume 2, John
Wiley £» Sons, 1983.
6. Perry, R.H.. and Chilton, C.H. (eds.) Cnemical Engineers' Handbook, 5th
edition, McGraw-Hill, New York, NY, 1573.
7. Weast, R.C., (ed.) CRC Handbook of Chemistry and Physics, 56th ed. CRC
Press, 1975.
8. Safety Requirements for the Storage and Handling of Anhydrous Ammonia.
ANSI K61.1, American National Standards Institute, Inc., 1430 Broadway,
New York, NY, 1981.
9. U.S. Dept. of Health, Education, and Welfare, Criteria for a Recommended
Standard...Occupational Exposure to Ammonia. U.S. Government Printing
Office, 197A.
10. Compressed Gas Association. Ammonia (Anhydrous). In Handbook of
Compressed Gases, van Nostrand ReinhoJd Company. New York, NY. 1966.
11. Sittig, Marshall. Handbook of Toxic & Hazardous Chemicals and
Carcinogens, 2nd edition, Noyes Publications, 1&95.
12. Air Products and Chemicals, Inc., Allentown, PA. Specialty Gas Material
Safety Data Sheet. Revised February 1984.
13. Chevron Waste Water Treating Process - WWT Process. Chevron Research
Company, San Francisco, CA, 1968.
109
-------
Klett, R.J. Tieat Soar Wacer for Profit. Hydrocarbon Processing,
October 1972.
15. Slack, A.V., and James, G. R. (eds). Ammonia, Part IV, Marcel Deititer,
Inc., New York and Easel, 1979.
16. Considine, D.M. (ed.). Chemical and Process Technology Encyclopedia,
McGraw-Hill. 1974.
17. The Badger Company, Inc. Acrylonitrile (Sohio process). Hydrocarbon
Processing, November 1981.
IS. System Practices for Ammonia. In 1986 Handbook - Refrigeration Systems
and Applications, \merican Society of Heating, Refrigerating and Air
Conditioning Engineers, Inc., Atlanta, CA, 1986.
19. Telephone conversation between M. Stohs of Radian Corporation and a
representative of General Battery Corporation, Reading, PA, August 1986.
20. U.S. Patent Nc. 3,524,724.
21. U.S. Patent No. 3,473.891.
22. Lips, H.I,, Gotterba, J.A., Lin, K.J., and Waterland, L.R. Environmental
Assessment of Combustior. Modification'Controls for Stationary Internal
Combustion Engines, Final Report. EPA-600/7-81-127 (NTIS PB82-224973),
July 1981.
23. Telephone conversation between M. Stohs of Radian Corporation ard a
representative of P3&S Chemical Company. Henderson, KY, 1986.
24. AS ME Boiler and Pressure Vessel Code. ANSI/ASME BPV-VIII-1, American
Society of Mechanical Engineers, New York., MY, 1983.
25. Chemical PJar.t and Petroleum Refinery Piping. ANSI/ASME B31.3, A=ericar.
National Standards Institute, Inc., New York, NY, 1980.
26. Steel Valves. ANSI/ASME B16.5, American National Standards Institute,
Inc.. New York. NY. 1977.
27. Steel Pipe Flanges and Flanged Fittings. ANSI/ASME B16.5. American
National Standards Institute, Inc., New York, NY. 1977.
28. Recommended Rules for Design and Construction of Large Welded
Low-Pressure Storage Tanks. API Standard 620. American Petrole-a
Institute, Washington, DC. 1970.
29. Blanken, J.M. Stress Corrosion Cracking of Ammonia Storage Spheres:
Survey and Panel Discussion. CEP Technical Manual. Ammonia Plant Safety
and Related Facilities. l'oluae 24, AIChE, 1984.
110
-------
30. Lunde, L. Stress Corrosion Cracking of Sceels in Ammonia: Specially
Vapor-Phase Cracking. CEP Technical Manual, Ammonia Plant Safety and
Related Facilities, Volume 24, AIChE, 1984.
31. American National Standard for Refrigeration Piping. ANSI B31.5,
American National Standards Institute, Inc., New York, NY, 1974.
32. American National Standard for Power—Operated Pumps for Anhydrous
Ammonia and LP Gas. ANSI/UL 51. American National Standards Institute,
Inc., New York. NY, 1981.
33. Pressure Relief Device Standards - Part 3 - Compressed Gas Storage
Containers. Pamphlet S-1.3, Compressed Gas Association, Inc., Arlington,
VA, 1984.
34. Lees, F.P. Loss Prevention in the Process Industries - Hazard
Identification, Assessment, and Control, Volumes 14 2, Butterworths,
London, 1983.
35. Straitz, J.7. Hake the Flare Protect the Environment. Hydrocarbon
Processing. October 1977.
36. Federal Register. Volume 50. April 16. 1985, pp. 14,941-14,945.
37. Aarts, J.J. and D.M, Morrison. Refrigerated Storage Tank Retainment
Walls. CEP Technical Manual, Ammonia Plane Safety and Related
Facilities, Volume 23, American Institute of Chemical Engineers, New
York. NY, 1981.
38. Roberts, R.H. and S.E. Handman. Minimize Ammonia Releases, Hydrocarbon
Processing, March 1986.
39. Feind, K. Reducing Vapor Loss in Ammonia Tank Spills. CEP Technical
Manual, Ammonia Plant Safety and Related Facilities, Volume 17, American
Institute of Chemical Engineers, Hew York, NY, 1975.
40. Hiltz, R.H. and S.S. Gross. The Use of Foams to Control the Vapor Hazard
from Liquified Gas Spills. In Control of Hazardous Material Spills -
Proc. 1980 National Conference on Control of hwiardous Material Spills,
Louisville, KY, May 1980.
41. Clark, W.D. Using Fire Foam on Ammonia Spills. CEP Technical Manual,
Ammonia Plant Safety and Related Facilities, Volume 18, American
Institute of Chemical Engineers, New York, NY, 1976.
42. Hiltz, K. Parr 3 - Vapor Hazard Control. In Bennett, G.F., Feates,
F.S., and Wilder, I. Hazardous Materials Spills Handbook, McGraw-Hill,
1982.
Ill
-------
A3. Greiner, M.L. Emergency Response Procedures for Anhydrous Aaaoip.a Vapor
Release. CEP Technical Manual, Ammonia Plant Safety and Related
Facilities, Volume 24, American Institute of Chemical Engineers. I ."aw
York, NY. 1984.
44. McQuaid, J. and A.P. Roberts. Loss of Containment - Its Effects and
Control. In Developments '82 (Institution of Chemical Engineers Jubilee
Symposium), London, England, April 1982.
45. Peters, M.S. and K.D. Timmerhaus. Plant Design and Economics for
Chemical Engineers. McGraw-Hill Book Compan/, New York, NY, 1980.
46. Valle-Riestra, J.F. Project Evaluation in the Chemical Process Indus-
tries. McGraw-Hill Book Co-jpany, New York. MY, 1933.
47. Richardson Engineering Services, Inc. The Richardson Rapid Construction
Cost Estimating System, Volume l-^, San Marcos, CA, 1986.
48. Pikulik, A. and H.E. Diaz. Ccst Estimating for Major Process Equipment.
Chemical Engineering. October 10. 1977.
4 9. Hall. R.S.. J. Matley, and K.J. McNaughton. Cost of Procesc Eauipment.
Chemical Engineering, April 5, 1982.
50. Yamartimo, J. Installed Cost of Corrosion-Resistant Piping-1578.
Chemical Engineering, November 20, 1978.
51. Telephone con*ersation between J.D. Quass of Radian Corporation and a
representative of Mark Controls Corporation, Houston, TX, August 1986.
52. R.S. Means Company, Inc. Building Construction Cost Data 1986 (44ch
Edition), Kingston. MA,
53. Telephone conversation between J.D. Quaas of radian Corporation and a
representative of Zoo* Enterprises, Chagrin Falls, OH, August 1986.
54. Telephore conversation between J.D. Quass of Radian Corporation and a
representative of Fike Corporation, Houston, TX, August 1936.
55. Green. D.W. (ed.}. Perry's Chemical Engineers' Handbook (Sixth Edition).
McGraw-Hill Book Company, Hew Yortt, NY, 1934.
56. Liptak, B.G. Costs of Process Instruments. Chemical Engineering,
September 7, 1970.
57. Liptak. B.G. Costs of Viscosity, Ueight, Analytical Instruments.
Chemical Engineering, September 21, 1970.
58. Liptak, B.G. Control-Panel Costs, Process Instruments. Chemical
Engineering. October 5. 1970.
112
-------
59. Capital and Operating Costs of Selected Air Pollution Control Systems.
EPA-450/5-80-002, U.S. Environmental Protection Agency, 1980.
60. Cost indices obtained from Chemical Engineering. McGraw-Hill Publishing
Company, New York, NY, June 1974, December 1985, and August 1986.
113
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APPENDIX A
GLOSSARY
This glossary defines selected terms used in the text of this manual
which might be unfamiliar to some users or which might be used differently by
different authors.
Accidental release: The unintentional spilling, leading, pumping, purging,
emitting, emptying, discharging, escaping, dumping, or disposing of a toxic
material into the environment in a nanner that is not in compliance with a
plant's federal, state, or local environmental permits and/or results in toxic
concentrations in the air that are a potential health tnreat to tne
surrounding community.
Assessment: The process whereby the hazards which h3ve been identi.ied are
evaluated in order to provide an estimate for the level of risk.
Cavitation: The formation and collapse of vapor bubbles in a flowing liquid.
Specifically the formation and collapse of vapor cavities in a pump when there
is sufficient resistance to flow at the inlet side.
Containment/control: A system to which toxic emissions from safety relief
discharges are routed to be controlled. A caustic scrubber and/or flare can
be containment/control devices. These systems may serve the dual function of
destructing continuous process exhaust gas eaissions.
Creep failure: Failure of a piece of metal as a result of creep. Creep is
time dependent deformation as a result of stress. Metals will deform when
exposed to stress. High levels of stress can result in rapid deformation and
rapid failure. Lower levels of stress can result in slew deforaation and
protracted failure.
114
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Deadheading; Closing or nearly closing or blocking the discharge outlet or
piping of an operating pump or compressor.
Facility: A location at which a process or set of processes are used to
produce, refine or repackage chemicals, or a location where a large enough
inventory of chemicals are stored so that a significant accidental release of
a toxic chemical is possible.
Hazard: A source of danger. The potential for death, injury or other forms
of damage to life and property.
Hygroscopic: Readily absorbing and retaining moisture, usually in reference
to readily absorbing moisture from the air.
Identification: The recognition of a situation, its causes and consequences
relating to a defined potential, e.g. Hazard Identification.
Mild steel: Carbon steel containing a maximum of about 0.25% carbon. Mild
steel is satisfactory for use where severe corrodants are not encountered or
where protective coatings can be used to prevent ot reduce corrosion rates to
acceptable levels.
Mitigation: Any measure taken to reduce the severity of the adverse effects
associated with the accidental release of a hazardous chemical.
Passivation film: A layer of oxide or other chemical compound of a meral on
its surface that acts as a protective barrier against corrosion or further
chemical reaction.
Plant: A location at which a process or set of processes are used to produce,
refine, or repackage, chemicals.
115
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Prevention; Design and operating measures applied to a process to ensure that
primary containment of toxic chemicals is maintained. Primary containment
means confinement of toxic chemicals within the equipment intended for normal
operating conditions.
Primary Containment: The containment provided by the piping, vessels and
machinery used in a facility for handling chemicals under normal operating
conditions.
Probability/potential: A measure, either qualitative or quantitative, that an
event will oc;ur within some unit of time.
Process; The sequence of physical and chemical operations for the production,
refining, repackaging or storage of chemicals.
Process machinery: Process equipment, such as pumps, compressors, heaters, or
agitators, that would not be categorized as piping or vessels.
Protection: Measures taken to capture or destroy a toxic chemical that has
breached primary containment, but before an uncontrolled release to the
environment has ovcrred,
Qualitative Evaluation: Assessing the risk of an pccidental release at a
facility in relative terms; the end result of the assessment being a verbal
description of the risk.
Quantitative Evaluation: Assessing the risk of an accidental release at a
facility in numerical terms: the end result of the assessment being some type
of number reflects risk, such as faults per year or mean time between failure.
116
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Reactivity: The ability of one chemical to undergo a chemical reaction with
another chemical. Reactivity of one chemical is always measured in reference
to the potential for reaction with itself or with another chemical. A chemical
is sometimes said to be "reactive", or have high "reactivity", without
reference to another chemical. Usually this means th?t the chemical has the
ability to react with common materials such as water, or cora.rn.on materials of
construction such as carbon steel.
Redundancy: For control systeas, redundancy is the presence of a second piece
of control equipment where only one would be required. The second piece of
equipment is installed to act as a backup in the event that the primary piece
of equipment fails. Redundant equipment can be installed to backup all or
selected portions of a control system.
Risk: The probability chat a hazard may be realized at any specified level in
a given span of time.
Secondary Containment: Process equipment specifically designed to contain
materi:il that has breached priaary containment before the material is released
to the environment and becomes an accidental release. A vent duct and
scrubber that are attached to the outlet of a pressure relief device are
examples of secondary containment.
Toxicity: A measure of the adverse health effects of exposure to a chemical.
117
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TABLE B-l.
APPENDIX B
ITETRIC (SI) CONVERSION FACTORS
Quantity
To Convert From
To
Multiply By
Length:
Area:
Vol uaie:
Maes (weight):
Pressure:
Temperaruie:
Caloric Value;
Enthalpy:
Specific-Heat
Capacity:
Density:
Concentration:
Flowrate:
Velocity:
Viscosity:
in
,f5
in2
ft3
)>
gal
lb
short ton (tor)
short ton (ton)
atn
mm Hg
peia
psig
°F
°C
Btu/lb
Btu/lbmol
kcal/gnol
Btu/lb-°F
lb/ft3
lb/gal
oz/gal
quarte/gal
gel/min
ga^/doy
ft /nun
ft/nin
ft/sec
centipoise (CP)
3
m
Mg
metric ton (t)
kPa
kPa
UPa
Ir.Pa*
°C*
K*
kJ/kg
kJ/kgrol
kJ/k^mol
kJ/kg-°C
kg/nu
kg/m,
k§/m3
/m
cij/min
tn^/day
n /tnin
m/min
m/sec
kg/m-s
cd 2.54
m 0.3048
:m, 6.4516
0.0929
in, 16.39
0.0283
0.0038
0. *>536
0.9072
0.9072
101.3
0.133
6.895
(psig)+14.696)x(6.895)
(5/9)x (°F-3 2)
°C+273.15
?.3 26
2.326
4.184
4.1668
16.02
119.8
25.000
0.0038
0.0038
0.0283
0.3048
0.3048
0.001
~Calculate as indicated
118
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c
* Tiiri I *
L
w
i ¦ir-firf,
n
o
Cb,
ifV ^fn •
------- |